Simulation for estimation of hydrogen sulfide scavenger injection dose rate for treatment of crude oil

Directory of Open Access Journals (Sweden)

T.M. Elshiekh

2015-12-01

Full Text Available The presence of hydrogen sulfide in the hydrocarbon fluids is a well known problem in many oil and gas fields. Hydrogen sulfide is an undesirable contaminant which presents many environmental and safety hazards. It is corrosive, malodorous, and toxic. Accordingly, a need has been long left in the industry to develop a process which can successfully remove hydrogen sulfide from the hydrocarbons or at least reduce its level during the production, storage or processing to a level that satisfies safety and product specification requirements. The common method used to remove or reduce the concentration of hydrogen sulfide in the hydrocarbon production fluids is to inject the hydrogen sulfide scavenger into the hydrocarbon stream. One of the chemicals produced by the Egyptian Petroleum Research Institute (EPRI is EPRI H2S scavenger. It is used in some of the Egyptian petroleum producing companies. The injection dose rate of H2S scavenger is usually determined by experimental lab tests and field trials. In this work, this injection dose rate is mathematically estimated by modeling and simulation of an oil producing field belonging to Petrobel Company in Egypt which uses EPRI H2S scavenger. Comparison between the calculated and practical values of injection dose rate emphasizes the real ability of the proposed equation.

Scavenging and recombination kinetics in a radiation spur: The successive ordered scavenging events

Science.gov (United States)

Al-Samra, Eyad H.; Green, Nicholas J. B.

2018-03-01

This study describes stochastic models to investigate the successive ordered scavenging events in a spur of four radicals, a model system based on a radiation spur. Three simulation models have been developed to obtain the probabilities of the ordered scavenging events: (i) a Monte Carlo random flight (RF) model, (ii) hybrid simulations in which the reaction rate coefficient is used to generate scavenging times for the radicals and (iii) the independent reaction times (IRT) method. The results of these simulations are found to be in agreement with one another. In addition, a detailed master equation treatment is also presented, and used to extract simulated rate coefficients of the ordered scavenging reactions from the RF simulations. These rate coefficients are transient, the rate coefficients obtained for subsequent reactions are effectively equal, and in reasonable agreement with the simple correction for competition effects that has recently been proposed.

Reduction of cathodic delamination rates of anticorrosive coatings using free radical scavengers

DEFF Research Database (Denmark)

Sørensen, Per Aggerholm; Weinell, C. E.; Dam-Johansen, Kim

2010-01-01

Cathodic delamination is one of the major modes of failure for anticorrosive coatings subjected to a physical damage and immersed in seawater. The cause of cathodic delamination has been reported to be the result of a chemical attack at the coating-steel interface by free radicals and peroxides...... formed as intermediates in the cathodic reaction during the corrosion process. In this study, antioxidants (i.e., free radical scavengers and peroxide decomposers) have been incorporated into various generic types of coatings to investigate the effect of antioxidants on the rate of cathodic delamination...... of epoxy coatings on cold rolled steel. The addition of free radical scavengers to epoxy coatings improved the resistance toward cathodic delamination by up to 50% during seawater immersion, while peroxide decomposers had a limited effect. Testing using substrates prepared from stainless steel...

Hygroscopic growth of atmospheric aerosol particles and its relation to nucleation scavenging in clouds

Energy Technology Data Exchange (ETDEWEB)

Svenningsson, B.

1997-11-01

Aerosol particles in the atmosphere are important in several aspects. Some major aerosol constituents that are deposited in ecosystems are acidic or fertilizers and some minor or trace constituents are toxic. Aerosol particles are also involved in the earth`s radiation balance, both directly by scattering the sunlight and indirectly by influencing the clouds. All these effects are influenced by the interaction between the aerosol particles and water vapour. A tandem differential mobility analyser (TDMA) has been designed to measure hygroscopic growth, i.e. the particle diameter change due to uptake of water at well defined relative humidities below 100%. Tests of the instrument performance have been made using aerosol particles of pure inorganic salts. Three field experiments have been performed as parts of large fog and cloud experiments. Bimodal hygroscopic growth spectra were found: less-hygroscopic particles containing a few percent and more-hygroscopic particles around 50% by volume of hygroscopically active material. In general the fraction of less-hygroscopic particles decreases with particle size and it is larger in polluted continental aerosols than in remote background aerosols. This external mixing cannot be fully understood using present views on the formation of aerosols. Evidence or the importance of the external mixing on the cloud nucleating properties of the particles are found in comparisons between hygroscopic growth spectra for the total aerosol, the interstitial aerosol in clouds, and cloud drop residuals. Cloud condensation nuclei spectra, calculated using aerosol particle size distributions and hygroscopic growth spectra, in combination with information on the major inorganic ions are presented. These CCN spectra reveal for instance that the influence of less-hygroscopic particles on the cloud droplets increases with increasing peak supersaturation. The fraction of the particles that were scavenged to cloud drops, as a function of particle

Scavenger

DEFF Research Database (Denmark)

2009-01-01

Scavenger is one of the cyber foraging frameworks developed in the Locusts project. It has been released as open source software at http://code.google.com/p/scavenger-cf/......Scavenger is one of the cyber foraging frameworks developed in the Locusts project. It has been released as open source software at http://code.google.com/p/scavenger-cf/...

Natural and anthropogenic radionuclide distributions in the Nansen Basin, Artic Ocean: Scavenging rates and circulation timescales

Science.gov (United States)

Kirk Cochran, J.; Hirschberg, David J.; Livingston, Hugh D.; Buesseler, Ken O.; Key, Robert M.

Determination of the naturally occurring radionuclides 232Th, 230Th, 228 Th and 210Pb, and the anthropogenic radionuclides 241Am, 239,240Pu, 134Cs and 137Cs in water samples collected across the Nansen Basin from the Barents Sea slope to the Gakkel Ridge provides tracers with which to characterize both scavenging rates and circulation timescales in this portion of the Arctic Ocean. Large volume water samples (˜ 15001) were filtered in situ to separate particulate (> 0.5 μm) and dissolved Th isotopes and 241Am. Thorium-230 displays increases in both particulate and dissolved activities with depth, with dissolved 230Th greater and particulate 230Th lower in the deep central Nansen Basin than at the Barents Sea slope. Dissolved 228Th activities also are greater relative to 228Ra, in the central basin. Residence times for Th relative to removal from solution onto particles are ˜1 year in surface water, ˜10 years in deep water adjacent to the Barents Sea slope, and ˜20 years in the Eurasian Basin Deep Water. Lead-210 in the central basin deep water also has a residence time of ˜20 years with respect to its removal from the water column. This texture of scavenging is reflected in distributions of the particle-reactive anthropogenic radionuclide 241Am, which shows higher activities relative to Pu in the central Nansen Basin than at the Barents Sea slope. Distributions Of 137Cs show more rapid mixing at the basin margins (Barents Sea slope in the south, Gakkel Ridge in the north) than in the basin interior. Cesium-137 is mixed throughout the water column adjacent to the Barents Sea slope and is present in low but detectable activities in the Eurasian Basin Deep Water in the central basin. At the time of sampling (1987) the surface water at all stations had been labeled with 134Cs released in the 1986 accident at the Chernobyl nuclear power station. In the ˜1 year since the introduction of Chernobyl 134Cs to the Nansen Basin, it had been mixed to depths of ˜800 m at

The influence of particle composition on Thorium scavenging in the Mediterranean Sea

International Nuclear Information System (INIS)

Roy-Barman, M.; Lemaitre, C.; Ayrault, S.; Lemaitre, C.; Jeandel, C.; Souhaut, M.

2009-01-01

Sediment trap data are crucial for the study of marine biochemical cycles but they need careful validation by Thorium (Th) isotopes. In the present study, 230 Th, 232 Th, Uranium (U), Aluminum (Al), Barium (Ba) and Manganese (Mn) were analyzed in sinking particles collected by moored sediment traps in the Ligurian sea (DYFAMED site) in order to determine the collection efficiency of the traps and to constrain which particulate phase(s) carries Th isotopes in a region with strong lithogenic inputs. The 230 Th xs evaluation was based on the U content of each sample rather than on the 232 Th content of each sample and the average 238 U/ 232 Th ratio of the continental crust because the latter method introduced too much uncertainty in the calculation. High trapping efficiencies (187 ± 85% at 200 m and 87 ± 11% at 1000 m) indicated no evidence of particle under-collection by the traps. The lack of correlation between 230 Th xs and the carbonate or the organic matter fraction suggests that these phases are not major 230 Th xs -carrying phases in the deep ocean. For most samples of the time series, the 230 Th xs concentration is correlated with the lithogenic fraction and the Mn concentration, but pulses of particles with high lithogenic and Mn content and low 230 Th xs concentration occur in winter. Assuming that 230 Th xs is only carried by lithogenic particles, we estimate K d Th litho ranges from (0.42 ± 0.04) * 10 7 ml/g to (0.8 ± 0.2) * 10 7 ml/g. Assuming that 230 Th xs is only carried by authigenic Mn oxide precipitates (MnO 2 ), we estimate that K d Th MnO2 ) ranges from (0.6 ± 0.1) * 10 10 ml/g to (1.1 ± 0.4) * 10 10 ml/g. The relative variation of K d T h MnO2 ) (a factor 7) between different oceanic sites is significantly lower than the relative variation of K d Th litho (a factor 50), suggesting that 230 Th xs has a tighter link with MnO 2 rather than with lithogenic particles and hence that 230 Th xs may be more likely scavenged by MnO 2 than by

Variational transition-state theory study of the rate constant of the DMS·OH scavenging reaction by O2.

Science.gov (United States)

Ramírez-Anguita, Juan M; González-Lafont, Àngels; Lluch, José M

2011-07-30

The chemical tropospheric dimethyl sulfide (DMS, CH3SCH3) degradation involves several steps highly dependent on the environmental conditions. So, intensive efforts have been devoted during the last years to enhance the understanding of the DMS oxidation mechanism under different conditions. The reaction of DMS with OH is considered to be the most relevant process that initiates the whole oxidation process. The experimental observations have been explained by a two-channel mechanism consisting of a H-abstraction process leading to CH3S(O)CH3 and HO2 and an addition reaction leading to the DMS·OH adduct. In the presence of O2, the DMS·OH adduct is competitively scavenged increasing the contribution of the addition channel to the overall DMS oxidation. Recent experimental measurements have determined from a global fit that the rate constant of this scavenging process is independent of pressure and temperature but this rate constant cannot be directly measured. In this article, a variational transition-state theory calculation of the low- and high-pressure rate constants for the reaction between DMS·OH and O2 has been carried out as a function of temperature. Our proposal is that the slight temperature dependence of the scavenging rate constant can only be explained if the H-abstraction bottleneck is preceded by a dynamical bottleneck corresponding to the association process between the DMS·OH adduct and the O2 molecule. The agreement between the low-pressure and high-pressure rate constants confirms the experimental observations. Copyright © 2011 Wiley Periodicals, Inc.

Correlation between the Inhibition of Positronium Formation by Scavenger Molecules, and Chemical Reaction Rate of Electrons with these Molecules in Nonpolar Liquids

DEFF Research Database (Denmark)

Levay, B.; Mogensen, O. E.

1977-01-01

a correlation between the inhibition coefficient and the chemical rate constant of electrons with scavenger molecules. We found that the dependence of the inhibition coefficient on the work function (VOo)f electrons in different liquids shows a very unusual behavior, similar to that recently found...... for the chemical rate constants of quasifree electrons with the same scavenger molecules. The inhibition coefficient as a function of Vo had a maximum for C2HsBr, while it increased monotonously with decreasing V, for CC14. The inhibition coefficient for C2H5Br in a 1:l molar tetramethylsilane......-n-tetradecane mixture was found to be greater than in both of the pure components. The clear correlation found between electron scavenging rate constants and positronium inhibition constitutes the severest test to date of the spur reaction model of positronium formation. The importance of the positron annihilation...

The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels

Science.gov (United States)

Khan, Muzafar; Heilemann, Gerd; Kuess, Peter; Georg, Dietmar; Berg, Andreas

2018-03-01

Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D), which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates. Some commonly used polymer gels are based on Methacrylic-Acid-Gel-Initiated-by-Copper (MAGIC). Here, we report on the dose sensitivity (ΔR2/ΔD) of MAGIC-type gels with different oxygen scavenger concentration for their specific dependence on the applied dose rate in order to improve the dosimetric performance, especially for high dose rates. A preclinical x-ray machine (‘Yxlon’, E  =  200 kV) was used for irradiation to cover a range of dose rates from low \\dot{D} min  =  0.6 Gy min-1 to high \\dot{D} max  =  18 Gy min-1. The dose response was evaluated using R2-imaging of the gel on a human high-field (7T) MR-scanner. The results indicate that all of the investigated dose rates had an impact on the dose response in polymer gel dosimeters, being strongest in the high dose region and less effective for low dose levels. The absolute dose rate dependence \\frac{(Δ R2/Δ D)}{Δ \\dot{D}} of the dose response in MAGIC-type gel is significantly reduced using higher concentrations of oxygen scavenger at the expense of reduced dose sensitivity. For quantitative dose evaluations the relative dose rate dependence of a polymer gel, normalized to its sensitivity is important. Based on this normalized sensitivity the dose rate sensitivity was reduced distinctly

Precipitation Scavenging of Aerosol Particles at a Rural Site in the Czech Republic.

Czech Academy of Sciences Publication Activity Database

Zíková, Naděžda; Ždímal, Vladimír

2016-01-01

Roč. 67, č. 2016 (2016), s. 27343 ISSN 0280-6509 R&D Projects: GA ČR GAP209/11/1342 EU Projects: European Commission(XE) 654109 - ACTRIS-2; European Commission(XE) 262254 - ACTRIS Institutional support: RVO:67985858 Keywords : below- cloud scavenging * in- cloud scavenging * hydrometeors Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.402, year: 2015

@u234@@Th scavenging and particle export fluxes from the upper 100 m of the Arabian Sea

Digital Repository Service at National Institute of Oceanography (India)

Sarin, M.M.; Rengarajan, R.; Ramaswamy, V.

for the upper 100 m yields a mean scavenging residence time of ~k30 days and a removal rate of ~k 3400 dpm m@u-2@@ d@u-1@@ for @u234@@Th, from dissolved to particulate phases. The deficiency of total @u234@@Th (dissolved + particulate) relative to @u238@@U...

Determination of photoformation rates and scavenging rate constants of hydroxyl radicals in natural waters using an automatic light irradiation and injection system

International Nuclear Information System (INIS)

Nakatani, Nobutake; Hashimoto, Norichika; Shindo, Hirotaka; Yamamoto, Masatoshi; Kikkawa, Megumi; Sakugawa, Hiroshi

2007-01-01

Photoformation rates and scavenging rate constants of hydroxyl radicals (·OH) in natural water samples were determined by an automatic determination system. After addition of benzene as a chemical probe to a water sample in a reaction cell, light irradiation and injection of irradiated water samples into an HPLC as a function of time were performed automatically. Phenol produced by the reaction between ·OH and the benzene added to the water sample was determined to quantify the ·OH formation rate. The rate constants of ·OH formation from the photolysis of nitrate ions, nitrite ions and hydrogen peroxide were comparable with those obtained in previous studies. The percent of expected ·OH photoformation rate from added nitrate ion were high in drinking water (97.4%) and river water (99.3%). On the other hand, the low percent (65.0%) was observed in seawater due to the reaction of ·OH with the high concentrations of chloride and bromide ions. For the automatic system, the coefficient of variance for the determination of the ·OH formation rate was less than 5.0%, which is smaller than that in the previous report. When the complete time sequence of analytical cycle was 40 min for one sample, the detection limit of the photoformation rate and the sample throughput were 8 x 10 -13 M s -1 and 20 samples per day, respectively. The automatic system successfully determined the photoformation rates and scavenging rate constants of ·OH in commercial drinking water and the major source and sink of ·OH were identified as nitrate and bicarbonate ions, respectively

Separation of nanoparticles: Filtration and scavenging from waste incineration plants.

Science.gov (United States)

Förster, Henning; Thajudeen, Thaseem; Funk, Christine; Peukert, Wolfgang

2016-06-01

Increased amounts of nanoparticles are applied in products of everyday life and despite material recycling efforts, at the end of their life cycle they are fed into waste incineration plants. This raises the question on the fate of nanoparticles during incineration. In terms of environmental impact the key question is how well airborne nanoparticles are removed by separation processes on their way to the bag house filters and by the existing filtration process based on pulse-jet cleanable fibrous filter media. Therefore, we investigate the scavenging and the filtration of metal nanoparticles under typical conditions in waste incineration plants. The scavenging process is investigated by a population balance model while the nanoparticle filtration experiments are realized in a filter test rig. The results show that depending on the particle sizes, in some cases nearly 80% of the nanoparticles are scavenged by fly ash particles before they reach the bag house filter. For the filtration step dust cakes with a pressure drop of 500Pa or higher are found to be very effective in preventing nanoparticles from penetrating through the filter. Thus, regeneration of the filter must be undertaken with care in order to guarantee highly efficient collection of particles even in the lower nanometre size regime. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of intense scavenging on Pa-Th fractionation in the wake of Kerguelen Island (Southern Ocean)

International Nuclear Information System (INIS)

Venchiarutti, C.; Roy-Barman, M.; Freydier, R.; Van Beek, P.; Souhaut, M.; Jeandel, C.

2011-01-01

Dissolved and particulate excess 230 Th and 231 Pa concentrations (noted 230 Th xs and 231 Pa xs respectively) and 231 Pa xs / 230 Th xs activity ratios were investigated on and out of the Kerguelen plateau (Southern Ocean) in the framework of the Kerguelen Ocean and Plateau compared Study project in order to better understand the influence of particle flux and particle chemistry and advection on the scavenging of 231 Pa. In the wake of Kerguelen, particulate 231 Pa xs is relatively abundant compared to its content in the dissolved phase. This, together with the low fractionation observed between 230 Th and 231 Pa (F Th/Pa ranging from 0.06 ± 0.01 to 1.6 ± 0.2) reflects the domination of the biogenic silica in the particle pool. Along the eastern escarpment of the Kerguelen plateau, the strong 231 Pa xs horizontal gradient in the deep waters highlights the intense removal of 231 Pa at depth, as already observed for 230 Th xs . This local boundary scavenging was attributed to re-suspension of opal-rich particles by nepheloid layers, resulting in fractionation factors F Th/Pa ≤ 1 along the Kerguelen plateau slope. Therefore, both the composition (biogenic opal) and the flux (intense along the margin) of particles control the scavenging of the two radionuclides in the Kerguelen wake. The modelling of 231 Pa distribution with an advection-scavenging model demonstrates that lateral advection of open ocean water on the Kerguelen plateau could supply most of the 231 Pa, which is then efficiently scavenged on the highly productive plateau, as previously proposed for 230 Th xs . It stresses that lateral advection can play a significant role in the overall budget of particle reactive trace elements in a coastal-open ocean system. (authors)

Scavenger Receptors and Their Potential as Therapeutic Targets in the Treatment of Cardiovascular Disease

Directory of Open Access Journals (Sweden)

Sam L. Stephen

2010-01-01

Full Text Available Scavenger receptors act as membrane-bound and soluble proteins that bind to macromolecular complexes and pathogens. This diverse supergroup of proteins mediates binding to modified lipoprotein particles which regulate the initiation and progression of atherosclerotic plaques. In vascular tissues, scavenger receptors are implicated in regulating intracellular signaling, lipid accumulation, foam cell development, and cellular apoptosis or necrosis linked to the pathophysiology of atherosclerosis. One approach is using gene therapy to modulate scavenger receptor function in atherosclerosis. Ectopic expression of membrane-bound scavenger receptors using viral vectors can modify lipid profiles and reduce the incidence of atherosclerosis. Alternatively, expression of soluble scavenger receptors can also block plaque initiation and progression. Inhibition of scavenger receptor expression using a combined gene therapy and RNA interference strategy also holds promise for long-term therapy. Here we review our current understanding of the gene delivery by viral vectors to cells and tissues in gene therapy strategies and its application to the modulation of scavenger receptor function in atherosclerosis.

A first experiment on the scavenging of materials by rainfall using a large artificial climate experiment chamber at ACEF in IES

International Nuclear Information System (INIS)

Kawabata, Hitoshi; Hasegawa, Hidenao; Akata, Naofumi; Chikuchi, Yuki; Kondo, Kunio; Inaba, Jiro

2004-01-01

Radionuclides in the atmosphere are removed to rough surfaces on the earth through wet or dry removal. According to our past results, the wet deposition flux of sea-salt particles is larger than the dry deposition flux in Rokkasho, Aomori. Therefore, to clarify the mechanism of wet removal of aerosol particles, a laboratory experiment using a large artificial climate experiment chamber at the Artificial Climate Experiment Facility (ACEF) in the Institute for Environmental Sciences was started. We conducted a preliminary experiment on the scavenging of aerosol particles by raindrops. The scavenging coefficient for NaCl particles was larger than that for test powder (JIS Z 8901 No. 11 Kanto loam). The scavenging coefficients for NaCl particles and test powder increased exponentially with the increase of precipitation intensity. (author)

Multiple free-radical scavenging (MULTIS) capacity in cattle serum.

Science.gov (United States)

Sueishi, Yoshimi; Kamogawa, Erisa; Kimura, Anna; Kitahara, Go; Satoh, Hiroyuki; Asanuma, Taketoshi; Oowada, Shigeru

2017-01-01

Multiple free-radical scavenging (MULTIS) activity in cattle and human sera was evaluated with electron spin resonance spectroscopy. Scavenging rates against six active species, namely hydroxyl radical, superoxide anion, alkoxyl radical, alkylperoxyl radical, methyl radical, and singlet oxygen were quantified. The difference in the electron spin resonance signal intensity in the presence and absence of the serum was converted into the scavenging rates. Comparative MULTIS measurements were made in sera from eight beef cattle, three fetal calves and fifteen healthy human volunteers. Further, we determined the MULTIS value of albumin, the most abundant component in serum. MULTIS values in cattle sera indicated higher scavenging activity against most free radical species tested than human sera. In particular, cattle serum scavenging activities against superoxide and methyl radical were higher than human serum by 2.6 and 3.7 fold, respectively. In cattle serum, albumin appears to play a dominant role in MULTIS activity, but in human serum that is not the case. Previous data indicated that the abundance of uric acid in bovine blood is nearly 80% less than humans; however, this difference does not explain the deviation in MULTIS profile.

Asynchronous beating of cilia enhances particle capture rate

Science.gov (United States)

Ding, Yang; Kanso, Eva

2014-11-01

Many aquatic micro-organisms use beating cilia to generate feeding currents and capture particles in surrounding fluids. One of the capture strategies is to ``catch up'' with particles when a cilium is beating towards the overall flow direction (effective stroke) and intercept particles on the downstream side of the cilium. Here, we developed a 3D computational model of a cilia band with prescribed motion in a viscous fluid and calculated the trajectories of the particles with different sizes in the fluid. We found an optimal particle diameter that maximizes the capture rate. The flow field and particle motion indicate that the low capture rate of smaller particles is due to the laminar flow in the neighbor of the cilia, whereas larger particles have to move above the cilia tips to get advected downstream which decreases their capture rate. We then analyzed the effect of beating coordination between neighboring cilia on the capture rate. Interestingly, we found that asynchrony of the beating of the cilia can enhance the relative motion between a cilium and the particles near it and hence increase the capture rate.

Influence of intense scavenging on Pa-Th fractionation in the wake of Kerguelen Island (Southern Ocean

Directory of Open Access Journals (Sweden)

C. Venchiarutti

2011-11-01

Full Text Available Dissolved and particulate excess ²³⁰Th and ²³¹Pa concentrations (noted ²³⁰Th_xs and ²³¹Pa_xs respectively and ²³¹Pa_xs/²³⁰Th_xs activity ratios were investigated on and out of the Kerguelen plateau (Southern Ocean in the framework of the Kerguelen Ocean and Plateau compared Study project in order to better understand the influence of particle flux and particle chemistry and advection on the scavenging of ²³¹Pa.

In the wake of Kerguelen, particulate ²³¹Pa_xs is relatively abundant compared to its content in the dissolved phase. This, together with the low fractionation observed between ²³⁰Th and ²³¹Pa (F_Th/Pa ranging from 0.06 ± 0.01 to 1.6 ± 0.2 reflects the domination of the biogenic silica in the particle pool.

Along the eastern escarpment of the Kerguelen plateau, the strong ²³¹Pa_xs horizontal gradient in the deep waters highlights the intense removal of ²³¹Pa at depth, as already observed for ²³⁰Th_xs. This local boundary scavenging was attributed to re-suspension of opal-rich particles by nepheloid layers, resulting in fractionation factors F_Th/Pa ≤ 1 along the Kerguelen plateau slope. Therefore, both the composition (biogenic opal and the flux (intense along the margin of particles control the scavenging of the two radionuclides in the Kerguelen wake.

The modelling of ²³¹Pa distribution with an advection-scavenging model demonstrates that lateral advection of open ocean water on the Kerguelen plateau could supply most of the ²³¹Pa, which is then efficiently scavenged on the highly productive plateau, as previously proposed for ²³⁰Th_xs. It stresses that lateral advection can play a significant role in the overall

Blood Glutamate Scavenging: Insight into Neuroprotection

Directory of Open Access Journals (Sweden)

Alexander Zlotnik

2012-08-01

Full Text Available Brain insults are characterized by a multitude of complex processes, of which glutamate release plays a major role. Deleterious excess of glutamate in the brain’s extracellular fluids stimulates glutamate receptors, which in turn lead to cell swelling, apoptosis, and neuronal death. These exacerbate neurological outcome. Approaches aimed at antagonizing the astrocytic and glial glutamate receptors have failed to demonstrate clinical benefit. Alternatively, eliminating excess glutamate from brain interstitial fluids by making use of the naturally occurring brain-to-blood glutamate efflux has been shown to be effective in various animal studies. This is facilitated by gradient driven transport across brain capillary endothelial glutamate transporters. Blood glutamate scavengers enhance this naturally occurring mechanism by reducing the blood glutamate concentration, thus increasing the rate at which excess glutamate is cleared. Blood glutamate scavenging is achieved by several mechanisms including: catalyzation of the enzymatic process involved in glutamate metabolism, redistribution of glutamate into tissue, and acute stress response. Regardless of the mechanism involved, decreased blood glutamate concentration is associated with improved neurological outcome. This review focuses on the physiological, mechanistic and clinical roles of blood glutamate scavenging, particularly in the context of acute and chronic CNS injury. We discuss the details of brain-to-blood glutamate efflux, auto-regulation mechanisms of blood glutamate, natural and exogenous blood glutamate scavenging systems, and redistribution of glutamate. We then propose different applied methodologies to reduce blood and brain glutamate concentrations and discuss the neuroprotective role of blood glutamate scavenging.

Carcass Type Affects Local Scavenger Guilds More than Habitat Connectivity.

Science.gov (United States)

Olson, Zachary H; Beasley, James C; Rhodes, Olin E

2016-01-01

Scavengers and decomposers provide an important ecosystem service by removing carrion from the environment. Scavenging and decomposition are known to be temperature-dependent, but less is known about other factors that might affect carrion removal. We conducted an experiment in which we manipulated combinations of patch connectivity and carcass type, and measured responses by local scavenger guilds along with aspects of carcass depletion. We conducted twelve, 1-month trials in which five raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), and domestic rabbit (Oryctolagus spp.) carcasses (180 trials total) were monitored using remote cameras in 21 forest patches in north-central Indiana, USA. Of 143 trials with complete data, we identified fifteen species of vertebrate scavengers divided evenly among mammalian (N = 8) and avian species (N = 7). Fourteen carcasses (9.8%) were completely consumed by invertebrates, vertebrates exhibited scavenging behavior at 125 carcasses (87.4%), and four carcasses (2.8%) remained unexploited. Among vertebrates, mammals scavenged 106 carcasses, birds scavenged 88 carcasses, and mammals and birds scavenged 69 carcasses. Contrary to our expectations, carcass type affected the assemblage of local scavenger guilds more than patch connectivity. However, neither carcass type nor connectivity explained variation in temporal measures of carcass removal. Interestingly, increasing richness of local vertebrate scavenger guilds contributed moderately to rates of carrion removal (≈6% per species increase in richness). We conclude that scavenger-specific differences in carrion utilization exist among carcass types and that reliable delivery of carrion removal as an ecosystem service may depend on robust vertebrate and invertebrate communities acting synergistically.

Carcass Type Affects Local Scavenger Guilds More than Habitat Connectivity.

Directory of Open Access Journals (Sweden)

Zachary H Olson

Full Text Available Scavengers and decomposers provide an important ecosystem service by removing carrion from the environment. Scavenging and decomposition are known to be temperature-dependent, but less is known about other factors that might affect carrion removal. We conducted an experiment in which we manipulated combinations of patch connectivity and carcass type, and measured responses by local scavenger guilds along with aspects of carcass depletion. We conducted twelve, 1-month trials in which five raccoon (Procyon lotor, Virginia opossum (Didelphis virginiana, and domestic rabbit (Oryctolagus spp. carcasses (180 trials total were monitored using remote cameras in 21 forest patches in north-central Indiana, USA. Of 143 trials with complete data, we identified fifteen species of vertebrate scavengers divided evenly among mammalian (N = 8 and avian species (N = 7. Fourteen carcasses (9.8% were completely consumed by invertebrates, vertebrates exhibited scavenging behavior at 125 carcasses (87.4%, and four carcasses (2.8% remained unexploited. Among vertebrates, mammals scavenged 106 carcasses, birds scavenged 88 carcasses, and mammals and birds scavenged 69 carcasses. Contrary to our expectations, carcass type affected the assemblage of local scavenger guilds more than patch connectivity. However, neither carcass type nor connectivity explained variation in temporal measures of carcass removal. Interestingly, increasing richness of local vertebrate scavenger guilds contributed moderately to rates of carrion removal (≈6% per species increase in richness. We conclude that scavenger-specific differences in carrion utilization exist among carcass types and that reliable delivery of carrion removal as an ecosystem service may depend on robust vertebrate and invertebrate communities acting synergistically.

Carcass Type Affects Local Scavenger Guilds More than Habitat Connectivity

Science.gov (United States)

Olson, Zachary H.; Beasley, James C.; Rhodes, Olin E.

2016-01-01

Scavengers and decomposers provide an important ecosystem service by removing carrion from the environment. Scavenging and decomposition are known to be temperature-dependent, but less is known about other factors that might affect carrion removal. We conducted an experiment in which we manipulated combinations of patch connectivity and carcass type, and measured responses by local scavenger guilds along with aspects of carcass depletion. We conducted twelve, 1-month trials in which five raccoon (Procyon lotor), Virginia opossum (Didelphis virginiana), and domestic rabbit (Oryctolagus spp.) carcasses (180 trials total) were monitored using remote cameras in 21 forest patches in north-central Indiana, USA. Of 143 trials with complete data, we identified fifteen species of vertebrate scavengers divided evenly among mammalian (N = 8) and avian species (N = 7). Fourteen carcasses (9.8%) were completely consumed by invertebrates, vertebrates exhibited scavenging behavior at 125 carcasses (87.4%), and four carcasses (2.8%) remained unexploited. Among vertebrates, mammals scavenged 106 carcasses, birds scavenged 88 carcasses, and mammals and birds scavenged 69 carcasses. Contrary to our expectations, carcass type affected the assemblage of local scavenger guilds more than patch connectivity. However, neither carcass type nor connectivity explained variation in temporal measures of carcass removal. Interestingly, increasing richness of local vertebrate scavenger guilds contributed moderately to rates of carrion removal (≈6% per species increase in richness). We conclude that scavenger-specific differences in carrion utilization exist among carcass types and that reliable delivery of carrion removal as an ecosystem service may depend on robust vertebrate and invertebrate communities acting synergistically. PMID:26886299

Peroxynitrite scavenging by flavonids.

NARCIS (Netherlands)

Haenen, G.R.M.M.; Paquay, J.B.G.; Korthouwer, R.E.M.; Bast, A.

1997-01-01

The peroxynitrite scavenging activity of a series of structurally related flavonoids was tested. It was found that flavonoids are excellent scavengers of peroxynitrite. Compared to the known peroxynitrite scavenger ebselen, the most active flavonoids proved to be 10 times more effective. Indications

Spatial complexity of carcass location influences vertebrate scavenger efficiency and species composition.

Science.gov (United States)

Smith, Joshua B; Laatsch, Lauren J; Beasley, James C

2017-08-31

Scavenging plays an important role in shaping communities through inter- and intra-specific interactions. Although vertebrate scavenger efficiency and species composition is likely influenced by the spatial complexity of environments, heterogeneity in carrion distribution has largely been disregarded in scavenging studies. We tested this hypothesis by experimentally placing juvenile bird carcasses on the ground and in nests in trees to simulate scenarios of nestling bird carrion availability. We used cameras to record scavengers removing carcasses and elapsed time to removal. Carrion placed on the ground was scavenged by a greater diversity of vertebrates and at > 2 times the rate of arboreal carcasses, suggesting arboreal carrion may represent an important resource to invertebrate scavengers, particularly in landscapes with efficient vertebrate scavenging communities. Nonetheless, six vertebrate species scavenged arboreal carcasses. Rat snakes (Elaphe obsolete), which exclusively scavenged from trees, and turkey vultures (Cathartes aura) were the primary scavengers of arboreal carrion, suggesting such resources are potentially an important pathway of nutrient acquisition for some volant and scansorial vertebrates. Our results highlight the intricacy of carrion-derived food web linkages, and how consideration of spatial complexity in carcass distribution (i.e., arboreal) may reveal important pathways of nutrient acquisition by invertebrate and vertebrate scavenging guilds.

Settling rates of plutonium-bearing particles in Pond B

International Nuclear Information System (INIS)

Orlandini, K.A.; Bowling, J.W.; Pinder, J.E. III

1986-01-01

Research is being conducted in Pond B to determine the relative importances of (1) changes in particles settling rates, (2) changes in remobilization rates, and (3) the influence of the macrophytes on the annual cycle in /sup 239,240/Pu inventories. The initial research has emphasized (1) an evaluation of the importance of particle adherence to macrophytes in reducing Pu inventories in the water column and (2) measurements of particle settling rates at different times of the year. This report describes the research on measurements of particle settling rates. 3 figures, 1 table

Influence of various scavengers of •OH radicals on the radiation sensitivity of yeast and bacteria.

Science.gov (United States)

Múčka, Viliam; Bláha, Pavel; Čuba, Václav; Červenák, Jaroslav

2013-12-01

To quantitatively investigate the influence of various •OH (hydroxyl radical) scavengers on the radiation sensitivity of yeast and bacteria, particularly to define the relationship between the protective effect of a scavenger and its •OH scavenging efficiency. In order to study the protective effect of •OH scavengers we used various concentrations of four scavengers (methanol, potassium formate, ethanol and ascorbic acid) in isotonic salt solutions. These solutions containing live yeast (Saccharomyces cerevisiae) or bacteria (Escherichia coli) were irradiated with (60)Co isotope γ -radiation using two different doses and dose rates. The number of surviving cells was determined prior to and after irradiation both in suspension with and without scavengers. The surviving fractions after irradiation with and without the scavenger were evaluated. The main results of the paper were: The surviving fraction increased approximately linearly within the measured interval with increasing concentration of the scavenger. The same dependences were found for the protecting effect depending on the scavenging efficiency. The slopes of these dependences (k) were found to be characteristic for each scavenger. The k value determined the degree in which the scavenging of •OH radicals participated in the protection of living cells. The protective effects of scavengers at the same scavenging efficiency were different and unique for each scavenger. No simple relation was found between the efficiency of scavenger k and the rate constant kOH of the reactions between scavengers and •OH radicals. Our results suggest that the studied scavengers effectively protected yeast and bacteria against ionizing radiation. Although the scavenging of •OH radicals seems to be important for protection of living cells, it is clearly not the only process on which the protection is based.

Identification and quantification of particle growth channels during new particle formation

Directory of Open Access Journals (Sweden)

M. R. Pennington

2013-10-01

Full Text Available Atmospheric new particle formation (NPF is a key source of ambient ultrafine particles that may contribute substantially to the global production of cloud condensation nuclei (CCN. While NPF is driven by atmospheric nucleation, its impact on CCN concentration depends strongly on atmospheric growth mechanisms since the growth rate must exceed the loss rate due to scavenging in order for the particles to reach the CCN size range. In this work, chemical composition measurements of 20 nm diameter particles during NPF in Hyytiälä, Finland, in March–April 2011 permit identification and quantitative assessment of important growth channels. In this work we show the following: (A sulfuric acid, a key species associated with atmospheric nucleation, accounts for less than half of particle mass growth during this time period; (B the sulfate content of a growing particle during NPF is quantitatively explained by condensation of gas-phase sulfuric acid molecules (i.e., sulfuric acid uptake is collision-limited; (C sulfuric acid condensation substantially impacts the chemical composition of preexisting nanoparticles before new particles have grown to a size sufficient to be measured; (D ammonium and sulfate concentrations are highly correlated, indicating that ammonia uptake is driven by sulfuric acid uptake; (E sulfate neutralization by ammonium does not reach the predicted thermodynamic end point, suggesting that a barrier exists for ammonia uptake; (F carbonaceous matter accounts for more than half of the particle mass growth, and its oxygen-to-carbon ratio (~ 0.5 is characteristic of freshly formed secondary organic aerosol; and (G differences in the overall growth rate from one formation event to another are caused by variations in the growth rates of all major chemical species, not just one individual species.

A method for nitric oxide radical scavenging properties of sulfur containing compounds.

NARCIS (Netherlands)

Vriesman, M.F.; Haenen, G.R.M.M.; Westerveld, G.J.; Paquay, J.B.G.; Voss, H.P.; Bast, A.

1997-01-01

A new method for the quantification of the nitric oxide (NO) scavenging activity of compounds in aqueous solutions is described using an amperometric NO sensor. After correction for the spontaneous degradation of NO, second-order rate kinetics of the scavenging reaction are observed.

The use of 234Th/238U disequilibrium to examine the fate of particle-reactive species on the Yangtze continental shelf

International Nuclear Information System (INIS)

McKee, B.A.; DeMaster, D.J.; Nittrouer, C.A.

1984-01-01

Measurements of 234 Th (tsub(1/2)=24.1 d) in water column and seabed samples from an area near the mouth of the Yangtze River (People's Republic of China) provide the following information: Most of the 234 Th in waters near the mouth of the Yangtze River is in particulate form, and horizontal transport and sedimentation of 234 Th-bearing particles dominate the 234 Th budget in this area. A model incorporating processes in at least two dimensions is required to understand the fate of particle-reactive species on the Yangtze continental shelf. The residence times of particle-reactive species (with respect to scavenging) range from 0.3 days (nearshore) to 4.0 days (offshore). The residence times (with respect to removal to the seabed) range from 0.5 day (nearshore) to 11.0 days (offshore). Scavenging residence times for 234 Th decrease as the concentration of suspended particles increases. The time for removal of 234 Th to the seabed increases with distance from shore (a variable which integrates such factors as scavenging rate, bathymetry, and frequency of resuspension). (orig.)

Organobasierter Sauerstoff-Scavenger/-Indikator

OpenAIRE

Langowski, H.C.; Wanner, T.

2007-01-01

WO 2007059901 A1 UPAB: 20070911 NOVELTY - Oxygen scavenger/indicator which contains at least one substance having combined scavenging and indicating functions for oxygen which is capable of absorbing oxygen under the effect of moisture in alkaline conditions, and at least one alkaline compound. The indicator effect is caused by a change in at least one physical property of the substance having combined scavenging and indicating function for oxygen, the change being initiated by the presence o...

Forensically significant scavenging guilds in the southwest of Western Australia.

Science.gov (United States)

O'Brien, R Christopher; Forbes, Shari L; Meyer, Jan; Dadour, Ian

2010-05-20

Estimation of time since death is an important factor in forensic investigations and the state of decomposition of a body is a prime basis for such estimations. The rate of decomposition is, however, affected by many environmental factors such as temperature, rainfall, and solar radiation as well as by indoor or outdoor location, covering and the type of surface the body is resting upon. Scavenging has the potential for major impact upon the rate of decomposition of a body, but there is little direct research upon its effect. The information that is available relates almost exclusively to North American and European contexts. The Australian faunal assemblage is unique in that it includes no native large predators or large detrivorous avians. This research investigates the animals that scavenge carcasses in natural outdoor settings in southern Western Australia and the factors which can affect each scavenger's activity. The research was conducted at four locations around Perth, Western Australia with different environmental conditions. Pig carcasses, acting as models for the human body, were positioned in an outdoor environment with no protection from scavengers or other environmental conditions. Twenty-four hour continuous time-lapse video capture was used to observe the pattern of visits of all animals to the carcasses. The time of day, length of feeding, material fed upon, area of feeding, and any movement of the carcass were recorded for each feeding event. Some species were observed to scavenge almost continually throughout the day and night. Insectivores visited the carcasses mostly during bloat and putrefaction; omnivores fed during all stages of decomposition and scavenging by carnivores, rare at any time, was most likely to occur during the early stages of decomposition. Avian species, which were the most prolific visitors to the carcasses in all locations, like reptiles, fed only during daylight hours. Only mammals and amphibians, which were seldom seen

Turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Meyer, Knud Erik; Walther, Jens Honore

2014-01-01

turbulence models. In the present work, the flow in a dynamic scale model of a uniflowscavenged cylinder is investigated experimentally. The model has a transparent cylinder and a moving piston driven by a linear motor. The flow is investigated using phase-locked stereoscopic particle image velocimetry (PIV...... cannot be assumed to be quasi-steady. The temporal development of the swirl strength is investigated by computing the angular momentum. The swirl strength shows an exponential decay from scavenge port closing to scavenge port opening corresponding to a reduction of 34 %, which is in good agreement...

Some approximations for the wet and dry removal of particles and gases from the atmosphere

Science.gov (United States)

W. G. N. Slinn

1976-01-01

Semi-empirical formulae are presented which can be used to estimate precipitation scavenging and dry deposition of particles and gases. The precipitation scavenging formulae are appropriate both for in- and below-cloud scavenging and comparisons with data indicate the importance of accounting for aerosol particle growth by water vapor condensation and attachment of the...

Morphological Evolution of Block Copolymer Particles: Effect of Solvent Evaporation Rate on Particle Shape and Morphology.

Science.gov (United States)

Shin, Jae Man; Kim, YongJoo; Yun, Hongseok; Yi, Gi-Ra; Kim, Bumjoon J

2017-02-28

Shape and morphology of polymeric particles are of great importance in controlling their optical properties or self-assembly into unusual superstructures. Confinement of block copolymers (BCPs) in evaporative emulsions affords particles with diverse structures, including prolate ellipsoids, onion-like spheres, oblate ellipsoids, and others. Herein, we report that the evaporation rate of solvent from emulsions encapsulating symmetric polystyrene-b-polybutadiene (PS-b-PB) determines the shape and internal nanostructure of micron-sized BCP particles. A distinct morphological transition from the ellipsoids with striped lamellae to the onion-like spheres was observed with decreasing evaporation rate. Experiments and dissipative particle dynamics (DPD) simulations showed that the evaporation rate affected the organization of BCPs at the particle surface, which determined the final shape and internal nanostructure of the particles. Differences in the solvent diffusion rates in PS and PB at rapid evaporation rates induced alignment of both domains perpendicular to the particle surface, resulting in ellipsoids with axial lamellar stripes. Slower evaporation rates provided sufficient time for BCP organization into onion-like structures with PB as the outermost layer, owing to the preferential interaction of PB with the surroundings. BCP molecular weight was found to influence the critical evaporation rate corresponding to the morphological transition from ellipsoid to onion-like particles, as well as the ellipsoid aspect ratio. DPD simulations produced morphologies similar to those obtained from experiments and thus elucidated the mechanism and driving forces responsible for the evaporation-induced assembly of BCPs into particles with well-defined shapes and morphologies.

Botanical Scavenger Hunt

Science.gov (United States)

Walker-Livingston, Wendy

2009-01-01

Why not combine the use of technology with the excitement of a scavenger hunt that moves middle-level students out into the "wilds" of their school campus to classify plants? In the lesson plan described here, students embark on a botanical scavenger hunt and then document their findings using a digital camera. This project was designed to allow…

Scavenger removal: Bird and bat carcass persistence in a tropical wind farm

Science.gov (United States)

Villegas-Patraca, Rafael; Macías-Sánchez, Samuel; MacGregor-Fors, Ian; Muñoz-Robles, Carlos

2012-08-01

Energy produced by wind farms has diverse positive environmental effects, but can also be related to negative impacts, including wildlife mortality through collisions with wind turbines. Bird and bat mortality caused by collisions with wind turbines can be estimated indirectly by counting carcasses within wind farms. However, carcass removal by scavengers often biases such measurements. In this study, we identified the main scavengers removing bird and bat carcasses in a tropical wind farm. A known fate analysis was done to assess the effect of carcass type (i.e., small bird, large bird, bat), vegetation type (i.e., secondary vegetation, croplands) and season (dry and rainy seasons of 2009) on carcass persistence rates. We identified three main scavenger groups, with mammals being the most abundant group. Our results show high rates of carcass removal relative to previous studies, especially for bats; there were fewer remaining carcasses after 20 days in our tropical site than in non-tropical environments reported elsewhere. We found a higher carcass persistence rate during the rainy season than in the dry season, possibly due to a greater abundance of food resources for scavenger organisms in the rainy season. Although we found some evidence for higher persistence rates for large bird carcasses than for small bird and bat carcasses during the rainy season, overall carcass type was not a strong predictor of persistence rates. Similarly, we did not find a strong effect of vegetation type on carcass persistence rates. Results suggest that in order to estimate accurate bird and bat mortality in tropical wind farm areas, seasonality should be incorporated to correction factors of carcass removal rates.

Peroxynitrite scavenging activity of herb extracts.

Science.gov (United States)

Choi, Hye Rhi; Choi, Jae Sue; Han, Yong Nam; Bae, Song Ja; Chung, Hae Young

2002-06-01

Peroxynitrite (ONOO(-)) is a cytotoxicant with strong oxidizing properties toward various cellular constituents, including sulphydryls, lipids, amino acids and nucleotides and can cause cell death, lipid peroxidation, carcinogenesis and aging. The aim of this study was to characterize ONOO(-) scavenging constituents from herbs. Twenty-eight herbs were screened for their ONOO(-) scavenging activities with the use of a fluorometric method. The potency of scavenging activity following the addition of authentic ONOO(-) was in the following order: witch hazel bark > rosemary > jasmine tea > sage > slippery elm > black walnut leaf > Queen Anne's lace > Linden flower. The extracts exhibited dose-dependent ONOO(-) scavenging activities. We found that witch hazel (Hamamelis virginiana L.) bark showed the strongest effect for scavenging ONOO(-) of the 28 herbs. Hamamelitannin, the major active component of witch hazel bark, was shown to have a strong ability to scavenge ONOO(-). It is suggested that hamamelitannin might be developed as an effective peroxynitrite scavenger for the prevention of ONOO(-) involved diseases. Copyright 2002 John Wiley & Sons, Ltd.

Cloud Scavenging Effects on Aerosol Radiative and Cloud-nucleating Properties - Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Ogren, John A.; Sheridan, Patrick S.; Andrews, Elisabeth

2009-03-05

The optical properties of aerosol particles are the controlling factors in determining direct aerosol radiative forcing. These optical properties depend on the chemical composition and size distribution of the aerosol particles, which can change due to various processes during the particles’ lifetime in the atmosphere. Over the course of this project we have studied how cloud processing of atmospheric aerosol changes the aerosol optical properties. A counterflow virtual impactor was used to separate cloud drops from interstitial aerosol and parallel aerosol systems were used to measure the optical properties of the interstitial and cloud-scavenged aerosol. Specifically, aerosol light scattering, back-scattering and absorption were measured and used to derive radiatively significant parameters such as aerosol single scattering albedo and backscatter fraction for cloud-scavenged and interstitial aerosol. This data allows us to demonstrate that the radiative properties of cloud-processed aerosol can be quite different than pre-cloud aerosol. These differences can be used to improve the parameterization of aerosol forcing in climate models.

Variation in bird-window collision mortality and scavenging rates within an urban landscape

Science.gov (United States)

Annual avian mortality from collisions with windows and buildings is estimated to range from a million to a billion birds in the United States alone. However, estimates of mortality based on carcass counts suffer from bias due to imperfect detection and carcass scavenging. We stu...

Particle loading rates for HVAC filters, heat exchangers, and ducts.

Science.gov (United States)

Waring, M S; Siegel, J A

2008-06-01

The rate at which airborne particulate matter deposits onto heating, ventilation, and air-conditioning (HVAC) components is important from both indoor air quality (IAQ) and energy perspectives. This modeling study predicts size-resolved particle mass loading rates for residential and commercial filters, heat exchangers (i.e. coils), and supply and return ducts. A parametric analysis evaluated the impact of different outdoor particle distributions, indoor emission sources, HVAC airflows, filtration efficiencies, coils, and duct system complexities. The median predicted residential and commercial loading rates were 2.97 and 130 g/m(2) month for the filter loading rates, 0.756 and 4.35 g/m(2) month for the coil loading rates, 0.0051 and 1.00 g/month for the supply duct loading rates, and 0.262 g/month for the commercial return duct loading rates. Loading rates are more dependent on outdoor particle distributions, indoor sources, HVAC operation strategy, and filtration than other considered parameters. The results presented herein, once validated, can be used to estimate filter changing and coil cleaning schedules, energy implications of filter and coil loading, and IAQ impacts associated with deposited particles. The results in this paper suggest important factors that lead to particle deposition on HVAC components in residential and commercial buildings. This knowledge informs the development and comparison of control strategies to limit particle deposition. The predicted mass loading rates allow for the assessment of pressure drop and indoor air quality consequences that result from particle mass loading onto HVAC system components.

Increasing land-use intensity reverses the relative occupancy of two quadrupedal scavengers.

Directory of Open Access Journals (Sweden)

Joshua P Twining

Full Text Available Human land use is continuously altering the natural environment, yet the greater ecological implications of this change for many groups that are key to healthy ecosystem functioning remains uncharacterised in the tropics. Terrestrial scavenging vertebrates are one such group, providing integral ecosystem services through the removal of carrion which is a crucial component of both nutrient cycling and disease dynamics. To explore how anthropogenic processes may affect forest scavengers, we investigated the changes in the relative occupancy of two important terrestrial scavengers along a gradient of land use intensity, ranging from protected forest to oil palm plantation in Borneo. We found the Malay civet (Viverra tangalunga had highest, albeit variable, occupancy in areas of low land use intensity and the Southeast Asian water monitor (Varanus salvator macromaculatus had highest occupancy in areas of high land use intensity. Land use had no effect on the combined occupancy of the two species. In high land use intensity sites, individual water monitors were larger and had better body condition, but at population level had a highly biased sex ratio with more males than females and increased signs of intraspecific conflict. We did not assess scavenging rate or efficiency as a process, but the high occupancy rates and apparent health of the scavengers in high land use intensity landscapes suggests this ecological process is robust to land use change.

Beta particle dose rates to micro-organisms in soil

International Nuclear Information System (INIS)

Kabir, M.; Spiers, F.W.; Iinuma, Takeshi.

1977-01-01

Studies were made to estimate the beta-particle dose rates to micro-organisms of various sizes in soil. The small insects and organisms living in soil are constantly exposed to beta-radiation arising from naturally occuring radionuclides in soil as in this case no overlying tissue shields them. The technique of measuring beta-particle dose rate consisted of using of a thin plastic scintillator to measure the pulse height distribution as the beta particle traverses the scintillator. The integrated response was determined by the number and size of the photomultiplier pulses. From the data of soil analyses it was estimated that typically about 29% of the beta particles emitted per gm. of soil were contributed by the U/Ra series, 21% by the Th series and about 50% by potassium. By combining the individual spectra of these three radionuclides in the proportion found in a typical soil, a resultant spectrum was computed representing the energy distribution of the beta particles. The dose rate received by micro-organisms of different shape and size in soil was derived from the equilibrium dose rates combined with a 'Geometrical Factor' of the organisms. For small organisms, the dose rates did not vary between the spherical and cylindrical types, but in the case of larger organisms, the dose rates were found to be greater for the spherical types of the same diameter. (auth.)

Enhanced protection of PDMS-embedded palladium catalysts by co-embedding of sulphide-scavengers.

Science.gov (United States)

Comandella, Daniele; Ahn, Min Hyung; Kim, Hojeong; Mackenzie, Katrin

2017-12-01

For Pd-containing hydrodechlorination catalysts, coating with poly(dimethyl siloxane) (PDMS) was proposed earlier as promising protection scheme against poisoning. The PDMS coating can effectively repel non-permeating poisons (such as SO 3 2- ) retaining the hydrodechlorination Pd activity. In the present study, the previously achieved protection efficiency was enhanced by incorporation of sulphide scavengers into the polymer. The embedded scavengers were able to bind permeating non-ionic poisons (such as H 2 S) during their passage through PDMS prior to Pd contact which ensured an extended catalyst lifetime. Three scavenger types forming non-permeable sulphur species from H 2 S - alkaline, oxidative or iron-based compounds - were either incorporated into single-layer coats around individual Pd/Al 2 O 3 particles or into a second layer above Pd-containing PDMS films (Pd-PDMS). Hydrodechlorination and hydrogenation were chosen as model reactions, carried out in batch and continuous-flow reactors. Batch tests with all scavenger-containing catalysts showed extended Pd protection compared to scavenger-free catalysts. Solid alkaline compounds (Ca(OH) 2 , NaOH, CaO) and MnO 2 showed the highest instantaneous scavenger efficiencies (retained Pd activity=30-60%), while iron-based catalysts, such as nano zero-valent iron (nZVI) or ferrocene (FeCp 2 ), proved less efficient (1-10%). When stepwise poisoning was applied, the protection efficiency of iron-based and oxidizing compounds was higher in the long term than that of alkaline solids. Long-term experiments in mixed-flow reactors were performed with selected scavengers, revealing the following trend of protection efficiency: CaO 2 >Ca(OH) 2 >FeCp 2 . Under field-simulating conditions using a fixed-bed reactor, the combination of sulphide pre-oxidation in the water phase by H 2 O 2 and local scavenger-enhanced Pd protection was successful. The oxidizing agent H 2 O 2 does not disturb the Pd-catalysed reduction, while the

The behavior of scavenged isotopes in marine anoxic environments: 210Pb and 210Po in the water column of the Black Sea

International Nuclear Information System (INIS)

Wei, C.L.; Murray, J.W.

1994-01-01

Vertical profiles of dissolved and particulate 210 Pb and 210 Po were determined at two stations in the Black Sea in June 1988. Vertical fluxes of 210 Pb and 210 Po were also measured in the upper 150 m, using floating sediment traps. The fractionation of 210 Pb between dissolved and particulate phases in the Black Sea is strongly influenced by the redox conditions in the water column. Dissolved 210 Pb dominates in the oxic zone, while particulate 210 Pb is the major form in the deep sulfide-rich anoxic zone. The distribution of 210 Pb across the suboxic zone appears to be mainly controlled by redox cycling of manganese and iron. In the sulfide-rich layer coprecipitation of lead with iron sulfide is probably the dominant scavenging mechanism. A simple scavenging model was used to calculate the residence times of dissolved and particulate 210 Pb in the oxic, suboxic, and anoxic zones. The residence times of dissolved 210 Pb relative to scavenging by particles are 0.5-1, 2-3, and 3.5 years in the oxic, suboxic, and anoxic layers, respectively. The corresponding residence times of particulate 210 Pb relative to particle removal processes in the same layers are 0.1, 1.5-2.5, and 8.5 years, respectively. A particle settling velocity of about 40 m y -1 was derived from the 210 Pb/ 226 Ra disequilibrium in the deep Black Sea. The relatively short residence times of 210 Pb support the hypothesis that anoxic basins are important sites for boundary scavenging of 210 Pb. The 210 Po profiles indicate that biological rather than inorganic particles are the major carrier phases for Po in the Black sea. Based on the magnitude of distribution coefficients, the relative partitioning of Pb, Po, and Th to particles found in the oxic and anoxic layers of the Black Sea are Po > Th > Pb and Po = Pb > Th, respectively. Colloidal phases may be important for the scavenging of these radionuclides

The LOX-1 Scavenger Receptor and Its Implications in the Treatment of Vascular Disease

Directory of Open Access Journals (Sweden)

M. W Twigg

2012-01-01

Full Text Available Cardiovascular disease is the leading cause of death. The disease is due to atherosclerosis which is characterized by lipid and fat accumulation in arterial blood vessel walls. A key causative event is the accumulation of oxidised low density lipoprotein particles within vascular cells, and this is mediated by scavenger receptors. One such molecule is the LOX-1 scavenger receptor that is expressed on endothelial, vascular smooth muscle, and lymphoid cells including macrophages. LOX-1 interaction with OxLDL particles stimulates atherosclerosis. LOX-1 mediates OxLDL endocytosis via a clathrin-independent internalization pathway. Transgenic animal model studies show that LOX-1 plays a significant role in atherosclerotic plaque initiation and progression. Administration of LOX-1 antibodies in cellular and animal models suggest that such intervention inhibits atherosclerosis. Antiatherogenic strategies that target LOX-1 function using gene therapy or small molecule inhibitors would be new ways to address the increasing incidence of vascular disease in many countries.

Deer carcass decomposition and potential scavenger exposure to chronic wasting disease

Science.gov (United States)

Jennelle, C.S.; Samuel, M.D.; Nolden, C.A.; Berkley, E.A.

2009-01-01

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy afflicting the Cervidae family in North America, causing neurodegeneration and ultimately death. Although there are no reports of natural cross-species transmission of CWD to noncervids, infected deer carcasses pose a potential risk of CWD exposure for other animals. We placed 40 disease-free white-tailed deer (Odocoileus virginianus) carcasses and 10 gut piles in the CWD-affected area of Wisconsin (USA) from September to April in 2003 through 2005. We used photos from remotely operated cameras to characterize scavenger visitation and relative activity. To evaluate factors driving the rate of carcass removal (decomposition), we used KaplanMeier survival analysis and a generalized linear mixed model. We recorded 14 species of scavenging mammals (6 visiting species) and 14 species of scavenging birds (8 visiting species). Prominent scavengers included American crows (Corvus brachyrhynchos), raccoons (Procyon lotor), and Virginia opossums (Didelphis virginiana). We found no evidence that deer consumed conspecific remains, although they visited gut piles more often than carcasses relative to temporal availability in the environment. Domestic dogs, cats, and cows either scavenged or visited carcass sites, which could lead to human exposure to CWD. Deer carcasses persisted for 18 days to 101 days depending on the season and year, whereas gut piles lasted for 3 days. Habitat did not influence carcass decomposition, but mammalian and avian scavenger activity and higher temperatures were positively associated with faster removal. Infected deer carcasses or gut piles can serve as potential sources of CWD prions to a variety of scavengers. In areas where surveillance for CWD exposure is practical, management agencies should consider strategies for testing primary scavengers of deer carcass material.

Postmortem scavenging by the Virginia opossum (Didelphis virginiana): Impact on taphonomic assemblages and progression.

