Air ion exposure system for plants.

PubMed

Morrow, R C; Tibbitts, T W

1987-02-01

A system was developed for subjecting plants to elevated air ion levels. This system consisted of a rectangular Plexiglas chamber lined with a Faraday cage. Air ions were generated by corona discharge from frayed stainless steel fibers placed at one end of the chamber. This source was capable of producing varying levels of either positive or negative air ions. During plant exposures, environmental conditions were controlled by operating the unit in a growth chamber.

Effects of Deepwater Horizon Oil on the Movement and Survival of Marsh Periwinkle Snails (Littoraria irrorata).

PubMed

Garner, T Ross; Hart, Michael A; Sweet, Lauren E; Bagheri, Hanna T J; Morris, Jeff; Stoeckel, James A; Roberts, Aaron P

2017-08-01

The Deepwater Horizon (DWH) oil spill resulted in the release of millions of barrels of oil into the Gulf of Mexico, and some marsh shorelines experienced heavy oiling including vegetation laid over under the weight of oil. Periwinkle snails (Littoraria irrorata) are a critical component of these impacted habitats, and population declines following oil spills, including DWH, have been documented. This study determined the effects of oil on marsh periwinkle movement and survivorship following exposure to oil. Snails were placed in chambers containing either unoiled or oiled laid over vegetation to represent a heavily impacted marsh habitat, with unoiled vertical structure at one end. In the first movement assay, snail movement to standing unoiled vegetation was significantly lower in oiled chambers (oil thickness ≈ 1 cm) compared to unoiled chambers, as the majority (∼75%) of snails in oiled habitats never reached standing unoiled vegetation after 72 h. In a second movement assay, there was no snail movement standing unoiled structure in chambers with oil thicknesses of 0.1 and 0.5 cm, while 73% of snails moved in unoiled chambers after 4h. A toxicity assay was then conducted by exposing snails to oil coated Spartina stems in chambers for periods up to 72 h, and mortality was monitored for 7 days post exposure. Snail survival decreased with increasing exposure time, and significant mortality (∼35%) was observed following an oil exposure of less than 24 h. Here, we have shown that oil impeded snail movement to clean habitat over a short distance and resulted in oil-exposure times that decreased survival. Taken together, along with declines documented by others in field surveys, these results suggest that marsh periwinkle snails may have been adversely affected following exposure to DWH oil.

Depletion of liver glutathione levels in rats: a potential confound of nose-only inhalation.

PubMed

Fechter, Laurence D; Nelson-Miller, Alisa; Gearhart, Caroline

2008-07-01

Nose-only inhalation exposure chambers offer key advantages to whole-body systems, particularly when aerosol or mixed aerosol-vapor exposures are used. Specifically, nose-only chambers provide enhanced control over the route of exposure and dose by minimizing the deposition of particles either on the subjects skin/fur or on surfaces of a whole-body exposure system. In the current series of experiments, liver, brain, and lung total glutathione (GSH) levels were assessed following either nose-only or whole-body exposures to either jet fuel or to clean, filtered air. The data were compared to untreated control subjects. Acute nose-only inhalation exposures of rats resulted in a significant depletion of liver GSH levels both in subjects that were exposed to clean, filtered air as well as those exposed to JP-8 jet fuel and to a synthetic jet fuel. Glutathione levels were not altered in lung or brain tissue. Whole-body inhalation exposure had no effect on GSH levels in any tissue for any of the treatment groups. A second experiment demonstrated that the loss of GSH did not occur if rats were anaesthetized prior to and during nose-only exposure to clean, filtered air or to mixed hydrocarbons. These data appear to be consistent with studies demonstrating depletion in liver GSH levels among rats subjected to restraint stress. Finally, the depletion of GSH that was observed in liver following a single acute exposure was reduced following five daily exposures to clean, filtered air, suggesting the possibility of habituation to restraint in the nose-only exposure chamber. The finding that placement in a nose-only exposure chamber per se yields liver GSH depletion raises the possibility of an interaction between this mode of toxicant exposure and the toxicological effects of certain inhaled test substances.

Exposure of research personnel to carbon dioxide during euthanasia procedures.

PubMed

Amparan, Ashlee A; Djoufack-Momo, Shelly M; Grunden, Beverly; Boivin, Gregory P-

2014-07-01

CO₂ is one of the most commonly used euthanasia agents for laboratory animals. Considerable research has gone into the effect of the agent on animals, but little has been done to examine potential human exposure during these procedures. In this study, we examine the CO₂ concentrations to which personnel are exposed while euthanizing rodents with CO₂. To examine the environmental levels of CO₂ generated during euthanasia, we examined several variables including flow rate, inclusion of a cage in the euthanasia chamber, inversion of the euthanasia chamber, chamber size, distance from the euthanasia chamber, and room size. Under all conditions, CO₂ concentrations in the room temporarily increased significantly to 600 to 4000 ppm. The results of this study show that, under several testing scenarios, occupational levels of CO₂ did not exceed governmentally mandated allowable exposure limits during routine rodent euthanasia procedures.

Exposure chamber measurements of mass transfer and partitioning at the plant/air interface.

PubMed

Maddalena, Randy L; McKone, Thomas E; Kado, Norman Y

2002-08-15

Dynamic measures of air and vegetation concentrations in an exposure chamber and a two-box mass balance model are used to quantify factors that control the rate and extent of chemical partitioning between vegetation and the atmosphere. A continuous stirred flow-through exposure chamber was used to investigate the gas-phase transfer of pollutants between air and plants. A probabilistic two-compartment mass balance model of plant/air exchange within the exposure chamber was developed and used with measured concentrations from the chamber to simultaneously evaluate partitioning (Kpa), overall mass transfer across the plant/air interface (Upa), and loss rates in the atmosphere (Ra) and aboveground vegetation (Rp). The approach is demonstrated using mature Capsicum annuum (bell pepper) plants exposed to phenanthrene (PH), anthracene (AN), fluoranthene (FL) and pyrene (PY). Measured values of log Kpa (V[air]/V[fresh plant]) were 5.7, 5.7, 6.0, and 6.2 for PH, AN, FL, and PY, respectively. Values of Upa (m d(-1)) under the conditions of this study ranged from 42 for PH to 119 for FL. After correcting for wall effects, the estimated reaction half-lives in air were 3, 9, and 25 h for AN, FL and PY. Reaction half-lives in the plant compartment were 17, 6, 17, and 5 d for PH, AN, FL, and PY, respectively. The combined use of exposure chamber measurements and models provides a robust tool for simultaneously measuring several different transfer factors that are important for modeling the uptake of pollutants into vegetation.

UV exposure in artificial and natural weathering: A comparative study

NASA Astrophysics Data System (ADS)

Heikkilä, A.; Kazadzis, S.; Meinander, O.; Vaskuri, A.; Kärhä, P.; Mylläri, V.; Syrjälä, S.; Koskela, T.

2017-02-01

We report on a study focusing on UV exposure conditions in three different types of chambers used for accelerated ageing of materials. The first chamber is equipped with four 300-W UVA/UVB mercury vapour lamps (Ultra-Vitalux/Osram). The second chamber uses four 40-W UVA fluorescent lamps (QUV-340/Q-Lab). The third chamber is Weather-Ometer Ci3000+ from Atlas with a 4500-W xenon arc lamp. UV irradiance prevailing in each chamber was measured using Bentham DM150 double monochromator spectroradiometer. The results were compared to measurements of solar spectral UV irradiance at Jokioinen, Finland, with a Brewer MkIII double monochromator spectrophotometer. The spectral shapes of the exposing UV radiation in the different chambers were found to notably differ from each other and from the solar UV spectrum. Both spatial inhomogeneities and temporal variability caused by various factors, like the ageing of the lamps, were detected. The effects were found to strongly depend on wavelength of the exposing UV radiation. The findings of this study underline the necessity of careful characterization of the UV exposure conditions provided by the facilities used in accelerated testing of materials.

The risk of developing decompression sickness during air travel following altitude chamber flight.

PubMed

Rush, W L; Wirjosemito, S A

1990-11-01

Approximately 35,000 students are trained annually in United States Air Force (USAF) altitude chambers. Students who depart the training site via aircraft on the same day as their altitude chamber exposure may place themselves at increased risk for decompression sickness (DCS). Air travel as a passenger in the immediate post-chamber flight period is unrestricted by current USAF regulations. A retrospective study was conducted to assess the potential risk involved in such post-chamber flight travel. During the years 1982-87, there were 292 cases of DCS involving altitude chamber students which were subsequently treated with hyperbaric oxygen therapy. Only seven cases were found wherein the student was asymptomatic prior to air travel and subsequently developed DCS. Because the percentage of students who postpone travel is unknown, a precise relative risk could not be determined. Although the number of cases where sequential chamber and aircraft hypobaric exposures has initiated DCS is small, the potential for such occurrences remains a health concern.

Development of Behavioral Toxicology Methodology for Interactive Exposure Regimens.

DTIC Science & Technology

1983-12-01

exposures conducted at weekly Interval had Identical effects. Five consecutive daily exposures resulted In partial tolerance to the disruptive effects...No. 2001C) for which the tap line was also located at the top of the chamber head measured the negative pressure of chamber Interior in relation to...result In partial tolerance development. lIT RESEARCH INSTITUTE 44 Although In contrast to Ator and Merigan’s finding, tolerance was not complete after

Emulsion Chamber Technology Experiment (ECT)

NASA Technical Reports Server (NTRS)

Gregory, John C.; Takahashi, Yoshiyuki

1996-01-01

The experimental objective of Emulsion Chamber Technology (ECT) was to develop space-borne emulsion chamber technology so that cosmic rays and nuclear interactions may subsequently be studied at extremely high energies with long exposures in space. A small emulsion chamber was built and flown on flight STS-62 of the Columbia in March 1994. Analysis of the several hundred layers of radiation-sensitive material has shown excellent post-flight condition and suitability for cosmic ray physics analysis at much longer exposures. Temperature control of the stack was 20 +/-1 C throughout the active control period and no significant deviations of temperature or pressure in the chamber were observed over the entire mission operations period. The unfortunate flight attitude of the orbiter (almost 90% Earth viewing) prevented any significant number of heavy particles (Z greater than or equal to 10) reaching the stack and the inverted flow of shower particles in the calorimeter has not allowed evaluation of absolute primary cosmic ray-detection efficiency nor of the practical time limits of useful exposure of these calorimeters in space to the level of detail originally planned. Nevertheless, analysis of the observed backgrounds and quality of the processed photographic and plastic materials after the flight show that productive exposures of emulsion chambers are feasible in low orbit for periods of up to one year or longer. The engineering approaches taken in the ECT program were proven effective and no major environmental obstacles to prolonged flight are evident.

Exposure chamber

DOEpatents

Moss, Owen R.

1980-01-01

A chamber for exposing animals, plants, or materials to air containing gases or aerosols is so constructed that catch pans for animal excrement, for example, serve to aid the uniform distribution of air throughout the chamber instead of constituting obstacles as has been the case in prior animal exposure chambers. The chamber comprises the usual imperforate top, bottom and side walls. Within the chamber, cages and their associated pans are arranged in two columns. The pans are spaced horizontally from the walls of the chamber in all directions. Corresponding pans of the two columns are also spaced horizontally from each other. Preferably the pans of one column are also spaced vertically from corresponding pans of the other column. Air is introduced into the top of the chamber and withdrawn from the bottom. The general flow of air is therefore vertical. The effect of the horizontal pans is based on the fact that a gas flowing past the edge of a flat plate that is perpendicular to the flow forms a wave on the upstream side of the plate. Air flows downwardly between the chamber walls and the outer edges of the pan. It also flows downwardly between the inner edges of the pans of the two columns. It has been found that when the air carries aerosol particles, these particles are substantially uniformly distributed throughout the chamber.

Soman toxicity during and after exposure to different environmental temperatures.

PubMed

Wheeler, T G

1989-01-01

A systematic study has been conducted to determine physiological susceptibility to the potent anticholinesterase soman during and after exposure to different environmental temperatures. Rats were placed in an environmental chamber set at -1, 7, 15, 23, or 31 degrees C (80% relative humidity, RH) from 0000 to 0800 h. Soman injections were given subcutaneously (sc) at 0600 h (during thermal stress), or at 0810 h after removal from the chamber (injected and tested at 23 degrees C, 60% RH). The measures (taken 30 min after soman injection) included core temperature, grip strength, general state of health, and LD10 estimates (taken 2 h post injection). Soman exposure produced a dose-related effect on each measure under all thermal stress conditions. During thermal stress, soman exposure produced major changes in core temperature ranging from 26 to 41 degrees C, which were linearly related to the environmental temperature condition. After removal from the chamber, soman exposure reduced core temperature by only 1 degree C without regard to prior thermal stress temperature. Grip strength and subjective health rating were soman dose-related with only a minor chamber temperature influence. The toxicity of soman was increased during exposure to either cold or hot environments and after removal from the cold environments. The adrenal-cortical stress response to cold involves increased metabolism and oxygen requirement. The exception was the decreased toxicity observed when soman exposure occurred after removal from a hot environment, exacerbated by a failure in the respiratory system due to anticholinesterase exposure. The increased toxicity of soman while in or after removal from a cold environment is believed to be due to a generalized adrenal-cortical stress response. The increased soman toxicity while in a hot environment, but decreased toxicity after removal from the hot environment, provides an interesting subject for further research.

SMOG CHAMBERS: A TOOL TO EXAMINE EFFECTS OF PHOTOCHEMICALLY AGED AIR POLLUTANTS ON BIOLOGICAL SYSTEMS

EPA Science Inventory

Irradiative exposure chambers or 'Smog chambers' have been used at the University of North Carolina for over 30 years to study photochemically active mixtures of volatile organic compounds and their transformation products (a significant sub-set of Hazardous Air Pollutants, HAPs)...

State-of-the-art exposure chamber for highly controlled and reproducible THz biological effects studies

NASA Astrophysics Data System (ADS)

Cerna, Cesario Z.; Elam, David P.; Echchgadda, Ibtissam; Sloan, Mark A.; Wilmink, Gerald J.

2014-03-01

Terahertz (THz) imaging and sensing technologies are increasingly being used at international airports for security screening purposes and at major medical centers for cancer and burn diagnosis. The emergence of new THz applications has directly resulted in an increased interest regarding the biological effects associated with this frequency range. Knowledge of THz biological effects is also desired for the safe use of THz systems, identification of health hazards, and development of empirically-based safety standards. In this study, we developed a state-of-the-art exposure chamber that allowed for highly controlled and reproducible studies of THz biological effects. This innovative system incorporated an industry grade cell incubator system that permitted a highly controlled exposure environment, where temperatures could be maintained at 37 °C +/- 0.1 °C, carbon dioxide (CO2) levels at 5% +/- 0.1%, and relative humidity (RH) levels at 95% +/- 1%. To maximize the THz power transmitted to the cell culture region inside the humid incubator, a secondary custom micro-chamber was fabricated and incorporated into the system. This micro-chamber shields the THz beam from the incubator environment and could be nitrogen-purged to eliminate water absorption effects. Additionally, a microscope that allowed for real-time visualization of the live cells before, during, and after THz exposure was integrated into the exposure system.

EFFECTS OF ACTIVATED CHARCOAL FILTRATION AND OZONATION ON HYDROCARBON AND CARBONYL LEVELS OF AMBIENT AIR USED IN CONTROLLED-EXPOSURE CHAMBER STUDIES OF AIR POLLUTANT HUMAN HEALTH EFFECTS

EPA Science Inventory

Air sampling experiments were done in 1985, 1987, and 1993 at the human-exposure chamber facility of the U.S. EPA Health Effects Research Laboratory in Chapel Hill, NC. easurements of VOC's by GC-FID and aldehyde measurements by the DNPH silica gel cartridge method were made, com...

Evaluating the efficacy of a thermal exposure chamber designed for assessing workers' thermal hazard.

PubMed

Tsai, Perng-Jy; Lo, Chuh-Lun; Sun, Yih-Min; Juang, Yow-Jer; Liu, Hung-Hsin; Chen, Wang-Yi; Yeh, Wen-Yu

2003-05-01

This study was conducted on a thermal exposure chamber designed for assessing workers' thermal hazard. In order to assess the efficacy of the studied chamber, three environmental conditions were selected to simulate high, middle and low thermal impact situations, with air temperatures (Ta) of 43.12, 36.23 and 25.77 masculine C, globe temperatures (Tg) of 44.41, 41.07 and 29.24 masculine C, relative humidity (RH) of 77, 59 and 39%, and air flow velocities (Va) of 1.70, 0.91 and 0.25 m/s, respectively. For the three specified thermal impact conditions, results show that the coefficients of variation (CVs) for Ta, Tg, RH and Va measured in the chamber studied were consistently less than 10%, except for Va under the low thermal impact condition (=50%). For each specified thermal impact condition, we generated 1,000 environmental combinations by using the Monte Carlo simulation approach according to the variations obtained from the four environmental factors. We directly adopted the ISO 7933 approach to estimate the allowable exposure time (AET) for each simulated environmental condition. This study yielded a range in the 95% confidence interval (95% CI) of the estimated AETs for the three specified thermal impact conditions which were consistently less than 5 min. We further conducted the sensitivity analysis to examine the effect of the four environmental factors on estimating AETs. We found Va was the least important factor in estimating AETs for any specified thermal impact condition. In conclusion, although Va was found with great variation for the chamber specified in the low thermal impact condition, the exposure chamber studied can still be regarded as a feasible one for assessing workers' thermal hazard.

Characterization of Potential Aerosol Mass using an Oxidation Chamber coupled to an Aerodyne HR-ToF-AMS during DAURE, SHARP, and FLAME-3

NASA Astrophysics Data System (ADS)

Ortega, A. M.; Brune, W. H.; Cubison, M.; Lefer, B. L.; Schallharter, S.; Metzger, A.; Mueller, M.; Hansel, A.; Jimenez, J. L.

2009-12-01

The Potential Aerosol Mass (PAM) oxidation chamber (Kang et al., ACP 2007) used in front of an aerosol instrument provides an indication of the secondary inorganic and organic aerosol formation potential in an airmass. The chamber, a flow tube with small residence time, rapidly oxidizes ambient air through exposure to high concentrations of ozone (O3) and hydroxy (OH) and hydroperoxy (HO2) radicals. Here we use a recently-modified PAM chamber in conjunction with an Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS; DeCarlo et al., Anal. Chem. 2006) during two ambient studies and one source study: the Determination of the Sources of the Atmospheric Aerosol in Urban and Rural Environments in Spain (DAURE) in February 2009, the Study of Houston Atmospheric Radical Precursors (SHARP) in April 2009, and the Fire Lab at Missoula Experiment phase 3 (FLAME-3) in Sep. 2009. The AMS samples alternatively between ambient air and chamber-processed air every 2.5 min., and a cycling of the UV light intensity (OH exposure) is also used with a maximum equivalent exposure of about 7 days. Large variations in the organic PAM were observed in the different studies. In particular very large PAM values were observed in several evenings in Houston when the site was impacted by emissions from petrochemical facilities. Optimum OH exposure for maximum PAM was observed at intermediate OH levels. For all experiments we compare the amount of SOA formed in the PAM chamber to the yield predicted by the measured precursors (from PTRMS instruments).

Therapeutic effect of bilastine in Japanese cedar pollinosis using an artificial exposure chamber (OHIO Chamber).

PubMed

Hashiguchi, Kazuhiro; Wakabayashi, Ken-Ichiro; Togawa, Michinori; Saito, Akihiro; Okubo, Kimihiro

2017-01-01

Environmental exposure chambers have been used to expose subjects to aeroallergens to investigate the efficacy of prophylactic treatment with symptomatic agents in Japan. We first examined the therapeutic effect of bilastine (BIL), a novel non-sedative second-generation H 1 -antihistamine, in subjects with Japanese cedar pollinosis using an artificial exposure chamber (OHIO Chamber). This was a randomized, double-blind, four-way crossover, placebo- and active-controlled phase II study (trial registration number JapicCTI-132213). Subjects were exposed to cedar pollen (8000 grains/m 3 ) for 2 h on Day -1 and 4 h each on Day 1 and 2. BIL 10 or 20 mg, placebo, or fexofenadine hydrochloride (FEX) 60 mg was administered orally 1 h after the start of pollen exposure on Day 1. Placebo or FEX was administered 12 h after the first dosing. The primary efficacy endpoint was the sum of total nasal symptom score (TNSS) from 0 to 3 h after the Day 1 dosing. We enrolled 136 subjects and the sum of TNSS on Day 1 of the three active treatments was significantly lower than that of placebo and was maintained up to 26 h after the first dosing (Day 2). The sum of TNSS or sneezing score on Day 1 after BIL 20 mg was more significantly decreased than after FEX. Moreover, BIL showed a faster onset of action than FEX. We demonstrated the efficacy, rapid onset, and long duration of action of BIL in subjects with Japanese cedar pollinosis exposed to cedar pollen using the OHIO Chamber. Copyright © 2016 Japanese Society of Allergology. Production and hosting by Elsevier B.V. All rights reserved.

Advanced Space Transportation Program (ASTP)

NASA Image and Video Library

1997-08-07

This double exposure depicts Marshall Space Flight Center's (MSFC) Test Stand 116 hosting a 60K Bantam Fastrac thrust chamber assembly test. The lower right exposure shows the engine firing in the test stand while the center exposure reveals workers monitoring the test in the interior block house of the test facility. The thrust chamber assembly is only part of the Fastrac engine project to build a low-cost engine for the X-34, an alternate light-weight unmarned launch vehicle. Both the nozzle and the engine for Fastrac are being manufactured at MSFC.

Chamber Tests with Human Subjects XX. Hypersensitivity to H as Demonstrated by Patch Tests Before and After Chamber Exposure to H Vapor

DTIC Science & Technology

1946-05-15

worn. In addition to erythema, edema and/or folliculitis were observed in only 2 of 230 men tested prior to exposure to H vapor. After exposure, 26% of...169 men manifested edema and/or folliculitis to patch tests. These men were arbitrarily considered "sensitized". This sensitized group also showed a...for edema or folliculitis , a value CONFIDENT-L.f, - 6 - C:7 Fx was calculated in which readings of 16 were assigned their erythema value of 8 and

Observation of super high energy big family with large scale Fe emulsion chambers

NASA Technical Reports Server (NTRS)

1985-01-01

In order to get higher efficiencies for detecting hadrons and to make technical improvements in the chamber structure, the Mt. Kambala Emulsion Chamber Collaboration constructed 57 sq. m. of Fe chamber, with thickness 29 c.u.(1c.u.=17.6 mm Fe), using 300 tons of Fe plates and made the first exposure from Sept., 1982 to May, 1984. The photosensitive layers consist of X-ray films of Sakura N type, Fuji No. 100 type and Tianjin III type, some of them contain also emulsion plates of Fuji ET7B type. They are inserted between the Fe plates at 2 c.u., beginning at 5 c.u. from the chamber top. In a number of blocks, 3 mm spacings are provided at every 2 c.u. of Fe plates to facilitate the replacement of photosensitive layers, without disassembling the chamber. On the bottom of the chamber Fe plates of thickness 9 mm are placed in order to shield the chamber from the radioactivities of the ground. An event, numbered K2 58 of visible energy sigma E sub gamma = 7345 TeV was found in this exposure. No obvious halo is seen in the event and all the showers are clearly separated and easy to measure. A brief report of the preliminary results is presented.

A microfluidic device with multi-valves system to enable several simultaneous exposure tests on Caenorhabditis elegans

NASA Astrophysics Data System (ADS)

Jung, Jaehoon; Nakajima, Masahiro; Masaru, Takeuchi; Huang, Qiang; Fukuda, Toshio

2014-03-01

In this paper, we report on a microfluidic device with a multi-valve system to conduct several exposure tests on Caenorhabditis elegans (C. elegans) simultaneously. It has pneumatic valves and no-moving-parts (NMP) valves. An NMP valve is incorporated with a chamber and enables the unidirectional movement of C. elegans in the chamber; once worms are loaded into the chamber, they cannot exit, regardless of the flow direction. To demonstrate the ability of the NMP valve to handle worms, we made a microfluidic device with three chambers. Each chamber was used to expose worms to Cd and Cu solutions, and K-medium. A pair of electrodes was installed in the device and the capacitance in-between the electrode was measured. When a C. elegans passed through the electrodes, the capacitance was changed. The capacitance change was proportional to the body volume of the worm, thus the body volume change by the heavy metal exposure was measured in the device. Thirty worms were divided into three groups and exposed to each solution. We confirmed that the different solutions induced differences in the capacitance changes for each group. These results indicate that our device is a viable method for simultaneously analyzing the effect of multiple stimuli on C. elegans.

Utility of controlled human exposure studies for assessing the health effects of complex mixtures and indoor air pollutants.

PubMed Central

McDonnell, W F

1993-01-01

The study of health effects induced by exposure to mixtures of pollutants is a complex task. The purpose of this paper is to identify areas of research in which the conduct of human controlled exposure (clinical) studies may contribute to better understanding health effects of exposure to indoor air and other mixtures. The strengths and weaknesses of clinical studies in general are reviewed, as well as examples from the literature of approaches that have been used. Human chamber studies play an important role alongside epidemiologic and animal toxicologic studies in such research. Human chamber studies are limited with regard to assessing chronic effects, rare effects, or effects from long-duration exposures but are powerful in assessing acute, reversible effects from short-duration exposures in humans. The areas in which human chamber studies are most likely to contribute include identification of effects or markers of effects for exposure to a given pollutant or mix of pollutants; direct dose-response assessment of effects for individual compounds and mixtures of set composition; identification of individual compounds responsible for the effects of a mixture; study of the joint effects of a binary mixture; development of markers of acute exposure for particular compounds; development of outcome measurements to be used in the field; and identification, characterization, and testing of sensitive subpopulations. PMID:8206031

Validation of a new whole-body cryotherapy chamber based on forced convection.

PubMed

Bouzigon, Romain; Arfaoui, Ahlem; Grappe, Frédéric; Ravier, Gilles; Jarlot, Benoit; Dugue, Benoit

2017-04-01

Whole-body cryotherapy (WBC) and partial-body cryotherapy (PBC) are two methods of cold exposure (from -110 to -195°C according to the manufacturers). However, temperature measurement in the cold chamber during a PBC exposure revealed temperatures ranging from -25 to -50°C next to the skin of the subjects (using isolating layer placed between the sensor and the skin). This discrepancy is due to the human body heat transfer. Moreover, on the surface of the body, an air layer called the boundary layer is created during the exposure and limits heat transfer from the body to the cabin air. Incorporating forced convection in a chamber with a participant inside could reduce this boundary layer. The aim of this study was to explore the use of a new WBC technology based on forced convection (frontal unilateral wind) through the measurement of skin temperature. Fifteen individuals performed a 3-min WBC exposure at -40°C with an average wind speed of 2.3ms -1 . The subjects wore a headband, a surgical mask, underwear, gloves and slippers. The skin temperature of the participants was measured with a thermal camera just before exposure, just after exposure and at 1, 3, 5, 10, 15 and 20min after exposure. Mean skin temperature significantly dropped by 11°C just after exposure (p<0.001) and then significantly increased during the 20-min post exposure period (p<0.001). No critically low skin temperature was observed at the end of the cold exposure. This decrease was greater than the mean decreases in all the cryosauna devices with reported exposures between -140°C and -160°C and those in two other WBC devices with reported exposures between -60°C and -110°C. The use of this new technology provides the ability to reach decreases in skin temperature similar to other technologies. The new chamber is suitable and relevant for use as a WBC device. Copyright © 2017 Elsevier Ltd. All rights reserved.

Materials screening chamber for testing materials resistance to atomic oxygen

NASA Technical Reports Server (NTRS)

Pippin, H. G.; Carruth, Ralph

1989-01-01

A unique test chamber for exposing material to a known flux of oxygen atoms is described. The capabilities and operating parameters of the apparatus include production of an oxygen atom flux in excess of 5 x 10 to the 16th atoms/sq cm-sec, controlled heating of the sample specimen, RF circuitry to contain the plasma within a small volume, and long exposure times. Flux measurement capabilities include a calorimetric probe and a light titration system. Accuracy and limitations of these techniques are discussed. An extension to the main chamber to allow simultaneous ultraviolet and atomic oxygen exposure is discussed. The oxygen atoms produced are at thermal energies. Sample specimens are maintained at any selected temperature between ambient and 200 C, to within + or - 2 C. A representative example of measurements made using the chamber is presented.

Coexposure to toluene and p-xylene in man: central nervous functions.

PubMed Central

Olson, B A; Gamberale, F; Iregren, A

1985-01-01

Sixteen men were studied in an exposure chamber to assess the effect of four hours' exposure to toluene (3.25 mmol/m3), xylene (2.84 mmol/m3), a mixture of toluene and xylene (2.20 + 0.94 mmol/m3), and a control condition. With the aid of microcomputers, subjects performed tests of simple reaction time, short term memory, and choice reaction time immediately after entering the chamber, after two, and after four hours' exposure. The results indicate that the performance on the tests was unaffected by exposure. In the light of this result the risk of an acute effect on central nervous functions after exposure for four hours at concentrations that do not exceed the Swedish threshold limit values was considered to be minimal. PMID:3970870

Relative toxicity testing of spacecraft materials. 1: Spacecraft materials. [lethality of pyrolysates

NASA Technical Reports Server (NTRS)

Lawrence, W. H.

1980-01-01

In chamber thermodegradation procedures were used to access the lethality to rats of the pyrolysis/combustion products of three foams, an adhesive backed metallic tape and RTV silicone rubber adhesive sealant used in spacecraft construction. The role of carbon monoxide in the overall pyrolysate toxicity was also investigated. Post exposure observation of the rats, histological evaluation of selected organs, carbon monoxide concentration in the chamber atmosphere during exposure and the percent carboxyhemoglobin in the animals expiring in the chamber are discussed. Thermogravimetric analysis and dosage response results are given. The lethal effect of the RTV silicon appears to be due to physical obstruction of the respiratory system by particulate matter from pyrolysis.

Subchronic rat inhalation study with Skydrol 500B-4 fire resistant hydraulic fluid.

PubMed

Healy, C E; Nair, R S; Ribelin, W E; Bechtel, C L

1992-03-01

Skydrol 500B-4 fire resistant hydraulic fluid, a proprietary phosphate ester mixture composed principally of dibutyl phenyl phosphate (DBPP) and tributyl phosphate (TBP) and used as a commercial airline hydraulic fluid, was evaluated in an inhalation toxicity study of Sprague-Dawley rats. Target exposure levels used in the study were 0, 5, 100, and 300 mg/m3, and exposures were maintained for 6 hr/day, 5 days/week. Mass median aerodynamic diameters determined for particles in the mid- and high-exposure inhalation chambers were 2.85 microns and 3.31 microns, with geometric standard deviations of 1.99 microns and 1.92 microns, respectively. The percentage of particles less than 10 microns in diameter were 96.4% in the mid-exposure chamber and 95.5% in the high-exposure chamber. After 6 weeks of Skydrol exposure, 10 rats/sex/group were euthanized and then assessed for indications of possible chemical toxicity. Another 15 rats/sex/group were studied for a total of 13 weeks of exposure. The only clinical sign of chemical toxicity was the observation of a reddish nasal discharge with accompanying oral salivation in mid- and high-exposure animals of both sexes, indicative of an irritant response. Statistically significant reduced body weights; increased absolute and relative liver weights; and decreased erythrocyte counts, hemoglobin levels, and hematocrit values were observed in high-exposure female rats euthanized after 13 weeks of Skydrol exposure. High-exposure male rats also had increased absolute and relative liver weights and decreased hematocrit values after 13 weeks. Plasma cholinesterase levels were decreased in high-exposure female rats both 6 and 13 weeks after the study was initiated.(ABSTRACT TRUNCATED AT 250 WORDS)

Test chamber investigation of the volatilization from source materials of brominated flame retardants and their subsequent deposition to indoor dust.

PubMed

Rauert, C; Harrad, S; Stranger, M; Lazarov, B

2015-08-01

Numerous studies have reported elevated concentrations of brominated flame retardants (BFRs) in dust from indoor micro-environments. Limited information is available, however, on the pathways via which BFRs in source materials transfer to indoor dust. The most likely hypothesized pathways are (a) volatilization from the source with subsequent partitioning to dust, (b) abrasion of the treated product, transferring microscopic fibers or particles to the dust (c) direct uptake to dust via contact between source and dust. This study reports the development and application of an in-house test chamber for investigating BFR volatilization from source materials and subsequent partitioning to dust. The performance of the chamber was evaluated against that of a commercially available chamber, and inherent issues with such chambers were investigated, such as loss due to sorption of BFRs to chamber surfaces (so-called sink effects). The partitioning of polybrominated diphenyl ethers to dust, post-volatilization from an artificial source was demonstrated, while analysis in the test chamber of a fabric curtain treated with the hexabromocyclododecane formulation, resulted in dust concentrations exceeding substantially those detected in the dust pre-experiment. These results provide the first experimental evidence of BFR volatilization followed by deposition to dust. Brominated flame retardants (BFRs) are ubiquitous in indoor air and dust, leading to human exposure and resultant concerns about their adverse impact on health. Indoor dust has been demonstrated to constitute an important vector of human exposure to BFRs, especially for toddlers. Despite the greater importance of dust contamination in the context of human exposure to BFRs, the mechanisms via which BFRs transfer from source materials to dust have hitherto been subject to only limited research. In this study, a test chamber is utilized to simulate the migration of BFRs to dust via volatilization from source materials and subsequent deposition to dust. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

X-ray photoelectron spectroscopy and secondary electron yield analysis of Al and Cu samples exposed to an accelerator environment

NASA Astrophysics Data System (ADS)

Rosenberg, R. A.; McDowell, M. W.; Ma, Q.; Harkay, K. C.

2003-09-01

It is well known that exposure to an accelerator environment can cause ``conditioning'' of the vacuum chamber surfaces. In order to understand the manner in which the surface structure might influence the production of gases and electrons in the accelerator, such surfaces should be studied both before and after exposure to accelerator conditions. Numerous studies have been performed on representative materials prior to being inserted into an accelerator, but very little has been done on materials that have ``lived'' in the accelerator for extended periods. In the present work, we mounted Al and Cu coupons at different positions in a section of the Advanced Photon Source storage ring and removed them following exposures ranging from 6 to 18 months. X-ray photoelectron spectroscopy (XPS) of the surface was performed before and after exposure. Changes were observed that depended on the location and whether the coupon was facing the chamber interior or chamber wall. These results will be presented and compared to XPS and secondary electron yield data obtained from laboratory measurements meant to simulate the accelerator conditions.

Space station protective coating development

NASA Technical Reports Server (NTRS)

Pippin, H. G.; Hill, S. G.

1989-01-01

A generic list of Space Station surfaces and candidate material types is provided. Environmental exposures and performance requirements for the different Space Station surfaces are listed. Coating materials and the processing required to produce a viable system, and appropriate environmental simulation test facilities are being developed. Mass loss data from the original version of the atomic oxygen test chamber and the improved facility; additional environmental exposures performed on candidate materials; and materials properties measurements on candidate coatings to determine the effects of the exposures are discussed. Methodologies of production, and coating materials, used to produce the large scale demonstration articles are described. The electronic data base developed for the contract is also described. The test chamber to be used for exposure of materials to atomic oxygen was built.

Beijing ambient particle exposure accelerates atherosclerosis in ApoE knockout mice.

PubMed

Chen, Tian; Jia, Guang; Wei, Yongjie; Li, Jiucun

2013-11-25

Air pollution is associated with significant adverse health effects including increased cardiovascular morbidity and mortality. However research on the cardiovascular effect of "real-world" exposure to ambient particulate matter (PM) in susceptible animal model is very limited. In this study, we aimed to investigate the association between Beijing ambient particle exposure and the atherosclerosis development in the apolipoprotein E knockout mice (ApoE(-/-) mice). Two parallel exposure chambers were used for whole body exposure among ApoE knockout mice. One of the chambers was supplied with untreated ambient air (PM group) and the other chamber was treated with ambient air filtered by high-efficiency particulate air (HEPA) filter (FA group). Twenty mice were divided into two groups and exposed to ambient PM (n=10 for PM group) or filtered air (n=10 for FA group) for two months from January 18th to March 18th, 2010. During the exposure, the mass concentrations of PM2.5 and PM10 in the two chambers were continuously monitored. Additionally, a receptor source apportionment model of chemical mass balance using 19 organic tracers was applied to determine the contributions of sources on the PM2.5 in terms of natural gas, diesel vehicle, gasoline vehicle, coal burning, vegetable debris, biomass burning and cooking. At the end of the two-month exposure, biomarkers of oxidative stress, inflammation and lipid metabolism in bronchoalveolar lavage fluid (BAL) and blood samples were determined and the plaque area on the aortic endothelium was quantified. In the experiment, the concentrations of PM10 and PM2.5 in PM chamber were 99.45μg/m(3) and 61.0μg/m(3) respectively, while PM2.5 in FA chamber was 17.6μg/m(3). Source apportionment analysis by organic tracers showed that gasoline vehicle (39.9%) and coal burning (24.3%) emission were the two major sources contributing to the mass concentration of PM2.5 in Beijing. Among the ApoE knockout mice, the PM group were significantly higher than the FA group in terms of serum total cholesterol, low-density lipoprotein, tumor necrosis factor-alpha (TNF-alpha) and C-reactive protein as well as TNF-alpha and interleukin-6 in BAL. Also the total antioxidant capacity and oxidized low-density lipoprotein were significantly different between the two groups. In addition, pathological analysis of aortic arch reveals that the plaques area in the PM group increased significantly compared to the FA group. Our results demonstrated that ambient PM exposure could induce considerable oxidative stress and systemic inflammation in ApoE knockout mice and contribute to the progression of atherosclerosis. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Dark Matter Search Results from the PICO-60 CF$$_3$$I Bubble Chamber

DOE PAGES

Amole, C.; Ardid, M.; Asner, D. M.; ...

2016-03-01

We reported new data from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 36.8 kg of CF 3I and located in the SNOLAB underground laboratory. PICO-60 is the largest bubble chamber to search for dark matter to date. With an analyzed exposure of 92.8 live-days, PICO-60 exhibits the same excellent background rejection observed in smaller bubble chambers. Alpha decays in PICO-60 exhibit frequency-dependent acoustic calorimetry, similar but not identical to that reported recently in a C 3F 8 bubble chamber. PICO-60 also observes a large population of unknown background events, exhibiting acoustic, spatial, and timingmore » behaviors inconsistent with those expected from a dark matter signal. We found these behaviors allow for analysis cuts to remove all background events while retaining 48.2%of the exposure. Stringent limits on WIMPs interacting via spin-dependent proton and spin-independent processes are set, and the interpretation of the DAMA/LIBRA modulation signal as dark matter interacting with iodine nuclei is ruled out.« less

Dark matter search results from the PICO-60 CF 3 I bubble chamber

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

Amole, C.; Ardid, M.; Asner, D. M.

2016-03-01

New data are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 36.8 kg of CF3I and located in the SNOLAB underground laboratory. PICO-60 is the largest bubble chamber to search for dark matter to date. With an analyzed exposure of 92.8 livedays, PICO-60 exhibits the same excellent background rejection observed in smaller bubble chambers. Alpha decays in PICO-60 exhibit frequency-dependent acoustic calorimetry, similar but not identical to that reported recently in a C3F8 bubble chamber. PICO-60 also observes a large population of unknown background events, exhibiting acoustic, spatial, and timing behaviors inconsistent withmore » those expected from a dark matter signal. These behaviors allow for analysis cuts to remove all background events while retaining 48.2% of the exposure. Stringent limits on weakly interacting massive particles interacting via spin-dependent proton and spin-independent processes are set, and most interpretations of the DAMA/LIBRA modulation signal as dark matter interacting with iodine nuclei are ruled out.« less

Chamber and field evaluations of air pollution tolerances of urban trees

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

Karnosky, D.F.

1981-04-01

Results are presented for a study of the relative air pollution tolerances of 32 urban-tree cultivars as determined by both chamber fumigations and field exposures. Tolerances to ozone and sulfur dioxide, alone and in combination, were determined using short-term, acute doses administered while the plants were inside a plastic fumigation chamber located inside the Cary Arboretum greenhouses. In a follow-up study still underway, representatives of the same cultivars were outplanted at four locations in the greater New York City area. To date, only oxidant-type injury has been observed on trees in the field plots. Cultivars tolerant to all chamber andmore » field exposures were Acer platanoides Cleveland, Crimson King, Emerald Queen, Jade Glen, and Summershade; Acer rubrum Autumn Flame and Red Sunset; Acer saccharum Green Mountain and Temple's Upright; Fagus sylvatica Rotundifolia; Fraxinus pennsylvanica Summit; and Ginkgo biloba Fastigate and Sentry. Cultivars sensitive to ozone as determined by the chamber and field tests and that may serve as bioindicators of the presence of ozone were Gleditsia triacanthos inermis imperial and Platanus acerifolia Bloodgood.« less

A lifestyle-based scenario for U.S. buildings: Implications for energy use

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

Diamond, Rick

Dynamic measures of air and vegetation concentrations in an exposure chamber and a two-box mass balance model are used to quantify factors that control the rate and extent of chemical partitioning between vegetation and the atmosphere. A continuous stirred flow-through exposure chamber was used to investigate the gas-phase transfer of pollutants between air and plants. A probabilistic two-compartment mass-balance model of plant/air exchange within the exposure chamber was developed and used with measured concentrations from the chamber to simultaneously evaluate partitioning (K{sub pa}), overall mass transfer across the plant/air interface (U{sub pa}) and loss rates in the atmosphere (R{sub a})more » and aboveground vegetation (R{sub p}). The approach is demonstrated using mature Capsicum annuum (bell pepper) plants exposed to phenanthrene (PH), anthracene (AN), fluoranthene (FL) and pyrene (PY). Measured values of log K{sub pa} (V{sub [air]}/V{sub [fresh plant]}) were 5.7, 5.7, 6.0 and 6.2 for PH, AN, FL and PY, respectively. Values of U{sub pa} (m d{sup -1}) under the conditions of this study ranged from 42 for PH to 119 for FL. After correcting for wall effects, the estimated reaction half-lives in air were 3, 9 and 25 hours for AN, FL and PY. Reaction half-lives in the plant compartment were 17, 6, 17 and 5 days for PH, AN, FL and PY. The combined use of exposure chamber measurements and models provides a robust tool for simultaneously measuring several different transfer factors that are important for modeling the uptake of pollutants into vegetation.« less

Regional differences in sweat rate response of steers to short-term heat stress

USDA-ARS?s Scientific Manuscript database

Six Angus steers (319±8.5 kg) were assigned to one of two groups (hot or cold exposure) of three steers each, and placed into two environmental chambers initially maintained at 16.5–18.8°C air temperature (Ta). cold chamber Ta was lowered to 8.4°C, while Ta within the hot chamber was increased to 32...

Deployment and testing of a second prototype expandable surgical chamber in microgravity

NASA Technical Reports Server (NTRS)

Markham, Sanford M.; Rock, John A.

1991-01-01

During microgravity exposure, two separate expandable surgical chambers were tested. Both chambers had been modified to fit the microgravity work station without extending over the sides of the table. Both chambers were attached to a portable laminar flow generator which served two purposes: to keep the chambers expanded during use; and to provide an operative area environment free of contamination. During the tests, the chambers were placed on various parts of a total body moulage to simulate management of several types of trauma. The tests consisted of cleansing contusions, debridement of burns, and suturing of lacerations. Also, indigo carmine dye was deliberately injected into the chamber during the tests to determine the ease of cleansing the chamber walls after contamination by escaping fluids. Upon completion of the tests, the expandable surgical chambers were deflated, folded, and placed in a flattened state back into their original containers for storage and later disposal. Results are briefly discussed.

PROGRAMMABLE EXPOSURE CONTROL SYSTEM FOR DETERMINATION OF THE EFFECTS OF POLLUTANT EXPOSURE REGIMES ON PLANT GROWTH

EPA Science Inventory

A field-exposure research facility was constructed to provide a controlled environment to determine the influence of the various components of ozone exposure on plant response. The facility uses modified open-top chambers and an automated control system for continuous delivery an...

Effect of ozone on photosynthesis, vegetative growth and productivity of prunus salicina in the San Joaquin Valley of California. Final report

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

Williams, L.E.; DeJong, T.M.; Retzlaff, W.A.

1991-10-31

In 1988, an experimental orchard of Cassleman plum (Prunus salicina) was planted in open top fumigation chambers and exposed for 4 growing seasons to three ozone concentrations near Fresno, California. During the two years from orchard establishment to the first fruit bearing stage, mean 12-h ozone levels (1989) were 0.044 ppm in the charcoal filtered chambers, 0.059 ppm in the ambient air chambers, 0.111 ppm in the ambient plus added ozone chambers and 0.064 ppm in the no-chamber field plots. The 1990 ozone levels were 0.038 ppm, 0.050 ppm, 0.090 ppm, and 0.050 ppm, respectively. Chronic ozone stress has amore » detrimental effect on leaf appearance and retention, trunk growth, and yield during the orchard establishment period. Fruit production was 28 percent lower in the ambient exposures and 38 percent lower in the twice ambient exposures, compared to trees grown in filtered air chambers. Photosynthesis was reduced 11 percent and 40 percent respectively. Premature leaf drop occurred at mean daily ozone concentrations greater than 0.09 ppm (the California Ambient Air Quality Standard) and had an adverse impact on trunk growth.« less

Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

PubMed Central

Fujimoto, Hiroshi; Suekane, Takashi; Imanishi, Katsuya; Yukiwaki, Satoshi; Wei, Hong; Nagayoshi, Kaori; Yahiro, Masayuki; Adachi, Chihaya

2016-01-01

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility. PMID:27958304

Influence of vacuum chamber impurities on the lifetime of organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Fujimoto, Hiroshi; Suekane, Takashi; Imanishi, Katsuya; Yukiwaki, Satoshi; Wei, Hong; Nagayoshi, Kaori; Yahiro, Masayuki; Adachi, Chihaya

2016-12-01

We evaluated the influence of impurities in the vacuum chamber used for the fabrication of organic light-emitting diodes on the lifetime of the fabricated devices and found a correlation between lifetime and the device fabrication time. The contact angle of the ITO substrates stored the chamber under vacuum were used to evaluate chamber cleanliness. Liquid chromatography-mass spectrometry was performed on Si wafers stored in the vacuum chamber before device fabrication to examine the impurities in the chamber. Surprisingly, despite the chamber and evaporation sources being at room temperature, a variety of materials were detected, including previously deposited materials and plasticizers from the vacuum chamber components. We show that the impurities, and not differences in water content, in the chamber were the source of lifetime variations even when the duration of exposure to impurities only varied before and after deposition of the emitter layer. These results suggest that the impurities floating in the vacuum chamber significantly impact lifetime values and reproducibility.

The systemic exposure to inhaled beclometasone/formoterol pMDI with valved holding chamber is independent of age and body size.

PubMed

Govoni, Mirco; Piccinno, Annalisa; Lucci, Germano; Poli, Gianluigi; Acerbi, Daniela; Baronio, Roberta; Singh, Dave; Kuna, Piotr; Chawes, Bo L K; Bisgaard, Hans

2015-02-01

Asthma guidelines recommend prescription of inhaled corticosteroids at a reduced dosage in children compared to older patients in order to minimize the systemic exposure and risk of unwanted side effects. In children, pressurized metered dose inhalers (pMDI) are recommended in combination with a valved holding chamber (VHC) to overcome the problem of coordinating inhalation with actuation. However, the influence of age and body size on the systemic exposure of drugs to be administered via a pMDI with VHC is still not fully elucidated. Therefore, we aimed to compare the systemic exposure to the active ingredients of a fixed combination of beclometasone-dipropionate/formoterol-fumarate administered via pMDI with VHC in children, adolescents and adults. The pharmacokinetics of formoterol and beclometasone-17-monopropionate (active metabolite of beclometasone-dipropionate) was evaluated over 8 h from three studies, each performed in a different age and body size group. Children (7-11 years, n = 20), adolescents (12-17 years, n = 29) and adults (≥18 years, n = 24) received a single dose of beclometasone/formoterol (children: 200 μg/24 μg, adolescents and adults: 400 μg/24 μg) via pMDI with AeroChamber Plus™. The systemic exposure in children in comparison to adolescents was equivalent for formoterol while it was halved for beclometasone-17-monopropionate in accordance with the halved dose of beclometasone administered in children (90% CIs within 0.8-1.25 for formoterol and 0.4-0.625 for beclometasone-17-monopropionate). The systemic exposure to beclometasone-17-monopropionate and formoterol was equivalent between adolescents and adults. The systemic exposure to the active ingredients of a fixed dose combination of beclometasone/formoterol administered via pMDI with AeroChamber Plus™ correlates with the nominal dose independently of patient age and body size. Thus, dose reduction in relation to age when using a pMDI with VHC may be unnecessary for reducing the systemic exposure in children. Copyright © 2014 Elsevier Ltd. All rights reserved.

Identification of Surrogate Measures of Diesel Exhaust Exposure in a Controlled Chamber Study

EPA Science Inventory

Exposure to diesel exhaust (DE) has been associated with acute cardiopulmonary and vascular responses, chronic noncancer health effects, and respiratory cancers in humans. To better understand DE exposures and eventually their related health effects, we established a controlled c...

Chronic vs. Short-Term Acute O 3 Exposure Effects on Nocturnal Transpiration in Two Californian Oaks

Treesearch

Nancy Grulke; E. Paoletti; R. L. Heath

2007-01-01

We tested the effect of daytime chronic moderate ozone (O3) exposure, short-term acute exposure, and both chronic and acute O3 exposure combined on nocturnal transpiration in California black oak and blue oak seedlings. Chronic O3 exposure (70 ppb for 8 h/day) was implemented in open-top chambers for...

Exercise Performance of Sea-Level Residents at 4300 m After 6 Days at 2200 m

DTIC Science & Technology

2009-11-01

tiple occasions at USARIEM during the baseline phase at sea level (SL, P B 5 ; 760 mmHg) or during two acute hypobaric chamber exposures (1 and 5 h...that were at the same P B as at the summit of Pikes Peak (i.e., 459 mmHg). Hypobaric chamber decompression from 760 mmHg to 459 mmHg took ; 10...of exposure to hypobaric hypoxia) and once beginning at ; 2 h of arriv- ing at the summit of Pikes Peak. Each long endurance performance assessment

Chronic Decompression Illness Cognitive Dysfunction Improved with Hyperbaric Oxygen: A Case Report

DTIC Science & Technology

2018-11-09

Altitude chamber exposures are used for training to allow aircrew to experience their hypoxia and pressure effect symptoms. Decompression illness ...chamber decompression illness is around 0.25% (1). Because the evolution of gas within the tissue or vasculature is being treated upon recompression

INFLUENCE OF OZONE EXPOSURE DYNAMICS ON THE GROWTH AND YIELD OF KIDNEY BEAN (JOURNAL VERSION)

EPA Science Inventory

A field experiment was conducted in open-top chambers to assess the importance of peak exposure concentration and exposure frequency on the responses of kidney bean plants to O3. There were five treatments in the study: charcoal-filtered air, constant exposure to 0.05 ppm O3 (131...

Development of a fluorescence-based sensor for rapid diagnosis of cyanide exposure.

PubMed

Jackson, Randy; Oda, Robert P; Bhandari, Raj K; Mahon, Sari B; Brenner, Matthew; Rockwood, Gary A; Logue, Brian A

2014-02-04

Although commonly known as a highly toxic chemical, cyanide is also an essential reagent for many industrial processes in areas such as mining, electroplating, and synthetic fiber production. The "heavy" use of cyanide in these industries, along with its necessary transportation, increases the possibility of human exposure. Because the onset of cyanide toxicity is fast, a rapid, sensitive, and accurate method for the diagnosis of cyanide exposure is necessary. Therefore, a field sensor for the diagnosis of cyanide exposure was developed based on the reaction of naphthalene dialdehyde, taurine, and cyanide, yielding a fluorescent β-isoindole. An integrated cyanide capture "apparatus", consisting of sample and cyanide capture chambers, allowed rapid separation of cyanide from blood samples. Rabbit whole blood was added to the sample chamber, acidified, and the HCN gas evolved was actively transferred through a stainless steel channel to the capture chamber containing a basic solution of naphthalene dialdehyde (NDA) and taurine. The overall analysis time (including the addition of the sample) was <3 min, the linear range was 3.13-200 μM, and the limit of detection was 0.78 μM. None of the potential interferents investigated (NaHS, NH4OH, NaSCN, and human serum albumin) produced a signal that could be interpreted as a false positive or a false negative for cyanide exposure. Most importantly, the sensor was 100% accurate in diagnosing cyanide poisoning for acutely exposed rabbits.

INHALATION TOXICOLOGY METHODS: The Generation and Characterization of Exposure Atmospheres and Inhalational Exposures

PubMed Central

Chen, Lung-Chi; Lippmann, Morton

2015-01-01

In this review, we outline the need for laboratory-based inhalation toxicology studies, the historical background on adverse health effects of airborne toxicants, and the benefits of advance planning for the building of analytic options into the study design to maximize the scientific gains to be derived from the investments in the study. We then discuss methods for: 1) the generation and characterization of exposure atmospheres for inhalation exposures in humans and laboratory animals; 2) their delivery and distribution into and within whole-body exposure chambers, head-only exposure chambers, face-masks, and mouthpieces or nasal catheters; 3) options for on-line functional assays during and between exposures; and 4) options for serial non-invasive assays of response. In doing so, we go beyond exposures to single agents and simple mixtures, and include methods for evaluating biological responses to complex environmental mixtures. We also emphasize that great care should be taken in the design and execution of such studies so that the scientific returns can be maximized both initially, and in follow-up utilization of archived samples of the exposure atmospheres, excreta, and tissues collected for histology. PMID:25645246

Distributed drift chamber design for rare particle detection in relativistic heavy ion collisions

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

Bellwied, R.; Bennett, M.J.; Bernardo, V.

2001-10-02

This report describes a multi-plane drift chamber that was designed and constructed to function as a topological detector for the BNL AGSE896 rare particle experiment. The chamber was optimized for good spatial resolution, two track separation, and a high uniform efficiency while operating in a 1.6 Tesla magnetic field and subjected to long term exposure from a 11.6 GeV/nucleon beam of 10**6 Au ions per second.

Toxicity of thermal degradation products of spacecraft materials

NASA Technical Reports Server (NTRS)

Lawrence, W. H.; Turner, J. E.; Sanford, C.; Foster, S.; Baldwin, E.; Oconnor, J.

1982-01-01

Three polymeric materials were evaluated for relative toxicity of their pyrolysis products to rats by inhalation: Y-7683 (LS 200), Y-7684 (Vonar 3 on Fiberglass), and Y-7685 (Vonar 3 on N W Polyester). Criteria employed for assessing relative toxicity were (1) lethality from in-chamber pyrolysis, (2) lethality from an outside-of-chamber pyrolysis MSTL Procedure, and (3) disruption of trained rats' shock-avoidance performance during sub-lethal exposures to in-chamber pyrolysis of the materials.

Avian inhalation exposure chamber

DOEpatents

Briant, James K.; Driver, Crystal J.

1992-01-01

An exposure system for delivering gaseous material ranging in particle size from 0.4 micrometers to 20.0 micrometers uniformly to the heads of experimental animals, primarily birds. The system includes a vertical outer cylinder and a central chimney with animal holding bottles connected to exposure ports on the vertical outer cylinder.

Decompression sickness rates for chamber personnel: case series from one facility.

PubMed

Brandt, Megan S; Morrison, Thomas O; Butler, William P

2009-06-01

During 2004, a case series of decompression sickness (DCS) meeting the definition of epidemic DCS was observed in the Shaw AFB Physiological Training Program. There were 10 cases of chamber-induced altitude DCS observed. Internal and external investigations focused on time, place, person, and environment. No temporal trend was observed. Chamber, masks, regulators, crew positions, and oxygen sources revealed no defects. Among the cases, mean age was 27 yr. Peak altitude in four cases was 35,000 ft and in the other six cases was 25,000 ft. Six had joint pain, one skin symptoms, and three neurological findings. Four were treated with 100% ground-level oxygen and six with hyperbaric oxygen. Four were students and six were inside observers (IO). Four were women and six men. In the IO, where four of the six were women, no gender effect was seen. Examining the IO monthly exposure load (exposures per month) against DCS suggested a dose-response relationship. This relationship held true when 4 yr of Shaw AFB IO data was studied. Indeed, Poisson regression analysis demonstrated a statistically significant 2.1-fold rise in DCS risk with each monthly exposure. Consequently, the number of exposures per month may need to be considered when devising IO schedules.

Wall Paint Exposure Assessment Model (WPEM)

EPA Pesticide Factsheets

WPEM uses mathematical models developed from small chamber data to estimate the emissions of chemicals from oil-based (alkyd) and latex wall paint which is then combined with detailed use, workload and occupancy data to estimate user exposure.

Method for sequentially processing a multi-level interconnect circuit in a vacuum chamber

NASA Technical Reports Server (NTRS)

Routh, D. E.; Sharma, G. C. (Inventor)

1984-01-01

An apparatus is disclosed which includes a vacuum system having a vacuum chamber in which wafers are processed on rotating turntables. The vacuum chamber is provided with an RF sputtering system and a dc magnetron sputtering system. A gas inlet introduces various gases to the vacuum chamber and creates various gas plasma during the sputtering steps. The rotating turntables insure that the respective wafers are present under the sputtering guns for an average amount of time such that consistency in sputtering and deposition is achieved. By continuous and sequential processing of the wafers in a common vacuum chamber without removal, the adverse affects of exposure to atmospheric conditions are eliminated providing higher quality circuit contacts and functional device.

Method for sequentially processing a multi-level interconnect circuit in a vacuum chamber

NASA Technical Reports Server (NTRS)

Routh, D. E.; Sharma, G. C. (Inventor)

1982-01-01

The processing of wafer devices to form multilevel interconnects for microelectronic circuits is described. The method is directed to performing the sequential steps of etching the via, removing the photo resist pattern, back sputtering the entire wafer surface and depositing the next layer of interconnect material under common vacuum conditions without exposure to atmospheric conditions. Apparatus for performing the method includes a vacuum system having a vacuum chamber in which wafers are processed on rotating turntables. The vacuum chamber is provided with an RF sputtering system and a DC magnetron sputtering system. A gas inlet is provided in the chamber for the introduction of various gases to the vacuum chamber and the creation of various gas plasma during the sputtering steps.

40 CFR 797.1950 - Mysid shrimp chronic toxicity test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... kill 50 percent of a test population during continuous exposure over a specified period of time. (6... with the test design into retention chambers within the test and the control chambers. Mysids in the... the definitive test. (ii) The mysids should be exposed to a series of widely spaced concentrations of...

Characterization of a Head-Only Aerosol Exposure System for Nonhuman Primates

DTIC Science & Technology

2010-01-01

Alicat Scientific). The flow used provided isokinetic sampling, assuming the presence of laminar flow at the filter inlet, so that the chamber...airflow measured at the chamber inlet using a Gilibrator flow meter (Sensidyne LP) was 29.79±0.88L/min (n= 10; CV=2.97%). With both the aerosol

Effects of genetic strain on stress-induced weight and body fat loss in rats: Application to air pollution research

EPA Science Inventory

Exposure to some air pollutants is suspected of contributing to obesity. Hazelton chambers are commonly used in air pollution studies but we found unexpected reductions in body weight and body fat of rats housed in Hazelton chambers under control conditions. We suspect that stres...

GAS-PHASE MASS TRANSFER MODEL FOR PREDICTING VOLATILE ORGANIC COMPOUND (VOC) EMISSION RATES FROM INDOOR POLLUTANT SOURCES

EPA Science Inventory

Analysis of the impact of sources on indoor pollutant concentrations and occupant exposure to indoor pollutants requires knowledge of the emission rates from the sources. Emission rates are often determined by chamber testing and the data from the chamber test are fitted to an em...

The use of three-dimensional printing to produce in vitro slice chambers

PubMed Central

Hyde, James; MacNicol, Melanie; Odle, Angela; Garcia-Rill, Edgar

2014-01-01

Background In recent years, 3D printing technology has become inexpensive and simple enough that any lab can own and use one of these printers. New Method We explored the potential use of 3D printers for quickly and easily producing in vitro slice chambers for patch clamp electrophysiology. Slice chambers were produced using five available plastics: ABS, PLA, Nylon 618, Nylon 680, and T-glase. These “lab-made” chambers were also made using stereolithography through a professional printing service (Shapeways). This study measured intrinsic membrane properties of neurons in the brain stem pedunculopontine nucleus (PPN) and layer V pyramidal neurons in retrosplenial cortex. Results Nylon 680 and T-glase significantly hyperpolarized PPN neurons. ABS increased input resistance, decreased action potential amplitude, and increased firing frequency in pyramidal cortical neurons. To test long term exposure to each plastic, human neuroblastoma SHSY5Y cell cultures were exposed to each plastic for 1 week. ABS decreased cell counts while Nylon 618 and Shapeways plastics eliminated cells. Primary mouse pituitary cultures were also tested for 24-hour exposure. ABS decreased cell counts while Nylon 618 and Shapeways plastics decreased cell counts. Comparison to Existing Methods Chambers can be quickly and inexpensively printed in the lab. ABS, PLA, Nylon 680, and T-glase plastics would suffice for many experiments instead of commercially produced slice chambers. Conclusions While these technologies are still in their infancy, they represent a powerful addition to the lab environment. With careful selection of print material, slice chambers can be quickly and inexpensively manufactured in the lab. PMID:25251556

Whole-body nanoparticle aerosol inhalation exposures.

PubMed

Yi, Jinghai; Chen, Bean T; Schwegler-Berry, Diane; Frazer, Dave; Castranova, Vince; McBride, Carroll; Knuckles, Travis L; Stapleton, Phoebe A; Minarchick, Valerie C; Nurkiewicz, Timothy R

2013-05-07

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter < 200 nm and a geometric standard deviation σg < 2.5 (5). The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size (6), which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria (5). A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m(3) whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm(3)) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m(3)). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpre and Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M/(Q*t), where Q is sampling flowrate (m(3)/min), and t is the sampling time (minute). The chamber pressure, temperature, relative humidity (RH), O2 and CO2 concentrations were monitored and controlled continuously. Nano-TiO2 aerosols collected on Nuclepore filters were analyzed with a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. In summary, we report that the nano-particle aerosols generated and delivered to our exposure chamber have: 1) steady mass concentration; 2) homogenous composition free of contaminants; 3) stable particle size distributions with a count-median aerodynamic diameter of 157 nm during aerosol generation. This system reliably and repeatedly creates test atmospheres that simulate occupational, environmental or domestic ENM aerosol exposures.

Whole-Body Nanoparticle Aerosol Inhalation Exposures

PubMed Central

Yi, Jinghai; Chen, Bean T.; Schwegler-Berry, Diane; Frazer, Dave; Castranova, Vince; McBride, Carroll; Knuckles, Travis L.; Stapleton, Phoebe A.; Minarchick, Valerie C.; Nurkiewicz, Timothy R.

2013-01-01

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter < 200 nm and a geometric standard deviation σg < 2.5 5. The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size 6, which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria 5. A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m3 whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm3) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m3). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpreand Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M/(Q*t), where Q is sampling flowrate (m3/min), and t is the sampling time (minute). The chamber pressure, temperature, relative humidity (RH), O2 and CO2 concentrations were monitored and controlled continuously. Nano-TiO2 aerosols collected on Nuclepore filters were analyzed with a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis. In summary, we report that the nano-particle aerosols generated and delivered to our exposure chamber have: 1) steady mass concentration; 2) homogenous composition free of contaminants; 3) stable particle size distributions with a count-median aerodynamic diameter of 157 nm during aerosol generation. This system reliably and repeatedly creates test atmospheres that simulate occupational, environmental or domestic ENM aerosol exposures. PMID:23685643

Chamber personnel's use of Nitrox 50 during hyperbaric oxygen treatment: a quality study--research report.

PubMed

Hansen, Marco B; Jansen, Tejs; Sifakis, Michael B; Hyldegaard, Ole; Jansen, Erik C

2013-01-01

We aimed to evaluate the feasibility and safety of using Nitrox 50 as breathing gas during attendance in a multiplace hyperbaric chamber. Paper logs between Jan.-Dec. 2011 were reviewed to analyze nitrogen gas-loading, actual bottom time, total bottom time and surface interval time. With the use of the Norwegian Diving Tables nitrogen gas-loading was converted to Repetitive Group Letters. Symptoms of decompression sickness and health problems related to hyperbaric exposures were registered at weekly staff meetings. The chamber personnel breathed chamber air or Nitrox 50. 1,207 hyperbaric exposures were distributed to five chamber attendants and technicians, 14 doctors, and six nurses. Nitrox 50 was inhaled on 978 occasions (81.0%). Median nitrogen gas-loading after first pressurization complied with Repetitive Group Letter A (range A-E), second to C (range A-F), third to D (range A-F), fourth to E (range C-H), fifth to F (range C-H), and sixth to E (range B-G). No symptoms of decompression sickness were reported (95% CI 0.00-0.33%). Breathing Nitrox 50 during repetitive hyperbaric sessions seems to be feasible and safe while meeting high demands in number of treatment sessions and patient flow and with fewer people employed in the hyperbaric unit.

Construction of vapor chambers used to expose mice to alcohol during the equivalent of all three trimesters of human development.

PubMed

Morton, Russell A; Diaz, Marvin R; Topper, Lauren A; Valenzuela, C Fernando

2014-07-13

Exposure to alcohol during development can result in a constellation of morphological and behavioral abnormalities that are collectively known as Fetal Alcohol Spectrum Disorders (FASDs). At the most severe end of the spectrum is Fetal Alcohol Syndrome (FAS), characterized by growth retardation, craniofacial dysmorphology, and neurobehavioral deficits. Studies with animal models, including rodents, have elucidated many molecular and cellular mechanisms involved in the pathophysiology of FASDs. Ethanol administration to pregnant rodents has been used to model human exposure during the first and second trimesters of pregnancy. Third trimester ethanol consumption in humans has been modeled using neonatal rodents. However, few rodent studies have characterized the effect of ethanol exposure during the equivalent to all three trimesters of human pregnancy, a pattern of exposure that is common in pregnant women. Here, we show how to build vapor chambers from readily obtainable materials that can each accommodate up to six standard mouse cages. We describe a vapor chamber paradigm that can be used to model exposure to ethanol, with minimal handling, during all three trimesters. Our studies demonstrate that pregnant dams developed significant metabolic tolerance to ethanol. However, neonatal mice did not develop metabolic tolerance and the number of fetuses, fetus weight, placenta weight, number of pups/litter, number of dead pups/litter, and pup weight were not significantly affected by ethanol exposure. An important advantage of this paradigm is its applicability to studies with genetically-modified mice. Additionally, this paradigm minimizes handling of animals, a major confound in fetal alcohol research.

Avian inhalation exposure chamber

DOEpatents

Briant, J.K.; Driver, C.J.

1992-05-05

An exposure system is designed for delivering gaseous material ranging in particle size from 0.4 micrometers to 20.0 micrometers uniformly to the heads of experimental animals, primarily birds. The system includes a vertical outer cylinder and a central chimney with animal holding bottles connected to exposure ports on the vertical outer cylinder. 2 figs.

Effect of ozone exposure on seasonal gas exchange of five western conifers

Treesearch

Nancy E. Grulke; Paul R. Miller; Theodor D. Leininger

1998-01-01

Five species of western conifers (Pinus ponderosa, Abies concolor, Pseudotsuga menziesii, Abies lasiocarpa, and Picea engelmannii) were exposed, in two standard open-top exposure chambers per treatment, to charcoal-filtered air and a simulated diurnal ozone exposure profile (120 d sum of 136 ppm-h) to test their relative...

Development of a Fluorescence-Based Sensor for Rapid Diagnosis of Cyanide Exposure

PubMed Central

2015-01-01

Although commonly known as a highly toxic chemical, cyanide is also an essential reagent for many industrial processes in areas such as mining, electroplating, and synthetic fiber production. The “heavy” use of cyanide in these industries, along with its necessary transportation, increases the possibility of human exposure. Because the onset of cyanide toxicity is fast, a rapid, sensitive, and accurate method for the diagnosis of cyanide exposure is necessary. Therefore, a field sensor for the diagnosis of cyanide exposure was developed based on the reaction of naphthalene dialdehyde, taurine, and cyanide, yielding a fluorescent β-isoindole. An integrated cyanide capture “apparatus”, consisting of sample and cyanide capture chambers, allowed rapid separation of cyanide from blood samples. Rabbit whole blood was added to the sample chamber, acidified, and the HCN gas evolved was actively transferred through a stainless steel channel to the capture chamber containing a basic solution of naphthalene dialdehyde (NDA) and taurine. The overall analysis time (including the addition of the sample) was <3 min, the linear range was 3.13–200 μM, and the limit of detection was 0.78 μM. None of the potential interferents investigated (NaHS, NH4OH, NaSCN, and human serum albumin) produced a signal that could be interpreted as a false positive or a false negative for cyanide exposure. Most importantly, the sensor was 100% accurate in diagnosing cyanide poisoning for acutely exposed rabbits. PMID:24383576

Effect of controlled adverse chamber environment exposure on tear functions in silicon hydrogel and hydrogel soft contact lens wearers.

PubMed

Kojima, Takashi; Matsumoto, Yukihiro; Ibrahim, Osama M A; Wakamatsu, Tais Hitomi; Uchino, Miki; Fukagawa, Kazumi; Ogawa, Junko; Dogru, Murat; Negishi, Kazuno; Tsubota, Kazuo

2011-11-11

To prospectively evaluate the effect of controlled adverse chamber environment (CACE) exposure on tear function, including tear osmolarity, in subjects wearing narafilcon A versus those wearing etafilcon A soft contact lens (SCL). Thirty-one healthy subjects with no history of contact lens wear (13 women, 18 men; average age, 30.5 ± 6.5 years) were randomly divided into age- and sex-matched groups (15 subjects wearing narafilcon A SCL; 16 subjects wearing etafilcon A SCL) and entered a CACE for 20 minutes. All subjects underwent tear osmolarity, tear evaporation rate, strip meniscometry, tear film breakup time, fluorescein vital staining, and functional visual acuity measurement before and after exposure to the controlled adverse chamber. The mean blink rate increased with significant deteriorations in the mean symptom VAS scores, mean tear osmolarity, tear evaporation rate, strip meniscometry score, and tear stability with CACE exposure along with a decrease in visual maintenance ratio in functional visual acuity testing in etafilcon A wearers. The mean symptom VAS scores, mean tear evaporation rate, tear stability, blink rates, and visual maintenance ratios did not change significantly in narafilcon A wearers after CACE exposure. This study suggested marked tear instability, higher tear osmolarity, and increased tear evaporation with marked dry eye and visual symptomatology in nonadapted hydrogel SCL wearers, suggesting that silicone hydrogel SCLs may be suitable for persons who live and work in cool, low-humidity, and windy environments, as tested in this study.

Analysis of Heat Stress and the Indoor Climate Control Requirements for Movable Refuge Chambers

PubMed Central

Hao, Xiaoli; Guo, Chenxin; Lin, Yaolin; Wang, Haiqiao; Liu, Heqing

2016-01-01

Movable refuge chambers are a new kind of rescue device for underground mining, which is believed to have a potential positive impact on reducing the rate of fatalities. It is likely to be hot and humid inside a movable refuge chamber due to the metabolism of trapped miners, heat generated by equipment and heat transferred from outside. To investigate the heat stress experienced by miners trapped in a movable refuge chamber, the predicted heat strain (PHS) model was used to simulate the heat transfer process between the person and the thermal environment. The variations of heat stress with the temperature and humidity inside the refuge chamber were analyzed. The effects of air temperature outside the refuge chamber and the overall heat transfer coefficient of the refuge chamber shell on the heat stress inside the refuge chamber was also investigated. The relationship between the limit of exposure duration and the air temperature and humidity was numerically analyzed to determine the upper limits of temperature and humidity inside a refuge chamber. Air temperature of 32 °C and relative humidity of 70% are recommended as the design standard for internal thermal environment control of movable refuge chambers. PMID:27213422

Analysis of Heat Stress and the Indoor Climate Control Requirements for Movable Refuge Chambers.

PubMed

Hao, Xiaoli; Guo, Chenxin; Lin, Yaolin; Wang, Haiqiao; Liu, Heqing

2016-05-20

Movable refuge chambers are a new kind of rescue device for underground mining, which is believed to have a potential positive impact on reducing the rate of fatalities. It is likely to be hot and humid inside a movable refuge chamber due to the metabolism of trapped miners, heat generated by equipment and heat transferred from outside. To investigate the heat stress experienced by miners trapped in a movable refuge chamber, the predicted heat strain (PHS) model was used to simulate the heat transfer process between the person and the thermal environment. The variations of heat stress with the temperature and humidity inside the refuge chamber were analyzed. The effects of air temperature outside the refuge chamber and the overall heat transfer coefficient of the refuge chamber shell on the heat stress inside the refuge chamber was also investigated. The relationship between the limit of exposure duration and the air temperature and humidity was numerically analyzed to determine the upper limits of temperature and humidity inside a refuge chamber. Air temperature of 32 °C and relative humidity of 70% are recommended as the design standard for internal thermal environment control of movable refuge chambers.

Effects of open-top chambers on Valencia' orange trees. [Citrus sinensis

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

Olszyk, D.M.; Takemoto, B.K.; Kats, G.

Open-top field chambers are the most widely used technology for evaluating the impacts of air pollutants on vegetation. This study was conducted to evaluate the long-term effects of chambers on Valencia orange trees (Citrus sinensis (L.) Osbeck). The trees were exposed to ambient ozone (O{sub 3}) for 51 months in large (4.3-m diam. by 2.9-m high) nonfiltered open-top chambers (NF) and in ambient air without chambers (AA). Results suggest that the yield increases for NF compared to AA trees could, in part, be accounted for by decreased flux of O{sub 3} into leaves (based on decreased O{sub 3} exposure andmore » leaf conductance). However, other factors, i.e., increased tree growth, altered leaf C allocation, and lack of wind stress occurring only in chambers, likely contributed to higher NF tree yields.« less

Moving bed reactor for solar thermochemical fuel production

DOEpatents

Ermanoski, Ivan

2013-04-16

Reactors and methods for solar thermochemical reactions are disclosed. Embodiments of reactors include at least two distinct reactor chambers between which there is at least a pressure differential. In embodiments, reactive particles are exchanged between chambers during a reaction cycle to thermally reduce the particles at first conditions and oxidize the particles at second conditions to produce chemical work from heat. In embodiments, chambers of a reactor are coupled to a heat exchanger to pre-heat the reactive particles prior to direct exposure to thermal energy with heat transferred from reduced reactive particles as the particles are oppositely conveyed between the thermal reduction chamber and the fuel production chamber. In an embodiment, particle conveyance is in part provided by an elevator which may further function as a heat exchanger.

Changes in growth, leaf abscission, and biomass associated with seasonal tropospheric ozone exposures of Populus tremuloides clones and seedlings

Treesearch

D.F. Karnosky; Z.E. Gagnon; R.E. Dickson; M.D. Coleman; E.H. Lee; J.G. Isebrands

1996-01-01

The effects of single-season tropospheric ozone (03) exposures on growth, leaf abscission, and biomass of trembling aspen (Populus tremuloides Michx.) rooted cuttings and seedlings were studied. Plants were grown in the Upper Peninsula of Michigan in open-top chambers with 03 exposures that ranged from...

Temperature changes in the pulp chamber during dentin ablation with Er:YAG laser

NASA Astrophysics Data System (ADS)

Zhang, Xianzeng; Zhao, Haibin; Zhan, Zhenlin; Guo, Wenqing; Xie, Shusen

2012-12-01

To examine the temperature changes in the pulp chamber during cavity preparation in dentin with the Er:YAG laser (2940 nm), a total 20 intact premolars teeth were divided into 4 groups for dentin ablation with different radiant exposures at 4Hz and 8Hz with and without water spray. A K-type thermocouple was used to monitor the temperature changes in pulp chamber during laser treatment. The total time of irradiation was 70 sec. the water spray rate was 3 mL/min. It showed that maximum temperature rise increases with the increasing of radiant exposure and pulse repetition rate and the additional water cooling during laser ablation can significantly reduce the temperature rise in pulp chamber which will benefit to avoid or reduce thermal damage to tooth structure and dental pulp. The highest rise of temperature in the pulp was achieved with 20 J/cm2 and 8 Hz (19.83°C ). For all sample without water spray, the rise of temperature was exceed 5 °C . In contrast, with water spray, the temperature rise in the pulp can be firmly controlled under 1°C. The results also indicated that ablation rate and efficiency can be enhanced by increasing the incident radiant exposure and pulse repetition rate, which simultaneously producing more heat accumulation in dental tissue and causing thermal damage to dental tissue. By applying an additional water spray, thermal damage can be significantly reduced in clinical application.

OBSERVATIONS OF HIGH-ENERGY COSMIC-RAY ELECTRONS FROM 30 GeV TO 3 TeV WITH EMULSION CHAMBERS

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

Kobayashi, T.; Komori, Y.; Yoshida, K.

2012-12-01

We have performed a series of cosmic-ray electron observations using balloon-borne emulsion chambers since 1968. While we previously reported the results from subsets of the exposures, the final results of the total exposures up to 2001 are presented here. Our successive experiments have yielded a total exposure of 8.19 m{sup 2} sr day at altitudes of 4.0-9.4 g cm{sup -2}. The performance of the emulsion chambers was examined by accelerator beam tests and Monte Carlo simulations, and the on-board calibrations were carried out by using the flight data. In this work, we present the cosmic-ray electron spectrum in the energymore » range from 30 GeV to 3 TeV at the top of the atmosphere, which is well represented by a power-law function with an index of -3.28 {+-} 0.10. The observed data can also be interpreted in terms of diffusive propagation models. The evidence of cosmic-ray electrons up to 3 TeV suggests the existence of cosmic-ray electron sources at distances within {approx}1 kpc and times within {approx}1 Multiplication-Sign 10{sup 5} yr ago.« less

Solar retorting of oil shale

DOEpatents

Gregg, David W.

1983-01-01

An apparatus and method for retorting oil shale using solar radiation. Oil shale is introduced into a first retorting chamber having a solar focus zone. There the oil shale is exposed to solar radiation and rapidly brought to a predetermined retorting temperature. Once the shale has reached this temperature, it is removed from the solar focus zone and transferred to a second retorting chamber where it is heated. In a second chamber, the oil shale is maintained at the retorting temperature, without direct exposure to solar radiation, until the retorting is complete.

Modern dosimetric tools for 60Co irradiation at high containment laboratories

PubMed Central

Twardoski, Barri; Feldmann, Heinz; Bloom, Marshall E.; Ward, Joe

2011-01-01

Purpose To evaluate an innovative photo-fluorescent film as a routine dosimetric tool during 60Co irradiations at a high containment biological research laboratory, and to investigate whether manufacturer-provided chamber exposure rates can be used to accurately administer a prescribed dose to biological specimens. Materials and methods Photo-fluorescent, lithium fluoride film dosimeters and National Institutes of Standards and Technology (NIST) transfer dosimeters were co-located in a self-shielded 60Co irradiator and exposed to γ-radiation with doses ranging from 5–85 kGy. Film dose-response relationships were developed for varying temperatures simulating conditions present when irradiating infectious biological specimens. Dose measurement results from NIST transfer dosimeters were compared to doses predicted using manufacturer-provided irradiator chamber exposure rates. Results The film dosimeter exhibited a photo-fluorescent response signal that was consistent and nearly linear in relationship to γ-radiation exposure over a wide dose range. The dosimeter response also showed negligible effects from dose fractionization and humidity. Significant disparities existed between manufacturer-provided chamber exposure rates and actual doses administered. Conclusion This study demonstrates the merit of utilizing dosimetric tools to validate the process of exposing dangerous and exotic biological agents to γ-radiation at high containment laboratories. The film dosimeter used in this study can be utilized to eliminate potential for improperly administering γ-radiation doses. PMID:21961968

Pattern of deposition of stainless steel welding fume particles inhaled into the respiratory systems of Sprague-Dawley rats exposed to a novel welding fume generating system.

PubMed

Yu, I J; Kim, K J; Chang, H K; Song, K S; Han, K T; Han, J H; Maeng, S H; Chung, Y H; Park, S H; Chung, K H; Han, J S; Chung, H K

2000-07-27

In order to investigate occupational diseases related to welding fume exposure, such as nasal septum perforation, pneumoconiosis and manganese intoxication, we built a welding fume exposure system that included a welding fume generator, exposure chamber and fume collector. The fume concentrations in the exposure chamber were monitored every 15 min during a 2-h exposure. Fume (mg/m(3)) concentrations of major metals, including Fe, Mn, Cr, and Ni were found to be consistently maintained. An acute inhalation toxicity study was conducted by exposing male Sprague-Dawley rats to the welding fumes generated in this apparatus by stainless steel arc welding. The rats were exposed in the inhalation chamber to a welding fume with a concentration of 62 mg/m(3) total suspended particulates for 4 h. Animals were sacrificed at 4 h and at 1, 3, 7, 10, and 14 days after exposure. Histopathological examinations were conducted on the animals' upper respiratory tracts, including the nasal pathway and the conducting airway, and on the gas exchange region including the alveolar ducts, alveolar sacs, and alveoli. Diameters of fume particles varied from 0.02 to 0.81 microm and were distributed log normally, with a mean diameter of 0.1 microm and geometric standard deviation of 1.42. Rats exposed to the welding fume for 4 h did not show any significant respiratory system toxicity. The mean particle diameter of 0.1 microm resulted in little adsorption of the welding fume particles in the upper respiratory tract. Particle adsorption took place principally in the lower respiratory tracts, including bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Development of a dose-controlled multiculture cell exposure chamber for efficient delivery of airborne and engineered nanoparticles

NASA Astrophysics Data System (ADS)

Asimakopoulou, Akrivi; Daskalos, Emmanouil; Lewinski, Nastassja; Riediker, Michael; Papaioannou, Eleni; Konstandopoulos, Athanasios G.

2013-04-01

In order to study the various health influencing parameters related to engineered nanoparticles as well as to soot emitted by Diesel engines, there is an urgent need for appropriate sampling devices and methods for cell exposure studies that simulate the respiratory system and facilitate associated biological and toxicological tests. The objective of the present work was the further advancement of a Multiculture Exposure Chamber (MEC) into a dose-controlled system for efficient delivery of nanoparticles to cells. It was validated with various types of nanoparticles (Diesel engine soot aggregates, engineered nanoparticles for various applications) and with state-of-the-art nanoparticle measurement instrumentation to assess the local deposition of nanoparticles on the cell cultures. The dose of nanoparticles to which cell cultures are being exposed was evaluated in the normal operation of the in vitro cell culture exposure chamber based on measurements of the size specific nanoparticle collection efficiency of a cell free device. The average efficiency in delivering nanoparticles in the MEC was approximately 82%. The nanoparticle deposition was demonstrated by Transmission Electron Microscopy (TEM). Analysis and design of the MEC employs Computational Fluid Dynamics (CFD) and true to geometry representations of nanoparticles with the aim to assess the uniformity of nanoparticle deposition among the culture wells. Final testing of the dose-controlled cell exposure system was performed by exposing A549 lung cell cultures to fluorescently labeled nanoparticles. Delivery of aerosolized nanoparticles was demonstrated by visualization of the nanoparticle fluorescence in the cell cultures following exposure. Also monitored was the potential of the aerosolized nanoparticles to generate reactive oxygen species (ROS) (e.g. free radicals and peroxides generation), thus expressing the oxidative stress of the cells which can cause extensive cellular damage or damage on DNA.

Are Urinary PAHs Biomarkers of Controlled Exposure to Diesel Exhaust?

EPA Science Inventory

Urinary polycyclic aromatic hydrocarbons (PAHs) were evaluated as possible biomarkers of exposure to diesel exhaust (DE) in two controlled-chamber studies. We report levels of 14 PAHs from 28 subjects in urine that were collected before, immediately after and the morning after ex...

Long-term repetitive sodium lauryl sulfate-induced irritation of the skin: an in vivo study.

PubMed

Branco, Nara; Lee, Ivy; Zhai, Hongbo; Maibach, Howard I

2005-11-01

Skin may adapt to topical irritants through accommodation. This study focuses on long-term exposure to irritants and attempts to demonstrate accommodation. Sodium lauryl sulfate (SLS) induced irritant contact dermatitis at 3 concentrations (0.025% to 0.075%). Distilled water, acetone and an empty chamber served as controls. Experimental compounds were applied to forearms of 7 healthy volunteers for 24 hr before replacing by a fresh chamber for 6 non-consecutive weeks over 103 days. Possible accommodation was quantified by visual scoring (erythema and dryness) and by bioengineering parameters: transepidermal water loss (TEWL), capacitance, chromametry and laser Doppler flowmetry (LDF). Significant erythema, dryness, elevated TEWL, skin colour reflectance and LDF values occurred during the exposure periods. Upon repeat exposure, an immediate and augmented response in erythema, TEWL, skin colour reflectance and LDF developed. However, irritant skin changes were not sustained. Irritation parameters return to baseline after cessation of exposure. There was no evidence of sustained irritation or accommodation after the last exposure. Study findings do not document sustained accommodation or adaptive hyposensitivity after long-term repetitive irritant exposure under these test conditions. Alternative models should be developed to prove or disprove the accommodation hypothesis.

A new passive radon-thoron discriminative measurement system.

PubMed

Sciocchetti, G; Sciocchetti, A; Giovannoli, P; DeFelice, P; Cardellini, F; Cotellessa, G; Pagliari, M

2010-10-01

A new passive radon-thoron discriminative measurement system has been developed for monitoring radon and thoron individually. It consists of a 'couple' of passive integrating devices with a CR39 nuclear track detector (NTD). The experimental prototype is based on the application of a new concept of NTD instrument developed at ENEA, named Alpha-PREM, acronym of piston radon exposure meter, which allows controlling the detector exposure with a patented sampling technique (Int. Eu. Pat. and US Pat.). The 'twin diffusion chambers system' was based on two A-PREM devices consisting of the standard device, named NTD-Rn, and a modified version, named NTD-Rn/Tn, which was set up to improve thoron sampling efficiency of the diffusion chamber, without changing the geometry and the start/stop function of the NTD-Rn device. Coupling devices fitted on each device allowed getting a system, which works as a double-chamber structure when deployed at the monitoring position. In this paper both technical and physical aspects are considered.

Morphological changes and viability of primary cultured human ocular trabecular meshwork cells after exposure to air.

PubMed

Kopsachilis, Nikolaos; Tsaousis, Konstantinos T; Carifi, Gianluca; Welge-Luessen, Ulrich

2014-06-01

To investigate the possible toxic effect of air exposure for an in vitro model of primary human ocular trabecular meshwork cells (HTM). HTM were isolated from five donor eyes and cultivated at 37 °C. After reaching confluence the cells were seeded on two well chamber slides. The chamber slides were turned upside down in a Petri culture dish full of culture medium and filled with air using a 5 ml syringe, starting this way the exposure of the cells to the air. Subsequently they were placed in the incubation chamber at 37 °C. Six groups of HTM cultures were set up: group 1 consisted of samples in which HTM were exposed to air for 30 min, group 2 for 1 h, group 3 for 3 h, group 4 for 6 h, group 5 for 12 h and group 6 for 24 h. At 3 h after exposure, the morphology of the cells was still intact, at 6 h few cells appeared deformed and exhibited characteristics of more senescent cells. At 12 h after exposure to air the HTM cells started losing their typical morphology and appeared enlarged and compromised. Viability was superior to 94% in groups 1-3 while for groups 4, 5, 6 it was 82.7%, 39.5% and 12.7% respectively. The toxic effect of air exposure for the studied in vitro model of HTM is not significant for the time period of one to three hours. However it starts reducing viability and alternating morphology 6 h after exposure until the time period of 24 h, where the percentage of living cells is drastically decreased. Therefore, we suggest that the use of an air bubble especially in glaucomatous patients should be applied with caution. Copyright © 2014 Elsevier Ltd. All rights reserved.

The use of decompression to simulate the effect of extravehicular activity on human lymphocyte transformation

NASA Technical Reports Server (NTRS)

Meehan, R. T.; Duncan, U.; Neale, L.; Waligora, J.; Taylor, G. R.

1986-01-01

Lymphocytes from 35 subjects participating in a chamber study simulating extravehicular activity (EVA) conditions were studied. No significant differences in H3 thymidine uptake between pre chamber and post chamber response to any mitogens autologous plasma, or among circulating mononuclear cells by flow cytometry are observed. The studies could not identify the subjects who developed venous bubbles. Data from eight subjects suggests that acute stress associated with participating in the study augments in vitro lymphocyte proliferation. Results indicate EVA exposure does not greatly influence space-flight induced alterations in immune effector cell function.

Functionalization of Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2007-01-01

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2, or F2, or CnHm) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

Functionalization of carbon nanotubes

NASA Technical Reports Server (NTRS)

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2007-01-01

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H.sub.2 or F.sub.2 or C.sub.nH.sub.m) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec.

All-aluminum-alloy UHV chamber for molecular beam epitaxy, 1

NASA Astrophysics Data System (ADS)

Suemitsu, M.; Miyamoto, N.

1984-03-01

The first all aluminum alloy (ex. JIS.6263-t6,2219-t87 etc) MBE chamber is constructed and described. After exposure to atmosphere, the chamber is drown to 10(-9) torr in 24 hours, and reaches an ultrahigh vacuum of 1.6x10(-10) torr by a 115 C, 24 bakeout process. The light weight and low cost as well as the short pump-down time and the law outgassing rate of the all aluminum alloy vacuum system seems to have a considerable applicative potentiality for equipment used in semiconductor ultrahigh vacuum processes.

Extinction of conditioned opiate withdrawal in rats in a two-chambered place conditioning apparatus

PubMed Central

Myers, Karyn M.; Bechtholt-Gompf, Anita J.; Coleman, Brian R.; Carlezon, William A.

2016-01-01

Conditioned opiate withdrawal contributes to relapse in addicts and can be studied in rats using the opiate withdrawal-induced conditioned place aversion (OW-CPA) paradigm. Attenuation of conditioned withdrawal through extinction may be beneficial in the treatment of addiction. Here we describe a protocol for studying OW-CPA extinction using a two-chambered place conditioning apparatus. Rats are made dependent on morphine through subcutaneous implantation of morphine pellets and then trained to acquire OW-CPA through pairings of one chamber with naloxone-precipitated withdrawal and the other chamber with saline. Extinction training consists of re-exposures to both chambers in the absence of precipitated withdrawal. Rats tested following the completion of training show a decline in avoidance of the formerly naloxone-paired chamber with increasing numbers of extinction training sessions. The protocol takes a minimum of seven days; the exact duration varies with the amount of extinction training, which is determined by the goals of the experiment. PMID:22362157

Response of selected plant and insect species to simulated solid rocket exhaust mixtures and to exhaust components from solid rocket fuels

NASA Technical Reports Server (NTRS)

Heck, W. W.; Knott, W. M.; Stahel, E. P.; Ambrose, J. T.; Mccrimmon, J. N.; Engle, M.; Romanow, L. A.; Sawyer, A. G.; Tyson, J. D.

1980-01-01

The effects of solid rocket fuel (SRF) exhaust on selected plant and and insect species in the Merritt Island, Florida area was investigated in order to determine if the exhaust clouds generated by shuttle launches would adversely affect the native, plants of the Merritt Island Wildlife Refuge, the citrus production, or the beekeeping industry of the island. Conditions were simulated in greenhouse exposure chambers and field chambers constructed to model the ideal continuous stirred tank reactor. A plant exposure system was developed for dispensing and monitoring the two major chemicals in SRF exhaust, HCl and Al203, and for dispensing and monitoring SRF exhaust (controlled fuel burns). Plants native to Merritt Island, Florida were grown and used as test species. Dose-response relationships were determined for short term exposure of selected plant species to HCl, Al203, and mixtures of the two to SRF exhaust.

Study of toxicological evaluation of fire suppressants and extinguishers

NASA Technical Reports Server (NTRS)

1975-01-01

The application of fluorocarbons as possible candidates for fire extinguishers and/or suppressants in confined spaces (such as spacecraft, aircraft, or submarines) was investigated, with special emphasis on their safety to man since they would be inhaled on an almost continuous basis. Short-term exposure experiments, using various animal species, were devised to look at specific parameters in order to determine which of the candidate compounds were sufficiently non-toxic to warrant long-term investigations. The following physiologic criteria were examined; tissue distribution, fluoride concentration, effect on mitochondria, microsomes, liposomes, and liver cell nuclei, erythrocyte fragility, clinical chemistry values, hematology, pathology, cardiac sensitization, behavioral effects. Various rodent species were used for initial investigations, with non-human primate exposures for Freon 116 which was warranted for negative results on rodents. Various types of exposure chambers were used, including closed dynamic chambers allowing for a recirculating atmosphere.

Voluntary inhalation of methamphetamine: a novel strategy for studying intake non-invasively.

PubMed

Juarez-Portilla, C; Kim, R D; Robotham, M; Tariq, M; Pitter, M; LeSauter, J; Silver, R

2017-03-01

The abuse of the psychostimulant methamphetamine (MA) is associated with substantial costs and limited treatment options. To understand the mechanisms that lead to abuse, animal models of voluntary drug intake are crucial. We aimed to develop a protocol to study long-term non-invasive voluntary intake of MA in mice. Mice were maintained in their home cages and allowed daily 1 h access to an attached tunnel leading to a test chamber in which nebulized MA was available. Restated, if they went to the nebulizing chamber, they self-administered MA by inhalation. This protocol was compared to injected and to imposed exposure to nebulized MA, in a series of seven experiments. We established a concentration of nebulized MA at which motor activity increases following voluntary intake resembled that following MA injection and imposed inhalation. We found that mice regulated their exposure to MA, self-administering for shorter durations when concentrations of nebulized MA were increased. Mice acquire the available MA by repeatedly running in and out of the nebulizing chamber for brief bouts of intake. Such exposure to nebulized MA elevated plasma MA levels. There was limited evidence of sensitization of locomotor activity. Finally, blocking access to the wheel did not affect time spent in the nebulizing chamber. We conclude that administration of MA by nebulization is an effective route of self-administration, and our new protocol represents a promising tool for examining the transitions from first intake to long-term use and its behavioral and neural consequences in a non-invasive protocol.

A method for exposing rodents to resuspended particles using whole-body plethysmography

PubMed Central

Wichers, Lindsay B; Ledbetter, Allen D; McGee, John K; Kellogg, Robert B; Rowan, William H; Nolan, Julianne P; Costa, Daniel L; Watkinson, William P

2006-01-01

Background Epidemiological studies have reported increased risks of cardiopulmonary-related hospitalization and death in association with exposure to elevated levels of particulate matter (PM) across a wide range of urban areas. In response to these findings, researchers have conducted animal inhalation exposures aimed at reproducing the observed toxicologic effects. However, it is technically difficult to quantitate the actual amount of PM delivered to the lung in such studies, and dose is frequently estimated using default respiration parameters. Consequently, the interpretation of PM-induced effects in rodents exposed via whole-body inhalation is often compromised by the inability to determine deposited dose. To address this problem, we have developed an exposure system that merges the generation of dry, aerosolized particles with whole-body plethysmography (WBP), thus permitting inhalation exposures in the unrestrained rat while simultaneously obtaining data on pulmonary function. Results This system was validated using an oil combustion-derived particle (HP12) at three nominal concentrations (3, 12, and 13 mg/m3) for four consecutive exposure days (6 hr/day); a single 6-hour exposure to 13 mg/m3 of HP12 was also conducted. These results demonstrated that the system was both reliable and consistent over these exposure protocols, achieving average concentrations that were within 10% of the targeted concentration. In-line filters located on the exhaust outlets of individual WBP chambers showed relative agreement in HP12 mass for each day and were not statistically different when compared to one another (p = 0.16). Temperatures and relative humidities were also similar between chambers during PM and air exposures. Finally, detailed composition analyses of both HP12 filter and bulk samples showed that grinding and aerosolization did not change particle chemistry. Conclusion The results of this study demonstrate that it is possible to expose rodents to resuspended, dry PM via whole-body inhalation while these animals are maintained in WBP chambers. This new methodology should significantly improve the ability to assess dosimetry under minimally stressful exposure conditions. PMID:16911796

Biomass fuel smoke exposure was associated with adverse cardiac remodeling and left ventricular dysfunction in Peru.

PubMed

Burroughs Peña, M S; Velazquez, E J; Rivera, J D; Alenezi, F; Wong, C; Grigsby, M; Davila-Roman, V G; Gilman, R H; Miranda, J J; Checkley, W

2017-07-01

While household air pollution from biomass fuel combustion has been linked to cardiovascular disease, the effects on cardiac structure and function have not been well described. We sought to determine the association between biomass fuel smoke exposure and cardiac structure and function by transthoracic echocardiography. We identified a random sample of urban and rural residents living in the high-altitude region of Puno, Peru. Daily biomass fuel use was self-reported. Participants underwent transthoracic echocardiography. Multivariable linear regression was used to examine the relationship of biomass fuel use with echocardiographic measures of cardiac structure and function, adjusting for age, sex, height, body mass index, diabetes, physical activity, and tobacco use. One hundred and eighty-seven participants (80 biomass fuel users and 107 non-users) were included in this analysis (mean age 59 years, 58% women). After adjustment, daily exposure to biomass fuel smoke was associated with increased left ventricular internal diastolic diameter (P=.004), left atrial diameter (P=.03), left atrial area (four-chamber) (P=.004) and (two-chamber) (P=.03), septal E' (P=.006), and lateral E' (P=.04). Exposure to biomass fuel smoke was also associated with worse global longitudinal strain in the two-chamber view (P=.01). Daily biomass fuel use was associated with increased left ventricular size and decreased left ventricular systolic function by global longitudinal strain. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Apparatus for in situ determination of burnup, cooling time and fissile content of an irradiated nuclear fuel assembly in a fuel storage pond

DOEpatents

Phillips, John R.; Halbig, James K.; Menlove, Howard O.; Klosterbuer, Shirley F.

1985-01-01

A detector head for in situ inspection of irradiated nuclear fuel assemblies submerged in a water-filled nuclear fuel storage pond. The detector head includes two parallel arms which extend from a housing and which are spaced apart so as to be positionable on opposite sides of a submerged fuel assembly. Each arm includes an ionization chamber and two fission chambers. One fission chamber in each arm is enclosed in a cadmium shield and the other fission chamber is unshielded. The ratio of the outputs of the shielded and unshielded fission chambers is used to determine the boron content of the pond water. Correcting for the boron content, the neutron flux and gamma ray intensity are then used to verify the declared exposure, cooling time and fissile material content of the irradiated fuel assembly.

Facility and Methods Developed for Simulated Space Vacuum Ultraviolet Exposure Testing of Polymer Films

NASA Technical Reports Server (NTRS)

Dever, Joyce A.; Pietromica, Anthony J.; Stueber, Thomas J.; Sechkar, Edward A.; Messer, Russell K.

2002-01-01

Vacuum ultraviolet (VUV) radiation of wavelengths between 115 and 200 nm produced by the Sun in the space environment can degrade polymer films, producing changes in their optical, mechanical, and chemical properties. These effects are particularly important for thin polymer films being considered for ultralightweight space structures, because, for most polymers, VUV radiation is absorbed in a thin surface layer. The NASA Glenn Research Center has developed facilities and methods for long-term ground testing of polymer films to evaluate space environmental VUV radiation effects. VUV exposure can also be used as part of combined or sequential simulated space environmental exposures to determine combined damaging effects with other aspects of the space environment, which include solar ultraviolet radiation, solar flare x-rays, electron and proton radiation, atomic oxygen (for low-Earth-orbit missions), and temperature effects. Because the wavelength sensitivity of VUV damage is not well known for most materials, Glenn's VUV facility uses a broad-spectrum deuterium lamp with a magnesium fluoride window that provides output between 115 and 200 nm. Deuterium lamps of this type were characterized by the National Institute of Standards and Technology and through measurements at Glenn. Spectral irradiance measurements show that from approximately 115 to 160 nm, deuterium lamp irradiance can be many times that of air mass zero solar irradiance, and as wavelength increases above approximately 160 nm, deuterium lamp irradiance decreases in comparison to the Sun. The facility is a cryopumped vacuum chamber that achieves a system pressure of approximately 5310(exp -6) torr. It contains four individual VUV-exposure compartments in vacuum, separated by water-cooled copper walls to minimize VUV radiation and any sample contamination cross interactions between compartments. Each VUV-exposure compartment contains a VUV deuterium lamp, a motor-controlled sample stage coupled with a moveable cesium iodide VUV phototube, and two thermocouples for temperature measurement. The vacuum chamber and exterior equipment is shown. Each VUV lamp is located at the top of the chamber with its projection-tube pushed through an O-ring compression fitting. The lamp assemblies are located on ports that can be isolated from the rest of the vacuum chamber, permitting maintenance or replacement of the lamps without breaking vacuum in the main chamber where the samples are located. A view of two of the four interior VUV-exposure compartments, including the moveable sample stages and detector holders is also shown. Glenn is using this facility to support testing of Next Generation Space Telescope sunshield materials that is being led by the NASA Goddard Space Flight Center and to develop an understanding of the wavelength, intensity, and temperature dependence of VUV-induced polymer degradation.

Adrenal hormones interact with sympathetic innervation to modulate growth of embryonic heart in oculo.

PubMed

Tucker, D C; Torres, A

1992-02-01

To allow experimental manipulation of adrenal hormone and autonomic influences on developing myocardium without alteration of hemodynamic load, embryonic rat heart was cultured in the anterior eye chamber of an adult rat. Sympathetic innervation of embryonic day 12 heart grafts was manipulated by surgical sympathectomy of one eye chamber in each host rat. Adrenal hormone exposure was manipulated by host adrenal medullectomy (MEDX) in experiment 1 and by host adrenalectomy (ADX) in experiment 2. In experiment 1, whole heart grafts were larger in MEDX than in sham-operated hosts by 8 wk in oculo (6.14 +/- 0.71 vs. 5.09 +/- 0.69 mm2 with innervation intact and 7.97 +/- 2.07 vs. 3.09 +/- 0.63 mm2 with sympathetic innervation prevented). In experiment 2, host ADX increased growth of embryonic day 12 ventricles grafted into sympathectomized eye chambers (0.69 +/- 0.10 vs. 0.44 +/- 0.04 mm2) but did not affect growth of grafts in intact eye chambers (0.85 +/- 0.09 vs. 1.05 +/- 0.15 mm2). Corticosterone replacement (4 mg/day) entirely reversed the effect of host ADX on graft growth (superior cervical ganglionectomy, 0.47 +/- 0.03 mm2; intact eye chambers, 0.90 +/- 0.91 mm2). Beating rate of grafts was not affected by adrenal hormone manipulations. These experiments indicate that the compromised growth of embryonic heart grafts placed in sympathectomized eye chambers requires exposure to adult levels of glucocorticoids during the early days after grafting. These results suggest that interactions between neural and hormonal stimulation influence cardiac growth in the in oculo culture system and during normal development.

Thermal conditions in freezing chambers and prediction of the thermophysiological responses of workers

NASA Astrophysics Data System (ADS)

Raimundo, A. M.; Oliveira, A. V. M.; Gaspar, A. R.; Quintela, D. A.

2015-11-01

The present work is dedicated to the assessment of the cold thermal strain of human beings working within freezing chambers. To obtain the present results, both field measurements and a numerical procedure based on a modified version of the Stolwijk thermoregulation model were used. Eighteen freezing chambers were considered. A wide range of physical parameters of the cold stores, the workers clothing insulation, and the working and recovering periods were observed. The combination of these environmental and individual parameters lead to different levels of thermal stress, which were grouped under three categories. Some good practices were observed in the field evaluations, namely situations with appropriate level of clothing protection and limited duration of exposure to cold avoiding unacceptable level of hypothermia. However, the clothing ensembles normally used by the workers do not provide the minimum required insulation, which suggests the possibility of the whole body cooling for levels higher than admissible. The numerical predictions corroborate the main conclusions of the field survey. The results obtained with both methodologies clearly show that, for the low temperature of the freezing chambers, the clothing insulation is insufficient, the exposure periods are too long, and the recovering periods are inadequate. Thus, high levels of physiological strain can indeed be reached by human beings under such working environments.

Thermal conditions in freezing chambers and prediction of the thermophysiological responses of workers.

PubMed

Raimundo, A M; Oliveira, A V M; Gaspar, A R; Quintela, D A

2015-11-01

The present work is dedicated to the assessment of the cold thermal strain of human beings working within freezing chambers. To obtain the present results, both field measurements and a numerical procedure based on a modified version of the Stolwijk thermoregulation model were used. Eighteen freezing chambers were considered. A wide range of physical parameters of the cold stores, the workers clothing insulation, and the working and recovering periods were observed. The combination of these environmental and individual parameters lead to different levels of thermal stress, which were grouped under three categories. Some good practices were observed in the field evaluations, namely situations with appropriate level of clothing protection and limited duration of exposure to cold avoiding unacceptable level of hypothermia. However, the clothing ensembles normally used by the workers do not provide the minimum required insulation, which suggests the possibility of the whole body cooling for levels higher than admissible. The numerical predictions corroborate the main conclusions of the field survey. The results obtained with both methodologies clearly show that, for the low temperature of the freezing chambers, the clothing insulation is insufficient, the exposure periods are too long, and the recovering periods are inadequate. Thus, high levels of physiological strain can indeed be reached by human beings under such working environments.

Case study on risk evaluation of printed electronics using nanosilver ink.

PubMed

Kim, Ellen; Lee, Ji Hyun; Kim, Jin Kwon; Lee, Gun Ho; Ahn, Kangho; Park, Jung Duck; Yu, Il Je

2016-01-01

With the ever-increasing development of nanotechnology, our society is being surrounded by possible risks related to exposure to manufactured nanomaterials. The consumer market already includes many products that contain silver nanoparticles (AgNPs), including various household products, such as yoga mats, cutting boards, running shirts, and socks. There is a growing concern over the release of AgNPs in workplaces related to the manufacture and application of nanomaterials. This study investigated the release of AgNPs during the operation of a printed electronics printer. Using an exposure simulation chamber, a nanoparticle collector, scanning mobility particle sizer (SMPS), condensation particle counter (CPC), dust monitor, and mixed cellulose ester (MCE) filters are all connected to measure the AgNP exposure levels when operating a printed electronics printer. A very small amount of AgNPs was released during the operation of the printed electronics printer, and the number of AgNPs inside the exposure simulation chamber was lower than that outside background. In addition, when evaluating the potential risks for consumers and workers using a margin of exposure (MOE) approach and target MOE of 1000, the operational results far exceeded the target MOE in this simulation study and in a previous workplace exposure study. The overall results indicate a no-risk concern level in the case of printed electronics using nanosilver ink.

Pulmonary responses in current smokers and ex-smokers following a two hour exposure at rest to clean air and fine ambient air particles.

EPA Science Inventory

BACKGROUND: Increased susceptibility of smokers to ambient PM may potentially promote development of COPD and accelerate already present disease. OBJECTIVES: To characterize the acute and subacute lung function response and inflammatory effects of controlled chamber exposure t...

Characterisation of the borgwaldt LM4E system for in vitro exposures to undiluted aerosols from next generation tobacco and nicotine products (NGPs).

PubMed

Adamson, Jason; Jaunky, Tomasz; Thorne, David; Gaça, Marianna D

2018-03-01

Traditional in vitro exposure to combustible tobacco products utilise exposure systems that include the use of smoking machines to generate, dilute and deliver smoke to in vitro cell cultures. With reported lower emissions from next generation tobacco and nicotine products (NGPs), including e-cigarettes and tobacco heating products (THPs), diluting the aerosol is potentially not required. Herein we present a simplified exposure scenario to undiluted NGP aerosols, using a new puffing system called the LM4E. Nicotine delivery from an e-cigarette was used as a dosimetry marker, and was measured at source across 4 LM4E ports and in the exposure chamber. Cell viability studies, using Neutral Red Uptake (NRU) assay, were performed using H292 human lung epithelial cells, testing undiluted aerosols from an e-cigarette and a THP. E-cigarette mean nicotine generated at source was measured at 0.084 ± 0.005 mg/puff with no significant differences in delivery across the 4 different ports, p = 0.268 (n = 10/port). Mean nicotine delivery from the e-cigarette to the in vitro exposure chamber (measured up to 100 puffs) was 0.046 ± 0.006 mg/puff, p = 0.061. Aerosol penetration within the LM4E was 55% from source to chamber. H292 cells were exposed to undiluted e-cigarette aerosol for 2 h (240 puffs) or undiluted THP aerosol for 1 h (120 puffs). There were positive correlations between puff number and nicotine in the exposed culture media, R 2  = 0.764 for the e-cigarette and R 2  = 0.970 for the THP. NRU determined cell viability for e-cigarettes after 2 h' exposure resulted in 21.5 ± 17.0% cell survival, however for the THP, full cytotoxicity was reached after 1-h exposure. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effects of nitrogen dioxide on pulmonary function in human subjects: an environmental chamber study

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

Kerr, H.D.; Kulle, T.J.; McIlhany, M.L.

Twenty human subjects with asthma and chronic bronchitis and 10 normal, healthy adults were exposed to 0.5 ppM of nitrogen dioxide for 2 h in an environmental chamber. Seven of the 13 subjects with asthma experienced symptoms with exposure, while only one each of the subjects with chronic bronchitis and the healthy, normal group experienced symptoms. Significant pulmonary function changes from control values with exposure to NO/sub 2/ were observed in decreased quasistatic compliance for the 10 normal subjects and the 20 subjects with asthma and chronic bronchitis. In addition, functional residual capacity increased significantly for the 20 subjects withmore » asthma and chronic bronchitis. The subjects with asthma and the subjects with chronic bronchitis as separate groups, however, did not show any significant changes with exposure. With this study we are reasonably confident that exposure of subjects with asthma and chronic bronchitis to 0.5 ppM NO/sub 2/ for 2 h does not produce a significant decrement in their pulmonary function.« less

Long-term radon concentrations estimated from 210Po embedded in glass

USGS Publications Warehouse

Lively, R.S.; Steck, D.J.

1993-01-01

Measured surface-alpha activity on glass exposed in radon chambers and houses has a linear correlation to the integrated radon exposure. Experimental results in chambers and houses have been obtained on glass exposed to radon concentrations between 100 Bq m-3 and 9 MBq m-3 for periods of a few days to several years. Theoretical calculations support the experimental results through a model that predicts the fractions of airborne activity that deposit and become embedded or adsorbed. The combination of measured activity and calculated embedded fraction for a given deposition environment can be applied to most indoor areas and produces a better estimate for lifetime radon exposure than estimates based on short-term indoor radon measurements.

Preliminary results of an attempt to predict over apron occupational exposure of cardiologists from cardiac fluoroscopy procedures based on DAP (dose area product) values.

PubMed

Toossi, Mohammad Taghi Bahreyni; Mehrpouyan, Mohammad; Nademi, Hossein; Fardid, Reza

2015-03-01

This study is an effort to propose a mathematical relation between the occupational exposure measured by a dosimeter worn on a lead apron in the chest region of a cardiologist and the dose area product (DAP) recorded by a meter attached to the X-ray tube. We aimed to determine factors by which DAP values attributed to patient exposure could be converted to the over-apron entrance surface air kerma incurred by cardiologists during an angiographic procedure. A Rando phantom representing a patient was exposed by an X-ray tube from 77 pre-defined directions. DAP value for each exposure angle was recorded. Cardiologist exposure was measured by a Radcal ionization chamber 10X5-180 positioned on a second phantom representing the physician. The exposure conversion factor was determined as the quotient of over apron exposure by DAP value. To verify the validity of this method, the over-apron exposure of a cardiologist was measured using the ionization chamber while performing coronary angiography procedures on 45 patients weighing on average 75 ± 5 kg. DAP values for the corresponding procedures were also obtained. Conversion factors obtained from phantom exposure were applied to the patient DAP values to calculate physician exposure. Mathematical analysis of our results leads us to conclude that a linear relationship exists between two sets of data: (a) cardiologist exposure measured directly by Radcal & DAP values recorded by the X-ray machine system (R (2) = 0.88), (b) specialist measured and estimated exposure derived from DAP values (R (2) = 0.91). The results demonstrate that cardiologist occupational exposure can be derived from patient data accurately.

Atmospheric pressure plasma processing of polymeric materials utilizing close proximity indirect exposure

DOEpatents

Paulauskas, Felix L.; Bonds, Truman

2016-09-20

A plasma treatment method that includes providing treatment chamber including an intermediate heating volume and an interior treatment volume. The interior treatment volume contains an electrode assembly for generating a plasma and the intermediate heating volume heats the interior treatment volume. A work piece is traversed through the treatment chamber. A process gas is introduced to the interior treatment volume of the treatment chamber. A plasma is formed with the electrode assembly from the process gas, wherein a reactive species of the plasma is accelerated towards the fiber tow by flow vortices produced in the interior treatment volume by the electrode assembly.

Design/Use of the Remotely Operated Bakeout Box Shutter (ROBBS)

NASA Technical Reports Server (NTRS)

Ottens, Brian P.

1999-01-01

A thermal vacuum box bakeout and certification allows orbital payloads to be cleaned and certified when the background TQCM measurements (a measure of how much molecular contamination is on a payload or chamber) are unacceptable or unmanageable in the standard thermal vacuum chamber. The box bakeout procedure is usually performed in 4 steps: bakeout the box, certify the box, bake out the payload, and finally certify the payload. In the procedure's current setup, the contaminant conduction hole ("lid") is initially open and a vacuum chamber break must occur between the bakeout and certification phases to close the box from the vacuum chamber. This exposure is necessary to allow the outgassed contaminants to escape the box's volume rapidly during bakeout phase, but payload certification isn't usually performed while the lid is still open, because it exposes the payload, TQCM, and box volume to chamber contaminants. The Remotely Operated Bakeout Box Shutter (ROBBS) is a new facility design and will allow the remote closure of the contamination hole while the chamber is still under vacuum, and with little or no time to do so.

A versatile UHV transport and measurement chamber for neutron reflectometry under UHV conditions

NASA Astrophysics Data System (ADS)

Syed Mohd, A.; Pütter, S.; Mattauch, S.; Koutsioubas, A.; Schneider, H.; Weber, A.; Brückel, T.

2016-12-01

We report on a versatile mini ultra-high vacuum (UHV) chamber which is designed to be used on the MAgnetic Reflectometer with high Incident Angle of the Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum in Garching, Germany. Samples are prepared in the adjacent thin film laboratory by molecular beam epitaxy and moved into the compact chamber for transfer without exposure to ambient air. The chamber is based on DN 40 CF flanges and equipped with sapphire view ports, a small getter pump, and a wobble stick, which serves also as sample holder. Here, we present polarized neutron reflectivity measurements which have been performed on Co thin films at room temperature in UHV and in ambient air in a magnetic field of 200 mT and in the Q-range of 0.18 Å-1. The results confirm that the Co film is not contaminated during the polarized neutron reflectivity measurement. Herewith it is demonstrated that the mini UHV transport chamber also works as a measurement chamber which opens new possibilities for polarized neutron measurements under UHV conditions.

A versatile UHV transport and measurement chamber for neutron reflectometry under UHV conditions.

PubMed

Syed Mohd, A; Pütter, S; Mattauch, S; Koutsioubas, A; Schneider, H; Weber, A; Brückel, T

2016-12-01

We report on a versatile mini ultra-high vacuum (UHV) chamber which is designed to be used on the MAgnetic Reflectometer with high Incident Angle of the Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum in Garching, Germany. Samples are prepared in the adjacent thin film laboratory by molecular beam epitaxy and moved into the compact chamber for transfer without exposure to ambient air. The chamber is based on DN 40 CF flanges and equipped with sapphire view ports, a small getter pump, and a wobble stick, which serves also as sample holder. Here, we present polarized neutron reflectivity measurements which have been performed on Co thin films at room temperature in UHV and in ambient air in a magnetic field of 200 mT and in the Q-range of 0.18 Å -1 . The results confirm that the Co film is not contaminated during the polarized neutron reflectivity measurement. Herewith it is demonstrated that the mini UHV transport chamber also works as a measurement chamber which opens new possibilities for polarized neutron measurements under UHV conditions.

Development of an Aerosol Model of Cryptococcus Reveals Humidity as an Important Factor Affecting the Viability of Cryptococcus during Aerosolization

PubMed Central

Springer, Deborah J.; Saini, Divey; Byrnes, Edmond J.; Heitman, Joseph; Frothingham, Richard

2013-01-01

Cryptococcus is an emerging global health threat that is annually responsible for over 1,000,000 infections and one third of all AIDS patient deaths. There is an ongoing outbreak of cryptococcosis in the western United States and Canada. Cryptococcosis is a disease resulting from the inhalation of the infectious propagules from the environment. The current and most frequently used animal infection models initiate infection via liquid suspension through intranasal instillation or intravenous injection. These models do not replicate the typically dry nature of aerosol exposure and may hinder our ability to decipher the initial events that lead to clearance or the establishment of infection. We have established a standardized aerosol model of murine infection for the human fungal pathogen Cryptococcus. Aerosolized cells were generated utilizing a Collison nebulizer in a whole-body Madison Chamber at different humidity conditions. The aerosols inside the chamber were sampled using a BioSampler to determine viable aerosol concentration and spray factor (ratio of viable aerosol concentration to total inoculum concentration). We have effectively delivered yeast and yeast-spore mixtures to the lungs of mice and observed the establishment of disease. We observed that growth conditions prior to exposure and humidity within the Madison Chamber during exposure can alter Cryptococcus survival and dose retained in mice. PMID:23894542

Comparison of crop yield sensitivity to ozone between open-top chamber and free-air experiments.

PubMed

Feng, Zhaozhong; Uddling, Johan; Tang, Haoye; Zhu, Jianguo; Kobayashi, Kazuhiko

2018-02-02

Assessments of the impacts of ozone (O 3 ) on regional and global food production are currently based on results from experiments using open-top chambers (OTCs). However, there are concerns that these impact estimates might be biased due to the environmental artifacts imposed by this enclosure system. In this study, we collated O 3 exposure and yield data for three major crop species-wheat, rice, and soybean-for which O 3 experiments have been conducted with OTCs as well as the ecologically more realistic free-air O 3 elevation (O 3 -FACE) exposure system; both within the same cultivation region and country. For all three crops, we found that the sensitivity of crop yield to the O 3 metric AOT40 (accumulated hourly O 3 exposure above a cut-off threshold concentration of 40 ppb) significantly differed between OTC and O 3 -FACE experiments. In wheat and rice, O 3 sensitivity was higher in O 3 -FACE than OTC experiments, while the opposite was the case for soybean. In all three crops, these differences could be linked to factors influencing stomatal conductance (manipulation of water inputs, passive chamber warming, and cultivar differences in gas exchange). Our study thus highlights the importance of accounting for factors that control stomatal O 3 flux when applying experimental data to assess O 3 impacts on crops at large spatial scales. © 2018 John Wiley & Sons Ltd.

Exposure to Novelty Weakens Conditioned Fear in Long-Evans Rats

ERIC Educational Resources Information Center

Anderson, Matthew J.; Burpee, Tara E.; Wall, Matthew J.; McGraw, Justin J.

2013-01-01

The present study sought to determine whether post-training exposure to a novel or familiar object, encountered in either the location of the original fear conditioning (black compartment of a passive avoidance {PA} chamber) or in a neutral setting (open field where initial object training had occurred) would prove capable of reducing fear at…

Characteristics of an aerosol photometer while automatically controlling chamber dilution-air flow rate.

PubMed

O'Shaughnessy, P T; Hemenway, D R

2000-10-01

Trials were conducted to determine those factors that affect the accuracy of a direct-reading aerosol photometer when automatically controlling airflow rate within an exposure chamber to regulate airborne dust concentrations. Photometer response was affected by a shift in the aerosol size distribution caused by changes in chamber flow rate. In addition to a dilution effect, flow rate also determined the relative amount of aerosol lost to sedimentation within the chamber. Additional calculations were added to a computer control algorithm to compensate for these effects when attempting to automatically regulate flow based on a proportional-integral-derivative (PID) feedback control algorithm. A comparison between PID-controlled trials and those performed with a constant generator output rate and dilution-air flow rate demonstrated that there was no significant decrease in photometer accuracy despite the many changes in flow rate produced when using PID control. Likewise, the PID-controlled trials produced chamber aerosol concentrations within 1% of a desired level.

Psidium guajava 'Paluma' (the guava plant) as a new bio-indicator of ozone in the tropics.

PubMed

Furlan, C M; Moraes, R M; Bulbovas, P; Domingos, M; Salatino, A; Sanz, M J

2007-06-01

Psidium guajava 'Paluma' saplings were exposed to carbon filtered air (CF), ambient non-filtered air (NF), and ambient non-filtered air+40ppb ozone (NF+O(3)) 8h per day during two months. The AOT40 values at the end of the experiment were 48, 910 and 12 895ppbh(-1), respectively for the three treatments. After 5 days of exposure (AOT40=1497ppbh(-1)), interveinal red stippling appeared in plants in the NF+O(3) chamber. In the NF chamber, symptoms were observed only after 40 days of exposure (AOT40=880ppbh(-1)). After 60 days, injured leaves per plant corresponded to 86% in NF+O(3) and 25% in the NF treatment, and the average leaf area injured was 45% in NF+O(3) and 5% in the NF treatment. The extent of leaf area injured (leaf injury index) was explained mainly by the accumulated exposure of ozone (r(2)=0.91; p<0.05).

Measurement of acute response to draught in the eye.

PubMed

Wyon, N M; Wyon, D P

1987-08-01

In order to assess the sensitivity to draught of 7 different tests, 41 volunteer subjects were exposed experimentally: 18 to 1.0 m/s and 9 to 0.5 m/s in a climate chamber: 14 to an average of 0.67 m/s in an air-conditioned car. All exposures were at 21-22 degrees C. Exposures were for 30 min indoors, 45 min in the car. Break-up Time (BUT) of the pre-corneal film after a blink was observed before and after exposure in the laboratory. There was a significant decrease after exposure to 1.0 m/s (P less than 0.01) but not to 0.5 m/s. The variance of the observed BUT increased after exposure to 0.5 m/s (P less than 0.05). The Norn Lacrimal Dilution test showed increased tear flow after the climate-chamber exposures (P less than 0.05). Self-reported BUT(S) was always several times longer than BUT. There was a significant correlation between these measures (P less than 0.05) before exposure, but not after. BUT(S), like BUT, decreased after exposure to 1.0 m/s (P less than 0.01), but not after 0.05 m/s. However, the variance of BUT(S) did not increase significantly after 0.5 m/s; it decreased significantly after 1.0 m/s (P less than 0.01). A significantly improved mucus ferning pattern was observed after draught exposure (P less than 0.005), presumably due in part to increased lacrimal flow. There was no significant effect of draught on the albumin content of tear samples taken before and after exposure. Lissamine Green staining performed before and after exposure revealed no effect on micro-damage to the conjunctival epithelium.

Are urinary PAHs biomarkers of controlled exposure to diesel exhaust?

PubMed Central

Lu, Sixin S.; Sobus, Jon R.; Sallsten, Gerd; Albin, Maria; Pleil, Joachim D.; Gudmundsson, Anders; Madden, Michael C.; Strandberg, Bo; Wierzbicka, Aneta; Rappaport, Stephen M.

2016-01-01

Urinary polycyclic aromatic hydrocarbons (PAHs) were evaluated as possible biomarkers of exposure to diesel exhaust (DE) in two controlled-chamber studies. We report levels of 14 PAHs from 28 subjects in urine that were collected before, immediately after and the morning after exposure. Using linear mixed-effects models, we tested for effects of DE exposure and several covariates (time, age, gender and urinary creatinine) on urinary PAH levels. DE exposures did not significantly alter urinary PAH levels. We conclude that urinary PAHs are not promising biomarkers of short-term exposures to DE in the range of 106–276 μg/m3. PMID:24754404

Evaluating the Efficiency of Air Shower in Removing Lead from Army Combat Uniform Swatches Loaded with Gunshot Residue

DTIC Science & Technology

2016-03-25

well-known toxicant and the exposure on indoor firing ranges presents a health risk to both range employees and shooters. Contaminated clothing... firing ranges have employed a new control – air shower (AS), although its effectiveness in this particular application has not been examined. The... firing lead- containing ammunition inside a sealed chamber and allowing the gunshot residue to settle on swatches placed inside the chamber. The

Performance of a liquid argon time projection chamber exposed to the CERN West Area Neutrino Facility neutrino beam

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

Arneodo, F.; Cavanna, F.; Mitri, I. De

2006-12-01

We present the results of the first exposure of a Liquid Argon TPC to a multi-GeV neutrino beam. The data have been collected with a 50 liters ICARUS-like chamber located between the CHORUS and NOMAD experiments at the CERN West Area Neutrino Facility (WANF). We discuss both the instrumental performance of the detector and its capability to identify and reconstruct low-multiplicity neutrino interactions.

Effects of nitrogen dioxide on pulmonary function in human subjects: an environmental chamber study

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

Kerr, H.D.; Kulle, T.J.; McIlhany, M.L.

Twenty human subjects with asthma and chronic bronchitis and 10 healthy adults were exposed to 0.5 ppM of nitrogen dioxide for 2 hr in an environment chamber. Seven of the 13 subjects with asthma experienced symptoms with exposure, while only one each of the subjects with bronchitis and the normal group experienced symptoms. Functional residual pulmonary capacity increased for those with asthma and bronchitis. 18 references, 5 tables.

Effect of nitrous acid on lung function in asthmatics: a chamber study.

PubMed Central

Beckett, W S; Russi, M B; Haber, A D; Rivkin, R M; Sullivan, J R; Tameroglu, Z; Mohsenin, V; Leaderer, B P

1995-01-01

Nitrous acid, a component of photochemical smog and a common indoor air pollutant, may reach levels of 100 ppb where gas stoves and unvented portable kerosene heaters are used. Nitrous acid is a primary product of combustion and may also be a secondary product by reaction of nitrogen dioxide with water. Because the usual assays for nitrogen dioxide measure several oxides of nitrogen (including nitrous acid) together, previous studies of indoor nitrogen dioxide may have included exposure to and health effects of nitrous acid. To assess the respiratory effects of nitrous acid exposure alone, we carried out a double-blinded crossover chamber exposure study with 11 mildly asthmatic adult subjects. Each underwent 3-hr exposures to 650 ppb nitrous acid and to filtered room air with three 20-min periods of moderate cycle exercise. Symptoms, respiratory parameters during exercise, and spirometry after exercise were measured. A statistically significant decrease in forced vital capacity was seen on days when subjects were exposed to nitrous acid. This effect was most marked at 25 min and 85 min after exposure began. Aggregate respiratory and mucous membrane symptoms were also significantly higher with nitrous acid. We conclude that this concentration and duration of exposure to nitrous acid alters lung mechanics slightly, does not induce significant airflow obstruction, and produces mild irritant symptoms in asthmatics. Images Figure 1. PMID:7607138

Drosophila melanogaster (fruit fly) locomotion during a sounding rocket flight

NASA Astrophysics Data System (ADS)

Miller, Mark S.; Keller, Tony S.

2008-05-01

The locomotor activity of young Drosophila melanogaster (fruit fly) was studied during a Nike-Orion sounding rocket flight, which included a short-duration microgravity exposure. An infrared monitoring system was used to determine the activity level, instantaneous velocity, and continuous velocity of 240 (120 male, 120 female) fruit flies. Individual flies were placed in chambers that limit their motion to walking. Chambers were oriented both vertically and horizontally with respect to the rocket's longitudinal axis. Significant changes in Drosophila locomotion patterns were observed throughout the sounding rocket flight, including launch, microgravity exposure, payload re-entry, and after ocean impact. During the microgravity portion of the flight (3.8 min), large increases in all locomotion measurements for both sexes were observed, with some measurements doubling compared to pad (1 G) data. Initial effects of microgravity were probably delayed due to large accelerations from the payload despining immediately before entering microgravity. The results indicate that short-duration microgravity exposure has a large effect on locomotor activity for both males and females, at least for a short period of time. The locomotion increases may explain the increased male aging observed during long-duration exposure to microgravity. Studies focusing on long-duration microgravity exposure are needed to confirm these findings, and the relationship of increased aging and locomotion.

Miniature microwave powered steam sterilization chamber

NASA Astrophysics Data System (ADS)

Atwater, James E.; Dahl, Roger W.; Garmon, Frank C.; Lunsford, Teddie D.; Michalek, William F.; Wheeler, Richard R., Jr.; Sauer, Richard L.

1997-10-01

A small device for the rapid ultrahigh temperature sterilization of surfaces is described. Microwave power generated by a 2.45 GHz magnetron is delivered via coaxial cable to a silicon carbide block housed within the chamber. Small quantities of water or aqueous hydrogen peroxide are introduced into the chamber. Upon application of power, the liquid flashes to vapor and superheats producing temperatures to 300 °C. The hot vapor permeates the enclosed space and contacts all exposed surfaces. Complete microbial kill of >10 6 colony forming units of the spore forming thermophile, Bacillus stearothermophilus, has been demonstrated using a variety of temperatures and exposure times in both steady state and thermal pulse modes of operation.

Search for anomalous C-jets in Chacaltaya emulsion chamber experiment

NASA Technical Reports Server (NTRS)

Kumano, H.

1985-01-01

Anomalous C-jets were measured in Chacaltaya emulsion chamber No.17. Measurement of 150 C-jets nuclear interactions occured in the target layer in the chamber itself with total visible energy greater than 5 TeV was completed. they are recorded in area of 11 sq m, corresponding to 17.1 sq m year exposure. Among them, seven events have no pinaught and two events are peculiar in that three showers out of four show abnormal cascade development. Two show remarkable characteristics indicating that they are coming from exotic interactions in the target layer. Illustrations of these events are presented and the thresholds of this type of event are discussed.

Users Polarization on Facebook and Youtube

PubMed Central

Bessi, Alessandro; Zollo, Fabiana; Del Vicario, Michela; Puliga, Michelangelo; Scala, Antonio; Caldarelli, Guido; Uzzi, Brian; Quattrociocchi, Walter

2016-01-01

Users online tend to select information that support and adhere their beliefs, and to form polarized groups sharing the same view—e.g. echo chambers. Algorithms for content promotion may favour this phenomenon, by accounting for users preferences and thus limiting the exposure to unsolicited contents. To shade light on this question, we perform a comparative study on how same contents (videos) are consumed on different online social media—i.e. Facebook and YouTube—over a sample of 12M of users. Our findings show that content drives the emergence of echo chambers on both platforms. Moreover, we show that the users’ commenting patterns are accurate predictors for the formation of echo-chambers. PMID:27551783

Users Polarization on Facebook and Youtube.

PubMed

Bessi, Alessandro; Zollo, Fabiana; Del Vicario, Michela; Puliga, Michelangelo; Scala, Antonio; Caldarelli, Guido; Uzzi, Brian; Quattrociocchi, Walter

2016-01-01

Users online tend to select information that support and adhere their beliefs, and to form polarized groups sharing the same view-e.g. echo chambers. Algorithms for content promotion may favour this phenomenon, by accounting for users preferences and thus limiting the exposure to unsolicited contents. To shade light on this question, we perform a comparative study on how same contents (videos) are consumed on different online social media-i.e. Facebook and YouTube-over a sample of 12M of users. Our findings show that content drives the emergence of echo chambers on both platforms. Moreover, we show that the users' commenting patterns are accurate predictors for the formation of echo-chambers.

Assessment of personal airborne exposures and surface contamination from x-ray vaporization of beryllium targets at the National Ignition Facility.

PubMed

Paik, Samuel Y; Epperson, Patrick M; Kasper, Kenneth M

2017-06-01

This article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measures in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2 , for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. All the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.

Assessment of personal airborne exposures and surface contamination from x-ray vaporization of beryllium targets at the National Ignition Facility

DOE PAGES

Paik, Samuel Y.; Epperson, Patrick M.; Kasper, Kenneth M.

2017-02-28

Here, this article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measuresmore » in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2, for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. Finally, all the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.« less

A study of the polyethylene membrane used in diffusion chambers for radon gas concentration measurements

NASA Astrophysics Data System (ADS)

Leung, S. Y. Y.; Nikezic, D.; Leung, J. K. C.; Yu, K. N.

2007-10-01

Solid-state nuclear track detectors (SSNTDs) in diffusion chambers have been routinely used for long-term measurements of radon gas concentrations. In usual practice, a filter is added across the top of the diffusion chamber to stop the progeny from entering. Thoron can also be deterred from entering the diffusion chamber by using a polyethylene (PE) membrane. However, the thickness of the PE membrane is rarely specified in the literature. In this paper, we will present our experimental results for a radon exposure that the number of alpha-particle tracks registered by the LR 115 SSNTD in a Karlsruhe diffusion chamber covered with one layer of PE membrane is actually enhanced. This is explained by enhanced deposition of radon progeny on the outside surface of the PE membrane and the insufficient thickness of the PE membrane to stop the alpha particles emitted from these deposited radon progeny to reach the SSNTD. We will present the PE thickness which can stop the alpha particles emitted from the deposited radon or thoron progeny. For the "twin diffusion chambers method", one of the diffusion chambers is covered with PE membranes. The optimal number of thickness of PE membranes will be determined, which allows the largest amount of radon gas to diffuse into the diffusion chamber while at the same time screening out the largest amount of thoron gas.

Varied dose exposures to ultrafine particles in the motorcycle smoke cause kidney cell damages in male mice.

PubMed

Wardoyo, Arinto Y P; Juswono, Unggul P; Noor, Johan A E

2018-01-01

Ultrafine particles (UFPs) are one of motorcycle exhaust emissions which can penetrate the lung alveoli and deposit in the kidney. This study was aimed to investigate mice kidney cell physical damage (deformation) due to motorcycle exhaust emission exposures. The motorcycle exhaust emissions were sucked from the muffler with the rate of 33 cm 3 /s and passed through an ultrafine particle filter system before introduced into the mice exposure chamber. The dose concentration of the exhaust emissions was varied by setting the injected time of the 20s, 40s, 60s, 80s, and 100s. The mice were exposed to the smoke in the chamber for 100 s twice a day. The impact of the ultrafine particles on the kidney was observed by identifying the histological image of the kidney cell deformation using a microscope. The exposure was conducted for 10 days. The kidney observations were carried out on day 11. The results showed that there was a significant linear correlation between the total concentration of ultrafine particles deposited in the kidneys and the physical damage percentages. The increased concentrations of ultrafine particles caused larger cell deformation to the kidneys.

Multiple exposures of sevoflurane during pregnancy induces memory impairment in young female offspring mice

PubMed Central

Chung, Woosuk; Yoon, Seunghwan

2017-01-01

Background Earlier studies have reported conflicting results regarding long-term behavioral consequences after anesthesia during the fetal period. Previous studies also suggest several factors that may explain such conflicting data. Thus, we examined the influence of age and sex on long-term behavioral consequences after multiple sevoflurane exposures during the fetal period. Methods C57BL/6J pregnant mice received oxygen with or without sevoflurane for 2 hours at gestational day (GD) 14-16. Offspring mice were subjected to behavioral assays for general activity (open field test), learning, and memory (fear chamber test) at postnatal day 30–35. Results Multiple sevoflurane exposures at GD 14–16 caused significant changes during the fear chamber test in young female offspring mice. Such changes did not occur in young male offspring mice. However, general activity was not affected in both male and female mice. Conclusions Multiple sevoflurane exposures in the second trimester of pregnancy affects learning and memory only in young female mice. Further studies focusing on diverse cognitive functions in an age-, sex-dependent manner may provide valuable insights regarding anesthesia-induced neurotoxicity. PMID:29225748

Characterization and Application of a Nose-Only Exposure Chamber for Inhalation Delivery of Liposomal Drugs and Nucleic Acids to Mice

PubMed Central

Seshadri, S.; Garbuzenko, O.B.; Han, T.; Wang, Z.; Minko, T.

2013-01-01

Abstract Background A small nose-only exposure chamber was evaluated for inhalation delivery of drug carrier systems (DCSs) to mice for the treatment of lung cancer. The chamber then was used for inhalation delivery of an anticancer drug, antisense oligonucleotides (ASO), and small interfering RNA (siRNA) directly to the cancerous lungs of mice. Methods The uniformity of particle delivery across the ports of the exposure chamber and stability of the DCS (liposomes) during continuous aerosolization by a Collison nebulizer were examined. The mean produced particle size by number was approximately 130 nm, and the mass median diameter was approximately 270 nm. The system was then used to deliver DCS containing doxorubicin (DOX) and ASO or siRNA targeted to multidrug resistance-associated protein 1 (MRP1) mRNA as suppressors of cancer cell resistance. The retention of the drug in the lungs and the effect on tumor size were compared after inhalation delivery and intravenous injection in a nu/nu mouse model of lung cancer. Results The aerosol mass across the four inhalation ports had a coefficient of variation of less than 12%, and approximately 1.4% of the nebulized mass was available for inhalation at each port. The mean size of 130 nm of liposomal DCS did not change significantly during continuous 60-min aerosolization. For inhalation delivery of DCS with DOX+ASO/siRNA, the amount of drugs available for inhalation was lower compared with intravenous injection of DOX; however, the observed lung dose and the retention time were significantly higher. The delivery of DOX+ASO/siRNA via inhalation resulted in tumor volume reduction of more than 90%, whereas only about 40% reduction was achieved after intravenous injection of DOX. Conclusions The investigated exposure system is suitable for inhalation delivery of complex DCS, and its use to deliver DCS containing anticancer drugs and resistance suppressors via inhalation offered a superior method for lung cancer treatment in mice compared with intravenous injections. PMID:23530772

Large area emulsion chamber experiments for the Space Shuttle

NASA Technical Reports Server (NTRS)

Parnell, T. A.

1985-01-01

Emulsion-chamber experiments employing nuclear-track emulsions, etchable plastic detectors, metal plates, and X-ray films continue to demonstrate high productivity and potential in the study of cosmic-ray primaries and their interactions. Emulsions, with unsurpassed track-recording capability, provide an appropriate medium for the study of nucleus-nucleus interactions at high energy, which will likely produce observations of a phase change in nuclear matter. The many advantages of emulsion chambers (excellent multitrack recording capability, large geometry factor, low apparatus cost, simplicity of design and construction) are complemented by the major advantages of the Space Shuttle as an experiment carrier. A Shuttle experiment which could make a significant advance in both cosmic-ray primary and nucleus-nucleus interaction studies is described. Such an experiment would serve as a guide for use of emulsions during the Space Station era. Some practical factors that must be considered in planning a Shuttle exposure of emulsion chambers are discussed.

Experimental PVC Material Challenge in Subjects with Occupational PVC Exposure

PubMed Central

Tuomainen, Anneli; Stark, Harri; Seuri, Markku; Hirvonen, Maija-Riitta; Linnainmaa, Markku; Sieppi, Anne; Tukiainen, Hannu

2006-01-01

Background Polyvinyl chloride (PVC) materials have been linked to asthma in several epidemiologic studies, but the possible causal factors remain unknown. Participants We challenged 10 subjects experimentally to degraded PVC products under controlled conditions. All of the subjects had previously experienced respiratory symptoms suspected to be caused by this kind of exposure in their work place. Five subjects had doctor-diagnosed asthma. Methods The subjects were exposed to degraded PVC material in an exposure chamber; a challenge with ceramic tile was used as the control test. We followed exhaled nitric oxide, nasal NO, lung functions, cytokines [tumor necrosis factor-α (TNF-α), interleukin-4 (IL-4), IL-6, and IL-12] and NO in nasal lavage fluid (NAL) during and after the exposures. We also measured 2-ethylhexanol in exhaled breath samples and NAL. Results On the morning after the PVC exposure, subjects reported respiratory tract symptoms significantly more often than they did after the control test (50% vs. 0%, respectively; p = 0.029; n = 10). We did not detect any changes in lung functions or levels of exhaled NO, nasal NO, or NO in NAL after PVC challenge compared with the control test. Cytokine levels increased after both exposures, with no statistically significant difference between situations. All of the exhaled breath samples collected during the PVC exposure contained 2-ethylhexanol. Conclusions PVC flooring challenge can evoke respiratory tract symptoms in exposed subjects. Our results do not support the hypothesis that PVC materials themselves evoke immediate asthmatic reactions. The chamber test used is well suited to this type of exposure study. PMID:16966097

Evaluating combined effect of noise and heat on blood pressure changes among males in climatic chamber.

PubMed

Dehghan, Habibollah; Bastami, Mohamad Taghi; Mahaki, Behzad

2017-01-01

Exposure to noise and heat causes individuals to experience some changes in the function of cardiovascular system in workplaces. This study aimed to find the combined effect of heat and noise on systolic and diastolic types of blood pressure in experimentally controlled conditions. This quasi-experimental study was performed with 12 male students in a climatic chamber in 2014. Blood pressure including systolic and diastolic was measured in the following conditions: 15 min after rest in exposure to heat (40°C, relative humidity [RH]: 30%), exposure to noise with 75, 85, and 95 dB rates in thermal comfort condition (22.1 ± 0.9 wet-bulb globe temperature), and combined exposure to heat (40°C, RH: 30%) and noise with 75, 85, and 95 dB. Friedman test was used to analyze the data. The mean change of systolic blood pressure was different significantly before and after exposure to heat and noise levels including 75, 85, and 95 dB ( P = 0.015, P = 0.001, P > 0.001, P = 0.027, respectively). Although systolic and diastolic blood pressures changed drastically, it was not significantly different in simultaneous exposure to heat and noise. Both systolic and diastolic blood pressures decreased in exposure to heat, while exposure to different levels of noise elevates systolic and diastolic blood pressures. However, when exposed to a combination of heat and noise, subtle changes of blood pressure were traced, which can be characterized as average, considering heat-only and noise-only tension situations.

Time dependence of 222Rn, 220Rn and their progenies' distributions in a diffusion chamber

NASA Astrophysics Data System (ADS)

Stevanovic, N.; Markovic, V. M.; Nikezic, D.

2017-11-01

Diffusion chamber with SSNTD (Solid State Nuclear Track Detector) placed inside is a passive detector for measuring the activity of 222Rn and 220Rn (radon and thoron) and their progenies. Calibration from detected alpha particle tracks to progeny activity is often acquired from theoretical models. One common assumption related to these models found in literature is that concentrations of 222Rn and 220Rn at the entrance of a chamber are constant during the exposure. In this paper, concentrations of 222Rn and 220Rn at the entrance of the chamber are taken to be variable with time, which is actually the case in reality. Therefore, spatial distributions of 222Rn and 220Rn and their progenies inside the diffusion chamber should be time dependent. Variation of 222Rn and 220Rn concentrations on the entrance of the chamber was modeled on the basis of true measurements. Diffusion equations in cylindrical coordinates were solved using FDM (Finite Difference Method) to obtain spatial distributions as functions of time. It was shown that concentrations of 222Rn, 220Rn and their progenies were not homogeneously distributed in the chamber. Due to variable 222Rn and 220Rn concentrations at the entrance of the chamber, steady state (the case when concentration of 222Rn, 220Rn and their progenies inside the chamber remains unchanged with time) could not be reached. Deposition of progenies on the chamber walls was considered and it was shown that distributions of deposited progenies were not uniform over walls' surface.

Symptomatic effects of exposure to diluted air sampled from a swine confinement atmosphere on healthy human subjects.

PubMed

Schiffman, Susan S; Studwell, Clare E; Landerman, Lawrence R; Berman, Katherine; Sundy, John S

2005-05-01

Aerial emissions from a swine house at North Carolina State University's field laboratory were diluted to a level that could occur at varying distances downwind from a confined animal feeding operation (CAFO) both within and beyond the property line, and these emissions were delivered to an environmental exposure chamber. The study design consisted of two 1-hr sessions, one in which 48 healthy human adult volunteers were exposed to diluted swine air and another in which they were exposed to clean air (control). Objective measures of blood pressure, temperature, heart rate, respiratory rate, lung function, nasal inflammation, secretory immunity, mood, attention, and memory were correlated with objective measures of air quality. Ratings of perceived (self-reported) health symptoms were also obtained. The mean levels of airborne constituents in the swine air condition were hydrogen sulfide (24 ppb), ammonia (817 ppb), total suspended particulates (0.0241 mg/m3), endotoxin (7.40 endotoxin units/m3), and odor (57 times above odor threshold). No statistical differences on objective measures of physical symptoms, mood, or attention resulted from the 1-hr exposure to swine emissions in the environmental chamber when compared with clean air for healthy human volunteers. However, subjects were 4.1 (p = 0.001) times more likely to report headaches, 6.1 (p = 0.004) times more likely to report eye irritation, and 7.8 (p = 0.014) times more likely to report nausea in the swine air (experimental) condition than in the control condition. These results indicate that short-term exposure in an environmental chamber to malodorous emissions from a swine house at levels expected downwind can induce clinically important symptoms in healthy human volunteers.

Bioassays with caged hyalella azteca to determine in situ toxicity downstream of two Saskatchewan, Canada, uranium operations.

PubMed

Robertson, Erin L; Liber, Karsten

2007-11-01

The main objectives of this in situ study were to evaluate the usefulness of an in situ bioassay to determine if downstream water bodies at the Key Lake and Rabbit Lake uranium operations (Saskatchewan, Canada) were toxic to Hyalella azteca and, if toxicity was observed, to differentiate between the contribution of surface water and sediment contamination to in situ toxicity. These objectives were achieved by performing 4-d in situ bioassays with laboratory-reared H. azteca confined in specially designed, paired, surface water and sediment exposure chambers. Results from the in situ bioassays revealed significant mortality, relative to the respective reference site, at the exposure sites at both Key Lake (p

Veterans at Risk: The Health Effects of Mustard Gas and Lewisite

DTIC Science & Technology

1993-01-01

to Mustard Gas During WWII Testing Programs 370 F. Summary of the Department of the Army Report: Use of Volunteers in Chemical Agent Research 378 Key...concentrations of mustard agents or Lewisite in gas chambers or in field exercises over contaminated ground areas. The human subjects had experienced a...wide range of exposures to mustard agents or Lewisite, from mild (a drop of agent on the arm in "patch" tests) to quite severe (repeated gas chamber

Filmless Radiographic System for Field Use.

DTIC Science & Technology

1988-02-12

electronic circuits. The receptor assembly contains the x-ray grid , cassette holder or EPID panel and the sensor panel for the automatic exposure control... Grid lines were still resolved. The appearance of fine details was altered but most of the diagnostic value was retained. The choice of the screens must...A 6:1, 60 lines per inch grid is mounted to the frame on the x-ray entrance side. II.F.4. Ion Chamber The ion chamber is used by the automatic

Radiation induced violations of blood circulation in the ciliary body and changes of the anterior chamber angle in the pathogenesis of glaucoma in clean up workers of the Chornobyl NPP accident and residents of contaminated areas.