Science.gov (United States)

King, Kama A; Lord, Wayne D; Ketchum, Heather R; O'Brien, R Christopher

2016-09-01

The Virginia opossum (Didelphis virginiana) is a highly active scavenger whose behavior has significant impacts on rates of decomposition and skeletonization, which have previously not been addressed. In this study, scavenging by the opossum led to the skeletonization of carcasses in half of the accumulated degree days (ADD) of a comparable non-scavenged control carcass. Opossums used body orifices, as well as natural tears caused by the decomposition process, to access internal tissues and consume them. This activity resulted in little movement of the carcass and the retained appearance of natural undisturbed decomposition. This concealed activity has the potential to cause drastically incorrect estimates of time since deposition and post-mortem interval. Scavenging by opossums was also found to leave distinct tooth mark and other defects on bone, which have not been previously distinguished in the literature. This research suggests, beyond effects on PMI, that scavenging by opossums has been historically overlooked and misattributed to canid scavengers. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

21 CFR 868.5590 - Scavenging mask.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Scavenging mask. 868.5590 Section 868.5590 Food... DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5590 Scavenging mask. (a) Identification. A scavenging mask is a device positioned over a patient's nose to deliver anesthetic or analgesic gases to the...

Precipitation scavenging of tritiated water vapour (HTO)

International Nuclear Information System (INIS)

Ogram, G.L.

1985-10-01

Precipitation scavenging (or washout) is an important mechanism for the removal of HTO from the atmosphere. Methods of parameterizing the depletion of a plume of HTO released to the atmosphere are examined. Simple approaches, commonly used for atmospheric transport modelling purposes, such as the use of a constant washout coefficient or washout ratio, or the use of parameters based on equilibrium assumptions, are often not justified. It is shown that these parameters depend strongly on ambient temperature and plume dimensions, as well as rainfall rate. An approximate expression for washout ratio, as a function of these variables, is developed, and it is shown that near equilibrium washout conditions are only expected to hold at long plume travel distances. A possible method of treating scavenging by snow is also suggested

Efficient scavenging of β-carotene radical cations by antiinflammatory salicylates

DEFF Research Database (Denmark)

Cheng, Hong; Liang, Ran; Han, Rui-Min

2014-01-01

by the anion of salicylic acid with 2.2 × 10 L mol s, but still of possible importance for light-exposed tissue. Surprisingly, acetylsalicylate, the aspirin anion, reacts with an intermediate rate in a reaction assigned to the anion of the mixed acetic-salicylic acid anhydride formed through base induced......The radical cation generated during photobleaching of β-carotene is scavenged efficiently by the anion of methyl salicylate from wintergreen oil in a second-order reaction approaching the diffusion limit with k = 3.2 × 10 L mol s in 9:1 v/v chloroform-methanol at 23 °C, less efficiently...... rearrangements. The relative scavenging rate of the β-carotene radical cation by the three salicylates is supported by DFT-calculations....

Influence of agitation intensity on flotation rate of apatite particles

Directory of Open Access Journals (Sweden)

Francisco Gregianin Testa

Full Text Available Abstract The agitation intensity has a directly influence on flotation performance, lifting the particles and promoting the contact of bubbles and particles. In this paper, the energy input by the agitation on apatite flotation was investigated. The influence of pulp agitation in the flotation rate of particles with different sizes and two dosage levels was evaluated by batch testing. The flotation tests were conducted in an oscillating grid flotation cell (OGC, developed to promote a near isotropic turbulence environment. The cell is able to control the intensity of agitation and measure the energy transferred to the pulp phase. A sample of pure apatite was crushed (P80=310µm, characterized and floated with sodium oleate as collector. Four levels of energy dissipation, from 0.1 to 2 kWm-3, and two levels of collector dosage are used during the tests. The flotation kinetics by particle size were determined in function of the energy transferred. The results show a strong influence of the agitation intensity on the apatite flotation rate with both low and high dosage. For fine particles, when increasing the energy input, the flotation rate increase too, and this fact can be attributed to elevation of bubble-particle collisions. The kinetic result for the coarse particles demonstrated a reduction of the flotation rate whenever the energy input for this particle size was increased, whereby the turbulence caused by the agitation promotes the detachment of bubble-particle.

Influence of microorganism content in suspended particles on the particle-water partitioning of mercury in semi-enclosed coastal waters.

Science.gov (United States)

Jang, Jiyi; Kim, Hyunji; Han, Seunghee

2014-02-01

It is known that particle scavenging of mercury (Hg) can be affected by the abundance of particulate organic matter in coastal waters. However, the role of living organic particles in Hg scavenging is not yet completely understood. In this study, we hypothesized that an abundance of living organic particles (i.e., phytoplankton and bacteria) would influence the particle-water partitioning of Hg in coastal waters. Surface seawater samples were collected from eight stations in Gwangyang Bay, Korea, in three seasons (November 2009, April 2010, and October 2010) for the determination of concentrations of suspended particulate matter (including chlorophyll-a and bacteria), and Hg in unfiltered and filtered waters. We found that more Hg partitioned toward particulate matter when phytoplankton biomass, indicated from the chlorophyll-a concentration in a particle, was higher. In the low algal season, when [chlorophyll-a]algae to transfer Hg to marine food chains. © 2013.

Simulation Modeling Method and Experimental Investigation on the Uniflow Scavenging System of an Opposed-Piston Folded-Cranktrain Diesel Engine

Directory of Open Access Journals (Sweden)

Fukang Ma

2017-05-01

Full Text Available The scavenging process for opposed-piston folded-cranktrain (OPFC diesel engines can be described by the time evolution of the in-cylinder and exhaust chamber residual gas rates. The relation curve of in-cylinder and exhaust chamber residual gas rate is called scavenging profile, which is calculated through the changes of in-cylinder and exhaust chamber gas compositions determined by computational fluid dynamics (CFD simulation. The scavenging profile is used to calculate the scavenging process by mono-dimensional (1D simulation. The tracer gas method (TGM is employed to validate the accuracy of the scavenging profile. At the same time, the gas exchange performance under different intake and exhaust state parameters was examined based on the TGM. The results show that the scavenging process from 1D simulation and experiment match well, which means the scavenging model obtained by CFD simulation performs well and validation of its effectiveness by TGM is possible. The difference between intake and exhaust pressure has a significant positive effect on the gas exchange performance and trapped gas mass, but the pressure difference has little effect on the scavenging efficiency and the trapped air mass if the delivery ratio exceeds 1.4.

Aerosol transport and wet scavenging in deep convective clouds: a case study and model evaluation using a multiple passive tracer analysis approach

Energy Technology Data Exchange (ETDEWEB)

Yang, Qing; Easter, Richard C.; Campuzano-Jost, Pedro; Jimenez, Jose L.; Fast, Jerome D.; Ghan, Steven J.; Wang, Hailong; Berg, Larry K.; Barth, Mary; Liu, Ying; Shrivastava, ManishKumar B.; Singh, Balwinder; Morrison, H.; Fan, Jiwen; Ziegler, Conrad L.; Bela, Megan; Apel, Eric; Diskin, G. S.; Mikoviny, Tomas; Wisthaler, Armin

2015-08-20

The effect of wet scavenging on ambient aerosols in deep, continental convective clouds in the mid-latitudes is studied for a severe storm case in Oklahoma during the Deep Convective Clouds and Chemistry (DC3) field campaign. A new passive-tracer based transport analysis framework is developed to characterize the convective transport based on the vertical distribution of several slowly reacting and nearly insoluble trace gases. The passive gas concentration in the upper troposphere convective outflow results from a mixture of 47% from the lower level (0-3 km), 21% entrained from the upper troposphere, and 32% from mid-atmosphere based on observations. The transport analysis framework is applied to aerosols to estimate aerosol transport and wet-scavenging efficiency. Observations yield high overall scavenging efficiencies of 81% and 68% for aerosol mass (Dp < 1μm) and aerosol number (0.03< Dp < 2.5μm), respectively. Little chemical selectivity to wet scavenging is seen among observed submicron sulfate (84%), organic (82%), and ammonium (80%) aerosols, while nitrate has a much lower scavenging efficiency of 57% likely due to the uptake of nitric acid. Observed larger size particles (0.15 - 2.5μm) are scavenged more efficiently (84%) than smaller particles (64%; 0.03 - 0.15μm). The storm is simulated using the chemistry version of the WRF model. Compared to the observation based analysis, the standard model underestimates the wet scavenging efficiency for both mass and number concentrations with low biases of 31% and 40%, respectively. Adding a new treatment of secondary activation significantly improves simulation results, so that the bias in scavenging efficiency in mass and number concentrations is reduced to <10%. This supports the hypothesis that secondary activation is an important process for wet removal of aerosols in deep convective storms.

Turbulent swirling flow in a dynamic model of a uniflow-scavenged two-stroke engine

Science.gov (United States)

Ingvorsen, K. M.; Meyer, K. E.; Walther, J. H.; Mayer, S.

2014-06-01

It is desirable to use computational fluid dynamics for optimization of the in-cylinder processes in low-speed two-stroke uniflow-scavenged marine diesel engines. However, the complex nature of the turbulent swirling in-cylinder flow necessitates experimental data for validation of the used turbulence models. In the present work, the flow in a dynamic scale model of a uniflow-scavenged cylinder is investigated experimentally. The model has a transparent cylinder and a moving piston driven by a linear motor. The flow is investigated using phase-locked stereoscopic particle image velocimetry (PIV) and time-resolved laser Doppler anemometry (LDA). Radial profiles of the phase-locked mean and rms velocities are computed from the velocity fields recorded with PIV, and the accuracy of the obtained profiles is demonstrated by comparison with reference LDA measurements. Measurements are carried out at five axial positions for 15 different times during the engine cycle and show the temporal and spatial development of the swirling in-cylinder flow. The tangential velocity profiles in the bottom of the cylinder near the end of the scavenge process are characterized by a concentrated swirl resulting in wake-like axial velocity profiles and the occurrence of a vortex breakdown. After scavenge port closing, the axial velocity profiles indicate that large transient swirl-induced structures exist in the cylinder. Comparison with profiles obtained under steady-flow conditions shows that the scavenge flow cannot be assumed to be quasi-steady. The temporal development of the swirl strength is investigated by computing the angular momentum. The swirl strength shows an exponential decay from scavenge port closing to scavenge port opening corresponding to a reduction of 34 %, which is in good agreement with theoretical predictions.

Particle and solution phase depth distributions of transuranics and 55Fe in the North Pacific

International Nuclear Information System (INIS)

Livingston, H.D.; Mann, D.R.; Casso, S.A.; Schneider, D.L.; Surprenant, L.D.; Bowen, V.T.

1987-01-01

In situ large volume filtration and chemisorption techniques were used to collect samples from the North Pacific for radiochemical analyses of fallout transuranics and 55 Fe in filterable and filtered phases. The data cover several locations for surface collections and a detailed depth profile north of Hawaii at 30 0 N. The observed partition of these nuclides between suspended particulate and filtered phases is directly linked to the rates at which they are moved downward through the water column in association with sinking particles. Particulate phases in open ocean surface waters contain higher Pu than subsurface particulates. 241 Am was found to exhibit much stronger particle association in accord with its known greater particle reactivity. In the high Pu deep water layer, particle associated Pu dropped to close to 1% of total Pu concentration. Together with a correlated increase in the proportion of oxidized Pu in this layer close to the sediment-water interface, this is clear evidence of remobilization of Pu from particles at, or near to, the interface. 55 Fe distributions on filtered particulates indicate a much deeper depth distribution relative to the transuranics. This may reflect both a higher particle association reactivity in respect to scavenging and a longer exposure history to scavenging. (author)

The Influence of Particle Charge on Heterogeneous Reaction Rate Coefficients

Science.gov (United States)

Aikin, A. C.; Pesnell, W. D.

2000-01-01

The effects of particle charge on heterogeneous reaction rates are presented. Many atmospheric particles, whether liquid or solid are charged. This surface charge causes a redistribution of charge within a liquid particle and as a consequence a perturbation in the gaseous uptake coefficient. The amount of perturbation is proportional to the external potential and the square of the ratio of debye length in the liquid to the particle radius. Previous modeling has shown how surface charge affects the uptake coefficient of charged aerosols. This effect is now included in the heterogeneous reaction rate of an aerosol ensemble. Extension of this analysis to ice particles will be discussed and examples presented.

Dielectric polymer: scavenging energy from human motion

Science.gov (United States)

Jean-Mistral, Claire; Basrour, Skandar; Chaillout, Jean-Jacques

2008-03-01

More and more sensors are embedded in human body for medical applications, for sport. The short lifetime of the batteries, available on the market, reveals a real problem of autonomy of these systems. A promising alternative is to scavenge the ambient energy such as the mechanical one. Up to now, few scavenging structures have operating frequencies compatible with ambient one. And, most of the developed structures are rigid and use vibration as mechanical source. For these reasons, we developed a scavenger that operates in a large frequency spectrum from quasi-static to dynamic range. This generator is fully flexible, light and does not hamper the human motion. Thus, we report in this paper an analytical model for dielectric generator with news electrical and mechanical characterization, and the development of an innovating application: scavenging energy from human motion. The generator is located on the knee and design to scavenge 0.1mJ per scavenging cycle at a frequency of 1Hz, enough to supply a low consumption system and with a poling voltage as low as possible to facilitate the power management. Our first prototype is a membrane with an area of 5*3cm and 31µm in thickness which scavenge 0.1mJ under 170V at constant charge Q.

Electron scavenging in ethylene glycol-water glass at 4 and 77 K: scavenging of trapped vs mobile electrons. [. gamma. -rays, x radiation

Energy Technology Data Exchange (ETDEWEB)

Lin, D P; Kevan, L [Wayne State Univ., Detroit, Mich. (USA). Dept. of Chemistry; Steen, H B

1976-01-01

Electron scavenging efficiencies have been measured at 77 and 4 K in ethylene glycol-water glass for the following scavengers which span a 250-fold range of scavenger efficiencies at 77 K: HCl, NaNO/sub 3/ and K/sub 2/Cr0/sub 4/. The range of scavenging efficiencies decreases to 62 at 4 K with the largest relative change occurring for the less efficient scavengers. These results are suggested to be most consistent with a model in which scavenging occurs by tunneling from shallowly and deeply trapped electrons at 4 and 77 K, respectively.

X particle effect for 6Li reaction rates calculations

International Nuclear Information System (INIS)

Kocak, G.; Balantekin, A. B.

2009-01-01

The inferred primordial 6 L i-7 L i abundances are different from standard big bang nucleosynthesis results, 6 L i is 1000 times larger and 7 L i is 3 times smaller than the big bang prediction. In big bang nucleosynthesis, negatively charged massive X particles a possible solution to explain this primordial Li abundances problem [1]. In this study, we consider only X particle effect for nuclear reactions to obtain S-factor and reaction rates for Li. All S-factors calculated within the Optical Model framework for d(α,γ)6 L i system. We showed that the enhancement effect of massive negatively charged X particle for 6 L i system reaction rate.(author)

Below-cloud scavenging by the rain: a micro physical approach

International Nuclear Information System (INIS)

Querel, A.

2012-01-01

Aerosol particles are an important component of the atmosphere and are of great concern in the case of an accidental release of radioactive particles. To better understand ground contamination due to a particle release in the vicinity of an accident, it is important to study the particle scavenging associated with rain. To achieve this objective during this thesis, an experiment at the micro physical scale (BERGAME experiment) was developed and the modelling of the washout was improved at mesoscale. The model used was DESCAM: a microphysics model that describes the bin size distributions for aerosol particles and hydro-meteors and calculates their evolution due to micro physical cloud processes. The BERGAME experiment was designed and built to measure the collection efficiencies which disagree with theoretical calculation. Using an optical method, it was shown that those discrepancies were due to rear capture. A new model of collection efficiencies for the 2 mm drops was proposed that takes into account for big raindrops the turbulent circulation occurring downstream increasing significantly the capture of small particles. The corrected collection efficiencies were implemented in the DESCAM model. By this way, significant modifications of the modelling were observed and studied. This is an important step toward an accurate modelling of the ground contamination in atmospheric dispersion models. (author)

The scavenger endothelial cell: a new player in homeostasis and immunity.

Science.gov (United States)

Sørensen, Karen Kristine; McCourt, Peter; Berg, Trond; Crossley, Clive; Le Couteur, David; Wake, Kenjiro; Smedsrød, Bård

2012-12-15

To maintain homeostasis, the animal body is equipped with a powerful system to remove circulating waste. This review presents evidence that the scavenger endothelial cell (SEC) is responsible for the clearance of blood-borne waste macromolecules in vertebrates. SECs express pattern-recognition endocytosis receptors (mannose and scavenger receptors), and in mammals, the endocytic Fc gamma-receptor IIb2. This cell type has an endocytic machinery capable of super-efficient uptake and degradation of physiological and foreign waste material, including all major classes of biological macromolecules. In terrestrial vertebrates, most SECs line the wall of the liver sinusoid. In phylogenetically older vertebrates, SECs reside instead in heart, kidney, or gills. SECs, thus, by virtue of their efficient nonphagocytic elimination of physiological and microbial substances, play a critical role in the innate immunity of vertebrates. In major invertebrate phyla, including insects, the same function is carried out by nephrocytes. The concept of a dual-cell principle of waste clearance is introduced to emphasize that professional phagocytes (macrophages in vertebrates; hemocytes in invertebrates) eliminate larger particles (>0.5 μm) by phagocytosis, whereas soluble macromolecules and smaller particles are eliminated efficiently and preferentially by clathrin-mediated endocytosis in nonphagocytic SECs in vertebrates or nephrocytes in invertebrates. Including these cells as important players in immunology and physiology provides an additional basis for understanding host defense and tissue homeostasis.

Bystander effect of alpha-particle irradiation on mutagenicity and its associated mechanism

International Nuclear Information System (INIS)

Lu Ying; Yang Zhihua; Cao Zhenshan; Fan Feiyue; Zhu Maoxiang

2004-01-01

The work is to investigate α-particle irradiation-induced bystander effects on the mutagenicity in human chromosome 11 in the human-hamster hybrid (A L cells) and its possible mechanism. A L cells were used for assaying mutation rates of human chromosome 11 through screening mutants in the presence of anti-CD59 surface antigen antibody (S1) and complement. A grid was interposed between α-particle source and the cells being irradiated, so as to fix proportion of the irradiated cells (15%) and the bystander effects on the mutagenicity were detected. Free radical scavenger DMSO and intercellular communication inhibitor Lindane were selected to investigate the potential mechanism of α-particle induced bystander effect. There was clear dose-dependent relationship between mutation rate and the dose of alpha particle radiation. However, the mutant fractions of cell population shielded by the grid in α-particle irradiation system were much higher than the expected levels of irradiated cells. Lindane, but not DMSO, could obviously decrease this bystander effect induced by α-particle irradiation. Alpha-particle irradiation can induce bystander effect on the mutagenicity, in which intercellular communication may play important roles

Scavenging of particulate elemental carbon into stratus cloud

Energy Technology Data Exchange (ETDEWEB)

Kaneyasu, Naoki; Maeda, Takahisa [National Inst. for Resources and Environment, Tsukuba (Japan)

1995-12-31

The role of atmospheric aerosols on the alternation of cloud radiative properties has widely been recognized since 1977 when Tomey and his coworkers have numerically demonstrated the effect of increased cloud condensation nuclei (CCN). At the same time, cloud processes are one of the most important factor in controlling the residence time of atmospheric aerosols through the wet removal process. The redistribution of the size and the composition of pre-cloud aerosols is also the important role of cloud process on the nature of atmospheric aerosols. In order to study these cloud-aerosol interaction phenomena, the incorporation of aerosols into cloud droplets is the first mechanism to be investigated. Among the several mechanisms for the incorporation of aerosols into cloud droplets, nucleation scavenging, is the potentially important process in the view of cloud-aerosol interactions. This critical supersaturation for a given radius of a particle can be theoretically calculated only for pure species, e.g., NaCl. However, a significant portion of the atmospheric aerosols is in the form of internal mixture of multiple components, such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, NH{sub 4}{sup +} and particulate elemental carbon. The knowledge acquired by field measurements is therefore essential on this subject. The present study focuses on the scavenging of major components of urban atmospheric aerosols, in particular the incorporation of particulate elemental carbon into stratus cloud. Particulate elemental carbon is the strongest light absorbing species in visible region, and has potential to change the optical property of cloud. On the basis of the measurements conducted at a mountain located in the suburb of Tokyo Metropolitan area, Japan, some insights on the scavenging of particulate elemental carbon into cloud droplet will be presented

Scavenging of particulate elemental carbon into stratus cloud

Energy Technology Data Exchange (ETDEWEB)

Kaneyasu, Naoki; Maeda, Takahisa [National Inst. for Resources and Environment, Tsukuba (Japan)

1996-12-31

The role of atmospheric aerosols on the alternation of cloud radiative properties has widely been recognized since 1977 when Tomey and his coworkers have numerically demonstrated the effect of increased cloud condensation nuclei (CCN). At the same time, cloud processes are one of the most important factor in controlling the residence time of atmospheric aerosols through the wet removal process. The redistribution of the size and the composition of pre-cloud aerosols is also the important role of cloud process on the nature of atmospheric aerosols. In order to study these cloud-aerosol interaction phenomena, the incorporation of aerosols into cloud droplets is the first mechanism to be investigated. Among the several mechanisms for the incorporation of aerosols into cloud droplets, nucleation scavenging, is the potentially important process in the view of cloud-aerosol interactions. This critical supersaturation for a given radius of a particle can be theoretically calculated only for pure species, e.g., NaCl. However, a significant portion of the atmospheric aerosols is in the form of internal mixture of multiple components, such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, NH{sub 4}{sup +} and particulate elemental carbon. The knowledge acquired by field measurements is therefore essential on this subject. The present study focuses on the scavenging of major components of urban atmospheric aerosols, in particular the incorporation of particulate elemental carbon into stratus cloud. Particulate elemental carbon is the strongest light absorbing species in visible region, and has potential to change the optical property of cloud. On the basis of the measurements conducted at a mountain located in the suburb of Tokyo Metropolitan area, Japan, some insights on the scavenging of particulate elemental carbon into cloud droplet will be presented

Scavenger receptors in homeostasis and immunity.

Science.gov (United States)

Canton, Johnathan; Neculai, Dante; Grinstein, Sergio

2013-09-01

Scavenger receptors were originally identified by their ability to recognize and to remove modified lipoproteins; however, it is now appreciated that they carry out a striking range of functions, including pathogen clearance, lipid transport, the transport of cargo within the cell and even functioning as taste receptors. The large repertoire of ligands recognized by scavenger receptors and their broad range of functions are not only due to the wide range of receptors that constitute this family but also to their ability to partner with various co-receptors. The ability of individual scavenger receptors to associate with different co-receptors makes their responsiveness extremely versatile. This Review highlights recent insights into the structural features that determine the function of scavenger receptors and the emerging role that these receptors have in immune responses, notably in macrophage polarization and in the pathogenesis of diseases such as atherosclerosis and Alzheimer's disease.

Body Size as a Driver of Scavenging in Theropod Dinosaurs.

Science.gov (United States)

Kane, Adam; Healy, Kevin; Ruxton, Graeme D; Jackson, Andrew L

2016-06-01

Theropod dinosaurs dominated Earth's terrestrial ecosystem as a diverse group of predators for more than 160 million years, yet little is known about their foraging ecology. Maintaining a balanced energy budget presented a major challenge for therapods, which ranged from the chicken-sized Microraptor up to the whale-sized Giganotosaurus, in the face of intense competition and the demands of ontogenetic growth. Facultative scavenging, a behavior present in almost all modern predators, may have been important in supplementing energetically expensive lifestyles. By using agent-based models based on the allometric relationship between size and foraging behaviors, we show that theropods between 27 and 1,044 kg would have gained a significant energetic advantage over individuals at both the small and large extremes of theropod body mass through their scavenging efficiency. These results were robust to rate of competition, primary productivity, and detection distance. Our models demonstrate the potential importance of facultative scavenging in theropods and the role of body size in defining its prevalence in Mesozoic terrestrial systems.

Gallic Acid as an Oxygen Scavenger in Bio-Based Multilayer Packaging Films.

Science.gov (United States)

Pant, Astrid F; Sängerlaub, Sven; Müller, Kajetan

2017-05-03

Oxygen scavengers are used in food packaging to protect oxygen-sensitive food products. A mixture of gallic acid (GA) and sodium carbonate was used as an oxygen scavenger (OSc) in bio-based multilayer packaging films produced in a three-step process: compounding, flat film extrusion, and lamination. We investigated the film surface color as well as oxygen absorption at different relative humidities (RHs) and temperatures, and compared the oxygen absorption of OSc powder, monolayer films, and multilayer films. The films were initially brownish-red in color but changed to greenish-black during oxygen absorption under humid conditions. We observed a maximum absorption capacity of 447 mg O₂/g GA at 21 °C and 100% RH. The incorporation of GA into a polymer matrix reduced the rate of oxygen absorption compared to the GA powder because the polymer acted as a barrier to oxygen and water vapor diffusion. As expected, the temperature had a significant effect on the initial absorption rate of the multilayer films; the corresponding activation energy was 75.4 kJ/mol. Higher RH significantly increased the oxygen absorption rate. These results demonstrate for the first time the production and the properties of a bio-based multilayer packaging film with GA as the oxygen scavenger. Potential applications include the packaging of food products with high water activity (a w > 0.86).

Scavenging capacity of medicinal plants against free radical-induced cellular damage by radiation and photoactivation

Energy Technology Data Exchange (ETDEWEB)

Gadkar, Shalaka [Ruia College, Mumbai (India); Mohan, H [Chemistry Group, Bhabha Atomic Research Centre, Mumbai (India); Kamat, J P [Radiation Biology and Health Science Division, Bhabha Atomic Research Centre, Mumbai (India)

2004-01-01

The scavenging capacity of medicinal plants. Andrographis paniculata (Ap) and Swertia chirata (Sc) was examined against cellular damage, induced by radiation and photo-activation in sub-cellular membranes. The results demonstrated significant radical scavenging capacity of the extracts. The rate constants as evaluated by deoxyribose degradation studies and the pulse radiolysis studies carried in presence of ABTS radical well supported the antioxidant properties of the extracts. (author)

Hydrothermal Fe cycling and deep ocean organic carbon scavenging: Model-based evidence for significant POC supply to seafloor sediments

Digital Repository Service at National Institute of Oceanography (India)

German, C.R.; Legendre, L.L.; Sander, S.G.;; Niquil, N.; Luther-III, G.W.; LokaBharathi, P.A.; Han, X.; LeBris, N.

by more than ~10% over background values, what the model does indicate is that scavenging of carbon in association with Fe-rich hydrothermal plume particles should play a significant role in the delivery of particulate organic carbon to deep ocean...

Differential Scavenging Among Pig, Rabbit, and Human Subjects.

Science.gov (United States)

Steadman, Dawnie Wolfe; Dautartas, Angela; Kenyhercz, Michael W; Jantz, Lee M; Mundorff, Amy; Vidoli, Giovanna M

2018-04-12

Different animal species have been used as proxies for human remains in decomposition studies for decades, although few studies have sought to validate their use in research aimed at estimating the postmortem interval. This study examines 45 pig, rabbit, and human subjects placed in three seasonal trials at the Anthropology Research Facility. In an earlier paper, we found that overall decomposition trends did vary between species that could be due to differential insect and scavenger behavior. This study specifically examines if scavenger behavior differs by carrion species. Daily photographs, game camera photographs, written observations, and Total Body Score (TBS) documented scavenging and decomposition changes. Results show that raccoons were the most commonly observed vertebrate scavenger, that scavenging was most extensive in winter, and that certain human subjects were preferred over other humans and all non-human subjects. Finally, scavenging activity greatly reduces the accuracy of postmortem interval estimates based on TBS. © 2018 American Academy of Forensic Sciences.

A new method for measuring scavenging activity of antioxidants to the hydroxyl radical formed by gamma-irradiation

International Nuclear Information System (INIS)

Yoshioka, Hiroe; Ohashi, Yasunori

2000-01-01

A new method using ESR spin trapping was proposed for measuring scavenging activity of antioxidants to the hydroxyl (OH) radical. (-)-epigallocatechin gallate (EGCg) and 5,5-dimethyl-l-pyrroline N-oxide (DMPO) were used as an antioxidant and a spin trapping agent, respectively. Conventional method using a Fenton reaction had some defects on the estimation of the activity, because antioxidant disturbed the generating system of OH radical besides it scavenged the spin adduct (DMPO-OH). This method used intense γ-irradiation as OH radical generating system, and the intensity decrease of DMPO-OH after the end of the irradiation was followed to obtain the rate constant of the scavenging of DMPO-OH with EGCg and to estimate the quantity of DMPO-OH formed during γ-irradiation. By using these values, the reaction rate constant between OH radical and EGCg was calculated as a ratio to that of DMPO. It was shown that this method is useful to compare precisely the OH radical scavenging activity of various antioxidants. (author)

Deposition of particles and iodine to outdoor surfaces and in the respiratory tract

International Nuclear Information System (INIS)

Garland, J.A.

1988-01-01

Dry deposition of particles depends strongly on particle size, and is also influenced by the geometry of the surface and weather parameters. Precipitation scavenging is also influenced to some degree by particle size, but hygroscopic properties of soluble particles are also likely to enhance deposition in precipitation. Similar comments apply in the respiratory tract, where particle size and solubility may influence the extent and site of deposition: the site is important for insoluble particles at least since it determines retention time in the body. Thus measurement of particle size and investigation of solubility would be valuable in interpreting deposition inhalation and air concentration observations. Iodine has several chemical forms in the air. It is valuable to sample in such a way that different forms are partitioned, although there is some uncertainty in their identification. The rate of deposition to vegetation depends strongly on the chemical form of the iodine, but the vapour forms of iodine that occur in the atmosphere may all be retained efficiently on inhalation

Americans with Disabilities Act Scavenger Hunt

Science.gov (United States)

Ramsey, Ursula

2018-01-01

This article describes a scavenger hunt for Business Law students. Specifically, students compete in this scavenger hunt to identify accessible design features on campus to undergird their study of Title III of the Americans with Disabilities Act (ADA). Title III of the ADA prohibits public accommodations from discriminating on the basis of…

In vitro free radical scavenging activity of platinum nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Watanabe, Aki; Kajita, Masashi; Kim, Juewon; Kanayama, Atsuhiro; Miyamoto, Yusei [Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 402, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562 (Japan); Takahashi, Kyoko; Mashino, Tadahiko, E-mail: yusei74@k.u-tokyo.ac.j [Department of Pharmaceutical Sciences, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato, Tokyo 105-8512 (Japan)

2009-11-11

A polyacrylic acid (PAA)-protected platinum nanoparticle species (PAA-Pt) was prepared by alcohol reduction of hexachloroplatinate. The PAA-Pt nanoparticles were well dispersed and homogeneous in size with an average diameter of 2.0 {+-} 0.4 nm (n = 200). We used electron spin resonance to quantify the residual peroxyl radical AOO. generated from 2,2-azobis (2-aminopropane) dihydrochloride (AAPH) by thermal decomposition in the presence of O{sub 2} and a spectrophotometric method to quantify the residual 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. PAA-Pt scavenged these two radicals in a dose-dependent manner. Platinum was the functional component. PAA-Pt reduced the rate of oxygen consumption required for linoleic acid peroxidation initiated by AOO. generated from AAPH, indicating inhibition of the propagation of linolate peroxidation. A thiobarbituric acid test also revealed dose-dependent inhibition of the linolate peroxidation by PAA-Pt. Fifty micromolar platinum, as PAA-Pt, completely quenched 250 {mu}M DPPH radical for 5 min. Even when twice diluted in half, the PAA-Pt still quenched 100% of the 250 {mu}M DPPH radical. The scavenging activity of PAA-Pt is durable. These observations suggest that PAA-Pt is an efficient scavenger of free radicals.

Investigation into Seasonal Scavenging Patterns of Raccoons on Human Decomposition.

Science.gov (United States)

Jeong, Yangseung; Jantz, Lee Meadows; Smith, Jake

2016-03-01

Although raccoons are known as one of the most common scavengers in the U.S., scavenging by these animals has seldom been studied in terms of forensic significance. In this research, the seasonal pattern of raccoon scavenging and its effect on human decomposition was investigated using 178 human cadavers placed at the Anthropological Research Facility (ARF) of the University of Tennessee, Knoxville (UTK) between February 2011 and December 2013. The results reveal that (i) the frequency of scavenging increases during summer, (ii) scavenging occurs relatively immediately and lasts shorter in summer months, and (iii) scavenging influences the decomposition process by hollowing limbs and by disturbing insect activities, both of which eventually increases the chance of mummification on the affected body. This information is expected to help forensic investigators identify raccoon scavenging as well as make a more precise interpretation of the effect of raccoon scavenging on bodies at crime scenes. © 2015 American Academy of Forensic Sciences.

Remarks relating to field experiments to measure the wet scavenging of tracer aerosols

International Nuclear Information System (INIS)

Stensland, G.J.

1977-12-01

An important question is whether or not the wet deposition of debris from a single (or multiple) airburst of a nuclear device poses a significant hazard to people on the ground. To answer this question for various scenarios, a basic understanding of the aerosol attachment rates to cloud water and raindrops is needed. The attachment rates can then be incorporated into the cloud physics scavenging models to make intelligent assessments. In order to gain an initial impression as to the importance (order of magnitude) of the wet scavenging effects and to provide the data to validate the cloud scavenging models, tracer release field experiments are useful and necessary. The major purpose of this report is to address questions related to the operation and interpretation of such field tracer efforts and in particular to consider the results from the August 3, 1972, Battelle Northwest Laboratory tracer experiment in St. Louis. The Battelle experiment involved the release of several aerosol tracers at 10,000 to 13,000 feet, near rain clouds, and the measurement of the resulting tracer in the rain collected at the ground level sampling sites

Shark scavenging behavior in the presence of competition

Directory of Open Access Journals (Sweden)

Shannon P. GERRY, Andrea J. SCOTT

2010-02-01

Full Text Available The distribution of organisms within a community can often be determined by the degree of plasticity or degree of specialization of resource acquisition. Resource acquisition is often based on the morphology of an organism, behavior, or a combination of both. Performance tests of feeding can identify the possible interactions that allow one species to better exploit a prey item. Scavenging behaviors in the presence or absence of a competitor were investigated by quantifying prey selection in a trophic generalist, spiny dogfish Squalus acanthias, and a trophic specialist, smooth-hounds Mustelus canis, in order to determine if each shark scavenged according to its jaw morphology. The diet of dogfish consists of small fishes, squid, ctenophores, and bivalves; they are expected to be nonselective predators. Smooth-hounds primarily feed on crustaceans; therefore, they are predicted to select crabs over other prey types. Prey selection was quantified by ranking each prey item according to the order it was consumed. Dietary shifts were analyzed by comparing the percentage of each prey item selected during solitary versus competitive scavenging. When scavenging alone, dogfish prefer herring and squid, which are easily handled by the cutting dentition of dogfish. Dogfish shift their diet to include a greater number of prey types when scavenging with a competitor. Smooth-hounds scavenge on squid, herring, and shrimp when alone, but increase the number of crabs in the diet when scavenging competitively. Competition causes smooth-hounds to scavenge according to their jaw morphology and locomotor abilities, which enables them to feed on a specialized resource [Current Zoology 56 (1: 100–108 2010].

Radical scavenging activity of crude polysaccharides from Camellia sinensis

Directory of Open Access Journals (Sweden)

Yang Fan

2011-01-01

Full Text Available A preparation of crude polysaccharides (TPS was isolated from Camellia sinensis by precipitation and ultrafiltration. TPS1, TPS2, and TPS3 had molecular weights of 240, 21.4, and 2.46 kDa, respectively. The radical scavenging activities of TPS were evaluated by DPPH free radical, hydroxyl radical and superoxide radical scavenging. These results revealed that TPS exhibited strong radical scavenging activity in a concentration-dependent manner. TPS3 with lowest molecular weight showed a higher radical scavenging activity.

Serum Hydroxyl Radical Scavenging Capacity as Quantified with Iron-Free Hydroxyl Radical Source

Science.gov (United States)

Endo, Nobuyuki; Oowada, Shigeru; Sueishi, Yoshimi; Shimmei, Masashi; Makino, Keisuke; Fujii, Hirotada; Kotake, Yashige

2009-01-01

We have developed a simple ESR spin trapping based method for hydroxyl (OH) radical scavenging-capacity determination, using iron-free OH radical source. Instead of the widely used Fenton reaction, a short (typically 5 seconds) in situ UV-photolysis of a dilute hydrogen peroxide aqueous solution was employed to generate reproducible amounts of OH radicals. ESR spin trapping was applied to quantify OH radicals; the decrease in the OH radical level due to the specimen’s scavenging activity was converted into the OH radical scavenging capacity (rate). The validity of the method was confirmed in pure antioxidants, and the agreement with the previous data was satisfactory. In the second half of this work, the new method was applied to the sera of chronic renal failure (CRF) patients. We show for the first time that after hemodialysis, OH radical scavenging capacity of the CRF serum was restored to the level of healthy control. This method is simple and rapid, and the low concentration hydrogen peroxide is the only chemical added to the system, that could eliminate the complexity of iron-involved Fenton reactions or the use of the pulse-radiolysis system. PMID:19794928

A numerical model of aerosol scavenging

International Nuclear Information System (INIS)

Bradley, M.M.; Molenkamp, C.R.

1991-10-01

Using a three-dimensional numerical cloud/smoke-plume model, we have simulated the burning of a large, mid-latitude city following a nuclear exchange. The model includes 18 dynamic and microphysical equations that predict the fire-driven airflow, cloud processes, and smoke-cloud interactions. In the simulation, the intense heating from the burning city produces a firestorm with updraft velocities exceeding 60 m/s. Within 15 minutes of ignition, the smoke plume penetrates the tropopause. The updraft triggers a cumulonimbus cloud that produces significant quantities of ice, snow, and hail. These solid hydrometeors, as well as cloud droplets and rain, interact with the smoke particles from the fire. At the end of the one-hour simulation, over 20% of the smoke is in slowly falling snowflakes. If the snow reaches the ground before the flakes completely sublimate (or melt and then evaporate), then only approximately 50% of the smoke will survive the scavenging processes and remain in the atmosphere to affect the global climate

Smooth Interfacial Scavenging for Resistive Switching Oxide via the Formation of Highly Uniform Layers of Amorphous TaOx.

Science.gov (United States)

Tsurumaki-Fukuchi, Atsushi; Nakagawa, Ryosuke; Arita, Masashi; Takahashi, Yasuo

2018-02-14

We demonstrate that the inclusion of a Ta interfacial layer is a remarkably effective strategy for forming interfacial oxygen defects at metal/oxide junctions. The insertion of an interfacial layer of a reactive metal, that is, a "scavenging" layer, has been recently proposed as a way to create a high concentration of oxygen defects at an interface in redox-based resistive switching devices, and growing interest has been given to the underlying mechanism. Through structural and chemical analyses of Pt/metal/SrTiO 3 /Pt structures, we reveal that the rate and amount of oxygen scavenging are not directly determined by the formation free energies in the oxidation reactions of the scavenging metal and unveil the important roles of oxygen diffusibility. Active oxygen scavenging and highly uniform oxidation via scavenging are revealed for a Ta interfacial layer with high oxygen diffusibility. In addition, the Ta scavenging layer is shown to exhibit a highly uniform structure and to form a very flat interface with SrTiO 3 , which are advantageous for the fabrication of a steep metal/oxide contact.

Estimates of particle- and thorium-cycling rates in the northwest Atlantic Ocean

International Nuclear Information System (INIS)

Murnane, R.J.; Sarmiento, J.L.; Cochran, J.K.

1994-01-01

The authors provide least squares estimates of particle-cycling rate constants and their errors at 13 depths in the Northwest Atlantic Ocean using a compilation of published results and conservation equations for thorium and particle cycling. The predicted rates of particle aggregation and disaggregation vary through the water column. The means and standard deviations, based on lognormal probability distributions, for the lowest and highest rates of aggregation (β 2 ) and disaggregation (β -2 ) in the water column are 8±27 y -1 2 -1 , and 580±2000 y -1 -2 3 ±10 4 y -1 . Median values for these rates are 2.1 y -1 2 -1 , and 149 y -1 -2 -1 . Predicted rate constants for thorium adsorption (k 1 = 5.0±1.0x10 4 m 3 kg -1 y -1 ) and desorption (k -1 = 3.1±1.5 y -1 ) are consistent with previous estimates. Least squares estimates of the sum of the time dependence and transport terms from the particle and thorium conservation equations are on the same order as other terms in the conservation equations. Forcing this sum to equal zero would change the predicted rates. Better estimates of the time dependence of thorium activities and particle concentrations and of the concentration and flux of particulate organic matter would help to constrain estimates of β 2 and β -2 . 46 refs., 8 figs., 5 tabs

Integral Engine Inlet Particle Separator. Volume 2. Design Guide

Science.gov (United States)

1975-08-01

herein will be used in the design of integral inlet particle separators for future Army aircraft gas turbine engines. Apprupriate technical personnel...into the comprensor at some future date. 5. A typical scavenge vane design Js; shown in Figures 85 and 86. The important features of the scavenge...service passageweys, for cooling of oil, and for directing sand and air into the scroll. Orientetion of the vanes is set by collection efficiency

Weight savings in aerospace vehicles through propellant scavenging

Science.gov (United States)

Schneider, Steven J.; Reed, Brian D.

1988-01-01

Vehicle payload benefits of scavenging hydrogen and oxygen propellants are addressed. The approach used is to select a vehicle and a mission and then select a scavenging system for detailed weight analysis. The Shuttle 2 vehicle on a Space Station rendezvous mission was chosen for study. The propellant scavenging system scavenges liquid hydrogen and liquid oxygen from the launch propulsion tankage during orbital maneuvers and stores them in well insulated liquid accumulators for use in a cryogenic auxiliary propulsion system. The fraction of auxiliary propulsion propellant which may be scavenged for propulsive purposes is estimated to be 45.1 percent. The auxiliary propulsion subsystem dry mass, including the proposed scavenging system, an additional 20 percent for secondary structure, an additional 5 percent for electrical service, a 10 percent weight growth margin, and 15.4 percent propellant reserves and residuals is estimated to be 6331 kg. This study shows that the fraction of the on-orbit vehicle mass required by the auxiliary propulsion system of this Shuttle 2 vehicle using this technology is estimated to be 12.0 percent compared to 19.9 percent for a vehicle with an earth-storable bipropellant system. This results in a vehicle with the capability of delivering an additional 7820 kg to the Space Station.

Weight savings in aerospace vehicles through propellant scavenging

Science.gov (United States)

Schneider, Steven J.; Reed, Brian D.

1988-05-01

Vehicle payload benefits of scavenging hydrogen and oxygen propellants are addressed. The approach used is to select a vehicle and a mission and then select a scavenging system for detailed weight analysis. The Shuttle 2 vehicle on a Space Station rendezvous mission was chosen for study. The propellant scavenging system scavenges liquid hydrogen and liquid oxygen from the launch propulsion tankage during orbital maneuvers and stores them in well insulated liquid accumulators for use in a cryogenic auxiliary propulsion system. The fraction of auxiliary propulsion propellant which may be scavenged for propulsive purposes is estimated to be 45.1 percent. The auxiliary propulsion subsystem dry mass, including the proposed scavenging system, an additional 20 percent for secondary structure, an additional 5 percent for electrical service, a 10 percent weight growth margin, and 15.4 percent propellant reserves and residuals is estimated to be 6331 kg. This study shows that the fraction of the on-orbit vehicle mass required by the auxiliary propulsion system of this Shuttle 2 vehicle using this technology is estimated to be 12.0 percent compared to 19.9 percent for a vehicle with an earth-storable bipropellant system. This results in a vehicle with the capability of delivering an additional 7820 kg to the Space Station.

Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating.

Science.gov (United States)

Koivisto, Antti J; Jensen, Alexander C Ø; Kling, Kirsten I; Kling, Jens; Budtz, Hans Christian; Koponen, Ismo K; Tuinman, Ilse; Hussein, Tareq; Jensen, Keld A; Nørgaard, Asger; Levin, Marcus

2018-01-05

Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO 2 )-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m 3 test chamber while measuring concentrations of 5.6nm to 31μm-size particles and volatile organic compounds (VOC), as well as particle deposition onto room surfaces and on the spray gun user hand. The particle emission and deposition rates were quantified using aerosol mass balance modelling. The geometric mean particle number emission rate was 1.9×10 10 s -1 and the mean mass emission rate was 381μgs -1 . The respirable mass emission-rate was 65% lower than observed for the entire measured size-range. The mass emission rates were linearly scalable (±ca. 20%) to the process duration. The particle deposition rates were up to 15h -1 for deposited particles consisted of mainly TiO 2 , TiO 2 mixed with Cl and/or Ag, TiO 2 particles coated with carbon, and Ag particles with size ranging from 60nm to ca. 5μm. As expected, no significant VOC emissions were observed as a result of spraying. Finally, we provide recommendations for exposure model parameterization. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

A new class of free radical scavengers reducing adriamycin mitochondrial toxicity

NARCIS (Netherlands)

Praet, M.; Calderon, P. B.; Pollakis, G.; Roberfroid, M.; Ruysschaert, J. M.

1988-01-01

Beef heart mitochondria were incubated with ADM and NADH. An adriamycin semiquinone radical was detected using ESR spectroscopy. The semiquinone radical production rate is decreased upon addition of a scavenger (AD 20) in the reaction medium. NMRI mice were treated with AD 20 (70 mg/kg, i.p.) 15 min

Assessment of weathering and leaching rates of Thule hot particles

Energy Technology Data Exchange (ETDEWEB)

Roos, P. (Technical Univ. of Denmark, Risoe National Laboratory for Sustainable Energy, Roskilde (Denmark)); Outola, I. (STUK-Radiation and Nuclear Safety Authority (Finland)); Nygren, U.; Ramebaeck, H. (FOI CBRN Defence and Security (Sweden)); Sidhu, R. (Institute of Energy Technology, Environmental Monitoring Section, Health and Safety Dept. (Norway))

2010-03-15

Within the current project a methodology for separating actinide particles originating from the Thule 1968 accident has been developed. Particles were completely isolated in water using visual and radiometric methods. The particles were attached electrostatic to a plastic support and could easily be moved to any container for leaching studies or other type of studies. Leaching and dissolution studies performed within the project indicate that some particles are relatively easily destroyed or leached while others are more refractory. The results shows that even though the oxide particles are hard to completely dissolve they release material even when exposed to weak solvents like water and salt solutions. Exposures to lung simulant fluids show relatively slow dissolution rates comparable to what is found using only water. Sequential extraction of particles shows that variation between particles is very large; some dissolve easily while some does not. Of radiological importance is the disruption of particles when exposed to dissolution. (author)

Assessment of weathering and leaching rates of Thule hot particles

International Nuclear Information System (INIS)

Roos, P.; Outola, I.; Nygren, U.; Ramebaeck, H.; Sidhu, R.

2010-03-01

Within the current project a methodology for separating actinide particles originating from the Thule 1968 accident has been developed. Particles were completely isolated in water using visual and radiometric methods. The particles were attached electrostatic to a plastic support and could easily be moved to any container for leaching studies or other type of studies. Leaching and dissolution studies performed within the project indicate that some particles are relatively easily destroyed or leached while others are more refractory. The results shows that even though the oxide particles are hard to completely dissolve they release material even when exposed to weak solvents like water and salt solutions. Exposures to lung simulant fluids show relatively slow dissolution rates comparable to what is found using only water. Sequential extraction of particles shows that variation between particles is very large; some dissolve easily while some does not. Of radiological importance is the disruption of particles when exposed to dissolution. (author)

Conservative interacting particles system with anomalous rate of ergodicity

OpenAIRE

Brzeźniak, Zdzislaw; Flandoli, Franco; Neklyudov, Misha; Zegarliński, Boguslaw

2010-01-01

We analyze certain conservative interacting particle system and establish ergodicity of the system for a family of invariant measures. Furthermore, we show that convergence rate to equilibrium is exponential. This result is of interest because it presents counterexample to the standard assumption of physicists that conservative system implies polynomial rate of convergence.

An experimental evaluation of potential scavenger effects on snake road mortality detections

Science.gov (United States)

Hubbard, Kaylan A.; Chalfoun, Anna D.

2012-01-01

As road networks expand and collisions between vehicles and wildlife become more common, accurately quantifying mortality rates for the taxa that are most impacted will be critical. Snakes are especially vulnerable to collisions with vehicles because of their physiology and behavior. Reptile road mortality is typically quantified using driving or walking surveys; however, scavengers can rapidly remove carcasses from the road and cause underestimation of mortality. Our objective was to determine the effect that scavengers might have had on our ability to accurately detect reptile road mortality during over 150 h and 4,000 km of driving surveys through arid shrublands in southwest Wyoming, which resulted in only two observations of mortality. We developed unique simulated snake carcasses out of Burbot (Lota lota), a locally invasive fish species, and examined removal rates across three different road types at three study sites. Carcass size was not a significant predictor of time of removal, and carcass removal was comparable during the daytime and nighttime hours. However, removal of simulated carcasses was higher on paved roads than unpaved or two-track roads at all study sites, with an average of 75% of the carcasses missing within 60 h compared to 34% and 31%, respectively. Scavengers may therefore negatively impact the ability of researchers to accurately detect herpetofaunal road mortality, especially for paved roads where road mortality is likely the most prevalent.

Coupled force-balance and particle-occupation rate equations for high-field electron transport

International Nuclear Information System (INIS)

Lei, X. L.

2008-01-01

It is pointed out that in the framework of balance-equation approach, the coupled force-balance and particle-occupation rate equations can be used as a complete set of equations to determine the high-field transport of semiconductors in both strong and weak electron-electron interaction limits. We call to attention that the occupation rate equation conserves the total particle number and maintains the energy balance of the relative electron system, and there is no need to introduce any other term in it. The addition of an energy-drift term in the particle-occupation rate equation [Phys. Rev. B 71, 195205 (2005)] is physically inadequate for the violation of the total particle-number conservation and the energy balance. It may lead to a substantial unphysical increase of the total particle number by the application of a dc electric field

Multiple free-radical scavenging capacity in serum

Science.gov (United States)

Oowada, Shigeru; Endo, Nobuyuki; Kameya, Hiromi; Shimmei, Masashi; Kotake, Yashige

2012-01-01

We have developed a method to determine serum scavenging-capacity profile against multiple free radical species, namely hydroxyl radical, superoxide radical, alkoxyl radical, alkylperoxyl radical, alkyl radical, and singlet oxygen. This method was applied to a cohort of chronic kidney disease patients. Each free radical species was produced with a common experimental procedure; i.e., uv/visible-light photolysis of free-radical precursor/sensitizer. The decrease in free-radical concentration by the presence of serum was quantified with electron spin resonance spin trapping method, from which the scavenging capacity was calculated. There was a significant capacity change in the disease group (n = 45) as compared with the healthy control group (n = 30). The percent values of disease’s scavenging capacity with respect to control group indicated statistically significant differences in all free-radical species except alkylperoxyl radical, i.e., hydroxyl radical, 73 ± 12% (p = 0.001); superoxide radical, 158 ± 50% (p = 0.001); alkoxyl radical, 121 ± 30% (p = 0.005); alkylperoxyl radical, 123 ± 32% (p>0.1); alkyl radical, 26 ± 14% (p = 0.001); and singlet oxygen, 57 ± 18% (p = 0.001). The scavenging capacity profile was illustrated using a radar chart, clearly demonstrating the characteristic change in the disease group. Although the cause of the scavenging capacity change by the disease state is not completely understood, the profile of multiple radical scavenging capacities may become a useful diagnostic tool. PMID:22962529

Sterile endophthalmitis rates and particle size analyses of different formulations of triamcinolone acetonide.

Science.gov (United States)

Dodwell, David G; Krimmel, Darrel A; de Fiebre, Christopher M

2015-01-01

To evaluate the rate of sterile endophthalmitis (SE) following intravitreal injection of three different formulations of triamcinolone acetonide (TA) in a single physician practice and also to assess the mean diameter and concentration of particles of the two TA formulations currently available commercially in the USA. It was hypothesized that TA formulations with smaller particles and/or greater concentrations would have a higher incidence of SE. Single-site, interventional case series in which the medical records of 392 consecutive eyes receiving intravitreal TA as Triesence(®), Kenalog(®)-40, or preservative-free TA between September 2008 and October 2013 were retrospectively reviewed for the incidence of SE. Particle sizing of TA formulations was conducted by an independent commercial laboratory. Five cases of SE were identified. The four cases of SE following Triesence(®) (4.6%) represented a rate significantly higher than the one case of SE following preservative-free TA (0.6%; P=0.049) and the 0% incidence rate of SE following Kenalog(®)-40 (P=0.0210). Triesence(®) had significantly smaller particles than Kenalog(®)-40 (P<0.0001). The rate of SE was the highest with the formulation of TA that had the smallest particle size and highest particle load (number of particles injected). The lowest rate of SE was seen with Kenalog(®)-40, the only TA formulation that contained a benzyl alcohol preservative. The data do not support a principal causative role of benzyl alcohol in the development of TA-induced SE. Instead, the data support the particle theory of TA-induced SE; however, larger-scale, multicenter studies are needed to confirm and expand on these findings.

Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates

Directory of Open Access Journals (Sweden)

C. D. O'Dowd

2007-01-01

Full Text Available A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs (50% cut from 3–5.4–9.6 nm and a nano-Scanning Mobility Particle Sizer (nSMPS and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

Indoor particle dynamics in a school office: determination of particle concentrations, deposition rates and penetration factors under naturally ventilated conditions.

Science.gov (United States)

Cong, X C; Zhao, J J; Jing, Z; Wang, Q G; Ni, P F

2018-05-09

Recently, the problem of indoor particulate matter pollution has received much attention. An increasing number of epidemiological studies show that the concentration of atmospheric particulate matter has a significant effect on human health, even at very low concentrations. Most of these investigations have relied upon outdoor particle concentrations as surrogates of human exposures. However, considering that the concentration distribution of the indoor particulate matter is largely dependent on the extent to which these particles penetrate the building and on the degree of suspension in the indoor air, human exposures to particles of outdoor origin may not be equal to outdoor particle concentration levels. Therefore, it is critical to understand the relationship between the particle concentrations found outdoors and those found in indoor micro-environments. In this study, experiments were conducted using a naturally ventilated office located in Qingdao, China. The indoor and outdoor particle concentrations were measured at the same time using an optical counter with four size ranges. The particle size distribution ranged from 0.3 to 2.5 μm, and the experimental period was from April to September, 2016. Based on the experimental data, the dynamic and mass balance model based on time was used to estimate the penetration rate and deposition rate at air exchange rates of 0.03-0.25 h -1 . The values of the penetration rate and deposition velocity of indoor particles were determined to range from 0.45 to 0.82 h -1 and 1.71 to 2.82 m/h, respectively. In addition, the particulate pollution exposure in the indoor environment was analyzed to estimate the exposure hazard from indoor particulate matter pollution, which is important for human exposure to particles and associated health effects. The conclusions from this study can serve to provide a better understanding the dynamics and behaviors of airborne particle entering into buildings. And they will also highlight

Free Radical Scavenging Properties of Annona squamosa

Science.gov (United States)

Vikas, Biba; Akhil B, S; P, Remani; Sujathan, K

2017-10-26

Annona squamosa has extensively been used in the traditional and folkloric medicine and found to possess many biological activities. Different solvents, petroleum ether, chloroform, ethyl acetate and methanol extracts of Annona squamosa seeds (ASPE, ASCH, ASEA, ASME) have been used to prepare plant extracts. The present investigations dealt with the free radical scavenging activity of four extracts using various techniques such as total reducing power estimation, total phenolic count, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging effect, evaluation of ABTS cation decolorisation capacity, FRAP assay, hdroxyl radical scavenging assay, super oxide assay and Nitric oxide radical scavenging assay of the extracts. The results showed that the four extracts of Annona squamosa showed significant reducing power in four extracts. The total phenolic contents in petroleum ether, chloroform, ethyl acetate, methanol extracts and positive control were 0.64±0.17, 0.54±0.27, 0.49±0.24, 0.57±0.22 and 0.66±0.33. The antioxidant capacity by ABTS assay of ASPE, ASCH, ASEA, ASME and positive control, trolox showed 77.75±0.5,73.25±1.7,78.5± 1.2 , 80 ± 0.8 μg/ml and 94.2 ± 0.9 respectively. The (50 % scavenging activity) SA50 of ASPE and ASCH, ASEA and ASME was found to be 34.4 μg/ml, 43.8 μg/ml 34.7 μg/m and 28.8 μg/ml respectively by DPPH assay. The percentage of hydroxyl radical scavenging increased with the increasing concentration of the extracts. ASPE, ASCH, ASEA and ASME showed superoxide radical scavenging activity, as indicated by their values 66 ± 0.5, 68 ± 1 ,63 ± 1 and 70 ± 0.5 μg/ml respectively compared to gallic acid which was 97 ± 0.5 μg/ml. The values for scavenging of nitric oxide for ASPE, ASCH, ASEA and ASME were 91.0 ± 1.0, 66.75 ± 0.5, 71.75 ± 1.1 and 75.75 ± 1.15 μg/ml while value for standard ascorbic acid was 91.0 ± 1.0 μg/ml. The results revealed strong antioxidants in four extracts may lead to the development of potent

Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

Energy Technology Data Exchange (ETDEWEB)

Dobbs, Adam James [Imperial College, London (United Kingdom)

2011-10-01

A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10.9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31.1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

Free radical scavenging window of infertile patients with polycystic ovary syndrome: correlation with embryo quality.

Science.gov (United States)

Huang, Bo; Li, Zhou; Ren, Xinling; Ai, Jihui; Zhu, Lixia; Jin, Lei

2017-06-01

The activity of free radicals in follicular fluid was related to ovarian responsiveness, in vitro fertilization (IVF), and embryo transfer success rate. However, studies analyzing the relationship between the free radical scavenging capacity and embryo quality of infertile women with polycystic ovarian syndrome (PCOS) were lacking. The aim of this study was to evaluate the relationship between the free radical scavenging window of women with PCOS and their embryo quality. The free radical scavenging capacity of follicular fluid from women with PCOS was determined by a,a-diphenyl-b-picrylhydrazyl (DPPH), 2,2-azinobis (3-ethylbenzthiazoline-6-sulphonic acid) assay, superoxide radical, and reactive oxygen species (ROS) assay. In the DPPH and ROS assays, the follicular fluid from grades I and II embryos was significantly higher than the follicular fluid from grades III and IVembryos. The lower control limit of DPPH radical scavenging capacity and upper control limit of ROS level were 13.2% and 109.0 cps, respectively. The calculated lower control limit and upper control limit were further confirmed in the follicular fluid of embryos of all grades. These cut-off values of free radical scavenging activity of follicular fluid could assist embryologists in choosing the development of embryos in PCOS patients undergoing IVF.

Invertebrates outcompete vertebrate facultative scavengers in simulated lynx kills in the Bavarian Forest National Park, Germany

Directory of Open Access Journals (Sweden)

Ray, R.–R.

2014-06-01

Full Text Available Understanding the role of scavengers in ecosystems is important for species conservation and wildlife management. We used road–killed animals, 15 in summer 2003 (June–August and nine in winter 2003/2004 (from November to January, to test the following hypotheses: (1 vertebrate scavengers such as raven (Corvus corax, red fox (Vulpes vulpes and wild boar (Sus scrofa consume a higher proportion of the carcasses than invertebrates; (2 the consumption rate is higher in winter than in summer due to the scarcity of other food resources; and (3 vertebrate scavengers are effective competitors of Eurasian lynx. We monitored 65 animals belonging to eight different mammal and bird species with camera traps. Surprisingly, Eurasian lynx (Lynx lynx was the most important vertebrate scavenger. However, in both seasons, the consumption of vertebrate scavengers was of minor impact. In summer, the carcasses were completely consumed within 10 days, mostly by invertebrates. In winter, only 5% of the carcasses were consumed within 10 days and 16% within 15 days. We conclude that vertebrates in the Bavarian Forest National Park are not strong competitors for lynx.

To scavenge or not to scavenge: that is the question

Energy Technology Data Exchange (ETDEWEB)

Nowak, Elzbieta; Brzuszkiewicz, Anna [Synchrotron Radiation Research Section, MCL, National Cancer Institute, Argonne National Laboratory, Argonne, IL 60439 (United States); Dauter, Miroslawa [SAIC-Frederick Inc., Basic Research Program, Argonne National Laboratory, Argonne, IL 60439 (United States); Dauter, Zbigniew, E-mail: dauter@anl.gov [Synchrotron Radiation Research Section, MCL, National Cancer Institute, Argonne National Laboratory, Argonne, IL 60439 (United States); Rosenbaum, Gerd, E-mail: dauter@anl.gov [Department of Biochemistry, University of Georgia, SER-CAT at the APS, Argonne, IL 60439 (United States); Synchrotron Radiation Research Section, MCL, National Cancer Institute, Argonne National Laboratory, Argonne, IL 60439 (United States)

2009-09-01

Analysis of a series of diffraction data sets measured from several native as well as nicotinic acid-soaked crystals of trypsin suggests that this potential scavenger does not have any statistically significant effect on the amount of radiation damage incurred in the crystals on X-ray irradiation at 100 K. Analysis of a series of diffraction data sets measured from four native as well as four nicotinic acid-soaked crystals of trypsin at 100 K shows a high variability in radiation-sensitivity among individual crystals for both nicotinic acid-soaked and native crystals. The level of radiation-sensitivity and the extent of its variability is statistically indistinguishable between the two conditions. This suggests that this potential scavenger does not have any statistically significant effect on the amount of radiation damage incurred in the crystals on X-ray irradiation. This is in contrast to previous results [Kauffmann et al. (2006 ▶), Structure, 14, 1099–1105] where only one crystal specimen was used for each condition (native and nicotinic acid-soaked)

Habitat of in vivo transformation influences the levels of free radical scavengers in Clinostomum complanatum: implications for free radical scavenger based vaccines against trematode infections.

Science.gov (United States)

Zafar, Atif; Rizvi, Asim; Ahmad, Irshad; Ahmad, Masood

2014-01-01

Since free radical scavengers of parasite origin like glutathione-S-transferase and superoxide dismutase are being explored as prospective vaccine targets, availability of these molecules within the parasite infecting different hosts as well as different sites of infection is of considerable importance. Using Clinostomum complanatum, as a model helminth parasite, we analysed the effects of habitat of in vivo transformation on free radical scavengers of this trematode parasite. Using three different animal models for in vivo transformation and markedly different sites of infection, progenetic metacercaria of C. complanatum were transformed to adult ovigerous worms. Whole worm homogenates were used to estimate the levels of lipid peroxidation, a marker of oxidative stress and free radical scavengers. Site of in vivo transformation was found to drastically affect the levels of free radical scavengers in this model trematode parasite. It was observed that oxygen availability at the site of infection probably influences levels of free radical scavengers in trematode parasites. This is the first report showing that habitat of in vivo transformation affects levels of free radical scavengers in trematode parasites. Since free radical scavengers are prospective vaccine targets and parasite infection at ectopic sites is common, we propose that infections at different sites, may respond differently to free radical scavenger based vaccines.

Consumption of Big Game Remains by Scavengers: A Potential Risk as Regards Disease Transmission in Central Spain

Directory of Open Access Journals (Sweden)

Ricardo Carrasco-Garcia

2018-03-01

Full Text Available Understanding the role that facultative scavenger species may play in spreading infectious pathogens, and even becoming reservoirs for humans, domestic and wild ungulates or, on the contrary, preventing the spread of disease, requires a prior understanding of the pattern of carrion scavenging in specific scenarios. The objectives of this paper are (i to describe the guild of vertebrate scavengers and (ii to study the species-specific, habitat, and management-related factors involved in the usage of gut piles in South Central Spain (SCS, a tuberculosis (TB endemic area. We used camera trapping at 18 hunting piles on seven hunting estates. A total of eight bird and five mammal taxa were detected at the remains of hunting piles. The most frequently detected species in terms of number of gut piles visited (78% and scavenged (61% was the red fox Vulpes vulpes, followed by the griffon vulture Gyps fulvus (56% as regards both presence and scavenging and the raven Corvus corax (61 and 39% as regards presence and scavenging, respectively. We evidenced that griffon vultures accounted for most of the scavenging activity in open habitats, while facultative mammal scavengers, red fox, and wild boar Sus scrofa made the highest contribution to scavenging in vegetation-covered habitats. In the case of wild boar, the gut piles deposited during the evening and night favored higher rates of scavenging, while the opposite pattern was observed for griffons. Overall, our findings suggest that when disposing of hunting remains in areas of risk as regards disease transmission it is particularly important to consider the access that facultative mammals, and especially wild boar, have to material, while the presence of the resource needs to be safeguarded to protect specialist scavengers of conservation value. These results are of particular relevance in the case of wild boar in the current context of re-emerging TB and emerging African swine fever (ASF in Europe.

Observation of advanced particle removal rates in pump limiter simulation experiments

International Nuclear Information System (INIS)

Goebel, D.M.; Conn, R.W.

1984-05-01

The performance of particle removal schemes for density and impurity control in tokamaks and mirror machines depends strongly on the plasma parameters and local recycling near the plasma neutralizier plates and gas pumping ducts. The relationship between plasma density, electron temperature, ion energy and gas flow and particle removal rate through a pumping duct located near a plasma neutralizer plate has been experimentally investigated in the steady state plasma device PISCES. Results indicate that initially the particle removal by pumps at the end of the duct is proportional to the plasma flux to the plate. A nonlinear increase in the pumping rate occurs when the ionization mean free path for neutrals from the plate becomes less than the plasma radius. The transition from a transparent to an opaque plasma due to local ionization of the neutrals produced at the neutralizer plate greatly enhances the particle removal rate by recycling of the neutral gas as it flows away from the neutralizer plate or out of the pumping ducts. Parameters were varied to determine the importance of ballistic scattering of higher energy ions from the plate, but no effects were found in these experiments

Microphysical processing of aerosol particles in orographic clouds

Science.gov (United States)

Pousse-Nottelmann, S.; Zubler, E. M.; Lohmann, U.

2015-08-01

An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener-Bergeron-Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases

Phytochemical Analysis and Free Radical Scavenging Activity of Medicinal Plants Gnidia glauca and Dioscorea bulbifera

Science.gov (United States)

Ghosh, Sougata; Derle, Abhishek; Ahire, Mehul; More, Piyush; Jagtap, Soham; Phadatare, Suvarna D.; Patil, Ajay B.; Jabgunde, Amit M.; Sharma, Geeta K.; Shinde, Vaishali S.; Pardesi, Karishma; Dhavale, Dilip D.; Chopade, Balu A.

2013-01-01

Gnidia glauca and Dioscorea bulbifera are traditional medicinal plants that can be considered as sources of natural antioxidants. Herein we report the phytochemical analysis and free radical scavenging activity of their sequential extracts. Phenolic and flavonoid content were determined. Scavenging activity was checked against pulse radiolysis generated ABTS•+ and OH radical, in addition to DPPH, superoxide and hydroxyl radicals by biochemical methods followed by principal component analysis. G. glauca leaf extracts were rich in phenolic and flavonoid content. Ethyl acetate extract of D. bulbifera bulbs and methanol extract of G. glauca stem exhibited excellent scavenging of pulse radiolysis generated ABTS•+ radical with a second order rate constant of 2.33×106 and 1.72×106, respectively. Similarly, methanol extract of G. glauca flower and ethyl acetate extract of D. bulbifera bulb with second order rate constants of 4.48×106 and 4.46×106 were found to be potent scavengers of pulse radiolysis generated OH radical. G. glauca leaf and stem showed excellent reducing activity and free radical scavenging activity. HPTLC fingerprinting, carried out in mobile phase, chloroform: toluene: ethanol (4: 4: 1, v/v) showed presence of florescent compound at 366 nm as well as UV active compound at 254 nm. GC-TOF-MS analysis revealed the predominance of diphenyl sulfone as major compound in G. glauca. Significant levels of n-hexadecanoic acid and octadecanoic acid were also present. Diosgenin (C27H42O3) and diosgenin (3á,25R) acetate were present as major phytoconstituents in the extracts of D. bulbifera. G. glauca and D. bulbifera contain significant amounts of phytochemicals with antioxidative properties that can be exploited as a potential source for herbal remedy for oxidative stress induced diseases. These results rationalize further investigation in the potential discovery of new natural bioactive principles from these two important medicinal plants. PMID:24367520

Protection against inhaled oxidants through scavenging of oxidized lipids by macrophage receptors MARCO and SR-AI/II

DEFF Research Database (Denmark)

Dahl, Morten; Bauer, Alison K; Arredouani, Mohamed

2007-01-01

Alveolar macrophages (AMs) express the class A scavenger receptors (SRAs) macrophage receptor with collagenous structure (MARCO) and scavenger receptor AI/II (SRA-I/II), which recognize oxidized lipids and provide innate defense against inhaled pathogens and particles. Increased MARCO expression...... in lungs of ozone-resistant mice suggested an additional role protecting against inhaled oxidants. After ozone exposure, MARCO-/- mice showed greater lung injury than did MARCO+/+ mice. Ozone is known to generate oxidized, proinflammatory lipids in lung lining fluid, such as 5beta,6beta......-epoxycholesterol (beta-epoxide) and 1-palmitoyl-2-(9'-oxo-nonanoyl)-glycerophosphocholine (PON-GPC). Intratracheal instillation of either lipid caused substantial neutrophil influx in MARCO-/- mice, but had no effect in MARCO+/+ mice. Normal AMs showed greater uptake in vitro of beta-epoxide compared with MARCO-/- AMs...

Free Radical Scavenging Activities of Methanol Extract and ...

African Journals Online (AJOL)

Michael Horsfall

fractions were subjected to in vitro antioxidant evaluation using the DPPH free radical scavenging ... The crude extract has IC-50 value for radical scavenging activity of 5μg/mL which was .... effective concentration of the sample that is required.

Synergistic radical scavenging potency of curcumin-in-β-cyclodextrin-in-nanomagnetoliposomes

Energy Technology Data Exchange (ETDEWEB)

Aadinath, W.; Bhushani, Anu; Anandharamakrishnan, C., E-mail: anandhram@cftri.res.in

2016-07-01

Curcumin is a highly potent nutraceutical associated with various health benefits. However, its hydrophobic nature affects its bioavailability and bioactivity, and limits nutraceutical applications. Drug-in-cyclodextrin-in-liposome has the ability to mask the hydrophobic nature of drug and achieve better encapsulation. Also, encapsulating iron oxide nanoparticles (IONPs) within liposomes endow additional beneficial functionalities of IONPs. In the present study, curcumin-β-cyclodextrin inclusion complex (IC) and IONPs were co-encapsulated within liposomes (curcumin-in-β-cyclodextrin-in-nanomagnetoliposomes) to achieve the synergistic antioxidant potential of curcumin and IONPs. IC of curcumin-β-cyclodextrin was prepared by a simple rapid method and successful inclusion was confirmed by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). Mean diameter of IONPs was found to be 180 nm and X-ray diffraction pattern confirmed the formation of hematite nanoparticles. Band gap energy calculated using absorption spectra was 2.25 eV, which falls in close proximity with the theoretically calculated values of hematite. Mean diameter of curcumin-in-β-cyclodextrin-in-nanomagnetoliposomes was 67 nm and encapsulation efficiency of curcumin was found to be 71%. Further, the co-encapsulated particles possessed significantly low IC{sub 50} value (64.7791 μg/ml, p < 0.01) compared to conventional curcumin liposome and IONPs, indicating its synergistically enhanced radical scavenging property. - Highlights: • Curcumin-in-β-cyclodextrin-in-nanomagnetoliposomes (mean diameter, 67 nm) has been prepared. • Encapsulation efficiency of curcumin was found to be 71%. • IONPs in the nano-carrier play dual role of targeted delivery and radical scavenging activities. • Conjunction of IONPs and curcumin into the liposomes increases the radical scavenging activity.

Free radical scavenging injectable hydrogels for regenerative therapy

Energy Technology Data Exchange (ETDEWEB)

Komeri, Remya [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India); Thankam, Finosh Gnanaprakasam [Dept. of Biomedical Sciences, Creighton University, 2500 California Plaza, Omaha NE68178 (United States); Muthu, Jayabalan, E-mail: mjayabalan52@gmail.com [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Polymer Science Division, BMT Wing, Thiruvananthapuram 695 012, Kerala State (India)

2017-02-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

Free radical scavenging injectable hydrogels for regenerative therapy

International Nuclear Information System (INIS)

Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2017-01-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07 kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. - Graphical abstract: Injectable hydrogel with inherent free radical scavenging property for regenerative tissue engineering application. - Highlights: • Novel injectable hydrogel (PEAX-P) is prepared using D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer

Test Method for High β Particle Emission Rate of 63Ni Source Plate

OpenAIRE

ZHANG Li-feng

2015-01-01

For the problem of measurement difficulties of β particle emission rate of Ni-63 source plate used for Ni-63 betavoltaic battery, a relative test method of scintillation current method was erected according to the measurement principle of scintillation detector.β particle emission rate of homemade Ni-63 source plate was tested by the method, and the test results were analysed and evaluated, it was initially thought that scintillation current method was a feasible way of testing β particle emi...

An illicit economy: scavenging and recycling of medical waste.

Science.gov (United States)

Patwary, Masum A; O'Hare, William Thomas; Sarker, M H

2011-11-01

This paper discusses a significant illicit economy, including black and grey aspects, associated with medical waste scavenging and recycling in a megacity, considering hazards to the specific group involved in scavenging as well as hazards to the general population of city dwellers. Data were collected in Dhaka, Bangladesh, using a variety of techniques based on formal representative sampling for fixed populations (such as recycling operatives) and adaptive sampling for roaming populations (such as scavengers). Extremely hazardous items (including date expired medicines, used syringes, knives, blades and saline bags) were scavenged, repackaged and resold to the community. Some HCE employees were also observed to sell hazardous items directly to scavengers, and both employees and scavengers were observed to supply contaminated items to an informal plastics recycling industry. This trade was made possible by the absence of segregation, secure storage and proper disposal of medical waste. Corruption, a lack of accountability and individual responsibility were also found to be contributors. In most cases the individuals involved with these activities did not understand the risks. Although motivation was often for personal gain or in support of substance abuse, participants sometimes felt that they were providing a useful service to the community. Copyright © 2011 Elsevier Ltd. All rights reserved.

An improved criterion for new particle formation in diverse atmospheric environments

Directory of Open Access Journals (Sweden)

C. Kuang

2010-09-01

Full Text Available A dimensionless theory for new particle formation (NPF was developed, using an aerosol population balance model incorporating recent developments in nucleation rates and measured particle growth rates. Based on this theoretical analysis, it was shown that a dimensionless parameter L_Γ, characterizing the ratio of the particle scavenging loss rate to the particle growth rate, exclusively determined whether or not NPF would occur on a particular day. This parameter determines the probability that a nucleated particle will grow to a detectable size before being lost by coagulation with the pre-existing aerosol. Cluster-cluster coagulation was shown to contribute negligibly to this survival probability under conditions pertinent to the atmosphere. Data acquired during intensive measurement campaigns in Tecamac (MILAGRO, Atlanta (ANARChE, Boulder, and Hyytiälä (QUEST II, QUEST IV, and EUCAARI were used to test the validity of L_Γ as an NPF criterion. Measurements included aerosol size distributions down to 3 nm and gas-phase sulfuric acid concentrations. The model was applied to seventy-seven NPF events and nineteen non-events (characterized by growth of pre-existing aerosol without NPF measured in diverse environments with broad ranges in sulfuric acid concentrations, ultrafine number concentrations, aerosol surface areas, and particle growth rates (nearly two orders of magnitude. Across this diverse data set, a nominal value of L_Γ=0.7 was found to determine the boundary for the occurrence of NPF, with NPF occurring when L_Γ<0.7 and being suppressed when L_Γ>0.7. Moreover, nearly 45% of measured L_Γ values associated with NPF fell in the relatively narrow range of 0.1<L_Γ<0.3.

Determination of reactivity rates of silicate particle-size fractions

Directory of Open Access Journals (Sweden)

Angélica Cristina Fernandes Deus

2014-04-01

Full Text Available The efficiency of sources used for soil acidity correction depends on reactivity rate (RR and neutralization power (NP, indicated by effective calcium carbonate (ECC. Few studies establish relative efficiency of reactivity (RER for silicate particle-size fractions, therefore, the RER applied for lime are used. This study aimed to evaluate the reactivity of silicate materials affected by particle size throughout incubation periods in comparison to lime, and to calculate the RER for silicate particle-size fractions. Six correction sources were evaluated: three slags from distinct origins, dolomitic and calcitic lime separated into four particle-size fractions (2, 0.84, 0.30 and <0.30-mm sieves, and wollastonite, as an additional treatment. The treatments were applied to three soils with different texture classes. The dose of neutralizing material (calcium and magnesium oxides was applied at equal quantities, and the only variation was the particle-size material. After a 90-day incubation period, the RER was calculated for each particle-size fraction, as well as the RR and ECC of each source. The neutralization of soil acidity of the same particle-size fraction for different sources showed distinct solubility and a distinct reaction between silicates and lime. The RER for slag were higher than the limits established by Brazilian legislation, indicating that the method used for limes should not be used for the slags studied here.

Particle-size effect on the rate of TiO2 carbonizing

International Nuclear Information System (INIS)

Lekanova, T.L.; Ryabkov, Yu.I.; Sevbo, O.A.

2003-01-01

Dependence of recovery rate constant of titanium dioxide in TiO 2 -C system on the value of specific surface initial components at 1300 deg C was studied. It is shown that decrease in equivalent particle size of titanium dioxide and carbon particles in the range of 500-100 μm has a similar effect on increase in titanium dioxide recovery rate. Analysis of kinetic equations suggests diffusion character of titanium dioxide carbonizing at the values of initial components specific surface in excess of 100 m 2 /g [ru

Effects of vulture exclusion on carrion consumption by facultative scavengers.

Science.gov (United States)

Hill, Jacob E; DeVault, Travis L; Beasley, James C; Rhodes, Olin E; Belant, Jerrold L

2018-03-01

Vultures provide an essential ecosystem service through removal of carrion, but globally, many populations are collapsing and several species are threatened with extinction. Widespread declines in vulture populations could increase the availability of carrion to other organisms, but the ways facultative scavengers might respond to this increase have not been thoroughly explored. We aimed to determine whether facultative scavengers increase carrion consumption in the absence of vulture competition and whether they are capable of functionally replacing vultures in the removal of carrion biomass from the landscape. We experimentally excluded 65 rabbit carcasses from vultures during daylight hours and placed an additional 65 carcasses that were accessible to vultures in forested habitat in South Carolina, USA during summer (June-August). We used motion-activated cameras to compare carrion use by facultative scavenging species between the experimental and control carcasses. Scavenging by facultative scavengers did not increase in the absence of competition with vultures. We found no difference in scavenger presence between control carcasses and those from which vultures were excluded. Eighty percent of carcasses from which vultures were excluded were not scavenged by vertebrates, compared to 5% of carcasses that were accessible to vultures. At the end of the 7-day trials, there was a 10.1-fold increase in the number of experimental carcasses that were not fully scavenged compared to controls. Facultative scavengers did not functionally replace vultures during summer in our study. This finding may have been influenced by the time of the year in which the study took place, the duration of the trials, and the spacing of carcass sites. Our results suggest that under the warm and humid conditions of our study, facultative scavengers would not compensate for loss of vultures. Carcasses would persist longer in the environment and consumption of carrion would likely shift from

Charged-particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, Cornelia; Angulo, C.; Arnould, M.

2000-01-01

The rapidly growing wealth of nuclear data becomes less and less easily accessible to the astrophysics community. Mastering this volume of information and making it available in an accurate and usable form for incorporation into stellar evolution or nucleosynthesis models become urgent goals of prime necessity. we report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal motivation for the setting-up of the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged-particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. When cross section data are not available in the whole needed range of energies, the theoretical predictions obtained in the framework of the Hauser-Feshbach model is used. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. Reverse reaction rates and analytical approximations of the adopted rates are also provided. (authors)

Charged-particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, Cornelia

1999-01-01

The rapidly growing wealth of nuclear data becomes less and less easily accessible to the astrophysics community. Mastering this volume of information and making it available in an accurate and usable form for incorporation into stellar evolution or nucleosynthesis models become urgent goals of prime necessity. We report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal motivation for the setting-up of the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged -particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. When cross section data are not available in the whole needed range of energies the theoretical predictions obtained in the framework of the Hauser-Feshbach model are used. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. Reverse reaction rates and analytical approximations of the adopted rates are also provided. (author)

Single Particle Laser Mass Spectrometry Applied to Differential Ice Nucleation Experiments at the AIDA Chamber

International Nuclear Information System (INIS)

Gallavardin, S. J.; Froyd, Karl D.; Lohmann, U.; Moehler, Ottmar; Murphy, Daniel M.; Cziczo, Dan

2008-01-01

Experiments conducted at the Aerosol Interactions and Dynamics in the Atmosphere (AIDA) chamber located in Karlsruhe, Germany permit investigation of particle properties that affect the nucleation of ice at temperature and water vapor conditions relevant to cloud microphysics and climate issues. Ice clouds were generated by heterogeneous nucleation of Arizona test dust (ATD), illite, and hematite and homogeneous nucleation of sulfuric acid. Ice crystals formed in the chamber were inertially separated from unactivated, or 'interstitial' aerosol particles with a pumped counterflow virtual impactor (PCVI), then evaporated. The ice residue (i.e., the aerosol which initiated ice nucleation plus any material which was scavenged from the gas- and/or particle-phase), was chemically characterized at the single particle level using a laser ionization mass spectrometer. In this manner the species that first nucleated ice could be identified out of a mixed aerosol population in the chamber. Bare mineral dust particles were more effective ice nuclei (IN) than similar particles with a coating. Metallic particles from contamination in the chamber initiated ice nucleation before other species but there were few enough that they did not compromise the experiments. Nitrate, sulfate, and organics were often detected on particles and ice residue, evidently from scavenging of trace gas-phase species in the chamber. Hematite was a more effective ice nucleus than illite. Ice residue was frequently larger than unactivated test aerosol due to the formation of aggregates due to scavenging, condensation of contaminant gases, and the predominance of larger aerosol in nucleation

Characterization and DPPH Radical Scavenging Activity of Gallic ...

African Journals Online (AJOL)

Characterization and DPPH Radical Scavenging Activity of Gallic Acid-Lecithin Complex. C Liu, C Chen, H Ma, E Yuan, Q Li. Abstract. Purpose: To investigate the physicochemical properties and DPPH radical scavenging activity of gallic acid–lecithin complex. Methods: The complex of gallic acid with lecithin was prepared ...

Theoretical Evaluation of the Escape Rate of Charged Particles Trapped in a Potential Energy Well

International Nuclear Information System (INIS)

Chang Yongbin; Ordonez, C.A.

2003-01-01

In various types of charged particle sources and traps, charged particles are temporarily trapped within a potential energy well. In the work reported, a theoretical evaluation of the escape rate of trapped charged particles is carried out. As a specific example, the loss rate is evaluated for trapped plasma particles that are undergoing both collisions among themselves and collisions with particles of a different plasma species having a different temperature. Conditions are considered in which both species are confined within a nested Penning trap

Particle deposition from aqueous suspensions in turbulent pipe flow - a comparison of observed deposition rates and predicted arrival rates

International Nuclear Information System (INIS)

Rodliffe, R.S.

1979-11-01

At the present time, there appear to be only four adequately controlled and characterised experimental studies of particle deposition from single phase water in turbulent pipe flow. These are used to illustrate the ranges of applicability of methods for predicting particle arrival rates at tube walls. Arrival rates are predicted from mass transfer correlations and the theory of Reeks and Skyrme (1976) when transport is limited by Brownian diffusion and inertial behaviour, respectively. The regimes in which finite particle size limits the application of these methods are defined and preliminary consideration is given to the conditions under which gravitational settling may make a contribution to deposition in vertically mounted tubes. (author)

Charged particle induced thermonuclear reaction rates: a compilation for astrophysics

International Nuclear Information System (INIS)

Grama, C.

1999-01-01

We report on the results of the European network NACRE (Nuclear Astrophysics Compilation of REaction rates). The principal reason for setting up the NACRE network has been the necessity of building up a well-documented and detailed compilation of rates for charged-particle induced reactions on stable targets up to Si and on unstable nuclei of special significance in astrophysics. This work is meant to supersede the only existing compilation of reaction rates issued by Fowler and collaborators. The main goal of NACRE network was the transparency in the procedure of calculating the rates. More specifically this compilation aims at: 1. updating the experimental and theoretical data; 2. distinctly identifying the sources of the data used in rate calculation; 3. evaluating the uncertainties and errors; 4. providing numerically integrated reaction rates; 5. providing reverse reaction rates and analytical approximations of the adopted rates. The cross section data and/or resonance parameters for a total of 86 charged-particle induced reactions are given and the corresponding reaction rates are calculated and given in tabular form. Uncertainties are analyzed and realistic upper and lower bounds of the rates are determined. The compilation is concerned with the reaction rates that are large enough for the target lifetimes shorter than the age of the Universe, taken equal to 15 x 10 9 y. The reaction rates are provided for temperatures lower than T = 10 10 K. In parallel with the rate compilation a cross section data base has been created and located at the site http://pntpm.ulb.ac.be/nacre..htm. (authors)

Radical scavenging propensity of Cu2 +, Fe3 + complexes of flavonoids and in-vivo radical scavenging by Fe3 +-primuletin

Science.gov (United States)

Jabeen, Erum; Janjua, Naveed Kausar; Ahmed, Safeer; Murtaza, Iram; Ali, Tahir; Hameed, Shahid

2017-01-01

Cu2 + and Fe3 + complexes of three flavonoids (morin or mo, quercetin or quer and primuletin or prim) were synthesized with the objective of improving antioxidant capacities of flavonoids. The radical scavenging activities of pure flavonoids and their metal complexes were assayed to monitor their tendencies towards sequestering of radicals at physiological conditions. The scavenger potencies of metal-flavonoid complexes were significantly higher than those of the parent flavonoids. Further, influence of the solvent polarity on the radical capturing by flavonoids and their metal complexes was in favor for the polar solvent. Fe3 +-prim displayed its radical scavenging ability via up gradation of CAT and SOD activities in in-vivo antioxidant assays.

Integrated Analysis of the Scavenging Process in Marine Two-Stroke Diesel Engines

DEFF Research Database (Denmark)

Andersen, Fredrik Herland

Large commercial ships such as container vessels and bulk carriers are propelledby low-speed, uniow scavenged two-stroke diesel engines. An integralin-cylinder process in this type of engine is the scavenging process, where the burned gases from the combustion process are evacuated through...... receiver fora two-stroke diesel engine. Time resolved boundary conditions corresponding to measurements obtained from an operating engine as well as realistic initial conditions are used in the simulations. The CFD model provides a detailed description of the in-cylinder ow from exhaust valve opening (EVO...... in the scavenge and exhaust receivers increase while the scavenge port exposure time, tscav, decrease. Further the scavenging pressure is varied while the engine speed is kept constant. From the perspective of the scavenging process this will resemble a load sweep following a generator curve. The scavenge port...

The effect of mixing rates on the formation and growth of condensation aerosols in a model stagnation flow

KAUST Repository

Alshaarawi, Amjad; Bisetti, Fabrizio

2015-01-01

A steady, laminar stagnation flow configuration is adopted to investigate numerically the interaction between condensing aerosol particles and gas-phase transport across a canonical mixing layer. The mixing rates are varied by adjusting the velocity and length scales of the stagnation flow parametrically. The effect of mixing rates on particle concentration, polydispersity, and mean droplet diameter is explored and discussed. This numerical study reveals a complex response of the aerosol to varying flow times. Depending on the flow time, the variation of the particle concentration in response to varying mixing rates falls into one of the two regimes. For fast mixing rates, the number density and volume fraction of the condensing particles increase with residence time (nucleation regime). On the contrary, for low mixing rates, number density decreases with residence time and volume fraction reaches a plateau (condensation regime). It is shown that vapor scavenging by the aerosol phase is key to explaining the transition between these two regimes. The results reported here are general and illustrate genuine features of the evolution of aerosols forming by condensation of supersaturated vapor from heat and mass transport across mixing layers.

The effect of mixing rates on the formation and growth of condensation aerosols in a model stagnation flow

KAUST Repository

Alshaarawi, Amjad

2015-03-01

A steady, laminar stagnation flow configuration is adopted to investigate numerically the interaction between condensing aerosol particles and gas-phase transport across a canonical mixing layer. The mixing rates are varied by adjusting the velocity and length scales of the stagnation flow parametrically. The effect of mixing rates on particle concentration, polydispersity, and mean droplet diameter is explored and discussed. This numerical study reveals a complex response of the aerosol to varying flow times. Depending on the flow time, the variation of the particle concentration in response to varying mixing rates falls into one of the two regimes. For fast mixing rates, the number density and volume fraction of the condensing particles increase with residence time (nucleation regime). On the contrary, for low mixing rates, number density decreases with residence time and volume fraction reaches a plateau (condensation regime). It is shown that vapor scavenging by the aerosol phase is key to explaining the transition between these two regimes. The results reported here are general and illustrate genuine features of the evolution of aerosols forming by condensation of supersaturated vapor from heat and mass transport across mixing layers.

Free Radical Scavenging and Cellular Antioxidant Properties of Astaxanthin.

Science.gov (United States)

Dose, Janina; Matsugo, Seiichi; Yokokawa, Haruka; Koshida, Yutaro; Okazaki, Shigetoshi; Seidel, Ulrike; Eggersdorfer, Manfred; Rimbach, Gerald; Esatbeyoglu, Tuba

2016-01-14

Astaxanthin is a coloring agent which is used as a feed additive in aquaculture nutrition. Recently, potential health benefits of astaxanthin have been discussed which may be partly related to its free radical scavenging and antioxidant properties. Our electron spin resonance (ESR) and spin trapping data suggest that synthetic astaxanthin is a potent free radical scavenger in terms of diphenylpicryl-hydrazyl (DPPH) and galvinoxyl free radicals. Furthermore, astaxanthin dose-dependently quenched singlet oxygen as determined by photon counting. In addition to free radical scavenging and singlet oxygen quenching properties, astaxanthin induced the antioxidant enzyme paroxoanase-1, enhanced glutathione concentrations and prevented lipid peroxidation in cultured hepatocytes. Present results suggest that, beyond its coloring properties, synthetic astaxanthin exhibits free radical scavenging, singlet oxygen quenching, and antioxidant activities which could probably positively affect animal and human health.

Scavenger Receptor Class B Type I Mediates Biliary Cholesterol Secretion Independent of ATP-Binding Cassette Transporter g5/g8 in Mice

NARCIS (Netherlands)

Wiersma, Harmen; Gatti, Alberto; Nijstad, Niels; Elferink, Ronald P. J. Oude; Kuipers, Folkert; Tietge, Uwe J. F.

2009-01-01

Scavenger receptor class B type I (SR-BI) mediates selective uptake of cholesterol from high-density lipoprotein (HDL) particles by the liver and influences biliary cholesterol secretion. However, it is not dear, if this effect is direct or indirect. The aim of this study was to determine the impact

Radical Scavenging Efficacy of Thiol Capped Silver Nanoparticles

Indian Academy of Sciences (India)

aSchool of Studies in Chemistry, Pt. Ravishankar Shukla University, Raipur 492 010, India. bDepartment of ... of nanosilver in foods, health care and consumer products as antimi- ... of the radical scavenging behavior of thiolated antiox- idants (alone) and ..... case of GSH@AgNPs; DPPH scavenging activity was found to be ...

The fate of particle-reactive radionuclides on the Amazon and Yangtze continental shelves

International Nuclear Information System (INIS)

McKee, B.A.

1986-01-01

Water column and seabed samples collected from the continental shelves adjacent to the Yangtze and Amazon Rivers were analyzed for particle-reactive radionuclides ( 234 Th, 228 Th, 210 Pb), and their respective parent nuclides ( 238 U, 228 Ra, 226 Ra). On the Amazon shelf, dissolved 238 U activities increase with increasing salinity to a shelf maximum (4.6 dpm 1 -1 ) that is much higher than the open-ocean value (2.5 dpm 1 -1 ) because uranium is desorbed from the ferric-oxyhydroxide coatings of bottom sediments and advected into the overlying water column during periodic resuspension events. As a result, measurement of only the riverine flux of dissolved 238 U underestimates (by a factor of 5) the flux of dissolved uranium from the Amazon shelf to the open ocean. K e values decrease with increased SSC and range from 10 5 ·10 6 ml g -1 for Th and from 10 4 ·10 6 ml g -1 for Po and Pb. The approach to equilibrium can best be described as a two-step process that is initially rapid (rate constants: 10-100 d -1 , during the first 30 minutes), but becomes less rapid (rate constants: 1-4 d -1 ) as equilibrium is attained. Distribution coefficients for 234 Th, 228 Th and 210 Pb exhibit large spatial variability on the Amazon shelf (range: 10 3 - 10 6 ml g -1 ) and on the Yangtze shelf (range: 10 4 - 10 6 ml g -1 ). On the Amazon shelf, particle residence time is short (2-3 hours) relative to scavenging residence time (15-20 hours) therefore, only 1-31% of equilibrium between dissolved and particulate thorium is attained. On the Yangtze shelf, particle residence time is long (12-89 hours) relative to scavenging time (2-23 hours) resulting in K d values near (97-100%) equilibrium

Implication of scavenger receptors in the interactions between diesel exhaust particles and immature or mature dendritic cells

Directory of Open Access Journals (Sweden)

Lassalle Philippe

2009-03-01

Full Text Available Abstract Background The exposure to pollutants such as diesel exhaust particles (DEP is associated with an increased incidence of respiratory diseases. However, the mechanisms by which DEP have an effect on human health are not completely understood. In addition to their action on macrophages and airway epithelial cells, DEP also modulate the functions of dendritic cells (DC. These professional antigen-presenting cells are able to discriminate unmodified self from non-self thanks to pattern recognition receptors such as the Toll like Receptors (TLR and Scavenger Receptors (SR. SR were originally identified by their ability to bind and internalize modified lipoproteins and microorganisms but also particles and TLR agonists. In this study, we assessed the implication of SR in the effects of DEP associated or not with TLR agonists on monocyte-derived DC (MDDC. For this, we studied the regulation of CD36, CXCL16, LOX-1, SR-A1 and SR-B1 expression on MDDC treated with DEP associated or not with TLR2, 3 and 4 ligands. Then, the capacity of SR ligands (dextran sulfate and maleylated-ovalbumin to block the effects of DEP on the function of lipopolysaccharide (LPS-activated DC has been evaluated. Results Our data demonstrate that TLR2 agonists mainly augmented CXCL16, LOX-1 and SR-B1 expression whereas DEP alone had only a weak effect. Interestingly, DEP modulated the action of TLR2 and TLR4 ligands on the expression of LOX-1 and SR-B1. Pretreatment with the SR ligand maleylated-ovalbumin but not dextran sulfate inhibited the endocytosis of DEP by MDDC. Moreover, this SR ligand blocked the effect by DEP at low dose (1 μg/ml on MDDC phenotype (a decrease of CD86 and HLA-DR expression and on the secretion of CXCL10, IL-12 and TNF-α. In contrast, the decrease of IL-12 and CXCL10 secretion and the generation of oxygen metabolite induced by DEP at 10 μg/ml was not affected by SR ligands Conclusion Our results show for the first time that the modulation of

Effect of Particle Size on Mechanical Properties of Sawdust-High Density Polyethylene Composites under Various Strain Rates

Directory of Open Access Journals (Sweden)

Haliza Jaya

2016-06-01

Full Text Available There is a need to understand the effect of wood particle size, as it affects the characteristics of wood-based composites. This study considers the effect of wood particle size relative to the dynamic behavior of wood composites. The compression Split Hopkinson Pressure Bar (SHPB was introduced to execute dynamic compression testing at the strain rate of 650 s-1, 900 s-1, and 1100 s-1, whereas a conventional universal testing machine (UTM was used to perform static compression testing at the strain rate of 0.1 s-1, 0.01 s-1, and 0.001 s-1 for four different particle sizes (63 µm, 125 µm, 250 µm, and 500 µm. The results showed that mechanical properties of composites were positively affected by the particle sizes, where the smallest particle size gave the highest values compared to the others. Moreover, the particle size also affected the rate sensitivity and the thermal activation volume of sawdust/HDPE, where smaller particles resulted in lower rate sensitivity. For the post-damage analysis, the applied strain rates influenced deformation behavior differently for all particle sizes of the specimens. In a fractographic analysis under dynamic loading, the composites with large particles experienced severe catastrophic deformation and damages compared to the smaller particles.

Effects of P25 TiO2 Nanoparticles on the Free Radical-Scavenging Ability of Antioxidants upon Their Exposure to Simulated Sunlight.

Science.gov (United States)

Li, Meng; Chong, Yu; Fu, Peter P; Xia, Qingsu; Croley, Timothy R; Lo, Y Martin; Yin, Jun-Jie

2017-11-15

Although nanosized ingredients, including TiO 2 nanoparticles (NPs), can be found in a wide range of consumer products, little is known about the effects these particles have on other active compounds in product matrices. These NPs can interact with reactive oxygen species (ROS), potentially disrupting or canceling the benefits expected from antioxidants. We used electron spin resonance spectrometry to assess changes in the antioxidant capacities of six dietary antioxidants (ascorbic acid, α-tocopherol, glutathione, cysteine, epicatechin, and epicatechin gallate) during exposure to P25 TiO 2 and/or simulated sunlight. Specifically, we determined the ability of these antioxidants to scavenge 1-diphenyl-2-picryl-hydrazyl radical, superoxide radical, and hydroxyl radical. Exposure to simulated sunlight alone did not lead to noticeable changes in radical-scavenging abilities; however, in combination with P25 TiO 2 NPs, the scavenging abilities of most antioxidants were weakened. We found glutathione to be the most resistant to treatment with sunlight and NPs among these six antioxidants.

Synthesis and Free Radical Scavenging Activity of New Hydroxybenzylidene Hydrazines.

Science.gov (United States)

Sersen, Frantisek; Gregan, Fridrich; Kotora, Peter; Kmetova, Jarmila; Filo, Juraj; Loos, Dusan; Gregan, Juraj

2017-05-29

Hydroxybenzylidene hydrazines exhibit a wide spectrum of biological activities. Here, we report synthesis and free radical scavenging activity of nine new N-(hydroxybenzylidene)-N'-[2,6-dinitro-4-(trifluoromethyl)]phenylhydrazines. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR, 19F-NMR, IR spectroscopy, LC-MS, and elemental analysis. The prepared compounds were tested for their activity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH), galvinoxyl radical (GOR), and 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulphonic acid (ABTS) radicals. The free radical scavenging activity expressed as SC50 values of these compounds varied in a wide range, from a strong to no radical scavenging effect. The most effective radical scavengers were hydroxybenzylidene hydrazines containing three hydroxyl groups in the benzylidene part of their molecules. The prepared compounds were also tested for their activity to inhibit photosynthetic electron transport in spinach chloroplasts. IC50 values of these compounds varied in wide range, from an intermediate to no inhibitory effect.

Invasive carnivores alter ecological function and enhance complementarity in scavenger assemblages on ocean beaches.

Science.gov (United States)

Brown, Marion B; Schlacher, Thomas A; Schoeman, David S; Weston, Michael A; Huijbers, Chantal M; Olds, Andrew D; Connolly, Rod M

2015-10-01

Species composition is expected to alter ecological function in assemblages if species traits differ strongly. Such effects are often large and persistent for nonnative carnivores invading islands. Alternatively, high similarity in traits within assemblages creates a degree of functional redundancy in ecosystems. Here we tested whether species turnover results in functional ecological equivalence or complementarity, and whether invasive carnivores on islands significantly alter such ecological function. The model system consisted of vertebrate scavengers (dominated by raptors) foraging on animal carcasses on ocean beaches on two Australian islands, one with and one without invasive red foxes (Vulpes vulpes). Partitioning of scavenging events among species, carcass removal rates, and detection speeds were quantified using camera traps baited with fish carcasses at the dune-beach interface. Complete segregation of temporal foraging niches between mammals (nocturnal) and birds (diurnal) reflects complementarity in carrion utilization. Conversely, functional redundancy exists within the bird guild where several species of raptors dominate carrion removal in a broadly similar way. As predicted, effects of red foxes were large. They substantially changed the nature and rate of the scavenging process in the system: (1) foxes consumed over half (55%) of all carrion available at night, compared with negligible mammalian foraging at night on the fox-free island, and (2) significant shifts in the composition of the scavenger assemblages consuming beach-cast carrion are the consequence of fox invasion at one island. Arguably, in the absence of other mammalian apex predators, the addition of red foxes creates a new dimension of functional complementarity in beach food webs. However, this functional complementarity added by foxes is neither benign nor neutral, as marine carrion subsidies to coastal red fox populations are likely to facilitate their persistence as exotic

Bergenin Content and Free Radical Scavenging Activity of Bergenia Extracts. .

Science.gov (United States)

Hendrychová, Helena; Martin, Jan; Tůmová, Lenka; Kočevar-Glavač, Nina

2015-07-01

Our research was focused on the evaluation of bergenin content and free radical scavenging activity of extracts prepared from three different species of Bergenia - B. crassifolia (L.) Fritsch., B. ciliata (Haw.) Sternb. and B. x ornata Stein. collected during different seasons. Using an HPLC method, the highest total amount of bergenin was revealed in the leaves of B. x ornata and B. crassifolia (4.9 - 5.1 mg x g(-1)). Free radical scavenging power was determined by two methods--FRAP and NADH. The best free radical scavengers were B. crassifolia (FRAP: 6.7 - 15.9 mg GAE. 100g(-1); NADH: 20.3 - 50.9%) and B. ornata (FRAP: 13.7 - 15.2 mg GAE. 100g(-1); NADH: 29.3 - 31.1%). The lowest content of bergenin and the weakest radical scavenger was B. ciliata (bergenin: 3.1 mg x g(-1); FRAP: 5.5 - 11.0 mg GAE.100g(-1); NADH: 23.2 - 25.6%). The presence of a large percentage of bergenin is responsible for the radical scavenging activity, as shown by the results from the FRAP and NADH assays. Significant, positive correlation was found between bergenin content and radical scavenging activity in both methods.

Radionuclide fluxes in the Arabian Sea: The role of particle composition

Digital Repository Service at National Institute of Oceanography (India)

Scholten, J.C.; Fietzke, J.; Mangini, A.; Stoffers, P.; Rixen, T.; Gaye-Haake, B.; Blanz, T.; Ramaswamy, V.; Sirocko, F.; Schulz, H.; Ittekkot, V.

scavenging. 2. Methods Sediment trap samples were obtained from loca- tions WAST, CAST and EAST. Details on the locations, sampling intervals and average composition of the sediment trap material are given in Table 1. investigated Collection interruptions Ca... as they sink through the water column [11]. One of the basic methods when applying radio- high ratios are expected at continental margins (high particle flux), and such a boundary scavenging was observed in the surface sediments of the Pacific Ocean [13...

PIV study of the effect of piston position on the in-cylinder swirling flow during the scavenging process in large two-stroke marine diesel engines

DEFF Research Database (Denmark)

Haider, Sajjad; Schnipper, Teis; Obeidat, Anas

2013-01-01

A simplified model of a low speed large twostroke marine diesel engine cylinder is developed. The effect of piston position on the in-cylinder swirling flow during the scavenging process is studied using the stereoscopic particle image velocimetry technique. The measurements are conducted...

Identification of Radical Scavengers in Sweet Grass (Hierochloe odorata)

NARCIS (Netherlands)

Pukalskas, A.; Beek, van T.A.; Venskutonis, R.P.; Linssen, J.P.H.; Veldhuizen, van A.; Groot, de Æ.

2002-01-01

Extracts from aerial parts of sweet grass (Hierochloe odorata) were active DPPH free radical scavengers, The active compounds were detected in extract fractions using HPLC with on-line radical scavenging detection. After multistep fractionation of the extract, two new natural products possessing

A Geospatial Scavenger Hunt

Science.gov (United States)

Martinez, Adriana E.; Williams, Nikki A.; Metoyer, Sandra K.; Morris, Jennifer N.; Berhane, Stephen A.

2009-01-01

With the use of technology such as Global Positioning System (GPS) units and Google Earth for a simple-machine scavenger hunt, you will transform a standard identification activity into an exciting learning experience that motivates students, incorporates practical skills in technology, and enhances students' spatial-thinking skills. In the…

Characterizing the composition and evolution of and urban particles in Chongqing (China) during summertime

Science.gov (United States)

Chen, Yang; Yang, Fumo; Mi, Tian; Cao, Junji; Shi, Guangming; Huang, Rujin; Wang, Huanbo; Chen, Jun; Lou, Shengrong; Wang, Qiyuan

2017-05-01

Urban particles were investigated using a single particle aerosol mass spectrometer (SPAMS) in Chongqing during the summertime (from 07/05/2014 to 08/06/2014). Chemical composition, mixing state, and atmospheric behavior of urban particles were studied. The major particle types include ECOC (Elemental-Carbon-Organic-Carbon 20.6%), OC (20.1%), KSec (K-Secondary) (13.3%), BB (Biomass burning, 11.9%), NaK (sodium-potassium-rich, 7.3%), Al-rich (4.0%), Fe-rich (3.2%), Ca-rich (1.4%), Ca-EC (1.6%), and NaKPb (0.5%). EC, ECOC, OC, and Ca-EC were prevalent in the condensation mode (Case studies suggested that wet scavenging (rain) rates of different single particle types followed an order of NaKPb > Fe-rich > EC > Ca-EC > Ca-rich > KSec > OC > NaK > ECOC > Al-rich > BB. Increased number fraction of EC and KSec were correlated with the increase of odd oxygen (Ox = O3 + NO2). EC, OC, and ECOC were enriched at higher relative humidity. The findings of this study on the mixing state, temporal variation, processing, and evolution of single particles provide new insight into the atmospheric behavior and impacts of urban particles.

Modeling of an Integrated Electromagnetic Generator for Energy Scavenging

NARCIS (Netherlands)

Lu, J.; Kovalgin, Alexeij Y.; Schmitz, Jurriaan

2007-01-01

The ubiquitous deploying of wireless electronic devices due to pervasive computing results in the idea of Energy Scavenging, i.e., harvesting ambient energy from surroundings of the electronic devices. As an approach to possible practical realization of such an energy scavenger, we aim at the

Reactive oxygen species and lipid peroxidation product-scavenging ability of yogurt organisms.

Science.gov (United States)

Lin, M Y; Yen, C L

1999-08-01

The antioxidative activity of the intracellular extracts of yogurt organisms was investigated. All 11 strains tested, including five strains of Streptococcus thermophilus and six strains of Lactobacillus delbrueckii ssp. bulgaricus, demonstrated an antioxidative effect on the inhibition of linoleic acid peroxidation. The antioxidative effect of intracellular extracts of 10(8) cells of yogurt organisms was equivalent to 25 to 96 ppm butylated hydroxytoluene, which indicated that all strains demonstrated excellent antioxidative activity. The scavenging of reactive oxygen species, hydroxyl radical, and hydrogen peroxide was studied for intracellular extracts of yogurt organisms. All strains showed reactive oxygen species-scavenging ability. Lactobacillus delbrueckii ssp. bulgaricus Lb demonstrated the highest hydroxyl radical-scavenging ability at 234 microM. Streptococcus thermophilus MC and 821 and L. delbrueckii ssp. bulgaricus 448 and 449 scavenged the most hydrogen peroxide at approximately 50 microM. The scavenging ability of lipid peroxidation products, t-butylhydroperoxide and malondialdehyde, was also evaluated. Results showed that the extracts were not able to scavenge the t-butylhydroperoxide. Nevertheless, malondialdehyde was scavenged well by most strains.

Occurrence and distribution of nitrogen-scavenging bacteria in marine environment

OpenAIRE

Sugahara, Isao; Kimura, Toshio; Hayashi, Koichiro

1987-01-01

The occurrence and distribution nitrogen-scavenging bacteria in the water of coastal and oceanic of Japan were studied during the Seisui-Maru cruises from 1986 to 1987. Nitroben-scavenging bacteria in the water usually occurred at the level of 10-104 cfu/ml.This value was almost comparable to that of aerobic heterotrophic bacteria. It seems that nitrogen-scavenging bacteria play an important role in the efficient uptake of low levels of nitrogenous compounds in marine enviroment.

Energy scavenging sources for biomedical sensors

International Nuclear Information System (INIS)

Romero, E; Warrington, R O; Neuman, M R

2009-01-01

Energy scavenging has increasingly become an interesting option for powering electronic devices because of the almost infinite lifetime and the non-dependence on fuels for energy generation. Moreover, the rise of wireless technologies promises new applications in medical monitoring systems, but these still face limitations due to battery lifetime and size. A trade-off of these two factors has typically governed the size, useful life and capabilities of an autonomous system. Energy generation from sources such as motion, light and temperature gradients has been established as commercially viable alternatives to batteries for human-powered flashlights, solar calculators, radio receivers and thermal-powered wristwatches, among others. Research on energy harvesting from human activities has also addressed the feasibility of powering wearable or implantable systems. Biomedical sensors can take advantage of human-based activities as the energy source for energy scavengers. This review describes the state of the art of energy scavenging technologies for powering sensors and instrumentation of physiological variables. After a short description of the human power and the energy generation limits, the different transduction mechanisms, recent developments and challenges faced are reviewed and discussed. (topical review)

Phototransformation rate constants of PAHs associated with soot particles

International Nuclear Information System (INIS)

Kim, Daekyun; Young, Thomas M.; Anastasio, Cort

2013-01-01

Photodegradation is a key process governing the residence time and fate of polycyclic aromatic hydrocarbons (PAHs) in particles, both in the atmosphere and after deposition. We have measured photodegradation rate constants of PAHs in bulk deposits of soot particles illuminated with simulated sunlight. The photodegradation rate constants at the surface (k p 0 ), the effective diffusion coefficients (D eff ), and the light penetration depths (z 0.5 ) for PAHs on soot layers of variable thickness were determined by fitting experimental data with a model of coupled photolysis and diffusion. The overall disappearance rates of irradiated low molecular weight PAHs (with 2–3 rings) on soot particles were influenced by fast photodegradation and fast diffusion kinetics, while those of high molecular weight PAHs (with 4 or more rings) were apparently controlled by either the combination of slow photodegradation and slow diffusion kinetics or by very slow diffusion kinetics alone. The value of z 0.5 is more sensitive to the soot layer thickness than the k p 0 value. As the thickness of the soot layer increases, the z 0.5 values increase, but the k p 0 values are almost constant. The effective diffusion coefficients calculated from dark experiments are generally higher than those from the model fitting method for illumination experiments. Due to the correlation between k p 0 and z 0.5 in thinner layers, D eff should be estimated by an independent method for better accuracy. Despite some limitations of the model used in this study, the fitted parameters were useful for describing empirical results of photodegradation of soot-associated PAHs. - Highlights: ► PAHs on soot were evaluated by a model of coupled photolysis and diffusion. ► Photodegradation rate at the surface, diffusion coefficient, and light penetration path were determined. ► Low MW PAHs were influenced by fast photodegradation and fast diffusion. ► High MW PAHs were controlled either by slow

Synthesis and Free Radical Scavenging Activity of New Hydroxybenzylidene Hydrazines

Directory of Open Access Journals (Sweden)

Frantisek Sersen

2017-05-01

Full Text Available Hydroxybenzylidene hydrazines exhibit a wide spectrum of biological activities. Here, we report synthesis and free radical scavenging activity of nine new N-(hydroxybenzylidene-N′-[2,6-dinitro-4-(trifluoromethyl]phenylhydrazines. The chemical structures of these compounds were confirmed by 1H-NMR, 13C-NMR, 19F-NMR, IR spectroscopy, LC-MS, and elemental analysis. The prepared compounds were tested for their activity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH, galvinoxyl radical (GOR, and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS radicals. The free radical scavenging activity expressed as SC50 values of these compounds varied in a wide range, from a strong to no radical scavenging effect. The most effective radical scavengers were hydroxybenzylidene hydrazines containing three hydroxyl groups in the benzylidene part of their molecules. The prepared compounds were also tested for their activity to inhibit photosynthetic electron transport in spinach chloroplasts. IC50 values of these compounds varied in wide range, from an intermediate to no inhibitory effect.

The oxygen-centered radicals scavenging activity of sulfasalazine and its metabolites. A direct protection of the bowel.

Science.gov (United States)

Prónai, L; Yukinobu, I; Láng, I; Fehér, J

1992-01-01

Oxygen-centered radicals, such as superoxide (O2-) and hydroxyl radicals (.OH) generated by phagocytes have been suggested to be involved in the pathogenesis of chronic inflammations of the bowel, such as Crohn's disease and colitis ulcerosa. Recently, sulfasalazine (SASP) and its metabolites have been reported to exert their effects as a direct scavenger of oxygen-centered radicals in the bowel. To scavenge oxygen-centered radicals in vivo, however, SASP and its metabolites have to react with O2- and/or .OH in vitro very rapidly, furthermore they have to reach an appropriate (possible millimolar) concentration range at the site of inflammation. To test this possibility, we investigated the direct O2- and .OH scavenging activity of SASP and its metabolites using the specific electron paramagnetic resonance/spin trapping method, and we compared the 50% inhibition rates of SASP and its metabolites with their known concentrations in the bowel and in the human plasma. It was found that SASP and its metabolites, such as 5-amino-salicylic acid (5-ASA), and acetyl-5-amino-salicylic acid (AC-5-ASA), but not sulfapyridine (SP) and acetyl-sulfapyridine (Ac-SP) have a direct O2- and .OH scavenging activity in vitro systems. Among the compounds, SASP and 5-ASA can reach a concentration which is appropriate to scavenge oxygen-centered radicals in the bowel but not in the human plasma. It was concluded that the in vivo antiinflammatory effects of SASP and its metabolites are, at least partly, due to the direct oxygen-centered scavenging activity of these drugs.

Particle creation rate for dynamical black holes

Energy Technology Data Exchange (ETDEWEB)

Firouzjaee, Javad T. [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), Tehran (Iran, Islamic Republic of); University of Oxford, Department of Physics (Astrophysics), Oxford (United Kingdom); Ellis, George F.R. [University of Cape Town, Mathematics and Applied Mathematics Department, Rondebosch (South Africa)

2016-11-15

We present the particle creation probability rate around a general black hole as an outcome of quantum fluctuations. Using the uncertainty principle for these fluctuation, we derive a new ultraviolet frequency cutoff for the radiation spectrum of a dynamical black hole. Using this frequency cutoff, we define the probability creation rate function for such black holes. We consider a dynamical Vaidya model and calculate the probability creation rate for this case when its horizon is in a slowly evolving phase. Our results show that one can expect the usual Hawking radiation emission process in the case of a dynamical black hole when it has a slowly evolving horizon. Moreover, calculating the probability rate for a dynamical black hole gives a measure of when Hawking radiation can be killed off by an incoming flux of matter or radiation. Our result strictly suggests that we have to revise the Hawking radiation expectation for primordial black holes that have grown substantially since they were created in the early universe. We also infer that this frequency cut off can be a parameter that shows the primordial black hole growth at the emission moment. (orig.)

Use of bird carcass removals by urban scavengers to adjust bird-window collision estimates

Directory of Open Access Journals (Sweden)

Justine A. Kummer

2016-12-01

Full Text Available Carcass removal by scavengers has been identified as one of the largest biases in estimating bird mortality from anthropogenic sources. Only two studies have examined carcass removal by scavengers in an urban environment, and previous estimates of bird-window collision mortality at houses have relied on carcass removal rates from wind turbine studies. We placed a bird carcass and time-lapse camera at 44 houses in Edmonton, Alberta. In total, 166 7-day trials were conducted throughout 2015. Time-to-event (survival analysis was used to identify covariates that affected removal. The carcass removal rate was determined for use in estimating the number of birds killed from bird-window collisions at houses in Alberta. In total, 67.5% of carcasses were removed. The date the carcass was placed, the year the house was built, and the level of development within 50 m of the house were the covariates that had the largest effect on carcass removal. In calculating our removal rate, the number of detected carcasses in the first 24 hours was adjusted by 1.47 to account for removal by scavengers. Previously collected citizen science data were used to create an estimate of 957,440 bird deaths each year in Alberta as a result of bird-window collisions with houses. This number is based on the most detailed bird-window collision study at houses to date and a carcass removal study conducted in the same area. Similar localized studies across Canada will need to be completed to reduce the biases that exist with the previous bird-window collision mortality estimate for houses in Canada.

Free radical scavenging injectable hydrogels for regenerative therapy.

Science.gov (United States)

Komeri, Remya; Thankam, Finosh Gnanaprakasam; Muthu, Jayabalan

2017-02-01

Pathological free radicals generated from inflamed and infarcted cardiac tissues interferes natural tissue repair mechanisms. Hypoxic microenvironment at the injured zone of non-regenerating cardiac tissues hinders the therapeutic attempts including cell therapy. Here we report an injectable, cytocompatible, free radical scavenging synthetic hydrogel formulation for regenerative therapy. New hydrogel (PEAX-P) is prepared with D-xylitol-co-fumarate-co-poly ethylene adipate-co-PEG comaromer (PEAX) and PEGDiacrylate. PEAX-P hydrogel swells 4.9 times the initial weight and retains 100.07kPa Young modulus at equilibrium swelling, which is suitable for cardiac applications. PEAX-P hydrogel retains elastic nature even at 60% compressive strain, which is favorable to fit with the dynamic and elastic natural tissue counterparts. PEAX-P hydrogel scavenges 51% DPPH radical, 40% hydroxyl radicals 41% nitrate radicals with 31% reducing power. The presence of hydrogel protects 62% cardiomyoblast cells treated with stress inducing media at LD 50 concentration. The free hydroxyl groups in sugar alcohols of the comacromer influence the free radical scavenging. Comparatively, PEAX-P hydrogel based on xylitol evinces slightly lower scavenging characteristics than with previously reported PEAM-P hydrogel containing mannitol having more hydroxyl groups. The possible free radical scavenging mechanism of the present hydrogel relies on the free π electrons associated with uncrosslinked fumarate bonds, hydrogen atoms associated with sugar alcohols/PEG and radical dilution by free water in the matrix. Briefly, the present PEAX-P hydrogel is a potential injectable system for combined antioxidant and regenerative therapy. Copyright © 2016 Elsevier B.V. All rights reserved.