PubMed

Garkava, N A; Fedirko, P A; Babenko, T F; Dorichevska, R E

2017-12-01

Estimate changes blood filling of the ciliary body and changes of the anterior chamber angle; study their influence to glaucoma pathogenesis in irradiated persons. Used the results of a randomly selected group survey of 41 clean up workers of the Chornobyl NPP accident (clean up workers), and 18 inhabitants of the zone of guaranteed voluntary resettlement; age at the time of the survey was 45-50 years. The control group consisted of 41 persons of the same age had not radiation exposure. State of the anterior chamber angle studied by gonioscopy, which was conducted 35 clean up workers and 35 persons of the control group. Changes of the blood circulation in the ciliary body examine by the ophtalmoreog raphy, what was done on 12 eyes of 6 clean up workers, control was 12 eyes of 6 persons had not radiation exposure. Detection revealed of the blood circulation in the ciliary body in all clean up workers, reography coefficient was probably lower (p < 0.05), than in the control group. The research of the state of the anterior chamber angle revealed a higher relative risk of appearance of involution changes of the anterior chamber angle in clean up work ers of ChNPP accident, in comparison with the control group was 3.5 (1.27; 9.5) χ2 = 7.48, p = 0.031. The same changes are characteristic for inhabitants of radiation polluted territories. Influence ionizing radiation causes a blood circulation decrease in the ciliary body and development changes of the angle of the anterior chamber. Presence of these changes can explain the features of the pathogene sis of glaucoma in irradiated late manifestation and, at the same time, severe course. N. A. Garkava, P. A. Fedirko, T. F. Babenko, R. E. Dorichevska.

Computational Approaches for Predicting Nonlinear Interactions of Chemical Mixtures in Biological Systems

DTIC Science & Technology

2009-12-01

exposure. Feces samples were collected at 24hrs and 48hrs. No fecal matter was present at 6hrs. Urine samples were collected at 6hrs, 24hrs and 48hrs...atmosphere sampling technique (Tremblay et al, in press) to characterize the inhalation exposure chamber for JP-8 and S- 8 exposures at Loma Linda Veterans... samples were collected for 1 min at 400 mL/min and quantified using thermal desorption gas chromatography mass spectrometry (TDS-GC/MS). The method was

Design and study of the characteristics of a three electrode experimental ionization chamber for gamma ray dosimetry of spent fuel

NASA Astrophysics Data System (ADS)

Ahmad, N.; Mirza, Nasir M.; Mirza, Sikander M.; Rashid, T.; Tufail, M.; Khan, Liaquat A.

1992-09-01

The ( I, V) characteristics of two and three electrode ionization chamber filled with argon gas have been studied. To determine the sensitivity and the response with increase in exposure rate, the chamber was tested with a 60Co commercial irradiator. The response is linear up to more than 1.5 krad/h. The experimentally measured sensitivity of the chamber is 1.849×10 -13 A/cm 3 per rad/h when the argon gas pressure in the chamber is 1.24 GPa (180 psi). The effect of transparency of the intermediate electrod on the saturation current due to 137Cs gamma-rays has also been studied. The experimental results show that the electrode with holes of small diameter acts as a better intermediate electrode as compared to the electrodes without holes or with holes of a larger diameter. The chamber has also been teste with fission product gamma-rays from spent fuel elements of a typical pool type research reactor. The results indicate that the presence of an intermediate electrode lowers the operating voltage by 50% and reduces the slope in the plateau region.

A facility for long-term Mars simulation experiments: the Mars Environmental Simulation Chamber (MESCH).

PubMed

Jensen, Lars Liengaard; Merrison, Jonathan; Hansen, Aviaja Anna; Mikkelsen, Karina Aarup; Kristoffersen, Tommy; Nørnberg, Per; Lomstein, Bente Aagaard; Finster, Kai

2008-06-01

We describe the design, construction, and pilot operation of a Mars simulation facility comprised of a cryogenic environmental chamber, an atmospheric gas analyzer, and a xenon/mercury discharge source for UV generation. The Mars Environmental Simulation Chamber (MESCH) consists of a double-walled cylindrical chamber. The double wall provides a cooling mantle through which liquid N(2) can be circulated. A load-lock system that consists of a small pressure-exchange chamber, which can be evacuated, allows for the exchange of samples without changing the chamber environment. Fitted within the MESCH is a carousel, which holds up to 10 steel sample tubes. Rotation of the carousel is controlled by an external motor. Each sample in the carousel can be placed at any desired position. Environmental data, such as temperature, pressure, and UV exposure time, are computer logged and used in automated feedback mechanisms, enabling a wide variety of experiments that include time series. Tests of the simulation facility have successfully demonstrated its ability to produce temperature cycles and maintain low temperature (down to -140 degrees C), low atmospheric pressure (5-10 mbar), and a gas composition like that of Mars during long-term experiments.

A Facility for Long-Term Mars Simulation Experiments: The Mars Environmental Simulation Chamber (MESCH)

NASA Astrophysics Data System (ADS)

Jensen, Lars Liengaard; Merrison, Jonathan; Hansen, Aviaja Anna; Mikkelsen, Karina Aarup; Kristoffersen, Tommy; Nørnberg, Per; Lomstein, Bente Aagaard; Finster, Kai

2008-06-01

We describe the design, construction, and pilot operation of a Mars simulation facility comprised of a cryogenic environmental chamber, an atmospheric gas analyzer, and a xenon/mercury discharge source for UV generation. The Mars Environmental Simulation Chamber (MESCH) consists of a double-walled cylindrical chamber. The double wall provides a cooling mantle through which liquid N2 can be circulated. A load-lock system that consists of a small pressure-exchange chamber, which can be evacuated, allows for the exchange of samples without changing the chamber environment. Fitted within the MESCH is a carousel, which holds up to 10 steel sample tubes. Rotation of the carousel is controlled by an external motor. Each sample in the carousel can be placed at any desired position. Environmental data, such as temperature, pressure, and UV exposure time, are computer logged and used in automated feedback mechanisms, enabling a wide variety of experiments that include time series. Tests of the simulation facility have successfully demonstrated its ability to produce temperature cycles and maintain low temperature (down to -140°C), low atmospheric pressure (5 10 mbar), and a gas composition like that of Mars during long-term experiments.

Discrimination between platelet-mediated and coagulation-mediated mechanisms in a model of complex thrombus formation in vivo

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

Cadroy, Y.; Horbett, T.A.; Hanson, S.R.

1989-04-01

To study mechanisms of complex thrombus formation in vivo, and to compare the relative antithrombotic effects of anticoagulants and antiplatelet agents, a model was developed in baboons. Segments of collagen-coated tubing followed by two sequentially placed expansion chambers exhibiting disturbed flow patterns were exposed to native blood under laminar flow conditions. The device was incorporated for 1 hour into an exteriorized arteriovenous shunt in baboons under controlled blood flow (20 ml/min). Morphologic evaluation by scanning electron microscopy showed that thrombi associated with collagen were relatively rich in platelets but thrombi in the chambers were rich in fibrin and red cells.more » Deposition of indium 111-labeled platelets was continuously measured with a scintillation camera. Platelet deposition increased in a linear (collagen-coated segment) or exponential (chambers 1 and 2) fashion over time, with values after 40 minutes averaging 24.1 +/- 3.3 x 10(8) platelets (collagen segment), 16.7 +/- 3.4 x 10(8) platelets (chamber 1), and 8.4 +/- 2.4 x 10(8) platelets (chamber 2). Total fibrinogen deposition after 40 minutes was determined by using iodine 125-labeled baboon fibrinogen and averaged 0.58 +/- 0.14 mg in the collagen segment, 1.51 +/- 0.27 mg in chamber 1, and 0.95 +/- 0.25 mg in chamber 2. Plasma levels of beta-thromboglobulin (beta TG), platelet-factor 4 (PF4), and fibrinopeptide A (FPA) increased fourfold to fivefold after 60 minutes of blood exposure to the thrombotic device. Platelet deposition onto the collagen segment, chamber 1, and chamber 2 was linearly dependent on the circulating platelet count. Platelet accumulation in chamber 1 and chamber 2 was also dependent on the presence of the proximal collagen segment.« less

Decompression tables for inside chamber attendants working at altitude.

PubMed

Bell, James; Thombs, Paul A; Davison, William J; Weaver, Lindell K

2014-01-01

Hyperbaric oxygen (HBO2) multiplace chamber inside attendants (IAs) are at risk for decompression sickness (DCS). Standard decompression tables are formulated for sea-level use, not for use at altitude. At Presbyterian/St. Luke's Medical Center (Denver, Colorado, 5,924 feet above sea level) and Intermountain Medical Center (Murray, Utah, 4,500 feet), the decompression obligation for IAs is managed with U.S. Navy Standard Air Tables corrected for altitude, Bühlmann Tables, and the Nobendem© calculator. IAs also breathe supplemental oxygen while compressed. Presbyterian/St. Luke's (0.83 atmospheres absolute/atm abs) uses gauge pressure, uncorrected for altitude, at 45 feet of sea water (fsw) (2.2 atm abs) for routine wound care HBO2 and 66 fsw (2.8 atm abs) for carbon monoxide/cyanide poisoning. Presbyterian/St. Luke's provides oxygen breathing for the IAs at 2.2 atm abs. At Intermountain (0.86 atm abs), HBO2 is provided at 2.0 atm abs for routine treatments and 3.0 atm abs for carbon monoxide poisoning. Intermountain IAs breathe intermittent 50% nitrogen/50% oxygen at 3.0 atm abs and 100% oxygen at 2.0 atm abs. The chamber profiles include a safety stop. From 1990-2013, Presbyterian/St. Luke's had 26,900 total IA exposures: 25,991 at 45 fsw (2.2 atm abs) and 646 at 66 fsw (2.8 atm abs); there have been four cases of IA DCS. From 2008-2013, Intermountain had 1,847 IA exposures: 1,832 at 2 atm abs and 15 at 3 atm abs, with one case of IA DCS. At both facilities, DCS incidents occurred soon after the chambers were placed into service. Based on these results, chamber inside attendant risk for DCS at increased altitude is low when the inside attendants breathe supplemental oxygen.

Design, construction, and characterization of a novel robotic welding fume generator and inhalation exposure system for laboratory animals.

PubMed

Antonini, James M; Afshari, Aliakbar A; Stone, Sam; Chen, Bean; Schwegler-Berry, Diane; Fletcher, W Gary; Goldsmith, W Travis; Vandestouwe, Kurt H; McKinney, Walter; Castranova, Vincent; Frazer, David G

2006-04-01

Respiratory effects observed in welders have included lung function changes, metal fume fever, bronchitis, and a possible increase in the incidence of lung cancer. Many questions remain unanswered regarding the causality and possible underlying mechanisms associated with the potential toxic effects of welding fume inhalation. The objective of the present study was to construct a completely automated, computer-controlled welding fume generation and inhalation exposure system to simulate real workplace exposures. The system comprised a programmable six-axis robotic welding arm, a water-cooled arc welding torch, and a wire feeder that supplied the wire to the torch at a programmed rate. For the initial studies, gas metal arc welding was performed using a stainless steel electrode. A flexible trunk was attached to the robotic arm of the welder and was used to collect and transport fume from the vicinity of the arc to the animal exposure chamber. Undiluted fume concentrations consistently ranged from 90-150 mg/m(3) in the animal chamber during welding. Temperature and humidity remained constant in the chamber during the welding operation. The welding particles were composed of (from highest to lowest concentration) iron, chromium, manganese, and nickel as measured by inductively coupled plasma atomic emission spectroscopy. Size distribution analysis indicated the mass median aerodynamic diameter of the generated particles to be approximately 0.24 microm with a geometric standard deviation (sigma(g)) of 1.39. As determined by transmission and scanning electron microscopy, the generated aerosols were mostly arranged as chain-like agglomerates of primary particles. Characterization of the laboratory-generated welding aerosol has indicated that particle morphology, size, and chemical composition are comparable to stainless steel welding fume generated in other studies. With the development of this novel system, it will be possible to establish an animal model using controlled welding exposures from automated gas metal arc and flux-cored arc welding processes to investigate how welding fumes affect health.

Sevoflurane Inhalation Accelerates the Long-Term Memory Consolidation via Small GTPase Overexpression in the Hippocampus of Mice in Adolescence.

PubMed

Nakamura, Emi; Kinoshita, Hiroyuki; Feng, Guo-Gang; Hayashi, Hisaki; Satomoto, Maiko; Sato, Motohiko; Fujiwara, Yoshihiro

2016-01-01

Sevoflurane exposure impairs the long-term memory in neonates. Whether the exposure to animals in adolescence affects the memory, however, has been unclear. A small hydrolase enzyme of guanosine triphosphate (GTPase) rac1 plays a role in the F-actin dynamics related to the synaptic plasticity, as well as superoxide production via reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation. The current study was designed to examine whether sevoflurane exposure to mice in early adolescence modifies the long-term learning ability concomitantly with the changes in F-actin constitution as well as superoxide production in the hippocampus according to the levels of rac1 protein expression. Four-week-old mice were subjected to the evaluation of long-term learning ability for three days. On day one, each mouse was allowed to enter a dark chamber for five min to acclimatization. On day two, the procedure was repeated with the addition of an electric shock as soon as a mouse entered the dark chamber. All mice subsequently inhaled 2 L/min air with (Sevoflurane group) and without (Control group) 2.5% sevoflurane for three hours. On day three, each mouse was placed on the platform and retention time, which is the latency to enter the dark chamber, was examined. The brain removed after the behavior test, was used for analyses of immunofluorescence, Western immunoblotting and intracellular levels of superoxide. Sevoflurane exposure significantly prolonged retention time, indicating the enhanced long-term memory. Sevoflurane inhalation augmented F-actin constitution coexisting with the rac1 protein overexpression in the hippocampus whereas it did not alter the levels of superoxide. Sevoflurane exposure to 4-week-old mice accelerates the long-term memory concomitantly with the enhanced F-actin constitution coexisting with the small GTPase rac1 overexpression in the hippocampus. These results suggest that sevoflurane inhalation may amplify long-term memory consolidation via the increased cytoskeleton constitution in the hippocampus of animals in early adolescence.

Non-Smoker Exposure to Secondhand Cannabis Smoke II: Effect of Room Ventilation on the Physiological, Subjective, and Behavioral/Cognitive Effects

PubMed Central

Herrmann, Evan S.; Cone, Edward J; Mitchell, John M.; Bigelow, George E.; LoDico, Charles; Flegel, Ron; Vandrey, Ryan

2015-01-01

Introduction Cannabis is the most widely used illicit drug. Many individuals are incidentally exposed to secondhand cannabis smoke, but little is known about the effects of this exposure. This report examines the physiological, subjective, and behavioral/cognitive effects of secondhand cannabis exposure, and the influence of room ventilation on these effects. Methods Non-cannabis-using individuals were exposed to secondhand cannabis smoke from six individuals smoking cannabis (11.3% THC) ad libitum in a specially constructed chamber for one hour. Chamber ventilation was experimentally manipulated so that participants were exposed under unventilated conditions or with ventilation at a rate of 11 air exchanges/hour. Physiological, subjective and behavioral/cognitive measures of cannabis exposure assessed after exposure sessions were compared to baseline measures. Results Exposure to secondhand cannabis smoke under unventilated conditions produced detectable cannabinoid levels in blood and urine, minor increases in heart rate, mild to moderate self-reported sedative drug effects, and impaired performance on the Digit Symbol Substitution Task (DSST). One urine specimen tested positive at using a 50 ng/mL cut-off and several specimens were positive at 20 ng/mL. Exposure under ventilated conditions resulted in much lower blood cannabinoid levels, and did not produce sedative drug effects, impairments in performance, or positive urine screen results. Conclusions Room ventilation has a pronounced effect on exposure to secondhand cannabis smoke. Under extreme, unventilated conditions, secondhand cannabis smoke exposure can produce detectable levels of THC in blood and urine, minor physiological and subjective drug effects, and minor impairment on a task requiring psychomotor ability and working memory. PMID:25957157

Non-smoker exposure to secondhand cannabis smoke II: Effect of room ventilation on the physiological, subjective, and behavioral/cognitive effects.

PubMed

Herrmann, Evan S; Cone, Edward J; Mitchell, John M; Bigelow, George E; LoDico, Charles; Flegel, Ron; Vandrey, Ryan

2015-06-01

Cannabis is the most widely used illicit drug. Many individuals are incidentally exposed to secondhand cannabis smoke, but little is known about the effects of this exposure. This report examines the physiological, subjective, and behavioral/cognitive effects of secondhand cannabis exposure, and the influence of room ventilation on these effects. Non-cannabis-using individuals were exposed to secondhand cannabis smoke from six individuals smoking cannabis (11.3% THC) ad libitum in a specially constructed chamber for 1h. Chamber ventilation was experimentally manipulated so that participants were exposed under unventilated conditions or with ventilation at a rate of 11 air exchanges/h. Physiological, subjective and behavioral/cognitive measures of cannabis exposure assessed after exposure sessions were compared to baseline measures. Exposure to secondhand cannabis smoke under unventilated conditions produced detectable cannabinoid levels in blood and urine, minor increases in heart rate, mild to moderate self-reported sedative drug effects, and impaired performance on the digit symbol substitution task (DSST). One urine specimen tested positive at using a 50 ng/ml cut-off and several specimens were positive at 20 ng/ml. Exposure under ventilated conditions resulted in much lower blood cannabinoid levels, and did not produce sedative drug effects, impairments in performance, or positive urine screen results. Room ventilation has a pronounced effect on exposure to secondhand cannabis smoke. Under extreme, unventilated conditions, secondhand cannabis smoke exposure can produce detectable levels of THC in blood and urine, minor physiological and subjective drug effects, and minor impairment on a task requiring psychomotor ability and working memory. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Ozone and limonene in indoor air: a source of submicron particle exposure.

PubMed Central

Wainman, T; Zhang, J; Weschler, C J; Lioy, P J

2000-01-01

Little information currently exists regarding the occurrence of secondary organic aerosol formation in indoor air. Smog chamber studies have demonstrated that high aerosol yields result from the reaction of ozone with terpenes, both of which commonly occur in indoor air. However, smog chambers are typically static systems, whereas indoor environments are dynamic. We conducted a series of experiments to investigate the potential for secondary aerosol in indoor air as a result of the reaction of ozone with d-limonene, a compound commonly used in air fresheners. A dynamic chamber design was used in which a smaller chamber was nested inside a larger one, with air exchange occurring between the two. The inner chamber was used to represent a model indoor environment and was operated at an air exchange rate below 1 exchange/hr, while the outer chamber was operated at a high air exchange rate of approximately 45 exchanges/hr. Limonene was introduced into the inner chamber either by the evaporation of reagent-grade d-limonene or by inserting a lemon-scented, solid air freshener. A series of ozone injections were made into the inner chamber during the course of each experiment, and an optical particle counter was used to measure the particle concentration. Measurable particle formation and growth occurred almost exclusively in the 0.1-0.2 microm and 0.2-0.3 microm size fractions in all of the experiments. Particle formation in the 0.1-0.2 microm size range occurred as soon as ozone was introduced, but the formation of particles in the 0.2-0.3 microm size range did not occur until at least the second ozone injection occurred. The results of this study show a clear potential for significant particle concentrations to be produced in indoor environments as a result of secondary particle formation via the ozone-limonene reaction. Because people spend the majority of their time indoors, secondary particles formed in indoor environments may make a significant contribution to overall particle exposure. This study provides data for assessing the impact of outdoor ozone on indoor particles. This is important to determine the efficacy of the mass-based particulate matter standards in protecting public health because the indoor secondary particles can vary coincidently with the variations of outdoor fine particles in summer. PMID:11133393

Ozone and limonene in indoor air: a source of submicron particle exposure.

PubMed

Wainman, T; Zhang, J; Weschler, C J; Lioy, P J

2000-12-01

Little information currently exists regarding the occurrence of secondary organic aerosol formation in indoor air. Smog chamber studies have demonstrated that high aerosol yields result from the reaction of ozone with terpenes, both of which commonly occur in indoor air. However, smog chambers are typically static systems, whereas indoor environments are dynamic. We conducted a series of experiments to investigate the potential for secondary aerosol in indoor air as a result of the reaction of ozone with d-limonene, a compound commonly used in air fresheners. A dynamic chamber design was used in which a smaller chamber was nested inside a larger one, with air exchange occurring between the two. The inner chamber was used to represent a model indoor environment and was operated at an air exchange rate below 1 exchange/hr, while the outer chamber was operated at a high air exchange rate of approximately 45 exchanges/hr. Limonene was introduced into the inner chamber either by the evaporation of reagent-grade d-limonene or by inserting a lemon-scented, solid air freshener. A series of ozone injections were made into the inner chamber during the course of each experiment, and an optical particle counter was used to measure the particle concentration. Measurable particle formation and growth occurred almost exclusively in the 0.1-0.2 microm and 0.2-0.3 microm size fractions in all of the experiments. Particle formation in the 0.1-0.2 microm size range occurred as soon as ozone was introduced, but the formation of particles in the 0.2-0.3 microm size range did not occur until at least the second ozone injection occurred. The results of this study show a clear potential for significant particle concentrations to be produced in indoor environments as a result of secondary particle formation via the ozone-limonene reaction. Because people spend the majority of their time indoors, secondary particles formed in indoor environments may make a significant contribution to overall particle exposure. This study provides data for assessing the impact of outdoor ozone on indoor particles. This is important to determine the efficacy of the mass-based particulate matter standards in protecting public health because the indoor secondary particles can vary coincidently with the variations of outdoor fine particles in summer.

Evaluation of gaseous chlorine dioxide for the inactivation of Tulane virus on blueberries.

PubMed

Kingsley, David H; Pérez-Pérez, Rafael E; Niemira, Brendan A; Fan, Xuetong

2018-05-20

To determine the effectiveness of gaseous chlorine dioxide (gClO 2 ) against a human norovirus surrogate on produce, gClO 2 was generated and applied to Tulane virus-coated blueberries in a 240 ml-treatment chamber. gClO 2 was produced by an acidifying sodium chlorite solution. Initial assessments indicated that blueberries treated with gClO 2 generated from ≤1 mg acidified sodium chlorite in the small chamber appeared unaffected while gClO 2 generated from ≥10 mg of acidified sodium chlorite solution altered the appearance and quality of the blueberries. Treatments of inoculated blueberries with gClO 2 generated from 0.1 mg sodium chlorite reduced the virus populations by >1 log after exposure for 30 to 330 min. For the 1 mg sodium chlorite treatments, the virus populations were reduced by >2.2 log after 15 min exposure and to non-detectable levels (>3.3 logs reductions) after 180 min exposure. Measured concentrations of gClO 2 peaked in the treatment chamber at 0.9 μg/l after 10 min for 0.1 mg treatments and 600 μg/l after around 20 min for 1 mg treatment. Overall results indicate that gClO 2 could be a feasible waterless intervention for blueberries and other produce. Published by Elsevier B.V.

Apparatus and method for stabilization or oxidation of polymeric materials

DOEpatents

Paulauskas, Felix L [Knoxville, TN; Sherman, Daniel M [Knoxville, TN

2010-01-19

An apparatus for treating polymeric materials comprises a treatment chamber adapted to maintain a selected atmosphere at a selected temperature; a means for supporting the polymeric material within the chamber; and, a source of ozone-containing gas, which decomposes at the selected temperature yielding at least one reactive oxidative species whereby the polymer is stabilized and cross linked through exposure to the oxidative species in the chamber at the selected temperature. The ozone may be generated by a plasma discharge or by various chemical processes. The apparatus may be configured for either batch-type or continuous-type processing. The apparatus and method are especially useful for preparing polymer fibers, particularly PAN fibers, for later carbonization treatments as well as to make flame-retardant fabrics.

Quartz resonator processing system

DOEpatents

Peters, Roswell D. M.

1983-01-01

Disclosed is a single chamber ultra-high vacuum processing system for the oduction of hermetically sealed quartz resonators wherein electrode metallization and sealing are carried out along with cleaning and bake-out without any air exposure between the processing steps. The system includes a common vacuum chamber in which is located a rotatable wheel-like member which is adapted to move a plurality of individual component sets of a flat pack resonator unit past discretely located processing stations in said chamber whereupon electrode deposition takes place followed by the placement of ceramic covers over a frame containing a resonator element and then to a sealing stage where a pair of hydraulic rams including heating elements effect a metallized bonding of the covers to the frame.

Testing of various membranes for use in a novel sediment porewater isolation chamber for infaunal invertebrate exposure to PCBs.

PubMed

Coleman, Jessica G; Lotufo, Guilherme R; Kennedy, Alan J; Poda, Aimee R; Rushing, Todd S; Ruiz, Carlos E; Bridges, Todd S

2014-07-01

In benthic sediment bioassays, determining the relative contribution to exposure by contaminants in overlying water, porewater, and sediment particles is technically challenging. The purpose of the present study was to assess the potential for membranes to be utilized as a mechanism to allow freely dissolved hydrophobic organic contaminants into a pathway isolation exposure chamber (PIC) while excluding all sediment particles and dissolved organic carbon (DOC). This investigation was conducted in support of a larger effort to assess contaminant exposure pathways to benthos. While multiple passive samplers exist for estimating concentrations of contaminants in porewater such as those using solid-phase micro extraction (SPME) and polyoxymethylene (POM), techniques to effectively isolate whole organism exposure to porewater within a sediment system are not available. We tested the use of four membranes of different pore sizes (0.1-1.2μm) including nylon, polycarbonate, polyethylsulfone, and polytetrafluoroethylene with a hydrophilic coating. Exposures included both diffusion of radiolabeled and non-labeled contaminants across membranes from aqueous, sediment slurry, and whole sediment sources to assess and evaluate the best candidate membrane. Data generated from the present study was utilized to select the most suitable membrane for use in the larger bioavailability project which sought to assess the relevance of functional ecology in bioavailability of contaminated sediments at remediation sites. The polytetrafluoroethylene membrane was selected for use in the PIC, although exclusion of dissolved organic carbon was not achieved. Published by Elsevier Ltd.

Modulation of elevated plus maze behavior after chronic exposure to the anabolic steroid 17alpha-methyltestosterone in adult mice.

PubMed

Rojas-Ortiz, Yoel Antonio; Rundle-González, Valerie; Rivera-Ramos, Isamar; Jorge, Juan Carlos

2006-01-01

Exposure to supraphysiological doses of androgens may disrupt affective components of behavior. In this study, behavior of adult C57Bl/6 male mice was studied after exposure to the anabolic androgenic steroid (AAS) 17alpha-methyltestosterone (17alpha-meT; 7.5 mg/kg) via a subcutaneous osmotic pump for 17 days. Controls received vehicle implants (0.9% NaCl + 30% cyclodextrine). On day 15, experimental animals were challenged with an ethanol (EtOH) injection (i.p.; 1 g/kg) while controls received saline injections. Five minutes after the injection, animals were tested in an automated elevated plus maze (EPM) or in automated activity chambers. In addition, injection-free animals were tested for ethanol consumption on day 16 after an overnight water deprivation period. Whereas chronic exposure to 17alpha-meT did not modulate open arm behavior, EtOH-exposed animals made more entries into the open arms than controls (P < 0.05). A significant reduction of risk assessment behaviors (rearing, flat approach behavior, and stretch attended posture) over the EPM was noted for EtOH-exposed animals whereas a reduction in stretch attended postures was observed among 17alpha-meT-exposed animals. Locomotor activity, and light-dark transitions in activity chambers remained unaltered. Exposure to AAS did not modulate EtOH consumption. Our data suggest that exposure to a supraphysiological dose of 17alpha-meT has minimal effects on exploratory-based anxiety.

Local exposure of 849 MHz and 1763 MHz radiofrequency radiation to mouse heads does not induce cell death or cell proliferation in brain

PubMed Central

Kim, Tae-Hyoung; Huang, Tai-Qin; Jang, Ja-June; Kim, Man Ho; Kim, Hyun-Jeong; Lee, Jae-Seon; Pack, Jeong Ki; Seo, Jeong-Sun

2008-01-01

Even though there is no direct evidence to prove the cellular and molecular changes induced by radiofrequency (RF) radiation itself, we cannot completely exclude the possibility of any biological effect of mobile phone frequency radiation. We established a carousel-type exposure chamber for 849 MHz or 1763 MHz of mobile phone RF radiation to expose RF to the heads of C57BL mice. In this chamber, animals were irradiated intermittently at 7.8 W/kg for a maximum of 12 months. During this period, the body weights of 3 groups-sham, 849 MHz RF, and 1763 MHz RF-did not show any differences between groups. The brain tissues were obtained from 3 groups at 6 months and 12 months to examine the differences in histology and cell proliferation between control and RF exposure groups, but we could not find any change upon RF radiation. Likewise, we could not find changes in the expression and distribution of NeuN and GFAP in hippocampus and cerebellum, or in cell death by TUNEL assay in RF exposure groups. From these data, we conclude that the chronic exposure to 849 MHz and 1763 MHz RF radiation at a 7.8 W/kg specific absorption rate (SAR) could not induce cellular alterations such as proliferation, death, and reactive gliosis. PMID:18587267

Science and Technology Review September 1999

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

Eimerl, D

1999-09-01

This review consists of the following titles; The Laboratory in the News; Life Performance of Complex Systems; A Better Picture of Aging Materials; Researchers Determine Chernobyl Liquidators' Exposure; and Target Chamber's Dedication Marks a Giant Milestone.

Ion-beam treatment to prepare surfaces of p-CdTe films

DOEpatents

Gessert, Timothy A.

2001-01-01

A method of making a low-resistance electrical contact between a p-CdTe layer and outer contact layers by ion beam processing comprising: a) placing a CdS/CdTe device into a chamber and evacuating the chamber; b) orienting the p-CdTe side of the CdS/CdTe layer so that it faces apparatus capable of generating Ar atoms and ions of preferred energy and directionality; c) introducing Ar and igniting the area of apparatus capable of generating Ar atoms and ions of preferred energy and directionality in a manner so that during ion exposure, the source-to-substrate distance is maintained such that it is less than the mean-free path or diffusion length of the Ar atoms and ions at the vacuum pressure; d) allowing exposure of the p-CdTe side of the device to said ion beam for a period less than about 5 minutes; and e) imparting movement to the substrate to control the real uniformity of the ion-beam exposure on the p-CdTe side of the device.

Issues related to dust aerosols in the magnesite industry. I. Chamber exposure.

PubMed

Reichrtová, E; Takác, L

1992-01-01

The present paper is an overview of the experimental research into the effects of flue magnesite dust in the magnesite industry in which the raw material (magnesite) is processed into refractory magnesite clinker. The issues related to dust are divided into two problem areas: a) dust aerosol arising in the process of ore mining and consisting largely of magnesite (MgCO3) and b) dust aerosol originating during ore baking in rotatory furnaces and made up mostly of MgO. Thus, larger groups of people become exposed to these aerosols as a result of solid particles escaping into the atmosphere than in the case of occupational exposure. Experimental research carried out on laboratory animals after chamber exposure provided findings on the deposition, retention and elimination of magnesite dust, on impaired balance between magnesium and calcium leading to damage of biological membranes, on how the immune profile or reproduction and embryogenesis is impacted as well as on the possible interaction with sodium salicylate as a result of an impaired acid base balance. These findings are followed up by evidence produced in the course of biological monitoring (Part II).

Effects of air exchange property of passive-type radon-thoron discriminative detectors on performance of radon and thoron measurements.

PubMed

Omori, Y; Janik, M; Sorimachi, A; Ishikawa, T; Tokonami, S

2012-11-01

Pairs of diffusion chambers with different air exchange rates are used in a large-scale survey to determine radon and thoron, separately. When they are enclosed in radon-proof bags for keeping after the exposure, since radon does not escape out immediately from the low-diffusion chamber, it leads to further exposure in the bags and disturbs the estimation of radon and thoron concentrations. In this study, the effects of the different air exchange properties of the radon-thoron discriminative detectors with CR-39 chips on the estimations of radon and thoron concentrations were investigated. The commercially available and frequently used detectors, Raduet, are examined in this study. The result shows that radon escapes out in 10 h. When degassing is not enough after the exposure in a calibration experiment or high-background radiation area, the residual radon causes the overestimation of the radon concentration and increase in the uncertainty in the thoron concentration, i.e. a low-performance quality of radon and thoron measurements.

Alcohol exposure during development: analysis of effects on female sexual behavior.

PubMed

Gass, Justin T; Jenkins, William J; Marino, Melissa D; Lugo, Joaquin N; Kelly, Sandra J

2007-12-01

Alcohol exposure during development has been shown to alter a variety of social behaviors in both humans and rodents. Sexual behavior in rodents has been well characterized and lends itself to a detailed investigation of the manner in which ethanol impacts this particular social behavior. Rats were exposed to ethanol during both the prenatal and early postnatal period (ET). Control groups included rats exposed to the administration procedures alone (intubated-control) and nontreated controls (NC). Sexual behavior of intact naïve female rats in estrus was assessed in adulthood (approximately postnatal day 90) and activity was measured by the number of crossings between chambers in the 3-chamber test apparatus. A separate study examined the olfactory preferences for 4 odors by intact naïve female rats in all 3 groups. The 4 odors were the odors resulting from 1 hour of occupation of the test chamber by an intact male, 1 hour of occupation of the test chamber by a gonadectomized male, 0.5 ml of urine from an intact male, and 0.5 ml of urine from a gonadectomized male. ET female rats showed a reduced return latency after ejaculation compared to both control groups. There was a trend toward a reduction in percent exits after all forms of male behavior in the ET animals compared to the control groups. No significant differences across groups were seen in the lordosis quotient, activity, or the behavior of the nonexperimental male. ET female rats showed a reduced preference for the odor from the intact male compared to both control groups and a reduced preference for the odor from the gonadectomized male compared to NC females only. These data suggest that ethanol exposure during the prenatal and postnatal period in females alters sexual motivation and changes the processing of olfactory cues and possibly coital cues from male rats.

Acoustic emission monitoring of tensile testing of corroded and un-corroded clad aluminum 2024-T3 and characterization of effects of corrosion on AE source events and material tensile properties

NASA Astrophysics Data System (ADS)

Okafor, A. Chukwujekwu; Natarajan, Shridhar

2014-02-01

Corrosion damage affects structural integrity and deteriorates material properties of aluminum alloys in aircraft structures. Acoustic Emission (AE) is an effective nondestructive evaluation (NDE) technique for monitoring such damages and predicting failure in large structures of an aircraft. For successful interpretation of data from AE monitoring, sources of AE and factors affecting it need to be identified. This paper presents results of AE monitoring of tensile testing of corroded and un-corroded clad Aluminum 2024-T3 test specimens, and characterization of the effects of strain-rate and corrosion damage on material tensile properties and AE source events. Effect of corrosion was studied by inducing corrosion in the test specimens by accelerated corrosion testing in a Q-Fog accelerated corrosion chamber for 12 weeks. Eight (8) masked dog-bone shaped specimens were placed in the accelerated corrosion chamber at the beginning of the test. Two (2) dog-bone shaped specimens were removed from the corrosion chamber after exposure time of 3, 6, 9, and 12 weeks respectively, and subjected to tension testing till specimen failure along with AE monitoring, as well as two (2) reference samples not exposed to corrosion. Material tensile properties (yield strength, ultimate tensile strength, toughness, and elongation) obtained from tension test and AE parameters obtained from AE monitoring were analyzed and characterized. AE parameters increase with increase in exposure period of the specimens in the corrosive environment. Aluminum 2024-T3 is an acoustically silent material during tensile deformation without any damage. Acoustic emission events increase with increase of corrosion damage and with increase in strain rate above a certain value. Thus AE is suitable for structural health monitoring of corrosion damage. Ultimate tensile strength, toughness and elongation values decrease with increase of exposure period in corrosion chamber.

Linking a dermal permeation and an inhalation model to a simple pharmacokinetic model to study airborne exposure to di(n-butyl) phthalate.

PubMed

Lorber, Matthew; Weschler, Charles J; Morrison, Glenn; Bekö, Gabriel; Gong, Mengyan; Koch, Holger M; Salthammer, Tunga; Schripp, Tobias; Toftum, Jørn; Clausen, Geo

2017-11-01

Six males clad only in shorts were exposed to high levels of airborne di(n-butyl) phthalate (DnBP) and diethyl phthalate (DEP) in chamber experiments conducted in 2014. In two 6 h sessions, the subjects were exposed only dermally while breathing clean air from a hood, and both dermally and via inhalation when exposed without a hood. Full urine samples were taken before, during, and for 48 h after leaving the chamber and measured for key DnBP and DEP metabolites. The data clearly demonstrated high levels of DnBP and DEP metabolite excretions while in the chamber and during the first 24 h once leaving the chamber under both conditions. The data for DnBP were used in a modeling exercise linking dose models for inhalation and transdermal permeation with a simple pharmacokinetic model that predicted timing and mass of metabolite excretions. These models were developed and calibrated independent of these experiments. Tests included modeling of the "hood-on" (transdermal penetration only), "hood-off" (both inhalation and transdermal) scenarios, and a derived "inhalation-only" scenario. Results showed that the linked model tended to duplicate the pattern of excretion with regard to timing of peaks, decline of concentrations over time, and the ratio of DnBP metabolites. However, the transdermal model tended to overpredict penetration of DnBP such that predictions of metabolite excretions were between 1.1 and 4.5 times higher than the cumulative excretion of DnBP metabolites over the 54 h of the simulation. A similar overprediction was not seen for the "inhalation-only" simulations. Possible explanations and model refinements for these overpredictions are discussed. In a demonstration of the linked model designed to characterize general population exposures to typical airborne indoor concentrations of DnBP in the United States, it was estimated that up to one-quarter of total exposures could be due to inhalation and dermal uptake.

Indoor Measurements of Environmental Tobacco Smoke Final Report to the Tobacco Related Disease Research Program

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

Apte, Michael G.; Gundel, Lara A.; Dod, Raymond L.

2004-03-02

The objective of this research project was to improve the basis for estimating environmental tobacco smoke (ETS) exposures in a variety of indoor environments. The research utilized experiments conducted in both laboratory and ''real-world'' buildings to (1) study the transport of ETS species from room to room, (2) examine the viability of using various chemical markers as tracers for ETS, and (3) to evaluate to what extent re-emission of ETS components from indoor surfaces might add to the ETS exposure estimates. A three-room environmental chamber was used to examine multi-zone transport and behavior of ETS and its tracers. One roommore » (simulating a smoker's living room) was extensively conditioned with ETS, while a corridor and a second room (simulating a child's bedroom) remained smoking-free. A series of 5 sets of replicate experiments were conducted under different door opening and flow configurations: sealed, leaky, slightly ajar, wide open, and under forced air-flow conditions. When the doors between the rooms were slightly ajar the particles dispersed into the other rooms, eventually reaching the same concentration. The particle size distribution took the same form in each room, although the total numbers of particles in each room depended on the door configurations. The particle number size distribution moved towards somewhat larger particles as the ETS aged. We also successfully modeled the inter-room transport of ETS particles from first principles--using size fractionated particle emission factors, predicted deposition rates, and thermal temperature gradient driven inter-room flows, This validation improved our understanding of bulk inter-room ETS particle transport. Four chemical tracers were examined: ultraviolet-absorbing particulate matter (UVPM), fluorescent particulate matter (FPM), nicotine and solanesol. Both (UVPM) and (FPM) traced the transport of ETS particles into the non-smoking areas. Nicotine, on the other hand, quickly adsorbed on unconditioned surfaces so that nicotine concentrations in these rooms remained very low, even during smoking episodes. These findings suggest that using nicotine as a tracer of ETS particle concentrations may yield misleading concentration and/or exposure estimates. The results of the solanesol analyses were compromised, apparently by exposure to light during collection (lights in the chambers were always on during the experiments). This may mean that the use of solanesol as a tracer is impractical in ''real-world'' conditions. In the final phase of the project we conducted measurements of ETS particles and tracers in three residences occupied by smokers who had joined a smoking cessation program. As a pilot study, its objective was to improve our understanding of how ETS aerosols are transported in a small number of homes (and thus, whether limiting smoking to certain areas has an effect on ETS exposures in other parts of the building). As with the chamber studies, we examined whether measurements of various chemical tracers, such as nicotine, solanesol, FPM and UVPM, could be used to accurately predict ETS concentrations and potential exposures in ''real-world'' settings, as has been suggested by several authors. The ultimate goal of these efforts, and a future larger multiple house study, is to improve the basis for estimating ETS exposures to the general public. Because we only studied three houses no firm conclusions can be developed from our data. However, the results for the ETS tracers are essentially the same as those for the chamber experiments. The use of nicotine was problematic as a marker for ETS exposure. In the smoking areas of the homes, nicotine appeared to be a suitable indicator; however in the non-smoking regions, nicotine behavior was very inconsistent. The other tracers, UVPM and FPM, provided a better basis for estimating ETS exposures in the ''real world''. The use of solanesol was compromised--as it had been in the chamber experiments.« less

Stress integration after acute and chronic predator stress: differential activation of central stress circuitry and sensitization of the hypothalamo-pituitary-adrenocortical axis.

PubMed

Figueiredo, Helmer F; Bodie, Bryan L; Tauchi, Miyuki; Dolgas, C Mark; Herman, James P

2003-12-01

Predator exposure is a naturalistic stressor of high ethological relevance. In the current study, our group examined central and peripheral integration of stress responses in rats after acute or repeated exposure to a natural predator (cat). Acute cat exposure rapidly induced hypothalamo-pituitary-adrenocortical (HPA) axis activation and paraventricular nucleus (PVN) CRH mRNA production. Repeated daily cat exposure (7 and 14 d) also up-regulated PVN mRNA CRH expression, but did not result in frank adrenocortical hyperactivity. Unlike other chronic homotypic stress regimens, repeated cat exposure facilitated corticosterone secretion after the 6th or 13th day of exposure. Notably, ACTH secretion and central amygdaloid nucleus CRH mRNA expression were enhanced in animals that were preexposed to the holding chamber relative to chamber-naive rats, suggesting that contextual cues can sensitize subsequent responses to a fearful stimulus. Analysis of c-fos activation was then used to identify brain circuits activated by acute predator stress. Cat exposure elicited a pattern of central c-fos activation that differed substantially from that after either restraint or hypoxia. Predator-specific c-fos mRNA induction was observed in several brain regions comprising the hypothetical brain defense circuit (bed nucleus of the stria terminalis, medial region of the ventromedial nucleus, and dorsal premammillary nucleus). Surprisingly, acute cat exposure did not induce c-fos expression in the PVN. In summary, the data indicate that 1) predation stress invokes a unique stress circuitry that promotes homotypic sensitization of the HPA axis, and 2) familiarization of animals to testing environments can prime central stress pathways to respond robustly to novel threats.

Response of giant sequoia canopy foliage to elevated concentrations of atmospheric ozone

Treesearch

Nancy Grulke; P.R. Miller; D. Scioli

1996-01-01

We examined the physiological response of foliage in the upper third of the canopy of 125-year-old giant sequoia (Sequoiadendron giganteum Buchholz.) trees to a 61-day exposure to 0.25x, 1x, 2x or 3x ambient ozone concentration. Four branch exposure chambers, one per ozone treatment, were installed on 1-m long secondary branches of each tree at a...

Toxicokinetic Study for Investigation of Sex Differences in Internal Dosimetry of Jet Propulsion Fuel 8 (JP-8) in the Laboratory Rat

DTIC Science & Technology

2013-07-26

8 (2000 mg/m 3 ) may have produced transient impairment of rat cochlear outer hair cell function in the absence of noise (Fechter et al., 2010); the...system is a dynamic, non- rebreathing system. In this system, an exposure atmosphere flow rate of approximately 0.5 L/min per open port was maintained...exposure atmosphere flow to the chamber or the exhaust. The outer plenum of the nose-only exposure system carried the animals’ exhaled breath and excess

Acoustic filtration and sedimentation of soot particles

NASA Astrophysics Data System (ADS)

Martin, K. M.; Ezekoye, O. A.

Removal of soot particles from a static chamber by an intense acoustic field is investigated. Combustion of a solid fuel fills a rectangular chamber with small soot particles, which sediment very slowly. The chamber is then irradiated by an intense acoustic source to produce a three dimensional standing wave field in the chamber. The acoustic excitation causes the soot particles to agglomerate, forming larger particles which sediment faster from the system. The soot also forms 1-2 cm disks, with axes parallel to the axis of the acoustic source, which are levitated by the sound field at half-wavelength spacing within the chamber. Laser extinction measurements are made to determine soot volume fractions as a function of exposure time within the chamber. The volume fraction is reduced over time by sedimentation and by particle migration to the disks. The soot disks are considered to be a novel mechanism for particle removal from the air stream, and this mechanism has been dubbed acoustic filtration. An experimental method is developed for comparing the rate of soot removal by sedimentation alone with the rate of soot removal by sedimentation and acoustic filtration. Results show that acoustic filtration increases the rate of soot removal by a factor of two over acoustically-induced sedimentation alone.

Apparatus and method for oxidation and stabilization of polymeric materials

DOEpatents

Paulauskas, Felix L [Knoxville, TN; White, Terry L [Knoxville, TN; Sherman, Daniel M [Knoxville, TN

2009-05-19

An apparatus for treating polymeric materials comprises a treatment chamber adapted to maintain a selected atmosphere; a means for supporting the polymeric material within the chamber; and, a source of plasma-derived gas containing at least one reactive oxidative species whereby the polymer is stabilized and cross linked through exposure to the oxidative species in the chamber at a selected temperature. The polymer may be directly exposed to the plasma, or alternatively, the plasma may be established in a separate volume from which the reactive species may be extracted and introduced into the vicinity of the polymer. The apparatus may be configured for either batch-type or continuous-type processing. The apparatus and method are especially useful for preparing polymer fibers, particularly PAN fibers, for later carbonization treatments.

Apparatus and method for oxidation and stabilization of polymeric materials

DOEpatents

Paulauskas, Felix L [Knoxville, TN; White, Terry L [Knoxville, TN; Sherman, Daniel M [Knoxville, TN

2010-08-31

An apparatus for treating polymeric materials comprises a treatment chamber adapted to maintain a selected atmosphere; a means for supporting the polymeric material within the chamber; and, a source of plasma-derived gas containing at least one reactive oxidative species whereby the polymer is stabilized and cross linked through exposure to the oxidative species in the chamber at a selected temperature. The polymer may be directly exposed to the plasma, or alternatively, the plasma may be established in a separate volume from which the reactive species may be extracted and introduced into the vicinity of the polymer. The apparatus may be configured for either batch-type or continuous-type processing. The apparatus and method are especially useful for preparing polymer fibers, particularly PAN fibers, for later carbonization treatments.

Method for determining the effects of oxygen plasma on a specimen

NASA Technical Reports Server (NTRS)

Whitaker, Ann F. (Inventor)

1991-01-01

A method for determining the effects of exposure of oxygen plasma on a specimen such as a thin film polymer or thin metals. The method includes providing an apparatus with a chamber having a holder supporting the polymer specimen in a plasma environment provided in the chamber. The chamber is regulated to a predetermined pressure and set temperature prior to the introduction of oxygen plasma therein. The specimen is then subjected to the plasma environment for a predetermined time during which time the temperature of the specimen is sensed and regulated to be maintained at the set temperature. Temperature sensing is accomplished by a probe which senses any changes in bulk sample temperature. Temperature regulation is provided by a thermoelectric module and by a coolant flow tube.

Changes in the U.S. Primary Standards for the Air Kerma From Gamma-Ray Beams

PubMed Central

Seltzer, Stephen M.; Bergstrom, Paul M.

2003-01-01

Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from 60Co, 137Cs, and 192Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for 60Co beams, +0.64 % to +1.07 % (depending on the chamber) for 137Cs beams, and −0.06 % for the single chamber used in the measurement of the standardized 192Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work. PMID:27413615

Changes in the U.S. Primary Standards for the Air Kerma From Gamma-Ray Beams.

PubMed

Seltzer, Stephen M; Bergstrom, Paul M

2003-01-01

Monte Carlo photon-electron transport calculations have been done to derive new wall corrections for the six NBS-NIST standard graphite-wall, air-ionization cavity chambers that serve as the U.S. national primary standard for air kerma (and exposure) for gamma rays from (60)Co, (137)Cs, and (192)Ir sources. The data developed for and from these calculations have also been used to refine a number of other factors affecting the standards. The largest changes are due to the new wall corrections, and the total changes are +0.87 % to +1.11 % (depending on the chamber) for (60)Co beams, +0.64 % to +1.07 % (depending on the chamber) for (137)Cs beams, and -0.06 % for the single chamber used in the measurement of the standardized (192)Ir source. The primary standards for air kerma will be adjusted in the near future to reflect the changes in factors described in this work.

An overview of changes in pressure values of the middle ear using impedance audiometry among diver candidates in a hyperbaric chamber before and after a pressure test

NASA Astrophysics Data System (ADS)

Anoraga, J. S.; Bramantyo, B.; Bardosono, S.; Simanungkalit, S. H.; Basiruddin, J.

2017-08-01

Impedance audiometry is not yet routinely used in pressure tests, especially in Indonesia. Direct exposure to pressure in a hyperbaric chamber is sometimes without any assessment of the middle ear or the Eustachian tube function (ETF) of ventilation. Impedance audiometry examinations are important to assess ETF ventilation. This study determined the middle ear pressure value changes associated with the ETF (ventilation) of prospective divers. This study included 29 prospective divers aged 20-40 years without conductive hearing loss. All subjects underwent a modified diving impedance audiometry examination both before and after the pressure test in a double-lock hyperbaric chamber. Using the Toynbee maneuver, the values obtained for changes of pressure in the middle ear were significant before and after the pressure test in the right and left ears: p < 0.001 and p = 0.018, respectively. The impedance audiometry examination is necessary for the selection of candidate divers undergoing pressure tests within a hyperbaric chamber.

Germination and growth of lettuce (Lactuca sativa) at low atmospheric pressure

NASA Technical Reports Server (NTRS)

Spanarkel, Robert; Drew, Malcolm C.

2002-01-01

The response of lettuce (Lactuca sativa L. cv. Waldmann's Green) to low atmospheric pressure was examined during the initial 5 days of germination and emergence, and also during subsequent growth to vegetative maturity at 30 days. Growth took place inside a 66-l-volume low pressure chamber maintained at 70 kPa, and plant response was compared to that of plants in a second, matching chamber that was at ambient pressure (approximately 101 kPa) as a control. In other experiments, to determine short-term effects of low pressure transients, plants were grown at ambient pressure until maturity and then subjected to alternating periods of 24 h of low and ambient atmospheric pressures. In all treatments the partial pressure of O2 was maintained at 21 kPa (approximately the partial pressure in air at normal pressure), and the partial pressure of CO2 was in the range 66.5-73.5 Pa (about twice that in normal air) in both chambers, with the addition of CO2 during the light phase. With continuous exposure to low pressure, shoot and root growth was at least as rapid as at ambient pressure, with an overall trend towards slightly greater performance at the lower pressure. Dark respiration rates were greater at low pressure. Transient periods at low pressure decreased transpiration and increased dark respiration but only during the period of exposure to low pressure. We conclude that long-term or short-term exposure to subambient pressure (70 kPa) was without detectable detriment to vegetative growth and development.

Amygdala activity associated with social choice in mice.

PubMed

Mihara, Takuma; Mensah-Brown, Kobina; Sobota, Rosanna; Lin, Robert; Featherstone, Robert; Siegel, Steven J

2017-08-14

Studies suggest that the amygdala is a key region for regulation of anxiety, fear and social function. Therefore, dysfunction of the amygdala has been proposed as a potential mechanism for negative symptoms in schizophrenia. This may be due to NMDA receptor-mediated hypofunction, which is thought to be related to the pathogenesis of schizophrenia. In this study, electroencephalographic amygdala activity was assessed in mice during the three-chamber social test. This activity was also evaluated following exposure to the NMDA receptor antagonist ketamine. Vehicle-treated mice spent significantly more time in the social than the non-social chamber. This social preference was eliminated by ketamine. However, ketamine-treated mice spent significantly less time in the social chamber and significantly more time in the nonsocial chamber than vehicle-treated mice. There were no significant differences in induced powers between social and non-social chamber entries in vehicle-treated mice, except for theta frequencies, which featured greater induced theta power during non-social chamber entry. Ketamine eliminated differences in induced theta power between social and non-social chamber entries. Moreover, ketamine increased the induced gamma power during social chamber entry compared to that of vehicle-treated mice. All other frequency ranges were not significantly influenced by zone or drug condition. All significant findings were upon entry to chambers not during interaction. Results suggest that impaired function of NMDA receptor-mediated glutamate transmission can induce social impairments and amygdala dysfunction, similar to the pattern in schizophrenia. Future studies will utilize this method to evaluate mechanisms of social dysfunction and development of treatments of social impairments in schizophrenia. Copyright © 2017. Published by Elsevier B.V.

Characterization and testing of a new environmental chamber designed for emission aging studies

NASA Astrophysics Data System (ADS)

Leskinen, A.; Yli-Pirilä, P.; Kuuspalo, K.; Sippula, O.; Jalava, P.; Hirvonen, M.-R.; Jokiniemi, J.; Virtanen, A.; Komppula, M.; Lehtinen, K. E. J.

2014-06-01

A 29 m3 Teflon chamber, designed for aging studies of combustion aerosols, at the University of Eastern Finland is described and characterized. The chamber belongs to a research facility, called Ilmari, where small-scale combustion devices, a dynamometer for vehicle exhaust studies, dilution systems, the chamber, as well as cell and animal exposure devices are side by side under the same roof. The small surface-to-volume ratio of the chamber enables reasonably long experiment times, with particle wall loss rate constants of 0.088, 0.080, 0.045, and 0.040 h-1 for polydisperse, 50, 100, and 200 nm monodisperse aerosols, respectively. The NO2 photolysis rate can be adjusted from zero to 0.62 min-1. The irradiance spectrum is centered at 365 nm and the maximum irradiance, produced by 160 blacklight lamps, is 29.7 W m-2, which corresponds to the UV irradiance in Central Finland at noon on a sunny day in the midsummer. The temperature inside the chamber is uniform and can be kept at 25 ± 1 °C when half of the blacklights are on. The chamber is kept in an overpressure with a moving top frame, which prevents sample dilution and contamination from entering the chamber during an experiment. The functionality of the chamber was tested with oxidation experiments of toluene, resulting in secondary organic aerosol (SOA) yields of 33-44%, depending on the initial conditions, such as the NOx concentration. The highest gaseous oxidation product yields of 14.4-19.5% were detected with ions corresponding to 2-butenedial (m/z 73.029) and 4-oxo-2-pentenal (m/z 99.044). Overall, reasonable yields of SOA and gaseous reaction products, comparable to those obtained in other laboratories, were obtained.

Meadow voles, Microtus pennsylvanicus, have the capacity to recall the "what", "where", and "when" of a single past event.

PubMed

Ferkin, Michael H; Combs, Amy; delBarco-Trillo, Javier; Pierce, Andrew A; Franklin, Stan

2008-01-01

Some non-human animals may possess the ability to recall the "what", "where", and "when" of a single past event. We tested the hypothesis that male meadow voles possess the capacity to recall the "what", "where", and "when" of a single past event associated with mate selection in two experiments. Briefly, male voles were allowed to explore an apparatus that contained two chambers. One chamber contained a day-20 pregnant female (24 h prepartum). The other chamber contained a sexually mature female that was neither pregnant nor lactating (REF female). Twenty-four hour after the exposure, the males were placed in the same apparatus, which was empty and clean. At this time, the pregnant female would have entered postpartum estrus (PPE), a period of heightened sexual receptivity. Males initially chose and spent significantly more time investigating the chamber that originally housed the pregnant female (now a PPE female) than the chamber that originally housed the REF female. Male voles also explored an apparatus containing a chamber with a PPE female and one chamber containing a REF female. Twenty-four hour later, males were placed into an empty and clean apparatus. The males did not display an initial choice and they spent similar amounts of time investigating the chamber that originally housed the PPE female (now a lactating female) and the chamber that originally housed the REF female. The results of these and additional experiments suggest that male voles may have the capacity to recall the "what", "where", and "when" of a single past event, which may allow males to remember the location of females who would currently be in heightened states of sexual receptivity.

Temperature changes in the pulpal chamber and the sealing performance of various methods of direct pulp capping of primary teeth.

PubMed

Yilmaz, Y; Keles, S; Mete, A

2013-06-01

To compare changes in pulpal chamber temperature during the visible-light curing of direct pulp capping compounds and various modes of diode laser irradiation without prior placement of a pulp capping compound and the resultant seals. Pulp exposure holes were made in 100 extracted human primary first molars, which were randomly assigned to ten equal groups. The holes were sealed by (a= Group 1, 2, 3, 4, 5, 6 and 7) different pulp capping compounds which were cured using various types of visible-light curing units or (b=Group 8, 9 and 10) diode laser irradiation without prior application of a pulp capping compound. Pulpal chamber temperatures were recorded during the procedure, and the resultant seals were examined under a scanning electron microscope. Visible-light curing of the pulp capping compounds and diode laser irradiation at a 0.7 W output power can cause non-injurious temperature rises in the pulpal chamber. At higher output powers of the diode laser, the temperature rises are sufficient to cause thermal injury. The seals were complete when pulp capping compounds were used for direct pulp capping, but were incomplete when laser irradiation without prior placement of a pulp capping compound was used for the identical purpose. The visible-light curing of pulp capping compounds is not harmful to vital pulp, and provides an effective seal of the pulp exposure hole. Laser irradiation is not an effective sealant, and can cause thermal injury to vital pulp at high output powers.

Chemosensory irritations and pulmonary effects of acute exposure to emissions from oriented strand board.

PubMed

Gminski, Richard; Marutzky, Rainer; Kevekordes, Sebastian; Fuhrmann, Frank; Bürger, Werner; Hauschke, Dieter; Ebner, Winfried; Mersch-Sundermann, Volker

2011-09-01

Due to the reduction of air change rates in low-energy houses, the contribution to indoor air quality of volatile organic compounds (VOCs) emitting from oriented strand boards (OSB) has become increasingly important. The aim of this study was to evaluate sensory irritations, pulmonary effects and odor annoyance of emissions from OSB in healthy human volunteers compared to clean air. Twenty-four healthy non-smokers were exposed to clean air and OSB emissions for 2 h under controlled conditions in a 48 m(3) test chamber at three different time points: to fresh OSB panels and to the same panels after open storage for 2 and 8 weeks. Chemosensory irritation, exhaled nitric oxide (NO) concentration, eye blink frequency, lung function and subjective perception of irritation of eyes, nose and throat were examined before, during and after exposure. Additionally, olfactory perception was investigated. Total VOC exposure concentrations reached 8.9 ± 0.8 mg/m(3) for the fresh OSB panels. Emissions consisted predominantly of α-pinene, Δ(3)-carene and hexanal. Two-hour exposure to high VOC concentrations revealed no irritating or pulmonary effects. All the subjective ratings of discomfort were at a low level and the medians did not exceed the expression 'hardly at all.' Only the ratings for smell of emissions increased significantly during exposure in comparison to clean air. In conclusion, exposure of healthy volunteers to OSB emissions did not elicit sensory irritations or pulmonary effects up to a VOC concentration of about 9 mg/m(3). Sensory intensity of OSB emissions in the chamber air was rated as 'neutral to pleasant.'

Effects of electromagnetic pulse exposure on gelatinase of blood-brain barrier in vitro.

PubMed

Zhou, Yan; Qiu, Lian-Bo; An, Guang-Zhou; Zhou, Jia-Xing; Du, Le; Ma, Ya-Hong; Guo, Guo-Zhen; Ding, Gui-Rong

2017-01-01

The biological effects of electromagnetic pulse (EMP) on the brain have been focused on for years. It was reported that gelatinase played an important role in maintaining brain function through regulating permeability in the blood-brain barrier (BBB). To investigate the effects of EMP on gelatinase of BBB, an in vitro BBB model was established using primary cultured rat brain microvascular endothelial cells (BMVEC), astrocytes and half-contact culture of these cells in a transwell chamber. Cultured supernatant and cells were collected at different time points after exposure to EMP (peak intensity 400 kV/m, rise time 10 ns, pulse width 350 ns, 0.5 pps and 200 pulses). Protein levels of cellular gelatinase MMP-2 and MMP-9, and endogenous inhibitor TIMP-1 and TIMP-2 were detected by Western blot. The activity of gelatinase in culture supernatant was detected by gelatin zymography. It was found that compared with the sham-exposed group, the protein level of MMP-2 was significantly increased at 6 h (p < 0.05), and the protein level of its endogenous inhibitor TIMP-2 did not change after EMP exposure. In addition, the protein levels of MMP-9 and its endogenous inhibitor TIMP-1 did not change after EMP exposure. Gelatin zymography results showed that the activity of MMP-2 in the inner pool and the outer pool of the transwell chamber was significantly increased at 6 h after EMP exposure compared with that of the sham group. These results suggested that EMP exposure could affect the expression and activity of MMP-2 in the BBB model.

Chamber study of PCBemissions from caulking materials and ...

EPA Pesticide Factsheets

The emissions of polychlorinated biphenyl (PCB) congeners from 13 caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 different models from five manufacturers were tested in 53-liter environmental chambers. The rates of PCB congener emissions from caulking materials and light ballasts were determined. Several factors that may have affected the emission rates were evaluated. The experimentally determined emission factors showed that, for a given PCB congener, there is a linear correlation between the emission factor and the concentration of the PCB congener in the source. Furthermore, the test results showed that an excellent log-linear correlation exists between the normalized emission factor and the vapor pressure (coefficient of determination, r2 ≥0.8846). The PCB congener emissions from ballasts at or near room temperature were relatively low with or without electrical load. However, the PCB congener emission rates increased significantly as the temperature increased. The results of this research provide new data and models for ranking the primary sources of PCBs and supports the development and refinement of exposure assessment models for PCBs. This study supplemented and complemented the field measurements in buildings conducted by U.S. EPA National Exposure Research Laboratory by providing a bette

Low-amplitude, high-frequency electromagnetic field exposure causes delayed and reduced growth in Rosa hybrida.

PubMed

Grémiaux, Alexandre; Girard, Sébastien; Guérin, Vincent; Lothier, Jérémy; Baluška, František; Davies, Eric; Bonnet, Pierre; Vian, Alain

2016-01-15

It is now accepted that plants perceive high-frequency electromagnetic field (HF-EMF). We wondered if the HF-EMF signal is integrated further in planta as a chain of reactions leading to a modification of plant growth. We exposed whole small ligneous plants (rose bush) whose growth could be studied for several weeks. We performed exposures at two different development stages (rooted cuttings bearing an axillary bud and 5-leaf stage plants), using two high frequency (900MHz) field amplitudes (5 and 200Vm(-1)). We achieved a tight control on the experimental conditions using a state-of-the-art stimulation device (Mode Stirred Reverberation Chamber) and specialized culture-chambers. After the exposure, we followed the shoot growth for over a one-month period. We observed no growth modification whatsoever exposure was performed on the 5-leaf stage plants. When the exposure was performed on the rooted cuttings, no growth modification was observed on Axis I (produced from the elongation of the axillary bud). Likewise, no significant modification was noted on Axis II produced at the base of Axis I, that came from pre-formed secondary axillary buds. In contrast, Axis II produced at the top of Axis I, that came from post-formed secondary buds consistently displayed a delayed and significant reduced growth (45%). The measurements of plant energy uptake from HF-EMF in this exposure condition (SAR of 7.2 10(-4)Wkg(-1)) indicated that this biological response is likely not due to thermal effect. These results suggest that exposure to electromagnetic field only affected development of post-formed organs. Copyright © 2015 Elsevier GmbH. All rights reserved.

Device for producing a fluid stream of varying composition

DOEpatents

Moss, Owen R.; Clark, Mark L.; Rossignol, E. John

1982-01-01

A device for producing a fluid stream of varying composition comprises a chamber having an inlet at one end and outlet at the other. Between the inlet and outlet there are substantially planar pans or baffles positioned normal to the bulk flow of fluid between the inlet and the outlet. These pans are arranged in pairs. Each pan, except those of the pair most remote from the inlet, is spaced from the walls of the chamber to permit air to flow past it. The pans of each pair are also spaced from each other, in a direction parallel to their planes, leaving an empty space along the mid-plane of the chamber. This produces a circulation and mixing of fluid between the pairs of pans or baffles. A secondary stream of fluid is introduced between two pairs of baffles in the intermediate portion of the chamber, so that the composition of the fluid is different in the portion adjacent to the outlet and the portion adjacent to the inlet. In a specific embodiment, the device is an exposure chamber for experimental animals, and the pans or baffles are catch pans for excrement.

Critical Care Performance in a Simulated Military Aircraft Cabin Environment

DTIC Science & Technology

2007-01-01

resources are depleted due to other factors such as fatigue or anxiety . The decline in 21 accuracy of serial reaction as time progresses is perhaps the most...exposure to moderate simulated altitude levels could modify heart rate variability ( HRV ) during exercise. HRV is indicative of the autonomic nervous...various altitudes in a hypobaric chamber, and the ascent to the different altitudes was separated by 2 hours. Acute effects of altitude exposure on HRV

Smog exposure and host resistance to respiratory pathogens ...

EPA Pesticide Factsheets

The US EPA is evaluating the health effects of photochemical smog on respiratory, cardiovascular and metabolic health (https://www.epa.gov/air-research/secondary-organic-aerosol-soas-research). Smog exposure has been associated with an increased risk of allergy and decreased resistance to respiratory infections; we therefore investigated the effects of smog on the host response to respiratory pathogens. Atmospheres were generated in a chamber fed with selected hydrocarbons (gasoline + -pinene-“smog A” or gasoline +isoprene-“smog B”), and subjected to ultraviolet light. Final chamber concentrations were 252 ppb NO2, 104 ppb O3, and 1070 ug/m3 secondary organic aerosol, SOA) (Smog A) or 617 ppb NO2, 376 ppb O3, and 53 ug/m3 SOA (Smog B). Balb/C female mice were exposed to filtered air or smog for 4 h/d X 5 d; subgroups of control and exposed mice were either immunized with heat-killed Streptococcus pneumoniae (HKSP; smog A) or infected with mouse-adapted influenza A/Puerto Rico/8/34 (H1N1) on the first or last day of exposure. Mice were necropsied 7 d after immunization or infection and markers of lung damage and resistance to infection were assessed. Exposure to smog A did not alter the concentration of antibody to HKSP in the serum or concentrations of protein, lactate dehydrogenase or leukocyte concentrations in the bronchoalveolar lavage fluid (BALF),although the % neutrophils was greater in the post-exposure air group. Virus burdens were similar i

Gender not a factor for altitude decompression sickness risk

NASA Technical Reports Server (NTRS)

Webb, James T.; Kannan, Nandini; Pilmanis, Andrew A.

2003-01-01

INTRODUCTION: Early, retrospective reports of the incidence of altitude decompression sickness (DCS) during altitude chamber training exposures indicated that women were more susceptible than men. We hypothesized that a controlled, prospective study would show no significant difference. METHODS: We conducted 25 altitude chamber decompression exposure profiles. A total of 291 human subjects, 197 men and 94 women, underwent 961 exposures to simulated altitude for up to 8 h, using zero to 4 h of preoxygenation. Throughout the exposures, subjects breathed 100% oxygen, rested or performed mild or strenuous exercise, and were monitored for precordial venous gas emboli (VGE) and DCS symptoms. RESULTS: No significant differences in DCS incidence were observed between men (49.5%) and women (45.3%). However, VGE occurred at significantly higher rates among men than women under the same exposure conditions, 69.3% and 55.0% respectively. Women using hormonal contraception showed significantly greater susceptibility to DCS than those not using hormonal contraception during the latter two weeks of the menstrual cycle. Significantly higher DCS incidence was observed in the heaviest men, in women with the highest body fat, and in subjects with the highest body mass indices and lowest levels of fitness. CONCLUSION: No differences in altitude DCS incidence were observed between the sexes under our test conditions, although men developed VGE more often than women. Age and height showed no significant influence on DCS incidence, but persons of either sex with higher body mass index and lower physical fitness developed DCS more frequently.

Low level CO2 effects on pulmonary function in humans

NASA Technical Reports Server (NTRS)

Sexton, J.; Mueller, K.; Elliott, A.; Gerzer, D.; Strohl, K. P.; West, J. B. (Principal Investigator)

1998-01-01

The purpose of the study was to determine whether chamber exposure to low levels of CO2 results in functional alterations in gas mixing and closing volume in humans. Four healthy volunteer subjects were exposed to 0.7% CO2 and to 1.2% CO2. Spirometry, lung volumes, single breath nitrogen washout, diffusing capacity for carbon monoxide (DLCO) by two methods, and cardiac output were measured in triplicate. Values were obtained over two non-consecutive days during the training period (control) and on days 2 or 3, 4, 6, 10, 13, and 23 of exposure to each CO2 level. Measurements were made during the same time of day. There was one day of testing after exposure, while still in the chamber but off carbon dioxide. The order of testing, up until measurements of DLCO and cardiac output, were randomized to avoid presentation effects. The consistent findings were a reduction in diffusing capacity for carbon monoxide and a fall in cardiac output, occurring to a similar degree with both exposures. For the group as a whole, there was no indication of major effects on spirometry, lung volumes, gas mixing or dead space. We conclude that small changes may occur in the function of distal gas exchanging units; however, these effects were not associated with any adverse health effects. The likelihood of pathophysiologic changes in lung function or structure with 0.7 or 1.2% CO2 exposure for this period of time, is therefore, low.

Effects of Isoprene- and Toluene-Generated Smog on Allergic ...

EPA Pesticide Factsheets

Reactions of organic compounds with nitric oxide (NO) and sunlight produce complex mixtures of pollutants including secondary organic aerosol (SOA), ozone (O3), nitrogen dioxide (NO2), and reactive aldehydes. The health effects of these photochemical smog mixtures in susceptible populations including asthmatics are unclear. We assessed effects of smog generated from mixtures of NO with isoprene (IS) or toluene (TL) on allergic inflammatory responses in Balb/cJ mice. House dust mite (HDM)-sensitized or control mice were all challenged with HDM intranasally 1 d prior to whole-body inhalation exposure to IS (chamber average 509 ppb NO2, 246 ppb O3, and 160 g/m3 SOA), TL (217 ppb NO2, 129 ppb O3, and 376 g/m3 SOA), or HEPA-filtered air (4 h/d for 2 days). Mice were necropsied within 3 h after the second exposure (2 d post-HDM challenge). Assessment of breathing parameters during exposure with double-chamber plethysmography showed a trend for increased specific airway resistance and decreased minute volume during the second day of TL exposure in both non-allergic and HDM-allergic mice. HDM-allergic air-exposed mice had significant increases in numbers of bronchoalveolar lavage (BAL) alveolar macrophages (AM) and eosinophils (EO), and trends for increases in BAL indices of lung injury in comparison with non-allergic air-exposed mice. Exposure to either IS or TL attenuated the increases in AM, EO, and lung injury markers in HDM-allergic mice. The results of this

Overview of the vapor generation and analysis parameters of the petroleum- and shale-derived fuel studies conducted in thomas dome exposure chambers at the toxic hazards research unit, Wright-Patterson Air Force Base (Dayton), Ohio, 1973-1983. Final report, January 1973-December 1983

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

Leahy, H.F.

1994-05-01

Over a decade ago (1973-1983), a series of long-term inhalation exposures were performed to study the toxicity of a number of aviation and marine fuels derived from petroleum and compare results with those derived from shale. These included JP-4, JP-5, and diesel fuel marine, as well as some specialty petroleum derived fuels W-7, JP-8, and JP-TS. The Thomas Domes located in the Armstrong Laboratory at Wright-Patterson Air Force Base (Dayton), Ohio, were ideally suited for these studies because of both the large capacity for inhalation exposure of the mixed animal complement and the convenience of entry without interrupting continuous exposures.more » The target total hydrocarbon (TH) concentrations ranged from 0.05 to 5.0 mg/L. The concentration levels of TH vapors were limited by the effective vapor pressure of the type of fuel and, if exceeded, the formation of condensate aerosols in the exposure chamber. The Th vapor generation and analytical equipment is described. Advances in gas chromatographic technology during the period covered provided a variety of qualitative pictures of the fuel, vapor, and waste TH components. Hydrocarbons above C14 existed only in very low concentrations in any of the vapors.« less

Effect of protective filters on fire fighter respiratory health: field validation during prescribed burns.

PubMed

De Vos, Annemarie J B M; Cook, Angus; Devine, Brian; Thompson, Philip J; Weinstein, Philip

2009-01-01

Bushfire smoke contains a range of air toxics. To prevent inhalation of these toxics, fire fighters use respiratory equipment. Yet, little is known about the effectiveness of the equipment on the fire ground. Experimental trials in a smoke chamber demonstrated that, the particulate/organic vapor/formaldehyde (POVF) filter performed best under simulated conditions. This article reports on the field validation trials during prescribed burns in Western Australia. Sixty-seven career fire fighters from the Fire and Emergency Services Authority of Western Australia were allocated one of the three types of filters. Spirometry, oximetry, self-reported symptom, and personal air sampling data were collected before, during and after exposure to bushfire smoke from prescribed burns. Declines in FEV(1) and SaO(2) were demonstrated after 60 and 120 min exposure. A significant higher number of participants in the P filter group reported increases in respiratory symptoms after the exposure. Air sampling inside the respirators demonstrated formaldehyde levels significantly higher in the P filter group compared to the POV and the POVF filter group. The field validation trials during prescribed burns supported the findings from the controlled exposure trials in the smoke chamber. Testing the effectiveness of three types of different filters under bushfire smoke conditions in the field for up to 2 hr demonstrated that the P filter is ineffective in filtering out respiratory irritants. The performance of the POV and the POVF filter appears to be equally effective after 2 hr bushfire smoke exposure in the field.