Functionalized graphene quantum dots loaded with free radicals combined with liquid chromatography and tandem mass spectrometry to screen radical scavenging natural antioxidants from Licorice and Scutellariae.

Science.gov (United States)

Wang, Guoying; Niu, XiuLi; Shi, Gaofeng; Chen, Xuefu; Yao, Ruixing; Chen, Fuwen

2014-12-01

A novel screening method was developed for the detection and identification of radical scavenging natural antioxidants based on a free radical reaction combined with liquid chromatography with tandem mass spectrometry. Functionalized graphene quantum dots were prepared for loading free radicals in the complex screening system. The detection was performed with and without a preliminary exposure of the samples to specific free radicals on the functionalized graphene quantum dots, which can facilitate charge transfer between free radicals and antioxidants. The difference in chromatographic peak areas was used to identify potential antioxidants. This is a novel approach to simultaneously evaluate the antioxidant power of a component versus a free radical, and to identify it in a vegetal matrix. The structures of the antioxidants in the samples were identified using tandem mass spectrometry and comparison with standards. Fourteen compounds were found to possess potential antioxidant activity, and their free radical scavenging capacities were investigated. The order of scavenging capacity of 14 compounds was compared according to their free radical scavenging rate. 4',5,6,7-Tetrahydroxyflavone (radical scavenging rate: 0.05253 mL mg(-1) s(-1) ) showed the strongest capability for scavenging free radicals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electron beam treatment with radical scavengers/enhancers

International Nuclear Information System (INIS)

Gehringer, P.

1994-08-01

E-beam treatment of low level contaminated groundwater is best apt to demonstrate the role of scavengers and enhancers, respectively because groundwater already contains some scavengers as natural solutes. The action of ionizing radiation to water is known to result in the formation of ions, molecular and free radical species. For low level contaminations of groundwater (pollutant concentration aqu - and H are of interest for pollutant decomposition. The pollutants have to compete for the free radical species with the natural solutes. 10 figures are discussed. (author)

New actualistic data on the ecology and energetics of hominin scavenging opportunities.

Science.gov (United States)

Pobiner, Briana L

2015-03-01

For decades, the 'hunting-scavenging debate' has been an important research focus in Plio-Pleistocene hominin behavioral ecology. Here I present new data on potential scavenging opportunities from fresh carnivore kills on a conservancy in central Kenya. This ecosystem is dominated by felids (mainly lions) and has a different carnivore guild than in many earlier studies of scavenging opportunities that took place in areas such as Ngorongoro and Serengeti in Tanzania and Maasai Mara in Kenya, where lions face high levels of inter-specific competition from bone-crunching hyenas. I found that while scavenging opportunities vary among carcasses, most carcasses retained some scavengeable resources. Excluding within-bone resources, even the scavengeable meat on 'defleshed' larger sized prey carcasses is usually substantial enough to meet the total daily caloric requirements of at least one adult male Homo erectus individual. I argue, as others have before me, that scavenging opportunities in a particular ecosystem will vary in part due to carnivore taxon, density and guild composition; prey size, biomass and community structure; and habitat (e.g., vegetation, physiography). We should expect variability in scavenging opportunities in different locales and should focus our research efforts on identifying which variables condition these differences in order to make our findings applicable to the diversity of ecological settings characterizing the past. Published by Elsevier Ltd.

Surface Potential and Particle Size Effect on the Rate of Perikinetic Coagulation

International Nuclear Information System (INIS)

Molina-Bolivar, J. A.; Galisteo-Gonzalez, F.; Cabrerizo-Vilchez, M.; Hidalgo-alvarez, R.

1998-01-01

The diffusion-controlled rapid coagulation rate of monodisperse polystyrene particles in aqueous solutions has been measured with a low angle scattering apparatus (nephelometer). We have refined this technique by using a narrow scattering flow cell and a pneumatic addicting-mixing device to introduce the salt solution and the latex sample in the cell. Coagulation rate constants were determined from analysis of the scattered light intensity dependence with time at an angle of 4.5 degree centigrade ± 1 degree centigrade. Experiments were designed to check the effects of particle size, surface potential and counterion valency on rapid coagulation constant. The particle ranged in diameter from 151 nm to 530 nm. The results are compared with the predictions of Smoluchowski's theory. Experiments to obtain the stability diagrams and the critical coagulation concentration of latexes have been performed. (Author) 31 refs

Nitric oxide radical scavenging potential of some Elburz medicinal ...

African Journals Online (AJOL)

Some plants scavenge nitric oxide (NO) with high affinity. For this purpose, forty extracts from 26 medicinal plants, growing extensively in Elburz mountains, were evaluated for their NO scavenging activity. Total phenolic and flavonoid contents of these extracts were also measured by Folin Ciocalteu and AlCl3 colorimetric ...

The research progress of several kinds of free radical scavengers

International Nuclear Information System (INIS)

Qian Liren; Huang Yuecheng; Cai Jianming

2009-01-01

Ionization radiation can generate free radicals in biological system, which could induce lipid peroxi-dation, biomacromolecule and biomembrane damage, lost of cell function, cell cycle disturbance, genetic mutation and so on. The scavenging free radicals can protect organism from radiation damage. Many radio-protective agents, such as amylase, hydroxyl-benzene derivatives, hormone, vitamin, have great abilities to protect organism from radiation via scavenging free radicals. In this paper, we mainly review the free radical scavenging effects of several kinds of radio-protective agents. (authors)

Scavenging efficiency and red fox abundance in Mediterranean mountains with and without vultures

Science.gov (United States)

Morales-Reyes, Zebensui; Sánchez-Zapata, José A.; Sebastián-González, Esther; Botella, Francisco; Carrete, Martina; Moleón, Marcos

2017-02-01

Vertebrate scavenging assemblages include two major functional groups: obligate scavengers (i.e., vultures), which depend totally on carrion and are undergoing severe declines around the globe, and facultative scavengers, which exploit carrion opportunistically and are generally ubiquitous. Our goal was to investigate the hypothesis that vultures can indirectly regulate the abundance of mesopredators (i.e., facultative scavengers) through modulating their access to carrion resources. We studied scavenging efficiency and red fox (Vulpes vulpes) abundance in two neighbouring areas of South-eastern Spain where vultures (mainly griffon vultures Gyps fulvus) are present (Cazorla) and absent (Espuña). To do so, we monitored ungulate carcasses consumption during winter and summer, and counted red fox scats along walking transects as a proxy of fox density. Our results confirmed that scavenging efficiency was higher in Cazorla and in carcasses visited by vultures. This resulted in increasing scavenging opportunities for facultative scavengers where vultures were absent. Accordingly, mean red fox abundance was higher in Espuña. These results suggest the existence of a vulture-mediated mesopredator release (i.e., an increase of mesopredator numbers following vulture loss), which could trigger important indirect ecological effects. Also, our study demonstrates that facultative scavengers are hardly able to functionally replace vultures, mainly because the former exploit carrion on a slower time scale.

A Targeted "Capture" and "Removal" Scavenger toward Multiple Pollutants for Water Remediation based on Molecular Recognition.

Science.gov (United States)

Wang, Jie; Shen, Haijing; Hu, Xiaoxia; Li, Yan; Li, Zhihao; Xu, Jinfan; Song, Xiufeng; Zeng, Haibo; Yuan, Quan

2016-03-01

For the water remediation techniques based on adsorption, the long-standing contradictories between selectivity and multiple adsorbability, as well as between affinity and recyclability, have put it on weak defense amid more and more severe environment crisis. Here, a pollutant-targeting hydrogel scavenger is reported for water remediation with both high selectivity and multiple adsorbability for several pollutants, and with strong affinity and good recyclability through rationally integrating the advantages of multiple functional materials. In the scavenger, aptamers fold into binding pockets to accommodate the molecular structure of pollutants to afford perfect selectivity, and Janus nanoparticles with antibacterial function as well as anisotropic surfaces to immobilize multiple aptamers allow for simultaneously handling different kinds of pollutants. The scavenger exhibits high efficiencies in removing pollutants from water and it can be easily recycled for many times without significant loss of loading capacities. Moreover, the residual concentrations of each contaminant are well below the drinking water standards. Thermodynamic behavior of the adsorption process is investigated and the rate-controlling process is determined. Furthermore, a point of use device is constructed and it displays high efficiency in removing pollutants from environmental water. The scavenger exhibits great promise to be applied in the next generation of water purification systems.

Scavenging ratios, wet deposition, and in-cloud oxidation: An application to the oxides of sulphur and nitrogen

International Nuclear Information System (INIS)

Barrie, L.A.

1985-01-01

With special regard to the class of substances in precipitation that potentially originate from both gaseous and particulate precursors, the process of precipitation scavenging is discussed. A model relating daily average ground level scavenging ratios (W) to nucleation scavenging and in-cloud chemical transformation is introduced and is used as guidance in the regression analysis of 3 years of SO 4 = and NO 3 - scavenging-ratio observations made at six locations in eastern Canada. It was found that W of SO 4 = -, NO 3 = -, and SO 4 = -bearing particles is inversely proportional to the one-third power of the precipitation amount in the event. The best regression model explained 41% of the variance in log W for SO 4 = . It included the effects of location, precipitation amount, precipitation type, and in-cloud SO 2 oxidation. The last effect accounted for 50% of the variance explained. The analysis predicts that, on average, in-cloud SO 2 oxidation accounts for 42--79% of the SO 4 = observed in rain and with the exception of one site, less than 20% of the SO 4 = observed in snow. These results are consistent with a mechanism of SO 2 oxidation involving photochemically produced H 2 O 2 . A similar analysis for NO 3 - supports the hypothesis that throughout the year much of the NO 3 - in precipitation originates from in-cloud NO 2 oxidation. It suggests that, depending on location, oxidation of 0.5--1.2 ppbv of NO 2 is sufficient to explain observations. One possible mechanism of oxidation is the reaction with O 3 to form NO 3 and hence soluble N 2 O 5

Changes in free-radical scavenging ability of kombucha tea during fermentation.

Science.gov (United States)

Jayabalan, R; Subathradevi, P; Marimuthu, S; Sathishkumar, M; Swaminathan, K

2008-07-01

Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Free-radical scavenging abilities of kombucha tea prepared from green tea (GTK), black tea (BTK) and tea waste material (TWK) along with pH, phenolic compounds and reducing power were investigated during fermentation period. Phenolic compounds, scavenging activity on DPPH radical, superoxide radical (xanthine-xanthine oxidase system) and inhibitory activity against hydroxyl radical mediated linoleic acid oxidation (ammonium thiocyanate assay) were increased during fermentation period, whereas pH, reducing power, hydroxyl radical scavenging ability (ascorbic acid-iron EDTA) and anti-lipid peroxidation ability (thiobarbituric assay) were decreased. From the present study, it is obvious that there might be some chances of structural modification of components in tea due to enzymes liberated by bacteria and yeast during kombucha fermentation which results in better scavenging performance on nitrogen and superoxide radicals, and poor scavenging performance on hydroxyl radicals. Copyright © 2007 Elsevier Ltd. All rights reserved.

The Impact of Flight Hardware Scavenging on Space Logistics

Science.gov (United States)

Oeftering, Richard C.

2011-01-01

For a given fixed launch vehicle capacity the logistics payload delivered to the moon may be only roughly 20 percent of the payload delivered to the International Space Station (ISS). This is compounded by the much lower flight frequency to the moon and thus low availability of spares for maintenance. This implies that lunar hardware is much more scarce and more costly per kilogram than ISS and thus there is much more incentive to preserve hardware. The Constellation Lunar Surface System (LSS) program is considering ways of utilizing hardware scavenged from vehicles including the Altair lunar lander. In general, the hardware will have only had a matter of hours of operation yet there may be years of operational life remaining. By scavenging this hardware the program, in effect, is treating vehicle hardware as part of the payload. Flight hardware may provide logistics spares for system maintenance and reduce the overall logistics footprint. This hardware has a wide array of potential applications including expanding the power infrastructure, and exploiting in-situ resources. Scavenging can also be seen as a way of recovering the value of, literally, billions of dollars worth of hardware that would normally be discarded. Scavenging flight hardware adds operational complexity and steps must be taken to augment the crew s capability with robotics, capabilities embedded in flight hardware itself, and external processes. New embedded technologies are needed to make hardware more serviceable and scavengable. Process technologies are needed to extract hardware, evaluate hardware, reconfigure or repair hardware, and reintegrate it into new applications. This paper also illustrates how scavenging can be used to drive down the cost of the overall program by exploiting the intrinsic value of otherwise discarded flight hardware.

Novel hydrazones – antioxidant potential and stabilization via polysaccharide particles

International Nuclear Information System (INIS)

Hristova-Avakumova, N; Hadjimitova, V; Nikolova-Mladenova, B; Yoncheva, K

2017-01-01

In this study, we aimed to: i) determine the impact of three new isonicotinoyl hydrazones derivatives in in vitro systems used to investigate free radical processes - radical scavenging approach (ABTS and DPPH) and iron induced peroxidation in lipid containing model systems and ii) evaluate the potential of polysaccharide-based particles to act as protective carriers preserving the antioxidant activity (AOA) of the tested compounds. The tested compounds revealed excellent antioxidant effectiveness in the ABTS system. In the DPPH radical scavenging assay the compounds exhibited very weak or absence of AOA. The data from the iron induced peroxidation methods disclosed better antioxidant properties of the derivatives in the system containing egg yolk homogenate which is more plausible compared to the lecithin containing one. The incorporation of a bromine atom on 5 th position in salicylaldehyde moiety is associated with diminishment of the radical scavenging activity in the systems containing stable free radicals but its AOA reduction after encapsulation during the storage was only 9.17%. The obtained data indicate that compounds have proven themselves as promising candidates for further evaluation as antioxidant agents. Their encapsulation in chitosan-alginate particles could be a useful approach for improving the stability of their antioxidant properties. (paper)

Influence of microorganism content in suspended particles on the particle–water partitioning of mercury in semi-enclosed coastal waters

International Nuclear Information System (INIS)

Jang, Jiyi; Kim, Hyunji; Han, Seunghee

2014-01-01

It is known that particle scavenging of mercury (Hg) can be affected by the abundance of particulate organic matter in coastal waters. However, the role of living organic particles in Hg scavenging is not yet completely understood. In this study, we hypothesized that an abundance of living organic particles (i.e., phytoplankton and bacteria) would influence the particle–water partitioning of Hg in coastal waters. Surface seawater samples were collected from eight stations in Gwangyang Bay, Korea, in three seasons (November 2009, April 2010, and October 2010) for the determination of concentrations of suspended particulate matter (including chlorophyll-a and bacteria), and Hg in unfiltered and filtered waters. We found that more Hg partitioned toward particulate matter when phytoplankton biomass, indicated from the chlorophyll-a concentration in a particle, was higher. In the low algal season, when [chlorophyll-a] −1 , the bacterial number, instead of chlorophyll-a concentration in particle, showed a positive correlation with the particle–water partition coefficient of Hg. Overall, microbial abundance seems to play a critical role in particle scavenging of Hg in coastal water. Taking this result in light of Hg in pristine coastal zones, we predict that increases in algal biomass amplify the potential for algae to transfer Hg to marine food chains. - Highlights: • Abundance of phytoplankton and bacteria influenced particle–water partitioning of Hg. • More Hg partitioned toward particles when microorganism biomass in particle is large. • Increases of algal biomass may enhance Hg bioaccumulation in coastal ecosystem

Influence of microorganism content in suspended particles on the particle–water partitioning of mercury in semi-enclosed coastal waters

Energy Technology Data Exchange (ETDEWEB)

Jang, Jiyi [School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (Korea, Republic of); Global Bioresources Research Center, Korea Institute of Ocean Science and Technology (KIOST), Ansan 426-744 (Korea, Republic of); Kim, Hyunji [School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (Korea, Republic of); Han, Seunghee, E-mail: shan@gist.ac.kr [School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (Korea, Republic of)

2014-02-01

It is known that particle scavenging of mercury (Hg) can be affected by the abundance of particulate organic matter in coastal waters. However, the role of living organic particles in Hg scavenging is not yet completely understood. In this study, we hypothesized that an abundance of living organic particles (i.e., phytoplankton and bacteria) would influence the particle–water partitioning of Hg in coastal waters. Surface seawater samples were collected from eight stations in Gwangyang Bay, Korea, in three seasons (November 2009, April 2010, and October 2010) for the determination of concentrations of suspended particulate matter (including chlorophyll-a and bacteria), and Hg in unfiltered and filtered waters. We found that more Hg partitioned toward particulate matter when phytoplankton biomass, indicated from the chlorophyll-a concentration in a particle, was higher. In the low algal season, when [chlorophyll-a] < 0.6 μg L{sup −1}, the bacterial number, instead of chlorophyll-a concentration in particle, showed a positive correlation with the particle–water partition coefficient of Hg. Overall, microbial abundance seems to play a critical role in particle scavenging of Hg in coastal water. Taking this result in light of Hg in pristine coastal zones, we predict that increases in algal biomass amplify the potential for algae to transfer Hg to marine food chains. - Highlights: • Abundance of phytoplankton and bacteria influenced particle–water partitioning of Hg. • More Hg partitioned toward particles when microorganism biomass in particle is large. • Increases of algal biomass may enhance Hg bioaccumulation in coastal ecosystem.

Innate catalytic and free radical scavenging activities of silver nanoparticles synthesized using Dillenia indica bark extract.

Science.gov (United States)

Mohanty, Alfa S; Jena, Bhabani S

2017-06-15

A green approach was envisaged for the rapid synthesis of stable silver nanoparticles in an aqueous medium using phenolic rich ethanolic bark extract from D. indica with marked free radical scavenging and reducing ability. Biosynthesis of silver nanoparticles (AgNPs) was confirmed and characterized by using UV-visible spectroscopy, particle size analyzer, X-ray diffractometry (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FT-IR). Bio-reduction of Ag+ was confirmed with the appearance of golden yellow coloration within 5-10min at 45°C with maximum absorbance at 421nm. XRD analysis of AgNPs indicated the crystalline nature of metallic Ag. As analyzed by TEM, AgNPs were found to be spherical in shape, well dispersed and size varied from 15 to 35nm and dynamic light scattering (DLS) studies showed the average particle size of 29nm with polydispersity index (PDI) of 0.280. Synthesized AgNPs were showing surface functionalization as revealed through FTIR studies. These AgNPs were observed to be highly stable at room temperature (28±2°C) for more than 3months, thereby indicating the ethanolic extract of D. indica was a reducing as well as a capping agent for stabilization of AgNPs. Moreover, these green synthesized AgNPs showed enhanced free radical scavenging and excellent catalytic activities when used in the reduction of 4-nitrophenol and methylene blue dye, at room temperature. Copyright © 2017 Elsevier Inc. All rights reserved.

Using the EDTA Hole Scavenger to Accelerate Decolorization in the Immobilized Photocatalytic Process

Directory of Open Access Journals (Sweden)

raziye Asgari

2015-07-01

Full Text Available This study investigated the effect of EDTA as a hole scavenger on accelerating the photocatalytic decolorization of direct blue 71 as a non-degradable model pollutant with nano TiO2 powder immobilized on a cementitious bed. For this purpose, 75 mg/L of the dye was decolorized in 75 minutes with 0.03 M of EDTA at a pH level of 6 and under irradiation produced by a 60-W UV-C lamp. This is while decolorization under identical conditions but in the absence of EDTA had been accomplished in 225 minutes. The experiment, therefore, confirmed the accelerating effect of the scavenger on decolorization. The kinetics of the photocatalytic process with EDTA followed a first order reaction with a constant rate of 0.05 min-1, which is 2.5 times faster than the process without EDTA.

Microphysical processing of aerosol particles in orographic clouds

Directory of Open Access Journals (Sweden)

S. Pousse-Nottelmann

2015-08-01

aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO. The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener–Bergeron–Findeisen (WBF process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice crystal number

Particle dynamics study in the wake of Kerguelen Island using thorium isotopes

International Nuclear Information System (INIS)

Venchiarutti, C.; Jeandel, C.; Roy-Barman, M.

2008-01-01

In the context of the Kerguelen Ocean and Plateau compared Study (KEOPS, 19 January-13 February 2005), particle dynamics were investigated using thorium isotope measurements over and off the Kerguelen plateau. Dissolved and particulate 230 Th and 232 Th samples were collected at nine stations. Dissolved excess 230 Th concentrations ( 230 Th(xs)) vary from 0.5 to 20.8 fg/kg and particulate 230 Th(xs) concentrations from 0.1 to 10.0 fg/kg. Dissolved and particulate 232 Th concentration ranges are 16.8-450.2 pg/kg and 3.8-502.8 pg/kg, respectively. The 230 Th(xs) concentrations increase linearly with depth down to the bottom at most of the plateau stations and down to 1000 m at the off-plateau stations. This linear trend is observed down to the bottom (1550 m) at Kerfix, the open-ocean 'upstream' station located west of the Kerguelen plateau. A simple reversible scavenging model applied to these data allowed the estimation of adsorption rate constant (k 1 ≅ 0.2-0.8 year -1 ), desorption rate constant (k -1 ) ≅ 1-8 year -1 ) and partition coefficients (average K = 0.16 ± 0.07). Calculated particle settling velocities S deduced from this simple model are ca. 500 m/year at most of the plateau stations and 800 m/year at all the off-plateau stations. The plateau settling velocities are relatively low for such a productive site, compared to the surrounding HNLC areas. The difference might reflect the fact that lateral advection is neglected in this model. Taking this advection into account allows the reconstruction of the observed 230 Th(xs) linear distributions, but only if faster settling velocities are considered. This implies that the 1 D model strongly underestimates the settling velocity of the particles. In the deep layers, the occurrence of intense boundary scavenging along the escarpment due to bottom sediment re-suspension and interaction with a nepheloid layer, yielding a removal of similar to 50% of the Th stock along the northwestward transect, is

High throughput assay for evaluation of reactive carbonyl scavenging capacity.

Science.gov (United States)

Vidal, N; Cavaille, J P; Graziani, F; Robin, M; Ouari, O; Pietri, S; Stocker, P

2014-01-01

Many carbonyl species from either lipid peroxidation or glycoxidation are extremely reactive and can disrupt the function of proteins and enzymes. 4-hydroxynonenal and methylglyoxal are the most abundant and toxic lipid-derived reactive carbonyl species. The presence of these toxics leads to carbonyl stress and cause a significant amount of macromolecular damages in several diseases. Much evidence indicates trapping of reactive carbonyl intermediates may be a useful strategy for inhibiting or decreasing carbonyl stress-associated pathologies. There is no rapid and convenient analytical method available for the assessment of direct carbonyl scavenging capacity, and a very limited number of carbonyl scavengers have been identified to date, their therapeutic potential being highlighted only recently. In this context, we have developed a new and rapid sensitive fluorimetric method for the assessment of reactive carbonyl scavengers without involvement glycoxidation systems. Efficacy of various thiol- and non-thiol-carbonyl scavenger pharmacophores was tested both using this screening assay adapted to 96-well microplates and in cultured cells. The scavenging effects on the formation of Advanced Glycation End-product of Bovine Serum Albumin formed with methylglyoxal, 4-hydroxynonenal and glucose-glycated as molecular models were also examined. Low molecular mass thiols with an α-amino-β-mercaptoethane structure showed the highest degree of inhibitory activity toward both α,β-unsaturated aldehydes and dicarbonyls. Cysteine and cysteamine have the best scavenging ability toward methylglyoxal. WR-1065 which is currently approved for clinical use as a protective agent against radiation and renal toxicity was identified as the best inhibitor of 4-hydroxynonenal.

High throughput assay for evaluation of reactive carbonyl scavenging capacity

Directory of Open Access Journals (Sweden)

N. Vidal

2014-01-01

Full Text Available Many carbonyl species from either lipid peroxidation or glycoxidation are extremely reactive and can disrupt the function of proteins and enzymes. 4-hydroxynonenal and methylglyoxal are the most abundant and toxic lipid-derived reactive carbonyl species. The presence of these toxics leads to carbonyl stress and cause a significant amount of macromolecular damages in several diseases. Much evidence indicates trapping of reactive carbonyl intermediates may be a useful strategy for inhibiting or decreasing carbonyl stress-associated pathologies. There is no rapid and convenient analytical method available for the assessment of direct carbonyl scavenging capacity, and a very limited number of carbonyl scavengers have been identified to date, their therapeutic potential being highlighted only recently. In this context, we have developed a new and rapid sensitive fluorimetric method for the assessment of reactive carbonyl scavengers without involvement glycoxidation systems. Efficacy of various thiol- and non-thiol-carbonyl scavenger pharmacophores was tested both using this screening assay adapted to 96-well microplates and in cultured cells. The scavenging effects on the formation of Advanced Glycation End-product of Bovine Serum Albumin formed with methylglyoxal, 4-hydroxynonenal and glucose-glycated as molecular models were also examined. Low molecular mass thiols with an α-amino-β-mercaptoethane structure showed the highest degree of inhibitory activity toward both α,β-unsaturated aldehydes and dicarbonyls. Cysteine and cysteamine have the best scavenging ability toward methylglyoxal. WR-1065 which is currently approved for clinical use as a protective agent against radiation and renal toxicity was identified as the best inhibitor of 4-hydroxynonenal.

Free radical scavenging properties of some wine probes

International Nuclear Information System (INIS)

Stasko, A.; Liptakova, M.; Malik, F.

1999-01-01

There are preliminary results of investigation of scavenging properties of 8 probes of Slovak wines (consisting of one reference, 3 probes of white wine and 4 probes of red wine). According to the literature so far, wine probes contain paramagnetic species (Mn 2+ , characterised with sextet spectrum, and a singlet line around g=2,00). In our probes we observed Mn 2+ signals, but no significant evidence for a single line of free radical was found. We can conclude that Mn 2+ content in the red wines is generally higher than in the white ones. Further, we investigated the scavenging activities of the probes adding solution of dinitropicryl hydrazyl (DPPH-stable radical) to them. Their ability to terminate free radicals resulted in the decrease of the final DPPH concentrations in the probes. The red wines have significantly higher capability to scavenge free radicals than the probes of white wines. (authors)

Surgical Space Suits Increase Particle and Microbiological Emission Rates in a Simulated Surgical Environment.

Science.gov (United States)

Vijaysegaran, Praveen; Knibbs, Luke D; Morawska, Lidia; Crawford, Ross W

2018-05-01

The role of space suits in the prevention of orthopedic prosthetic joint infection remains unclear. Recent evidence suggests that space suits may in fact contribute to increased infection rates, with bioaerosol emissions from space suits identified as a potential cause. This study aimed to compare the particle and microbiological emission rates (PER and MER) of space suits and standard surgical clothing. A comparison of emission rates between space suits and standard surgical clothing was performed in a simulated surgical environment during 5 separate experiments. Particle counts were analyzed with 2 separate particle counters capable of detecting particles between 0.1 and 20 μm. An Andersen impactor was used to sample bacteria, with culture counts performed at 24 and 48 hours. Four experiments consistently showed statistically significant increases in both PER and MER when space suits are used compared with standard surgical clothing. One experiment showed inconsistent results, with a trend toward increases in both PER and MER when space suits are used compared with standard surgical clothing. Space suits cause increased PER and MER compared with standard surgical clothing. This finding provides mechanistic evidence to support the increased prosthetic joint infection rates observed in clinical studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Biogeochemical significance of transport exopolymer particles in the Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

DileepKumar, M.; Sarma, V.V.S.S.; Ramaiah, N.; Gauns, M.; DeSousa, S.N.

was found between waters of the Arabian Sea and the Bay of Bengal. The TEP concentrations were lower in the Bay of Bengal due to faster scavenging from water column because of interaction with mineral particles. They were higher and occurred even in intense...

Microstructure and strain rate effects on the mechanical behavior of particle reinforced epoxy-based reactive materials

Science.gov (United States)

White, Bradley William

The effects of reactive metal particles on the microstructure and mechanical properties of epoxy-based composites is investigated in this work. Particle reinforced polymer composites show promise as structural energetic materials that can provide structural strength while simultaneously being capable of releasing large amounts of chemical energy through highly exothermic reactions occurring between the particles and with the matrix. This advanced class of materials is advantageous due to the decreased amount of high density inert casings needed for typical energetic materials and for their ability to increase payload expectancy and decrease collateral damage. Structural energetic materials can be comprised of reactive particles that undergo thermite or intermetallic reactions. In this work nickel (Ni) and aluminum (Al) particles were chosen as reinforcing constituents due to their well characterized mechanical and energetic properties. Although, the reactivity of nickel and aluminum is well characterized, the effects of their particle size, volume fractions, and spatial distribution on the mechanical behavior of the epoxy matrix and composite, across a large range of strain rates, are not well understood. To examine these effects castings of epoxy reinforced with 20--40 vol.% Al and 0--10 vol.% Ni were prepared, while varying the aluminum nominal particle size from 5 to 50 mum and holding the nickel nominal particle size constant at 50 mum. Through these variations eight composite materials were produced, possessing unique microstructures exhibiting different particle spatial distributions and constituent makeup. In order to correlate the microstructure to the constitutive response of the composites, techniques such as nearest-neighbor distances, and multiscale analysis of area fractions (MSAAF) were used to quantitatively characterize the microstructures. The composites were investigated under quasi-static and dynamic compressive loading conditions to characterize

Scavenging energy from human motion with tubular dielectric polymer

Science.gov (United States)

Jean-Mistral, Claire; Basrour, Skandar

2010-04-01

Scavenging energy from human motion is a challenge to supply low consumption systems for sport or medical applications. A promising solution is to use electroactive polymers and especially dielectric polymers to scavenge mechanical energy during walk. In this paper, we present a tubular dielectric generator which is the first step toward an integration of these structures into textiles. For a 10cm length and under a strain of 100%, the structure is able to scavenge 1.5μJ for a poling voltage of 200V and up to 40μJ for a poling voltage of 1000V. A 30cm length structure is finally compared to our previous planar structure, and the power management module for those structures is discussed.

Particle mis-identification rate algorithm for the CLIC ILD and CLIC SiD detectors

CERN Document Server

Nardulli, J

2011-01-01

This note describes the algorithm presently used to determine the particle mis- identification rate and gives results for single particles for the CLIC ILD and CLIC SiD detector concepts as prepared for the CLIC Conceptual Design Report.

Radiation chemistry of heavy-particle tracks. I. General considerations

International Nuclear Information System (INIS)

Magee, J.L.; Chatterjee, A.

1980-01-01

The radiation chemistry of heavy-particle tracks in dilute aqueous solution is considered in a unified manner. Emphasis is on the physical and chemical phenomena which are involved rather than on the construction of models to be used in actual calculations although the latter problem is discussed. A differential segment of a heavy-particle track is composed of two parts which we call core and penumbra; elementary considerations show that all properties of such a differential track can be uniquely specified in terms of a two-parameter system, and we choose energy per nucleon (E) and atomic numbers (Z) as independent parameters. The nature of heavy-particle-track processes varies with the magnitude of the energy deposit (LET), and we discuss three categories of track problems, for low-, intermediate-, and high-LET cases, respectively. Scavenger reactions normally terminate radical recombination in a track, and for heavy-particle tracks we find a criterion involving the scavenger concentration for a convenient separation of core and penumbra into essentially noninteracting parts which can be treated independently. Problems of the core expansion in the three regions are considered, and it is found that a versatile model can be constructed on concepts previously introduced by Ganguly and Magee. A model for the penumbra, based on the authors' electron-track theory, is presented and discussed

Basic investigations on the performance of a normoxic polymer gel with tetrakis-hydroxy-methyl-phosphonium chloride as an oxygen scavenger: Reproducibility, accuracy, stability, and dose rate dependence

International Nuclear Information System (INIS)

Bayreder, Christian; Georg, Dietmar; Moser, Ewald; Berg, Andreas

2006-01-01

Magnetic resonance (MR)-based polymer gel dosimetry using normoxic polymer gels, represents a new dosimetric method specially suited for high-resolution three-dimensional dosimetric problems. The aim of this study was to investigate the dose response with regard to stability, accuracy, reproducibility, and the dose rate dependence. Tetrakis-hydroxy-methyl-phosphonium chloride (THPC) is used as an oxygen scavenger, and methacrylic acid as a monomer. Accuracy, reproducibility, and dose resolution were determined for MR protocols at low spatial resolution (typical for clinical scanners), medium, and microimaging-resolution protocols at three different dose levels. The dose-response stability and preirradiation-induced variations in R2, related to the time interval between preparation and irradiation of the polymer gel, were investigated. Also postirradiation stability of the polymer gel was considered. These experiments were performed using a 60 Co beam (E=1.2 MV) in a water phantom. Moreover, we investigated the dose rate dependence in the low, medium, and saturation dose region of the normoxic polymer gel using a linear accelerator at photon energy of 25 MV. MR scanning was performed on a 3 T whole body scanner (MEDSPEC 30/80, BRUKER BIOSPIN, Ettlingen, Germany) using several coils and different gradient systems adapted to the acquired spatial resolution investigated. For T2-parameter selective imaging and determination of the relaxation rate R2=1/T2, a multiple spin echo sequence with 20 equidistant echoes was used. With regard to preirradiation induced variations R2 increases significantly with the increasing time interval between the polymer gel preparation and irradiation. Only a slight increase in R2 can be observed for varying the postirradiation-time solely. The dose reproducibility at voxel volumes of about 1.4x1.4x2 mm 3 is better than 2%. The accuracy strongly depends on the calibration curve. THPC represents a very effective oxygen scavenger in

Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

CERN Document Server

Kürten, Andreas; Almeida, Joao; Kupiainen-Määttä, Oona; Dunne, Eimear M.; Duplissy, Jonathan; Williamson, Christina; Barmet, Peter; Breitenlechner, Martin; Dommen, Josef; Donahue, Neil M.; Flagan, Richard C.; Franchin, Alessandro; Gordon, Hamish; Hakala, Jani; Hansel, Armin; Heinritzi, Martin; Ickes, Luisa; Jokinen, Tuija; Kangasluoma, Juha; Kim, Jaeseok; Kirkby, Jasper; Kupc, Agnieszka; Lehtipalo, Katrianne; Leiminger, Markus; Makhmutov, Vladimir; Onnela, Antti; Ortega, Ismael K.; Petäjä, Tuukka; Praplan, Arnaud P.; Riccobono, Francesco; Rissanen, Matti P.; Rondo, Linda; Schnitzhofer, Ralf; Schobesberger, Siegfried; Smith, James N.; Steiner, Gerhard; Stozhkov, Yuri; Tomé, António; Tröstl, Jasmin; Tsagkogeorgas, Georgios; Wagner, Paul E.; Wimmer, Daniela; Ye, Penglin; Baltensperger, Urs; Carslaw, Ken; Kulmala, Markku; Curtius, Joachim

2016-01-01

Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia arethought to be the dominant processes responsible for new particle formation (NPF) in the cold temperaturesof the middle and upper troposphere. Ions are also thought to be important for particle nucleation inthese regions. However, global models presently lack experimentally measured NPF rates under controlledlaboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here withdata obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets)chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. Theconditions during nucleation cover a temperature range from 208 to 298 K, sulfuric acid concentrationsbet ween 5 × 105and 1 × 109cm3, and ammonia mixing ratios from zero added ammonia, i.e., nominally purebinary, to a maximum of ~1400 parts per trillion by volume (pptv). We performed nucleation s...

MEMS-Based Boiler Operation from Low Temperature Heat Transfer and Thermal Scavenging

Directory of Open Access Journals (Sweden)

Leland Weiss

2012-04-01

Full Text Available Increasing world-wide energy use and growing population growth presents a critical need for enhanced energy efficiency and sustainability. One method to address this issue is via waste heat scavenging. In this approach, thermal energy that is normally expelled to the environment is transferred to a secondary device to produce useful power output. This paper investigates a novel MEMS-based boiler designed to operate as part of a small-scale energy scavenging system. For the first time, fabrication and operation of the boiler is presented. Boiler operation is based on capillary action that drives working fluid from surrounding reservoirs across a heated surface. Pressure is generated as working fluid transitions from liquid to vapor in an integrated steamdome. In a full system application, the steam can be made available to other MEMS-based devices to drive final power output. Capillary channels are formed from silicon substrates with 100 µm widths. Varying depths are studied that range from 57 to 170 µm. Operation of the boiler shows increasing flow-rates with increasing capillary channel depths. Maximum fluid mass transfer rates are 12.26 mg/s from 170 µm channels, an increase of 28% over 57 µm channel devices. Maximum pressures achieved during operation are 229 Pa.

Free radical-scavenging delta-lactones from Boletus calopus.

Science.gov (United States)

Kim, Jin-Woo; Yoo, Ick-Dong; Kim, Won-Gon

2006-12-01

The methanol extracts from the fruiting body of the mushroom Boletus calopus showed free radical-scavenging activity. Bioactivity-guided fractionation of the methanol extracts led to a new hydroxylated calopin named calopin B, along with the known delta-lactones calopin and cyclocalopin A. The structure of the new calopin analogue was elucidated by spectroscopic methods. All compounds showed potent free radical-scavenging activity against superoxide, DPPH, and ABTS radicals with IC (50) values of 1.2 - 5.4 microg/mL.

In-vitro free radical scavenging activity of biosynthesized gold and silver nanoparticles using Prunus armeniaca (apricot) fruit extract

Energy Technology Data Exchange (ETDEWEB)

Dauthal, Preeti; Mukhopadhyay, Mausumi, E-mail: mausumi_mukhopadhyay@yahoo.com [S.V. National Institute of Technology, Department of Chemical Engineering (India)

2013-01-15

In-vitro free radical scavenging activity of biosynthesized gold (Au-NPs) and silver (Ag-NPs) nanoparticles was investigated in the present study. Natural precursor Prunus armeniaca (apricot) fruit extract was used as a reducing agent for the nanoparticle synthesis. The free radical scavenging activity of the nanoparticles were observed by modified 1,1 Prime -diphynyl-2-picrylhydrazyl, DPPH and 2,2 Prime -azinobis (3-ethylbenzothiazoline-6-sulfonic acid), ABTS assay. The synthesized nanoparticles were characterized by UV-Visible spectroscopy, dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy, and fourier transform infrared spectroscopy (FTIR). Appearance of optical absorption peak at 537 nm (2.20 keV) and 435 nm (3 keV) within 0.08 and 0.5 h of reaction time was confirmed the presence of metallic Au and Ag nanoclusters, respectively. Nearly spherical nanoparticles with majority of particle below 20 nm (TEM) for both Au-NPs and Ag-NPs were synthesized. XRD pattern confirmed the existence of pure nanocrystalline Au-NPs while few additional peaks in the vicinity of fcc silver-speculated crystallization of metalloproteins of fruit extract on the surface of the Ag-NPs and vice versa. FTIR spectra was supported the role of amino acids of protein/enzymes of fruit extract for synthesis and stabilization of nanoparticles. Dose-dependent scavenging activity was observed for Au-NPs and Ag-NPs in both DPPH and ABTS in-vitro assay. 50 % scavenging activity for DPPH were 11.27 and 16.18 mg and for ABTS 3.40 and 7.12 mg with Au-NPs and Ag-NPs, respectively.

A comment on "Novel scavenger removal trials increase wind turbine-caused avian fatality estimates"

Science.gov (United States)

Huso, Manuela M.P.; Erickson, Wallace P.

2013-01-01

In a recent paper, Smallwood et al. (2010) conducted a study to compare their “novel” approach to conducting carcass removal trials with what they term the “conventional” approach and to evaluate the effects of the different methods on estimated avian fatality at a wind power facility in California. A quick glance at Table 3 that succinctly summarizes their results and provides estimated fatality rates and 80% confidence intervals calculated using the 2 methods reveals a surprising result. The confidence intervals of all of their estimates and most of the conventional estimates extend below 0. These results imply that wind turbines may have the capacity to create live birds. But a more likely interpretation is that a serious error occurred in the calculation of either the average fatality rate or its standard error or both. Further evaluation of their methods reveals that the scientific basis for concluding that “many estimates of scavenger removal rates prior to [their] study were likely biased low due to scavenger swamping” and “previously reported estimates of avian fatality rates … should be adjusted upwards” was not evident in their analysis and results. Their comparison to conventional approaches was not applicable, their statistical models were questionable, and the conclusions they drew were unsupported.

pH-dependent radical scavenging capacity of green tea catechins

NARCIS (Netherlands)

Muzolf, M.; Szymusiak, H.; Gliszczynska-Swiglo, A.; Rietjens, I.M.C.M.; Tyrakowska, B.

2008-01-01

The effect of pH on the radical scavenging capacity of green tea catechins was investigated using experimental as well as theoretical methods. It was shown that the radical scavenging capacity of the catechins, quantified by the TEAC value, increases with increasing pH of the medium. Comparison of

Scavenging Capacities of Some Wines and Wine Phenolic Extracts

Directory of Open Access Journals (Sweden)

Ioannis G. Roussis

2005-01-01

Full Text Available The aim of this study was to assess the ability of different wines – a sweet red, a dry red, a sweet white, and a dry white – to scavenge the stable 1,1’-diphenyl-2-picryl-hydrazyl radical (DPPH. and to determine their phenolic composition. Both red wines contained, apart from anthocyanins, also higher concentration of total phenolics, tartaric esters, and flavonols than the two white wines. All wines exhibited scavenging activity analogous to their total phenolic content. However, their phenolics differed in antiradical potency, which was visible in their EC50 values. The dry red wine, Xinomavro, had a lower EC50 value, indicating the higher antiradical potency of its phenolics. The scavenging capacities of phenolic extracts from Xinomavro red wine on hydroxyl radicals, superoxide radicals, and singlet oxygen were also assessed. Wine total extract was fractionated by extraction, and each of the three fractions was then subfractionated by column chromatography into two subfractions. Wine total extract, and its fractions and subfractions exhibited scavenging capacity on hydroxyl radicals, superoxide radicals, and singlet oxygen, indicating the activity of many wine phenolics. The most active wine extracts towards hydroxyl radicals were characterized by the high peaks of flavanols, anthocyanins and flavonols in their HPLC-DAD chromatograms. The most active extract towards superoxide radicals was rich in flavanols and anthocyanins. The characteristic phenolics of the most active wine extracts towards singlet oxygen were flavanols, flavonols and phenolic acids. The ability of all red wine phenolic extracts to scavenge singlet oxygen, along with hydroxyl and superoxide radicals, emphasizes its health functionality.

An inverse modeling procedure to determine particle growth and nucleation rates from measured aerosol size distributions

Directory of Open Access Journals (Sweden)

B. Verheggen

2006-01-01

Full Text Available Classical nucleation theory is unable to explain the ubiquity of nucleation events observed in the atmosphere. This shows a need for an empirical determination of the nucleation rate. Here we present a novel inverse modeling procedure to determine particle nucleation and growth rates based on consecutive measurements of the aerosol size distribution. The particle growth rate is determined by regression analysis of the measured change in the aerosol size distribution over time, taking into account the effects of processes such as coagulation, deposition and/or dilution. This allows the growth rate to be determined with a higher time-resolution than can be deduced from inspecting contour plots ('banana-plots''. Knowing the growth rate as a function of time enables the evaluation of the time of nucleation of measured particles of a certain size. The nucleation rate is then obtained by integrating the particle losses from time of measurement to time of nucleation. The regression analysis can also be used to determine or verify the optimum value of other parameters of interest, such as the wall loss or coagulation rate constants. As an example, the method is applied to smog chamber measurements. This program offers a powerful interpretive tool to study empirical aerosol population dynamics in general, and nucleation and growth in particular.

Trophic facilitation or limitation? Comparative effects of pumas and black bears on the scavenger community.

Science.gov (United States)

Allen, Maximilian L; Elbroch, L Mark; Wilmers, Christopher C; Wittmer, Heiko U

2014-01-01

Scavenging is a widespread behaviour and an important process influencing food webs and ecological communities. Large carnivores facilitate the movement of energy across trophic levels through the scavenging and decomposition of their killed prey, but competition with large carnivores is also likely to constrain acquisition of carrion by scavengers. We used an experimental approach based on motion-triggered video cameras at black-tailed deer (Odocoileus hemionus columbianus) carcasses to measure the comparative influences of two large carnivores in the facilitation and limitation of carrion acquisition by scavengers. We found that pumas (Puma concolor) and black bears (Ursus americanus) had different effects on their ecological communities. Pumas, as a top-level predator, facilitated the consumption of carrion by scavengers, despite significantly reducing their observed sum feeding times (165.7 min ± 21.2 SE at puma kills 264.3 min ± 30.1 SE at control carcasses). In contrast, black bears, as the dominant scavenger in the system, limited consumption of carrion by scavengers as evidenced by the observed reduction of scavenger species richness recorded at carcasses where they were present (mean = 2.33 ± 0.28 SE), compared to where they were absent (mean = 3.28 ± 0.23 SE). Black bears also had large negative effects on scavenger sum feeding times (88.5 min ± 19.8 SE at carcasses where bears were present, 372.3 min ± 50.0 SE at carcasses where bears were absent). In addition, we found that pumas and black bears both increased the nestedness (a higher level of order among species present) of the scavenger community. Our results suggest that scavengers have species-specific adaptions to exploit carrion despite large carnivores, and that large carnivores influence the structure and composition of scavenger communities. The interactions between large carnivores and scavengers should be considered in future studies of food webs and ecological communities.

Whole house particle removal and clean air delivery rates for in-duct and portable ventilation systems.

Science.gov (United States)

Macintosh, David L; Myatt, Theodore A; Ludwig, Jerry F; Baker, Brian J; Suh, Helen H; Spengler, John D

2008-11-01

A novel method for determining whole house particle removal and clean air delivery rates attributable to central and portable ventilation/air cleaning systems is described. The method is used to characterize total and air-cleaner-specific particle removal rates during operation of four in-duct air cleaners and two portable air-cleaning devices in a fully instrumented test home. Operation of in-duct and portable air cleaners typically increased particle removal rates over the baseline rates determined in the absence of operating a central fan or an indoor air cleaner. Removal rates of 0.3- to 0.5-microm particles ranged from 1.5 hr(-1) during operation of an in-duct, 5-in. pleated media filter to 7.2 hr(-1) for an in-duct electrostatic air cleaner in comparison to a baseline rate of 0 hr(-1) when the air handler was operating without a filter. Removal rates for total particulate matter less than 2.5 microm in aerodynamic diameter (PM2.5) mass concentrations were 0.5 hr(-1) under baseline conditions, 0.5 hr(-1) during operation of three portable ionic air cleaners, 1 hr(-1) for an in-duct 1-in. media filter, 2.4 hr(-1) for a single high-efficiency particle arrestance (HEPA) portable air cleaner, 4.6 hr(-1) for an in-duct 5-in. media filter, 4.7 hr(-1) during operation of five portable HEPA filters, 6.1 hr(-1) for a conventional in-duct electronic air cleaner, and 7.5 hr(-1) for a high efficiency in-duct electrostatic air cleaner. Corresponding whole house clean air delivery rates for PM2.5 attributable to the air cleaner independent of losses within the central ventilation system ranged from 2 m3/min for the conventional media filter to 32 m3/min for the high efficiency in-duct electrostatic device. Except for the portable ionic air cleaner, the devices considered here increased particle removal indoors over baseline deposition rates.

Effect of superoxide anion scavenger on rat hearts with chronic intermittent hypoxia.

Science.gov (United States)

Pai, Peiying; Lai, Ching Jung; Lin, Ching-Yuang; Liou, Yi-Fan; Huang, Chih-Yang; Lee, Shin-Da

2016-04-15

Only very limited information regarding the protective effects of the superoxide anion scavenger on chronic intermittent hypoxia-induced cardiac apoptosis is available. The purpose of this study is to evaluate the effects of the superoxide anion scavenger on cardiac apoptotic and prosurvival pathways in rats with sleep apnea. Forty-two Sprague-Dawley rats were divided into three groups, rats with normoxic exposure (Control, 21% O2, 1 mo), rats with chronic intermittent hypoxia exposure (Hypoxia, 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo), and rats with pretreatment of the superoxide anion scavenger and chronic intermittent hypoxia exposure (Hypoxia-O2 (-)-Scavenger, MnTMPyP pentachloride, 1 mg/kg ip per day; 3-7% O2vs. 21% O2per 40 s cycle, 8 h per day, 1 mo) at 5-6 mo of age. After 1 mo, the protein levels and apoptotic cells of excised hearts from three groups were measured by Western blotting and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assay. The superoxide anion scavenger decreased hypoxia-induced myocardial architecture abnormalities, left ventricular hypertrophy, and TUNEL-positive apoptosis. The superoxide anion scavenger decreased hypoxia-induced Fas ligand, Fas death receptors, Fas-associated death domain (FADD), activated caspase-8, and activated caspase-3 (Fas-dependent apoptotic pathway) as well as Bad, activated caspase-9 and activated caspase-3 (mitochondria-dependent apoptotic pathway), endonuclease G (EndoG), apoptosis-inducing factor (AIF), and TUNEL-positive apoptosis. The superoxide anion scavenger increased IGF-1, IGF-1R, p-PI3k, p-Akt, p-Bad, Bcl-2, and Bcl-xL (survival pathway). Our findings imply that the superoxide anion scavenger might prevent cardiac Fas-mediated and mitochondrial-mediated apoptosis and enhance the IGF-1-related survival pathway in chronic intermittent hypoxia. The superoxide anion scavenger may prevent chronic sleep apnea-enhanced cardiac apoptotic pathways and enhances

Impact Of Particle Agglomeration On Accumulation Rates In The Glass Discharge Riser Of HLW Melter

International Nuclear Information System (INIS)

Kruger, A. A.; Rodriguez, C. A.; Matyas, J.; Owen, A. T.; Jansik, D. P.; Lang, J. B.

2012-01-01

The major factor limiting waste loading in continuous high-level radioactive waste (HLW) melters is an accumulation of particles in the glass discharge riser during a frequent and periodic idling of more than 20 days. An excessive accumulation can produce robust layers a few centimeters thick, which may clog the riser, preventing molten glass from being poured into canisters. Since the accumulation rate is driven by the size of particles we investigated with x-ray microtomography, scanning electron microscopy, and image analysis the impact of spinel forming components, noble metals, and alumina on the size, concentration, and spatial distribution of particles, and on the accumulation rate. Increased concentrations of Fe and Ni in the baseline glass resulted in the formation of large agglomerates that grew over the time to an average size of ∼185+-155 μm, and produced >3 mm thick layer after 120 h at 850 deg C. The noble metals decreased the particle size, and therefore significantly slowed down the accumulation rate. Addition of alumina resulted in the formation of a network of spinel dendrites which prevented accumulation of particles into compact layers

238U decay series nuclides in the northeastern Arabian Sea: scavenging rates and cycling processes

International Nuclear Information System (INIS)

Sarin, M.M.; Krishnaswami, S.; Ramesh, R.; Somayajulu, B.L.K.

1994-01-01

The extent of radioactive disequilibrium between 234 Th- 238 U, 210 Po- 210 Pb and 210 Pb- 226 Ra has been measured in four vertical profiles from the northeastern Arabian Sea, a region characterized by oxygen deficient and denitrification layers at intermediate depths. The most common feature of the data is that the dissolved concentrations of the daughter nuclides are considerably less than those of their parents, exceptions being the near equilibrium or excess concentrations of 210 Po (relative to 210 Pb) at ∼ 100 m and that of 210 Pb relative to 226 Ra in surface waters. These results suggest that scavenging of dissolved 234 Th, 210 Po and 210 Pb occurs throughout the water column in the northeastern Arabian Sea. (Author)

Edaravone, a potent free radical scavenger, reacts with peroxynitrite to produce predominantly 4-NO-edaravone.

Science.gov (United States)

Fujisawa, Akio; Yamamoto, Yorihiro

2016-05-01

3-Methyl-1-phenyl-2-pyrazolin-5-one (edaravone) is used in clinical treatment of acute brain infarction to rescue the penumbra, based on its ability to prevent lipid peroxidation by scavenging lipid peroxyl radicals. Here, we show that edaravone also reacts with peroxynitrite to yield 4-NO-edaravone as the major product and 4-NO2-edaravone as a minor product. We observed little formation of 3-methyl-1-phenyl-2-pyrazolin-4,5-dione (4-oxoedaravone) and its hydrate, 2-oxo-3-(phenylhydrazono)butanoic acid, which are the major free radical-induced oxidation products of edaravone, suggesting that free radicals are not involved in the reaction with peroxynitrite. The reaction of peroxynitrite with edaravone is approximately 30-fold greater than with uric acid, a physiological peroxynitrite scavenger (reaction rate k = 1.5 × 10 (4)  M(-1) s(-1) vs. 480 M(-1) s(-1)). These results suggest that edaravone functions therapeutically as a scavenger of peroxynitrite as well as lipid peroxyl radicals, which is consistent with a report that edaravone treatment reduced levels of 3-nitrotyrosine in the cerebrospinal fluid of patients with amyotrophic lateral sclerosis.

Human macrophage scavenger receptors: Primary structure, expression, and localization in atherosclerotic lesions

International Nuclear Information System (INIS)

Matsumoto, Akiyo; Itakura, Hiroshige; Kodama, Tatsuhiko; Naito, Makoto; Takahashi, Kiyoshi; Ikemoto, Shinji; Asaoka, Hitoshi; Hayakawa, Ikuho; Kanamori, Hiroshi; Takaku, Fumimaro; Aburatani, Hiroyuki; Suzuki, Hiroshi; Kobari, Yukage; Miyai, Tatsuya; Cohen, E.H.; Wydro, R.; Housman, D.E.

1990-01-01

Two types of cDNAs for human macrophage scavenger receptors were cloned from a cDNA library derived from the phorbol ester-treated human monocytic cell line THP-1. The type I and type II human scavenger receptors encoded by these cDNAs are homologous (73% and 71% amino acid identity) to their previously characterized bovine counterparts and consist of six domains: cytoplasmic (I), membrane-spanning (II), spacer (III), α-helical coiled-coil (IV), collagen-like (V), and a type-specific C-terminal (VI). The receptor gene is located on human chromosome 8. The human receptors expressed in CHO-K1 cells mediated endocytosis of modified low density lipoproteins. Two mRNAs, 4.0 and 3.2 kilobases, have been detected in human liver, placenta, and brain. Immunohistochemical studies using an anti-peptide antibody which recognizes human scavenger receptors indicated the presence of the scavenger receptors in the macrophages of lipid-rich atherosclerotic lesions, suggesting the involvement of scavenger receptors in atherogenesis

A multiple free-radical scavenging (MULTIS) study on the antioxidant capacity of a neuroprotective drug, edaravone as compared with uric acid, glutathione, and trolox.

Science.gov (United States)

Kamogawa, Erisa; Sueishi, Yoshimi

2014-03-01

Edaravone (3-methyl-1-phenyl-2-pyrazoline-5-one) is a neuroprotective drug that has been used for brain ischemia injury treatment. Because its activity is speculated to be due to free radical scavenging activity, we carried out a quantitative determination of edaravone's free radical scavenging activity against multiple free radical species. Electron spin resonance (ESR) spin trapping-based multiple free-radical scavenging (MULTIS) method was employed, where target free radicals were hydroxyl radical, superoxide anion, alkoxyl radical, alkylperoxyl radical, methyl radical, and singlet oxygen. Edaravone showed relatively high scavenging abilities against hydroxyl radical (scavenging rate constant k=2.98×10(11) M(-1) s(-1)), singlet oxygen (k=2.75×10(7) M(-1) s(-1)), and methyl radical (k=3.00×10(7) M(-1) s(-1)). Overall, edaravone's scavenging activity against multiple free radical species is as robust as other known potent antioxidant such as uric acid, glutathione, and trolox. A radar chart illustration of the MULTIS activity relative to uric acid, glutathione, and trolox indicates that edaravone has a high and balanced antioxidant activity with low specificity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Computational study of the structure-free radical scavenging relationship of procyanidins.

Science.gov (United States)

Mendoza-Wilson, Ana María; Castro-Arredondo, Sergio Ivan; Balandrán-Quintana, René Renato

2014-10-15

Procyanidins (PCs) are effective free radical scavengers, however, their antioxidant ability is variable because they have different degrees of polymerisation, are composed by distinct types of subunits and are very susceptible to changes in conformation. In this work the structure-free radical scavenging relationship of monomers, dimers and trimers of PCs was studied through the hydrogen atom transfer (HAT), sequential proton-loss electron-transfer (SPLET) and single electron transfer followed by proton transfer (SET-PT) mechanisms in aqueous phase, employing the Density Functional Theory (DFT) computational method. The structure-free radical scavenging relationship of PCs showed a very similar behaviour in HAT and SET-PT mechanisms, but very different in the SPLET mechanism. The structural factor that showed more effects on the ability of PCs to scavenge free radicals in aqueous phase was the conformation. Copyright © 2014 Elsevier Ltd. All rights reserved.

Free radical scavenging activity and lipoxygenase inhibition of Mahonia aquifolium extract and isoquinoline alkaloids

Directory of Open Access Journals (Sweden)

Kettmann Viktor

2007-07-01

Full Text Available Abstract Roots and stem-bark of Mahonia aquifolium (Oregon grape (Berberidaceae are effectively used in the treatment of skin inflammatory conditions. In the present study, the effect of Mahonia aquifolium crude extract and its two representative alkaloid fractions containing protoberberine and bisbenzylisoquinoline (BBIQ alkaloids on activity of 12-lipoxygenase (12-LOX, was studied. The reactivity with 1,1-diphenyl-2-picryl-hydrazyl (DPPH, a free stable radical, was evaluated to elucidate the rate of possible lipid-derived radical scavenging in the mechanism of the enzyme inhibition. The results indicate that although the direct radical scavenging mechanism cannot be ruled out in the lipoxygenase inhibition by Mahonia aquifolium and its constituents, other mechanisms based on specific interaction between enzyme and alkaloids could play the critical role in the lipoxygenase inhibition rather than non-specific reactivity with free radicals.

The scavenger activities of tea polyphenol and quercetin against oxygen radicals

International Nuclear Information System (INIS)

Fang Ruoying; Cheng Jiwu; Hu Tianxi; Tu Tiecheng; Dong Jirong; Wang Wenfeng; Lin nianyun

1992-01-01

Studies of free radical biology and medicine have shown that carcinogenesis, vascular diseases of heart and brain, radiation injuries, ageing etc are strictly correlated with free radical injury of tissues. Thus, pharmacologists and biologists are focusing attention on searching for scavengers, especially naturally occurring antioxidant of oxidizing free radicals. Previous studies have indicated that phenolic antioxidants have efficient scavenger activities. Utilizing following methods including chemical luminescence, ESR spectroscopy and pulse radiolysis techniques the scavenger activities of tea polyphenols and quercetin against active species of oxygen have been studied

Washout ratio of NaCl particles by raindrops, snowflakes and fog particles obtained using the large artificial climate experiment chamber at ACEF in IES

International Nuclear Information System (INIS)

Kawabata, Hitoshi; Kondo, Kunio; Hasegawa, Hidenao; Akata, Naofumi; Chikuchi, Yuki; Hisamatsu, Shun'ichi; Inaba, Jiro; Komagata, Yuuetsu

2007-01-01

Scavenging of NaCl particles by rainfall, snowfall and fog was examined in a large artificial climate experiment chamber in which the meteorological elements were controlled. The scavenging coefficient of Na by rainfall and snowfall were obtained using Na concentrations in air and precipitation. The washout ratio of Na by fog was also measured using Na concentrations in air and fog water. The scavenging coefficients by snowfall were found to be larger than those by rainfall, and showed that the removal efficiency of the former was higher than that of the latter. The coefficients by both rainfall and snowfall increased linearly with precipitation intensity. When the average diameters of fog droplets were the same, the washout ratio of Na by fog increased with fog liquid water content. On the other hand, when liquid water contents were the same, the washout ratio decreased with increasing average diameter of fog droplets. The washout ratio of Na by fog exponentially increased with the total surface area of fog droplets. (author)

Trophic facilitation or limitation? Comparative effects of pumas and black bears on the scavenger community.