Sorption of Organophosphorus Flame-Retardants on Settled ...

EPA Pesticide Factsheets

Dust is an important sink for indoor air pollutants, such as organophosphorus flame-retardants (OPFRs) that are used as additives in industrial and consumer products including electrical and electronic products, furniture, plastics, textile, and building/construction materials. This research investigated the sorption of OPFRs, tris(2-chloroethyl) phosphate (TCEP), tris(1-chlor-2-propyl) phosphate (TCPP), and tris(1,3-dichloro-2-propyl) phosphate (TDCPP) on settled Arizona Test Dust (ATD) using a dual small chamber system. During the test, seven free film release paper dust trays covered with ATD were placed in the sink test chamber. Constant gas phase OPFRs from the source chamber were dosed into the test chamber. The dust evenly spread on each dust tray was removed from the test chamber at different exposure times to determine the amount of OPFRs absorbed by the dust. The ATD has been characterized for a nominal particle size and surface area. The mass of dust on each of seven dust trays was weighed before the dust was placed inside the sink chamber. OPFRs concentrations at the inlet and faceplate of the test chamber were monitored by collecting polyurethane foam (PUF) samples. The OPFR exposed dust and PUF samples were extracted by 1:1 ethyl acetate/methylene chloride and analyzed on GC/MS. The data were used to calculate the OPFR sorption concentration on the dust through dust/air partition. Settled dust can adsorb OPFR from air. The sorption concentration wa

NTP Toxicology and Carcinogenesis Studies of Chloroprene (CAS No. 126-99-8) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

PubMed

1998-09-01

Chloroprene is used almost exclusively in the manufacture of neoprene (polychloroprene). Chloroprene was chosen for study because it is a high-volume production chemical with limited information on its carcinogenic potential and because it is the 2-chloro analogue of 1,3-butadiene, a potent, multi-species, multi-organ carcinogen. Male and female F344/N rats and B6C3F1 mice were exposed to chloroprene (greater than 96% pure) by inhalation for 16 days, 13 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, Drosophila melanogaster, and B6C3F1 mice (bone marrow cells and peripheral blood erythrocytes). 16-Day Study in Rats: Groups of 10 male and 10 female F344/N rats were exposed to 0, 32, 80, 200, or 500 ppm chloroprene by inhalation, 6 hours per day, 5 days per week, for 16 days. Three 500 ppm males died on day 2 or 3 of the study. Mean body weight gains of 200 ppm males and females and 500 ppm females were significantly less than those of the chamber control groups. On the first day of exposure, rats exposed to 500 ppm were hypoactive and unsteady and had rapid shallow breathing. These effects were also observed to some degree in animals exposed to 200 ppm. After the second day of exposure, the effects in these groups worsened, and hemorrhage from the nose was observed. A normocytic, normochromic, responsive anemia; thrombocytopenia; and increases in serum activities of alanine aminotransferase, glutamate dehydrogenase, and sorbitol dehydrogenase occurred on day 4 in 200 ppm females and 500 ppm males. Kidney weights of 80 and 500 ppm females were significantly greater than those of the chamber control group, as were the liver weights of 200 and 500 ppm females. The incidences of minimal to mild olfactory epithelial degeneration of the nose in all exposed groups of males and females were significantly greater than those in the chamber control groups. The incidence of squamous metaplasia of the respiratory epithelium was significantly increased in 500 ppm males. The incidences of centrilobular to random hepatocellular necrosis in 500 ppm males and 200 ppm females were significantly greater than those in the chamber control groups. 16-Day Study in Mice: Groups of 10 male and 10 female B6C3F1 mice were exposed to 0, 12, 32, 80, or 200 ppm chloroprene by inhalation, 6 hours per day, 5 days per week, for 16 days. All males and females exposed to 200 ppm died on day 2 or day 3 of the study. Mean body weight gains of males exposed to 32 or 80 ppm were significantly less than that of the chamber control group. Mice exposed to 200 ppm exhibited narcosis during exposure and were hypoactive with reduced body tone after the first day of exposure. In general, hematology and clinical chemistry parameters measured for exposed males and females were similar to those of the chamber control groups. Thymus weights of 80 ppm males and females were significantly less than those of the chamber control groups. Liver weights of 80 ppm females were significantly greater than those of the chamber control groups. Increased incidences of multifocal random hepatocellular necrosis occurred in males and females exposed to 200 ppm. Hypertrophy of the myocardium, foci of hemorrhage, and mucosal erosion were observed in three males and three females exposed to 200 ppm. Squamous epithelial hyperplasia of the forestomach was observed in two males and two females exposed to 80 ppm. Thymic necrosis, characterized by karyorrhexis of thymic lymphocytes, was observed in all males and females in the 200 ppm groups. 13-Week Study in Rats: Groups of 10 male and 10 female F344/N rats were exposed to chloroprene at concentrations of 0, 5, 12, 32, 80, or 200 ppm by inhalation, 6 hours per day, 5 days per week, for 13 weeks. One male exposed to 200 ppm died during the study. The final mean body weights and body weight gains of all exposed groups of males and females were similar to those of the chamber control groups. Clinical findings in 200 ppm males included red or clear discharge around the nose and eye region. At week 13, a norm a normocytic, normochromic, and non-responsive anemia occurred in 200 ppm males and females. A thrombocytopenia occurred in 200 ppm males and females on day 2 and in 80 and 200 ppm females on day 22. However, at week 13, platelet counts rebounded and were minimally increased in 200 ppm males and females. On day 2, a minimal to mild increase in activated partial thromboplastin time and prothrombin time occurred in 200 ppm males and females. The 200 ppm males and females also had increased activities of serum alanine aminotransferase, glutamate dehydrogenase, and sorbitol dehydrogenase on day 22; these increases were transient, and by week 13 the serum activities of these enzymes were similar to those of the chamber controls. An alkaline phosphatase enzymeuria occurred in 200 ppm females on day 22; at week 13, an alkaline phosphatase enzymeuria oc-curred in 32, 80, and 200 ppm males and 200 ppm females. At week 13, a proteinuria occurred in 200 ppm males. Liver nonprotein sulfhydryl concentrations in male rats immediately following 1 day or 12 weeks of exposure to 200 ppm and in females exposed to 200 ppm for 12 weeks were significantly less than those of the chamber control groups. Kidney weights of 200 ppm males and females and 80 ppm females were significantly greater than those of the chamber control groups. Sperm motility of 200 ppm males was significantly less than that of the controls. In neurobehavioral assessments, horizontal activity was increased in male rats exposed to 32 ppm or greater and total activity was increased in 32 and 200 ppm males. Increased incidences of minimal to mild olfactory epithelial degeneration and respiratory metaplasia occurred in males and females exposed to 80 or 200 ppm. The incidence of olfactory epithelial degeneration in 32 ppm females was also significantly greater than that in the chamber control group. The incidence of hepatocellular necrosis in 200 ppm females was significantly greater than that in the chamber control group. Scattered chronic inflammation also occurred in the liver of male and female rats in the 200 ppm groups; the incidence in 200 ppm females was significantly greater than that in the chamber control group. The incidences of hemosiderin pigmentation were significantly increased in males and females exposed to 200 ppm. 13-Week Study in Mice: Groups of 10 male and 10 female B6C3F1 mice were exposed to chloroprene at concentrations of 0, 5, 12, 32, or 80 ppm by inhalation, 6 hours per day, 5 days per week, for 13 weeks. All male and female mice survived to the end of the study. The final mean body weight and body weight gain of males exposed to 80 ppm were significantly less than those of the chamber control group. Hematocrit concentrations of females exposed to 32 or 80 ppm and erythrocyte counts of 80 ppm females were significantly less than those of the chamber control group. Platelet counts of 32 and 80 ppm females were also greater than that of the chamber control group. Increased incidences of squamous epithelial hyperplasia of the forestomach occurred in males and females exposed to 80 ppm. 2-Year Study in Rats: Groups of 50 male and 50 female F344/N rats were exposed to chloroprene at concentrations of 0, 12.8, 32, or 80 ppm by inhalation, 6 hours per day, 5 days per week, for 2 years. Survival, Body Weights, and Clinical Findings: Survival of males exposed to 32 or 80 ppm was significantly less than that of the chamber control group. Mean body weights of males exposed to 80 ppm were less than those of the chamber controls after week 93. Masses of the torso were observed during the study in exposed female groups, and these clinical findings correlated with mammary gland fibroadenomas observed at necropsy. Pathology Findings: The incidences of squamous cell papilloma and squamous cell papilloma or squamous cell carcinoma (combined) of the oral cavity in male rats exposed to 32 ppm and male and female rats exposed to 80 ppm were significantly greater than those in the chamber controls and exceeded the historical control ranges. The incidences of thyroid gland follicular cell adenoma or carcinoma (combined) in males exposed to 32 or 80 ppm were significantly greater than that in the chamber control group and exceeded the historical control range. Although the incidences of follicular cell adenoma and follicular cell adenoma or carcinoma (combined) in 80 ppm females were not significantly greater than those in the chamber controls, they did exceed the historical control range for these neoplasms. The incidences of alveolar epithelial hyperplasia of the lung were significantly greater in all exposed groups of males and females than in the chamber control groups. The incidences of alveolar/bronchiolar carcinoma and alveolar/bronchiolar adenoma or carcinoma (combined) in 80 ppm males were slightly greater than those in the chamber control group. Although these neoplasm incidences were not significant, they exceeded the historical control range. The incidence of alveolar/bronchiolar adenoma, although not significant, was greater in 80 ppm females than in the chamber control group. The incidences of multiple fibroadenoma of the mammary gland in all exposed groups of females were greater than that in the chamber control group. The incidences of fibroadenoma (including multiple fibroadenoma) in 32 and 80 ppm females were significantly greater than that in the chamber controls. The incidences of fibroadenoma in the chamber control group and in all exposed groups of females exceeded the historical control range. The severity of nephropathy in exposed groups of male and female rats was slightly greater than in the chamber controls. Renal tubule adenoma and hyperplasia were observed in males and females. Additional kidney sections from male and female control and exposed rats were examined to provide a clearer indication of the potential effects of chloroprene on the kidney. The combined single- and step-section incidences of renal tubule hyperplasia in 32 and 80 ppm males and 80 ppm females and the incidences of adenoma and adenoma or carcinoma (combined) in all exposed males were significantly greater than those in the chamber controls. A slight increase in the incidence of transitional epithelium carcinoma of the urinary bladder was observed in 80 ppm females. In addition, one 32 ppm male had a transitional epithelium carcinoma and one 80 ppm male had a transitional cell papilloma. These findings are noteworthy because no urinary bladder neoplasms have been observed in chamber control male or female F344/N rats. In the nose, the incidences of atrophy, basal cell hyperplasia, metaplasia, and necrosis of the olfactory epithelium in 32 and 80 ppm males and females and of atrophy and necrosis in 12.8 ppm males were significantly greater than those in the chamber control groups. The incidences of chronic inflammation were significantly increased in males exposed to 12.8 or 32 ppm and in males and females exposed to 80 ppm. The incidences of fibrosis and adenomatous hyperplasia in 80 ppm males and females were significantly greater than those in the chamber controls. Generally, lesions in the nasal cavity were mild to moderate in severity. 2-Year Study in Mice: Groups of 50 male and 50 female B6C3F1 mice were exposed to chloroprene at concentrations of 0, 12.8, 32, or 80 ppm by inhalation, 6 hours per day, 5 days per week, for 2 years. Survival, Body Weights, and Clinical Findings: Survival of males exposed to 32 or 80 ppm and of all exposed female groups was significantly less than that of the chamber controls. The mean body weights of 80 ppm females were significantly less than those of the chamber control group after week 75. Clinical findings included masses of the head, which correlated with harderian gland adenoma and/or carcinoma in 32 ppm males and 80 ppm males and fe-males. Dorsal and lateral torso masses of female mice correlated with mammary gland neoplasms in 32 and 80 ppm females and subcutaneous sarcomas in 12.8, 32, and 80 ppm females. Pathology Findings: The incidences of alveolar/bronchiolar neoplasms in the lungs of all groups of exposed males and females were significantly greater than those in the chamber control groups and generally exceeded the historical control ranges. The incidences of multiple alveolar/bronchiolar adenoma and alveolar/bronchiolar carcinoma were increased in all exposed groups of males and females. The incidences of bronchiolar hyperplasia in all exposed groups of males and females were significantly greater than those in the chamber control groups. Male mice had a pattern of nonneoplastic liver lesions along with silver-staining helical organisms within the liver consistent with infection with Helicobacter hepaticus. An organism compatible with H. hepaticus was confirmed with a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)-based assay. In NTP studies with H. hepaticus-associated hepatitis, increased incidences of hemangiosarcoma have been seen in the livers of male mice. Therefore, hemangiosarcomas of the liver were excluded from the analyses of circulatory (endothelial) neoplasms in males in this study. Even with this exclusion, the combined occurrence of hemangioma or hemangiosarcoma at other sites was significantly increased at all chloroprene exposure concentrations in males and in 32 ppm females. Incidences of neoplasms at other sites in this study of chloroprene were not considered to have been significantly impacted by the infection with H. hepaticus or its associated hepatitis. The incidences of harderian gland adenoma and harderian gland adenoma or carcinoma (combined) in males exposed to 32 or 80 ppm and females exposed to 80 ppm were significantly greater than those in the chamber controls. The incidences of harderian gland adenoma or carcinoma (combined) in 32 ppm males and 80 ppm males and females exceeded the historical control ranges. The incidences of mammary gland carcinoma and adenoacanthoma or carcinoma (combined) in 80 ppm females were significantly greater than those in the chamber control group. The incidences of mammary gland carcinoma and of adenoacanthoma in 32 and 80 ppm females exceeded the historical control ranges. Multiple mammary gland carcinomas occurred in exposed females. The incidences of hepatocellular carcinoma in all exposed female groups and hepatocellular adenoma or carcinoma (combined) in 32 and 80 ppm females were significantly greater than those in the chamber controls; in the 80 ppm group, the incidence exceeded the historical control ranges for carcinoma and adenoma or carcinoma (combined). The incidence of eosinophilic foci in 80 ppm females was also significantly greater than that in the chamber controls. The incidences of sarcoma of the skin were significantly greater in all exposed groups of females than in the chamber controls. The incidences of sarcoma of the mesentery were also increased in all exposed groups of females. The incidence of squamous cell papilloma in 80 ppm females was greater than that in the chamber controls; the difference was not significant, but the incidence exceeded the historical control range. Males also showed a positive trend in the incidence of squamous cell papilloma of the forestomach. In males and females exposed to 80 ppm, the incidences of hyperplasia of the forestomach epithelium were significantly greater than those in the chamber controls. Carcinomas of the Zymbal's gland were seen in three 80 ppm females, and two carcinomas metastasized to the lung. Zymbal's gland carcinomas have not been reported in control female mice in the NTP historical database. The incidence of renal tubule adenoma in 80 ppm males was greater than that in the chamber controls. Though this difference was not significant, the incidence of this rare neoplasm exceeded the historical control range. The incidences of renal tubule hyperplasia in males exposed to 32 or 80 ppm were significantly greater than that in the chamber controls. Additional sections of kidney were examined from control and exposed males to verify these findings. The combined single- and step-section incidence of renal tubule adenoma in 80 ppm males and the combined incidences of renal tubule hyperplasia in all groups of exposed male mice were greater than those in the chamber controls. The incidences of olfactory epithelial atrophy, adenomatous hyperplasia, and metaplasia in 80 ppm males and females were significantly greater than those in the chamber controls. The incidences of hematopoietic proliferation of the spleen in 32 and 80 ppm males and in all groups of exposed females were significantly greater than those in the chamber controls. Genetic Toxicology: Chloroprene was not mutagenic in any of the tests performed by the NTP. No induction of mutations was noted in any of four strains of S. typhimurium in the presence or the absence of S9 metabolic activation enzymes, and no induction of sex-linked recessive lethal mutations was observed in germ cells of male D. melanogaster treated with chloroprene via feeding or injection. In male mice exposed to chloroprene by inhalation for 12 days over a 16-day period, no induction of chromosomal aberrations, sister chromatid exchanges, or micronucleated erythrocytes in bone marrow or peripheral blood occurred. Results of a second micronucleus assay in male and female mice after 13 weeks of exposure to chloroprene via inhalation were also negative. Conclusion: Under the conditions of these 2-year inhalation studies, there was clear evidence of carcinogenic activity of chloroprene in male F344/N rats based on increased incidences of neoplasms of the oral cavity; increased incidences of neoplasms of the thyroid gland, lung, and kidney were also attributed to chloroprene exposure. There was clear evidence of carcinogenic activity of chloroprene in female F344/N rats based on increased incidences of neoplasms of the oral cavity; increased incidences of neoplasms of the thyroid gland, mammary gland, and kidney were also attributed to exposure to chloroprene. Low incidences of urinary bladder neoplasms in male and female rats and lung neoplasms in female rats may also have been related to exposure to chloroprene. There was clear evidence of carcinogenic activity of chloroprene in male B6C3F1 mice based on increased incidences of neoplasms of the lung, circulatory system (hemangiomas and hemangiosarcomas), and harderian gland; increased incidences of neoplasms of the forestomach and kidney were also attributed to exposure to chloroprene. There was clear evidence of carcinogenic activity of chloroprene in female B6C3F1 mice based on increased incidences of neoplasms of the lung, circulatory system (hemangiomas and hemangiosarcomas), harderian gland, mammary gland, liver, skin, and mesentery; increased incidences of neoplasms of the forestomach and Zymbal's gland were also attributed to exposure to chloroprene. Exposure of male and female rats to chloroprene was associated with increased incidences of alveolar epithelial hyperplasia in the lung; nephropathy; and several nonneoplastic effects in the nose including olfactory epithelial atrophy, fibrosis, adenomatous hyperplasia, basal cell hyperplasia, chronic inflammation, respiratory metaplasia, and necrosis. Exposure of male and female mice to chloroprene was associated with increased incidences of bronchiolar hyperplasia and histiocytic cell infiltration in the lung; epithelial hyperplasia in the forestomach; renal tubule hyperplasia (males only); several effects in the nose including olfactory epithelial atrophy, respiratory metaplasia, and adenomatous hyperplasia; and hematopoietic cell proliferation in the spleen. Synonyms: Chlorobutadiene, 2-chlorobuta-1,3-diene, 2-chloro-1,3-butadiene, -chloroprene

Effect of ammonia on Swiss albino mice

NASA Technical Reports Server (NTRS)

Hilado, C. J.; Casey, C. J.; Furst, A.

1977-01-01

Times to incapacitation and death and LC /50/ values were determined for Swiss albino male mice exposed to different concentrations of ammonia in a 4.2 liter hemispherical chamber. The LC/50/ for a 30 minute exposure was 21,430 ppm.

Time Perception and the Experience of Time When Immersed in an Altered Sensory Environment.

PubMed

Glicksohn, Joseph; Berkovich-Ohana, Aviva; Mauro, Federica; Ben-Soussan, Tal D

2017-01-01

The notion that exposure to a monotonous sensory environment could elicit reports indicating aberrant subjective experience and altered time perception is the impetus for the present report. Research has looked at the influence of exposure to such environments on time perception, reporting that the greater the environmental variation, the shorter is the time estimation obtained by the method of production. Most conditions for creating an altered sensory environment, however, have not facilitated an immersive experience, one that directly impacts both time perception and subjective experience. In this study, we invited our participants to enter a whole-body altered sensory environment for a 20-min session, wherein they were asked to relax without falling asleep. The session included white-colored illumination of the chamber with eyes closed (5 min), followed by 10 min of illuminating the room with color, after which a short report of subjective experience was collected using a brief questionnaire; this was followed by an additional 5 min of immersion in white light with closed eyes. The participants were then interviewed regarding their subjective experience, including their experience of time within the chamber. Prior to entering the chamber, the participants completed a time-production (TP) task. One group of participants then repeated the task within the chamber, at the end of the session; a second group of participants repeated the task after exiting the chamber. We shall report on changes in TP, and present data indicating that when produced time is plotted as a function of target duration, using a log-log plot, the major influence of sensory environment is on the intercept of the psychophysical function. We shall further present data indicating that for those participants reporting a marked change in time experience, such as "the sensation of time disappeared," their TP data could not be linearized using a log-log plot, hence indicating that for these individuals there might be a "break" in the psychophysical function.

DNA strand breakage and lipid peroxidation after exposure to welding fumes in vivo.

PubMed

Chuang, Cheng-Hung; Huang, Chong-En; Chen, Hsiu-Ling

2010-01-01

A remarkable number of complex aerosols are generated from welding processes. The objective of this study was to compare DNA damage and lipid peroxidation in plasma and in lung and in liver tissue of rats exposed to welding fumes in an exposure chamber with those of control animals. Three air samples from the chamber were also collected to assess the exposure dose for each exposure (total samplings = 18). Eight male Sprague-Dawley rats were exposed to welding fumes at a concentration of 1540.76 mg/m(3) for 10 min/day six times on day 1, day 3, day 7, day 15, day 30 and day 40. Lung, liver and kidney injury was measured following exposure, as well as in unexposed control rats (n = 4 at the beginning of the study). DNA strand breakage [tail moment (TMOM)] in exposed animals showed significant differences at day 1, day 4, day 7 and day 15 relative to the levels in control animals. Malondialdehyde (MDA, a lipid peroxidation product) levels increased gradually post-welding to 0.4 microM at 7 days. MDA and TMOM both reached maximum levels 7 days after the first exposure. At the start, an increasing trend in DNA strand breakage was more obvious than increases in MDA levels; MDA seemed to reflect long-term effects of exposure to welding fumes since it increased after 7 days and was sustained to 40 days in vivo. Significant differences in both MDA levels and DNA strand breakage were seen in lung, liver and kidney 40 days after the first fume inhalation. We conclude that acute exposure of rats to welding fumes causes noticeable oxidative damage and lipid peroxidation effects and that DNA damage may recover after long and repeat exposure. More chronic inhalation and low-dose studies are needed in order to further assess the effects of inhalation of welding fumes on DNA and to elucidate the possible causal mechanisms associated with the biologically damaging effects of welding fumes.

Atmospheric scavenging exhaust

NASA Technical Reports Server (NTRS)

Fenton, D. L.; Purcell, R. Y.

1977-01-01

Solid propellant rocket exhaust was directly utilized to ascertain raindrop scavenging rates for hydrogen chloride. The airborne HCl concentration varied from 0.2 to 10.0 ppm and the raindrop sizes tested included 0.55 mm, 1.1 mm, and 3.0 mm. Two chambers were used to conduct the experiments. A large, rigid walled, spherical chamber stored the exhaust constituents while the smaller chamber housing all the experiments was charged as required with rocket exhaust HCl. Surface uptake experiments demonstrated an HCl concentration dependence for distilled water. Sea water and brackish water HCl uptake was below the detection limit of the chlorine-ion analysis technique employed. Plant life HCl uptake experiments were limited to corn and soybeans. Plant age effectively correlated the HCl uptake data. Metallic corrosion was not significant for single 20 minute exposures to the exhaust HCl under varying relative humidity.

Atmospheric scavenging of solid rocket exhaust effluents

NASA Technical Reports Server (NTRS)

Fenton, D. L.; Purcell, R. Y.

1978-01-01

Solid propellant rocket exhaust was directly utilized to ascertain raindrop scavenging rates for hydrogen chloride. Two chambers were used to conduct the experiments; a large, rigid walled, spherical chamber stored the exhaust constituents, while the smaller chamber housing all the experiments was charged as required with rocket exhaust HCl. Surface uptake experiments demonstrated an HCl concentration dependence for distilled water. Sea water and brackish water HCl uptake was below the detection limit of the chlorine-ion analysis technique used. Plant life HCl uptake experiments were limited to corn and soybeans. Plant age effectively correlated the HCl uptake data. Metallic corrosion was not significant for single 20 minute exposures to the exhaust HCl under varying relative humidity. Characterization of the aluminum oxide particles substantiated the similarity between the constituents of the small scale rocket and the full size vehicles.

In vitro imaging of remaining dentin and pulp chamber by optical coherence tomography: comparison between 850 and 1280 nm

NASA Astrophysics Data System (ADS)

Fonsêca, Déborah D. D.; Kyotoku, Bernardo B. C.; Maia, Ana M. A.; Gomes, Anderson S. L.

2009-03-01

We report the application of optical coherence tomography (OCT) to generate images of the remaining dentin and pulp chamber of in vitro human teeth. Bidimensional images of remaining dentin and of the pulp chamber were obtained parallel to the long axis of the teeth, by two OCT systems operating around 1280 and 850 nm, and compared to tomography images using the i-CAT® Cone Beam Volumetric Tomography system as the gold standard. The results demonstrated the efficacy of the OCT technique; furthermore, the wavelength close to 1280 nm presented greater penetration depth in the dentine than 850 nm, as expected from scattering and absorption coefficients. The OCT technique has great potential to be used on clinical practice, preventing accidental exposure of the pulp and promoting preventive restoration treatment.

Disinfection effect of non-thermal atmospheric pressure plasma for foodborne bacteria

NASA Astrophysics Data System (ADS)

Pervez, Mohammad Rasel; Inomata, Takanori; Ishijima, Tatsuo; Kakikawa, Makiko; Uesugi, Yoshihiko; Tanaka, Yasunori; Yano, Toshihiro; Miwa, Shoji; Noguchi, Akinori

2015-09-01

Non-thermal atmospheric pressure plasma (NAPP) exposure can be a suitable alternative for bacteria inactivation in food processing industry. Specimen placed in the enclosure are exposed to various reactive radicals produced within the discharge chamber. It is also exposed to the periodic variation of the electric field strength in the chamber. Dielectric barrier discharge is produced by high voltage pulse (Vpp = 18 kV, pulse width 20 μs, repetition frequency 10 kHz) in a polypropylene box (volume = 350 cm3) using helium as main feed gas. Inactivation efficiency of NAPP depends on the duration of NAPP exposure, applied voltage pulse strength and type, pulse duration, electrode separation and feed gas composition. In this study we have investigated inactivation of Bacillus lichenformis spore as an example of food borne bacteria. Keeping applied voltage, electrode configuration and total gas flow rate constant, spores are exposed to direct NAPP for different time duration while O2 concentration in the feed gas composition is varied. 10 minutes NAPP exposure resulted in ~ 3 log reduction of Bacillus lichenformis spores for 1% O2concentration (initial concentration ~ 106 / specimen). This work is supported by research and development promotion grant provided by the Hokuriku Industrial Advancement Center.

Relative abundances of elements (20 or = Z or = 28) at energies up to 70 GeV/amu using relativistic rise in ion chambers

NASA Technical Reports Server (NTRS)

Barthelmy, S. D.; Israel, M. H.; Klarmann, J.

1985-01-01

The results of a new balloon borne cosmic ray detector flown from Palestine, TX in Sept., 1982 are discussed. The exposure of 62 square meter-ster-hr is sufficient to prove the concept of using gas ionization chambers as energy measuring devices in the relativistic rise region. The abundances, relative Fe-26, of the pure secondaries Cr-22 and Ti-24, the pure primary Ni26, and the mixed primary and secondary Ca-20 between 6 and 70GeV/amu were measured.

Experimental setup for radon exposure and first diffusion studies using gamma spectroscopy

NASA Astrophysics Data System (ADS)

Maier, Andreas; van Beek, Patrick; Hellmund, Johannes; Durante, Marco; Schardt, Dieter; Kraft, Gerhard; Fournier, Claudia

2015-11-01

In order to measure the uptake and diffusion of 222Rn in biological material, an exposure chamber was constructed where cell cultures, biological tissues and mice can be exposed to 222Rn-activities similar to therapy conditions. After exposure, the material is transferred to a gamma spectrometer and the decay of 214Pb and 214Bi is analyzed. From the time kinetics of these decays the total amount of the initial 222Rn concentration can be calculated. In this paper the design and construction as well as first test measurements are reported.

Sporicidal effects of iodine-oxide thermite reaction products

NASA Astrophysics Data System (ADS)

Russell, Rod; Bless, Stephan; Blinkova, Alexandra; Chen, Tiffany

2012-03-01

Iodine pentoxide-aluminum thermite reactions have been driven by impacts at 1000 m/s on steel plates 3 mm or thicker. This reaction releases iodine gas that is known to be a sporicide. To test the impact reactions for sporicidal effects, reactions took place in closed chambers containing dried Bacillus subtilis spores. The reduction in colony-forming units was dependent on the exposure time; long exposure times resulted in a 105 decrease in germination rate. This was shown to be due to the gas exposure rather than the heat or turbulence. Sporicidal effectiveness was increased by adding neodymium and saran resin.

Novel approach to study the cardiovascular effects and mechanism of action of urban particulate matter using lung epithelial-endothelial tetra-culture system.

PubMed

Kim, Ha Ryong; Cho, Han Soo; Shin, Da Young; Chung, Kyu Hyuck

2017-02-01

In vitro models have become increasingly sophisticated, and their usefulness in supporting toxicity testing is well established. The present study was designed to establish a novel in vitro model that mimics the cellular network surrounding airways and pulmonary blood vessels, to study the cardiovascular toxic effects of particulate matter (PM). Transwell culture method was used to develop a novel tetra-culture system consisting of tri-cultures (one lung epithelial and two immune cell lines) in the apical chamber and endothelial cells in the basolateral chamber. Tri-cultures were exposed to standard reference material (SRM) 1648a, an urban PM. SRM 1648a did not show cytotoxic effects; however, it increased IL-6 level in apical and basolateral chambers. The cells in the basolateral chamber showed increased monocyte adhesion. Furthermore, exposure of tri-cultured cells to SRM 1648a in the apical chamber induced ICAM-1 expression in endothelial cells in the basolateral chamber by activating the IL-6/STAT3 pathway. In conclusion, a tetra-culture system was established to facilitate the identification of cellular adhesion molecule expression induced by the interaction between pulmonary epithelial and endothelial cells. The tetra-culture system will contribute to elucidation of the relationships between inhalable PM and cardiovascular diseases. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oxygen-reducing biocathodes operating with passive oxygen transfer in microbial fuel cells.

PubMed

Xia, Xue; Tokash, Justin C; Zhang, Fang; Liang, Peng; Huang, Xia; Logan, Bruce E

2013-02-19

Oxygen-reducing biocathodes previously developed for microbial fuel cells (MFCs) have required energy-intensive aeration of the catholyte. To avoid the need for aeration, the ability of biocathodes to function with passive oxygen transfer was examined here using air cathode MFCs. Two-chamber, air cathode MFCs with biocathodes produced a maximum power density of 554 ± 0 mW/m(2), which was comparable to that obtained with a Pt cathode (576 ± 16 mW/m(2)), and 38 times higher than that produced without a catalyst (14 ± 3 mW/m(2)). The maximum current density with biocathodes in this air-cathode MFC was 1.0 A/m(2), compared to 0.49 A/m(2) originally produced in a two-chamber MFC with an aqueous cathode (with cathode chamber aeration). Single-chamber, air-cathode MFCs with the same biocathodes initially produced higher voltages than those with Pt cathodes, but after several cycles the catalytic activity of the biocathodes was lost. This change in cathode performance resulted from direct exposure of the cathodes to solutions containing high concentrations of organic matter in the single-chamber configuration. Biocathode performance was not impaired in two-chamber designs where the cathode was kept separated from the anode solution. These results demonstrate that direct-air biocathodes can work very well, but only under conditions that minimize heterotrophic growth of microorganisms on the cathodes.

Ultra-accelerated natural sunlight exposure testing

DOEpatents

Jorgensen, Gary J.; Bingham, Carl; Goggin, Rita; Lewandowski, Allan A.; Netter, Judy C.

2000-06-13

Process and apparatus for providing ultra accelerated natural sunlight exposure testing of samples under controlled weathering without introducing unrealistic failure mechanisms in exposed materials and without breaking reciprocity relationships between flux exposure levels and cumulative dose that includes multiple concurrent levels of temperature and relative humidity at high levels of natural sunlight comprising: a) concentrating solar flux uniformly; b) directing the controlled uniform sunlight onto sample materials in a chamber enclosing multiple concurrent levels of temperature and relative humidity to allow the sample materials to be subjected to accelerated irradiance exposure factors for a sufficient period of time in days to provide a corresponding time of about at least a years worth of representative weathering of the sample materials.

Ultra-accelerated natural sunlight exposure testing facilities

DOEpatents

Lewandowski, Allan A.; Jorgensen, Gary J.

2003-08-12

A multi-faceted concentrator apparatus for providing ultra-accelerated natural sunlight exposure testing for sample materials under controlled weathering conditions comprising: facets that receive incident natural sunlight, transmits VIS/NIR and reflects UV/VIS to deliver a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in chamber means that provide concurrent levels of temperature and/or relative humidity at high levels of up to 100.times. of natural sunlight that allow sample materials to be subjected to accelerated irradiance exposure factors for a significant period of time of about 3 to 10 days to provide a corresponding time of about at least a years worth representative weathering of sample materials.

Evaluation of the Combined Effects of Heat and Lighting on the Level of Attention and Reaction Time: Climate Chamber Experiments in Iran.

PubMed

Mohebian, Zohreh; Farhang Dehghan, Somayeh; Dehghan, Habiballah

2018-01-01

Heat exposure and unsuitable lighting are two physical hazardous agents in many workplaces for which there are some evidences regarding their mental effects. The purpose of this study was to assess the combined effect of heat exposure and different lighting levels on the attention rate and reaction time in a climatic chamber. This study was conducted on 33 healthy students (17 M/16 F) with a mean (±SD) age of 22.1 ± 2.3 years. The attention and reaction time test were done by continuous performance test and the RT meter, respectively, in different exposure conditions including the dry temperatures (22°C and 37°C) and lighting levels (200, 500, and 1500 lux). Findings demonstrated that increase in heat and lighting level caused a decrease in average attention percentage and correct responses and increase in commission error, omission error, and response time ( P < 0.05). The average of simple, diagnostic, two-color selective, and two-sound selective reaction times increased after combined exposure to heat and lighting ( P < 0.05). The results of this study indicated that, in job task which requires using cognitive functions like attention, vigilance, concentration, cautiousness, and reaction time, the work environment must be optimized in terms of heat and lighting level.

Development of a Small Chamber Method to Study SVOCs Sink Effect

EPA Science Inventory

The transport mechanisms of semivolatile organic compounds (SVOCs) between sources, air,house dust, and interior surfaces in the residential environment needs to be better understood in order to more accurately estimate indoor SVOC exposure and develop risk management strategies ...

Latent Presentation of Decompression Sickness After Altitude Chamber Training in an Active Duty Flier.

PubMed

Gentry, James; Rango, Juan; Zhang, Jianzhong; Biedermann, Shane

2017-04-01

Decompression sickness (DCS) is a potential danger and risk for both divers and aircrew alike. DCS is also a potential side effect of altitude (hypobaric) chamber training as well and can present long after training occurs. Literature review shows that altitude chamber induced DCS has approximately a 0.25% incidence. A 32-yr-old, active duty military member developed symptoms of DCS 3 h after his hypobaric chamber training. Unfortunately, he did not seek treatment for DCS until 48 h after the exposure. His initial treatment included ground level oxygen therapy for 30 min at 12 L of oxygen per minute using a nonrebreathing mask. He achieved complete symptom resolution and was returned to duty. However, 12 d after his initial Flight Medicine evaluation, the patient returned complaining of a right temporal headache, multijoint pains, and fatigue. He was treated in the hyperbaric chamber and had complete resolution of symptoms. He was returned to flying status and 5 mo later denied any return of symptoms. Hypobaric chamber familiarity training is a requirement for all military aircrew personnel to allow them assess their ability to identify symptoms of hypoxia. This training method is not only costly to maintain, but it also places aircrew and chamber technicians at risk for potential long-term side effects from failed recompression treatment of DCS. We are presenting a case of recurrent DCS symptoms 12 d after initial ground level oxygen therapy.Gentry J, Rango J, Zhang J, Biedermann S. Latent presentation of decompression sickness after altitude chamber training in an active duty flier. Aerosp Med Hum Perform. 2017; 88(4):427-430.

Design of an environmentally controlled rotating chamber for bioaerosol aging studies

PubMed Central

Verreault, Daniel; Duchaine, Caroline; Marcoux-Voiselle, Melissa; Turgeon, Nathalie; Roy, Chad J.

2015-01-01

A chamber was designed and built to study the long-term effects of environmental conditions on air-borne microorganisms. The system consists of a 55.5-L cylindrical chamber, which can rotate at variable speeds on its axis. The chamber is placed within an insulated temperature controlled enclosure which can be either cooled or heated with piezoelectric units. A germicidal light located at the chamber center irradiates at a 360° angle. Access ports are located on the stationary sections on both ends of the chamber. Relative humidity (RH) is controlled by passing the aerosol through meshed tubes surrounded by desiccant. Validation assay indicates that the interior temperature is stable with less than 0.5 °C in variation when set between 18 and 30 °C with the UV light having no effect of temperature during operation. RH levels set at 20%, 50% and 80% varied by 2.2%, 3.3% and 3.3%, respectively, over a 14-h period. The remaining fraction of particles after 18 h of suspension was 8.8% at 1 rotation per minute (rpm) and 2.6% at 0 rpm with the mass median aerodynamic diameter (MMAD) changing from 1.21 ± 0.04 μm to 1.30 ± 0.02 μm at 1 rpm and from 1.21 ± 0.04 μm to 0.91 ± 0.01 μm at 0 rpm within the same time period. This chamber can be used to increase the time of particle suspension in an aerosol cloud and control the temperature, RH and UV exposure; the design facilitates stationary sampling to be performed while the chamber is rotating. PMID:25055842

Characterization and testing of a new environmental chamber

NASA Astrophysics Data System (ADS)

Leskinen, A.; Yli-Pirilä, P.; Kuuspalo, K.; Sippula, O.; Jalava, P.; Hirvonen, M.-R.; Jokiniemi, J.; Virtanen, A.; Komppula, M.; Lehtinen, K. E. J.

2015-06-01

A 29 m3 Teflon chamber, designed for studies on the aging of combustion aerosols, at the University of Eastern Finland is described and characterized. The chamber is part of a research facility, called Ilmari, where small-scale combustion devices, a dynamometer for vehicle exhaust studies, dilution systems, the chamber, and cell and animal exposure devices are located side by side under the same roof. The small surface-to-volume ratio of the chamber enables reasonably long experiment times, with particle wall loss rate constants of 0.088, 0.080, 0.045, and 0.040 h-1 for polydisperse, 50, 100, and 200 nm monodisperse aerosols, respectively. The NO2 photolysis rate can be adjusted from 0 to 0.62 min-1. The irradiance spectrum is centered at either 350 or 365 nm, and the maximum irradiance, produced by up to 160 blacklight lamps, is 29.7 W m-2, which corresponds to the ultraviolet (UV) irradiance in Central Finland at noon on a sunny day in the midsummer. The temperature inside the chamber is uniform and can be kept at 25±1 °C. The chamber is kept in an overpressure with a moving top frame, which reduces sample dilution and entrance of contamination during an experiment. The functionality of the chamber was tested with oxidation experiments of toluene, resulting in secondary organic aerosol (SOA) yields of 12-42%, depending on the initial conditions, such as NOx concentration and UV irradiation. The highest gaseous oxidation product yields of 12.4-19.5% and 5.8-19.5% were detected with ions corresponding to methyl glyoxal (m/z 73.029) and 4-oxo-2-pentenal (m/z 99.044), respectively. Overall, reasonable yields of SOA and gaseous reaction products, comparable to those obtained in other laboratories, were obtained.

Toxicology and Carcinogenesis Studies of Furfuryl Alcohol (CAS No. 98-00-0) in F344/N Rats and B6C3F1 Mice (Inhalation Studies).

PubMed

1999-02-01

Furfuryl alcohol-based resins are used as binding agents in foundry sand and as corrosion inhibitors in mortar, grout, and cement. Because of their heat resistance, furan resins are used in the manufacture of fiberglass-reinforced plastic equipment. Furfuryl alcohol was selected for evaluation because of the absence of data on its carcinogenic potential and its large production volume, widespread use in manufacturing, and ubiquitous presence in consumer goods. Male and female F344/N rats and B6C3F1 mice were exposed to furfuryl alcohol (greater than 98% pure) by inhalation for 16 days, 14 weeks, or 2 years. Genetic toxicology studies were conducted in Salmonella typhimurium, cultured Chinese hamster ovary cells, and mouse bone marrow cells. 16-DAY STUDY IN RATS: Groups of five male and five female rats were exposed to concentrations of 0, 16, 31, 63, 125, or 250 ppm furfuryl alcohol by inhalation, 6 hours per day, 5 days per week for 16 days. All male and female rats exposed to 250 ppm died by day 2 of the study, and one male rat exposed to 125 ppm died on day 5. Final mean body weights of male and female rats exposed to 125 ppm were significantly less than those of the chamber control groups. Male rats exposed to 31, 63, or 125 ppm and female rats exposed to 125 ppm gained less weight than the chamber control groups. Clinical findings included dyspnea, hypoactivity, and nasal and ocular discharge in males and females exposed to 63, 125, or 250 ppm. All exposed animals developed lesions in the nasal respiratory epithelium and olfactory epithelium, and the severities of these lesions generally increased with increasing exposure concentration. 16-DAY STUDY IN MICE: Groups of five male and five female mice were exposed to concentrations of 0, 16, 31, 63, 125, or 250 ppm furfuryl alcohol by inhalation, 6 hours per day, 5 days per week for 16 days. All male and female mice exposed to 250 ppm died by day 4 of the study, and one female mouse exposed to 125 ppm died on day 14. Mean body weights of male and female mice exposed to 63 or 125 ppm were significantly less than those of the chamber control groups. All exposed animals except one 16 ppm male developed lesions in the nasal respiratory epithelium and/or olfactory epithelium, and the severities of these lesions generally increased with increasing exposure concentration. 14-WEEK STUDY IN RATS: Groups of 10 male and 10 female rats were exposed to furfuryl alcohol at concentrations of 0, 2, 4, 8, 16, or 32 ppm, 6 hours per day, 5 days per week for 14 weeks. All rats survived to the end of the study. The mean body weight gain of females exposed to 32 ppm was less than that of the chamber control group. Exposure-related increases in the incidences of squamous metaplasia of the respiratory and transitional epithelium, goblet cell hyperplasia of the respiratory epithelium, and hypertrophy of the respiratory epithelium lining the nasopharyngeal duct were observed in the nose of male and female rats. The incidences of degeneration, hyperplasia, metaplasia, and surface exudate of the olfactory epithelium generally increased with increasing exposure concentration in males and females. 14-WEEK STUDY IN MICE: Groups of 10 male and 10 female mice were exposed to furfuryl alcohol at concentrations of 0, 2, 4, 8, 16, or 32 ppm, 6 hours per day, 5 days per week for 14 weeks. All mice survived to the end of the study. Heart weights of 32 ppm males were significantly less than those of the chamber controls. Exposure-related histologic changes included degeneration, metaplasia, and chronic inflammation of the olfactory epithelium; hyaline droplets of the respiratory epithelium; and squamous metaplasia of the submucosal gland of the cuboidal epithelium in males and females. 2-YEAR STUDY IN RATS: Groups of 50 male and 50 female rats were exposed to furfuryl alcohol by inhalation, 6 hours per day, 5 days per week for 105 weeks, at concentrations of 0, 2, 8, or 32 ppm. Survival and Body Weights All male rats exposed to 32 ppm died by week 99; survival of all other exposed groups of male and femald female rats was similar to that of the chamber control groups. Mean body weights of 32 ppm males were less than those of the chamber control group beginning at week 19. Pathology Findings All groups of exposed male and female rats had significantly increased incidences of nonneoplastic histologic changes of the nose compared to the chamber control groups. An adenoma of the lateral wall of the nose was observed in one 2 ppm male and one 8 ppm female, an adenoma of the respiratory epithelium was observed in one 8 ppm male and one 32 ppm female, one carcinoma of the respiratory epithelium was observed in a 32 ppm male, and squamous cell carcinomas of the nose were observed in three 32 ppm males. Renal tubule adenomas were present in one chamber control male, one 2 ppm male, two 8 ppm males, and two 32 ppm females. One 2 ppm female had a renal tubule carcinoma. Additional histologic sections from the kidney revealed the presence of additional hyperplasias in all groups of males and females; one additional renal tubule adenoma was observed in each of the chamber control, 2 ppm, and 8 ppm male groups, and four additional adenomas were observed in 32 ppm males. In females, two additional adenomas were found in the 8 ppm group, one adenoma in the 32 ppm group, and one carcinoma in the 2 ppm group. The severities of nephropathy relative to the chamber controls were increased in 32 ppm males and females. Males exposed to 32 ppm had extrarenal signs indicative of marked nephropathy including parathyroid gland hyperplasia and fibrous osteodystrophy. 2-YEAR STUDY IN MICE: Groups of 50 male and 50 female mice were exposed to furfuryl alcohol by inhalation, 6 hours per day, 5 days per week for 105 weeks, at concentrations of 0, 2, 8, or 32 ppm. Survival, Body Weights, and Clinical Findings Survival of exposed males and females was similar to that of the chamber control groups. Mean body weights of exposed males were generally similar to those of the chamber control group throughout the study. Mean body weights of exposed females were less than those of the chamber control group during year 2 of the study. Female mice exposed to 32 ppm developed focal corneal opacities. Pathology Findings The incidences of renal tubule neoplasms were increased in 32 ppm male mice compared to the chamber control group and exceeded the historical control range for inhalation studies. Step sectioning revealed the presence of additional hyperplasias in the chamber control and exposed groups and one adenoma in 32 ppm males. The severity of nephropathy increased with increasing exposure concentration in male mice. The incidence of renal tubule degeneration in male mice exposed to 32 ppm was significantly greater than in the chamber control group. Incidences of a variety of nonneoplastic lesions of the nose were significantly greater in all exposed groups of male and female mice than in the chamber control groups. The incidence of degeneration of the cornea was significantly greater in 32 ppm female mice compared to the chamber control group. GENETIC TOXICOLOGY: Furfuryl alcohol was not mutagenic in Salmonella typhimurium strain TA98, TA100, TA1535, or TA1537, with or without S9. It did induce sister chromatid exchanges in cultured Chinese hamster ovary cells in the absence of S9, but not in the presence of S9. No induction of chromosomal aberrations was noted in cultured Chinese hamster ovary cells treated with furfuryl alcohol in the absence of S9, but in the presence of S9 an equivocal result was obtained. In vivo, no induction of sister chromatid exchanges, chromosomal aberrations, or micronuclei was noted in bone marrow cells of male mice after treatment with furfuryl alcohol. CONCLUSIONS: Under the conditions of these 2-year inhalation studies, there was some evidence of carcinogenic activity of furfuryl alcohol in male F344/N rats based on increased incidences of combined neoplasms of the nose. There was equivocal evidence of carcinogenic activity of furfuryl alcohol in female F344/N rats based on marginally increased incidences of neoplasms of the nose and renal tubule neoplasms. There was some evidence of carcinogenic activity of furfuryl alcohol in male B6C3F1 mice based on increased inci dences of renal tubule neoplasms. There was no evidence of carcinogenic activity of furfuryl alcohol in female B6C3F1 mice exposed to 2, 8, or 32 ppm. Exposure of male and female rats and male mice to furfuryl alcohol was associated with increased incidences of nonneoplastic lesions of the nose and increased severities of nephropathy. Exposure of female mice to furfuryl alcohol was associated with increased incidences of nonneoplastic lesions of the nose and corneal degeneration. Synonyms: 2-Furancarbinol; 2-furanmethanol, furfuralcohol, a-furylcarbinol; 2-hydroxymethylfuran

Histological Study of the Toxic Effects of Solder Fumes on Spermatogenesis in Rats

PubMed Central

Arab, Mohammad Reza; Heidari, Mohammad Hossein; Mashhadi, Rezvaneh; Mirzaei, Ramazan; Jahantigh, Mehdi

2011-01-01

Objective: Toxic fumes generated during the soldering process contain various contaminants released at sufficient rates to cause both short- and long-term health problems. Studies have shown that these fumes change the quality and quantity of semen fluid in exposed workers. The aim of the present study was to determine the potentially toxic effects of solder fumes on spermatogenesis in seminiferous tubules of rats as an experimental model, with conditioned media in an exposed chamber. Materials and Methods: A total number of 48 male Sprague Dawley adult rats were randomly divided into experimental (n=30) and control (n=18) groups. Based on exposure time, each group was further subdivided into two, four and six subgroups. Rats in the experimental groups were exposed to solder fumes in an exposure chamber for one hour/ day. The concentrations of fumes [formaldehyde, stanum (Sn) and lead (Pb)] were measured by a standard method via atomic absorption and spectrophotometry. According to a timetable, under deep anesthesia, the rats of both experimental and control subgroups were killed. After fixation of testes, specimens were weighed and routinely processed. Paraffin sections were stained by hematoxylin and eosin. Spermiogenesis index was calculated and data analyzed by Mann Whitney NPAR test. Results: Analysis of air samples in the exposure chamber showed the following fume concentrations: 0.193 mg/m3 for formaldehyde, 0.35 mg/m3 for Sn and 3 mg/m3 for Pb. Although there was no significant difference in testes weight between control and experimental subgroups, there was only a significant difference in spermiogenesis index between the six week experimental and control subgroups (p<0.02). Conclusion: The results of this study showed that solder fumes can change the spermiogenesis index in experimental groups in a time dependent manner. PMID:23671821

The effect of low- and high-power microwave irradiation on in vitro grown Sequoia plants and their recovery after cryostorage.

PubMed

Halmagyi, A; Surducan, E; Surducan, V

2017-09-01

Two distinct microwave power levels and techniques have been studied in two cases: low-power microwave (LPM) irradiation on in vitro Sequoia plants and high-power microwave (HPM) exposure on recovery rates of cryostored (-196°C) Sequoia shoot apices. Experimental variants for LPM exposure included: (a) in vitro plants grown in regular conditions (at 24 ± 1°C during a 16-h light photoperiod with a light intensity of 39.06 μEm -2 s -1 photosynthetically active radiation), (b) in vitro plants grown in the anechoic chamber with controlled environment without microwave irradiation, and (c) in vitro plants grown in the anechoic chamber with LPM irradiation for various times (5, 15, 30, 40 days). In comparison to control plants, significant differences in shoot multiplication and growth parameters (length of shoots and roots) were observed after 40 days of LPM exposure. An opposite effect was achieved regarding the content of total soluble proteins, which decreased with increasing exposure time to LPM. HPM irradiation was tested as a novel rewarming method following storage in liquid nitrogen. To our knowledge, this is the first report using this type of rewarming method. Although, shoot tips subjected to HPM exposure showed 28% recovery following cryostorage compared to 44% for shoot tips rewarmed in liquid medium at 22 ± 1 °C, we consider that the method represent a basis and can be further improved. The results lead to the overall conclusion that LPM had a stimulating effect on growth and multiplication of in vitro Sequoia plants, while the HPM used for rewarming of cryopreserved apices was not effective to achieve high rates of regrowth after liquid nitrogen exposure.

The effect of carbon dioxide flow rate on the euthanasia of laboratory mice.

PubMed

Moody, C M; Chua, B; Weary, D M

2014-10-01

Laboratory rodents are commonly euthanized by exposure to gradually increasing concentrations of carbon dioxide (CO2). Current recommended flow rates range between 10 and 30% chamber vol/min and result in insensibility before exposure to painful concentrations (<40%). However, this method causes dyspnea, indicated by deep, rapid breathing. In humans dyspnea is associated with a negative affective experience. Sensations of dyspnea may explain why rodents find CO2 concentrations >3% aversive. This study aimed to assess the effect of CO2 flow rates on time between the onset of dyspnea and various measures of insensibility (recumbency, loss of the righting reflex and loss of the pedal withdrawal reflex) to identify flow rates that minimize the potential experience of dyspnea. The results of this study indicate that a flow rate of 50% chamber vol/min, while holding the CO2 cage concentration just below 40%, minimizes the interval between the onset of labored breathing and recumbency. Using a 50% flow rate this interval averaged (± SE) 30.3 ± 2.9 s versus 49.7 ± 2.9 s at 20% chamber vol/min (F3,22 = 7.83, P = 0.0013). Similarly, the interval between the onset of labored breathing and loss of the righting reflex averaged 38.2 ± 2.4 s at a flow rate of 50% versus 59.2 ± 2.4 s at 20% chamber vol/min of CO2 (F3,22 = 13.62, P < 0.0001). We conclude that higher flow rates reduce the duration of dyspnea, but even at the highest flow rate mice experience more than 30 s between the onset of dyspnea and the most conservative estimate of insensibility. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Regional differences in sweat rate response of steers to short-term heat stress

NASA Astrophysics Data System (ADS)

Scharf, B.; Wax, L. E.; Aiken, G. E.; Spiers, D. E.

2008-11-01

Six Angus steers (319 ± 8.5 kg) were assigned to one of two groups (hot or cold exposure) of three steers each, and placed into two environmental chambers initially maintained at 16.5-18.8°C air temperature ( T a). Cold chamber T a was lowered to 8.4°C, while T a within the hot chamber was increased to 32.7°C over a 24-h time period. Measurements included respiration rate, and air and body (rectal and skin) temperatures. Skin temperature was measured at shoulder and rump locations, with determination of sweat rate using a calibrated moisture sensor. Rectal temperature did not change in cold or hot chambers. However, respiration rate nearly doubled in the heat ( P < 0.05), increasing when T a was above 24°C. Skin temperatures at the two locations were highly correlated ( P < 0.05) with each other and with T a. In contrast, sweat rate showed differences at rump and shoulder sites. Sweat rate of the rump exhibited only a small increase with T a. However, sweat rate at the shoulder increased more than four-fold with increasing T a. Increased sweat rate in this region is supported by an earlier report of a higher density of sweat glands in the shoulder compared to rump regions. Sweat rate was correlated with several thermal measurements to determine the best predictor. Fourth-order polynomial expressions of short-term rectal and skin temperature responses to hot and cold exposures produced r values of 0.60, 0.84, and 0.98, respectively. These results suggest that thermal inputs other than just rectal or skin temperature drive the sweat response in cattle.

Characterizing Microbe-Environment Interactions Through Experimental Evolution: The Autonomous Adaptive Directed Evolution Chamber

NASA Astrophysics Data System (ADS)

Ibanez, C. R.; Blaich, J.; Owyang, S.; Storrs, A.; Moffet, A.; Wong, N.; Zhou, J.; Gentry, D.

2015-12-01

We are developing a laboratory system for studying micro- to meso-scale interactions between microorganisms and their physicochemical environments. The Autonomous Adaptive Directed Evolution Chamber (AADEC) cultures microorganisms in controlled,small-scale geochemical environments. It observes corresponding microbial interactions to these environments and has the ability to adjust thermal, chemical, and other parameters in real time in response to these interactions. In addition to the sensed data, the system allows the generation of time-resolved ecological, genomic, etc. samples on the order of microbial generations. The AADEC currently houses cultures in liquid media and controls UVC radiation, heat exposure, and nutrient supply. In a proof-of-concept experimental evolution application, it can increase UVC radiation resistance of Escherichia coli cultures by iteratively exposing them to UVC and allowing the surviving cells to regrow. A baseline characterization generated a million fold resistance increase. This demonstration uses a single-well growth chamber prototype, but it was limited by scalability. We have expanded upon this system by implementing a microwell plate compatible fluidics system and sensor housing. This microwell plate system increases the diversity of microbial interactions seen in response to the geochemical environments generated by the system, allowing greater control over individual cultures' environments and detection of rarer events. The custom microfluidic card matches the footprint of a standard microwell plate. This card enables controllable fluid flow between wells and introduces multiple separate exposure and sensor chambers, increasing the variety of sensors compatible with the system. This gives the device control over scale and the interconnectedness of environments within the system. The increased controllability of the multiwell system provides a platform for implementing machine learning algorithms that will autonomously adjust geochemical environmental parameters.

Assessment of offspring development and behavior following gestational exposure to inhaled methanol in the rat.

PubMed

Stanton, M E; Crofton, K M; Gray, L E; Gordon, C J; Boyes, W K; Mole, M L; Peele, D B; Bushnell, P J

1995-11-01

The prospect of widespread human exposure associated with its use as an alternative fuel has sparked concern about the toxic potential of inhaled methanol (MeOH). Previous studies have revealed congenital malformations in rats following inhaled MeOH (Nelson et al. (1985). Fundam. Appl. Toxicol. 5, 727-736) but these studies did not include postnatal behavioral assessment. In the present study, pregnant Long-Evans rats were placed in exposure chambers containing 15,000 ppm MeOH or air for 7 hr/day on Gestational Days (GD) 7-19. The total alveolar dose of methanol was estimated at about 6.1 g/kg/day, for a total dose of about 42.7 g/kg for the entire study. Maternal body weights were recorded daily and blood methanol concentrations were determined at the end of exposure on GD 7, 10, 14, and 18. Following birth (Postnatal Day 0 [PND 0]), a number of tests were performed at various points in development, including: offspring mortality and body wt (PND 1,3), motor activity (PND 13-21, 30, 60), olfactory learning (PND 18), behavioral thermoregulation (PND 20-21), T-maze learning (PND 23-24), acoustic startle response (PND 24, 60), reflex modification audiometry (PND 60), pubertal landmarks (PND 31-56), passive avoidance (PND 72), and visual-evoked potentials (PND 160). Maternal blood MeOH levels, measured from samples taken within 15 min after removal from the exposure chamber, declined from about 3.8 mg/ml on the first day of exposure to 3.1 mg/ml on the 12th day of exposure. MeOH transiently reduced maternal body wt (4-7%) on GD 8-10, and offspring BW (5%) on PND 1. No other test revealed significant effects of MeOH. Prenatal exposure to high levels of inhaled MeOH appears to have little effect on this broad battery of tests beyond PND 1 in the rat.

Effects of Acute Exposures to Carbon Dioxide upon Cognitive Functions

NASA Technical Reports Server (NTRS)

Ryder, V. E.; Scully, R. R.; Alexander, D. J.; Lam, C. W.; Young, M.; Satish, U.; Basner, M.

2017-01-01

Carbon dioxide (CO2) originates from human metabolism and typically remains about 10-fold higher in concentration on the International Space Station (ISS) than at the earth's surface. There have been recurring complaints by crew members of episodes of "mental viscosity" adversely affecting their performance, and there is evidence from the ISS that associates CO2 levels with reports of headaches by crewmembers. Consequently, flight rules have been employed to control CO2 below 3 mm Hg, which is well below the existing Spacecraft Maximum Allowable Concentration (SMAC) of 10 mm Hg for 24-hour exposures, and 5.3 mm Hg for exposures of 7 to 180 days. Headaches, while sometime debilitating themselves, are also symptoms that can provide evidence that physiological defense mechanisms have been breached, and there is evidence that CO2 has effects at levels below the threshold for headaches. This concern appears to be substantiated in reports that CO2 at concentrations below 2 mm Hg substantially reduced some cognitive functions that are associated with the ability to make complex decisions in conditions that are characterized by volatility, uncertainty, complexity, ambiguity, and delayed feedback. These are conditions that could be encountered by crews in off-nominal situations or during the first missions beyond low earth orbit. Therefore, we set out to determine if decision-making under volatile, uncertain, confusing and ambiguous circumstances, where feedback is delayed or absent, is correlated with low levels of CO2 during acute exposures (several hours) in crew-like subjects and to determine if additional cognitive domains are sensitive to concentrations of CO2 at, or below, current ISS levels by using a test battery that is currently available onboard ISS. We enrolled 22 volunteers (8 females, 14 males) between the ages of 30-55 (38.8 +/- 7.0) years whose training and professional experience reflect that of the astronaut corps. Subjects were divided among 4 study groups. Exposures occurred in the 20-foot environmental chamber in Bldg 7 at JSC. Each group was exposed to each of four concentrations of CO2 (600, 1200, 2500, and 5000 ppm), and the exposure order was balanced across the groups which were randomly assigned to 4 possible complete exposure orders. Study participants and investigators were blinded to the exposure order. Each exposure lasted 4 hours and occurred on the same day each week for 4 consecutive weeks. Testing included the Strategic Management Simulation (SMS) methodology and the Cognition battery of psychometric measures that are being utilized aboard the ISS. Subjects participated in a familiarization session one week prior to the start of exposure sessions. Each exposure session followed the schedule noted in Figure 1 below. On the morning of each exposure, subjects completed the Cognition battery in a conference room at indoor ambient CO2 levels. Subjects then entered the exposure chamber and were acclimated to the environment for 15 minutes before completing another round of the Cognition battery. After a 20 minute rest, subject completed the approx.80 minute SMS. Subjects were allowed another 20 minute rest period before completing the final Cognition test battery in the exposure chamber. Subjects then returned to the conference room where they completed one final round of Cognition. Data from both testing methodologies are currently being analyzed and will be presented. Study investigators have not yet been unblinded to the coded exposure concentrations, but preliminary results suggest differences.

PERFORMANCE AUDITING OF A HUMAN AIR POLLUTION EXPOSURE CHAMBER FOR PM2.5

EPA Science Inventory

Databases derived from human health effects research play a vital role in setting environmental standards. An underlying assumption in using these databases for standard setting purposes is that they are of adequate quality. The performance auditing program described provides n...

Effects of Repeated Sublethal VX Exposure on Operant Time Estimation in Rats

DTIC Science & Technology

2007-08-01

1 week of food restriction, preliminary behavioral training ( autoshaping ) began. Apparatus Eight commercially available operant chambers for... Autoshaping was used to produce acquisition of lever pressing. Every 50 seconds (range = 10-90 s) on average, the cue light was illuminated and

REVIEW OF INDOOR EMISSION SOURCE MODELS--PART 1. OVERVIEW

EPA Science Inventory

Indoor emission source models are mainly used as a component in indoor air quality (IAQ) and exposure modeling. They are also widely used to interpret the experimental data obtained from environmental chambers and buildings. This paper compiles 46 indoor emission source models fo...

Microbial ranking of porous packaging materials (exposure chamber method), ASTM method: collaborative study.

PubMed

Placencia, A M; Peeler, J T

1999-01-01

A collaborative study involving 11 laboratories was conducted to measure the microbial barrier effectiveness of porous medical packaging. Two randomly cut samples from each of 6 commercially available porous materials and one positive and one negative control were tested by one operator in each of 11 laboratories. Microbial barrier effectiveness was measured in terms of logarithm reduction value (LRV), which reflects the log10 microbial penetration of the material being tested. The logarithm of the final concentration is subtracted from that of the initial concentration to obtain the LRV. Thus the higher the LRV, the better the barrier. Repeatability standard deviations ranged from 6.42 to 16.40; reproducibility standard deviations ranged from 15.50 to 22.70. Materials B(53), C(50), D(CT), and E(45MF) differ significantly from the positive control. The microbial ranking of porous packaging materials (exposure chamber method), ASTM method, has been adopted First Action by AOAC INTERNATIONAL.

A review of chamber experiments for determining specific emission rates and investigating migration pathways of flame retardants

NASA Astrophysics Data System (ADS)

Rauert, Cassandra; Lazarov, Borislav; Harrad, Stuart; Covaci, Adrian; Stranger, Marianne

2014-01-01

The widespread use of flame retardants (FRs) in indoor products has led to their ubiquitous distribution within indoor microenvironments with many studies reporting concentrations in indoor air and dust. Little information is available however on emission of these compounds to air, particularly the measurement of specific emission rates (SERs), or the migration pathways leading to dust contamination. Such knowledge gaps hamper efforts to develop understanding of human exposure. This review summarizes published data on SERs of the following FRs released from treated products: polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs), tetrabromobisphenol-A (TBBPA), novel brominated flame retardants (NBFRs) and organophosphate flame retardants (PFRs), including a brief discussion of the methods used to derive these SERs. Also reviewed are published studies that utilize emission chambers for investigations/measurements of mass transfer of FRs to dust, discussing the chamber configurations and methods used for these experiments. A brief review of studies investigating correlations between concentrations detected in indoor air/dust and possible sources in the microenvironment is included along with efforts to model contamination of indoor environments. Critical analysis of the literature reveals that the major limitations with utilizing chambers to derive SERs for FRs arise due to the physicochemical properties of FRs. In particular, increased partitioning to chamber surfaces, airborne particles and dust, causes loss through “sink” effects and results in long times to reach steady state conditions inside the chamber. The limitations of chamber experiments are discussed as well as their potential for filling gaps in knowledge in this area.

Changes in deviation of absorbed dose to water among users by chamber calibration shift.

PubMed

Katayose, Tetsurou; Saitoh, Hidetoshi; Igari, Mitsunobu; Chang, Weishan; Hashimoto, Shimpei; Morioka, Mie

2017-07-01

The JSMP01 dosimetry protocol had adopted the provisional 60 Co calibration coefficient [Formula: see text], namely, the product of exposure calibration coefficient N C and conversion coefficient k D,X . After that, the absorbed dose to water D w  standard was established, and the JSMP12 protocol adopted the [Formula: see text] calibration. In this study, the influence of the calibration shift on the measurement of D w among users was analyzed. The intercomparison of the D w using an ionization chamber was annually performed by visiting related hospitals. Intercomparison results before and after the calibration shift were analyzed, the deviation of D w among users was re-evaluated, and the cause of deviation was estimated. As a result, the stability of LINAC, calibration of the thermometer and barometer, and collection method of ion recombination were confirmed. The statistical significance of standard deviation of D w was not observed, but that of difference of D w among users was observed between N C and [Formula: see text] calibration. Uncertainty due to chamber-to-chamber variation was reduced by the calibration shift, consequently reducing the uncertainty among users regarding D w . The result also pointed out uncertainty might be reduced by accurate and detailed instructions on the setup of an ionization chamber.

A Technique for Murine Irradiation in a Controlled Gas Environment

PubMed Central

Walb, M. C.; Moore, J. E.; Attia, A.; Wheeler, K. T.; Miller, M. S.; Munley, M. T.

2013-01-01

NASA’s extra-vehicular activities (EVAs) involve exposure to high energy photons while breathing 100% oxygen. Using previously verified mouse models, our laboratory is studying whether low dose irradiation under these hyperoxic conditions could lead to an increase in carcinogenic potential. To simulate the environment astronauts encounter during an EVA, enclosed chambers were constructed that allowed for mouse movement, controlled gas conditions, and uniform radiation dose delivery. Custom-built gas chambers with input/output gas valves and dividers that allowed for uniform gas flow were used to keep 6 unanesthetized mice separated while they were irradiated. The chambers were supplied with 100% oxygen or air using ball valves linked together with T-splitters. A calibrated ion chamber was used to verify the radiation dose distribution across an entire chamber. Mice were placed in the gas environments for 0.5 h, irradiated with a 10 or 18 MV photon beam from a medical linear accelerator, and left in their gas environment for 2 h post-irradiation. We irradiated 200 mice (5 different doses between 0–1000 mGy) under normoxic or 100% oxygen conditions. For the next step of this research, these mice will be euthanized 9 months post-irradiation, and lung tumors will be counted and sized to determine if hyperoxia increases the carcinogenic effect for this model. PMID:22846321

Functionalization of Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2009-01-01

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

Decalcification of benthic foraminifera due to "Hebei Spirit" oil spill, Korea.

PubMed

Lee, Yeon Gyu; Kim, Shin; Jeong, Da Un; Lee, Jung Sick; Woo, Han Jun; Park, Min Woo; Kim, Byeong Hak; Son, Maeng Hyun; Choi, Yang Ho

2014-10-15

In order to determine the effects on foraminifera due to spilled crude oil in the "Herbei Spirit" incident, a study of benthic foraminiferal assemblages was carried out on sediment samples collected from the Sogeunri tidal flat, Taean Peninsula, Korea. Breakages of the chambers in the Ammonia beccarii and Elphidium subincertum species of the Sogeunri tidal flat with a low pH (6.98 on average) were marked. These chamber breakages occurred in 71.6% of A. beccarii and are thought to be caused by decalcification due to the fall in pH resulting from the "Hebei Spirit" oil spill. The factors that affect breakage of the chamber in benthic foraminifera under low pH condition may be not only deto decalcification but also to exposure duration of substrata in the tidal flat spilled crude oil. Copyright © 2014 Elsevier Ltd. All rights reserved.

Development and validation of a GEANT4 radiation transport code for CT dosimetry

PubMed Central

Carver, DE; Kost, SD; Fernald, MJ; Lewis, KG; Fraser, ND; Pickens, DR; Price, RR; Stabin, MG

2014-01-01

We have created a radiation transport code using the GEANT4 Monte Carlo toolkit to simulate pediatric patients undergoing CT examinations. The focus of this paper is to validate our simulation with real-world physical dosimetry measurements using two independent techniques. Exposure measurements were made with a standard 100-mm CT pencil ionization chamber, and absorbed doses were also measured using optically stimulated luminescent (OSL) dosimeters. Measurements were made in air, a standard 16-cm acrylic head phantom, and a standard 32-cm acrylic body phantom. Physical dose measurements determined from the ionization chamber in air for 100 and 120 kVp beam energies were used to derive photon-fluence calibration factors. Both ion chamber and OSL measurement results provide useful comparisons in the validation of our Monte Carlo simulations. We found that simulated and measured CTDI values were within an overall average of 6% of each other. PMID:25706135

Development and validation of a GEANT4 radiation transport code for CT dosimetry.

PubMed

Carver, D E; Kost, S D; Fernald, M J; Lewis, K G; Fraser, N D; Pickens, D R; Price, R R; Stabin, M G

2015-04-01

The authors have created a radiation transport code using the GEANT4 Monte Carlo toolkit to simulate pediatric patients undergoing CT examinations. The focus of this paper is to validate their simulation with real-world physical dosimetry measurements using two independent techniques. Exposure measurements were made with a standard 100-mm CT pencil ionization chamber, and absorbed doses were also measured using optically stimulated luminescent (OSL) dosimeters. Measurements were made in air with a standard 16-cm acrylic head phantom and with a standard 32-cm acrylic body phantom. Physical dose measurements determined from the ionization chamber in air for 100 and 120 kVp beam energies were used to derive photon-fluence calibration factors. Both ion chamber and OSL measurement results provide useful comparisons in the validation of the Monte Carlo simulations. It was found that simulated and measured CTDI values were within an overall average of 6% of each other.

Changes in fluorescence spectra of bioaerosols exposed to ozone in a laboratory reaction chamber to simulate atmospheric aging.

PubMed

Santarpia, Joshua L; Pan, Yong-Le; Hill, Steven C; Baker, Neal; Cottrell, Brian; McKee, Laura; Ratnesar-Shumate, Shanna; Pinnick, Ronald G

2012-12-31

A laboratory system for exposing aerosol particles to ozone and rapidly measuring the subsequent changes in their single-particle fluorescence is reported. The system consists of a rotating drum chamber and a single-particle fluorescence spectrometer (SPFS) utilizing excitation at 263 nm. Measurements made with this system show preliminary results on the ultra-violet laser-induced-fluorescence (UV-LIF) spectra of single aerosolized particles of Yersinia rohdei, and of MS2 (bacteriophage) exposed to ozone. When bioparticles are exposed in the chamber the fluorescence emission peak around 330 nm: i) decreases in intensity relative to that of the 400-550 nm band; and ii) shifts slightly toward shorter-wavelengths (consistent with further drying of the particles). In these experiments, changes were observed at exposures below the US Environmental Protection Agency (EPA) limits for ozone.

Dark Matter Search Results from the PICO -60 C 3F8 Bubble Chamber

NASA Astrophysics Data System (ADS)

Amole, C.; Ardid, M.; Arnquist, I. J.; Asner, D. M.; Baxter, D.; Behnke, E.; Bhattacharjee, P.; Borsodi, H.; Bou-Cabo, M.; Campion, P.; Cao, G.; Chen, C. J.; Chowdhury, U.; Clark, K.; Collar, J. I.; Cooper, P. S.; Crisler, M.; Crowder, G.; Dahl, C. E.; Das, M.; Fallows, S.; Farine, J.; Felis, I.; Filgas, R.; Girard, F.; Giroux, G.; Hall, J.; Harris, O.; Hoppe, E. W.; Jin, M.; Krauss, C. B.; Laurin, M.; Lawson, I.; Leblanc, A.; Levine, I.; Lippincott, W. H.; Mamedov, F.; Maurya, D.; Mitra, P.; Nania, T.; Neilson, R.; Noble, A. J.; Olson, S.; Ortega, A.; Plante, A.; Podviyanuk, R.; Priya, S.; Robinson, A. E.; Roeder, A.; Rucinski, R.; Scallon, O.; Seth, S.; Sonnenschein, A.; Starinski, N.; Štekl, I.; Tardif, F.; Vázquez-Jáuregui, E.; Wells, J.; Wichoski, U.; Yan, Y.; Zacek, V.; Zhang, J.; PICO Collaboration

2017-06-01

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C3 F8 located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO -60 C 3F8 exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4 ×10-41 cm2 for a 30 -GeV c-2 WIMP, more than 1 order of magnitude improvement from previous PICO results.

Improved dark matter search results from PICO-2L Run 2

DOE PAGES

Amole, C.