Directory of Open Access Journals (Sweden)

Maximilian L Allen

Full Text Available Scavenging is a widespread behaviour and an important process influencing food webs and ecological communities. Large carnivores facilitate the movement of energy across trophic levels through the scavenging and decomposition of their killed prey, but competition with large carnivores is also likely to constrain acquisition of carrion by scavengers. We used an experimental approach based on motion-triggered video cameras at black-tailed deer (Odocoileus hemionus columbianus carcasses to measure the comparative influences of two large carnivores in the facilitation and limitation of carrion acquisition by scavengers. We found that pumas (Puma concolor and black bears (Ursus americanus had different effects on their ecological communities. Pumas, as a top-level predator, facilitated the consumption of carrion by scavengers, despite significantly reducing their observed sum feeding times (165.7 min ± 21.2 SE at puma kills 264.3 min ± 30.1 SE at control carcasses. In contrast, black bears, as the dominant scavenger in the system, limited consumption of carrion by scavengers as evidenced by the observed reduction of scavenger species richness recorded at carcasses where they were present (mean = 2.33 ± 0.28 SE, compared to where they were absent (mean = 3.28 ± 0.23 SE. Black bears also had large negative effects on scavenger sum feeding times (88.5 min ± 19.8 SE at carcasses where bears were present, 372.3 min ± 50.0 SE at carcasses where bears were absent. In addition, we found that pumas and black bears both increased the nestedness (a higher level of order among species present of the scavenger community. Our results suggest that scavengers have species-specific adaptions to exploit carrion despite large carnivores, and that large carnivores influence the structure and composition of scavenger communities. The interactions between large carnivores and scavengers should be considered in future studies of food webs and ecological communities.

Mobile vapor recovery and vapor scavenging unit

International Nuclear Information System (INIS)

Stokes, C.A.; Steppe, D.E.

1991-01-01

This patent describes a mobile anti- pollution apparatus, for the recovery of hydrocarbon emissions. It comprises a mobile platform upon which is mounted a vapor recovery unit for recovering vapors including light hydrocarbons, the vapor recovery unit having an inlet and an outlet end, the inlet end adapted for coupling to an external source of hydrocarbon vapor emissions to recover a portion of the vapors including light hydrocarbons emitted therefrom, and the outlet end adapted for connection to a means for conveying unrecovered vapors to a vapor scavenging unit, the vapor scavenging unit comprising an internal combustion engine adapted for utilizing light hydrocarbon in the unrecovered vapors exiting from the vapor recovery unit as supplemental fuel

Scavenging of radionuclides in the marine environment, (1)

International Nuclear Information System (INIS)

Mahara, Yasunori

1989-01-01

It is very important to predict diffusion, scavenging and accumulation of the long lives radionuclides which may be discharged from the reprocessing plant in the marine environment, for the purpose of polishing up methods of the radiation does estimation to the high quality stage. This study reports that distribution and behavior of transuranic elements, which are extremely harmful for the human beings and are discharged probably from the reprocessing plant, are investigated in both the survey of bibliography and the in-situ observation. Results of the field observation on the distribution of transuranic elements in the marine show that plutonium and americium are easily scavenged from the sea water and are accumulated on the sea bottom. Transuranic elements, which are originated from fallout and are discharged from the reprocessing plant, have generally the similar distribution in the marine and the same chemical behavior. This facts suggest that the fallout data which are probably and easily collected in the world are available for fabrication of the scavenging model for transuranic elements discharged from the reprocessing plants. (author)

Scavenger Receptor CD163 and Its Biological Functions

Directory of Open Access Journals (Sweden)

Gabriela Onofre

2009-01-01

Full Text Available CD163 is a member of scavenger receptor super family class B of the first subgroup. It is mapped to the region p13 on chromosome 12. Five different isoforms of CD163 have been described, which differ in the structure of their cytoplasmic domains and putative phosporylation sites. This scavenger receptor is selectively expressed on cells of monocytes and macrophages lineage exclusively. CD163 immunological function is essentially homeostatic. It also has other functions because participates in adhesion to endothelial cells, in tolerance induction and tissues regeneration. Other very important function of CD163 is the clearance of hemoglobin in its cell-free form and participation in anti-inflammation in its soluble form, exhibiting cytokine-like functions. We review the biological functions of CD163 which have been discovered until now. It seems apparent from this review that CD163 scavenger receptor can be used as biomarker in different diseases and as a valuable diagnostic parameter for prognosis of many diseases especially inflammatory disorders and sepsis.

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

Science.gov (United States)

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

2012-08-15

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

The effect of coarse second-phase particles on the rate of grain refinement during severe deformation processing

DEFF Research Database (Denmark)

Apps, P.J.; Bowen, Jacob R.; Prangnell, P.B.

2003-01-01

The effect of second-phase particles on the rate of grain refinement during severe deformation processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg a...... by an effective strain of only five in the particle-containing alloy, compared to ten in the single-phase material. The mechanisms that contribute to this acceleration of the grain refinement process are discussed.......The effect of second-phase particles on the rate of grain refinement during severe deformation processing has been investigated, by comparing the microstructure evolution in an AA8079 aluminium alloy, containing 2.5 vol.% of ~2 μm particles, with that in a high purity, single-phase, Al-0.13% Mg...... alloy, deformed identically by ECAE to an effective strain of ten. The materials were analysed by high-resolution EBSD orientation mapping, which revealed that grain refinement occurred at a dramatically higher rate in the particle-containing alloy. A submicron grain structure could be achieved...

Plate-out rates of radon progeny and particles in a spherical chamber

International Nuclear Information System (INIS)

Cheng, Y.S.; Chen, B.T.

1990-01-01

In indoor and mining environments, deposition or ''plate-out'' of radon progeny onto walls occurs simultaneously with attachment of the radon progeny to airborne particles. Attachment and plate-out processes affect the atmosphere in which radon exposures takes place by reducing concentrations and shifting activity size distributions. Both processes have important consequences in determining the deposition pattern and initial dose of inhaled radon progeny. Theoretical deposition models show that turbulence and natural convection in a room are the major factors that influence plate-out rates. Here we describe plate-out measurements for radon progeny and aerosol particles in a spherical chamber under controlled laboratory conditions. The temperature and velocity profiles in still and turbulent air were monitored. A 161-liter spherical aluminum chamber was used to study the mixing. During mixing, air velocity was detected when rotational speeds were higher than 500 rpm. Monodisperse silver aerosols and polystyrene latex particles in the size range of 5 nm to 2 μm were used in the deposition study. Radon-220 progeny were generated by passing Rn-220 gas into the chamber and letting the gas decay into 212 Pb. The deposition rates of the particles and radon progeny ( 212 Pb) in the chamber were determined by monitoring the concentration decay of the aerosol as a function of time

Optimization of free radical scavenging capacity and pH of Hylocereus polyrhizus peel by Response Surface Methodology

Science.gov (United States)

Putranto, A. W.; Dewi, S. R.; Puspitasari, Y.; Nuriah, F. A.

2018-03-01

Red dragon fruit (Hylocereus polyrhizus) peel, a by-product of juice processing, contains a high antioxidant that can be used for nutraceuticals. Hence, it is important to extract and investigate its antioxidant stability. The aim of this study was to optimize the free radical scavenging capacity and pH of H. polyrhizus peel extract using Central Composite Design (CCD) under Response Surface Methodology (RSM). The extraction of H. polyrhizus peel was done by using green-Pulsed Electric Field (PEF)-assisted extraction method. Factors optimized were electric field strength (kV/cm) and extraction time (seconds). The result showed that the correlation between responses (free radical-scavenging capacity and pH) and two factors was quadratic model. The optimum conditions was obtained at the electric field strength of 3.96 kV/cm, and treatment time of 31.9 seconds. Under these conditions, the actual free radical-scavenging capacity and pH were 75.86 ± 0.2 % and 4.8, respectively. The verification model showed that the actual values are in accordance with the predicted values, and have error rate values of free radical-scavenging capacity and pH responses were 0.1% and 3.98%, respectively. We suggest to extract the H. polyrhizus peel using a green and non-thermal extraction technology, PEF-assisted extraction, for research, food applications and nutraceuticals industry.

Environment, urban poverty and scavenging: review of relationship and its effectiveness

International Nuclear Information System (INIS)

Chamhuri Siwar; Amzad Hossain; Norshamleeda Chamhuri

2001-01-01

Urban poverty and environment is interrelated to each other. Environmental degradation is a crucial factor for urban poverty and vice-versa. The generation of solid waste all over the world has reached an alarming proportion and constitutes one of the world's greatest sources of environmental degradation (fagan, 1974). Solid waste is one of the three major environmental problems faced by municipalities in Malaysia (World Bank, 1993) which is one of the major cause or contributor to urban poverty. However, urban solid waste consists of two strata such as source of environmental degradation and income generating agents for urban poor scavengers. In Malaysia, full-time and part-time scavengers are recycling 6% of total generated residential solid waste in some selected areas other wise its emitted or disposed to the environment. On the other hand, by doing this work full-time scavengers are earning wages of RM750 per month which is equal to that of the majority of Third world urbanities; part-time scavengers are earning 33% of their daily income. This paper discusses a theoretical framework of the relationship of environment and urban poverty. Policies, issues and some case studies of scavenging as a means of urban poverty reduction and environmental improvements of sustainable urban development are also explored. (Author)

Collaborative Project: Understanding the Chemical Processes tat Affect Growth rates of Freshly Nucleated Particles

Energy Technology Data Exchange (ETDEWEB)

McMurry, Peter [Univ. of Minnesota, Minneapolis, MN (United States); Smuth, James [University Corporation for Atmospheric Research, Irvine, CA (United States)

2015-11-12

This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate.

Different Roles of Endo- and Exo-cyclic Double Bonds in Limonene Ozonolysis System: Effect of Water and OH Radical Scavengers

Science.gov (United States)

Gong, Y.; Li, H.; Chen, Z.

2017-12-01

Limonene, as an important monoterpene, has a high emission rate both from biogenic and anthropogenic sources. Its doubly unsaturated structure leads to a high potential for secondary organic aerosol formation and a detailed understanding of roles of endo- and exo-cyclic double bonds in limonene ozonolysis is in urgent need. This study provided new insights into the mechanism and effect of both unsaturated bonds oxidation. A low and a high ratio set of [O3]/[limonene] experiments in the presence or absence of OH scavenger (2-butanol or cyclohexane) in the relative humidity (RH) range of 0-90% were conducted. Molar yields of hydrogen peroxide (H2O2) and hydromethyl hydroperoxide (HMHP) both increased rapidly as RH rose from 0 to 50%, then reached a plateau above 70% RH, while peroxyformic acid (PFA) and peroxyacetic acid (PAA) kept increasing with RH. The ozonolysis of exocyclic double bonds showed larger capacity for producing these peroxides than endocyclic ones, resulting in significantly higher yields of H2O2, HMHP, PFA and PAA in limonene ozonolysis than α-pinene when ozone was sufficient. The SOA mass fraction of total peroxides was 50% at high [O3]/[limonene] ratio, whereas only 12% at low ratio. The gas-particle partitioning coefficient of undetected peroxides rose up from (0.8-2.0)×10-3m3μg-1 at 0% RH to (4.0-5.2)×10-3m3μg-1 at 90% RH, indicating some water-dependent channels contributed low-volatility peroxides formation. A box model was employed to simulate the reaction system, and the results obviously underestimated the yield of H2O2, whilst overestimated the yield of undetected peroxides. It is interesting to note that SOA produced at high [O3]/[limonene] ratio could generate considerable amount of H2O2 in the aqueous phase, which may be another source of H2O2 in cloud drops. To elucidate the mechanism further, the yield of OH radicals formed from endocyclic double bonds was found to be about 3 times larger than that from exocyclic double bonds

Ground squirrel shooting and potential lead exposure in breeding avian scavengers

Science.gov (United States)

Herring, Garth; Eagles-Smith, Collin A.; Wagner, Mason T.

2016-01-01

Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding’s ground squirrels (Spermophilus beldingi) are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb)-based bullets may pose a risk to avian scavengers if they consume carcasses containing Pb fragments. To assess the potential risk to breeding avian scavengers we developed a model to estimate the number, mass, and distribution of Pb fragments in shot ground squirrels using radiographic images. Eighty percent of shot carcasses contained detectible Pb fragments with an average of 38.6 mg of Pb fragments. Seven percent of all carcasses contained Pb fragment masses exceeding a lethal dose for a model raptor nestling (e.g. American kestrel Falco sparverius). Bullet type did not influence the number of fragments in shot ground squirrels, but did influence the mass of fragments retained. Belding’s ground squirrels shot with .17 Super Mag and unknown ammunition types contained over 28 and 17 times more mass of Pb fragments than those shot with .22 solid and .22 hollow point bullets, respectively. Ground squirrel body mass was positively correlated with both the number and mass of Pb fragments in carcasses, increasing on average by 76% and 56% respectively across the range of carcass masses. Although the mass of Pb retained in ground squirrel carcasses was small relative to the original bullet mass, avian scavenger nestlings that frequently consume shot ground squirrels may be at risk for Pb-induced effects (e.g., physiology, growth, or survival). Using modeling efforts we found that if nestling golden eagles (Aquila chrysaetos), red-tailed hawks (Buteo jamaicensis), and Swainson’s hawks (B. swainsoni) consumed shot ground squirrels proportionately to the nestling’s mass, energy needs

Ground Squirrel Shooting and Potential Lead Exposure in Breeding Avian Scavengers.

Directory of Open Access Journals (Sweden)

Garth Herring

Full Text Available Recreational ground squirrel shooting is a popular activity throughout the western United States and serves as a tool for managing ground squirrel populations in agricultural regions. Belding's ground squirrels (Spermophilus beldingi are routinely shot in California, Nevada, and Oregon across habitats that overlap with breeding avian scavengers. Ground squirrels shot with lead (Pb-based bullets may pose a risk to avian scavengers if they consume carcasses containing Pb fragments. To assess the potential risk to breeding avian scavengers we developed a model to estimate the number, mass, and distribution of Pb fragments in shot ground squirrels using radiographic images. Eighty percent of shot carcasses contained detectible Pb fragments with an average of 38.6 mg of Pb fragments. Seven percent of all carcasses contained Pb fragment masses exceeding a lethal dose for a model raptor nestling (e.g. American kestrel Falco sparverius. Bullet type did not influence the number of fragments in shot ground squirrels, but did influence the mass of fragments retained. Belding's ground squirrels shot with .17 Super Mag and unknown ammunition types contained over 28 and 17 times more mass of Pb fragments than those shot with .22 solid and .22 hollow point bullets, respectively. Ground squirrel body mass was positively correlated with both the number and mass of Pb fragments in carcasses, increasing on average by 76% and 56% respectively across the range of carcass masses. Although the mass of Pb retained in ground squirrel carcasses was small relative to the original bullet mass, avian scavenger nestlings that frequently consume shot ground squirrels may be at risk for Pb-induced effects (e.g., physiology, growth, or survival. Using modeling efforts we found that if nestling golden eagles (Aquila chrysaetos, red-tailed hawks (Buteo jamaicensis, and Swainson's hawks (B. swainsoni consumed shot ground squirrels proportionately to the nestling's mass, energy

Scavenger and antioxidant properties of prenylflavones isolated from Artocarpus heterophyllus.

Science.gov (United States)

Ko, F N; Cheng, Z J; Lin, C N; Teng, C M

1998-07-15

The antioxidant properties of prenylflavones, isolated from Artocarpus heterophyllus Lam., was evaluated in this study. Among them, artocarpine, artocarpetin, artocarpetin A, and cycloheterophyllin diacetate and peracetate had no effect on iron-induced lipid peroxidation in rat brain homogenate. They also did not scavenge the stable free radical 1,1-diphenyl-2-picrylhydrazyl. In contrast, cycloheterophyllin and artonins A and B inhibited iron-induced lipid peroxidation in rat brain homogenate and scavenged 1,1-diphenyl-2-picrylhydrazyl. They also scavenged peroxyl radicals and hydroxyl radicals that were generated by 2,2'-azobis(2-amidinopropane) dihydrochloride and the Fe3+-ascorbate-EDTA-H2O2 system, respectively. However, they did not inhibit xanthine oxidase activity or scavenge superoxide anion, hydrogen peroxide, carbon radical, or peroxyl radicals derived from 2,2'-azobis(2,4-dimethylvaleronitrile) in hexane. Moreover, cycloheterophyllin and artonins A and B inhibited copper-catalyzed oxidation of human low-density lipoprotein, as measured by fluorescence intensity, thiobarbituric acid-reactive substance and conjugated-diene formations and electrophoretic mobility. It is concluded that cycloheterophyllin and artonins A and B serve as powerful antioxidants against lipid peroxidation when biomembranes are exposed to oxygen radicals.

Isolation and Structure Elucidation of Radical Scavengers from Thymus vulgaris Leaves

NARCIS (Netherlands)

Dapkevicius, A.; Beek, van T.A.; Lelyveld, G.P.; Veldhuizen, van A.; Groot, de Æ.; Linssen, J.P.H.; Venskutonis, R.

2002-01-01

2,2-Diphenyl-1-picrylhydrazyl radical (DPPH*) scavenging activity-guided fractionation of a leaf extract of Thymus vulgaris led to the isolation of the radical scavengers rosmarinic acid 1, eriodictyol, taxifolin, luteolin 7-glucuronide, p-cymene 2,3-diol, p-cymene 2,3-diol 6-6'-dimer, carvacrol,

Scavenging processes in high speed two-stroke engines studied with laser diagnostics

Energy Technology Data Exchange (ETDEWEB)

Ekenberg, M.

1998-12-31

The major problem with the carburetted two-stroke engine is the short-circuiting of fuel that occurs during the scavenging phase. This leads to large emissions of unburned hydrocarbons. The object of this thesis has been to map the flow behaviour in the cylinder during the scavenging phase, and to detect differences between different cylinder designs. The measurement techniques used has been Laser Doppler Velocimetry (LDV), Laser Induced Fluorescence (LIF) and Laser Sheet Droplet Illumination (LSDI). Of these measurement methods, LDV and LSDI has been used inside the cylinder. LIF was used outside the exhaust port. All measurements were performed in engines running at their rated speeds, 9000 rpm for three of the designs and 5800 rpm for one design. All engines were run at full load with combustion. The LDV measurements inside the cylinder show that cylinders with cup handle transfer channels have a flow pattern inside the cylinder that gives less short-circuiting, and hence less emissions of hydrocarbons, than the cylinder with open transfer channels has. The LIF measurements outside the exhaust port show that the HC emissions that are caused by short-circuiting comes earlier in the scavenging phase for the cylinder with open transfer channels than is the case for the cylinders with cup handle transfer channels. The LSDI measurements in the cylinder give the transfer channel flow angle, for the cylinders with cup handle transfer channels. For the cylinder with open transfer channels, the results are not as useful; fuel droplet vaporization close to the exhaust port ruins the results 35 refs, 43 figs

The TDF System for Thermonuclear Plasma Reaction Rates, Mean Energies and Two-Body Final State Particle Spectra

International Nuclear Information System (INIS)

Warshaw, S I

2001-01-01

The rate of thermonuclear reactions in hot plasmas as a function of local plasma temperature determines the way in which thermonuclear ignition and burning proceeds in the plasma. The conventional model approach to calculating these rates is to assume that the reacting nuclei in the plasma are in Maxwellian equilibrium at some well-defined plasma temperature, over which the statistical average of the reaction rate quantity σv is calculated, where σ is the cross-section for the reaction to proceed at the relative velocity v between the reacting particles. This approach is well-understood and is the basis for much nuclear fusion and astrophysical nuclear reaction rate data. The Thermonuclear Data File (TDF) system developed at the Lawrence Livermore National Laboratory (Warshaw 1991), which is the topic of this report, contains data on the Maxwellian-averaged thermonuclear reaction rates for various light nuclear reactions and the correspondingly Maxwellian-averaged energy spectra of the particles in the final state of those reactions as well. This spectral information closely models the output particle and energy distributions in a burning plasma, and therefore leads to more accurate computational treatments of thermonuclear burn, output particle energy deposition and diagnostics, in various contexts. In this report we review and derive the theoretical basis for calculating Maxwellian-averaged thermonuclear reaction rates, mean particle energies, and output particle spectral energy distributions for these reactions in the TDF system. The treatment of the kinematics is non-relativistic. The current version of the TDF system provides exit particle energy spectrum distributions for two-body final state reactions only. In a future report we will discuss and describe how output particle energy spectra for three- and four-body final states can be developed for the TDF system. We also include in this report a description of the algorithmic implementation of the TDF

Fatal embryo chondral damage associated with fluoroquinolones in eggs of threatened avian scavengers

International Nuclear Information System (INIS)

Lemus, J.A.; Blanco, G.; Arroyo, B.; Martinez, F.; Grande, J.

2009-01-01

Stabled livestock reared in housed conditions are often subjected to intensive treatments with veterinary drug, which residues may be present in livestock meat ingested by scavengers, but nothing is known about their presence in eggs of wild birds and their potential detrimental effects on breeding success. We searched for residues of veterinary drugs and other toxicants in infertile and embryonated unhatched eggs of griffon vultures (Gyps fulvus) and red kites (Milvus milvus), two threatened avian scavengers. Quinolones (ciprofloxacin and enrofloxacin) were found in most unhatched eggs of both scavenger species clearly associated with severe alterations in the development of embryo cartilage and bones that could preclude embryo movements and subsequently normal development, pre-hatch position and successful hatching. The detrimental effects on developing eggs of veterinary drugs from livestock operations may help to explain reduced breeding success of avian scavengers. - Fluoroquinolones used in livestock farming and found in eggs of avian scavenger caused severe alterations in embryo cartilage and bone development.

Fatal embryo chondral damage associated with fluoroquinolones in eggs of threatened avian scavengers

Energy Technology Data Exchange (ETDEWEB)

Lemus, J.A. [Departamento de Ecologia Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), J. Gutierrez Abascal 2, 28006 Madrid (Spain); Blanco, G., E-mail: gublanco2@yahoo.e [Departamento de Ecologia Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), J. Gutierrez Abascal 2, 28006 Madrid (Spain); Arroyo, B.; Martinez, F.; Grande, J. [Departamento de Ecologia Evolutiva, Museo Nacional de Ciencias Naturales (CSIC), J. Gutierrez Abascal 2, 28006 Madrid (Spain)

2009-08-15

Stabled livestock reared in housed conditions are often subjected to intensive treatments with veterinary drug, which residues may be present in livestock meat ingested by scavengers, but nothing is known about their presence in eggs of wild birds and their potential detrimental effects on breeding success. We searched for residues of veterinary drugs and other toxicants in infertile and embryonated unhatched eggs of griffon vultures (Gyps fulvus) and red kites (Milvus milvus), two threatened avian scavengers. Quinolones (ciprofloxacin and enrofloxacin) were found in most unhatched eggs of both scavenger species clearly associated with severe alterations in the development of embryo cartilage and bones that could preclude embryo movements and subsequently normal development, pre-hatch position and successful hatching. The detrimental effects on developing eggs of veterinary drugs from livestock operations may help to explain reduced breeding success of avian scavengers. - Fluoroquinolones used in livestock farming and found in eggs of avian scavenger caused severe alterations in embryo cartilage and bone development.

Study of influence of catechins on bystander responses in alpha-particle radiobiological experiments using thin PADC films

Energy Technology Data Exchange (ETDEWEB)

Law, Y.L. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong); Yu, K.N., E-mail: peter.yu@cityu.edu.h [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong (Hong Kong)

2009-10-15

In this study, Chinese hamster ovary (CHO) cells were cultured in custom-made petri dishes with thin PADC films as substrates. Alpha particles with energies of 5 MeV were then irradiated from the bottom of PADC films. The DNA strand breaks in the bystander cells induced by irradiation were quantified with the use of terminal dUTP transferase-mediated nick end-labeling (TUNEL) assay. To study the influence of catechins on the bystander responses, catechins were added into the medium before alpha-particle irradiation of the cells. Fewer DNA strand breaks in the bystander cells were observed. As catechins are ROS (reactive oxygen species)-scavengers, the studied bystander cells might have been protected from radiation through scavenging of ROS by catechins.

Study of influence of catechins on bystander responses in alpha-particle radiobiological experiments using thin PADC films

International Nuclear Information System (INIS)

Law, Y.L.; Yu, K.N.

2009-01-01

In this study, Chinese hamster ovary (CHO) cells were cultured in custom-made petri dishes with thin PADC films as substrates. Alpha particles with energies of 5 MeV were then irradiated from the bottom of PADC films. The DNA strand breaks in the bystander cells induced by irradiation were quantified with the use of terminal dUTP transferase-mediated nick end-labeling (TUNEL) assay. To study the influence of catechins on the bystander responses, catechins were added into the medium before alpha-particle irradiation of the cells. Fewer DNA strand breaks in the bystander cells were observed. As catechins are ROS (reactive oxygen species)-scavengers, the studied bystander cells might have been protected from radiation through scavenging of ROS by catechins.

Speciated particle dry deposition to the sea surface: Results from ASEPS '97

DEFF Research Database (Denmark)

Pryor, S.C.; Barthelmie, R.J.; Geernaert, L.L.S.

1999-01-01

on Precipitation Scavenging and Atmosphere-Surface Exchange Processes. AMS, Richland, Washington, USA, 12pp.) model to calculate size-segregated dry deposition of particle inorganic nitrogen compounds to the western Baltic during the late Spring of 1997 based on data collected as part of the Air-Sea Exchange...

Radical Scavenging Capacity of Wine Anthocyanins Is Strongly pH-Dependent

NARCIS (Netherlands)

Borowski, T.; Tyrakowska, B.; Oszmianski, J.; Rietjens, I.M.C.M.

2005-01-01

The radical scavenging capacity of red wine anthocyanins was quantified by the so-called TEAC assay with special emphasis on the influence of pH and conjugation on this activity. The pH appears to be a dominant factor in the radical scavenging capacity of wine anthocyanins, with higher pH values

Numerical Investigation of the Scavenging Process in Marine Two-Stroke Diesel Engines

DEFF Research Database (Denmark)

Andersen, Fredrik Herland; Hult, Johan; Nogenmyr, Karl-Johan

2013-01-01

The scavenging process is an integral part of any two-stroke internal combustion engine cycle whether it is spark ignited or compression ignited. The scavenging process is responsible for transporting the burned gases from the previous working stroke out of the combustion chamber to allow...... for the fresh charge or fresh air to enter for the next combustion/working stroke. This implies that the scavenging process is responsible for setting the initial condition for the combustion process, consequently affecting fuel economy, power output and emission of hazardous gases. Two-stroke diesel engines...

Evaluation of salt particle collection device for preventing SCC on canister - Effect on particle collection rate by electric field

International Nuclear Information System (INIS)

Takeda, H.; Saegusa, T.

2013-01-01

Now, in Japan, while metal casks are used for spent nuclear fuel storage, a practical use of concrete casks is under review because of its cost effectiveness and procurement easiness. In reviewing the practical use, stress corrosion cracking (SCC) of a canister container in the concrete cask becomes an issue and is needed to be resolved soon. A natural ventilation system is generally adopted for the storage facilities, especially in Japan where facilities are built near coasts so that the cooling air includes sea salt particles. Therefore, the occurrence of SCC is concerned when the sea salt particles adhere to welded parts of the canisters. In this study, we proposed a salt particle collection device with low pressure loss which does not interfere with the air flow into the building or the concrete casks. The device is composed of a stack of 10 parallel stainless steel plates, the air is free to circulate in the space between them. Pressure loss tests in a laboratory and salt particle collection tests in the field have been performed. It has been clarified that the pressure loss of the device is one-thirtieth to one-twentieth of that of a commercial filter and 40% of the particles in the air could be collected and the device would not influence the heat removal performance. Moreover, we evaluated the effect of electric field on the particle collection under supposing the particle charge. In the case of electric field over 10 3 kV/m the particle collection rate could be improved dramatically

Hydrogen production over Au-loaded mesoporous-assembled SrTiO3 nanocrystal photocatalyst: Effects of molecular structure and chemical properties of hole scavengers

International Nuclear Information System (INIS)

Puangpetch, Tarawipa; Chavadej, Sumaeth; Sreethawong, Thammanoon

2011-01-01

Graphical abstract: Formic acid, which is the smallest and completely-dissociated water-soluble carboxylic acid, exhibited the highest hydrogen production enhancement ability over the 1 wt.% Au-loaded mesoporous-assembled SrTiO 3 nanocrystal photocatalyst. Display Omitted Research highlights: → The 1 wt.% Au-loaded mesoporous-assembled SrTiO 3 nanocrystal photocatalyst was synthesized. → The molecular structure and chemical properties of hole scavengers affected H 2 production rate. → Formic acid exhibited the highest photocatalytic H 2 production enhancement ability. -- Abstract: The hydrogen production via the photocatalytic water splitting under UV irradiation using different compounds as hole scavengers (including methanol, formic acid, acetic acid, propanoic acid, hydrochloric acid, and sulfuric acid) under a low concentration range ( 3 nanocrystal photocatalyst. The results indicated that the hydrogen production efficiency greatly depended on the molecular structure, chemical properties, and concentration of the hole scavengers. Formic acid, which is the smallest and completely-dissociated water-soluble carboxylic acid, exhibited the highest hydrogen production enhancement ability. The 2.5 vol.% aqueous formic acid solution system provided the highest photocatalytic hydrogen production rate.

Polyphenolic Compounds and Free Radical Scavenging Activity in Eight Lamiaceae Herbs of Manipur

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Sandhyarani Devi KHOMDRAM

2011-05-01

Full Text Available Eight plants of Lamiaceae under subfamily Nepetoideae found in Manipur, India were selected for estimation of their polyphenolic compounds and free radical scavenging activity which is expressed on dry weight basis. In this present study, the total phenol and flavonoid contents as well as the free radical scavenging activity were studied using spectrophotometric method. The total phenol content was determined based on Folin-Ciocalteau reagent, flavonoid was determined by aluminium chloride spectrophotometric method and tannin by Folin Dennis Method. The free radical scavenging activity was determined by using DPPH radical which is expressed as IC50 (μg/ml. The total phenolic content varied from 21.39±0.927 to 46.28±0.543 mg/g, flavonoids content in the selected samples varied from 13.30±0.684 to 26.03±0.217 mg/g and tannin content varied from 8.72±0.160 to 17.04±0.206 mg/g. The free radical scavenging activity among the selected samples varied from 11.67±0.221 to 38.29±0.532 μg/ml. The correlation between the free radical scavenging activity with total phenol content (R2=0.511, with flavonoids (R2=0.241 and with tannin (R2=0.690 was calculated and maximum correlation value was found between tannin content and the free radical scavenging activity of the plant samples. The result supports that tannins were more responsible for free radical scavenging activity in the presently selected plants.

Highly functionalized piperidines: Free radical scavenging, anticancer activity, DNA interaction and correlation with biological activity

OpenAIRE

Suvankar Das; Cristiane J. da Silva; Marina de M. Silva; Maria Dayanne de A. Dantas; Ângelo de Fátima; Ana Lúcia T. Góis Ruiz; Cleiton M. da Silva; João Ernesto de Carvalho; Josué C.C. Santos; Isis M. Figueiredo; Edeildo F. da Silva-Júnior; Thiago M. de Aquino; João X. de Araújo-Júnior; Goutam Brahmachari; Luzia Valentina Modolo

2018-01-01

Twenty-five piperidines were studied as potential radical scavengers and antitumor agents. Quantitative interaction of compounds with ctDNA using spectroscopic techniques was also evaluated. Our results demonstrate that the evaluated piperidines possesses different abilities to scavenge the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the anion radical superoxide (·O2−). The piperidine 19 was the most potent radical DPPH scavenger, while the most effective to ·O2− scavenger was piperidine...

Flavonoids as scavengers of nitric oxide radical.

NARCIS (Netherlands)

van Acker, S.A.B.E.; Tromp, M.N.J.L.; Haenen, G.R.M.M.; van der Vijgh, W.J.F.; Bast, A.

1995-01-01

Flavonoids are a group of naturally occurring compounds used, e.g., in the treatment of vascular endothelial damage. They are known to be excellent scavengers of oxygen free radicals. Since the nitric oxide radical (

Role of antioxidant scavenging enzymes and extracellular ...

African Journals Online (AJOL)

ChithrashreeGS

2012-08-23

Aug 23, 2012 ... peroxidase are two important antioxidant scavenging enzymes involved in ... Catalase was assayed using the method of Beers and Sizer. (1951) with .... yeast dextrose calcium carbonate agar (YDC) medium. Catalase and ...

Radiation formation of colloidal metallic particles in aqueous systems

International Nuclear Information System (INIS)

Cuba, Vaclav; Nemec, Mojmir; Gbur, Tomas; John, Jan; Pospisil, Milan; Mucka, Viliam

2008-01-01

Full text: Radiation and photochemical methods have been successfully utilized in various steps of nanoparticles preparation. Presented study deals with formation of silver nanoparticles in various aqueous solutions initiated by UV and gamma radiation. Silver nitrate and silver cyanide were used as precursors for radiation and/or photochemical reduction of Ag + ions to the metallic form. Influence of various parameters (dose of radiation, dose rate, exposition time) on nucleation and formation of colloid particles was studied. Attention was also focused on composition of irradiated solution. Aliphatic alcohols were used as scavengers of OH radicals and other oxidizing species. Various organic stabilizers of formed nanoparticles were used, among others ethylenediaminetetraacetic acid, citric acid and polyvinyl alcohol. Irradiation effects were evaluated using UV/Vis absorption spectra in colloid solution, solid phase formed after long-term irradiation was analysed via X-ray structural analysis

Uptake and metabolism of polymerized albumin by rat liver. Role of the scavenger receptor

International Nuclear Information System (INIS)

Wright, T.L.; Roll, F.J.; Jones, A.L.; Weisiger, R.A.

1988-01-01

Hepatitis B virus binds avidly to albumin polymers, which in turn may mediate viral attachment to liver cells. This hypothesis is critically dependent on prior results obtained using glutaraldehyde-polymerized human serum albumin as a model for naturally occurring albumin species. We used the perfused rat liver to characterize the uptake, cellular distribution, and metabolism of glutaraldehyde-polymerized human albumin. 125 I-glutaraldehyde-polymerized human albumin was efficiently removed from the perfusate by the liver (29% extraction). However, few autoradiographic grains were located over hepatic parenchymal cells (6%). Instead, most glutaraldehyde-polymerized human albumin appeared to be removed by endothelial (59%) or Kupffer (31%) cells. Hepatic uptake was strongly inhibited by formaldehyde-treated monomeric albumin, a known ligand of the endothelial scavenger receptor for chemically modified proteins. After uptake, most glutaraldehyde-polymerized human albumin was rapidly degraded and released into the perfusate (74% within 60 min). This process was blocked by chloroquine and leupeptin, suggesting that it involves lysosomal acid hydrolases. We conclude that glutaraldehyde-polymerized albumin is efficiently cleared and degraded by the endothelial scavenger pathway. Glutaraldehyde-polymerized albumin therefore appears to be a poor model for predicting the hepatic handling of naturally occurring albumin species bound to hepatitis B virions. Even if viral particles were to follow this pathway, few would enter parenchymal hepatocytes

Critical rate of energy loss for registration of charged particles in cellulose nitrate

International Nuclear Information System (INIS)

Knoefel, T.M.J.; Sachett, I.A.

1979-09-01

Cellulose nitrate films LR-115 type II (Kodak-Pathe) have been exposed, at right angles, to alpha-particle beams in the energy range 2.5 - 5.5 MeV. From measurements of both through etched track density, a critical rate of energy lo ss for track registration of (0.85 +- 0.05) MeV cm 2 /mg has been derived, which corresponds to a critical alpha-particle energy of (4.6 +- 0.4) MeV. These results are compatible with those obtained by other authors whenever similar etching conditions are used. The concepts of threshold rate of energy loss and a threshold energy for etched-track formation are introduced, and their values are obtained from the experiment as being (0.80 +- 0.05) MeV cm 2 /mg and (5.1 +- 0.4) Mev, respectively. In addition, the present work provides a suitable set of useful, reference data for further applications of such plastic nuclear track detector in problems concerned with the detection of low-energy alpha particles. (Author) [pt

Scavenging in the genus Natrix

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Cesar Ayres

2012-07-01

Full Text Available Scavenging is reported as an unusual behaviour of snakes. However, it is likely more common than is supposed. Here I report the use of dead newts as prey source by water snakes of the genus Natrix at a dam in north-western Spain. Juveniles and adults viperine snakes (Natrix maura, and also an adult grass snake (Natrix natrix were found feeding on newt carcasses.

Predatory blue crabs induce stronger nonconsumptive effects in eastern oysters Crassostrea virginica than scavenging blue crabs

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Avery E. Scherer

2017-02-01

Full Text Available By influencing critical prey traits such as foraging or habitat selection, predators can affect entire ecosystems, but the nature of cues that trigger prey reactions to predators are not well understood. Predators may scavenge to supplement their energetic needs and scavenging frequency may vary among individuals within a species due to preferences and prey availability. Yet prey reactions to consumers that are primarily scavengers versus those that are active foragers have not been investigated, even though variation in prey reactions to scavengers or predators might influence cascading nonconsumptive effects in food webs. Oysters Crassostrea virginica react to crab predators by growing stronger shells. We exposed oysters to exudates from crabs fed live oysters or fed aged oyster tissue to simulate scavenging, and to controls without crab cues. Oysters grew stronger shells when exposed to either crab exudate, but their shells were significantly stronger when crabs were fed live oysters. The stronger response to predators than scavengers could be due to inherent differences in diet cues representative of reduced risk in the presence of scavengers or to degradation of conspecific alarm cues in aged treatments, which may mask risk from potential predators subsisting by scavenging.

In vitro free radical scavenging activity of Ixora coccinea L

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Moni Rani Saha

2008-06-01

Full Text Available Antioxidant activity of the methanol extract of Ixora coccinea L. was determined by DPPH free radical scavenging assay, reducing power and total antioxidant capacity using phosphomolybdenum method. Preliminary phytochemical screening revealed that the extract of the flower of I. coccinea possesses flavonoids, steroids and tannin materials. The extract showed significant activities in all antioxidant assays compared to the standard antioxidant in a dose dependent manner and remarkable activities to scavenge reactive oxygen species (ROS may be attributed to the high amount of hydrophilic phenolics. In DPPH radical scavenging assay the IC50 value of the extract was found to be 100.53 μg/mL while ascorbic acid had the IC50 value 58.92 μg/mL. Moreover, I. coccinea extract showed strong reducing power and total antioxidant capacity.

Performance of zeolite scavenge column in Xe monitoring system

International Nuclear Information System (INIS)

Wang Qian; Wang Hongxia; Li Wei; Bian Zhishang

2010-01-01

In order to improve the performance of zeolite scavenge column, its ability of removal of humidity and carbon dioxide was studied by both static and dynamic approaches. The experimental results show that various factors, including the column length and diameter, the mass of zeolite, the content of water in air, the temperature rise during adsorption, and the activation effectiveness all effect the performance of zeolite column in scavenging humanity and carbon dioxide. Based on these results and previous experience, an optimized design of the zeolite column is made for use in xenon monitoring system. (authors)

Sinking rates and ballast composition of particles in the Atlantic Ocean: implications for the organic carbon fluxes to the deep ocean

Science.gov (United States)

Fischer, G.; Karakaş, G.

2009-01-01

The flux of materials to the deep sea is dominated by larger, organic-rich particles with sinking rates varying between a few meters and several hundred meters per day. Mineral ballast may regulate the transfer of organic matter and other components by determining the sinking rates, e.g. via particle density. We calculated particle sinking rates from mass flux patterns and alkenone measurements applying the results of sediment trap experiments from the Atlantic Ocean. We have indication for higher particle sinking rates in carbonate-dominated production systems when considering both regional and seasonal data. During a summer coccolithophorid bloom in the Cape Blanc coastal upwelling off Mauritania, particle sinking rates reached almost 570 m per day, most probably due the fast sedimentation of densely packed zooplankton fecal pellets, which transport high amounts of organic carbon associated with coccoliths to the deep ocean despite rather low production. During the recurring winter-spring blooms off NW Africa and in opal-rich production systems of the Southern Ocean, sinking rates of larger particles, most probably diatom aggregates, showed a tendency to lower values. However, there is no straightforward relationship between carbonate content and particle sinking rates. This could be due to the unknown composition of carbonate and/or the influence of particle size and shape on sinking rates. It also remains noticeable that the highest sinking rates occurred in dust-rich ocean regions off NW Africa, but this issue deserves further detailed field and laboratory investigations. We obtained increasing sinking rates with depth. By using a seven-compartment biogeochemical model, it was shown that the deep ocean organic carbon flux at a mesotrophic sediment trap site off Cape Blanc can be captured fairly well using seasonal variable particle sinking rates. Our model provides a total organic carbon flux of 0.29 Tg per year down to 3000 m off the NW African upwelling

Model for GCR-particle fluxes in stony meteorites and production rates of cosmogenic nuclides

International Nuclear Information System (INIS)

Reedy, R.C.

1984-01-01

A model is presented for the differential fluxes of galactic-cosmic-ray (GCR) particles with energies above 1 MeV inside any spherical stony meteorite as a function of the meteorite's radius and the sample's depth. This model is based on the Reedy-Arnold equations for the energy-dependent fluxes of GCR particles in the moon and is an extension of flux parameters that were derived for several meteorites of various sizes. This flux is used to calculate the production rates of many cosmogenic nuclides as a function of radius and depth. The peak production rates for most nuclides made by the reactions of energetic GCR particles occur near the centers of meteorites with radii of 40 to 70 g cm -2 . Although the model has some limitations, it reproduces well the basic trends for the depth-dependent production of cosmogenic nuclides in stony meteorites of various radii. These production profiles agree fairly well with measurements of cosmogenic nuclides in meteorites. Some of these production profiles are different than those calculated by others. The chemical dependence of the production rates for several nuclides varies with size and depth. 25 references, 8 figures

Influences of in-cloud aerosol scavenging parameterizations on aerosol concentrations and wet deposition in ECHAM5-HAM

Directory of Open Access Journals (Sweden)

B. Croft

2010-02-01

Full Text Available A diagnostic cloud nucleation scavenging scheme, which determines stratiform cloud scavenging ratios for both aerosol mass and number distributions, based on cloud droplet, and ice crystal number concentrations, is introduced into the ECHAM5-HAM global climate model. This scheme is coupled with a size-dependent in-cloud impaction scavenging parameterization for both cloud droplet-aerosol, and ice crystal-aerosol collisions. The aerosol mass scavenged in stratiform clouds is found to be primarily (>90% scavenged by cloud nucleation processes for all aerosol species, except for dust (50%. The aerosol number scavenged is primarily (>90% attributed to impaction. 99% of this impaction scavenging occurs in clouds with temperatures less than 273 K. Sensitivity studies are presented, which compare aerosol concentrations, burdens, and deposition for a variety of in-cloud scavenging approaches: prescribed fractions, a more computationally expensive prognostic aerosol cloud processing treatment, and the new diagnostic scheme, also with modified assumptions about in-cloud impaction and nucleation scavenging. Our results show that while uncertainties in the representation of in-cloud scavenging processes can lead to differences in the range of 20–30% for the predicted annual, global mean aerosol mass burdens, and near to 50% for accumulation mode aerosol number burden, the differences in predicted aerosol mass concentrations can be up to one order of magnitude, particularly for regions of the middle troposphere with temperatures below 273 K where mixed and ice phase clouds exist. Different parameterizations for impaction scavenging changed the predicted global, annual mean number removal attributed to ice clouds by seven-fold, and the global, annual dust mass removal attributed to impaction by two orders of magnitude. Closer agreement with observations of black carbon profiles from aircraft (increases near to one order of magnitude for mixed phase clouds

Aerosol surface area concentration: a governing factor in new particle formation in Beijing

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R. Cai

2017-10-01

Full Text Available The predominating role of aerosol Fuchs surface area, AFuchs, in determining the occurrence of new particle formation (NPF events in Beijing was elucidated in this study. The analysis was based on a field campaign from 12 March to 6 April 2016 in Beijing, during which aerosol size distributions down to  ∼  1 nm and sulfuric acid concentrations were simultaneously monitored. The 26 days were classified into 11 typical NPF days, 2 undefined days, and 13 non-event days. A dimensionless factor, LΓ, characterized by the relative ratio of the coagulation scavenging rate over the condensational growth rate (Kuang et al., 2010, was applied in this work to reveal the governing factors for NPF events in Beijing. The three parameters determining LΓ are sulfuric acid concentration, the growth enhancement factor characterized by contribution of other gaseous precursors to particle growth, Γ, and AFuchs. Different from other atmospheric environments, such as in Boulder and Hyytiälä, the daily-maximum sulfuric acid concentration and Γ in Beijing varied in a narrow range with geometric standard deviations of 1.40 and 1.31, respectively. A positive correlation between the estimated new particle formation rate, J1.5, and sulfuric acid concentration was found with a mean fitted exponent of 2.4. However, the maximum sulfuric acid concentrations on NPF days were not significantly higher (even lower, sometimes than those on non-event days, indicating that the abundance of sulfuric acid in Beijing was high enough to initiate nucleation, but may not necessarily lead to NPF events. Instead, AFuchs in Beijing varied greatly among days with a geometric standard deviation of 2.56, whereas the variabilities of AFuchs in Tecamac, Atlanta, and Boulder were reported to be much smaller. In addition, there was a good correlation between AFuchs and LΓ in Beijing (R2 = 0.88. Therefore, it was AFuchs that fundamentally determined the occurrence of NPF events

Investigation of the chemistry of liquid H{sub 2}S scavengers

Energy Technology Data Exchange (ETDEWEB)

Buhaug, Janne Bjoerntvedt

2002-07-01

The production of natural gas in the North Sea is facing a growing problem: contamination of the natural gas with dihydrogen sulfide, H{sub 2}S. As a gas reservoir is emptied, seawater containing sulfates is pumped into it, and the sulfates are reduced to dihydrogen sulfide by sulfate-reducing bacteria. Dihydrogen sulfide is then pumped up along with the oil, gas and water from the reservoir, causing severe corrosion of pipelines and contamination of the final natural gas product. Dihydrogen sulfide is extremely toxic, and in fields with especially large concentrations of H{sub 2}S this is a severe health risk for the platform workers. Hence, it is desirable to remove the dihydrogen sulfide at the earliest stage possible. There are four main methods for removing H{sub 2}S from natural gas: (1) Liquid scavengers, (2) Solid scavengers, (3) Liquid redox processes, (4) Amine / Claus catalyst. Liquid scavengers are widely used in the natural gas industry, especially at sites with relatively low concentrations of H{sub 2}S. As a rule of thumb, liquid scavengers are economically favourable at sites with a removal of less than 50 kg/day of H{sub 2}S. This thesis is concerned with the cyclic amine 1,3,5 -tris(2-hydroxyethyl)-1,3,5-triazinane, often referred to as Triazine. This is used in fields with relatively low concentration of H{sub 2}S and dominates the liquid scavenger market.

Free radical scavenging potential and HPTLC analysis of Indigofera tinctoria linn (Fabaceae

Directory of Open Access Journals (Sweden)

Sakthivel Srinivasan

2016-04-01

Full Text Available The objective of this study was to evaluate the free radical scavenging potential and high performance thin layer chromatography (HPTLC fingerprinting of Indigofera tinctoria (I. tinctoria. Phytochemical analysis was carried out using standard methods, and free radical scavenging activity of the plant was determined using 2,2-diphenyl-1-picrylhydrazy (DPPH, nitric oxide (NO and superoxide anion (O2− radical scavenging capacities. HPTLC plate was kept in CAMAG TLC Scanner 3 and the Rf values at fingerprint data were recorded by WINCATS software. Aqueous extract of I. tinctoria reliably showed the total phenolics (267.2±2.42 mg/g, flavonoids (75.43±3.36 mg/g and antioxidants (349.11±8.04 mg/g. The extract was found to have DPPH (52.08%, NO (23.12% and O2− (26.79% scavenging activities at the concentration of 250 μg/mL and the results were statistically significant compared with ascorbic acid standard (p<0.05. HPTLC results confirmed that the extract contained several potential active components such as phenols, flavonoids, saponins and terpenoids as the slides revealed multi-colored bands of varying intensities. This study confirmed that the plant had multipotential antioxidant and free radicals scavenging activities.

Particle size distribution effect on burn rate of ammonium nitrate based propellant

NARCIS (Netherlands)

Miedema, J.R.; Klein, A.J.J.; Zee, F.W.M.

1995-01-01

Burn rate control of a Phase Stabilised Ammonium Nitrate (PSAN) propellant by specific surface area (SSA) tuning of the PSAN oxidiser resulted in unexpected effects of applying a new batch of PSAN having a different particle size distribution. Analysis of the deviations and consultation of

Scavenging by spiders (Araneae) and its relationship to pest management of the brown recluse spider.

Science.gov (United States)

Vetter, Richard S

2011-06-01

Experiments reported in Sandidge (2003; Nature 426: 30) indicated that the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, preferred to scavenge dead prey over live prey and that the spiders were not detrimentally affected when fed insecticide-killed crickets. Extrapolations made in subsequent media coverage disseminating the results of this research made counter-intuitive statements that pesticide treatment in houses would increase brown recluse populations in homes. This information was presented as if the scavenging behavior was specialized in the brown recluse; however, it was more likely that this behavior has not been well studied in other species. To provide a comparison, the current laboratory study examined the likelihood of non-Loxosceles spiders to scavenge dead prey. Of 100 non-Loxosceles spiders that were tested (from 11 families, 24 genera, and at least 29 species from a variety of spider hunting guilds), 99 scavenged dead crickets when offered in petri dishes. Some of the spiders were webspinners in which real-world scavenging of dead prey is virtually impossible, yet they scavenge when given the opportunity. Therefore, scavenging is a flexible opportunistic predatory behavior that is spread across a variety of taxa and is not a unique behavior in brown recluses. These findings are discussed in relation to pest management practices.

Uses and flock management practices of scavenging chickens in Wolaita Zone of southern Ethiopia.

Science.gov (United States)

Desta, Takele Taye; Wakeyo, Oli

2012-03-01

Rearing of scavenging chickens is among the most commonly practiced farm activities in Ethiopia. This system is dominated by indigenous chickens. Output from indigenous chickens is low due to poor management and absence of intense selection that is intended to improve economically important traits. This showed that village chickens are rather evolved for adaptation traits. However, the level of risk is low, and this has made rearing of scavenging chickens a choice of farm activity for smallholder farmers. The objective of this study was to characterize the scavenging chickens' production system in Wolaita Zone. Single-visit survey involving individual interview of 119 farmers and 6 focus group discussions was used to collect the data. Our results showed that rearing of scavenging chickens was constrained especially by disease and predation problems. However, farmers proposed a set of solutions to minimize the effect of these problems. Rearing of scavenging chickens fulfils the multi-functional need of the society. This system has special features because it can sustain in its own without the need for modern commercial chicken farming facilities. However, farmers also reported the drawbacks of rearing of scavenging chickens and these mainly include uproot of garden crops and tiresomeness of the night watching. Selection of chickens was mainly depending on physically observed traits like body size and plumage colour. The initial foundation flock was mainly obtained from the local market. The ideal place for scavenging chickens production is the one that has intermediate weather condition and has some trees that can be used as shade; however, it was substantiated that it has to be free from bush and shrubs, weeds and wet lands. Therefore, these pieces of knowledge embedded among smallholder farmers need to be well documented and synthesized to design an appropriate type of technology packages that can be communicated back to farmers to improve productivity of the

Energy scavenging strain absorber: application to kinetic dielectric elastomer generator

Science.gov (United States)

Jean-Mistral, C.; Beaune, M.; Vu-Cong, T.; Sylvestre, A.

2014-03-01

Dielectric elastomer generators (DEGs) are light, compliant, silent energy scavengers. They can easily be incorporated into clothing where they could scavenge energy from the human kinetic movements for biomedical applications. Nevertheless, scavengers based on dielectric elastomers are soft electrostatic generators requiring a high voltage source to polarize them and high external strain, which constitutes the two major disadvantages of these transducers. We propose here a complete structure made up of a strain absorber, a DEG and a simple electronic power circuit. This new structure looks like a patch, can be attached on human's wear and located on the chest, knee, elbow… Our original strain absorber, inspired from a sailing boat winch, is able to heighten the external available strain with a minimal factor of 2. The DEG is made of silicone Danfoss Polypower and it has a total area of 6cm per 2.5cm sustaining a maximal strain of 50% at 1Hz. A complete electromechanical analytical model was developed for the DEG associated to this strain absorber. With a poling voltage of 800V, a scavenged energy of 0.57mJ per cycle is achieved with our complete structure. The performance of the DEG can further be improved by enhancing the imposed strain, by designing a stack structure, by using a dielectric elastomer with high dielectric permittivity.

Seasonal and interannual variability in deep ocean particle fluxes at the Oceanic Flux Program (OFP)/Bermuda Atlantic Time Series (BATS) site in the western Sargasso Sea near Bermuda

Science.gov (United States)

Conte, Maureen H.; Ralph, Nate; Ross, Edith H.

consistent with a model of rapid particle turnover and material scavenging from the suspended pool during new particle formation. We suggest that much of the deep mass flux is generated in situ by deep-dwelling zooplankton, and that mass flux, as well as scavenging of suspended materials from the deep water column, varies in proportion to changes in grazer activity. Labile, very rapidly sinking aggregates (e.g., salp fecal material) arriving in the bathypelagic zone within days of their upper ocean production may act to stimulate zooplankton grazing rates and increase large particle production and deep mass flux days to weeks in advance of the arrival of bulk of surface-produced material. This process could reconcile mean particle sinking rate estimates with the phase coherence observed between upper and deep ocean mass fluxes.

Analysis of the Scavenging Process of a Two-Stroke Free-Piston Engine Based on the Selection of Scavenging Ports or Valves

Directory of Open Access Journals (Sweden)

Boru Jia

2018-02-01

Full Text Available The free-piston engine generator (FPEG is a linear energy conversion device with the objective of utilisation within a hybrid-electric automotive vehicle power system. In this research, the piston dynamic characteristics of an FPEG is compared with that of a conventional engine (CE of the same size, and the difference in the valve timing is compared for both port scavenging type and valve scavenging type, with the exhaust valve closing timing is selected as the parameter. A zero-dimensional simulation model is developed in Ricardo WAVE software (2016.1, with the piston dynamics obtained from the simulation model in Matlab/SIMULINK (R2017a. For the CE and FEPG using scavenging ports, in order to improve its power output to the same level as that of a CE, the inlet gas pressure is suggested to be improved to above 1.2 bar, approximately 0.2 bar higher than that used for a CE. If a CE cylinder with exhaust valves is adopted or referred to during the development of an FPEG prototype, the exhaust valve is suggested to be closed earlier to improve its power output, and a higher intake pressure is also suggested if its output power is expected to be the same or higher than that of a CE.

Free radical scavenging activity and lipid peroxidation inhibition of Hypericum helianthemoides (spach Boiss

Directory of Open Access Journals (Sweden)

Soheila Moein

2015-06-01

Full Text Available Antioxidants are compounds that obstruct the oxidation of macromolecules in the body. In general, there are two categories of antioxidants, natural and synthetic. Recently, interest has been increased considerably for obtaining new natural antioxidants. In this study, the scavenging of free radicals such as DPPH, NO and OH by Hypericum helianthemoides extract was evaluated. Also, the antioxidant properties of this extract were evaluated by FRAP, FTC methods and determination phenolic compounds. The plant was collected from north of Fars Province and plant extraction was obtained using ethanol. In DPPH radical scavenging, different concentrations of the Hypericum extract were added to DPPH radical. In hydroxyl radical scavenging, Fenton reaction mixture, TCA and TBA were mixed with Hypericum extract. In nitric radical scavenging, nitropruside was mixed with Hypericum extract and then sulphanilic acid, naphthylene diamine were added. In determination of phenolic compounds, Folin-ciocalteu and sodium carbonate were added to Hypericum extract. In DPPH radical scavenging, the IC50 of Hypericum extract (309.35±6.5μg/ml was higher than the antioxidant standards, BHT (IC50=81.9±2.6 μg/ml and quercetin (IC50=60.04±6.48 μg/ml. The highest scavenging of hydroxyl radicals was observed in Hypericum extract (70.3±0.8%, 125 μg/ml. In gallic acid it was (73.8±3.3%. In 200 μg/ml of Hypericum extract scavenged NO radical (85.2±2.7%. In FRAP method, the IC50 of this extract was 109.7±10.5 μg/ml. In FTC method, the inhibition of lipid peroxidation by Hypericum extract, BHT and ascorbic acid were 59.2±2.2, 66.9±0.15, 64.06±0.02 respectively. Total phenol of the plant extract was 3±0.4 mg/g.

Role of the reaction of stabilized Criegee intermediates with peroxy radicals in particle formation and growth in air.

Science.gov (United States)

Zhao, Yue; Wingen, Lisa M; Perraud, Véronique; Greaves, John; Finlayson-Pitts, Barbara J

2015-05-21

Ozonolysis of alkenes is an important source of secondary organic aerosol (SOA) in the atmosphere. However, the mechanisms by which stabilized Criegee intermediates (SCI) react to form and grow the particles, and in particular the contributions from oligomers, are not well understood. In this study, ozonolysis of trans-3-hexene (C6H12), as a proxy for small alkenes, was investigated with an emphasis on the mechanisms of particle formation and growth. Ozonolysis experiments were carried out both in static Teflon chambers (18-20 min reaction times) and in a glass flow reactor (24 s reaction time) in the absence and presence of OH or SCI scavengers, and under different relative humidity (RH) conditions. The chemical composition of polydisperse and size-selected SOA particles was probed using different mass spectrometric techniques and infrared spectroscopy. Oligomers having SCI as the chain unit are found to be the dominant components of such SOA particles. The formation mechanism for these oligomers suggested by our results follows the sequential addition of SCI to organic peroxy (RO2) radicals, in agreement with previous studies by Moortgat and coworkers. Smaller particles are shown to have a relatively greater contribution from longer oligomers. Higher O/C ratios are observed in smaller particles and are similar to those of oligomers resulting from RO2 + nSCI, supporting a significant role for longer oligomers in particle nucleation and early growth. Under atmospherically relevant RH of 30-80%, water vapor suppresses oligomer formation through scavenging SCI, but also enhances particle nucleation. Under humid conditions, or in the presence of formic or hydrochloric acid as SCI scavengers, peroxyhemiacetals are formed by the acid-catalyzed particle phase reaction between oligomers from RO2 + nSCI and a trans-3-hexene derived carbonyl product. In contrast to the ozonolysis of trans-3-hexene, oligomerization involving RO2 + nSCI does not appear to be prevalent in the

Bubbles and Dust: Dissolution Rates of Unhydrated Volcanic Ash as a Function of Morphology, Composition, and Particle Size

Science.gov (United States)

Wygel, C. M.; Sahagian, D. L.