2016-03-01

New data are reported from a second run of the 2-liter PICO-2L C 3F 8 bubble chamber with a total exposure of 129 kg-days at a thermodynamic threshold energy of 3.3 keV. These data show that measures taken to control particulate contamination in the superheated fluid resulted in the absence of the anomalous background events observed in the first run of this bubble chamber. One single nuclear-recoil event was observed in the data, consistent both with the predicted background rate from neutrons and with the observed rate of unambiguous multiple-bubble neutron scattering events. The chamber exhibits the same excellent electron-recoil and alphamore » decay rejection as was previously reported. These data provide the most stringent direct detection constraints on weakly interacting massive particle (WIMP)-proton spin-dependent scattering to date for WIMP masses <50 GeV/c 2.« less

Changes in the emission properties of metallic targets upon exposure to repetitively pulsed laser radiation

NASA Astrophysics Data System (ADS)

Konov, V. I.; Pimenov, S. M.; Prokhorov, A. M.; Chapliev, N. I.

1988-02-01

A scanning electron microscope and a repetitively pulsed CO2 laser are used to reveal the relationships which govern the correlation of the transforming metal surface microrelief with the emission of charged particles and the surface luminescence upon exposure to multipulse laser focusing. It is shown that the effect of sorption and laser-stimulated desorption on the emission signals can manifest itself in different ways depending on the current oscillation mode in the target-vacuum chamber circuit.

Development and characterization of a resistance spot welding aerosol generator and inhalation exposure system.

PubMed

Afshari, Aliakbar; Zeidler-Erdely, Patti C; McKinney, Walter; Chen, Bean T; Jackson, Mark; Schwegler-Berry, Diane; Friend, Sherri; Cumpston, Amy; Cumpston, Jared L; Leonard, H Donny; Meighan, Terence G; Frazer, David G; Antonini, James M

2014-10-01

Limited information exists regarding the health risks associated with inhaling aerosols that are generated during resistance spot welding of metals treated with adhesives. Toxicology studies evaluating spot welding aerosols are non-existent. A resistance spot welding aerosol generator and inhalation exposure system was developed. The system was designed by directing strips of sheet metal that were treated with an adhesive to two electrodes of a spot welder. Spot welds were made at a specified distance from each other by a computer-controlled welding gun in a fume collection chamber. Different target aerosol concentrations were maintained within the exposure chamber during a 4-h exposure period. In addition, the exposure system was run in two modes, spark and no spark, which resulted in different chemical profiles and particle size distributions. Complex aerosols were produced that contained both metal particulates and volatile organic compounds (VOCs). Size distribution of the particles was multi-modal. The majority of particles were chain-like agglomerates of ultrafine primary particles. The submicron mode of agglomerated particles accounted for the largest portion of particles in terms of particle number. Metal expulsion during spot welding caused the formation of larger, more spherical particles (spatter). These spatter particles appeared in the micron size mode and accounted for the greatest amount of particles in terms of mass. With this system, it is possible to examine potential mechanisms by which spot welding aerosols can affect health, as well as assess which component of the aerosol may be responsible for adverse health outcomes.

SPME-Based Ca-History Method for Measuring SVOC Diffusion Coefficients in Clothing Material.

PubMed

Cao, Jianping; Liu, Ningrui; Zhang, Yinping

2017-08-15

Clothes play an important role in dermal exposure to indoor semivolatile organic compounds (SVOCs). The diffusion coefficient of SVOCs in clothing material (D m ) is essential for estimating SVOC sorption by clothing material and subsequent dermal exposure to SVOCs. However, few studies have reported the measured D m for clothing materials. In this paper, we present the solid-phase microextraction (SPME) based C a -history method. To the best of our knowledge, this is the first try to measure D m with known relative standard deviation (RSD). A thin sealed chamber is formed by a circular ring and two pieces of flat SVOC source materials that are tightly covered by the targeted clothing materials. D m is obtained by applying an SVOC mass transfer model in the chamber to the history of gas-phase SVOC concentrations (C a ) in the chamber measured by SPME. D m 's of three SVOCs, di-iso-butyl phthalate (DiBP), di-n-butyl phthalate (DnBP), and tris(1-chloro-2-propyl) phosphate (TCPP), in a cotton T-shirt can be obtained within 16 days, with RSD less than 3%. This study should prove useful for measuring SVOC D m in various sink materials. Further studies are expected to facilitate application of this method and investigate the effects of temperature, relative humidity, and clothing material on D m .

Exposure of men to intermittent photic stimulation under simulated IFR conditions.

DOT National Transportation Integrated Search

1966-10-01

Ten men were subjected to intermittent photic stimulation in an airplane cockpit in an environmental chamber by (1) a Grimes red rotating beacon (1.5 FPS), (2) an Air Guard strobe light (1.0 FPS) and (3) propeller flicker (10 FPS). IFR conditions wer...

A Proposed Mechanism for Hypobaria Induced Neuronal Injury: A Swine Model

DTIC Science & Technology

2017-04-22

Non-hypoxic hypobaric exposure in Air Force U-2 pilots and hypobaric chamber personnel is associated with increased brain white matter...utilizing advanced techniques such as multi-b-value diffusion (Q-space) and kurtosis anisotropy. We developed a swine model to test this theory.

Right pleuropericardial release: a useful technique in off-pump coronary surgery.

PubMed

Velissaris, Theodore; Stuklis, Robert G; Hett, David A; Ohri, Sunil K

2003-06-01

We describe the use of right pleurotomy combined with right pericardial release during off-pump coronary surgery. The maneuver releases the compression exerted on the right cardiac chambers during cardiac verticalization and improves hemodynamic stability during exposure of the posterior or lateral coronary vessels.

OZONE ALTERS THE CONCENTRATIONS OF NUTRIENTS IN BEAN TISSUE

EPA Science Inventory

Studies were conducted to determine the impact of ozone on the nutrient concentrations in tissue from various organs of beans (Phaseolus vulgaris L. cv Bush Bluelake 290). The plants were exposed to episodic concentrations of ozone in open-top field exposure chambers from soon af...

Screening of Bangladeshi winter wheat (Triticum aestivum L.) cultivars for sensitivity to ozone

USDA-ARS?s Scientific Manuscript database

The sensitivity to ozone of ten Bangladeshi wheat cultivars was tested by exposing plants to eight ozone exposure regimes in controlled environment chambers. Visible leaf injury, dry weight, chlorophyll, carotenoid content, leaf greenness (SPAD value), quantum yield of photochemistry and stomatal re...

Ultra-Accelerated Natural Sunlight Exposure Testing Facilities

DOEpatents

Lewandowski, Allan A.; Jorgensen, Gary J.

2004-11-23

A multi-faceted concentrator apparatus for providing ultra-accelerated natural sunlight exposure testing for sample materials under controlled weathering conditions comprising: facets that receive incident natural sunlight, transmits VIS/NIR and reflects UV/VIS onto a secondary reflector that delivers a uniform flux of UV/VIS onto a sample exposure plane located near a center of a facet array in a chamber that provide concurrent levels of temperature and/or relative humidity at high levels of up to 100.times. of natural sunlight that allow sample materials to be subjected to accelerated irradiance exposure factors for a significant period of time of about 3 to 10 days to provide a corresponding time of about at least a years worth representative weathering of sample materials.

Effects of Radon Inhalation on Some Biophysical Properties of Blood in Rats

NASA Astrophysics Data System (ADS)

Essa, M. F.; Shahin, Fayez M.; Ahmed, Ashour M.; Abdel-Salam, Omar

2013-03-01

The major source of human exposure to natural radiation arises from the inhalation of radon (222Rn) gas. Exposure to high concentrations of radon 222Rn and its daughters for long period leads to pathological effects like lung cancer, leukaemia, skin cancer and kidney diseases. The present study was performed on rats to investigate the effect of radon exposure on the absorption spectra of hemoglobin. Measurements have been performed in a radon chamber where rats were exposed to radon for 1, 5 or 7 weeks. The inhalation of radon resulted in decrease in intensity of the absorption bands characterizing the hemoglobin molecular structure with increased radon doses.

Preacclimatization in hypoxic chambers for high altitude sojourns.

PubMed

Küpper, Thomas E A H; Schöffl, Volker

2010-09-01

Since hypoxic chambers are more and more available, they are used for preacclimatization to prepare for sojourns at high altitude. Since there are different protocols and the data differ, there is no general consensus about the standard how to perform preacclimatization by simulated altitude. The paper reviews the different types of exposure and focuses on the target groups which may benefit from preacclimatization. Since data about intermittent hypoxia for some hours per day to reduce the incidence of acute mountain sickness differ, it is suggested to perform preacclimatization by sleeping some nights at a simulated altitude which follows the altitude profile of the "gold standard" for high altitude acclimatization.

The use of FT-IR reflection-absorbance spectroscopy to study photochemical degradation of polymeric coatings on mirrors

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

Webb, J.D.; Chughtai, A.R.; Czanderna, A.W.

1981-10-01

A technique is presented for in situ study of degradative changes in polymeric coatings on metallic substrates. The technique uses a controlled environment chamber in conjunction with a Fourier-transform infrared (FT-IR) spectrophotometer. The chamber design permits collection of IR reflection-absorbance spectra from a sample undergoing exposure to controlled ultraviolet (UV) radiation, gas mixtures, and temperatures. Initial data presented confirm the ability of the technique to provide information regarding the bulk photochemistry of bisphenol-A polycarbonate coatings on gold and aluminum substrates. Refinements of this technique should allow a detailed kinetic study of degradative reactions at the polymer/metal interface.

Use of FT-IR reflection-absorbance spectroscopy to study photochemical degradation of polymeric coatings on mirrors

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

Webb, J D; Schissel, P; Czanderna, A W

1981-01-01

A technique is presented for in situ study of degradative changes in polymeric coatings on metallic substrates. The technique uses a controlled environment chamber in conjunction with a Fourier-transform infrared (FT-IR) spectrophotometer. The chamber design permits collection of IR reflection-absorbance spectra from a sample undergoing exposure to controlled ultraviolet (uv) radiation, gas mixtures, and temperatures. Initial data presented confirm the ability of the technique to provide information regarding the bulk photochemistry of bisphenol-A polycarbonate coatings on gold and aluminum substrates. Refinements of this technique should allow a detailed kinetic study of degradative reactions at the polymer/metal interface.

Methods for study of cardiovascular adaptation of small laboratory animals during exposure to altered gravity. [hypothermia for cardiovascular control and cancer therapy

NASA Technical Reports Server (NTRS)

Popovic, V.

1973-01-01

Several new techniques are reported for studying cardiovascular circulation in small laboratory animals kept in metabolic chambers. Chronical cannulation, miniaturized membrane type heart-lung machines, a prototype walking chamber, and a fluorocarbon immersion method to simulate weightlessness are outlined. Differential hypothermia work on rat cancers provides localized embedding of radionuclides and other chemotherapeutical agents in tumors and increases at the same time blood circulation through the warmed tumor as compared to the rest of the cold body. Some successful clinical applications of combined chemotherapy and differential hypothermia in skin cancer, mammary tumors, and brain gliomas are described.

Single-pass environmental chamber for quantifying human responses to airborne chemicals.

PubMed

Suarez, Joseph C; Warmath, D Stan; Koetz, Kurt P; Hood, Alison F; Thompson, Mark L; Kendal-Reed, Martin S; Walker, Dianne B; Walker, James C

2005-03-01

Despite increasing interest in the short-term effects of airborne environmental contaminants, experimental findings are generated at a very slow pace. This is due in part to the expense and complexity of most environmental chambers, which are needed for quantifying effects of wholebody exposures. We lessened this obstacle by designing, constructing, and testing a single-pass, 10-m3 stainless-steel chamber. Compressed air is purified before being sent to an air dilution olfactometer, which supplies 1000 L (1 m3) per minute (referenced to STP) while maintaining 40% relative humidity (RH) and 22.6 degrees C. Precise control of all stimulus parameters is greatly simplified since air is not recirculated. Vapor-phase odorant concentrations are achieved by varying the proportion of total airflow passing through one or more saturators, and are verified in real time by an infrared (IR) spectrometer. An adjoining 5-m3 anteroom is used for introducing known intensities of more chemically complex vapor and/or particulate stimuli into the chamber. Prior to the point that air is exhausted from the chamber, all components are made of stainless steel, Teflon, or glass. A LabView program contains feedback loops that achieve document chamber conditions and document performance. Additional instrumentation and computer systems provide for the automated collection of perceptual, respiratory, eye blink, heart rate, blood pressure, psychological state, and cognitive data. These endpoints are now being recorded, using this facility, in response to ranges of concentrations of propionic acid and environmental tobacco smoke.

Biomarkers of human cardiopulmonary response after short-term exposures to medical laser generated particulate matter from simulated procedures: a pilot study

PubMed Central

Lopez, Ramon; Farber, Mark O.; Wong, Vincent; Lacey, Steven E.

2016-01-01

Objective We conducted an exposure chamber study in humans using a simulated clinical procedure lasing porcine tissue to demonstrate evidence of effects of exposure to laser generated particulate matter (LGPM). Methods We measured pre- and post-exposure changes in exhaled nitric oxide (eNO), spirometry, heart rate variability (HRV), and blood markers of inflammation in five volunteers. Results Change in pre- and post-exposure measurements of eNO and spirometry were unremarkable. Neutrophil and lymphocyte counts increased and fibrinogen levels decreased in four of the five subjects. Measures of HRV showed decreases in the standard deviation of normal between beat intervals and sequential five-minute intervals. Conclusion These data represent the first evidence of human physiologic response to LGPM exposure. Further exploration of coagulation effects and HRV are warranted. PMID:27465102

Enhanced Deposition by Electrostatic Field-Assistance Aggravating Diesel Exhaust Aerosol Toxicity for Human Lung Cells.

PubMed

Stoehr, Linda C; Madl, Pierre; Boyles, Matthew S P; Zauner, Roland; Wimmer, Monika; Wiegand, Harald; Andosch, Ancuela; Kasper, Gerhard; Pesch, Markus; Lütz-Meindl, Ursula; Himly, Martin; Duschl, Albert

2015-07-21

Air pollution is associated with increased risk of cardiovascular and pulmonary diseases, but conventional air quality monitoring gives no information about biological consequences. Exposing human lung cells at the air-liquid interface (ALI) to ambient aerosol could help identify acute biological responses. This study investigated electrode-assisted deposition of diesel exhaust aerosol (DEA) on human lung epithelial cells (A549) in a prototype exposure chamber. A549 cells were exposed to DEA at the ALI and under submerged conditions in different electrostatic fields (EFs) and were assessed for cell viability, membrane integrity, and IL-8 secretion. Qualitative differences of the DEA and its deposition under different EFs were characterized using scanning mobility particle sizer (SMPS) measurements, transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). Upon exposure to DEA only, cell viability decreased and membrane impairment increased for cells at the ALI; submerged cells were unaffected. These responses were enhanced upon application of an EF, as was DEA deposition. No adverse effects were observed for filtered DEA or air only, confirming particle-induced responses. The prototype exposure chamber proved suitable for testing DEA-induced biological responses of cells at the ALI using electrode-assisted deposition and may be useful for analysis of other air pollutants.

Cerium Oxide Nanoparticle Nose-Only Inhalation Exposures ...

EPA Pesticide Factsheets

There is a critical need to assess the health effects associated with exposure of commercially produced NPs across the size ranges reflective of that detected in the industrial sectors that are generating, as well as incorporating, NPs into products. Generation of stable and low concentrations of size-fractionated nanoscale aerosols in nose-only chambers can be difficult, and when the aerosol agglomerates during generation, the problems are significantly increased. One problem is that many nanoscale aerosol generators have higher aerosol output and/or airflow than can be accommodated by a nose-only inhalation chamber, requiring much of the generated aerosol to be diverted to exhaust. Another problem is that mixing vessels used to modulate the fluctuating output from aerosol generators can cause substantial wall losses, consuming much of the generated aerosol. Other available aerosol generation systems can produce nanoscale aerosols from nanoparticles (NPs), however these NPs are generated in real time and do not approximate the physical and chemical characteristics of NPs that are commercially produced exposing the workers and the public. The health effects associated with exposure to commercial NP production, which are more morphologically and size heterogeneous, is required for risk assessment. To overcome these problems, a low-consumption dry-particulate nanoscale aerosol generator was developed to deliver stable concentrations in the range of 10–5000 µg

Biological effects of short-term, high-concentration exposure to methyl isocyanate. V. Morphologic evaluation of rat and guinea pig lungs

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

Fowler, E.H.; Dodd, D.E.; Troup, C.M.

1987-06-01

The morphologic changes induced in the lungs of rats and guinea pigs exposed to high concentrations of MIC vapor (100, 600, and 1000 ppm in the rat and 25, 125, 225, and 675 ppm in the guinea pig) for a short time (15 min) in a static exposure chamber were evaluated at varying postexposure periods (0, 1, 2, and 4, and 16 hr). The 675 ppm-exposed guinea pigs were evaluated only immediately following removal from the chamber. Attention was primarily focused on the intrapulmonary conducting airways and the parenchyma (gas exchange region) of the lungs. The severity of morphologic changesmore » observed by light microscopy was directly correlated with exposure concentration and time postexposure in both species. Specifically, degenerative changes were observed in the bronchial, bronchiolar, and alveolar epithelium in both species. Quantitative differences were observed; 100 ppm of MIC in the rat resulted in much less damage than did 125 ppm of MIC in the guinea pig. Morphologic evidence of sloughing of large sheets of conducting airway epithelium with fibrin buildup and increased mucus production resulted in plugging of major airways and atelectasis. These observations support the hypothesis that tissue hypoxia was a major contributing factor resulting in death.« less

An intercomparison for NIRS and NYU passive thoron gas detectors at NYU.

PubMed

Sorimachi, Atsuyuki; Ishikawa, Tetsuo; Tokonami, Shinji; Chittaporn, Passaporn; Harley, Naomi H

2012-04-01

An intercomparison on thoron ((220)Rn) measurement was carried out between National Institute of Radiological Sciences, Japan (NIRS), and New York University School of Medicine, USA (NYU). The measurements of (220)Rn concentration at NIRS and NYU were performed by using the scintillation cell method and the two-filter method, respectively, as the standard measurement method. Three types of alpha track detectors based on passive radon ((222)Rn)-(220)Rn discriminative measurement technique were used: Raduet and Radopot detectors were used at NIRS, and four-leaf detectors were used at NYU. In this study, the authors evaluated (220)Rn concentration variation in terms of run for exposure, measurement method, and exposure chamber. The detectors were exposed to (220)Rn gas with approximately 15 kBq m(-3) during the period from 0.75 to 3 d. As a result, the variation of each measurement method among these exposure runs was comparable to or less than that for the two-filter method. Agreement between the standard measurement methods of NIRS and NYU was observed to be about 10%, as is the case with the passive detectors. The Raduet detector showed a large variation in the detection response between the NIRS and NYU chambers, which could be related to different traceability.

Prevention of suture knot exposure in posterior chamber intraocular lens implantation by 4-point scleral fixation technique.

PubMed

Baykara, Mehmet; Avci, Remzi

2004-01-01

The results and complications of posterior chamber intraocular lens (IOL) implantation by a 4-point scleral fixation technique are described. Fifty eyes of 47 patients who underwent scleral-fixated IOL implantation were retrospectively evaluated. Twenty-one (42%) eyes had a history of trauma and 29 (58%) eyes had previously undergone cataract surgery. In all cases, IOL implantation by 4-point scleral fixation was performed and the knots of fixation sutures were rotated and buried in the globe. The IOL position was adjusted by suture rotation for best centration. The mean follow-up time was 7 +/- 4 months. Four (8%) eyes had minimal corneal edema preoperatively. Cystoid macular edema was noted in 2 (6.8%) eyes in the cataract surgery group and 8 (38%) eyes in the posttraumatic group. Two (9.5%) eyes in the posttraumatic group had atrophic macular changes and 1 (4.7%) had corneal scarring, which impaired vision. No complications such as knot exposure, tilting of the IOL, decentralization, or endophthalmitis were noted postoperatively. Postoperative mean corrected visual acuity was 0.4 +/- 0.3 in the posttraumatic group and 0.4 +/- 0.2 in the cataract surgery group. The 4-point scleral fixation technique resulted in no serious postoperative complications such as suture exposure and endophthalmitis. Because the knot can be rotated and buried in the globe, knot exposure is less likely to occur. This procedure is more effective than other techniques regarding IOL centralization.

Development of a passive air sampler to measure airborne organophosphorus pesticides and oxygen analogs in an agricultural community.

PubMed

Armstrong, Jenna L; Yost, Michael G; Fenske, Richard A

2014-09-01

Organophosphorus pesticides are some of the most widely used insecticides in the US, and spray drift may result in human exposures. We investigate sampling methodologies using the polyurethane foam passive air sampling device to measure cumulative monthly airborne concentrations of OP pesticides chlorpyrifos, azinphos-methyl, and oxygen analogs. Passive sampling rates (m(3)d(-1)) were determined using calculations using chemical properties, loss of depuration compounds, and calibration with side-by-side active air sampling in a dynamic laboratory exposure chamber and in the field. The effects of temperature, relative humidity, and wind velocity on outdoor sampling rates were examined at 23 sites in Yakima Valley, Washington. Indoor sampling rates were significantly lower than outdoors. Outdoor rates significantly increased with average wind velocity, with high rates (>4m(3)d(-1)) observed above 8ms(-1). In exposure chamber studies, very little oxygen analog was observed on the PUF-PAS, yet substantial amounts chlorpyrifos-oxon and azinphos methyl oxon were measured in outdoor samples. PUF-PAS is a practical and useful alternative to AAS because it results in little artificial transformation to the oxygen analog during sampling, it provides cumulative exposure estimates, and the measured sampling rates were comparable to rates for other SVOCs. It is ideal for community based participatory research due to low subject burden and simple deployment in remote areas. Copyright © 2014 Elsevier Ltd. All rights reserved.

40 CFR 797.1330 - Daphnid chronic toxicity test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... an extended period of time. In this test guideline, mortality and reproduction (and optionally... exposure over a specified period of time. In this guideline, the effect measured is immobilization. (4..., wet weight) to the volume (liters) of test solution in a test chamber at a point in time or passing...

IMPACT OF O3 ON LEAF CONSTRUCTION COST AND CARBON ISOTOPE DISCRIMINATION

EPA Science Inventory

Plant response to ozone (O3) is controlled by the interactive balance between avoidance and intolerance processes. ush bean (Phaseolus vulgaris L.) plants were exposed to O3 in open-top field-exposure chambers in early and late season studies at Corvallis, Oregon. lants were grow...

DIRECT MEASUREMENT TECHNIQUE FOR THE DETERMINING VENTILATION RATE IN THE DEPOSIT FEEDING CLAM, MACOMA NASUTA (BIVALVIA, TELLINACEAE)

EPA Science Inventory

An exposure chamber, the "clambox", was developed to measure ventilation rate, sediment processing rate, and efficiency of pollutant uptake byMacoma nasuta Conrad, a surface surface deposit-feeding clams. Clams, collected from Yaquina, Bay, Oregon, USA, were cemented into a hole ...

INDEPENDENT AND CONTRASTING EFFECTS OF ELEVATED CO2 AND N-FERTILIZATION ROOT ARCHITECTURE

EPA Science Inventory

The effects of elevated CO2 and N fertilization on architecture of Pinus ponderosa fine roots and their associated mycorrhizal symbionts were measured over a 4-year period. The study was conducted in open-top field-exposure chambers located near Placerville, CA. A replicated (thr...

Description of the microbial ecology evaluation device, flight equipment, and ground transporter

NASA Technical Reports Server (NTRS)

Chassay, C. E.; Taylor, G. R.

1973-01-01

Exposure of test systems in space required the fabrication of specialized hardware termed a Microbial Ecology Evaluation Device that had individual test chambers and a complex optical filter system. The characteristics of this device and the manner in which it was deployed in space are described.

POTENTIAL FOR REDUCING STYRENE EXPOSURES FROM COPIED PAPER THROUGH USE OF LOW-EMITTING TONERS

EPA Science Inventory

The paper reports results of tests, conducted using 53-L chambers to determine styrene emission rates from freshly copied paper produced on a single photocopier using two toners manufactured for the copier having different styrene contents. Copied-paper styrene emissions with bot...

POTENTIAL FOR REDUCING INDOOR STYRENE EXPOSURE FROM COPIED PAPER THROUGH USE OF LOW-EMITTING TONERS

EPA Science Inventory

Tests were conducted, using 53-L dynamic chambers, to determine airborne styrene emission rates over time from freshly copied paper. Copies were produced on a single photocopier, using two toners manufactured for this copier but having different styrene contents. The resulting em...

PLANT CULTURAL SYSTEM FOR MONITORING EVAPOTRANSPIRATION AND PHYSIOLOGICAL RESPONSES UNDER FIELD CONDITIONS

EPA Science Inventory

A plant culture system incorporating the water-table root-screen method for controlling plant water status was adapted for use in open-top field exposure chambers for studying the effects of drought stress on physiological responses. The daily transpiration rates of the plants we...

QUANTITATIVE ULTRAVIOLET SPECTROSCOPY IN WEATHERING OF A MODEL POLYESTER-URETHANE COATING. (R828081E01)

EPA Science Inventory

Spectroscopy was used to quantify the effects of ultraviolet light on a model polyester–urethane coating as it degraded in an accelerated exposure chamber. An explorative calculation of the effective dosage absorbed by the coatings was made and, depending on the quantum...

40 CFR 797.1330 - Daphnid chronic toxicity test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... an extended period of time. In this test guideline, mortality and reproduction (and optionally... exposure over a specified period of time. In this guideline, the effect measured is immobilization. (4..., wet weight) to the volume (liters) of test solution in a test chamber at a point in time or passing...

40 CFR 797.1300 - Daphnid acute toxicity test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... continuous exposure over a specified period of time. In this guideline, the effect measured is immobilization... at a point in time, or passing through the test chamber during a specific interval. (7) Static system..., daphnids which have been cultured and acclimated in accordance with the test design are randomly placed...

40 CFR 797.1300 - Daphnid acute toxicity test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... continuous exposure over a specified period of time. In this guideline, the effect measured is immobilization... at a point in time, or passing through the test chamber during a specific interval. (7) Static system..., daphnids which have been cultured and acclimated in accordance with the test design are randomly placed...

40 CFR 797.1300 - Daphnid acute toxicity test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... continuous exposure over a specified period of time. In this guideline, the effect measured is immobilization... at a point in time, or passing through the test chamber during a specific interval. (7) Static system..., daphnids which have been cultured and acclimated in accordance with the test design are randomly placed...

40 CFR 797.1330 - Daphnid chronic toxicity test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... an extended period of time. In this test guideline, mortality and reproduction (and optionally... exposure over a specified period of time. In this guideline, the effect measured is immobilization. (4..., wet weight) to the volume (liters) of test solution in a test chamber at a point in time or passing...

40 CFR 797.1300 - Daphnid acute toxicity test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... continuous exposure over a specified period of time. In this guideline, the effect measured is immobilization... at a point in time, or passing through the test chamber during a specific interval. (7) Static system..., daphnids which have been cultured and acclimated in accordance with the test design are randomly placed...

40 CFR 797.1330 - Daphnid chronic toxicity test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... an extended period of time. In this test guideline, mortality and reproduction (and optionally... exposure over a specified period of time. In this guideline, the effect measured is immobilization. (4..., wet weight) to the volume (liters) of test solution in a test chamber at a point in time or passing...

40 CFR 797.1300 - Daphnid acute toxicity test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... continuous exposure over a specified period of time. In this guideline, the effect measured is immobilization... at a point in time, or passing through the test chamber during a specific interval. (7) Static system..., daphnids which have been cultured and acclimated in accordance with the test design are randomly placed...

40 CFR 797.1330 - Daphnid chronic toxicity test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... an extended period of time. In this test guideline, mortality and reproduction (and optionally... exposure over a specified period of time. In this guideline, the effect measured is immobilization. (4..., wet weight) to the volume (liters) of test solution in a test chamber at a point in time or passing...

Pulmonary toxicity following exposure to a tile coating product containing alkylsiloxanes. A clinical and toxicological evaluation

PubMed Central

Nørgaard, A. W.; Hansen, J. S.; Sørli, J. B.; Jacobsen, P.; Lynggard, F.; Levin, M.; Nielsen, G. D.; Wolkoff, P.; Ebbehøj, N. E.; Larsen, S. T.

2014-01-01

Context Coating products are widely used for making surfaces water and dirt repellent. However, on several occasions the use of these products has been associated with lung toxicity. Objective In the present study, we evaluated the toxic effects of an aerosolized tile-coating product. Methods Thirty-nine persons, who reported respiratory and systemic symptoms following exposure to the tile-coating product, were clinically examined. The product was analysed chemically and furthermore, the exposure scenario was reconstructed using a climate chamber and the toxicological properties of the product were studied using in vivo and by in vitro surfactometry. Results The symptoms developed within few hours and included coughing, tachypnoea, chest pain, general malaise and fever. The physical examination revealed perihilar lung infiltrates on chest radiograph and reduced blood oxygen saturation. The acute symptoms resolved gradually within 1–3 days and no delayed symptoms were observed. By means of mass spectrometry and X-ray spectroscopy, it was shown that the product contained non-fluorinated alkylsiloxanes. The exposure conditions in the supermarket were reconstructed under controlled conditions in a climate chamber and particle and gas exposure levels were monitored over time allowing estimation of human exposure levels. Mice exposed to the product developed symptoms of acute pulmonary toxicity in a concentration-and time-dependent manner. The symptoms of acute pulmonary toxicity likely resulted from inhibition of the pulmonary surfactant function as demonstrated by in vitro surfactometry. Among these patients only a partial association between the level of exposure and the degree of respiratory symptoms was observed, which could be because of a high inter-individual difference in sensitivity and time-dependent changes in the chemical composition of the aerosol. Conclusion Workers need to cautiously apply surface coating products because the contents can be highly toxic through inhalation, and the aerosols can disperse to locations remote from the worksite and affect bystanders. PMID:24815546

Ameliorating Impact of Prophylactic Intranasal Oxytocin on Signs of Fear in a Rat Model of Traumatic Stress

PubMed Central

Renicker, Micah D.; Cysewski, Nicholas; Palmer, Samuel; Nakonechnyy, Dmytro; Keef, Andrew; Thomas, Morgan; Magori, Krisztian; Daberkow, David P.

2018-01-01

Oxytocin treatment reduces signs of long-term emotional stress after exposure to trauma; however, little is known about the potential protective effects of oxytocin treatment on behavioral and physiological changes associated with extreme stress exposure. The objective of this study was to investigate oxytocin treatment as a prophylactic measure against rat signs of fear. Two separate experiments were conducted in which the time of intranasal oxytocin administration differed. Intranasal oxytocin (1.0 μg/kg) was administered 5 min after daily exposure to foot shock in Experiment #1 and 1 h before foot shock in Experiment #2. In Experiment #1, possible massage-evoked oxytocin release (5 min after foot shock) was also investigated. In both experiments, a contextual fear conditioning procedure was employed in which stress was induced via inescapable foot shock (3 days, 40 shocks/day, 8 mA/shock) in a fear conditioning chamber. Male Sprague-Dawley rats (n = 24) were divided into four groups (n = 6, per group) for each experiment. Experiment #1 groups: Control Exp#1 (intranasal saline and no foot shock); Stress Exp#1 (intranasal saline 5 min after foot shock); Massage+Stress Exp#1 (massage-like stroking and intranasal saline 5 min after foot shock); Oxytocin+Stress Exp#1 (intranasal oxytocin 5 min after foot shock). Experiment #2 groups: Control Exp#2 (intranasal saline and no foot shock); Stress Exp#2 (intranasal saline 1 h before foot shock); Oxytocin Exp#2 (intranasal oxytocin and no foot shock); Oxytocin+Stress Exp#2 (intranasal oxytocin 1 h before foot shock). One week after fear conditioning (and other treatments), rats were independently evaluated for behavioral signs of fear. Two weeks after conditioning, physiological signs of fear were also assessed (Experiment #1). Relative to controls, rats treated with intranasal oxytocin 5 min after daily foot shock sessions exhibited significantly less immobility upon re-exposure to the shock chamber and attenuated physiological responses related to fear (e.g., elevated heart rate and blood pressure). Furthermore, intranasal oxytocin treatment given 1 h before daily foot shock sessions significantly decreased immobility and defecation upon re-exposure to the shock chamber, relative to controls. The results of this study suggest that prophylactic intranasal oxytocin, administered contemporaneously with aversive stimuli, mitigates behavioral and physiological responses associated with traumatic stress. PMID:29892216

Tobacco smoke aging in the presence of ozone: A room-sized chamber study

NASA Astrophysics Data System (ADS)

Petrick, Lauren M.; Sleiman, Mohamad; Dubowski, Yael; Gundel, Lara A.; Destaillats, Hugo

2011-09-01

Exposure to tobacco pollutants that linger indoors after smoking has taken place ( thirdhand smoke, THS) can occur over extended periods and is modulated by chemical processes involving atmospheric reactive species. This study investigates the role of ozone and indoor surfaces in chemical transformations of tobacco smoke residues. Gas and particle constituents of secondhand smoke (SHS) as well as sorbed SHS on chamber internal walls and model materials (cotton, paper, and gypsum wallboard) were characterized during aging. After smoldering 10 cigarettes in a 24-m 3 room size chamber, gas-phase nicotine was rapidly removed by sorption to chamber surfaces, and subsequently re-emitted during ventilation with clean air to a level of ˜10% that during the smoking phase. During chamber ventilation in the presence of ozone (180 ppb), ozone decayed at a rate of 5.6 h -1 and coincided with a factor of 5 less nicotine sorbed to wallboard. In the presence of ozone, no gas phase nicotine was detected as a result of re-emission, and higher concentrations of nicotine oxidation products were observed than when ventilation was performed with ozone-free air. Analysis of the model surfaces showed that heterogeneous nicotine-ozone reaction was faster on paper than cotton, and both were faster than on wallboard. However, wallboard played a dominant role in ozone-initiated reaction in the chamber due to its large total geometric surface area and sink potential compared to the other substrates. This study is the first to show in a room-sized environmental chamber that the heterogeneous ozone chemistry of sorbed nicotine generates THS constituents of concern, as observed previously in bench-top studies. In addition to the main oxidation products (cotinine, myosmine and N-methyl formamide), nicotine-1-oxide was detected for the first time.

Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress

PubMed Central

Lane, Whitney O.; Jantzen, Alexandra E.; Carlon, Tim A.; Jamiolkowski, Ryan M.; Grenet, Justin E.; Ley, Melissa M.; Haseltine, Justin M.; Galinat, Lauren J.; Lin, Fu-Hsiung; Allen, Jason D.; Truskey, George A.; Achneck, Hardean E.

2012-01-01

The overall goal of this method is to describe a technique to subject adherent cells to laminar flow conditions and evaluate their response to well quantifiable fluid shear stresses1. Our flow chamber design and flow circuit (Fig. 1) contains a transparent viewing region that enables testing of cell adhesion and imaging of cell morphology immediately before flow (Fig. 11A, B), at various time points during flow (Fig. 11C), and after flow (Fig. 11D). These experiments are illustrated with human umbilical cord blood-derived endothelial progenitor cells (EPCs) and porcine EPCs2,3. This method is also applicable to other adherent cell types, e.g. smooth muscle cells (SMCs) or fibroblasts. The chamber and all parts of the circuit are easily sterilized with steam autoclaving. In contrast to other chambers, e.g. microfluidic chambers, large numbers of cells (> 1 million depending on cell size) can be recovered after the flow experiment under sterile conditions for cell culture or other experiments, e.g. DNA or RNA extraction, or immunohistochemistry (Fig. 11E), or scanning electron microscopy5. The shear stress can be adjusted by varying the flow rate of the perfusate, the fluid viscosity, or the channel height and width. The latter can reduce fluid volume or cell needs while ensuring that one-dimensional flow is maintained. It is not necessary to measure chamber height between experiments, since the chamber height does not depend on the use of gaskets, which greatly increases the ease of multiple experiments. Furthermore, the circuit design easily enables the collection of perfusate samples for analysis and/or quantification of metabolites secreted by cells under fluid shear stress exposure, e.g. nitric oxide (Fig. 12)6. PMID:22297325

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

Paik, Samuel Y.; Epperson, Patrick M.; Kasper, Kenneth M.

Here, this article presents air and surface sampling data collected over the first two years since beryllium was introduced as a target material at the National Ignition Facility. Over this time, 101 experiments with beryllium-containing targets were executed. The data provides an assessment of current conditions in the facility and a baseline for future impacts as new, reduced regulatory limits for beryllium are being proposed by both the Occupational Safety and Health Administration and Department of Energy. This study also investigates how beryllium deposits onto exposed surfaces as a result of x-ray vaporization and the effectiveness of simple decontamination measuresmore » in reducing the amount of removable beryllium from a surface. Based on 1,961 surface wipe samples collected from entrant components (equipment directly exposed to target debris) and their surrounding work areas during routine reconfiguration activities, only one result was above the beryllium release limit of 0.2 µg/100 cm 2 and 27 results were above the analytical reporting limit of 0.01 µg/100 cm 2, for a beryllium detection rate of 1.4%. Surface wipe samples collected from the internal walls of the NIF target chamber, however, showed higher levels of beryllium, with beryllium detected on 73% and 87% of the samples during the first and second target chamber entries (performed annually), respectively, with 23% of the samples above the beryllium release limit during the second target chamber entry. The analysis of a target chamber wall panel exposed during the first 30 beryllium-containing experiments (cumulatively) indicated that 87% of the beryllium contamination remains fixed onto the surface after wet wiping the surface and 92% of the non-fixed contamination was removed by decontaminating the surface using a dry wipe followed by a wet wipe. Personal airborne exposures assessed during access to entrant components and during target chamber entry indicated that airborne beryllium was not present in workers' breathing zones. Finally, all the data thus far have shown that beryllium has been effectively managed to prevent exposures to workers during routine and non-routine work.« less

Exposure-Relevant Ozone Chemistry in Occupied Spaces

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

Coleman, Beverly Kaye

2009-04-01

Ozone, an ambient pollutant, is transformed into other airborne pollutants in the indoor environment. In this dissertation, the type and amount of byproducts that result from ozone reactions with common indoor surfaces, surface residues, and vapors were determined, pollutant concentrations were related to occupant exposure, and frameworks were developed to predict byproduct concentrations under various indoor conditions. In Chapter 2, an analysis is presented of secondary organic aerosol formation from the reaction of ozone with gas-phase, terpene-containing consumer products in small chamber experiments under conditions relevant for residential and commercial buildings. The full particle size distribution was continuously monitored, andmore » ultrafine and fine particle concentrations were in the range of 10 to>300 mu g m -3. Particle nucleation and growth dynamics were characterized.Chapter 3 presents an investigation of ozone reactions with aircraft cabin surfaces including carpet, seat fabric, plastics, and laundered and worn clothing fabric. Small chamber experiments were used to determine ozone deposition velocities, ozone reaction probabilities, byproduct emission rates, and byproduct yields for each surface category. The most commonly detected byproducts included C1?C10 saturated aldehydes and skin oil oxidation products. For all materials, emission rates were higher with ozone than without. Experimental results were used to predict byproduct exposure in the cabin and compare to other environments. Byproduct levels are predicted to be similar to ozone levels in the cabin, which have been found to be tens to low hundreds of ppb in the absence of an ozone converter. In Chapter 4, a model is presented that predicts ozone uptake by and byproduct emission from residual chemicals on surfaces. The effects of input parameters (residue surface concentration, ozone concentration, reactivity of the residue and the surface, near-surface airflow conditions, and byproduct yield) were explored. In Chapter 5, the reaction of ozone with permethrin, a residual insecticide used in aircraft cabins, to form phosgene is investigated. A derivatization technique was developed to detect phosgene at low levels, and chamber experiments were conducted with permethrin-coated cabin materials. It was determined that phosgene formation, if it occurs in the aircraft cabin, is not likely to exceed the relevant, health-based phosgene exposure guidelines.« less

Investigation of a sterilization system using active oxygen species generated by ultraviolet irradiation.

PubMed

Yoshino, Kiyoshi; Matsumoto, Hiroyuki; Iwasaki, Tatsuyuki; Kinoshita, Shinobu; Noda, Kazutoshi; Oya, Kei; Iwamori, Satoru

2015-01-01

We have been investigating an advanced sterilization system that employs active oxygen species (AOS). We designed the sterilization equipment, including an evacuation system, which generates AOS from pure oxygen gas using ultraviolet irradiation, in order to study the conditions necessary for sterilization in the system's chamber. Using Geobachillus stearothermophilus spores (10(6) CFU) in a sterile bag as a biological indicator (BI) in the chamber of the AOS sterilization apparatus, we examined the viability of the BI as a function of exposure time, assessing the role of the decompression level in the sterilization performance. We found that the survival curves showed exponential reduction, and that the decompression level did not exert a significant influence on the survival curve. Subsequently, we investigated the sterilization effect as influenced by the spatial and environmental temperature variation throughout the chamber, and found that the sterilization effect varied with position, due to the varying environmental temperature in the respective areas. We confirmed that temperature is one of the most important factors influencing sterilization in the chamber, and estimated the temperature effect on the distribution of atomic oxygen concentration, using the quartz crystal microbalance (QCM) method with fluorocarbon thin film prepared by radio frequency sputtering.

Workplace exposure and release of ultrafine particles during atmospheric plasma spraying in the ceramic industry.

PubMed

Viana, M; Fonseca, A S; Querol, X; López-Lilao, A; Carpio, P; Salmatonidis, A; Monfort, E

2017-12-01

Atmospheric plasma spraying (APS) is a frequently used technique to produce enhanced-property coatings for different materials in the ceramic industry. This work aimed to characterise and quantify the impact of APS on workplace exposure to airborne particles, with a focus on ultrafine particles (UFPs, <100nm) and nanoparticles (<50nm). Particle number, mass concentrations, alveolar lung deposited surface area concentration, and size distributions, in the range 10nm-20μm were simultaneously monitored at the emission source, in the potential worker breathing zone, and in outdoor air. Different input materials (known as feedstock) were tested: (a) micron-sized powders, and (b) suspensions containing submicron- or nano-sized particles. Results evidenced significantly high UFP concentrations (up to 3.3×10 6 /cm 3 ) inside the spraying chamber, which impacted exposure concentrations in the worker area outside the spraying chamber (up to 8.3×10 5 /cm 3 ). Environmental release of UFPs was also detected (3.9×10 5 /cm 3 , outside the exhaust tube). Engineered nanoparticle (ENP) release to workplace air was also evidenced by TEM microscopy. UFP emissions were detected during the application of both micron-sized powder and suspensions containing submicron- or nano-sized particles, thus suggesting that emissions were process- (and not material-) dependent. An effective risk prevention protocol was implemented, which resulted in a reduction of UFP exposure in the worker area. These findings demonstrate the potential risk of occupational exposure to UFPs during atmospheric plasma spraying, and raise the need for further research on UFP formation mechanisms in high-energy industrial processes. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Adverse effect of diesel engine produced particulate matter on various stone types and concrete: a laboratory exposure experiment

NASA Astrophysics Data System (ADS)

Farkas, Orsolya; Szabados, György; Antal, Ákos; Török, Ákos

2015-04-01

The effect of particulate matter on construction materials have been studied under laboratory conditions. For testing the adverse effects of diesel soot and particulate matter on stone and concrete a small scale laboratory exposure chamber was constructed. Blocks of 9 different stone types and concrete was placed in the chamber and an exhaust pipe of diesel engine was diverted into the system. Tested stones included: porous limestone, cemented non-porous limestone, travertine, marble, rhyolite tuff, andesite and granite. The engine was operated for 10 hours and the produced particulate matter was diverted directly to the surface of the material specimens of 3 cm in diameter each. Working parameters of the engine were controlled; the composition of the exhaust gas, smoke value and temperature were continuously measured during the test. Test specimens were documented and analysed prior to exposure and after the exposure test. Parameters such colorimetric values, weight, surface properties, mineralogical compositions of the test specimens were recorded. The working temperature was in the order of 300°C-320°C. The gas concentration was in ppm as follows: 157 CO; 5.98 CO2, 34.3 THC; 463 NOx; 408 NO; 12.88 O2. Our tests have demonstrated that significant amount of particulate matter was deposited on construction materials even at a short period of time; however the exposure was very intense. It also indicates that that the interaction of particulate matter and aerosol compounds with construction materials in urban areas causes rapid decay and has an adverse effect not only on human health but also on built structures.

Measurements of dermal uptake of nicotine directly from air and clothing.

PubMed

Bekö, G; Morrison, G; Weschler, C J; Koch, H M; Pälmke, C; Salthammer, T; Schripp, T; Toftum, J; Clausen, G

2017-03-01

In this preliminary study, we have investigated whether dermal uptake of nicotine directly from air or indirectly from clothing can be a meaningful exposure pathway. Two participants wearing only shorts and a third participant wearing clean cotton clothes were exposed to environmental tobacco smoke (ETS), generated by mechanically "smoking" cigarettes, for three hours in a chamber while breathing clean air from head-enveloping hoods. The average nicotine concentration (420 μg/m 3 ) was comparable to the highest levels reported for smoking sections of pubs. Urine samples were collected immediately before exposure and 60 hour post-exposure for bare-skinned participants. For the clothed participant, post-exposure urine samples were collected for 24 hour. This participant then entered the chamber for another three-hour exposure wearing a hood and clothes, including a shirt that had been exposed for five days to elevated nicotine levels. The urine samples were analyzed for nicotine and two metabolites-cotinine and 3OH-cotinine. Peak urinary cotinine and 3OH-cotinine concentrations for the bare-skinned participants were comparable to levels measured among non-smokers in hospitality environments before smoking bans. The amount of dermally absorbed nicotine for each bare-skinned participant was conservatively estimated at 570 μg, but may have been larger. For the participant wearing clean clothes, uptake was ~20 μg, and while wearing a shirt previously exposed to nicotine, uptake was ~80 μg. This study demonstrates meaningful dermal uptake of nicotine directly from air or from nicotine-exposed clothes. The findings are especially relevant for children in homes with smoking or vaping. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Inhaled delivery of Δ(9)-tetrahydrocannabinol (THC) to rats by e-cigarette vapor technology.

PubMed

Nguyen, Jacques D; Aarde, Shawn M; Vandewater, Sophia A; Grant, Yanabel; Stouffer, David G; Parsons, Loren H; Cole, Maury; Taffe, Michael A

2016-10-01

Most human Δ(9)-tetrahydrocannabinol (THC) use is via inhalation, and yet few animal studies of inhalation exposure are available. Popularization of non-combusted methods for the inhalation of psychoactive drugs (Volcano(®), e-cigarettes) further stimulates a need for rodent models of this route of administration. This study was designed to develop and validate a rodent chamber suitable for controlled exposure to vaporized THC in a propylene glycol vehicle, using an e-cigarette delivery system adapted to standard size, sealed rat housing chambers. The in vivo efficacy of inhaled THC was validated using radiotelemetry to assess body temperature and locomotor responses, a tail-flick assay for nociception and plasma analysis to verify exposure levels. Hypothermic responses to inhaled THC in male rats depended on the duration of exposure and the concentration of THC in the vehicle. The temperature nadir was reached after ∼40 min of exposure, was of comparable magnitude (∼3 °Celsius) to that produced by 20 mg/kg THC, i.p. and resolved within 3 h (compared with a 6 h time course following i.p. THC). Female rats were more sensitive to hypothermic effects of 30 min of lower-dose THC inhalation. Male rat tail-flick latency was increased by THC vapor inhalation; this effect was blocked by SR141716 pretreatment. The plasma THC concentration after 30 min of inhalation was similar to that produced by 10 mg/kg THC i.p. This approach is flexible, robust and effective for use in laboratory rats and will be of increasing utility as users continue to adopt "vaping" for the administration of cannabis. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antioxidant responses following active and passive smoking of tobacco and electronic cigarettes.

PubMed

Poulianiti, Konstantina; Karatzaferi, Christina; Flouris, Andreas D; Fatouros, Ioannis G; Koutedakis, Yiannis; Jamurtas, Athanasios Z

2016-07-01

It has been indicated that acute active and passive tobacco cigarette smoking may cause changes on redox status balance that may result in significant pathologies. However, no study has evaluated the effects of active and passive e-cigarette smoking on redox status of consumers. To examine the acute effects of active and passive e-cigarette and tobacco cigarette smoking on selected redox status markers. Using a randomized single-blind crossover design, 30 participants (15 smokers and 15 nonsmokers) were exposed to three different experimental conditions. Smokers underwent a control session, an active tobacco cigarette smoking session (smoked 2 cigarettes within 30-min) and an active e-cigarette smoking session (smoked a pre-determined number of puffs within 30-min using a liquid with 11 ng/ml nicotine). Similarly, nonsmokers underwent a control session, a passive tobacco cigarette smoking session (exposure of 1 h to 23 ± 1 ppm of CO in a 60 m(3) environmental chamber) and a passive e-cigarette smoking session (exposure of 1 h to air enriched with pre- determined number of puffs in a 60 m(3) environmental chamber). Total antioxidant capacity (TAC), catalase activity (CAT) and reduced glutathione (GSH) were assessed in participants' blood prior to, immediately after, and 1-h post-exposure. TAC, CAT and GSH remained similar to baseline levels immediately after and 1-h-post exposure (p > 0.05) in all trials. Tobacco and e-cigarette smoking exposure do not acutely alter the response of the antioxidant system, neither under active nor passive smoking conditions. Overall, there is not distinction between tobacco and e-cigarette active and passive smoking effects on specific redox status indices.

Experimental and numerical study on particle distribution in a two-zone chamber

NASA Astrophysics Data System (ADS)

Lai, Alvin C. K.; Wang, K.; Chen, F. Z.

Better understanding of aerosol dynamics is an important step for improving personal exposure assessments in indoor environments. Although the limitation of the assumptions in a well-mixed model is well known, there has been very little research reported in the published literature on the discrepancy of exposure assessments between numerical models which take account of gravitational effects and the well-mixed model. A new Eulerian-type drift-flux model has been developed to simulate particle dispersion and personal exposure in a two-zone geometry, which accounts for the drift velocity resulting from gravitational settling and diffusion. To validate the numerical model, a small-scale chamber was fabricated. The airflow characteristics and particle concentrations were measured by a phase Doppler Anemometer. Both simulated airflow and concentration profiles agree well with the experimental results. A strong inhomogeneous concentration was observed experimentally for 10 μm aerosols. The computational model was further applied to study a simple hypothetical, yet more realistic scenario. The aim was to explore different levels of exposure predicted by the new model and the well-mixed model. Aerosols are initially uniformly distributed in one zone and subsequently transported and dispersed to an adjacent zone through an opening. Owing to the significant difference in the rates of transport and dispersion between aerosols and gases, inferred from the results, the well-mixed model tends to overpredict the concentration in the source zone, and under-predict the concentration in the exposed zone. The results are very useful to illustrate that the well-mixed assumption must be applied cautiously for exposure assessments as such an ideal condition may not be applied for coarse particles.

Impact of short-term heat stress on physiological responses and expression profile of HSPs in Barbari goats

NASA Astrophysics Data System (ADS)

Dangi, Satyaveer Singh; Gupta, Mahesh; Nagar, Vimla; Yadav, Vijay Pratap; Dangi, Saroj K.; Shankar, Om; Chouhan, Vikrant Singh; Kumar, Puneet; Singh, Gyanendra; Sarkar, Mihir

2014-12-01

Six, nonpregnant, Barbari goats aged 4-5 years were selected for the study. For the first 6 days, the animals were kept in psychrometric chamber at thermoneutral temperature for 6 h each day to make them acclimated to climatic chamber. On the 7th day, the animals were exposed to 41 °C temperature for 3 h and then to 45 °C for the next 3 h. Cardinal physiological responses were measured, and blood samples (3 ml) were collected at 1-h interval during the heat exposure period and then once after 6 h of the heat exposure. The rectal temperature (RT) and respiratory rate (RR) increased significantly ( P < 0.05) during the heat exposure compared to pre- and postexposure. The relative messenger RNA (mRNA) expression of heat shock protein (HSP)60, HSP70, and HSP90 increased significantly ( P < 0.05) within 1 h after exposure to heat stress at 41 and 45 °C and decreased significantly ( P < 0.05) in next 2 h but remain significantly ( P < 0.05) elevated from preexposure. HSP105/110 relative mRNA expression level remained unchanged during the first 4 h, and thereafter, it increased significantly ( P < 0.05) and reached the peak at 6 h. Relative protein expression pattern of HSPs during exposure to heat stress showed similar trend as observed for the relative mRNA expression. Given the response sensitivity and intensity of HSP genes to environmental stresses, HSP70 was found to be the most sensitive to temperature fluctuation, and it could be used as an important molecular biomarker to heat stress in animals.

Fucus and Ascophyllum seaweeds are significant contributors to coastal iodine emissions

NASA Astrophysics Data System (ADS)

Huang, R.-J.; Thorenz, U. R.; Kundel, M.; Venables, D. S.; Ceburnis, D.; Chen, J.; Vogel, A. L.; Küpper, F. C.; Smyth, P. P. A.; Berresheim, H.; O'Dowd, C. D.; Hoffmann, T.

2012-09-01

Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. I2 mixing ratios from 104 to 393 ppt were found above the macroalgae beds, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically-driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds increased with exposure time - after 6 h exposure to ambient air the mixing ratios were one order of magnitude higher than those initially present. This contrasts with the emission characteristics of Laminaria digitata, where most I2 was emitted within the first half hour of exposure. Discrete in situ measurements (off-line) of I2 emission from ambient air-exposed chamber experiments of L. digitata, A. nodosum and F. vesiculosus substantially supported the field observations. Further online and time-resolved measurements of the I2 emission from O3-exposed macroalgal experiments in chamber confirmed the distinct I2 emission characteristics of A. nodosum and F. vesiculosus compared to that of L. digitata. The emission rates of A. nodosum and F. vesiculosus were comparable to or even higher than L. digitata after the initial exposure period of ~20-30 min. We suggest that A. nodosum and F. vesiculosus may provide an unaccounted and important source of photolabile iodine in the coastal boundary layer and that their impact on photochemistry and coastal new particle formation should be reevaluated in light of their longer exposure at low-tide and their widespread distribution.

Controlled exposure of volunteers with chronic obstructive pulmonary disease to sulfur dioxide

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

Linn, W.S.; Fischer, D.A.; Shamoo, D.A.

1985-08-01

Twenty-four volunteers with chronic obstructive pulmonary disease (COPD) were exposed to sulfur dioxide (SO/sub 2/) at 0, 0.4, and 0.8 ppm in an environmental control chamber. Exposures lasted 1 hr and included two 15-min exercise periods (mean exercise ventilation rate 18 liter/min). Pulmonary mechanical function was evaluated before exposures, after initial exercise, and at the end of exposure. Blood oxygenation was measured by ear oximetry before exposure and during the second exercise period. Symptoms were recorded throughout exposure periods and for 1 week afterward. No statistically significant changes in physiology or symptoms could be attributed to SO/sub 2/ exposure. Oldermore » adults with COPD seem less reactive to a given concentration of SO/sub 2/ than heavily exercising young adult asthmatics. This may be due to lower ventilation rates (i.e., lower SO/sub 2/ dose rates) and/or to lower airway reactivity in the COPD group.« less

Cholinesterase activity in black-crowned night-herons exposed to fenthion-treated water

USGS Publications Warehouse

Smith, G.J.; Spann, J.W.; Hill, E.F.

1986-01-01

Fenthion, (O,O-Dimethyl O-(3-methyl-4-(methylthio)phenyl) phosphorothioate), a widely used mosquito control agent, has caused wildlife mortality. To simulate a shallow wetland environment, an exposure chamber was used containing water treated with fenthion at 1 and 10 times the field application rate of 112 g active ingredient (AI)/ha. This system permitted an evaluation of exposure routes and the effects of fenthion in a representative species of wading bird, the black-crowned night-heron (Nycticorax nycticorax). The results suggested that herons received only a dermal exposure, and that their brain acetylcholinesterase activity was not significantly inhibited. In contrast, however, plasma butyrylcholinesterase activity was inhibited, suggesting the herons were exposed to the insecticide. The application rates and types of exposures were not life-threatening in this species.

24 and 48 h allergen exposure in patch testing. Comparative study with 11 common contact allergens and NiCl2.

PubMed

Kalimo, K; Lammintausta, K

1984-01-01

Patch test reactions to 11 common contact allergens were studied after 24 h and 48 h occlusion with Finn Chambers in 390 patients. Concordant allergic results were found in 96 cases (74%). In 22 patients (17%), the reaction was positive only after 48 h and in 11 cases (8.5%) only after 24 h exposure. Most of the discordant reactions were to nickel, cobalt, neomycin, formaldehyde and perfume mix. Irritant reactions were found in 55 cases, the majority occurring after 48 h occlusion. Nickel chloride tested in parallel with 48 h exposure lead to more positive allergic and toxic reactions than nickel sulphate.

Effects of whole-body cryotherapy duration on thermal and cardio-vascular response.

PubMed

Fonda, Borut; De Nardi, Massimo; Sarabon, Nejc

2014-05-01

Whole-body cryotherapy (WBC) is the exposure of minimally dressed participants to very cold air, either in a specially designed chamber (cryo-chamber) or cabin (cryo-cabin), for a short period of time. Practitioners are vague when it comes to recommendations on the duration of a single session. Recommended exposure for cryo-chamber is 150s, but no empirically based recommendations are available for a cryo-cabin. Therefore the aim of this study was to examine thermal and cardio-vascular responses after 90, 120, 150 and 180s of WBC in a cryo-cabin. Our hypothesis was that skin temperature would be significantly lower after longer exposers. Twelve male participants (age 23.9±4.2 years) completed four WBC of different durations (90, 120, 150 and 180s) in a cryo-cabin. Thermal response, heart rate and blood pressure were measured prior, immediately after, 5min after and 30min after the session. Skin temperature differed significantly among different durations, except between 150 and 180s. There was no significant difference in heart rate and blood pressure. Thermal discomfort during a single session displayed a linear increase throughout the whole session. Our results indicate that practitioners and clinicians using cryo-cabin for WBC do not need to perform sessions longer than 150s. We have shown that longer sessions do not substantially affect thermal and cardio-vascular response, but do increase thermal discomfort. Copyright © 2014 Elsevier Ltd. All rights reserved.

The study of the proteome of healthy human blood plasma under conditions of long-term confinement in an isolation chamber.

PubMed

Trifonova, O P; Pastushkova, L Kh; Samenkova, N F; Chernobrovkin, A L; Karuzina, I I; Lisitsa, A V; Larina, I M

2013-05-01

We identified changes in the proteome of healthy human blood plasma caused by exposure to 105-day confinement in an isolation chamber. After removal of major proteins and concentration of minor proteins, plasma fractions were analyzed by two-dimensional electrophoresis followed by identification of significantly different protein spots by mass spectrometric analysis of the peptide fragments. The levels of α- and β-chains of fibrinogen, a fragment of complement factor C4, apolipoproteins AI and E, plasminogen factor C1 complement, and immunoglobulin M changed in participants during the isolation period. These changes probably reflect the adaptive response to altered conditions of life.

FOLIAR N RESPONSE OF PONDEROSA PINE SEEDLINGS TO ELEVATED CO2 AND O3

EPA Science Inventory

Interactions between needle N status and exposure to combined CO2 and O3 stresses were studied in Pinus ponderosa seedlings. The seedlings were grown for three years (April 1998 through March 2001) in outdoor chambers in native soils from eastern Oregon, and exposed to ambient ...

An accelerated exposure and testing apparatus for building joint sealants

NASA Astrophysics Data System (ADS)

White, C. C.; Hunston, D. L.; Tan, K. T.; Hettenhouser, J.; Garver, J. D.

2013-09-01

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise movement control. The reliability and effectiveness of the apparatus were demonstrated on a model sealant material. The results clearly show that this apparatus provides an excellent platform to study the long-term durability of building joint sealants.

An accelerated exposure and testing apparatus for building joint sealants.

PubMed

White, C C; Hunston, D L; Tan, K T; Hettenhouser, J; Garver, J D

2013-09-01

The design, fabrication, and implementation of a computer-controlled exposure and testing apparatus for building joint sealants are described in this paper. This apparatus is unique in its ability to independently control and monitor temperature, relative humidity, ultraviolet (UV) radiation, and mechanical deformation. Each of these environmental factors can be controlled precisely over a wide range of conditions during periods of a month or more. Moreover, as controlled mechanical deformations can be generated, in situ mechanical characterization tests can be performed without removing specimens from the chamber. Temperature and humidity were controlled during our experiments via a precision temperature regulator and proportional mixing of dry and moisture-saturated air; while highly uniform UV radiation was attained by attaching the chamber to an integrating sphere-based radiation source. A computer-controlled stepper motor and a transmission system were used to provide precise movement control. The reliability and effectiveness of the apparatus were demonstrated on a model sealant material. The results clearly show that this apparatus provides an excellent platform to study the long-term durability of building joint sealants.

Relative toxicity of products of pyrolysis and combustion of polymeric materials using various test conditions

NASA Technical Reports Server (NTRS)

Hilado, C. J.

1976-01-01

Relative toxicity data for a large number of natural and synthetic polymeric materials are presented which were obtained by 11 pyrolysis and three flaming-combustion test methods. The materials tested include flexible and rigid polyurethane foams, different kinds of fabrics and woods, and a variety of commodity polymers such as polyethylene. Animal exposure chambers of different volumes containing mice, rats, or rabbits were used in the tests, which were performed over the temperature range from ambient to 800 C with and without air flow or recirculation. The test results are found to be sensitive to such variables as exposure mode, temperature, air flow and dilution, material concentration, and animal species, but relative toxicity rankings appear to be similar for many methods and materials. It is concluded that times to incapacitance and to death provide a more suitable basis for relative toxicity rankings than percent mortality alone, that temperature is the most important variable in the tests reported, and that variables such as chamber volume and animal species may not significantly affect the rankings.

Freshwater in situ toxicity testing: Daphnia magna, Ceriodaphnia dubia, Pimephales promelas, Hyalella azteca and Chironomus tentans

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

Burton, G.A. Jr.

The use of traditional laboratory toxicity test species in field exposures have proven to be a valuable assessment tool for monitoring effluent, water, sediment and storm water quality. Mimicking fluctuating exposures of stressors with associated interactions with differing physico-chemical variables is difficult. In situ exposures are conducted for similar time periods measuring similar response endpoints as in more traditional laboratory tests. However, organisms are transferred to the field and exposed in various types of test chambers. The author has observed responses which are similar and which are significantly different from simultaneous laboratory exposures. Temperature, dissolved oxygen, suspended solids, natural light,more » flow, and predation may affect in situ responses, but are often removed from laboratory exposures. The strengths and weaknesses observed with these test systems over the past few years will be reviewed.« less

Dark Matter Search Results from the PICO-60 C$$_3$$F$$_8$$ Bubble Chamber

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

Amole, C.; et al.

2017-02-24

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of Cmore » $$_3$$F$$_8$$ located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C$$_3$$F$$_8$$ exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than 1 event per month. A blind analysis of an efficiency-corrected 1167-kg-day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the WIMP-proton spin-dependent cross section at 3.4 $$\\times$$ 10$$^{-41}$$ cm$^2$ for a 30-GeV$$\\thinspace$$c$$^{-2}$$ WIMP, more than one order of magnitude improvement from previous PICO results.« less

TU-FG-209-09: Mathematical Estimation and Experimental Measurement of Patient Free-In-Air Skin Entrance Exposure During a Panoramic Dental X-Ray Procedure

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

Errico, A; Behrman, R; Li, B

Purpose: To develop a simple mathematical model for estimating the patient free-in-air skin entrance exposure (SEE) during a panoramic dental x-ray that does not require the use of a head phantom. This eliminates issues associated with phantom centering and the mounting of a detector on the phantom for routine QC testing. Methods: We used a Sirona Orthophos XG panoramic radiographic unit and a Radcal Accu-Gold system for this study. A solid state detector was attached over the slit of the Orthophos’ sensor with the help of a custom-built jig. A single measurement of the free-in-air exposure at this position wasmore » taken over a full panoramic scan. A mathematical model for estimating the SEE was developed based upon this measurement, the system geometry, x-ray field beam width, and x-ray sweep angle. To validate the model, patient geometry was simulated by a 16 cm diameter PMMA CTDI phantom centered at the machine’s isocenter. Measurements taken on the phantom’s surface were made using a solid state detector with lead backing, an ion chamber, and the ion chamber with the phantom wrapped in lead to mitigate backscatter. Measurements were taken near the start position of the tube and at 90 degrees from the start position. Results: Using the solid state detector, the average SEE was 23.5+/−0.02 mR and 55.5+/−0.08 mR at 64 kVp and 73 kVp, respectively. With the lead-wrapping, the measurements from the ion chamber matched those of the solid state detector to within 0.1%. Preliminary results gave the difference between the mathematical model and the phantom measurements to be approximately 5% at both kVps. Conclusion: Reasonable estimates of patient SEE for panoramic dental radiography can be made using a simple mathematical model without the need for a head phantom.« less

Laboratory Measurements of Oxygen Gas Release from Basaltic Minerals Exposed to UV- Radiation: Implications for the Viking Gas Exchange Experiments

NASA Astrophysics Data System (ADS)

Hurowitz, J. A.; Yen, A. S.

2007-12-01

The biology experiments onboard the Viking Landers determined that the Martian soils at Chryse and Utopia Planitia contain an unknown chemical compound of a highly oxidizing nature. The Gas Exchange Experiments (GEx) demonstrated that the humidification of a 1-cc Martian soil sample resulted in the production of as much as 790 nanomoles of oxygen gas. Yen et al. (2000) have provided experimental evidence that superoxide radicals can be generated on plagioclase feldspar (labradorite) grain surfaces by exposure to ultraviolet (UV) light in the presence of oxygen gas. Adsorbed superoxide radicals are thought to react readily with water vapor, and produce oxygen gas in quantities sufficient to explain the Viking GEx results. Direct evidence for the formation of oxygen gas, however, was not provided in the experiments of Yen et al (2000). Accordingly, the motivation of this study is to determine whether superoxide radicals adsorbed on labradorite surfaces are capable of producing oxygen gas upon exposure to water vapor. We have constructed an experimental apparatus that is capable of monitoring oxygen gas release from basaltic mineral powders that have been exposed to UV-radiation under Martian atmospheric pressure conditions. The apparatus consists of a stainless-steel vacuum chamber with a UV- transparent window where sample radiation exposures are performed. The vacuum chamber has multiple valved ports for injection of gases and water vapor. The vacuum chamber is connected via a precision leak valve to a quadrupole mass spectrometer, which measures changes in the composition of the headspace gases over our mineral samples. We will report on the results of our experiments, which are aimed at detecting and quantifying oxygen gas release from UV-exposed basaltic mineral samples using this new experimental facility. These results will further constrain whether superoxide ions adsorbed on mineral surfaces provide a viable explanation for the Viking GEx results, which have been of considerable controversy in the roughly three decades since the measurements were first made.

SU-E-I-60: Validation of An Optically Stimulated Luminescent (OSL) Dosimeter for Use in Output Exposure Control Verification of Mammography Imaging Systems.

PubMed

Ranger, R; Butler, P; Yahnke, C; Valentino, D

2012-06-01

To develop and validate an Optically Stimulated Luminescent (OSL) dosimeter for exposure control verification of x-ray projection mammography imaging systems. The active detection element of the dosimeter is a strip of OSL material 3.0 mm wide, 0.13 mm thick and 30.0 mm long with an overlying aluminum step wedge with thicknesses of 0, 0.2, 0.4 and 0.6 mm Al, encapsulated in a light-tight plastic enclosure with outer dimensions of 10.0 mm wide, 5.4 mm thick, and 54.0 mm long. The dosimeter is used in conjunction with a breast phantom for the purpose of estimating the half-value layer (HVL), entrance surface exposure (ESE), and average glandular dose (AGD) in conventional projection mammography. ESE and HVL were computed based on analysis of exposure profiles obtained from exposed strip dosimeters. The AGD was estimated by multiplying the ESE by the appropriate exposure to dose conversion factor for the thickness and % glandular tissue fraction represented by the phantom and target-filter combination employed. The accuracy and reproducibility of the ESE, HVL and AGD estimates obtained using the dosimeter positioned on the surface of the ACR phantom at the chest wall edge, was evaluated using mammography systems utilizing different imaging receptor technology, i.e. screen-film (SF), computed radiography (CR) and direct radiography (DR) and compared against results obtained using a calibrated ion chamber fitted with a mammography probe. ESE, AGD and HVL results obtained using the OSL mammography QA dosimeter agreed with results obtained using an ion chamber to within 5-10%, depending on the target-filter combination used. Repeat readings were highly consistent with a coefficient of variation = 5%. The OSL mammography QA dosimeter has been shown to effectively estimate ESE, HVL and AGD, demonstrating its usefulness for secondary monitoring of output exposure of mammography imaging systems. © 2012 American Association of Physicists in Medicine.

Comparison of carbon dioxide, argon, and nitrogen for inducing unconsciousness or euthanasia of rats.

PubMed

Sharp, Jody; Azar, Toni; Lawson, David

2006-03-01

We compared CO(2), Ar, and N(2) for inducing unconsciousness and euthanasia of Sprague-Dawley rats. We determined time to unconsciousness and monitored heart rate (HR) and mean arterial blood pressure (MAP) by radiotelemetry to assess stress, recovery after exposure, and time of death. Unconsciousness (mean +/- standard error) occurred 24 +/- 3, 87 +/- 8, and 93 +/- 8 s after short-term exposure to CO(2), Ar, and N(2), respectively. During exposure, CO(2) depressed HR, whereas Ar and N(2) increased HR. Upon removal from the chamber, rats' HR rapidly normalized after CO(2) or N(2) but remained elevated for 60 min after Ar. During exposure, all agents depressed MAP, which returned to resting levels 10 to 50 min after rats' removal from the chamber. For euthanasia, CO(2) at approximately 100% induced unconsciousness in 37 +/- 3 s, increased and then depressed MAP and HR, and caused death at 188 +/- 15 s. CO(2) at approximately 30% induced unconsciousness in 150 +/- 15 s, decreased HR and MAP, and induced death at 440 +/- 9 s. Ar at approximately 100% increased MAP but decreased HR, induced unconsciousness with hyperreflexia at 54 +/- 4 s, and caused death at 197 +/- 20 s. N(2) at approximately 100% decreased MAP but not HR and produced unconsciousness with hyperreflexia at 164 +/- 17 s and death at 426 +/- 28 s. We conclude that CO(2) effectively produced unconsciousness and euthanasia, but we were unable to ascertain distress. Ar also appears effective but produced hyperreflexia and tachycardia. N(2) was ineffective.

[Establishment of heat acclimatization model in rabbits and its pathophysiological characteristics].

PubMed

Wang, Tao; Wang, Jing; Wang, Shang; Li, Pei-Yao; Zhang, Wen-Cheng; Zhao, Xiao-Ling; Wang, Hai

2013-09-01

To establish an effective and stable rabbit heat acclimatization model for the experiment of heat acclimatization mechanisms. Sixteen healthy male rabbits were divided into heat acclimatization group and control group randomly (n = 8). Heat acclimatization (HA) group was kept in simulation chamber with dry bulb temperature of (36 +/- 1) degrees C, wet bulb temperature of (29 +/- 0.5) degrees C, black-bulb temperature of (40 +/- 1.0) degrees C, 100 min/day for 21 days. Control group was kept in the room with temperature of 20 degrees C and relative humidity < 60% during 20 days, then removed into simulation chamber on day 21 to estimate and monitor the rectal temperature together with the heat acclimatization group. Venous blood of control and heat acclimatization group before and after heat exposure on the 1st day, 11th day and 21st day were collected to detect levels of tumor necrosis factor-alpha (TNF-alpha), interleukin 6 (IL-6) and heat shock protein 70 (HSP70) by ELISA analysis. (1) Rectal temperature: There was no significant change in control group during 21 days. In heat acclimatization group, it increased (2.07 +/- 0.43) degrees C after the 1st exposure, and increased (1.78 +/- 0.37) degrees C after the 11th exposure, the range of increasing decreased (0.29 +/- 0.09) degrees C. After the 21st exposure, it increased (1.52 +/- 0.29) degrees C, which was (0.55 +/- 0.14) degrees C lower than that of the 1st (P < 0.05),and (0.53 +/- 0.14) degrees C lower to that of the control group under 1st heat stress (P < 0.05); (2) The level of TNF-alpha after the 1st exposure increased significantly (P < 0.05), but didn't raise along with the exposure times. And fell back to the original level after the 11th and 21st exposure. Compared with control group, the level of IL-6 increased after the 1st, 11th and 21st exposure (P < 0.05), and maintained highly after the 11th and 21st exposure. Compared with the control group, the level of HSP70 increased dramatically with the heat exposure times. Significant increasing of (HSP70) could be detected after the 11th and 21st exposure (P < 0.05), but there was no difference to that of the 1st exposure. Prolonged or repeated exposure to heat stressful environmental conditions can reduce the physiological strain, improve heat tolerance, elicits heat acclimatization.

Testing environment shape differentially modulates baseline and nicotine-induced changes in behavior: Sex differences, hypoactivity, and behavioral sensitization.

PubMed

Illenberger, J M; Mactutus, C F; Booze, R M; Harrod, S B

2018-02-01

In those who use nicotine, the likelihood of dependence, negative health consequences, and failed treatment outcomes differ as a function of gender. Women may be more sensitive to learning processes driven by repeated nicotine exposure that influence conditioned approach and craving. Sex differences in nicotine's influence over overt behaviors (i.e. hypoactivity or behavioral sensitization) can be examined using passive drug administration models in male and female rats. Following repeated intravenous (IV) nicotine injections, behavioral sensitization is enhanced in female rats compared to males. Nonetheless, characteristics of the testing environment also mediate rodent behavior following drug administration. The current experiment used a within-subjects design to determine if nicotine-induced changes in horizontal activity, center entries, and rearing displayed by male and female rats is detected when behavior was recorded in round vs. square chambers. Behaviors were recorded from each group (males-round: n=19; males-square: n=18; females-square: n=19; and females-round: n=19) immediately following IV injection of saline, acute nicotine, and repeated nicotine (0.05mg/kg/injection). Prior to nicotine treatment, sex differences were apparent only in round chambers. Following nicotine administration, the order of magnitude for the chamber that provided enhanced detection of hypoactivity or sensitization was contingent upon both the dependent measure under examination and the animal's biological sex. As such, round and square testing chambers provide different, and sometimes contradictory, accounts of how male and female rats respond to nicotine treatment. It is possible that a central mechanism such as stress or cue sensitivity is impacted by both drug exposure and environment to drive the sex differences observed in the current experiment. Until these complex relations are better understood, experiments considering sex differences in drug responses should balance characteristics of the testing environment to provide a complete interpretation of drug-induced changes to behavior. Copyright © 2018 Elsevier Inc. All rights reserved.

[Modification of the pattern of fatty acids of erythrocytes’ membranes due to the acetone intoxication].

PubMed

Momot, T V; Kushnerova, N F; Rakhmanin, Yu A

Results of the study of the impact of acetone intoxication on the fatty acids pattern of the general lipids of erythrocytes’ membranes in rats are presented. The inhalation exposure of acetone was carried out in the inoculation chamber with the volume of 100 liters. The chamber was designed for the type of B.A. Kurlyandsky with self-contained system of purification and air regeneration and specified parameters of temperature (20-22С) and air humidity. The flow rate of the air and aerosolized acetone passed through the chamber accounted of 10 liters/min. Concentration of acetone in the chamber was sustained at the level of 206 ± 3,9 mg/m that corresponds to maximum permissible concentration for acetone vapor in the air of a working area. The time of exposure was 6 hours per day for 3 weeks in a monotonous mode, excluding weekend, and was based upon specific parameters of environment simulation in industry. The acetone impact was shown to be accompanied by the gain in the quantity of all kinds of saturated fatty acids and the fall of unsaturated fatty acids in general lipids of erythrocytes ’ membranes in rats and in the structure ofphospholipid fractions. In the content of phosphatydilcholine and phosphatydilethanolamine, as a basic structural phospholipids of biological membranes, there was noted the increase in palmitic and stearic acids. In the range offatty acids of the n-6 family the amount of linoleic and arachidonic acids decreased. In the array of fatty acids of the n-3 family the content of linolenic, eicosapentaenoic and docosahexaenoic acids (n-3 family) declined. Redistribution of fatty acids in the erythrocytes membrane towards to such alteration in quantity as the increasing of saturation and decreasing of the unsaturated fatty acids supposes the change of its physical and chemical properties, permeability, lability and complexity of passing erythrocyte via microcircular channels.

Eruption and emplacement dynamics of a thick trachytic lava flow of the Sancy volcano (France)

NASA Astrophysics Data System (ADS)

Latutrie, Benjamin; Harris, Andrew; Médard, Etienne; Gurioli, Lucia

2017-01-01

A 70-m-thick, 2200-m-long (51 × 106 m3) trachytic lava flow unit underlies the Puy de Cliergue (Mt. Dore, France). Excellent exposure along a 400-m-long and 60- to 85-m-high section allows the flow interior to be accessed on two sides of a glacial valley that cuts through the unit. We completed an integrated morphological, structural, textural, and chemical analysis of the unit to gain insights into eruption and flow processes during emplacement of this thick silicic lava flow, so as to elucidate the chamber and flow dynamic processed that operate during the emplacement of such systems. The unit is characterized by an inverse chemical stratification, where there is primitive lava beneath the evolved lava. The interior is plug dominated with a thin basal shear zone overlying a thick basal breccia, with ramping affecting the entire flow thickness. To understand these characteristics, we propose an eruption model that first involves processes operating in the magma chamber whereby a primitive melt is injected into an evolved magma to create a mixed zone at the chamber base. The eruption triggered by this event first emplaced a trachytic dome, into which banded lava from the chamber base was injected. Subsequent endogenous dome growth led to flow down the shallow slope to the east on which the highly viscous (1012 Pa s) coulée was emplaced. The flow likely moved extremely slowly, being emplaced over a period of 4-10 years in a glacial manner, where a thick (>60-m) plug slid over a thin (5-m-thick) basal shear zone. Excellent exposure means that the Puy de Cliergue complex can be viewed as a case type location for understanding and defining the eruption and emplacement of thick, high-viscosity, silicic lava flow systems.

Toxicity of aged gasoline exhaust particles to normal and diseased airway epithelia

NASA Astrophysics Data System (ADS)

Künzi, Lisa; Krapf, Manuel; Daher, Nancy; Dommen, Josef; Jeannet, Natalie; Schneider, Sarah; Platt, Stephen; Slowik, Jay G.; Baumlin, Nathalie; Salathe, Matthias; Prévôt, André S. H.; Kalberer, Markus; Strähl, Christof; Dümbgen, Lutz; Sioutas, Constantinos; Baltensperger, Urs; Geiser, Marianne

2015-06-01

Particulate matter (PM) pollution is a leading cause of premature death, particularly in those with pre-existing lung disease. A causative link between particle properties and adverse health effects remains unestablished mainly due to complex and variable physico-chemical PM parameters. Controlled laboratory experiments are required. Generating atmospherically realistic aerosols and performing cell-exposure studies at relevant particle-doses are challenging. Here we examine gasoline-exhaust particle toxicity from a Euro-5 passenger car in a uniquely realistic exposure scenario, combining a smog chamber simulating atmospheric ageing, an aerosol enrichment system varying particle number concentration independent of particle chemistry, and an aerosol deposition chamber physiologically delivering particles on air-liquid interface (ALI) cultures reproducing normal and susceptible health status. Gasoline-exhaust is an important PM source with largely unknown health effects. We investigated acute responses of fully-differentiated normal, distressed (antibiotics-treated) normal, and cystic fibrosis human bronchial epithelia (HBE), and a proliferating, single-cell type bronchial epithelial cell-line (BEAS-2B). We show that a single, short-term exposure to realistic doses of atmospherically-aged gasoline-exhaust particles impairs epithelial key-defence mechanisms, rendering it more vulnerable to subsequent hazards. We establish dose-response curves at realistic particle-concentration levels. Significant differences between cell models suggest the use of fully-differentiated HBE is most appropriate in future toxicity studies.

Toxicity of aged gasoline exhaust particles to normal and diseased airway epithelia

PubMed Central

Künzi, Lisa; Krapf, Manuel; Daher, Nancy; Dommen, Josef; Jeannet, Natalie; Schneider, Sarah; Platt, Stephen; Slowik, Jay G.; Baumlin, Nathalie; Salathe, Matthias; Prévôt, André S. H.; Kalberer, Markus; Strähl, Christof; Dümbgen, Lutz; Sioutas, Constantinos; Baltensperger, Urs; Geiser, Marianne

2015-01-01

Particulate matter (PM) pollution is a leading cause of premature death, particularly in those with pre-existing lung disease. A causative link between particle properties and adverse health effects remains unestablished mainly due to complex and variable physico-chemical PM parameters. Controlled laboratory experiments are required. Generating atmospherically realistic aerosols and performing cell-exposure studies at relevant particle-doses are challenging. Here we examine gasoline-exhaust particle toxicity from a Euro-5 passenger car in a uniquely realistic exposure scenario, combining a smog chamber simulating atmospheric ageing, an aerosol enrichment system varying particle number concentration independent of particle chemistry, and an aerosol deposition chamber physiologically delivering particles on air-liquid interface (ALI) cultures reproducing normal and susceptible health status. Gasoline-exhaust is an important PM source with largely unknown health effects. We investigated acute responses of fully-differentiated normal, distressed (antibiotics-treated) normal, and cystic fibrosis human bronchial epithelia (HBE), and a proliferating, single-cell type bronchial epithelial cell-line (BEAS-2B). We show that a single, short-term exposure to realistic doses of atmospherically-aged gasoline-exhaust particles impairs epithelial key-defence mechanisms, rendering it more vulnerable to subsequent hazards. We establish dose-response curves at realistic particle-concentration levels. Significant differences between cell models suggest the use of fully-differentiated HBE is most appropriate in future toxicity studies. PMID:26119831

Toxicity of aged gasoline exhaust particles to normal and diseased airway epithelia.

PubMed

Künzi, Lisa; Krapf, Manuel; Daher, Nancy; Dommen, Josef; Jeannet, Natalie; Schneider, Sarah; Platt, Stephen; Slowik, Jay G; Baumlin, Nathalie; Salathe, Matthias; Prévôt, André S H; Kalberer, Markus; Strähl, Christof; Dümbgen, Lutz; Sioutas, Constantinos; Baltensperger, Urs; Geiser, Marianne

2015-06-29

Particulate matter (PM) pollution is a leading cause of premature death, particularly in those with pre-existing lung disease. A causative link between particle properties and adverse health effects remains unestablished mainly due to complex and variable physico-chemical PM parameters. Controlled laboratory experiments are required. Generating atmospherically realistic aerosols and performing cell-exposure studies at relevant particle-doses are challenging. Here we examine gasoline-exhaust particle toxicity from a Euro-5 passenger car in a uniquely realistic exposure scenario, combining a smog chamber simulating atmospheric ageing, an aerosol enrichment system varying particle number concentration independent of particle chemistry, and an aerosol deposition chamber physiologically delivering particles on air-liquid interface (ALI) cultures reproducing normal and susceptible health status. Gasoline-exhaust is an important PM source with largely unknown health effects. We investigated acute responses of fully-differentiated normal, distressed (antibiotics-treated) normal, and cystic fibrosis human bronchial epithelia (HBE), and a proliferating, single-cell type bronchial epithelial cell-line (BEAS-2B). We show that a single, short-term exposure to realistic doses of atmospherically-aged gasoline-exhaust particles impairs epithelial key-defence mechanisms, rendering it more vulnerable to subsequent hazards. We establish dose-response curves at realistic particle-concentration levels. Significant differences between cell models suggest the use of fully-differentiated HBE is most appropriate in future toxicity studies.

The Effect of Designated Pollutants on Plants

DTIC Science & Technology

1979-12-01

chamber . . . . .. . . o 34 10 Leaf injury on marigold plants at Vandenberg AFB exposed to HCI gas. . . . . . . . . . . . . * . . . * 0 * * * * 36 11...in a preliminary field trial . 6. . . . . . . . . . . . . . . . . . . . .. . 22 12 Injury on bean, zinnia, and marigold seedlings after field exposure...solid rocket fuel under field conditions . . . . . . . . 26 16 Chlorine content of marigold and zinnia plants exposed weekly to gas generated by solid

SEASONAL PATTERNS OF PHOTOSYNTHESIS IN DOUGLAS FIR SEEDLINGS DURING THE THIRD AND FOURTH YEAR OF EXPOSURE TO ELEVATED CO2 AND TEMPERATURE

EPA Science Inventory

We examined the interactive effects of elevated atmospheric CO2 and temperature on seasonal patterns of photosynthesis in Douglas-fir (Psuedotsuga menziesii (Mirb.) Franco) seedlings. Seedlings were grown in sunlit chambers controlled to track either ambient (~400 ppm) CO2 or am...

Roof temperatures in simulated attics

Treesearch

J. E. Winandy; R. Beaumont

The degradation of wood treated with fire retardant (FR) chemicals in roof systems is a problem of major national significance. Understanding of this phenomenon is limited by lack of information on how the performance of FR-treated wood in the laboratory correlates to that of FR-treated wood in the field. In this study, five outdoor field exposure chambers were...

A replacement for methoxyflurane (Metofane) in open-circuit anaesthesia.

PubMed

Itah, Refael; Gitelman, Inna; Davis, Claytus

2004-07-01

Methoxyflurane (Metofane) has been widely used as an open-circuit anaesthetic in small laboratory animals for several decades. Its low vapour pressure and high blood solubility have permitted its use in convenient and simple drop-chamber/nose-cone setups. Recently, following the decision by the primary manufacturer to discontinue production, it has become increasingly difficult to obtain methoxyflurane. We describe here a simple and effective adaptation of isoflurane, an excellent inhalation anaesthetic, to open-circuit drop-chamber/nose-cone anaesthesia. It was found that the vapour concentration of isoflurane could be continuously varied by dissolving the anaesthetic in propylene glycol and that a 20% solution produced effective anaesthesia such that in adult mice, 2 ml of 20% isoflurane in propylene glycol induced anaesthesia within 2 min in a one-litre drop chamber. Furthermore, anaesthesia maintenance with 20% isoflurane was tested in two sets of mice. In one set, surgical plane anaesthesia was maintained for 10 min in a head chamber. After removal of the chamber, the animals awoke within one minute and recovered without any indication of post-anaesthetic distress. The second set contained pregnant mice; here anaesthesia was maintained for between 10 and 12 min, during which laparotomy, exposure of one uterine horn, intrauterine injection and wound closure were completed. The recovery from anaesthesia was also within a minute and with no signs of distress. Healthy litters were delivered after a normal gestation. This isoflurane/propylene glycol procedure is simple, effective and humane, and is a good substitute for methoxyflurane.

Effects of ozone on productivity and diversity of an early successional forest community

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

Barbo, D.N.; Chappelka, A.H.

1995-12-31

Little research exists on the effects of tropospheric ozone on the diversity and productivity of native understory vegetation and tree species growing in competition. To address this question, open-top chambers were utilized at a field site in Auburn, Alabama. After completion of a study in 1990, no weed removal, cutting or chemical treatments were allowed in the chambers. Major species include blackberry, andropogan, bahia grass and two species of blackberry, andropogan, bahia grass and two species of panicum grass. In the winter of 1993-1994, after leaf fall, all vegetation was cut to groundline and left as litter. Vegetation was allowedmore » to regenerate naturally the following spring. In addition 5, one-year-old loblolly pines were planted in each chamber in January, 1994. Four treatments, blocked 4 times were used: carbon-filtered air, non-filtered (ambient air), ambient (no plastics) and twice ambient ozone concentrations. Trees were measured monthly for height and diameter. Abundance and frequency of species, and percent ground cover of understory vegetation were calculated. First year results show a decrease in species diversity with increasing ozone concentrations. Percent cover, however, was greatest in the chambers receiving the lowest and highest ozone exposures. Blackberry was the dominate species in the 2 X-ambient ozone treatments. Loblolly pine growth appeared suppressed in the carbon-filtered chambers due to intense competition from understory vegetation. This study will continue for at least one more growing season.« less

Responses of sensitive and tolerant bush beans (Phaseolus vulgaris L.) to ozone in open-top chambers are influenced by phenotypic differences, morphological characteristics, and the chamber environment.

PubMed

Elagöz, Vahram; Manning, William J

2005-08-01

Responses of bush bean (Phaseolus vulgaris L.) lines 'S156' (O(3)-sensitive) and 'R123' (O(3)-tolerant), and cultivars 'BBL 290' (O(3)-sensitive) and 'BBL 274' (O(3)-tolerant) to ambient ozone (O(3)) were investigated during the 2001 and 2002 growing seasons. Seedlings were grown in pots inside open-top chambers (OTCs), with charcoal filtered (CF) and non-filtered (NF) ambient air, and in non-chambered ambient air (AA) plots. Growth parameters from individual plants were evaluated after harvests at the end of vegetative (V(4)) and reproductive (R(10)) growth phases. Results at V(4) indicated that CF did not provide additional benefits over NF in 'S156' in 2001 and 2002. In contrast, exposure to CF significantly impaired the growth of 'R123'. At the end of R(10), 'S156' produced more pods, most of which remained immature, and contained fewer seeds or were more frequently aborted, whereas pods produced in 'R123' reached pod maturation and senescence more consistently. Despite increased seed weights inside the OTCs, as observed in 'S156', differences between the two lines were insignificant when grown outside OTCs. Results from the 'BBL 290'/'BBL 274' pair, especially at V(4) phase, remained inconclusive. Plant morphological characteristics, variabilities in environmental conditions, and 'chamber effects' inside OTCs were influential in determining plant response to ambient O(3).

Threshold altitude resulting in decompression sickness

NASA Technical Reports Server (NTRS)

Kumar, K. V.; Waligora, James M.; Calkins, Dick S.

1990-01-01

A review of case reports, hypobaric chamber training data, and experimental evidence indicated that the threshold for incidence of altitude decompression sickness (DCS) was influenced by various factors such as prior denitrogenation, exercise or rest, and period of exposure, in addition to individual susceptibility. Fitting these data with appropriate statistical models makes it possible to examine the influence of various factors on the threshold for DCS. This approach was illustrated by logistic regression analysis on the incidence of DCS below 9144 m. Estimations using these regressions showed that, under a noprebreathe, 6-h exposure, simulated EVA profile, the threshold for symptoms occurred at approximately 3353 m; while under a noprebreathe, 2-h exposure profile with knee-bends exercise, the threshold occurred at 7925 m.

Thermoregulation is impaired in an environment without circadian time cues

NASA Technical Reports Server (NTRS)

Fuller, C. A.; Sulzman, F. M.; Moore-Ede, M. C.

1978-01-01

Thirteen adult male squirrel monkeys were restrained to a metabolism chair for periods of two or more weeks within an isolation chamber having controlled environmental lighting and ambient temperature. The monkeys were subjected to mild 6-hour cold exposures at all circadian phases of the day. It was found that a prominent circadian rhythm in body temperature, regulated against mild cold exposure, was present in those monkeys synchronized in a 24-hour light-dark cycle. Cold exposures were found to produce decreased core body temperatures when the circadian rhythms were free running or when environmental time indicators were not present. It is concluded that the thermoregulating system depends on the internal synchronization of the circadian time-keeping system.

Survival and growth of newly transformed Lampsilis cardium and Lampsilis siliquoidea in a flow-through, continuous feeding test system

USGS Publications Warehouse

Meinertz, Jeffery R.; Schreier, Theresa M.; Hess, Karina R.; Bartsch, Michelle

2011-01-01

A test system was evaluated for assessing chronic toxicity of waterborne chemicals with early life stage mussels. To determine if the test system could result in ≥80% survival in a control (unexposed) group, fat mucket mussels (Lampsilis siliquoidea Barnes, 1823) and plain pocketbook mussels (L. cardium Rafinesque, 1820) 1 day post transformation were stocked into test chambers (250 mL beakers, water volume, 200 mL, 21 °C, 40 mussels of 1 species per chamber) within a test system constructed for conducting chronic, continuous exposure, flow-through toxicity tests. The test system contained 60 chambers containing silica sand, 30 chambers with L. siliquoidea, and 30 with L. cardium. Each chamber in the continuous feeding system received 1 of 6 food types prepared with concentrated algal products. After 28 days, mussels were harvested from chambers to assess survival and growth. For L. siliquoidea, mean survival ranged from 34 to 80% and mean shell length ranged from 464 to 643 µm. For L. cardium, mean survival ranged from 12 to 66% and mean shell length ranged from 437 to 612 µm. The maximum mean growth rate for L. siliquoidea was 12.7 µm/d and for L. cardium was 11.8 µm/d. When offered a continuous diet of Nannochloropsis, Tetraselmis, and Chlorella for 28 days in the test system, the survival of 1 day post transformation L. siliquoidea was 80%. The test system can be easily enhanced with a pumping system continuously delivering test chemical to the test system's flow stream allowing for chronic toxicity tests with 1 day post transformation mussels.

Penetration of 38% hydrogen peroxide into the pulp chamber in bovine and human teeth submitted to office bleach technique.

PubMed

Camargo, Samira Esteves Afonso; Valera, Marcia Carneiro; Camargo, Carlos Henrique Ribeiro; Gasparoto Mancini, Maria Nadir; Menezes, Marcia Maciel

2007-09-01

This study evaluated the pulp chamber penetration of peroxide bleaching agent in human and bovine teeth after office bleach technique. All the teeth were sectioned 3 mm apical of the cement-enamel junction and were divided into 2 groups, A (70 third human molars) and B (70 bovine lateral incisors), that were subdivided into A1 and B1 restored by using composite resin, A2 and B2 by using glass ionomer cement, and A3 and B3 by using resin-modified glass ionomer cement; A4, A5, B4, and B5 were not restored. Acetate buffer was placed in the pulp chamber, and the bleaching agent was applied for 40 minutes as follows: A1-A4 and B1-B4, 38% hydrogen peroxide exposure and A5 and B5, immersion into distilled water. The buffer solution was transferred to a glass tube in which leuco crystal violet and horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to analysis of variance and Dunnett, Kruskal-Wallis, and Tukey tests (5%). A higher level of hydrogen peroxide penetrated into the pulp chamber in resin-modified glass ionomer cements in bovine (0.79 +/- 0.61 microg) and human (2.27 +/- 0.41 microg) groups. The bleaching agent penetration into the pulp chamber was higher in human teeth for any experimental situation. The penetration of the hydrogen peroxide depends on restorative materials, and under the conditions of this study human teeth are more susceptible to penetration of bleaching agent into the pulp chamber than bovine teeth.

Cytotoxicity, cytokine release and ER stress-autophagy gene expression in endothelial cells and alveolar-endothelial co-culture exposed to pristine and carboxylated multi-walled carbon nanotubes.

PubMed

Chang, Shiwei; Zhao, Xuqi; Li, Siyu; Liao, Tuqiang; Long, Jimin; Yu, Zhiqiang; Cao, Yi

2018-06-18

Recently we found that direct exposure of human umbilical vein endothelial cells (HUVECs) to multi-walled carbon nanotubes (MWCNTs) might induce toxicological responses through the modulation of ER stress gene expression, but whether this signal could be transferred from other cells to endothelial cells (ECs) is unknown. This study investigated the toxicity of pristine and carboxylated MWCNTs to HUVECs and alveolar-endothelial co-culture, the later of which could mimic the possible signaling communications between ECs and MWCNT exposed alveolar cells. The results showed that direct contact with high levels of MWCNTs induced cytotoxicity and modulated expression of genes associated with ER stress (HSPA5, DDIT3 and XBP-1s) and autophagy (BECN1 and ATG12) both in A549-THP-1 macrophages cultured in the upper chambers as well as HUVECs. However, most of these responses were minimal or negligible in HUVECs cultured in the lower chambers. Moreover, significantly increased cytokine release (interleukin-6 and soluble vascular cell adhesion molecule-1) was only observed in MWCNT exposed HUVECs (p < 0.01) but not HUVECs cultured in the lower chambers (p > 0.05). The minimal or even absent response was likely due to relatively low translocation of MWCNTs from upper chambers to lower chambers, whereas A549-macrophages cultured in the upper chambers internalized large amount MWCNTs. The results indicated that ER stress-autophagy signaling might not be able to transfer from alveolar cells to endothelial cells unless sufficient MWCNTs are translocated. Copyright © 2018 Elsevier Inc. All rights reserved.

A test of the IAEA code of practice for absorbed dose determination in photon and electron beams

NASA Astrophysics Data System (ADS)

Leitner, Arnold; Tiefenboeck, Wilhelm; Witzani, Josef; Strachotinsky, Christian

1990-12-01

The IAEA (International Atomic Energy Agency) code of practice TRS 277 gives recommendations for absorbed dose determination in high energy photon and electron beams based on the use of ionization chambers calibrated in terms of exposure of air kerma. The scope of the work was to test the code for cobalt 60 gamma radiation and for several radiation qualities at four different types of electron accelerators and to compare the ionization chamber dosimetry with ferrous sulphate dosimetry. The results show agreement between the two methods within about one per cent for all the investigated qualities. In addition the response of the TLD capsules of the IAEA/WHO TL dosimetry service was determined.

The effect of olfactory exposure to non-insecticidal agrochemicals on bumblebee foraging behavior.

PubMed

Sprayberry, Jordanna D H; Ritter, Kaitlin A; Riffell, Jeffrey A

2013-01-01

Declines in bumblebee populations have led to investigations into potential causes - including agrochemical effects on bumblebee physiology. The indirect effects of agrochemicals (i.e. behavior modulation) have been postulated, but rarely directly tested. Olfactory information is critical in mediating bumblebee-floral interactions. As agrochemicals emit volatiles, they may indirectly modify foraging behavior. We tested the effects of olfactory contamination of floral odor by agrochemical scent on foraging activity of Bombus impatiens using two behavioral paradigms: localization of food within a maze and forced-choice preference. The presence of a fungicide decreased bumblebees' ability to locate food within a maze. Additionally, bumblebees preferred to forage in non-contaminated feeding chambers when offered a choice between control and either fertilizer- or fungicide-scented chambers.

Small-Chamber Measurements of Chemical-Specific Emission Factors for Drywall

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

Maddalena, Randy; Russell, Marion; Apte, Michael G.

2010-06-01

Imported drywall installed in U.S. homes is suspected of being a source of odorous and potentially corrosive indoor pollutants. To support an investigation of those building materials by the Consumer Products Safety Commission (CPSC), Lawrence Berkeley National Laboratory (LBNL) measured chemical-specific emission factors for 30 samples of drywall materials. Emission factors are reported for 75 chemicals and 30 different drywall samples encompassing both domestic and imported stock and incorporating natural, synthetic, or mixed gypsum core material. CPSC supplied all drywall materials. First the drywall samples were isolated and conditioned in dedicated chambers, then they were transferred to small chambers wheremore » emission testing was performed. Four sampling and analysis methods were utilized to assess (1) volatile organic compounds, (2) low molecular weight carbonyls, (3) volatile sulfur compounds, and (4) reactive sulfur gases. LBNL developed a new method that combines the use of solid phase microextraction (SPME) with small emission chambers to measure the reactive sulfur gases, then extended that technique to measure the full suite of volatile sulfur compounds. The testing procedure and analysis methods are described in detail herein. Emission factors were measured under a single set of controlled environmental conditions. The results are compared graphically for each method and in detailed tables for use in estimating indoor exposure concentrations.« less

Characterization of a commercially-available, optically-stimulated luminescent dosimetry system for use in computed tomography.

PubMed

Lavoie, Lindsey; Ghita, Monica; Brateman, Libby; Arreola, Manuel

2011-09-01

Optically-stimulated luminescent (OSL) nanoDot dosimeters, commercially available from Landauer, Inc. (Glenwood, IL), were assessed for use in computed tomography (CT) for erasure and reusability, linearity and reproducibility of response, and angular and energy response in different scattering conditions. Following overnight exposure to fluorescent room light, the residual signal on the dosimeters was 2%. The response of the dosimeters to identical exposures was consistent, and reported doses were within 4% of each other. The dosimeters responded linearly with dose up to 1 Gy. The dosimeter response to the CT beams decreased with increased tube voltage, showing up to a -16% difference when compared to a 0.6-cm(3) NIST-traceable calibrated ionization chamber for a 135 kVp CT beam. The largest range in percent difference in dosimeter response to scatter at central and peripheral positions inside CTDI phantoms was 14% at 80 kVp CT tube voltage, when compared to the ionization chamber. The dosimeters responded uniformly to x-ray tube angle over the ranges of increments of 0° to 75° and 105° to 180° when exposed in air, and from 0° to 360° when exposed inside a CTDI phantom. While energy and scatter correction factors should be applied to dosimeter readings for the purpose of determining absolute doses, these corrections are straightforward but depend on the accuracy of the ionization chamber used for cross-calibration. The linearity and angular responses, combined with the ability to reuse the dosimeters, make this OSL system an excellent choice for clinical CT dose measurements.

Assessment of the capacity of vehicle cabin air inlet filters to reduce diesel exhaust-induced symptoms in human volunteers

PubMed Central

2014-01-01

Background Exposure to particulate matter (PM) air pollution especially derived from traffic is associated with increases in cardiorespiratory morbidity and mortality. In this study, we evaluated the ability of novel vehicle cabin air inlet filters to reduce diesel exhaust (DE)-induced symptoms and markers of inflammation in human subjects. Methods Thirty healthy subjects participated in a randomized double-blind controlled crossover study where they were exposed to filtered air, unfiltered DE and DE filtered through two selected particle filters, one with and one without active charcoal. Exposures lasted for one hour. Symptoms were assessed before and during exposures and lung function was measured before and after each exposure, with inflammation assessed in peripheral blood five hours after exposures. In parallel, PM were collected from unfiltered and filtered DE and assessed for their capacity to drive damaging oxidation reactions in a cell-free model, or promote inflammation in A549 cells. Results The standard particle filter employed in this study reduced PM10 mass concentrations within the exposure chamber by 46%, further reduced to 74% by the inclusion of an active charcoal component. In addition use of the active charcoal filter was associated by a 75% and 50% reduction in NO2 and hydrocarbon concentrations, respectively. As expected, subjects reported more subjective symptoms after exposure to unfiltered DE compared to filtered air, which was significantly reduced by the filter with an active charcoal component. There were no significant changes in lung function after exposures. Similarly diesel exhaust did not elicit significant increases in any of the inflammatory markers examined in the peripheral blood samples 5 hour post-exposure. Whilst the filters reduced chamber particle concentrations, the oxidative activity of the particles themselves, did not change following filtration with either filter. In contrast, diesel exhaust PM passed through the active charcoal combination filter appeared less inflammatory to A549 cells. Conclusions A cabin air inlet particle filter including an active charcoal component was highly effective in reducing both DE particulate and gaseous components, with reduced exhaust-induced symptoms in healthy volunteers. These data demonstrate the effectiveness of cabin filters to protect subjects travelling in vehicles from diesel exhaust emissions. PMID:24621126

Effects of toluene inhalation on detection of auditory signals in rats.

PubMed

Bushnell, P J; Kelly, K L; Crofton, K M

1994-01-01

Inhalation of organic solvents can affect vigilance and reaction time in humans. An animal model of vigilance was designed to assess the effects of toluene on these processes. Adult male Long-Evans rats were trained to detect auditory signals (20-msec increases in the intensity of white noise). Two to 4 s after each signal (or blank period), two retractable levers were inserted into the test chamber. A press on one lever after a signal and on the other lever after a blank resulted in the delivery of food. Signal detection analysis showed that sensitivity (Sensitivity Index, SI) and response bias (Responsivity Index, RI) increased with signal intensity, indicating that loud signals were more detectable than soft signals and that the animals' criterion for responding "signal" increased with signal intensity. Response latency for correct choices was faster for signal trials than for blank trials. Toluene vapor was added to the airstream of these chambers at concentrations of 0, 1000, 1500, or 2000 ppm, either 10 or 30 min before testing and for the duration of each 1-h test. In air, SI increased across the duration of the test; this within-session improvement was reversed by toluene. RI did not change in air; it was decreased by toluene at the beginning of each exposure session, returned to the control level during exposure to 1000 and 1500 ppm toluene and exceeded air control after 40 min exposure to 2000 ppm toluene. Latency increased monotonically across toluene concentrations and time on test. Neither signal intensity nor the duration of toluene exposure before testing altered these effects of toluene. SI, RI, and latency baselines were recovered after toluene exposure indicating that no persistent effects of toluene were detectable. This conclusion was supported by data from other rats showing that toluene exposure (2000 ppm for 2 h/day for 4 consecutive days) did not affect auditory thresholds, as determined by reflex modification of an acoustic startle response using a 16 kHz tone as a prepulse stimulus, 7 or 17 days after exposure to toluene. Finally, rats tested immediately or 20 min after exposure to 0, 1000, 1500, or 2000 ppm toluene were not affected by the vapor, indicating that the impairment observed during toluene inhalation did not persist beyond the period of exposure.

Acute exposure to wood smoke from incomplete combustion--indications of cytotoxicity.

PubMed

Muala, Ala; Rankin, Gregory; Sehlstedt, Maria; Unosson, Jon; Bosson, Jenny A; Behndig, Annelie; Pourazar, Jamshid; Nyström, Robin; Pettersson, Esbjörn; Bergvall, Christoffer; Westerholm, Roger; Jalava, Pasi I; Happo, Mikko S; Uski, Oskari; Hirvonen, Maija-Riitta; Kelly, Frank J; Mudway, Ian S; Blomberg, Anders; Boman, Christoffer; Sandström, Thomas

2015-10-29

Smoke from combustion of biomass fuels is a major risk factor for respiratory disease, but the underlying mechanisms are poorly understood. The aim of this study was to determine whether exposure to wood smoke from incomplete combustion would elicit airway inflammation in humans. Fourteen healthy subjects underwent controlled exposures on two separate occasions to filtered air and wood smoke from incomplete combustion with PM1 concentration at 314 μg/m(3) for 3 h in a chamber. Bronchoscopy with bronchial wash (BW), bronchoalveolar lavage (BAL) and endobronchial mucosal biopsies was performed after 24 h. Differential cell counts and soluble components were analyzed, with biopsies stained for inflammatory markers using immunohistochemistry. In parallel experiments, the toxicity of the particulate matter (PM) generated during the chamber exposures was investigated in vitro using the RAW264.7 macrophage cell line. Significant reductions in macrophage, neutrophil and lymphocyte numbers were observed in BW (p < 0.01, <0.05, <0.05, respectively) following the wood smoke exposure, with a reduction in lymphocytes numbers in BAL fluid (<0.01. This unexpected cellular response was accompanied by decreased levels of sICAM-1, MPO and MMP-9 (p < 0.05, <0.05 and <0.01). In contrast, significant increases in submucosal and epithelial CD3+ cells, epithelial CD8+ cells and submucosal mast cells (p < 0.01, <0.05, <0.05 and <0.05, respectively), were observed after wood smoke exposure. The in vitro data demonstrated that wood smoke particles generated under these incomplete combustion conditions induced cell death and DNA damage, with only minor inflammatory responses. Short-term exposure to sooty PAH rich wood smoke did not induce an acute neutrophilic inflammation, a classic hallmark of air pollution exposure in humans. While minor proinflammatory lymphocytic and mast cells effects were observed in the bronchial biopsies, significant reductions in BW and BAL cells and soluble components were noted. This unexpected observation, combined with the in vitro data, suggests that wood smoke particles from incomplete combustion could be potentially cytotoxic. Additional research is required to establish the mechanism of this dramatic reduction in airway leukocytes and to clarify how this acute response contributes to the adverse health effects attributed to wood smoke exposure. NCT01488500.

A circadian rhythm of conidiation in Neurospora crassa (L-12)

NASA Technical Reports Server (NTRS)

Miyoshi, Yashuhiro

1993-01-01

Two fungi growth chambers containing six growth tubes each are used in this experiment. One chamber is for the space experiment; the other is for the simultaneous ground control experiment. The hyphae of Neurospora crassa band A mutant are inoculated at one end of each tube. Both the chambers are kept at 3 C plus or minus 1.5 C to stop hyphae growth until the Spacelab is activated. After the activation, each chamber is transferred simultaneously to the Spacelab and a phytotron in KSC and kept in continuous light at the same temperature. After about 24 hours of light exposure, each chamber is inserted into a growth chamber bag to keep it in constant darkness. The circadian rhythm of conidiation is initiated by this light to dark transition. After the dark incubation for 5 days at room temperature, both the growth chambers are kept at 3 C plus or minus 1.5 C to stop growth of the hyphae. After the space shuttle lands, both conidiation patterns are compared and analyzed. It has been known that numerous physiological phenomena show circadian rhythms. They are characterized by the fact that the oscillation can persist under constant conditions of light and temperature. Therefore, it has been accepted by most investigators that the generation mechanism of the circadian rhythm is endogeneous. However, one cannot reject the possibility that these rhythms are caused by some geophysical exogeneous factor having a 24-hour period, such as atmospheric pressure, gravity, or electromagnetic radiation. We use Neurospora crassa band A mutual which shows an obvious circadian rhythm in its spore-forming (conidiation) on the ground, and we intend to attempt the conidation of this mutant in the Spacelab where 24-hour periodicity is severely attenuated and to elucidate the effect of the geophysical exogeneous factor in the generation mechanism of the circadian rhythm.

Cardiac Autonomic Effects of Acute Exposures to Airborne Particulates in Men and Women

NASA Technical Reports Server (NTRS)

Howarth, M. S.; Schlegel, T. T.; Knapp, C. F.; Patwardhan, A. R.; Jenkins, R. A.; Ilgner, R. H.; Evans, J. M.

2007-01-01

The aim of this research was to investigate cardiac autonomic changes associated with acute exposures to airborne particulates. Methods: High fidelity 12-lead ECG (CardioSoft, Houston, TX) was acquired from 19 (10 male / 9 female) non-smoking volunteers (age 33.6 +/- 6.6 yrs) during 10 minutes pre-exposure, exposure and post-exposure to environmental tobacco smoke (ETS), cooking oil fumes, wood smoke and sham (water vapor). To control exposure levels, noise, subject activity, and temperature, all studies were conducted inside an environmental chamber. Results: The short-term fractal scaling exponent (Alpha-1) and the ratio of low frequency to high frequency Heart Rate Variability (HRV) powers (LF/HF, a purported sympathetic index) were both higher in males (p<0.017 and p<0.05, respectively) whereas approximate entropy (ApEn) and HF/(LF+HF) (a purported parasympathetic index) were both lower in males (p<0.036, and p<0.044, respectively). Compared to pre-exposure (p<0.0002) and sham exposure (p<0.047), male heart rates were elevated during early ETS post-exposure. Our data suggest that, in addition to tonic HRV gender differences, cardiac responses to some acute airborne particulates are gender related.

Combining Nitrous Oxide with Carbon Dioxide Decreases the Time to Loss of Consciousness during Euthanasia in Mice — Refinement of Animal Welfare?

PubMed Central

Thomas, Aurelie A.; Flecknell, Paul A.; Golledge, Huw D. R.

2012-01-01

Carbon dioxide (CO2) is the most commonly used euthanasia agent for rodents despite potentially causing pain and distress. Nitrous oxide is used in man to speed induction of anaesthesia with volatile anaesthetics, via a mechanism referred to as the “second gas” effect. We therefore evaluated the addition of Nitrous Oxide (N2O) to a rising CO2 concentration could be used as a welfare refinement of the euthanasia process in mice, by shortening the duration of conscious exposure to CO2. Firstly, to assess the effect of N2O on the induction of anaesthesia in mice, 12 female C57Bl/6 mice were anaesthetized in a crossover protocol with the following combinations: Isoflurane (5%)+O2 (95%); Isoflurane (5%)+N2O (75%)+O2 (25%) and N2O (75%)+O2 (25%) with a total flow rate of 3l/min (into a 7l induction chamber). The addition of N2O to isoflurane reduced the time to loss of the righting reflex by 17.6%. Secondly, 18 C57Bl/6 and 18 CD1 mice were individually euthanized by gradually filling the induction chamber with either: CO2 (20% of the chamber volume.min−1); CO2+N2O (20 and 60% of the chamber volume.min−1 respectively); or CO2+Nitrogen (N2) (20 and 60% of the chamber volume.min−1). Arterial partial pressure (Pa) of O2 and CO2 were measured as well as blood pH and lactate. When compared to the gradually rising CO2 euthanasia, addition of a high concentration of N2O to CO2 lowered the time to loss of righting reflex by 10.3% (P<0.001), lead to a lower PaO2 (12.55±3.67 mmHg, P<0.001), a higher lactataemia (4.64±1.04 mmol.l−1, P = 0.026), without any behaviour indicative of distress. Nitrous oxide reduces the time of conscious exposure to gradually rising CO2 during euthanasia and hence may reduce the duration of any stress or distress to which mice are exposed during euthanasia. PMID:22438874

26th Space Simulation Conference Proceedings. Environmental Testing: The Path Forward

NASA Technical Reports Server (NTRS)

Packard, Edward A.

2010-01-01

Topics covered include: A Multifunctional Space Environment Simulation Facility for Accelerated Spacecraft Materials Testing; Exposure of Spacecraft Surface Coatings in a Simulated GEO Radiation Environment; Gravity-Offloading System for Large-Displacement Ground Testing of Spacecraft Mechanisms; Microscopic Shutters Controlled by cRIO in Sounding Rocket; Application of a Physics-Based Stabilization Criterion to Flight System Thermal Testing; Upgrade of a Thermal Vacuum Chamber for 20 Kelvin Operations; A New Approach to Improve the Uniformity of Solar Simulator; A Perfect Space Simulation Storm; A Planetary Environmental Simulator/Test Facility; Collimation Mirror Segment Refurbishment inside ESA s Large Space; Space Simulation of the CBERS 3 and 4 Satellite Thermal Model in the New Brazilian 6x8m Thermal Vacuum Chamber; The Certification of Environmental Chambers for Testing Flight Hardware; Space Systems Environmental Test Facility Database (SSETFD), Website Development Status; Wallops Flight Facility: Current and Future Test Capabilities for Suborbital and Orbital Projects; Force Limited Vibration Testing of JWST NIRSpec Instrument Using Strain Gages; Investigation of Acoustic Field Uniformity in Direct Field Acoustic Testing; Recent Developments in Direct Field Acoustic Testing; Assembly, Integration and Test Centre in Malaysia: Integration between Building Construction Works and Equipment Installation; Complex Ground Support Equipment for Satellite Thermal Vacuum Test; Effect of Charging Electron Exposure on 1064nm Transmission through Bare Sapphire Optics and SiO2 over HfO2 AR-Coated Sapphire Optics; Environmental Testing Activities and Capabilities for Turkish Space Industry; Integrated Circuit Reliability Simulation in Space Environments; Micrometeoroid Impacts and Optical Scatter in Space Environment; Overcoming Unintended Consequences of Ambient Pressure Thermal Cycling Environmental Tests; Performance and Functionality Improvements to Next Generation Thermal Vacuum Control System; Robotic Lunar Lander Development Project: Three-Dimensional Dynamic Stability Testing and Analysis; Thermal Physical Properties of Thermal Coatings for Spacecraft in Wide Range of Environmental Conditions: Experimental and Theoretical Study; Molecular Contamination Generated in Thermal Vacuum Chambers; Preventing Cross Contamination of Hardware in Thermal Vacuum Chambers; Towards Validation of Particulate Transport Code; Updated Trends in Materials' Outgassing Technology; Electrical Power and Data Acquisition Setup for the CBER 3 and 4 Satellite TBT; Method of Obtaining High Resolution Intrinsic Wire Boom Damping Parameters for Multi-Body Dynamics Simulations; and Thermal Vacuum Testing with Scalable Software Developed In-House.

Combining nitrous oxide with carbon dioxide decreases the time to loss of consciousness during euthanasia in mice--refinement of animal welfare?

PubMed

Thomas, Aurelie A; Flecknell, Paul A; Golledge, Huw D R

2012-01-01

Carbon dioxide (CO(2)) is the most commonly used euthanasia agent for rodents despite potentially causing pain and distress. Nitrous oxide is used in man to speed induction of anaesthesia with volatile anaesthetics, via a mechanism referred to as the "second gas" effect. We therefore evaluated the addition of Nitrous Oxide (N(2)O) to a rising CO(2) concentration could be used as a welfare refinement of the euthanasia process in mice, by shortening the duration of conscious exposure to CO2. Firstly, to assess the effect of N(2)O on the induction of anaesthesia in mice, 12 female C57Bl/6 mice were anaesthetized in a crossover protocol with the following combinations: Isoflurane (5%)+O(2) (95%); Isoflurane (5%)+N(2)O (75%)+O(2) (25%) and N(2)O (75%)+O(2) (25%) with a total flow rate of 3 l/min (into a 7 l induction chamber). The addition of N(2)O to isoflurane reduced the time to loss of the righting reflex by 17.6%. Secondly, 18 C57Bl/6 and 18 CD1 mice were individually euthanized by gradually filling the induction chamber with either: CO(2) (20% of the chamber volume.min-1); CO(2)+N(2)O (20 and 60% of the chamber volume.min(-1) respectively); or CO(2)+Nitrogen (N(2)) (20 and 60% of the chamber volume.min-1). Arterial partial pressure (P(a)) of O(2) and CO(2) were measured as well as blood pH and lactate. When compared to the gradually rising CO(2) euthanasia, addition of a high concentration of N(2)O to CO(2) lowered the time to loss of righting reflex by 10.3% (P<0.001), lead to a lower P(a)O(2) (12.55 ± 3.67 mmHg, P<0.001), a higher lactataemia (4.64 ± 1.04 mmol.l(-1), P = 0.026), without any behaviour indicative of distress. Nitrous oxide reduces the time of conscious exposure to gradually rising CO(2) during euthanasia and hence may reduce the duration of any stress or distress to which mice are exposed during euthanasia.

White Matter Hyperintensities and Hypobaric Exposure

PubMed Central

McGuire, Stephen A.; Sherman, Paul M.; Wijtenburg, S. Andrea; Rowland, Laura M.; Grogan, Patrick M.; Sladky, John H.; Robinson, Andrew Y.; Kochunov, Peter V.

2014-01-01

Objective Demonstrate that occupational exposure to nonhypoxic hypobaria is associated with subcortical white matter hyperintensities (WMHs) on fluid-attenuated inversion recovery magnetic resonance imaging (MRI). Methods Eighty-three altitude chamber personnel (PHY), 105 U-2 pilots (U2P), and 148 age- controlled and health-matched doctorate degree controls (DOC) underwent high-resolution MRI. Subcortical WMH burden was quantified as count and volume of subcortical WMH lesions after transformation of images to the Talairach atlas–based stereo-tactic frame. Results Subcortical WMHs were more prevalent in PHY (volume p = 0.011/count p = 0.019) and U2P (volume p<0.001/count p<0.001) when compared to DOC, whereas PHY were not significantly different than U2P. Interpretation This study provides strong evidence that nonhypoxic hypobaric exposure may induce subcortical WMHs in a young, healthy population lacking other risk factors for WMHs and adds this occupational exposure to other environmentally related potential causes of WMHs. PMID:25164539

An experiment on the dynamics of ion implantation and sputtering of surfaces

NASA Astrophysics Data System (ADS)

Wright, G. M.; Barnard, H. A.; Kesler, L. A.; Peterson, E. E.; Stahle, P. W.; Sullivan, R. M.; Whyte, D. G.; Woller, K. B.

2014-02-01

A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface.

An experiment on the dynamics of ion implantation and sputtering of surfaces.

PubMed

Wright, G M; Barnard, H A; Kesler, L A; Peterson, E E; Stahle, P W; Sullivan, R M; Whyte, D G; Woller, K B

2014-02-01

A major impediment towards a better understanding of the complex plasma-surface interaction is the limited diagnostic access to the material surface while it is undergoing plasma exposure. The Dynamics of ION Implantation and Sputtering Of Surfaces (DIONISOS) experiment overcomes this limitation by uniquely combining powerful, non-perturbing ion beam analysis techniques with a steady-state helicon plasma exposure chamber, allowing for real-time, depth-resolved in situ measurements of material compositions during plasma exposure. Design solutions are described that provide compatibility between the ion beam analysis requirements in the presence of a high-intensity helicon plasma. The three primary ion beam analysis techniques, Rutherford backscattering spectroscopy, elastic recoil detection, and nuclear reaction analysis, are successfully implemented on targets during plasma exposure in DIONISOS. These techniques measure parameters of interest for plasma-material interactions such as erosion/deposition rates of materials and the concentration of plasma fuel species in the material surface.

Measuring Optical Component Radiation Damage

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

Wenzl, Derek; Tesarek, Richard

2017-08-01

Scintillator based detectors are used to monitor beam losses in the Fermilab accelerator complex. These detectors are approximately 500 times faster than traditional ionization chamber loss monitors and can see beam losses 20 nanoseconds apart. These fast loss monitors are used in areas of the accelerator known to be sources of heavy beam loss and as such, are exposed to high doses of radiation. Over time, radiation exposure reduces the ability of optical components to transmit light by darkening the material. The most dramatic effects are seen in the optical cement and light guide materials comprising the detector. We exploremore » this darkening effect by measuring the transmittance spectra of the detector materials for varying irradiation exposures. Presented here, are the optical transmittance spectra for a variety of radiation exposures and optical materials. The data has revealed an epoxy which withstands exposure far better than traditional optical cements.« less

Sporicidal Effects of Iodine-oxide Thermite Reaction Products

NASA Astrophysics Data System (ADS)

Russell, Rod; Bless, Stephan; Blinkova, Alexandra; Chen, Tiffany; InstituteAdvanced Tehnology Collaboration; Dept of Molecular Genetics; Microbiology-UT Austin Collaboration; Chemistry; Biochemistry-UT Austin Collaboration

2011-06-01

Iodine pentoxide-aluminum thermite reactions have been driven by impacts at 1000 m/s on steel plates 3 mm or thicker. The activation energy of this material reaction is 197 J/g. The reactivity is increased by reducing grain size. This reaction releases iodine gas that is known to be a sporicide. In order to test the impact reactions for sporicidal effects, reactions took place in closed chambers containing dried Bacillus subtilis spores. The reduction in colony-forming units was dependent on the exposure time; long exposure times resulted in a 105 decrease in germination rate. This was shown to be due to the gas exposure and not the heat or turbulence. Sporicidal effectiveness was increased by adding neodymium and saran resin. The sporicidal effect is very dependent on exposure time, ranging from about 90% kill for times on the order of a second to 99.99% for one-hour times.

Histological changes in male accessory reproductive organs in rats exposed to cigarette smoke and the protective effect of honey supplementation.

PubMed

Mohamed, Mahaneem; Sulaiman, Siti Amrah; Jaafar, Hasnan

2012-01-01

The effect of cigarette smoke (CS) on histology of male accessory reproductive organs and the possible protective effect of honey supplementation in rats were investigated in this study. Rats received distilled water, honey, CS exposure or honey plus CS exposure. Honey (1.2 g/kg body weight/day) was administered by gavage and CS exposure (3 times per day) was done in a chamber for 13 weeks. CS exposure significantly increased relative weight of epididymis and ventral prostate. There were also significantly increased number of clear cells and epithelial height of cauda epididymis as well as severe interstitial oedema and decreased epithelial height of prostate gland. However, with the supplementation of honey, these histological changes were significantly reversed suggesting the protective effect of honey against the toxic effect of CS on male accessory reproductive organs in rats.

EUVL mask dual pods to be used for mask shipping and handling in exposure tools

NASA Astrophysics Data System (ADS)

Gomei, Yoshio; Ota, Kazuya; Lystad, John; Halbmair, Dave; He, Long

2007-03-01

The concept of Extreme Ultra-Violet Lithography (EUVL) mask dual pods is proposed for use in both mask shipping and handling in exposure tools. The inner pod was specially designed to protect masks from particle contamination during shipping from mask houses to wafer factories. It can be installed in a load-lock chamber of exposure tools and evacuated while holding the mask inside. The inner pod upper cover is removed just before the mask is installed to a mask stage. Prototypes were manufactured and tested for shipping and for vacuum cycling. We counted particle adders through these actions with a detectable level of 54 nm and up. The adder count was close to zero, or we can say that the obtained result is within the noise level of our present evaluation environment. This indicates that the present concept is highly feasible for EUVL mask shipping and handling in exposure tools.

An optically stimulated luminescence dosimeter for measuring patient exposure from imaging guidance procedures.

PubMed

Ding, George X; Malcolm, Arnold W

2013-09-07

There is a growing interest in patient exposure resulting from an x-ray imaging procedure used in image-guided radiation therapy. This study explores a feasibility to use a commercially available optically stimulated luminescence (OSL) dosimeter, nanoDot, for estimating imaging radiation exposure to patients. The kilovoltage x-ray sources used for kV-cone-beam CT (CBCT) imaging acquisition procedures were from a Varian on-board imager (OBI) image system. An ionization chamber was used to determine the energy response of nanoDot dosimeters. The chamber calibration factors for x-ray beam quality specified by half-value layer were obtained from an Accredited Dosimetry Calibration Laboratory. The Monte Carlo calculated dose distributions were used to validate the dose distributions measured by using the nanoDot dosimeters in phantom and in vivo. The range of the energy correction factors for the nanoDot as a function of photon energy and bow-tie filters was found to be 0.88-1.13 for different kVp and bow-tie filters. Measurement uncertainties of nanoDot were approximately 2-4% after applying the energy correction factors. The tests of nanoDot placed on a RANDO phantom and on patient's skin showed consistent results. The nanoDot is suitable dosimeter for in vivo dosimetry due to its small size and manageable energy dependence. The dosimeter placed on a patient's skin has potential to serve as an experimental method to monitor and to estimate patient exposure resulting from a kilovoltage x-ray imaging procedure. Due to its large variation in energy response, nanoDot is not suitable to measure radiation doses resulting from mixed beams of megavoltage therapeutic and kilovoltage imaging radiations.

An optically stimulated luminescence dosimeter for measuring patient exposure from imaging guidance procedures

NASA Astrophysics Data System (ADS)

Ding, George X.; Malcolm, Arnold W.

2013-09-01

There is a growing interest in patient exposure resulting from an x-ray imaging procedure used in image-guided radiation therapy. This study explores a feasibility to use a commercially available optically stimulated luminescence (OSL) dosimeter, nanoDot, for estimating imaging radiation exposure to patients. The kilovoltage x-ray sources used for kV-cone-beam CT (CBCT) imaging acquisition procedures were from a Varian on-board imager (OBI) image system. An ionization chamber was used to determine the energy response of nanoDot dosimeters. The chamber calibration factors for x-ray beam quality specified by half-value layer were obtained from an Accredited Dosimetry Calibration Laboratory. The Monte Carlo calculated dose distributions were used to validate the dose distributions measured by using the nanoDot dosimeters in phantom and in vivo. The range of the energy correction factors for the nanoDot as a function of photon energy and bow-tie filters was found to be 0.88-1.13 for different kVp and bow-tie filters. Measurement uncertainties of nanoDot were approximately 2-4% after applying the energy correction factors. The tests of nanoDot placed on a RANDO phantom and on patient's skin showed consistent results. The nanoDot is suitable dosimeter for in vivo dosimetry due to its small size and manageable energy dependence. The dosimeter placed on a patient's skin has potential to serve as an experimental method to monitor and to estimate patient exposure resulting from a kilovoltage x-ray imaging procedure. Due to its large variation in energy response, nanoDot is not suitable to measure radiation doses resulting from mixed beams of megavoltage therapeutic and kilovoltage imaging radiations.

Development of an inhalation system of high melting point metal fumes and its use for exposure of rats to chromium and nickel fumes.

PubMed

Serita, F; Homma, K; Fukuda, K; Sawatari, K; Suzuki, Y; Toya, T

1990-01-01

An experimental inhalation system was developed for fumes generated from powders of high melting point metals such as chromium, nickel, manganese and iron. The system consisted of a plasma flame metal sprayer as a fume generator, a granular bed type fume collector, a fluidized bed aerosol generator, an exposure and a control chamber of a horizontal-flow type and inhalant monitoring and controlling units. Performance of the chambers was ensured by a distribution test using flyash as a test aerosol. Using this system, rats were exposed to chromium fumes for one week or to nickel fumes for two months. The exposure concentrations of the chromium and nickel fumes were 1.85 +/- 0.55 mg/m3 and 0.51 +/- 0.15 mg/m3 (mean +/- SD), near the target levels of 2 mg/m3 and 0.5 mg/m3, respectively. The mass median aerodynamic diameter and the geometric standard deviation of the chromium fumes were 2.1 microns and 2.00, respectively. Those of the nickel fumes were 3.7 microns and 1.74, respectively. Species analysis of these fume particles revealed that 26.4% of the total chromium was hexavalent and the residue was trivalent and that 1-3% of the total nickel was nickel(III) and the residue was nickel(II). Inhaled-metal concentrations in the lungs showed steady increases with the exposure periods and were within the normal range of variation. On the basis of these results, it is concluded that this system is useful for long-term inhalation experiments using high melting point metal fumes.

Psychosocial predator-based animal model of PTSD produces physiological and behavioral sequelae and a traumatic memory four months following stress onset.

PubMed

Zoladz, Phillip R; Park, Collin R; Fleshner, Monika; Diamond, David M

2015-08-01

We have a well-established animal model of PTSD composed of predator exposure administered in conjunction with social instability that produces PTSD-like behavioral and physiological abnormalities one month after stress initiation. Here, we assessed whether the PTSD-like effects would persist for at least 4months after the initiation of the psychosocial stress regimen. Adult male Sprague-Dawley rats were exposed to either 2 or 3 predator-based fear conditioning sessions. During each session, rats were placed in a chamber for a 3-min period that terminated with a 30-s tone, followed by 1h of immobilization of the rats during cat exposure (Day 1). All rats in the stress groups received a second fear conditioning session 10days later (Day 11). Half of the stress rats received a third fear conditioning session 3weeks later (Day 32). The two cat-exposed groups were also exposed to daily unstable housing conditions for the entire duration of the psychosocial stress regimen. The control group received stable (conventional) housing conditions and an equivalent amount of chamber exposure on Days 1, 11 and 32, without cat exposure. Behavioral testing commenced for all groups on Day 116. The stress groups demonstrated increased anxiety on the elevated plus maze, impaired object recognition memory and robust contextual and cued fear conditioned memory 3months after the last conditioning session. Combined data from the two stress groups revealed lower post-stress corticosterone levels and greater diastolic blood pressure relative to the control group. These findings indicate that predator-based psychosocial stress produces persistent PTSD-like physiological and behavioral abnormalities that may provide insight into the neurobiological and endocrine sequelae in traumatized people with PTSD. Copyright © 2015 Elsevier Inc. All rights reserved.

Neurological Effects of Exposure to Non-Hypoxic Hypobaria

DTIC Science & Technology

2014-04-16

be at risk for subclinical brain injury, raising concern about the long-term impact in aircrew. Altitude chamber personnel are a second...flight surgeon FSL BET brain extraction tool FSL FLIRT FMRIB’s linear image registration tool IQ intelligence quotient IRB Institutional Review...population would potentially have similar risks and findings. Chronic brain injury in other neurological diseases is associated with lower

EFFECTS OF ELEVATED CO-2 AND N FERTILIZATION ON FINE ROOT DYNAMICS AND FUNGAL GROWTH IN SEEDLING PINUS PONDEROSA

EPA Science Inventory

The effects of elevated CO-2 and N fertilization on fine root growth of Pinus ponderosa Dougl. ex P. Laws. C. Laws., grown in native soil in open-top field-exposure chambers at Placerville, CA, were monitored for a 2-year period using minirhizotrons. The experimental design was a...

Geometric and material determinants of patterning efficiency by dielectrophoresis.

PubMed

Albrecht, Dirk R; Sah, Robert L; Bhatia, Sangeeta N

2004-10-01

Dielectrophoretic (DEP) forces have been used extensively to manipulate, separate, and localize biological cells and bioparticles via high-gradient electric fields. However, minimization of DEP exposure time is desirable, because of possible untoward effects on cell behavior. Toward this goal, this article investigates the geometric and material determinants of particle patterning kinetics and efficiency. In particular, the time required to achieve a steady-state pattern is theoretically modeled and experimentally validated for a planar, interdigitated bar electrode array energized in a standing-wave configuration. This measure of patterning efficiency is calculated from an improved Fourier series solution of DEP force, in which realistic boundary conditions and a finite chamber height are imposed to reflect typical microfluidic applications. The chamber height, electrode spacing, and fluid viscosity and conductivity are parameters that profoundly affect patterning efficiency, and optimization can reduce electric field exposure by orders of magnitude. Modeling strategies are generalizable to arbitrary electrode design as well as to conditions where DEP force may not act alone to cause particle motion. This improved understanding of DEP patterning kinetics provides a framework for new advances in the development of DEP-based biological devices and assays with minimal perturbation of cell behavior. Copyright 2004 Biophysical Society

Correlative study of functional and structural regeneration of urothelium after chitosan-induced injury.

PubMed

Erman, Andreja; Kerec Kos, Mojca; Žakelj, Simon; Resnik, Nataša; Romih, Rok; Veranič, Peter

2013-11-01

High transepithelial electrical resistance (TEER) demonstrates a functional permeability barrier of the normal urothelium, which is maintained by a layer of highly differentiated superficial cells. When the barrier is challenged, a quick regeneration is induced. We used side-by-side diffusion chambers as an ex vivo system to determine the time course of functional and structural urothelial regeneration after chitosan-induced injury. The exposure of the urothelium to chitosan caused a 60 % decrease in TEER, the exposure of undifferentiated urothelial cells to the luminal surface and leaky tight junctions. During the regeneration period (350 min), TEER recovered to control values after approximately 200 min, while structural regeneration continued until 350 min after injury. The tight junctions are the earliest and predominant component of the barrier to appear, while complete barrier regeneration is achieved by delayed superficial cell terminal differentiation. The barrier function and the structure of untreated urothelium were unaffected in side-by-side diffusion chambers for at least 6 h. The urinary bladder tissue excised from an animal thus retains the ability to maintain and restore the transepithelial barrier and cellular ultrastructure for a sufficient period to allow for studies of regeneration in ex vivo conditions.

Geometric and Material Determinants of Patterning Efficiency by Dielectrophoresis

PubMed Central

Albrecht, Dirk R.; Sah, Robert L.; Bhatia, Sangeeta N.

2004-01-01

Dielectrophoretic (DEP) forces have been used extensively to manipulate, separate, and localize biological cells and bioparticles via high-gradient electric fields. However, minimization of DEP exposure time is desirable, because of possible untoward effects on cell behavior. Toward this goal, this article investigates the geometric and material determinants of particle patterning kinetics and efficiency. In particular, the time required to achieve a steady-state pattern is theoretically modeled and experimentally validated for a planar, interdigitated bar electrode array energized in a standing-wave configuration. This measure of patterning efficiency is calculated from an improved Fourier series solution of DEP force, in which realistic boundary conditions and a finite chamber height are imposed to reflect typical microfluidic applications. The chamber height, electrode spacing, and fluid viscosity and conductivity are parameters that profoundly affect patterning efficiency, and optimization can reduce electric field exposure by orders of magnitude. Modeling strategies are generalizable to arbitrary electrode design as well as to conditions where DEP force may not act alone to cause particle motion. This improved understanding of DEP patterning kinetics provides a framework for new advances in the development of DEP-based biological devices and assays with minimal perturbation of cell behavior. PMID:15454417

Ozone deposition velocities, reaction probabilities and product yields for green building materials

NASA Astrophysics Data System (ADS)

Lamble, S. P.; Corsi, R. L.; Morrison, G. C.

2011-12-01

Indoor surfaces can passively remove ozone that enters buildings, reducing occupant exposure without an energy penalty. However, reactions between ozone and building surfaces can generate and release aerosols and irritating and carcinogenic gases. To identify desirable indoor surfaces the deposition velocity, reaction probability and carbonyl product yields of building materials considered green (listed, recycled, sustainable, etc.) were quantified. Nineteen separate floor, wall or ceiling materials were tested in a 10 L, flow-through laboratory reaction chamber. Inlet ozone concentrations were maintained between 150 and 200 ppb (generally much lower in chamber air), relative humidity at 50%, temperature at 25 °C and exposure occurred over 24 h. Deposition velocities ranged from 0.25 m h -1 for a linoleum style flooring up to 8.2 m h -1 for a clay based paint; reaction probabilities ranged from 8.8 × 10 -7 to 6.9 × 10 -5 respectively. For all materials, product yields of C 1 thru C 12 saturated n-aldehydes, plus acetone ranged from undetectable to greater than 0.70 The most promising material was a clay wall plaster which exhibited a high deposition velocity (5.0 m h -1) and a low product yield (

A new field-laboratory methodology for assessing human response to noise

NASA Technical Reports Server (NTRS)

Borsky, P. N.

1973-01-01

Gross measures of community annoyance with intrusive noises have been made in a number of real environment surveys which indicate that aircraft noise may have to be reduced 30-40 EPNdb before it will generally be considered acceptable. Interview studies, however, cannot provide the precise information which is needed by noise abatement engineers of the variable human response to different types and degrees of noise exposure. A new methodological field-survey approach has been developed to provide such information. The integrated attitudes and experiences of a random sample of subjects in the real environment are obtained by a prior field survey. Then these subjects record their more precise responses to controlled noise exposures in a new realistic laboratory. The laboratory is a sound chamber furnished as a typical living room (18 ft x 14 ft) and subjects watch a color TV program while they judge simulated aircraft flyovers that occur at controlled levels and intervals. Methodological experiments indicate that subjects in the laboratory have the sensation that the airplanes are actually moving overhead across the ceiling of the chamber. It was also determined that annoyance judgments in the laboratory stabilize after three flyovers are heard prior to a judgment of annoyance.

Antinociception induced by chronic exposure of rats to cigarette smoke.

PubMed

Anderson, Kenton L; Pinkerton, Kent E; Uyeminami, Dale; Simons, Christopher T; Carstens, Mirela Iodi; Carstens, E

2004-08-05

To investigate if chronic exposure to cigarette smoke induces analgesia, rats were exposed to concentrated cigarette smoke in an environmental chamber over four successive 5-day blocks (6 h/day), with 2 smoke-free days between blocks. A control group was exposed to room air. Tail flick latencies increased significantly (analgesia) during each smoke exposure block, with a relative decline in analgesia across blocks (tolerance) and a return to control levels during the first three smoke-free interludes while remaining higher after the conclusion of the 4-week exposure period. Mechanical (von Frey) withdrawal thresholds declined over time in smoke-exposed and control groups, with the smoke-exposed group showing significantly lower thresholds. Plasma nicotine reached 95.4 +/- 32 (S.D.) ng/ml at the end of weekly smoke exposure and declined to 44.9 +/- 10.6 ng/ml 24 h after withdrawal. Rats lost weight during smoke exposure and quickly regained weight during smoke-free interludes and at the cessation of smoke exposure. Analgesia may contribute to the initiation of smoking, and rapid reversal of the analgesic effect following acute exposure may contribute to the difficulty in quitting smoking.

Selective functionalization of carbon nanotubes based upon distance traveled

NASA Technical Reports Server (NTRS)

Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

2010-01-01

Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H.sub.2 or NH.sub.3 or NF.sub.3 or F.sub.2 or CF.sub.4 or C.sub.nH.sub.m) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. The predominant species that are deposited on the CNT array vary with the distance d measured along a path from the precursor gas to the CNT array; two or three different predominant species can be deposited on a CNT array for distances d=d1 and d=d2>d1 and d=d3>d2.

Acoustic Cluster Therapy: In Vitro and Ex Vivo Measurement of Activated Bubble Size Distribution and Temporal Dynamics.

PubMed

Healey, Andrew John; Sontum, Per Christian; Kvåle, Svein; Eriksen, Morten; Bendiksen, Ragnar; Tornes, Audun; Østensen, Jonny

2016-05-01

Acoustic cluster technology (ACT) is a two-component, microparticle formulation platform being developed for ultrasound-mediated drug delivery. Sonazoid microbubbles, which have a negative surface charge, are mixed with micron-sized perfluoromethylcyclopentane droplets stabilized with a positively charged surface membrane to form microbubble/microdroplet clusters. On exposure to ultrasound, the oil undergoes a phase change to the gaseous state, generating 20- to 40-μm ACT bubbles. An acoustic transmission technique is used to measure absorption and velocity dispersion of the ACT bubbles. An inversion technique computes bubble size population with temporal resolution of seconds. Bubble populations are measured both in vitro and in vivo after activation within the cardiac chambers of a dog model, with catheter-based flow through an extracorporeal measurement flow chamber. Volume-weighted mean diameter in arterial blood after activation in the left ventricle was 22 μm, with no bubbles >44 μm in diameter. After intravenous administration, 24.4% of the oil is activated in the cardiac chambers. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Effects of aqueous humor hydrodynamics on human eye heat transfer under external heat sources.

PubMed

Tiang, Kor L; Ooi, Ean H

2016-08-01

The majority of the eye models developed in the late 90s and early 00s considers only heat conduction inside the eye. This assumption is not entirely correct, since the anterior and posterior chambers are filled aqueous humor (AH) that is constantly in motion due to thermally-induced buoyancy. In this paper, a three-dimensional model of the human eye is developed to investigate the effects AH hydrodynamics have on the human eye temperature under exposure to external heat sources. If the effects of AH flow are negligible, then future models can be developed without taking them into account, thus simplifying the modeling process. Two types of external thermal loads are considered; volumetric and surface irradiation. Results showed that heat convection due to AH flow contributes to nearly 95% of the total heat flow inside the anterior chamber. Moreover, the circulation inside the anterior chamber can cause an upward shift of the location of hotspot. This can have significant consequences to our understanding of heat-induced cataractogenesis. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Dark matter search results from the PICO-2L C$$_3$$F$$_8$$ bubble chamber

DOE PAGES

Amole, C.

2015-06-11

New data are reported from the operation of a 2 liter C 3F 8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C 3F 8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of < 3.5 × 10 –10 and an alpha rejection factor of > 98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed duringmore » the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. Lastly, these data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.« less

Lymphocyte proliferation in mice after a full laparotomy is the same whether performed in a sealed carbon dioxide chamber or in room air.

PubMed

Lee, S W; Southall, J C; Gleason, N R; Huang, E H; Bessler, M; Whelan, R L

2000-03-01

Our laboratory has demonstrated that significantly more cell-mediated immunosuppression occurs after full laparotomy than after either anesthesia control or carbon dioxide (CO2) pneumoperitoneum. We further demonstrated that the postoperative immunosuppression is related to the length of the incision. Other investigators believe that the immunosuppression observed after laparotomy is caused by peritoneal exposure to small amounts of lipopolysaccharide found in circulating air. They believe that the better-preserved immune function associated with laparoscopic surgery results from the avoidance of air contamination of the peritoneal cavity. To investigate this hypothesis, we determined and compared postoperative lymphocyte proliferation rates after (a) laparotomy in room air, (b) laparotomy in a CO2 chamber, (c) CO2 insufflation in a murine model, and (d) anesthesia alone. Female C3H/He mice (n = 21) were divided randomly into four groups: (a) anesthesia control, (b) air laparotomy, (c) CO2 laparotomy, and (d) CO2 insufflation. The control mice underwent no procedure. The group 2 animals underwent a full midline incision (xiphoid to pubis) and exposure to room air for 20 min and then were clipped closed. The group 3 mice underwent a full midline incision in a sealed CO2 chamber for 20 min, and the group 4 mice insufflation with CO2 gas at 4 to 6 mm Hg for 20 min. Splenocytes were harvested from all the animals on day 2 after the interventions. Lymphocyte proliferation then was assessed using the nonradioactive colorimetric MTS/PMS system 72 h after concanavalin-A stimulation. There was no significant difference in lymphocyte proliferation between the air and CO2 laparotomy groups. Lymphocyte proliferation in the anesthesia control and CO2 insufflation groups was significantly higher than in both the air laparotomy (p<0.05) and CO2 laparotomy (p<0.05) groups (p values by Tukey-Kramer test). There was no significant difference between the anesthesia control and CO2 pneumoperitoneum groups. Our results suggest that full laparotomy performed in a sealed CO2 chamber compared to room air laparotomy resulted in similar suppression of lymphocyte proliferation. Furthermore, no significant suppression of lymphocyte proliferation was observed in the CO2 pneumoperitoneum group. These results, with regard to lymphocyte proliferation rates, refute the hypothesis that postoperative immunosuppression is related to air exposure and support the alternative hypothesis that immunosuppression is related to incision length.

Comparison of short-term chronic and chronic silver toxicity to fathead minnows in unamended and sodium chloride-amended waters.

PubMed

Naddy, Rami B; Rehner, Anita B; McNerney, Gina R; Gorsuch, Joseph W; Kramer, James R; Wood, Chris M; Paquin, Paul R; Stubblefield, William A

2007-09-01

The chronic (early life stage [ELS]) and short-term chronic (STC) toxicity of silver (as silver nitrate) to fathead minnows (FHM) was determined concurrently in flow-through exposures (33 volume additions/d). Paired ELS (approximately 30 d) and STC (7 d) studies were conducted with and without the addition of 60 mg/L Cl (as NaCl). The paired studies in unamended water were later repeated using standard flow conditions (9 volume additions/d). The purpose of the paired studies was to determine if short-term chronic endpoints can be used to predict effects in ELS studies. For each experiment, a "split-chamber" design (organisms were held in a common exposure chamber) allowed the direct comparison between short-term and chronic exposures. It appeared that the chronic toxicity of silver was mitigated to some extent by NaCl addition. The maximum acceptable toxicant concentration for growth in the ELS study was 0.53 microg dissolved Ag/L under standard flow conditions. Early life stage and STC endpoints in all three studies typically agreed within a factor of two. Whole-body sodium and silver concentrations measured in individual fathead minnows during these studies showed an increase in silver body burdens and a decrease in sodium concentration. These results indicate that the STC study could be used as a surrogate test to estimate chronic toxicity and that the mechanism of chronic silver toxicity may be the same as for acute toxicity.

Establishment of Airborne Nanoparticle Exposure Chamber System to Assess Nano TiO2 Induced Mice Lung Effects

NASA Astrophysics Data System (ADS)

Chen, Chia-Hua; Li, Jui-Ping; Huang, Nai-Chun; Yang, Chung-Shi; Chen, Jen-Kun

2011-12-01

A great many governments have schemed their top priority to support the research and development of emerging nanotechnology, which lead to increasing products containing nanomaterials. However, platforms and protocols to evaluate the safety of nanomaterials are not yet established. We therefore design and fabricate a nanoparticle exposure chamber system (NECS) and try to standardize protocols to assess potential health risk of inhalable nanoparticles. This platform comprises: (1) nano-aerosol generators to produce homogeneous airborne nanoparticles, (2) double isolated container to prevent from unexpected exposure to humans, (3) gas supply system for housing animals or incubating cultured cells, and (4) system for automatic control and airborne nanoparticle analysis. The NECS providing multiple functions includes: (1) a secure environment to handle nanomaterials, (2) real-time measurement for the size and distribution of airborne nanoparticles, (3) SOP of safety evaluation for nanomaterials, and (4) key technology for the development of inhalable pharmaceuticals. We used NECS to mimic occupational environment for exploring potential adverse effects of TiO2 nanoparticles. The adult male ICR mice were exposed to 25nm, well-characterized TiO2 particles for 1 and 4 weeks. More than 90% of the inhaled TiO2 nanoparticles deposit in lung tissue, which tends to be captured by alveolar macrophages. Pulmonary function test does not show significant physiological changes between one and 4 weeks exposure. For plasma biochemistry analysis, there are no obvious inflammation responses after exposure for one and 4 weeks; however, disruption of alveolar septa and increased thickness of alveolar epithelial cells were observed. According to our results, the NECS together with our protocols show comprehensive integration and ideally fit the standard of OECD guildelines-TG403, TG412, TG413; it can be further customized to fulfill diverse demands of industry, government, and third party contract research organization (CRO).

The seaweeds Fucus vesiculosus and Ascophyllum nodosum are significant contributors to coastal iodine emissions

NASA Astrophysics Data System (ADS)

Huang, R.-J.; Thorenz, U. R.; Kundel, M.; Venables, D. S.; Ceburnis, D.; Ho, K. F.; Chen, J.; Vogel, A. L.; Küpper, F. C.; Smyth, P. P. A.; Nitschke, U.; Stengel, D. B.; Berresheim, H.; O'Dowd, C. D.; Hoffmann, T.

2013-05-01

Based on the results of a pilot study in 2007, which found high mixing ratios of molecular iodine (I2) above the intertidal macroalgae (seaweed) beds at Mweenish Bay (Ireland), we extended the study to nine different locations in the vicinity of Mace Head Atmospheric Research Station on the west coast of Ireland during a field campaign in 2009. The mean values of \\chem{I_2} mixing ratio found above the macroalgae beds at nine different locations ranged from 104 to 393 ppt, implying a high source strength of I2. Such mixing ratios are sufficient to result in photochemically driven coastal new-particle formation events. Mixing ratios above the Ascophyllum nodosum and Fucus vesiculosus beds increased with exposure time: after 6 h exposure to ambient air the mixing ratios were one order of magnitude higher than those initially present. This contrasts with the emission characteristics of Laminaria digitata, where most I2 was emitted within the first half hour of exposure. Discrete in situ measurements (offline) of I2 emission from ambient air-exposed chamber experiments of L. digitata, A. nodosum and F. vesiculosus substantially supported the field observations. Further online and time-resolved measurements of the I2 emission from O3-exposed macroalgal experiments in a chamber confirmed the distinct I2 emission characteristics of A. nodosum and F. vesiculosus compared to those of L. digitata. The emission rates of A. nodosum and F. vesiculosus were comparable to or even higher than L. digitata after the initial exposure period of 20-30 min. We suggest that A. nodosum and F. vesiculosus may provide an important source of photolabile iodine in the coastal boundary layer and that their impact on photochemistry and coastal new-particle formation should be reevaluated in light of their longer exposure at low tide and their widespread distribution.

Small spatial variability in methane emission measured from a wet patterned boreal bog

NASA Astrophysics Data System (ADS)

Korrensalo, Aino; Männistö, Elisa; Alekseychik, Pavel; Mammarella, Ivan; Rinne, Janne; Vesala, Timo; Tuittila, Eeva-Stiina

2018-03-01

We measured methane fluxes of a patterned bog situated in Siikaneva in southern Finland from six different plant community types in three growing seasons (2012-2014) using the static chamber method with chamber exposure of 35 min. A mixed-effects model was applied to quantify the effect of the controlling factors on the methane flux. The plant community types differed from each other in their water level, species composition, total leaf area (LAITOT) and leaf area of aerenchymatous plant species (LAIAER). Methane emissions ranged from -309 to 1254 mg m-2 d-1. Although methane fluxes increased with increasing peat temperature, LAITOT and LAIAER, they had no correlation with water table or with plant community type. The only exception was higher fluxes from hummocks and high lawns than from high hummocks and bare peat surfaces in 2013 and from bare peat surfaces than from high hummocks in 2014. Chamber fluxes upscaled to ecosystem level for the peak season were of the same magnitude as the fluxes measured with the eddy covariance (EC) technique. In 2012 and in August 2014 there was a good agreement between the two methods; in 2013 and in July 2014, the chamber fluxes were higher than the EC fluxes. Net fluxes to soil, indicating higher methane oxidation than production, were detected every year and in all community types. Our results underline the importance of both LAIAER and LAITOT in controlling methane fluxes and indicate the need for automatized chambers to reliably capture localized events to support the more robust EC method.

Book Preservation

NASA Technical Reports Server (NTRS)

1980-01-01

Books produced since 1850, held in the Library of Congress, have a very high acid content, hence a shorter life expectancy than prior-published volumes. A means of "deacidifying" books on a large, economically-viable scale is of great interest, particularly to the research library community, which stores millions of valuable, often irreplaceable documents. The General Electric vacuum chamber used in deacidification tests serves a dual purpose. It creates an environment in which DEZ can do its job without presence of oxygen and also dries the books. After the drying phase, DEZ is introduced to the chamber as a paper-penetrating vapor. The complete process typically takes eight days, four days for vacuum drying and four days of book exposure to DEZ. Accelerated aging tests showed that the process can extend paper life almost fourfold, even on color illustrations.

Use of an Anaerobic Chamber Environment for the Assay of Endogenous Cellular Protein-Tyrosine Phosphatase Activities

PubMed Central

Zhu, Li

2002-01-01

Protein-tyrosine phosphatases (PTPases) have a catalytic cysteine residue whose reduced state is integral to the reaction mechanism. Since exposure to air can artifactually oxidize this highly reactive thiol, PTPase assays have typically used potent reducing agents to reactivate the enzymes present; however, this approach does not allow for the measurement of the endogenous PTPase activity directly isolated from the in vivo cellular environment. Here we provide a method for using an anaerobic chamber to preserve the activity of the total PTPase complement in a tissue lysate or of an immunoprecipitated PTPase homolog to characterize their endogenous activation state. Comparison with a sample treated with biochemical reducing agents allows the determination of the activatable (reducible) fraction of the endogenous PTPase pool. PMID:12734574

The Effect of Olfactory Exposure to Non-Insecticidal Agrochemicals on Bumblebee Foraging Behavior

PubMed Central

Sprayberry, Jordanna D. H.; Ritter, Kaitlin A.; Riffell, Jeffrey A.

2013-01-01

Declines in bumblebee populations have led to investigations into potential causes – including agrochemical effects on bumblebee physiology. The indirect effects of agrochemicals (i.e. behavior modulation) have been postulated, but rarely directly tested. Olfactory information is critical in mediating bumblebee-floral interactions. As agrochemicals emit volatiles, they may indirectly modify foraging behavior. We tested the effects of olfactory contamination of floral odor by agrochemical scent on foraging activity of Bombus impatiens using two behavioral paradigms: localization of food within a maze and forced-choice preference. The presence of a fungicide decreased bumblebees’ ability to locate food within a maze. Additionally, bumblebees preferred to forage in non-contaminated feeding chambers when offered a choice between control and either fertilizer- or fungicide-scented chambers. PMID:24204608

Characterization of Vinyl Ester Composites Filled with Carbonized Jatropha seed shell: effect of accelerated weathering

NASA Astrophysics Data System (ADS)

Sri Aprilia, N. A.; Khalil, H. P. S. Abdul; Amin, Amri; Meurah Rosnelly, Cut; Fathanah, Ummi; Mariana

2018-05-01

The effect of accelerated weathering test of carbonized jatropha seed shell filled vinyl ester biocomposites was investigated. In this study, four loading of carbonized jatropha seed shell and one without loading of vinyl ester biocomposites were used. The samples exposure at several circles time in QUV chamber. The durability of vinyl ester biocomposites filled carbonized jatropha seed shell changes in mechanical properties and weight loss during exposure in UV and condensation. The tensile test and flexural indicated decrease with increasing of carbonized jatropha seed shell loading. The SEM fracture surface of biocomposites looks rough and some carbonized out of the matrix.

Numerical modeling of heat and mass transfer in the human eye under millimeter wave exposure.

PubMed

Karampatzakis, Andreas; Samaras, Theodoros

2013-05-01

Human exposure to millimeter wave (MMW) radiation is expected to increase in the next several years. In this work, we present a thermal model of the human eye under MMW illumination. The model takes into account the fluid dynamics of the aqueous humor and predicts a frequency-dependent reversal of its flow that also depends on the incident power density. The calculated maximum fluid velocity in the anterior chamber and the temperature rise at the corneal apex are reported for frequencies from 40 to 100 GHz and different values of incident power density. Copyright © 2013 Wiley Periodicals, Inc.

Toxic volatile organic compounds in environmental tobacco smoke: Emission factors for modeling exposures of California populations

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

Daisey, J.M.; Mahanama, K.R.R.; Hodgson, A.T.

The primary objective of this study was to measure emission factors for selected toxic air contaminants in environmental tobacco smoke (ETS) using a room-sized environmental chamber. The emissions of 23 volatile organic compounds (VOCs), including, 1,3-butadiene, three aldehydes and two vapor-phase N-nitrosamines were determined for six commercial brands of cigarettes and reference cigarette 1R4F. The commercial brands were selected to represent 62.5% of the cigarettes smoked in California. For each brand, three cigarettes were machine smoked in the chamber. The experiments were conducted over four hours to investigate the effects of aging. Emission factors of the target compounds were alsomore » determined for sidestream smoke (SS). For almost all target compounds, the ETS emission factors were significantly higher than the corresponding SS values probably due to less favorable combustion conditions and wall losses in the SS apparatus. Where valid comparisons could be made, the ETS emission factors were generally in good agreement with the literature. Therefore, the ETS emission factors, rather than the SS values, are recommended for use in models to estimate population exposures from this source. The variabilities in the emission factors ({mu}g/cigarette) of the selected toxic air contaminants among brands, expressed as coefficients of variation, were 16 to 29%. Therefore, emissions among brands were Generally similar. Differences among brands were related to the smoked lengths of the cigarettes and the masses of consumed tobacco. Mentholation and whether a cigarette was classified as light or regular did not significantly affect emissions. Aging was determined not to be a significant factor for the target compounds. There were, however, deposition losses of the less volatile compounds to chamber surfaces.« less

Inflammatory Response of Human Gestational Membranes to Ureaplasma parvum Using a Novel Dual-Chamber Tissue Explant System.

PubMed

Potts, Lauren C; Feng, Liping; Seed, Patrick C; Jayes, Friederike L; Kuchibhatla, Maragatha; Antczak, Brian; Nazzal, Matthew K; Murtha, Amy P

2016-05-01

Preterm premature rupture of membranes (PPROM) is often associated with intra-amniotic inflammation and infection. Current understanding of the pathogenesis of PPROM includes activation of pro-inflammatory cytokines and proteolytic enzymes leading to compromise of membrane integrity. The impact of exposure to bacterial pathogens, including Ureaplasma parvum, on gestational membranes is poorly understood. Our objective was to develop a dual-chamber system to characterize the inflammatory response of gestational membranes to U. parvum in a directional nature. Full-thickness human gestational membrane explants, with either choriodecidua or amnion oriented superiorly, were suspended between two washers in a cylindrical device, creating two distinct compartments. Brilliant green dye was introduced into the top chamber to assess the integrity of the system. Tissue viability was evaluated after 72 h using a colorimetric cell proliferation assay. Choriodecidua or amnion was exposed to three doses of U. parvum and incubated for 24 h. Following treatment, media from each compartment were used for quantification of U. parvum (quantitative PCR), interleukin (IL)-8 (enzyme-linked immunosorbent assay), and matrix metalloproteinase (MMP)-2 and MMP-9 activity (zymography). We observed that system integrity and explant viability were maintained over 72 h. Dose-dependent increases in recovered U. parvum, IL-8 concentration, and MMP-2 activity were detected in both compartments. Significant differences in IL-8 concentration and MMP-9 activity were found between the choriodecidua and amnion. This tissue explant system can be used to investigate the inflammatory consequences of directional bacterial exposure for gestational membranes and provides insight into the pathogenesis of PPROM and infectious complications of pregnancy. © 2016 by the Society for the Study of Reproduction, Inc.

Changes in southern Piedmont grassland community structure and nutritive quality with future climate scenarios of elevated tropospheric ozone and altered rainfall patterns.

PubMed

Gilliland, N J; Chappelka, A H; Muntifering, R B; Ditchkoff, S S

2016-01-01

Forage species common to the southern USA Piedmont region, Lolium arundinacea, Paspalum dilatatum, Cynodon dactylon and Trifolium repens, were established in a model pasture system to test the future climate change scenario of increasing ozone exposure in combination with varying rainfall amounts on community structure and nutritive quality. Forages were exposed to two levels of ozone [ambient (non-filtered; NF) and twice ambient (2×) concentrations] with three levels of precipitation (average or ±20% of average) in modified open-top chambers (OTCs) from June to September 2009. Dry matter (DM) yield did not differ over the growing season between forage types, except in primary growth grasses where DM yield was higher in 2× than NF treatment. Primary growth clover decreased in nutritive quality in 2× ozone because of increased concentrations of neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL). Re-growth clover exhibited the largest decrease in nutritive quality, whereas grasses were not adversely affected in 2× ozone. Re-growth grasses responded positively to 2× ozone exposure, as indicated in increased relative food value (RFV) and percentage crude protein (CP) than NF-exposed re-growth grasses. Effects of precipitation were not significant over the growing season for primary or re-growth forage, except in primary growth grasses where DM yield was higher in chambers with above average (+20%) precipitation. Total canopy cover was significantly higher over the growing season in chambers receiving above average precipitation, but no significant effects were observed with ozone. Results indicate shifts in plant community structure and functioning related to mammalian herbivore herbivory in future climate change scenarios. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

Toxic Volatile Organic Compounds in Environmental Tobacco Smoke:Emission Factors for Modeling Exposures of California Populations

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

Daisey, J.M.; Mahanama, K.R.R.; Hodgson, A.T.

The primary objective of this study was to measure emission factors for selected toxic air in environmental tobacco smoke (ETS) using a room-sized environmental chamber. The emissions of 23 volatile organic compounds (VOCs), including 1,3-butadiene, three aldehydes and two vapor-phase N-nitrosarnines were determined for six commercial brands of cigarettes and reference cigarette 1R4F. The commercial brands were selected to represent 62.5% of the cigarettes smoked in California. For each brand, three cigarettes were machine smoked in the chamber. The experiments were conducted over four hours to investigate the effects of aging. Emission factors of the target compounds were also determinedmore » for sidestream smoke (SS). For almost all target compounds, the ETS emission factors were significantly higher than the corresponding SS values probably due to less favorable combustion conditions and wall losses in the SS apparatus. Where valid comparisons could be made, the ETS emission factors were generally in good agreement with the literature. Therefore, the ETS emission factors, rather than the SS values, are recommended for use in models to estimate population exposures from this source. The variabilities in the emission factors (pgkigarette) of the selected toxic air contaminants among brands, expressed as coefficients of variation, were 16 to 29%. Therefore, emissions among brands were generally similar. Differences among brands were related to the smoked lengths of the cigarettes and the masses of consumed tobacco. Mentholation and whether a cigarette was classified as light or regular did not significantly affect emissions. Aging was determined not to be a significant factor for the target compounds. There were, however, deposition losses of the less volatile compounds to chamber surfaces.« less

Evidence for less irritation to the peritoneal membrane in rats dialyzed with solutions low in glucose degradation products.

PubMed

Wieczorowska-Tobis, Katarzyna; Brelinska, Renata; Witowski, Janusz; Passlick-Deetjen, Jutta; Schaub, Thomas P; Schilling, Holger; Breborowicz, Andrzej

2004-01-01

Acidic pH and the presence of glucose degradation products (GDP) are believed to compromise the biocompatibility of peritoneal dialysis fluids (PDF). The present study examines the effects of long-term exposure to GDP and low pH by comparing conventional PDF and a new, neutral pH, low GDP solution. All experiments were performed using a chronic infusion model of dialysis in nonuremic rats. The animals were treated for 6 weeks with 2 daily injections of 4.25% glucose-containing PDF. The following PDF were tested: CAPD3 (single-chamber bag, low pH, high GDP), CAPD3 pH 7.4 (single-chamber bag, neutral pH, high GDP), CAPD3-Balance (double-chamber bag, neutral pH, low GDP). All test solutions were obtained from Fresenius Medical Care, Bad Homburg, Germany. After 6 weeks of exposure, peritoneal permeability to water, urea, creatinine, glucose, and sodium, assessed by peritoneal equilibration test, was similar in all groups. However, compared to other PDF, dialysis with CAPD3-Balance was associated with reduced concentrations of protein and hyaluronan in the dialysate, decreased peritoneal eosinophilia, and reduced dialysate levels of chemokines CCL2/MCP-1 and CCL5/RANTES. Morphologic changes in the peritoneal membrane of CAPD3-Balance-treated animals were much less pronounced and included reduced vascular density, preservation of the mesothelial monolayer and intercellular junction, and no reduplication of the submesothelial basement membrane. A new generation of PDF with physiologic pH and low GDP level produce less irritation to the peritoneal membrane and better preserve its structural integrity. This effect seems to be related predominantly to minimized GDP concentrations.

Bayesian Modeling of Exposure and Airflow Using Two-Zone Models

PubMed Central

Zhang, Yufen; Banerjee, Sudipto; Yang, Rui; Lungu, Claudiu; Ramachandran, Gurumurthy

2009-01-01

Mathematical modeling is being increasingly used as a means for assessing occupational exposures. However, predicting exposure in real settings is constrained by lack of quantitative knowledge of exposure determinants. Validation of models in occupational settings is, therefore, a challenge. Not only do the model parameters need to be known, the models also need to predict the output with some degree of accuracy. In this paper, a Bayesian statistical framework is used for estimating model parameters and exposure concentrations for a two-zone model. The model predicts concentrations in a zone near the source and far away from the source as functions of the toluene generation rate, air ventilation rate through the chamber, and the airflow between near and far fields. The framework combines prior or expert information on the physical model along with the observed data. The framework is applied to simulated data as well as data obtained from the experiments conducted in a chamber. Toluene vapors are generated from a source under different conditions of airflow direction, the presence of a mannequin, and simulated body heat of the mannequin. The Bayesian framework accounts for uncertainty in measurement as well as in the unknown rate of airflow between the near and far fields. The results show that estimates of the interzonal airflow are always close to the estimated equilibrium solutions, which implies that the method works efficiently. The predictions of near-field concentration for both the simulated and real data show nice concordance with the true values, indicating that the two-zone model assumptions agree with the reality to a large extent and the model is suitable for predicting the contaminant concentration. Comparison of the estimated model and its margin of error with the experimental data thus enables validation of the physical model assumptions. The approach illustrates how exposure models and information on model parameters together with the knowledge of uncertainty and variability in these quantities can be used to not only provide better estimates of model outputs but also model parameters. PMID:19403840

Growth of five families of Pinus taeda L. during three years of ozone exposure

Treesearch

M.B. Adams; J.M. Kelly; G.E. Taylor; N.T. Edwards

1990-01-01

Loblolly pine (Pinus taeda L.) seedlings of five half-sib families were grown for 3 yr in the field in open-top chambers. The seedlings were fumigated during the growing seasons (approximately April-October) with ozone at the following target levels: subambient (CF), ambient (AMB), and ambient+ 60 ppb (AMB+). At the end of the three growing seasons...

Microgravity Simulation Facility (MSF)

NASA Technical Reports Server (NTRS)

Richards, Stephanie E. (Compiler); Levine, Howard G.; Zhang, Ye

2016-01-01

The Microgravity Simulator Facility (MSF) at Kennedy Space Center (KSC) was established to support visiting scientists for short duration studies utilizing a variety of microgravity simulator devices that negate the directional influence of the "g" vector (providing simulated conditions of micro or partial gravity). KSC gravity simulators can be accommodated within controlled environment chambers allowing investigators to customize and monitor environmental conditions such as temperature, humidity, CO2, and light exposure.

The Effects of Behavioral History on Response Acquisition with Immediate and Delayed Reinforcement

ERIC Educational Resources Information Center

Snycerski, Susan; Laraway, Sean; Huitema, Bradley E.; Poling, Alan

2004-01-01

Effects of prior exposure to the experimental chamber with levers present or absent and variable-time (VT) 60-s water deliveries arranged during one, five, or no 1-hr sessions were examined in rats during a 6-hr response-acquisition session in which presses on one lever produced water delivery immediately or after a 15-s resetting delay, and…

7 CFR 319.41-5a - Administrative instructions; method used for the disinfection of imported broomcorn and broomcorn...

Code of Federal Regulations, 2010 CFR

2010-01-01

.... (1) The temperature of the stalks and of the fumigation chamber during the fumigation shall be not less than 60 °F. (2) The dosage for the fumigation shall be 3 pounds of liquid hydrocyanic acid or its... acid shall be introduced and the low pressure held for the duration of the fumigation. (4) The exposure...

Ozone exposure-response curves for tree species in Great Smoky Mountains National Park: A re-evaluation of how potential impacts may have changed over the past 25 years

EPA Science Inventory

Seedlings of tree species native to Great Smoky Mountains National Park were exposed to ozone in open-top chambers for one or two growing seasons. Species used were red maple (Acer rubrum), chestnut oak (Quercus prinus), black locust (Robinia pseudoacadia), winged sumac (Rhus co...

Towards the development of an autocontamination trap system to manage populations of emerald ash borer (Coleoptera: Buprestidae) with the native entomopathogenic fungus, Beauveria bassiana.

PubMed

Lyons, D Barry; Iavallée, Robert; Kyei-Poku, George; Van Frankenhuyzen, Kees; Johny, Shajahan; Guertin, Claude; Francese, Joseph A; Jones, Gene C; Blais, Martine

2012-12-01

Emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) is an invasive species from Asia that was discovered in North America Canada, in 2002. Herein, we describe studies to develop an autocontamination trapping system to disseminate Beauveria bassiana to control beetle populations. The standard trap for emerald ash borer in Canada is a light green prism trap covered in an insect adhesive and baited with (Z)-3-hexenol. We compared of green multifunnel traps, green intercept panel traps (both with and without fluon coating) and green prism traps for capturing emerald ash borer in a green ash plantation. The coated green multifunnel traps captured significantly more males and more females than any other trap design. We examined the efficacy of two native B. bassiana isolates, INRS-CFL and L49-1AA. In a field experiment the INRS-CFL isolate attached to multifunnel traps in autocontamination chambers retained its pathogenicity to emerald ash borer adults for up to 43 d of outdoor exposure. Conidia germination of the INRS-CFL isolate was >69% after outdoor exposure in the traps for up to 57 d. The L49-1AA isolate was not pathogenic in simulated trap exposures and the germination rate was extremely low (<5.3%). Mean (+/- SEM) conidia loads on ash borer adults after being autocontaminated in the laboratory using pouches that had been exposed in traps out of doors for 29 d were 579,200 (+/- 86,181) and 2,400 (+/- 681) for the INRS-CFL and the LA9-1AA isolates, respectively. We also examined the fungal dissemination process under field conditions using the L49-1AA isolate in a green ash plantation. Beetles were lured to baited green multifunnel traps with attached autocontamination chambers. Beetles acquired fungal conidia from cultures growing on pouches in the chambers and were recaptured on Pestick-coated traps. In total, 2,532 beetles were captured of which 165 (6.5%) had fungal growth that resembled B. bassiana. Of these 25 beetles were positive for the L49-1AA isolate.

The link between organic aerosol mass loading and degree of oxygenation: an α-pinene photooxidation study

NASA Astrophysics Data System (ADS)

Pfaffenberger, L.; Barmet, P.; Slowik, J. G.; Praplan, A. P.; Dommen, J.; Prévôt, A. S. H.; Baltensperger, U.

2013-07-01

A series of smog chamber (SC) experiments was conducted to identify factors responsible for the discrepancy between ambient and SC aerosol degree of oxygenation. An Aerodyne high-resolution time-of-flight aerosol mass spectrometer is used to compare mass spectra from α-pinene photooxidation with ambient aerosol. Composition is compared in terms of the fraction of particulate CO2+, a surrogate for carboxylic acids, vs. the fraction of C2H3O+, a surrogate for aldehydes, alcohols and ketones, as well as in the Van Krevelen space, where the evolution of the atomic hydrogen-to-carbon ratio (H : C) vs. the atomic oxygen-to-carbon ratio (O : C) is investigated. Low (near-ambient) organic mass concentrations were found to be necessary to obtain oxygenation levels similar to those of low-volatility oxygenated organic aerosol (LV-OOA) commonly identified in ambient measurements. The effects of organic mass loading and OH (hydroxyl radical) exposure were decoupled by inter-experiment comparisons at the same integrated OH concentration. An OH exposure between 3 and 25 × 107 cm-3 h is needed to increase O : C by 0.05 during aerosol aging. For the first time, LV-OOA-like aerosol from the abundant biogenic precursor α-pinene was produced in a smog chamber by oxidation at typical atmospheric OH concentrations. Significant correlation between measured secondary organic aerosol (SOA) and reference LV-OOA mass spectra is shown by Pearson's R2 values larger than 0.90 for experiments with low organic mass concentrations between 1.2 and 18 μg m-3 at an OH exposure of 4 × 107 cm-3 h, corresponding to about two days of oxidation time in the atmosphere, based on a global mean OH concentration of ~ 1 × 106 cm-3. α-Pinene SOA is more oxygenated at low organic mass loadings. Because the degree of oxygenation influences the chemical, volatility and hygroscopic properties of ambient aerosol, smog chamber studies must be performed at near-ambient concentrations to accurately simulate ambient aerosol properties.

Formation of nitro-PAHs from the heterogeneous reaction of ambient particle-bound PAHs with N2O5/NO3/NO2

PubMed Central

Zimmermann, Kathryn; Jariyasopit, Narumol; Massey Simonich, Staci L.; Tao, Shu; Atkinson, Roger; Arey, Janet

2014-01-01

Reactions of ambient particles collected from four sites within the Los Angeles, CA air basin and Beijing, China with a mixture of N2O5, NO2, and NO3 radicals were studied in an environmental chamber at ambient pressure and temperature. Exposures in the chamber system resulted in the degradation of particle-bound PAHs and formation of molecular weight (mw) 247 nitropyrenes (NPYs) and nitrofluoranthenes (NFLs), mw 273 nitrotriphenylenes (NTPs), nitrobenz[a]anthracenes (NBaAs), and nitrochrysene (NCHR), and mw 297 nitrobenzo[a]pyrene (NBaP). The distinct isomer distributions resulting from exposure of filter-adsorbed deuterated fluoranthene to N2O5/NO3/NO2 and that collected from the chamber gas-phase suggest that formation of NFLs in ambient particles did not occur by NO3 radical-initiated reaction, but from reaction of N2O5, presumably subsequent to its surface adsorption. Accordingly, isomers known to result from gas-phase radical-initiated reactions of parent PAHs, such as 2-NFL and 2- and 4-NPY, were not enhanced from the exposure of ambient particulate matter to N2O5/NO3/NO2. The reactivity of ambient particles toward nitration by N2O5/NO3/NO2, defined by relative 1-NPY formation, varied significantly, with the relative amounts of freshly emitted particles versus aged particles (particles that had undergone atmospheric chemical processing) affecting the reactivity of particle-bound PAHs toward heterogeneous nitration. Analyses of unexposed ambient samples suggested that, in nighttime samples where NO3 radical-initiated chemistry had occurred, heterogeneous formation of 1-NPY on ambient particles may have contributed to the ambient 1-NPY concentrations at downwind receptor sites. These results, together with observations that 2-NFL is consistently the dominant particle-bound nitro-PAH measured in ambient atmospheres, suggest that for PAHs that exist in both the gas- and particle-phase, the heterogeneous formation of particle-bound nitro-PAHs is a minor formation route compared to gas-phase formation. PMID:23865889

Subjective and objective convergence of the eyes at simulated altitude of 18,000 feet preceded by short-term exposure to heat stress.

PubMed

Sinha, Biswajit; Dubey, D K

2014-01-01

Armed forces personnel including military aviators are quite often exposed concurrently to various environmental stressors like high environmental temperature and hypoxia. Literatures have suggested that exposure to one environmental stressor may modify the physiological response on subsequent exposure to same or different stressor. The present study was undertaken to investigate the impact of cross tolerance between two environmental stressors of aviation (heat and hypoxia) in ten healthy adult males in a simulated altitude chamber in a within subject experimental study. They were assessed for their convergence ability of the eyes at ground and at simulated altitude of 18,000 ft with or without pre-exposure to heat stress. Subjective convergence at simulated altitude of 18,000 ft did not show any improvement following pre-exposure to heat stress. Objective convergence was improved following pre-exposure to heat stress and was found to be 10.76 cm and 9.10 cm without and with heat stress respectively at simulated altitude of 18,000 ft. Improved objective convergence at high altitude as a result of pre-exposure to heat stress is indicative of better ocular functions. This might benefit aviators while flying at hypoxic condition.

Scanning tunneling microscopy study of low temperature silicon epitaxy on hydrogen/silicon(001) and phosphine adsorption on silicon(111)-7x7

NASA Astrophysics Data System (ADS)

Ji, Jeong-Young

A three-chamber ultra-high-vacuum (UHV) system with preparation, scanning tunneling microscopy (STM), and chemical vapor deposition (CVD) chambers was designed and built. Here, one can perform surface preparation, STM e-beam lithography, precursor gas dosing, ion sputtering, silicon epitaxy, and various measurements such as reflection high energy electron diffraction (RHEED), low energy electron diffraction (LEED), and Auger electron spectroscopy (AES). Processes performed in the ultra-clean preparation and gas-filled CVD chambers can be monitored by transferring the samples back to the STM chamber to take topographical images. Si deposition on H-terminated Si(001)-2x1 surfaces at temperatures 300--530 K was studied by scanning tunneling microscopy. Hydrogen apparently hinders Si adatom diffusion and enhances surface roughening. Post-growth annealing transfers the top layer atoms downward to fill in vacancies in the lower layer, restoring the crystallinity of the thin film. Hydrogen is shown to remain on the growth front up to at least 10 ML. Si deposition onto the H/Si(001)-3x1 surface at 530 K suggests that dihydride units further suppress Si adatom diffusion and increase surface roughness. PH3 adsorption on Si(111)-7x7 was studied for various exposures between 0.3--60 L at room temperature by means of the scanning-tunneling-microscopy (STM). PH3-, PH2-, H-reacted, and unreacted adatoms can be identified by analyzing STM images at different sample biases. Most of PH3 adsorbs dissociatively on the surface at initial exposure, generating H and PH2 adsorption sites, followed by molecular adsorption of PH3. Rest atoms are more reactive than the adatoms and PH 2-reacted rest atom sites are also observed in STM images. Statistical analysis shows that center adatoms are more reactive than corner adatoms and the saturation P coverage is ˜0.22 ML. Finally, 900 K annealing of a PH 3 dosed surface results in a disordered, partially P-covered surface and PH3 dosing at 900 K forms the same surface reconstruction as a P2-adsorbed surface at similar temperature.

A reproducible radiation delivery method for unanesthetized rodents during periods of hind limb unloading

NASA Astrophysics Data System (ADS)

Walb, M. C.; Black, P. J.; Payne, V. S.; Munley, M. T.; Willey, J. S.

2015-07-01

Exposure to the spaceflight environment has long been known to be a health challenge concerning many body systems. Both microgravity and/or ionizing radiation can cause acute and chronic effects in multiple body systems. The hind limb unloaded (HLU) rodent model is a ground-based analogue for microgravity that can be used to simulate and study the combined biologic effects of reduced loading with spaceflight radiation exposure. However, studies delivering radiation to rodents during periods of HLU are rare. Herein we report the development of an irradiation protocol using a clinical linear accelerator that can be used with hind limb unloaded, unanesthetized rodents that is capable of being performed at most academic medical centers. A 30.5 cm × 30.5 cm × 40.6 cm rectangular chamber was constructed out of polymethyl methacrylate (PMMA) sheets (0.64 cm thickness). Five centimeters of water-equivalent material were placed outside of two PMMA inserts on either side of the rodent that permitted the desired radiation dose buildup (electronic equilibrium) and helped to achieve a flatter dose profile. Perforated aluminum strips permitted the suspension dowel to be placed at varying heights depending on the rodent size. Radiation was delivered using a medical linear accelerator at an accelerating potential of 10 MV. A calibrated PTW Farmer ionization chamber, wrapped in appropriately thick tissue-equivalent bolus material to simulate the volume of the rodent, was used to verify a uniform dose distribution at various regions of the chamber. The dosimetry measurements confirmed variances typically within 3%, with maximum variance <10% indicated through optically stimulated luminescent dosimeter (OSLD) measurements, thus delivering reliable spaceflight-relevant total body doses and ensuring a uniform dose regardless of its location within the chamber. Due to the relative abundance of LINACs at academic medical centers and the reliability of their dosimetry properties, this method may find great utility in the implementation of future ground-based studies that examine the combined spaceflight challenges of reduced loading and radiation while using the HLU rodent model.

Sensitivity of wheat and rice to low levels of atmospheric ethylene

NASA Technical Reports Server (NTRS)

Klassen, Stephen P.; Bugbee, Bruce

2002-01-01

Ethylene (C2H4) gas is produced throughout the life cycle of plants and can accumulate in closed growth chambers to levels 100 times higher than in outside environments. Elevated atmospheric C2H4 can cause a variety of abnormal responses, but the sensitivity to elevated C2H4 is not well characterized. We evaluated the C2H4 sensitivity of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) in five studies. The first three studies compared the effects of continuous C2H4 levels ranging from 0 to 1000 nmol mol-1 (ppb) in a growth chamber throughout the life cycle of the plants. A short-term 1000 nmol mol-1 treatment was included in which exposure was stopped at anthesis. Yield was reduced by 36% in wheat and 63% in rice at 50 nmol mol-1 and both species were virtually sterile when continuously exposed to 1000 nmol mol-1. However, the yield reductions were much less with exposure that stopped at anthesis, suggesting the detrimental effect of C2H4 on yield was greatest around the time of seed set. Two additional studies evaluated the differential sensitivity of two wheat cultivars (Super Dwarf and USU-Apogee) to 50 nmol mol-1 C2H4 at three CO2 levels [350, 1200, 5000 micromoles mol-1 (ppm)] in a greenhouse. Yield of USU-Apogee was not significantly reduced by C2H4 but the yield of Super Dwarf was reduced by 60%. Elevated CO2 did not influence the sensitivity to C2H4. A difference in the C2H4 sensitivity of USU-Apogee between greenhouse and growth chamber trials suggests that C2H4 sensitivity is dependent on the environment. Collectively, the data suggest that relatively low levels of C2H4 could induce anomalous plant responses by accumulation in greenhouses and growth chambers with inadequate ventilation. The data also suggest that C2H4 sensitivity can be reduced by both genetic and environmental manipulations. 2002 Crop Science Society of America.

Results from a Search for Dark Matter in the Complete LUX Exposure

NASA Astrophysics Data System (ADS)

Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Bramante, R.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Chiller, A. A.; Chiller, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Dobson, J. E. Y.; Druszkiewicz, E.; Edwards, B. N.; Faham, C. H.; Fiorucci, S.; Gaitskell, R. J.; Gehman, V. M.; Ghag, C.; Gibson, K. R.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Ihm, M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lee, C.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Phelps, P.; Reichhart, L.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Stephenson, S.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.; LUX Collaboration

2017-01-01

We report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35 ×1 04 kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 kg of active mass is operated at the Sanford Underground Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence of WIMP nuclear recoils. At a WIMP mass of 50 GeV c-2 , WIMP-nucleon spin-independent cross sections above 2.2 ×10-46 cm2 are excluded at the 90% confidence level. When combined with the previously reported LUX exposure, this exclusion strengthens to 1.1 ×10-46 cm2 at 50 GeV c-2 .

Blood pressure changes in man during infrasonic exposure. An experimental study.

PubMed

Danielsson, A; Landström, U

1985-01-01

Twenty healthy male volunteers were exposed to infrasound in a pressure chamber especially designed for the experiments. The effects on blood pressure, pulse rate and serum cortisol levels of acute infrasonic stimulation were studied in a series of different experiments. Varying frequencies (6, 12, 16 Hz) and pressure levels (95, 110, 125 dB(lin)) were tested. Significantly increased diastolic and decreased systolic blood pressures were recorded without any rise in pulse rate. The increase in diastolic blood pressure reached a maximal mean of about 8 mmHg after 30 min exposure. The results suggest that acute infrasonic stimulation induces a peripheral vasoconstriction with increased blood pressure, previously shown to occur in conjunction with industrial noise. Chronic long-term exposure to environmental infrasound may be of importance for the development of essential hypertension in predisposed individuals.

Production of sugarcane bagasse-based activated carbon for formaldehyde gas removal from potted plants exposure chamber.

PubMed

Mohamed, Elham F; El-Hashemy, Mohammed A; Abdel-Latif, Nasser M; Shetaya, Waleed H

2015-12-01

Agricultural wastes such as rice straw, sugar beet, and sugarcane bagasse have become a critical environmental issue due to growing agriculture demand. This study aimed to investigate the valorization possibility of sugarcane bagasse waste for activated carbon preparation. It also aimed to fully characterize the prepared activated carbon (BET surface area) via scanning electron microscope (SEM) and in terms of surface functional groups to give a basic understanding of its structure and to study the adsorption capacity of the sugarcane bagasse-based activated carbon using aqueous methylene blue (MB). The second main objective was to evaluate the performance of sugarcane bagasse-based activated carbon for indoor volatile organic compounds removal using the formaldehyde gas (HCHO) as reference model in two potted plants chambers. The first chamber was labeled the polluted chamber (containing formaldehyde gas without activated carbon) and the second was taken as the treated chamber (containing formaldehyde gas with activated carbon). The results indicated that the sugarcane bagasse-based activated carbon has a moderate BET surface area (557 m2/g) with total mesoporous volume and microporous volume of 0.310 and 0.273 cm3/g, respectively. The prepared activated carbon had remarkable adsorption capacity for MB. Formaldehyde removal rate was then found to be more than 67% in the treated chamber with the sugarcane bagasse-based activated carbon. The plants' responses for this application as dry weight, chlorophyll contents, and protein concentration were also investigated. Preparation of activated carbon from sugarcane bagasse (SCBAC) is a promising approach to produce cheap and efficient adsorbent for gas pollutants removal. It may be also a solution for the agricultural wastes problems in big cities, particularly in Egypt. MB adsorption tests suggest that the SCBAC have high adsorption capacity. Formaldehyde gas removal in the plant chambers indicates that the SCBAC have potential to recover volatile gases. The results confirmed that the activated carbon produced from sugarcane bagasse waste raw materials can be used as an applicable adsorbent for treating a variety of gas pollutants from the indoor environment.

Murine pulmonary responses after sub-chronic exposure to aluminum oxide-based nanowhiskers

PubMed Central

2012-01-01

Background Aluminum oxide-based nanowhiskers (AO nanowhiskers) have been used in manufacturing processes as catalyst supports, flame retardants, adsorbents, or in ceramic, metal and plastic composite materials. They are classified as high aspect ratio nanomaterials. Our aim was to assess in vivo toxicity of inhaled AO nanowhisker aerosols. Methods Primary dimensions of AO nanowhiskers specified by manufacturer were 2–4 nm x 2800 nm. The aluminum content found in this nanomaterial was 30% [mixed phase material containing Al(OH)3 and AlOOH]. Male mice (C57Bl/6 J) were exposed to AO nanowhiskers for 4 hrs/day, 5 days/wk for 2 or 4 wks in a dynamic whole body exposure chamber. The whiskers were aerosolized with an acoustical dry aerosol generator that included a grounded metal elutriator and a venturi aspirator to enhance deagglomeration. Average concentration of aerosol in the chamber was 3.3 ± 0.6 mg/m3 and the mobility diameter was 150 ± 1.6 nm. Both groups of mice (2 or 4 wks exposure) were necropsied immediately after the last exposure. Aluminum content in the lung, heart, liver, and spleen was determined. Pulmonary toxicity assessment was performed by evaluation of bronchoalveolar lavage (BAL) fluid (enumeration of total and differential cells, total protein, activity of lactate dehydrogenase [LDH] and cytokines), blood (total and differential cell counts), lung histopathology and pulmonary mechanics. Results Following exposure, mean Al content of lungs was 0.25, 8.10 and 15.37 μg/g lung (dry wt) respectively for sham, 2 wk and 4 wk exposure groups. The number of total cells and macrophages in BAL fluid was 2-times higher in animals exposed for 2 wks and 6-times higher in mice exposed for 4 wks, compared to shams (p < 0.01, p < 0.001, respectively). However no neutrophilic inflammation in BAL fluid was found and neutrophils were below 1% in all groups. No significant differences were found in total protein, activity of LDH, or cytokines levels (IL-6, IFN-γ, MIP-1α, TNF-α, and MIP-2) between shams and exposed mice. Conclusions Sub-chronic inhalation exposures to aluminum-oxide based nanowhiskers induced increased lung macrophages, but no inflammatory or toxic responses were observed. PMID:22713230

Murine pulmonary responses after sub-chronic exposure to aluminum oxide-based nanowhiskers.

PubMed

Adamcakova-Dodd, Andrea; Stebounova, Larissa V; O'Shaughnessy, Patrick T; Kim, Jong Sung; Grassian, Vicki H; Thorne, Peter S

2012-06-19

Aluminum oxide-based nanowhiskers (AO nanowhiskers) have been used in manufacturing processes as catalyst supports, flame retardants, adsorbents, or in ceramic, metal and plastic composite materials. They are classified as high aspect ratio nanomaterials. Our aim was to assess in vivo toxicity of inhaled AO nanowhisker aerosols. Primary dimensions of AO nanowhiskers specified by manufacturer were 2-4 nm x 2800 nm. The aluminum content found in this nanomaterial was 30% [mixed phase material containing Al(OH)3 and AlOOH]. Male mice (C57Bl/6 J) were exposed to AO nanowhiskers for 4 hrs/day, 5 days/wk for 2 or 4 wks in a dynamic whole body exposure chamber. The whiskers were aerosolized with an acoustical dry aerosol generator that included a grounded metal elutriator and a venturi aspirator to enhance deagglomeration. Average concentration of aerosol in the chamber was 3.3 ± 0.6 mg/m3 and the mobility diameter was 150 ± 1.6 nm. Both groups of mice (2 or 4 wks exposure) were necropsied immediately after the last exposure. Aluminum content in the lung, heart, liver, and spleen was determined. Pulmonary toxicity assessment was performed by evaluation of bronchoalveolar lavage (BAL) fluid (enumeration of total and differential cells, total protein, activity of lactate dehydrogenase [LDH] and cytokines), blood (total and differential cell counts), lung histopathology and pulmonary mechanics. Following exposure, mean Al content of lungs was 0.25, 8.10 and 15.37 μg/g lung (dry wt) respectively for sham, 2 wk and 4 wk exposure groups. The number of total cells and macrophages in BAL fluid was 2-times higher in animals exposed for 2 wks and 6-times higher in mice exposed for 4 wks, compared to shams (p < 0.01, p < 0.001, respectively). However no neutrophilic inflammation in BAL fluid was found and neutrophils were below 1% in all groups. No significant differences were found in total protein, activity of LDH, or cytokines levels (IL-6, IFN-γ, MIP-1α, TNF-α, and MIP-2) between shams and exposed mice. Sub-chronic inhalation exposures to aluminum-oxide based nanowhiskers induced increased lung macrophages, but no inflammatory or toxic responses were observed.

Standing wave compressor

DOEpatents

Lucas, Timothy S.

1991-01-01

A compressor for compression-evaporation cooling systems, which requires no moving parts. A gaseous refrigerant inside a chamber is acoustically compressed and conveyed by means of a standing acoustic wave which is set up in the gaseous refrigerant. This standing acoustic wave can be driven either by a transducer, or by direct exposure of the gas to microwave and infrared sources, including solar energy. Input and output ports arranged along the chamber provide for the intake and discharge of the gaseous refrigerant. These ports can be provided with optional valve arrangements, so as to increase the compressor's pressure differential. The performance of the compressor in either of its transducer or electromagnetically driven configurations, can be optimized by a controlling circuit. This controlling circuit holds the wavelength of the standing acoustical wave constant, by changing the driving frequency in response to varying operating conditions.

Evidence for percutaneous absorption of isotretinoin from the photo-isomerization of topical tretinoin.

PubMed

Lehman, P A; Malany, A M

1989-11-01

Tretinoin (0.1% Retin-A cream) was topically applied to human cadaver skin in vitro using Franz diffusion chambers. The photo-isomerization of tretinoin and retinoic acid percutaneous absorption in the absence of metabolic activity were assessed with and without ambient light exposure to the skin. Using HPLC, UV, and GC/MSD, a retinoid exhibiting identical chromatographic and spectral characteristics of isotretinoin was observed in the samples from the skin exposed to light, but was virtually absent in the skin samples maintained in the dark. From a single topical application of tretinoin, isotretinoin was as abundant as tretinoin in the chamber receiver solution, dermis, epidermis, and on the skin surface at 24 h after topical application. The data suggest the possibility that isotretinoin may have an important role in the pharmacology of topically applied tretinoin.

Space Age Spuds

NASA Technical Reports Server (NTRS)

2000-01-01

American Ag-Tech International, Ltd. developed a system called Quantum Tubers through the Wisconsin Center for Space Automation and Robotics (a NASA-sponsored Commercial Space Center). Using computerization and technologies originally intended for growing plants in space, the company developed a growth chamber that accelerates plant growth and is free of plant pathogens. The chamber is used to grow minitubers, which serve as nuclear seed stock for potatoes. Using lighting technology, temperature and humidity controls, and automation technology, the minituber can be generated in one closed facility with out much labor handling. This means they can be grown year round in extreme environments. The system eliminates the need for multiple generations of seed and eliminates exposure to pathogens, disease and pests. The Quantum Tubers system can produce 10-20 million tubers throughout the year, about equal to the world's supply of this generation seed stock.

Optothermal transfer simulation in laser-irradiated human dentin.

PubMed

Moriyama, Eduardo H; Zangaro, Renato A; Lobo, Paulo D C; Villaverde, Antonio Balbin; Pacheco, Marcos T; Watanabe, Ii-Sei; Vitkin, Alex

2003-04-01

Laser technology has been studied as a potential replacement to the conventional dental drill. However, to prevent pulpal cell damage, information related to the safety parameters using high-power lasers in oral mineralized tissues is needed. In this study, the heat distribution profiles at the surface and subsurface regions of human dentine samples irradiated with a Nd:YAG laser were simulated using Crank-Nicolson's finite difference method for different laser energies and pulse durations. Heat distribution throughout the dentin layer, from the external dentin surface to the pulp chamber wall, were calculated in each case, to investigate the details of pulsed laser-hard dental tissue interactions. The results showed that the final temperature at the pulp chamber wall and at the dentin surface are strongly dependent on the pulse duration, exposure time, and the energy contained in each pulse.

The correlation of sodium and potassium metabolism with the level of energy consumption in man during adaptation to heat

NASA Technical Reports Server (NTRS)

Afanasyev, B. G.; Zhestovskiy, V. A.

1978-01-01

The sodium and potassium metabolism was studied in a thermal chamber at 35 deg and 80 percent relative humidity in 8 men for a period of 6 days. The control group (3 subjects) were outside of the chamber at a comfortable ambient temperature. The intracellular sodium and potassium metabolism were assessed based on their content in the erythrocytes. The finding was that during adaptation to heat, a considerable amount of sodium was excreted by the body in the sweat and urine (about 1/3 of the sodium content of the human body) as compared with its intake and the amount of potassium retained in the body. Changes in the concentration of sodium and potassium may serve as indexes of the state of adaptation processes during constant exposure to heat.

3 MV hypervelocity dust accelerator at the Colorado Center for Lunar Dust and Atmospheric Studies.

PubMed

Shu, Anthony; Collette, Andrew; Drake, Keith; Grün, Eberhard; Horányi, Mihály; Kempf, Sascha; Mocker, Anna; Munsat, Tobin; Northway, Paige; Srama, Ralf; Sternovsky, Zoltán; Thomas, Evan

2012-07-01

A hypervelocity dust accelerator for studying micrometeorite impacts has been constructed at the Colorado Center for Lunar Dust and Atmospheric Studies (CCLDAS) at the University of Colorado. Based on the Max-Planck-Institüt für Kernphysik (MPI-K) accelerator, this accelerator is capable of emitting single particles of a specific mass and velocity selected by the user. The accelerator consists of a 3 MV Pelletron generator with a dust source, four image charge pickup detectors, and two interchangeable target chambers: a large high-vacuum test bed and an ultra-high vacuum impact study chamber. The large test bed is a 1.2 m diameter, 1.5 m long cylindrical vacuum chamber capable of pressures as low as 10(-7) torr while the ultra-high vacuum chamber is a 0.75 m diameter, 1.1 m long chamber capable of pressures as low as 10(-10) torr. Using iron dust of up to 2 microns in diameter, final velocities have been measured up to 52 km/s. The spread of the dust particles and the effect of electrostatic focusing have been measured using a long exposure CCD and a quartz target. Furthermore, a new technique of particle selection is being developed using real time digital filtering techniques. Signals are digitized and then cross-correlated with a shaped filter, resulting in a suppressed noise floor. Improvements over the MPI-K design, which include a higher operating voltage and digital filtering for detection, increase the available parameter space of dust emitted by the accelerator. The CCLDAS dust facility is a user facility open to the scientific community to assist with instrument calibrations and experiments.

Mechanisms of differentiation in the Skaergaard magma chamber

NASA Astrophysics Data System (ADS)

Tegner, C.; Lesher, C. E.; Holness, M. B.; Jakobsen, J. K.; Salmonsen, L. P.; Humphreys, M. C. S.; Thy, P.

2012-04-01

The Skaergaard intrusion is a superb natural laboratory for studying mechanisms of magma chamber differentiation. The magnificent exposures and new systematic sample sets of rocks that solidified inwards from the roof, walls and floor of the chamber provide means to test the relative roles of crystal settling, diffusion, convection, liquid immiscibility and compaction in different regions of the chamber and in opposite positions relative to gravity. Examination of the melt inclusions and interstitial pockets has demonstrated that a large portion of intrusion crystallized from an emulsified magma chamber composed of immiscible silica- and iron-rich melts. The similarity of ratios of elements with opposite partitioning between the immiscible melts (e.g. P and Rb) in wall, floor and roof rocks, however, indicate that large-scale separation did not occur. Yet, on a smaller scale of metres to hundred of metres and close to the interface between the roof and floor rocks (the Sandwich Horizon), irregular layers and pods of granophyre hosted by extremely iron-rich cumulates point to some separation of the two liquid phases. Similar proportions of the primocryst (cumulus) minerals in roof, wall and floor rocks indicate that crystal settling was not an important mechanism. Likewise, the lack of fractionation of elements with different behavior indicate that diffusion and fluid-driven metasomatism played relatively minor roles. Compositional convection and/or compaction within the solidifying crystal mush boundary layer are likely the most important mechanisms. A correlation of low trapped liquid fractions (calculated from strongly incompatible elements) in floor rocks with high fractionation density (the density difference between the crystal framework and the liquid) indicate that compaction is the dominating process in expelling evolved liquid from the crystal mush layer. This is supported by high and variable trapped liquid contents in the roof rocks, where gravity-driven compaction will not work.

Effects of outgassing of loader chamber walls on hydriding of thin films for commercial applications

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

Provo, James L., E-mail: jlprovo@verizon.net

2014-07-01

An important aspect of understanding industrial processing is to know the characteristics of the materials used in such processes. A study was performed to determine the effects of hydriding chamber material on the degree of hydriding for the commercial production of thin film hydride targets for various research universities, commercial companies, and government national laboratories. The goal was to increase the degree of hydriding of various thin film hydrides and to study the vacuum environment during air-exposure hydriding. For this purpose, dynamic residual gas analysis during deuterium gas hydride processing was utilized with erbium thin films, employing a special set-upmore » for direct dynamic hydride gas sampling during processing at elevated temperature and full loading gas pressure. Complete process data for (1) a copper–(1.83 wt. %)beryllium wet hydrogen fired passivated (600 °C–1 h) externally heated pipe hydriding chamber are reported. Dynamic residual gas analysis comparisons during hydriding are presented for hydriding chambers made from (2) alumina (99.8 wt. %), (3) copper (with an interior aluminum coating ∼10 k Å thick, and (4) for a stainless-steel air-fired passivated (900 °C–1 h) chamber. Dynamic data with deuterium gas in the chamber at the hydriding temperature (450 °C) showed the presence and growth of water vapor (D{sub 2}O) and related mixed ion species(H{sub 2}O{sup +}, HDO{sup +}, D{sub 2}O{sup +}, and OD{sup +}) from hydrogen isotope exchange reactions during the 1 h process time. Peaks at mass-to-charge ratios (i.e., m/e) of 12(C{sup +}), 16(CD{sub 2}{sup +}), 17(CHD{sub 2}{sup +}), and 18(CD{sub 3}{sup +}, OD{sup +}) increased for approximately the first half hour of a 1 h hydriding process and then approach steady state. Mass-to-charge peaks at 19(HDO{sup +}) and 20(D{sub 2}O{sup +}) continue to increase throughout the process cycle. Using the m/e = 20 (D{sub 2}O{sup +}) peak intensity from chamber (1)–Cu(1.83 wt. %)Be as a standard, the peak intensity from chamber (4)—stainless-steel (air-fired) was 7.1× higher, indicating that the surface of stainless-steel had a larger concentration of reactive oxygen and/or water than hydrogen. The (D{sub 2}O{sup +}) peak intensity from chamber (3)—Cu (interior Al coating) was 1.55× larger and chamber (2)—alumina(99.8%) was 1.33× higher than Cu(1.83 wt. %)Be. Thus copper–(1.83 wt. %)beryllium was the best hydriding chamber material studied followed closely by the alumina (99.8 wt. %) chamber. Gas take-up by Er occluder targets processed in Cu(1.83 wt. %)Be hydriding chambers (i.e., gas/metal atomic ratios) correlate with the dynamic RGA data.« less

An experimental study of the combined effects of n-hexane and methyl ethyl ketone.

PubMed Central

Takeuchi, Y; Ono, Y; Hisanaga, N; Iwata, M; Aoyama, M; Kitoh, J; Sugiura, Y

1983-01-01

This study was intended to determine whether or not methyl ethyl ketone (MEK) enhances the neurotoxicity of n-hexane at low concentration and after long term exposure. Separate groups of eight rats were exposed to 100 ppm n-hexane, 200 ppm MEK, 100 ppm n-hexane plus 200 ppm MEK, or fresh air in an exposure chamber for 12 hours a day for 24 weeks. The body weight, motor nerve conduction velocity (MCV), distal motor latency (DL), and mixed nerve conduction velocities (MNCVs) were measured before exposure and after four, eight, 12, 16, 20, and 24 weeks' exposure. One rat of each group was histopathologically examined after 24 weeks' exposure. Exposure of 100 ppm n-hexane did not significantly decrease the functions of the peripheral nerve throughout the experiment. Exposure to 200 ppm MEK significantly increased MCV and MNCVs and decreased DL after four weeks' exposure, but at this later stage no significant changes were found throughout the experiment by comparison with the controls. Mixed exposure to 100 ppm n-hexane plus 200 ppm MEK significantly decreased by comparison with the controls. On histopathological examination of the tail nerve, however, no changes were found in any of the exposed groups or the controls. These results suggest that MEK might enhance the neurotoxicity of n-hexane at a low concentration, and mixed exposures to n-hexane and MEK should be avoided. PMID:6830718

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

Williamson, Jeffrey F.

This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as amore » means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.« less

History of dose specification in Brachytherapy: From Threshold Erythema Dose to Computational Dosimetry

NASA Astrophysics Data System (ADS)

Williamson, Jeffrey F.

2006-09-01

This paper briefly reviews the evolution of brachytherapy dosimetry from 1900 to the present. Dosimetric practices in brachytherapy fall into three distinct eras: During the era of biological dosimetry (1900-1938), radium pioneers could only specify Ra-226 and Rn-222 implants in terms of the mass of radium encapsulated within the implanted sources. Due to the high energy of its emitted gamma rays and the long range of its secondary electrons in air, free-air chambers could not be used to quantify the output of Ra-226 sources in terms of exposure. Biological dosimetry, most prominently the threshold erythema dose, gained currency as a means of intercomparing radium treatments with exposure-calibrated orthovoltage x-ray units. The classical dosimetry era (1940-1980) began with successful exposure standardization of Ra-226 sources by Bragg-Gray cavity chambers. Classical dose-computation algorithms, based upon 1-D buildup factor measurements and point-source superposition computational algorithms, were able to accommodate artificial radionuclides such as Co-60, Ir-192, and Cs-137. The quantitative dosimetry era (1980- ) arose in response to the increasing utilization of low energy K-capture radionuclides such as I-125 and Pd-103 for which classical approaches could not be expected to estimate accurate correct doses. This led to intensive development of both experimental (largely TLD-100 dosimetry) and Monte Carlo dosimetry techniques along with more accurate air-kerma strength standards. As a result of extensive benchmarking and intercomparison of these different methods, single-seed low-energy radionuclide dose distributions are now known with a total uncertainty of 3%-5%.

Efficacy of antimicrobial 405 nm blue-light for inactivation of airborne bacteria

NASA Astrophysics Data System (ADS)

Dougall, Laura R.; Anderson, John G.; Timoshkin, Igor V.; MacGregor, Scott J.; Maclean, Michelle

2018-02-01

Airborne transmission of infectious organisms is a considerable concern within the healthcare environment. A number of novel methods for `whole room' decontamination, including antimicrobial 405 nm blue light, are being developed. To date, research has focused on its effects against surface-deposited contamination; however, it is important to also establish its efficacy against airborne bacteria. This study demonstrates evidence of the dose-response kinetics of airborne bacterial contamination when exposed to 405 nm light and compares bacterial susceptibility when exposed in three different media: air, liquid and surfaces. Bacterial aerosols of Staphylococcus epidermidis, generated using a 6-Jet Collison nebulizer, were introduced into an aerosol suspension chamber. Aerosolized bacteria were exposed to increasing doses of 405 nm light, and air samples were extracted from the chamber using a BioSampler liquid impinger, with viability analysed using pour-plate culture. Results have demonstrated successful aerosol inactivation, with a 99.1% reduction achieved with a 30 minute exposure to high irradiance (22 mWcm-2) 405 nm light (P=0.001). Comparison to liquid and surface exposures proved bacteria to be 3-4 times more susceptible to 405 nm light inactivation when in aerosol form. Overall, results have provided fundamental evidence of the susceptibility of bacterial aerosols to antimicrobial 405 nm light treatment, which offers benefits in terms of increased safety for human exposure, and eradication of microbes regardless of antibiotic resistance. Such benefits provide advantages for a number of applications including `whole room' environmental decontamination, in which reducing levels of airborne bacteria should reduce the number of infections arising from airborne contamination.

Design and demonstration of a pumpless 14 compartment microphysiological system.

PubMed

Miller, Paula G; Shuler, Michael L

2016-10-01

We describe a human "Body-on-a-chip" device (or microphysiological system) that could be used to emulate drug distribution, metabolism, and action in the body. It is based upon a physiologically based pharmacokinetic-pharmacodynamic (PBPK-PD) model, where multiple chambers representing different organs are connected with fluidic channels to mimic multi-organ interactions within the body. Here we describe a pumpless 14 chamber (13 organs) microfluidic cell culture device that provides a separation between barrier and nonbarrier types of cell cultures. Our barrier chamber layer (skin, GI tract, and lung) allows for direct access and/or exposures to chemical or biological reagents forcing these reagents to pass through a barrier of cells established on a microfabricated membrane before exposing the nonbarrier tissue chambers (fat, kidney, heart, adrenal glands, liver, spleen, pancreas, bone marrow, brain, muscle) or entering the microfluidic circulation within the device. Our nonbarrier tissue chambers were created as three-dimensional configurations by resuspending cells in hydrogel (PGMatrix). We used cell lines to represent five of these organs (barrier lines-A549 [lung] and Caco2 [GI]) (nonbarrier lines-HepG2 C3A [liver], Meg01 [bone marrow], and HK2 [kidney]). The dimensions of our straight duct-like channels to each organ chamber were designed to provide the appropriate flow of a culture medium. The organ volumes and organ flow rates that have been reported for an average human male were used to estimate the desired fluid retention times in each organ chamber. The flow through the channels was induced by gravity on a custom programmed rocker platform which enabled pumpless operation and minimized bubble entrapment. The purpose of this paper is to describe the design and operation of a 14 chamber multi-organ system representing 13 tissues/organs with both barrier and nonbarrier tissue chambers and to study the interactive responses among the various cell lines. We demonstrate that five different cell lines survived with high viability (above 85%) for 7 days. We compared the individual observed flow rates to the compartments to the desired or estimated flow rates. This work demonstrates the feasibility of constructing, operating and maintaining a simple, gravity-driven, multi-organ microphysiological system with the capability of measuring cellular functions such as CYP1A1 and CYP3A4 activities, albumin release, urea, maintenance of tight junctions, and presence of surfactant for a sustained period. Biotechnol. Bioeng. 2016;113: 2213-2227. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Dietary Protection Against Pulmonary Oxygen Poisoning.

DTIC Science & Technology

1980-12-31

hyperoxia produces pathological changes in lung which can be fatal. With an interest in delineating dietary factors which might affect the pulmonary response...by dietary fat type (6,7). This study was conducted to investigate any changes in pulmonary PG synthetic capacity following treatment with diets...at 1 atmosphere in controlled environment chambers (9). In our mc3Rl system oxygen exposure produces discernible pulmonary biochem-cal changes after 24

Flame and acid resistant polymide fibers

NASA Technical Reports Server (NTRS)

Stringham, R. S.; Toy, M. S.

1977-01-01

Economical process improves flame resistance and resistance to acids of polyamide fibers, without modifying colors of mechanical properties. Process improves general safety of garments and other items made from polyamide fibers and makes them suitable for applications requiring exposure to oxygen-rich atmosphere or corrosive acids. Halo-olefins are added to surface of fibers by photoadditon in sealed chamber. Process could be used with films and other forms of polyamide.

Effects of chronic and acute exposure to sulphur dioxide on the growth of hybrid poplar cuttings

Treesearch

Leon S. Dochinger; Keith F. Jensen

1975-01-01

Hybrid poplar clones were fumigated in controlled-environment chambers with either 5 ppm sulphur dioxide for 1½, 3, and 6 h or with 0.25 ppm sulphur dioxide for six weeks. Multivariate analyses were made from shoot-growth data before and after treatment and on the foliar injury induced by S02. Both short- and long-term fumigation produced similar...

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

Koukol, J.; Dugger, W.M. Jr.

The isolation and characterization of a cyanidin glucoside from leaves of dock plants (Rumerx crispus L.) after exposure to smog are described. Experiments in which plants were exposed only to ozone, a component of smog, also led to the appearance of the anthocyanin in the leaves of plants. Identification of the anthocyanin was undertaken as the first step in studying the stimulatory effect of ozone on anthocyanin biosynthesis. The ozone fumigations were carried out in special chambers.

Natural Exposure versus Chamber Simulation.

DTIC Science & Technology

1984-09-01

Phoma) or at the Forested sites ( Trichoderma , Fusarum and Cephalosporium). -tNtter genera occured only once or twice out of eig-htfungal examinations...APR CURVULARIA x PENICILLIUM X X x X X FUSARIUM CLADOSPORIUM X PHOIAA X ASPERGILLUS X CEPHALOSPORIUM X X TRICHODERMA X PESTALOTIA GL TOCLADIUM...X x x * CLADOSPORIUM PHOMA x ASPERGILLUS. CEPHALOSPORI’JM X x x TRICHODERMA X X X X X X X PESTALOTIA x GLIOCLADIUM NIGROSPORA STEMPHYLIUM ALTERNARIA

Observations on Mildew Susceptibility of Painted Surfaces in Tropical Chamber Exposure

DTIC Science & Technology

1983-12-01

resins of iron oxide, red iron urea formaldehyde or oxide. blends of urea / melamine + modifiers, stabili- zers, wetting and sus- pension agents. MIL-E...type, modified or chromate yellow, molyb- with not less than 20% date orange, carbazole di- butylated melamine oxazine violet, yellow formaldehyde ...com- Pure short oil length Enamel, Modified Alkyd posed of cobalt, zinc, phthalic alkyd resin Camouflage, Lusterless and chromium oxides, and/ baking

Krm83 calibration of the 2013 LUX dark matter search

NASA Astrophysics Data System (ADS)

Akerib, D. S.; Alsum, S.; Araújo, H. M.; Bai, X.; Bailey, A. J.; Balajthy, J.; Beltrame, P.; Bernard, E. P.; Bernstein, A.; Biesiadzinski, T. P.; Boulton, E. M.; Brás, P.; Byram, D.; Cahn, S. B.; Carmona-Benitez, M. C.; Chan, C.; Currie, A.; Cutter, J. E.; Davison, T. J. R.; Dobi, A.; Druszkiewicz, E.; Edwards, B. N.; Fallon, S. R.; Fan, A.; Fiorucci, S.; Gaitskell, R. J.; Genovesi, J.; Ghag, C.; Gilchriese, M. G. D.; Hall, C. R.; Hanhardt, M.; Haselschwardt, S. J.; Hertel, S. A.; Hogan, D. P.; Horn, M.; Huang, D. Q.; Ignarra, C. M.; Jacobsen, R. G.; Ji, W.; Kamdin, K.; Kazkaz, K.; Khaitan, D.; Knoche, R.; Larsen, N. A.; Lenardo, B. G.; Lesko, K. T.; Lindote, A.; Lopes, M. I.; Manalaysay, A.; Mannino, R. L.; Marzioni, M. F.; McKinsey, D. N.; Mei, D.-M.; Mock, J.; Moongweluwan, M.; Morad, J. A.; Murphy, A. St. J.; Nehrkorn, C.; Nelson, H. N.; Neves, F.; O'Sullivan, K.; Oliver-Mallory, K. C.; Palladino, K. J.; Pease, E. K.; Rhyne, C.; Shaw, S.; Shutt, T. A.; Silva, C.; Solmaz, M.; Solovov, V. N.; Sorensen, P.; Sumner, T. J.; Szydagis, M.; Taylor, D. J.; Taylor, W. C.; Tennyson, B. P.; Terman, P. A.; Tiedt, D. R.; To, W. H.; Tripathi, M.; Tvrznikova, L.; Uvarov, S.; Velan, V.; Verbus, J. R.; Webb, R. C.; White, J. T.; Whitis, T. J.; Witherell, M. S.; Wolfs, F. L. H.; Xu, J.; Yazdani, K.; Young, S. K.; Zhang, C.; LUX Collaboration

2017-12-01

LUX was the first dark matter experiment to use a Krm83 calibration source. In this paper, we describe the source preparation and injection. We also present several Krm83 calibration applications in the context of the 2013 LUX exposure, including the measurement of temporal and spatial variation in scintillation and charge signal amplitudes, and several methods to understand the electric field within the time projection chamber.

Evaluation of the Effects of Hydrogen Peroxide on Common Aviation Structural Materials

DTIC Science & Technology

2009-12-01

population of Geobacillus stearothermophilus . Once the sanitization/ decontamination phase is completed, the enclosure is 1 VHP is a registered...disinfection and/or decon- tamination technologies available, vaporized hydrogen peroxide (VHP)1 is of particular interest because it can be rapidly sterilized ...decontamination Unit (STERIS Corporation, Mentor, OH, USA) using VAPROX®2 as the sterilant in an enclosed chamber for 1, 10, or 25 VHP cycles . The exposure

Physiological Equivalence of Normobaric and Hypobaric Exposures of Humans to 25,000 Feet

DTIC Science & Technology

2010-12-01

alveolar oxygen tension (PAO2), alveolar carbon dioxide tension (PACO2), and respiratory quotient (RQ) differed significantly between the chamber and...the U.S. Navy (1) and Air force (2) physiological training programs have instituted ground-level hypoxia training. Respiratory physiologists have been...gas composition and respiratory quotients (RQ) under hypobaric and normobaric condi- tions will be quite different at the same level of ventilatory

Medical and Performance Problems of Acute High Altitude-Exposure,

DTIC Science & Technology

1981-07-11

counter the respiratory alkalosis of altitude with a metabolic acidosis, thereby maintaining normal pH. The occurrence and severity of symptoms have...In chamber studies at our Institute, the role of hypocapnic alkalosis in the development of AMS was assessed by exposing subjects to simulated high...beneficial effect on symptomatology, if not by preventing the development of alkalosis ? Further- more, Why does the development of hypocapnia appear to be

Estimation of dose rates at the entrance surface for exposure scenarios of total body irradiation using MCNPX code

NASA Astrophysics Data System (ADS)

Cunha, J. S.; Cavalcante, F. R.; Souza, S. O.; Souza, D. N.; Santos, W. S.; Carvalho Júnior, A. B.

2017-11-01

One of the main criteria that must be held in Total Body Irradiation (TBI) is the uniformity of dose in the body. In TBI procedures the certification that the prescribed doses are absorbed in organs is made with dosimeters positioned on the patient skin. In this work, we modelled TBI scenarios in the MCNPX code to estimate the entrance dose rate in the skin for comparison and validation of simulations with experimental measurements from literature. Dose rates were estimated simulating an ionization chamber laterally positioned on thorax, abdomen, leg and thigh. Four exposure scenarios were simulated: ionization chamber (S1), TBI room (S2), and patient represented by hybrid phantom (S3) and water stylized phantom (S4) in sitting posture. The posture of the patient in experimental work was better represented by S4 compared with hybrid phantom, and this led to minimum and maximum percentage differences of 1.31% and 6.25% to experimental measurements for thorax and thigh regions, respectively. As for all simulations reported here the percentage differences in the estimated dose rates were less than 10%, we considered that the obtained results are consistent with experimental measurements and the modelled scenarios are suitable to estimate the absorbed dose in organs during TBI procedure.

Intrinsic hydrophilic nature of epitaxial thin-film of rare-earth oxide grown by pulsed laser deposition.

PubMed

Prakash, Saurav; Ghosh, Siddhartha; Patra, Abhijeet; Annamalai, Meenakshi; Motapothula, Mallikarjuna Rao; Sarkar, Soumya; Tan, Sherman J R; Zhunan, Jia; Loh, Kian Ping; Venkatesan, T

2018-02-15

Herein, we report a systematic study of water contact angle (WCA) of rare-earth oxide thin-films. These ultra-smooth and epitaxial thin-films were grown using pulsed laser deposition and then characterized using X-Ray diffraction (XRD), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). Through both the traditional sessile drop and the novel f-d method, we found that the films were intrinsically hydrophilic (WCA < 10°) just after being removed from the growth chamber, but their WCAs evolved with an exposure to the atmosphere with time to reach their eventual saturation values near 90° (but always stay 'technically' hydrophilic). X-Ray photoelectron spectroscopy analysis was used to further investigate qualitatively the nature of hydrocarbon contamination on the freshly prepared as well as the environmentally exposed REO thin-film samples as a function of the exposure time after they were removed from the deposition chamber. A clear correlation between the carbon coverage of the surface and the increase in WCA was observed for all of the rare-earth films, indicating the extrinsic nature of the surface wetting properties of these films and having no relation to the electronic configuration of the rare-earth atoms as proposed by Azimi et al.

Demonstrated survivability of a high temperature optical fiber cable on a 1500 pound thrust rocket chamber

NASA Technical Reports Server (NTRS)

Sovie, Amy L.

1992-01-01

A demonstration of the ability of an existing optical fiber cable to survive the harsh environment of a rocket engine was performed at the NASA Lewis Research Center. The intent of this demonstration was to prove the feasibility of applying fiber optic technology to rocket engine instrumentation systems. Extreme thermal transient tests were achieved by wrapping a high temperature optical fiber, which was cablized for mechanical robustness, around the combustion chamber outside wall of a 1500 lb Hydrogen-Oxygen rocket engine. Additionally, the fiber was wrapped around coolant inlet pipes which were subject to near liquid hydrogen temperatures. Light from an LED was sent through the multimode fiber, and output power was monitored as a function of time while the engine was fired. The fiber showed no mechanical damage after 419 firings during which it was subject to transients from 30 K to 350 K, and total exposure time to near liquid hydrogen temperatures in excess of 990 seconds. These extreme temperatures did cause attenuation greater than 3 dB, but the signal was fully recovered at room temperature. This experiment demonstrates that commercially available optical fiber cables can survive the environment seen by a typical rocket engine instrumentation system, and disclose a temperature-dependent attenuation observed during exposure to near liquid hydrogen temperatures.

Individual Susceptibility to Hypobaric Environments: An Update

NASA Technical Reports Server (NTRS)

Law, Jennifer; Watkins, Sharmi

2009-01-01

Astronauts are at risk for developing decompression sickness (DCS) while exposed to the hypobaric environment of the extravehicular suit in space, in terrestrial hypobaric chambers, and during ascent from neutral buoyancy training dives. There is increasing recognition that DCS risk is different between diving and altitude exposures, with many individual parameters and environmental factors implicated as risk factors for development of DCS in divers but are not recognized as risk factors in altitude exposures. Much of the literature to date has focused on patent foramen ovale (PFO), which has long been considered a major risk factor for DCS in diving exposures, but its link to serious DCS in altitude exposures remains unclear. Knowledge of those risk factors specific to hypobaric DCS may help identify susceptible individuals and aid in astronaut selection, crew assignment, and mission planning. This paper reviews the current literature pertaining to these risk factors, including PFO, anthropometric parameters, gender, menstrual cycle, lifetime diving experience, physical fitness, biochemical levels, complement activation, cigarette smoking, fluid balance, and ambient temperature. Further research to evaluate pertinent risk factors for DCS in altitude exposures is recommended.

Comparison of the behavior of stainless and mild steel manual metal arc welding fumes in rat lung.

PubMed

Kalliomäki, P L; Junttila, M L; Kalliomäki, K K; Lakomaa, E L; Kivelä, R

1983-04-01

The lung retention and clearance of manual metal arc (MMA) stainless steel and mild steel welding fumes were determined in the rat. The exposure simulated the actual welding situation. The duration of exposure in the "nose-only" exposure chamber was 1 h/workday for one, two, three, or four weeks in the retention study and for four weeks in the clearance study. The concentration of exogenous iron was determined by the magnetic measuring method. Instrumental neutron activation analysis was applied to determine the concentration of total iron, chromium, and nickel in the lungs. The results indicated that the lung retention and clearance patterns for the two types of welding fumes were different. A linear relationship was observed between the amount of stainless steel MMA welding fume retained in the lungs and the duration of exposure, whereas the retention of mild steel MMA welding fume in the lung was saturated as a function of the cumulative exposure time rates. The maximum amount of lung-retained contaminants was 880 micrograms for stainless steel MMA welding fume and 220 micrograms for mild steel MMA fume.

No effects of pulsed radio frequency electromagnetic fields on melatonin, cortisol, and selected markers of the immune system in man.

PubMed

Radon, K; Parera, D; Rose, D M; Jung, D; Vollrath, L

2001-05-01

There is growing public concern that radio frequency electromagnetic fields may have adverse biological effects. In the present study eight healthy male students were tested to see whether or not radio frequency electromagnetic fields as used in modern digital wireless telecommunication (GSM standard) have noticeable effects on salivary melatonin, cortisol, neopterin, and immunoglobulin A (sIgA) levels during and several hours after exposure. In a specifically designed, shielded experimental chamber, the circularly polarized electromagnetic field applied was transmitted by an antenna positioned 10 cm behind the head of upright sitting test persons. The carrier frequency of 900 MHz was pulsed with 217 Hz (average power flux density 1 W/m2). In double blind trials, each test person underwent a total of 20 randomly allotted 4 hour periods of exposure and sham exposure, equally distributed at day and night. The results obtained show that the salivary concentrations of melatonin, cortisol, neopterin and sIgA did not differ significantly between exposure and sham exposure. Copyright 2001 Wiley-Liss, Inc.

Effect of circadian rhythm on CNS oxygen toxicity.

NASA Technical Reports Server (NTRS)

Hof, D. G.; Dexter, J. D.; Mengel, C. E.

1971-01-01

The circadian rhythm in susceptibility to oxygen toxicity seizures was investigated by using six groups of 20 male Sprague-Dawley rats (101-196 gm.). The animals were given standard chow, exposed to standard diurnal conditions of light (0700-1900 hr) and dark (1900-0700 hr), and fasted for 15-16 hr prior to exposure to hyperbaric oxygen. The animals were placed in a previously oxygen flushed chamber and raised to 60 psi (gauge) oxygen at a rate of 3 psi/min. Time of exposure started with attainment of 60 psi. End point was first convulsion. The animals' weights were equally distributed within the groups, and the groups were defined by hour of exposure. Time of exposure in minutes prior to seizure was significantly longer in those exposed at 0700-0800 hr and 1000-1100 hr than in four other groups. There was no relationship between animals' weights and time of exposure to seizures. All R values were negative, and the highest R value was -035. These data suggest a definite circadian rhythm in susceptibility to oxygen toxicity seizures.

Occupational allergic rhinitis from guar gum.

PubMed

Kanerva, L; Tupasela, O; Jolanki, R; Vaheri, E; Estlander, T; Keskinen, H

1988-05-01

Three cases of allergic rhinitis from a vegetable gum, guar gum, have been detected. Two subjects were exposed to fine guar gum powder (Emco Gum 563, Meyhall Chemical AG, Switzerland), an insulator in rubber cables, when opening cables in a power cable laboratory. After 1-2 years' exposure the patients developed rhinitis. Scratch-chamber tests, nasal provocation tests, nasal eosinophilia and a RAST test proved their allergy. A third subject developed allergic rhinitis from another guar gum product (Meyproid 5306, Meyhall Chemical AG) after 2 years' exposure in a paper factory. A positive skin test and nasal provocation test confirmed the diagnosis. A fourth case of possible allergy to guar gum after exposure to Meyproid 5306 in a paper factory is also presented. No final diagnosis was reached in this case (in 1974). The present subjects, only one of whom was atopic, developed allergy within 2 years, although their exposure to guar gum was not especially heavy. Therefore, when handling guar, adequate ventilation facilities should be provided and protective clothing, including a respiratory mask, should be worn.

Development of chloride-induced corrosion in pre-cracked RC beams under sustained loading: Effect of load-induced cracks, concrete cover, and exposure conditions

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

Yu, Linwen; Université de Sherbrooke, Quebec; François, Raoul, E-mail: raoul.francois@insa-toulouse.fr

2015-01-15

This paper deals with corrosion initiation and propagation in pre-cracked reinforced concrete beams under sustained loading during exposure to a chloride environment. Specimen beams that were cast in 2010 were compared to specimens cast in 1984. The only differences between the two sets of beams were the casting direction in relation to tensile reinforcement and the exposure conditions in the salt-fog chamber. The cracking maps, corrosion maps, chloride profiles, and cross-sectional loss of one group of two beams cast in 2010 were studied and their calculated corrosion rates were compared to that of beams cast in 1984 in order tomore » investigate the factors influencing the natural corrosion process. Experimental results show that, after rapid initiation of corrosion at the crack tip, the corrosion process practically halted and the time elapsing before corrosion resumed depended on the exposure conditions and cover depth.« less

Thyroid function during intermittent exposure to hypobaric hypoxia

NASA Astrophysics Data System (ADS)

Sawhney, R. C.; Malhotra, A. S.

1990-09-01

Circulatory levels of triiodothyronine (T3) and thyroxine (T4) and their kinetics were studied in rabbits exposed to intermittent hypobaric hypoxia (5200 m, 395 mm Hg, PO2 83 mm Hg) 6 h daily for 5 weeks in a decompression chamber maintained at room temperature of 22° 24° C. Kinetics of T3 and T4 were studied on days 21 and 28 of hypoxic exposure. The T3 and T4 values were found to be significantly lower on day 8 of exposure to hypoxia compared to the pre-exposure values. The decreased levels were maintained throughout the entire period of hypoxic stress. The metabolic clearance rate, production rate, distribution space and extrathyroidal T3 and T4 pools were significantly decreased in animals under hypoxic stress compared to the control animals. The decline in thyroid hormone levels and their production in rabbits under hypoxic stress indicate an adaptive phenomenon under conditions of low oxygen availability.

High altitude simulation, substance P and airway rapidly adapting receptor activity in rabbits.

PubMed

Bhagat, R; Yasir, A; Vashisht, A; Kulshreshtha, R; Singh, S B; Ravi, K

2011-09-15

To investigate whether there is a change in airway rapidly adapting receptor (RAR) activity during high altitude exposure, rabbits were placed in a high altitude simulation chamber (barometric pressure, 429 mm Hg). With 12 h exposure, when there was pulmonary congestion, an increase in basal RAR activity was observed. With 36 h exposure, when there was alveolar edema, there was a further increase in basal RAR activity. In these backgrounds, there was an increase in the sensitivity of the RARs to substance P (SP). To assess whether there was an increase in lung SP level, neutral endopeptidase activity was determined which showed a decrease in low barometric pressure exposed groups. It is concluded that along with the SP released, pulmonary congestion and edema produced, respectively by different durations of low barometric pressure exposure cause a progressive increase in RAR activity which may account for the respiratory symptoms reported in climbers who are unacclimatized. Copyright © 2011 Elsevier B.V. All rights reserved.

NASA Rat Acoustic Tolerance Test 1994-1995

NASA Technical Reports Server (NTRS)

Holley, Daniel C.; Mele, Gary D.; Naidu, Sujata

1996-01-01

The major objective of this Cooperative Agreement was to develop a noise level specification for laboratory rats in the Centrifuge Facility Specimen Chambers (Space Station Biological Research Project), and to validate the specification for 3 noise octave bands: center frequencies 8 kHz, 16, kHz, and 32 kHz. This has been accomplished. Objective measures were used to verify that the chronic noise exposure was not harmful to the animals from physiological and behavioral perspectives. These measures were defined in the Stress Assessment Battery Validation for the Rat Acoustic Tolerance Test. In addition, the effects of the chronic noise exposure on rat hearing was assessed by the Brainstem Auditory Evoked Potential Method (BAER).

Inhalation testing of toiletries in animals.

PubMed

Wells, A B

1979-06-01

Synopsis The purpose of testing is to establish the safety of ingredients to be handled in the factory and of the products to be used by the consumer. Inhalation tests tend to require much time and are expensive; the number of inhalation tests may be reduced by preliminary measurement of the respirable fraction of an aerosol or powder, by toxicity tests on macrophages in culture, and by instillation of suspensions into the lung via the trachea. Inhalation exposures may be in whole body exposure chambers or the head only may be exposed; the techniques are discussed. The criteria of a satisfactory inhalation test are considered and histological features which should be investigated are reviewed.

Regulation of the Low Dose Radiation Paracrine-Specific Anchorage-Independent Growth Response by Annexin A2

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

Weber, Thomas J.; Opresko, Lee K.; Waisman, David M.

2009-07-13

ABSTRACT-Here we identify release of annexin A2 into the culture medium in response to low dose X-ray radiation exposure and establish functional linkages to an established paracrine factor-mediated anchorage-independent growth response. Using a standard bicameral coculture model, we observe that annexin A2 levels associated with non-irradiated neighboring cells seeded in the lower chamber (annexin A2 silenced [shRNA] JB6 cells) are increased upon coculture with irradiated (10-50 cGy) JB6 cells seeded in the upper chamber, relative to coculture with sham exposed JB6 cells seeded in the upper chamber, suggesting that annexin A2 released into the medium is capable of communicating inmore » a paracrine fashion. Using a previously established coculture model, we observed that the paracrine factor-mediated anchorage-independent growth response to low dose X-ray radiation is markedly reduced when irradiated annexin A2 silenced (shRNA) JB6 cells are used, relative to coculture with irradiated annexin A2 competent vector control counterparts. These observations suggest that annexin A2 is functionally linked to the radiation paracrine factor-specific anchorage-independent growth response in JB6 cells.« less

Influence of in-situ ion-beam sputter cleaning on the conditioning effect of vacuum gaps

NASA Astrophysics Data System (ADS)

Kobayashi, Shinichi; Kojima, Hiroyuki; Saito, Yoshio

1994-05-01

An ion beam sputtering technique was used to clean the electrode surfaces of vacuum gaps. Ions of the sputtering gas were irradiated by means of an ion gun in a vacuum chamber attached to a breakdown measurement chamber. By providing in situ ion-beam sputter cleaning, this system makes it possible to make measurements free from contamination due to exposure to the air. The sputtering gas was He or Ar, and the electrodes were made of oxygen-free copper (purity more than 99.96%). An impulse voltage with the wave form of 64/700 microsecond(s) was applied to the test gap, and the pressure in the breakdown measurement chamber at the beginning of breakdown tests was 1.3 X 10-8 Pa. These experiments showed that ion-beam sputter cleaning results in higher breakdown fields after a repetitive breakdown conditioning procedure, and that He is more effective in improving hold- off voltages after the conditioning (under the same ion current density, the breakdown field was 300 MV/m for He sputtering and 200 MV/m for Ar sputtering). The breakdown fields at the first voltage application after the sputtering cleaning, on the other hand, were not improved.

Chamber study of PCB emissions from caulking materials and light ballasts.

PubMed

Liu, Xiaoyu; Guo, Zhishi; Krebs, Kenneth A; Stinson, Rayford A; Nardin, Joshua A; Pope, Robert H; Roache, Nancy F

2015-10-01

The emissions of polychlorinated biphenyl (PCB) congeners from thirteen caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 different models from five manufacturers were tested in 53-L environmental chambers. The rates of PCB congener emissions from caulking materials and light ballasts were determined. Several factors that may have affected the emission rates were evaluated. The experimentally determined emission factors showed that, for a given PCB congener, there is a linear correlation between the emission factor and the concentration of the PCB congener in the source. Furthermore, the test results showed that an excellent log-linear correlation exists between the normalized emission factor and the vapor pressure (coefficient of determination, r(2)⩾0.8846). The PCB congener emissions from ballasts at or near room temperature were relatively low with or without electrical load. However, the PCB congener emission rates increased significantly as the temperature increased. The results of this research provide new data and models for ranking the primary sources of PCBs and supports the development and refinement of exposure assessment models for PCBs. Published by Elsevier Ltd.

Prenatal low-dose bisphenol A enhances behavioral responses induced by a predator odor.

PubMed

Fujimoto, Tetsuya; Kubo, Kazuhiko; Nishikawa, Yasuo; Aou, Shuji

2015-01-01

Bisphenol A (BPA) is an environmental endocrine disrupter (EED). Previous studies by our group showed that pre- and postnatal administration of low-level BPA induced depression-like behavior in rats. In this study, we evaluated the effects of prenatal BPA on behavioral responses to a predator odor by using a novel cross-form apparatus consisting of 4 plastic chambers. On the first day, nothing was placed into the chambers (Session 1). On the second day, a predator odor (fox odor) was located in separate chambers at 2 opposite corners of the apparatus (Session 2). Pregnant Wistar rats were exposed to low-dose BPA (less than the reference dose) during the 7 days just before birth, and the offspring of the treated rats were evaluated as adults. The locomotor activity and avoidance response of each rat on both test days were compared. The control and BPA groups showed reduced locomotor activity in the presence of the predator odor, but the odor-avoidance response was significant only in the BPA rats. The BPA-exposed rats were obviously sensitive to the predator odor. These results suggest that prenatal BPA exposure has an amplifying effect on avoidance responses to predator odor stress.

Incidence of DCS and oxygen toxicity in chamber attendants: a 28-year experience.

PubMed

Witucki, Pete; Duchnick, Jay; Neuman, Tom; Grover, Ian

2013-01-01

Decompression sickness (DCS) and central nervous system oxygen toxicity are inherent risks for "inside" attendants (IAs) of hyperbaric chambers. At the Hyperbaric Medicine Center at the University of California San Diego (UCSD), protocols have been developed for decompressing IAs. Protocol 1: For a total bottom time (TBT) of less than 80 minutes at 2.4 atmospheres absolute (atm abs) or shallower, the U.S. Navy (1955) no-decompression tables were utilized. Protocol 2: For a TBT between 80 and 119 minutes IAs breathed oxygen for 15 minutes prior to initiation of ascent. Protocol 3: For a TBT between 120-139 minutes IAs breathed oxygen for 30 minutes prior to ascent. These protocols have been utilized for approximately 28 years and have produced zero cases of DCS and central nervous system oxygen toxicity. These results, based upon more than 24,000 exposures, have an upper limit of risk of DCS and oxygen toxicity of 0.02806 (95% CI) using UCSD IA decompression Protocol 1, 0.00021 for Protocol 2, and 0.00549 for Protocol 3. We conclude that the utilization of this methodology may be useful at other sea-level multiplace chambers.

Dynamic behavior of semivolatile organic compounds in indoor air

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

Loy, Michael David Van

1998-12-09

Exposures to a wide range of air pollutants are often dominated by those occurring in buildings because of three factors: 1) most people spend a large fraction of their time indoors, 2) many pollutants have strong indoor sources, and 3) the dilution volume in buildings is generally several orders of magnitude smaller than that of an urban airshed. Semivolatile organic compounds (SVOCS) are emitted by numerous indoor sources, including tobacco combustion, cooking, carpets, paints, resins, and glues, so indoor gasphase concentrations of these compounds are likely to be elevated relative to ambient levels. The rates of uptake and release ofmore » reversibly sorbing SVOCS by indoor materials directly affect both peak concentrations and persistence of the pollutants indoors after source elimination. Thus, accurate predictions of SVOC dynamics in indoor air require an understanding of contaminant sorption on surface materials such as carpet and wallboard. The dynamic behaviors of gas-phase nicotine and phenanthrene were investigated in a 20 ms stainless steel chamber containing carpet and painted wallboard. Each compound was studied independently, first in the empty chamber, then with each sorbent individually, and finally with both sorbents in the chamber.« less

Design, construction, and testing a purpose-built climate-controlled solvent vapor annealing chamber for guided self-assembly of block polymer thin films

NASA Astrophysics Data System (ADS)

Gnabasik, Ryan; Haase, Rustin; Baruth, Andrew

2014-03-01

Despite its efficacy to produce well-ordered, periodic nanostructures, the intricate role multiple parameters play in solvent vapor annealing has not been fully established. In solvent vapor annealing a thin polymer film is exposed to the vapors of a solvent(s) thus forming a swollen and mobile layer to direct the self-assembly process at the nanoscale. Recent developments in both theory and experiment have directly identified critical parameters, but controlling them in any systematic way has proven non-trivial. These identified parameters include vapor pressure, solvent concentration in the film, and, critically, the solvent evaporation rate. To explore their role, a purpose-built solvent vapor annealing chamber was designed and constructed. The all-metal chamber is inert to solvent exposure and pneumatically actuated valves allow for precision timing in the introduction and withdrawal of solvent vapor. Furthermore, the mass flow controlled inlet, chamber pressure gauges, in situ spectral reflectance-based thickness monitoring, and high precision micrometer relief valve, give real-time monitoring and control during the annealing and evaporation phases. Using atomic force microscopy to image the annealed films, we are able to map out the parameter space for a series of polystyrene- b-polylactide (Mn = 75 kg/mol and fPLA = 0.28) block polymer thin films with an intrinsic cylindrical morphology and identify their role in directed assembly. Funded by Creighton University Summer Research Grant.

Liquid Oxygen/Liquid Methane Component Technology Development at MSFC

NASA Technical Reports Server (NTRS)

Robinson, Joel W.

2010-01-01

The National Aeronautics & Space Administration (NASA) has identified Liquid Oxygen (LOX)/Liquid Methane (LCH4) as a potential propellant combination for future space vehicles based upon exploration studies. The technology is estimated to have higher performance and lower overall systems mass compared to existing hypergolic propulsion systems. Besides existing in-house risk reduction activities, NASA has solicited from industry their participation on component technologies based on the potential application to the lunar ascent main engine (AME). Contracted and NASA efforts have ranged from valve technologies to engine system testbeds. The application for the AME is anticipated to be an expendable, pressure-fed engine for ascent from the moon at completion of its lunar stay. Additionally, the hardware is expected to provide an abort capability prior to landing, in the event that descent systems malfunction. For the past 4 years, MSFC has been working with the Glenn Research Center and the Johnson Space Center on methane technology development. This paper will focus on efforts specific to MSFC in pursuing ignition, injector performance, chamber material assessments and cryogenic valve technologies. Ignition studies have examined characteristics for torch, spark and microwave systems. Injector testing has yielded insight into combustion performance for shear, swirl and impinging type injectors. The majority of chamber testing has been conducted with ablative and radiatively cooled chambers with planned activities for regenerative and transpiration cooled chambers. Lastly, an effort is underway to examine the long duration exposure issues of cryogenic valve internal components. The paper will summarize the status of these efforts.

A practical approach to estimate emission rates of indoor air pollutants due to the use of personal combustible products based on small-chamber studies.

PubMed

Szulejko, Jan E; Kim, Ki-Hyun

2016-02-01

As emission rates of airborne pollutants are commonly measured from combusting substances placed inside small chambers, those values need to be re-evaluated for the possible significance under practical conditions. Here, a simple numerical procedure is investigated to extrapolate the chamber-based emission rates of formaldehyde that can be released from various combustible sources including e-cigarettes, conventional cigarettes, or scented candles to their concentration levels in a small room with relatively poor ventilation. This simple procedure relies on a mass balance approach by considering the masses of pollutants emitted from source and lost through ventilation under the assumption that mixing occurs instantaneously in the room without chemical reactions or surface sorption. The results of our study provide valuable insights into re-evaluation procedure of chamber data to allow comparison between extrapolated and recommended values to judge the safe use of various combustible products in confined spaces. If two scented candles with a formaldehyde emission rate of 310 µg h(-1) each were lit for 4 h in a small 20 m(3) room with an air change rate of 0.5 h(-1), then the 4-h (candle lit) and 8-h (up to 8 h after candle lighting) TWA [FA] were determined to be 28.5 and 23.5 ppb, respectively. This is clearly above the 8-h NIOSH recommended exposure limit (REL) time weighted average of 16 ppb. Copyright © 2015 Elsevier Ltd. All rights reserved.

Exposure to wood smoke particles produces inflammation in healthy volunteers.

PubMed

Ghio, Andrew J; Soukup, Joleen M; Case, Martin; Dailey, Lisa A; Richards, Judy; Berntsen, Jon; Devlin, Robert B; Stone, Susan; Rappold, Ana

2012-03-01

Human exposure to wood smoke particles (WSP) impacts on human health through changes in indoor air quality, exposures from wild fires, burning of biomass and air pollution. This investigation tested the postulate that healthy volunteers exposed to WSP would demonstrate evidence of both pulmonary and systemic inflammation. Ten volunteers were exposed to filtered air and, 3 weeks or more later, WSP. Each exposure included alternating 15 min of exercise and 15 min of rest for a total duration of 2 h. Wood smoke was generated by heating an oak log on an electric element and then delivered to the exposure chamber. Endpoints measured in the volunteers included symptoms, pulmonary function tests, measures of heart rate variability and repolarisation, blood indices and analysis of cells and fluid obtained during bronchoalveolar lavage. Mean particle mass for the 10 exposures to air and WSP was measured using the mass of particles collected on filters and found to be below the detectable limit and 485±84 μg/m(3), respectively (mean±SD). There was no change in either symptom prevalence or pulmonary function with exposure to WSP. At 20 h after wood smoke exposure, blood tests demonstrated an increased percentage of neutrophils, and bronchial and bronchoalveolar lavage revealed a neutrophilic influx. We conclude that exposure of healthy volunteers to WSP may be associated with evidence of both systemic and pulmonary inflammation.

Growth and Chemical Responses to CO2 Enrichment Virginia Pine (Pinus Virginiana Mill.) (NDP-009)

DOE Data Explorer

Luxmoore, R. J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Norby, R. J. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); O'Neill, E. G. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Weller, D. G. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (USA); Ells, J. M. [Agricultural Research Service, USDA; North Carolina State University, Raleigh, NC (USA); Rogers, H. H. [Agricultural Research Service, USDA; North Carolina State University, Raleigh, NC (USA)

1985-01-01

From June 28 to October 29 in 1982, Virginia pine seedlings were exposed to elevated CO2 levels in open-top growth chambers at one of four concentrations (75, 150, 300, and 600 ppm above ambient). Plant dry weight; height; stem diameter; and chemical contents of leaf, stem, and root tissues were measured before and after exposure. Soil variables were also characterized. These data illustrate the short-term physical and chemical response of Virginia pine seedlings to elevated levels of CO2. The data are in seven files: initial dry weights before exposure (844 kB), dry weights after exposure (4 kB), major nutrient concentrations after final harvest (12 kB), minor nutrient concentrations after final harvest (17 kB), soil nutrient concentrations after final harvest (4 kB), soil leachate elements after final harvest (5 kB), and soil leachate solutes after final harvest (4 kB).

Results from a search for dark matter in the complete LUX exposure

DOE PAGES

Akerib, D. S.; Alsum, S.; Araújo, H. M.; ...

2017-01-11

Here, we report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35 ×10 4 kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 kg of active mass is operated at the Sanford Underground Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence of WIMP nuclear recoils. At a WIMP mass of 50 GeV c –2, WIMP-nucleon spin-independent cross sections above 2.2 ×10 –46 cm 2 are excluded at the 90%more » confidence level. When combined with the previously reported LUX exposure, this exclusion strengthens to 1.1 × 10 –46 cm 2 at 50 GeV c –2.« less

Optic neuropathy following an altitude exposure.

PubMed

Steigleman, Allan; Butler, Frank; Chhoeu, Austin; O'Malley, Timothy; Bower, Eric; Giebner, Stephen

2003-09-01

This case report describes a 20-yr-old man who presented with retro-orbital pain and blurred vision in his left eye 3 wk after an altitude exposure in a hypobaric chamber. He was found to have significant deficits in color vision and visual fields consistent with an optic neuropathy in his left eye. The patient was diagnosed with decompression sickness and treated with hyperbaric oxygen with a U.S. Navy Treatment Table VI. All signs and symptoms resolved with a single hyperbaric oxygen treatment but recurred. A head MRI revealed a left frontoethmoid sinus opacity. A concomitant sinusitis was diagnosed. The patient had full resolution of symptoms after a total of four hyperbaric oxygen treatments and antibiotic therapy at 6-wk follow-up. Although a para-infectious etiology for this patient's optic neuropathy cannot be excluded, his history of altitude exposure and significant, rapid response to hyperbaric oxygen treatment strongly implies decompression sickness in this case.

Responses of growth, photosynthesis and VOC emissions of Pinus tabulaeformis Carr. Exposure to elevated CO2 and/or elevated O3 in an urban area.

PubMed

Xu, Sheng; Chen, Wei; Huang, Yanqing; He, Xingyuan

2012-03-01

Responses of growth, photosynthesis and emission of volatile organic compounds of Pinus tabulaeformis exposed to elevated CO(2) (700 ppm) and O(3) (80 ppb) were studied in open top chambers. Elevated CO(2) increased growth, but it did not significantly (p > 0.05) affect net photosynthetic rate, stomatal conductance, chlorophyll content, the maximum quantum yield of photosystem II, or the effective quantum yield of photosystem II electron transport after 90 d of gas exposure. Elevated O(3) decreased growth (by 42.2% in needle weight and 25.8% in plant height), net photosynthetic rate and stomatal conductance after 90 d of exposure, but its negative effects were alleviated by elevated CO(2). Elevated O(3) significantly (p < 0.05) increased the emission rate of volatile organic compounds, which may be a helpful response to protect photosynthetic apparatus against O(3) damage.

Results from a Search for Dark Matter in the Complete LUX Exposure.

PubMed

Akerib, D S; Alsum, S; Araújo, H M; Bai, X; Bailey, A J; Balajthy, J; Beltrame, P; Bernard, E P; Bernstein, A; Biesiadzinski, T P; Boulton, E M; Bramante, R; Brás, P; Byram, D; Cahn, S B; Carmona-Benitez, M C; Chan, C; Chiller, A A; Chiller, C; Currie, A; Cutter, J E; Davison, T J R; Dobi, A; Dobson, J E Y; Druszkiewicz, E; Edwards, B N; Faham, C H; Fiorucci, S; Gaitskell, R J; Gehman, V M; Ghag, C; Gibson, K R; Gilchriese, M G D; Hall, C R; Hanhardt, M; Haselschwardt, S J; Hertel, S A; Hogan, D P; Horn, M; Huang, D Q; Ignarra, C M; Ihm, M; Jacobsen, R G; Ji, W; Kamdin, K; Kazkaz, K; Khaitan, D; Knoche, R; Larsen, N A; Lee, C; Lenardo, B G; Lesko, K T; Lindote, A; Lopes, M I; Manalaysay, A; Mannino, R L; Marzioni, M F; McKinsey, D N; Mei, D-M; Mock, J; Moongweluwan, M; Morad, J A; Murphy, A St J; Nehrkorn, C; Nelson, H N; Neves, F; O'Sullivan, K; Oliver-Mallory, K C; Palladino, K J; Pease, E K; Phelps, P; Reichhart, L; Rhyne, C; Shaw, S; Shutt, T A; Silva, C; Solmaz, M; Solovov, V N; Sorensen, P; Stephenson, S; Sumner, T J; Szydagis, M; Taylor, D J; Taylor, W C; Tennyson, B P; Terman, P A; Tiedt, D R; To, W H; Tripathi, M; Tvrznikova, L; Uvarov, S; Verbus, J R; Webb, R C; White, J T; Whitis, T J; Witherell, M S; Wolfs, F L H; Xu, J; Yazdani, K; Young, S K; Zhang, C

2017-01-13

We report constraints on spin-independent weakly interacting massive particle (WIMP)-nucleon scattering using a 3.35×10^{4}  kg day exposure of the Large Underground Xenon (LUX) experiment. A dual-phase xenon time projection chamber with 250 kg of active mass is operated at the Sanford Underground Research Facility under Lead, South Dakota (USA). With roughly fourfold improvement in sensitivity for high WIMP masses relative to our previous results, this search yields no evidence of WIMP nuclear recoils. At a WIMP mass of 50  GeV c^{-2}, WIMP-nucleon spin-independent cross sections above 2.2×10^{-46}  cm^{2} are excluded at the 90% confidence level. When combined with the previously reported LUX exposure, this exclusion strengthens to 1.1×10^{-46}  cm^{2} at 50  GeV c^{-2}.

Atrial and ventricular septal changes in ethanol vapour exposed chick embryos.

PubMed

Kamran, Kiran; Khan, Muhammad Yunus; Minhas, Liaqat Ali

2015-03-01

To study the effects of ethanol vapour exposure on development of atrial and ventricular septa of chick embryo. The experimental study was conducted at the College of Physicians and Surgeons, Islamabad, from 2006 to 2007. The experimental and control groups were further divided into three subgroups based on the day of sacrifice. The experimental group was exposed to ethanol vapours produced in a specially-designed vapour chamber and then compared with age-matched controls. There were 90 eggs in each of the two groups. The development of inter-ventricular septum completed at day 7 of development in chick embryo. Ethanol vapour exposure produced a small discontinuity at day 10 of development in a chick embryo which may be labelled as ventricular septal defect since ventricular development is completed by day 7. Interatrial septum formed till day 7 with small perforations which persisted till hatching. Ethanol vapour exposure may lead to ventricular septal defect.

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

Macauley, J.M.; Clark, J.R.; Pitts, A.R.

Concurrent 12-week laboratory and field studies were conducted to determine toxicity of the suspended particulate phase (SPP) of drilling fluid to Thalassia testudinum and its epiphytes. Test systems were treated once per week to achieve nominal concentrations of 100 mg/L SPP. Chlorophyll content of Thalassia leaves and epiphyte biomass and chlorophyll content were monitored during each test. Laboratory exposures were conducted in 7-L, flow-through (7 L/h) microcosms consisting of Plexiglas cylinders containing intact cores of Thalassia from a local seagrass bed. Field exposures were conducted in water-tight plexiglas chambers (2 m x 2 m x 1.5 m) placed over testmore » plots in a seagrass bed for 24 h during SPP additions. Epiphyte biomass was reduced after 6 weeks of intermittent exposure to SPP in laboratory and field tests. After 12 weeks, epiphyte biomass had increased to densities similar to control values.« less

Dark matter sensitivity of multi-ton liquid xenon detectors

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

Schumann, Marc; Bütikofer, Lukas; Baudis, Laura

2015-10-01

We study the sensitivity of multi ton-scale time projection chambers using a liquid xenon target, e.g., the proposed DARWIN instrument, to spin-independent and spin-dependent WIMP-nucleon scattering interactions. Taking into account realistic backgrounds from the detector itself as well as from neutrinos, we examine the impact of exposure, energy threshold, background rejection efficiency and energy resolution on the dark matter sensitivity. With an exposure of 200 t × y and assuming detector parameters which have been already demonstrated experimentally, spin-independent cross sections as low as 2.5 × 10{sup −49} cm{sup 2} can be probed for WIMP masses around 40 GeV/c{sup 2}. Additional improvementsmore » in terms of background rejection and exposure will further increase the sensitivity, while the ultimate WIMP science reach will be limited by neutrinos scattering coherently off the xenon nuclei.« less

Enhanced Adhesion of EVA Laminates to Primed Glass Substrates Subjected to Damp-Heat Exposure

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

Pern, F. J.; Jorgensen, G. J.

2005-02-01

We investigated the effectiveness of glass-surface priming to promote enhanced adhesion of EVA laminates during damp-heat exposure at 85 C and 85% relative humidity. The primary objective was to develop advanced encapsulant formulations by incorporation of various primer formulations that exhibit improved adhesion during damp-heat exposure. Several primer formulations were identified that greatly enhanced the EVA adhesion strength, including to the extent that peeling could not be initiated, even for the laminates of the glass substrate/fast-cure EVA15295P/TPE backsheet (a Tedlar/polyester/EVA tri-laminate) that were exposed in a damp-heat test chamber for more than 750 h. The results show that a synergisticmore » increase in the interfacial hydrophobicity, siloxane density, and cross-linking density are the key attributes to the improvement in the EVA adhesion strength.« less

In Vitro Exposures in Diesel Exhaust Atmospheres: Resuspension of PM from Filters Verses Direct Deposition of PM from Air

PubMed Central

Lichtveld, Kim M.; Ebersviller, Seth M.; Sexton, Kenneth G.; Vizuete, William; Jaspers, Ilona; Jeffries, Harvey E.

2012-01-01

One of the most widely used in vitro particulate matter (PM) exposures methods is the collection of PM on filters, followed by resuspension in a liquid medium, with subsequent addition onto a cell culture. To avoid disruption of equilibria between gases and PM, we have developed a direct in vitro sampling and exposure method (DSEM) capable of PM-only exposures. We hypothesize that the separation of phases and post-treatment of filter-collected PM significantly modifies the toxicity of the PM compared to direct deposition, resulting in a distorted view of the potential PM health effects. Controlled test environments were created in a chamber that combined diesel exhaust with an urban-like mixture. The complex mixture was analyzed using both the DSEM and concurrently-collected filter samples. The DSEM showed that PM from test atmospheres produced significant inflammatory response, while the resuspension exposures at the same exposure concentration did not. Increasing the concentration of resuspended PM sixteen times was required to yield measurable IL-8 expression. Chemical analysis of the resuspended PM indicated a total absence of carbonyl compounds compared to the test atmosphere during the direct-exposures. Therefore, collection and resuspension of PM into liquid modifies its toxicity and likely leads to underestimating toxicity. PMID:22834915

Aerosol generation and characterization of multi-walled carbon nanotubes exposed to cells cultured at the air-liquid interface.

PubMed

Polk, William W; Sharma, Monita; Sayes, Christie M; Hotchkiss, Jon A; Clippinger, Amy J

2016-04-23

Aerosol generation and characterization are critical components in the assessment of the inhalation hazards of engineered nanomaterials (NMs). An extensive review was conducted on aerosol generation and exposure apparatus as part of an international expert workshop convened to discuss the design of an in vitro testing strategy to assess pulmonary toxicity following exposure to aerosolized particles. More specifically, this workshop focused on the design of an in vitro method to predict the development of pulmonary fibrosis in humans following exposure to multi-walled carbon nanotubes (MWCNTs). Aerosol generators, for dry or liquid particle suspension aerosolization, and exposure chambers, including both commercially available systems and those developed by independent researchers, were evaluated. Additionally, characterization methods that can be used and the time points at which characterization can be conducted in order to interpret in vitro exposure results were assessed. Summarized below is the information presented and discussed regarding the relevance of various aerosol generation and characterization techniques specific to aerosolized MWCNTs exposed to cells cultured at the air-liquid interface (ALI). The generation of MWCNT aerosols relevant to human exposures and their characterization throughout exposure in an ALI system is critical for extrapolation of in vitro results to toxicological outcomes in humans.

An evaluation of the impact of flooring types on exposures to fine and coarse particles within the residential micro-environment using CONTAM.

PubMed

Bramwell, Lisa; Qian, Jing; Howard-Reed, Cynthia; Mondal, Sumona; Ferro, Andrea R

2016-01-01

Typical resuspension activities within the home, such as walking, have been estimated to contribute up to 25% of personal exposures to PM10. Chamber studies have shown that for moderate walking intensities, flooring type can impact the rate at which particles are re-entrained into the air. For this study, the impact of residential flooring type on incremental average daily (24 h) time-averaged exposure was investigated. Distributions of incremental time-averaged daily exposures to fine and coarse PM while walking within the residential micro-environment were predicted using CONTAM, the multizone airflow and contaminant transport program of the National Institute of Standards and Technology. Knowledge of when and where a person was walking was determined by randomly selecting 490 daily diaries from the EPA's consolidated human activity database (CHAD). On the basis of the results of this study, residential flooring type can significantly impact incremental time-averaged daily exposures to coarse and fine particles (α=0.05, P<0.05, N=490, Kruskal-Wallis test) with high-density cut pile carpeting resulting in the highest exposures. From this study, resuspension from walking within the residential micro-environment contributed 6-72% of time-averaged daily exposures to PM10.

Respiratory responses of vigorously exercising children to 0. 12 ppm ozone exposure

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

McDonnell, W.F. 3d.; Chapman, R.S.; Leigh, M.W.

1985-10-01

Changes in respiratory function have been suggested for children exposed to less than 0.12 ppm ozone (O3) while engaged in normal activities. Because the results of these studies have been confounded by other variables, such as temperature or the presence of other pollutants or have been questioned as to the adequacy of exposure measurements, the authors determined the acute response of children exposed to 0.12 ppm O3 in a controlled chamber environment. Twenty-three white males 8 to 11 yr of age were exposed once to clean air and once to 0.12 ppm O3 in random order. Exposures were for 2.5more » h and included 2 h of intermittent heavy exercise. Measures of forced expiratory volume in one second (FEV1) and the symptom cough were determined prior to and after each exposure. A significant decline in FEV1 was found after the O3 exposure compared to the air exposure, and it appeared to persist for 16 to 20 h. No significant increase in cough was found due to O3 exposure. Forced vital capacity, specific airways resistance, respiratory frequency, tidal volume, and other symptoms were measured in a secondary exploratory analysis of this study.« less

Influence of halothane and methoxyflurane on regional brain and spinal cord concentrations of methionine-enkephalin in the rat.

PubMed

Agarwal, R K; Court, M; Chandna, V K; Mohan, A; Engelking, L R; Kumar, A M

1994-01-01

Rats were exposed to either oxygen (controls), 1.5% halothane in oxygen, or methoxyflurane (0.5%) in oxygen over a period of 2 h, then sacrificed at the end of exposure (2-h group), 4 h after removal from environmental chamber (4-h group), or at 24 h following anesthetic exposure (24-h group). Pituitary (excluding the neural lobe, Pit), brain, and spinal cord areas were isolated and processed with Met-enkephalin tissue concentrations determined. In halothane-exposed animals, Met-enkephalin concentrations in pit and across CNS areas studied were significantly lower at 2 h following anesthetic exposure than in control animals. Concentrations of Met-enkephalin in many areas of CNS and Pit of 4-h group approached control levels. Concentrations of Met-enkephalin in all areas studied except spinal cord returned to basal levels by 24 h following halothane exposure. Exposure to methoxyflurane resulted in less dramatic changes in Met-enkephalin concentrations across CNS regions examined. Exposure to methoxyflurane resulted in significant decreases in Met-enkephalin levels in olfactory bulb, thalamus, and hippocampus only. Met-Enkephalin levels did not change significantly in other areas of the central nervous system following methoxyflurane exposure. These results indicate that halothane and methoxyflurane may have differential effects on the endogenous opioid system.

Metrological assessment of a portable analyzer for monitoring the particle size distribution of ultrafine particles.

PubMed

Stabile, Luca; Cauda, Emanuele; Marini, Sara; Buonanno, Giorgio

2014-08-01

Adverse health effects caused by worker exposure to ultrafine particles have been detected in recent years. The scientific community focuses on the assessment of ultrafine aerosols in different microenvironments in order to determine the related worker exposure/dose levels. To this end, particle size distribution measurements have to be taken along with total particle number concentrations. The latter are obtainable through hand-held monitors. A portable particle size distribution analyzer (Nanoscan SMPS 3910, TSI Inc.) was recently commercialized, but so far no metrological assessment has been performed to characterize its performance with respect to well-established laboratory-based instruments such as the scanning mobility particle sizer (SMPS) spectrometer. The present paper compares the aerosol monitoring capability of the Nanoscan SMPS to the laboratory SMPS in order to evaluate whether the Nanoscan SMPS is suitable for field experiments designed to characterize particle exposure in different microenvironments. Tests were performed both in a Marple calm air chamber, where fresh diesel particulate matter and atomized dioctyl phthalate particles were monitored, and in microenvironments, where outdoor, urban, indoor aged, and indoor fresh aerosols were measured. Results show that the Nanoscan SMPS is able to properly measure the particle size distribution for each type of aerosol investigated, but it overestimates the total particle number concentration in the case of fresh aerosols. In particular, the test performed in the Marple chamber showed total concentrations up to twice those measured by the laboratory SMPS-likely because of the inability of the Nanoscan SMPS unipolar charger to properly charge aerosols made up of aggregated particles. Based on these findings, when field test exposure studies are conducted, the Nanoscan SMPS should be used in tandem with a condensation particle counter in order to verify and correct the particle size distribution data. Published by Oxford University Press on behalf of the British Occupational Hygiene Society 2014.

Effect of dim and bright light exposure on some immunological parameters measured under thermal neutral conditions.

PubMed

Hyun, Ki-Ja; Kondo, Masayuki; Koh, Taichin; Tokura, Hiromi; Tamotsu, Satoshi; Oishi, Tadashi

2005-01-01

This study assesses the effects of ambient light conditions, under a thermoneutral environment, on selected immunological parameters of 7 healthy young women (aged 19 to 22 yrs). Subjects entered the bioclimatic chamber at 11: 00 h, controlled at 26 degrees C and 60% relative humidity, a "neutral climate". They lead a well-regulated life in the climatic chamber (pre-condition) while exposed to dim (200 lux) or, on the next day, bright (5000 lux) light between 06 : 00 to 12 : 00 h. Just before the end of each period of light exposure, a blood sample was taken for later immunological assay of white blood cell count (WBC), phagocytosis, interferon-gamma (IFN-gamma), interleukin-4 (IL-4), CD69 T cells (CD69), CD4+CD25+ T cells (CD4+CD25+), and transforming growth factor-beta 1 (TGF-beta1). The results, when compared with the pre-condition, were as follows: 1) CD69 and IFN-gamma increased during normal conditions without thermal stress under dim light; 2) WBC increased and IL-4 decreased under bright light; 3) as shown by the highly significant decrease of TGF-beta1, the immune system was activated under bright light; 4) phagocytosis tended to increase under bright light exposure; 5) CD69 and IFN-gamma were significantly higher, and CD4+CD25+ tended to decrease under bright light; 6) phagocytosis tended to be lower and TGF-beta1 significantly higher under dim light, indicating a decline of immune system function. Taken together, this preliminary single time-point sampling study infers that some parameters are activated (CD69) while others are attenuated (phagocytosis, TGF-beta1) according to the environmental light intensity, dim vs. bright, in women adhering to a standardized routine in the absence of thermal stress. These findings are discussed in terms of inhibition of the sympathetic and excitation of the parasympathetic nervous system under the influence of life-style regularity and daytime bright light exposure.

Direct Visualization of Mucus Production by the Cold-Water Coral Lophelia pertusa with Digital Holographic Microscopy

PubMed Central

Zetsche, Eva-Maria; Baussant, Thierry; Meysman, Filip J. R.; van Oevelen, Dick

2016-01-01

Lophelia pertusa is the dominant reef-building organism of cold-water coral reefs, and is known to produce significant amounts of mucus, which could involve an important metabolic cost. Mucus is involved in particle removal and feeding processes, yet the triggers and dynamics of mucus production are currently still poorly described because the existing tools to study these processes are not appropriate. Using a novel microscopic technique—digital holographic microscopy (DHM)–we studied the mucus release of L. pertusa under various experimental conditions. DHM technology permits μm-scale observations and allows the visualization of transparent mucoid substances in real time without staining. Fragments of L. pertusa were first maintained in flow-through chambers without stressors and imaged with DHM, then exposed to various stressors (suspended particles, particulate food and air exposure) and re-imaged. Under non-stressed conditions no release of mucus was observed, whilst mucus strings and sheaths were produced in response to suspended particles (activated charcoal and drill cuttings sediment) i.e. in a stressed condition. Mucus strings and so-called ‘string balls’ were also observed in response to exposure to particulate food (brine shrimp Artemia salina). Upon air-exposure, mucus production was clearly visible once the fragments were returned to the flow chamber. Distinct optical properties such as optical path length difference (OPD) were measured with DHM in response to the various stimuli suggesting that different mucus types are produced by L. pertusa. Mucus produced to reject particles is similar in refractive index to the surrounding seawater, suggesting that the energy content of this mucus is low. In contrast, mucus produced in response to either food particle addition or air exposure had a higher refractive index, suggesting a higher metabolic investment in the production of these mucoid substances. This paper shows for the first time the potential of DHM technology for the detection, characterization and quantification of mucus production through OPD measurements in L. pertusa. PMID:26840074

Emission of ammonia from indoor concrete wall and assessment of human exposure.

PubMed

Bai, Z; Dong, Y; Wang, Z; Zhu, T

2006-04-01

Addition of urea-based antifreeze admixtures during cement mixing can make it possible to produce concrete cement in construction of buildings in cold weather; this, however, has led to increasing indoor air pollution due to continuous transformation and emission from urea to gaseous ammonia in indoor concrete wall. It is believed that ammonia is harmful to human body and exposure to ammonia can cause some serious symptoms such as headaches, burns, and even permanent damage to the eyes and lungs. In order to understand the emission of ammonia from indoor concrete wall in civil building and assess the health risk of people living in these buildings, the experimental pieces of concrete wall were first prepared by concreting cement and urea-based antifreeze admixtures to simulate the indoor wall in civil building in this work. Then environmental chamber was adopted for studying the effect of temperature, relative humility and air exchange rate on emission of ammonia from experimental pieces of concrete wall. Also the field experiment was made at selected rooms in given civil buildings. Exposure and potential dose of adult and children exposed to indoor/outdoor ammonia in summer and in winter are calculated and evaluated by using Scenario Evaluation Approach. The results indicated that high air exchange rate leads to decreased ammonia concentration, and elevation of temperature causes increasing ammonia concentration and volatilizing rate in chamber. The complete emission of ammonia from the wall containing urea-based antifreeze admixtures needs more than 10 years in general. Ventilating or improving air exchange can play a significant role in reducing ammonia concentration in actual rooms in field experiments. Urea-based antifreeze admixtures in concrete wall can give rise to high exposure and potential dose, especially in summer. Generally, adults have a high potential dose than children, while children have personal average dose rate beyond adults in the same conditions.

Kr 83 m calibration of the 2013 LUX dark matter search

DOE PAGES

Akerib, D. S.; Alsum, S.; Araújo, H. M.; ...

2017-12-26

Here, LUX was the first dark matter experiment to use a 83mKr calibration source. In this paper, we describe the source preparation and injection. We also present several 83mKr calibration applications in the context of the 2013 LUX exposure, including the measurement of temporal and spatial variation in scintillation and charge signal amplitudes, and several methods to understand the electric field within the time projection chamber.

Kr 83 m calibration of the 2013 LUX dark matter search

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

Akerib, D. S.; Alsum, S.; Araújo, H. M.

Here, LUX was the first dark matter experiment to use a 83mKr calibration source. In this paper, we describe the source preparation and injection. We also present several 83mKr calibration applications in the context of the 2013 LUX exposure, including the measurement of temporal and spatial variation in scintillation and charge signal amplitudes, and several methods to understand the electric field within the time projection chamber.

Behavioral Responses to DDT and Pyrethroids Between Anopheles Minimus Species A and C Malaria Vectors in Thailand

DTIC Science & Technology

2005-01-01

and lambdacyhalothrin in contact and noncontact trials* Condition Population Chemical (No. of tests) Number escaped (%) % mortality Escaped Remained...bioassays. Figures 2–5 show the proportions of mosquitoes remaining in the exposure and control chambers under different test conditions and chemical...minimus. Genetica 82: 63–72. 33. van Bortel W, Trung HD, Roelants P, Harbach RE, Backeljau T, Coosemans M, 2000. Molecular identification of Anopheles

An environmental transfer hub for multimodal atom probe tomography

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

Perea, Daniel E.; Gerstl, Stephan S. A.; Chin, Jackson

Environmental control during transfer between instruments is required for specimens sensitive to air or thermal exposure to prevent morphological or chemical changes. Atom Probe Tomography is an expanding technique but commercial instruments remain limited to loading under ambient conditions. Here we describe a multifunctional environmental transfer hub allowing controlled cryogenic, atmospheric and vacuum transfer between an Atom Probe and other instruments containing separate chambers to allow downstream time-resolved in-situ studies.

A critical evaluation of the fish early-life stage toxicity test for engineered nanomaterials: experimental modifications and recommendations.

PubMed

Shaw, Benjamin J; Liddle, Corin C; Windeatt, Kirsten M; Handy, Richard D

2016-09-01

There are concerns that regulatory toxicity tests are not fit for purpose for engineered nanomaterials (ENMs) or need modifications. The aim of the current study was to evaluate the OECD 210 fish, early-life stage toxicity test for use with TiO2 ENMs, Ag ENMs, and MWCNT. Both TiO2 ENMS (≤160 mg l(-1)) and MWCNT (≤10 mg l(-1)) showed limited acute toxicity, whilst Ag ENMs were acutely toxic to zebrafish, though less so than AgNO3 (6-day LC50 values of 58.6 and 5.0 µg l(-1), respectively). Evidence of delayed hatching, decreased body length and increased muscle width in the tail was seen in fish exposed to Ag ENMs. Oedema (swollen yolk sacs) was also seen in fish from both Ag treatments with, for example, mean yolk sac volumes of 17, 35 and 39 µm(3) for the control, 100 µg l(-1) Ag ENMs and 5 µg l(-1) AgNO3 treatments, respectively. Among the problems with the standard test guidelines was the inability to maintain the test solutions within ±20 % of nominal concentrations. Pronounced settling of the ENMs in some beakers also made it clear the fish were not being exposed to nominal concentrations. To overcome this, the exposure apparatus was modified with the addition of an exposure chamber that ensured mixing without damaging the delicate embryos/larvae. This allowed more homogeneous ENM exposures, signified by improved measured concentrations in the beakers (up to 85.7 and 88.1 % of the nominal concentrations from 10 mg l(-1) TiO2 and 50 µg l(-1) Ag ENM exposures, respectively) and reduced variance between measurements compared to the original method. The recommendations include: that the test is conducted using exposure chambers, the use of quantitative measurements for assessing hatching and morphometrics, and where there is increased sensitivity of larvae over embryos to conduct a shorter, larvae-only toxicity test with the ENMs.

Results of investigation of muon fluxes of superhigh energy cosmic rays with X-ray emulsion chambers

NASA Technical Reports Server (NTRS)

Ivanenko, I. P.; Ivanova, M. A.; Kuzmichev, L. A.; Ilyina, N. P.; Mandritskaya, K. V.; Osipova, E. A.; Rakobolskaya, I. V.; Zatsepin, G. T.

1985-01-01

The overall data from the investigation of the cosmic ray muon flux in the range of zenith angles (0-90) deg within the energy range (3.5 to 5.0) TeV is presented. The exposure of large X-ray emulsion chambers underground was 1200 tons. year. The data were processe using the method which was applied in the experiment Pamir and differred from the earlier applied one. The obtained value of a slope power index of the differential energy spectrum of the global muon flux is =3.7 that corresponds to the slope of the pion generation differential spectrum, gamma sub PI = 2.75 + or - .04. The analysis of the muon zenith-angular distribution showed that the contribution of rapid generation muons in the total muon flux agree the best with the value .2% and less with .7% at a 90% reliability level.

An instrument employing electronic counters and an emulsion chamber for studying heavy cosmic ray interactions (JACEE-3)

NASA Technical Reports Server (NTRS)

Austin, R. W.; Meegan, C. A.; Parnell, T. A.; Selig, W. J.; Watts, J. W.; Burnett, T. H.; Iwai, J.; Lord, J. J.; Strauscz, S.; Wilkes, R. J.;

Performance of V-4Cr-4Ti material exposed to DIII-D tokamak environment

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

Tsai, H.; Chung, H.M.; Smith, D.L.

1997-04-01

Test specimens made with the 832665 heat of V-4Cr-4Ti alloy were exposed in the DIII-D tokamak environment to support the installation of components made of a V-4Cr-4Ti alloy in the radiative divertor of the DIII-D. Some of the tests were conducted with the Divertor Materials Evaluation System (DiMES) to study the short-term effects of postvent bakeout, when concentrations of gaseous impurities in the DIII-D chamber are the highest. Other specimens were mounted next to the chamber wall behind the divertor baffle plate, to study the effects of longer-term exposures. By design, none of the specimens directly interacted with the plasma.more » Preliminary results from testing the exposed specimens indicate only minor degradation of mechanical properties. Additional testing and microstructural characterization are in progress.« less

Ozone curbs crown rust

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

Not Available

1970-01-01

Crown rust, the most destructive disease of oats, was suppressed in laboratory fumigation chambers by ozone air pollution levels commonly surpassed in many areas. Whether the effects of air pollution on crown rust are of economic importance under field conditions is yet to be determined. Crown rust, caused by the fungus Puccinia coronata, is particularly destructive in Southern and North Central States, often reducing yields 20 percent or more. Rust pustules on oats were significantly smaller when plants were exposed to 10 parts per hundred million ozone for 6 hours in the light on the 10 days after infection. Aboutmore » half as many rust spores were produced in the ozone chamber as in one protected by carbon filters. Exposure to 10 pphm ozone did not affect viability of spores. Spores produced on exposed plants germinated and penetrated stomates of oat leaves as well as spores produced on unexposed leaves.« less

Cold-welding test environment

NASA Technical Reports Server (NTRS)

Wang, J. T.

1972-01-01

A flight test was conducted and compared with ground test data. Sixteen typical spacecraft material couples were mounted on an experimental research satellite in which a motor intermittently drove the spherical moving specimens across the faces of the fixed flat specimens in an oscillating motion. Friction coefficients were measured over a period of 14-month orbital time. Surface-to-surface sliding was found to be the controlling factor of generating friction in a vacuum environment. Friction appears to be independent of passive vacuum exposure time. Prelaunch and postlaunch tests identical to the flight test were performed in an oil-diffusion-pumped ultrahigh vacuum chamber. Only 50% of the resultant data agreed with the flight data owing to pump oil contamination. Identical ground tests were run in an ultrahigh vacuum facility and a ion-pumped vacuum chamber. The agreement (90%) between data from these tests and flight data established the adequacy of these test environments and facilities.

Chamber catalogues of optical and fluorescent signatures distinguish bioaerosol classes

NASA Astrophysics Data System (ADS)

Hernandez, Mark; Perring, Anne E.; McCabe, Kevin; Kok, Greg; Granger, Gary; Baumgardner, Darrel

2016-07-01

Rapid bioaerosol characterization has immediate applications in the military, environmental and public health sectors. Recent technological advances have facilitated single-particle detection of fluorescent aerosol in near real time; this leverages controlled ultraviolet exposures with single or multiple wavelengths, followed by the characterization of associated fluorescence. This type of ultraviolet induced fluorescence has been used to detect airborne microorganisms and their fragments in laboratory studies, and it has been extended to field studies that implicate bioaerosol to compose a substantial fraction of supermicron atmospheric particles. To enhance the information yield that new-generation fluorescence instruments can provide, we report the compilation of a referential aerobiological catalogue including more than 50 pure cultures of common airborne bacteria, fungi and pollens, recovered at water activity equilibrium in a mesoscale chamber (1 m3). This catalogue juxtaposes intrinsic optical properties and select bandwidths of fluorescence emissions, which manifest to clearly distinguish between major classes of airborne microbes and pollens.

Environmental chamber measurements of mercury flux from coal utilization by-products

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

Pekney, Natalie J.; Martello, Donald; Schroeder, Karl

2009-05-01

An environmental chamber was constructed to measure the mercury flux from coal utilization by-product (CUB) samples. Samples of fly ash, FGD gypsum, and wallboard made from FGD gypsum were tested under both dark and illuminated conditions with or without the addition of water to the sample. Mercury releases varied widely, with 7- day experiment averages ranging from -6.8 to 73 ng/m(2) h for the fly ash samples and -5.2 to 335 ng/m(2) h for the FGD/wallboard samples. Initial mercury content, fly ash type, and light exposure had no observable consistent effects on the mercury flux. For the fly ash samples,more » the effect of a mercury control technology was to decrease the emission. For three of the four pairs of FGD gypsum and wallboard samples, the wallboard sample released less (or absorbed more) mercury than the gypsum.« less

Environmental chamber measurements of mercury flux from coal utilization by-products

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

Pekney, N.J.; Martello, D.V.; Schroeder, K.T.

2009-05-01

An environmental chamber was constructed to measure the mercury flux from coal utilization by-product (CUB) samples. Samples of fly ash, FGD gypsum, and wallboard made from FGD gypsum were tested under both dark and illuminated conditions with or without the addition of water to the sample. Mercury releases varied widely, with 7-day experiment averages ranging from -6.8 to 73 ng/m2 h for the fly ash samples and -5.2 to 335 ng/m2 h for the FGD/wallboard samples. Initial mercury content, fly ash type, and light exposure had no observable consistent effects on the mercury flux. For the fly ash samples, themore » effect of a mercury control technology was to decrease the emission. For three of the four pairs of FGD gypsum and wallboard samples, the wallboard sample released less (or absorbed more) mercury than the gypsum.« less

Inflammatory Cytokines and White Blood Cell Counts ...

EPA Pesticide Factsheets

Epidemiological observations of urban inhalation exposures to diesel exhaust (DE) and ozone (O3) have shown pre-clinical cardiopulmonary responses in humans. Identifying the key biological mechanisms that initiate these health bioindicators is difficult due to variability in environmental exposure in time and from person to person. Previously, environmentally controlled human exposure chambers have been used to study DE and O3 dose-response patterns separately, but investigation of co-exposures has not been performed under controlled conditions. Because a mixture is a more realistic exposure scenario for the general public, in this study we investigate the relationships of urban levels of urban-level DE exposure (300 μg/m3), O3 (0.3 ppm), DE + O3 co-exposure, and innate immune system responses. Fifteen healthy human volunteers were studied for changes in ten inflammatory cytokines (interleukins 1β, 2, 4, 5, 8, 10, 12p70 and 13, IFN-γ, and TNF-α) and counts of three white blood cell types (lymphocytes, monocytes, and neutrophils) following controlled exposures to DE, O3, and DE+O3. The results show subtle cytokines responses to the diesel-only and ozone-only exposures, and that a more complex (possibly synergistic) relationship exists in the combination of these two exposures with suppression of IL-5, IL-12p70, IFN-γ, and TNF-α that persists up to 22-hours for IFN-γ and TNF-α. The white blood cell differential counts showed significant monocyte and lympho

Post-Session Administration of USP Methylene Blue Facilitates the Retention of Pathological Fear Extinction and Contextual Memory in Phobic Adults

PubMed Central

Telch, Michael J.; Bruchey, Aleksandra K.; Rosenfield, David; Cobb, Adam R.; Smits, Jasper; Pahl, Sandra; Gonzalez-Lima, F.

2015-01-01

Objective Preclinical studies have shown that low-dose USP methylene blue increases mitochondrial cytochrome oxidase activity in the brain and improves memory retention after learning tasks, including fear extinction. We report on the first controlled experiment to examine the memory-enhancing effects of post-training methylene blue administration on retention of fear extinction and contextual memory following fear extinction training. Method Adults (N = 42) displaying marked claustrophobic fear were randomized to double-blind administration of 260 mg of methylene blue versus placebo immediately following six five-minute extinction trials to an enclosed chamber. Retesting occurred one month later to assess fear renewal as indexed by peak fear during exposure to a non-trained enclosed chamber with the prediction that methylene blue's effects would vary as a function of fear reduction achieved during extinction training. Incidental contextual memory was assessed 1 and 30 days after training to assess the cognitive enhancing effects of methylene blue independent of its effects on fear attenuation. Results Consistent with predictions, participants displaying low end fear at post-training showed significantly less fear at follow-up if they received methylene blue post-training relative to placebo. In contrast, participants displaying moderate to high levels of post-training fear tended to fare worse at follow-up relative to placebo. Methylene blue's enhancement of contextual memory was unrelated to initial or post-training claustrophobic fear. Conclusions Methylene blue enhances memory and the retention of fear extinction when administered after a successful exposure session, but may have a deleterious effect on extinction when administered after an unsuccessful exposure session. PMID:25018057

Effects of post-session administration of methylene blue on fear extinction and contextual memory in adults with claustrophobia.

PubMed

Telch, Michael J; Bruchey, Aleksandra K; Rosenfield, David; Cobb, Adam R; Smits, Jasper; Pahl, Sandra; Gonzalez-Lima, F

2014-10-01

Preclinical studies have shown that low-dose methylene blue increases mitochondrial cytochrome oxidase activity in the brain and improves memory retention after learning tasks, including fear extinction. The authors report on the first controlled experiment to examine the memory-enhancing effects of posttraining methylene blue administration on retention of fear extinction and contextual memory following fear extinction training. Adult participants displaying marked claustrophobic fear were randomly assigned to double-blind administration of 260 mg of methylene blue (N=23) or administration of placebo (N=19) immediately following six 5-minute extinction trials in an enclosed chamber. Retesting occurred 1 month later to assess fear renewal as indexed by peak fear during exposure to a nontraining chamber, with the prediction that the effects of methylene blue would vary as a function of fear reduction achieved during extinction training. Incidental contextual memory was assessed 1 and 30 days after training to assess the cognitive-enhancing effects of methylene blue independent of its effects on fear attenuation. Consistent with predictions, participants displaying low end fear posttraining showed significantly less fear at the 1-month follow-up if they received methylene blue posttraining compared with placebo. In contrast, participants displaying moderate to high levels of posttraining fear tended to fare worse at the follow-up if they received methylene blue posttraining. Methylene blue's enhancement of contextual memory was unrelated to initial or posttraining claustrophobic fear. Methylene blue enhances memory and the retention of fear extinction when administered after a successful exposure session but may have a deleterious effect on extinction when administered after an unsuccessful exposure session.

The emulsion chamber technology experiment

NASA Technical Reports Server (NTRS)

Gregory, John C.

1992-01-01

Photographic emulsion has the unique property of recording tracks of ionizing particles with a spatial precision of 1 micron, while also being capable of deployment over detector areas of square meters or 10's of square meters. Detectors are passive, their cost to fly in Space is a fraction of that of instruments of similar collecting. A major problem in their continued use has been the labor intensiveness of data retrieval by traditional microscope methods. Two factors changing the acceptability of emulsion technology in space are the astronomical costs of flying large electronic instruments such as ionization calorimeters in Space, and the power and low cost of computers, a small revolution in the laboratory microscope data-taking. Our group at UAH made measurements of the high energy composition and spectra of cosmic rays. The Marshall group has also specialized in space radiation dosimetry. Ionization calorimeters, using alternating layers of lead and photographic emulsion, to measure particle energies up to 10(exp 15) eV were developed. Ten balloon flights were performed with them. No such calorimeters have ever flown in orbit. In the ECT program, a small emulsion chamber was developed and will be flown on the Shuttle mission OAST-2 to resolve the principal technological questions concerning space exposures. These include assessments of: (1) pre-flight and orbital exposure to background radiation, including both self-shielding and secondary particle generation; the practical limit to exposure time in space can then be determined; (2) dynamics of stack to optimize design for launch and weightlessness; and (3) thermal and vacuum constraints on emulsion performance. All these effects are cumulative and affect our ability to perform scientific measurements but cannot be adequately predicted by available methods.

Modeling particle dispersion and deposition in indoor environments

NASA Astrophysics Data System (ADS)

Gao, N. P.; Niu, J. L.

Particle dispersion and deposition in man-made enclosed environments are closely related to the well-being of occupants. The present study developed a three-dimensional drift-flux model for particle movements in turbulent indoor airflows, and combined it into Eulerian approaches. To account for the process of particle deposition at solid boundaries, a semi-empirical deposition model was adopted in which the size-dependent deposition characteristics were well resolved. After validation against the experimental data in a scaled isothermal chamber and in a full-scale non-isothermal environmental chamber, the drift-flux model was used to investigate the deposition rates and human exposures to particles from two different sources with three typical ventilation systems: mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD). For particles originating from the supply air, a V-shaped curve of the deposition velocity variation as a function of particle size was observed. The minimum deposition appeared at 0.1- 0.5μm. For supermicron particles, the ventilation type and air exchange rate had an ignorable effect on the deposition rate. The movements of submicron particles were like tracer gases while the gravitational settling effect should be taken into account for particles larger than 2.5μm. The temporal increment of human exposure to a step-up particle release in the supply air was determined, among many factors, by the distance between the occupant and air outlet. The larger the particle size, the lower the human exposure. For particles released from an internal heat source, the concentration stratification of small particles (diameter <10μm) in the vertical direction appeared with DV and UFAD, and it was found the advantageous principle for gaseous pollutants that a relatively less-polluted occupied zone existed in DV and UFAD was also applicable to small particles.

Emissions of volatile organic compounds from building materials and consumer products

NASA Astrophysics Data System (ADS)

Wallace, Lance A.; Pellizzari, Edo; Leaderer, Brian; Zelon, Harvey; Sheldon, Linda

EPA's TEAM Study of personal exposure to volatile organic compounds (VOC) in air and drinking water of 650 residents of seven U.S. cities resulted in the identification of a number of possible sources encountered in peoples' normal daily activities and in their homes. A follow-up EPA study of publicaccess buildings implicated other potential sources of exposure. To learn more about these potential sources, 15 building materials and common consumer products were analyzed using a headspace technique to detect organic emissions and to compare relative amounts. About 10-100 organic compounds were detected offgassing from each material. Four mixtures of materials were then chosen for detailed study: paint on sheetrock; carpet and carpet glue; wallpaper and adhesives; cleansers and a spray pesticide. The materials were applied as normally used, allowed to age 1 week (except for the cleansers and pesticides, which were used normally during the monitoring period), and placed in an environmentally controlled chamber. Organic vapors were collected on Tenax-GC over a 4-h period and analyzed by GC-MS techniques. Emission rates and chamber concentrations were calculated for 17 target chemicals chosen for their toxic, carcinogenic or mutagenic properties. Thirteen of the 17 chemicals were emitted by one or more of the materials. Elevated concentrations of chloroform, carbon tetrachloride, 1,1,1-trichloroethane, n-decane, n-undecane, p-dichlorobenzene, 1,2-dichloroethane and styrene were produced by the four mixtures of materials tested. For some chemicals, these amounts were sufficient to account for a significant fraction of the elevated concentrations observed in previous indoor air studies. We conclude that common materials found in nearly every home and place of business may cause elevated exposures to toxic chemicals.

Repeated stressor exposure enhances contextual fear memory in a beta-adrenergic receptor-dependent process and increases impulsivity in a non-beta receptor-dependent fashion.

PubMed

Camp, Robert M; Johnson, John D

2015-10-15

Memory formation is promoted by stress via the release of norepinephrine and stimulation of beta-adrenergic receptors (β-ARs). Previous data demonstrate that repeated stressor exposure increases norepinephrine turnover and β-AR signaling within the amygdala, which led to the hypothesis that some stress-induced behavioral changes are likely due to facilitated associative learning. To test this, Fischer rats were exposed to chronic mild stress for four days. On day 5, subjects (including non-stressed controls) were injected with the beta-blocker propranolol or vehicle prior to conditioning in an operant box (animals receive two mild foot shocks) or passive avoidance apparatus (animals received a foot shock upon entry into the dark chamber). Twenty-four hours later, subjects were returned to the operant box for measurement of freezing or returned to the passive avoidance apparatus for measurement of latency to enter the dark chamber. Subjects were also tested in an open field to assess context-independent anxiety-like behavior. Animals exposed to chronic stress showed significantly more freezing behavior in the operant box than did controls, and this exaggerated freezing was blocked by propranolol during the conditioning trial. There was no effect of stress on behavior in the open field. Unexpectedly, retention latency was significantly reduced in subjects exposed to chronic stress. These results indicate that chronic exposure to stress results in complex behavioral changes. While repeated stress appears to enhance the formation of fearful memories, it also results in behavioral responses that resemble impulsive behaviors that result in poor decision-making. Copyright © 2015 Elsevier Inc. All rights reserved.

Progesterone concentrations during estrous cycle of dairy cows exposed to electric and magnetic fields.

PubMed

Burchard, J F; Nguyen, D H; Block, E

1998-01-01

Sixteen multiparous nonpregnant lactating Holstein cows (each weighing 662 +/- 65 kg in 150.4 +/- 40 day of lactation) were confined to wooden metabolic cages with 12:12 h light:dark cycle during the experiment. The cows were divided into two sequences of eight cows each and exposed to electric and magnetic fields (EMF) in an exposure chamber. This chamber produced a vertical electric field of 10 kV/m and a uniform horizontal magnetic field of 30 microT at 60 Hz. One sequence was exposed for three estrous cycles of 24 to 27 days. During the first estrous cycle, the electric and magnetic fields were off; during the second estrous cycle, they were on; and during the third estrous cycle, they were off. The second sequence was also exposed for three 24 to 26 days estrous cycles, but the exposure to the fields was reversed (first estrous cycle, on; second estrous cycle, off; third estrous cycle, on). The length of each exposure period (21 to 27 days) varied according to the estrous cycle length. No differences were detected in plasma progesterone concentrations and area under the progesterone curve during estrous cycles between EMF nonexposed and exposed periods (2.28 +/- 0.17 and 2.25 +/- 0.17; and 24.5 +/- 1.9 vs. 26.4 +/- 1.9 ng/ml, respectively). However, estrous cycle length, determined by the presence of a functional corpus luteum detected by concentrations of progesterone equal to or more than 1 ng/ml plasma, was shorter in nonexposed cows than when they were exposed to EMF (22.0 +/- 0.9 vs. 25.3 +/- 1.4 days).

Turbulent eddy diffusion models in exposure assessment - Determination of the eddy diffusion coefficient.

PubMed

Shao, Yuan; Ramachandran, Sandhya; Arnold, Susan; Ramachandran, Gurumurthy

2017-03-01

The use of the turbulent eddy diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic eddy diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by eddy diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43-2.89 ACHs). An eddy diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent eddy diffusion models for exposure assessment in workplace/indoor environments more practical.

Mass carbon monoxide poisoning among television viewers of a football match.

PubMed

Godoy, P; Pont, C; Artigues, A; Alsedà, M

2016-11-01

The objective was to study a mass carbon monoxide (CO) poisoning and the characteristics of the asymptomatic cases. On the 2nd of February, 2015, a group of more than 30 television viewers of a football match contacted the emergency department due to suspected CO poisoning from a butane stove. A visual inspection of the location of the exposure and a descriptive epidemiological study were conducted. Based on the type of variable, the presence of a statistical association was studied with Fisher's exact test or the Kruskal-Wallis test. Thirty-four of the 39 individuals were affected (87.2%). The exposed individuals had a mean age of 43.8 years (SD, 22.1), and 28.2% (11/39) were women. The time of exposure was 52.4min (SD, 21.0), and the mean distance from the oven was 4.2m (SD, 2.5). The most common symptoms were headache (50%), nausea (20.6%), weakness (20.6%) and dizziness (14.7%). The carboxyhaemoglobin (COHb) levels were very high (13.8% ±5.8%). Some 97.1% of the individuals required oxygen therapy, and 39.4% required hyperbaric chamber treatment. Some 29.5% of the cases had no symptoms but showed COHb levels similar to those that did have symptoms (13.6% vs. 15.3%, nonsignificant difference). The asymptomatic cases had a shorter exposure time (38.3min vs. 53.3min; P<.036). Almost a third of the exposed individuals were asymptomatic, even with COHb levels similar to those of the symptomatic patients, and the majority of these asymptomatic patients even required oxygen treatment in a hyperbaric chamber. Copyright © 2016 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

Tritium retention in S-65 beryllium after 100 eV plasma exposure

NASA Astrophysics Data System (ADS)

Causey, Rion A.; Longhurst, Glen R.; Harbin, Wally

1997-02-01

The tritium plasma experiment (TPE) has been used to measure the retention of tritium in S-65 beryllium under conditions similar to that expected for the international thermonuclear experimental reactor (ITER). Beryllium samples 2 mm thick and 50 mm in diameter were exposed to a plasma of tritium and deuterium. The particle flux striking the samples was varied from approximately 1 × 10 17 ( D + T)/ cm2s up to about 3 × 10 18 ( D + T)/ cm2s. The beryllium samples were negatively biased to elevate the energy of the impinging ions to 100 eV. The temperature of the samples was varied from 373 K to 973 K. Exposure times of 1 h were used. Subsequent to the plasma exposure, the samples were outgassed in a separate system where 99% He and 1% H 2 gas was swept over the samples during heating. The sweep gas along with the released tritium was sent through an ionization chamber, through a copper oxide catalyst bed, and into a series of glycol bubblers. The amount of released tritium was determined both by the ionization chamber and by liquid scintillation counting of the glycol. Tritium retention in the beryllium disks varied from a high of 2.4 × 10 17 ( D + T)/ cm2 at 373 K to a low of 1 × 10 16 ( D + T)/ cm2 at 573 K. For almost every case, the tritium retention in the beryllium was less than that calculated using the C = 0 boundary condition at the plasma facing surface. It is believed that this lower than expected retention is due to rapid release of tritium from the large specific surface area created in the implant zone due to the production of voids, bubbles, and blisters.