2017-12-01

Volcanic eruptions are natural hazards due to their explosive nature and widespread transportation and deposition of ash particles. After deposition and subsequent leaching in soils or water bodies, ash deposition positively (nutrients) and negatively (contaminants) impacts the health of flora and fauna, including humans. The effects of ash leachates have been difficult to replicate in field and laboratory studies due to the many complexities and differences between ash particles. Ash morphology is characteristic for each eruption, dependent upon eruption energy, and should play a critical role in determining leaching rates. Morphology reflects overall particle surface area, which is strongly influenced by the presence of surface dust. In addition, ash composition, which in part controls morphology and particle size, may also affect leaching rates. This study determines the extent to which ash morphology, surface area, composition, and particle size control ash dissolution rates. Further, it is necessary to determine whether compound vesicular ash particles permit water into their interior structures to understand if both the internal and external surface areas are available for leaching. To address this, six fresh, unhydrated ash samples from diverse volcanic environments and a large range in morphology, from Pele's spheres to vesicular compound ash, are tested in the laboratory. Ash morphology was characterized on the Scanning Electron Microscope (SEM) before and after leaching and surface area was quantified by Brunauer Emmett Teller (BET) analysis and with geometric calculations. Column Leachate Tests (CLT) were conducted to compare leaching rates over a range of basaltic to silicic ashes as a function of time and surface area, to recreate the effects of ash deposition in diverse volcanic environments. After the CLT, post-leaching water analyses were conducted by Ion Coupled Plasma-Mass Spectrometry (ICP-MS) and Ion Chromatography (IC). We find that leaching

In vivo heme scavenging by Staphylococcus aureus IsdC and IsdE proteins

International Nuclear Information System (INIS)

Mack, John; Vermeiren, Christie; Heinrichs, David E.; Stillman, Martin J.

2004-01-01

We report the first characterization of the in vivo porphyrin scavenging abilities of two components of a newly discovered heme scavenging system involving iron-regulated surface determinant (Isd) proteins. These proteins are present within the cell envelope of the Gram-positive human pathogen Staphylococcus aureus. IsdC and IsdE, when expressed heterologously in Escherichia coli, efficiently scavenged intracellular heme and resulted in de novo heme synthesis in excess of 100-fold above background. Magnetic circular dichroism analyses showed that the heme-binding properties of the two proteins differ significantly from one another. IsdC bound almost exclusively free-base protoporphyrin IX, whereas the IsdE protein was associated with low spin Fe(III) and Fe(II) heme. These properties provide important insight into the possible mechanisms of iron scavenging from bound heme by Isd proteins

Free radical scavenging activity of Eagle tea and their flavonoids

Directory of Open Access Journals (Sweden)

Qiong Meng

2012-06-01

Full Text Available In this study, an online HPLC-DAD-MS coupled with 2,2′-azinobis (3-ethylbenzthiazoline-6-sulfonic acid diammonium salt (ABTS assay was employed for evaluating free radical scavenging activity of Eagle tea and their active components. Twenty-three chromatographic peaks were detected, and nineteen components had free radical scavenging activity. Among them, eight compounds were identified as flavonoids (hyperin, isoquercitrin, quercitrin, quercetin, kaempferol, catechins, chlorogenic acid and epicatechin based on MS data and standard chromatographic characters.

Low frequency energy scavenging using sub-wave length scale acousto-elastic metamaterial

Directory of Open Access Journals (Sweden)

Riaz U. Ahmed

2014-11-01

Full Text Available This letter presents the possibility of energy scavenging (ES utilizing the physics of acousto-elastic metamaterial (AEMM at low frequencies (<∼3KHz. It is proposed to use the AEMM in a dual mode (Acoustic Filter and Energy Harvester, simultaneously. AEMM’s are typically reported for filtering acoustic waves by trapping or guiding the acoustic energy, whereas this letter shows that the dynamic energy trapped inside the soft constituent (matrix of metamaterials can be significantly harvested by strategically embedding piezoelectric wafers in the matrix. With unit cell AEMM model, we experimentally asserted that at lower acoustic frequencies (< ∼3 KHz, maximum power in the micro Watts (∼35µW range can be generated, whereas, recently reported phononic crystal based metamaterials harvested only nano Watt (∼30nW power against 10KΩ resistive load. Efficient energy scavengers at low acoustic frequencies are almost absent due to large required size relevant to the acoustic wavelength. Here we report sub wave length scale energy scavengers utilizing the coupled physics of local, structural and matrix resonances. Upon validation of the argument through analytical, numerical and experimental studies, a multi-frequency energy scavenger (ES with multi-cell model is designed with varying geometrical properties capable of scavenging energy (power output from ∼10µW – ∼90µW between 0.2 KHz and 1.5 KHz acoustic frequencies.

Scavenging capacity of strawberry tree (Arbutus unedo L.) leaves on free radicals.

Science.gov (United States)

Oliveira, Ivo; Coelho, Valentim; Baltasar, Raquel; Pereira, José Alberto; Baptista, Paula

2009-07-01

Despite strawberry tree (Arbutus unedo L.) leaves had a long use in traditional medicine due to its antiseptic, diuretic, astringent and depurative properties, the potential of their antioxidant activity are still lacking. Our study goals to assess the antioxidant and free radical scavenging potential of water, ethanol, methanol and diethyl ether extracts of A. unedo leaves. Total phenols content was achieved spectrophotometrically using Folin-Ciocalteau reagent with gallic acid as standard. Antioxidant activity was evaluated using three different methods: reducing power of iron (III)/ferricyanide complex assay, scavenging effect on DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals and scavenging effect on superoxide radicals by using the PMS-NADH-nitroblue tetrazolium system. Ethanol extracts of A. unedo leaves were the highest in reducing power (IC(50) 232.7 microg/mL) and DPPH scavenging effect (IC(50) 63.2 microg/mL) followed by water extracts (with IC(50) of 287.7 and 73.7 microg/mL, respectively); whereas diethyl ether extracts were the lowest. In the scavenging on superoxide radical assay, methanol extracts obtained the best results (IC(50) 6.9 microg/mL). For all the methods tested the antioxidant activity was concentration dependent. In accordance with antioxidant activity, highest total phenols content were found in ethanol, followed by water, methanol and diethyl ether extract. The results indicated that A. unedo leaves are a potential source of natural antioxidants.

Contaminant degradation by irradiated semiconducting silver chloride particles: kinetics and modelling.

Science.gov (United States)

Ma, Tian; Garg, Shikha; Miller, Christopher J; Waite, T David

2015-05-15

The kinetics and mechanism of light-mediated formic acid (HCOO(-)) degradation in the presence of semiconducting silver chloride particles are investigated in this study. Our experimental results show that visible-light irradiation of AgCl(s) results in generation of holes and electrons with the photo-generated holes and its initial oxidation product carbonate radical, oxidizing HCOO(-) to form CO2. The HCOO(-) degradation rate increases with increase in silver concentration due to increase in rate of photo-generation of holes while the increase in chloride concentration decreases the degradation rate of HCOO(-) as a result of the scavenging of holes by Cl(-), thereby resulting in decreased holes and carbonate radical concentration. The results obtained indicate that a variety of other solution conditions including dioxygen concentration, bicarbonate concentration and pH influence the availability of holes and hence the HCOO(-) degradation rate in a manner consistent with our understanding of key processes. Based on our experimental results, we have developed a kinetic model capable of predicting AgCl(s)-mediated HCOO(-) photo-degradation over a wide range of conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

CERN Document Server

Kassel, Florian; Dabrowski, Anne; de Boer, Wim

2016-01-01

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field,...

Spectroscopy investigation on chemo-catalytic, free radical scavenging and bactericidal properties of biogenic silver nanoparticles synthesized using Salicornia brachiata aqueous extract

Science.gov (United States)

Seralathan, Janani; Stevenson, Priscilla; Subramaniam, Shankar; Raghavan, Rachana; Pemaiah, Brindha; Sivasubramanian, Aravind; Veerappan, Anbazhagan

2014-01-01

Nanosized silver have been widely used in many applications, such as catalysis, photonics, sensors, medicine etc. Thus, there is an increasing need to develop high-yield, low cost, non-toxic and eco-friendly procedures for the synthesis of nanoparticles. Herein, we report an efficient, green synthesis of silver nanoparticles utilizing the aqueous extract of Salicornia brachiata, a tropical plant of the Chenopodiaceae family. Silver nanoparticles have been characterized by ultraviolet-visible spectroscopy, scanning electron microscopy and transmission electron microscopy. The morphology of the particles formed consists of highly diversified shapes like spherical, rod-like, prism, triangular, pentagonal and hexagonal pattern. However, addition of sodium hydroxide to the extract produces mostly spherical particles. The stable nanoparticles obtained using this green method show remarkable catalytic activity in the reduction of 4-nitro phenol to 4-amino phenol. The reduction catalyzed by silver nanoparticles followed the first-order kinetics, with a rate constant of, 0.6 × 10-2 s-1. The bactericidal activity of the synthesized silver nanoparticles against the pathogenic bacteria, Staphylococcus aureus, Staphylococcus aureus E, Bacillus subtilis and Escherichia coli, was also explored using REMA. The obtained results showed that the minimum inhibitory concentration required to induce bactericidal effect is lower than the control antibiotic, ciprofloxacin. In addition to these, the biogenic synthesized nanoparticles also exhibited excellent free radical scavenging activity.

Superoxide scavenging activity of pirfenidone-iron complex

International Nuclear Information System (INIS)

Mitani, Yoshihiro; Sato, Keizo; Muramoto, Yosuke; Karakawa, Tomohiro; Kitamado, Masataka; Iwanaga, Tatsuya; Nabeshima, Tetsuji; Maruyama, Kumiko; Nakagawa, Kazuko; Ishida, Kazuhiko; Sasamoto, Kazumi

2008-01-01

Pirfenidone (PFD) is focused on a new anti-fibrotic drug, which can minimize lung fibrosis etc. We evaluated the superoxide (O 2 ·- ) scavenging activities of PFD and the PFD-iron complex by electron spin resonance (ESR) spectroscopy, luminol-dependent chemiluminescence assay, and cytochrome c reduction assay. Firstly, we confirmed that the PFD-iron complex was formed by mixing iron chloride with threefold molar PFD, and the complex was stable in distillated water and ethanol. Secondary, the PFD-iron complex reduced the amount of O 2 ·- produced by xanthine oxidase/hypoxanthine without inhibiting the enzyme activity. Thirdly, it also reduced the amount of O 2 ·- released from phorbor ester-stimulated human neutrophils. PFD alone showed few such effects. These results suggest the possibility that the O 2 ·- scavenging effect of the PFD-iron complex contributes to the anti-fibrotic action of PFD used for treating idiopathic pulmonary fibrosis

Applying Knowledge of Species-Typical Scavenging Behavior to the Search and Recovery of Mammalian Skeletal Remains.

Science.gov (United States)

Young, Alexandria; Stillman, Richard; Smith, Martin J; Korstjens, Amanda H

2016-03-01

Forensic investigations involving animal scavenging of human remains require a physical search of the scene and surrounding areas. However, there is currently no standard procedure in the U.K. for physical searches of scavenged human remains. The Winthrop and grid search methods used by police specialist searchers for scavenged remains were examined through the use of mock red fox (Vulpes vulpes) scatter scenes. Forty-two police specialist searchers from two different regions within the U.K. were divided between those briefed and not briefed with fox-typical scavenging information. Briefing searchers with scavenging information significantly affected the recovery of scattered bones (χ(2) = 11.45, df = 1, p = 0.001). Searchers briefed with scavenging information were 2.05 times more likely to recover bones. Adaptions to search methods used by searchers were evident on a regional level, such that searchers more accustom to a peri-urban to rural region recovered a higher percentage of scattered bones (58.33%, n = 84). © 2015 American Academy of Forensic Sciences.

Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

Energy Technology Data Exchange (ETDEWEB)

Smith, James N. [NCAR, Boulder, CO (United States); McMurry, Peter H. [NCAR, Boulder, CO (United States)

2015-11-12

This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

Role of antioxidant scavenging enzymes and extracellular ...

African Journals Online (AJOL)

In the present work, we studied the role of antioxidant scavenging enzymes of plant pathogenic bacteria: catalase, ascorbate peroxidase and a virulence factor; extracelluar polysaccharide production in determining the virulence of Xanthomonas oryzae pv. oryzae (Xoo) isolates and its differential reaction to rice cultivars.

Effect of a generalized particle momentum distribution on plasma nuclear fusion rates

International Nuclear Information System (INIS)

Kim, Yeong E.; Zubarev, Alexander L.

2006-01-01

We investigate the effect of a generalized particle momentum distribution derived by Galitskii and Yakimets (GY) on nuclear reaction rates in plasma. We derive an approximate semi-analytical formula for nuclear fusion reaction rate between nuclei in a plasma (quantum plasma nuclear fusion; or QPNF). The QPNF formula is applied to calculate deuteron-deuteron fusion rate in a plasma, and the results are compared with the results calculated with the conventional Maxwell-Boltzmann velocity distribution. As an application, we investigate the deuteron-deuteron fusion rate for mobile deuterons in a deuterated metal/alloy. The calculated deuteron-deuteron fusion rates at low energies are enormously enhanced due to the modified tail of the GY's generalized momentum distribution. Our preliminary estimates indicate also that the deuteron-lithium (D+Li) fusion rate and the proton-lithium (p+Li) fusion rate in a metal/alloy at ambient temperatures are also substantially enhanced. (author)

Multi-dimensional scavenging analysis of a free-piston linear alternator based on numerical simulation

Energy Technology Data Exchange (ETDEWEB)

Mao, Jinlong; Zuo, Zhengxing; Li, Wen; Feng, Huihua [School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081 (China)

2011-04-15

A free-piston linear alternator (FPLA) is being developed by the Beijing Institute of Technology to improve the thermal efficiency relative to conventional crank-driven engines. A two-stroke scavenging process recharges the engine and is crucial to realizing the continuous operation of a free-piston engine. In order to study the FPLA scavenging process, the scavenging system was configured using computational fluid dynamics. As the piston dynamics of the FPLA are different to conventional crank-driven two-stroke engines, a time-based numerical simulation program was built using Matlab to define the piston's motion profiles. A wide range of design and operating options were investigated including effective stroke length, valve overlapping distance, operating frequency and charging pressure to find out their effects on the scavenging performance. The results indicate that a combination of high effective stroke length to bore ratio and long valve overlapping distance with a low supercharging pressure has the potential to achieve high scavenging and trapping efficiencies with low short-circuiting losses. (author)

Using measurements of the aerosol charging state in determination of the particle growth rate and the proportion of ion-induced nucleation

Directory of Open Access Journals (Sweden)

J. Leppä

2013-01-01

Full Text Available The fraction of charged nucleation mode particles as a function of particle diameter depends on the particle growth rate and the proportion of particles formed via ion-induced nucleation. In this study we have tested the applicability of recent data analysis methods to determine the growth rate and the proportion of ion-induced nucleation from the measured charged fractions. For this purpose we have conducted a series of aerosol dynamic simulations covering a wide range of atmospheric conditions. The growth rate and initial fraction of charged particles were estimated from simulated data using these methods and compared with the values obtained directly from the simulations. We found that the data analysis methods used in this study should not be used when the nuclei growth rate is less than ~3 nm h⁻¹, or when charged particles grow much more rapidly than neutral ones. Furthermore, we found that the difference in removal rates of neutral and charged particles should be taken into account when estimating the proportion of ion-induced nucleation. Neglecting the higher removal rate of charged particles compared with that of neutral ones could result in an underestimation of the proportion of ion-induced nucleation by up to a factor of 2. This underestimation is further increased if charged particles grow more rapidly than neutral ones. We also provided a simple way of assessing whether these methods are suitable for analyzing data measured under specific conditions. The assessment procedure was illustrated using a few examples of actual measurement sites with a more detailed examination of the typical conditions observed at the SMEAR II station in Hyytiälä, Finland.

The evolution of the class A scavenger receptors

Directory of Open Access Journals (Sweden)

Whelan Fiona J

2012-11-01

Full Text Available Abstract Background The class A scavenger receptors are a subclass of a diverse family of proteins defined based on their ability to bind modified lipoproteins. The 5 members of this family are strikingly variable in their protein structure and function, raising the question as to whether it is appropriate to group them as a family based on their ligand binding abilities. Results To investigate these relationships, we defined the domain architecture of each of the 5 members followed by collecting and annotating class A scavenger receptor mRNA and amino acid sequences from publicly available databases. Phylogenetic analyses, sequence alignments, and permutation tests revealed a common evolutionary ancestry of these proteins, indicating that they form a protein family. We postulate that 4 distinct gene duplication events and subsequent domain fusions, internal repeats, and deletions are responsible for the diverse protein structures and functions of this family. Despite variation in domain structure, there are highly conserved regions across all 5 members, indicating the possibility that these regions may represent key conserved functional motifs. Conclusions We have shown with significant evidence that the 5 members of the class A scavenger receptors form a protein family. We have indicated that these receptors have a common origin which may provide insight into future functional work with these proteins.

Meridional circulation across the Antarctic Circumpolar Current serves as a double

NARCIS (Netherlands)

Rutgers van der Loeff, M.; Venchiarutti, C.; Stimac, I.; van Ooijen, J.; Huhn, O.; Rohardt, G.; Strass, V.H.

2016-01-01

Upwelling of Circumpolar Deep Water in the Weddell Gyre and low scavenging rates south of the Antarctic Circumpolar Current (ACC) cause an accumulation of particle reactive nuclides in the Weddell Gyre. A ventilation/reversible scavenging model that successfully described the accumulation of 230Th

Using Scavenger Hunts to Familiarize Students with Scientific Journal Articles.

Science.gov (United States)

Lijek, Rebeccah S; Fankhauser, Sarah C

2016-03-01

Primary scientific literature can be difficult to navigate for anyone unfamiliar with its foreign, formal structure. We sought to create a fun, easy learning tool to help familiarize students of all ages with the structure of a scientific article. Our main learning objective was for the student to realize that science writing is formulaic-that specific information is found in predictable locations within an article-and that, with an understanding of the formula, anyone can comfortably navigate any journal article and accurately predict what to expect to find in each section. To this end, we designed a Journal Article Scavenger Hunt that requires the user to find and identify a series of commonplace features of a primary research article. The scavenger hunt activity is quick and easy to implement, and is adaptable to various ages and settings, including the classroom, lab, and at outreach events. The questions in the scavenger hunt can be scaled in difficulty and specificity to suit the instructor's needs. Over many years of using this activity, we have received positive feedback from students of all ages, from elementary school students to lay adult-learners as well as science teachers themselves. By making the unknown seem predictable and approachable, the scavenger hunt helps a variety of audiences feel more comfortable with science and more confident in their ability to engage directly with the scientific literature. Journal of Microbiology & Biology Education.

Slew-rate dependence of tracer magnetization response in magnetic particle imaging

Science.gov (United States)

Shah, Saqlain A.; Ferguson, R. M.; Krishnan, K. M.

2014-10-01

Magnetic Particle Imaging (MPI) is a new biomedical imaging technique that produces real-time, high-resolution tomographic images of superparamagnetic iron oxide nanoparticle tracers. Currently, 25 kHz and 20 mT/μ0 excitation fields are common in MPI, but lower field amplitudes may be necessary for patient safety in future designs. Here, we address fundamental questions about MPI tracer magnetization dynamics and predict tracer performance in future scanners that employ new combinations of excitation field amplitude (Ho) and frequency (ω). Using an optimized, monodisperse MPI tracer, we studied how several combinations of drive field frequencies and amplitudes affect the tracer's response, using Magnetic Particle Spectrometry and AC hysteresis, for drive field conditions at 15.5, 26, and 40.2 kHz, with field amplitudes ranging from 7 to 52 mT/μ0. For both fluid and immobilized nanoparticle samples, we determined that magnetic response was dominated by Néel reversal. Furthermore, we observed that the peak slew-rate (ωHo) determined the tracer magnetic response. Smaller amplitudes provided correspondingly smaller field of view, sometimes resulting in excitation of minor hysteresis loops. Changing the drive field conditions but keeping the peak slew-rate constant kept the tracer response almost the same. Higher peak slew-rates led to reduced maximum signal intensity and greater coercivity in the tracer response. Our experimental results were in reasonable agreement with Stoner-Wohlfarth model based theories.

Phytochemical screening, free radical scavenging and antibacterial ...

African Journals Online (AJOL)

Cassia sieberiana is a tropical plant, widely distributed throughout Sudan and Guinea savannah. It is used in traditional medicine for the treatment of malarial, cancer and stomach ache. The study was conducted to screen for phytochemicals, free radical scavenging and antibacterial potentials of the root bark.

Recovery of Li from alloys of Al- Li and Li- Al using engineered scavenger compounds

Science.gov (United States)

Riley, W. D.; Jong, B. W.; Collins, W. K.; Gerdemann, S. J.

1994-01-01

A method of producing lithium of high purity from lithium aluminum alloys using an engineered scavenger compound, comprising: I) preparing an engineered scavenger compound by: a) mixing and heating compounds of TiO2 and Li2CO3 at a temperature sufficient to dry the compounds and convert Li.sub.2 CO.sub.3 to Li.sub.2 O; and b) mixing and heating the compounds at a temperature sufficient to produce a scavenger Li.sub.2 O.3TiO.sub.2 compound; II) loading the scavenger into one of two electrode baskets in a three electrode cell reactor and placing an Al-Li alloy in a second electrode basket of the three electrode cell reactor; III) heating the cell to a temperature sufficient to enable a mixture of KCl-LiCl contained in a crucible in the cell to reach its melting point and become a molten bath; IV) immersing the baskets in the bath until an electrical connection is made between the baskets to charge the scavenger compound with Li until there is an initial current and voltage followed by a fall off ending current and voltage; and V) making a connection between the basket electrode containing engineered scavenger compound and a steel rod electrode disposed between the basket electrodes and applying a current to cause Li to leave the scavenger compound and become electrodeposited on the steel rod electrode.

Activation of Rho GTPases by Cytotoxic Necrotizing Factor 1 Induces Macropinocytosis and Scavenging Activity in Epithelial Cells

Science.gov (United States)

Fiorentini, Carla; Falzano, Loredana; Fabbri, Alessia; Stringaro, Annarita; Logozzi, Mariaantonia; Travaglione, Sara; Contamin, Stéphanette; Arancia, Giuseppe; Malorni, Walter; Fais, Stefano

2001-01-01

Macropinocytosis, a ruffling-driven process that allows the capture of large material, is an essential aspect of normal cell function. It can be either constitutive, as in professional phagocytes where it ends with the digestion of captured material, or induced, as in epithelial cells stimulated by growth factors. In this case, the internalized material recycles back to the cell surface. We herein show that activation of Rho GTPases by a bacterial protein toxin, the Escherichia coli cytotoxic necrotizing factor 1 (CNF1), allowed epithelial cells to engulf and digest apoptotic cells in a manner similar to that of professional phagocytes. In particular, we have demonstrated that 1) the activation of all Rho, Rac, and Cdc42 by CNF1 was essential for the capture and internalization of apoptotic cells; and 2) such activation allowed the discharge of macropinosomal content into Rab7 and lysosomal associated membrane protein-1 acidic lysosomal vesicles where the ingested particles underwent degradation. Taken together, these findings indicate that CNF1-induced “switching on” of Rho GTPases may induce in epithelial cells a scavenging activity, comparable to that exerted by professional phagocytes. The activation of such activity in epithelial cells may be relevant, in mucosal tissues, in supporting or integrating the scavenging activity of resident macrophages. PMID:11452003

Aperture and counting rate of rectangular telescopes for single and multiple parallel particles. [Spark chamber telescopes

Energy Technology Data Exchange (ETDEWEB)

D' Ettorre Piazzoli, B; Mannocchi, G [Consiglio Nazionale delle Ricerche, Turin (Italy). Lab. di Cosmo-Geofisica; Melone, S [Istituto di Fisica dell' Universita, Ancona, Italy; Picchi, P; Visentin, R [Comitato Nazionale per l' Energia Nucleare, Frascati (Italy). Laboratori Nazionali di Frascati

1976-06-01

Expressions for the counting rate of rectangular telescopes in the case of single as well as multiple particles are given. The aperture for single particles is obtained in the form of a double integral and analytical solutions are given for some cases. The intensity for different multiplicities of parallel particles is related to the geometry of the detectors and to the features of the radiation. This allows an absolute comparison between the data recorded by different devices.

Influence of particle size on the low and high strain rate behavior of dense colloidal dispersions of nanosilica

Energy Technology Data Exchange (ETDEWEB)

Asija, Neelanchali; Chouhan, Hemant; Gebremeskel, Shishay Amare; Bhatnagar, Naresh, E-mail: nareshb@mech.iitd.ac.in [Indian Institute of Technology Delhi, Mechanical Engineering Department (India)

2017-01-15

Shear thickening is a non-Newtonian flow behavior characterized by the increase in apparent viscosity with the increase in applied shear rate, particularly when the shear rate exceeds a critical value termed as the critical shear rate (CSR). Due to this remarkable property of shear-thickening fluids (STFs), they are extensively used in hip protection pads, protective gear for athletes, and more recently in body armor. The use of STFs in body armor has led to the development of the concept of liquid body armor. In this study, the effect of particle size is explored on the low and high strain rate behavior of nanosilica dispersions, so as to predict the efficacy of STF-aided personal protection systems (PPS), specifically for ballistic applications. The low strain rate study was conducted on cone and plate rheometer, whereas the high strain rate characterization of STF was conducted on in-house fabricated split Hopkinson pressure bar (SHPB) system. Spherical nanosilica particles of three different sizes (100, 300, and 500 nm) as well as fumed silica particles of four different specific surface areas (Aerosil A-90, A-130, A-150, and A-200), respectively, were used in this study. The test samples were prepared by dispersing nanosilica particles in polypropylene glycol (PPG) using ultrasonic homogenization method. The low strain rate studies aided in determining the CSR of the synthesized STF dispersions, whereas the high strain rate studies explored the impact-resisting ability of STFs in terms of the impact toughness and the peak stress attained during the impact loading of STF in SHPB testing.

Charged-particle thermonuclear reaction rates: II. Tables and graphs of reaction rates and probability density functions

International Nuclear Information System (INIS)

Iliadis, C.; Longland, R.; Champagne, A.E.; Coc, A.; Fitzgerald, R.

2010-01-01

Numerical values of charged-particle thermonuclear reaction rates for nuclei in the A=14 to 40 region are tabulated. The results are obtained using a method, based on Monte Carlo techniques, that has been described in the preceding paper of this issue (Paper I). We present a low rate, median rate and high rate which correspond to the 0.16, 0.50 and 0.84 quantiles, respectively, of the cumulative reaction rate distribution. The meaning of these quantities is in general different from the commonly reported, but statistically meaningless expressions, 'lower limit', 'nominal value' and 'upper limit' of the total reaction rate. In addition, we approximate the Monte Carlo probability density function of the total reaction rate by a lognormal distribution and tabulate the lognormal parameters μ and σ at each temperature. We also provide a quantitative measure (Anderson-Darling test statistic) for the reliability of the lognormal approximation. The user can implement the approximate lognormal reaction rate probability density functions directly in a stellar model code for studies of stellar energy generation and nucleosynthesis. For each reaction, the Monte Carlo reaction rate probability density functions, together with their lognormal approximations, are displayed graphically for selected temperatures in order to provide a visual impression. Our new reaction rates are appropriate for bare nuclei in the laboratory. The nuclear physics input used to derive our reaction rates is presented in the subsequent paper of this issue (Paper III). In the fourth paper of this issue (Paper IV) we compare our new reaction rates to previous results.

Enhancement and degradation of the R2* relaxation rate resulting from the encapsulation of magnetic particles with hydrophilic coatings.

Science.gov (United States)

de Haan, Hendrick W; Paquet, Chantal

2011-12-01

The effects of including a hydrophilic coating around the particles are studied across a wide range of particle sizes by performing Monte Carlo simulations of protons diffusing through a system of magnetic particles. A physically realistic methodology of implementing the coating by cross boundary jump scaling and transition probabilities at the coating surface is developed. Using this formulation, the coating has three distinct impacts on the relaxation rate: an enhancement at small particle sizes, a degradation at intermediate particle sizes, and no effect at large particles sizes. These varied effects are reconciled with the underlying dephasing mechanisms by using the concept of a full dephasing zone to present a physical picture of the dephasing process with and without the coating for all sizes. The enhancement at small particle sizes is studied systemically to demonstrate the existence of an optimal ratio of diffusion coefficients inside/outside the coating to achieve maximal increase in the relaxation rate. Copyright © 2011 Wiley Periodicals, Inc.

Graphene oxide as efficient high-concentration formaldehyde scavenger and reutilization in supercapacitor.

Science.gov (United States)

Liang, Hongyu; Bu, Yongfeng; Zhang, Yutian; Zhang, Junyan

2015-04-15

Graphene oxide (GO) was investigated as a low-cost and high-efficient scavenger for high-concentration formaldehyde in alkali media. It showed very high removal capacity, 411 mg of formaldehyde per milligram of GO, and strong resistant to temperature changes. Additionally, the used GO can be easily renewed by a simple electrochemical method. By analyzing the componential and electrochemical characterizations of GO before and after use, the results showed that the degradation mechanism of formaldehyde is a collaborative process of chemical oxidation and physical adsorption, and the former dominates the degradation process. With the aid of oxygen-containing groups in GO, most formaldehyde can be easily oxidized by GO in alkaline media (this is equivalent to GO was reduced by formaldehyde). On the other hand, the used GO (reduced GO, noted as rGO) exhibits more ideal electronic double-layer capacitor (EDLC) feature than GO, along with higher rate capacitance (up to 136 F g(-1) at 50 A g(-1)). In short, GO is not only an efficient formaldehyde scavenger, but the used GO (rGO) can serve as promising electrical energy storage material. This study provides new insights for us to reutilize the discarded adsorbents generated from the environmental protection. Copyright © 2014 Elsevier Inc. All rights reserved.

Test for antioxidant ability by scavenging long-lived mutagenic radicals in mammalian cells and by blood test with intentional radicals: an application of gallic acid

International Nuclear Information System (INIS)

Kumagai, Jun; Kawaura, Tomoko; Miyazaki, Tetsuo; Prost, Michel; Prost, Emmanuelle; Watanabe, Masami; Quetin-Leclercq, J.Joeelle

2003-01-01

Antioxidant ability of gallic acid (GA) are determined both by electron spin resonance measurement of long-lived radicals produced in γ-ray irradiated Syrian golden hamster embryo cells with GA and by hemolysis measurement with GA when blood cells are submitted to radicals. Scavenging properties of GA are determined by the reaction rate constant with long-lived mutagenic radicals in the cells while the blood test allows to analyze the global effects of this compound: radical scavenger+metal ion chelator+regeneration of intra- and extra-cellular antioxidant

21 CFR 868.5430 - Gas-scavenging apparatus.

Science.gov (United States)

2010-04-01

...) Identification. A gas-scavenging apparatus is a device intended to collect excess anesthetic, analgesic, or trace gases or vapors from a patient's breathing system, ventilator, or extracorporeal pump-oxygenator, and to conduct these gases out of the area by means of an exhaust system. (b) Classification. Class II...

Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic ...

African Journals Online (AJOL)

Antioxidant Capacity, Radical Scavenging Kinetics and Phenolic Profile of Methanol Extracts of Wild Plants of Southern Sonora, Mexico. EF Moran-Palacio, LA Zamora-Álvarez, NA Stephens-Camacho, GA Yáñez- Farías, A Virgen-Ortiz, O Martínez-Cruz, JA Rosas-Rodríguez ...

In vitro free radical scavenging activity of ethanolic extract of the whole plant of Evolvulus alsinoides (L.) L.

Science.gov (United States)

Gomathi, Duraisamy; Ravikumar, Ganesan; Kalaiselvi, Manokaran; Vidya, Balasubramaniam; Uma, Chandrasekar

2015-06-01

To identify the free radical scavenging activity of ethanolic extract of Evolvulus alsinoides. The free radical scavenging activity was evaluated by in vitro methods like reducing power assay, total antioxidant activity, 2,2-diphenyl-1-picrylhydrazyl (DPPH) reduction, superoxide radical scavenging activity, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS(+)) scavenging activity, hydroxyl radical scavenging assay, and nitric oxide radical scavenging assay, which were studied by using ascorbic acid as standard. The extract showed significant activities in all antioxidant assays compared with the reference antioxidant ascorbic acid. The total antioxidant activity as well as the reducing power was also found to increase in a dose-dependent manner. Evolvulus alsinoides may act as a chemopreventive agent, providing antioxidant properties and offering effective protection from free radicals.

The behavior of particle-reactive tracers in a high turbidity environment: 234Th and 210Pb on the Amazon continental shelf

International Nuclear Information System (INIS)

Smoak, J.M.; DeMaster, D.J.; Pope, R.H.; Kuehl, S.A.; McKee, B.A.

1996-01-01

Excess 234 Th and 210 Pb seabed inventories were measured in cores collected from the Amazon continental shelf to examine particle scavenging and seabed dynamics. Typical excess 210 Pb inventories range from 100 to 300 dpm cm -2 , and the total excess 210 Pb inventory for the Amazon shelf was determined to be 2.7 x 10 17 dpm. The 210 Pb measurements indicate that particle-reactive species are scavenged not only form the Amazon River but also from the lateral advection of offshore water. In order to sustain the 210 Pb inventories, the volume of water supplied by the lateral advection from offshore must be approximately five to ten times the water discharge of the Amazon River. This lateral advection supplies about 67% of the total excess 210 Pb to the Amazon continental shelf with relatively small contributions from riverine input (31%), atmospheric fallout (2.3%), and in-situ production (0.1%). The 234 Th inventories were measured on four cruises, which occurred during periods of differing river discharge, wind stress, and flow rates of the North Brazil Current. The 234 Th excess seabed inventories show large spatial and seasonal variability, with a range from 0 to 22 dpm cm -2 . This approach indicates that for most of the shelf, the inventories of the shorter-term tracer ( 234 Th) are less than predicted by the inventories of the longer-term tracer ( 210 Pb). There are two explanations for this trend. The first is that a larger portion of the 234 Th inventory occurs in the fluid muds or the water column relative to 210 Pb. The second is that the supply of offshore water, scavenging efficiency, and/or deposition have been lower over the two year study period relative to the last one hundred years. 38 refs., 7 figs

New particle formation in air mass transported between two measurement sites in Northern Finland

Directory of Open Access Journals (Sweden)

M. Komppula

2006-01-01

organic vapours to accumulate in the air and to interact with the particles is relatively short. This can lead to low nucleation mode growth rates and even to suppression of detectable particle formation event due to efficient scavenging of newly formed clusters, as was observed in the case studies.

The acceleration of dissolved cobalt's ecological stoichiometry due to biological uptake, remineralization, and scavenging in the Atlantic Ocean

Science.gov (United States)

Saito, Mak A.; Noble, Abigail E.; Hawco, Nicholas; Twining, Benjamin S.; Ohnemus, Daniel C.; John, Seth G.; Lam, Phoebe; Conway, Tim M.; Johnson, Rod; Moran, Dawn; McIlvin, Matthew

2017-10-01

alkaline phosphatase enzyme to be prevalent in the upper water column, as well as a sulfolipid biosynthesis protein indicative of P sparing. The negative dCo : P relationships in the ocean interior became increasingly vertical with depth, and were consistent with the sum of scavenging and remineralization processes (as shown by their dCo : P vector sums). Attenuation of the remineralization with depth resulted in the increasingly vertical dCo : P relationships. Analysis of particulate Co with particulate Mn and particulate phosphate also showed positive linear relationships below the euphotic zone, consistent with the presence and increased relative influence of Mn oxide particles involved in scavenging. Visualization of dCo : P slopes across an ocean section revealed hotspots of scavenging and remineralization, such as at the hydrothermal vents and below the oxygen minimum zone (OMZ) region, respectively, while that of an estimate of Co* illustrated stoichiometrically depleted values in the mesopelagic and deep ocean due to scavenging. This study provides insights into the coupling between the dissolved and particulate phase that ultimately creates Redfield stoichiometric ratios, demonstrating that the coupling is not an instantaneous process and is influenced by the element inventory and rate of exchange between phases. Cobalt's small water column inventory and the influence of external factors on its biotic stoichiometry can erode its limited inertia and result in an acceleration of the dissolved stoichiometry towards that of the particulate phase in the upper euphotic zone. As human use of cobalt grows exponentially with widespread adoption of lithium ion batteries, there is a potential to affect the limited biogeochemical inertia of cobalt and its resultant ecology in the oceanic euphotic zone.

Transport and scavenging of Pu in surface waters of the Southern Hemisphere Oceans

DEFF Research Database (Denmark)

Gastaud, J.; Povinec, P.P.; Aoyama, M.

2011-01-01

The distribution of 239Pu in Atlantic and Indian Ocean waters about four decades after their main injection from atmospheric nuclear weapons tests is discussed. Recent data obtained in the framework of the SHOTS (Southern Hemisphere Ocean Tracer Studies) projects are evaluated and compared...... with previous investigations. Seawater samples were collected during the round the globe BEAGLE2003 (Blue Ocean Global Expedition) along the 30°S transect in the Atlantic and the 20°S transect in the Indian Ocean. The results indicate transport of surface waters labelled with 239Pu from the western North...... Pacific via the Indonesian Seas to the South Indian Ocean and then to the South Atlantic Ocean. Along the whole BEAGLE2003 sampling route, the Atlantic Ocean has the lowest 239Pu content due to its particle scavenging on the long way from the western North Pacific. On the other hand, concentrations...

Intracellular ROS protection efficiency and free radical-scavenging activity of curcumin.

Directory of Open Access Journals (Sweden)

Abolfazl Barzegar

Full Text Available Curcumin has many pharmaceutical applications, many of which arise from its potent antioxidant properties. The present research examined the antioxidant activities of curcumin in polar solvents by a comparative study using ESR, reduction of ferric iron in aqueous medium and intracellular ROS/toxicity assays. ESR data indicated that the steric hindrance among adjacent big size groups within a galvinoxyl molecule limited the curcumin to scavenge galvinoxyl radicals effectively, while curcumin showed a powerful capacity for scavenging intracellular smaller oxidative molecules such as H₂O₂, HO•, ROO•. Cell viability and ROS assays demonstrated that curcumin was able to penetrate into the polar medium inside the cells and to protect them against the highly toxic and lethal effects of cumene hydroperoxide. Curcumin also showed good electron-transfer capability, with greater activity than trolox in aqueous solution. Curcumin can readily transfer electron or easily donate H-atom from two phenolic sites to scavenge free radicals. The excellent electron transfer capability of curcumin is because of its unique structure and different functional groups, including a β-diketone and several π electrons that have the capacity to conjugate between two phenyl rings. Therfore, since curcumin is inherently a lipophilic compound, because of its superb intracellular ROS scavenging activity, it can be used as an effective antioxidant for ROS protection within the polar cytoplasm.

Performance of Chickens under Semi-scavenging Conditions: A ...

African Journals Online (AJOL)

Performance of Chickens under Semi-scavenging Conditions: A Case Study of ... per household was lost per year due to diseases, predators, accidents, and theft. ... as well as chicken house construction so as to avoid the risks of predators.

Antimicrobial and free radical scavenging activities of five ...

African Journals Online (AJOL)

Extracts from five indigenous Palestinian medicinal plants including Rosmarinus officinalis, Pisidium guajava, Punica granatum peel, grape seeds and Teucrium polium were investigated for antimicrobial and free radical scavenging activities against eight microorganisms, using well diffusion method. The microorganisms ...

Effect of concentration and molecular weight of chitosan and its derivative on the free radical scavenging ability.

Science.gov (United States)

Li, Huili; Xu, Qing; Chen, Yun; Wan, Ajun

2014-03-01

Chitosan is a biodegradable and biocompatible natural scaffold material, which has numerous applications in biomedical sciences. In this study, the in vitro antioxidant activity of chitosan scaffold material was investigated by the chemiluminescence signal generated from the hydroxyl radical (•OH) scavenging assay. The scavenging mechanism was also discussed. The results indicated that the free radical scavenging ability of chitosan scaffold material significantly depends on the chitosan concentration and shows interesting kinetic change. Within the experimental concentration range, the optimal concentration of chitosan was 0.2 mg/mL. The molecular weight of chitosan also attributed to the free radical scavenging ability. Comparison between chitosan and its derivative found that carboxymethyl chitosan possessed higher scavenging ability. Copyright © 2013 Society of Plastics Engineers.

Exact Solutions of Fragmentation Equations with General Fragmentation Rates and Separable Particles Distribution Kernels

Directory of Open Access Journals (Sweden)

S. C. Oukouomi Noutchie

2014-01-01

Full Text Available We make use of Laplace transform techniques and the method of characteristics to solve fragmentation equations explicitly. Our result is a breakthrough in the analysis of pure fragmentation equations as this is the first instance where an exact solution is provided for the fragmentation evolution equation with general fragmentation rates. This paper is the key for resolving most of the open problems in fragmentation theory including “shattering” and the sudden appearance of infinitely many particles in some systems with initial finite particles number.

Influence of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in cyclone heat exchanger

International Nuclear Information System (INIS)

Mothilal, T.; Pitchandi, K.

2015-01-01

Present work elaborates the effect of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in a cyclone heat exchanger. The RNG k-ε turbulence model was adopted for modeling high turbulence flow and Discrete phase model (DPM) to track solid particles in a cyclone heat exchanger by ANSYS FLUENT software. The effect of inlet air velocity (5 to 25 m/s) and inlet solid particle feed rate of (0.2 to 2.5 g/s) at different particle diameter (300 to 500 μm) on holdup mass and heat transfer rate in cyclone heat exchanger was studied at air inlet temperature of 473 K. Results show that holdup mass and heat transfer rate increase with increase in inlet air velocity and inlet solid particle feed rate. Influence of solid particle feed rate on holdup mass has more significance. Experimental setup was built for high efficiency cyclone. Good agreement was found between experimental and simulation pressure drop. Empirical correlation was derived for dimensionless holdup mass and Nusselt number based on CFD data by regression technique. Correlation predicts dimensional holdup mass with +5% to -8% errors of experimental data and Nusselt number with +9% to -3%

Influence of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in cyclone heat exchanger

Energy Technology Data Exchange (ETDEWEB)

Mothilal, T. [T. J. S. Engineering College, Gummidipoond (India); Pitchandi, K. [Sri Venkateswara College of Engineering, Sriperumbudur (India)

2015-10-15

Present work elaborates the effect of inlet velocity of air and solid particle feed rate on holdup mass and heat transfer characteristics in a cyclone heat exchanger. The RNG k-ε turbulence model was adopted for modeling high turbulence flow and Discrete phase model (DPM) to track solid particles in a cyclone heat exchanger by ANSYS FLUENT software. The effect of inlet air velocity (5 to 25 m/s) and inlet solid particle feed rate of (0.2 to 2.5 g/s) at different particle diameter (300 to 500 μm) on holdup mass and heat transfer rate in cyclone heat exchanger was studied at air inlet temperature of 473 K. Results show that holdup mass and heat transfer rate increase with increase in inlet air velocity and inlet solid particle feed rate. Influence of solid particle feed rate on holdup mass has more significance. Experimental setup was built for high efficiency cyclone. Good agreement was found between experimental and simulation pressure drop. Empirical correlation was derived for dimensionless holdup mass and Nusselt number based on CFD data by regression technique. Correlation predicts dimensional holdup mass with +5% to -8% errors of experimental data and Nusselt number with +9% to -3%.

Evaluation of free radical scavenging capacity and antioxidative damage effect of resveratrol-nanostructured lipid carriers

Science.gov (United States)

Jin, Ju; Shi, Fan; Li, Qiu-wen; Li, Pei-shan; Chen, Tong-sheng; Wang, Yi-fei; Wang, Zhi-ping

2016-03-01

Cellular damage induced by free-radicals like reactive oxygen species has been implicated in several diseases. 2, 2-azobis(2-amidino-propane) dihydrochloride(AAPH) generates two potent ROS capable of inducing lipid peroxidation: alkoxy radical(RO-) and peroxy radical(ROO-). These radicals are similar to those that are physiologically active and thus might initiate a cascade of intracellular toxic events leading to oxidation, lipid peroxidation, DNA damage and subsequent cell death. Hence naturally anti-oxidant play a vital role in combating these conditions. In this study, resveratrol loaded nanostructured lipid carriers (Res-NLC) was prepared by hot melting and then high pressure homogenization technique. The effects of Res-NLC on free radical scavenging capacity and antioxidative damage is investigated. The particle size and zeta potential of Res-NLC were 139.3 ± 1.7 nm and -11.21 ± 0.41 mV, respectively. By free radical scavenging assays, the IC50 value of Res-NLC were 19.25, 5.29 μg/mL with DPPH, ABTS assay respectively, and 0.161 mg ferrous sulfate/1 mg Res-NLC with FRAP assay; and by AAPH-induced oxidative injury cell model assay, Res-NLC showed the strong protective effect against the human liver tumor HepG2 cell oxidative stress damage. These results indicated that the antioxidant properties of Res-NLC hold great potential used as an alternative to more toxic synthetic antioxidants as an additive in food, cosmetic and pharmaceutical preparations for the oxidative diseases treatment.

Levels of Crotonaldehyde and 4-hydroxy-(E-2-nonenal and Expression of Genes Encoding Carbonyl-Scavenging Enzyme at Critical Node During Rice Seed Aging

Directory of Open Access Journals (Sweden)

Fu Shenzao

2018-05-01

Full Text Available Abstract:: The critical node (CN is an important stage during seed aging, which is related to effective genebank conservation. Previous studies have demonstrated that proteins undergo carbonylated modification at the CN in rice, indicating oxidative damage. However, the levels of reactive carbonyl species (RCS and the associated scavenging system at the CN are largely unknown. In this study, we optimized methods for the extraction and analysis of RCS from dry rice embryos. In order to acquire seeds at the CN, rice seeds were subjected to natural conditions for 7, 9, 11 and 13 months, and the seed germination rates were reduced to 90%, 82%, 71% and 57%, respectively. We chose the stage with seed germination rate of 82% as the CN according to the rice seed vigor loss curve. The levels of crotonaldehyde and 4-hydroxy-(E-2-nonenal (HNE were significantly increased at the CN. In addition, genes encoding carbonyl-scavenging enzyme, including OsALDHs and OsAKRs, were significantly down-regulated at the CN, and reductions in the expression of OsALDH2-2, OsALDH2-5, OsALDH3-4, OsALDH7, OsAKR1 and OsAKR2 in particular could be responsible for RCS accumulation. Thus, the accumulations of crotonaldehyde and HNE and down-regulation of genes encoding carbonyl-scavenging enzyme might be related to an accelerating loss of seed viability at the CN. Key words: carbonyl-scavenging system, reactive carbonyl species, seed aging, crotonaldehyde, critical node, rice storage

Ultimate Scaling of High-κ Gate Dielectrics: Higher-κ or Interfacial Layer Scavenging?

Directory of Open Access Journals (Sweden)

Takashi Ando

2012-03-01

Full Text Available Current status and challenges of aggressive equivalent-oxide-thickness (EOT scaling of high-κ gate dielectrics via higher-κ ( > 20 materials and interfacial layer (IL scavenging techniques are reviewed. La-based higher-κ materials show aggressive EOT scaling (0.5–0.8 nm, but with effective workfunction (EWF values suitable only for n-type field-effect-transistor (FET. Further exploration for p-type FET-compatible higher-κ materials is needed. Meanwhile, IL scavenging is a promising approach to extend Hf-based high-κ dielectrics to future nodes. Remote IL scavenging techniques enable EOT scaling below 0.5 nm. Mobility-EOT trends in the literature suggest that short-channel performance improvement is attainable with aggressive EOT scaling via IL scavenging or La-silicate formation. However, extreme IL scaling (e.g., zero-IL is accompanied by loss of EWF control and with severe penalty in reliability. Therefore, highly precise IL thickness control in an ultra-thin IL regime ( < 0.5 nm will be the key technology to satisfy both performance and reliability requirements for future CMOS devices.

Study of anti-oxidation and scavenging effects on free radicals of quercetin

International Nuclear Information System (INIS)

Wang Chongdao; Qiang Yizhong; Lao Qinhua; Shao Yuan

1999-01-01

The effects of Quercetin on the contents of lipid peroxides (LPO) in the mice caused by γ-whole-body irradiation by method of the modified spectrophotometry of TBA, and the scavenging effects of Quercetin on the free radicals of DNA induced by radiation exposure by means of ESR technique were investigated. The results demonstrates that Quercetin has a good anti-oxidation effect and is very effective in scavenging of free radicals

Increasing land-use intensity reverses the relative occupancy of two quadrupedal scavengers

OpenAIRE

Twining, Joshua P.; Bernard, Henry; Ewers, Robert M.

2017-01-01

Human land use is continuously altering the natural environment, yet the greater ecological implications of this change for many groups that are key to healthy ecosystem functioning remains uncharacterised in the tropics. Terrestrial scavenging vertebrates are one such group, providing integral ecosystem services through the removal of carrion which is a crucial component of both nutrient cycling and disease dynamics. To explore how anthropogenic processes may affect forest scavengers, we inv...

Energy scavenging from environmental vibration.

Energy Technology Data Exchange (ETDEWEB)

Galchev, Tzeno (University of Michigan); Apblett, Christopher Alan; Najafi, Khalil (University of Michigan)

2009-10-01

The goal of this project is to develop an efficient energy scavenger for converting ambient low-frequency vibrations into electrical power. In order to achieve this a novel inertial micro power generator architecture has been developed that utilizes the bi-stable motion of a mechanical mass to convert a broad range of low-frequency (< 30Hz), and large-deflection (>250 {micro}m) ambient vibrations into high-frequency electrical output energy. The generator incorporates a bi-stable mechanical structure to initiate high-frequency mechanical oscillations in an electromagnetic scavenger. This frequency up-conversion technique enhances the electromechanical coupling and increases the generated power. This architecture is called the Parametric Frequency Increased Generator (PFIG). Three generations of the device have been fabricated. It was first demonstrated using a larger bench-top prototype that had a functional volume of 3.7cm3. It generated a peak power of 558{micro}W and an average power of 39.5{micro}W at an input acceleration of 1g applied at 10 Hz. The performance of this device has still not been matched by any other reported work. It yielded the best power density and efficiency for any scavenger operating from low-frequency (<10Hz) vibrations. A second-generation device was then fabricated. It generated a peak power of 288{micro}W and an average power of 5.8{micro}W from an input acceleration of 9.8m/s{sup 2} at 10Hz. The device operates over a frequency range of 20Hz. The internal volume of the generator is 2.1cm{sup 3} (3.7cm{sup 3} including casing), half of a standard AA battery. Lastly, a piezoelectric version of the PFIG is currently being developed. This device clearly demonstrates one of the key features of the PFIG architecture, namely that it is suitable for MEMS integration, more so than resonant generators, by incorporating a brittle bulk piezoelectric ceramic. This is the first micro-scale piezoelectric generator capable of <10Hz operation. The

Apoptotic and free radical scavenging properties of the methanolic extract of Gentianella alborosea.

Science.gov (United States)

Acero, Nuria; Llinares, Francisco; Galán de Mera, Antonio; Oltra, Beatriz; Muñoz-Mingarro, Dolores

2006-09-01

Gentianella alborosea ("Hercampure") is a Peruvian species used in folk medicine for the treatment of a variety of health disorders. We tested the free radical scavenging (DPPH) and induction of apoptosis on a human uterus tumor cell line (HeLa) by its methanolic extract. The results showed a noticeable radical scavenging activity and a dose-dependent apoptotic effect.

[In vitro anti-inflammatory and free radical scavenging activities of flavans from Ilex centrochinensis].

Science.gov (United States)

Li, Lu-jun; Yu, Li-juan; Li, Yan-ci; Liu, Meng-yuan; Wu, Zheng-zhi

2015-04-01

This study was carried out to evaluate the anti-inflammatory and free radical scavenging activities of flavans from flex centrochinensis S. Y. Hu in vitro and their structure-activity relationship. LPS-stimulated RAW 264.7 macrophage was used as inflammatory model. MTT assay for cell availability, Griess reaction for nitric oxide (NO) production, the content of TNF-alpha, IL-1beta, IL-6 and PGE, were detected with ELISA kits; DPPH, superoxide anion and hydroxyl free radicals scavenging activities were also investigated. According to the result, all flavans tested exhibited anti-inflammatory effect in different levels. Among them, compounds 1, 3, 4 and 6 showed potent anti-inflammatory effect through the inhibition of NO, TNF-alpha, IL-lp and IL-6, of which 1 was the most effective inhibitor, however, 2 and 5 were relatively weak or inactive. The order of free radical scavenging activities was similar to that of anti-inflammatory activities. Therefore, these results suggest that 3, 4 and 6, especially of 1, were,in part responsible for the anti-inflammatory and free radical scavenging activity of Ilex centrochinensis. Hydroxyl group at 4'-position of B-ring plays an important role in the anti-inflammatory and free radical scavenging capacities.

Variations of Antioxidant Properties and NO Scavenging Abilities during Fermentation of Tea

Science.gov (United States)

Xu, Yang; Zhao, Hang; Zhang, Min; Li, Chun-Jie; Lin, Xue-Zhen; Sheng, Jun; Shi, Wei

2011-01-01

Tea is known as one of the most popular beverages in the world, which is believed to be beneficial for health. The main components in tea will change a lot depending on the different processes of fermentation, and thus the effects of different teas on human health may differ. The aim of this study is to explore the varied abilities of reactive oxygen species (ROS) and nitric oxide (NO) scavenging during the fermentation of tea. In this study, we conducted the in vitro experiments which involved some reaction systems indicating the abilities of scavenging ROS and NO. We also investigated the effects of tea and their components (catechins, theabrownins, caffeine) on the intracellular levels of ROS and NO, using Raw 264.7 cells as the model. We found that regardless of whether it was out of cell system or in Raw 264.7 cells, the abilities of scavenging ROS would decrease during the fermentation of tea. Further, the post-fermented pu-erh tea showed the best effect on inhibiting the lipopolysaccharide (LPS)-induced production of NO. These findings indicated that the fermentation process caused a change of the components which might be due to the changes of their antioxidant properties and NO scavenging abilities. PMID:21845097

Reward Your Students with an Online Scavenger Hunt!

Science.gov (United States)

Board, Keith

2013-01-01

Do you have a class of students who do excellent work and whom you would like to give an enjoyable reward? Try an "Internet scavenger hunt" for a fun and educational change of pace! This article shares how to run the activity.

Effect of an inefficient electron scavenger on infrared- and visible-absorbing electrons in an ethanol matrix

International Nuclear Information System (INIS)

Noda, S.; Yoshida, K.; Ogasawara, M.; Yoshida, H.

1980-01-01

In order to obtain a deeper insight into the initial localization and the subsequent stabilization of electrons and to unravel the detailed mechanism of the electron scavenging reaction in a glassy ethanol matrix, spectrophotometric studies have been made on this matrix with toluene, an inefficient electron scavenger, γ irradiated at 4.2 0 K. Inhomogeneous depletion of the trapped electron spectrum by toluene indicates that IR-absorbing (lambda/sub max/ = 1500 nm) and visible-absorbing (lambda/sub max/ = 640 nm) electrons are initially generated, but that the former are unstable at higher temperature. Toluene scavenges the IR-absorbing electrons more efficiently by a factor of 10 than the visible-absorbing electrons. This selectivity is much higher than that of an efficient scavenger, such as benzyl chloride, as previously reported. The electron scavenging reaction results in the formation of the transient radical anion of toluene, which is readily protonated to yield the methylcyclohexadienyl radical at 77 0 K. 3 figures

Hemoglobin and heme scavenger receptors

DEFF Research Database (Denmark)

Nielsen, Marianne Jensby; Møller, Holger Jon; Moestrup, Søren Kragh

2010-01-01

Heme, the functional group of hemoglobin, myoglobin, and other hemoproteins, is a highly toxic substance when it appears in the extracellular milieu. To circumvent potential harmful effects of heme from hemoproteins released during physiological or pathological cell damage (such as hemolysis...... and rhabdomyolysis), specific high capacity scavenging systems have evolved in the mammalian organism. Two major systems, which essentially function in a similar way by means of a circulating latent plasma carrier protein that upon ligand binding is recognized by a receptor, are represented by a) the hemoglobin...

Computational studies of free radical-scavenging properties of phenolic compounds.

Science.gov (United States)

Alov, Petko; Tsakovska, Ivanka; Pajeva, Ilza

2015-01-01

For more than half a century free radical-induced alterations at cellular and organ levels have been investigated as a probable underlying mechanism of a number of adverse health conditions. Consequently, significant research efforts have been spent for discovering more effective and potent antioxidants / free radical scavengers for treatment of these adverse conditions. Being by far the most used antioxidants among natural and synthetic compounds, mono- and polyphenols have been the focus of both experimental and computational research on mechanisms of free radical scavenging. Quantum chemical studies have provided a significant amount of data on mechanisms of reactions between phenolic compounds and free radicals outlining a number of properties with a key role for the radical scavenging activity and capacity of phenolics. The obtained quantum chemical parameters together with other molecular descriptors have been used in quantitative structure-activity relationship (QSAR) analyses for the design of new more effective phenolic antioxidants and for identification of the most useful natural antioxidant phenolics. This review aims at presenting the state of the art in quantum chemical and QSAR studies of phenolic antioxidants and at analysing the trends observed in the field in the last decade.

Shape similarities and differences in the skulls of scavenging raptors.

Science.gov (United States)

Guangdi, S I; Dong, Yiyi; Ma, Yujun; Zhang, Zihui

2015-04-01

Feeding adaptations are a conspicuous feature of avian evolution. Bill and cranial shape as well as the jaw muscles are closely related to diet choice and feeding behaviors. Diurnal raptors of Falconiformes exhibit a wide range of foraging behaviors and prey preferences, and are assigned to seven dietary groups in this study. Skulls of 156 species are compared from the dorsal, lateral and ventral views, by using geometric morphometric techniques with those landmarks capturing as much information as possible on the overall shape of cranium, bill, orbits, nostrils and attachment area for different jaw muscles. The morphometric data showed that the skull shape of scavengers differ significantly from other raptors, primarily because of different feeding adaptations. As a result of convergent evolution, different scavengers share generalized common morphology, possessing relatively slender and lower skulls, longer bills, smaller and more sideward orbits, and more caudally positioned quadrates. Significant phylogenetic signals suggested that phylogeny also played important role in shape variation within scavengers. New World vultures can be distinguished by their large nostrils, narrow crania and small orbits; Caracaras typically show large palatines, crania and orbits, as well as short, deep and sharp bill.

The scavenging effects of tea polyphenol and quercetin on active oxygen species

International Nuclear Information System (INIS)

Fang Ruoying; Cheng Jiwu; Hu Tianxi; Tu Tiechen; Dong Jirong; Wang Wenfeng; Lin Nianyun

1993-01-01

The abilities of scavenging active oxygen species, O 2 free radical and OH., by tea polyphenols and quercetin have been studied by chemiluminescence, ESR and pulse radiolysis. Tea polyphenols and quercetin are all phenolic antioxidants. The synergetic studies show that both tea polyphenols and quercetin are strong free radical scavengers. Tea polyphenols are better than quercetin. the results from CL studies are in good accord with those from ESR and PR studies

Nature or Nurture? Gender Roles Scavenger Hunt

Science.gov (United States)

Whalen, Shannon; Maurer-Starks, Suanne

2008-01-01

The examination of gender roles and stereotypes and their subsequent impact on sexual behavior is a concept for discussion in many sex education courses in college and sex education units in high school. This analysis often leads to a discussion of the impact of nature vs. nurture on gender roles. The gender roles scavenger hunt is an interactive…

The ecosystem baseline for particle flux in the Northern Gulf of Mexico

Directory of Open Access Journals (Sweden)

S.L.C. Giering

2018-01-01

Full Text Available Response management and damage assessment during and after environmental disasters such as the Deepwater Horizon (DWH oil spill require an ecological baseline and a solid understanding of the main drivers of the ecosystem. During the DWH event, a large fraction of the spilled oil was transported to depth via sinking marine snow, a routing of spilled oil unexpected to emergency response planners. Because baseline knowledge of particle export in the Northern Gulf of Mexico and how it varies spatially and temporally was limited, we conducted a detailed assessment of the potential drivers of deep (~1400 m depth particle fluxes during 2012–2016 using sediment traps at three contrasting sites in the Northern Gulf of Mexico: near the DWH site, at an active natural oil seep site, and at a site considered typical for background conditions. The DWH site, located ~70 km from the Mississippi River Delta, showed flux patterns that were strongly linked to the Mississippi nitrogen discharge and an annual subsequent surface bloom. Fluxes carried clear signals of combustion products, which likely originated from pyrogenic sources that were transported offshore via the Mississippi plume. The seep and reference sites were more strongly influenced by the open Gulf of Mexico, did not show a clear seasonal flux pattern, and their overall sedimentation rates were lower than those at the DWH site. At the seep site, based on polycyclic aromatic hydrocarbon data, we observed indications of three different pathways for “natural” oiled-snow sedimentation: scavenging by sinking particles at depth, weathering at the surface before incorporation into sinking particles, and entry into the food web and subsequent sinking in form of detritus. Overall, sedimentation rates at the three sites were markedly different in quality and quantity owing to varying degrees of riverine and oceanic influences, including natural seepage and contamination by combustion products.

Particle hygroscopicity during atmospheric new particle formation events: implications for the chemical species contributing to particle growth

Directory of Open Access Journals (Sweden)

Z. Wu

2013-07-01

Full Text Available This study examines the hygroscopicity of newly formed particles (diameters range 25–45 nm during two atmospheric new particle formation (NPF events in the German mid-level mountains during the Hill Cap Cloud Thuringia 2010 (HCCT-2010 field experiment. At the end of the NPF event involving clear particle growth, we measured an unusually high soluble particle fraction of 58.5% at 45 nm particle size. The particle growth rate contributed through sulfuric acid condensation only accounts for around 6.5% of the observed growth rate. Estimations showed that sulfuric acid condensation explained, however, only around 10% of that soluble particle fraction. Therefore, the formation of additional water-soluble matter appears imperative to explain the missing soluble fraction. Although direct evidence is missing, we consider water-soluble organics as candidates for this mechanism. For the case with clear growth process, the particle growth rate was determined by two alternative methods based on tracking the mode diameter of the nucleation mode. The mean particle growth rate obtained from the inter-site data comparison using Lagrangian consideration is 3.8 (± 2.6 nm h−1. During the same period, the growth rate calculated based on one site data is 5.0 nm h−1 using log-normal distribution function method. In light of the fact that considerable uncertainties could be involved in both methods, we consider both estimated growth rates consistent.

Joule heat production rate and the particle energy injection rate as a function of the geomagnetic indices AE and AL

International Nuclear Information System (INIS)

Ahn, B.; Akasofu, S.; Kamide, Y.

1983-01-01

As a part of the joint efforts of operating six meridian chains of magnetometers during the IMS, magnetic records from 71 stations are used to deduce the distribution of electric fields and currents in the polar ionosphere for March 17, 18, and 19, 1978. As a continuation of this project, we have constructed hourly distribution maps of the Joule heat production rate and their sum over the entire polar region on the three days. For this purpose the conductivity distribution is inferred at each instant partially on the basis of an empirical method devised by Ahn et al. (1982). The particle energy injection rate is estimated similarly by using an empirical method. The data set thus obtained allows us to estimate also the global Joule heat production rate U/sub J/, the global particle energy injection rate U/sub A/ and the sum U/sub Gamma/ of the two quantities. It is found that three global quantities (watt) are related almost linearly to the AE(nT) and AL(nT) indices. Our present estimates give the following relationships: U/sub J/ = 2.3 times 10 8 x AE 8 U/sub A/ = 0.6 times 10 8 x AE 8 and U/sub I/ = 2.9 times 10 8 x AE: U/sub J/ = 3.0 times 10 8 x AL 8 U/sub A/ = 0.8 times 10 8 x AL, and U/sub I/ = 3.8 times 10 8 x AL

Free radical scavenging potential, reducing power, phenolic and biochemical constituents of Porphyra species from India

Digital Repository Service at National Institute of Oceanography (India)

Pise, N.M.; Jena, K.B.; Maharana, D.; Gaikwad, D.; Jagtap, T.G.

. Antioxidant potentials of algae were assessed through phenolic content, 2, 2-diphenyl-1- picrylhydrazyl (DPPH) activity, hydrogen peroxide (H sub(2)O sub(2)), scavenging power and reducing potential. A dose-dependent free radical scavenging action against DPPH...

The French Paradox: Determining the Superoxide-Scavenging Capacity of Red Wine and Other Beverages

Science.gov (United States)

Logan, Barry A.; Hammond, Matthew P.; Stormo, Benjamin M.

2008-01-01

Plant-derived phenolic compounds such as those found in red wine, tea, and certain fruit juices may protect against cardiovascular disease by detoxifying (scavenging) superoxide and other unstable reactive oxygen species. We present a laboratory exercise that can be used to assess the superoxide-scavenging capacity of beverages. Among the…

Atmospheric washout of radioactive aerosol for different types of precipitation events

International Nuclear Information System (INIS)

Bernauer, Felix

2015-01-01

classes of crystal types and three classes of riming was developed. A number of meteorologically stable precipitation events was identified, including 34680 minutes of precipitation with 74% in solid, 19% in mixed and 7% in liquid phase. In agreement with literature the calculated scavenging coefficients were found in a range from (5.0±0.7). 10 -5 s -1 to (1.0±0.2). 10 -3 s -1 . As expected, the scavenging coefficients showed a clear Green eld gap between 30nm and 60 nm. The Green field gap was more pronounced for liquid phase events than for mixed and solid phase events. In the particle size range between 30 nm and 60 nm solid phase events showed the largest scavenging coefficients. Due to the very efficient interception and impaction mechanisms, mixed phase events showed the largest scavenging coefficients for aerosol particles larger than 60 nm. For solid phase precipitation events, and aerosol particles larger than 30 nm, the dependence of the scavenging coefficient on maximum dimension and vertical velocity was not as pronounced as the dependence on hydrometeor crystal type and surface structure. As expected, all types of precipitation showed increasing mean scavenging coefficients averaged over the whole aerosol particle size range, for increasing precipitation rates. The clearest dependence of the scavenging coefficient on precipitation rate was observed for liquid phase precipitation, while for solid phase precipitation additionally to the precipitation rate also hydrometeor crystal type and surface structure played an important role. Parameterizing the scavenging coefficient λ as a function of precipitation rate I using the equation λ = A . (I/I 0 ) B , is commonly done in decision support systems and atmospheric transport models. The values for A and B are fixed and do not depend on the type of precipitation. The most important result of this study is that precipitation events consisting of different types of hydrometeors can be parametrized by different

Atmospheric washout of radioactive aerosol for different types of precipitation events

Energy Technology Data Exchange (ETDEWEB)

Bernauer, Felix

2015-12-15

classes of crystal types and three classes of riming was developed. A number of meteorologically stable precipitation events was identified, including 34680 minutes of precipitation with 74% in solid, 19% in mixed and 7% in liquid phase. In agreement with literature the calculated scavenging coefficients were found in a range from (5.0±0.7). 10{sup -5}s{sup -1} to (1.0±0.2). 10{sup -3}s{sup -1}. As expected, the scavenging coefficients showed a clear Green eld gap between 30nm and 60 nm. The Green field gap was more pronounced for liquid phase events than for mixed and solid phase events. In the particle size range between 30 nm and 60 nm solid phase events showed the largest scavenging coefficients. Due to the very efficient interception and impaction mechanisms, mixed phase events showed the largest scavenging coefficients for aerosol particles larger than 60 nm. For solid phase precipitation events, and aerosol particles larger than 30 nm, the dependence of the scavenging coefficient on maximum dimension and vertical velocity was not as pronounced as the dependence on hydrometeor crystal type and surface structure. As expected, all types of precipitation showed increasing mean scavenging coefficients averaged over the whole aerosol particle size range, for increasing precipitation rates. The clearest dependence of the scavenging coefficient on precipitation rate was observed for liquid phase precipitation, while for solid phase precipitation additionally to the precipitation rate also hydrometeor crystal type and surface structure played an important role. Parameterizing the scavenging coefficient λ as a function of precipitation rate I using the equation λ = A . (I/I{sub 0}){sup B}, is commonly done in decision support systems and atmospheric transport models. The values for A and B are fixed and do not depend on the type of precipitation. The most important result of this study is that precipitation events consisting of different types of hydrometeors can be

[Correlation Between Functional Groups and Radical Scavenging Activities of Acidic Polysaccharides from Dendrobium].

Science.gov (United States)

Liao, Ying; Yuan, Wen-yu; Zheng, Wen-ke; Luo, Ao-xue; Fan, Yi-jun

2015-11-01

To compare the radical scavenging activity of five different acidic polysaccharides, and to find the correlation with the functional groups. Alkali extraction method and Stepwise ethanol precipitation method were used to extract and concentrate the five Dendrobium polysaccharides, and to determine the contents of sulfuric acid and uronic acid of each kind of acidic polysaccharides, and the scavenging activity to ABTS+ radical and hydroxyl radical. Functional group structures were examined by FTIR Spectrometer. Five kinds of Dendrobium polysaccharides had different ability of scavenging ABTS+ free radical and hydroxyl free radical. Moreover, the study had shown that five kinds of antioxidant activity of acidic polysaccharides had obvious correlation withuronic acid and sulfuric acid. The antioxidant activity of each sample was positively correlated with the content of uronic acid, and negatively correlated with the content of sulfuric acid. Sulfuric acid can inhibit the antioxidant activity of acidic polysaccharide but uronic acid can enhance the free radical scavenging activity. By analyzing the structure characteristics of five acidic polysaccharides, all samples have similar structures, however, Dendrobium denneanum, Dendrobium devonianum and Dendrobium officinale which had β configuration have higher antioxidant activity than Dendrobium nobile and Dendrobium fimbriatum which had a configuration.

Gallic acid as an oxygen scavenger in bio-based multilayer packaging films

OpenAIRE

Pant, Astrid; Sängerlaub, Sven; Müller, Kajetan

2017-01-01

Oxygen scavengers are used in food packaging to protect oxygen-sensitive food products. A mixture of gallic acid (GA) and sodium carbonate was used as an oxygen scavenger (OSc) in bio-based multilayer packaging films produced in a three-step process: compounding, flat film extrusion, and lamination. We investigated the film surface color as well as oxygen absorption at different relative humidities (RHs) and temperatures, and compared the oxygen absorption of OSc powder, monolayer films, and ...

Effect of particle-particle shearing on the bioleaching of sulfide minerals.

Science.gov (United States)

Chong, N; Karamanev, D G; Margaritis, A

2002-11-05

The biological leaching of sulfide minerals, used for the production of gold, copper, zinc, cobalt, and other metals, is very often carried out in slurry bioreactors, where the shearing between sulfide particles is intensive. In order to be able to improve the efficiency of the bioleaching, it is of significant importance to know the effect of particle shearing on the rate of leaching. The recently proposed concept of ore immobilization allowed us to study the effect of particle shearing on the rate of sulfide (pyrite) leaching by Thiobacillus ferrooxidans. Using this concept, we designed two very similar bioreactors, the main difference between which was the presence and absence of particle-particle shearing. It was shown that when the oxygen mass transfer was not the rate-limiting step, the rate of bioleaching in the frictionless bioreactor was 2.5 times higher than that in a bioreactor with particle friction (shearing). The concentration of free suspended cells in the frictionless bioreactor was by orders of magnitude lower than that in the frictional bioreactor, which showed that particle friction strongly reduces the microbial attachment to sulfide surface, which, in turn, reduces the rate of bioleaching. Surprisingly, it was found that formation of a layer of insoluble iron salts on the surface of sulfide particles is much slower under shearless conditions than in the presence of particle-particle shearing. This was explained by the effect of particle friction on liquid-solid mass transfer rate. The results of this study show that reduction of the particle friction during bioleaching of sulfide minerals can bring important advantages not only by increasing significantly the bioleaching rate, but also by increasing the rate of gas-liquid oxygen mass transfer, reducing the formation of iron precipitates and reducing the energy consumption. One of the efficient methods for reduction of particle friction is ore immobilization in a porous matrix. Copyright 2002

Development of nitroxide radicals–containing polymer for scavenging reactive oxygen species from cigarette smoke

International Nuclear Information System (INIS)

Yoshitomi, Toru; Kuramochi, Kazuhiro; Binh Vong, Long; Nagasaki, Yukio

2014-01-01

We developed a nitroxide radicals–containing polymer (NRP), which is composed of poly(4-methylstyrene) possessing nitroxide radicals as a side chain via amine linkage, to scavenge reactive oxygen species (ROS) from cigarette smoke. In this study, the NRP was coated onto cigarette filters and its ROS-scavenging activity from streaming cigarette smoke was evaluated. The intensity of electron spin resonance signals of the NRP in the filter decreased after exposure to cigarette smoke, indicating consumption of nitroxide radicals. To evaluate the ROS-scavenging activity of the NRP-coated filter, the amount of peroxy radicals in an extract of cigarette smoke was measured using UV–visible spectrophotometry and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The absorbance of DPPH at 517 nm decreased with exposure to cigarette smoke. When NRP-coated filters were used, the decrease in the absorbance of DPPH was prevented. In contrast, both poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters, which have no nitroxide radical, did not show any effect, indicating that the nitroxide radicals in the NRP scavenge the ROS in cigarette smoke. As a result, the extract of cigarette smoke passed through the NRP-coated filter has a lower cellular toxicity than smoke passed through poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters. Accordingly, NRP is a promising material for ROS scavenging from cigarette smoke. (papers)

Free radical scavenging activity and phenolic contents of ...

African Journals Online (AJOL)

Anthocleista djalonensis extract is widely used in Nigerian folk medicine to treat conditions whose pathogenesis implicate oxidative stress, such as diabetes and hepatitis. However, little is known of the mechanism underlying these activities. In this study, the free radical scavenging potential of a methanol extract of A.

The significance of cooking for early hominin scavenging.

Science.gov (United States)

Smith, Alex R; Carmody, Rachel N; Dutton, Rachel J; Wrangham, Richard W

2015-07-01

Meat scavenged by early Homo could have contributed importantly to a higher-quality diet. However, it has been suggested that because carrion would normally have been contaminated by bacteria it would have been dangerous and therefore eaten rarely prior to the advent of cooking. In this study, we quantified bacterial loads on two tissues apparently eaten by hominins, meat and bone marrow. We tested the following three hypotheses: (1) the bacterial loads on exposed surfaces of raw meat increase within 24 h to potentially dangerous levels, (2) simple roasting of meat on hot coals kills most bacteria, and (3) fewer bacteria grow on marrow than on meat, making marrow a relatively safe food. Our results supported all three hypotheses. Our experimental data imply that early hominins would have found it difficult to scavenge safely without focusing on marrow, employing strategies of carrion selection to minimize pathogen load, or cooking. Copyright © 2015 Elsevier Ltd. All rights reserved.

Characterization of mineral particles in winter fog of Beijing analyzed by TEM and SEM.

Science.gov (United States)

Li, Weijun; Shao, Longyi

2010-02-01

Aerosol samples were collected during winter fog and nonfog episodes in Beijing. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were applied to study morphologies, sizes, and compositions of aerosol particles. TEM observation indicates that most mineral particles collected in fog episode are scavenged in fog droplets. Number-size distributions of mineral particles collected in fog and nonfog episodes show two main peaks at the ranges of 0.1-0.3 and 1-2.5 microm, respectively. Based on their major compositions, mineral particles mainly include Si-rich, Ca-rich, and S-rich. Average S/Ca ratio of mineral particles collected in fog episode is 6.11, being eight times higher than that in nonfog episodes. Development mechanism of individual mineral particles in fog droplets is proposed. It is suggested that mineral particles with abundant alkaline components (e.g., "Ca-rich" particles) occurred in air should alleviate acidic degree of fog and contribute to complexity of fog droplets in Beijing.

Chlorine dioxide as phenol and H2S scavenger - formation of halogenated phenols and subsequent environmental risk

Energy Technology Data Exchange (ETDEWEB)

Melbye, Alf G.; Faksness, Liv-Guri; Knudsen, Boerre Leif

2006-03-15

Formation of halogenated phenols as side products from treatment of produced water with aqueous chlorine dioxide has been investigated. The literature describes formation of halogenated hydrocarbons in effluent treatment using chlorine, hypochlorite and chlorine dioxide. A new chlorine dioxide product, originally intended as a H2S scavenger in the oil and gas industry, has been tested both as a phenol scavenger and H2S-scavenger for produced water applications. The concern about the possible formation of halogenated by-products initiated laboratory testing of chlorine dioxide as phenol and H2S scavenger for produced water applications. The tests also included synthetic matrixes containing phenols, and the tests show that halogenated phenols, mainly brominated species, are found in produced water after treatment with chlorine dioxide. Due to potential environmental risk from halogenated organic contaminants, the use of chlorine dioxide as phenol and H2S scavenger is not recommended. (Author)

Graphene supported Sn-Sb rate at carbon core-shell particles as a superior anode for lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Chen, Shuangqiang; Chen, Peng; Wang, Yong [Department of Chemical Engineering, School of Environmental and Chemical Engineering, Shanghai University (China); Wu, Minghong; Pan, Dengyu [Institute of Nanochemistry and Nanobiology, Shanghai Univ. (China)

2010-10-15

This paper reports the preparation and Li-storage properties of graphene nanosheets(GNS), GNS supported Sn-Sb rate at carbon (50-150 nm) and Sn-Sb nanoparticles (5-10 nm). The best cycling performance and excellent high rate capabilities were observed for GNS-supported Sn-Sb rate at carbon core-shell particles, which exhibited initial capacities of 978, 850 and 668 mAh/g respectively at 0.1C, 2C and 5C (1C = 800 mA/g) with good cyclability. Besides the GNS support, the carbon skin around Sn-Sb particles is believed to be a key factor to improve electrochemical properties of Sn-Sb. (author)

Evaluation of Free Radical Scavenging Activity in Ethanolic Extract from Promising Accessions of Curcuma aeruginosa RoxB.

Directory of Open Access Journals (Sweden)

Waras Nurcholis

2017-11-01

Full Text Available This study evaluated the free radical scavenging activity in ethanolic extracts from 20 accessions of Curcuma aeruginosa. The radical scavenging activity of the extract accessions was investigated with 2,2-diphenyl-1-picrylhydrazyl (DPPH radical. IC50 values for DPPH radical scavenging activity ranged from 89.81 to 505.65 µg mL-1. Based on IC50 values, twenty accessions of C. aeruginosa can be divided into three groups: strong (two accessions; moderate (seventeen accessions; and low (one accession of DPPH scavenger. Sukoharjo (SH and Muara Bungo (MB showed promising accessions for antioxidant potential, thus these accessions important to selection for future breeding program in pharmaceutical products.

CXCR7 functions as a scavenger for CXCL12 and CXCL11.

Directory of Open Access Journals (Sweden)

Ulrike Naumann

2010-02-01

Full Text Available CXCR7 (RDC1, the recently discovered second receptor for CXCL12, is phylogenetically closely related to chemokine receptors, but fails to couple to G-proteins and to induce typical chemokine receptor mediated cellular responses. The function of CXCR7 is controversial. Some studies suggest a signaling activity in mammalian cells and zebrafish embryos, while others indicate a decoy activity in fish. Here we investigated the two propositions in human tissues.We provide evidence and mechanistic insight that CXCR7 acts as specific scavenger for CXCL12 and CXCL11 mediating effective ligand internalization and targeting of the chemokine cargo for degradation. Consistently, CXCR7 continuously cycles between the plasma membrane and intracellular compartments in the absence and presence of ligand, both in mammalian cells and in zebrafish. In accordance with the proposed activity as a scavenger receptor CXCR7-dependent chemokine degradation does not become saturated with increasing ligand concentrations. Active CXCL12 sequestration by CXCR7 is demonstrated in adult mouse heart valves and human umbilical vein endothelium.The finding that CXCR7 specifically scavenges CXCL12 suggests a critical function of the receptor in modulating the activity of the ubiquitously expressed CXCR4 in development and tumor formation. Scavenger activity of CXCR7 might also be important for the fine tuning of the mobility of hematopoietic cells in the bone marrow and lymphoid organs.

Radical scavenging potentials of single and combinatorial herbal formulations in vitro

Directory of Open Access Journals (Sweden)

Okey A. Ojiako

2016-04-01

Full Text Available Reactive oxygen and nitrogen species (RONS are involved in deleterious/beneficial biological processes. The present study sought to investigate the capacity of single and combinatorial herbal formulations of Acanthus montanus, Emilia coccinea, Hibiscus rosasinensis, and Asystasia gangetica to act as superoxide radicals (SOR, hydrogen peroxide (HP, nitric oxide radical (NOR, hydroxyl radical (HR, and 2,2-diphenyl-1-picrylhydrazyl (DPPH radical antagonists using in vitro models. The herbal extracts were single herbal formulations (SHfs, double herbal formulations (DHfs, triple herbal formulations (THfs, and a quadruple herbal formulation (QHf. The phytochemical composition and radical scavenging capacity index (SCI of the herbal formulations were measured using standard methods. The flavonoids were the most abundant phytochemicals present in the herbal extracts. The SCI50 defined the concentration (μg/mL of herbal formulation required to scavenge 50% of the investigated radicals. The SHfs, DHfs, THfs, and QHf SCI50 against the radicals followed the order HR > SOR > DPPH radical > HP > NOR. Although the various herbal formulations exhibited ambivalent antioxidant activities in terms of their radical scavenging capabilities, a broad survey of the results of the present study showed that combinatorial herbal formulations (DHfs, THfs, and QHf appeared to exhibit lower radical scavenging capacities than those of the SHfs in vitro.

Nitric oxide radical scavenging potential of some Elburz medicinal ...

African Journals Online (AJOL)

ONOS

2010-08-09

Aug 9, 2010 ... NO is also implicated in inflammation and other pathological ... adhesion and prevention of smooth muscle cell prolife- ... reduce NO levels is making use of NO scavengers. For ..... human nutrition and health are considerable.

Identification, characterisation and composition of scavengeable feed resources for rural poultry production in Central Tanzania

NARCIS (Netherlands)

Goromela, E.H.; Kwakkel, R.P.; Verstegen, M.W.A.; Katule, A.M.

2007-01-01

A participatory study was carried out in four villages of central Tanzania to appraise existing and potential scavengeable feed resources available for rural poultry. In addition, proximate analysis of selected scavengeable feed resources including chicken crop and gizzards contents was carried out

Tourism in protected areas: Disentangling road and traffic effects on intra-guild scavenging processes.

Science.gov (United States)

Donázar, José Antonio; Ceballos, Olga; Cortés-Avizanda, Ainara

2018-07-15

The expansion of road networks and the increase in traffic have emerged in recent years as key threats to the conservation of biodiversity. This is particularly concerning in many protected areas because the increase of recreational activities requiring the use of vehicles. Effects of roads and traffic within guild scenarios and ecological processes remain however poorly known. Here we examined how road proximity and traffic intensity influence patterns of resource use in an Old-World avian scavenger guild living in a protected natural park in northern Spain. We experimentally placed 130 carcasses at different distances from a scenic road in the centre of the park. Vehicles were recorded by means of traffic counters which revealed that maximum numbers were reached during weekends and holidays and during the middle hours of the day. Avian scavenger attendance at carcasses was recorded by means of camera-traps. Obligated scavengers, Eurasian griffon (Gyps fulvus) and Egyptian vultures (Neophron percnopterus) were frequently observed (59.4% and 37.7% of the consumed carcasses) together with five other facultative scavenger species. We found that the richness (number of species) and the probability of consumption of the resource were reduced the smaller the distance to the road and in days with higher traffic intensity. The same factors affected the probability of presence of all the scavenger species. Moreover, some of them, notably griffon vultures, showed hourly patterns of carcass attendance suggesting avoidance of maximum traffic levels. Our results highlight that roads and traffic would trigger consequences on the structure and functioning of scavenger food webs, which may be particularly concerning in protected areas with remarkable levels of biodiversity. Future regulations at protected areas should couple both traffic and tourist affluence with wildlife conservation. In this way important ecological processes would be preserved while maintaining a good

Simulation Modeling and Optimization of Uniflow Scavenging System Parameters on Opposed-Piston Two-Stroke Engines

Directory of Open Access Journals (Sweden)

Fukang Ma

2018-04-01

Full Text Available Based on the introduction of opposed-piston two-stroke (OP2S gasoline direct injection (GDI engines, the OP2S-GDI engine working principle and scavenging process were analyzed. GT-Power software was employed to model the working process based on the structural style and principle of OP2S-GDI engine. The tracer gas method and OP2S-GDI engine experiment were employed for model validation at full load of 6000 rpm. The OP2S-GDI engine scavenging system parameters were optimized, including intake port height stroke ratio, intake port circumference ratio, exhaust port height stroke ratio, exhaust port circumference ratio, and opposed-piston motion phase difference. At the same time, the effect of the port height stroke ratio and opposed-piston motion phase difference on effective compression ratio and expansion ratio were considered, and the indicated work was employed as the optimization objective. A three-level orthogonal experiment was applied in the calculation process to reduce the calculation work. The influence and correlation coefficient on the scavenging efficiency and delivery ratio were investigated by the orthogonal experiment analysis of intake and exhaust port height stroke ratio and circular utilization. The effect of the scavenging system parameters on delivery ratio, scavenging efficiency and indicated work were calculated to obtain the best parameters. The results show that intake port height stroke ratio is the main factor for the delivery ratio, while exhaust port height stroke ratio is the main factor to engine delivery ratio and scavenging efficiency.

Transport and deposition of particles and radionuclides at the Puy de Dome, France

International Nuclear Information System (INIS)

Bourcier, L.

2009-01-01

Aerosol particles play a key role both on air quality and on the radiative balance of the Earth. Their sources, as well as their deposition are key stages in their life cycle. This work is a contribution in a better knowledge of the chemical composition of particles, cloud droplets and rain droplets. The specificity of our study is to couple, on three sampling sites (Puy de Dome (1465 m a.s.l.), Opme (660 m a.s.l.) and Cezeaux (400 m a.s.l.)), observations on the chemical composition and the radionuclides activity in cloud/rain/aerosol phases. We observed, in aerosol phase, ionic and carbonaceous concentrations and radionuclides activity higher in summer than in winter at the Puy de Dome, inverse of the seasonal variation observed at the Cezeaux for chemical compounds. From these observations, we offer a representative composition de each mass air type. This work is supplemented by a study of cloud and rain liquid, which allow us to study the scavenging of the pollutants by the rain. The chemical composition of the rain reveals a similar behaviour to that of the particles at the Puy de Dome, indicating that the role of activation and scavenging of particles is preponderant in the composition of the rain. This is confirmed by a study of the environmental and structural factors of the rain which do not seem to influence the washout ratio in a significant manner. Our work highlights the role of long range transport of pollutants in the composition of atmospheric liquid phase. (author)

Antioxidant and Nitrite-Scavenging Capacities of Phenolic Compounds from Sugarcane (Saccharum officinarum L. Tops

Directory of Open Access Journals (Sweden)

Jian Sun

2014-08-01

Full Text Available Sugarcane tops were extracted with 50% ethanol and fractionated by petroleum ether, ethyl acetate (EtOAc, and n-butyl alcohol successively. Eight phenolic compounds in EtOAc extracts were purified through silica gel and Sephadex LH-20 column chromatographies, and then identified by nuclear magnetic resonance and electrospray ionization mass spectra. The results showed that eight phenolic compounds from EtOAc extracts were identified as caffeic acid, cis-p-hydroxycinnamic acid, quercetin, apigenin, albanin A, australone A, moracin M, and 5'-geranyl-5,7,2',4'-tetrahydroxyflavone. The antioxidant and nitrite-scavenging capacities of different solvent extracts correlated positively with their total phenolic (TP contents. Amongst various extracts, EtOAc extracts possessed the highest TP content and presented the strongest oxygen radical absorbance capacity (ORAC, 1,1'-diphenyl-2-picrylhydrazyl (DPPH radical-scavenging capacity, 2,2'-azobis-3-ethylbenthiaazoline-6-sulfonic acid (ABTS radical-scavenging capacity, ferric reducing antioxidant power (FRAP and nitrite-scavenging capacity. Thus, sugarcane tops could be promoted as a source of natural antioxidant.

Diet and scavenging habits of the smooth skate Dipturus innominatus.

Science.gov (United States)

Forman, J S; Dunn, M R

2012-04-01

The diet of smooth skate Dipturus innominatus was determined from examination of stomach contents of 321 specimens of 29·3-152·0 cm pelvic length, sampled from research and commercial trawlers at depths of 231-789 m on Chatham Rise, New Zealand. The diet was dominated by the benthic decapods Metanephrops challengeri and Munida gracilis, the natant decapod Campylonotus rathbunae and fishes from 17 families, of which hoki Macruronus novaezelandiae, sea perch Helicolenus barathri, various Macrouridae and a variety of discarded fishes were the most important. Multivariate analyses indicated the best predictors of diet variability were D. innominatus length and a spatial model. The diet of small D. innominatus was predominantly small crustaceans, with larger crustaceans, fishes and then scavenged discarded fishes increasing in importance as D. innominatus got larger. Scavenged discards were obvious as fish heads or tails only, or skeletal remains after filleting, often from pelagic species. Demersal fish prey were most frequent on the south and west Chatham Rise, in areas where commercial fishing was most active. Dipturus innominatus are highly vulnerable to overfishing, but discarding practices by commercial fishing vessels may provide a positive feedback to populations through improved scavenging opportunities. © 2012 NIWA. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.

An investigation of red fox (Vulpes vulpes) and Eurasian badger (Meles meles) scavenging, scattering, and removal of deer remains: forensic implications and applications.

Science.gov (United States)

Young, Alexandria; Márquez-Grant, Nicholas; Stillman, Richard; Smith, Martin J; Korstjens, Amanda H

2015-01-01

Within northwest Europe, especially the United Kingdom, the red fox (Vulpes vulpes) and the Eurasian Badger (Meles meles) are the largest wild scavengers capable of modifying a set of remains through scavenging. Knowledge of region-specific and species-typical scavenging behaviors of scavengers within the crime scene area and surroundings can aid in more efficient and accurate interpretations. The scavenging behaviors of captive and wild foxes and badgers were recorded and compared through actualistic methods and direct observation. The scavenging by wild foxes and badgers of surface-deposited baits and whole deer (Cervus nippon; Capreolus capreolus) in a woodland was observed and analyzed. Wild foxes were found to scavenge deer more frequently than badgers. The scavenging of deer remains by foxes was also compared with forensic cases. The scavenging pattern and recovery distances of deer and human remains scavenged by foxes were similar but were potentially affected by the condition and deposition of a body, and the presence of clothing. © 2014 American Academy of Forensic Sciences.

Effects of interactive transport and scavenging of smoke on the calculated temperature change resulting from large amounts of smoke

International Nuclear Information System (INIS)

MacCracken, M.C.; Walton, J.J.

1984-12-01

Several theoretical studies with numerical models have shown that substantial land-surface cooling can occur if very large amounts (approx. 100 x 10 12 = 100 Tg) of highly absorbing sooty-particles are injected high into the troposphere and spread instantaneously around the hemisphere (Turco et al., 1983; Covey et al. 1984; MacCracken, 1983). A preliminary step beyond these initial calculations has been made by interactively coupling the two-layer, three-dimensional Oregon State University general circulation model (GCM) to the three-dimensional GRANTOUR trace species model developed at the Lawrence Livermore National Laboratory. The GCM simulation includes treatment of tropospheric dynamics and thermodynamics and the effect of soot on solar radiation. The GRANTOUR simulation includes treatment of particle transport and scavenging by precipitation, although no satisfactory verification of the scavenging algorithm has yet been possible. We have considered the climatic effects of 150 Tg (i.e., the 100 Mt urban war scenario from Turco et al., 1983) and of 15 Tg of smoke from urban fires over North America and Eurasia. Starting with a perpetual July atmospheric situation, calculation of the climatic effects as 150 Tg of smoke are spread slowly by the winds, rather than instantaneously dispersed as in previous calculations, leads to some regions of greater cooling under the denser parts of the smoke plumes and some regions of less severe cooling where smoke arrival is delayed. As for the previous calculations, mid-latitude decreases of land surface air temperature for the 150 Tg injection are greater than 15 0 C after a few weeks. For a 15 Tg injection, however, cooling of more than several degrees centigrade only occurs in limited regions under the dense smoke plumes present in the first few weeks after the injection. 10 references, 9 figures

Identification of Radical Scavenging Compounds in Rhaponticum carthamoides by Means of LC-DAD-SPE-NMR

NARCIS (Netherlands)

Miliauskas, G.; Beek, van T.A.; Waard, de P.; Venskutonis, R.P.; Sudhölter, E.J.R.

2005-01-01

A hyphenated LC-DAD-SPE-NMR setup in combination with on-line radical scavenging detection has been applied for the identification of radical scavenging compounds in extracts of Rhaponticum carthamoides. After NMR measurements, the pure compounds were infused into a mass spectrometer. The technique

Trypsin Binding with Copper Ions Scavenges Superoxide: Molecular Dynamics-Based Mechanism Investigation

Directory of Open Access Journals (Sweden)

Xin Li

2018-01-01

Full Text Available Trypsin is a serine protease, which has been proved to be a novel superoxide scavenger. The burst of superoxide induced by polychlorinated biphenyls can be impeded by trypsin in both wild type and sod knockout mutants of Escherichia coli. The experimental results demonstrated that the activities of superoxide scavenging of trypsin were significantly accelerated by Cu ions. Also, with the addition of Cu ions, a new β-sheet (β7 transited from a random coil in the Cu(II-trypsin (TP system, which was favorable for the formation of more contacts with other sheets of trypsin. Residue–residue network analysis and the porcupine plots proved that the Cu ion in trypsin strengthened some native interactions among residues, which ultimately resulted in much greater stability of the Cu(II-TP system. Moreover, compact and stable trypsin structures with Cu ions might be responsible for significantly provoking the activity of superoxide scavenging.

Measurement of Localized Corrosion Rates at Inclusion Particles in AA7075 by In Situ Three Dimensional (3D) X-ray Synchrotron Tomography

Energy Technology Data Exchange (ETDEWEB)

Singh, Sudhanshu S.; Williams, Jason J.; Stannard, Tyler J.; Xiao, Xianghui; De Carlo, Francesco; Chawla, Nikhilesh

2016-03-01

In situ X-ray synchrotron tomography was used to measure the localized corrosion rate of Mg2Si particles present in 7075 aluminum alloys in deionized ultra-filtered (DIUF) water. The evolution of hydrogen bubbles was captured as a function of time and the measured volume was used to calculate the local corrosion rate of Mg2Si particles. It was shown that in the absence of chloride ions, stress was needed to create fresh particle surfaces, either by fracture or debonding, to initiate corrosion at the particles.

Predicting the Effects of Powder Feeding Rates on Particle Impact Conditions and Cold Spray Deposited Coatings

Science.gov (United States)

Ozdemir, Ozan C.; Widener, Christian A.; Carter, Michael J.; Johnson, Kyle W.

2017-10-01

As the industrial application of the cold spray technology grows, the need to optimize both the cost and the quality of the process grows with it. Parameter selection techniques available today require the use of a coupled system of equations to be solved to involve the losses due to particle loading in the gas stream. Such analyses cause a significant increase in the computational time in comparison with calculations with isentropic flow assumptions. In cold spray operations, engineers and operators may, therefore, neglect the effects of particle loading to simplify the multiparameter optimization process. In this study, two-way coupled (particle-fluid) quasi-one-dimensional fluid dynamics simulations are used to test the particle loading effects under many potential cold spray scenarios. Output of the simulations is statistically analyzed to build regression models that estimate the changes in particle impact velocity and temperature due to particle loading. This approach eases particle loading optimization for more complete analysis on deposition cost and time. The model was validated both numerically and experimentally. Further numerical analyses were completed to test the particle loading capacity and limitations of a nozzle with a commonly used throat size. Additional experimentation helped document the physical limitations to high-rate deposition.

Antioxidant properties of a radical-scavenging peptide purified from enzymatically prepared fish skin gelatin hydrolysate.

Science.gov (United States)

Mendis, Eresha; Rajapakse, Niranjan; Kim, Se-Kwon

2005-02-09

Hoki (Johnius belengerii) skin gelatin was hydrolyzed with three commercial enzymes to identify radical-scavenging potencies of derived peptides. Peptides derived from tryptic hydrolysate exhibited the highest scavenging activities on superoxide, carbon-centered 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals assessed by ESR spectroscopy. Following consecutive chromatographic separations of tryptic hydroolysate, the peptide sequence His-Gly-Pro-Leu-Gly-Pro-Leu (797 Da) acted as a strong radical scavenger under studied conditions. Further, this peptide could act as an antioxidant against linoleic acid peroxidation and the activity was closer to the highly active synthetic antioxidant butylated hydroxytoluene (BHT). In addition, antioxidative enzyme levels in cultured human hepatoma cells were increased in the presence of this peptide and it was presumed to be the peptide involved in maintaining the redox balance in the cell environment. Present data indicate that free-radical-scavenging activities of hoki skin gelatin peptides substantially contribute to their antioxidant properties measured in different oxidative systems.

Chemical Constituents with Free-Radical-Scavenging Activities from the Stem of Microcos paniculata

Directory of Open Access Journals (Sweden)

Yu Chen

2010-08-01

Full Text Available The free-radical-scavenging activities of various solvent extracts of Microcos paniculata were evaluated through in vitro model systems, such as 1,1-diphenyl-2-picrylhydrazyl (DPPH, 2,2'-azino-bis-(3-ethylbenzothiazoline-6-sulfonate (ABTS and Co (II EDTA-induced luminol chemiluminescence by flow injection. In all three of these systems the ethyl acetate (EtOAc extract showed the highest free-radical-scavenging activity compared with the other three (n-BuOH, water and petroleum ether extracts. Free-radical-scavenging assay-guided chromatographic separation of the EtOAc extract, using a normal-phase and reverse-phase silica gel column chromatography yielded five compounds: a new triterpene named methyl 3b-O-p-hydroxy-E-cinnamoyloxy-2a,23-dihydroxyolean-12-en-28-oate (1, whose spectral data are presented for the first time, together with four known compounds, epicatechin (2, 3-trans-feruloyl maslinic acid (3, maslinic acid (4 and sucrose (5. All of the compounds were isolated from Microcos paniculata for the first time. The compounds were identified by spectroscopic methods. Among them, compound 2 displayed significant free-radical-scavenging activity which is similar to that of standard antioxidant ascorbic acid (VC and therefore may be a promising natural antioxidant.

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

Energy Technology Data Exchange (ETDEWEB)

Kassel, Florian; Boer, Wim de [Institute for Experimental Nuclear Physics (IEKP), KIT, Karlsruhe (Germany); Guthoff, Moritz; Dabrowski, Anne [CERN, Meyrin (Switzerland)

2016-10-15

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb{sup -1} corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate-dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the transient current technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model, the rate-dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate-dependent measurements from a strong radioactive source, was able to predict the non-linear decrease of the

Severe signal loss in diamond beam loss monitors in high particle rate environments by charge trapping in radiation-induced defects

International Nuclear Information System (INIS)

Kassel, Florian; Boer, Wim de; Guthoff, Moritz; Dabrowski, Anne

2016-01-01

The beam condition monitoring leakage (BCML) system is a beam monitoring device in the compact muon solenoid (CMS) experiment at the large hadron collider (LHC). As detectors 32 poly-crystalline (pCVD) diamond sensors are positioned in rings around the beam pipe. Here, high particle rates occur from the colliding beams scattering particles outside the beam pipe. These particles cause defects, which act as traps for the ionization, thus reducing the charge collection efficiency (CCE). However, the loss in CCE was much more severe than expected from low rate laboratory measurements and simulations, especially in single-crystalline (sCVD) diamonds, which have a low initial concentration of defects. After an integrated luminosity of a few fb -1 corresponding to a few weeks of LHC operation, the CCE of the sCVD diamonds dropped by a factor of five or more and quickly approached the poor CCE of pCVD diamonds. The reason why in real experiments the CCE is much worse than in laboratory experiments is related to the ionization rate. At high particle rates the trapping rate of the ionization is so high compared with the detrapping rate, that space charge builds up. This space charge reduces locally the internal electric field, which in turn increases the trapping rate and recombination and hence reduces the CCE in a strongly non-linear way. A diamond irradiation campaign was started to investigate the rate-dependent electrical field deformation with respect to the radiation damage. Besides the electrical field measurements via the transient current technique (TCT), the CCE was measured. The experimental results were used to create an effective deep trap model that takes the radiation damage into account. Using this trap model, the rate-dependent electrical field deformation and the CCE were simulated with the software SILVACO TCAD. The simulation, tuned to rate-dependent measurements from a strong radioactive source, was able to predict the non-linear decrease of the CCE in

Free radical scavenging and cytotoxic activity of five commercial ...

African Journals Online (AJOL)

Polygonum cuspidatum), and pomegranate (Punica granatum). It shows radical scavenging activity in the following order, according to their median effective concentration (EC

Free radical scavengers and antioxidants from Lemongrass (Cymbopogon citratus (DC.) Stapf.).

Science.gov (United States)

Cheel, José; Theoduloz, Cristina; Rodríguez, Jaime; Schmeda-Hirschmann, Guillermo

2005-04-06

Methanol, MeOH/water extracts, infusion, and decoction of Cymbopogon citratus were assessed for free radical scavenging effects measured by the bleaching of the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical, scavenging of the superoxide anion, and inhibition of the enzyme xanthine oxidase (XO) and lipid peroxidation in human erythrocytes. The extracts presented effect in the DPPH and superoxide anion assay, with values ranging between 40 and 68% and 15-32% at 33 and 50 microg/mL, respectively, inhibited lipid peroxidation in erythrocytes by 19-71% at 500 microg/mL and were inactive toward the XO at 50 microg/mL. Isoorientin, isoscoparin, swertiajaponin, isoorientin 2' '-O-rhamnoside, orientin, chlorogenic acid, and caffeic acid were isolated and identified by spectroscopic methods. Isoorientin and orientin presented similar activities toward the DPPH (IC(50): 9-10 microM) and inhibited lipid peroxidation by 70% at 100 microg/mL. Caffeic and chlorogenic acid were active superoxide anion scavengers with IC(50) values of 68.8 and 54.2 microM, respectively, and a strong effect toward DPPH. Caffeic acid inhibited lipid peroxidation by 85% at 100 microg/mL.

Effects of baking conditions, dough fermentation, and bran particle size on antioxidant properties of whole-wheat pizza crusts.

Science.gov (United States)

Moore, Jeffrey; Luther, Marla; Cheng, Zhihong; Yu, Liangli Lucy

2009-02-11

This study investigated the effects of processing conditions including bran particle size, dough fermentation time, and baking time and temperature on the extractable antioxidant properties of whole-wheat pizza crust. Experiments were carried out using two different varieties of hard white winter wheat, Trego and Lakin. Antioxidant properties examined included oxygen radical absorbing capacity (ORAC), hydroxyl radical scavenging capacity (HOSC), relative 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity (RDSC), cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacity, total phenolic contents (TPC), and ferulic acid contents. Results indicated that bran particle size had no effect on the antioxidant properties evaluated. Increasing dough fermentation time from 0 to 48 h had no significant influence on antioxidant properties except HOSC, which increased as much as 28%, possibly as a result of increase in soluble free ferulic acid, which increased as much as 130%. Increasing baking temperature from 204 to 288 degrees C with a 7 min bake time increased all evaluated antioxidant properties by as much as 82%. Increasing baking time from 7 to 14 min with 204 degrees C baking temperature might increase some antioxidant properties as much as 60%. The results from this study suggest that longer dough fermentation times and increased baking time or temperature may be potential approaches to increase the antioxidant availability in whole-wheat pizza crust.

Effects of Scavenging System Configuration on In-Cylinder Air Flow Organization of an Opposed-Piston Two-Stroke Engine

Directory of Open Access Journals (Sweden)

Fukang Ma

2015-06-01

Full Text Available In-cylinder air flow is very important from the point of view of mixture formation and combustion. In this direction, intake chamber structure and piston crown shape play a very crucial role for in-cylinder air pattern of opposed-piston two-stroke (OP2S engines. This study is concerned with the three-dimensional (3D computational fluid dynamics (CFD analysis of in-cylinder air motion coupled with the comparison of predicted results with the zero-dimensional (0D parametric model. Three configurations viz., a flat piston uniform scavenging chamber, a flat piston non-uniform scavenging chamber and a pit piston non-uniform scavenging chamber have been studied. 0D model analysis of in-cylinder air flow is consistent with 3D CFD simulation. It is concluded that a pit piston non-uniform scavenging chamber is the best design from the point of view of tumble ratio, turbulent kinetic energy and turbulent intensity, which play very important roles in imparting proper air motion. Meanwhile a flat piston uniform scavenging chamber can organize a higher swirl ratio and lower tumble ratio which is important to improve the scavenging process.

Improving the API dissolution rate during pharmaceutical hot-melt extrusion I: Effect of the API particle size, and the co-rotating, twin-screw extruder screw configuration on the API dissolution rate.

Science.gov (United States)

Li, Meng; Gogos, Costas G; Ioannidis, Nicolas

2015-01-15

The dissolution rate of the active pharmaceutical ingredients in pharmaceutical hot-melt extrusion is the most critical elementary step during the extrusion of amorphous solid solutions - total dissolution has to be achieved within the short residence time in the extruder. Dissolution and dissolution rates are affected by process, material and equipment variables. In this work, we examine the effect of one of the material variables and one of the equipment variables, namely, the API particle size and extruder screw configuration on the API dissolution rate, in a co-rotating, twin-screw extruder. By rapidly removing the extruder screws from the barrel after achieving a steady state, we collected samples along the length of the extruder screws that were characterized by polarized optical microscopy (POM) and differential scanning calorimetry (DSC) to determine the amount of undissolved API. Analyses of samples indicate that reduction of particle size of the API and appropriate selection of screw design can markedly improve the dissolution rate of the API during extrusion. In addition, angle of repose measurements and light microscopy images show that the reduction of particle size of the API can improve the flowability of the physical mixture feed and the adhesiveness between its components, respectively, through dry coating of the polymer particles by the API particles. Copyright © 2014. Published by Elsevier B.V.

Smelting reduction rate of fine Wustite particles in a CO gas-conveyed bed; CO gas yuso sonai Wustite biryushi no yoyu kangen sokudo

Energy Technology Data Exchange (ETDEWEB)

Hayashi, S; Iguchi, Y [Nagoya Institute of Technology, Nagoya (Japan)

1999-06-01

Using a laboratory scale fine particles-gas conveyed bed, the reduction rates of liquid wustite with CO gas were measured. CO-CO{sub 2} mixtures having various flow rates and compositions were flowed downward through a cylindrical reactor maintained at a constant temperature of 1,723 to 1,823K. A batch of pure spherical wustite particles (mean dia.: 48.5 {mu}m) was concurrently fed into the reactor at a small constant rate and reduced in a hot zone. The reduction process was found to proceed in such a manner that metallic iron particles were enclosed inside a wustite droplet. Rate analysis was made of one dimensional mass balance equations for particles and gas in a steady moving bed under an isothermal condition using the reaction rate for a single particle taking the shrinkage into consideration. Under relatively small reducing potentials, it was concluded that the major fraction of overall reaction resistance is attributable to chemical reaction. However, under higher reducing potentials, the reduction process was estimated to include some mass transfer resistances within the liquid oxide phase. From the temperature dependence of forward chemical reaction rate constants, the activation energy was evaluated to be 90.6 kJ/mol. (author)

Demonstration of physical phenomenas and scavenging activity from d-psicose and methionine maillard reaction products

Directory of Open Access Journals (Sweden)

Arum Tiyas Suminar

2017-01-01

Full Text Available Maillard reaction has been well understood as a non-enzymatic reaction between reducing sugars and amino acids to generate the Maillard reaction products (MRPs. This study is aimed to demonstrate the browning intensity, color development, spectra measurements, scavenging activity, and the correlation between browning intensity and scavenging activity of the MRPs generated from D-Psicose and Methionine (Psi-Met at 50℃. The browning intensity of MRPs was investigated based on the absorbance using spectrophotometer at 420 nm, the color development was observed using digital colorimeter to gained L*a*b* value then calculated as browning index, the spectra development was analyzed using spectrophotometer at 190 - 750 nm, and the scavenging activity was determined with ABTS method using spectrophotometer at 734 nm. The browning intensity, color development, and scavenging activity were improved along with the increase in heating process. Based on spectra analysis, MRPs from Psi-Met was initially detected at 21 h and Psi at 24 h of heating treatment, which indicating that Psi-Met have faster and better reaction than Psi during heating process. Positive non-linear and significant correlation between browning intensity and scavenging activity were assigned. This finding may provide beneficial information of D-psicose and MRPs to the next scientific research and to the food industries which applies MRPs in their products.

Studies on free radical scavenging activity in Chinese seaweeds part I. Screening results

Science.gov (United States)

Yan, Xiao-Jun; Fang, Guo-Ming; Lou, Qing-Xiang

1999-09-01

Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1, 1-diphenyl-2-picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.

Effects of frequency and a radical scavenger on ultrasonic degradation of water-soluble polymers.

Science.gov (United States)

Koda, Shinobu; Taguchi, Kimihiko; Futamura, Kazunori

2011-01-01

Ultrasonic degradation of methyl cellulose, pullulan, dextran and poly(ethylene oxide) in aqueous solutions was investigated at the frequencies of 20 and 500 kHz, where the ultrasonic power delivered into solutions was kept constant (22 W). The number average molecular mass and the polydispersity were obtained as a function of sonication time. The degradation under sonication at the 500 kHz frequency proceeded faster in comparison with the 20 kHz sonication for four polymers. The addition of a radical scavenger, t-BuOH, resulted in suppression of degradation of water-soluble polymers. The degradation rate constants were estimated from the plot of molecular weight against sonication time. The degradation rate of methyl cellulose was the largest one among the investigated polymers. The difference in the degradation rates was discussed in terms of the flexibility and the hydrodynamic radius of polymer chains in aqueous solutions. Copyright © 2010 Elsevier B.V. All rights reserved.

Iteration particle swarm optimization for contract capacities selection of time-of-use rates industrial customers

International Nuclear Information System (INIS)

Lee, Tsung-Ying; Chen, Chun-Lung

2007-01-01

This paper presents a new algorithm for solving the optimal contract capacities of a time-of-use (TOU) rates industrial customer. This algorithm is named iteration particle swarm optimization (IPSO). A new index, called iteration best is incorporated into particle swarm optimization (PSO) to improve solution quality and computation efficiency. Expanding line construction cost and contract recovery cost are considered, as well as demand contract capacity cost and penalty bill, in the selection of the optimal contract capacities. The resulting optimal contract capacity effectively reaches the minimum electricity charge of TOU rates users. A significant reduction in electricity costs is observed. The effects of expanding line construction cost and contract recovery cost on the selection of optimal contract capacities can also be estimated. The feasibility of the new algorithm is demonstrated by a numerical example, and the IPSO solution quality and computation efficiency are compared to those of other algorithms

How Predictability of Feeding Patches Affects Home Range and Foraging Habitat Selection in Avian Social Scavengers?

NARCIS (Netherlands)

Monsarrat, S.; Benhamou, S.; Sarrazin, F.; Bessa-Gomes, C.; Bouten, W.; Duriez, O.

2013-01-01

Feeding stations are commonly used to sustain conservation programs of scavengers but their impact on behaviour is still debated. They increase the temporal and spatial predictability of food resources while scavengers have supposedly evolved to search for unpredictable resources. In the Grands

Extension of a Kinetic-Theory Approach for Computing Chemical-Reaction Rates to Reactions with Charged Particles

Science.gov (United States)

Liechty, Derek S.; Lewis, Mark J.

2010-01-01

Recently introduced molecular-level chemistry models that predict equilibrium and nonequilibrium reaction rates using only kinetic theory and fundamental molecular properties (i.e., no macroscopic reaction rate information) are extended to include reactions involving charged particles and electronic energy levels. The proposed extensions include ionization reactions, exothermic associative ionization reactions, endothermic and exothermic charge exchange reactions, and other exchange reactions involving ionized species. The extensions are shown to agree favorably with the measured Arrhenius rates for near-equilibrium conditions.

Novel Water Soluble Chitosan Derivatives with 1,2,3-Triazolium and Their Free Radical-Scavenging Activity.

Science.gov (United States)

Li, Qing; Sun, Xueqi; Gu, Guodong; Guo, Zhanyong

2018-03-28

Chitosan is an abundant and renewable polysaccharide, which exhibits attractive bioactivities and natural properties. Improvement such as chemical modification of chitosan is often performed for its potential of providing high bioactivity and good water solubility. A new class of chitosan derivatives possessing 1,2,3-triazolium charged units by associating "click reaction" with efficient 1,2,3-triazole quaternization were designed and synthesized. Their free radical-scavenging activity against three free radicals was tested. The inhibitory property and water solubility of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. It is hypothesized that triazole or triazolium groups enable the synthesized chitosan to possess obviously better radical-scavenging activity. Moreover, the scavenging activity against superoxide radical of chitosan derivatives with triazolium (IC 50 radical-scavenging assay, the same pattern were observed, which should be related to the triazolium grafted at the periphery of molecular chains.

Radical scavenging compounds from the aerial parts of ...

African Journals Online (AJOL)

Results: The ethyl acetate and n-butanol fractions were the most active fractions and contained apigenin, apigenin glucuronide, luteolin, caffeic acid, methyl caffeate, rosmarinic acid and methyl rosmarinate as the radical scavenging compounds with EC50 values of 26.67 ± 0.31, 185.89 ± 1.02, 5.35 ± 0.31, 3.92 ± 0.06, ...

Genetic Variant of the Scavenger Receptor BI in Humans

NARCIS (Netherlands)

Vergeer, Menno; Korporaal, Suzanne J. A.; Franssen, Remco; Meurs, Illiana; Out, Ruud; Hovingh, G. Kees; Hoekstra, Menno; Sierts, Jeroen A.; Dallinga-Thie, Geesje M.; Motazacker, Mohammad Mahdi; Holleboom, Adriaan G.; van Berkel, Theo J. C.; Kastelein, John J. P.; van Eck, Miranda; Kuivenhoven, Jan Albert

2011-01-01

BACKGROUND In mice, the scavenger receptor class B type I (SR-BI) is essential for the delivery of high-density lipoprotein (HDL) cholesterol to the liver and steroidogenic organs. Paradoxically, elevated HDL cholesterol levels are associated with increased atherosclerosis in SR-BI-knockout mice. It

Genetic variant of the scavenger receptor BI in humans

NARCIS (Netherlands)

Vergeer, Menno; Korporaal, Suzanne J A; Franssen, Remco; Meurs, Illiana; Out, Ruud; Hovingh, G Kees; Hoekstra, Menno; Sierts, Jeroen A; Dallinga-Thie, Geesje M; Motazacker, Mohammad Mahdi; Holleboom, Adriaan G; Van Berkel, Theo J C; Kastelein, John J P; Van Eck, Miranda; Kuivenhoven, Jan Albert

2011-01-01

BACKGROUND: In mice, the scavenger receptor class B type I (SR-BI) is essential for the delivery of high-density lipoprotein (HDL) cholesterol to the liver and steroidogenic organs. Paradoxically, elevated HDL cholesterol levels are associated with increased atherosclerosis in SR-BI-knockout mice.

In vitro antioxidant and free radical scavenging activity of different parts of Tabebuia pallida growing in Bangladesh.

Science.gov (United States)

Rahman, Md Mahbubur; Islam, Md Badrul; Biswas, Mohitosh; Khurshid Alam, A H M

2015-10-30

In humans, many diseases are associated with the accumulation of free radicals. Antioxidants can scavenge free radicals and minimize their impact. Therefore, the search for naturally occurring antioxidants of plant origin is imperative. Here, we aimed to investigate the antioxidant and free radical scavenging properties of methanolic extracts from Tabebuia pallida (T. pallida) stem bark (TPSB), root bark (TPRB), leaves (TPL), and flowers (TPF). The antioxidant and free radical scavenging activity were determined by several standard methods using spectrophotomer. Total phenolic and flavonoid contents were estimated using Folin-Ciocalteu reagent and aluminum chloride colorimetric assay methods, respectively. Among the extracts, TPL showed the highest total antioxidant capacity followed by TPRB, TPF, and TPSB. Based on DPPH and hydroxyl radical scavenging activity, TPL showed strong scavenging activity (91.05 ± 1.10 and 62.00 ± 0.57) with IC50 of 9.20 ± 0.28 and 46.00 ± 2.84 μg/mL, respectively when compared with standard BHT (IC50 of 7.00 ± 0.25 μg/mL) and CA (75.00 ± 0.14 μg/mL). These results suggest that TPL had the highest radical scavenging activity among the extractives that closely resembled the standard's. In lipid peroxidation inhibition assay, TPL exhibited the most potent inhibitory activity (83.18 ± 2.12 %) with IC50 of 12.00 ± 2.12 μg/mL, which closely resembled standard CA (IC50 of 10.50 ± 0.28 μg/mL). Also, the reducing capacity on ferrous ion was in the following order: TPL > TPRB > TF > TPSB. The phenolic and flavonoid contents of TPL were higher than other extractives. A positive correlation (p value free radical (DPPH(·) and (·)OH) scavenging efficiencies and lipid peroxidation inhibition activity. Methanolic extract of T. pallida leaf is a potential source of natural antioxidants and serves as an effective free radical scavenger and/or inhibitor. Hence, T. pallida might be a good plant-based pharmaceutical product for several

An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors

Directory of Open Access Journals (Sweden)

Jian Li

2015-12-01

Full Text Available The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

Free radical scavenging activity of ethanolic extracts from herbs and spices commercialized in Brazil

Directory of Open Access Journals (Sweden)

Lilian Regina Barros Mariutti

2008-12-01

Full Text Available Ethanolic extracts from 23 different dried herbs and spices commercialized in Brazil were investigated for their free radical scavenging properties using the stable free radicals 2,2'-diphenyl-β-picrylhydrazyl (DPPH• and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS•+, and Trolox as reference (TEAC for both radicals. The kinetic curves for both radicals showed to follow the first order kinetics model and the decay rate constant (k obs was calculated. For all the samples, the two methods showed a good linear TEAC correlation, indicating that the average reactivity of the compounds present in the ethanolic extracts was similar. Sage and rosemary extracts showed the highest free radical scavenging capacities, while onion showed negligible activity and colorifico, one of the most consumed spices in Brazil, showed low ABTS•+ scavenging activity. Three distinct situations were found for the extracts concerning the DPPH• scavenging capacities: (1 extracts, like rosemary and laurel, that presented the same efficient concentrations (EC50 but differed in the TEAC values and velocities of action (k obs, (2 extracts, such as garlic and basil, that showed similar EC50 and TEAC values, but different k obs values and (3 extracts that reacted at the same velocities but completely differed in the free radical scavenging capacities, like black pepper, savory, nutmeg, rosemary and sage. Similar considerations could be done for the ABTS•+ results. For the first time the ABTS•+ scavenging activity for allspice, basil, cardamom, chives, colorifico, cumin, dill, laurel, marjoram, parsley and tarragon was reported.Extratos etanólicos de 23 ervas e condimentos desidratados comercializados no Brasil foram analisados quanto as suas propriedades antioxidantes utilizando os radicais 2,2'-difenil-β-picrilhidrazil (DPPH• e ácido 2,2'-azino-bis(3-etilbenzotiazolina-6-sulfônico (ABTS•+, Trolox foi usado como referência para ambos radicais

Evaluation of antioxidant, free radical scavenging and antimicrobial, activity of Quercus incana Roxb.

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Rizwana eSarwar

2015-11-01

Full Text Available Considering the indigenous utilization of Quercus incana Roxb., the present study deals with the investigation of antioxidant, free radical scavenging activity, total phenolic content and antimicrobial activity of Quercus incana Roxb. In vitro antioxidant activity of the plant fractions were determined by DPPH and NO scavenging method. Total phenolic contents were determined by gallic acid equivalent (GAE and antimicrobial activities were determined by agar well diffusion method. It was observed that Quercus incana Roxb. showed significant antibacterial activity against Gram-positive and Gram-negative bacteria. n-Butanol fraction showed maximum activity against Micrococcus leuteus with 19 mm zone of inhibition. n-Butanol fraction of Quercus incana Roxb. showed immense antifungal activity against Aspergillus niger (32 mm ± 0.55 and Aspergillus flavus (28 mm ± 0.45. Similarly n-butanol fraction showed relatively good antioxidant activity with IC50 value of 55.4 ± 0.21μg/mL. The NO scavenging activity of ethyl acetate fraction (IC50 = 23.21 ± 0.31 μg/mL was fairly good compared to other fractions. The current study of Quercus incana Roxb. suggests the presences of synergetic action of some biological active compounds that may be present in the leaves of medicinal plant. Further studies are needed to better characterize the important active constituents responsible for the antimicrobial, antioxidant and free radical scavenging activity.

Lipid organics in background aerosols, cloudwater, and snow and implication for organic scavenging

International Nuclear Information System (INIS)

Groellert, C.

1998-01-01

During three years free tropospheric snow, aerosol, and cloudwater samples were collected at Mount Sonnblick, Austria, at an elevation of 3106 m a.s.l. The samples were analyzed for their lipid organic trace components using extraction with n-hexane as sample pretreatment and gas chromatography-mass spectrometry-flame ionization detection for identification and quantification of the substances. The main components identified in all the samples were the phthalic acid esters which are of anthropogenic origin. Of further interest were aliphatic alcohols (not detected in aerosols) and phenols. They are of biogenic origin. The concentrations were found to be higher in spring than in the fall season. To compare the concentrations of aerosol, cloudwater and snow samples scavenging ratios (aerosol to snow), scavenging efficiencies (aerosol to cloud) and cloud to snow ratios were calculated for the first time for organic compounds. Scavenging ratios were 10 to 100 times lower, scavenging efficiencies 2 to 10 times lower than sulfate. This can result from the poor watersolubility of the compounds or from gas phase sorptions on the filter surface (overestimation of aerosol concentrations). The cloud to snow ratios were generally higher than for sulfate. However, a few components exhibited very low cloud to snow ratios which might be due to additional sources in snow for these substances (alcohols). (author)

Sedimentary and mineral dust sources of dissolved iron to the world ocean

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J. K. Moore

2008-05-01

Full Text Available Analysis of a global compilation of dissolved-iron observations provides insights into the processes controlling iron distributions and some constraints for ocean biogeochemical models. The distribution of dissolved iron appears consistent with the conceptual model developed for Th isotopes, whereby particle scavenging is a two-step process of scavenging mainly by colloidal and small particulates, followed by aggregation and removal on larger sinking particles. Much of the dissolved iron (<0.4 μm is present as small colloids (>~0.02 μm and, thus, is subject to aggregation and scavenging removal. This implies distinct scavenging regimes for dissolved iron consistent with the observations: 1 a high scavenging regime – where dissolved-iron concentrations exceed the concentrations of strongly binding organic ligands; and 2 a moderate scavenging regime – where dissolved iron is bound to both colloidal and soluble ligands. Within the moderate scavenging regime, biological uptake and particle scavenging decrease surface iron concentrations to low levels (<0.2 nM over a wide range of low to moderate iron input levels. Removal rates are also highly nonlinear in areas with higher iron inputs. Thus, observed surface-iron concentrations exhibit a bi-modal distribution and are a poor proxy for iron input rates. Our results suggest that there is substantial removal of dissolved iron from subsurface waters (where iron concentrations are often well below 0.6 nM, most likely due to aggregation and removal on sinking particles of Fe bound to organic colloids.

We use the observational database to improve simulation of the iron cycle within a global-scale, Biogeochemical Elemental Cycling (BEC ocean model. Modifications to the model include: 1 an improved particle scavenging parameterization, based on the sinking mass flux of particulate organic material, biogenic silica, calcium carbonate, and mineral dust particles; 2 desorption of dissolved iron

Highly functionalized piperidines: Free radical scavenging, anticancer activity, DNA interaction and correlation with biological activity

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Suvankar Das

2018-01-01

Full Text Available Twenty-five piperidines were studied as potential radical scavengers and antitumor agents. Quantitative interaction of compounds with ctDNA using spectroscopic techniques was also evaluated. Our results demonstrate that the evaluated piperidines possesses different abilities to scavenge the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH and the anion radical superoxide (·O2−. The piperidine 19 was the most potent radical DPPH scavenger, while the most effective to ·O2− scavenger was piperidine 10. In general, U251, MCF7, NCI/ADR-RES, NCI-H460 and HT29 cells were least sensitive to the tested compounds and all compounds were considerably more toxic to the studied cancer cell lines than to the normal cell line HaCaT. The binding mode of the compounds and ctDNA was preferably via intercalation. In addition, these results were confirmed based on theoretical studies. Finally, a linear and exponential correlation between interaction constant (Kb and GI50 for several human cancer cell was observed.

Exposure assessment and heart rate variability monitoring in workers handling titanium dioxide particles: a pilot study

Energy Technology Data Exchange (ETDEWEB)

Ichihara, Sahoko [Mie University, Graduate School of Regional Innovation Studies (Japan); Li, Weihua [WHO Collaborating Centre for Research in Human Reproduction, Shanghai Institute of Planned Parenthood Research (China); Omura, Seiichi [Tokyo Institute of Technology (Japan); Fujitani, Yuji [National Institute for Environmental Studies (Japan); Liu, Ying; Wang, Qiangyi [WHO Collaborating Centre for Research in Human Reproduction, Shanghai Institute of Planned Parenthood Research (China); Hiraku, Yusuke [Mie University Graduate School of Medicine, Department of Environmental and Molecular Medicine (Japan); Hisanaga, Naomi [Aichi Gakusen University, Faculty of Human Science and Design (Japan); Wakai, Kenji [Nagoya University Graduate School of Medicine, Department of Preventive Medicine (Japan); Ding, Xuncheng [WHO Collaborating Centre for Research in Human Reproduction, Shanghai Institute of Planned Parenthood Research (China); Kobayashi, Takahiro, E-mail: takakoba@airies.or.jp [Association for International Research Initiatives for Environmental Studies (Japan); Ichihara, Gaku, E-mail: gak@rs.tus.ac.jp [Tokyo University of Science, Department of Occupational and Environmental Health, Faculty of Pharmaceutical Sciences (Japan)

2016-03-15

Titanium dioxide (TiO{sub 2}) particles are used for surface coating and in a variety of products such as inks, fibers, food, and cosmetics. The present study investigated possible respiratory and cardiovascular effects of TiO{sub 2} particles in workers exposed to this particle at high concentration in a factory in China. The diameter of particles collected on filters was measured by scanning electron microscopy. Real-time size-dependent particle number concentration was monitored in the nostrils of four workers using condensation particle counter and optical particle counter. Electrocardiogram was recorded using Holter monitors for the same four workers to record heart rate variability. Sixteen workers underwent assessment of the respiratory and cardiovascular systems. Mass-based individual exposure levels were also measured with personal cascade impactors. The primary particle diameter ranged from 46 to 562 nm. Analysis of covariance of the pooled data of the four workers showed that number of particles with a diameter <300 nm was associated positively with total number of N–N and negatively with total number of increase or decrease in successive RR intervals greater than 50 ms (RR50+/−) or percentage of RR 50+/− that were parameters of parasympathetic function. The total mass concentration was 9.58–30.8 mg/m{sup 3} during work, but significantly less before work (0.36 mg/m{sup 3}). The clear abnormality in respiratory function was not observed in sixteen workers who had worked for 10 months to 13 years in the factory. The study showed that exposure to particles with a diameter <300 nm might affect HRV in workers handling TiO{sub 2} particles. The results highlight the need to investigate the possible impact of exposure to nano-scaled particles on the autonomic nervous system.

Scavenger Receptors and Resistance to Inhaled Allergens

Science.gov (United States)

2010-02-01

throughput manner which will enable future studies. We plan to continue two especially interesting aspects of these studies. First, the epigenetic control...directs mod- ified proteins to antigen presentation. Eur. J. Immunol. 29: 512–521. 30. Granucci, F., F. Petralia, M. Urbano , S. Citterio, F. Di Tota, L...11 Suppl:S32-6. 50. Granucci F, Petralia F, Urbano M, Citterio S, Di Tota F, Santambrogio L, Ricciardi-Castagnoli P: The scavenger receptor MARCO

Comparative investigation of the free radical scavenging potential and anticancer property of Diospyros blancoi (Ebenaceae

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Muhammad Ali Khan

2016-05-01

Conclusions: Our results indicate that Diospyros blancoi stem bark had the significant highest antioxidant and free radical scavenging properties as well as moderate anticancer activity. Hence, we assume that the anticancer activity of this plant can be, at least in part, attributed to its content in phenolic compounds as well as its significant free radical scavenging properties.

Clustered DNA damage on subcellular level: effect of scavengers

Czech Academy of Sciences Publication Activity Database

Pachnerová Brabcová, Kateřina; Sihver, L.; Yasuda, N.; Matuo, Y.; Štěpán, Václav; Davídková, Marie

2014-01-01

Roč. 53, č. 4 (2014), s. 705-712 ISSN 0301-634X R&D Projects: GA MŠk LD12008 Institutional support: RVO:61389005 Keywords : clustered damage * indirect effects * haevy ion * plasmid in liquid water * scavenger Subject RIV: BO - Biophysics Impact factor: 1.528, year: 2014

Precritical increase of particle collision rates

International Nuclear Information System (INIS)

Muenchow, L.

1990-01-01

In quantum kinetics the collision integral follows from the imaginary part of the mass operator. Using this connection it is shown that the coupling of single particle motion to precritical density fluctuations causes a strong increase of the collision integral near the point of phase instability. 13 refs

Antioxidant and Free Radical Scavenging Capacity of Seed and Shell Essential Oils Extracted from Abrus precatorius (L

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Sunday O. Okoh

2014-04-01

Full Text Available Essential oils from plants have been proven safe as natural antioxidants, and few are already marketed as digestive enhancers as well as in prevention of several degenerative diseases. This study evaluated the antioxidant capacity of seed and shell essential oils of Abrus precatorius (L, a herb used for ethno-medicinal practices in Nigeria. The essential oils were obtained by hydro-distillation. The ability of the oils to act as hydrogen/electrons donor or scavenger of radicals were determined by in-vitro antioxidant assays using 2,2-diphenyl-2-picryl-hydrazyl free radical (DPPH. scavenging; 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS radical scavenging; lipid peroxide and nitric oxide radicals scavenging assays. The IC50 of the seed and shell oils (2.10 mg/mL and 1.20 mg/mL respectively showed that antioxidant activity is higher than that for the standard drugs (3.20 mg/mL and 3.40 mg/mL for the nitric oxide scavenging assay. The lipid peroxidation radical activity of the oils were similar to vitamin C, weak DPPH and ABTS radical scavenging activities were discovered in comparison to vitamin C and rutin. Generally, in the four antioxidant assays, a significant correlation existed between concentrations of the oils and percentage inhibition of free radicals and lipid peroxidation. The composition of A. precatorius essential oils reported earlier may account for their antioxidant capacity.

Free Radical Scavenging Activity of Scoparia dulcis Extract.

Science.gov (United States)

Babincová, M.; Sourivong, P.

2001-01-01

We studied the scavenging capabilities of an extract of Scoparia dulcis (a cosmopolitan weed widespread in Laos and Vietnam) for 1-diphenyl-2-picrylhydrazyl and measured hemoglobin-catalyzed linoleic acid peroxidation with an oxygen electrode. Our results demonstrated strong antioxidant activity corresponding to mitigation of the generation of hydroxyl radicals, a possible rationale for the observed therapeutic effects of this weed.

Evaluation of Antioxidant and Free Radical Scavenging Abilities of ...

African Journals Online (AJOL)

Objective: This study was aimed at determining the antioxidants and free radical scavenging abilities of some packaged fruit juices (PFJ) widely used as source of fluids in Nigeria. Materials and methods: Packaged fruit juice samples produced by The Coca cola Company and Chi company namely: Apple(AP), blackcurrant, ...

Antioxidant and free radical scavenging activities of plant extracts ...

African Journals Online (AJOL)

Twenty-two species of medicinal plants collected in the Mexican state of Morelos were selected to evaluate their free radical scavenging and antioxidant activities. The extracts from the aerial parts of the plants were obtained using hexane, acetone and methanol (66 extracts). The initial qualitative screening of antioxidants ...

Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating

DEFF Research Database (Denmark)

Koivisto, Antti J.; Jensen, Alexander C. Ø.; Kling, Kirsten I.

2017-01-01

Here, we studied the particle release rate during Electrostatic spray deposition of anatase-(TiO2)-based photoactive coating onto tiles and wallpaper using a commercially available electrostatic spray device. Spraying was performed in a 20.3m3 test chamber while measuring concentrations of 5.6nm ...

Evaluation of precipitation scavenging rates of background aerosol

International Nuclear Information System (INIS)

Hicks, B.B.

1976-01-01

An attempt was made to obtain information on the rates at which raining clouds cleanse the atmosphere, with natural radioactivity used as a tracer of naturally-occurring aerosols. In the atmosphere, the air concentrations of the radioactive Rn daughters would be expected to approach equilibrium with increasing height. In a theoretical study, Jacobi et al. (1959) showed that the short-lived first daughter of radon ( 218 Po, 3 min half life) is in equilibrium with radon above about 20 m. Gamma-ray spectrometry was used to measure the isotopes of interest in successive samples of precipitation collected at ground level during nine rainfall occasions. Gamma-ray spectra of freshly collected rainfall were typically dominated by the photopeaks at 0.352 MeV ( 214 Pb) and 0.609 MeV( 214 Bi). After these isotopes have decayed, the 212 Pb photopeak at 0.323 MeV becomes apparent ( 212 Pb is a thoron daughter). In the present work this feature was employed to allow accurate measurement of each isotope

Comparison of the effectiveness and safety between lymphocytes scavenger and IL-2 receptor blocking agent induction in living kidney transplantation

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Ning-bo QIN

2013-03-01

Full Text Available Objective 　To compare the safety of two antibody inductors, namely lymphocytes scavenger and IL-2 receptor blocking agent, in living kidney transplantation. Methods 　The data of 191 patients, who received living kidney transplant in our hospital from Feb. 2007 to Jul. 2012, were retrospectively analyzed, and grouped according to the inductors they received as: a lymphocytes scavenger group (n=56, with rabbit antithymocyte immunoglobulin (rATG, 4 cases and porcine antihuman T-lymphocyte immunoglobulin (pATG, 52 cases served as the inductor; b IL -2 receptor blocking agent group (n=54, with basiliximab (40 cases and daclizumab (14 cases served as the inductor; and c control group (n=81. The incidence of rejection and infection, and the survival rate of patient/allograft within one year were then compared among the three groups. Results 　Within one year after the transplantation, the incidence of acute rejection in lymphocytes scavenger group, IL-2 receptor blocking agent group and control group was 12.5%, 11.1% and 28.4%, respectively. There was a significant difference between the two inductor groups and control group (P=0.003, but no significant difference was found between the two inductor groups (P>0.05. The incidence of delayed graft function (DGF in the three groups was 8.9%, 7.4% and 13.6%, respectively, with no statistical significance (P>0.05. Also there was no significant difference among the three groups in the incidence of infection and the survival rate of patient/allograft within one year after transplantation (P>0.05. Conclusion 　Both inductors may significantly reduce the incidence of acute rejection within one year without increasing the incidence of infection and other adverse events, nor affect the postoperative patient/graft survival, so they are both safe and effective.

Free radical scavenging and COX-2 inhibition by simple colon metabolites of polyphenols: A theoretical approach.

Science.gov (United States)

Amić, Ana; Marković, Zoran; Marković, Jasmina M Dimitrić; Jeremić, Svetlana; Lučić, Bono; Amić, Dragan

2016-12-01

Free radical scavenging and inhibitory potency against cyclooxygenase-2 (COX-2) by two abundant colon metabolites of polyphenols, i.e., 3-hydroxyphenylacetic acid (3-HPAA) and 4-hydroxyphenylpropionic acid (4-HPPA) were theoretically studied. Different free radical scavenging mechanisms are investigated in water and pentyl ethanoate as a solvent. By considering electronic properties of scavenged free radicals, hydrogen atom transfer (HAT) and sequential proton loss electron transfer (SPLET) mechanisms are found to be thermodynamically probable and competitive processes in both media. The Gibbs free energy change for reaction of inactivation of free radicals indicates 3-HPAA and 4-HPPA as potent scavengers. Their reactivity toward free radicals was predicted to decrease as follows: hydroxyl>alkoxyls>phenoxyl≈peroxyls>superoxide. Shown free radical scavenging potency of 3-HPAA and 4-HPPA along with their high μM concentration produced by microbial colon degradation of polyphenols could enable at least in situ inactivation of free radicals. Docking analysis with structural forms of 3-HPAA and 4-HPPA indicates dianionic ligands as potent inhibitors of COX-2, an inducible enzyme involved in colon carcinogenesis. Obtained results suggest that suppressing levels of free radicals and COX-2 could be achieved by 3-HPAA and 4-HPPA indicating that these compounds may contribute to reduced risk of colon cancer development. Copyright © 2016 Elsevier Ltd. All rights reserved.

Is the scavenger receptor MARCO a new immune checkpoint?

Science.gov (United States)

Arredouani, Mohamed S

2014-11-01

Whereas macrophages use the scavenger receptor MARCO primarily in antimicrobial immunity by interacting with both exogenous and endogenous environments, in dendritic cells (DCs) MARCO is believed to pleiotropically link innate to adaptive immunity. MARCO exerts a significant modulatory effect on TLR-induced DC activation, thus offering novel avenues in cancer immunotherapy.

Scavenger receptor AI/II truncation, lung function and COPD

DEFF Research Database (Denmark)

Thomsen, M; Nordestgaard, B G; Tybjaerg-Hansen, A

2011-01-01

The scavenger receptor A-I/II (SRA-I/II) on alveolar macrophages is involved in recognition and clearance of modified lipids and inhaled particulates. A rare variant of the SRA-I/II gene, Arg293X, truncates the distal collagen-like domain, which is essential for ligand recognition. We tested whet...

Protective role of OH scavengers and DNA/chromatin organization in the induction of DNA breaks: mechanistic models and Monte Carlo simulations

International Nuclear Information System (INIS)

Ballarini, F.; Rossetti, M.; Scannicchio, D.; Jacob, P.; Molinelli, S.; Ottolenghi, A.; Volata, A.

2003-01-01

Radiation-induced DNA damage can be modulated by various factors, including the environment scavenging capacity (SC) and the DNA organization within the cell nucleus (chromatin compactness, DNA-binding proteins etc.). In this context the induction of ssb and dsb by photons and light ions of different energies impinging on different DNA structures (e.g. linear DNA, SV40 'minichromosomes' and cellular DNA) at different OH-radical SC values was modelled with the Monte Carlo PARTRAC code. Presently PARTRAC can transport electrons, photons, protons and alpha particles in liquid water with an 'event-by-event' approach, and can simulate the DNA content of mammalian cells with an 'atom-by-atom' description, from nucleotide pairs to chromatin fibre loops and chromosome territories. Energy depositions in the sugar-phosphate were considered as potential (direct) ssb. The production, diffusion and reaction of chemical species were explicitly simulated; reactions of OH radicals with the sugar-phosphate were assumed to lead to 'indirect' ssb with probability 65%. Two ssb on opposite strands within 10 bp were considered as a dsb. Yields of ssb and dsb/Gy/Dalton were calculated for different DNA structures as a function of the OH mean life time. By Zyuzikov, N.; Michael, B.D. (Gray Cancer Institute, (GB)); Wu, L. (Ch Zyuzdirect damage yields. In general, also depending on radiation quality, linear DNA was found to be more susceptible to strand breakage than SV40 minichromosomes, which in turn showed higher damage yields with respect to cellular DNA. The very good agreement found with available experimental data provided a validation of the model and allowed us to quantify separately the protective effect of OH scavengers and DNA/chromatin organization. Comparisons with data on nucleoids (DNA unfolded and depleted of histones) suggested that the experimental procedures used to obtain such targets might lower the environment SC, due to the loss of cellular scavenging compounds

Hydroxyl radical-scavenging property of secoisolariciresinol diglucoside (SDG) isolated from flax-seed.

Science.gov (United States)

Prasad, K

1997-03-01

Recently there has been a moderate resurgence in the use of flax-seed in a variety of ways including bread. The scientific basis of its use is very limited. There is some claim for beneficial effects in cancer and lupus nephritis. These claims could be due to its ability to scavenge oxygen radicals. However, its antioxidant activity is not known. Recently a method has been developed to isolate secoisolariciresinol diglucoside (SDG) from defatted flax-seed in large quantity (patent pending). We investigated the ability of SDG to scavenge .OH using high pressure liquid chromatography (HPLC) method. .OH was generated by photolysis of H2O2 (1.25-10.0 mumoles/ml) with ultraviolet light and was trapped with salicylic acid which is hydroxylated to produce .OH-adduct products 2,3-dihydroxybenzoic acid (DHBA) and 2,5-DHBA. H2O2 produced a concentration-dependent .OH as estimated by 2,3-DHBA and 2,5-DHBA. A standard curve was constructed for known concentrations of 2,3-DHBA and 2,5-DHBA against corresponding area under the peaks which then was used for measurement of 2,3-DHBA and 2,5-DHBA generated by UV irradiation of H2O2 in the presence of salicylic acid. SDG in the concentration range of 25, 50, 100, 250, 500, 750, 1000 and 2000 micrograms/ml (36.4, 72.8, 145.6, 364.0, 728.0, 1092.0, 1456.0 and 2912.0 microM respectively) produced a concentration-dependent decrease in the formation of 2,3-DHBA and 2,5-DHBA, the inhibition being 4 and 4.65% respectively with 25 micrograms/ml (36.4 microM) and 82 and 74% respectively with 2000 micrograms/ml (2912.0 microM). The decrease in .OH-adduct products was due to scavenging of .OH and not by scavenging of formed 2,3-DHBA and 2,5-DHBA. SDG prevented the lipid peroxidation of liver homogenate in a concentration-dependent manner in the concentration range from 319.3-2554.4 microM. These results suggest that SDG scavenges .OH and therefore has an antioxidant activity.

The electrochemical reduction rate of colloidal particles of silver halides as a function of the electrolyte composition

International Nuclear Information System (INIS)

Selivanov, V.N.

1997-01-01

Influence of silver halide colloid particles concentration (AgI), electrolyte composition and signs of the electrode and colloids charges on their reduction threshold current densities has been studied. It has been discovered that reduction threshold current densities of positively charged colloid particles exceed by a factor of 3-4 the threshold densities of silver ions diffusion current. It is shown that the threshold density of colloids reduction current is limited by the rates of their electrophoretic transfer and diffusion

The efficacy of edaravone (radicut), a free radical scavenger, for cardiovascular disease.

Science.gov (United States)

Kikuchi, Kiyoshi; Tancharoen, Salunya; Takeshige, Nobuyuki; Yoshitomi, Munetake; Morioka, Motohiro; Murai, Yoshinaka; Tanaka, Eiichiro

2013-07-04

Edaravone was originally developed as a potent free radical scavenger, and has been widely used to treat acute ischemic stroke in Japan since 2001. Free radicals play an important role in the pathogenesis of a variety of diseases, such as cardiovascular diseases and stroke. Therefore, free radicals may be targets for therapeutic intervention in these diseases. Edaravone shows protective effects on ischemic insults and inflammation in the heart, vessel, and brain in experimental studies. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic, and anti-cytokine effects in cardiovascular diseases and stroke. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, heart failure, diabetes, or hypertension, because these diseases result from oxidative stress and/or cytokine-induced apoptosis. This review evaluates the potential of edaravone for treatment of cardiovascular disease, and covers clinical and experimental studies conducted between 1984 and 2013. We propose that edaravone, which scavenges free radicals, may offer a novel option for treatment of cardiovascular diseases. However, additional clinical studies are necessary to verify the efficacy of edaravone.

Microglial Scavenger Receptors and Their Roles in the Pathogenesis of Alzheimer's Disease

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Kim Wilkinson

2012-01-01

Full Text Available Alzheimer’s disease (AD is increasing in prevalence with the aging population. Deposition of amyloid-β (Aβ in the brain of AD patients is a hallmark of the disease and is associated with increased microglial numbers and activation state. The interaction of microglia with Aβ appears to play a dichotomous role in AD pathogenesis. On one hand, microglia can phagocytose and clear Aβ, but binding of microglia to Aβ also increases their ability to produce inflammatory cytokines, chemokines, and neurotoxic reactive oxygen species (ROS. Scavenger receptors, a group of evolutionally conserved proteins expressed on the surface of microglia act as receptors for Aβ. Of particular interest are SCARA-1 (scavenger receptor A-1, CD36, and RAGE (receptor for advanced glycation end products. SCARA-1 appears to be involved in the clearance of Aβ, while CD36 and RAGE are involved in activation of microglia by Aβ. In this review, we discuss the roles of various scavenger receptors in the interaction of microglia with Aβ and propose that these receptors play complementary, nonredundant functions in the development of AD pathology. We also discuss potential therapeutic applications for these receptors in AD.

Free radical scavenging activity of coenzyme Q measured by a chemiluminescent assay

International Nuclear Information System (INIS)

Battino, Maurizio; Ferri, Elida; Girotti, Stefano; Lenaz, Giorgio

1991-01-01

Involvement of coenzyme Q (CoQ) in anti-oxydant activities, in addition to its major redox role, has frequently been suggested in recent years. In order to elucidate if CoQ could really be engaged in scavenging free radicals produced endogenously in a biological system, an experimental system was developed in which beef heart mitochondria in the presence of a saturating NADH concentration and of rotenone produce free radicals. The presence of oxygen-reactive forms was easily detected by a luminol-dependent chemiluminescence process. The chemi-luminescence assay showed that short-chain CoQ homologues can act as pro-oxidants, enhancing free radical effects, while exogenous coenzyme Q 10 could scavenge free radicals, especially at very low concentration. In this system, exogenous CoQ 10 was more effective than α-tocopherol at the same concentration in scavenging free radicals. The molecular mechanism that leads to this activity is still unclear, but these results are of biochemical importance because they indicate that CoQ may act as an anti=oxidant in situations mimicking physiopathological conditions. This direct chemiluminescent method is promising for studies of biochemical processes which involve active oxygen species. (author). 24 refs.; 4 figs

Seasonal changes of 234Th scavenging in surface water across the western Black Sea: an implication of the cyclonic circulation patterns

International Nuclear Information System (INIS)

Gulin, S.B.

2000-01-01

Two seasonal surveys of 234 Th activity in surface water were carried out in November 1998 and June 1999 along the transect Sevastopol (Ukraine) - Istanbul (Turkey) crossing the entire western Black Sea between the SW Crimean Peninsula and the Bosphorus Strait entry. A steady-state model of 234 Th/ 238 U equilibrium in seawater was used to calculate the net removal flux of 234 Th by particles. The results obtained from central stations of the transect were in good agreement with those observed seasonally in 1992-1994 within the western cyclonic gyre of the abyssal Black Sea, showing that in June 1999 the sampling was conducted during the peak summer bloom of coccolithophorids, while in November 1998 the samples were collected three weeks after the autumn phytoplankton bloom. The 234 Th scavenging rates and the total mass fluxes were thus much higher in the June sampling period than in November at the stations located in the western cyclonic gyre and at the northern margin of the abyssal Black Sea basin. In contrast, the considerable seasonal differences were not found at the location near the Bosphorus Strait entry, suggesting a larger lateral input of particulate matter transported to this area from the western and northwestern shelf due to cyclonic circulation of the surface waters

Disintegration rate and properties of active pharmaceutical ingredient particles as determined from the dissolution time profile of a pharmaceutical formulation: an inverse problem.

Science.gov (United States)

Horkovics-Kovats, Stefan

2014-02-01

Dissolution profile of a finished dosage form (FDF) contains hidden information regarding the disintegration of the form and the particle properties of the active pharmaceutical ingredient. Here, an extraction of this information from the dissolution profile without limitation to sink conditions is provided. In the article, mathematical relationships between the continuously measured dissolution profile of an FDF containing uniform or heterogeneous particles and its disintegration rate are developed. Further, the determinability of the disintegration kinetics and particle properties released from an FDF using the derived recurrent procedure was analyzed. On the basis of the theoretical data sets, it was demonstrated that the introduced analysis of dissolution profiles correctly identifies the disintegration rate of FDF containing multiple particle types. Furthermore, for known disintegration rates, the intrinsic lifetime of particles (time needed for total particle dissolution in infinite volume) released from the FDF and their relative amount can be determined. The extractable information from FDF dissolution time profiles can be utilized in designing of the formulation process, resulting in improved understanding of FDF properties, contributing thus to the implementation of quality by design in the FDF development. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

Scavenger receptors in human airway epithelial cells: role in response to double-stranded RNA.

Directory of Open Access Journals (Sweden)

Audrey Dieudonné

Full Text Available Scavenger receptors and Toll-like receptors (TLRs cooperate in response to danger signals to adjust the host immune response. The TLR3 agonist double stranded (dsRNA is an efficient activator of innate signalling in bronchial epithelial cells. In this study, we aimed at defining the role played by scavenger receptors expressed by bronchial epithelial cells in the control of the innate response to dsRNA both in vitro and in vivo. Expression of several scavenger receptor involved in pathogen recognition was first evaluated in human bronchial epithelial cells in steady-state and inflammatory conditions. Their implication in the uptake of dsRNA and the subsequent cell activation was evaluated in vitro by competition with ligand of scavenger receptors including maleylated ovalbumin and by RNA silencing. The capacity of maleylated ovalbumin to modulate lung inflammation induced by dsRNA was also investigated in mice. Exposure to tumor necrosis factor-α increased expression of the scavenger receptors LOX-1 and CXCL16 and the capacity to internalize maleylated ovalbumin, whereas activation by TLR ligands did not. In contrast, the expression of SR-B1 was not modulated in these conditions. Interestingly, supplementation with maleylated ovalbumin limited dsRNA uptake and inhibited subsequent activation of bronchial epithelial cells. RNA silencing of LOX-1 and SR-B1 strongly blocked the dsRNA-induced cytokine production. Finally, administration of maleylated ovalbumin in mice inhibited the dsRNA-induced infiltration and activation of inflammatory cells in bronchoalveolar spaces and lung draining lymph nodes. Together, our data characterize the function of SR-B1 and LOX-1 in bronchial epithelial cells and their implication in dsRNA-induced responses, a finding that might be relevant during respiratory viral infections.

Effects of cooling rate on particle rearrangement statistics: Rapidly cooled glasses are more ductile and less reversible.

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Fan, Meng; Wang, Minglei; Zhang, Kai; Liu, Yanhui; Schroers, Jan; Shattuck, Mark D; O'Hern, Corey S

2017-02-01

Amorphous solids, such as metallic, polymeric, and colloidal glasses, display complex spatiotemporal response to applied deformations. In contrast to crystalline solids, during loading, amorphous solids exhibit a smooth crossover from elastic response to plastic flow. In this study, we investigate the mechanical response of binary Lennard-Jones glasses to athermal, quasistatic pure shear as a function of the cooling rate used to prepare them. We find several key results concerning the connection between strain-induced particle rearrangements and mechanical response. We show that the energy loss per strain dU_{loss}/dγ caused by particle rearrangements for more rapidly cooled glasses is larger than that for slowly cooled glasses. We also find that the cumulative energy loss U_{loss} can be used to predict the ductility of glasses even in the putative linear regime of stress versus strain. U_{loss} increases (and the ratio of shear to bulk moduli decreases) with increasing cooling rate, indicating enhanced ductility. In addition, we characterized the degree of reversibility of particle motion during a single shear cycle. We find that irreversible particle motion occurs even in the linear regime of stress versus strain. However, slowly cooled glasses, which undergo smaller rearrangements, are more reversible during a single shear cycle than rapidly cooled glasses. Thus, we show that more ductile glasses are also less reversible.

Hydroxyl radical scavenging activity of peptide from sea cucumber ...

African Journals Online (AJOL)

enzyme complex, sea cucumber protein hydrolysis was carried out to obtain hydrolysates that have hydroxyl-radical-scavenging activity (HRSA). The hydrolytic process was monitored by HRSA and conditions for this process were optimized as follows: pH 6.5, temperature 35°C, 12 mg enzyme complex in a reaction solution ...

The scavenging of volatile anesthetic agents in the cardiovascular intensive care unit environment: a technical report.

Science.gov (United States)

Pickworth, Thomas; Jerath, Angela; DeVine, Rita; Kherani, Nazmin; Wąsowicz, Marcin

2013-01-01

The use of volatile-based sedation within critical care environments has been limited by difficulties of drug administration and safety concerns over environment pollution and staff exposure in an intensive care unit (ICU) with no scavenging. The aim of this study was to develop a simple scavenging system to be used with the Anesthesia Conserving Device (AnaConDa(®)) and to determine whether or not ambient concentrations of residual anesthetic are within current acceptable limits. The scavenging system consists of two Deltasorb(®) canisters attached to the ICU ventilator in series. AnaConDa is a miniature vaporizer designed to provide volatile-based sedation within an ICU. The first ten patients recruited into a larger randomized trial assessing outcomes after elective coronary graft bypass surgery were sedated within the cardiac ICU using either isoflurane or sevoflurane. Sedation was guided by the Sedation Agitation Scale, resulting in an end-tidal minimum anesthetic concentration of volatile agent ranging from 0.1-0.3. At one hour post ICU admission, infrared photometric analysis was used to assess environmental contamination at four points along the ventilator circuit and scavenging system and around the patient's head. All measurements taken within the patient's room were below 1 part per million, which satisfies criteria for occupational exposure. This study shows that volatile agents can be administered safely within critical care settings using a simple scavenging system. Our scavenging system used in conjunction with the AnaConDa device reduced the concentration of environmental contamination to a level that is acceptable to Canadian standards and standards in most Western countries and thus conforms to international safety standards. The related clinical trial was registered at www.clinicaltrials.gov (NCT01151254).

Novel Water Soluble Chitosan Derivatives with 1,2,3-Triazolium and Their Free Radical-Scavenging Activity

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Qing Li

2018-03-01

Full Text Available Chitosan is an abundant and renewable polysaccharide, which exhibits attractive bioactivities and natural properties. Improvement such as chemical modification of chitosan is often performed for its potential of providing high bioactivity and good water solubility. A new class of chitosan derivatives possessing 1,2,3-triazolium charged units by associating “click reaction” with efficient 1,2,3-triazole quaternization were designed and synthesized. Their free radical-scavenging activity against three free radicals was tested. The inhibitory property and water solubility of the synthesized chitosan derivatives exhibited a remarkable improvement over chitosan. It is hypothesized that triazole or triazolium groups enable the synthesized chitosan to possess obviously better radical-scavenging activity. Moreover, the scavenging activity against superoxide radical of chitosan derivatives with triazolium (IC50 < 0.01 mg mL−1 was more efficient than that of derivatives with triazole and Vitamin C. In the 1,1-diphenyl-2-picrylhydrazyl (DPPH and hydroxyl radical-scavenging assay, the same pattern were observed, which should be related to the triazolium grafted at the periphery of molecular chains.

African vultures don't follow migratory herds: scavenger habitat use is not mediated by prey abundance.

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Corinne J Kendall

Full Text Available The ongoing global decline in vulture populations raises major conservation concerns, but little is known about the factors that mediate scavenger habitat use, in particular the importance of abundance of live prey versus prey mortality. We test this using data from the Serengeti-Mara ecosystem in East Africa. The two hypotheses that prey abundance or prey mortality are the main drivers of vulture habitat use provide alternative predictions. If vultures select areas based only on prey abundance, we expect tracked vultures to remain close to herds of migratory wildebeest regardless of season. However, if vultures select areas where mortality rates are greatest then we expect vultures to select the driest regions, where animals are more likely to die of starvation, and to be attracted to migratory wildebeest only during the dry season when wildebeest mortality is greatest. We used data from GSM-GPS transmitters to assess the relationship between three vulture species and migratory wildebeest in the Mara-Serengeti ecosystem. Results indicate that vultures preferentially cluster around migratory herds only during the dry season, when herds experience their highest mortality. Additionally during the wet season, Ruppell's and Lappet-faced vultures select relatively dry areas, based on Normalized Difference Vegetation Index, whereas White-backed vultures preferred wetter areas during the wet season. Differences in habitat use among species may mediate coexistence in this scavenger guild. In general, our results suggest that prey abundance is not the primary driver of avian scavenger habitat use. The apparent reliance of vultures on non-migratory ungulates during the wet season has important conservation implications for vultures in light of on-going declines in non-migratory ungulate species and use of poisons in unprotected areas.

Inhibition of radiation-induced DNA strand breaks by hoechst 33258: OH-radical scavenging and DNA radical quenching

International Nuclear Information System (INIS)

Adhikary, A.; Bothe, E.; Von Sonntag, C.; Adhikary, A.

1997-01-01

The minor-groove-binding dye Hoechst 33258 has been found to protect pBR322 DNA in aqueous solution against radiation-induced single-strand breaks (ssb). This protective effect has been assumed to be largely due to the scavenging of the strand-break-generating OH radicals by Hoechst. From D 37 values for ssb at different Hoechst concentrations the value of the OH radical scavenging constant of DNA-bound Hoechst has been estimated at k Ho/DNA = 2.7 * 10 11 dm 3 mol -1 . This unexpectedly high value has led us to study the reactions of OH radicals with Hoechst in the absence and in the presence of double-stranded calf thymus DNA (ds DNA) by pulse radiolysis, and the formation of radiation-induced ssb by low angle laser light scattering. The D 37 /D 37 0 values at different Hoechst concentrations agree with the values obtained by Martin and al. and demonstrate the protection. However, this protection cannot be explained on the basis of OH radical scavenging alone using the above rate constants. There must, in addition, be some quenching of DNA radicals. Hoechst radicals are formed in the later ms time range, i.e a long time after the disappearance of the OH radicals. This delayed Hoechst radical formation has been assigned to a a reaction of DNA radicals with Hoechst, thereby inhibiting strand breakage. In confirmation, pulse radiolysis of aqueous solution of nucleotides in the presence of Hoechst yields a similar delayed Hoechst radical formation. The data indicate that in DNA the cross-section of this quenching has a diameter of 3 to 4 base pairs per Hoechst molecule. (N.C.)

An anaerobic bacterium, Bacteroides thetaiotaomicron, uses a consortium of enzymes to scavenge hydrogen peroxide

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Mishra, Surabhi; Imlay, James A.

2013-01-01

Summary Obligate anaerobes are periodically exposed to oxygen, and it has been conjectured that on such occasions their low-potential biochemistry will predispose them to rapid ROS formation. We sought to identify scavenging enzymes that might protect the anaerobe Bacteroides thetaiotaomicron from the H2O2 that would be formed. Genetic analysis of eight candidate enzymes revealed that four of these scavenge H2O2 in vivo: rubrerythrins 1 and 2, AhpCF, and catalase E. The rubrerythrins served as key peroxidases under anoxic conditions. However, they quickly lost activity upon aeration, and AhpCF and catalase were induced to compensate. The AhpCF is an NADH peroxidase that effectively degraded low micromolar levels of H2O2, while the catalytic cycle of catalase enabled it to quickly degrade higher concentrations that might arise from exogenous sources. Using a non-scavenging mutant we verified that endogenous H2O2 formation was much higher in aerated B. thetaiotaomicron than in Escherichia coli. Indeed, the OxyR stress response to H2O2 was induced when B. thetaiotaomicron was aerated, and in that circumstance this response was necessary to forestall cell death. Thus aeration is a serious threat for this obligate anaerobe, and to cope it employs a set of defenses that includes a repertoire of complementary scavenging enzymes. PMID:24164536

Seroepidemiologic Survey of Potential Pathogens in Obligate and Facultative Scavenging Avian Species in California

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Straub, Mary H.; Kelly, Terra R.; Rideout, Bruce A.; Eng, Curtis; Wynne, Janna; Braun, Josephine; Johnson, Christine K.

2015-01-01

Throughout the world, populations of scavenger birds are declining rapidly with some populations already on the brink of extinction. Much of the current research into the factors contributing to these declines has focused on exposure to drug residues, lead, and other toxins. Despite increased monitoring of these declining populations, little is known about infectious diseases affecting scavenger bird species. To assess potential infectious disease risks to both obligate and facultative scavenger bird species, we performed a serosurvey for eleven potential pathogens in three species of scavenging birds in California: the California condor (Gymnogyps californianus), turkey vulture (Cathartes aura) and golden eagle (Aquila chrysaetos). California condors were seropositive for avian adenovirus, infectious bronchitis virus, Mycoplasma gallisepticum, avian paramyxovirus-2, West Nile virus (WNV) and Toxoplasma gondii. Golden eagles were seropositive for avian adenovirus, Chlamydophila psittaci and Toxoplasma gondii, and turkey vultures were seropositive for avian adenovirus, Chlamydophila psittaci, avian paramyxovirus-1, Toxoplasma gondii and WNV. Risk factor analyses indicated that rearing site and original release location were significantly associated with a positive serologic titer to WNV among free-flying condors. This study provides preliminary baseline data on infectious disease exposure in these populations for aiding in early disease detection and provides potentially critical information for conservation of the endangered California condor as it continues to expand its range and encounter new infectious disease threats. PMID:26606755

Efficient Scavenging of Solar and Wind Energies in a Smart City.

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Wang, Shuhua; Wang, Xue; Wang, Zhong Lin; Yang, Ya

2016-06-28

To realize the sustainable energy supply in a smart city, it is essential to maximize energy scavenging from the city environments for achieving the self-powered functions of some intelligent devices and sensors. Although the solar energy can be well harvested by using existing technologies, the large amounts of wasted wind energy in the city cannot be effectively utilized since conventional wind turbine generators can only be installed in remote areas due to their large volumes and safety issues. Here, we rationally design a hybridized nanogenerator, including a solar cell (SC) and a triboelectric nanogenerator (TENG), that can individually/simultaneously scavenge solar and wind energies, which can be extensively installed on the roofs of the city buildings. Under the same device area of about 120 mm × 22 mm, the SC can deliver a largest output power of about 8 mW, while the output power of the TENG can be up to 26 mW. Impedance matching between the SC and TENG has been achieved by using a transformer to decrease the impedance of the TENG. The hybridized nanogenerator has a larger output current and a better charging performance than that of the individual SC or TENG. This research presents a feasible approach to maximize solar and wind energies scavenging from the city environments with the aim to realize some self-powered functions in smart city.

A drop in the pond: the effect of rapid mass-loss on the dynamics and interaction rate of collisionless particles

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Penoyre, Zephyr; Haiman, Zoltán

2018-01-01

In symmetric gravitating systems experiencing rapid mass-loss, particle orbits change almost instantaneously, which can lead to the development of a sharply contoured density profile, including singular caustics for collisionless systems. This framework can be used to model a variety of dynamical systems, such as accretion discs following a massive black hole merger and dwarf galaxies following violent early star formation feedback. Particle interactions in the high-density peaks seem a promising source of observable signatures of these mass-loss events (i.e. a possible EM counterpart for black hole mergers or strong gamma-ray emission from dark matter annihilation around young galaxies), because the interaction rate depends on the square of the density. We study post-mass-loss density profiles, both analytic and numerical, in idealized cases and present arguments and methods to extend to any general system. An analytic derivation is presented for particles on Keplerian orbits responding to a drop in the central mass. We argue that this case, with initially circular orbits, gives the most sharply contoured profile possible. We find that despite the presence of a set of singular caustics, the total particle interaction rate is reduced compared to the unperturbed system; this is a result of the overall expansion of the system dominating over the steep caustics. Finally, we argue that this result holds more generally, and the loss of central mass decreases the particle interaction rate in any physical system.

Extracts, Anthocyanins and Procyanidins from Aronia melanocarpa as Radical Scavengers and Enzyme Inhibitors

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Hilde Barsett

2013-03-01

Full Text Available Extracts, subfractions, isolated anthocyanins and isolated procyanidins B2, B5 and C1 from the berries and bark of Aronia melanocarpa were investigated for their antioxidant and enzyme inhibitory activities. Four different bioassays were used, namely scavenging of the diphenylpicrylhydrazyl (DPPH radical, inhibition of 15-lipoxygenase (15-LO, inhibition of xanthine oxidase (XO and inhibition of α-glucosidase. Among the anthocyanins, cyanidin 3-arabinoside possessed the strongest and cyanidin 3-xyloside the weakest radical scavenging and enzyme inhibitory activity. These effects seem to be influenced by the sugar units linked to the anthocyanidin. Subfractions enriched in procyanidins were found to be potent α-glucosidase inhibitors; they possessed high radical scavenging properties, strong inhibitory activity towards 15-LO and moderate inhibitory activity towards XO. Trimeric procyanidin C1 showed higher activity in the biological assays compared to the dimeric procyanidins B2 and B5. This study suggests that different polyphenolic compounds of A. melanocarpa can have beneficial effects in reducing blood glucose levels due to inhibition of α-glucosidase and may have a potential to alleviate oxidative stress.

Anti-oxidation and scavenging effects of some extracts from Chinese medicines on free radicals

International Nuclear Information System (INIS)

Wang Chongdao; Qiang Yizhong; Lao Qinhua; Cui Fengmei; Shao Yuan; Sun Cunpu

1999-11-01

The inhibiting effects of Chinonin, Quercetin and Tannic Acid on the lipid oxidation induced by radiation exposure were investigated by means of a modified TBA spectrophotometry. The scavenging effects on free radicals caused by γ-irradiation exposure of the three active principles were observed by technique of ESR. The results showed that anti-oxidation effects of Chinonin and Quercetin were better than that of Tannic Acid, while the scavenging effects of the three active principles on free radicals were similar

Extraction method for high free radical scavenging activity of Siamese neem tree flowers

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Worarat Chaisawangwong

2009-10-01

Full Text Available Siamese neem tree (Azadirachta indica A. Juss. var. siamensis Valeton is a medicinal plant found in Thailand. Youngleaves and young flowers of this plant are commonly consumed as a bitter tonic vegetable. The flowers are also used fortreatment of fever. The flower extract has been reported to exhibit in vitro free radical scavenging activity and can inhibitlipid peroxidation of bronchogenic cancer cell line. Active compounds in the flowers are flavonoids such as rutin andquercetin. The content of these compounds in the crude extract depends on the method of extraction. Therefore, the appropriateextraction method promoting high yield of total flavonoids and high free radical scavenging activity was investigated inthis study. Six different extraction methods, i.e. maceration, percolation, decoction, soxhlet extraction, ultrasonic extraction(UE, and microwave assisted extraction (MA were carried out for extracting dried powder of Siamese neem tree young flowers. The solvent used for maceration, percolation, and soxhlet extraction was 50% ethanol, while distilled water was used for decoction and MA, and both solvents were used for UE. The content of crude extract, free radical scavenging activity, and total flavonoids content of each extract were investigated and compared. Comparing the various extraction methods, decoction provided an extract containing a high amount of total flavonoids (17.54 mgRE/g extract and promoting the highest scavenging activity at EC50 11.36 g/ml. Decoction is also simple, cheap, and convenient and could be used in developing countries. Thus, it should be the recommended extraction method for the flowers of Siamese neem tree for furtherdevelopment of antioxidant pharmaceutical preparations.

Parameter Optimization on the Uniflow Scavenging System of an OP2S-GDI Engine Based on Indicated Mean Effective Pressure (IMEP

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Fu-Kang Ma

2017-03-01

Full Text Available In this paper, an opposed-piston two-stroke (OP2S gasoline direct injection (GDI engine is introduced and its working principles and scavenging process were analyzed. An optimization function was established to optimize the scavenging system parameters, include intake port height, exhaust port height, intake port circumference ratio, the exhaust port circumference ratio and opposed-piston motion phase difference. The effect of the port height on the effective compression ratio and effective expansion ratio were considered, and indicated mean effective pressure (IMEP was employed as the optimization objective instead of scavenging efficiency. Orthogonal experiments were employed to reduce the calculation work. The effect of the scavenging parameters on delivery ratio, trapping ratio, scavenging efficiency and indicated thermal efficiency were calculated, and the best parameters were also obtained by the optimization function. The results show that IMEP can be used as the optimization objective in the uniflow scavenging system; intake port height is the main factor to the delivery ratio, while exhaust port height is the main to engine trapping ratio, scavenging efficiency and indicated thermal efficiency; exhaust port height is the most important factor to effect the gas exchange process of OP2S-GDI engine.

Scavenger Receptor BI Plays a Role in Facilitating Chylomicron Metabolism

NARCIS (Netherlands)

Out, R.; Kruijt, J.K.; Rensen, P.C.N.; Hildebrand, R.B.; Vos, P. de; Eck, M. van; Berkel, T.J.C. van

2004-01-01

The function of scavenger receptor class B type I (SR-BI) in mediating the selective uptake of high density lipoprotein (HDL) cholesterol esters is well established. However, the potential role of SR-BI in chylomicron and chylomicron remnant metabolism is largely unknown. In the present

Composition and properties of atmospheric particles in the eastern Atlantic and impacts on gas phase uptake rates

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G. McFiggans

2009-12-01

humidity using HTDMA data. Heterogeneous uptake rates of hypoiodous acid (HOI were also predicted and the nss accumulation mode was found to be the most significant part of the size distribution, which could act as an inert sink for this species. The predicted uptake rates were enhanced by around a factor of 2 during the African influence period due to the addition of both coarse and fine particles.

The hygroscopicity of the nss fraction was modelled using the Aerosol Diameter Dependent Equilibrium Model (ADDEM using the measured composition and results compared with the HTDMA data. This was the first time such a reconciliation study with this model has been performed with marine data and good agreement was reached within the resolution of the instruments. The effect of hygroscopic growth on HOI uptake was also modelled and ambient uptake rates were found to be approximately doubled compared to equivalent dry particles.

High risk of lead contamination for scavengers in an area with high moose hunting success.

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Legagneux, Pierre; Suffice, Pauline; Messier, Jean-Sébastien; Lelievre, Frédérick; Tremblay, Junior A; Maisonneuve, Charles; Saint-Louis, Richard; Bêty, Joël

2014-01-01

Top predators and scavengers are vulnerable to pollutants, particularly those accumulated along the food chain. Lead accumulation can induce severe disorders and alter survival both in mammals (including humans) and in birds. A potential source of lead poisoning in wild animals, and especially in scavengers, results from the consumption of ammunition residues in the tissues of big game killed by hunters. For two consecutive years we quantified the level lead exposure in individuals of a sentinel scavenger species, the common raven (Corvus corax), captured during the moose (Alces alces) hunting season in eastern Quebec, Canada. The source of the lead contamination was also determined using stable isotope analyses. Finally, we identified the different scavenger species that could potentially be exposed to lead by installing automatic cameras targeting moose gut piles. Blood lead concentration in ravens increased over time, indicating lead accumulation over the moose-hunting season. Using a contamination threshold of 100 µg x L(-1), more than 50% of individuals were lead-contaminated during the moose hunting period. Lead concentration was twice as high in one year compared to the other, matching the number of rifle-shot moose in the area. Non-contaminated birds exhibited no ammunition isotope signatures. The isotope signature of the lead detected in contaminated ravens tended towards the signature from lead ammunition. We also found that black bears (Ursus americanus), golden eagles and bald eagles (Aquila chrysaetos and Haliaeetus leucocephalus, two species of conservation concern) scavenged heavily on moose viscera left by hunters. Our unequivocal results agree with other studies and further motivate the use of non-toxic ammunition for big game hunting.

High risk of lead contamination for scavengers in an area with high moose hunting success.

Directory of Open Access Journals (Sweden)

Pierre Legagneux

Full Text Available Top predators and scavengers are vulnerable to pollutants, particularly those accumulated along the food chain. Lead accumulation can induce severe disorders and alter survival both in mammals (including humans and in birds. A potential source of lead poisoning in wild animals, and especially in scavengers, results from the consumption of ammunition residues in the tissues of big game killed by hunters. For two consecutive years we quantified the level lead exposure in individuals of a sentinel scavenger species, the common raven (Corvus corax, captured during the moose (Alces alces hunting season in eastern Quebec, Canada. The source of the lead contamination was also determined using stable isotope analyses. Finally, we identified the different scavenger species that could potentially be exposed to lead by installing automatic cameras targeting moose gut piles. Blood lead concentration in ravens increased over time, indicating lead accumulation over the moose-hunting season. Using a contamination threshold of 100 µg x L(-1, more than 50% of individuals were lead-contaminated during the moose hunting period. Lead concentration was twice as high in one year compared to the other, matching the number of rifle-shot moose in the area. Non-contaminated birds exhibited no ammunition isotope signatures. The isotope signature of the lead detected in contaminated ravens tended towards the signature from lead ammunition. We also found that black bears (Ursus americanus, golden eagles and bald eagles (Aquila chrysaetos and Haliaeetus leucocephalus, two species of conservation concern scavenged heavily on moose viscera left by hunters. Our unequivocal results agree with other studies and further motivate the use of non-toxic ammunition for big game hunting.

Radical-scavenging-linked antioxidant activities of extracts from black chokeberry and blueberry cultivated in Korea.

Science.gov (United States)

Hwang, Seok Joon; Yoon, Won Byong; Lee, Ok-Hwan; Cha, Seung Ju; Kim, Jong Dai

2014-03-01

The objective of this study was to investigate the radical-scavenging-linked antioxidant properties of the extracts from black chokeberry and blueberry cultivated in Korea. The 70% ethanol extracts were prepared from black chokeberry and blueberry, and evaluated for total phenolic content, total flavonoid content, total proanthocyanidin content, and antioxidative activities, using various in vitro assays, such as DPPH(2,2-diphenyl-1-picrylhydrazyl), ABTS(2,2-azino-bis-(3-ethylenebenzothiozoline-6-sulphonic acid)) radical-scavenging activity, FRAP(ferric-reducing antioxidant power) and reducing power. The major phenolic compounds, including cyanidin-3-galactoside, cyanidin-3-arabinoside, neochlorogenic acid, procyanidin B1, were analysed by HPLC with a photodiode array detector. Results showed that total phenol, flavonoid and proanthocyanidin contents of black chokeberry extract were higher than those of blueberry extract. In addition, black chokeberry extract exhibited higher free radical-scavenging activity and reducing power than did blueberry extract. Cyanidin-3-galactoside was identified as a major phenolic compound, with considerable content in black chokeberry, that correlated with its higher antioxidant and radical-scavenging effects. These results suggest that black chokeberry extracts could be considered as a good source of natural antioxidants and functional food ingredients. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Efficacy of Edaravone (Radicut, a Free Radical Scavenger, for Cardiovascular Disease

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Eiichiro Tanaka

2013-07-01

Full Text Available Edaravone was originally developed as a potent free radical scavenger, and has been widely used to treat acute ischemic stroke in Japan since 2001. Free radicals play an important role in the pathogenesis of a variety of diseases, such as cardiovascular diseases and stroke. Therefore, free radicals may be targets for therapeutic intervention in these diseases. Edaravone shows protective effects on ischemic insults and inflammation in the heart, vessel, and brain in experimental studies. As well as scavenging free radicals, edaravone has anti-apoptotic, anti-necrotic, and anti-cytokine effects in cardiovascular diseases and stroke. Edaravone has preventive effects on myocardial injury following ischemia and reperfusion in patients with acute myocardial infarction. Edaravone may represent a new therapeutic intervention for endothelial dysfunction in the setting of atherosclerosis, heart failure, diabetes, or hypertension, because these diseases result from oxidative stress and/or cytokine-induced apoptosis. This review evaluates the potential of edaravone for treatment of cardiovascular disease, and covers clinical and experimental studies conducted between 1984 and 2013. We propose that edaravone, which scavenges free radicals, may offer a novel option for treatment of cardiovascular diseases. However, additional clinical studies are necessary to verify the efficacy of edaravone.

Free-Radical-Scavenging, Antityrosinase, and Cellular Melanogenesis Inhibitory Activities of Synthetic Isoflavones.

Science.gov (United States)

Lu, Tzy-Ming; Ko, Horng-Huey; Ng, Lean-Teik; Hsieh, Yen-Pin

2015-06-01

In this study, we examined the potential of synthetic isoflavones for application in cosmeceuticals. Twenty-five isoflavones were synthesized and their capacities of free-radical-scavenging and mushroom tyrosinase inhibition, as well as their impact on cell viability of B16F10 murine melanoma cells and HaCaT human keratinocytes were evaluated. Isoflavones that showed significant mushroom tyrosinase inhibitory activities were further studied on reduction of cellular melanin formation and antityrosinase activities in B16F10 melanocytes in vitro. Among the isoflavones tested, 6-hydroxydaidzein (2) was the strongest scavenger of both ABTS(.+) and DPPH(.) radicals with SC50 values of 11.3 ± 0.3 and 9.4 ± 0.1 μM, respectively. Texasin (20) exhibited the most potent inhibition of mushroom tyrosinase (IC50 14.9 ± 4.5 μM), whereas retusin (17) showed the most efficient inhibition both of cellular melanin formation and antityrosinase activity in B16F10 melanocytes, respectively. In summary, both retusin (17) and texasin (20) exhibited potent free-radical-scavenging capacities as well as efficient inhibition of cellular melanogenesis, suggesting that they are valuable hit compounds with potential for advanced cosmeceutical development. Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich.