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1

Acetylene, Not Ethylene, Inactivates the Uptake Hydrogenase of Actinorhizal Nodules during Acetylene Reduction Assays 1  

PubMed Central

Acetylene reduction assays were shown to inactivate uptake hydrogenase activity to different extents in one Casuarina and two Alnus symbioses. Inactivation was found to be caused by C2H2 and not by C2H4. Acetylene completely inactivated the hydrogenase activity of intact root systems of Alnus incana inoculated with Frankia strain Avcl1 in 90 minutes, as shown by a drop in the relative efficiency of nitrogenase from 1.0 to 0.73. The hydrogenase of Frankia preparations (containing vesicles) and of cell-free extracts (not containing vesicles) from the same symbiosis was much more susceptible to acetylene inactivation. Cell-free extracts lost all hydrogenase activity after 5 minutes of exposure to acetylene. The hydrogenase activity of intact root systems of Casuarina obesa was less sensitive to acetylene than that of root systems of A. incana, since the relative efficiency of nitrogenase changed only from 1.0 to 0.95 over 90 minutes. Frankia preparations and cell-free extracts of C. obesa still retained hydrogenase activity after a 10 minute-exposure to acetylene. PMID:16667724

Sellstedt, Anita; Winship, Lawrence J.

1990-01-01

2

Acetylene, Not Ethylene, Inactivates the Uptake Hydrogenase of Actinorhizal Nodules during Acetylene Reduction Assays.  

PubMed

Acetylene reduction assays were shown to inactivate uptake hydrogenase activity to different extents in one Casuarina and two Alnus symbioses. Inactivation was found to be caused by C(2)H(2) and not by C(2)H(4). Acetylene completely inactivated the hydrogenase activity of intact root systems of Alnus incana inoculated with Frankia strain Avcl1 in 90 minutes, as shown by a drop in the relative efficiency of nitrogenase from 1.0 to 0.73. The hydrogenase of Frankia preparations (containing vesicles) and of cell-free extracts (not containing vesicles) from the same symbiosis was much more susceptible to acetylene inactivation. Cell-free extracts lost all hydrogenase activity after 5 minutes of exposure to acetylene. The hydrogenase activity of intact root systems of Casuarina obesa was less sensitive to acetylene than that of root systems of A. incana, since the relative efficiency of nitrogenase changed only from 1.0 to 0.95 over 90 minutes. Frankia preparations and cell-free extracts of C. obesa still retained hydrogenase activity after a 10 minute-exposure to acetylene. PMID:16667724

Sellstedt, A; Winship, L J

1990-09-01

3

Acetylene reduction by nitrogen-fixing blue-green algae  

Microsoft Academic Search

Known nitrogen-fixing species of blue-green algae are capable of reducing acetylene to ethylene, but acetylene is not reduced by Anacystis nidulans, which does not fix nitrogen. Cycad root nodules which contain blue-green algae as endophytes reduce acetylene. Acetylene reduction is inhibited by carbon monoxide. Nitrate or ammonium-nitrogen has no immediate effect on algae reducing acetylene, but algae grown on nitrate-nitrogen

W. D. P. Stewart; G. P. Fitzgerald; R. H. Burris

1968-01-01

4

Acetylene inhibition of nitrous oxide reduction by denitrifying bacteria  

Microsoft Academic Search

Acetylene (0.1 atm) caused complete or almost complete inhibition of reduction of NâO by whole cell suspensions of Pseudomonas perfectomarinus, P. aeruginosa and Micrococcus denitrificans. Acetylene did not inhibit reduction of NOâ⁻ or NOâ⁻ by these organisms. In the presence of acetylene there was stoichiometric conversion of NOâ⁻ or NOâ⁻ to NâO with negligible subsequent reduction of the latter. In

T. Yoshinari; R. Knowles

1976-01-01

5

Aerobic nitrogenase activity measured as acetylene reduction in the marine non-heterocystous cyanobacterium Trichodesmium spp. grown under artificial conditions  

Microsoft Academic Search

Aerobic nitrogenase activity in the marine non-heterocystous cyanobacterium Trichodesmium spp. NIBB 1067, isolated off the Izu Peninsula, Japan in 1983 and grown under artificial conditions, was assayed by the acetylene reduction method. This strain exhibited acetylene reduction activity under aerobic conditions when cells had been grown in the medium free of combined nitrogen. Activity was markedly enhanced by light, and

K. Ohki; Y. Fujita

1988-01-01

6

Comparison of N2 Fixation and Yields in Cajanus cajan between Hydrogenase-Positive and Hydrogenase-Negative Rhizobia by In Situ Acetylene Reduction Assays and Direct 15N Partitioning 1  

PubMed Central

Pigeon peas [Cajanus cajan (L.) Millsp.] were grown in soil columns containing 15N-enriched organic matter. Seasonal N2 fixation activity was determined by periodically assaying plants for reduction of C2H2. N2 fixation rose sharply from the first assay period at 51 days after planting to a peak of activity between floral initiation and fruit set. N2 fixation (acetylene reduction) activity dropped concomitantly with pod maturation but recovered after pod harvests. Analysis of 15N content of plant shoots revealed that approximately 91 to 94% of plant N was derived from N2 fixation. The effect of inoculation with hydrogenase-positive and hydrogenase-negative rhizobia was examined. Pigeon peas inoculated with strain P132 (hydrogenase-positive) yielded significantly more total shoot N than other inoculated or uninoculated treatments. However, two other hydrogenase-positive strains did not yield significantly more total shoot N than a hydrogenase-negative strain. The extent of nodulation by inoculum strains compared to indigenous rhizobia was determined by typing nodules according to intrinsic antibiotic resistance of the inoculum strains. The inoculum strains were detected in almost all typed nodules of inoculated plants. Gas samples were taken from soil columns several times during the growth cycle of the plants. H2 was never detected, even in columns containing pigeon peas inoculated with hydrogenase-negative rhizobia. This was attributed to H2 consumption by soil bacteria. Estimation of N2 fixation by acetylene reduction activity was closest to the direct 15N method when ethylene concentrations in the gas headspace (between the column lid and soil surface) were extrapolated to include the soil pore space as opposed solely to measurement in the headspace. There was an 8-fold difference between the two acetylene reduction assay methods of estimation. Based on a planting density of 15,000 plants per hectare, the direct 15N fixation rates ranged from 67 (noninoculated) to 134 kilograms per hectare, while grain yields ranged from 540 to 825 kilograms per hectare. Grain yields were not increased with N fertilizer. PMID:16663148

La Favre, Jeffrey S.; Focht, Dennis D.

1983-01-01

7

Acetylene Reduction Activity in Free-Living Cultures of Rhizobia  

Microsoft Academic Search

A survey of 272 free-living rhizobia strains showed that a majority of the Rhizobium japonicum and unclassified Rhizobium isolates are capable of both growth and acetylene reduction on a Casamino Acids-minimal medium. Two other taxonomic categories of Rhizobium were discernible: R. meliloti and R. trifolii, which grow but do not reduce acetylene; and R. leguminosarum, which fails to grow on

T. KANESHIRO; C. D. CROWELL; R. F. HANRAHAN

8

Nitrogen-fixation associated with the marine blue-green alga, Trichodesmium , as measured by the acetylene-reduction technique  

Microsoft Academic Search

The marine blue-green alga, Trichodesmium, was collected from the Gulf Stream, near Miami, and occurred in two distinct colonial forms both of which reduced acetylene to ethylene. Trichodesmium was more abundant during the summer but its acetylene-reducing potential showed no obvious seasonal variation. Illuminated Trichodesmium reduced acetylene to ethylene equally well either anaerobically or aerobically (20% oxygen). Acetylene-reduction in the

Barrie F. Taylor; Chun C. Lee; John S. Bunt

1973-01-01

9

Growth and acetylene reduction activity by intact plants of Alnus incana under field conditions  

Microsoft Academic Search

The nitrogen-fixing grey alder,Alnus incana (L.) Moench, has a potential use in forest soil restoration and as part of energy forestry plantations. As a first step to estimate nitrogen fixation byA. incana under field conditions we performed studies on nitrogenase activity and its possible relation to abiotic factors and growth of the alders. Nitrogenase activity was measured as acetylene reduction

Kerstin Huss-Danell; Per-Olof Lundquist; Alf Ekblad

1989-01-01

10

Changes in acetylene reduction activities and effects of inoculated rhizosphere nitrogen-fixing bacteria on rice  

Microsoft Academic Search

Acetylene reduction activities (ARAs) of soils and rice plants during rice-growing season were monitored in temperate region in northeast China. This activity was significantly higher in rhizosphere soil than that in inter-row soil after rice seedlings were transplanted. The ARA was high for most of growing season, suggesting that the native N2-fixing bacteria responded to rice roots very quickly. Sixteen

Zhe Piao; Zongjun Cui; Bin Yin; Jian Hu; Chunhong Zhou; Guanghui Xie; Baolin Su; Shixue Yin

2005-01-01

11

Acetylene reduction, H2 evolution and (15)N 2 fixation in the Alnus incana-Frankia symbiosis.  

PubMed

Acetylene reduction, (15)N2 reduction and H2 evolution were measured in root systems of intact plants of grey alder (Alnus incana (L.) Moench) in symbiosis with Frankia. The ratios of C2H2: (15)N2 were compared with C2H2:N2 ratios calculated from C2H2 reduction and H2 evolution, and with C2H2:N2 ratios calculated from accumulated C2H4 production and nitrogen content. It was possible to calculate C2H2:N2 ratios from C2H2 reduction and H2 evolution because this source of Frankia did not show any hydrogenase activity. The ratios obtained using the different methods ranged from 2.72 to 4.42, but these values were not significantly different. It was also shown that enriched (15)N could be detected in the shoot after a 1-h incubation of the root-system. It is concluded that the measurement of H2 evolution in combination with C2H2 reduction represents a nondestructive assay for nitrogen fixation in a Frankia symbiosis which shows no detectable hydrogenase activity. PMID:24240308

Sellstedt, A

1986-03-01

12

High rate of N2 fixation by East Siberian cryophilic soil bacteria as determined by measuring acetylene reduction in nitrogen-poor medium solidified with gellan gum.  

PubMed

For evaluating N(2) fixation of diazotrophic bacteria, nitrogen-poor liquid media supplemented with at least 0.5% sugar and 0.2% agar are widely used for acetylene reduction assays. In such a soft gel medium, however, many N(2)-fixing soil bacteria generally show only trace acetylene reduction activity. Here, we report that use of a N(2) fixation medium solidified with gellan gum instead of agar promoted growth of some gellan-preferring soil bacteria. In a soft gel medium solidified with 0.3% gellan gum under appropriate culture conditions, bacterial microbiota from boreal forest bed soils and some free-living N(2)-fixing soil bacteria isolated from the microbiota exhibited 10- to 200-fold-higher acetylene reduction than those cultured in 0.2% agar medium. To determine the N(2) fixation-activating mechanism of gellan gum medium, qualitative differences in the colony-forming bacterial components from tested soil microbiota were investigated in plate cultures solidified with either agar or gellan gum for use with modified Winogradsky's medium. On 1.5% agar plates, apparently cryophilic bacterial microbiota showed strictly distinguishable microbiota according to the depth of soil in samples from an eastern Siberian Taiga forest bed. Some pure cultures of proteobacteria, such as Pseudomonas fluorescens and Burkholderia xenovorans, showed remarkable acetylene reduction. On plates solidified with 1.0% gellan gum, some soil bacteria, including Luteibacter sp., Janthinobacterium sp., Paenibacillus sp., and Arthrobacter sp., uniquely grew that had not grown in the presence of the same inoculants on agar plates. In contrast, Pseudomonas spp. and Burkholderia spp. were apparent only as minor colonies on the gellan gum plates. Moreover, only gellan gum plates allowed some bacteria, particularly those isolated from the shallow organic soil layer, to actively swarm. In consequence, gellan gum is a useful gel matrix to bring out growth potential capabilities of many soil diazotrophs and their consortia in communities of soil bacteria. PMID:19286791

Hara, Shintaro; Hashidoko, Yasuyuki; Desyatkin, Roman V; Hatano, Ryusuke; Tahara, Satoshi

2009-05-01

13

Reduction of Acetylene and Hydrazine with a Molybdenum-Glutathione Complex  

PubMed Central

Crystalline preparations of a molybdenum-glutathione complex catalyze the reduction of acetylene to ethylene in the presence of borohydride. The reaction proceeds at rates up to 6 mol of C2H2 produced per min per mol of bound Mo, which is 4% of the activity of a quantity of nitrogenase with an equivalent amount of Mo. The activity of the complex is enhanced 100-fold by ATP, but the addition of ADP has no effect. Stimulation in activity by GTP is about the same as that by ATP, and the effects of CTP or UTP are considerably less. Inhibition of acetylene-reduction activity by the addition of 32 mM orthophosphate was 14%, by 32 mM pyrophosphate 62%, by 0.2 atm of O2 65%, and by 0.5 atm of CO 12%; 0.5 atm of H2 had no effect. The molybdenum-glutathione complex also catalyzes the reduction of hydrazine to ammonia in a reaction that is dependent upon borohydride. The reaction is enhanced about 7-fold by ATP and proceeds at a rate of 2 mol of NH3 produced per min per mol of bound Mo. PMID:16592055

Werner, Dietrich; Russell, Sterling A.; Evans, Harold J.

1973-01-01

14

Carbon dioxide reduction to methane and coupling with acetylene to form propylene catalyzed by remodeled nitrogenase  

PubMed Central

A doubly substituted form of the nitrogenase MoFe protein (?-70Val?Ala, ?-195His?Gln) has the capacity to catalyze the reduction of carbon dioxide (CO2) to yield methane (CH4). Under optimized conditions, 1 nmol of the substituted MoFe protein catalyzes the formation of 21 nmol of CH4 within 20 min. The catalytic rate depends on the partial pressure of CO2 (or concentration of HCO3?) and the electron flux through nitrogenase. The doubly substituted MoFe protein also has the capacity to catalyze the unprecedented formation of propylene (H2C = CH-CH3) through the reductive coupling of CO2 and acetylene (HC?CH). In light of these observations, we suggest that an emerging understanding of the mechanistic features of nitrogenase could be relevant to the design of synthetic catalysts for CO2 sequestration and formation of olefins. PMID:23150564

Yang, Zhi-Yong; Moure, Vivian R.; Dean, Dennis R.; Seefeldt, Lance C.

2012-01-01

15

Effects of Abiotic Factors on Acetylene Reduction by Cyanobacteria Epiphytic on Moss at a Subantarctic Island  

PubMed Central

Acetylene reduction (AR) rates by cyanobacteria epiphytic on a moss at Marion Island (46°54? S, 37°45? E) increased from ?5°C to a maximum at 25 to 27°C. Q10 values between 0 and 25°C were between 2.3 and 2.9, depending on photosynthetic photon flux density. AR rates declined sharply at temperatures above the optimum and were lower at 35°C than at 0°C. Photosynthetic photon flux density at low levels markedly influenced AR, and half of the maximum rate occurred at 84 ?mol m?2 s?1, saturation occurring at ca. 1,000 ?mol m?2 s?1. Higher photosynthetic photon flux density levels decreased AR rates. AR increased up to the highest sample moisture content investigated (3,405%), and the pH optimum was between 5.9 and 6.2. The addition of P, Co, and Mo, individually or together, depressed AR. PMID:16346626

Smith, Valdon R.

1984-01-01

16

Acetylene reduction (nitrogen fixation) by enterobacteriaceae isolated from paper mill process waters.  

PubMed

Using selective media containing galactitol, over 130 Enterobacteriaceae have been isolated from paper mill process waters collected from different localities. These bacteria were extensively characterized and tested for acetylene-reducing (nitrogen-fixing) activity under anaerobic conditions. High activity was found in representatives of Klebsiella pneumoniae, Enterobacter aerogenes, Enterobacter cloacae, Erwinia herbicola, Citrobacter freundii, Citrobacter intermedius, and Escherichia coli. Under argon, nitrogenase synthesis was generally not repressed by 5 mM l-glutamate, l-aspartate, l-leucine or Casamino Acids (0.5 g/liter). In many strains, both the specific activities (nanomoles of C(2)H(4) per minute per milligram of protein) and the activities (nanomoles of C(2)H(4) per minute) had considerably declined after 24 h. In three selected strains, activity in intact cells grown under nitrogen was unaffected by the presence during assay of 10 mM l-amino acids or ammonium acetate. All of the strains examined were tolerant towards inactivation of nitrogen-fixing activity by 1.8% (vol/vol) oxygen during assay, and inactivation by up to 10% oxygen was partly reversible. Representatives of the six taxa synthesized nitrogenase in stirred aerobic cultures, though the protein concentrations attained were lower than under anaerobic conditions. It seems reasonable to suggest that under natural conditions, nitrogen fixation is able to contribute significantly to the nitrogen economy of the cells. PMID:16345168

Neilson, A H; Sparell, L

1976-08-01

17

Acetylene reduction, H 2 evolution and 15 N 2 fixation in the Alnus incana-Frankia symbiosis  

Microsoft Academic Search

Acetylene reduction, 15N2 reduction and H2 evolution were measured in root systems of intact plants of grey alder (Alnus incana (L.) Moench) in symbiosis with Frankia. The ratios of C2H2: 15N2 were compared with C2H2:N2 ratios calculated from C2H2 reduction and H2 evolution, and with C2H2:N2 ratios calculated from accumulated C2H4 production and nitrogen content. It was possible to calculate

A. Sellstedt

1986-01-01

18

Root-Associated N2 Fixation (Acetylene Reduction) by Enterobacteriaceae and Azospirillum Strains in Cold-Climate Spodosols  

PubMed Central

N2 fixation by bacteria in associative symbiosis with washed roots of 13 Poaceae and 8 other noncultivated plant species in Finland was demonstrated by the acetylene reduction method. The roots most active in C2H2 reduction were those of Agrostis stolonifera, Calamagrostis lanceolata, Elytrigia repens, and Phalaris arundinacea, which produced 538 to 1,510 nmol of C2H4·g?1 (dry weight)· h?1 when incubated at pO2 0.04 with sucrose (pH 6.5), and 70 to 269 nmol of C2H4· g?1 (dry weight)·h?1 without an added energy source and unbuffered. Azospirillum lipferum, Enterobacter agglomerans, Klebsiella pneumoniae, and a Pseudomonas sp. were the acetylene-reducing organisms isolated. The results demonstrate the presence of N2-fixing organisms in associative symbiosis with plant roots found in a northern climatic region in acidic soils ranging down to pH 4.0. PMID:16345687

Haahtela, Kielo; Wartiovaara, Tuula; Sundman, Veronica; Skuji?š, J.

1981-01-01

19

Nitrogen fixation (Acetylene Reduction) by annual winter legumes on a coal surface mine  

SciTech Connect

The winter annuals, crimson clover, rose clover, subterranean clover and hairy vetch, were evaluated for nitrogen fixing capacity on coal surface mine substrates by measuring their ability to reduce acetylene to ethylene. The effects of fertilizer, Abruzzi rye, Kentucky 31 fescue grass and a phytotoxic plant Chenopodium album on nitrogen fixation were also assessed. Crimson clover was recommended as the best legume to use on topsoil and shale in the south. Hairy vetch gave good results on shale and subterranean clover did well on topsoil. The use of these species for revegetation is discussed. Overall, no correlation between substrate pH and ethylene levels was found and effects of substrate depended upon the legume species. Super phosphate fertilizer supported less nitrogen fixation than 13-13-13. Abruzzi rye in some unknown way inhibited plant density and nitrogen fixation by legumes but not by free living substrate micro-organisms. Shale from under dead Chenopodium plants in both field and greehouse experiments did not inhibit nitrogen fixation. 7 tables.

Gabrielson, F.C.

1982-01-01

20

Diel interactions of oxygenic photosynthesis and n(2) fixation (acetylene reduction) in a marine microbial mat community.  

PubMed

Diel variations in N(2) fixation (acetylene reduction), CO(2) fixation, and oxygen concentrations were measured, on three separate occasions, in a marine microbial mat located on Shackleford Banks, North Carolina. Nitrogenase activity (NA) was found to be inversely correlated with CO(2) fixation and, in two of the three diel periods studied, was higher at night than during the day. Oxygen concentrations within the top 3 mm of the mat ranged from 0 to 400 muM on a diel cycle; anaerobic conditions generally persisted below 4 mm. NA in the mat was profoundly affected by naturally occurring oxygen concentrations. Experimentally elevated oxygen concentrations resulted in a significant depression of NA, whereas the addition of the Photosystem II inhibitor 3(3,4-dichlorophenyl)-1,1-dimethylurea decreased oxygen concentrations within the mat and resulted in a significant short-term enhancement of NA. Mat N(2)-fixing microorganisms include cyanobacteria and heterotrophic, photoautotrophic, and chemolithotrophic eubacteria. Measured (whole-mat) NA is probably due to a combination of the NA of each of these groups of organisms. The relative contributions of each group to whole-mat NA probably varied during diel and seasonal (successional) cycles. Reduced compounds derived from photosynthetic CO(2) fixation appeared to be an important source of energy for NA during the day, whereas heterotrophic or chemolithotrophic utilization of reduced compounds appeared to be an important source of energy for NA at night, under reduced ambient oxygen concentrations. Previous estimates of N(2) fixation calculated on the basis of daytime measurements may have seriously underestimated diel and seasonal nitrogen inputs in mat systems. PMID:16347456

Bebout, B M; Paerl, H W; Crocker, K M; Prufert, L E

1987-10-01

21

Definition of human rotavirus serotypes by plaque reduction assay.  

PubMed Central

Twenty different human rotavirus reassortants were characterized serologically by a plaque reduction assay as belonging to one of three distinct serotypes. Fourteen were similar if not identical to our prototype Wa strain; two were like the prototype DS-1 strain, and four belonged to a third serotype for which a prototype has not yet been selected. Hyperimmune sera raised against the three serotypes were required to distinguish among them, since postinfection sera had lower titers and were more cross-reactive than hyperimmune sera. These results confirmed the ability of a qualitative cytopathic neutralization test to predict correctly the Wa or DS-1 serotype. A strain of rhesus rotavirus (MMU 18006) was identified as belonging to the newly defined third serotype. Finally, an attempt was made to correlate previously published serotype analysis by neutralization of fluorescent cell-forming units with the results determined by the plaque reduction neutralization assay. PMID:6286487

Wyatt, R G; Greenberg, H B; James, W D; Pittman, A L; Kalica, A R; Flores, J; Chanock, R M; Kapikian, A Z

1982-01-01

22

Molecule-assisted nanoparticle clustering effect in immunomagnetic reduction assay  

NASA Astrophysics Data System (ADS)

Immunomagnetic reduction assay is used to quantitatively detect bio-molecules. Many reports show that the to-be-detected bio-molecular concentration dependent reduction in the alternative-current (ac) magnetic susceptibility of a reagent is governed by the logistic function, which is a four-parameter function. One of the parameters relates to the increase in the rate of the magnetic reduction signal when the concentration of to-be-detected bio-molecules is increased. Theoretically, this parameter is attributed to the clustering associations between to-be-detected bio-molecules and labeling particles in the reagent. In an immunomagnetic reduction assay, the bioactive labeling particles are anti-body-functionalized magnetic nanoparticles. However, there is no detailed information about the effect of the clustering associations on this parameter. In this work, the clustering association is manipulated by controlling the concentrations of anti-body-functionalized magnetic nanoparticles in the reagent. The experimental results show that higher values for this parameter are obtained with concentrated anti-body-functionalized magnetic nanoparticles in the reagent. This implies that particle clustering is enhanced by an increase in the concentration of the bio-functionalized magnetic particles. It is also demonstrated that the particle clustering effect dominates the increased rate of the magnetic reduction signal.

Yang, S. Y.; Chieh, J. J.; Huang, K. W.; Yang, C. C.; Chen, T. C.; Ho, C. S.; Chang, S. F.; Chen, H. H.; Horng, H. E.; Hong, C. Y.; Yang, H. C.

2013-04-01

23

Molecular Structure of Acetylene  

NSDL National Science Digital Library

Acetylene is an odorless and colorless gas that was discovered in England by E. Davy. This gas can be made from limestone and coal or from other petrochemical processes. The combustion of acetylene and pure oxygen produces the hottest flame temperature possible of 3300oC. As a result, it is an important fuel for welding and cutting metals. In addition, this chemical can be used as an anesthetic, however overexposure is hazardous. Nowadays acetylene is used for carburization (i.e. hardening) of steel. Research in the last ten years came to the conclusion, that acetylene is the best hydrocarbon available for this purpose.

2002-08-14

24

29 CFR 1910.102 - Acetylene.  

Code of Federal Regulations, 2011 CFR

...Chapter 9 (“Acetylene Piping”) of NFPA 51A-2006 (“Standard for Acetylene...Chapter 7 (“Acetylene Piping”) of NFPA 51A-2001 (“Standard for Acetylene Charging...cylinders comply with the provisions of NFPA 51A-2006 (“Standard for Acetylene...

2011-07-01

25

29 CFR 1910.102 - Acetylene.  

Code of Federal Regulations, 2010 CFR

...Chapter 9 (“Acetylene Piping”) of NFPA 51A-2006 (“Standard for Acetylene...Chapter 7 (“Acetylene Piping”) of NFPA 51A-2001 (“Standard for Acetylene Charging...cylinders comply with the provisions of NFPA 51A-2006 (“Standard for Acetylene...

2010-07-01

26

Acetylenic carbon allotrope  

DOEpatents

A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

Lagow, Richard J. (6204 Shadow Mountain Dr., Austin, TX 78731)

1998-01-01

27

Acetylenic carbon allotrope  

DOEpatents

A fourth allotrope of carbon, an acetylenic carbon allotrope, is described. The acetylenic carbon allotropes of the present invention are more soluble than the other known carbon allotropes in many common organic solvents and possesses other desirable characteristics, e.g. high electron density, ability to burn cleanly, and electrical conductive properties. Many uses for this fourth allotrope are described herein.

Lagow, Richard J. (6204 Shadow Mountain Dr., Austin, TX 78731)

1999-01-01

28

Effect of acetylene on nitrous oxide reduction and sulfide oxidation in batch and gradient cultures of Thiobacillus denitrificans.  

PubMed Central

Anaerobic enrichment cultures with H2S and N2O as substrates which were inoculated with a biofilm sample showed rapid growth and gas formation after 2 to 3 days at 27 degrees C. By using the deep-agar dilution technique, a pure culture was obtained. The strain was tentatively identified as Thiobacillus denitrificans. The isolate was used for batch and gradient culture studies under denitrifying conditions, oxidizing H2S with concomitant reduction of N2O to N2. In batch culture, oxidation of H2S was stepwise, with transient accumulation of elemental sulfur; the final oxidation product was SO4(2-). In gradient culture, there was no notable accumulation of elemental sulfur and microsensor measurements of H2S and N2O showed that H2S was oxidized directly to SO4(2-). In the presence of C2H2, however, oxidation of H2S stopped at the level of elemental sulfur and no SO4(2-) was produced in either batch or gradient cultures. This is a hitherto unknown inhibitory effect of C2H2. The inhibition is suggested to occur at the level of sulfite reductase, which catalyzes the oxidation of elemental sulfur to SO3(2-) in T. denitrificans. However, reduction of N2O in this strain was, surprisingly, not affected by C2H2. The isolate is the first chemolithoautotrophic organism shown to reduce N2O in the presence of C2H2. Denitrification in natural ecosystems is often quantified as N2O accumulation after C2H2 addition. However, the presence of large numbers of similar organisms with C2H2-insensitive N2O reduction could lead to underestimation of in situ rates. PMID:1352443

Dalsgaard, T; Bak, F

1992-01-01

29

Serum rotavirus neutralizing-antibody titers compared by plaque reduction and enzyme-linked immunosorbent assay-based neutralization assays.  

PubMed Central

Comparisons in rotavirus neutralizing-antibody responses were made with sera collected from vaccinated infants. The methods were a plaque reduction assay and a new enzyme-linked immunosorbent assay-based neutralization assay. Agreement of 94% was found in detecting at least fourfold seroresponses, and correlation coefficients between titers obtained by the two methods showed excellent agreement, indicating that either could be used reliably. PMID:8815124

Ward, R L; Kapikian, A Z; Goldberg, K M; Knowlton, D R; Watson, M W; Rappaport, R

1996-01-01

30

Evaluation of the Nitrogen-fixing Ability of Endophytic Clostridia based on Acetylene Reduction and Reverse Transcription-PCR Targeting the nifH Transcript and Ribosomal RNA  

Microsoft Academic Search

To examine whether plant-derived clostridia and their consortium fix nitrogen in plants, an inoculation system was developed using the grass Miscanthus sinensis under aseptic conditions. Among 13 clostridial strains previ- ously isolated from M. sinensis, Clostridium sp. strain Kas107-1 was selected as the best colonizer in the plant with the non-diazotrophic bacterium Entrobacter sp. strain B901-2. Nitrogen-fixing (acetylene-reducing) activity was

Asami Saito; Kiwamu Minamisawa

2006-01-01

31

Use of immunomagnetic reduction for C-reactive protein assay in clinical samples  

PubMed Central

Background: Magnetic nanoparticles biofunctionalized with antibodies are able to recognize and bind to the corresponding antigens. In this work, anti-C-reactive protein (CRP) antibody was covalently conjugated onto the surface of magnetic nanoparticles to label CRP specifically in serum. Methods: The level of serum CRP was detected by immunomagnetic reduction (IMR) assay, which identifies the changes in the magnetic signal representing the level of interaction between antibody-conjugated magnetic nanoparticles and CRP proteins. To investigate the feasibility of IMR for clinical application, pure CRP solutions and 40 human serum samples were tested for IMR detection of CRP to characterize sensitivity, specificity, and interference. Results: In comparison with the immunoturbidimetry assay, the results of the IMR assay indicated higher sensitivity and had a high correlation with those of the current immunoturbidimetry assay. Conclusion: We have developed a novel and promising way to assay CRP in human serum using immunomagnetic reduction in clinical diagnosis. PMID:22915855

Chang, Chien-Hsi; Lai, Zhi-Xian; Lin, Hsiu-Li; Yang, Che-Chuan; Chen, Hsin-Hsien; Yang, Shieh-Yueh; Horng, Herng-Er; Hong, Chin-Yih; Yang, Hong-Chang; Lin, Hsiu-Chen

2012-01-01

32

15. 9 micron acetylene laser  

Microsoft Academic Search

A laser system in which acetylene is mixed with a gaseous mixture of helium and carbon monoxide is described. The laser is vibrationally excited significantly populating the lower vibrational levels of the CO. The carbon monoxide will transfer its energy to the acetylene, populating the upper (01000) level to create laser radiation near 15.9 microns which may be operated in

T. J. Manuccia; J. A. Stregack; B. L. Wexler

1980-01-01

33

A modified MS2 bacteriophage plaque reduction assay for the rapid screening of antiviral plant extracts  

PubMed Central

Introduction: Traditional methods of screening plant extracts and purified components for antiviral activity require up to a week to perform, prompting the need to develop more rapid quantitative methods to measure the ability of plant based preparations to block viral replication. We describe an adaption of an MS2 plaque reduction assay for use in S. aureus. Results: MS2 bacteriophage was capable of infecting and replicating in B. cereus, S. aureus and F + E. coli but not F- E. coli. Indeed, both B. cereus and S. aureus were more sensitive to MS2 induced lysis than F+ E. coli. When MS2 bacteriophage was mixed with Camellia sinensis extract (1 mg/ml), Scaevola spinescens extract (1 mg/ml) or Aloe barbadensis juice and the mixtures inoculated into S. aureus, the formation of plaques was reduced to 8.9 ± 3.8%, 5.4 ± 2.4% and 72.7 ± 20.9% of the untreated MS2 control values respectively. Conclusions: The ability of the MS2 plaque reduction assay to detect antiviral activity in these known antiviral plant preparations indicates its suitability as an antiviral screening tool. An advantage of this assay compared with traditionally used cytopathic effect reduction assays and replicon based assays is the more rapid acquisition of results. Antiviral activity was detected within 24 h of the start of testing. The MS2 assay is also inexpensive and non-pathogenic to humans making it ideal for initial screening studies or as a simulant for pathogenic viruses. PMID:21808571

Cock, Ian; Kalt, F. R.

2010-01-01

34

Selective hydrogenation of unsaturated ketones and acetylene alcohols  

NASA Astrophysics Data System (ADS)

The data on selective hydrogenation of unsaturated ketones and acetylene alcohols are analysed. The requirements for choosing selective catalytic systems are surveyed. The routes for the reduction of oxygen-containing compounds and factors affecting them are considered. The bibliography includes 177 references.

Sul'man, Esfir'M.

1994-11-01

35

Experimental study on low-detection limit for immunomagnetic reduction assays by manipulating reagent entities.  

PubMed

The low limit of detection (LLD) plays an important role in biomolecular assays, especially for early-stage assays. Biomolecular detections usually involve the use of two main elements: a reagent and an analyzer, which both greatly contribute to the LLD. In this work, the relationships among the LLD and reagent-related factors are investigated. The to-be-detected biomolecule is c-reactive protein (CRP) as an example. The assay method is immunomagnetic reduction (IMR). The components of reagent are Fe(3)O(4) magnetic nanoparticles bio-functionalized with antibodies against CRP, dispersed in pH-7.4 phosphate buffered saline solution. Several key factors of the reagent, such as particle concentration, volume ratio of reagent to sample, and particle size, are manipulated to optimize the LLD of detecting CRP. PMID:23392387

Yang, S Y; Yang, C C; Horng, H E; Shih, B Y; Chieh, J J; Hong, C Y; Yang, H C

2013-06-01

36

Molecular Structure of Divinyl acetylene  

NSDL National Science Digital Library

In 1920, while doing research on acetylene, Dr. Nieuwland, Professor of Organic Chemistry at University of Notre Dame, found a yellowish oil in addition to the gas. The oil is identified as divinyl acetylene, which, when left alone, will thicken into a jelly and then into a hard resin which tends to explode when handled. It is a highly reactive and explosive chemical. It is sensitive to shocks, sparks, mechanical friction, heat or other accidental ignition. It is far more shock sensitive than primary explosives such as TNT. It is mainly used in manufacturing of synthetic rubber.

2002-10-09

37

Accidental death resulting from acetylene cylinder impact.  

PubMed

Acetylene is an inflammable gas commonly used for welding in small-scale industries. We present a case of a 34-year-old male welder who died following injuries sustained from explosion of an acetylene gas-welding cylinder. In this case report, we discuss the circumstances leading to the explosion of the welding cylinder, the autopsy findings, and a brief review of the literature on deaths resulting from blasts of acetylene cylinders. PMID:15894853

Rani, Mukta; Gupta, Avneesh; Dikshit, P C; Aggrawal, Anil; Setia, Puneet; Dhankar, Vijay

2005-06-01

38

Thermal Conversion of Methane to Acetylene  

SciTech Connect

This report describes the experimental demonstration of a process for the direct thermal conversion of methane to acetylene. The process utilizes a thermal plasma heat source to dissociation products react to form a mixture of acetylene and hydrogen. The use of a supersonic expansion of the hot gas is investigated as a method of rapidly cooling (quenching) the product stream to prevent further reaction or thermal decomposition of the acetylene which can lower the overall efficiency of the process.

Fincke, James Russell; Anderson, Raymond Paul; Hyde, Timothy Allen; Wright, Randy Ben; Bewley, Randy Lee; Haggard, Delon C; Swank, William David

2000-01-01

39

Comparative evaluation of microplate enzyme-linked immunosorbent assay versus plaque reduction assay for antiviral susceptibility testing of herpes simplex virus isolates.  

PubMed Central

We tested the antiviral susceptibilities of 30 clinical isolates of herpes simplex virus using the microplate in situ enzyme-linked immunosorbent assay (MISE) and the plaque reduction assay (PRA). There was concordance for 26 of 30 acyclovir results and all 30 foscarnet results. MISE and PRA results each predicted the response to acyclovir in 12 of 14 instances and the response to foscarnet in 8 instances. MISE is more rapid than PRA, has an objective endpoint, and correlates well with the clinical response to therapy. PMID:8849218

Safrin, S; Palacios, E; Leahy, B J

1996-01-01

40

Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure  

NASA Technical Reports Server (NTRS)

State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials

Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

2012-01-01

41

Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure  

NASA Technical Reports Server (NTRS)

State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials.

Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

2011-01-01

42

Reduction of misleading ("false") positive results in mammalian cell genotoxicity assays. I. Choice of cell type.  

PubMed

Current in vitro mammalian cell genotoxicity assays show a high rate of positive results, many of which are misleading when compared with in vivo genotoxicity or rodent carcinogenicity data. P53-deficiency in many of the rodent cell lines may be a key factor in this poor predictivity. As part of an European Cosmetics Industry Association initiative for improvement of in vitro mammalian cell assays, we have compared several rodent cell lines (V79, CHL, CHO) with p53-competent human peripheral blood lymphocytes (HuLy), TK6 human lymphoblastoid cells, and the human liver cell line, HepG2. We have compared in vitro micronucleus (MN) induction following treatment with 19 compounds that were accepted as producing misleading or "false" positive results in in vitro mammalian cell assays [6]. Of these, six chemicals (2-ethyl-1,3-hexandiol, benzyl alcohol, urea, sodium saccharin, sulfisoxazole and isobutyraldehyde) were not toxic and did not induce any MN at concentrations up to 10mM. d,l-Menthol and ethionamide induced cytotoxicity, but did not induce MN. o-Anthranilic acid was not toxic and did not induce MN in V79, CHL, CHO, HuLy and HepG2 cells up to 10mM. Toxicity was induced in TK6 cells, although there were no increases in MN frequency up to and above the 55% toxicity level. The other 10 chemicals (1,3-dihydroxybenzene, curcumin, propyl gallate, p-nitrophenol, ethyl acrylate, eugenol, tert-butylhydroquinone, 2,4-dichlorophenol, sodium xylene sulfonate and phthalic anhydride) produced cytotoxicity in at least one cell type, and were evaluated further for MN induction in most or all of the cell types listed above. All these chemicals induced MN at concentrations <10mM, with levels of cytotoxicity below 60% (measured as the replication index) in at least one cell type. The rodent cell lines (V79, CHO and CHL) were consistently more susceptible to cytotoxicity and MN induction than p53-competent cells, and are therefore more susceptible to giving misleading positive results. These data suggest that a reduction in the frequency of misleading positive results can be achieved by careful selection of the mammalian cell type for genotoxicity testing. PMID:22138618

Fowler, Paul; Smith, Katie; Young, Jamie; Jeffrey, Laura; Kirkland, David; Pfuhler, Stefan; Carmichael, Paul

2012-02-18

43

RAPID TETRAZOLIUM DYE REDUCTION ASSAY TO ASSESS THE BACTERICIDAL ACTIVITY OF OYSTER (CRASSOSTREA VIRGINICA) HEMOCYTES AGAINST VIBRIO PARAHAEMOLYTICUS  

EPA Science Inventory

An assay was developed to assess the ability of oyster, Crassostrea virginica, hemocytes to kill the human pathogenic bacterium, Vibrio parahaemolyticus (ATCC 17802). Bacterial killing was estimated colorimetrically by the enzymatic reduction of a tetrazolium dye, 3-(4,5-dimethyl...

44

Spectroscopic study of the acetylene species  

E-print Network

This thesis describes recent spectroscopic studies of acetylene and its HCCD isotopomer. Three different kinds of experiments have been performed: Laser-Induced Fluorescence (LIF), Dispersed Fluorescence (DF), and Stimulated ...

Duan, Zicheng, 1976-

2003-01-01

45

Acetylene-Terminated Aspartimides And Derived Resins  

NASA Technical Reports Server (NTRS)

New polymers and derived blends exhibit improved processability and properties. New toughened epoxies exhibit excellent properties, but use temperatures limited. Bismaleimide resins are some base materials formulated to develop materials having moderate use temperatures. Work conducted on use of acetylenic (ethynyl) group to cross-link and extend chains of oligomers and polymers to obtain materials to perform at higher temperatures. Extended to include acetylene-terminated aspartimides (ATA's).

Hergenrother, Paul M.; Connell, John W.; Havens, Stephen J.

1989-01-01

46

Acetylene fermentation: An Earth-based analog of biological carbon cycling on Titan  

NASA Astrophysics Data System (ADS)

Acetylene (C2H2) is present in part per million quantities in the atmosphere of Titan; conceivably as an intermediate product of methane photolysis. Currently, Earth’s atmosphere contains only trace amounts of C2H2 (~40 pptv), however higher concentrations likely prevailed during the Hadean and early Archean eons (4.5 - 3.5 Ga). We isolated C2H2-fermenting microbes from various aquatic and sedimentary environments. Acetylene fermentation proceeds via acetylene hydratase (AH) through acetaldehyde, which dismutates to ethanol and acetate, and if oxidants are present (e.g., sulfate) eventually to CO2. Thus, the remnants of a C2H2 cycle exists today on Earth but may also occur on Titan and/or Enceladus, both being planetary bodies hypothesized to have liquid water underlying their frozen surfaces. We developed a molecular method for AH by designing PCR primers to target the functional gene in Pelobacter acetylenicus. We used this method to scan new environments for the presence of AH and we employed DNA sequencing of the 16S rRNA gene in order to positively identify pelobacters in environmental samples. Acetylene fermentation was documented in five diverse salt-, fresh-, and ground-water sites. Pelobacter was identified as the genus responsible for acetylene fermentation in some, but not all, of these sites. Successful probing for AH preceded the discovery of acetylene consumption in a contaminated groundwater site, demonstrating the utility of functional gene probing. A pure culture of a C2H2-fermenting pelobacter was obtained from an intertidal mudflat. We also obtained an enrichment culture (co-cultured with a sulfate reducer) from freshwater lake sediments, but neither was pelobacter nor AH detected in this sample, suggesting that an alternative pathway may be involved here. Slurry experiments using these lake sediments either with or without added C2H2 or sulfate showed that sulfate reduction and acetylene fermentation were independent processes. In general, the ubiquity of acetylene fermentation as well as the presence of AH (an enzyme specific to acetylene) begs the questions; 1) why has this ability persisted on Earth for so long in the absence of significant atmospheric acetylene? 2) does C2H2-fermentation represent a possible means of sustaining growth in the anoxic, aqueous subsurface regions of Titan (and Enceladus)?

Miller, L. G.; Baesman, S. M.; Hoeft, S. E.; Kirshtein, J.; Wolf, K.; Voytek, M. A.; Oremland, R. S.

2009-12-01

47

Hydroponic Growth and the Nondestructive Assay for Dinitrogen Fixation 1  

PubMed Central

Hydroponic growth medium must be well buffered if it is to support sustained plant growth. Although 1.0 millimolar phosphate is commonly used as a buffer for hydroponic growth media, at that concentration it is generally toxic to a soybean plant that derives its nitrogen solely from dinitrogen fixation. On the other hand, we show that 1.0 to 2.0 millimolar 2-(N-morpholino)ethanesulfonic acid, pKa 6.1, has excellent buffering capacity, and it neither interferes with nor contributes nutritionally to soybean plant growth. Furthermore, it neither impedes nodulation nor the assay of dinitrogen fixation. Hence, soybean plants grown hydroponically on a medium supplemented with 1.0 to 2.0 millimolar 2-(N-morpholino)ethanesulfonic acid and 0.1 millimolar phosphate achieve an excellent rate of growth and, in the absence of added fixed nitrogen, attain a very high rate of dinitrogen fixation. Combining the concept of hydroponic growth and the sensitive acetylene reduction technique, we have devised a simple, rapid, reproducible assay procedure whereby the rate of dinitrogen fixation by individual plants can be measured throughout the lifetime of those plants. The rate of dinitrogen fixation as measured by the nondestructive acetylene reduction procedure is shown to be approximately equal to the rate of total plant nitrogen accumulation as measured by Kjeldahl analysis. Because of the simplicity of the procedure, one investigator can readily assay 50 plants individually per day. PMID:16662112

Imsande, John; Ralston, Edward J.

1981-01-01

48

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2012 CFR

...is: (i) Maximum methyl acetylene and propadiene molar ratio of 3 to 1; (ii) Maximum combined concentration of methyl...acetylene-propadiene mixture must have a refrigeration system without vapor compression or have a refrigeration system with the following...

2012-10-01

49

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2013 CFR

...is: (i) Maximum methyl acetylene and propadiene molar ratio of 3 to 1; (ii) Maximum combined concentration of methyl...acetylene-propadiene mixture must have a refrigeration system without vapor compression or have a refrigeration system with the following...

2013-10-01

50

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2014 CFR

...is: (i) Maximum methyl acetylene and propadiene molar ratio of 3 to 1; (ii) Maximum combined concentration of methyl...acetylene-propadiene mixture must have a refrigeration system without vapor compression or have a refrigeration system with the following...

2014-10-01

51

46 CFR 154.1735 - Methyl acetylene-propadiene mixture.  

Code of Federal Regulations, 2011 CFR

...is: (i) Maximum methyl acetylene and propadiene molar ratio of 3 to 1; (ii) Maximum combined concentration of methyl...acetylene-propadiene mixture must have a refrigeration system without vapor compression or have a refrigeration system with the following...

2011-10-01

52

Conversion of methane and acetylene into gasoline range hydrocarbons  

E-print Network

Conversion of methane and acetylene to higher molecular weight hydrocarbons over zeolite catalyst (HZSM-5) was studied The reaction between methane and acetylene successfully produced high molecular weight hydrocarbons, such as naphthalene, benzene...

Alkhawaldeh, Ammar

2012-06-07

53

Acetylene Fermentation: Relevance to Primordial Biogeochemistry and the Search for Life in the Outer Solar System  

NASA Astrophysics Data System (ADS)

Acetylene is a highly reactive component of planet(oid)s with anoxic, methane-rich atmospheres, such as Jupiter, Saturn, Titan, and perhaps the primordial Earth. Included in this group is Enceladus, although it is not clear if the acetylene detected within its jets by Cassini was formed by photolysis of methane, from thermo-catalysis of organic matter in the orb's interior, or a fragmentation artifact of the mass spectrum of a larger hydrocarbon. Acetylene inhibits many microbial processes (e.g., methanogenesis, methane oxidation, hydrogen metabolism, denitrification) yet a number of anaerobes can use it as a carbon and energy source to support growth. The best studied is Pelobacter acetylenicus, which carries out a two-step reaction involving the enzymes acetylene hydratase and acetaldehyde dismutase. The former, a low potential W-containing enzyme, forms acetaldehyde while the latter produces ethanol and acetate. Metabolism of acetylene by mixed microbial communities (sediments and/or enrichment cultures) produces these intermediates, and when coupled with sulfate-reduction or methanogenesis respectively forms CO2 or an equal mixtures of CO2 plus CH4. It is not inconceivable that such an anaerobic, microbial food chain could exist in the waters beneath the ice cap of Enceladus, Titan, or even in the mesothermal atmospheric regions of the gas giants. Detection of the identified intermediate products of acetylene fermentation, namely acetaldehyde, ethanol, acetate and formate in the atmospheres of these planet(oid)s would constitute evidence for a microbial life signature. This evidence would be strongly reinforced if a stable carbon isotope fractionation was identified as well, whereby the products of acetylene fermentation were enriched in 12C relative to 13C (i.e., had a lighter ?13C signal) when compared to that of the starting acetylene. The most practical target to test this hypothesis would be Enceladus (if the detected acetylene is shown to be a real presence in the jet vapors) owing to the relative ease of sample collection and analysis either in future flybys or lander/collector missions.

Oremland, R. S.; Baesman, S. M.; Miller, L. G.

2013-12-01

54

Vapor pressures of acetylene at low temperatures  

NASA Technical Reports Server (NTRS)

The atmospheres of many of the outer planets and their satellites contain a large number of hydrocarbon species. In particular, acetylene (C2H2) has been identified at Jupiter, Saturn and its satellite Titan, Uranus and Neptune. In the lower atmospheres of these planets, where colder temperatures prevail, the condensation and/or freezing of acetylene is probable. In order to obtain accurate models of the acetylene in these atmospheres, it is necessary to have a complete understanding of its vapor pressures at low temperatures. Vapor pressures at low temperatures for acetylene are being determined. The vapor pressures are measured with two different techniques in order to cover a wide range of temperatures and pressures. In the first, the acetylene is placed in a sample tube which is immersed in a low temperature solvent/liquid nitrogen slush bath whose temperature is measured with a thermocouple. The vapor pressure is then measured directly with a capacitance manometer. For lower pressures, a second technique which was called the thin-film infrared method (TFIR) was developed. It involves measuring the disappearance rate of a thin film of acetylene at a particular temperature. The spectra are then analyzed using previously determined extinction coefficient values, to determine the disappearance rate R (where R = delta n/delta t, the number of molecules that disappear per unit time). This can be related to the vapor pressure directly. This technique facilitates measurement of the lower temperatures and pressures. Both techniques have been calibrated using CO2, and have shown good agreement with the existing literature data.

Masterson, C. M.; Allen, John E., Jr.; Kraus, G. F.; Khanna, R. K.

1990-01-01

55

Detection of measles, mumps and rubella viruses by immuno-colorimetric assay and its application in focus reduction neutralization tests.  

PubMed

Measles, mumps and rubella are vaccine-preventable diseases; however limited epidemiological data are available from low-income or developing countries. Thus, it is important to investigate the transmission of these viruses in different geographical regions. In this context, a cell culture-based rapid and reliable immuno-colorimetric assay (ICA) was established and its utility studied. Twenty-three measles, six mumps and six rubella virus isolates and three vaccine strains were studied. Detection by ICA was compared with plaque and RT-PCR assays. In addition, ICA was used to detect viruses in throat swabs (n?=?24) collected from patients with suspected measles or mumps. Similarly, ICA was used in a focus reduction neutralization test (FRNT) and the results compared with those obtained by a commercial IgG enzyme immuno assay. Measles and mumps virus were detected 2 days post-infection in Vero or Vero-human signaling lymphocytic activation molecule cells, whereas rubella virus was detected 3 days post-infection in Vero cells. The blue stained viral foci were visible by the naked eye or through a magnifying glass. In conclusion, ICA was successfully used on 35 virus isolates, three vaccine strains and clinical specimens collected from suspected cases of measles and mumps. Furthermore, an application of ICA in a neutralization test (i.e., FRNT) was documented; this may be useful for sero-epidemiological, cross-neutralization and pre/post-vaccine studies. PMID:25244651

Vaidya, Sunil R; Kumbhar, Neelakshi S; Bhide, Vandana S

2014-12-01

56

Growth kinetics of Mycobacterium tuberculosis measured by quantitative resazurin reduction assay: a tool for fitness studies  

PubMed Central

We standardized a method to evaluate the growth kinetics of Mycobacterium tuberculosis by measuring quantitatively the reduction of resazurin by spectrophotometry. Growth curves and the rate of growth of twenty-one M. tuberculosis clinical isolates were determined. The method showed technical simplicity and is inexpensive to assess the fitness of each isolate. PMID:24031495

von Groll, Andrea; Martin, Anandi; Portaels, Françoise; da Silva, Pedro Eduardo Almeida; Palomino, Juan Carlos

2010-01-01

57

Hydration of Acetylene: A 125th Anniversary  

ERIC Educational Resources Information Center

The year 2006 is the 125th anniversary of a chemical reaction, the discovery of which by Mikhail Kucherov had a profound effect on the development of industrial chemistry in the 19-20th centuries. This was the hydration of alkynes catalyzed by mercury ions that made possible industrial production of acetaldehyde from acetylene. Historical…

Ponomarev, Dmitry A.; Shevchenko, Sergey M.

2007-01-01

58

Acetylenes and Other Constituents from Artemisia dracunculus.  

PubMed

The aerial parts of ARTEMISIA DRACUNCULUS afforded several known compounds as well as three new acetylenes, two phenylpropane derivatives, two monoterpenes, hex-3 Z-en-1-ol and vomifoliol A glucosides. The structures were elucidated by spectroscopic methods and a few chemical transformations. PMID:17226182

Jakupovic, J; Tan, R X; Bohlmann, F; Jia, Z J; Huneck, S

1991-10-01

59

New incubation device for in situ measurement of acetylene-reducing activity in ricefields  

Microsoft Academic Search

A device forin situ estimation of biological nitrogen fixation in shallow-water ricefields was developed using the acetylene-reducing assay.\\u000a The device consists of a rigid transparent bottomless plastic bottle provided with an agitation system. Laboratory experiments\\u000a using flooded pots inoculated withAnabaena UAM 202 indicated that agitation significantly reduced the time needed to detect the production of ethylene by eliminating\\u000a the slow

Antonio Quesada; Eva Sanchez Maeso; Eduardo Fernandez Valiente

1989-01-01

60

Oxygen transport through polyethylene terephthalate (PET) coated with plasma-polymerized acetylene at atmospheric pressure  

NASA Astrophysics Data System (ADS)

Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate.ootnotetextE.M. Moser, R. Urech, E. Hack, H. K"unzli, E. M"uller, Thin Solid Films, 317, 1998, pp. 388-392. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 ?m. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film.

Wemlinger, Erik; Pedrow, Patrick; Garcia-Pérez, Manuel; Sablani, Shyam

2011-11-01

61

A single medium for the isolation of acetylene-reducing (dinitrogen-fixing) bacteria from soils.  

PubMed

A single medium, containing standard basal salts and three common carbon sources (sucrose, mannitol, and sodium lactate) is proposed to replace nitrogen-free media in common use for isolating dinitrogen-fixing bacteria. Eight commonly isolated genera of dinitrogen-fixing bacterial exhibited growth on this combined carbon medium that equalled or bettered growth on other carbon-containing media. Combined carbon medium also yielded the highest counts of putative dinitrogen-fixing bacteria from three southern Alberta soils. A survey of the bacteria isolated aerobically from the Burdett soil on combined carbon agar indicated that, at higher dilutions, 75% of the isolates exhibited acetylene reduction. These bacteria were identified as Azospirillum spp., Bacillus polymyxa, B. macerans, Klebsiella pneumoniae, Erwinia herbicola, and Enterobacter cloacae. The inclusion of yeast extract in combined carbon medium is considered essential to supply organic growth factors and may supply "starter" nitrogen that promotes growth without inhibiting acetylene reduction. PMID:7214234

Rennie, R J

1981-01-01

62

49 CFR 173.303 - Charging of cylinders with compressed gas in solution (acetylene).  

Code of Federal Regulations, 2010 CFR

...Charging of cylinders with compressed gas in solution (acetylene...FOR SHIPMENTS AND PACKAGINGS Gases; Preparation and Packaging...of cylinders with compressed gas in solution (acetylene...Specification 8 and 8AL). Acetylene gas must be shipped in...

2010-10-01

63

Spectroscopic study of acetylene and hydrogen cyanide  

NASA Astrophysics Data System (ADS)

High-resolution molecular spectroscopy has been used to study acetylene line parameters and emission spectra of hydrogen cyanide. All acetylene spectra were recorded in our laboratory at the University of Lethbridge using a 3-channel tuneable diode laser spectrometer. N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the v1+v3 band of acetylene at seven temperatures in the range 213-333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. The line-broadening and line-shift coefficients as well as their temperature-dependent parameters have been also evaluated theoretically, in the frame work of a semi-classical approach based on an exponential representation of the scattering operator, an intermolecular potential composed of electrostatic quadrupole--quadrupole and pairwise atom--atom interactions as well as on exact trajectories driven by an effective isotropic potential. The experimental results for both N2-broadening and shifting show good agreement with the theoretical results. We have studied the line intensities of the 1vl 20?0v120 band system from the HCN emission spectrum. The infrared emission spectrum of H12C 14N was measured at the Justus-Liebig University, Giessen, Germany. The emission spectrum was analyzed with the spectrum analysis software Symath running using Mathematica as a platform. This approach allowed us to retrieve information on band intensity parameters.

Rozario, Hoimonti Immaculata

64

PERKINSUS-"CIDAL" ACTIVITY OF OYSTER HEMOCYTES USING A TETRAZOLIUM DYE REDUCTION ASSAY: OPTIMIZATION AND APPLICATIONS  

EPA Science Inventory

A bactericidal assay developed to assess the ability of oyster (Crassostrea virginica) hemocytes to kill the human pathogen Vibrio parahaemolyticus was optimized to estimate killing of the oyster parasite Perkinsus marinus. Assay variables, temperature, hemocyte:parasite ratio, i...

65

The noncellular reduction of MTT tetrazolium salt by TiO? nanoparticles and its implications for cytotoxicity assays.  

PubMed

We report results of noncellular tests, revealing the occurrence of photocatalytic interactions between titanium dioxide (TiO2, titania) nanoparticles and the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide] cytotoxicity indicator. These interactions induce the reduction of MTT and formation of purple formazan under biologically relevant conditions. Classical MTT assays have been performed to evaluate the production of formazan in DMEM-F12 and RPMI-1640 cell culture media (containing 10% fetal bovine serum-FBS) treated with Degussa-P25 TiO2 nanoparticles, in the absence of cells. The colorimetric determinations revealed the noncellular MTT to formazan transformation induced by TiO2 nanoparticles, under conditions commonly used for in vitro cytotoxicity testing of nanomaterials. The formazan precipitation was found to be proportional to the TiO2 concentration, being enhanced under laboratory daylight exposure. The photocatalytic nature of the studied effect was assessed under UV irradiation at 365nm. The biological significance of the reported reaction was established with respect to cellular reference experiments performed on V79-4, HeLa and B16 cell lines. The results show false viability increases with up to 14% (for TiO2 concentrations generally higher than 50?g/ml), induced by the TiO2-MTT reaction. This type of artifacts may lead to underestimated toxicity or false proliferation results. PMID:23531555

Lupu, A R; Popescu, T

2013-08-01

66

Infrared spectroscopy of acetylene by Dr. G. Bradley Armen  

E-print Network

Infrared spectroscopy of acetylene by Dr. G. Bradley Armen Department of Physics and Astronomy 401 at the quantum level. In this laboratory we will study the infrared (IR) absorption of acetylene molecules this, we'll make use of an interesting and important laboratory tool: the Fourier transform infrared

Dai, Pengcheng

67

Acetylene-Based Materials in Organic Photovoltaics  

PubMed Central

Fossil fuel alternatives, such as solar energy, are moving to the forefront in a variety of research fields. Organic photovoltaic systems hold the promise of a lightweight, flexible, cost-effective solar energy conversion platform, which could benefit from simple solution-processing of the active layer. The discovery of semiconductive polyacetylene by Heeger et al. in the late 1970s was a milestone towards the use of organic materials in electronics; the development of efficient protocols for the palladium catalyzed alkynylation reactions and the new conception of steric and conformational advantages of acetylenes have been recently focused the attention on conjugated triple-bond containing systems as a promising class of semiconductors for OPVs applications. We review here the most important and representative (poly)arylacetylenes that have been used in the field. A general introduction to (poly)arylacetylenes, and the most common synthetic approaches directed toward making these materials will be firstly given. After a brief discussion on working principles and critical parameters of OPVs, we will focus on molecular arylacetylenes, (co)polymers containing triple bonds, and metallopolyyne polymers as p-type semiconductor materials. The last section will deal with hybrids in which oligomeric/polymeric structures incorporating acetylenic linkages such as phenylene ethynylenes have been attached onto C60, and their use as the active materials in photovoltaic devices. PMID:20480031

Silvestri, Fabio; Marrocchi, Assunta

2010-01-01

68

Evaluation of anthelmintic activity in captive wild ruminants by fecal egg reduction tests and a larval development assay.  

PubMed

The effectiveness of anthelmintics was evaluated in four herds of captive ruminants, wapiti (Cervus elaphus), Armenian red sheep (Ovis orientalis), giraffe (Giraffa camelopardalis), and pronghorn (Antilocapra americana), by the use of fecal egg reduction tests (FERTs) and a commercial larval development assay (LDA) designed to evaluate susceptibility or resistance of nematodes to anthelmintics. Haemonchus sp. was the predominant nematode in the red sheep, giraffe, and pronghorn herds, whereas Ostertagia sp. and Trichostrongylus sp. were predominant in the wapiti. The LDA data indicated susceptibility by the worms to benzimidazoles except in the red sheep flock, which showed a high level of resistance. High levels of resistance to levamisole were seen in the worm populations from the wapiti and red sheep, moderate resistance in the pronghorn herd, and susceptibility in the giraffe herd. Worms were susceptible in all four herds to a combination of benzimidazole/levamisole. There was suspected avermectin resistance by Trichostrongylus sp. in the wapiti herd and by Haemonchus sp. in the giraffe. The FERTs agreed with the LDA in showing the Haemonchus in the giraffe was susceptible to fenbendazole and had suspected resistance to ivermectin, whereas Haemonchus in the red sheep and pronghorn were susceptible to ivermectin. There was correlation between the tests evaluating anthelmintics. The LDA is useful as a screening test in the selection of an anthelmintic for use in grazing ruminants, but the effectiveness of a drug in a host species may depend as much on the dose used, and the method of administration, as it does on the parasite's sensitivity to the anthelmintic. PMID:11237142

Young, K E; Jensen, J M; Craig, T M

2000-09-01

69

Reduction of the diagnostic window with a new combined p24 antigen and human immunodeficiency virus antibody screening assay  

Microsoft Academic Search

In order to reduce the window phase between time of human immunodeficiency virus (HIV) infection and laboratory diagnosis, new fourth generation screening assays which permit a simultaneous detection of HIV antigen and antibody have been developed. In a multicenter study, a new automated fourth generation assay, Enzymun-Test® HIV Combi (Boehringer Mannheim GmbH) was compared to third generation assay, p24 antigen

Lutz Gürtler; Annelies Mühlbacher; Ulrike Michl; Hanns Hofmann; G Giancarlo Paggi; Vincenzo Bossi; Rigmor Thorstensson; Roberto G.-Villaescusa; Adolfo Eiras; JoseManuel Hernandez; Walter Melchior; Frédéric Donie; Bernard Weber

1998-01-01

70

Double Resonance Studies of Electronically Excited Acetylene.  

NASA Astrophysics Data System (ADS)

The double resonance techniques of Ultraviolet ^{-}Ultraviolet Double Resonance (UVUVDR), Ultraviolet-Optical Double Resonance (UVODR), and Stimulated Emission Pumping (SEP) have been used to investigate electronically excited states of acetylene. Electronically excited states of acetylene have stable structures in the linear (D_{infty h}), cis-bent (C_sp{2v}{b}) , trans-bent (C_sp{2h} {c}), vinylidene (C_sp {2v}{a}), and nonplanar (C _sp{2}{b} and C _sp{2}{c}) configurations, all of which might appear in the spectrum. The Complete Nuclear Permutation Inversion-Molecular Symmetry (CNPI -MS) group theoretical treatment was utilized (Chapter 2) to provide a consistent and point group independent framework with which to classify the overall rovibronic wavefunctions connected with these different structures. Knowing the unique patterns of rotational energy levels presented by the different isomeric structures of acetylene is instrumental in determining the electronic symmetry and molecular structure of the states appearing in the spectrum. Although the excited states in the 60,000-78,000 cm^{-1} energy region are strongly predissociated, the UVUVDR and UVODR double resonance techniques permit the recording the rotationally resolved spectra. The rotationally resolved spectra allow the complete characterization of these states, which in a one-photon absorption spectrum can only be classified as diffuse. The most important result of these double resonance studies is the structural and electronic symmetry characterization of two predissociated electronic states (Chapters 3 and 4), most notably the nonplanar ~ E -state. Confirmation of this nonplanar gauche structure relies heavily on the observation of an unprecedented K_{a} dependent pattern of rotational selection rules. The rotational energy level pattern exhibited by the ~ E -state is consistent with that expected (Chapter 2) for a nonplanar near cis-bent (C_sp{2} {b}) state of ^1 A electronic symmetry. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).

Lundberg, James Kenneth

1992-01-01

71

Plant pathology Effect of nitrate on acetylene reduction  

E-print Network

of nitrogen and carbon metabolism, involved in nitrogen fixation in the root nodules of soybean G Alcantar 138 of B japonicum CB 1809 was a good tool for investigating the effects associated with N2 fixation metabolism re- spectively, in symbiotic nodules. On the other hand, parallelism of nodule cytosol nitrate

Paris-Sud XI, Université de

72

Aromatic acetylenes for carbon matrix composite material  

SciTech Connect

Carbon composite materials are being used increasingly in aerospace structures because of the high strength to weight ratio of such materials. Acetylenic substituted aromatic compounds, which have low melting points, can be easily processed, lose little weight during their curing, and do not need multiple impregnations to achieve high density, are good candidates as carbon precursor materials. In this laboratory, the compound 1,2,4,5-tetrakis(phenylethynyl)benzene 1 was prepared by the palladium catalyzed reaction of phenylacetylene with 1,2,4,5-tetrabromobenzene in the presence of excess amine base. Laboratory studies have shown that 1 melts at 195{degrees}C and forms a thermosetting material with high thermal and oxidative stability and a high char yield upon pyrolysis under nitrogen. Changes which occurred upon pyrolysis in air were studied by infrared spectroscopy. The monomer 1 is a crystalline solid that is stable indefinitely at room temperature.

Jones, K.M.; Keller, T.M. [Naval Research Lab., Washington, DC (United States)

1993-12-31

73

High pressure chemistry of substituted acetylenes  

SciTech Connect

High pressure in situ synchrotron x-ray diffraction experiments were performed on substituted polyacetylenes: tert-butyl acetylene [TBA: (CH{sub 3}){sub 3}-C{triple_bond}CH] and ethynyl trimethylsilane [ETMS: (CH{sub 3}){sub 3}-Si{triple_bond}CH] to investigate pressure-induced chemical reactions. The starting samples were the low temperature crystalline phases which persisted metastably at room temperature and polymerized beyond 11 GPa and 26 GPa for TBA and ETMS respectively. These reaction onset pressures are considerably higher than what we observed in the shockwave studies (6.1 GPa for TBA and 6.6 GPa for ETMS). Interestingly, in the case of ETMS, it was observed with fluid ETMS as starting sample, reacts to form a semi-crystalline polymer (crystalline domains corresponding to the low-T phase) at pressures less than {approx}2 GPa. Further characterization using vibrational spectroscopy is in progress.

Chellappa, Raja [Los Alamos National Laboratory; Dattelbaum, Dana [Los Alamos National Laboratory; Sheffield, Stephen [Los Alamos National Laboratory; Robbins, David [Los Alamos National Laboratory

2011-01-25

74

A biogeochemical and genetic survey of acetylene fermentation by environmental samples and bacterial isolates  

USGS Publications Warehouse

Anoxic samples (sediment and groundwater) from 13 chemically diverse field sites were assayed for their ability to consume acetylene (C2H2). Over incubation periods ranging from ˜ 10 to 80 days, selected samples from 7 of the 13 tested sites displayed significant C2H2 removal. No significant formation of ethylene was noted in these incubations; therefore, C2H2 consumption could be attributed to acetylene hydratase (AH) rather than nitrogenase activity. This putative AH (PAH) activity was observed in only 21% of the total of assayed samples, while amplification of AH genes from extracted DNA using degenerate primers derived from Pelobacter acetylenicus occurred in even fewer (9.8%) samples. Acetylene-fermenting bacteria were isolated as a pure culture from the sediments of a tidal mudflat in San Francisco Bay (SFB93) and as an enrichment culture from freshwater Searsville Lake (SV7). Comparison of 16S rDNA clone libraries revealed that SFB93 was closely related to P. carbolinicus, while SV7 consisted of several unrelated bacteria. AH gene was amplified from SFB93 but not SV7. The inability of the primers to generate amplicons in the SV7 enrichment, as well as from several of the environmental samples that displayed PAH activity, implied that either the primers were too highly constrained in their specificity or that there was a different type of AH gene in these environmental samples than occurs in P. acetylenicus. The significance of this work with regard to the search for life in the outer Solar System, where C2HL2 is abundant, is discussed.

Miller, Laurence G.; Baesman, Shaun M.; Kirshtein, Julie; Voytek, Mary A.; Oremland, Ronald S.

2013-01-01

75

76 FR 75840 - Revising Standards Referenced in the Acetylene Standard  

Federal Register 2010, 2011, 2012, 2013, 2014

...risk of material harm exists in the workplace and the standard would substantially...protect their employees from the hazards found in workplaces engaged in acetylene operations. Therefore...proposed, OSHA will encourage the State Plan States to...

2011-12-05

76

76 FR 75782 - Revising Standards Referenced in the Acetylene Standard  

Federal Register 2010, 2011, 2012, 2013, 2014

...risk of material harm exists in the workplace and the standard would substantially...protect their employees from the hazards found in workplaces engaged in acetylene operations. Therefore, OSHA encourages the State Plan States to...

2011-12-05

77

Tropospheric and lower stratospheric vertical profiles of ethane and acetylene  

NASA Technical Reports Server (NTRS)

The first known vertical distributions of ethane and acetylene which extend into the lower stratosphere are reported. The average upper tropospheric concentrations, between 20,000 ft and 35,000 ft, near 37 deg N-123 deg W were 1.2 micrograms/cu m (1.0 ppb) for ethane and 0.24 micrograms /cu m (0.23 ppb) for acetylene while the values near 9 N-80 W were 0.95 micrograms/cu m (0.77 ppb) and 0.09 micrograms/cu m (0.09 ppb), respectively. Detectable quantities of both ethane and acetylene are present in the lower stratosphere. There is a sharp decrease in the levels of these two compounds as one crosses the tropopause and ascends into the lower stratosphere. The observed levels of ethane and acetylene may allow some impact on the background chemistry of the troposphere and stratosphere.

Cronn, D.; Robinson, E.

1979-01-01

78

On the ionic states of vinylidene and acetylene  

NASA Astrophysics Data System (ADS)

Electronic states of C 2H +2 cation (with acetylenic and vinylidenic structure) are investigated by ab initio SCF and PNO CEPA calculations. The lowest excited state of the acetylene cation is calculated to be 4A 2 in a strongly bent cis conformation, and a qualitative explanation is given for the lack of detectable emission from theà 2? g+ state. Only the radical anion with the vinylidenic structure is bound.

Rosmus, P.; Botchwina, P.; Maier, J. P.

1981-11-01

79

Acetylene structure and dynamics on Pd(111)  

SciTech Connect

Acetylene molecules adsorbed onto a Pd(111) crystal surface were imaged by scanning tunneling microscopy (STM) below 70 K. Single C{sub 2}H{sub 2} molecules appeared as a combination of a protrusion and a depression 3.5 {Angstrom} apart. This peculiar shape is due to the molecular {pi} orbital, which is oriented at a shallow angle out of the surface. Six orientations of the molecule with respect to the substrate were observed, indicating two different threefold hollow binding sites each with three possible rotational states. At 44 K, thermally activated rotation of the molecules between the three equivalent states on the same threefold hollow site occurs on the time scale of seconds. Diffusion of molecules between adjacent threefold sites began at {approximately}70K. The findings agree with the structure of the adsorption site determined by total-energy calculations and with the STM image calculated using the electron scattering quantum chemistry method. {copyright} {ital 1998} {ital The American Physical Society}

Dunphy, J.C.; Rose, M.; Behler, S.; Ogletree, D.F.; Salmeron, M. [Lawrence Berkeley National Laboratory, Materials Sciences Division, University of California, Berkeley, California 94720 (United States)] [Lawrence Berkeley National Laboratory, Materials Sciences Division, University of California, Berkeley, California 94720 (United States); Sautet, P. [Laboratoire de Chimie Theorique, ENS, 69364Lyon (France)] [Laboratoire de Chimie Theorique, ENS, 69364Lyon (France); [Institut de Recherches sur la Catalyse, CNRS, 69626Villeurbanne (France)

1998-05-01

80

Ion-induced dissociation dynamics of acetylene  

NASA Astrophysics Data System (ADS)

We report on the results of dissociation dynamics of multiple charged acetylene molecules formed in collision with 1.2 MeV Ar8+ projectiles. Using the coincidence map, we can separate out the different dissociation pathways between carbon and hydrogen ionic fragments as well as complete two-body breakup events. From the measured slopes of the coincidence islands for carbon atomic fragments and theoretical values determined from the charge and momentum distribution of the correlated particles, we observe a diatomlike behavior of the C-C charged complex during dissociation of multiply charged C2H2 . We conclude that this behavior in breakup dynamics is a signature of sequentiality in dissociation of this multiply charged molecular species. The shape and orientation of the islands give further information about the momentum balance in the fragmentation process of two- or many-body dissociation pathways. Kinetic energy release of different breakup channels are reported here and compared with values calculated from the pure Coulomb explosion model.

de, Sankar; Rajput, Jyoti; Roy, A.; Ghosh, P. N.; Safvan, C. P.

2008-02-01

81

Electron impact induced anion production in acetylene.  

PubMed

A detailed experimental investigation of electron induced anion production in acetylene, C2H2, in the energy range between 1 and 90 eV is presented. The anions are formed by two processes in this energy range: dissociative electron attachment (DEA) and dipolar dissociation (DD). DEA in C2H2 is found to lead to the formation of H(-) and C2(-)/C2H(-) through excitation of resonances in the electron energy range 1-15 eV. These anionic fragments are formed with super thermal kinetic energy and reveal no anisotropy in the angular distributions. DD in C2H2 leads to the formation of H(-), C(-)/CH(-) and C2(-)/C2H(-) with threshold energies of 15.7, 20.0 and 16.5 eV respectively. The measured anion yields have been used to calculate anion production rates for H(-), C(-)/CH(-) and C2(-)/C2H(-) in Titan's ionosphere. PMID:24343432

Szyma?ska, Ewelina; ?adež, Iztok; Krishnakumar, E; Mason, Nigel J

2014-02-28

82

Ethane and acetylene abundances in the Jovian atmosphere  

NASA Technical Reports Server (NTRS)

The paper reports spectra of Jupiter in the spectral region from 755 to 850 kaysers, which covers the nu-9 fundamental of ethane and contains lines from the R branch of the nu-5 fundamental of acetylene. The monochromatic absorption coefficient of the central Q branch of the nu-9 fundamental of ethane, which was determined in the laboratory, is applied in a radiative-transfer calculation to evaluate the ethane mixing ratio in the Jovian atmosphere; the present data are also used to place an upper limit on the acetylene mixing ratio. For the radiative-transfer calculation, emission intensity is computed for the region above the 0.02-atm level assuming both an isothermal inversion layer and a previously reported temperature profile. The resulting maximum mixing ratios consistent with the observations are 0.00003 for ethane and 7.5 by 10 to the -8th power for acetylene.

Tokunaga, A.; Knacke, R. F.; Owen, T.

1976-01-01

83

Microgravity Superagglomerates Produced By Silane And Acetylene  

NASA Technical Reports Server (NTRS)

The size of the agglomerates produced in the upper portion of a flame is important for a variety of applications. Soot particle size and density effect the amount of radiative heat transfer from a fire to its surroundings. Particle size determines the lifetime of smoke in a building or in the atmosphere, and exposure hazard for smoke inhaled and deposited in the lungs. The visibility through a smoke layer and dectectability of the smoke are also greatly affected by agglomerate size. Currently there is limited understanding of soot growth with an overall dimension of 10 m and larger. In the case of polystyrene, smoke agglomerates in excess of 1 mm have been observed raining out from large fires. Unlike hydrocarbon fuels, silane has the advantage that silica particles are the major combustion product resulting in a particle volume fraction a factor of ten greater than that for a carbonaceous smoke. There are two very desirable properties of silica aero-gels that are important for both space and earth based applications. The first important property is its inertness to most oxidizing and reducing atmospheres. Therefore, silica aero-gels make excellent fire ablatives and can be used in very demanding applications. The second important property is that silica aero-gels are expected to have very high porosity (greater than 0.999), making them lightweight and ideal for aerospace applications. The added benefit of the high porosity is that they can be used as extremely efficient filters for many earth based applications as well. Evidence of the formation of superagglomerates in a laminar acetylene/air diffusion flame was found by Sorensen et al. [1]. An interconnecting web of super-agglomerates was observed to span the width of the soot plume in the region just above the flame tip and described as a gel state. It was observed that this gel state immediately breaks up into agglomerates as larges as 100 m due to buoyancy induced turbulence. Large soot agglomerates were observed in microgravity butane jet diffusion flames by Ito et al.[2]. Several other works to date have studied the effect of flame structure on soot volume fraction and agglomeration size in a microgravity environment.[3-4]. In microgravity the absence of buoyant convective flows increases the residence time in the flame and causes a broadening of the high temperature region in the flame. Both of these factors play a significant role in gas phase radiation and soot formation

Gokoglu, Suleyman (Technical Monitor); Bundy, Matthew; Mulholland, George W.; Manzello, Samuel; Yang, Jiann; Scott, John Henry; Sivathanu, Yudaya

2003-01-01

84

Strong-Field Dissociative Double Ionization of Acetylene  

NASA Astrophysics Data System (ADS)

We investigate dissociative double ionization of acetylene, one of the smallest organic molecules yet with a rich electronic structure, in strong laser fields by measuring two fragment ions and two electrons in coincidence. The two-body fragmentation channels are dominated by the removal of electrons from the lower-lying molecular orbitals rather than from the highest occupied one. The electron localization-assisted enhanced ionization mechanism plays a central role for the strong-field deprotonation ionization of acetylene by releasing the second electron from the up-field potential well of the hydrogen site at the internuclear distance near twice the equilibrium value of the C-H bond.

Gong, Xiaochun; Song, Qiying; Ji, Qinying; Pan, Haifeng; Ding, Jingxin; Wu, Jian; Zeng, Heping

2014-06-01

85

Siloxane containing addition polyimides. II - Acetylene terminated polyimides  

NASA Technical Reports Server (NTRS)

Acetylene terminated polyimide oligomers having a range of molecular weights have been synthesized by reacting bis (gamma-aminopropyl) tetramethyldisiloxane, aminophenylacetylene and 3, 3', 4, 4' benzophenonetetracarboxylic dianhydride in different molar ratios. The prepolymers were isolated and characterized for melt flow and cure properties. They show promise as adhesives for bonding titanium to titanium and as matrix resins for graphite cloth reinforced composites. The most promising system has been blended in varying proportions with Thermid 600, a commercially available acetylene terminated polyimide oligomer, and the mixtures have been tested for application as composite matrix resins.

Maudgal, S.; St. Clair, T. L.

1984-01-01

86

Acetylene absorption and binding in nonporous crystal lattice  

SciTech Connect

Unusual storage: An organic nonporous material, p-tert-butylcalix[4]arene, sorbs acetylene with high storage density under ambient conditions. It is presumed that gas molecules diffuse through the seemingly nonporous lattice without disrupting the arrangement of the host molecules (see picture; red O, blue C, gray H, yellow void space).

Thallapally, Praveen K.; Dobrzanska, Liliana B.; Gingrich, Todd R.; Wirsig, Trevor B.; Barbour, Leonard J.; Atwood, Jerry L.

2006-09-01

87

Interstitial pneumonitis after acetylene welding: a case report.  

PubMed

Acetylene is a colorless gas commonly used for welding. It acts mainly as a simple asphyxiant. In this paper, however, we present a patient who developed a severe interstitial pneumonitis after acetylene exposure during aluminum welding. A 44-year old man was welding with acetylene, argon and aluminum electrode sticks in a non-ventilated aluminum tank for 2 h. Four hours after welding dyspnea appeared and 22 h later he was admitted at the Emergency Department due to severe respiratory insufficiency with pO2 = 6.7 kPa. Chest X-ray showed diffuse interstitial infiltration. Pulmonary function and gas diffusion tests revealed a severe restriction (55% of predictive volume) and impaired diffusion capacity (47% of predicted capacity). Toxic interstitial pneumonitis was diagnosed and high-dose systemic corticosteroid methylprednisolone and inhalatory corticosteroid fluticasone therapy was started. Computed Tomography (CT) of the lungs showed a diffuse patchy ground-glass opacity with no signs of small airway disease associated with interstitial pneumonitis. Corticosteroid therapy was continued for the next 8 weeks gradually reducing the doses. The patient's follow-up did not show any deterioration of respiratory function. In conclusion, acetylene welding might result in severe toxic interstitial pneumonitis that improves after an early systemic and inhalatory corticosteroid therapy. PMID:24658888

Brvar, Miran

2014-01-01

88

The vibrational energy pattern acetylene ''VI...: Inter and intrapolyad structures  

E-print Network

The vibrational energy pattern acetylene ''VI...: Inter­ and intrapolyad structures B. I. Zhilinski March 2000; accepted August 2000# Intra­ interpolyad structures are investigated vibrational energy of vibrational energy levels. Distinct regular oscillatory contributions evidenced number vibrational levels main

Zhilinskií, Boris

89

A gasdynamic laser using products of acetylene explosions  

Microsoft Academic Search

A combustion pulse explosive gasdynamic laser (GDL) has been used to investigate the characteristics of acetylene-air fuel combustion products flow. The 2-liter GDL spherical explosion chamber was connected to the nozzle grid by a flat widening adapter. The chamber and adapter volumes were separated with a copper diaphragm. The explosion products escaped through the nozzle grid to the evacuated 200-liter

A. B. Britan; A. N. Khmelevskii; V. A. Levin; S. A. Losev; V. V. Lugovskoi; G. D. Smekhov; A. M. Starik

1983-01-01

90

Nongenotoxic effects and a reduction of the DXR-induced genotoxic effects of Helianthus annuus Linné (sunflower) seeds revealed by micronucleus assays in mouse bone marrow  

PubMed Central

Background This research evaluated the genotoxicity of oil and tincture of H. annuus L. seeds using the micronucleus assay in bone marrow of mice. The interaction between these preparations and the genotoxic effects of doxorubicin (DXR) was also analysed (antigenotoxicity test). Methods Experimental groups were evaluated at 24-48 h post treatment with N-Nitroso-N-ethylurea (positive control – NEU), DXR (chemotherapeutic), NaCl (negative control), a sunflower tincture (THALS) and two sources of sunflower oils (POHALS and FOHALS). Antigenotoxic assays were carried out using the sunflower tincture and oils separately and in combination with NUE or DXR. Results For THALS, analysis of the MNPCEs showed no significant differences between treatment doses (250–2,000 mg.Kg-1) and NaCl. A significant reduction in MNPCE was observed when THALS (2,000 mg.Kg-1) was administered in combination with DXR (5 mg.Kg-1). For POHALS or FOHALS, analysis of the MNPCEs also showed no significant differences between treatment doses (250–2,000 mg.Kg-1) and NaCl. However, the combination DXR?+?POHALS (2,000 mg.Kg-1) or DXR?+?FOHALS (2,000 mg.Kg-1) not contributed to the MNPCEs reduction. Conclusions This research suggests absence of genotoxicity of THALS, dose-, time- and sex-independent, and its combination with DXR can reduce the genotoxic effects of DXR. POHALS and FOHALS also showed absence of genotoxicity, but their association with DXR showed no antigenotoxic effects. PMID:24694203

2014-01-01

91

Production of extracellular superoxide by human lymphoblast cell lines: comparison of electron spin resonance techniques and cytochrome C reduction assay.  

PubMed

Superoxide production by NADPH oxidases plays an important role in the development and progression of cardiovascular disease (CVD). However, measurement of superoxide (O(2)(-)), a marker of oxidative stress, remains a challenging task in clinical and translational studies. In this study we analyzed O(2)(-) production in cultured human lymphoblast cell lines by three different methods: (a) superoxide dismutase (SOD)-inhibitable cytochrome C reduction, (b) spin trapping of superoxide with 5-(ethoxycarbonyl)-5-methyl-1-pyrroline N-oxide (EMPO) and 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO), and (c) using electron spin resonance (ESR) with the cell-permeable spin probe 1-hydroxy-3-methoxycarbonyl-2,2,5,5-tetramethylpyrrolidine (CMH). Lymphocytes were isolated and immortalized by an Epstein-Barr Virus (EBV)-transformation procedure. Superoxide was measured in cultured lymphoblast cell lines at baseline and upon stimulation with phorbol 12-myristate 13-acetate (PMA). Cytochrome C and the spin traps EMPO and DEPMPO detected two to five times less superoxide compared to CMH. Thus, CMH provided the most quantitative measurement of superoxide generation in human lymphoblast cell lines. Superoxide detection with CMH was linear dependent on cell concentration and was inhibited by SOD but not by catalase. Both cell-permeable polyethylene glycol (PEG)-SOD and extracellular Cu,Zn-SOD inhibited O(2)(-) detection by 90% in PMA-stimulated cells, suggesting a predominantly extracellular O(2)(-) generation in human lymphoblasts. Our study describes a new technique for O(2)(-) measurement in cultured human lymphoblasts using ESR and CMH. A highly sensitive in vitro measurement of O(2)(-) in human cell lines would allow investigators to study genotype/phenotype interactions in translational studies. PMID:17222393

Dikalov, Sergey I; Li, Wei; Mehranpour, Payam; Wang, Shaoshan S; Zafari, A Maziar

2007-04-01

92

Acetylene bubble-powered autonomous capsules: towards in situ fuel.  

PubMed

A fuel-free autonomous self-propelled motor is illustrated. The motor is powered by the chemistry of calcium carbide and utilising water as a co-reactant, through a polymer encapsulation strategy. Expulsion of acetylene bubbles powers the capsule motor. This is an important step, going beyond the toxic hydrogen peroxide fuel used normally, to find alternative propellants for self-propelled machines. PMID:25347401

Moo, James Guo Sheng; Wang, Hong; Pumera, Martin

2014-12-28

93

[Tunable fiber laser based photoacoustic spectroscopy for acetylene detection].  

PubMed

An acetylene detection system has been constructed with a tunable erbium-doped fiber laser (TEDFL) based photoacoustic spectrometer. Combining wavelength modulation and second harmonic signal detection technique, the system is able to effectively eliminate the background noise generated by absorption of the cell windows and the wall of the acoustic resonator. The system was applied to low concentration acetylene flowing measurement, through optimizing the systemic optics, acoustics and electron detection technique condition. The experimental results show that the second harmonic amplitude is directly proportional to gas concentration. Their linear pertinence coefficient is 0.999 53. The system sensitivity limit for acetylene detection is 0.3 ppm under atmosphere pressure with 100 ms time constant and 3. 5 mW average optical power. The TEDFL was used as light source in stead of the DFB diode laser which is relatively costly. The system appears promising as a basis for developing cheap, practical, portable spectroscopy instruments for trace gas detection. The detection sensitivity could be greatly improved by using multi-path cell or increasing the laser power with EDFA. PMID:19839300

Peng, Yong; Yu, Qing-Xu

2009-08-01

94

Comparison of two assays, a faecal egg count reduction test (FECRT) and a coproantigen reduction test (CRT), for the diagnosis of resistance to triclabendazole in Fasciola hepatica in sheep.  

PubMed

A sheep trial was performed to evaluate two diagnostic assays, a faecal egg count reduction test (FECRT) and a coproantigen reduction test (CRT), for the diagnosis of resistance of Fasciola hepatica to triclabendazole (TCBZ). The FECRT defines successful TCBZ treatment as a 95% or greater reduction in fluke faecal egg counts (FECs) at 14 days post-treatment (dpt). The CRT defines effective TCBZ treatment as faeces negative for Fasciola coproantigens at 14dpt, as measured by the commercial BIO K201 coproantigen ELISA (Bio-X Diagnostics, Jemelle, Belgium). Forty-nine indoor-reared sheep were split into four trial groups and each sheep was infected with 200 metacercariae of 1 of 4 F. hepatica isolates, previously described as susceptible (Cullompton and Fairhurst) and resistant (Leon and Oberon) to TCBZ action, respectively. TCBZ treatment was administered at 12 weeks post-infection (wpi) to one sub-group in each infected sheep group, and these sheep were culled at 4 weeks post-treatment (wpt). Untreated sheep sub-groups, were culled at a parallel time-point, that is, at 16wpi. Necropsy was performed to confirm treatment efficacy. Individual faecal samples were collected twice-weekly throughout the trial period, sub-sampled and examined by a standardised egg sedimentation protocol and by the BIO K201 ELISA. Results supported the use of both the FECRT and the CRT for the diagnosis of resistance of F. hepatica to TCBZ. In addition, the study confirmed the TCBZ susceptibility of the Cullompton and Fairhurst F. hepatica isolates and the TCBZ resistance of the Oberon F. hepatica isolate. However, the Leon F. hepatica isolate was found to be susceptible, rather than resistant, to TCBZ action. PMID:21112153

Flanagan, A; Edgar, H W J; Gordon, A; Hanna, R E B; Brennan, G P; Fairweather, I

2011-03-10

95

Mechanism-based inactivation of cytochrome P-450 dependent benzo(a)pyrene hydroxylase activity by acetylenic and olefinic polycyclic arylhydrocarbons  

SciTech Connect

A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxygenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene (EP), 3-ethynylperylene (EPL), cis- and trans-1-(2-bromo-vinyl)pyrene (c-BVP and t-BVP), and 1-allylpyrene (AP) serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo(a)pyrene (BP) hydroxylase, while 1-vinyl-pyrene (VP) and phenyl 1-pyrenyl acetylene (PPA) do not cause a detectable suicide inhibition of the BP hydroxylase. The mechanism-based loss of BP hydroxylase activity caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes. In the presence of NADPH, /sup 3/H-labeled EP covalently attached to P-450 isozymes with a measured stoichiometry of one mole of EP per mole of the P-450 heme. The results of the effects of these aryl derivatives in the mammalian cell-mediated mutagenesis assay and toxicity assay show that none of the compounds examined nor any of the their metabolites produced in the incubation system are cytotoxic to V79 cells.

Gan, L.S.

1986-01-01

96

Models for reactions of acetylene on platinum (111): the. mu. /sub 3/-eta/sup 2/-acetylene derivative  

SciTech Connect

The reactions of acetylene with the Pt(111) surface have been studied in detail; the species Pt/sub 3/(..mu../sub 3/-eta/sup 2/-HCCH), Pt/sub 3/(..mu../sub 3/-eta/sup 2/-C=CH/sub 2/), and Pt/sub 3/(..mu../sub 3/-CCH/sub 3/) are formed sequentially, and theoretical studies of each species have been carried out. This article reports an attempt to mimic this chemistry by reaction of acetylene with the coordinatively unsaturated cluster (Pt/sub 3/(..mu../sub 3/-CO)(..mu..-dppm)/sub 3/)-(PF/sub 6/)/sub 2/ (1, dppm = Ph/sub 2/PCH/sub 2/PPh/sub 2/)/sup 5/ and the characterization of the first Pt/sub 3/(..mu../sub 3/-eta/sup 2/-HCCH) complexes. The chief chemical results are given here.

Douglas, G.; Manojlovic-Muir, L.; Muir, K.W.; Rashidi, M.; Anderson, C.M.; Puddephatt, R.J.

1987-10-14

97

Thermodynamic study on the formation of acetylene during coal pyrolysis in the arc plasma jet  

SciTech Connect

Based on the principle of minimizing the Gibbs free energy, the composition of C-H-O-N-S equilibrium system about acetylene formation during the pyrolysis in arc plasma jet for four kinds of different rank-ordered coals such as Datong, Xianfeng, Yangcheng, and Luan was analyzed and calculated. The results indicated that hydrogen, as the reactive atmosphere, was beneficial to the acetylene formation. The coal ranks and the hydrogen, oxygen, nitrogen, and sulfur in coal all could obviously affect the acetylene yield. The mole fraction of acetylene is the maximum when the ratio value of atom H/C was 2. The content of oxygen was related to the acetylene yield, but it does not compete with CO formation. These agreed with the experimental results, and they could help to select the coal type for the production of acetylene through plasma pyrolysis process.

Bao, W.; Li, F.; Cai, G.; Lu, Y.; Chang, L. [Taiyuan University of Technology, Taiyuan (China)

2009-07-01

98

Conversion of Natural Gas to Liquids via Acetylene as an Intermediate  

SciTech Connect

This paper describes an experimental investigation of the conversion of natural gas to liquid transportation fuels through acetylene as an intermediate. The first step is the direct thermal conversion of methane to acetylene utilizing a thermal plasma heat source to dissociate the methane. The dissociation products react to form a mixture of acetylene and hydrogen. Significant improvements over the prior art were observed; these improvements may be attributed to an improved methane injection configuration and minimization of radial temperature gradients. Conversion efficiencies (percent methane converted) approached 100% and acetylene yields in the 90–95% range with 2–4% solid carbon production were obtained. A variety of methods were examined for the second step, the conversion of acetylene to liquid products. The most promising technology was the reaction of acetylene with hydrogen over a shape-selective zeolite to form C3–C5+ aliphatics.

Fincke, James Russell; Anderson, Raymond Paul; Taylor, C. E.

2002-05-01

99

Models for reactions of acetylene on platinum(111): a vinyl(acetylene)triplatinum complex and evidence for an ethylidyne intermediate  

SciTech Connect

Reaction of (Pt/sub 3/(..mu../sub 3/-H)(..mu..-dppm)/sub 3/)/sup +/ (1) with excess acetylene gives (Pt/sub 3/(CH=CH/sub 2/)(..mu../sub 3/-eta/sup 2/(parallel)-HCCH)(..mu..-dppm)/sub 3/)/sup +/, where dppm = Ph/sub 2/PCH/sub 2/PPh/sub 2/. Deuterium-labeling studies indicate that H-D scrambling occurs within the vinyl group but not in the acetylene ligand. For example, (Pt/sub 3/(..mu../sub 3/-D)(..mu..-dppm)/sub 3/)/sup +/ with HCCH gave (Pt/sub 3/(CH==CH/sub 7/-d/sub 1/)(..mu../sub 3/-eta/sup 2/(parallel)-HCCH)(..mu..-dppm)/sub 3/)/sup +/, in which the deuterium label was distributed randomly in all three possible positions in the vinyl group. It is possible that this scrambling occurs by way of a short-lived ethylidyne intermediate. The complex is fluxional, due to rotation of the acetylene ligand, at room temperature. Similar reaction of 1 with excess propyne gives (Pt/sub 3/(CH=CHMe)(..mu../sub 3/-eta/sup 2/(**)-MeCCH)(..mu..-dppm)/sub 3/)/sup +/, but this complex is not fluxional at room temperature and is formed selectively by cis insertion of propyne into the Pt-H groups. There is a strong resemblance to the chemistry resulting from chemisorption of acetylene on a Pt(111) surface, thus providing a clear example of the value of coordinatively unsaturated clusters as mimics of metal surfaces.

Rashidi, M.; Puddephatt, R.J.

1988-07-01

100

Kinetics and Structure of Superagglomerates Produced by Silane and Acetylene  

NASA Technical Reports Server (NTRS)

The evolution of smoke in a laminar diffusion flame involves several steps. The first step is particle inception/nucleation in the high-temperature fuel-rich region of the flame followed by surface growth and coagulation/coalescence of the small particles. As the primary spheres grow in size and lose hydrogen, the colliding particles no longer coalesce but retain their identity as a cluster of primary spheres, termed an agglomerate. Finally, in the upper portion of the flame, the particles enter an oxidizing environment which may lead to partial or complete burnout of the agglomerates. Currently there is no quantitative model for describing the growth of smoke agglomerates up to superagglomerates with an overall dimension of 10 microns and greater. Such particles are produced during the burning of acetylene and fuels containing benzene rings such as toluene and polystyrene. In the case of polystyrene, smoke agglomerates in excess of 1 mm have been observed "raining" out from large fires. Evidence of the formation of superagglomerates in a laminar acetylene/air diffusion flame has been recently reported. Acetylene was chosen as the fuel since the particulate loading in acetylene/air diffusion flames is very high. Photographs were obtained by Sorensen using a microsecond xenon lamp of the "stream" of soot just above the flame. For low flow rates of acetylene, only submicrometer soot clusters are produced and they give rise to the homogeneous appearance of the soot stream. When the flow rate is increased to 1.7 cu cm/s, soot clusters up to 10 microns are formed and they are responsible for the graininess and at a flow rate of 3.4 cu cm/s, a web of interconnected clusters as large as the width of the flame is seen. This interconnecting web of superagglomerates is described as a gel state by Sorensen et al (1998). This is the first observation of a gel for a gas phase system. It was observed that this gel state immediately breaks up into agglomerates due to buoyancy induced turbulence and gravitational sedimentation.

Mulholland, G. W.; Hamins, A.; Sivathanu, Y.

1999-01-01

101

Blends of an aromatic poly(etherimide) with acetylene-terminated polyisoimides  

Microsoft Academic Search

A series of novel semi-interpenetrating networks (semi-1PNS) has been prepared and characterized. The semi-TPNs were prepared by blending a commercially available polyetherimide with commercially available acetylene-terminated polyisoimides. Thermal treatment of the polyetherimide\\/acetylene-terminated polyisoimide blends causes the acetylene-terminated polyisoimide to concurrently rearrange to a polyimide and to crosslink. The resulting semi-IPNs exhibit excellent mechanical performance and chemical resistance. The preparation and

Frank W Mercer; Vijay N Reddy; Martin T McKenzie

1995-01-01

102

Liquid chromatographic assay of the relative activities of serum pancreatic and salivary alpha-amylase using reductively pyridylaminated maltopentaose as a fluorescent substrate.  

PubMed

A method for the high-performance liquid chromatographic assay of the relative activities of serum pancreatic and salivary alpha-amylase has been developed, using maltopentaose reductively aminated with 2-aminopyridine as a fluorescent substrate. Both enzymes showed similar modes of action, cleaving the second and the third (from the non-reducing terminal) interglycosidic linkages of this substrate. However, the relative ease of cleavage of these two sites by the pancreatic enzyme was significantly different from that by the salivary enzyme. Therefore, determination of the molar ratio of the cleavage products by HPLC could lead to estimation of the activity ratio of these enzymes. The optimum chromatographic conditions for HPLC were as follows: column, LiChrosorb RP-18 (Merck, 7 microns, 250 X 4 mm I.D.); column temperature, ambient; eluent, 0.01% orthophosphoric acid-acetonitrile (4:1, v/v) containing 2.4 mM sodium laurylsulphate; flow-rate, 1.0 ml/min; wavelengths for fluorimetric detection, 320 nm (excitation)/400 nm (emission). The problem of interference by serum alpha-glucosidase was solved by specific inhibition with tris (hydroxymethyl) aminomethane and erythritol. The data obtained by the proposed method correlated well with those produced by the conventional method based on electrophoresis. PMID:3499444

Honda, S; Ohmura, T; Segawa, Y; Minematsu, T; Kakehi, K

1987-08-01

103

Acetylene-derived polymers and their applications in hair and skin care.  

PubMed

Synopsis Since the introduction over 30 years ago of polyvinylpyrrolidone (PVP) as the first synthetic hairspray resin, acetylene-derived polymers have found wide and increasing applications in the cosmetics and toiletries industry. This review covers the two main classes of acetylenic polymers. In the first class, in which the chemistry may be traced back to reaction of acetylene with formaldehyde, are included PVP homopolymers and copolymers of VP with vinyl acetate, dimethylaminoethyl methacrylate, vinylcaprolactam and styrene. In the second class, stemming from reaction of acetylene with methanol, are the poly (vinyl methyl ether/maleic acid) monoester resins. PMID:19456933

Petter, P J

1989-02-01

104

Characteristics of the radical polymerization of acetylene monomers  

NASA Astrophysics Data System (ADS)

The radical polymerization of acetylene monomers is studied via electron spin resonance (ESR) spectroscopy, calorimetry, chromatography, and gravimetry within a wide range of temperatures (77-340 K). A growing macroradical with an unpaired electron localized on the terminal moiety of a macromolecule is shown to lose its activity, due to the delocalization of electron over the conjugated system of double bonds after attaining the very short length of 5-10 monomer units. This explains the low conversion and molecular masses of the synthesized polymers.

Gordon, D. A.; Volodina, V. A.; Mikhailov, A. I.

2014-12-01

105

Experimental methods to examine the role of vibrational excitation in the singlet-triplet spin-orbit coupling in acetylene  

E-print Network

Despite being a seemingly simple molecule, acetylene has a complicated electronic structure that has been studied extensively both experimentally and theoretically. Acetylene has been observed to have a complex spin-orbit ...

Robertson, Erika Marie

2010-01-01

106

Mechanism of tungsten-dependent acetylene hydratase from quantum chemical calculations  

E-print Network

Mechanism of tungsten-dependent acetylene hydratase from quantum chemical calculations Rong hydratase is a tungsten-dependent enzyme that cata- lyzes the nonredox hydration of acetylene metalloenzyme cluster approach Tungsten is the heaviest metal in biology and plays prominent roles in carbon

Liao, Rongzhen

107

Numerical study of ethylene and acetylene laminar flame speeds  

SciTech Connect

Detailed chemical kinetic computations for ethylene-air and acetylene-air mixtures have been performed to simulate laminar flame speeds. Sensitivity analysis was applied to determine those reactions which strongly influence flame propagation. In ethylene-air mixtures, the C{sub 2}H{sub 3} + O{sub 2} = CH{sub 2}CHO + O reaction was one of the most sensitive reactions in the C{sub 2}H{sub 4}/C{sub 2}H{sub 3} submechanism and therefore this reaction was very important to ethylene flame propagation. This reaction was not considered in previously reported mechanisms used to model ethylene-air flame propagation. In acetylene-air mixtures, the C{sub 2}H{sub 2}+O {yields} Products, HCCO+H=CH{sub 2}(s)+CO, HCCO+O{sub 2}=CO{sub 2}+CO+H, H+C{sub 2}H{sub 2}(+M) = C{sub 2}H{sub 3}(+M) and CH{sub 2}(s)+C{sub 2}H{sub 2} = H{sub 2}CCCH+H were the most sensitive reactions in the C{sub 2}H{sub 2}/HCCO / CH{sub 2}(s) reaction set.

Marinov, N.M.; Pitz, W.J.; Westbrook, C.K.

1995-03-01

108

Critical points bifurcation analysis of high-? bending dynamics in acetylene  

NASA Astrophysics Data System (ADS)

The bending dynamics of acetylene with pure vibrational angular momentum excitation and quantum number ? ?0 are analyzed through the method of critical points analysis, used previously [V. Tyng and M. E. Kellman, J. Phys. Chem. B 110, 18859 (2006)] for ? =0 to find new anharmonic modes born in bifurcations of the low-energy normal modes. Critical points in the reduced phase space are computed for continuously varied bend polyad number Nb=n4+n5 as ? =?4+?5 is varied between 0 and 20. It is found that the local L, orthogonal O, precessional P, and counter-rotator CR families persist for all ?. In addition, for ? ?8, there is a fifth family of critical points which, unlike the previous families, has no fixed relative phase ("off great circle" OGC). The concept of the minimum energy path in the polyad space is developed. With restriction to ? =0 this is the local mode family L. This has an intuitive relation to the minimum energy path or reaction mode for acetylene-vinylidene isomerization. With ? ?0 included as a polyad number, the ? =0 minimum energy path forms a troughlike channel in the minimum energy surface in the polyad space, which consists of a complex mosaic of L, O, and OGC critical points. There is a division of the complete set of critical points into layers, the minimum energy surface forming the lowest.

Tyng, Vivian; Kellman, Michael E.

2009-12-01

109

Nanosecond discharge ignition in acetylene-containing mixtures  

NASA Astrophysics Data System (ADS)

We study experimentally and numerically the kinetics of ignition in lean and stoichiometric C2H2?:?O2?:?Ar mixtures after a high-voltage nanosecond discharge. The ignition delay time is measured behind a reflected shock wave with and without the discharge using detection of CH radiation. Generation of the discharge plasma is shown to lead to a decrease in ignition delay time. Discharge processes followed by chain chemical reactions with energy release are simulated during ignition in the C2H2?:?O2?:?Ar mixtures. The generation of atoms, radicals and excited and charged particles in the discharge phase is numerically simulated. The calculations are based on the measured time-resolved discharge current and electric field. The calculated densities of the active particles produced in the discharge on a nanosecond time scale are employed as input data to simulate plasma-assisted ignition on a microsecond scale. The calculated ignition delay times are compared with the experimental data. It is shown that the effect of the discharge plasma on ignition of the acetylene-containing mixtures is associated with active species production in the discharge phase rather than with gas heating during the discharge and in its afterglow. A sensitivity analysis is made to determine limiting reactions in acetylene autoignition and ignition after the discharge under the conditions studied.

Kosarev, I. N.; Pakhomov, A. I.; Kindysheva, S. V.; Anokhin, E. M.; Aleksandrov, N. L.

2013-08-01

110

Acetylene as fast food: implications for development of life on anoxic primordial Earth and in the outer solar system.  

PubMed

Acetylene occurs, by photolysis of methane, in the atmospheres of jovian planets and Titan. In contrast, acetylene is only a trace component of Earth's current atmosphere. Nonetheless, a methane-rich atmosphere has been hypothesized for early Earth; this atmosphere would also have been rich in acetylene. This poses a paradox, because acetylene is a potent inhibitor of many key anaerobic microbial processes, including methanogenesis, anaerobic methane oxidation, nitrogen fixation, and hydrogen oxidation. Fermentation of acetylene was discovered approximately 25 years ago, and Pelobacter acetylenicus was shown to grow on acetylene by virtue of acetylene hydratase, which results in the formation of acetaldehyde. Acetaldehyde subsequently dismutates to ethanol and acetate (plus some hydrogen). However, acetylene hydratase is specific for acetylene and does not react with any analogous compounds. We hypothesize that microbes with acetylene hydratase played a key role in the evolution of Earth's early biosphere by exploiting an available source of carbon from the atmosphere and in so doing formed protective niches that allowed for other microbial processes to flourish. Furthermore, the presence of acetylene in the atmosphere of a planet or planetoid could possibly represent evidence for an extraterrestrial anaerobic ecosystem. PMID:18199006

Oremland, Ronald S; Voytek, Mary A

2008-02-01

111

Organogermanium Chemistry: Germacyclobutanes and digermane Additions to Acetylenes  

SciTech Connect

This dissertation comprises two main research projects. The first project, presented in Chapter 1, involves the synthesis and thermochemistry of germacyclobutanes (germetanes). Four new germetanes (spirodigermetane, diallylgermetane, dichlorogermetane, and germacyclobutane) have been synthesized using a modified di-Grignard synthesis. Diallylgermetane is shown to be a useful starting material for obtaining other germetanes, particularly the parent germetane, germacyclobutane. The gas-phase thermochemistries of spirodigermetane, diallylgermetane and germacyclobutane have been explored via pulsed stirred-flow reactor (SFR) studies, showing remarkable differences in decomposition, depending on the substitution at the germanium atom. The second project investigates the thermochemical, photochemical, and catalytic additions of several digermanes to acetylenes. The first examples of thermo- and photochemical additions of Ge-Ge bonds to C{triple_bond}C are demonstrated. Mechanistic investigations are described and comparisons are made to analogous disilane addition reactions, previously studied in their group.

Andrew Michael Chubb

2003-12-12

112

Ultrafast Extreme Ultraviolet Induced Isomerization of Acetylene Cations  

SciTech Connect

Ultrafast isomerization of acetylene cations ([HC = CH]{sup +}) in the low-lying excited A{sup 2}{Sigma}{sub g}{sup +} state, populated by the absorption of extreme ultraviolet (XUV) photons (38 eV), has been observed at the Free Electron Laser in Hamburg, (FLASH). Recording coincident fragments C{sup +} + CH{sub 2}{sup +} as a function of time between XUV-pump and -probe pulses, generated by a split-mirror device, we find an isomerization time of 52 {+-} 15 fs in a kinetic energy release (KER) window of 5.8 < KER < 8 eV, providing clear evidence for the existence of a fast, nonradiative decay channel.

Jiang, Y.; Rudenko, Artem; Herrwerth, O.; Foucar, L.; Kurka, M.; Kuhnel, K.; Lezius, M.; Kling, Matthias; van Tilborg, Jeroen; Belkacem, Ali; Ueda, K.; Dusterer, S.; Treusch, R.; Schroter, Claus-Dieter; Moshammer, Robbert; Ullrich, Joachim

2011-06-17

113

Photo double ionization of acetylene and subsequent fragmentation pathways  

NASA Astrophysics Data System (ADS)

We have investigated the photo double ionization of acetylene (C2H2) molecules using photons of 42eV energy. Coincident measurements of both ions and electrons with the COLd Target Recoil Ion Momentum Spectroscopy (COLTRIMS) method make kinematically complete study possible. We extract the 3d-momentum vectors of each particle using the measured flight time to the detector and the position on the detector. We identify the fragmentation pathways by using the measured energy of the photo electrons, kinetic energy release of the nuclear fragments, photon energy, and the ionization potential for a specific dication state evaluated from theory. We mainly discuss the pathways leading to the symmetric breakup (CH^+/CH^+), the deprotonation (H^+/C2H^+) and the quasi-symmetric fragmentation (C^+/H2C^+). We explain the importance of such pathways for the study of the time dependent dynamics of the fragmentation.

Gaire, B.; Braun, P.; Bocharova, I.; Sturm, F.; Haxton, D.; Belkacem, A.; Weber, Th.; Cocke, C. L.; Landers, A.; Dorner, R.

2012-06-01

114

Ultrafast dynamics in acetylene clocked in a femtosecond XUV stopwatch  

NASA Astrophysics Data System (ADS)

Few-photon induced ultrafast dynamics in acetylene (C2H2) leading to several dissociation channels—deprotonation (H++C2H+ and H++C2H2+), symmetric break-up (CH++CH+) and isomerization (C++CH2+)--were investigated employing the (XUV; extreme ultra-violet)-pump-(XUV extreme ultra-violet)-probe scheme at the free-electron laser in Hamburg, combined with multi-hit coincidence detection. The kinetic energy releases and fragment-ion momentum distributions for various decay channels are presented. The C++CH2+ and H++C2H2+ channels reveal clear signatures of ultrafast molecular mechanisms, demonstrating potential applications of our pump-probe technique to complex systems in order to study a large variety of ultrafast phenomena in the XUV regime.

Jiang, Y. H.; Senftleben, A.; Kurka, M.; Rudenko, A.; Foucar, L.; Herrwerth, O.; Kling, M. F.; Lezius, M.; Tilborg, J. V.; Belkacem, A.; Ueda, K.; Rolles, D.; Treusch, R.; Zhang, Y. Z.; Liu, Y. F.; Schröter, C. D.; Ullrich, J.; Moshammer, R.

2013-08-01

115

Acetylenic-terminated fluorinated polyimide, properties and applications  

SciTech Connect

A new line of acetylene-terminated, oligomeric polyimides has been introduced for aerospace and electronic applications. The oligomers are derived from the monomers 4,4'-hexafluoroisopropylidinebis(phthalic anhydride), 1,3'-bis(3-aminophenoxy)benzene, and 3-ethynylaniline. They are fully imidized and cure by reactions of the terminal ethynyl groups. These products have unique properties when compared with similar systems containing nonfluorinated dianhydrides. Studies have shown improved solubility in a variety of solvents and stable solutions at high concentrations. The glass transition temperature is in the 300-350 C range. Decomposition by thermal gravimetric analysis (TCA), occurs at about 550 C. The weight loss by isothermal TGA is less than 1.0 percent per hour at 400 C in air. The dielectric constants are less than 3.0 over a wide range of frequencies. 9 references.

Capo, D.J.; Schoenberg, J.E.

1987-04-01

116

Detailed modeling of hydrocarbon nanoparticle nucleation in acetylene discharges  

NASA Astrophysics Data System (ADS)

The initial stage of nanoparticle formation and growth in radiofrequency acetylene (C2H2) plasmas is investigated by means of a self-consistent one-dimensional fluid model. A detailed chemical kinetic scheme, containing electron impact, ion-neutral, and neutral-neutral reactions, has been developed in order to predict the underlying dust growth mechanisms and the most important dust precursors. The model considers 41 different species (neutrals, radicals, ions, and electrons) describing hydrocarbons (CnHm) containing up to 12 carbon atoms. Possible routes for particle growth are discussed. Both positive and negative ion reaction pathways are considered, as consecutive anion- and cation-molecule reactions seem to lead to a fast build up of the carbon skeleton.

de Bleecker, Kathleen; Bogaerts, Annemie; Goedheer, Wim

2006-02-01

117

Generalized critical points analysis of acetylene vibrational dynamics  

NASA Astrophysics Data System (ADS)

Classical tools of nonlinear dynamics are used to study the highly excited vibrations of small molecules. For effective Hamiltonians with one polyad number (approximate constant of motion), previously developed methods locate new anharmonic modes using the critical points in the reduced classical phase space. Theoretical arguments are given for generalizing the method to more than one polyad number. As the simplest classical invariant structure, critical points of the reduced phase space are solved analytically without relying on either integrating trajectories or visual inspection. These critical points, especially those that are linearly stable, are expected to indicate regions with the same type of classical dynamics as well as quantum modes of vibration. The pure bending Hamiltonian of acetylene (C2H2) is analyzed to demonstrate the effectiveness of critical points analysis. Four families of critical points are born in distinct bifurcations, each corresponding to a novel anharmonic mode. These modes are visualized with custom computer-generated animations. Their origin and nature are qualitatively explained through separate consideration of DD-I and ? resonance alone. Quantum survival probability verifies that the Local and Counter Rotator modes are the stable modes of vibration at high excitation. The same analysis is extended for the first time to the acetylene stretch-bend system, which has never been analyzed classically with all the resonance couplings. Preliminary results are obtained for the polyad series containing the C-H stretch overtones. The local C-H stretch critical points family, induced by the stretch-stretch (K11/33) resonance, is located and shown to bifurcate into at least 4 new families when the stretch-bend resonances are included. The new families indicate that the mixing between the stretch and bend may result in novel vibrational modes. This dissertation includes my previously co-authored materials.

Ding, Xinli

118

Acetylene as a substrate in the development of primordial bacterial communities  

USGS Publications Warehouse

The fermentation of atmospheric acetylene by anaerobic bacteria is proposed as the basis of a primordial heterotrophic food chain. The accumulation of fermentation products (acetaldehyde, ethanol, acetate and hydrogen) would create niches for sulfate-respiring bacteria as well as methanogens. Formation of acetylene-free environments in soils and sediments would also alter the function of nitrogenase from detoxification to nitrogen-fixation. The possibility of an acetylene-based anaerobic food chain in Jovian-type atmospheres is discussed. ?? 1988 Kluwer Academic Publishers.

Culbertson, C.W.; Strohmaier, F.E.; Oremland, R.S.

1988-01-01

119

Inhibition of alkylbenzene biodegradation under denitrifying conditions by using the acetylene block technique.  

PubMed Central

Addition of acetylene to microcosms simultaneously amended with nitrate and alkylbenzenes resulted in inhibition of the rate of alkylbenzene biodegradation under denitrifying conditions. Toluene, xylenes, and 1,2,4-trimethylbenzene were recalcitrant, whereas ethylbenzene was degraded at a slower rate than usual. Benzene was not degraded in either case. Addition of acetylene to microcosms preexposed to nitrate and alkylbenzenes produced similar inhibition. These data indicate that the activities of microorganisms that degrade alkylbenzenes under denitrifying conditions may be suppressed if the standard acetylene block technique is used to verify denitrifying activity. PMID:1444371

Hutchins, S R

1992-01-01

120

The abundances of ethane to acetylene in the atmospheres of Jupiter and Saturn  

NASA Technical Reports Server (NTRS)

The present determination of the stratospheric abundances of ethane and acetylene on Jupiter and Saturn on the basis of IR spectra near 780/cm uses atmospheric models whose thermal and density profiles have constant mixing ratios. The ratio of ethane to acetylene is noted to be insensitive to model atmosphere assumptions; it is 55 + or - 31 for Jupiter and 23 + or - 12 where model mixing ratios are uniform. Atmospheric model density profiles adapted from theoretical photochemical models are noted to also yield a higher ethane/acetylene ratios for Jupiter.

Noll, K. S.; Knacke, R. F.; Tokunaga, A. T.; Lacy, J. H.; Beck, S.; Serabyn, E.

1986-01-01

121

The abundances of ethane and acetylene in the atmospheres of Jupiter and Saturn  

NASA Technical Reports Server (NTRS)

The present determination of the stratospheric abundances of ethane and acetylene on Jupiter and Saturn on the basis of IR spectra near 780/cm uses atmospheric models whose thermal and density profiles have constant mixing ratios. The ratio of ethane to acetylene is noted to be insensitive to model atmosphere assumptions; it is 55 + or - 31 for Jupiter and 23 + or - 12 where model mixing ratios are uniform. Atmospheric model density profiles adapted from theoretical photochemical models are noted to also yield a higher ethane/acetylene ratios for Jupiter.

Noll, K. S.; Knacke, R. F.; Tokunaga, A. T.; Lacy, J. H.; Beck, S.

1986-01-01

122

Denitrification in Low pH Spodosols and Peats Determined with the Acetylene Inhibition Method  

PubMed Central

Potential denitrification rates were determined for predominantly acid (pH ? 3.6) horizons of forestal, miry, and agricultural soils from 22 locations in southern Finland. The acetylene inhibition method was used with nitrate-amended water-logged soils incubated in an N2 atmosphere containing 2.5 or 5% C2H2. Complete inhibition of the reduction of N2O to N2 was observed in 99.3% of the samples. The denitrification rates varied from 0.12 to 53.8 ?g of N·cm-3·day-1. Correlation between denitrification rate and soil pH was highly significant: r = 0.84 on a volume basis, and r = 0.44 on a weight basis. Vegetation type and amount of soil organic matter had a minor or no effect, respectively. In spodosolized soils the rates were significantly higher for B horizons than for A horizons. These results show that denitrification can occur in acid soils. PMID:16345603

Müller, Michael M.; Sundman, Veronica; Skujinš, J.

1980-01-01

123

ESI-MS, DFT and Synthetic Studies on the H2-Mediated Coupling of Acetylene: Insertion of C=X Bonds into Rhodacyclopentadienes and Brønsted Acid Cocatalyzed Hydrogenolysis of Organorhodium Intermediates  

PubMed Central

The catalytic mechanism of the hydrogen-mediated coupling of acetylene to carbonyl compounds and imines has been examined using three techniques: (a) ESI-MS and ESI-CAD-MS analyses, (b) computational modeling, and (c) experiments wherein putative reactive intermediates are diverted to alternative reaction products. ESI-MS analysis of reaction mixtures from the hydrogen-mediated reductive coupling of acetylene to ?-ketoesters or N-benzenesulfonyl aldimines corroborate a catalytic mechanism involving C=X (X = O, NSO2Ph) insertion into a cationic rhodacyclopentadiene obtained by way of acetylene oxidative dimerization with subsequent Brønsted acid cocatalyzed hydrogenolysis of the resulting oxa- or azarhodacycloheptadiene. Hydrogenation of 1,6-diynes in the presence of ?-ketoesters provides analogous coupling products. ESI mass spectrometric analysis again corroborates a catalytic mechanism involving carbonyl insertion into a cationic rhodacyclopentadiene. For all ESI-MS experiments, the structural assignments of ions are supported by multi-stage collisional activated dissociation (CAD) ESI-MS analyses. Further support for the proposed catalytic mechanism derives from experiments aimed at the interception of putative reactive intermediates and their diversion to alternate reaction products. For example, rhodium catalyzed coupling of acetylene to aldehyde in the absence of hydrogen or Brønsted acid cocatalyst provides the corresponding (Z)-butadienyl ketone, which arises from ?-hydride elimination of the proposed oxarhodacycloheptadiene intermediate, as corroborated by isotopic labeling. Additionally, the putative rhodacyclopentadiene intermediate obtained from the oxidative coupling of acetylene is diverted to the product of reductive [2+2+2] cycloaddition when N-p-toluenesulfonyl-dehydroalanine ethyl ester is used as the coupling partner. The mechanism of this transformation also is corroborated by isotopic labeling. Computer model studies based on density functional theory (DFT) support the proposed mechanism and identify Brønsted acid cocatalyst assisted hydrogenolysis to be the most difficult step. The collective studies provide new insight into the reactivity of cationic rhodacyclopentadienes, which should facilitate the design of related rhodium catalyzed C-C couplings. PMID:19845357

Williams, Vanessa M.; Kong, Jong Rock; Ko, Byoung Joon; Mantri, Yogita; Brodbelt, Jennifer S.; Baik, Mu-Hyun; Krische, Michael J.

2009-01-01

124

Structure of the non-redox-active tungsten/[4Fe:4S] enzyme acetylene hydratase  

PubMed Central

The tungsten–iron–sulfur enzyme acetylene hydratase stands out from its class because it catalyzes a nonredox reaction, the hydration of acetylene to acetaldehyde. Sequence comparisons group the protein into the dimethyl sulfoxide reductase family, and it contains a bis-molybdopterin guanine dinucleotide-ligated tungsten atom and a cubane-type [4Fe:4S] cluster. The crystal structure of acetylene hydratase at 1.26 ? now shows that the tungsten center binds a water molecule that is activated by an adjacent aspartate residue, enabling it to attack acetylene bound in a distinct, hydrophobic pocket. This mechanism requires a strong shift of pKa of the aspartate, caused by a nearby low-potential [4Fe:4S] cluster. To access this previously unrecognized W–Asp active site, the protein evolved a new substrate channel distant from where it is found in other molybdenum and tungsten enzymes. PMID:17360611

Seiffert, Grazyna B.; Ullmann, G. Matthias; Messerschmidt, Albrecht; Schink, Bernhard; Kroneck, Peter M. H.; Einsle, Oliver

2007-01-01

125

Four new guaianolides and acetylenic alcohol from Saussurea katochaete collected in China.  

PubMed

Four new guaianolides and an acetylenic alcohol were isolated from Saussurea katochaete (Asteraceae) collected in China. The structures were determined based on the spectroscopic data including the absolute configuration by application of advanced Mosher's method. PMID:22574438

Saito, Yoshinori; Iwamoto, Yuko; Okamoto, Yasuko; Gong, Xun; Kuroda, Chiaki; Tori, Motoo

2012-04-01

126

Infrared Spectroscopy of Interphases Between Model Rubber Compounds and Plasma Polymerized Acetylene Films  

Microsoft Academic Search

Thin (? 750 Å) plasma polymerized films of acetylene deposited onto polished steel substrates are promising primers for rubber-to-metal bonding. The as-deposited films contained mono- and di-substituted acetylene groups, aromatic groups, and groups such as carbonyl which apparently resulted from reaction of residual free radicals with oxygen when the films were exposed to the atmosphere. There was some evidence for

Y. M. Tsai; F. J. Boerio; Dong K. Kim

1995-01-01

127

A review of acetylene, ethylene and ethane molecular spectroscopy for planetary applications  

NASA Technical Reports Server (NTRS)

Spectroscopic work in acetylene, ethylene and ethane, are of particular interest since the Voyager IRIS observations of Jupiter. Acetylene and ethane but not ethylene were observed in the Jovian spectrum. Two fundamental bands of the observed gases are used to determine the spatial distribution of these hydrocarbons on Jupiter and to illuminate the photochemistry of these species. The 100 to 1000 cm region is discussed and selected examples of current laboratory work are given.

Maguire, W. C.

1982-01-01

128

Mechanism-based inactivation of benzo(a)pyrene hydroxylase by aryl acetylenes and aryl olefins  

SciTech Connect

A series of aryl acetylenes and aryl olefins have been examined as substrates and inhibitors of cytochrome P-450 dependent monooxgenases in liver microsomes from 5,6-benzoflavone or phenobarbital pretreated rats. 1-Ethynylpyrene, 3-ethynylperylene, 2-ethynylfluorene, methyl 1-pyrenyl acetylene, cis- and trans-1-(2-bromovinyl)pyrene, and 1-allylpyrene serve as mechanism-based irreversible inactivators (suicide inhibitors) of benzo(a)pyrene hydroxylase, while 1-vinylpyrene and phenyl 1-pyrenyl acetylene do not cause a detectable suicide inhibition of benzo(a)pyrene hydroxylase. The mechanism-based loss of benzo(a)pyrene hydroxylase caused by the aryl acetylenes is not accompanied by a corresponding loss of the P-450 content of the microsomes (suicide destruction). The suicide inhibition by these aryl acetylenes therefore does not involve covalent binding to the heme moiety of the monooxygenase. Nevertheless, in the presence of NADPH, /sup 3/H-labeled 1-ethynylpyrene becomes covalently attached to the cytochrome P-450 protein; the measured stoichiometry of binding is one 1-ethynylpyrene per P-450 heme unit. The authors conclude that the inhibition of benzo(a)pyrene hydroxylase produced by 1-ethynylpyrene may be related to the mechanism of suicide inhibition of P-450 activity by chloramphenicol rather than the mechanism of suicide destruction of P-450 previously described for acetylene and propyne.

Gan, L.S.; Lu, J.Y.L.; Alworth, W.L.

1986-05-01

129

Kinetic tetrazolium microtiter assay  

NASA Technical Reports Server (NTRS)

A method for conducting an in vitro cell assay using a tetrazolium indicator is disclosed. The indicator includes a nonionic detergent which solubilizes a tetrazolium reduction product in vitro and has low toxicity for the cells. The incubation of test cells in the presence of zolium bromide and octoxynol (TRITON X-100) permits kinetics of the cell metabolism to be determined.

Pierson, Duane L. (inventor); Stowe, Raymond P. (inventor); Koeing, David W. (inventor)

1992-01-01

130

Topoisomerase Assays  

PubMed Central

Topoisomerases are nuclear enzymes that play essential roles in DNA replication, transcription, chromosome segregation, and recombination. All cells have two major forms of topoisomerases: type I, which makes single-stranded cuts in DNA, and type II enzymes, which cut and pass double-stranded DNA. DNA topoisomerases are important targets of approved and experimental anti-cancer agents. The protocols described in this unit are of assays used to assess new chemical entities for their ability to inhibit both forms of DNA topoisomerase. Included are an in vitro assay for topoisomerase I activity based on relaxation of supercoiled DNA and an assay for topoisomerase II based on the decatenation of double-stranded DNA. The preparation of mammalian cell extracts for assaying topoisomerase activity is described, along with a protocol for an ICE assay for examining topoisomerase covalent complexes in vivo and an assay for measuring DNA cleavage in vitro. PMID:22684721

Nitiss, John L.; Soans, Eroica; Rogojina, Anna; Seth, Aman; Mishina, Margarita

2012-01-01

131

The Heat of Sublimation of Solid Ethylene and Acetylene  

NASA Astrophysics Data System (ADS)

The atmospheres of the outer planets and their satellites include trace, but chemically important, amounts of small hydrocarbon molecules. These molecules also appear in solid form in clouds within the atmospheres and as surface layers on the planet or on haze particles in the atmosphere. The modeling of the composition and photochemistry of these atmospheres depends critically on accurate values of the vapor pressure of these hydrocarbons, which in turn requires accurately measured data. It is important to acquire these data over as much of the temperature and pressure range of interest as possible to reduce the need to extrapolate since this can introduce major errors in vapor pressure. In addition to vapor pressures, study of the behavior of solid-vapor equilibrium for small particles, and especially of surface layers, requires information on the heat of sublimation of the solid phases. Ethylene (C2H4) and acetylene (C2H2) are present in the atmospheres of Saturn and Titan, so we previously measured the solid phase vapor pressure of the former from 69 to 97 K (Nelson, Allen, and Harris 1997) and of the latter from 84 to 124 K (Nelson and Allen 1998). We have now refined those data and used them to evaluate the heats of sublimation of these molecules over the same temperature ranges. Nelson, R. N., Allen, J. E., Jr., and Harris, B. C., Jr., 1997, B.A.A.S. 29, 1009 Nelson, R. N. and Allen, J. E., Jr., 1997, B.A.A.S. 30, 1101

Nelson, R. N.; Allen, J. E., Jr.

2002-09-01

132

An improved processible acetylene-terminated polyimide for composites  

NASA Technical Reports Server (NTRS)

The newest member of a family of thermosetting acetylene-substituted polyimide oligomers is HR600P. This oligomer is the isoimide version of the oligomer known as HR600P and Thermid 600. Although both types of material yield the same heat resistant end products after cure, HR600P has much superior processing characteristics. This attributed to its lower melting temperature (160 + or - 10 C, 320 + or - 20 F) in contrast to 202 C (396 F) for Thermid MC-600, its longer gel time at its processing temperature (16 to 30 minutes bvs 3 minutes), and its excellent solubility in low boiling solvents such as tetrahydrofuran, glymes, or 4:1 methyl ethyl ketone/toluene mixtures. These advantages provide more acceptable coating and impregnation procedures, allow for more complete removal at lower temperatures, provide a longer pot life or working time, and allow composite structure fabrication in conventional autoclaves used for epoxy composite curing. The excellent processing characteristics of HR600P allow its use in large area laminated structures, structural composites, and molding compositions.

Landis, A. L.; Naselow, A. B.

1985-01-01

133

Opsonophagocytic assay.  

PubMed

The opsonophagocytic killing (OPK) assay is used as a correlate for protection to measure the functional capacities of vaccine-candidate-raised antibodies. This in vitro assay aids selecting promising vaccines by demonstrating whether the vaccine-induced antibodies drive efficient complement deposition and subsequent opsonophagocytic killing. Here, we describe two protocols for an OPK assay using either human-derived PMNs or cultured HL-60 cells. PMID:24218277

Dwyer, Markryan; Gadjeva, Mihaela

2014-01-01

134

Comparison and reliability of two non-invasive acetylene uptake techniques for the measurement of cardiac output  

Microsoft Academic Search

Comparison and reliability of two non-invasive acetylene uptake techniques for the measurement of cardiac output. Thirteen trained male cyclists performed CO2 rebreathing (CO2RB) at intensities from rest to 200 W, and open-circuit acetylene uptake (OpCirc) and single-breath acetylene uptake (SB) at intensities from rest to 300 W, with all procedures using 50 W increments. Oxygen consumption \\u000a cardiac output \\u000a and heart rate (HR), were

D. W. Dibski; D. J. Smith; R. Jensen; S. R. Norris; G. T. Ford

2005-01-01

135

[Photodissociation of Acetylene and Acetone using Step-Scan Time-Resolved FTIR Emission Spectroscopy  

NASA Technical Reports Server (NTRS)

The photodissociation of acetylene and acetone was investigated as a function of added quenching gas pressures using step-scan time-resolved FTIR emission spectroscopy. Its main components consist of Bruker IFS88, step-scan Fourier Transform Infrared (FTIR) spectrometer coupled to a flow cell equipped with Welsh collection optics. Vibrationally excited C2H radicals were produced from the photodissociation of acetylene in the unfocused experiments. The infrared (IR) emission from these excited C2H radicals was investigated as a function of added argon pressure. Argon quenching rate constants for all C2H emission bands are of the order of 10(exp -13)cc/molecule.sec. Quenching of these radicals by acetylene is efficient, with a rate constant in the range of 10(exp -11) cc/molecule.sec. The relative intensity of the different C2H emission bands did not change with the increasing argon or acetylene pressure. However, the overall IR emission intensity decreased, for example, by more than 50% when the argon partial pressure was raised from 0.2 to 2 Torr at fixed precursor pressure of 160mTorr. These observations provide evidence for the formation of a metastable C2H2 species, which are collisionally quenched by argon or acetylene. Problems encountered in the course of the experimental work are also described.

McLaren, Ian A.; Wrobel, Jacek D.

1997-01-01

136

Cellulase Assays  

NASA Astrophysics Data System (ADS)

Cellulose is a heterogeneous polysaccharide, and its enzymatic hydrolysis requires endoglucanase, exoglucanase (cellobiohydrolase), and ?-glucosidase to work together. We summarize the most commonly used assays for individual enzymes and cellulase mixture.

Zhang, Y. H. Percival; Hong, Jiong; Ye, Xinhao

137

Deactivation mechanisms for Pd/Al{sub 2}O{sub 3} acetylene hydrogenation catalysts  

SciTech Connect

The selective hydrogenation of acetylenic impurities to ethylene is a crucial purification step in the production of olefins by steam cracking. This hydrogenation is done catalytically using a Pd/Al{sub 2}O{sub 3} catalyst in a fixed bed reactor. The designed lifetime of the catalyst in a front end acetylene converter is about 4 years. Accelerated catalyst deactivation and thermal runaways caused by loss in catalyst selectivity are common problems which plague acetylene converters. Such problems result in unscheduled shutdowns and increased costs to replace deactivated catalyst. This presentation outlines several deactivation mechanisms of the catalyst and discusses how they affect catalyst lifetime and performance. Catalyst characterization using electron microscopy and CO chemisorption provides information on how poisons deteriorate the catalyst and Pd particle size changes produced by use and regeneration. Thermal gravimetric analysis was also used to determine the extent of coke burn-off using less severe regeneration procedures.

Hall, J.B.; Huggins, B.J.; Meyers, B.L. [Amoco Corp., Naperville, IL (United States); Kaminsky, M.P. [Amoco Chemical Co., Naperville, IL (United States)

1994-12-31

138

Estimation of nitrogenase activity in the presence of ethylene biosynthesis by use of deuterated acetylene as a substrate  

SciTech Connect

Nitrogenase reduces deuterated acetylene primarily to cis dideuterated ethylene. This can be distinguished from undeuterated ethylene by the use of Fourier transform infrared spectroscopy. Characteristic bands in the region from 800 to 3,500 cm-1 can be used to identify and quantitate levels of these products. This technique is applicable to field studies of nitrogen fixation where ethylene biosynthesis by plants or bacteria is occurring. We have verified the reaction stoichiometry by using Klebsiella pneumoniae and Bradyrhizobium japonicum in soybeans. The most useful bands for quantitation of substrate purity and product distribution are as follows: acetylene-d0, 3,374 cm-1; acetylene-d1, 2,584 cm-1; acetylene-d2, 2,439 cm-1; cis-ethylene-d2, 843 cm-1; trans-ethylene-d2, 988 cm-1; ethylene-d1, 943 cm-1; ethylene-d0, 949 cm-1. (The various deuterated ethylenes and acetylenes are designated by a lowercase d and subscript to indicate the number, but not the position, of deuterium atoms in the molecule.) Mass spectrometry coupled to a gas chromatograph system has been used to assist in quantitation of the substrate and product distributions. Significant amounts of trans-ethylene-d2 were produced by both wild-type and nifV mutant K. pneumoniae. Less of this product was observed with the soybean system.

Lin-Vien, D.; Fateley, W.G.; Davis, L.C. (Kansas State Univ., Manhattan (USA))

1989-02-01

139

Heats of Formation of Triplet Ethylene, Ethylidene, and Acetylene  

SciTech Connect

Heats of formation of the lowest triplet state of ethylene and the ground triplet state of ethylidene have been predicted by high level electronic structure calculations. Total atomization energies obtained from coupled-cluster CCSD(T) energies extrapolated to the complete basis set limit using correlation consistent basis sets (CBS), plus additional corrections predict the following heats of formation in kcal/mol: Delta H0f(C2H4,3A1) = 80.1 at 0 K and 78.5 at 298 K, and Delta H0f(CH3CH,3A") = 86.8 at 0 K and 85.1 at 298 K, with an error of less than +-1.0 kcal/mol. The vertical and adiabatic singlet-triplet separation energies of ethylene were calculated as Delta ES-T,vert = 104.1 and Delta ES-T,adia = 65.8 kcal/mol. These results are in excellent agreement with recent quantum Monte Carlo (DMC) values of 103.5 +- 0.3 and 66.4 +- 0.3 kcal/mol. Both sets of computational values differ from the experimental estimate of 58 +- 3 kcal/mol for the adiabatic splitting. The computed singlet-triplet gap at 0 K for acetylene is Delta ES-T,adia(C2H2) = 90.5 kcal/mol, which is in notable disagreement with the experimental value of 82.6 kcal/mol. The heat of formation of the triplet is Delta H0f(C2H2,3B2) = 145.3 kcal/mol. There is a systematic underestimation of the singlet-triplet gaps in recent photodecomposition experiments by ~;;7 to 8 kcal/mol. For vinylidene, we predict Delta H0f(H2CC,1A1) = 98.8 kcal/mol at 298 K (exptl. 100.3 +- 4.0), Delta H0f(H2CC,3B2) = 146.2 at 298 K, and an energy gap Delta ES-T-adia(H2CC) = 47.7 kcal/mol.

Nguyen, M.T.; Matus, M.H.; Lester Jr, W.A.; Dixon, David A.

2007-06-28

140

Rhenium-Catalyzed anti-Markovnikov Addition Reaction of Methanetricarboxylates to Unactivated Terminal Acetylenes.  

PubMed

A novel anti-Markovnikov addition reaction of methanetricarboxylates with terminal acetylenes under neutral conditions was achieved using a rhenium complex. This transformation represents a rare example of intermolecular anti-Markovnikov addition of carbon nucleophiles to unactivated terminal acetylenes. 1,3-Diesters having bulky substituents at the active methylene carbon are also applicable as substrates to provide anti-Markovnikov adducts as single regio- and stereoisomers. Preliminary mechanistic studies imply that the rhenium vinylidene species is the key intermediate in the current catalytic cycle. PMID:25563809

Hori, Shunsuke; Murai, Masahito; Takai, Kazuhiko

2015-02-01

141

In vivo tumour and metastasis reduction and in vitro effects on invasion assays of the ruthenium RM175 and osmium AFAP51 organometallics in the mammary cancer model.  

PubMed

We have compared the organometallic arene complexes [(eta(6)-biphenyl)M(ethylenediamine)Cl](+) RM175 (M=Ru(II)) and its isostructural osmium(II) analogue AFAP51 (M=Os(II)) for their ability to induce cell detachment resistance from fibronectin, collagen IV and poly-l-lysine, and cell re-adhesion after treatment, their effects on cell migration and cell viability, on matrix metalloproteinases production, and on primary tumour growth of MCa mammary carcinoma, the effect of human serum albumin on their cytotoxicity. There are differences between ruthenium and osmium. The Os complex is up to 6x more potent than RM175 towards highly-invasive breast MDA-MB-231, human breast MCF-7 and human epithelial HBL-100 cancer cells, but whereas RM175 was active against MCa mammary carcinoma in vivo and caused metastasis reduction, AFAP51 was not. Intriguingly the presence of human serum albumin in the growth medium enhanced the cytotoxicity of both compounds. RM175 increased the resistance of MDA-MB-231 cells to detachment from substrates and both compounds inhibited the production of MMP-2. These data confirm the key role of ruthenium itself in anti-metastatic activity. It will be interesting to explore the activity of osmium arene complexes in other tumour models and the possibility of changing the non-arene ligands to tune the anticancer activity of osmium in vivo. PMID:19906432

Bergamo, A; Masi, A; Peacock, A F A; Habtemariam, A; Sadler, P J; Sava, G

2010-01-01

142

79 Br and 127 I nqr spectra in series of acetylene derivatives  

Microsoft Academic Search

The complete79Br and127I NQR spectra of a number of bromo and iodo derivatives of acetylene were studied for the first time, and the field constants of the NQR frequencies were determined. It was found that the asymmetry parameters in them are low. Changes in the field constants are determined by the competing conjugation of the iodine atom and the corresponding

G. K. Semin; S. A. Petukhov; S. I. Gushchin; I. R. Gol'ding; E. V. Bryukhova; A. M. Sladkov

1983-01-01

143

Stereoselective Synthesis of Vinylsilanes by a Gold(I)-Catalyzed Acetylenic Sila-Cope Rearrangement  

E-print Network

Stereoselective Synthesis of Vinylsilanes by a Gold(I)-Catalyzed Acetylenic Sila-Cope Rearrangement- coupling reactions.1 The application of these reactions to stereo- selective olefin synthesis is contingent reactions to the stereoselective synthesis of olefins substituted with the allyl group cis to silicon

Toste, Dean

144

Association Mechanisms of Unsaturated C2 Hydrocarbons with Their Cations: Acetylene and Ethylene  

NASA Technical Reports Server (NTRS)

The ion-molecule association mechanism of acetylene and ethylene with their cations is investigated by ab initio quantum chemical methods to understand the structures, association energies, and the vibrational and electronic spectra of the products. Stable puckered cyclic isomers are found as the result of first forming less stable linear and bridge isomers. The puckered cyclic complexes are calculated to be strongly bound, by 87, 35 and 56 kcal/mol for acetylene-acetylene cation, ethylene-ethylene cation and acetylene-ethylene cation, respectively. These stable complexes may be intermediates that participate in further association reactions. There are no association barriers, and no significant inter-conversion barriers, so the initial linear and bridge encounter complexes are unlikely to be observable. However, the energy gap between the bridged and cyclic puckered isomers greatly differs from complex to complex: it is 44 kcal/mol in C4H4 +, but only 6 kcal/mol in C4H8 +. The accurate CCSD(T) calculations summarized above are also compared against less computationally expensive MP2 and density functional theory (DFT) calculations for structures, relative energies, and vibrational spectra. Calculated vibrational spectra are compared against available experiments for cyclobutadiene cation. Electronic spectra are also calculated using time-dependent DFT.

Bera, Partha P.; Head-Gordon, Martin; Lee, Timothy J.

2013-01-01

145

Acetylene-Accelerated Alcohol Catalytic CVD Growth of Vertically Aligned Single-Walled  

E-print Network

- 1 - Acetylene-Accelerated Alcohol Catalytic CVD Growth of Vertically Aligned Single-Walled Carbon partial pressure resulted in negligible growth and quickly deactivated the catalyst. The dormant catalyst that vertically-aligned SWNT arrays were obtained, first from alcohol catalytic chemical vapor deposition (ACCVD

Maruyama, Shigeo

146

Methane emissions measured at two California landfills by OTM-10 and an acetylene tracer method  

EPA Science Inventory

Methane emissions were measured at two municipal solid waste landfills in California using static flux chambers, an optical remote sensing approach known as vertical radial plume mapping (VRPM) using a tunable diode laser (TDL) and a novel acetylene tracer method. The tracer meth...

147

Reactor design and energy concepts for a plasma process of acetylene black production  

Microsoft Academic Search

Acetylene black can be produced from methane decomposition in a plasma reactor. Different types of plasma reactor are designed for this purpose and a parametric analysis of the system is made. Carbon yield in the reactor seems to be dependent on methane flow rate and plasma power. The results obtained from various types of material analysis of the product obtained

K. Shakourzadeh Bolouri; J. Amouroux

1986-01-01

148

Saturated absorption spectroscopy of acetylene gas inside large-core photonic bandgap fiber  

Microsoft Academic Search

Saturated absorption spectroscopy is performed on the acetylene nu1 + nu3 band near 1532 nm inside photonic bandgap fibers of small (~10 mum) and large (~20 mum) core diameters. The observed linewidths are narrower in the 20 mum fiber and vary from 20 to 40 MHz depending on pressure and power. Variations in the background light transmission, attributed by others

Rajesh Thapa; Kevin Knabe; Mohammed Faheem; Ahmer Naweed; Oliver L. Weaver; Kristan L. Corwin

2006-01-01

149

Surface studies of the reactivity of methyl, acetylene and atomic hydrogen at CVD diamond surfaces  

Microsoft Academic Search

The chemical reactions occurring at a CVD diamons surface exposed to methyl and acetylene species have been studied under high vacuum conditions, primarily using isotope scrambling, reactive beam scattering and computer simulation techniques. The influence of a H\\/D atom flux on the processes observed has also been studied. Methyl radicals are observed to adsorb readily on hydrogen-free and hydrogenated diamond

J. S. Foord; K. P. Loh; R. B. Jackman

1998-01-01

150

Growth of diamond films using an enclosed methyl-acetylene and propadiene combustion flame  

E-print Network

1 Growth of diamond films using an enclosed methyl-acetylene and propadiene combustion flame K Abstract Diamond growth in low pressure combustion flames was studied using a safer, more economical diamond films on a heated molybdenum substrate. This work identifies the dependence of film growth rate

Dandy, David

151

TOXICITY OF ACETYLENIC ALCOHOLS TO THE FATHEAD MINNOW, PIMEPHALES PROMELAS: NARCOSIS AND PROELECTROPHILE ACTIVATION  

EPA Science Inventory

The 96-h LC50 values for 16 acetylenic alcohols in the fathead minnow (Pimephales promelas) were determined using continuous-flow diluters. The measured LC50 values for seven tertiary propargylic alcohols agreed closely with the QSAR predictions based upon data for other organic ...

152

Synthesis of substituted acetylenic epoxides followed by indium-catalyzed rearrangement to 2,3,5-trisubstituted furans.  

PubMed

Syntheses of various aromatic and aliphatic 2,3,5-trisubstituted furans from acetylenic epoxides are described. These epoxides are directly prepared by nucleophilic ring closure of propargylic alkoxides generated by lithium acetylide addition to ?-haloketones. PMID:21384932

Kang, Jun Yong; Connell, Brian T

2011-04-01

153

Nonstationary coherent optical effects caused by pulse propagation through acetylene-filled hollow-core photonic-crystal fibers  

NASA Astrophysics Data System (ADS)

Experimental observations of nonstationary coherent optical phenomena, i.e., optical nutation, free induction, and photon echo, in the acetylene (12C2H2) filled hollow-core photonic-crystal fiber (PCF) are reported. The presented results were obtained for the acetylene vibration-rotational transition P9 at wavelength 1530.37 nm at room temperature under a gas pressure of <0.5 Torr. An all-fiber pumped-through cell based on the commercial 2.6-m-long PCF with a 10-?m hollow-core diameter was used. The characteristic relaxation time T2 during which the optical coherent effects were typically observed in our experiments was estimated to be ?8 ns. This time is governed by the limited time of the acetylene molecules' presence inside the effective PCF modal area and by intermolecule collisions. An accelerated attenuation of the optical nutation oscillations is explained by a random orientation of acetylene molecules.

Ocegueda, M.; Hernandez, E.; Stepanov, S.; Agruzov, P.; Shamray, A.

2014-06-01

154

The photolysis of NH3 in the presence of substituted acetylenes - A possible source of oligomers and HCN on Jupiter  

NASA Technical Reports Server (NTRS)

An NMR spectral study is presently conducted of NH3 photolysis in the presence of substituted acetylenes with NMR spectra and gas chromatography. Quantum yields and percentage conversions to products are reported. It is shown that acetylenic hydrocarbons generated during methane photolysis in Jupiter's stratosphere can react with radicals formed by NH3 photolysis to yield nonvolatile, yellow-brown polymers, alkylnitriles, and in due course, HCN, as observed on Jupiter.

Ferris, James P.; Jacobson, Richard R.; Guillemin, Jean C.

1992-01-01

155

A detailed kinetic modeling study of aromatics formation in laminar premixed acetylene and ethylene flames  

SciTech Connect

A computational study was performed for the formation and growth of polycyclic aromatic hydrocarbons (PAHs) in laminar premixed acetylene and ethylene flames. A new detailed reaction mechanism describing fuel pyrolysis and oxidation, benzene formation, and PAH mass growth and oxidation is presented and critically tested. It is shown that the reaction model predicts reasonably well the concentration profiles of major and intermediate species and aromatic molecules in a number of acetylene and ethylene flames reported in the literature. It is demonstrated that reactions of n-C{sub 4}H{sub x} + C{sub 2}H{sub 2} leading to the formation of one-ring aromatics are as important as the propargyl recombination, and hence must be included in kinetic modeling of PAH formation in hydrocarbon flames. It is further demonstrated that the mass growth of PAHs can be accounted for by the previously proposed H-abstraction-C{sub 2}H{sub 2}-addiction mechanism.

Wang, H. [Univ. of Delaware, Newark, DE (United States). Dept. of Mechanical Engineering] [Univ. of Delaware, Newark, DE (United States). Dept. of Mechanical Engineering; Frenklach, M. [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering] [Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

1997-07-01

156

Isotope effect in normal-to-local transition of acetylene bending modes  

DOE PAGESBeta

The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helps to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement.

Ma, Jianyi [University of New Mexico, Albuquerque, NM, (United States); Xu, Dingguo [University of New Mexico, Albuquerque, NM, (United States) and Sichuan Univ. (China); Guo, Hua [University of New Mexico, Albuquerque, NM, (United States); Tyng, Vivian [Univ. of Oregon, Eugene, OR (United States); Kellman, Michael E. [Univ. of Oregon, Eugene, OR (United States)

2012-01-03

157

Acetylene-terminated low-stress polyimide oligomer for interlayer dielectric applications  

Microsoft Academic Search

The authors describe a novel low-stress, acetylene-terminated polyimide well suited as the interlayer dielectric for MCMs (multichip modules). For successful application as an interlayer dielectric in a high-density microelectronic package, organic polymers must possess a variety of demanding properties, e.g. processibility, mechanical strength, adhesion, low dielectric constant, low water absorption, minimal outgassing, low thermal expansion, etc. The appropriate balance of

P. G. Jobe; C. Puglisi; J. McMahon; R. D. Rossi

1991-01-01

158

Vacuum-Ultraviolet Chemiluminescence in the Reaction of Atomic Oxygen with Acetylene  

Microsoft Academic Search

Vacuum-ultraviolet emission from the reaction of atomic oxygen with acetylene was investigated spectrographically and with photoionization detectors. The spectrum was observed at wavelengths above 1400 Å and consisted entirely of bands belonging to the fourth positive system of CO. At short wavelengths, the intensity declines rapidly, but radiation was detected with photoionization detectors filled with xylene (1425–1475 Å), NO (1100–1340

F. F. Marmo; J. P. Padur; P. Warneck

1967-01-01

159

High resolution spectroscopic detection of acetylene-vinylidene isomerization by spectral cross correlation  

NASA Astrophysics Data System (ADS)

Information about the unimolecular acetylene (HC 3/4 CH)?vinylidene (H2C=C:) isomerization on the S0 energy surface has been extracted from vibrationally unassigned high resolution stimulated emission pumping (SEP) spectra of acetylene. The combination of a new pattern recognition scheme, spectral cross correlation (SCC) with complete nuclear permutation-inversion (CNPI) group theory is shown to be a powerful new technique for characterizing bond rearrangement in highly vibrationally excited normally rigid polyatomic molecules. SCC detects isomerization ``resonances'' which destroy an approximate vibrational symmetry (e.g., the number of cis-bending quanta). The energies (relative to the zero point level of the stablest isomer) and widths of such resonances provide information about the ``energies'' of isomer rovibrational levels and the isomer-level-specific isomerization rate. Vinylidene isomerization resonances may be distinguished from ordinary acetylene Fermi or Coriolis perturbations by a unique rotational symmetry dependence due to the correlation between acetylene [D?h(M)] and vinylidene [C2v(M)] levels in the CNPI group G8. An SCC map of the HCCH S0 15 000-15 900 cm-1 energy region above the zero point level was obtained by comparing SEP spectra recorded via S1(Ã 1Au)33 and 2162 Ka=1 intermediate levels. The predicted rotational symmetry dependence of the SCC was found between 15 410-15 640 cm-1, but the vinylidene resonance line shape was obscured by Franck-Condon interference effects from well known perturbations between the 33 and 2162 SEP intermediate levels. It was therefore not yet possible to determine the height of the isomerization barrier (or even whether a barrier exists) but an upper bound for the vinylidene zero point level of 15 525 cm-1 was inferred from the SCC data.

Chen, Yongqin; Jonas, David M.; Kinsey, J. L.; Field, R. W.

1989-10-01

160

Toward spectroscopically accurate global ab initio potential energy surface for the acetylene-vinylidene isomerization  

NASA Astrophysics Data System (ADS)

A new full-dimensional global potential energy surface (PES) for the acetylene-vinylidene isomerization on the ground (S0) electronic state has been constructed by fitting ˜37 000 high-level ab initio points using the permutation invariant polynomial-neural network method with a root mean square error of 9.54 cm-1. The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES. Furthermore, acetylene vibrational energy levels have been calculated using the Lanczos algorithm with an exact (J = 0) Hamiltonian. The vibrational energies up to 12 700 cm-1 above the zero-point energy are in excellent agreement with the experimentally derived effective Hamiltonians, suggesting that the PES is approaching spectroscopic accuracy. In addition, analyses of the wavefunctions confirm the experimentally observed emergence of the local bending and counter-rotational modes in the highly excited bending vibrational states. The reproduction of the experimentally derived effective Hamiltonians for highly excited bending states signals the coming of age for the ab initio based PES, which can now be trusted for studying the isomerization reaction.

Han, Huixian; Li, Anyang; Guo, Hua

2014-12-01

161

Models for reactions of acetylene on platinum(111): the vinylidene intermediate  

SciTech Connect

One of the most studied surface reactions is that of acetylene on platinum(111). A ..mu../sub 3/-eta/sup 2/-acetylene complex is formed at low temperature but this rearranges on warming to a ..mu../sub 3/-eta/sup 2/-vinylidene, Pt/sub 3/(..mu../sub 3/-eta/sup 2/-C=CH/sub 2/), which then reacts with surface-bound hydrogen to give a ..mu../sub 3/-ethylidyne, Pt/sub 3/(..mu../sub 3/-CMe). Since the cluster (Pt/sub 3/(..mu../sub 3/-H)(..mu..-dppm)/sub 3/)/sup +/ (dppm = Ph/sub 2/PCH/sub 2/PPh/sub 2/) acts as a useful model for the triply bridging sites on a Pt(111) surface, a study of its reaction with acetylene was initiated with the aim of isolating complexes having the above functional groups, none of which appears to be known. This article reports the formation of a stable ..mu../sub 3/-eta/sup 2/-C=CH/sub 2/ complex.

Rashidi, M.; Puddephatt, R.J.

1986-10-29

162

Functionalized acetylenic compounds via 1-bromo- 1,2-dienes and organocopper reagents  

SciTech Connect

The acetylenic unity provides a convenient handle which may be converted into a variety of functionalities. In this frame, the authors developed a general and efficient method for the synthesis of chiral 1-alkynes, with a tertiary or a quaternary asymmetric carbon atom in the {alpha} position to the triple bond, by stereoselective cross-coupling of bromocuprates [(RCuBr)MaBr LiBr R=Alkyl, aryl] with optically active 1-bromo-1,2-dienes. This method provides terminal acetylenes which can easily converted into biologically active compounds, such as the antiphlogistic (+)-Ibuprofen. The authors report here that this procedure can be extended to the preparation of a large variety of functionalized acetylenic systems. In fact, bromocuprates, obtained from protected functionalized Grignard reagents and LiCuBr{sub 2}, react with bromoallenes affording the 1-alkynes with high yields, regio- and stereoselectivity. Compounds are also conveniently obtained from cyanocuprates, prepared by reaction of functionalized zinc reagents with the cuprous cyanide/lithium chloride complex; the organozinc derivatives are directly obtained from organic halides and highly activated zinc powder, prepared by metal vapour technique.

Caporusso, A.M.; Iodice, A.; Lardicci, L.; Salvadori, P. [Chimica Industriale dell` Universita, Pisa (Italy)

1995-12-31

163

Toward spectroscopically accurate global ab initio potential energy surface for the acetylene-vinylidene isomerization.  

PubMed

A new full-dimensional global potential energy surface (PES) for the acetylene-vinylidene isomerization on the ground (S0) electronic state has been constructed by fitting ?37 000 high-level ab initio points using the permutation invariant polynomial-neural network method with a root mean square error of 9.54 cm(-1). The geometries and harmonic vibrational frequencies of acetylene, vinylidene, and all other stationary points (two distinct transition states and one secondary minimum in between) have been determined on this PES. Furthermore, acetylene vibrational energy levels have been calculated using the Lanczos algorithm with an exact (J = 0) Hamiltonian. The vibrational energies up to 12 700 cm(-1) above the zero-point energy are in excellent agreement with the experimentally derived effective Hamiltonians, suggesting that the PES is approaching spectroscopic accuracy. In addition, analyses of the wavefunctions confirm the experimentally observed emergence of the local bending and counter-rotational modes in the highly excited bending vibrational states. The reproduction of the experimentally derived effective Hamiltonians for highly excited bending states signals the coming of age for the ab initio based PES, which can now be trusted for studying the isomerization reaction. PMID:25554156

Han, Huixian; Li, Anyang; Guo, Hua

2014-12-28

164

Pulse-induced nonequilibrium dynamics of acetylene inside carbon nanotube studied by an ab initio approach  

PubMed Central

Nanoscale molecular confinement substantially modifies the functionality and electronic properties of encapsulated molecules. Many works have approached this problem from the perspective of quantifying ground-state molecular changes, but little is known about the nonequilibrium dynamics of encapsulated molecular system. In this letter, we report an analysis of the nonequilibrium dynamics of acetylene (C2H2) inside a semiconducting carbon nanotube (CNT). An ultrashort high-intense laser pulse (2 fs width and 1015 W/cm2 intensity) brings the systems out of equilibrium. This process is modeled by comprehensive first-principles time-dependent density-functional simulations. When encapsulated, acetylene dimer, unlike a single acetylene molecule, exhibits correlated vibrational dynamics (C–C bond rotation and H–C–C bending) that is markedly different from the dynamics observed in the gas phase. This result highlights the role of CNT in modulating the optical electric field within the tube. At longer simulation timescales (> 20 fs) in the largest-diameter tube studied here [CNT(14,0)], we observe synchronized rotation about the C–C axes in the dimer and ultimately ejection of one of the four hydrogen atoms. Our results illustrate the richness of photochemical phenomena in confined geometries. PMID:22615352

Miyamoto, Yoshiyuki; Zhang, Hong; Rubio, Angel

2012-01-01

165

Fragmentation processes following core excitation in acetylene and ethylene by partial ion yield spectroscopy  

NASA Astrophysics Data System (ADS)

Partial ion yield spectroscopy provides a very detailed picture of fragmentation processes following core excitation in isolated molecules. We exploit this potential in the analysis of decay processes following C1s[right arrow]pi and C1s[right arrow]Rydberg excitations in ethylene and acetylene. We show that the relative intensity of spectral features related to the excitation to empty molecular orbitals or to Rydberg states is a function of the time variation of the fragmentation process. Namely, we see an intensity increase in the Rydberg states compared to the molecular orbitals as the fragmentation process becomes more extensive, a result attributable to the diffuse nature of the Rydberg virtual orbitals, which makes spectator decay more likely than participator decay. Therefore, the number of dissociative final states that can be reached from Rydberg excitation is higher than for excitation to empty molecular orbitals. In acetylene, we obtain the first direct evidence of the presence of a sigma* excitation embedded in the Rydberg series. The formation of the fragment H2+ in ethylene occurs following a recombination process, while in acetylene it is related to excess vibrational energy stored in the intermediate state. Furthermore, we can use the enhancement in channels corresponding to doubly charged species as an indication for the presence of shape resonances.

Piancastelli, M. N.; Stolte, W. C.; Ohrwall, G.; Yu, S.-W.; Bull, D.; Lantz, K.; Schlachter, A. S.; Lindle, D. W.

2002-11-01

166

Growth of ammonia-oxidizing archaea in soil microcosms is inhibited by acetylene.  

PubMed

Autotrophic ammonia-oxidizing bacteria were considered to be responsible for the majority of ammonia oxidation in soil until the recent discovery of the autotrophic ammonia-oxidizing archaea. To assess the relative contributions of bacterial and archaeal ammonia oxidizers to soil ammonia oxidation, their growth was analysed during active nitrification in soil microcosms incubated for 30 days at 30 degrees C, and the effect of an inhibitor of ammonia oxidation (acetylene) on their growth and soil nitrification kinetics was determined. Denaturing gradient gel electrophoresis (DGGE) analysis of bacterial ammonia oxidizer 16S rRNA genes did not detect any change in their community composition during incubation, and quantitative PCR (qPCR) analysis of bacterial amoA genes indicated a small decrease in abundance in control and acetylene-containing microcosms. DGGE fingerprints of archaeal amoA and 16S rRNA genes demonstrated changes in the relative abundance of specific crenarchaeal phylotypes during active nitrification. Growth was also indicated by increases in crenarchaeal amoA gene copy number, determined by qPCR. In microcosms containing acetylene, nitrification and growth of the crenarchaeal phylotypes were suppressed, suggesting that these crenarchaea are ammonia oxidizers. Growth of only archaeal but not bacterial ammonia oxidizers occurred in microcosms with active nitrification, indicating that ammonia oxidation was mostly due to archaea in the conditions of the present study. PMID:19656195

Offre, Pierre; Prosser, James I; Nicol, Graeme W

2009-10-01

167

Polycyclic propargylamine and acetylene derivatives as multifunctional neuroprotective agents.  

PubMed

The aim of this study was to design drug-like molecules with multiple neuroprotective mechanisms which would ultimately inhibit N-methyl-D-aspartate (NMDA) receptors, block L-type voltage gated calcium channels (VGCC) and inhibit apoptotic processes as well as the monoamine oxidase-B (MAO-B) enzyme in the central nervous system. These types of compounds may act as neuroprotective and symptomatic drugs for disorders such as Alzheimer's and Parkinson's disease. In designing the compounds we focused on the structures of rasagiline and selegiline, two well known MAO-B inhibitors and proposed neuroprotective agents. Based on this consideration, the compounds synthesised all contain the propargylamine functional group of rasagiline and selegiline or a derivative thereof, conjugated to various polycyclic cage moieties. Being non-polar, these polycyclic moieties have been shown to aid in the transport of conjugated compounds across the blood-brain barrier, as well as cell membranes and have secondary positive neuroprotective effects. All novel synthesised polycyclic derivatives proved to have significant anti-apoptotic activity (p < 0.05) which was comparable to the positive control, selegiline. Four compounds (12, 15 and 16) showed promising VGCC and NMDA receptor channel inhibitory activity ranging from 18% to 59% in micromolar concentrations and compared favourably to the reference compounds. In the MAO-B assay, 8-phenyl-ethynyl-8-hydroxypentacycloundecane (10), exhibited MAO-B inhibition of 73.32% at 300 ?M. This compound also reduced the percentage of apoptotic cells by as much as 40% when compared to the control experiments. PMID:24769350

Zindo, Frank T; Barber, Quinton R; Joubert, Jacques; Bergh, Jacobus J; Petzer, Jacobus P; Malan, Sarel F

2014-06-10

168

Formation of Complex Organics by Gas Phase and Intracluster Ion-Molecule Reactions Involving Acetylene and Hydrogen Cyanide  

NASA Astrophysics Data System (ADS)

Many complex organics including polycyclic aromatic hydrocarbons are present in flames and combustion processes as well as in interstellar clouds and solar nebulae. Here, we present evidence for the formation of complex covalent organics by gas phase and intracluster reactions of the benzene, phenylium, pyridine, pyrimidine, phenylacetylene and benzonitrile cations with acetylene and hydrogen cyanide molecules. These reactions are studied using mass-selected ion mobility, chemical reactivity, collisional dissociation, and ab initio calculations. Measurements of collision cross sections in helium provide structural information on the adducts and allow probing structural changes at different temperatures (isomerization). We observed multiple additions of five acetylene molecules on the pyridine cation at room temperature. This is a remarkable result considering that only two acetylene molecules were added to the phenyl cation and no addition was observed on the benzene cation at room temperature. The experimental results are in full agreement with the ab initio calculations which predict that the first and second acetylenes add to the pyridine ion in barrierless, highly exothermic reactions. Similar reactions have been observed for the pyrimidine radical cation although the extent of the addition reactions is limited to only two acetylene molecules at room temperature. The results provide the first evidence for the incorporation of nitrogen in the formation cyclic hydrocarbons via the gas phase reactions of pyridine and pyrimidine ions with acetylene molecules. In addition, the formation of covalent adducts in the ionized acetylene/HCN system will be reported for the first time. Sequential reactions leading to the formation of pyridine and pyrimidine radical cations and higher adducts are observed over a wide range of temperature and pressure. The formation of these covalent adducts may represent a general class of addition reactions that can form complex heterocyclic species in ionizing environments.

El-Shall, S.; Hamed, A.; Soliman, A. R.; Momoh, P. O.

2011-05-01

169

Evidence for partial quenching of orbital angular momentum upon complex formation in the infrared spectrum of OH-acetylene.  

PubMed

The entrance channel leading to the addition reaction between the hydroxyl radical and acetylene has been examined by spectroscopic characterization of the asymmetric CH stretching band of the pi-hydrogen bonded OH-acetylene reactant complex. The infrared action spectrum observed at 3278.6 cm(-1) (origin) consists of seven peaks of various intensities and widths, and is very different from those previously reported for closed-shell HF/HCl-acetylene complexes. The unusual spectrum arises from a partial quenching of the OH orbital angular momentum in the complex, which in turn is caused by a significant splitting of the OH monomer orbital degeneracy into (2)A(') and (2)A(") electronic states. The magnitude of the (2)A(')-(2)A(") splitting as well as the A rotational constant for the OH-acetylene complex are determined from the analysis of this b-type infrared band. The most populated OH product rotational state, j(OH)=9/2, is consistent with intramolecular vibrational energy transfer to the nu2 C triple bonded C stretching mode of the departing acetylene fragment. The lifting of the OH orbital degeneracy and partial quenching of its electronic orbital angular momentum indicate that the electronic changes accompanying the evolution of reactants into products have begun to occur in the reactant complex. PMID:15367011

Marshall, Mark D; Davey, James B; Greenslade, Margaret E; Lester, Marsha I

2004-09-22

170

Evidence for partial quenching of orbital angular momentum upon complex formation in the infrared spectrum of OH-acetylene  

NASA Astrophysics Data System (ADS)

The entrance channel leading to the addition reaction between the hydroxyl radical and acetylene has been examined by spectroscopic characterization of the asymmetric CH stretching band of the ?-hydrogen bonded OH-acetylene reactant complex. The infrared action spectrum observed at 3278.6 cm-1 (origin) consists of seven peaks of various intensities and widths, and is very different from those previously reported for closed-shell HF/HCl-acetylene complexes. The unusual spectrum arises from a partial quenching of the OH orbital angular momentum in the complex, which in turn is caused by a significant splitting of the OH monomer orbital degeneracy into 2A' and 2A? electronic states. The magnitude of the 2A'-2A? splitting as well as the A rotational constant for the OH-acetylene complex are determined from the analysis of this b-type infrared band. The most populated OH product rotational state, jOH=9/2, is consistent with intramolecular vibrational energy transfer to the ?2 C?C stretching mode of the departing acetylene fragment. The lifting of the OH orbital degeneracy and partial quenching of its electronic orbital angular momentum indicate that the electronic changes accompanying the evolution of reactants into products have begun to occur in the reactant complex.

Marshall, Mark D.; Davey, James B.; Greenslade, Margaret E.; Lester, Marsha I.

2004-09-01

171

Acetylene and oxygen as inhibitors of nitrous oxide production in Nitrosomonas europaea and Nitrosospira briensis: a cautionary tale.  

PubMed

Autotrophic ammonia-oxidizing bacteria produce nitrous oxide (N(2)O) as a by-product of nitrification or as an intermediate of nitrifier denitrification. In soil incubations, acetylene (C(2)H(2)) and large partial pressures of oxygen (O(2)) are used to distinguish between these sources. C(2)H(2) inhibits ammonia oxidation and should therefore inhibit N(2)O production by both nitrification and nitrifier denitrification. O(2) suppresses the reduction pathway of nitrifier denitrification. However, doubts concerning the reliability of C(2)H(2) and O(2) as inhibitors have arisen recently. Therefore, in this study we tested the influence of C(2)H(2) and large partial pressures of O(2) alone and in combination on N(2)O production in pure cultures of the ammonia oxidizers Nitrosomonas europaea and Nitrosospira briensis. C(2)H(2) largely inhibited nitrite production in both ammonia oxidizers and N(2)O production by N. europaea. Surprisingly, it did not affect the N(2)O production in N. briensis. The variable response of ammonia oxidizers to C(2)H(2) might have consequences for the use of C(2)H(2) as an inhibitor of nitrification in soils. Different partial pressures of O(2) ranging from less than 10 kPa O(2) to 100 kPa O(2) were tested for their effectiveness in inhibiting N(2)O production via nitrifier denitrification. The partial pressure of 100 kPa O(2) yielded minimal N(2)O production by both ammonia-oxidizing species and seemed to inhibit N(2)O emission from nitrifier denitrification to a large extent. However, a negative effect of 100 kPa O(2) on ammonia oxidation itself could not be excluded. The applicability of both inhibitors in determining N(2)O production pathways in soils is discussed. PMID:19712342

Wrage, Nicole; Velthof, Gerard L; Oenema, Oene; Laanbroek, Hendrikus J

2004-01-01

172

Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix C  

NASA Technical Reports Server (NTRS)

The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2000-01-01

173

Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix H  

NASA Technical Reports Server (NTRS)

The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation-O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

Xu, F.; Faeth, G. M.; Yuan, Z.-G. (Technical Monitor); Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2001-01-01

174

Soot Formation in Laminar Acetylene/Air Diffusion Flames at Atmospheric Pressure. Appendix J  

NASA Technical Reports Server (NTRS)

The flame structure and soot-formation (soot nucleation and growth) properties of axisymmetric laminar coflowing jet diffusion flames were studied experimentally. Test conditions involved acetylene-nitrogen jets burning in coflowing air at atmospheric pressure. Measurements were limited to the axes of the flames and included soot concentrations, soot temperatures, soot structure, major gas species concentrations, radical species (H, OH, and O) concentrations, and gas velocities. The results show that as distance increases along the axes of the flames, detectable soot formation begins when significant H concentrations are present, and ends when acetylene concentrations become small. Species potentially associated with soot oxidation--O2, CO2, H2O, O, and OH-are present throughout the soot-formation region so that soot formation and oxidation proceed at the same time. Strong rates of soot growth compared to soot nucleation early in the soot-formation process, combined with increased rates of soot nucleation and oxidation as soot formation proceeds, causes primary soot particle diameters to reach a maximum relatively early in the soot-formation process. Aggregation of primary soot particles proceeds, however, until the final stages of soot oxidation. Present measurements of soot growth (corrected for soot oxidation) in laminar diffusion flames were consistent with earlier measurements of soot growth in laminar premixed flames and exhibited encouraging agreement with existing hydrogen-abstraction/carbon-addition (HACA) soot growth mechanisms in the literature that were developed based on measurements within laminar premixed flames. Measured primary soot particle nucleation rates in the present laminar diffusion flames also were consistent with corresponding rates measured in laminar premixed flames and yielded a crude correlation in terms of acetylene and H concentrations and the temperature.

Xu, F.; Faeth, G. M.; Urban, D. L. (Technical Monitor); Yuan, Z.-G. (Technical Monitor)

2001-01-01

175

Using saturated absorption spectroscopy on acetylene-filled hollow-core fibers for absolute frequency measurements  

NASA Astrophysics Data System (ADS)

Current portable near-infrared optical frequency references offer modest accuracy and instability compared to laboratory references. Low pressure reference cells are necessary to realize features narrower than the Doppler broadened overtone transitions, and most setups to date have occurred in free-space. Hollow-core photonic crystal fibers offer a potential alternative to free-space setups through their small cores (˜10's of mum) and low-loss guidance. Furthermore, HC-PCF can be made into fiber cells that could be directly integrated into existing telecommunications networks. Efforts were made to fabricate these fiber cells with a low pressure of molecules trapped inside, but this has proven to be quite challenging. Therefore, investigation of these fibers is conducted by placing the ends of the fiber inside vacuum chambers loaded with acetylene (12C2H2). The linewidths of several P branch nu1 +nu3 transitions (near 1.5 mum) are investigated as a function of acetylene pressure and optical pump power in three different HC-PCFs. Frequency modulation spectroscopy is then implemented on the acetylene-filled HC-PCF to generate sub-Doppler dispersion features that are useful for frequency stabilization using standard servo electronics. Instability and accuracy of this near-IR optical reference were then determined by analysis of heterodyne experiments conducted with frequency combs referenced to a GPS-disciplined rubidium oscillator. The instability and accuracy of this HC-PCF reference are within an order of magnitude of free-space experiments, as expected based on the ratio of linewidths observed in the two experiments. Therefore, HC-PCF has been shown to be suitable for potential frequency references. Further work is necessary to fabricate gas fiber cells with high optical transmission and low molecular contamination.

Knabe, Kevin

176

Mechanisms of. pi. -bond oxidation by cytochrome p-450: acetylenes as probes  

SciTech Connect

Phenylacetylene and biphenylacetylene are oxidized by microsomal and purified P-450 to the corresponding arylacetic acids. During this transformation, the acetylenic hydrogen undergoes a 1,2 shift which causes a kinetic isotope effect of 1.8 on the overall enzymatic rate. The same products and kinetic isotope effects are observed when the arylacetylenes are oxidized by m-chloroperbenzoic acid. Suicide inactivation of P-450 by the arylacetylenes, which occurs simultaneously with metabolite formation, is insensitive to isotopic substitution so the partition ratio changes from 26 for phenylacetylene of 14 for (1-/sup 2/H) phenylacetylene.

Komives, E.A.

1987-01-01

177

A new acetylenic compound from the rhizomes of Atractylodes chinensis and its absolute configuration.  

PubMed

A new acetylenic compound "atractyloyne", (3S,4E,6E,12E)-1-isovaleryloxy-tetradeca-4,6,12-triene-8,10-diyne-3,14-diol (1) was isolated from the rhizomes of Atractylodes chinensis (Compositae) together with a known compound (4E,6E,12E)-3-isovaleryloxy-tetradeca-4,6,12-triene-8,10-diyne-1,14-diol (2). These structures were determined on the basis of the spectroscopic data and chemical evidence, and the absolute configuration of 1 was established by the modified 2-methoxy-2-trifluoromethylphenylacetic acid (MTPA) method. PMID:16327194

Nakai, Yoichiro; Sakakibara, Iwao; Hirakura, Kazuhiro; Terabayashi, Susumu; Takeda, Shuichi

2005-12-01

178

A versatile gold synthon for acetylene C-H bond activation.  

PubMed

The reaction of N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene gold hydroxide ([Au(OH)(IPr)]; 1) with acetylene and trimethylsilylacetylene derivatives cleanly leads to the formation of a gold-acetylide bond with the concomitant formation of water or trimethylsilanol. All compounds were isolated in high yield (>85%). The crystal structures of selected gold acetylides in conjunction with their UV-vis absorption/emission properties were investigated. Finally, DFT calculations were performed in an attempt to gain an insight into the mechanism of the general reaction. PMID:20922211

Fortman, George C; Poater, Albert; Levell, Jack W; Gaillard, Sylvain; Slawin, Alexandra M Z; Samuel, Ifor D W; Cavallo, Luigi; Nolan, Steven P

2010-11-21

179

Solid-state NMR studies of the adsorption of acetylene on platinum/alumina catalysts  

E-print Network

/y-alumina and subsequently evacuated. 25 "C Bloch Decay/MAS NMR spectra of cyclohexane adsorbed onto 10%Pt/y-alumina. 27 FT mass spectra taken at a field strength of 3-Tesla. 28 CAVERN uC CP/MAS NMR spectra of an overpressure of acetylene on 10%Pt/y-alumina adsorbed... pumped two-section ion cell, an Extrel 2001 data system, and a 3-Tesla Oxford superconducting magnet. ~~ Samples were introduced into the cell by a variable leak valve (at sample pressure of 4 x 10' torr). Ionization was performed by electron impact...

Lambregts, Marsha Jo Lupher

2012-06-07

180

Doppler broadening thermometry of acetylene and accurate measurement of the Boltzmann constant  

NASA Astrophysics Data System (ADS)

In this paper, we present accurate measurements of the fundamental Boltzmann constant based on a line-shape analysis of acetylene spectra in the ?1 + ?3 band recorded using a tunable diode laser. Experimental spectra recorded at low pressures (0.25 - 9 Torr), have been analyzed using a Speed Dependent Voigt model that takes into account the molecular speed dependence effects. This line-shape model reproduces the experimental data with good accuracy and allows us to determine precise line-shape parameters for the P(25) transition of the ?1 + ?3 band. From the recorded spectra we obtained the Doppler-width and then determined the Boltzmann constant, kB.

Hashemi, R.; Povey, C.; Derksen, M.; Naseri, H.; Garber, J.; Predoi-Cross, A.

2014-12-01

181

Polymerization of ionized acetylene clusters into covalent bonded ions: evidence for the formation of benzene radical cation.  

PubMed

Since the discovery of acetylene and benzene in protoplanetary nebulae under powerful ultraviolet ionizing radiation, efforts have been made to investigate the polymerization of ionized acetylene. Here we report the efficient formation of benzene ions within gas-phase ionized acetylene clusters (C2H2)n+ with n = 3-60. The results from experiments, which use mass-selected ion mobility techniques, indicate that the (C2H2)3+ ion has unusual stability similar to that of the benzene cation; its primary fragment ions are similar to those reported from the benzene cation, and it has a collision cross section of 47.4 A2 in helium at 300 K, similar to the value of 47.9 A2 reported for the benzene cation. In other words, (C2H2)3+ structurally looks like benzene, it has stability similar to that of benzene, it fragments such as benzene, therefore, it must be benzene! PMID:16984178

Momoh, Paul O; Abrash, Samuel A; Mabrouki, Ridha; El-Shall, M Samy

2006-09-27

182

Silicon carbide-derived carbon nanocomposite as a substitute for mercury in the catalytic hydrochlorination of acetylene.  

PubMed

Acetylene hydrochlorination is an important coal-based technology for the industrial production of vinyl chloride, however it is plagued by the toxicity of the mercury chloride catalyst. Therefore extensive efforts have been made to explore alternative catalysts with various metals. Here we report that a nanocomposite of nitrogen-doped carbon derived from silicon carbide activates acetylene directly for hydrochlorination in the absence of additional metal species. The catalyst delivers stable performance during a 150 hour test with acetylene conversion reaching 80% and vinyl chloride selectivity over 98% at 200 °C. Experimental studies and theoretical simulations reveal that the carbon atoms bonded with pyrrolic nitrogen atoms are the active sites. This proof-of-concept study demonstrates that such a nanocomposite is a potential substitute for mercury while further work is still necessary to bring this to the industrial stage. Furthermore, the finding also provides guidance for design of carbon-based catalysts for activation of other alkynes. PMID:24751500

Li, Xingyun; Pan, Xiulian; Yu, Liang; Ren, Pengju; Wu, Xing; Sun, Litao; Jiao, Feng; Bao, Xinhe

2014-01-01

183

Formation of artificial pores in nano-TiO2 photo-electrode films using acetylene-black for high-efficiency, dye-sensitized solar cells  

PubMed Central

Acetylene-black paste without a light scattering layer was applied to meso-porous TiO2 photo-electrode films with a crystalline framework, a low residual carbon, and a tunable morphological pore size. The thermal-treated TiO2 photo-electrode films had an increased acetylene-black concentration with an increase in artificial pores and a decrease in residual carbon. The performance of dye-sensitized solar cells (DSSCs) was enhanced by the use of the TiO2 photo-anode pastes at various acetylene-black concentrations. The photo-conversion efficiency of the DSSCs using TiO2 photo-electrode films with 1.5 wt% acetylene-black was enhanced from 7.98 (no acetylene-black) to 9.75% without the integration of a light- scattering layer. PMID:23511122

Cho, Tae-Yeon; Han, Chi-Whan; Jun, Yongseok; Yoon, Soon-Gil

2013-01-01

184

Designing zeolite catalysts for size- and shape-selective reactions: Selective hydrogenation of acetylene in the presence of butadiene and ethylene  

SciTech Connect

In the production of ethylene from the steam cracking of natural gas, small amounts of acetylene and butadiene are produced. Downstream, acetylene can present a hazard in a cryogenic separation process while nonselective hydrogenation removes acetylene as well as valuable ethylene and butadiene. With the aid of adsorption measurements, a selective hydrogenation catalyst has been designed. Small-pore zeolites, which serve as catalytic supports and provide reactant selective control, were ion-exchanged with Ni{sup 2+} and subsequently reduced. Compared to a commercial catalyst in which 60% of butadiene and all of the acetylene are hydrogenated, these new catalysts totally hydrogenate acetylene with only 10-20% hydrogenation of the butadiene and almost no hydrogenation of ethylene. To achieve selective hydrogenation, poisoning of the metal sites on the external zeolite surface is essential in order to obtain a product spectrum dominated by catalytic sites within the zeolite framework.

Corbin, D.R.; Abrams, L.; Bonifaz, C. (E.I. du Pont de Nemours Company, Wilmington, DE (USA))

1989-02-01

185

An improved choline monooxygenase assay  

SciTech Connect

Glycine betaine accumulates in leaves of plants from several angiosperm families in response to drought or salinization. Its synthesis, from the oxidation of choline, is mediated by a two step pathway. In spinach the first enzyme of this pathway is a ferredoxin-dependent choline monooxygenase (CMO). In order to purify this enzyme a sensitive and reliable assay is necessary. Two types of modifications were explored to improve the existing assay. (1) Ferredoxin reduction - one way of providing reduced Fd to CMO is by the addition of isolated spinach thylakoids in the assay mixture. In order to optimize the reduction of Fd two different systems were compared: (a) where only PS is active, by adding DCMU to inhibit electron transport from PS II and DAD as electron donor for PS I; (b) where both PS II and PS I are active. (2) Betaine aldehyde estimation - to simplify this, it is possible to couple the CMO reaction with betaine aldehyde dehydrogenase (BADH) from E. coli. BADH converts betaine aldehyde to betaine as it is formed in the assay, eliminating the need for a chemical oxidation step.

Lafontaine, P.J.; Hanson, A.D. (Michigan State Univ. Plant Research Lab., East Lansing (United States))

1991-05-01

186

Clinical Assay Development Program (CADP)  

Cancer.gov

Skip to Content Search this site Clinical Assay Development Program (CADP) Do you need: Advice on further development of a cancer diagnostics assay? Assay optimization? Design or implementation of assay controls, assay standards or assay calibrators? Determination

187

Transient responses of nitrogenase to acetylene and oxygen in actinorhizal nodules and cultured frankia.  

PubMed

Nitrogenase activity in root nodules of four species of actinorhizal plants showed varying declines in response to exposure to acetylene (10% v/v). Gymnostoma papuanum (S. Moore) L. Johnson. and Casuarina equisetifolia L. nodules showed a small decline (5-15%) with little or no recovery over 15 minutes. Myrica gale L. nodules showed a sharp decline followed by a rapid return to peak activity. Alnus incana ssp. rugosa (Du Roi) Clausen. nodules usually showed varying degrees of decline followed by a slower return to peak or near-peak activity. We call these effects acetylene-induced transients. Rapid increases in oxygen tension also caused dramatic transient decreases in nitrogenase activity in all species. The magnitude of the transient decrease was related to the size of the O(2) partial pressure (pO(2)) rise, to the proximity of the starting and ending oxygen tensions to the pO(2) optimum, and to the time for which the plant was exposed to the lower pO(2). Oxygen-induced transients, induced both by step jumps in pO(2) and by O(2) pulses, were also observed in cultures of Frankia. The effects seen in nodules are purely a response by the bacterium and not a nodule effect per se. Oxygen-induced nitrogenase transients in actinorhizal nodules from the plant genera tested here do not appear to be a result of changes in nodule diffusion resistance. PMID:16667301

Silvester, W B; Winship, L J

1990-02-01

188

Transient responses of nitrogenase to acetylene and oxygen in actinorhizal nodules and cultured Frania  

SciTech Connect

Nitrogenase activity in root nodules of four species of actinorhizal plants showed varying declines in response to exposure to acetylene (10% v/v). Gymnostoma papuanum (S.Moore) L. Johnson. and Casuarina equisetifolia L. nodules showed a small decline (5-15%) with little or no recovery over 15 minutes. Myrica gale L. nodules showed a sharp decline followed by a rapid return to peak activity. Alnus incana ssp. rugosa (Du Roi) Clausen. nodules usually showed varying degrees of decline followed by a slower return to peak or near-peak activity. We call these effects acetylene-induced transients. Rapid increases in oxygen tension also caused dramatic transient decreases in nitrogenase activity in all species. The magnitude of the transient decrease was related to the size of the O{sub 2} partial pressure (pO{sub 2}) rise, to the proximity of the starting and ending oxygen tensions to the pO{sub 2} optimum, and to the time for which the plant was exposed to the lower pO{sub 2}. Oxygen-induced transients, induced both by step jumps in pO{sub 2} and by O{sub 2} pulses, were also observed in cultures of Frankia. The effects seen in nodules are purely a response by the bacterium and not a nodule effect per se. Oxygen-induced nitrogenase transients in actinorhizal nodules from the plant genera tested here do not appear to be a result of changes in nodule diffusion resistance.

Silvester, W.B.; Winship, L.J. (Harvard Univ., Petersham, MA (USA))

1990-02-01

189

Selective Hydrogenation of Acetylene over Pd, Au, and PdAu Supported Nanoparticles  

NASA Astrophysics Data System (ADS)

The removal of trace amounts of acetylene in ethylene streams is a high-volume industrial process that must possess high selectivity of alkyne hydrogenation over hydrogenation of alkenes. Current technology uses metallic nanoparticles, typically palladium or platinum, for acetylene removal. However, problems arise due to the deactivation of the catalysts at high temperatures as well as low selectivities at high conversions. Pore expanded MCM-41 is synthesized via a two-step strategy in which MCM-41 was prepared via cetyltrimethylammonium bromide (CTMABr) followed by the hydrothermal treatment with N,N-dimethyldecylamine (DMDA). This material was washed with ethanol to remove DMDA, or calcined to remove both surfactants. PE-MCM-41 based materials were impregnated with palladium, gold, and palladium-gold nanoparticles. The removal of DMDA had an effect on both the conversion and selectivity, in which they were found to drop significantly. However, by using the bimetallic PdAu catalysts, higher selectivity could be achieved due to increased electron density.

Walker, Michael P.

190

The Structure of the 1-CHLORO-1-FLUOROETHYLENE--ACETYLENE Complex  

NASA Astrophysics Data System (ADS)

The insensitivity of the moments of inertia to certain geometric parameters for the limited set of isotopologues studied led to unexpected results for a preliminary structure of the complex formed between 1-chloro-1-fluoroethylene and acetylene presented three years ago. The availability of this chlorofluoroethylene with a single deuterium substitution in both (E) and (Z) isomeric forms allows us to supplement the original data set with microwave spectra of (E)-CHDC35ClF--HCCH and (Z)-CHDC35ClF--HCCH. Supported by the results of ab initio calculations, a planar, chemically reasonable structure is obtained for this complex, in which the acetylene forms a hydrogen bond with the fluorine atom of 1-chloro-1-fluoroethylene. The hydrogen bond bends to allow a secondary interaction with the hydrogen atom cis to this fluorine atom. Comparisons with the structure of the analogous complexes formed with vinyl fluoride and 1,1-difluoroethylene reveal the effects of chlorine substitution geminal to the acceptor atom of the hydrogen bond. H.O. Leung and M.D. Marshall, The 62nd OSU International Symposium on Molecular Spectroscopy, Talk RG10 (2007) Kindly provided by Prof. Norman Craig, Oberlin College

Leung, Helen O.; Marshall, Mark D.; Grimes, David D.

2010-06-01

191

Rhizobium , Bradyrhizobium and Agrobacterium strains isolated from cultivated legumes  

Microsoft Academic Search

The present study was conducted to isolate and characterize rhizobial strains from root nodules of cultivated legumes, i.e. chickpea, mungbean, pea and siratro. Preliminary characterization of these isolates was done on the basis of plant infectivity test, acetylene reduction assay, C-source utilization, phosphate solubilization, phytohormones and polysaccharide production. The plant infectivity test and acetylene reduction assay showed effective root nodule

Sohail Hameed; Sumera Yasmin; Kauser A. Malik; Yusuf Zafar; Fauzia Y. Hafeez

2004-01-01

192

Cis-trans isomerization in the S[subscript 1] state of acetylene: Identification of cis-well vibrational levels  

E-print Network

A systematic analysis of the S[subscript 1]-trans ([bar-over A][superscript 1]A[subscript u]) state of acetylene, using IR-UV double resonance along with one-photon fluorescence excitation spectra, has allowed assignment ...

Merer, Anthony J.

193

Gold(I)-Catalyzed Intramolecular Acetylenic Schmidt Reaction David J. Gorin, Nicole R. Davis, and F. Dean Toste*  

E-print Network

Gold(I)-Catalyzed Intramolecular Acetylenic Schmidt Reaction David J. Gorin, Nicole R. Davis, and F 10, 2005; E-mail: fdtoste@berkeley.edu Gold(I) complexes have seen increased utility as catalysts-bonding from gold into an electron-deficient intermediate may play a role in mediating the formation of bicyclo

Toste, Dean

194

Quasiclassical trajectory study of fast H-atom collisions with acetylene.  

PubMed

Translationally hot H collisions with the acetylene are investigated using quasiclassical trajectory calculations, on a recent full-dimensional ab initio-based potential energy surface. Three outcomes are focused on: non-reactive energy transfer via prompt collisions, non-reactive energy transfer via the formation of the vinyl complex, and reactive chemical H-atom exchange, also via complex formation. The details of these outcomes are presented and correlated with the collision lifetime. Large energy transfer is found via complex formation, which can subsequently decay back to reactants, a non-reactive event, or to new products, a reactive event. For the present system, these two events are experimentally indistinguishable. PMID:22697549

Han, Yong-Chang; Sharma, Amit R; Bowman, Joel M

2012-06-01

195

Visualizing recurrently migrating hydrogen in acetylene dication by intense ultrashort laser pulses.  

PubMed

We demonstrate the visualization of ultrafast hydrogen migration in deuterated acetylene dication (C2D2{2+}) by employing the pump-probe Coulomb explosion imaging with sub-10-fs intense laser pulses (9 fs, 0.13 PW/cm{2}, 800 nm). It is shown, from the temporal evolution of the momenta of the fragment ions produced by the three-body explosion, C2D2{3+}-->D{+} + C{+} + CD{+}, that the migration proceeds in a recurrent manner: the deuterium atom first shifts from one carbon site to the other in a short time scale (approximately 90 fs) and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation. PMID:18233560

Hishikawa, Akiyoshi; Matsuda, Akitaka; Fushitani, Mizuho; Takahashi, Eiji J

2007-12-21

196

Hydrothermal synthesis and acetylene sensing properties of variety low dimensional zinc oxide nanostructures.  

PubMed

Various morphologies of low dimensional ZnO nanostructures, including spheres, rods, sheets, and wires, were successfully synthesized using a simple and facile hydrothermal method assisted with different surfactants. Zinc acetate dihydrate was chosen as the precursors of ZnO nanostructures. We found that polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), glycine, and ethylene glycol (EG) play critical roles in the morphologies and microstructures of the synthesized nanostructures, and a series of possible growth processes were discussed in detail. Gas sensors were fabricated using screen-printing technology, and their sensing properties towards acetylene gas (C2H2), one of the most important arc discharge characteristic gases dissolved in oil-filled power equipments, were systematically measured. The ZnO nanowires based sensor exhibits excellent C2H2 sensing behaviors than those of ZnO nanosheets, nanorods, and nanospheres, indicating a feasible way to develop high-performance C2H2 gas sensor for practical application. PMID:24672324

Zhou, Qu; Chen, Weigen; Peng, Shudi; Zeng, Wen

2014-01-01

197

Doppler broadening thermometry of acetylene and accurate measurement of the Boltzmann constant.  

PubMed

In this paper, we present accurate measurements of the fundamental Boltzmann constant based on a line-shape analysis of acetylene spectra in the ?1 + ?3 band recorded using a tunable diode laser. Experimental spectra recorded at low pressures (0.25 - 9 Torr), have been analyzed using a Speed Dependent Voigt model that takes into account the molecular speed dependence effects. This line-shape model reproduces the experimental data with good accuracy and allows us to determine precise line-shape parameters for the P(25) transition of the ?1 + ?3 band. From the recorded spectra we obtained the Doppler-width and then determined the Boltzmann constant, kB. PMID:25481135

Hashemi, R; Povey, C; Derksen, M; Naseri, H; Garber, J; Predoi-Cross, A

2014-12-01

198

Tabletop imaging of structural evolutions in chemical reactions demonstrated for the acetylene cation  

NASA Astrophysics Data System (ADS)

The introduction of femto-chemistry has made it a primary goal to follow the nuclear and electronic evolution of a molecule in time and space as it undergoes a chemical reaction. Using Coulomb Explosion Imaging, we have shot the first high-resolution molecular movie of a to and fro isomerization process in the acetylene cation. So far, this kind of phenomenon could only be observed using vacuum ultraviolet light from a free-electron laser. Here we show that 266?nm ultrashort laser pulses are capable of initiating rich dynamics through multiphoton ionization. With our generally applicable tabletop approach that can be used for other small organic molecules, we have investigated two basic chemical reactions simultaneously: proton migration and C=C bond breaking, triggered by multiphoton ionization. The experimental results are in excellent agreement with the timescales and relaxation pathways predicted by new and quantitative ab initio trajectory simulations.

Ibrahim, Heide; Wales, Benji; Beaulieu, Samuel; Schmidt, Bruno E.; Thiré, Nicolas; Fowe, Emmanuel P.; Bisson, Éric; Hebeisen, Christoph T.; Wanie, Vincent; Giguére, Mathieu; Kieffer, Jean-Claude; Spanner, Michael; Bandrauk, André D.; Sanderson, Joseph; Schuurman, Michael S.; Légaré, François

2014-07-01

199

Tabletop imaging of structural evolutions in chemical reactions demonstrated for the acetylene cation.  

PubMed

The introduction of femto-chemistry has made it a primary goal to follow the nuclear and electronic evolution of a molecule in time and space as it undergoes a chemical reaction. Using Coulomb Explosion Imaging, we have shot the first high-resolution molecular movie of a to and fro isomerization process in the acetylene cation. So far, this kind of phenomenon could only be observed using vacuum ultraviolet light from a free-electron laser. Here we show that 266 nm ultrashort laser pulses are capable of initiating rich dynamics through multiphoton ionization. With our generally applicable tabletop approach that can be used for other small organic molecules, we have investigated two basic chemical reactions simultaneously: proton migration and C=C bond breaking, triggered by multiphoton ionization. The experimental results are in excellent agreement with the timescales and relaxation pathways predicted by new and quantitative ab initio trajectory simulations. PMID:25034613

Ibrahim, Heide; Wales, Benji; Beaulieu, Samuel; Schmidt, Bruno E; Thiré, Nicolas; Fowe, Emmanuel P; Bisson, Éric; Hebeisen, Christoph T; Wanie, Vincent; Giguére, Mathieu; Kieffer, Jean-Claude; Spanner, Michael; Bandrauk, André D; Sanderson, Joseph; Schuurman, Michael S; Légaré, François

2014-01-01

200

Saturated absorption spectroscopy of acetylene gas inside large-core photonic bandgap fiber.  

PubMed

Saturated absorption spectroscopy is performed on the acetylene nu(1) + nu(3) band near 1532 nm inside photonic bandgap fibers of small (approximately 10 microm) and large (approximately 20 microm) core diameters. The observed linewidths are narrower in the 20 microm fiber and vary from 20 to 40 MHz depending on pressure and power. Variations in the background light transmission, attributed by others to surface modes, are significantly reduced in the 20 microm fiber. The optimum signal for use as a frequency reference in a 0.8 m long, 20 microm diameter fiber is found to occur at about 0.5 torr for 30 mW of pump power. The saturation power is found by modeling the propagation and attenuation of light inside the fiber. PMID:16880865

Thapa, Rajesh; Knabe, Kevin; Faheem, Mohammed; Naweed, Ahmer; Weaver, Oliver L; Corwin, Kristan L

2006-08-15

201

Benzene···acetylene: a structural investigation of the prototypical CH···? interaction.  

PubMed

The structure of a prototype CH···? system, benzene···acetylene, has been determined in the gas phase using Fourier-transform microwave spectroscopy. The spectrum is consistent with an effective C(6v) structure with an H···? distance of 2.4921(1) Å. The HCCH subunit likely tilts by ~5° from the benzene symmetry axis. The dipole moment was determined to be 0.438(11) D from Stark effect measurements. The observed intermolecular distance is longer than in similar benzene···HX complexes and than the distances observed in the benzene···HCCH cocrystal and predicted by many high level ab initio calculations; however, the experimentally estimated binding energy of 7.1(7) kJ mol(-1) is similar to previously studied benzene···HX complexes. Several additional sets of transitions were observed in the rotational spectrum, likely corresponding to excited states arising from low energy intermolecular vibrational modes of the dimer. PMID:24686437

Ulrich, Nathan W; Seifert, Nathan A; Dorris, Rachel E; Peebles, Rebecca A; Pate, Brooks H; Peebles, Sean A

2014-05-21

202

The effect of vesicular-arbuscular mycorrhizae on growth and nitrogen fixation (acetylene reduction) by subterranean clover and pearl millet  

E-print Network

for symbiotic nitrogen fixation using subterranean clover (Trifolium sub- terraneum L. ) inoculated with Rhizobium trifolii and mycorrhizal fun- gi. Two additional experiments were performed using pearl millet (P 1 i 1 &L. ) K. Sd . ) t 1 t auth~A* t tll... and Enterobacter cloacae) and in the Trifolium subterra- neum-Rhizobium symbiosis in a low fertility soil of central Texas. LITERATURE REVIEW The rising cost of commercial nitrogen and phosphorus fertiliz- ers motivates researchers to find alternative methods...

Sherrod, Carole Cay

1983-01-01

203

Schultheiss, Schiepe, & Rawolle Hormone assays 1 Running head: HORMONE ASSAYS  

E-print Network

Schultheiss, Schiepe, & Rawolle Hormone assays 1 Running head: HORMONE ASSAYS Hormone assays Oliver: Schultheiss, O. C., Schiepe, A., & Rawolle, M. (2012). Hormone assays. In H. Cooper, P. M. Camic, D. L. Long Association. #12;Schultheiss, Schiepe, & Rawolle Hormone assays 2 Hormone assays Hormones can be assayed from

Schultheiss, Oliver C.

204

Development of a spectrofluorimetry-based device for determining the acetylene content in the oils of power transformers.  

PubMed

Power transformers are essential for a functioning electrical system and therefore require special attention by maintenance programs because a fault can harm both the company and society. The temperature inside a power transformer and the dissolved gases, which are primarily composed of acetylene, are the two main parameters monitored when detecting faults. This paper describes the development of a device for analyzing the acetylene content in insulating oil using spectrofluorimetry. Using this device introduces a new methodology for the maintaining and operating power transformers. The prototype is currently operating in a substation. The results presented by this system were satisfactory; when compared to chromatographic data, the errors did not exceed 15%. This prototype may be used to confirm the quality of an insulating oil sample to detect faults in power transformers. PMID:24209339

Quintella, Cristina M; Meira, Marilena; Silva, Weidson Leal; Filho, Rogério G D; Araújo, André L C; Júnior, Elias T S; Sales, Lindolfo J O

2013-12-15

205

Denitrification, nitrate reduction to ammonium, and inoganic nitrogen pools in intetidal sediments  

Microsoft Academic Search

Dissimilatory nitrate reductions and inorganic nitrogen pools in intertidal sediments of Delaware Inlet near Nelson, New Zealand, were studied between March 1981 and January 1982. The acetylene block technique was used in sediment cores to estimate rates of in situ denitrification. In the top 10.5 cm of sediment the denitrification rates were 1.2 to 11.0 mg N m-2d-1 (Juncus maritimus

H. F. Kaspar

1983-01-01

206

Cis-trans isomerization in the S1 state of acetylene: Identification of cis-well vibrational levels  

Microsoft Academic Search

A systematic analysis of the S1-trans (A~1Au) state of acetylene, using IR-UV double resonance along with one-photon fluorescence excitation spectra, has allowed assignment of at least part of every single vibrational state or polyad up to a vibrational energy of 4200 cm-1. Four observed vibrational levels remain unassigned, for which no place can be found in the level structure of

Anthony J. Merer; Adam H. Steeves; Joshua H. Baraban; Hans A. Bechtel; Robert W. Field

2011-01-01

207

Cis-trans isomerization in the S1 state of acetylene: Identification of cis-well vibrational levels  

Microsoft Academic Search

A systematic analysis of the S1-trans (A˜1Au) state of acetylene, using IR-UV double resonance along with one-photon fluorescence excitation spectra, has allowed assignment of at least part of every single vibrational state or polyad up to a vibrational energy of 4200 cm–1. Four observed vibrational levels remain unassigned, for which no place can be found in the level structure of

Anthony J. Merer; Adam H. Steeves; Joshua H. Baraban; Hans A. Bechtel; Robert W. Field

2011-01-01

208

Production of commercial hydrogen and acetylene from propane-butane and liquid hydrocarbons in an electric-arc plasma reactor  

Microsoft Academic Search

A fundamentally new structure of a plasma reactor for production of acetylene and commercial hydrogen from gaseous and liquid\\u000a hydrocarbons has been developed and proposed. In this device, the plasma jet of synthesis gas is submerged in the volume of\\u000a liquid hydrocarbons to form a gas volume in which the second stage of pyrolysis reactions is realized. Experimental investigations\\u000a have

A. L. Mossé; A. V. Gorbunov; A. A. Galinovskii; V. V. Savchin; A. V. Lozhechnik

2008-01-01

209

Towards an all fibre based optical frequency standard using acetylene-filled hollow-core photonic bandgap fibres  

Microsoft Academic Search

linestrength. Applications of highly stable lasers outside the research laboratories are often hampered by the complexity of the setup. With a recently developed simple and compact acetylene stabilized fibre laser [1] we obtained a shot-term relative frequency instability of 5.0xl0- 13 ( r \\/s(1, for averaging times r up to 100 s (see Fig. 1), and a relative repeatability over

Jan Hald; Anders Brusch; Charlotte I. Falk; Jan C. Petersen; Lars Nielsen

2011-01-01

210

Fragment ion-photon coincidence study of dissociative ionization accompanying light emission by electron impact on acetylene  

Microsoft Academic Search

Fragment ion-photon coincidence (FIPCO) spectra by 120 eV electron impact on acetylene, C2 H2 , have been observed. Correlated detection of CH(A-X) emission and H+ and C+ ions, as well as between the CH+ ion and its own emission, was observed and verified with the help of Monte Carlo simulation of the band shapes observed. The translational energy distribution of

Kenji Furuya; Kouichiro Maruyama; Eri Koto; Akihiro Matsuo; Teiichiro Ogawa

2000-01-01

211

Pressure-induced shift and broadening of acetylene lines in the region 6580–6600 cm ?1  

Microsoft Academic Search

Highly accurate measurements of pressure shift and broadening parameters of acetylene absorption lines in the region 6580–6600cm?1 have been performed by tunable diode laser spectroscopy (TDLS). For these purposes the three channel spectrometer with distributed-feedback diode laser, operated at 1.53?m was used. The laser is generating pulses of 4–10ms duration at a repetition frequency of 40Hz. A temperature-stabilization system, using

A. I. Nadezhdinskii; Ya. Ya. Ponurovskii

2007-01-01

212

Absolute nuclear material assay  

DOEpatents

A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

Prasad, Manoj K. (Pleasanton, CA); Snyderman, Neal J. (Berkeley, CA); Rowland, Mark S. (Alamo, CA)

2012-05-15

213

Synthesis, structure and cytotoxic activity of new acetylenic derivatives of betulin.  

PubMed

A new series of betulin derivatives containing one or two pharmacophores bearing an acetylenic and carbonyl function at the C-3 and/or C-28 positions has been synthesized and characterized by ¹H- and ¹³C-NMR, IR, MS and elemental analyses. The crystal structure of 28-O-propynoylbetulin was determined by X-ray structural analysis. All new compounds, as well as betulin, were tested in vitro for their antiproliferative activity against human SW707 colorectal, CCRF/CEM leukemia, T47D breast cancer, and against murine P388 leukemia and Balb3T3 normal fibroblasts cell lines. Most of the compounds showed better cytotoxicity than betulin and cisplatin used as reference agent. 28-O-Propynoylbetulin was the most potent derivative, being over 500 times more potent than betulin and about 100 times more cytotoxic than cisplatin against the human leukemia (CCRF/CEM) cell line, with an ID?? value of 0.02 ?g/mL. PMID:23595090

Boryczka, Stanis?aw; B?benek, Ewa; Wietrzyk, Joanna; Kempi?ska, Katarzyna; Jastrz?bska, Maria; Kusz, Joachim; Nowak, Maria

2013-01-01

214

The effects of triplet perturbers on photophysical processes in the Ã1Au state of acetylene  

NASA Astrophysics Data System (ADS)

Rotationally resolved excitation spectra of the acetylene à 1Au?X˜ 1?g+ transition were recorded by measuring separately the total emission in two spectral regions: UV (200-400 nm) and NIR (0.9-1.5 ?m). UV emission is due to Ã?X˜ transitions. The source of the NIR signal is suggested by the observation that the NIR:UV intensity ratio is approximately constant throughout the V02K01 subband. (V denotes the trans-bending mode.) This is consistent with C2H à 2??X˜2?+ NIR transitions occurring as a result of resonance-enhanced two-photon excitation of predissociated Rydberg states. The V03K01 subband shows significant fluctuations in the NIR:UV intensity ratio. The increase in trans-bending excitation from 2?3' to 3?3' enables accidental resonances with background states (both triplet and S1) to alter the NIR emission intensity. Triplet perturbers can facilitate Tn (n>1)?T1 NIR transitions or modify the resonance enhancement of C2H Ø-state production. Extra lines in the V03K01 subband, due to an S1 anharmonic perturber, show dramatically diminished NIR but enhanced UV emission intensity. This indicates that the perturbing state is anomalously resistant to photodissociation.

Drucker, Stephen; O'Brien, Jonathan P.; Patel, Paresh; Field, Robert W.

1997-02-01

215

Cycloheximide prevents the de novo polypeptide synthesis required to recover from acetylene inhibition in Nitrosopumilus maritimus.  

PubMed

Developing methods to differentiate the relative contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) to ammonia (NH3) oxidation has been challenging due to the lack of compounds that selectively inhibit AOA. In this study, we investigated the effects of specific bacteria- and eukaryote-selective protein synthesis inhibitors on the recovery of acetylene (C2H2)-inactivated NH3 oxidation in the marine AOA Nitrosopumilus maritimus and compared the results with recovery of the AOB Nitrosomonas europaea. C2 H2 irreversibly inhibited N. maritimus NH3 oxidation in a similar manner to what was observed previously with N. europaea. However, cycloheximide (CHX), a widely used eukaryotic protein synthesis inhibitor, but not bacteria-specific protein synthesis inhibitors (kanamycin and gentamycin), inhibited the recovery of NH3-oxidizing activity in N. maritimus. CHX prevented the incorporation of (14)CO2 -labeling into cellular proteins, providing further evidence that CHX acts as a protein synthesis inhibitor in N. maritimus. If the effect of CHX on protein synthesis can be confirmed among other isolates of AOA, the combination of C2H2 inactivation followed by recovery of NH3 oxidation either in the presence of bacteria-selective protein synthesis inhibitors or CHX might be used to estimate the relative contributions of AOB and AOA to NH3 oxidation in natural environments. PMID:24606542

Vajrala, Neeraja; Bottomley, Peter J; Stahl, David A; Arp, Daniel J; Sayavedra-Soto, Luis A

2014-06-01

216

Oxy-acetylene driven laboratory scale shock tubes for studying blast wave effects  

E-print Network

Instrumentation is needed to produce realistic blast waves in a laboratory setting. This paper describes the development and characterization of oxy-acetylene driven, laboratory scale shock tubes for use in studying blast injury, candidate armor materials, and material properties at blast loading rates. The pressure-time profiles show a true shock front and exponential decay characteristic of blast waves and have relevant durations. The modular design includes shock tube diameters of 27 mm and 41 mm, and a selection of peak pressures from 204 kPa to 920 kPa can be produced by selection of the driver section diameter and placement of the test sample. Characterization studies of several driver/driven section combinations showed consistent results, with peak pressures having 0.8 - 6.9 percent uncertainty in the mean. This shock tube design provides a more realistic blast profile than current air-driven shock tubes. In addition, operation does not require specialized personnel or facilities like most blast-driven...

Courtney, Michael

2011-01-01

217

Surface characterization of the interfaces from plasma-polymerized acetylene films deposited onto cold-rolled steel for rubber-to-metal bonding  

NASA Astrophysics Data System (ADS)

The molecular structure of the interface between plasma-polymerized acetylene films and steel was determined using in-situ reflection-absorption infrared spectroscopy (RAIR) and X-ray photoelectron spectroscopy (XPS). Plasma-polymerized acetylene films were deposited onto polished steel substrates in microwave (MW) and radio frequency (RF)-powered reactors. The films deposited in RF-powered reactors were characterized in-situ using XPS and FTIR spectrometers that were interfaced directly to the reactors. RAIR showed that the plasma polymerized films contained large numbers of methyl and methylene groups but only a small number of monosubstituted acetylene groups, indicating that there was substantial rearrangement of the monomer molecules during plasma polymerization. The rearrangement of the monomer molecules during plasma was also determined by optical emission spectroscopy (OES), where CH and C2 species predominated in the optical emission spectra. Bands were observed near 1020 and 885 cm-1 in the RAIR spectra that were attributed to skeletal stretching vibrations in C-C-O-Fe groups, indicating that the plasma-polymerized films interacted with the substrate through formation of alkoxide bonds. Another band was observed near 1565 cm-1 and attributed to carboxylate groups in the interface between films and the oxidized surface of the substrate. Results from XPS also confirmed the formation of alkoxide and carboxylate groups in the interface during plasma polymerization of acetylene. Results from XPS showed that the surface of steel substrates consisted mostly of a mixture of Fe2O3 and FeOOH and that iron was mostly present in the Fe(III) oxidation state. However, during plasma-polymerization of acetylene, there was a tendency for the concentration of Fe(II) to increase, due to the reducing nature of argon/acetylene plasmas. Natural rubber reacted with plasma-polymerized acetylene primers through unsaturated functional groups present in the film. The RAIR and XPS results showed the presence of amino groups at the early steps of the vulcanization process. Activator products such as sulfenamide groups were found at the rubber/plasma-polymerized acetylene interface, the absorption bands near 1560 cm-1 in the RAIR spectra was due to the C=N stretching mode of the sulfenamide fragments of the accelerator. The band found in the RAIR spectra near 1143 cm -1 is characteristic from aliphatic secondary amines. Similarly, the presence of zinc was also found in the early stages of the vulcanization of natural rubber onto acetylene films. Zinc stearate reacted with accelerator and sulfur to form an accelerator complex. The zinc complex eventually reacted with natural rubber, sulfur, and the plasma-polymerized acetylene film to form rubber-bound intermediates.

Rosales Lombardi, Pablo I.

218

Seasonal variations of temperature, acetylene and ethane in Saturn's atmosphere from 2005 to 2010, as observed by Cassini-CIRS  

NASA Astrophysics Data System (ADS)

Acetylene (C2H2) and ethane (C2H6) are by-products of complex photochemistry in the stratosphere of Saturn. Both hydrocarbons are important to the thermal balance of Saturn's stratosphere and serve as tracers of vertical motion in the lower stratosphere. Earlier studies of Saturn's hydrocarbons using Cassini-CIRS observations have provided only a snapshot of their behaviour. Following the vernal equinox in August 2009, Saturn's northern and southern hemispheres have entered spring and autumn, respectively, however the response of Saturn's hydrocarbons to this seasonal shift remains to be determined. In this paper, we investigate how the thermal structure and concentrations of acetylene and ethane have evolved with the changing season on Saturn. We retrieve the vertical temperature profiles and acetylene and ethane volume mixing ratios from ??˜=15.5cm-1 Cassini-CIRS observations. In comparing 2005 (solar longitude, Ls ˜ 308°), 2009 (Ls ˜ 3°) and 2010 (Ls ˜ 15°) results, we observe the disappearance of Saturn's warm southern polar hood with cooling of up to 17.1 K ± 0.8 K at 1.1 mbar at high-southern latitudes. Comparison of the derived temperature trend in this region with a radiative climate model (Section 4 of Fletcher et al., 2010 and Greathouse et al. (2013, in preparation)) indicates that this cooling is radiative although dynamical changes in this region cannot be ruled out. We observe a 21 ± 12% enrichment of acetylene and a 29 ± 11% enrichment of ethane at 25°N from 2005 to 2009, suggesting downwelling at this latitude. At 15°S, both acetylene and ethane exhibit a decrease in concentration of 6 ± 11% and 17 ± 9% from 2005 to 2010, respectively, which suggests upwelling at this latitude (though a statistically significant change is only exhibited by ethane). These implied vertical motions at 15°S and 25°N are consistent with a recently-developed global circulation model of Saturn's tropopause and stratosphere(Friedson and Moses, 2012), which predicts this pattern of upwelling and downwelling as a result of a seasonally-reversing Hadley circulation. Ethane exhibits a general enrichment at mid-northern latitudes from 2005 to 2009. As the northern hemisphere approaches summer solstice in 2017, this feature might indicate an onset of a meridional enrichment of ethane, as has been observed in the southern hemisphere during/after southern summer solstice.

Sinclair, J. A.; Irwin, P. G. J.; Fletcher, L. N.; Moses, J. I.; Greathouse, T. K.; Friedson, A. J.; Hesman, B.; Hurley, J.; Merlet, C.

2013-07-01

219

Rapid mercury assays  

SciTech Connect

We have developed rapid assays with the potential of detecting mercury in environmental samples. our methods combine the simple ELISA-format with the selective, high affinity complexation of mercuric ions by sulfur-containing ligands. The first assay is based on a sandwich chelate formed by a protein-bound ligand immobilized on the wells of a microliter plate, mercuric ion of the analyzed sample, and another ligand conjugated to a reporter enzyme. The second assay involves competition between mercuric ions and an organomercury-conjugate to bind to a chelating conjugate. Several sulfur containing chelators (e.g., dithiocarbamates) and organomercurials linked to macromolecular carriers have been investigated in these assay formats. The assays detect mercuric ions in ppb/high ppt concentrations with high selectivity.

Szurdoki, S.; Kido, H.; Hammock, B.D. [Univ. of California, Davis, CA (United States)

1996-10-01

220

Chromophores from Photolyzed Ammonia Reacting with Acetylene: Application to Jupiter’s Great Red Spot  

NASA Astrophysics Data System (ADS)

The production mechanisms of chromophores at Jupiter, and notably at the Great Red Spot (GRS), have been long-standing puzzles. A clue to the formation of the GRS coloring agent may be the great height of this storm, which can upwell ammonia to pressure levels of a few hundred mbar where solar photons capable of dissociating NH3 penetrate. Acetylene formed at higher altitudes can diffuse down and react with the NH3 photodissociation products, forming a deposit that absorbs in the ultraviolet and visible region (Ferris and Ishikawa, J. Amer. Chem. Soc. 110, 4306-4312, 1988). We have investigated the system NH3 + C2H2 + CH4 using a Zn lamp emitting at 214 nm to produce NH2 + H and subsequent reaction products. The deposits produced in these reactions were analyzed by optical and infrared spectroscopy and soft-ionization (He*) time-of-flight mass spectroscopy. The combination of NH3 + CH4 produced no visibly absorbing material, but NH3 + C2H2 and NH3 + C2H2 + CH4 mixtures both produced a yellow-orange film whose transmission spectra are similar to that of the GRS obtained by Cassini VIMS. Infrared spectra show a strong band at 2056 wavenumbers which may arise from nitrile (-CN), isonitrile (-NC), or diazide (-CNN) functional groups. The high-resolution mass spectra are consistent with compounds of the form CnH2n+1Nm, similar to the products formed in NH3 + CH4 spark discharges (Molton and Ponnamperuma, Icarus 21, 166-174, 1974). We thank NASA's Planetary Atmospheres Program for support.

Carlson, Robert W.; Baines, K. H.; Anderson, M. S.; Filacchione, G.

2012-10-01

221

An experimental and theoretical study of nitrogen-broadened acetylene lines  

NASA Astrophysics Data System (ADS)

We present experimental nitrogen-broadening coefficients derived from Voigt profiles of isotropic Raman Q-lines measured in the ?2 band of acetylene (C2H2) at 150 K and 298 K, and compare them to theoretical values obtained through calculations that were carried out specifically for this work. Namely, full classical calculations based on Gordon's approach, two kinds of semi-classical calculations based on Robert-Bonamy method as well as full quantum dynamical calculations were performed. All the computations employed exactly the same ab initio potential energy surface for the C2H2-N2 system which is, to our knowledge, the most realistic, accurate and up-to-date one. The resulting calculated collisional half-widths are in good agreement with the experimental ones only for the full classical and quantum dynamical methods. In addition, we have performed similar calculations for IR absorption lines and compared the results to bibliographic values. Results obtained with the full classical method are again in good agreement with the available room temperature experimental data. The quantum dynamical close-coupling calculations are too time consuming to provide a complete set of values and therefore have been performed only for the R(0) line of C2H2. The broadening coefficient obtained for this line at 173 K and 297 K also compares quite well with the available experimental data. The traditional Robert-Bonamy semi-classical formalism, however, strongly overestimates the values of half-width for both Q- and R-lines. The refined semi-classical Robert-Bonamy method, first proposed for the calculations of pressure broadening coefficients of isotropic Raman lines, is also used for IR lines. By using this improved model that takes into account effects from line coupling, the calculated semi-classical widths are significantly reduced and closer to the measured ones.

Thibault, Franck; Martínez, Raúl Z.; Bermejo, Dionisio; Ivanov, Sergey V.; Buzykin, Oleg G.; Ma, Qiancheng

2014-07-01

222

Recovery of acetylene absorption line profile basing on tunable diode laser spectroscopy with intensity modulation and photoacoustic spectroscopy  

NASA Astrophysics Data System (ADS)

A novel and direct absorption line recovery technique based on tunable diode laser spectroscopy with intensity modulation is presented. Photoacoustic spectroscopy is applied for high sensitivity, zero background and efficient acoustic enhancement at a low modulation frequency. A micro-electromechanical systems (MEMS) mirror driven by an electrothermal actuator is used for generating laser intensity modulation (without wavelength modulation) through the external reflection. The MEMS mirror with 10?m thick structure material layer and 100nm thick gold coating is formed as a circular mirror of 2mm diameter attached to an electrothermal actuator and is fabricated on a chip that is wire-bonded and placed on a PCB holder. Low modulation frequency is adopted (since the resonant frequencies of the photoacoustic gas cell and the electrothermal actuator are different) and intrinsic high signal amplitude characteristics in low frequency region achieved from measured frequency responses for the MEMS mirror and the gas cell. Based on the property of photoacoustic spectroscopy and Beer's law that detectable sensitivity is a function of input laser intensity in the case of constant gas concentration and laser path length, a Keopsys erbium doped fibre amplifier (EDFA) with opto-communication C band and high output power up to 1W is chosen to increase the laser power. High modulation depth is achieved through adjusting the MEMS mirror's reflection position and driving voltage. In order to scan through the target gas absorption line, the temperature swept method is adopted for the tunable distributed feed-back (DFB) diode laser working at 1535nm that accesses the near-infrared vibration-rotation spectrum of acetylene. The profile of acetylene P17 absorption line at 1535.39nm is recovered ideally for ~100 parts-per-million (ppm) acetylene balanced by nitrogen. The experimental signal to noise ratio (SNR) of absorption line recovery for 500mW laser power was ~80 and hence the detectable sensitivity is of the order of 1ppm.

Li, Li; Thursby, Graham; Stewart, George; Arsad, Norhana; Uttamchandani, Deepak; Culshaw, Brian; Wang, Yiding

2010-04-01

223

Doped colorimetric assay liposomes  

DOEpatents

The present invention provides compositions comprising colorimetric assay liposomes. The present invention also provides methods for producing colorimetric liposomes and calorimetric liposome assay systems. In preferred embodiments, these calorimetric liposome systems provide high levels of sensitivity through the use of dopant molecules. As these dopants allow the controlled destabilization of the liposome structure, upon exposure of the doped liposomes to analyte(s) of interest, the indicator color change is facilitated and more easily recognized.

Charych, Deborah (Albany, CA); Stevens, Raymond C. (Albany, CA)

2001-01-01

224

Microfluidic DNA hybridization assays  

Microsoft Academic Search

DNA hybridization is one of the most powerful techniques applied in diagnostic assays. Microfluidics provides a promising\\u000a means to analyse small sample volumes, reduce reagent consumption and cost, shorten processing time as well as develop fast,\\u000a sensitive and portable diagnostic tools. By coupling with the microfluidic technology, DNA hybridization assay can achieve\\u000a high sensitivity, enhance hybridization kinetics and decrease the

Xuan WengHai; Hai Jiang; Dongqing Li

225

Catalyst-Directed Diastereoselectivity in Hydrogenative Couplings of Acetylene to ?-Chiral Aldehydes: Formal Synthesis of All Eight L-Hexoses  

PubMed Central

Hydrogenative coupling of acetylene to ?-chiral aldehydes 1a–4a using enantiomeric rhodium catalysts ligated by (S)-MeO-BIPHEP and (R)-MeO-BIPHEP delivers the diastereomeric products of carbonyl-(Z)-butadienylation 1b–4b and 1c–4c, respectively, with good to excellent levels of catalyst directed diastereofacial selectivity. Diastereomeric L-glyceraldehyde acetonide adducts 1b and 1c were converted to the four isomeric enoates 6b, 8b, 6c, and 8c, representing a formal synthesis of all eight L-hexoses. PMID:18729371

Han, Soo Bong; Kong, Jong Rock; Krische, Michael J.

2011-01-01

226

Histrionicotoxins: Roentgen-Ray Analysis of the Novel Allenic and Acetylenic Spiroalkaloids Isolated from a Colombian Frog, Dendrobates histrionicus  

Microsoft Academic Search

The structures and absolute configuration of two unique alkaloids isolated from the Colombian frog, Dendrobates histrionicus, have been elucidated by Roentgen-ray (x-ray) crystallography. Histrionicotoxin is (2pR, 6S, 7pS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis -2-penten-4-ynyl)-1-azaspiro[5.5] undecane, while in dihydro-isohistrionicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent. Dendrobates histrionicus exhibits remarkable interpopulational variations in amounts and composition of skin toxins,

John W. Daly; Isabella Karle; Charles W. Myers; Takashi Tokuyama; James A. Waters; Bernhard Witkop

1971-01-01

227

Generation of the organo-rare gas dications HCCRg2+ (Rg = Ar and Kr) in the reaction of acetylene dications with rare gases.  

PubMed

Using doubly ionized acetylene as a superelectrophilic reagent, the new rare-gas compounds HCCAr2+ and HCCKr2+ have been prepared for the first time in hyperthermal collisions of mass-selected C2H2(2+) with neutral rare gases (Rg). However, electron transfer from the rare gas to the acetylene dication as well as proton transfer from C2H2(2+) to the rare gas efficiently compete with formation of HCCRg2+. The computational investigations show that the formation of HCCRg2+ from acetylene dication is endothermic with Rg = He, Ne, Ar and Kr and only weakly exothermic with Xe. These energetic factors, as well as the pronounced competition with the other reactive channels help to explain why HCCRg2+ is only observed with Rg = Ar and Kr. PMID:19039346

Ascenzi, Daniela; Tosi, Paolo; Roithová, Jana; Ricketts, Claire L; Schröder, Detlef; Lockyear, Jessica F; Parkes, Michael A; Price, Stephen D

2008-12-21

228

SiC formation by reaction of Si(001) with acetylene: Electronic structure and growth mode  

SciTech Connect

The carbonization process of a single domain 2{times}1-reconstructed Si(001) vicinal surface (5{degree} off axis from [001] in the [{bar 1}10] direction) in acetylene has been studied by combining in situ surface science techniques (x-ray photoemission spectroscopy, x-ray photoelectron diffraction, reflection-electron energy loss spectroscopy, low-energy electron diffraction) and ex situ analytical techniques ({sup 12}C and {sup 2}H dosing by nuclear reaction analysis, scanning electron microscopy, and reflection high-energy electron diffraction). It is found that at a growth temperature of about 820{degree}C a variety of growth mechanisms can be observed, particularly during the first step of carbonization. An analysis of C1s and Si2p core-level shifts and of the respective intensities of them, combined with the examination of photoelectron diffraction curves, gives evidence for a penetration of C atoms into the silicon substrate, to form a nonstoichiometric compound. Contemporaneously 3C-SiC nuclei form, aligned with respect to the substrate. Then a quasicontinuous 3C-SiC film grows heteroepitaxially (cube on cube unstrained growth) on the substrate up to a thickness of {approximately}40{Angstrom}. C1s and Si2p photoelectron diffraction patterns, compared with calculated ones, show that the single domain initial surface does not necessarily force a preferential alignment of one of the two inequivalent SiC{l_brace}110{r_brace} planes with respect to the (110) Si plane. Consequently, such vicinal Si(001) surfaces are not necessarily templates for the growth of crystalline films free of antiphase boundary domains. Finally, we have observed that an imperfect coalescence of 3C-SiC nuclei leaves easy paths for Si out migration from the substrate and SiC polycrystalline growth, even at a temperature as low as 820{degree}C. The current models of Si(001) carbonization are examined and compared to our experimental findings. (Abstract Truncated)

Dufour, G.; Rochet, F. [Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris, Cedex 05 (France)] [Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris, Cedex 05 (France); Stedile, F.C. [Departamento de Fisico-quimica, Instituto de Quimica, UFRGS, Av. Bento Goncalves, 9500 Porto Alegre, Rio Grande do Sul (Brazil)] [Departamento de Fisico-quimica, Instituto de Quimica, UFRGS, Av. Bento Goncalves, 9500 Porto Alegre, Rio Grande do Sul (Brazil); Poncey, C. [Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France)] [Laboratoire de Chimie Physique, Universite Pierre et Marie Curie, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); De Crescenzi, M.; Gunnella, R. [Dipartimento di Matematica e Fisica, Unita dellIstituto Nazionale di Fisica della Materia, Universita di Camerino, 62032 Camerino (Italy)] [Dipartimento di Matematica e Fisica, Unita dellIstituto Nazionale di Fisica della Materia, Universita di Camerino, 62032 Camerino (Italy); Froment, M. [Laboratoire de Physique des Liquides et Electrochimie, Universite Pierre et Marie Curie, Tour 22, 4 place Jussieu, 75230 Paris Cedex 05 (France)] [Laboratoire de Physique des Liquides et Electrochimie, Universite Pierre et Marie Curie, Tour 22, 4 place Jussieu, 75230 Paris Cedex 05 (France)

1997-08-01

229

Titan haze: structure and properties of cyanoacetylene and cyanoacetylene-acetylene photopolymers  

NASA Technical Reports Server (NTRS)

The structure and morphological properties of polymers produced photochemically from the UV irradiation of cyanoacetylene and cyanoacetylene mixtures have been examined to evaluate their possible contribution to the haze layers found on Titan. A structural analysis of these polymers may contribute to our understanding of the data returned from the Huygens probe of the Cassini mission that will pass through the atmosphere of Titan in the year 2004. Infrared analysis, elemental analysis, and thermal methods (thermogravimetric analysis, thermolysis, pyrolysis) were used to examine structures of polycyanoacetylenes produced by irradiation of the gas phase HC3N at 185 and 254 nm. The resulting brown to black polymer, which exists as small particles, is believed to be a branched chain of conjugated carbon-carbon double bonds, which, on exposure to heat, cyclizes to form a graphitic structure. Similar methods of analysis were used to show that when HC3N is photolyzed in the presence of Titan's other atmospheric constituents (CH4, C2H6, C2H2, and CO), a copolymer is formed in which the added gases are incorporated as substituents on the polymer chain. Of special significance is the copolymer of HC3N and acetylene (C2H2). Even in experiments where C2H2 was absorbing nearly all of the incident photons, the ratio of C2H2 to HC3N found in the resulting polymer was only 2:1. Scanning electron microscopy was used to visually examine the polymer particles. While pure polyacetylene particles are amorphous spheres roughly 1 micrometer in diameter, polycyanoacetylenes appear to be strands of rough, solid particles slightly smaller in size. The copolymer of HC3N and C2H2 exhibits characteristics of both pure polymers. This is particularly important as pure polyacetylenes do not match the optical constants measured for Titan's atmospheric hazes. The copolymers produced by the incorporation of other minor atmospheric constituents, like HC3N, into the polyacetylenes are expected to have optical constants more comparable to those of the Titan haze.

Clarke, D. W.; Ferris, J. P.

1997-01-01

230

Conjugate additions, aza-Cope, and dissociative rearrangements and unexpected electrocyclic ring closures in the reactions of 2-(2-pyrrolidinyl)-substituted heteroaromatic systems with acetylenic sulfones.  

PubMed

The reactions of 2-heteroaryl-substituted pyrrolidines with acetylenic sulfones proceeded via two pathways. The first involves conjugate addition of the pyrrolidine to the acetylenic sulfone to afford a zwitterion, followed by dissociation of the C-N bond and recombination of the resulting carbocation and vinyl anion to afford the corresponding azepine derivative. The second comprises a cascade of conjugate addition, aza-Cope rearrangement and anionic 6pi electrocyclic ring-closure steps. The stability of the carbocation intermediate formed by C-N cleavage determines the dominant pathway. PMID:20614920

Weston, Mitchell H; Parvez, Masood; Back, Thomas G

2010-08-01

231

Homogeneous, bioluminescent proteasome assays.  

PubMed

Protein degradation is mediated predominantly through the ubiquitin-proteasome pathway. The importance of the proteasome in regulating degradation of proteins involved in cell-cycle control, apoptosis, and angiogenesis led to the recognition of the proteasome as a therapeutic target for cancer. The proteasome is also essential for degrading misfolded and aberrant proteins, and impaired proteasome function has been implicated in neurodegerative and cardiovascular diseases. Robust, sensitive assays are essential for monitoring proteasome activity and for developing inhibitors of the proteasome. Peptide-conjugated fluorophores are widely used as substrates for monitoring proteasome activity, but fluorogenic substrates can exhibit significant background and can be problematic for screening because of cellular autofluorescence or interference from fluorescent library compounds. Furthermore, fluorescent proteasome assays require column-purified 20S or 26S proteasome (typically obtained from erythrocytes), or proteasome extracts from whole cells, as their samples. To provide assays more amenable to high-throughput screening, we developed a homogeneous, bioluminescent method that combines peptide-conjugated aminoluciferin substrates and a stabilized luciferase. Using substrates for the chymotrypsin-like, trypsin-like, and caspase-like proteasome activities in combination with a selective membrane permeabilization step, we developed single-step, cell-based assays to measure each of the proteasome catalytic activities. The homogeneous method eliminates the need to prepare individual cell extracts as samples and has adequate sensitivity for 96- and 384-well plates. The simple "add and read" format enables sensitive and rapid proteasome assays ideal for inhibitor screening. PMID:25308265

O'Brien, Martha A; Moravec, Richard A; Riss, Terry L; Bulleit, Robert F

2015-01-01

232

Rationally tuned micropores within enantiopure metal-organic frameworks for highly selective separation of acetylene and ethylene  

SciTech Connect

Separation of acetylene and ethylene is an important industrial process because both compounds are essential reagents for a range of chemical products and materials. Current separation approaches include the partial hydrogenation of acetylene into ethylene over a supported Pd catalyst, and the extraction of cracked olefins using an organic solvent; both routes are costly and energy consuming. Adsorption technologies may allow separation, but microporous materials exhibiting highly selective adsorption of C{sub 2}H{sub 2}/C{sub 2}H{sub 4} have not been realized to date. Here, we report the development of tunable microporous enantiopure mixed-metal-organic framework (M'MOF) materials for highly selective separation of C{sub 2}H{sub 2} and C{sub 2}H{sub 4}. The high selectivities achieved suggest the potential application of microporous M'MOFs for practical adsorption-based separation of C{sub 2}H{sub 2}/C{sub 2}H{sub 4}.

Xiang, Sheng-Chang [University of Texas at San Antonio (UTSA); Zhang, Zhangjing [University of Texas at San Antonio (UTSA); Zhao, Cong-Gui [University of Texas at San Antonio (UTSA); Hong, Kunlun [ORNL; Zhao, Xuebo [University of Newcastle upon Tyne; Ding, De-Rong [University of Texas at San Antonio (UTSA); Xie, Ming-Hua [University of Texas, Pan American, Edinburg, TX; Wu, Chuan-De [University of Texas, Pan American, Edinburg, TX; Madhab, Das [University of Texas at San Antonio (UTSA); Gill, Rachel [University of Newcastle upon Tyne; Thomas, K Mark [University of Newcastle upon Tyne; Chen, Banglin [University of Texas at San Antonio (UTSA)

2011-01-01

233

The Effect of Surface Finish on Low-Temperature Acetylene-Based Carburization of 316L Austenitic Stainless Steel  

NASA Astrophysics Data System (ADS)

We observed a strong influence of surface finish on the efficacy of low-temperature acetylene-based carburization of AISI 316L austenitic stainless steel. Steel coupons were prepared with different surface finishes prior to carburization, from P400 SiC grit paper to 1- µm-diameter-diamond-paste. The samples with the finer surface finish developed a thicker "case" (a carbon-rich hardened surface layer) and a larger surface carbon concentration. Transmission electron microscopy revealed that the differences arose mainly from the nature of the deformation-induced disturbed layer on the steel surface. A thick (>400 nm) disturbed layer consisting of nano-crystalline grains (?10 nm diameter) inhibits acetylene-based carburization. The experimental observations can be explained by assuming that during machining or coarse polishing, the surface oxide layer is broken up and becomes incorporated into the deformation-induced disturbed layer. The incorporated oxide-rich films retard or completely prevent the ingress of carbon into the stainless steel.

Ge, Yindong; Ernst, Frank; Kahn, Harold; Heuer, Arthur H.

2014-12-01

234

In situ TDLAS measurement of absolute acetylene concentration profiles in a non-premixed laminar counter-flow flame  

NASA Astrophysics Data System (ADS)

Acetylene (C2H2), as an important precursor for chemiluminescence species, is a key to understand, simulate and model the chemiluminescence and the related reaction paths. Hence we developed a high resolution spectrometer based on direct Tunable Diode Laser Absorption Spectroscopy (TDLAS) allowing the first quantitative, calibration-free and spatially resolved in situ C2H2 measurement in an atmospheric non-premixed counter-flow flame supported on a Tsuji burner. A fiber-coupled distributed feedback diode laser near 1535 nm was used to measure several absolute C2H2 concentration profiles (peak concentrations up to 9700 ppm) in a laminar non-premixed CH4/air flame ( T up to 1950 K) supported on a modified Tsuji counter-flow burner with N2 purge slots to minimize end flames. We achieve a fractional optical resolution of up to 5×10-5 OD (1 ?) in the flame, resulting in temperature-dependent acetylene detection limits for the P17e line at 6513 cm-1 of up to 2.1 ppm?m. Absolute C2H2 concentration profiles were obtained by translating the burner through the laser beam using a DC motor with 100 ?m step widths. Intercomparisons of the experimental C2H2 profiles with simulations using our new hydrocarbon oxidation mechanisms show excellent agreement in position, shape and in the absolute C2H2 values.

Wagner, S.; Klein, M.; Kathrotia, T.; Riedel, U.; Kissel, T.; Dreizler, A.; Ebert, V.

2012-06-01

235

Dissociative electron attachment, electron transmission, and electron energy-loss study of the temporary negative ion of acetylene  

SciTech Connect

The three title electron-impact techniques are used to study the ground and excited states of acetylene negative ion and their decay processes. The ..pi..* resonance at 2.6 eV predissociates into C/sub 2/H/sup -/ and H. Four narrow resonances are observed in the transmission spectrum in the 7.5--9.5 eV region and assigned to Feshbach and core-excited shape resonances with double occupation of Rydberg orbitals and ground state positive ion core. These four resonances decay into low-lying Rydberg states of neutral acetylene, the first two undergo quasiresonant autodetachment ejecting low energy (<0.7 eV) electrons, and the lowest also dissociates to yield C/sup -//sub 2/. One additional resonance is observed in the C/sup -//sub 2/ yield, which is not observable in other decay channels. The shapes of the dissociative attachment bands differ qualitatively from the band shapes of the parent and grandparent states, indicating either a strong v dependence of the dissociation rate or the admixture of sigma* orbitals in some of the dissociating anion states.

Dressler, R.; Allan, M.

1987-10-15

236

Cavity Ringdown Laser Asorption Spectroscopy(crlas) of Isotopically Labeled Acetylene Between 12,500 - 13,600 wn  

NASA Astrophysics Data System (ADS)

About five years ago, Arkansas State University created the Arkansas Center for Laser Applications and Science (ArCLAS) with the intention of making it a state-of-the-art facility for laser-based research and optical spectroscopy in the midSouth. Since that time, University and DoD support has lead to the acquisition of numerous laser based spectrometers including a novel three color picosecond system utilized primarily for STIRAP measurements of bulk gas samples. Over the past few months, we have begun collecting near infrared overtone and combination band spectra for the acetylene molecule with a pulsed cavity ringdown laser absorption spectrometer (CRDLAS) as part of the STIRAP support effort. Certainly acetylene has been extensively studied by a number of different spectroscopic methods. During these CRDLAS investigations a 13C_2H_2 band was discovered which we believe has not been previously reported. Here a complete rovibrational analysis of this band will be presented. See for example, Michel Herman, Jacques lievin, Jean Vander Auwera, and Alain Campargue, in Global and Accurate Vibration Hamiltonians from High Resolution Molecular Spectroscopy, Advances in Chemical Physics Volume 108, John Wiley and Sons, NY, NY (1999) and references therein.

Lue, Christopher J.; Sullivan, Michael N.; Draganjac, Mark E.; Reeve, Scott W.

2011-06-01

237

Tachykinin receptor assays.  

PubMed

Described in this unit are methods for obtaining, preparing, and testing smooth muscle preparations bearing tachykinin receptors to study the agonist or antagonist properties of test compounds. Concentration-response curves to agonists are constructed to measure their ability to produce smooth muscle contractions and thus evaluate the potency and efficacy of the agonists. Antagonists are tested for their ability to shift the agonist concentration-response curve and to calculate their potency. Two different protocols are described for each of the three tachykinin receptors (NK(1), NK(2), and NK(3)). The NK(1) receptor assays use guinea pig ileum longitudinal muscle myenteric plexus (GPI) and rat urinary bladder (RUB), the NK(2) receptor assays use isolated endothelium-deprived rabbit pulmonary artery (RPA) and hamster trachea (HT), and the NK(3) receptor assays use GPI and rat portal vein (RPV). PMID:22294370

Meini, Stefania; Maggi, Carlo Alberto

2010-03-01

238

Lateral flow strip assay  

DOEpatents

A lateral flow strip assay apparatus comprising a housing; a lateral flow strip in the housing, the lateral flow strip having a receiving portion; a sample collection unit; and a reagent reservoir. Saliva and/or buccal cells are collected from an individual using the sample collection unit. The sample collection unit is immersed in the reagent reservoir. The tip of the lateral flow strip is immersed in the reservoir and the reagent/sample mixture wicks up into the lateral flow strip to perform the assay.

Miles, Robin R. (Danville, CA); Benett, William J. (Livermore, CA); Coleman, Matthew A. (Oakland, CA); Pearson, Francesca S. (Livermore, CA); Nasarabadi, Shanavaz L. (Livermore, CA)

2011-03-08

239

Just Click It: Undergraduate Procedures for the Copper(I)-Catalyzed Formation of 1,2,3-Triazoles from Azides and Terminal Acetylenes  

ERIC Educational Resources Information Center

The click chemistry uses only the most reliable reactions to build complex molecules from olefins, electrophiles and heteroatom linkers. A variation on Huisgen's azide-alkyne 1,2,3-triazole synthesis, the addition of the copper (I), the premium example of the click reaction, catalyst strongly activates terminal acetylenes towards the 1,3-dipole in…

Sharpless, William D.; Peng Wu; Hansen, Trond Vidar; Lindberg, James G.

2005-01-01

240

Synthesis of fully substituted iminolactones via a three-component condensation of isocyanides and acetylenic esters with 2-bromo-1-(4-bromophenyl)ethanone  

Microsoft Academic Search

A novel three-component condensation reaction between an isocyanide, an electron-deficient acetylenic ester, and 2-bromo-1-(4-bromophenyl)?ethanone\\u000a efficiently provides fully substituted iminolactones in a one-pot condensation reaction without any activation or modification\\u000a in high yields.

Ahmad Shaabani; Ebrohim Soleimani; Afshin Sarvary

2008-01-01

241

Methane Post-Processor Development to Increase Oxygen Recovery beyond State-of-the-Art Carbon Dioxide Reduction Technology  

NASA Technical Reports Server (NTRS)

State-of-the-art life support carbon dioxide (CO2) reduction technology, based on the Sabatier reaction, is theoretically capable of 50% recovery of oxygen from metabolic CO2. This recovery is constrained by the limited availability of reactant hydrogen. Post-processing of the methane byproduct from the Sabatier reactor results in hydrogen recycle and a subsequent increase in oxygen recovery. For this purpose, a Methane Post-Processor Assembly containing three sub-systems has been developed and tested. The assembly includes a Methane Purification Assembly (MePA) to remove residual CO2 and water vapor from the Sabatier product stream, a Plasma Pyrolysis Assembly (PPA) to partially pyrolyze methane into hydrogen and acetylene, and an Acetylene Separation Assembly (ASepA) to purify the hydrogen product for recycle. The results of partially integrated testing of the sub-systems are reported

Abney, Morgan B.; Greenwood, Zachary; Miller, Lee A.; Alvarez, Giraldo; Iannantuono, Michelle; Jones, Kenny

2013-01-01

242

Methane Post-Processor Development to Increase Oxygen Recovery beyond State-of-the-Art Carbon Dioxide Reduction Technology  

NASA Technical Reports Server (NTRS)

State-of-the-art life support carbon dioxide (CO2) reduction technology, based on the Sabatier reaction, is theoretically capable of 50% recovery of oxygen from metabolic CO2. This recovery is constrained by the limited availability of reactant hydrogen. Post-processing of the methane byproduct from the Sabatier reactor results in hydrogen recycle and a subsequent increase in oxygen recovery. For this purpose, a Methane Post-Processor Assembly containing three sub-systems has been developed and tested. The assembly includes a Methane Purification Assembly (MePA) to remove residual CO2 and water vapor from the Sabatier product stream, a Plasma Pyrolysis Assembly (PPA) to partially pyrolyze methane into hydrogen and acetylene, and an Acetylene Separation Assembly (ASepA) to purify the hydrogen product for recycle. The results of partially integrated testing of the sub-systems are reported.

Abney, Morgan; Miller, Lee; Greenwood, Zach; Iannantuono, Michelle; Jones, Kenny

2013-01-01

243

Multiplexed Elispot assay.  

PubMed

Micron scale latex beads are well established as highly biocompatible reagents. Imbibing two fluorescent dyes into the interior of the beads enables the creation of a family of combinatorially colored labels. Previous use of such beads, in flow cytometry for example, has focused on beads of approximately 5 microm diameter. We show here that 280 nm combinatorially labeled particles can be used to create ELISA-style assays in 200 microm scale virtual wells, using digital microscopy as the readout. The utility of this technique is illustrated by profiling the secreted cytokine footprints of peripheral blood mononuclear cells in a multiparametric version of the popular Elispot assay. Doing so reveals noncanonical classes of T lymphocytes. We further show that the secreting cell type can be concurrently identified by surface staining with a cell type specific antibody conjugated to the same multiplexed beads. PMID:19084532

Harriman, William D; Collarini, Ellen J; Cromer, Remy G; Dutta, April; Strandh, Magnus; Zhang, Fen; Kauvar, Lawrence M

2009-02-28

244

Kinetic Tetrazolium Microtiter Assay  

NASA Technical Reports Server (NTRS)

Kinetic tetrazolium microtiter assay (KTMA) involves use of tetrazolium salts and Triton X-100 (or equivalent), nontoxic, in vitro color developer solubilizing colored metabolite formazan without injuring or killing metabolizing cells. Provides for continuous measurement of metabolism and makes possible to determine rate of action of antimicrobial agent in real time as well as determines effective inhibitory concentrations. Used to monitor growth after addition of stimulatory compounds. Provides for kinetic determination of efficacy of biocide, greatly increasing reliability and precision of results. Also used to determine relative effectiveness of antimicrobial agent as function of time. Capability of generating results on day of test extremely important in treatment of water and waste, disinfection of hospital rooms, and in pharmaceutical, agricultural, and food-processing industries. Assay also used in many aspects of cell biology.

Pierson, Duane L.; Stowe, Raymond; Koenig, David

1993-01-01

245

Isotope effect in acetylene C2H2 and C2D2 rotations on Cu(001)  

NASA Astrophysics Data System (ADS)

A comprehensive analysis of the elementary processes behind the scanning tunneling microscope controlled rotation of C2H2 and C2D2, isotopologues of a single acetylene molecule adsorbed on the Cu(001) surface, is given, with a focus on the isotope effects. With the help of density-functional theory we calculate the vibrational modes of C2H2 and C2D2 on Cu(001) and estimate the anharmonic couplings between them, using a simple strings-on-rods model. The probability of the elementary processes, nonlinear and combination band, is estimated using the Keldysh diagram technique. This allows us to clarify the main peculiarities and the isotope effects of the C2H2 and C2D2 on Cu(001) rotation, discovered in the pioneering work [B. C. Stipe et al., Phys. Rev. Lett. 81, 1263 (1998), 10.1103/PhysRevLett.81.1263], which have not been previously understood.

Shchadilova, Yulia E.; Tikhodeev, Sergei G.; Paulsson, Magnus; Ueba, Hiromu

2014-04-01

246

ABSORPTION CROSS SECTION OF GASEOUS ACETYLENE AT 85 K IN THE WAVELENGTH RANGE 110-155 nm  

SciTech Connect

Absorption spectra and absorption cross sections of gaseous acetylene, C{sub 2}H{sub 2}, at 298 and 85 K were measured in the wavelength range 110-155 nm with a slit-jet system coupled to a synchrotron as a source of vacuum ultraviolet light. Using published spectral parameters of C{sub 2}H{sub 2}, we simulated the absorption profile for the Rydberg transition to state 4R{sub 0} in the range 124.6-125.1 nm, according to which the temperature of the jet-expanded sample at stagnation pressure 200 Torr is 85 {+-} 5 K. Our cross sections of C{sub 2}H{sub 2} are applicable for determining properties sensitive to temperature for diagnostic work on Saturn and Titan.

Cheng, Bing-Ming; Chen, Hui-Fen; Lu, Hsiao-Chi; Chen, Hong-Kai; Alam, M. S.; Chou, Sheng-Lung; Lin, Meng-Yeh, E-mail: bmcheng@nsrrc.org.tw [National Synchrotron Radiation Research Center, No. 101, Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)

2011-09-01

247

Histrionicotoxins: Roentgen-Ray Analysis of the Novel Allenic and Acetylenic Spiroalkaloids Isolated from a Colombian Frog, Dendrobates histrionicus  

PubMed Central

The structures and absolute configuration of two unique alkaloids isolated from the Colombian frog, Dendrobates histrionicus, have been elucidated by Roentgen-ray (x-ray) crystallography. Histrionicotoxin is (2pR, 6S, 7pS, 8aS)-7-(cis-1-buten-3-ynyl)-8-hydroxy-2-(cis-2-penten-4- ynyl)-1-azaspiro[5.5] undecane, while in dihydro-isohistrionicotoxin the acetylenic 2-pentenynyl side chain is replaced by an allenic 2-(3,4 pentadienyl) substituent. Dendrobates histrionicus exhibits remarkable interpopulational variations in amounts and composition of skin toxins, in behavior, and in phenotypic characters, aspects of which are illustrated in a color plate. The histrionico-toxins are the third class of alkaloids isolated from the defensive skin secretions of Neotropical (Dendrobatidae) frogs. Images PMID:5288773

Daly, John W.; Karle, Isabella; Myers, Charles W.; Tokuyama, Takashi; Waters, James A.; Witkop, Bernhard

1971-01-01

248

Microcalorimetric assay of acetylcholinesterase.  

PubMed

Comparative assays were made in a spectrophotometer and a microcalorimeter for the reaction between acetylcholinesterase (EC 3.1.1.7) and acetylthiocholine. The rate of light absorbance change and the rate of heat flow were measured from similar and simultaneous reactions in spectrophotometer and microcalorimeter, respectively. At the enzyme activity levels studied, i.e., 0.05-0.15 I.U. in calorimetry and 1-4 I.U. in spectrophotometry, the reaction rates were linear and showed first-order kinetics A highly significant positive correlation was seen between the two methods (r = 0.997). More importantly, spectrophotometric assay with acetylthiocholine (which utilized a secondary reaction with chromagen, dithiobisnitrobenzoic acid) stood in highly significant positive correlation with calorimetric assays (which did not require a chromagen) either with the same substrate (r = 0.976) or with acetylcholine (r = 0.900). It appears that microcalorimetry can be used in preference to spectrophotometry for enzyme kinetic studies to overcome the complexity of reaction mixture and interference problems and with the advantage of using natural substrates. PMID:7370307

Rosenstein, S; Brown, H D

1980-04-17

249

Carbon Dioxide Reduction Post-Processing Sub-System Development  

NASA Technical Reports Server (NTRS)

The state-of-the-art Carbon Dioxide (CO2) Reduction Assembly (CRA) on the International Space Station (ISS) facilitates the recovery of oxygen from metabolic CO2. The CRA utilizes the Sabatier process to produce water with methane as a byproduct. The methane is currently vented overboard as a waste product. Because the CRA relies on hydrogen for oxygen recovery, the loss of methane ultimately results in a loss of oxygen. For missions beyond low earth orbit, it will prove essential to maximize oxygen recovery. For this purpose, NASA is exploring an integrated post-processor system to recover hydrogen from CRA methane. The post-processor, called a Plasma Pyrolysis Assembly (PPA) partially pyrolyzes methane to recover hydrogen with acetylene as a byproduct. In-flight operation of post-processor will require a Methane Purification Assembly (MePA) and an Acetylene Separation Assembly (ASepA). Recent efforts have focused on the design, fabrication, and testing of these components. The results and conclusions of these efforts will be discussed as well as future plans.

Abney, Morgan B.; Miller, Lee A.; Greenwood, Zachary; Barton, Katherine

2012-01-01

250

Reduction cranioplasty.  

PubMed

Reduction cranioplasty can greatly improve the quality of life for selected patients with severe macrocephaly and can significantly diminish some of the difficulties in the long-term chronic care of others. Because of differences in age, cranial morphology and surgical goals, the surgical plan must be tailored to the individual patient. Three techniques for reduction cranioplasty, with the advantages and disadvantages of each, are described. Four patients, representing the spectrum of severe macrocephaly and also the problems associated with reduction cranioplasty, are presented. Surgical indications, tactical considerations and risks are discussed. PMID:7547453

Winston, K R; Ogilvy, C S; McGrail, K

1995-01-01

251

Enhanced reductive dechlorination of tetrachloroethene during reduction of cobalamin (III) by nano-mackinawite.  

PubMed

We demonstrated adsorption and reduction of cobalamin(III) (Co(III)) on nano-mackinawite (nFeS) surface and their impact on reductive dechlorination of tetrachloroethene (PCE). The adsorption of Co(III) on the nFeS surface followed Langmuir isotherm and the reduction of Co(III) provided different reactive surface chemical species on nFeS surface. Content of Fe(2+)S on nFeS surface decreased (45.9-14.5%) as Fe(2+)S was oxidized to Fe(3+)S and Fe(3+)O coupled with the surface reduction of Co(III) to cobalamin(II) (Co(II)). S(2-) and S(n)(2-) contents on the nFeS surface also decreased by 48.5% and 82.3%, respectively during the formation of sulfidecobalamin(II) (?S(2-)Co(II)) by the reactive surface sulfur. PCE was fully degraded in nFeSCo(III) suspension at pH 8.3 in 120 h. The dechlorination kinetic rate constant of PCE in the nFeSCo(III) suspension (k(FeSCo(III))=0.188±0.003 h(-1)) was 145 times greater than that in nFeS suspension, showing a potential role of ?S(2-)Co(II) as an electron transfer mediator to shuttle electrons for the enhanced reductive dechlorination. PCE was transformed to acetylene and 1,3-butadiene as major products via reductive ?-elimination and isomerization reactions, respectively. The experimental findings can provide basic knowledge to identify a reaction mechanism for the enhanced reductive dechlorination of chlorinated organic by biogeochemical reactions possibly observed in natural reducing environments. PMID:22939091

Amir, Amnorzahira; Lee, Woojin

2012-10-15

252

Pathways and kinetics of chlorinated ethylene and chlorinated acetylene reaction with Fe(O) particles  

Microsoft Academic Search

Pathways and kinetics through which chlorinated ethylenes and their daughter products react with Fe(O) particles were investigated through batch experiments. Substantial intra- and interspecies inhibitory effects were observed, requiring the use of a modified Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model in which species compete for a limited number of reactive sites at the particle-water interface. Results indicate that reductive β-elimination accounts for

William A. Arnold; A. Lynn Roberts

2000-01-01

253

Measuring antioxidant potential in corals using the FRAP assay  

Microsoft Academic Search

In this paper, we standardized a method for determining antioxidant potential in corals. This was determined using a simple, reproducible and inexpensive method: the ferric reducing\\/antioxidant potential (FRAP) assay. This procedure involves the reduction of FeIII-TPTZ to a blue colored FeII-TPTZ by biological antioxidants and chemical reductants, some of which might have no antioxidant activity in a sample. The FRAP

Sean P. Griffin; Ranjeet Bhagooli

2004-01-01

254

Test procedure for boxed waste assay system  

SciTech Connect

This document, prepared by Los Alamos National Laboratory`s NMT-4 group, details the test methodology and requirements for Acceptance/Qualification testing of a Boxed Waste Assay System (BWAS) designed and constructed by Pajarito Scientific Corporation. Testing of the BWAS at the Plutonium Facility (TA55) at Los Alamos National Laboratory will be performed to ascertain system adherence to procurement specification requirements. The test program shall include demonstration of conveyor handling capabilities, gamma ray energy analysis, and imaging passive/active neutron accuracy and sensitivity. Integral to these functions is the system`s embedded operating and data reduction software.

Wachter, J. [Los Alamos National Lab., NM (United States)

1994-12-07

255

Yeast DEL assay detects clastogens.  

PubMed

Chromosomal rearrangements, including DNA deletions are involved in carcinogenesis. The deletion (DEL) assay scoring for DNA deletions in the yeast Saccharomyces cerevisiae is able to detect a wide range of carcinogens. Among approximately 60 compounds of known carcinogenic activity, the DEL assay detected 86% correctly whereas the Ames Salmonella assay detected only 30% correctly [R.J. Brennan, R.H. Schiestl, Detecting carcinogens with the yeast DEL assay, Methods Mol. Biol. 262 (2004) 111-124]. Since the DEL assay is highly inducible by DNA double strand breaks, this study examined the utility of the DEL assay for detecting clastogens. Ten model compounds, with varied mechanisms of genotoxicity, were examined for their effect on the frequency of DNA deletions with the DEL assay. The compounds tested were: actinomycin D, camptothecin, methotrexate and 5-fluorodeoxyuridine, which are anticancer agents, noscapine and furosemide are therapeutics, acridine, methyl acrylate and resorcinol are industrial chemicals and diazinon is an insecticide. The in vitro micronucleus assay (IVMN) in CHO cells, a commonly used tool for detection of clastogens, was performed on the same compounds and the results of the two assays were compared. The results of our study show that there is 70% concordance in the presence of metabolic activation (rat liver S9) and 80% concordance in the absence of metabolic activation between the DEL assay and the standard in vitro micronucleus assay. The lack of cytotoxicity observed for four of the ten compounds examined indicates limited diffusion of lipophilic compounds across the yeast cell wall. Thus, the development of a more permeable yeast tester strain is expected to greatly improve concordance of the DEL assay with the IVMN assay. The yeast DEL assay is inexpensive, amenable to automation and requires less expertise to perform than the IVMN. Thus, it has a strong potential as a robust, fast and economical screen for detecting clastogens in vitro. PMID:15781217

Kirpnick, Zhanna; Homiski, Michael; Rubitski, Elizabeth; Repnevskaya, Marina; Howlett, Niall; Aubrecht, Jiri; Schiestl, Robert H

2005-04-01

256

Recent Line-Shape and Doppler Thermometry Studies Involving Transitions in the ?1 +?3 Band of Acetylene  

NASA Astrophysics Data System (ADS)

The line positions for transitions in the ?1 +?3 band are often used as a frequency standard by the telecom industry and also needed for planetary atmospheric studies. Four relevant studies have been recently carried out in our group and will be discussed briefly below. (1) N2-broadened line widths and N2-pressure induced line shifts have been measured for transitions in the ?1 +?3 band of acetylene at seven temperatures in the range 213333K to obtain the temperature dependences of broadening and shift coefficients. The Voigt and hard-collision line profile models were used to retrieve the line parameters. This study has been published in Molecular Physics, 110 Issue 21/22 (2012) 2645-2663. (2) Six nitrogen perturbed transitions of acetylene within the ?1 +?3 absorption band have been recorded using a 3-channel diode laser spectrometer. We have examined C2H2 spectra using a hard collision (Rautian) profile over a range of five temperatures (213 K-333 K). From these fits we have obtained the N2-broadening and narrowing coefficients of C2H2 and examined their temperature dependence. The experimentally measured narrowing coefficients have been used to estimate the nitrogen diffusion coefficients. The broadening coefficients and corresponding temperature dependence exponents have also been compared to that of calculations completed using a classical impact approach on an ab initio potential energy surface. We have observed a good agreement between our theoretical and experimental results. This study was published in Canadian Journal of Physics 91(11) 896-905 (2013). (3) An extension of the previous study was to analyze the room temperature for the same six transitions using the Voigt, Rautian, Galatry, RautianGalatry and Correlated Rautian profiles. For the entire pressure range, we have tested the applicability of these line-shape models. Except for Voigt profile, Dicke narrowing effect has been considered in all mentioned line-shape models. The experimental results for the narrowing parameters have been compared with calculated values based on the theory of diffusion. This study is in press in press in the Journal of Quantitative Spectroscopy and Radiative Transfer. (4) In this paper we present accurate measurements of the fundamental Boltzmann constant based on a lineshape analysis of acetylene spectra in the ?1 +?3 band recorded using a tunable diode laser. Experimental spectra recorded at low pressures have been analyzed using both the Voigt model and the Speed Dependent Voigt model that takes into account the molecular speed dependence effects. These line-shape models reproduces the experimental data with high accuracy and allow us to determine precise line-shape parameters for the transitions used, the Doppler-width and then determined the Boltzmann constant, kB. This study has been submitted for publication in the Journal of Chemical Physics. 1 1 Research described in this work was funded by NSERC, Canada.

Hashemi, Robab; Rozario, Hoimonti; Povey, Chad; Garber, Jolene; Derksen, Mark; Predoi-Cross, Adriana

2014-06-01

257

Comprehensive photokinetic and NMR study of a biphotochromic supermolecule involving two naphthopyrans linked to a central thiophene unit through acetylenic bonds.  

PubMed

A photophysical and photochemical study of a biphotochromic compound where two naphthopyran units are linked by an acetylene-thiophene-acetylene bridge has been carried out in toluene. Both fluorescence and intersystem crossing to the triplet manifold were found to compete with the photocoloration process. Two photoproducts (transoid-trans and transoid-cis stereoisomers), absorbing at approximately 480 nm and corresponding to the opening of a single photochromic unit, were detected by spectrophotometric analysis after short irradiation time in diluted solution and identified by 1H-nuclear magnetic resonance (NMR) spectroscopy. After prolonged irradiation at 228 K of highly concentrated solutions (up to 3 x 10(-3) mol dm(-3)), two additional isomers, absorbing at approximately 550 nm, were formed. Their NMR spectra indicate the opening of both photochromic units. An interesting effect of selective vibronic excitation was found, showing that the photoreaction is favored at excited vibronic levels to the detriment of the radiative relaxation. PMID:14743863

Ortica, Fausto; Moustrou, Corinne; Berthet, Jérôme; Favaro, Gianna; Samat, André; Guglielmetti, Robert; Vermeersch, Gaston; Mazzucato, Ugo

2003-12-01

258

Synthesis of 3-iodoindoles by the Pd/Cu-catalyzed coupling of N,N-dialkyl-2-iodoanilines and terminal acetylenes, followed by electrophilic cyclization.  

PubMed

[reaction: see text] 3-Iodoindoles have been prepared in excellent yields by coupling terminal acetylenes with N,N-dialkyl-o-iodoanilines in the presence of a Pd/Cu catalyst, followed by an electrophilic cyclization of the resulting N,N-dialkyl-o-(1-alkynyl)anilines using I2 in CH2Cl2. Aryl-, vinylic-, alkyl-, and silyl-substituted terminal acetylenes undergo this process to produce excellent yields of 3-iodoindoles. The reactivity of the carbon-nitrogen bond cleavage during cyclization follows the following order: Me > n-Bu, Me > Ph, and cyclohexyl > Me. Subsequent palladium-catalyzed Sonogashira, Suzuki, and Heck reactions of the resulting 3-iodoindoles proceed smoothly in good yields. PMID:16388618

Yue, Dawei; Yao, Tuanli; Larock, Richard C

2006-01-01

259

Measurements of linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene in the ?4+?5 combination band using a cw quantum cascade laser  

NASA Astrophysics Data System (ADS)

Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296 K in the P branch of the ?4+?5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296-683 K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253-1310 cm-1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ?4+?5 combination band and other vibrational bands of acetylene.

Sajid, Muhammad Bilal; Es-sebbar, Et-touhami; Farooq, Aamir

2014-11-01

260

The effect of added acetylene on the rf discharge chemistry of C2F6. A mechanistic model for fluorocarbon plasmas  

NASA Astrophysics Data System (ADS)

The effect of added acetylene on the rf discharge chemistry of C2F6 was studied as a function of acetylene concentration. The principle products are HF, CF4, CHF3, C2F4, and CF2 as determined by mass spectrometry. Under conditions typically used for etching SiO2, residence time and power density control the amount of conversion of feed gas to products. Large amounts of polymeric material, with composition (CF)n, are formed in the discharge zone. A chemical model for flourocarbon discharges is proposed, which assumes an equilibrium between dissociation and recombination of flourocarbon fragments and flourine atoms. Polymerization and selective etching of Si and SiO2 in flourocarbon dishcarges containing oxygen or hydrogen additives is interpreted in terms of the proposed model.

Truesdale, E. A.; Smolinsky, G.; Mayer, T. M.

1980-05-01

261

Synthesis of indoles, benzofurans, and related heterocycles via an acetylene-activated SNAr/intramolecular cyclization cascade sequence in water or DMSO.  

PubMed

The synthesis of 2-substituted indoles and benzofurans was achieved by nucleophilic aromatic substitution, followed by subsequent 5-endo-dig cyclization between the nucleophile and an ortho acetylene. The acetylene serves the dual role of the electron withdrawing group to activate the substrate for SNAr, and the C1-C2 carbon scaffold for the newly formed 5-membered heteroaromatic ring. This method allows for the bond forming sequence of Ar-X-N/O-C1 to proceed in a single synthetic step, furnishing indoles and benzofurans in moderate to high yields. Since the method is not transition metal mediated, brominated and chlorinated substrates are tolerated, and benzofuran formation can be conducted using water or water-DMSO mixtures as solvent. PMID:25608594

Hudson, R; Bizier, N P; Esdale, K N; Katz, J L

2015-02-10

262

Evaluation of the porcine gastric mucin binding assay for high pressure inactivation studies using murine norovirus and Tulane virus.  

PubMed

We compared high hydrostatic pressure (HHP) inactivation results of murine norovirus (MNV-1) and Tulane virus (TV) obtained through the porcine gastric mucin binding assay (referred to as PGM-MB/PCR assay) and plaque assay and evaluated HHP inactivation of human norovirus (HuNoV) GI.1 and GII.4 strains using the PGM-MB/PCR assay. Viruses were treated at different pressure levels for 2 min at 4 or 21°C in culture media of neutral pH and in culture media of pH 4 at 21°C. The log reductions of infectious virus particles of MNV-1 and TV caused by HHP were assessed using the PGM-MB/PCR and plaque assays while the log reductions of HuNoVs were assessed by the PGM-MB/PCR assay only. For TV and MNV-1, the two pressure inactivation curves obtained using the plaque and PGM-MB/PCR assays were almost identical at ? ?2-log reduction levels regardless the treatment temperature and pH. Further increasing the pressure level over the ?2 log reduction level resulted in higher log reductions of TV and MNV-1 assessed by the plaque assay, but did not increase the log reductions assessed by the PGM-MB/PCR assay. HHP treatments could achieve maximums of ?3 and 3.5 log reductions of GI.1 and GII.4 assessed by PGM-MB/PCR assay, respectively. Based on these results, it can be reasonably concluded that the PGM-MB/PCR assay would be very likely able to estimate HHP inactivation of HuNoV at ? 2 log-reduction levels. It would also likely to conservatively quantify HHP inactivation of GI.1 strain at 2-3 log-reduction levels and GII.4 strain at 2-3.5 log-reduction levels. PMID:25362063

Li, Xinhui; Chen, Haiqiang

2014-10-31

263

Catalytic decomposition of acetylene over CoFe 2O 4\\/BaFe 12O 19 core shell nanoparticles for the production of carbon nanotubes  

Microsoft Academic Search

In this study, carbon nanotubes were formed by acetylene decomposition on hydrogen-reduced CoFe2O4\\/BaFe12O19 core shell catalysts at 500–800°C. X-ray diffraction (XRD) was used to examine the crystal characteristics of catalysts. The carbon nanotubes were also examined both by transmission electron microscopy (TEM) to define their appearance and structure. Little amount of carbon nanotubes were found on the catalyst surface at

M. H. Khedr; M. Bahgat; S. A. Abdel-Moaty

2009-01-01

264

Chain extension and crosslinking of telechelic oligomers—I. Michael additions of bisamines to bismaleimides and bis(acetylene ketone)s  

Microsoft Academic Search

Some commercial amine-ended oligo(oxypropylene)s and oligo(oxyethylene-b-oxypropylene)s, and an amine-ended oligo(dimethylsiloxane), have been chain extended via Michael additions with some simple bismaleimides and bis(acetylene ketone)s. The polymers so-formed have molar masses of up to ca 20,000, corresponding to degrees of polymerization of the starting oligomers of up to ca 15. The polymers are either linear (and therefore soluble) or crosslinked, depending

Leslie R. Dix; John R. Ebdon; Nicholas J. Flint; Philip Hodge; Richard O'Dell

1995-01-01

265

The Influence of Mixing on Staged Flame Processes (Synthesis of Hydrogen Cyanide or Acetylene and Ethylene by Light Hydrocarbons in a Flame Reaction)  

Microsoft Academic Search

The formation of hydrogen cyanide by propane and ammonia and the formation of acetylene and ethylene by propane in flame-reactions was investigated in a special burner using pure oxygen as oxidant. It was possible to perform the reactions in a one-stage or a two-stage process under turbulent flow conditionsIn the case of hydrogen cyanide formation in a one-stage process propane,

H. BOCKHORN; N. GALDO; H. A. KERBERTZ; F. FETTING

1971-01-01

266

Violence reduction.  

PubMed

As one of the first violence-reduction nurses in the country, Alice Kershberg gathers data on the assaults against people who have presented to her emergency department, and works with the police and local councils to reduce violence in her local community. Here, Ms Kershberg talks to Erin Dean about her role and aspects of her career. PMID:24689483

Dean, Erin; Kershberg, Alice

2014-04-01

267

Selective Hydrogenation of Acetylene in the Presence of Ethylene on K+ -beta-Zeolite Supported Pd and PdAg Catalysts  

SciTech Connect

The selective hydrogenation of acetylene in the presence of ethylene has been studied on K+ exchanged {beta}-zeolite supported Pd and PdAg catalysts. Results from batch reactor studies with Fourier transform infrared spectroscopy (FTIR) have shown that the K+-{beta}-zeolite support is more selective than the Al2O3 or Na+-{beta}-zeolite supports toward the hydrogenation of acetylene. The rate and equilibrium constants for Pd/K+-{beta}-zeolite and PdAg/K+-{beta}-zeolite were determined using a Langmuir-Hinshelwood model. The selectivity of the PdAg bimetallic catalyst is twice of that of the Pd catalyst. Results from flow reactor studies show that the PdAg/K+-{beta}-zeolite catalyst has higher selectivity but lower activity toward acetylene hydrogenation than the Pd/K+-{beta}-zeolite catalyst. The selectivity to the undesirable ethane by-product is inhibited on the bimetallic catalyst. Extended X-ray absorption fine structure (EXAFS) studies and transmission electron microscope (TEM) analysis confirm the formation of Pd-Ag bimetallic bonds in the PdAg/K+-{beta}-zeolite catalyst.

Huang,W.; Pyrz, W.; Lobo, R.; Chen, J.

2007-01-01

268

NCI Launches Proteomics Assay Portal  

Cancer.gov

In a paper recently published by the journal Nature Methods, Investigators from the National Cancer Institute’s Clinical Proteomic Tumor Analysis Consortium (NCI-CPTAC) announced the launch of a proteomics Assay Portal for multiple reaction monitoring-mass spectrometry (MRM-MS) assays. This community web-based repository for well-characterized quantitative proteomic assays currently consists of 456 unique peptide assays to 282 unique proteins and serves as a public resource of methodologies and data related to cancer associated targets.

269

Optimization of Acetylene Black Conductive Additive andPolyvinylidene Difluoride Composition for High Power RechargeableLithium-Ion Cells  

SciTech Connect

Fundamental electrochemical methods were applied to study the effect of the acetylene black (AB) and the polyvinylidene difluoride (PVDF) polymer binder on the performance of high-power designed rechargeable lithium ion cells. A systematic study of the AB/PVDF long-range electronic conductivity at different weight ratios is performed using four-probe direct current tests and the results reported. There is a wide range of AB/PVDF ratios that satisfy the long-range electronic conductivity requirement of the lithium-ion cathode electrode; however, a significant cell power performance improvement is observed at small AB/PVDF composition ratios that are far from the long-range conductivity optimum of 1 to 1.25. Electrochemical impedance spectroscopy (EIS) tests indicate that the interfacial impedance decreases significantly with increase in binder content. The hybrid power pulse characterization results agree with the EIS tests and also show improvement for cells with a high PVDF content. The AB to PVDF composition plays a significant role in the interfacial resistance. We believe the higher binder contents lead to a more cohesive conductive carbon particle network that results in better overall all local electronic conductivity on the active material surface and hence reduced charge transfer impedance.

Liu, G.; Zheng, H.; Battaglia, V.S.; Simens, A.S.; Minor, A.M.; Song, X.

2007-07-01

270

Fourier transform spectroscopy using a synchrotron source: Characterization of the instrument line shape and acetylene line parameters around 100 ?m  

NASA Astrophysics Data System (ADS)

The acetylene 100 ?m spectral region of astrophysical interest was studied to retrieve absolute line positions and intensities of weak hot bands. An absorption path of 150 m was used and the spectra were recorded using the far-infrared AILES beamline of the synchrotron SOLEIL and a Bruker IFS 125-HR. To achieve accurate measurements from FT spectra using the full beam of the synchrotron, special cares have been taken into account concerning the apparatus function and especially the optical weighting. The wavenumber dependence of the size of the synchrotron beam was modeled leading to similar results that have been previously obtained for the analysis of the ?5-?4 band ([8] Jacquemart et al., J Quant Spectrosc Radiat Transfer 2010;111:1223-33) but with a better precision. In the present work, line positions and intensities have been measured for the first time for 816 transitions of 12C2H2 belonging to 17 bands between 51 and 215 cm-1. The accuracy of measurements are estimated to be around 0.1×10-3 cm-1 for line positions and between 5 and 10% for intensities depending on the strength of the transitions. The spectroscopic knowledge of these hot bands is of importance especially for theoretical and astrophysical applications.

Jacquemart, D.; Chaboud, M.

2013-04-01

271

The photolysis of NH3 in the presence of substituted acetylenes: a possible source of oligomers and HCN on Jupiter.  

PubMed

Photolysis of NH3 in the presence of propyne yields dimethylketazine (4) as the main product along with dimethylketimine, isopropylamine, and propioazine (7). Dimethylketazine and isopropylamine are the principal reaction products when the photolysis is performed at 198 K. The conversion to dimethylketazine is about 35 times greater at 198 K because it is not volatile and condenses on the wall of the photolysis cell out of the UV flux. Photolysis of dimethylketazine at 185 nm yields acetonitrile and small amounts of N-methyldimethylketimine (8). Photolysis of 8 gives acetonitrile. Photolysis of NH3 in the presence of 2-butyne gives the cis and trans isomers of 2-butene as the principal products along with the corresponding azine (9). Photolysis of azine 9 yields acetonitrile and propionitrile. Photolysis of hydrazine in the presence of propyne yields acetonitrile and isopropylamine but no azines were detected as reaction products. Quantum yields and percentage conversion to products are reported. These studies show that acetylenic hydrocarbons formed by the photolysis of methane in the stratosphere of Jupiter may react with radicals formed by NH3 photolysis to give nonvolatile yellow-brown polymers, dialkylazines, alkylnitriles, and eventually HCN. This scenario accounts for the observation of both HCN and chromophores on Jupiter. PMID:11538398

Ferris, J P; Jacobson, R R; Guillemin, J C

1992-01-01

272

COMPUTATIONAL MODELING AND EXPERIMENTAL STUDIES ON NOx REDUCTION UNDER PULVERIZED COAL COMBUSTION CONDITIONS  

SciTech Connect

In this work, both computer simulation and experimental studies were conducted to investigate several strategies for NO{sub x} reduction under pulverized coal combustion conditions with an aim to meet the stringent environmental standards for NO{sub x} control. Both computer predictions and reburning experiments yielded favorable results in terms of NO{sub x} control by reburning with a combination of methane and acetylene as well as non-selective catalytic reduction of NO{sub x} with ammonia following reburning with methane. The greatest reduction was achieved at the reburning stoichiometric ratio of 0.9; the reduction was very significant, as clearly shown in Chapters III and V. Both the experimental and computational results favored mixing gases: methane and acetylene (90% and 10% respectively) and methane and ammonia (98% and 2%) in order to get optimum reduction levels which can not be achieved by individual gases at any amounts. Also, the above gaseous compositions as reburning fuels seemed to have a larger window of stoichiometric ratio (SR2 < 0.9) as opposed to just methane (SR2=0.9) so as to reduce and keep NO{sub x} at low ppm levels. From the various computational runs, it has been observed that although there are several pathways that contribute to NO{sub x} reduction, the key pathway is NO {r_arrow} HCN {r_arrow} NH{sub 3} {r_arrow} N{sub 2} + H{sub 2}. With the trends established in this work, it is possible to scale the experimental results to real time industrial applications using computational calculations.

Subha K. Kumpaty; Kannikeswaran Subramanian; Victor P. Nokku; Tyrus L. Hodges; Adel Hassouneh; Ansumana Darboe; Sravan K. Kumpati

1998-06-01

273

PathogenMip Assay: A Multiplex Pathogen Detection Assay  

PubMed Central

The Molecular Inversion Probe (MIP) assay has been previously applied to a large-scale human SNP detection. Here we describe the PathogenMip Assay, a complete protocol for probe production and applied approaches to pathogen detection. We have demonstrated the utility of this assay with an initial set of 24 probes targeting the most clinically relevant HPV genotypes associated with cervical cancer progression. Probe construction was based on a novel, cost-effective, ligase-based protocol. The assay was validated by performing pyrosequencing and Microarray chip detection in parallel experiments. HPV plasmids were used to validate sensitivity and selectivity of the assay. In addition, 20 genomic DNA extracts from primary tumors were genotyped with the PathogenMip Assay results and were in 100% agreement with conventional sequencing using an L1-based HPV genotyping protocol. The PathogenMip Assay is a widely accessible protocol for producing and using highly discriminating probes, with experimentally validated results in pathogen genotyping, which could potentially be applied to the detection and characterization of any microbe. PMID:17311101

Akhras, Michael S.; Thiyagarajan, Sreedevi; Villablanca, Andrea C.; Davis, Ronald W.; Nyrén, Pål; Pourmand, Nader

2007-01-01

274

Remarkable behavior of a bifunctional alkynylborane zirconocene complex toward donor ligands and acetylenes.  

PubMed

Treatment of a [(trimethylsilylethynyl)alkenyl]ZrCp2 complex with Piers' borane [HB(C6F5)2] resulted in the clean formation of the Zr/B complex [?(2)-(C6F5)2B-C?C-SiMe3]ZrCp2 (3). This compound shows some unique reaction patterns. With a variety of typical donor ligands (carbon monoxide, an isonitrile, a nitrile, THF-d8,) it forms the respective adducts 5 (four examples characterized by X-ray diffraction). Toward terminal alkynes (RC?CH) compound 3 behaves as a Zr(II) metal Lewis base/boron Lewis acid frustrated Lewis pair (FLP) and undergoes typical regioselective 1,2-Zr/B addition reactions to yield the metallaheterocyclic products 7 (four examples characterized by X-ray diffraction). Compound 3 also undergoes characteristic 1,4-Zr/B FLP addition to a silyl-substituted conjugated enyne (to give 9) and also to 1,4-bis(trimethylsilyl)butadiyne to yield a metallacyclic butatriene derivative 10 (both 9 and 10 were characterized by X-ray diffraction). Eventually, compound 3 reacted with mes2P-C?CH to give the metallacycloallenoid product 15, which was probably formed by means of 1,2-Zr/B FLP addition followed by alkynyl shift from boron to zirconium and reductive coupling. Treatment of 3 with tolane gave the closely related zirconacycloallenoid complex 16 by carbon carbon coupling. Both the products 15 and 16 were characterized by X-ray diffraction. PMID:24128274

Podiyanachari, Santhosh Kumar; Kehr, Gerald; Mück-Lichtenfeld, Christian; Daniliuc, Constantin G; Erker, Gerhard

2013-11-20

275

From Antenna to Assay  

PubMed Central

Conspectus Ligand-sensitized, luminescent lanthanide(III) complexes are of considerable importance because their unique photophysical properties (microsecond to millisecond lifetimes, characteristic and narrow emission bands, and large Stokes shifts) make them well suited as labels in fluorescence-based bioassays. The long-lived emission of lanthanide(III) cations can be temporally resolved from scattered light and background fluorescence to vastly enhance measurement sensitivity. One challenge in this field is the design of sensitizing ligands that provide highly emissive complexes with sufficient stability and aqueous solubility for practical applications. In this Account, we give an overview of some of the general properties of the trivalent lanthanides and follow with a summary of advances made in our laboratory in the development of highly luminescent Tb(III) and Eu(III) complexes for applications in biotechnology. A focus of our research has been the optimization of these compounds as potential commercial agents for use in Homogeneous Time-Resolved Fluorescence (HTRF) technology. Our approach involves developing high-stability octadentate Tb(III) and Eu(III) complexes that rely on all-oxygen donor atoms and using multi-chromophore chelates to increase molar absorptivity; earlier examples utilized a single pendant chromophore (that is, a single “antenna”). Ligands based on 2-hydroxyisophthalamide (IAM) provide exceptionally emissive Tb(III) complexes with quantum yield values up to ?60% that are stable at the nanomolar concentrations required for commercial assays. Through synthetic modification of the IAM chromophore and time-dependent density functional theory (TD-DFT) calculations, we have developed a method to predict absorption and emission properties of these chromophores as a tool to guide ligand design. Additionally, we have investigated chiral IAM ligands that yield Tb(III) complexes possessing both high quantum yield values and strong circularly polarized luminescence (CPL) activity. To efficiently sensitize Eu(III) emission, we have used the 1-hydroxypyridin-2-one (1,2-HOPO) chelate to create remarkable ligands that combine excellent photophysical properties and exceptional aqueous stabilities. A more complete understanding of this chromophore has been achieved by combining low-temperature phosphorescence measurements with the same TD-DFT approach used with the IAM system. Eu(III) complexes with strong CPL activity have also been obtained with chiral 1,2-HOPO ligands. We have also undertaken the kinetic analysis of radiative and non-radiative decay pathways for a series of Eu(III) complexes; the importance of the metal ion symmetry on the ensuing photophysical properties is clear. Lastly, we describe a Tb(III)-IAM compound—now carried through to commercial availability—that offers improved performance in the common HTRF platform and has the potential to vastly improve sensitivity. PMID:19323456

Moore, Evan G.; Samuel, Amanda P. S.; Raymond, Kenneth N.

2009-01-01

276

Doug Berndt Evaluated Bacterial Assay  

USGS Multimedia Gallery

USGS microbiology technician evaluates a bacterial assay to determine the cause of a wildlife mortality. The USGS National Wildlife Health Center works to identify, track, and prevent wildlife disease....

277

Laser-induced dispersed vibration-rotation fluorescence of acetylene: Spectra of ortho and para forms and partial trapping of vibrational energy  

NASA Astrophysics Data System (ADS)

The laser-induced dispersed vibration-rotation fluorescence method has been developed further when compared with a previous publication [Saarinen [et al.], J. Chem. Phys. 110, 1424 (1999)]. More than one order of magnitude better signal-to-noise ratio has been achieved in the wave-number region 2900-3500 cm-1 by taking advantage of directionality of the fluorescence signal. The improvement has been applied to overtone spectroscopy of normal acetylene where for high CH stretching excitations separate spectra of ortho and para forms are obtained containing basically just single CH stretching vibrational quantum transitions from the pumped antisymmetric vibrational (nu]1+3[nu]3([Sigmau)+ and nu]2+3[nu]3([Sigmau)+ and close-lying symmetric vibrational local mode (4nu]3([Sigmag)+ and nu]1+[nu]2+2[nu]3 (?g)+ states. No nuclear spin conversion is observed in these spectra. Two new symmetric vibrational states ?1+2?2+4?40 (?g)+)(29% and (50%)) have been observed and the precision of the spectroscopic parameters of previously published symmetric states has been improved by an order of magnitude. Unexpected fluorescence originating from the antisymmetric CH stretching fundamental state nu3 and some associated states of acetylene have also been observed. These spectra are characterized by both ortho and para forms in normal abundance and by unusual intensity patterns due to strong reabsorption of the fluorescence by ground state acetylene molecules in the sample cell. A simple collisional step-down mechanism is proposed to account for the appearance of the nu3 fluorescence band system. The excess vibrational energy in the sample volume is partly trapped in the form of nu3 mode energy and it decays from the system by radiation.

Metsala, Markus; Yang, Shengfu; Vaittinen, Olavi; Halonen, Lauri

2002-11-01

278

Functional Assays for Ricin Detection  

NASA Astrophysics Data System (ADS)

In this review, we provide background information on ricin structure, present available functional assays for other toxins that are potential biothreat agents, and finish by describing the functional assay of ricin itself. Using appropriate sample preparation and optimized detection based on N-glycosidase activity, we demonstrate that specific detection of whole ricin at a level of around 0.1 ng/mL is possible and applicable to environmental samples.

Ezan, Eric; Duriez, Elodie; Fenaille, François; Becher, François

279

Rapid nonchromatographic assay for aminopropyltransferases  

SciTech Connect

Aminopropyltransferases are key enzymes in the biosynthesis of the polyamines spermidine and spermine. A procedure is described for assaying these enzymes be differential charcoal adsorption of /sup 14/C-labeled decarboxylated adenosylmethionine substrate from the labeled polyamine product. This assay is linear with time and enzyme concentration, and is suitable for use with a variety of amine acceptors. This procedure has the advantage, over those previously used, that it is extremely rapid yet very sensitive.

Anton, D.L.

1986-01-01

280

Lichenized unicellular cyanobacteria fix nitrogen in the light  

Microsoft Academic Search

Diurnal variation in N-2-fixation (acetylene reduction) rate was measured in Thyrea girardii (Durieu & Mont.) Bagl. & Carestia and Thyrea confusa Henssen, lichens containing a unicellular cyanobacterial photobiont. In field assays, mean acetylene-reduction rates in the light were 25.8 +\\/- 8.9 (n = 11) and 21.0 +\\/- 5.6 nmol C2H4 center dot g(-1).h(-1) (n = 13) for T. girardii and

P. D. Crittenden; X. Llimona; L. G. Sancho

2007-01-01

281

Application of nondestructive assay techniques in Kazakstan  

SciTech Connect

As Kazakstan has transitioned from being part of the Soviet Union to a nonweapons state (Treaty of Nonproliferation of Nuclear Weapons [NPT] signatory) under International Atomic Energy Agency (IAEA) inspections, significant changes have been required. Some of these changes have occurred in nuclear material protection, control, and accounting at the four nuclear facility sites in the Republic of Kazakstan. Specifically, the Republic of Kazakstan has changed from relying primarily on a subset of physical protection methods to a graded safeguards approach using a balance of material control, material accounting, and physical protection. Once more intensive material control and accounting procedures and systems are in place, a necessary step is to supply the accounting systems with measured values of high quality. This need can be met with destructive and nondestructive methods. Material control systems can also use qualitative nondestructive assay information as input. This paper will discuss the nondestructive assay techniques and systems the US Department of Energy (DOE) is providing to Kazakstan under both DOE programs and the Cooperative Threat Reduction Act as part of the nuclear material control and accounting upgrades at four facilities in Kazakstan. 4 refs., 6 figs.

Sprinkle, J.K. Jr.; Butler, G.; Collins, M. [and others

1997-11-01

282

Site Map | Clinical Assay Development Program (CADP)  

Cancer.gov

Skip to Content Search this site Site Map Home About CADP Mission Background CADP Resources for Assay Development CADN — Clinical Assay Development Network CADC — Clinical Assay Development Center SRS — Specimen Retrieval System Access to CADP Resources Eligibility Instructions Submit

283

21 CFR 864.7525 - Heparin assay.  

Code of Federal Regulations, 2014 CFR

... 2014-04-01 2014-04-01 false Heparin assay. 864.7525 Section 864.7525...Hematology Kits and Packages § 864.7525 Heparin assay. (a) Identification. A heparin assay is a device used to determine the...

2014-04-01

284

21 CFR 864.7525 - Heparin assay.  

Code of Federal Regulations, 2010 CFR

... 2010-04-01 2010-04-01 false Heparin assay. 864.7525 Section 864.7525...Hematology Kits and Packages § 864.7525 Heparin assay. (a) Identification. A heparin assay is a device used to determine the...

2010-04-01

285

Bioluminescent toxicity assay of synfuel by-product waters  

SciTech Connect

Large amounts of complex by-product waters, potentially toxic to biological systems, are generated during in situ recovery of fuels from oil shale, coal, and tar sand deposits. Since these by-product waters may contain a broad spectrum of organic and inorganic pollutants, analysis of individual compounds may not always be practical. Separation of complex by-product water into environmentally interpretable hydrophilic (HP) and organophilic (OP) fractions can, however, provide a useful approach for initial toxicity evaluation. The Microtox assay was developed by Beckman Microbics Operations. For this assay, reduction of bacterial luminescence upon exposure to potential inhibitors was used as an index of toxicity. This paper presents results of the Microtox assay on eight whole waters and their HP and OP fractions, derived from oil shale, coal, and tar sand recovery processes.

Delistraty, D.

1984-05-01

286

A root hair assay to expedite cell death research.  

PubMed

Programmed cell death can be defined as an organized cellular destruction and can be activated throughout plant development, as a defense response against invading pathogens or during environmental stress. The root hair assay presented herein enables in vivo quantitative measurements of programmed cell death based on the morphological changes of dying root hairs. Application of this novel, simple technique eliminates the need for establishing cell suspension cultures, resulting in a significant reduction in time, cost, and labor input. Here, we present a detailed root hair assay protocol for the dicotyledonous model plant Arabidopsis thaliana, where results from germination to scoring of cell death can be obtained within 7 days. We also suggest and present a panel of cell death inducing treatments which can be used to study abiotic stress- and mycotoxin-induced programmed cell death in the root hair system in Arabidopsis. A root hair assay protocol for the monocotyledonous model species Brachypodium distachyon is also included. PMID:25408445

Kacprzyk, Joanna; McCabe, Paul F

2015-01-01

287

Reactions between chlorine atom and acetylene in solid para-hydrogen: Infrared spectrum of the 1-chloroethyl radical  

SciTech Connect

We applied infrared matrix isolation spectroscopy to investigate the reactions between Cl atom and acetylene (C{sub 2}H{sub 2}) in a para-hydrogen (p-H{sub 2}) matrix at 3.2 K; Cl was produced via photodissociation at 365 nm of matrix-isolated Cl{sub 2} in situ. The 1-chloroethyl radical ({center_dot}CHClCH{sub 3}) and chloroethene (C{sub 2}H{sub 3}Cl) are identified as the main products of the reaction Cl + C{sub 2}H{sub 2} in solid p-H{sub 2}. IR absorption lines at 738.2, 1027.6, 1283.4, 1377.1, 1426.6, 1442.6, and 2861.2 cm{sup -1} are assigned to the 1-chloroethyl radical. For the reaction of Cl + C{sub 2}D{sub 2}, lines due to the {center_dot}CDClCH{sub 2}D radical and trans-CHDCDCl are observed; the former likely has a syn-conformation. These assignments are based on comparison of observed vibrational wavenumbers and {sup 13}C- and D-isotopic shifts with those predicted with the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ methods. Our observation indicates that the primary addition product of Cl + C{sub 2}H{sub 2}, 2-chlorovinyl ({center_dot}CHCHCl) reacts readily with a neighboring p-H{sub 2} molecule to form {center_dot}CHClCH{sub 3} and C{sub 2}H{sub 3}Cl. Observation of {center_dot}CDClCH{sub 2}D and trans-CHDCDCl from Cl + C{sub 2}D{sub 2} further supports this conclusion. Although the reactivity of p-H{sub 2} appears to be a disadvantage for making highly reactive free radicals in solid p-H{sub 2}, the formation of 1-chloroethyl radical indicates that this secondary reaction might be advantageous in producing radicals that are difficult to prepare from simple photolysis or bimolecular reactions in situ.

Golec, Barbara [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lee, Yuan-Pern [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China)

2011-11-07

288

Reactions between chlorine atom and acetylene in solid para-hydrogen: Infrared spectrum of the 1-chloroethyl radical  

SciTech Connect

We applied infrared matrix isolation spectroscopy to investigate the reactions between Cl atom and acetylene (C{sub 2}H{sub 2}) in a para-hydrogen (p-H{sub 2}) matrix at 3.2 K; Cl was produced via photodissociation at 365 nm of matrix-isolated Cl{sub 2} in situ. The 1-chloroethyl radical ({center_dot}CHClCH{sub 3}) and chloroethene (C{sub 2}H{sub 3}Cl) are identified as the main products of the reaction Cl + C{sub 2}H{sub 2} in solid p-H{sub 2}. IR absorption lines at 738.2, 1027.6, 1283.4, 1377.1, 1426.6, 1442.6, and 2861.2 cm{sup -1} are assigned to the 1-chloroethyl radical. For the reaction of Cl + C{sub 2}D{sub 2}, lines due to the {center_dot}CDClCH{sub 2}D radical and trans-CHDCDCl are observed; the former likely has a syn-conformation. These assignments are based on comparison of observed vibrational wavenumbers and {sup 13}C- and D-isotopic shifts with those predicted with the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ methods. Our observation indicates that the primary addition product of Cl + C{sub 2}H{sub 2}, 2-chlorovinyl ({center_dot}CHCHCl) reacts readily with a neighboring p-H{sub 2} molecule to form {center_dot}CHClCH{sub 3} and C{sub 2}H{sub 3}Cl. Observation of {center_dot}CDClCH{sub 2}D and trans-CHDCDCl from Cl + C{sub 2}D{sub 2} further supports this conclusion. Although the reactivity of p-H{sub 2} appears to be a disadvantage for making highly reactive free radicals in solid p-H{sub 2}, the formation of 1-chloroethyl radical indicates that this secondary reaction might be advantageous in producing radicals that are difficult to prepare from simple photolysis or bimolecular reactions in situ.

Golec, Barbara [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Lee, Yuan-Pern [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China)

2011-10-28

289

Novel CX?? halogen bonds in complexes of acetylene and its derivatives of Na and MPH3 (M=Cu, Ag, Au) with XCCF (X=Cl, Br, I).  

PubMed

Ab initio calculations have been carried out for a variety of model systems with a T-shaped CX?? motif. The CX?? interaction of acetylene with the halogen donor molecule XCCF (X=Cl, Br, I) is invariably found to be weak with the interaction energy less than 11kJ/mol in magnitude. Substitution of the two protons in acetylene with more electron-donating sodium atoms increases the ? electron density in the CC bond and leads to a substantial enhancement in its interaction with the halogen donor. The calculated interaction energies increase to as much as 73kJ/mol in the case of C2Na2-ICCF. The interaction of XCCF with a model coinage metal ethynide, H3PMCCMPH3 (M=Cu, Ag, Au), is intermediate between these two extremes, and the interaction energy is related to the nature of coinage metals. The CX?? halogen bonds have been analyzed with natural bond orbital, atoms in molecules, and energy decomposition. PMID:24632150

Zhuo, Hongying; Liu, Mingjuan; Li, Qingzhong; Li, Wenzuo; Cheng, Jianbo

2014-06-01

290

A theoretical study on the reaction pathways and the mechanism of 1,3- dipolar cycloaddition of vinyl acetylene and methyl azide.  

PubMed

1,3-dipolar cycloaddition procedure is one of the most widely practiced methods in order to synthesize heterocyclic compounds. Although, it seems very simple, but, there are numerous precursors of heterocyclic molecules who have more than one positions to react with a 1,3-dipole species. As a result, while using a precursor with more than one position for reaction, it is probable to synthesize several products with different structures. This paper studies all possible interactions of vinyl acetylene, which has two positions for reaction, with methyl azide. This reaction could lead to the emergence of any 1,3-dipolar cycloaddition products. Our ultimate goal is to help researchers to find out how precursors containing both carbon-carbon double, and the triple bonds interact with 1,3- dipolar species. The present study used the DFT calculations at B3LYP/6-311++G(3df,pd) level to check all probable interactions between vinyl acetylene and methyl azide, and determined Potential Energy Surface, and optimized all species. PMID:24852164

Siadati, Seyyed Amir; Mahboobifar, Ali; Nasiri, Ramin

2014-01-01

291

Aldehyde Reduction by Cytochrome P450  

PubMed Central

This protocol describes the procedure for measuring the relative rates of metabolism of the ?,?-unsaturated aldehydes, 9-anthracene aldehyde (9-AA) and 4-hydroxy-trans-2-nonenal (4-HNE); specifically the aldehyde reduction reactions of cytochrome P450s (CYPs). These assays can be performed using either liver microsomal or other tissue fractions, spherosome preparations of recombinant CYPs, or recombinant CYPs from other sources. The method used here to study the reduction of a model ?,?-unsaturated aldehyde, 9-AA, by CYPs was adapted from the assay used to investigate 9-anthracene oxidation as reported by Marini et al. (Marini et al., 2003). For experiments measuring reduction of the endogenous aldehyde, 4-HNE, the substrate was incubated with CYP in the presence of oxygen and NADPH and the metabolites were separated by High Pressure Liquid Chromatograpy (HPLC), using an adaptation of the method of Srivastava et al. (Srivastava et al., 2010). For study of 9-AA and 4-HNE reduction, the first step involves incubation of the substrate with the CYP in appropriate media, followed by quantification of metabolites through either spectrofluorimetry or analysis by HPLC coupled with a radiometric assay, respectively. Metabolite identification can be achieved by HPLC GC-mass spectrometric analysis. Inhibitors of cytochrome P450 function can be utilized to show the role of the hemoprotein or other enzymes in these reduction reactions. The reduction reactions for CYP’s were not inhibited by either anaerobiosis or inclusion of CO in the gaseous phase of the reaction mixture. These character of these reactions are similar to those reported for some cytochrome P450-catalyzed azo reduction reactions. PMID:21553396

Amunom, Immaculate; Srivastava, Sanjay; Prough, Russell A.

2011-01-01

292

Automated high-throughput Vibrio fischeri assay for (eco)toxicity screening: application to ionic liquids.  

PubMed

An automated high-throughput Vibrio fischeri assay was developed and further applied to the evaluation of ionic liquids (ILs) (eco)toxicity. The assay was based on the reduction of bacterial bioluminescence in the presence of test compounds and the results were presented as EC(50). The assays were performed with eight commercially available ILs with distinct cationic head groups, alkyl side chains and anions. EC(50) values between 6.5 and 691.9 mmol L(-1) were obtained for the tested ILs, being hmim [Cl] the most toxic and bmim [Cl] the less toxic ones, confirming the influence of the different structural elements. Moreover, all the tested ILs exhibited a (eco)toxicity lower than Cu(II), used as a positive control during the optimization and analysis steps. The automated assay assured the precise control of the contact time between V. fischeri and test compound by means of a simple protocol that guaranteed adequate aspiration and handling of the solutions as well as the precise implementation of a computer controlled stop period. Furthermore, a significant reduction of the assay costs was achieved through automation mainly by a drastic reduction of the volume of bacterial suspension and test compound. The methodology was validated by comparison with a microplate assay; it was stated that the results, obtained after a 3min contact time, changed proportionally relatively to Cu(II) in both assays. This confirmed the applicability of the methodology as an (eco)toxicity screening assay, with reduction of time and increase of robustness and repeatability (n=10; rsd<1.1%). It is expected that due to its simplicity and reduced cost the developed assay can be integrated in the early stage of development of new compounds as a rapid screening test. PMID:22417674

Pinto, Paula C A G; Costa, Susana P F; Lima, José L F C; Saraiva, M Lúcia M F S

2012-06-01

293

Three dimensional colorimetric assay assemblies  

SciTech Connect

A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

Charych, D.; Reichart, A.

2000-06-27

294

Three dimensional colorimetric assay assemblies  

DOEpatents

A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flu virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

Charych, Deborah (Albany, CA); Reichart, Anke (Albany, CA)

2000-01-01

295

Immunoradiometric assay of plasma lactoferrin.  

PubMed

The concentration of lactoferrin, a non-heme iron binding glycoprotein, was determined in more than 1500 EDTA plasma samples by a 2-site solid phase immunoradiometric assay to assess the significance of lactoferrin in plasma and to investigate applications for this assay. The use of commercially available antibody and antigen and a relatively short assay time make this assay more suitable for use in routine clinical laboratories than previous methods. A normal range of 250-750 micrograms/l was established. There was a correlation between plasma lactoferrin concentration and the circulating blood neutrophil count in most patients except those with splenomegaly, post-splenectomy and undergoing intensive chemotherapy. Patients with gross splenomegaly usually had an increased and post-splenectomy patients a decreased lactoferrin/neutrophil ratio indicating a respective increase and decrease in the marginated pool. In patients with acute leukemia after chemotherapy or transplantation plasma lactoferrin levels increased 1 to 5 d before blood neutrophil counts rose. As plasma lactoferrin seems to be derived from neutrophils, its concentration is probably related to the size of the total blood granulocyte pool. Calculation of the lactoferrin/neutrophil ratio demonstrated variations in the size of the bone marrow reserve and the marginated neutrophil pool. PMID:6856340

Brown, R D; Rickard, K A; Kronenberg, H

1983-01-01

296

Bacterial mutagenicity assays: test methods.  

PubMed

The most widely used assays for detecting chemically induced gene mutations are those employing bacteria. The plate incorporation assay using various Salmonella typhimurium LT2 and E. coli WP2 strains is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances capable of causing DNA damage leading to gene mutations. The test is used worldwide as an initial screen to determine the mutagenic potential of new chemicals and drugs.The test uses several strains of S. typhimurium which carry different mutations in various genes of the histidine operon, and E. coli which carry the same AT base pair at the critical mutation site within the trpE gene. These mutations act as hot spots for mutagens that cause DNA damage via different mechanisms. When these auxotrophic bacterial strains are grown on a minimal media agar plates containing a trace of the required amino-acid (histidine or tryptophan), only those bacteria that revert to amino-acid independence (His(+) or Tryp(+)) will grow to form visible colonies. The number of spontaneously induced revertant colonies per plate is relatively constant. However, when a mutagen is added to the plate, the number of revertant colonies per plate is increased, usually in a dose-related manner.This chapter provides detailed procedures for performing the test in the presence and absence of a metabolic activation system (S9-mix), including advice on specific assay variations and any technical problems. PMID:22147566

Gatehouse, David

2012-01-01

297

Pregnancy diagnosis by biochemical assay.  

PubMed

If pregnancy diagnosis by biochemical assay is to become practical, new marker characterization will be required. Pregnancy marker development is reviewed in dogs and other species, as are molecular biology techniques that have the potential to reveal previously inaccessible targets in the dog. PMID:1421818

Kuniyuki, A H; Hughes, M J

1992-09-01

298

Towards Magnetic Suspension Assay Technology  

Microsoft Academic Search

In this study micromagnetic simulations are used to evaluate two novel approaches of magnetically tagging biomolecules in high-throughput biological assays. Comparisons are made between a simple magnetic moment-based tagging system, where the total magnetic moment of each microscopic tag encodes the identity of an attached biomolecule, and a multibit tagging system, where each tag is comprised of multiple magnetic binary

T. J. Hayward; J. Llandro; K. P. Kopper; T. Trypiniotis; T. Mitrelias; J. A. C. Bland; C. H. W. Barnes

2008-01-01

299

Polymerase Chain Reaction Assay and  

E-print Network

Polymerase Chain Reaction Assay and Bacterial Meningitis Surveillance in Remote Areas, Niger Fati reference laboratory for meningitis in Niger used polymerase chain reaction (PCR) to enhance) and the national reference center for menin- gitis in Niger. The polymerase chain reaction (PCR) method

Paris-Sud XI, Université de

300

Asymmetric reductive amination.  

PubMed

Asymmetric reductive amination (ARA) affords synthetically valuable chiral amines straightforwardly. This chapter reviews the recent advances made in the area, focusing on ARA by hydrogenation, transfer hydrogenation, organocatalytic reduction, and biocatalytic reduction. PMID:24158548

Wang, Chao; Xiao, Jianliang

2014-01-01

301

Full dimensional Franck-Condon factors for the acetylene tilde{{A}} 1Au—{tilde{X}} {^1? _g^+} transition. I. Method for calculating polyatomic linear—bent vibrational intensity factors and evaluation of calculated intensities for the gerade vibrational modes in acetylene  

NASA Astrophysics Data System (ADS)

Franck-Condon vibrational overlap integrals for the tilde{A} {^1A_u}—{tilde{X}} {^1? _g^+} transition in acetylene have been calculated in full dimension in the harmonic normal mode basis. The calculation uses the method of generating functions first developed for polyatomic Franck-Condon factors by Sharp and Rosenstock [J. Chem. Phys. 41(11), 3453-3463 (1964)], and previously applied to acetylene by Watson [J. Mol. Spectrosc. 207(2), 276-284 (2001)] in a reduced-dimension calculation. Because the transition involves a large change in the equilibrium geometry of the electronic states, two different types of corrections to the coordinate transformation are considered to first order: corrections for axis-switching between the Cartesian molecular frames and corrections for the curvilinear nature of the normal modes at large amplitude. The angular factor in the wavefunction for the out-of-plane component of the trans bending mode, ? _4^' ' }, is treated as a rotation, which results in an Eckart constraint on the polar coordinates of the bending modes. To simplify the calculation, the other degenerate bending mode, ? _5^' ' }, is integrated in the Cartesian basis and later transformed to the constrained polar coordinate basis, restoring the conventional v and l quantum numbers. An updated tilde{A}-state harmonic force field obtained recently in the R. W. Field research group is evaluated. The results for transitions involving the gerade vibrational modes are in qualitative agreement with experiment. Calculated results for transitions involving ungerade modes are presented in Paper II of this series [G. B. Park, J. H. Baraban, and R. W. Field, "Full dimensional Franck-Condon factors for the acetylene tilde{A} {^1A_u}—{tilde{X}} {^1? _g^+} transition. II. Vibrational overlap factors for levels involving excitation in ungerade modes," J. Chem. Phys. 141, 134305 (2014)].

Park, G. Barratt

2014-10-01

302

Comparison of Cryptosporidium parvum Viability and Infectivity Assays following Ozone Treatment of Oocysts  

PubMed Central

Several in vitro surrogates have been developed as convenient, user-friendly alternatives to mouse infectivity assays for determining the viability of Cryptosporidium parvum oocysts. Such viability assays have been used increasingly to determine oocyst inactivation following treatment with chemical, physical, or environmental stresses. Defining the relationship between in vitro viability assays and oocyst infectivity in susceptible hosts is critical for determining the significance of existing oocyst inactivation data for these in vitro assays and their suitability in future studies. In this study, four viability assays were compared with mouse infectivity assays, using neonatal CD-1 mice. Studies were conducted in the United States and United Kingdom using fresh (<1 month) or environmentally aged (3 months at 4°C) oocysts, which were partially inactivated by ozonation before viability and/or infectivity analyses. High levels of variability were noted within and between the viability and infectivity assays in the U.S. and United Kingdom studies despite rigorous control over oocyst conditions and disinfection experiments. Based on the viability analysis of oocyst subsamples from each ozonation experiment, SYTO-59 assays demonstrated minimal change in oocyst viability, whereas 4?,6?-diamidino-2-phenylindole–propidium iodide assays, in vitro excystation, and SYTO-9 assays showed a marginal reduction in oocyst viability. In contrast, the neonatal mouse infectivity assay demonstrated significantly higher levels of oocyst inactivation in the U.S. and United Kingdom experiments. These comparisons illustrate that four in vitro viability assays cannot be used to reliably predict oocyst inactivation following treatment with low levels of ozone. Neonatal mouse infectivity assays should continue to be regarded as a “gold standard” until suitable alternative viability surrogates are identified for disinfection studies. PMID:10877794

Bukhari, Z.; Marshall, M. M.; Korich, D. G.; Fricker, C. R.; Smith, H. V.; Rosen, J.; Clancy, J. L.

2000-01-01

303

Fe(3+)-Fe(2+) transformation method: an important antioxidant assay.  

PubMed

If we look at the multitude of varied and interesting reaction that constitute biochemistry and bioorganic chemistry, it is possible to classify a great many as either oxidation or reduction reactions. The reducing agent transfers electrons to another substance and is thus it oxidized. And, because it gives electrons, it is also called an electron donor. Electron donors can also form charge transfer complexes with electron acceptors. Reductants in biochemistry are very diverse. For example ferric ions (Fe(3+)) are good reducing agents. Also, different bioanalytical reduction methods are available such as Fe(3+)-ferrous ions (Fe(2+)) reduction method, ferric reducing antioxidant power reducing assay. In this section, Fe(3+)-Fe(2+) transformation will be discussed. Recently there has been growing interest in research into the role of plant-derived antioxidants in food and human health. The beneficial influence of many foodstuffs and beverages including fruits, vegetables, tea, coffee, and cacao on human health has been recently recognized to originate from their antioxidant activity. For this purpose, the most commonly method used in vitro determination of reducing capacity of pure food constituents or plant extracts is Fe(3+) reducing ability. This commonly used reducing power method is reviewed and presented in this study. Also, the general chemistry underlying this assay was clarified. Hence, this overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. In addition, the most important advantages of this method were detected and highlighted. The chemical principles of these methods are outlined and critically discussed. The chemical principles of methods of Fe(3+)-Fe(2+) transformation assay are outlined and critically discussed. PMID:25323511

Gülçin, ?lhami

2015-01-01

304

Nerve-growth-factor-dependent neurite outgrowth assay; a research model for chemotherapy-induced neuropathy  

Microsoft Academic Search

The rat clonal pheochromocytoma cell line PC12 can be induced to display neurite outgrowth upon induction with nerve growth factor (NGF). This NGF-dependent neurite outgrowth assay looks a promising model for research on toxic neuropathies. Using this assay we demonstrated that cisplatin caused a dose-dependent reduction of NGF-dependent neurite formation. Increasing doses of NGF, however, proved to exert protective activity

A. A. Geldof

1995-01-01

305

Danish North Sea crude assayed  

SciTech Connect

Danish North Sea blend was assayed earlier this year. The light, sweet crude comprises crude oil from 10 fields. The crude is piped from offshore production facilities to the A/S Dansk Shell refinery at Fredericia, Denmark. Fig. 1 shows the boiling point curve for the crude, and Fig. 2 illustrates the metals content (vanadium, nickel, and iron), as a function of distillation temperature. The table lists properties of the crude and its fractions.

Rhodes, A.K.

1994-09-12

306

Acetylene weak bands at 2.5 $?$m from intracavity Cr2+:ZnSe laser absorption observed with time-resolved Fourier transform spectroscopy  

E-print Network

The spectral dynamics of a mid-infrared multimode Cr^2+:ZnSe laser located in a vacuum sealed chamber containing acetylene at low pressure is analyzed by a stepping-mode high-resolution time-resolved Fourier transform interferometer. Doppler-limited absorption spectra of C_2H_2 in natural isotopic abundance are recorded around 4000 cm^-1 with kilometric absorption path lengths and sensitivities better than 3 10^-8 cm-1. Two cold bands are newly identified and assigned to the n_1+n_4^1 and n_3+n_5^1 transitions of ^12C^13CH_2. The n_1+n_5^1 band of ^12C_2HD and fourteen ^12C_2H_2 bands are observed, among which for the first time n_2+2n_4^2+n_5^-1.

Véronique Girard; Robert Farrenq; Evgeni Sorokin; Irina T. Sorokina; Guy Guelachvili; Nathalie Picqué

2006-12-01

307

Synthesis, characterization and antimicrobial evaluation of some new schiff, mannich and acetylenic Mannich bases incorporating a 1,2,4-triazole nucleus.  

PubMed

A series of Schiff and Mannich bases derived from 4-amino-5-(3-fluoro-phenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione were synthesized. The alkylation of 4-phenyl-5-(3-fluorophenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione with propargyl bromide afforded the corresponding thiopropargylated derivative which upon treatment with the appropriate secondary amines in the presence of CuCl2 furnished the desired acetylenic Mannich bases. The synthesized compounds were characterized on the basis of their spectral (IR, 1H- and 13C-NMR) data and evaluated for their biological activities. Some of the compounds were found to exhibit significant antimicrobial activity. PMID:25412038

Aouad, Mohamed R

2014-01-01

308

Identification of nine acetylenic fatty acids, 9-hydroxystearic acid and 9,10-epoxystearic acid in the seed oil of Jodina rhombifolia hook et arn. (Santalaceae)  

Microsoft Academic Search

In addition to some usual fatty acids, the seed oil ofJodina rhombifolia (Santalaceae) contains nine acetylenic fatty acids [9-octadecynoic acid (stearolic acid) (1.1%),trans-10-heptadecen-8-ynoic acid (pyrulic acid) (20.1%), 7-hydroxy-trans-10-heptadecen-8-ynoic acid (2.3%),trans-10,16-heptadecadien-8-ynoic acid (0.7%), 7-hydroxy-trans-10,16-heptadecadien-8-ynoic acid (0.1%),trans-11-octadecen-9-ynoic acid (ximenynic acid) (20.3%), 8-hydroxy-trans-11-octadecen-9-ynoic acid (12.2%),trans-11,17-octadecadien-9-ynoic acid (1.5%), 8-hydroxy-trans-11,17-octadecadien-9-ynoic acid (1.3%), 9-hydroxystearic acid (<0.1%) and 9,10-epoxystearic acid (0.7%)]. The fatty acids\\u000a have been analyzed

V. Spitzer; S. A. de L. Bordignon; E. P. Schenkel; F. Marx

1994-01-01

309

Optical fiber hybridization assay fluorosensor  

NASA Astrophysics Data System (ADS)

The present work describes an all-fiber hybridization assay sensor that relies on the evanescent field excitation of fluorescence from surface-bound fluorophores. The evanescent field is made accessible through the use of a long adiabatically tapered single-mode fiber probe. A semiconductor laser operating at 785 nm wavelength is used in a pulsed mode to excite fluorescence in the tapered region of a fiber probe using the near-infrared fluorophore IRD 41. We have carried out real-time hybridization tests for IRD 41-labeled oligonucleotide at various probe concentrations binding to complementary oligonucleotide cross-linked to the tapered fiber surface. Short oligonucleotides (20-mer) bound to the fiber surface have been used to detect near-infrared dye labeled complementary sequences at sub-nanomolar levels. Sandwich assays with total RNA were conducted to examine the capability of the biosensor for detecting bacterial cells using rRNA as the target. The results indicate that this fluorosensor is capable of detecting H. pylori in a sandwich assay at picomolar concentrations.

Pilevar, Saeed; Davis, Christopher C.; Hodzic, Vildana; Portugal, Frank

1999-04-01

310

Reductive dechlorination of tetrachloroethylene and trichloroethylene catalyzed by vitamin B{sub 12} in homogeneous and heterogeneous systems  

SciTech Connect

The reduction of tetrachloroethylene (PCE) and trichloroethylene (TCE) catalyzed by vitamin B{sub 12} was examined in homogeneous and heterogeneous (B{sub 12} bound to agarose) batch systems using titanium(III) citrate as the bulk reductant. The solution and surface-mediated reaction rates at similar B{sub 12} loadings were comparable, indicating that binding vitamin B{sub 12} to a surface did not lower catalytic activity. No loss in PCE reducing activity was observed with repeated usage of surface-bound vitamin B{sub 12}. Carbon mass recoveries were 81-84% for PCE reduction and 89% for TCE reduction, relative to controls. In addition to sequential hydrogenolysis, a second competing reaction mechanism for the reduction of PCE and TCE by B{sub 12}, reductive {beta}-elimination, is proposed to account for the observation of acetylene as a significant reaction intermediate. Reductive {beta}-elimination should be considered as a potential pathway in other reactive systems involving the reduction of vicinal polyhaloethenes. Surface-bound catalysts such as vitamin B{sub 12} may have utility in the engineered degradation of aqueous phase chlorinated ethenes. 19 refs., 6 figs., 1 tab.

Burris, D.R.; Smith, M.H. [Armstrong Lab., Tyndall Air Force Base, FL (United States)] [Armstrong Lab., Tyndall Air Force Base, FL (United States); Delcomyn, C.A. [Applied Research Associates, Inc., Tyndall Air Force Base, FL (United States)] [Applied Research Associates, Inc., Tyndall Air Force Base, FL (United States); Roberts, A.L. [Johns Hopkins Univ., Baltimore, MD (United States)] [Johns Hopkins Univ., Baltimore, MD (United States)

1996-10-01

311

Evaluation of The Alamarblue Assay for Adherent Cell Irradiation Experiments  

PubMed Central

The AlamarBlue assay is based on fluorometric detection of metabolic mitochondrial activity of cells. In this study, we determined the methodology for application of the assay to radiation response experiments in 96-well plates. AlamarBlue was added and its reduction measured 7 hours later. Selection of the initial number of plated cells was important so that the number of proliferating cells remains lower than the critical number that produced full AlamarBlue reduction (plateau phase) at the time points of measurements. Culture medium was replaced twice a week to avoid suppression of viability due to nutrient competition and metabolic waste accumulation. There was no need to replace culture medium before adding AlamarBlue. Cell proliferation continued after irradiation and the suppression effect on cell viability was most evident on day 8. At this time point, by comparing measurements from irradiated vs. non-irradiated cells, for various dose levels, a viability dose response curve was plotted. Immediately after the 8th day (nadir), cells started to re-grow at a rate inversely related to the radiation dose. By comparing measurements at the time point of nadir vs. a convenient subsequent time point, re-growth dose response abilities were plotted, simulating clonogenic assays. PMID:24910583

Zachari, Maria A.; Chondrou, Panagiota S.; Pouliliou, Stamatia E.; Mitrakas, Achilleas G.; Abatzoglou, Ioannis; Zois, Christos E.; Koukourakis, Michael I.

2014-01-01

312

Full dimensional Franck-Condon factors for the acetylene A? (1)Au-X? (1)?(g)(+) transition. II. Vibrational overlap factors for levels involving excitation in ungerade modes.  

PubMed

A full-dimensional Franck-Condon calculation has been applied to the A? (1)Au-X? 1?g+ transition in acetylene in the harmonic normal mode basis. Details of the calculation are discussed in Part I of this series. To our knowledge, this is the first full-dimensional Franck-Condon calculation on a tetra-atomic molecule undergoing a linear-to-bent geometry change. In the current work, the vibrational intensity factors for levels involving excitation in ungerade vibrational modes are evaluated. Because the Franck-Condon integral accumulates away from the linear geometry, we have been able to treat the out-of-plane component of trans bend (?4('')) in the linear X? state in the rotational part of the problem, restoring the ? Euler angle and the a-axis Eckart conditions. A consequence of the Eckart conditions is that the out-of-plane component of ?4('') does not participate in the vibrational overlap integral. This affects the structure of the coordinate transformation and the symmetry of the vibrational wavefunctions used in the overlap integral, and results in propensity rules involving the bending modes of the X? state that were not previously understood. We explain the origin of some of the unexpected propensities observed in IR-UV laser-induced fluorescence spectra, and we calculate emission intensities from bending levels of the A? state into bending levels of the X? state, using normal bending mode and local bending mode basis sets. Our calculations also reveal Franck-Condon propensities for the Cartesian components of the cis bend (?5('')), and we predict that the best A?-state vibrational levels for populating X?-state levels with large amplitude bending motion localized in a single C-H bond (the acetylene?vinylidene isomerization coordinate) involve a high degree of excitation in ?6(') (cis-bend). Mode ?4(') (torsion) populates levels with large amplitude counter-rotational motion of the two hydrogen atoms. PMID:25296804

Park, G Barratt; Baraban, Joshua H; Field, Robert W

2014-10-01

313

Comparison of rapid screening assays using organic chemicals  

SciTech Connect

In a continuation of a study presented last year using metals, the sensitivity of short term toxicity tests is examined using common organic chemicals. In toxicity testing, the focus has shifted from the traditional long-term studies utilizing the mortality of complex, multicellular eukaryotic organisms as the endpoint towards short-term studies in which transformation of biochemical pathways are monitored. The relative sensitivity of aquatic screening techniques are compared to the standardized 48-hr Daphnia magna and Ceriodaphnia dubia, 96-hr fathead minnow and 96-hr algal acute assays. The short-term test procedures investigated are: dehydrogenase enzyme activity assays utilizing triphenyltetrazolium chloride (TTC) and resazurin as the calorimetric indicators; TOXI-Chromotest, inhibition of {beta}-galactosidase; reduction in bioluminescence output utilizing the Microtox{reg_sign} test; nitrification inhibition assays with a commercial preparation of nitrifying bacteria (Nitroseed{trademark}) and municipal activated sludge; respiration inhibition assays with a commercial preparation of heterotrophic bacteria (Polytox{reg_sign}) and activated sludge; inhibition of root growth in terrestrial plants; and galactosidase inhibition through the use of a fluorometrically tagged substrate with the Daphnia magna IQ{trademark} test. Toxicity values generated by this laboratory on commonly used organic chemicals are compared.

Beach, S.A.; Robideau, R.R. [3M Environmental Lab., St. Paul, MN (United States)

1994-12-31

314

Algal and bacterial non-symbiotic nitrogen fixation in paddy soils  

Microsoft Academic Search

Summary  The nitrogen fixing activity of three Ivory Coast soils was tested in the laboratory by the acetylene reduction assay and\\u000a the Kjeldahl method. Nitrogen fixation due to algae was estimated to be of the order of 4 to 8 (acetylene method) and 7 ?g\\u000a N per g soil per day (Kjeldahl method). Nitrogen fixation due to bacterial activity in the

G. Rinaudo; J. Balandreau; Y. Dommergues

1971-01-01

315

Strength Reduction via SSAPRE  

Microsoft Academic Search

We present techniques that allow strength reduction to be performed concurrently with partial redundancy elimination in the SSAPRE framework. By sharing the characteristics inherent to SSAPRE, the resulting strength reduction algorithm exhibits many interesting attributes. We compare various aspects of the new strength reduction algorithm with previous strength reduction algorithms. We also outline and discuss our implementation of the closely

Robert Kennedy; Fred C. Chow; Peter Dahl; Shin-ming Liu; Raymond Lo; Mark Streich

1998-01-01

316

Opportunity for Clinical Assay Development Support  

Cancer.gov

The NCI’s Division of Cancer Treatment and Diagnosis and the Cancer Diagnosis Program announce a request for applications for the Clinical Assay Development Program (CADP) for investigators seeking clinical assay development and validation resources.

317

Background Assay and Rejection in DRIFT  

E-print Network

The DRIFT-IId dark matter detector is a m$^3$-scale low-pressure TPC with directional sensitivity to WIMP-induced nuclear recoils. Its primary backgrounds were due to alpha decays from contamination on the central cathode. Efforts to reduce these backgrounds led to replacing the 20 \\mu m wire central cathode with one constructed from 0.9 \\mu m aluminized mylar, which is almost totally transparent to alpha particles. Detailed modeling of the nature and origin of the remaining backgrounds led to an in-situ, ppt-sensitive assay of alpha decay backgrounds from the central cathode. This led to further improvements in the thin-film cathode resulting in over 2 orders of magnitude reduction in backgrounds compared to the wire cathode. Finally, the addition of O$_2$ to CS$_2$ gas was found to produce multiple species of electronegative charge carriers, providing a method to determine the absolute position of nuclear recoils and reject all known remaining backgrounds while retaining a high efficiency for nuclear recoil detection.

Jeff Brack; Ed Daw; Alexei Dorofeev; Anthony Ezeribe; Jean-Luc Gauvreau; Michael Gold; John Harton; Randy Lafler; Robert Lauer; Eric R. Lee; Dinesh Loomba; John Matthews; Eric H. Miller; Alissa Monte; Alex Murphy; Sean Paling; Nguyen Phan; Steve Sadler; Andrew Scarff; Daniel Snowden-Ifft; Neil Spooner; Sam Telfer; Daniel Walker; Matt Williams; Leonid Yuriev

2014-04-08

318

Denitrification and nitric oxide reduction in an aerobic toluene-treating biofilter  

SciTech Connect

The presence of significant denitrification activity in an aerobic toluene-treating biofilter was demonstrated under batch and flow-through conditions. N{sub 2}O concentrations of 9.2 ppm{sub v} were produced by denitrifying bacteria in the presence of 15% acetylene, in a flow-through system with a bulk gas phase O{sub 2} concentration of >17%. The carbon source for denitrification was not toluene but a byproduct or metabolite of toluene catabolism. Denitrification conditions were successfully used for the reduction of 60 ppm{sub v} nitric oxide to 15 ppm{sub v} at a flow rate of 3 L/min (EBRT of 3 min) in a fully aerated, 17%/v/v O{sub 2} (superficially aerobic) biofilter. Higher NO removal efficiency (97%) was obtained by increasing the toluene supply to the biofilter.

Plessis, C.A. du; Kinney, K.A.; Schroeder, E.D.; Chang, D.P.Y.; Scow, K.M. [Univ. of California, Davis, CA (United States)] [Univ. of California, Davis, CA (United States)

1998-05-20

319

Data transformation methods for multiplexed assays  

DOEpatents

Methods to improve the performance of an array assay are described. A correlation between fluorescence intensity-related parameters and negative control values of the assay is determined. The parameters are then adjusted as a function of the correlation. As a result, sensitivity of the assay is improved without changes in its specificity.

Tammero, Lance F. Bentley; Dzenitis, John M; Hindson, Benjamin J

2013-07-23

320

SNP genotyping using KASPar assays.  

PubMed

In a separate chapter we describe a simple method for single nucleotide polymorphism (SNP) discovery using genomic reduction. Here we describe a scalable and cost-effective SNP genotyping method based on KBioscience's competitive allele-specific PCR amplification of target sequences and endpoint fluorescence genotyping (KASPar™) using a FRET capable plate reader or Fluidigm's dynamic array high-throughput platform. PMID:25373762

Smith, Scott M; Maughan, Peter J

2015-01-01

321

Preclinical Radiobiology and Predictive Assays  

NASA Astrophysics Data System (ADS)

Physical measurements of absorbed particle radiation doses are currently inadequate to estimate biological outcome at the stopping ranges of particle beams from protons to heavier ions. Estimates of biological significance and clinical impact are essential additional elements to implement ion beam therapy (IBT). This chapter provides a brief review of the current status of preclinical molecular and cellular radiobiology and predictive assays with a focus on the current use of radiobiology to characterize radiation fields of ions, to implement treatment planning with scanned ion beams, and to predict successful clinical outcome.

Blakely, Eleanor A.; Chang, Polly Y.

322

Comparison of Established and Emerging Biodosimetry Assays  

PubMed Central

Rapid biodosimetry tools are required to assist with triage in the case of a large-scale radiation incident. Here, we aimed to determine the dose-assessment accuracy of the well-established dicentric chromosome assay (DCA) and cytokinesis-block micronucleus assay (CBMN) in comparison to the emerging ?-H2AX foci and gene expression assays for triage mode biodosimetry and radiation injury assessment. Coded blood samples exposed to 10 X-ray doses (240 kVp, 1 Gy/min) of up to 6.4 Gy were sent to participants for dose estimation. Report times were documented for each laboratory and assay. The mean absolute difference (MAD) of estimated doses relative to the true doses was calculated. We also merged doses into binary dose categories of clinical relevance and examined accuracy, sensitivity and specificity of the assays. Dose estimates were reported by the first laboratories within 0.3–0.4 days of receipt of samples for the ?-H2AX and gene expression assays compared to 2.4 and 4 days for the DCA and CBMN assays, respectively. Irrespective of the assay we found a 2.5–4-fold variation of interlaboratory accuracy per assay and lowest MAD values for the DCA assay (0.16 Gy) followed by CBMN (0.34 Gy), gene expression (0.34 Gy) and ?-H2AX (0.45 Gy) foci assay. Binary categories of dose estimates could be discriminated with equal efficiency for all assays, but at doses ?1.5 Gy a 10% decrease in efficiency was observed for the foci assay, which was still comparable to the CBMN assay. In conclusion, the DCA has been confirmed as the gold standard biodosimetry method, but in situations where speed and throughput are more important than ultimate accuracy, the emerging rapid molecular assays have the potential to become useful triage tools. PMID:23862692

Rothkamm, K.; Beinke, C.; Romm, H.; Badie, C.; Balagurunathan, Y.; Barnard, S.; Bernard, N.; Boulay-Greene, H.; Brengues, M.; De Amicis, A.; De Sanctis, S.; Greither, R.; Herodin, F.; Jones, A.; Kabacik, S.; Knie, T.; Kulka, U.; Lista, F.; Martigne, P.; Missel, A.; Moquet, J.; Oestreicher, U.; Peinnequin, A.; Poyot, T.; Roessler, U.; Scherthan, H.; Terbrueggen, B.; Thierens, H.; Valente, M.; Vral, A.; Zenhausern, F.; Meineke, V.; Braselmann, H.; Abend, M.

2014-01-01

323

Making transuranic assay measurements using modern controllers  

SciTech Connect

This paper describes methodology and computer-controlled instrumentation developed at the Los Alamos National Laboratory that accurately performs nondestructive assays of large containers bearing transuranic wastes and nonradioactive matrix materials. These assay systems can measure fissile isotopes with 1-mg sensitivity and spontaneous neutron-emitting isotopes at a 10-mg sensitivity. The assays are performed by neutron interrogation, detection, and counting in a custom assay chamber. An International Business Machines Personal Computer (IBM-PC) is used to control the CAMAC-based instrumentation system that acquires the assay data. 6 refs., 7 figs.

Kuckertz, T.H.; Caldwell, J.T.; Medvick, P.A.; Kunz, W.E.; Hastings, R.D.

1987-01-01

324

Rapid prototyping of lateral flow assays.  

PubMed

Principles and characteristics of lateral flow strip assays are reviewed. Recent technology developments permit the use of inexpensive electronic readers for interrogating lateral flow strip test results, thus avoiding the inevitable variation and subjectivity of visual inspection to assess the capture of reporter-labeled analyte on test lines of the strip. Protocols for developing lateral flow assays are described, including two specific case studies for assaying cotinine (a small-molecule metabolite of nicotine) in a competitive format, and assaying HIV antibodies in a sandwich-type assay format. PMID:19159100

Volkov, Alexander; Mauk, Michael; Corstjens, Paul; Niedbala, R Sam

2009-01-01

325

Assay Development for Histone Methyltransferases  

PubMed Central

Abstract Epigenetic modifications play a crucial role in human diseases. Unlike genetic mutations, however, they do not change the underlying DNA sequences. Epigenetic phenomena have gained increased attention in the field of cancer research, with many studies indicating that they are significantly involved in tumor establishment and progression. Histone methyltransferases (HMTs) are a large group of enzymes that specifically methylate protein lysine and arginine residues, especially in histones, using S-adenosyl-l-methionine (SAM) as the methyl donor. However, in general, HMTs have no widely accepted high-throughput screening (HTS) assay format, and reference inhibitors are not available for many of the enzymes. In this study, we describe the application of a miniaturized, radioisotope-based reaction system: the HotSpotSM platform for methyltransferases. Since this platform employs tritiated SAM as a cofactor, it can be applied to the assay of any HMT. The key advantage of this format is that any substrate can be used, including peptides, proteins, or even nucleosomes, without the need for labeling or any other modifications. Using this platform, we have determined substrate specificities, characterized enzyme kinetics, performed compound profiling for both lysine and arginine methyltransferases, and carried out HTS for a small-library LOPAC against DOT1L. After hit confirmation and profiling, we found that suramin inhibited DOT1L, NSD2, and PRMT4 with IC50 values at a low ?M range. PMID:23557020

Eason, Mia M.; Ferry, Joseph J.; Planck, Jamie L.; Walsh, Colin P.; Smith, Robert F.; Howitz, Konrad T.

2013-01-01

326

Rotor assembly and assay method  

DOEpatents

A rotor assembly for carrying out an assay includes a rotor body which is rotatable about an axis of rotation, and has a central chamber and first, second, third, fourth, fifth, and sixth chambers which are in communication with and radiate from the central chamber. The rotor assembly further includes a shuttle which is movable through the central chamber and insertable into any of the chambers, the shuttle including a reaction cup carrying an immobilized antigen or an antibody for transport among the chambers. A method for carrying out an assay using the rotor assembly includes moving the reaction cup among the six chambers by passing the cup through the central chamber between centrifugation steps in order to perform the steps of: separating plasma from blood cells, binding plasma antibody or antigen, washing, drying, binding enzyme conjugate, reacting with enzyme substrate and optically comparing the resulting reaction product with unreacted enzyme substrate solution. The movement of the reaction cup can be provided by attaching a magnet to the reaction cup and supplying a moving magnetic field to the rotor. 34 figures.

Burtis, C.A.; Johnson, W.F.; Walker, W.A.

1993-09-07

327

Assay of potentially contaminated propellant  

SciTech Connect

One of the decontamination and decommissioning projects within DOD is demilitarization of an aging stockpile of munitions. A large portion of the stockpile contains depleted uranium (DU) as an armor piercing core and so these munitions must be assayed for the presence of uranium in other components. The assay method must be fast and preferably easy to implement. Presence of DU is indicated by its alpha decay. The alpha particles in turn produce ions in the ambient air. If a significant fraction of these ions can escape the quantity of propellant, the ions can be detected instead of the alpha particles. As a test of the feasibility of detecting alpha emissions from DU somewhere within a cartridge of propellant, the transmission of ions through layers of real propellant was measured. The propellant is in the form of graphite-coated cylindrical pellets. A 105nun cartridge was modified for use as a pellet chamber. A check source served as an ion source. The ion detector consisted of a grid held at 300V coupled to an ammeter. Results confirm that this is a promising technique for testing the propellant for the presence of DU quickly yet with sensitivity.

Koster, J.E.; Williams, H.E. III [Los Alamos National Lab., NM (United States); Scott, W.S. [Savanna Army Depot Activity (United States)

1995-02-01

328

Rotor assembly and assay method  

DOEpatents

A rotor assembly for carrying out an assay includes a rotor body which is rotatable about an axis of rotation, and has a central chamber and first, second, third, fourth, fifth, and sixth chambers which are in communication with and radiate from the central chamber. The rotor assembly further includes a shuttle which is movable through the central chamber and insertable into any of the chambers, the shuttle including a reaction cup carrying an immobilized antigen or an antibody for transport among the chambers. A method for carrying out an assay using the rotor assembly includes moving the reaction cup among the six chambers by passing the cup through the central chamber between centrifugation steps in order to perform the steps of: separating plasma from blood cells, binding plasma antibody or antigen, washing, drying, binding enzyme conjugate, reacting with enzyme substrate and optically comparing the resulting reaction product with unreacted enzyme substrate solution. The movement of the reaction cup can be provided by attaching a magnet to the reaction cup and supplying a moving magnetic field to the rotor.

Burtis, Carl A. (Oak Ridge, TN); Johnson, Wayne F. (Loudon, TN); Walker, William A. (Knoxville, TN)

1993-01-01

329

SNO+ Scintillator Purification and Assay  

SciTech Connect

We describe the R and D on the scintillator purification and assay methods and technology for the SNO+ neutrino and double-beta decay experiment. The SNO+ experiment is a replacement of the SNO heavy water with liquid scintillator comprised of 2 g/L PPO in linear alkylbenzene (LAB). During filling the LAB will be transported underground by rail car and purified by multi-stage distillation and steam stripping at a flow rate of 19 LPM. While the detector is operational the scintillator can be recirculated at 150 LPM (full detector volume in 4 days) to provide repurification as necessary by either water extraction (for Ra, K, Bi) or by functional metal scavenger columns (for Pb, Ra, Bi, Ac, Th) followed by steam stripping to remove noble gases and oxygen (Rn, O{sub 2}, Kr, Ar). The metal scavenger columns also provide a method for scintillator assay for ex-situ measurement of the U and Th chain radioactivity. We have developed ''natural'' radioactive spikes of Pb and Ra in LAB and use these for purification testing. Lastly, we present the planned operating modes and purification strategies and the plant specifications and design.

Ford, R.; Vazquez-Jauregui, E. [SNOLAB, Creighton Mine, Lively, P3Y 1N2 (Canada); Chen, M. [Department of Physics, Queen's University, Kingston, K7L 3N6 (Canada); Chkvorets, O.; Hallman, D. [Department of Physics, Laurentian University, Sudbury, P3E 2C6 (Canada)

2011-04-27

330

Sulfo-N-hydroxysuccinimide interferes with bicinchoninic acid protein assay.  

PubMed

This study revealed a major interference from sulfo-N-hydroxysuccinimide (sulfo-NHS) in the bicinchoninic acid (BCA) protein assay. Sulfo-NHS, a common reagent used in bioconjugation and analytical biochemistry, exhibited absorbance signals and absorbance peaks at 562 nm, comparable to bovine serum albumin (BSA). However, the combined absorbance of sulfo-NHS and BSA was not strictly additive. The sulfo-NHS interference was suggested to be caused by the reduction of Cu(2+) in the BCA Kit's reagent B (4% cupric sulfate) in a manner similar to that of the protein. PMID:21704014

Vashist, Sandeep Kumar; Zhang, BinBin; Zheng, Dan; Al-Rubeaan, Khalid; Luong, John H T; Sheu, Fwu-Shan

2011-10-01

331

Evaluating 6 ricin field detection assays.  

PubMed

This study presents data showing the performance of 6 commercial detection assays against ricin around concentrations specified as detection limits by the producers. A 2-fold dilution series of 20?ng/ml ricin was prepared and used for testing the lateral-flow kits: BADD, Pro Strips™, ENVI, RAID DX, Ricin BioThreat Alert, and IMASS™ device. Three of the 6 tested field assays (IMASS™ device, ENVI assay, and the BioThreat Alert assay) were able to detect ricin, although differences in the measured detection limits compared to the official detection limits and false-negative results were observed. We were not able to get the BADD, Pro Strips™, and RAID assays to function in our laboratory. We conclude that when purchasing a field responder assay, there is large variation in the specificity of the assays, and a number of in-house tests must be performed to ensure functionality. PMID:24978020

Slotved, Hans-Christian; Sparding, Nadja; Tanassi, Julia Tanas; Steenhard, Nina R; Heegaard, Niels H H

2014-01-01

332

Collaborative study for validation of a serological potency assay for rabies vaccine (inactivated) for veterinary use.  

PubMed

European Pharmacopoeia (Ph. Eur.) monograph 0451 on Rabies vaccine (inactivated) for veterinary use describes an in vivo batch potency test that is based on the NIH test. This assay uses a large number of mice and results in a significant degree of suffering. In the interest of replacement, reduction and refinement of animal tests (3R) a serological potency assay for Rabies vaccine (inactivated) for animal use, developed and validated at the Paul-Ehrlich-Institut, has been assessed in a collaborative study organised by the EDQM (European Directorate for the Quality of Medicines & HealthCare). The goal was to demonstrate the wider transferability of the proposed assay and confirm its suitability. The study involved 13 laboratories and assessed 4 different vaccines from the EU market. Results of the study confirm that a limit test using a relatively small number of animals in a serological assay is possible, reproducible and reliable. The optimal number of animals per vaccine is product specific but may roughly be indicated to be between 8 and 10 for the products included in this study. Non-responders should be included in the analysis because they may reflect sub-potent vaccines. However, there may be a need to impose a maximum on the number of non-responders allowed for the reference vaccine as a monitor for assay validity. This assay provides a significant 3R improvement in terms of both the number of animals used and the amount of suffering entailed and provides a more reliable and reproducible assay format than the vaccination challenge assay. It also reduces the time required as compared to the vaccination challenge assay. It has been recommended to the Ph. Eur. group of experts 15V that this assay be included as an alternative to the batch potency assay in the Ph. Eur. monograph 0451. PMID:21144488

Krämer, B; Bruckner, L; Daas, A; Milne, C

2010-10-01

333

High performance addition-type thermoplastics (ATTs) - Evidence for the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated material and a bismaleimide  

NASA Technical Reports Server (NTRS)

Recently, the concept and demonstration of a new versatile synthetic reaction for making a large number of high-performance addition-type thermoplastics (ATTs) were reported. The synthesis shows promise for providing polymers having an attractive combination of easy processability, good toughness, respectable high temperature mechanical performance, and excellent thermo-oxidative stability. The new chemistry involves the reaction of an acetylene-terminated material with a bismaleimide or benzoquinone. In order to clarify the reaction mechanism, model compound studies were undertaken in solutions as well as in the solid state. The reaction products were purified by flash chromatography and characterized by conventional analytical techniques including NMR, FT-IR, UV-visible, mass spectroscopy, and high pressure liquid chromatography. The results are presented of the model compound studies which strongly support the formation of a Diels-Alder adduct in the reaction of an acetylene-terminated compound and a bismaleimide or benzoquinone.

Pater, R. H.; Soucek, M. D.; Chang, A. C.; Partos, R. D.

1991-01-01

334

Steroid Assays in Paediatric Endocrinology  

PubMed Central

Most steroid disorders of the adrenal cortex come to clinical attention in childhood and in order to investigate these problems, there are many challenges to the laboratory which need to be appreciated to a certain extent by clinicians. The analysis of sex steroids in biological fluids from neonates, over adrenarche and puberty present challenges of specificities and concentrations often in small sample sizes. Different reference ranges are also needed for interpretations. For around 40 years, quantitative assays for the steroids and their regulatory peptide hormones have been possible using immunoassay techniques. Problems are recognised and this review aims to summarise the benefits and failings of immunoassays and introduce where tandem mass spectrometry is anticipated to meet the clinical needs for steroid analysis in paediatric endocrine investigations. It is important to keep a dialogue between clinicians and the laboratory, especially when any laboratory result does not make sense in the clinical investigation. Conflict of interest:None declared. PMID:21274330

2010-01-01

335

Antioxidants and the Comet assay.  

PubMed

It is widely accepted that antioxidants, either endogenous or from the diet, play a key role in preserving health. They are able to quench radical species generated in situations of oxidative stress, either triggered by pathologies or xenobiotics, and they protect the integrity of DNA from genotoxicants. Nevertheless, there are still many compounds with unclear or unidentified prooxidant/antioxidant activities. This is of concern since there is an increase in the number of compounds synthesized or extracted from vegetables to which humans might be exposed. Despite the well-established protective effects of fruit and vegetables, the antioxidant(s) responsible have not all been clearly identified. There might also be alternative mechanisms contributing to the protective effects for which a comprehensive description is lacking. In the last two decades, the Comet assay has been extensively used for the investigation of the effects of antioxidants and many reports can be found in the literature. The Comet assay, a relatively fast, simple, and sensitive technique for the analysis of DNA damage in all cell types, has been applied for the screening of chemicals, biomonitoring and intervention studies. In the present review, several of the most well-known antioxidants are considered. These include: catalase, superoxide dismutase, glutathione peroxidase, selenium, iron chelators, melatonin, melanin, vitamins (A, B, C and E), carotenes, flavonoids, isoflavones, tea polyphenols, wine polyphenols and synthetic antioxidants. Investigations showing beneficial as well as non-beneficial properties of the antioxidants selected, either at the in vitro, ex vivo or in vivo level are discussed. PMID:18602333

Cemeli, Eduardo; Baumgartner, Adolf; Anderson, Diana

2009-01-01

336

Predictive Assay For Cancer Targets  

SciTech Connect

Early detection of cancer is a key element in successful treatment of the disease. Understanding the particular type of cancer involved, its origins and probable course, is also important. PhIP (2-amino-1-methyl-6 phenylimidazo [4,5-b]pyridine), a heterocyclic amine produced during the cooking of meat at elevated temperatures, has been shown to induce mammary cancer in female, Sprague-Dawley rats. Tumors induced by PhIP have been shown to contain discreet cytogenetic signature patterns of gains and losses using comparative genomic hybridization (CGH). To determine if a protein signature exists for these tumors, we are analyzing expression levels of the protein products of the above-mentioned tumors in combination with a new bulk protein subtractive assay. This assay produces a panel of antibodies against proteins that are either on or off in the tumor. Hybridization of the antibody panel onto a 2-D gel of tumor or control protein will allow for identification of a distinct protein signature in the tumor. Analysis of several gene databases has identified a number of rat homologs of human cancer genes located in these regions of gain and loss. These genes include the oncogenes c-MYK, ERBB2/NEU, THRA and tumor suppressor genes EGR1 and HDAC3. The listed genes have been shown to be estrogen-responsive, suggesting a possible link between delivery of bio-activated PhIP to the cell nucleus via estrogen receptors and gene-specific PhIP-induced DNA damage, leading to cell transformation. All three tumors showed similar silver staining patterns compared to each other, while they all were different than the control tissue. Subsequent screening of these genes against those from tumors know to be caused by other agents may produce a protein signature unique to PhIP, which can be used as a diagnostic to augment optical and radiation-based detection schemes.

Suess, A; Nguyen, C; Sorensen, K; Montgomery, J; Souza, B; Kulp, K; Dugan, L; Christian, A

2005-09-19

337

Optimization and validation of the TZM-bl assay for standardized assessments of neutralizing antibodies against HIV-1.  

PubMed

The TZM-bl assay measures antibody-mediated neutralization of HIV-1 as a function of reductions in HIV-1 Tat-regulated firefly luciferase (Luc) reporter gene expression after a single round of infection with Env-pseudotyped viruses. This assay has become the main endpoint neutralization assay used for the assessment of pre-clinical and clinical trial samples by a growing number of laboratories worldwide. Here we present the results of the formal optimization and validation of the TZM-bl assay, performed in compliance with Good Clinical Laboratory Practice (GCLP) guidelines. The assay was evaluated for specificity, accuracy, precision, limits of detection and quantitation, linearity, range and robustness. The validated manual TZM-bl assay was also adapted, optimized and qualified to an automated 384-well format. PMID:24291345

Sarzotti-Kelsoe, Marcella; Bailer, Robert T; Turk, Ellen; Lin, Chen-li; Bilska, Miroslawa; Greene, Kelli M; Gao, Hongmei; Todd, Christopher A; Ozaki, Daniel A; Seaman, Michael S; Mascola, John R; Montefiori, David C

2014-07-01

338

[pi] electron delocalization and compression in acyclic acetylenic precursors to multidimensional carbon networks. Comparison with experiment for the recently synthesized tris(trimethylsilyl)-substituted tetraethynylmethane. Structures, thermochemistry, infrared spectra, polarizabilities, and hyperpolarizabilities  

Microsoft Academic Search

Several acyclic acetylenic precursors to multidimensional carbon networks, including tetraethynylbutatriene (C[sub 12]H[sub 4]), tetraethynylmethane (C[sub 9]H[sub 4]) derivatives, and the yet unknown molecules tetraethynylallene (C[sub 11]H[sub 4]) and hexaethynyl[3]radialene (C[sub 18]H[sub 6]), have been studied using ab initio molecular quantum mechanics. Their equilibrium geometries, vibrational frequencies, thermochemical properties, and nonlinear optical responses have been predicted. To allow direct comparisons with

Buyong Ma; Horst M. Sulzbach; Yaoming Xie; Henry F. III Schaefer

1994-01-01

339

Interaction of Tertiary Phosphines with Acetylenic Compouxds. Alkyl Migration Accompanied by CP Bond Cleavage and Fragmentation During the Interaction of Trialkyphosphines with Phenylacetylene in the Presence of Proton Donors  

Microsoft Academic Search

We have recently describedphosphobetaines with negative charge on ?-carbon atom of vinyl group or on ?-carbon atom of l 1,3-butadienyl group prepared by interaction of trial-kylphosphines with acetylenic and vinylacetylenic compounds, respectively. In the course of developing these investigations an extra route of phosphobetaine formation has been found representing the deprotonation of corresponding phosphonium salts. It has been found that

M. H. Injikian; G. Ts. Gasparian; S. K. Barseghian; M. Zh. Hovakimian

1990-01-01

340

The Ferric Reducing Ability of Plasma (FRAP) as a Measure of “Antioxidant Power”: The FRAP Assay  

Microsoft Academic Search

A simple, automated test measuring the ferric reducing ability of plasma, the FRAP assay, is presented as a novel method for assessing “antioxidant power.” Ferric to ferrous ion reduction at low pH causes a colored ferrous-tripyridyltriazine complex to form. FRAP values are obtained by comparing the absorbance change at 593 nm in test reaction mixtures with those containing ferrous ions

Iris F. F. Benzie; J. J. Strain

1996-01-01

341

Validation of a Cell-Free Translation Assay for Detecting Shiga Toxin 2 in Bacterial Culture  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have validated a cell-free translation (CFT) assay for detecting Shiga toxin (Stx). The limit of detection (LOD) for pure Stx2 (PStx2) and partially pure Stx2 (PPStx2) in water reached 20 pg/µl and 3.5 pg/µL respectively without the artificial process of proteolytic activation and reduction of th...

342

Pollen tetrad-based visual assay for meiotic recombination in Arabidopsis  

E-print Network

), is a highly conserved feature of meiosis from fungi to mammals. Recombination helps ensure chromosome for meiosis, resulting in sterility. We have developed a visual assay capable of detecting Cos and GCs. cross-over meiosis tetrad gene conversion interference Meiosis, the reductive division of the genome

Copenhaver, Gregory P.

343

Fine-tuning control on CNT diameter distribution, length and density using thermal CVD growth at atmospheric pressure: an in-depth analysis on the role of flow rate and flow duration of acetylene (C2H2) gas  

NASA Astrophysics Data System (ADS)

An optimization control has been demonstrated to obtain carbon nanotubes having specific diameter distribution, length, homogeneity, and yield during its growth by thermal chemical vapor deposition technique under atmospheric pressure. Carbon nanotubes (CNTs) were grown on silicon wafer where a predeposition of iron catalyst of 2 nm thickness was made by sputtering. The growth was conducted under two variable parameters, i.e., flow rate and flow duration. Argon and hydrogen mixture was used for pretreatment of catalyst and as etching gas, and acetylene as a carbon precursor. In-depth analysis shows that increase in flow rate from 10 to 50 sccm resulted in increase in the concentration of amorphous carbon, CNTs diameter range and decrease in length, we found best result at 20 sccm flow rate of acetylene gas. On the other hand, as we varied flow duration from 6 to 14 min, with keeping flow rate of acetylene 20 sccm constant, dense homogeneous growth of horizontal CNTs network plus an increase in length and diameter range were observed. An optimization of flow rate and flow duration is presented here to obtain a selective diameter distribution and length as expected by this growth technique. Atomic force microscopy, field emission scanning electron microscopy and Raman spectroscopy were used to investigate the samples' morphologies in support of the observations made.

Tripathi, Nishant; Mishra, Prabhash; Harsh, Harsh; Islam, S. S.

2015-01-01

344

Infrared and microwave spectra of the acetylene-ammonia and carbonyl sulfide-ammonia complexes: a comparative study of a weak C-H···N hydrogen bond and an S···N bond.  

PubMed

We report a combined high resolution infrared and microwave spectroscopic investigation of the acetylene-ammonia and carbonyl sulfide-ammonia complexes using a pulsed slit-nozzle multipass absorption spectrometer based on a quantum cascade laser and a pulsed nozzle beam Fourier transform microwave spectrometer, respectively. The ro-vibrational transitions of the acetylene-ammonia complex have been measured at 6 ?m in the vicinity of the ?(4) band of ammonia for the first time. The previously reported pure rotational transitions have been extended to higher J and K values with (14)N nuclear quadrupole hyperfine components detected and analyzed. The spectral analysis reveals that acetylene binds to ammonia through a C-H···N weak hydrogen bond to form a C(3v) symmetric top, consistent with the previous microwave [Fraser et al., J. Chem. Phys., 1984, 80, 1423] and infrared spectroscopic study at 3 ?m [Hilpert et al., J. Chem. Phys., 1996, 105, 6183]. A parallel study has also been carried out for the carbonyl sulfide-ammonia complex whose pure rotational and ro-vibrational spectra at 6 ?m have been detected and analyzed for the first time. The spectral and the subsequent structural analyses, in conjunction with the corresponding ab initio calculation, indicate that the OCS-NH(3) complex assumes C(3v) symmetry with S pointing to N of NH(3), in contrast to the T-shaped geometries obtained for the isoelectronic N(2)O-NH(3) and CO(2)-NH(3) complexes. PMID:21776482

Liu, Xunchen; Xu, Yunjie

2011-08-21

345

Lack of activity of cadmium in in vitro estrogenicity assays.  

PubMed

Prompted by reports about strong estrogenic effects of cadmium, attempts were made to reproduce these observations using the yeast estrogen screen (YES) and the E-Screen assays. For the first time, possible activation of the Src/MAPK pathway was also investigated. In the YES, only a slight activation (10% of a maximal effect) of the estrogen receptor alpha (ERalpha) was observed at cadmium concentrations between 5 x 10(-7) M and 5 x 10(-6) M. In the E-Screen assay, carried out by two laboratories, the heavy metal was without observable cell proliferative effects when tested in the range between 6 x 10(-11) M and 1 x 10(-5) M. However, in both assays, cadmium led to a reduction of the effects of 17beta-estradiol (E2). Treatment of MCF-7 human breast cancer cells with 1 x 10(-7) M cadmium failed to induce phosphorylation of Src and the MAP kinases Erk1 and Erk2-effects shown to occur with E2 and epidermal growth factor (EGF). In summary, we were unable to confirm the strong estrogenicity of cadmium reported recently by a number of laboratories. This apparent absence of effects in our hands is not due to a lack of uptake of the metal or to effective protection against cadmium by high levels of glutathione or metallothionein, since toxicity and an antagonism of E2 responses were observed both in the YES and the E-Screen. PMID:16716372

Silva, Elisabete; Lopez-Espinosa, Maria José; Molina-Molina, José-Manuel; Fernández, Marieta; Olea, Nicolas; Kortenkamp, Andreas

2006-10-01

346

Visualizing hydrogen atoms migrating in acetylene dication by time-resolved three-body and four-body Coulomb explosion imaging.  

PubMed

The visualization of ultrafast isomerization of deuterated acetylene dication (C(2)D(2)(2+)) is demonstrated by time-resolved Coulomb explosion imaging with sub-10 fs intense laser pulses (9 fs, 0.13 PW cm(-2), 800 nm). The Coulomb explosion imaging monitoring the three-body explosion process, C(2)D(2)(3+)? D(+) + C(+) + CD(+), as a function of the delay between the pump and probe pulses revealed that the migration of a deuterium atom proceeds in a recurrent manner; One of the deuterium atoms first shifts from one carbon site to the other in a short timescale (?90 fs), and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation. Correlated motion of the two deuterium atoms associated with the hydrogen migration and structural deformation to non-planar geometry are identified by the time-resolved four-body Coulomb explosion imaging, C(2)D(2)(4+)? D(+) + C(+) + C(+) + D(+). PMID:21442121

Matsuda, Akitaka; Fushitani, Mizuho; Takahashi, Eiji J; Hishikawa, Akiyoshi

2011-05-21

347

Determination of halogens via molecules in the air acetylene flame using high-resolution continuum source absorption spectrometry, Part II: Chlorine  

NASA Astrophysics Data System (ADS)

As continuation of the work on fluorine, the second part of the studies of halogens in the air-acetylene flame attends to the determination of chlorine using high-resolution continuum source absorption spectrometry and molecular absorption. In case of chlorine, the diatomic InCl molecule proved to be a suitable species. For an excess of In in the flame, chlorine is converted to InCl which produces a distinctive band head at 267.24 nm that could be evaluated analytically. The influence of concentrated inorganic acids and metallic matrices on the absorption at this band head was tested. In all cases the signal proved to be unaffected, i.e., no spectral interferences were observed. However, serious chemical interferences were found in the presence of sulfuric and phosphoric acids, which could be partially eliminated by adding Ca in the form of nitrate. Moreover, nitric and hydrofluoric acids as well as Cu and Ga matrices also produced significant chemical interferences. Therefore, the method of standard additions should be used for calibration purposes. Concerning the limit of detection, a value of 3 mg L - 1 was achieved for a measurement time of 5 s in the presence of 10,000 mg L - 1 In. The calibration curve was linear up to a chlorine concentration of 1800 mg L - 1 . Three certified reference materials (BCR 151, HISS-1, and PACS-2) were analyzed to test the performance of the new method, yielding good precision and accuracy.

Huang, Mao Dong; Becker-Ross, Helmut; Florek, Stefan; Heitmann, Uwe; Okruss, Michael

2006-08-01

348

Improvements of anti-corrosion and mechanical properties of NiTi orthopedic materials by acetylene, nitrogen and oxygen plasma immersion ion implantation  

NASA Astrophysics Data System (ADS)

Nickel-titanium shape memory alloys (NiTi) are useful materials in orthopedics and orthodontics due to their unique super-elasticity and shape memory effects. However, the problem associated with the release of harmful Ni ions to human tissues and fluids has been raising safety concern. Hence, it is necessary to produce a surface barrier to impede the out-diffusion of Ni ions from the materials. We have conducted acetylene, nitrogen and oxygen plasma immersion ion implantation (PIII) into NiTi alloys in an attempt to improve the surface properties. All the implanted and annealed samples surfaces exhibit outstanding corrosion and Ni out-diffusion resistance. Besides, the implanted layers are mechanically stronger than the substrate underneath. XPS analyses disclose that the layer formed by C 2H 2 PIII is composed of mainly TiC x with increasing Ti to C concentration ratios towards the bulk. The nitrogen PIII layer is observed to be TiN, whereas the oxygen PIII layer is composed of oxides of Ti 4+, Ti 3+ and Ti 2+.

Poon, Ray W. Y.; Ho, Joan P. Y.; Liu, Xuanyong; Chung, C. Y.; Chu, Paul K.; Yeung, Kelvin W. K.; Lu, William W.; Cheung, Kenneth M. C.

2005-08-01

349

Experimental observation and analysis of the 3?(1)(?(g)) stretching vibrational state of acetylene using continuous-wave infrared stimulated emission.  

PubMed

We present a sensitive experimental method for molecular spectroscopy that can be used to determine ro-vibrational states using mid-infrared stimulated emission. Our infrared stimulated emission probing (IRSEP) experiment is based on using a narrow-line, continuous-wave Ti:sapphire laser beam (pump) to excite the molecules to an upper vibrational state and a continuous-wave, mid-infrared beam from an optical parametric oscillator (probe) to detect the stimulated emission by the excited molecules. Spectroscopic data are gathered by tuning the wavelengths of the beams. The molecules are probed before their velocity distribution is disturbed by collisions, which leads to a sub-Doppler resolution. The full width at half maximum of the emission peaks is below 10 MHz. The stimulated emission lines are measured with an accuracy of at least 0.005 cm(-1). We use the IRSEP experiment to observe and analyze the symmetric ro-vibrational state [21+] (3?1(?g)) of acetylene (C2H2). This state is not accessible via one photon transitions from the ground vibrational state. We use the least-squares method to determine that the band center is at 9991.9725 (12) cm(-1) and the rotational parameters are B = 1.156145 (22) and D = 1.608 (87) × 10(-6) cm(-1), where the uncertainties in parentheses are one-standard errors in the least significant digit. PMID:23927255

Siltanen, Mikael; Metsälä, Markus; Vainio, Markku; Halonen, Lauri

2013-08-01

350

Particle-induced artifacts in the MTT and LDH viability assays  

PubMed Central

In vitro testing is a common first step in assessing combustion generated and engineered nanoparticle related health hazards. Commercially available viability assays are frequently used to compare the toxicity of different particle types and to generate dose response data. Nanoparticles, well known for having large surface areas and chemically active surfaces, may interfere with viability assays, producing a false assessment of toxicity and making it difficult to compare toxicity data. The objective of this study is to measure the extent of particle interference in two common viability assays, the MTT reduction and the lactate dehydrogenase (LDH) release assays. Diesel particles, activated carbon, flame soot, oxidized flame soot, and titanium dioxide particles are assessed for interactions with the MTT and LDH assay under cell-free conditions. Diesel particles, at concentrations as low as 0.05 ?g/ml, reduce MTT. Other particle types reduce MTT only at a concentration of 50 ?g/ml and higher. The activated carbon, soot, and oxidized soot particles bind LDH to varying extents, reducing the concentration measured in the LDH assay. The interfering effects of the particles explain in part the different toxicities measured in human bronchial epithelial cells (16HBE14o). We conclude that valid particle toxicity assessments can only be assured after first performing controls to verify that the particles under investigation do not interfere with a specific assay at the expected concentrations. PMID:22799765

Holder, Amara L.; Goth-Goldstein, Regine; Lucas, Donald; Koshland, Catherine P.

2012-01-01

351

Feasibility studies for assaying alpha-fetoprotein using antibody-activated magnetic nanoparticles  

PubMed Central

Some previous reports have already shown the characterizations of immunomagnetic reduction (IMR). The assay technology involves the utilities of biofunctionalized magnetic nanoparticles to label target biomolecules. However, the detection threshold and interference tests for IMR have not been investigated in detail. In this study, alpha-fetoprotein (AFP) was used as a target biomolecule. The signals for AFP solutions of various concentrations, or with interfering materials, were detected via IMR. These samples were also used for characterizing the detection threshold and interference with enzyme-linked immunosorbent assay (ELISA). The results of assaying AFP level with IMR and ELISA were compared. The detection threshold for assaying AFP with IMR was found to be 3 ng/mL, which is 15 times lower than that of ELISA, and definitely suppresses false negative. For the interfering materials noted commonly in serum such as hemoglobin, bilirubin, triglyceride, and vascular endothelial growth factor, there was no detectable interfering effect when assaying AFP with IMR. Several serum samples from normal people and liver-tumor-bearing patients were used for the detections of AFP concentration via IMR. These results reveal the feasibilities of assaying AFP in blood using IMR, as well as achieving high-sensitive and high-specific assay for AFP. PMID:22619536

Huang, Kai-Wen; Yang, Shieh-Yueh; Hong, Yu-Wei; Chieh, Jen-Jie; Yang, Che-Chuan; Horng, Herng-Er; Wu, Chau-Chung; Hong, Chin-Yih; Yang, Hong-Chang

2012-01-01

352

Development of an upconverting chelate assay  

NASA Astrophysics Data System (ADS)

We report progress on performing a cell-based assay for the detection of EGFR on cell surfaces by using upconverting chelates. An upconversion microscope has been developed for performing assays and testing optical response. A431 cells are labeled with europium DOTA and imaged using this upconverting microscope.

Xiao, Xudong; Haushalter, Jeanne P.; Kotz, Kenneth T.; Faris, Gregory W.

2005-04-01

353

The Ames Salmonella\\/microsome mutagenicity assay  

Microsoft Academic Search

The Ames Salmonella\\/microsome mutagenicity assay (Salmonella test; Ames test) is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances that can produce genetic damage that leads to gene mutations. The test employs several histidine dependent Salmonella strains each carrying different mutations in various genes in the histidine operon. These mutations act as hot

Kristien Mortelmans; Errol Zeiger

2000-01-01

354

Strategic petroleum reserve crude oil assays  

SciTech Connect

This booklet provides background information on the purchase of crude oils for the Strategic Petroleum Reserve (SPR), procedures used to assess quality of the stored petroleum, and methods used in generating assays of the various streams which may be sold. Current assays of the eight SPR crude oil streams are included.

Not Available

1991-11-01

355

The comet assay: a comprehensive review  

Microsoft Academic Search

The comet assay is a sensitive and rapid method for DNA strand break detection in individual cells. Its use has increased significantly in the past few years. This paper is a review of the studies published to date that have made use of the comet assay. The principles of strand break detection using both the alkaline and neutral versions of

Daryl W. Fairbairn; Peggy L. Olive; Kim L. O'Neill

1995-01-01

356

Drag reduction in nature  

NASA Technical Reports Server (NTRS)

Recent studies on the drag-reducing shapes, structures, and behaviors of swimming and flying animals are reviewed, with an emphasis on potential analogs in vehicle design. Consideration is given to form drag reduction (turbulent flow, vortex generation, mass transfer, and adaptations for body-intersection regions), skin-friction drag reduction (polymers, surfactants, and bubbles as surface 'additives'), reduction of the drag due to lift, drag-reduction studies on porpoises, and drag-reducing animal behavior (e.g., leaping out of the water by porpoises). The need for further research is stressed.

Bushnell, D. M.; Moore, K. J.

1991-01-01

357

Paper disk assay for glycosaminoglycan sulfotransferases  

SciTech Connect

A method is described for the assay of sulfotransferases, which transfer sulfate from 3'-phosphoadenosine-5'-phosphosulfate (PAPS) to glycosaminoglycan acceptors. Following the sulfation reactions, the (/sup 35/S)sulfate-labeled products are precipitated and then separated from a sulfate donor ((/sup 35/S)PAPS) and its degradation products by a paper disk method, and then the radioactivity remaining on the paper disk is subsequently determined by liquid scintillation counting. The rapidity and simplicity of the method are advantageous for multiple assays and have allowed us to establish assay conditions for serum sulfotransferases which introduce sulfate at position 6 of the internal N-acetylgalactosamine units of chondroitin, position 2 (amino group) of the glucosamine units of heparan sulfate and sugar units of keratan sulfate, respectively. The assay method will be applicable with modification to the assay of other glycosaminoglycan sulfotransferases and glycoprotein sulfotransferases.

Sugahara, K.; Ishii, T.; Yamashina, I.

1987-11-01

358

Fluorometric assay for red blood cell antibodies  

SciTech Connect

A fluorometric assay is described for the detection of red blood cell antibodies. The assay reveals as little as 600 molecules of bound, fluoroesceinated rabbit anti-human IgG antibodies per erythrocyte. Eleven patients with possible autoimmune erythrocyte disorder and negative direct antiglobulin test were studied by the fluorometric assay. The outcome of the fluorometric assay was compared with that of the human allogeneic rosette test. Results obtained by the two methods were in complete agreement. Five of the patients were shown to possess unexpectedly high levels of erythrocyte-bound IgG in spite of a negative, direct antiglobulin test. These findings and the validity of the fluorometric assay are discussed.

Schreiber, A.B.; Lambermont, M.; Strosberg, A.D.; Wybran, J.

1981-03-01

359

ATP-independent substrate reduction by nitrogenase P-cluster variant  

PubMed Central

The P-cluster of nitrogenase is largely known for its function to mediate electron transfer to the active cofactor site during catalysis. Here, we show that a P-cluster variant (designated P*-cluster), which consists of paired [Fe4S4]-like clusters, can catalyze ATP-independent substrate reduction in the presence of a strong reductant, europium(II) diethylenetriaminepentaacetate [Eu(II)-DTPA]. The observation of a decrease of activity in the rank ?nifH, ?nifB?nifZ, and ?nifB MoFe protein, which corresponds to a decrease of the amount of P*-clusters in these cofactor-deficient proteins, firmly establishes P*-cluster as a catalytically active metal center in Eu(II)-DTPA–driven reactions. More excitingly, the fact that P*-cluster is not only capable of catalyzing the two-electron reduction of proton, acetylene, ethylene, and hydrazine, but also capable of reducing cyanide, carbon monoxide, and carbon dioxide to alkanes and alkenes, points to a possibility of developing biomimetic catalysts for hydrocarbon production under ambient conditions. PMID:22509042

Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W.

2012-01-01

360

Miniaturization and application of the MTT assay to evaluate metabolic activity of protozoa in the presence of toxicants  

Microsoft Academic Search

This paper describes a critical evaluation of a miniaturised colorimetric assay, using MTT (3-(4,5- dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) reduction, applied to protozoan viability testing. The toxic substances used were copper, zinc, Triton X-100 (a membrane surfactant) and cycloheximide (an inhibitor of the protein synthesis). The viability assay of the ciliate protozoan Tetrahymena pyriformis was optimised in terms of MTT concentration and incubation

N. Dias; A. Nicolau; G. S. Carvalho; M. Mota; N. Lima

1999-01-01

361

Design and optimization of a double-enzyme glucose assay in microfluidic lab-on-a-chip  

Microsoft Academic Search

An electrokinetic driven microfluidic lab-on-a-chip was developed for glucose quantification using double-enzyme assay. The enzymatic glucose assay involves the two-step oxidation of glucose, which was catalyzed by hexokinase and glucose-6-phosphate dehydrogenase, with the concomitant reduction of NADP+ to NADPH. A fluorescence microscopy setup was used to monitor the different processes (fluid flow and enzymatic reaction) in the microfluidic chip. A

Yegermal Tesfaw Atalay; Daan Witters; Steven Vermeir; Nicolas Vergauwe; Pieter Verboven; Jeroen Lammertyn

2009-01-01

362

Human somatic mutation assays as biomarkers of carcinogenesis  

SciTech Connect

This paper describes four assays that detect somatic gene mutations in humans: the hypoxanthine-guanine phosphoribosyl transferase assay, the glycophorin A assay, the HLA-A assay, and the sickle cell hemoglobin assay. Somatic gene mutations can be considered a biomarker of carcinogenesis, and assays for somatic mutation may assist epidemiologists in studies that attempt to identify factors associated with increased risks of cancer. Practical aspects of the use of these assays are discussed.

Compton, P.J.E.; Smith, M.T. (Univ. of California, Berkeley (United States)); Hooper, K. (California Dept. of Health Services, Berkeley (United States))

1991-08-01

363

The kinetics-based enzyme-linked immunosorbent assay for coronavirus antibodies in cats: calibration to the indirect immunofluorescence assay and computerized standardization of results through normalization to control values.  

PubMed Central

The computer-assisted, kinetics-based enzyme-linked immunosorbent assay for coronavirus antibodies in cats was calibrated to the conventional indirect immunofluorescence assay by linear regression analysis and computerized interpolation (generation of "immunofluorescence assay-equivalent" titers). Procedures were developed for normalization and standardization of kinetics-based enzyme-linked immunosorbent assay results through incorporation of five different control sera of predetermined ("expected") titer in daily runs. When used with such sera and with computer assistance, the kinetics-based enzyme-linked immunosorbent assay minimized both within-run and between-run variability while allowing also for efficient data reduction and statistical analysis and reporting of results. PMID:3032390

Barlough, J E; Jacobson, R H; Downing, D R; Lynch, T J; Scott, F W

1987-01-01

364

Reduction of glycyrrhizic acid  

Microsoft Academic Search

The reduction of glycyrrhizic acid by NaBH4 and LiAlH4 was studied. The conditions for the selective reduction of the COOH groups of the carbohydrate chain and the C(11)=0 group\\u000a of aglycon were found.

L. A. Baltina; N. G. Serdyuk; E. V. Vasil’eva; G. A. Tolstikov

1997-01-01

365

Harm Reduction Therapy Groups  

Microsoft Academic Search

Harm reduction psychotherapy is the newest approach to engaging and working with substance users and abusers. It combines public health principles and interventions, motivational interviewing, and psychiatric treatment with psychodynamic psychotherapy to create an integrated model of treating individuals with substance abuse and psychiatric or emotional problems. In groups, harm reduction psychotherapy exposes group members to the continuum of drug

Jeannie Little

2006-01-01

366

Does Source Reduction Work?  

ERIC Educational Resources Information Center

Suggests that quantification is essential to establish the cost-effectiveness of source reduction (SR). Presents case studies of monitoring methods for seven different kinds of SR efforts: (1) packaging changes, (2) SR businesses, (3) waste exchanges, (4) individual nonresidential efforts, (5) variable garbage rates, (6) yard waste reduction, and…

Allaway, David

1992-01-01

367

CARBON DIOXIDE EMISSION REDUCTION  

E-print Network

CARBON DIOXIDE EMISSION REDUCTION TECHNOLOGIES AND MEASURES IN US INDUSTRIAL SECTOR FINAL REPORT TO KOREA ENVIRONMENT INSTITUTE FEBRUARY 2007 #12;B #12;C CARBON DIOXIDE EMISSION REDUCTION TECHNOLOGIES.5 Primary Energy Use and Carbon Dioxide Emissions for Selected US Chemical Subsectors in 1994

Delaware, University of

368

Quantitative Plasmodium sporozoite neutralization assay (TSNA).  

PubMed

The circumsporozoite (CS) protein is the major surface protein of Plasmodium sporozoites. Antibodies to the immunodominant repeat domain of CS immobilize sporozoites and prevent infection of hepatocytes. Plasmodium falciparum vaccines containing CS repeats are undergoing human trials in endemic areas, and proof of efficacy has been obtained. The correlates of protection are under investigation. Levels of anti-repeat antibodies in the serum of the human volunteers have been measured mostly by enzyme-linked immunosorbent assay (ELISA) and IFA. Assays that measure the effect of the serum antibodies on parasite infectivity (serum neutralization assays SNAs) are not usually performed because they require a susceptible host and P. falciparum sporozoites are highly infectious only to humans. To overcome this limitation, we developed a new assay named transgenic sporozoite neutralization assay (TSNA) that uses as neutralization target, a transgenic rodent malaria parasite Plasmodium berghei that bears the P. falciparum CS repeats [CS(Pf)]. Following incubation with human serum, CS(Pf) infectivity of HepG2 cells is evaluated by real-time PCR. We have compared ELISA titers and TSNAs in a limited number of sera from humans immunized with (T1B)4 MAP, a peptide vaccine containing P. falciparum CS repeats. A comparison between the two assays did not reach significance (p=0.175) when analyzed by non-parametric Spearman correlation method. Ongoing human trials of CS-based vaccines should provide an opportunity to determine whether TSNAs will provide better correlates of protective immunity than ELISA assays. PMID:15350520

Kumar, Kota Arun; Oliveira, Giane A; Edelman, Robert; Nardin, Elizabeth; Nussenzweig, Victor

2004-09-01

369

A All-Vacuum High Resolution Fourier Transform Spectrometer with Absorption Pathlengths up to 352 M: Acetylene Spectrum at 1.4-1.7 Microns.  

NASA Astrophysics Data System (ADS)

The spectra of acetylene (C_2H _2) and of water vapor have been recorded at room temperature with Doppler- or pressure -broadening-limited resolution at pathlengths up to 352m. The spectra were obtained with the combination of a FTIR (Fourier Transform Infrared) spectrometer, evacuated transfer optics, and a multipass cell of 4m base length. The measurements were performed at the Justus-Liebig-Universitat in Giessen, Germany, using the FTIR spectrometer at that university, the multipass cell assembled at The Ohio State University, and the vacuum transfer optics designed by the author. The regions in which the spectra were recorded are 5900-7150 cm^{-1} and 1850-6600 cm^{-1}. Calibration difficulties pertaining to the determination of the absolute accuracy of the data have been resolved, and molecular parameters have been extracted for the HCCH data. These calibration problems were not documented in earlier studies using high resolution Fourier transform spectrometers. For this reason, the dissertation addresses this matter in somewhat greater detail. This work contains a description of the technology used to obtain the data, and a description of the calibration of the spectra to make them suitable for future use as secondary wavenumber calibration standards. The bands detected for the first time in this study have been reported, and updated energy level diagrams for HCCH and H^{13}CCH have been included. The molecular parameters obtained from the HCCH spectra have been presented. The appendices include, among others, the basic observational data, a spectral map and associated wavenumber lists of HCCH, and a description of the weighting scheme developed by the author for Fourier Transform spectra.

Keppler, Karen Ann

1995-01-01

370

Dichlorophenylurea-insensitive Reduction of Silicomolybdic Acid by Chloroplast Photosystem II  

PubMed Central

The photoreduction of silicomolybdate and other heteropoly ions by chloroplasts is insensitive to 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea (DCMU). Both water and diphenylcarbazide can be used as electron source for the reduction. Three different assays for silicomolybdate reduction are described including oxygen evolution, formation of a reduced heteropoly blue silicomolybdate, or an indirect assay for reduced silicomolybdate by redox indicators, such as ferricyanide or cytochrome c. The effects of detergents and tris washing are consistent with silicomolybdate reduction through photosystem II before the DCMU site. The effects of orthophenanthroline and bathophenanthroline indicate chelator-sensitive sites in photosystem II before the site of DCMU action. PMID:16659102

Barr, R.; Crane, F. L.; Giaquinta, R. T.

1975-01-01

371

Methods for threshold determination in multiplexed assays  

DOEpatents

Methods for determination of threshold values of signatures comprised in an assay are described. Each signature enables detection of a target. The methods determine a probability density function of negative samples and a corresponding false positive rate curve. A false positive criterion is established and a threshold for that signature is determined as a point at which the false positive rate curve intersects the false positive criterion. A method for quantitative analysis and interpretation of assay results together with a method for determination of a desired limit of detection of a signature in an assay are also described.

Tammero, Lance F. Bentley; Dzenitis, John M; Hindson, Benjamin J

2014-06-24

372

[Recent advances in enzyme assays using fluoremetry].  

PubMed

Enzymes play such a pivotal role in cellular metabolism that enzyme assays are important for bio-engineering, disease diagnoses and drug discovery. Among the reported methods, fluoremetry has attracted more and more attention due to its high sensitivity and possibility of continuous dynamic monitoring. The recent progresses and applications in enzyme assays using fluorescent probes were reviewed. Different methods were classified into direct fluorescence detection and indirect fluorescence detection according to their labeled substrates and detection mechanisms. Our writing purpose is to provide the readers with a flavor of the kinds of tools and strategies available in enzyme assays with fluorescent probes. Also, the research situation and prospects were disucssed PMID:20352949

Xing, Yanlong; Mao, Xiangzhao; Wang, Shu; Wang, Hualei; Wei, Dongzhi

2009-12-01

373

A new microbiological assay for glycine  

E-print Network

A NEW MICROBIOLOOICAL ASSAY FOR OLYCINE A Thesis Levis Calhoun Sans, Jx. Approved as to style end content by Chairraan oP Committee ani oP 3epartaan' LISi'Airy A d N COLLEGE OF TEXAS A HEM MICROBIOLOGICAL ASSAY FOR GLYCINE by Lewis... of the ox'gan1sm. It is quite unusual that the effect. of st1muistion or inhibition of a hydrolysate is the same for different types of organisms As a conseglkence p 1n some cases the assay values obtained will differ when different organisss are used...

Sams, Lewis Calhoun

1954-01-01

374

Practical assay for nitrite and nitrosothiol as an alternative to the griess assay or the 2,3-diaminonaphthalene assay.  

PubMed

Nitrite is a heavily assayed substrate in the fields of food safety, water quality control, disease diagnosis, and forensic investigation and more recently in basic biological studies on nitric oxide physiology and pathology. The colorimetric Griess assay and the fluorimetric 2,3-diaminonaphthalene (DAN) assay are the current gold standards for nitrite quantification. They are not without limitations, yet have amazingly survived 156 and 44 years, respectively, due to the lack of a practical alternative. Both assays exhibit slow detection kinetics due to inactivation of nucleophiles under strongly acidic media, require an extensive incubation time for reaction to go completion, and hence offer a limited detection throughput. By converting an intermolecular reaction of the Griess assay intramolecularly, we designed a novel probe (NT555) for nitrite detection, which displays superior detection kinetics and sensitivity. NT555 was constructed following our "covalent-assembly" probe design principle. Upon detection, it affords a gigantic bathochromic shift of the absorption spectrum and a sensitive turn-on fluorescence signal from a zero background, both of which are typical of an "assembly" type probe. Overall, NT555 has addressed various difficulties associated with the Griess and the DAN assays and represents an attractive alternative for practical applications. PMID:25519711

Shen, Yanming; Zhang, Quanjuan; Qian, Xuhong; Yang, Youjun

2015-01-20

375

A High-throughput Screening Assay for Determining Cellular Levels of Total Tau Protein  

PubMed Central

The microtubule-associated protein (MAP) tau has been implicated in the pathology of numerous neurodegenerative diseases. In the past decade, the hyperphosphorylated and aggregated states of tau protein have been important targets in the drug discovery field for the potential treatment of Alzheimer’s disease. Although several compounds have been reported to reduce the hyperphosphorylated state of tau or impact the stabilization of tau, their therapeutic activities are still to be validated. Recently, reduction of total cellular tau protein has emerged as an alternate intervention point for drug development and a potential treatment of tauopathies. We have developed and optimized a homogenous assay, using the AlphaLISA and HTRF assay technologies, for the quantification of total cellular tau protein levels in the SH-SY5Y neuroblastoma cell line. The signal-to-basal ratios were 375 and 5.3, and the Z’ factors were 0.67 and 0.60 for the AlphaLISA and HTRF tau assays, respectively. The clear advantages of this homogeneous tau assay over conventional total tau assays, such as ELISA and Western blot, are the elimination of plate wash steps and miniaturization of the assay into 1536-well plate format for the ultra–high-throughput screening of large compound libraries. PMID:23905996

Dehdashti, Seameen J.; Zheng, Wei; Gever, Joel R.; Wilhelm, Robert; Nguyen, Dac-Trung; Sittampalam, Gurusingham; McKew, John C.; Austin, Christopher P.; Prusiner, Stanley B.

2014-01-01

376

CONTROL ASSAY DEVELOPMENT: METHODOLOGY AND LABORATORY VERIFICATION  

EPA Science Inventory

The report describes Control Assay Development (CAD), a data acquisition program designed to evaluate the potential applicability of various treatment processes for the control of solid, liquid, and gaseous emissions from coal conversion plants. The CAD program described could be...

377

Methylenetetrahydrofolate dehydrogenase assay microplate format Stock solutions  

E-print Network

Methylenetetrahydrofolate dehydrogenase assay ­ microplate format Stock solutions 2X buffer: 166 m. Store on ice. This yields a 1 mM CH2-THF stock in 100 mM 2-mercaptoethanol. Final volume in each well

378

21 CFR 864.7250 - Erythropoietin assay.  

Code of Federal Regulations, 2013 CFR

...or urine. This assay provides diagnostic information for the evaluation of erythrocytosis (increased total red cell mass) and anemia. (b) Classification. Class II. The special control for this device is FDA's “Document for Special Controls for...

2013-04-01

379

21 CFR 864.7250 - Erythropoietin assay.  

Code of Federal Regulations, 2010 CFR

...or urine. This assay provides diagnostic information for the evaluation of erythrocytosis (increased total red cell mass) and anemia. (b) Classification. Class II. The special control for this device is FDA's “Document for Special Controls for...

2010-04-01

380

21 CFR 864.7250 - Erythropoietin assay.  

Code of Federal Regulations, 2014 CFR

...or urine. This assay provides diagnostic information for the evaluation of erythrocytosis (increased total red cell mass) and anemia. (b) Classification. Class II. The special control for this device is FDA's “Document for Special Controls for...

2014-04-01

381

21 CFR 864.7425 - Carboxyhemoglobin assay.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7425 Carboxyhemoglobin assay. (a) Identification. A...

2011-04-01

382

21 CFR 864.7525 - Heparin assay.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7525 Heparin assay. (a) Identification. A heparin...

2011-04-01

383

21 CFR 864.7490 - Sulfhemoglobin assay.  

Code of Federal Regulations, 2011 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7490 Sulfhemoglobin assay. (a) Identification. A...

2011-04-01

384

BIOMARKER ASSAYS IN NIPPLE APIRATE FLUID  

EPA Science Inventory

ABSTRACT The noninvasive technique of nipple aspiration as a potential source of biomarkers of breast cancer risk was evaluated. The feasibility of performing mutagenesis assays, amplifying DNA and performing protein electrophoresis on nipple aspirate fluid was explored. ...

385

21 CFR 864.7525 - Heparin assay.  

Code of Federal Regulations, 2012 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7525 Heparin assay. (a) Identification. A heparin...

2012-04-01

386

21 CFR 864.7490 - Sulfhemoglobin assay.  

Code of Federal Regulations, 2012 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7490 Sulfhemoglobin assay. (a) Identification. A...

2012-04-01

387

21 CFR 864.7525 - Heparin assay.  

Code of Federal Regulations, 2013 CFR

... FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7525 Heparin assay. (a) Identification. A heparin...

2013-04-01

388

Assay for Arf GTP-binding Proteins  

Cancer.gov

The National Cancer Institute's Laboratory of Cellular and Molecular Biology is seeking statements of capability or interest from parties interested in collaborative research to further develop, evaluate, or commercialize an antibody-based proteomics assay.

389

Electrochemical Assay of Gold-Plating Solutions  

NASA Technical Reports Server (NTRS)

Gold content of plating solution is assayed by simple method that required only ordinary electrochemical laboratory equipment and materials. Technique involves electrodeposition of gold from solution onto electrode, the weight gain of which is measured. Suitable fast assay methods are economically and practically necessary in electronics and decorative-plating industries. If gold content in plating bath is too low, poor plating may result, with consequent economic loss to user.

Chiodo, R.

1982-01-01

390

Preliminary assay reveals quality of Mars blend  

Microsoft Academic Search

Shell Oil Co. has assayed a preproduction well sample of Mars blend, from the Louisiana Gulf of Mexico. The assay shows the crude to have an API gravity of 31° and a sulfur content of 2.0 wt%. Distillation data for the crude are shown in this paper. When partners Shell (71.5%) and BP (28.5%) begin commercial production in July, several

1996-01-01

391

The comet assay: a heavenly method!  

PubMed

The contributions to this special issue of Mutagenesis have been selected to cover the main research areas served by the comet assay, namely genotoxicology, environmental toxicology, human biomonitoring and fundamental investigations into mechanisms of DNA damage and repair. Innovative methods are described, technical issues are explored, and guidelines are given for venturing into relatively new or unexploited areas of research. The popularity of the comet assay in a historical context is illustrated by a bibliometric survey. PMID:25527721

Collins, Andrew R

2015-01-01

392

Scintillation proximity assay of arginine methylation.  

PubMed

Methylation of arginine residues, catalyzed by protein arginine methyltransferases (PRMTs), is one important protein posttranslational modification involved in epigenetic regulation of gene expression. A fast and effective assay for PRMT can provide valuable information for dissecting the biological functions of PRMTs, as well as for screening small-molecule inhibitors of arginine methylation. Currently, among the methods used for PRMT activity measurement, many contain laborious separation procedures, which restrict the applications of these assays for high-throughput screening (HTS) in drug discovery. The authors report here a mix-and-measure method to measure PRMT activity based on the principle of scintillation proximity assay (SPA). In this assay, (3)H-AdoMet was used as methyl donor, and biotin-modified histone H4 peptide served as a methylation substrate. Following the methylation reaction catalyzed by PRMTs, streptavidin-coated SPA beads were added to the reaction solution, and SPA signals were detected by a MicroBeta scintillation counter. No separation step is needed, which simplifies the assay procedure and greatly enhances the assay speed. Particularly, the miniaturization and robustness suggest that this method is suited for HTS of PRMT inhibitors. PMID:21821785

Wu, Jiang; Xie, Nan; Feng, You; Zheng, Y George

2012-02-01

393

Protein immobilization techniques for microfluidic assays  

PubMed Central

Microfluidic systems have shown unequivocal performance improvements over conventional bench-top assays across a range of performance metrics. For example, specific advances have been made in reagent consumption, throughput, integration of multiple assay steps, assay automation, and multiplexing capability. For heterogeneous systems, controlled immobilization of reactants is essential for reliable, sensitive detection of analytes. In most cases, protein immobilization densities are maximized, while native activity and conformation are maintained. Immobilization methods and chemistries vary significantly depending on immobilization surface, protein properties, and specific assay goals. In this review, we present trade-offs considerations for common immobilization surface materials. We overview immobilization methods and chemistries, and discuss studies exemplar of key approaches—here with a specific emphasis on immunoassays and enzymatic reactors. Recent “smart immobilization” methods including the use of light, electrochemical, thermal, and chemical stimuli to attach and detach proteins on demand with precise spatial control are highlighted. Spatially encoded protein immobilization using DNA hybridization for multiplexed assays and reversible protein immobilization surfaces for repeatable assay are introduced as immobilization methods. We also describe multifunctional surface coatings that can perform tasks that were, until recently, relegated to multiple functional coatings. We consider the microfluidics literature from 1997 to present and close with a perspective on future approaches to protein immobilization. PMID:24003344

Kim, Dohyun; Herr, Amy E.

2013-01-01

394

Radioimmune assay of human platelet prostaglandin synthetase  

SciTech Connect

Normal platelet function depends, in part, on platelet PG synthesis. PG synthetase (cyclo-oxygenase) catalyzes the first step in PG synthesis, the formation of PGH/sub 2/ from arachidonic acid. Inhibition of the enzyme by ASA results in an abnormality in the platelet release reaction. Patients with pparent congenital abnormalities in the enzyme have been described, and the effects have been referred to as ''aspirin-like'' defects of the platelet function. These patients lack platelet PG synthetase activity, but the actual content of PG synthetase protein in these individuals' platelets is unknown. Therefore an RIA for human platelet PG synthetase would provide new information, useful in assessing the aspirin-like defects of platelet function. An RIA for human platelet PG synthetase is described. The assay utilizes a rabbit antibody directed against the enzyme and (/sup 125/I)-labelled sheep PG synthetase as antigen. The human platelet enzyme is assayed by its ability to inhibit precipitation of the (/sup 125/I)antigen. The assay is sensitive to 1 ng of enzyme. By the immune assay, human platelets contain approximately 1200 ng of PG synethetase protein per 1.5 mg of platelet protein (approximately 10/sup 9/ platelets). This content corresponds to 10,000 enzyme molecules per platelet. The assay provides a rapid and convenient assay for the human platelet enzyme, and it can be applied to the assessment of patients with apparent platelet PG synthetase (cyclo-oxygenase) deficiency.

Roth, G.J.; Machuga, E.T.

1982-02-01

395

Synthesis and antiproliferative assay of norcantharidin derivatives in cancer cells.  

PubMed

Diels-Alder reaction between furan and maleic anhydride resulted in 5,6-dehydro norcantharidin, then norcantharidin was obtained by reduction. The substituted-carboxylic acid was condensed with N-aminothiourea in presence of phosphorus oxychloride, yielding 2-amino-1,3,4-thiadiazole derivatives. Novel norcantharidin derivatives were synthesized with acylation, then intramolecular condensation using norcantharidin (or 5,6-dehydro norcantharidin) and 2-amino- 1,3,4-thiadiazole derivatives. All the target compounds were confirmed by IR, (1)HNMR, ESI-MS and were reported for the first time. Norcantharidin derivatives antiproliferative assay was tested by MTT method against A549 and PC-3 cell lines. The results showed that all the norcantharidin derivatives displayed moderate inhibitory activities. PMID:23909288

Tu, Guo Gang; Zhan, Jian Feng; Lv, Qiao Li; Wang, Jia Qi; Kuang, Bin Hai; Li, Shao Hua

2014-06-01

396

A photochemical study of the kinetics of the reactions of NH2 with phosphine, ethylene, and acetylene using flash photolysis-laser induced fluorescence. Ph.D. Thesis Catholic Univ. of America; [ammonia in the atmosphere of Jupiter  

NASA Technical Reports Server (NTRS)

The photochemistry of the reactions of NH2 was investigated in an attempt to explain the existence of an abundance of ammonia in the Jovian atmosphere. The production of ammonia reservoirs from the coupling of ammonia with other atmospheric constituents was considered. The rate constants for the reactions of NH2 radicals with phosphine, acetylene, and ethylene were measured. Flash photolysis was used for the production of NH2 radicals and laser induced fluorescence was employed for radical detection. It was determined that the rates of the reactions were too slow to be significant as a source of ammonia reservoirs in the Jovian atmosphere.

Bosco, S. R.

1982-01-01

397

Reduction redux of adinkras  

NASA Astrophysics Data System (ADS)

We show performing general "0-brane reduction" along an arbitrary fixed direction in space-time and applied to the starting point of minimal, off-shell 4D, 𝒩 = 1 irreducible supermultiplets, yields adinkras whose adjacency matrices are among some of the special cases proposed by Kuznetsova, Rojas and Toppan. However, these more general reductions also can lead to "Garden Algebra" structures beyond those described in their work. It is also shown that for light-like directions, reduction to the 0-brane breaks the equality in the number of fermions and bosons for dynamical theories. This implies that light-like reductions should be done instead to the space of 1-branes or equivalently to the worldsheet.

Gates, S. James; Randall, Stephen; Stiffler, Kory

2014-04-01

398

AMD NOX REDUCTION IMPACTS  

EPA Science Inventory

This is the first phase of a potentially multi-phase project aimed at identifying scientific methodologies that will lead to the development of innnovative analytical tools supporting the analysis of control strategy effectiveness, namely. accountabilty. Significant reductions i...

399

A novel coagulation assay incorporating adherent endothelial cells in thromboelastometry.  

PubMed

Following vascular injury or activation, endothelial cells (ECs) participate in the modulation of haemostasis and fibrinolysis. Viscoelastic tests (VETs) are a potent bedside monitoring tool that reports haemostatic parameters in real time. However, VETs neglect the influence of the surrounding endothelium. Our aim was therefore to establish an assay that incorporates ECs in a whole blood VET and to assess the impact of ECs on coagulation parameters. Outgrowth endothelial cells (OECs) and human umbilical vein endothelial cells (HUVECs) were seeded onto microbeads to create transferable EC-microcarriers. Microbeads were then added to citrated whole blood in the measurement cup of a thromboelastometry device (ROTEM). After the addition of CaCl2 (star-TEM®) to the blood sample (NATEM assay), standard ROTEM parameters were analysed. Scanning electron microscopy (SEM) was carried out to visualise the interactions of the beads, whole blood components and the ROTEM pin after clotting. SEM showed that the added microbeads were effectively incorporated into the final blood clot. In the presence of activated ECs, the clotting time (CT) of the blood was shortened fourfold compared to that in uncoated control beads. A significant reduction in CT was also observed in the presence of unstimulated ECs. Interestingly, CT was also reduced by the addition of purified EC culture supernatant. CT shortening was prevented by incubating the supernatant with an inhibiting antibody against tissue factor (TF). Our findings demonstrate that ECs can be incorporated into a ROTEM assay via coated microbeads, and whole blood clotting initiation is accelerated by non-activated and activated ECs. PMID:23494019

Zipperle, J; Schlimp, C J; Holnthoner, W; Husa, A-M; Nürnberger, S; Redl, H; Schöchl, H

2013-05-01

400

Embryotoxicity assays for leached components from dental restorative materials  

PubMed Central

Background Currently, there are no suitable assays available to evaluate the embryotoxicity of leached components from restorative dental materials. Methods The effect of the medium conditioned by composites and amalgam on mouse blastocysts in vitro was tested. The materials were also subcutaneously implanted, and the effect of the medium supplemented with serum from the host blood was evaluated in the embryotoxicity assay. The embryo implantation rate in the material-transplanted mothers was also evaluated. Results The results show that while the culture in media conditioned by amalgams did not affect blastocyst development, the medium conditioned by composites caused blastocyst degeneration and apoptosis. The development of blastocysts in a medium containing serum obtained from animals after transplantation was, however, without effect. Finally, inconsistent reduction in the implantation rate in transplanted mothers was observed. Conclusions In this study, we provide examples of in vitro and in vivo tests that may be used to evaluate embryotoxicity for dental materials. Our results show that leached components from our composite-material induced embryotoxicity in vitro, however, no toxicity was observed when subcutaneously implanted in vivo. This highlights the necessity of integrated in vitro and in vivo tests for valuable predictive estimation of embryotoxicity for complex materials. PMID:21978455

2011-01-01

401

21 CFR 864.7500 - Whole blood hemoglobin assays.  

Code of Federal Regulations, 2013 CFR

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2013-04-01

402

21 CFR 864.7500 - Whole blood hemoglobin assays.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Whole blood hemoglobin assays. 864.7500 Section...Kits and Packages § 864.7500 Whole blood hemoglobin assays. (a) Identification. A whole blood hemoglobin assay is a device...

2012-04-01

403

21 CFR 864.7500 - Whole blood hemoglobin assays.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Whole blood hemoglobin assays. 864.7500 Section...Kits and Packages § 864.7500 Whole blood hemoglobin assays. (a) Identification. A whole blood hemoglobin assay is a device...

2014-04-01

404

21 CFR 864.7500 - Whole blood hemoglobin assays.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Whole blood hemoglobin assays. 864.7500 Section...Kits and Packages § 864.7500 Whole blood hemoglobin assays. (a) Identification. A whole blood hemoglobin assay is a device...

2011-04-01

405

21 CFR 866.3305 - Herpes simplex virus serological assays.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Herpes simplex virus serological assays. 866.3305 Section...Reagents § 866.3305 Herpes simplex virus serological assays. (a) Identification . Herpes simplex virus serological assays are devices...

2011-04-01

406

21 CFR 866.3305 - Herpes simplex virus serological assays.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Herpes simplex virus serological assays. 866.3305 Section...Reagents § 866.3305 Herpes simplex virus serological assays. (a) Identification . Herpes simplex virus serological assays are devices...

2012-04-01

407

21 CFR 866.3305 - Herpes simplex virus serological assays.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 false Herpes simplex virus serological assays. 866.3305 Section...Reagents § 866.3305 Herpes simplex virus serological assays. (a) Identification. Herpes simplex virus serological assays are devices...

2014-04-01

408

21 CFR 866.3305 - Herpes simplex virus serological assays.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Herpes simplex virus serological assays. 866.3305 Section...Reagents § 866.3305 Herpes simplex virus serological assays. (a) Identification . Herpes simplex virus serological assays are devices...

2013-04-01

409

21 CFR 864.7500 - Whole blood hemoglobin assays.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Whole blood hemoglobin assays. 864.7500 Section...Kits and Packages § 864.7500 Whole blood hemoglobin assays. (a) Identification. A whole blood hemoglobin assay is a device...

2010-04-01

410

21 CFR 866.3305 - Herpes simplex virus serological assays.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Herpes simplex virus serological assays. 866... Serological Reagents § 866.3305 Herpes simplex virus serological assays. (a) Identification . Herpes simplex virus serological assays...

2010-04-01

411

The effects of urbanization on Lepomis macrochirus using the comet assay.  

PubMed

Urbanization has been linked to increased concentrations of polycyclic aromatic hydrocarbons in natural waterways. This study was designed to examine the impact of urbanization and a wastewater treatment plant by investigating the impact on field-collected bluegill (Lepomis macrochirus). Results show a significant increase in DNA strand breaks in blood cells (comet assay) linked to urbanization and a reduction in DNA strand breaks downstream of the WWTP, likely the result of dilution. A laboratory study exposing L. macrochirus to the known mutagen, methyl methanesulfonate, was performed to validate the comet assay endpoints in this species. Results of the laboratory study showed that the comet assay endpoints of tail length and tail extent moment responded in a dose- and time-dependent manner. Habitat quality assessments, along with chemical concentrations of polycyclic hydrocarbons in sediments showed that habitat quality between all sites were similar and that hydrocarbons likely contributed to the DNA strand breaks observed. PMID:22885057

Otter, Ryan R; Meier, John; Kubach, Kevin M; Lazorchak, James M; Klaine, Stephen J

2012-10-01

412

A novel and more sensitive loop-mediated isothermal amplification assay targeting IS6110 for detection of Mycobacterium tuberculosis complex.  

PubMed

Developing improved tuberculosis (TB) diagnostics is one of the international research priorities, as TB remains globally a major health threat. Loop-mediated isothermal amplification (LAMP) is a new nucleic acid detection method that can be used in low-resource settings, because it does not require expensive or complex instruments. Using the repetitive insertion sequence IS6110 as a target gene, we developed an efficient LAMP assay, which specifically detects members of the Mycobacterium tuberculosis complex (MTBC). This assay proved 20 times more sensitive than IS6110-based conventional PCR. Moreover, its sensitivity was, respectively, 50 and 20 times higher than the one obtained with the two previously described LAMP assays for M. tuberculosis, based on gyrB and rrs, respectively. Identical sensitivities were obtained for LAMP and nested PCR, but the LAMP assay was more rapid and cost-effective than the latter. Although, our LAMP assay can successfully be performed using a non-denatured template, this results in a 200-fold reduction in the sensitivity of the assay. Moreover, by performing our LAMP assay on 15 clinical sputum samples from TB patients we were able to detect MTB. Taken together, our preliminary results indicate that IS6110-based MTBC-LAMP assay is a promising new TB-diagnostic test, with high sensitivity and that could easily be applied for the diagnosis of TB in a low-resource setting. PMID:19515543

Aryan, Ehsan; Makvandi, Manoochehr; Farajzadeh, Ahmad; Huygen, Kris; Bifani, Pablo; Mousavi, Seyed-Latif; Fateh, Abolfazl; Jelodar, Abbass; Gouya, Mohammad-Mehdi; Romano, Marta

2010-03-31

413

Current and future application of genetic toxicity assays: the role and value of in vitro mammalian assays.  

PubMed

With the advent of new technologies (e.g., genomics, automated analyses, and in vivo monitoring), new regulations (e.g., the reduction of animal tests by the European REACH), and new approaches to toxicology (e.g., Toxicity Testing in the 21st Century, National Research Council), the field of regulatory genetic toxicology is undergoing a serious re-examination. Within this context, Toxicological Sciences has published a series of articles in its Forum Section on the theme, "Genetic Toxicity Assessment: Employing the Best Science for Human Safety Evaluation" (beginning with Goodman et al.). As a contribution to the Forum discussions, we present current methods for evaluating mutagenic/genotoxic risk using standard genotoxicity test batteries, and suggest ways to address and incorporate new technologies. We recognize that the occurrence of positive results in relation to cancer prediction has led to criticism of in vitro mammalian cell genetic toxicity assays. We address criticism of test results related to weak positives, associated only with considerable toxicity, only seen at high concentrations, not accompanied by positive results in the other tests of standard test batteries, and/or not correlating well with rodent carcinogenicity tests. We suggest that the problems pointed out by others with these assays already have been resolved, to a large extent, by international groups working to update assay protocols, and by changes in data interpretation at regulatory agencies. New guidances at the U.S. Environmental Protection Agency and the U.S. Food and Drug Administration improve data evaluation and help refocus risk assessment. We discuss the results of international groups working together to integrate new technologies and evaluate new tests, including human monitoring. We suggest that strategies for identifying human health risks should naturally change to integrate new technologies; however, changes should be made only when justified by strong scientific evidence of improvement in the risk assessment paradigm. PMID:19336498

Elespuru, Rosalie K; Agarwal, Rajiv; Atrakchi, Aisar H; Bigger, C Anita H; Heflich, Robert H; Jagannath, Devaraya R; Levy, Dan D; Moore, Martha M; Ouyang, Yanli; Robison, Timothy W; Sotomayor, Rene E; Cimino, Michael C; Dearfield, Kerry L

2009-06-01

414

The role of H2 reduction in the growth of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) with their high mechanical, electrical, thermal and chemical properties are regarded as promising materials for many different potential applications. Chemical vapor deposition (CVD) is a common method for CNT synthesis especially for mass production. There are important parameters (synthesis temperature, catalyst and calcination conditions, substrate, carbon source, synthesis time, H2 reduction, etc.) affecting the structure, morphology and the amount of the CNT synthesis. In this study, CNTs were synthesized by CVD of acetylene (C2H2) on magnesium oxide (MgO) powder substrate impregnated by iron nitrate (Fe (NO3)3•9H2O) solution. The synthesis conditions were as follows: at catalyst calcination temperatures of 400 and 550°C, calcination time of 0, 15, 30 and 45 min, hydrogen concentrations of 0, 50 and 100 % vol, synthesis temperature of 800°C and synthesis time of 30 minutes. The synthesized materials were characterized by thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), X ray diffraction (XRD) and Raman spectroscopy. Effects of H2 reduction on catalyst calcination and CNT synthesis were investigated.

Yuca, Neslihan; Gümü?, Fatih; Karatepe, Nilgün

2013-09-01

415

Novel microwell-based spectrophotometric assay for determination of atorvastatin calcium in its pharmaceutical formulations  

PubMed Central

The formation of a colored charge-transfer (CT) complex between atorvastatin calcium (ATR-Ca) as a n-electron donor and 2, 3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as a ?-electron acceptor was investigated, for the first time. The spectral characteristics of the CT complex have been described, and the reaction mechanism has been proved by computational molecular modeling. The reaction was employed in the development of a novel microwell-based spectrophotometric assay for determination of ATR-Ca in its pharmaceutical formulations. The proposed assay was carried out in 96-microwell plates. The absorbance of the colored-CT complex was measured at 460 nm by microwell-plate absorbance reader. The optimum conditions of the reaction and the analytical procedures of the assay were established. Under the optimum conditions, linear relationship with good correlation coefficient (0.9995) was found between the absorbance and the concentration of ATR-Ca in the range of 10-150 ?g/well. The limits of detection and quantitation were 5.3 and 15.8 ?g/well, respectively. No interference was observed from the additives that are present in the pharmaceutical formulation or from the drugs that are co-formulated with ATR-Ca in its combined formulations. The assay was successfully applied to the analysis of ATR-Ca in its pharmaceutical dosage forms with good accuracy and precision. The assay described herein has great practical value in the routine analysis of ATR-Ca in quality control laboratories, as it has high throughput property, consumes minimum volume of organic solvent thus it offers the reduction in the exposures of the analysts to the toxic effects of organic solvents, and reduction in the analysis cost by 50-fold. Although the proposed assay was validated for ATR-Ca, however, the same methodology could be used for any electron-donating analyte for which a CT reaction can be performed. PMID:21982201

2011-01-01

416

Novel high-throughput deoxyribonuclease 1 assay.  

PubMed

Deoxyribonuclease I (DNase I), the most active and abundant apoptotic endonuclease in mammals, is known to mediate toxic, hypoxic, and radiation injuries to the cell. Neither inhibitors of DNase I nor high-throughput methods for screening of high-volume chemical libraries in search of DNase I inhibitors are, however, available. To overcome this problem, we developed a high-throughput DNase I assay. The assay is optimized for a 96-well plate format and based on the increase of fluorescence intensity when fluorophore-labeled oligonucleotide is degraded by the DNase. The assay is highly sensitive to DNase I compared to other endonucleases, reliable (Z' ? 0.5), and operationally simple, and it has low operator, intraassay, and interassay variability. The assay was used to screen a chemical library, and several potential DNase I inhibitors were identified. After comparison, 2 hit compounds were selected and shown to protect against cisplatin-induced kidney cell death in vitro. This assay will be suitable for identifying inhibitors of DNase I and, potentially, other endonucleases. PMID:25326282

Jang, Dae Song; Penthala, Narsimha R; Apostolov, Eugene O; Wang, Xiaoying; Fahmi, Tariq; Crooks, Peter A; Basnakian, Alexei G

2015-02-01

417

A bioluminescent assay for monoamine oxidase activity.  

PubMed

This article describes a novel two-step homogeneous bioluminescent assay for monoamine oxidase (MAO) that is simple, sensitive, and amenable to high-throughput screening. In the first step, MAO reacts with an aminopropylether analog of methyl ester luciferin. In the second step, a luciferin detection reagent inactivates MAO and converts the product of the first step into a luminescent signal. The amount of light produced is proportional to the amount of MAO and the time of incubation in the first step, but the luminescent signal is stable in the second step with a half-life greater than 5h. The assay has high precision, is more sensitive than current fluorescent methods, and can accurately measure the binding constants of known substrates and inhibitors. An automated screen of the Sigma-RBI Library of Pharmacologically Active Compounds (LOPAC(1280)) revealed a surprisingly high percentage of MAO inhibitors (16%) with a low false hit rate (0.9%). This implies that a significant number of compounds interact with the MAO enzymes and suggests that it is important to include MAO assays in drug metabolism studies. Other advantages of this bioluminescent assay over comparable fluorescent assays are discussed. PMID:17084801

Valley, Michael P; Zhou, Wenhui; Hawkins, Erika M; Shultz, John; Cali, James J; Worzella, Tracy; Bernad, Laurent; Good, Troy; Good, Dave; Riss, Terry L; Klaubert, Dieter H; Wood, Keith V

2006-12-15

418

Multiplexing schemes for generic SNP genotyping assays.  

PubMed

Association studies in populations relate genomic variation among individuals with medical condition. Key to these studies is the development of efficient and affordable genotyping techniques. Generic genotyping assays are independent of the target SNPs and offer great flexibility in the genotyping process. Efficient use of such assays calls for identifying sets of SNPs that can be interrogated in parallel under constraints imposed by the genotyping technology. In this paper, we study problems arising in the design of genotyping experiments using generic assays. Our problem formulation deals with two main factors that affect the genotyping cost: the number of assays used and the number of PCR reactions required for sample preparation. We prove that the resulting computational problems are hard, but provide approximate and heuristic solutions to these problems. Our algorithmic approach is based on recasting the multiplexing problems as partitioning and packing problems on a bipartite graph. We tested our algorithmic approaches on an extensive collection of synthetic data and on data that was simulated using real SNP sequences. Our results show that the algorithms achieve near-optimal designs in many cases and demonstrate the applicability of generic assays to SNP genotyping. PMID:15952875

Sharan, Roded; Gramm, Jens; Yakhini, Zohar; Ben-Dor, Amir

2005-06-01

419

A novel data mining method to identify assay-specific signatures in functional genomic studies  

PubMed Central

Background: The highly dimensional data produced by functional genomic (FG) studies makes it difficult to visualize relationships between gene products and experimental conditions (i.e., assays). Although dimensionality reduction methods such as principal component analysis (PCA) have been very useful, their application to identify assay-specific signatures has been limited by the lack of appropriate methodologies. This article proposes a new and powerful PCA-based method for the identification of assay-specific gene signatures in FG studies. Results: The proposed method (PM) is unique for several reasons. First, it is the only one, to our knowledge, that uses gene contribution, a product of the loading and expression level, to obtain assay signatures. The PM develops and exploits two types of assay-specific contribution plots, which are new to the application of PCA in the FG area. The first type plots the assay-specific gene contribution against the given order of the genes and reveals variations in distribution between assay-specific gene signatures as well as outliers within assay groups indicating the degree of importance of the most dominant genes. The second type plots the contribution of each gene in ascending or descending order against a constantly increasing index. This type of plots reveals assay-specific gene signatures defined by the inflection points in the curve. In addition, sharp regions within the signature define the genes that contribute the most to the signature. We proposed and used the curvature as an appropriate metric to characterize these sharp regions, thus identifying the subset of genes contributing the most to the signature. Finally, the PM uses the full dataset to determine the final gene signature, thus eliminating the chance of gene exclusion by poor screening in earlier steps. The strengths of the PM are demonstrated using a simulation study, and two studies of real DNA microarray data – a study of classification of human tissue samples and a study of E. coli cultures with different medium formulations. Conclusion We have developed a PCA-based method that effectively identifies assay-specific signatures in ranked groups of genes from the full data set in a more efficient and simplistic procedure than current approaches. Although this work demonstrates the ability of the PM to identify assay-specific signatures in DNA microarray experiments, this approach could be useful in areas such as proteomics and metabolomics. PMID:16907975

Rollins, Derrick K; Zhai, Dongmei; Joe, Alrica L; Guidarelli, Jack W; Murarka, Abhishek; Gonzalez, Ramon

2006-01-01

420

Spatially selective photonic crystal enhanced fluorescence and application to background reduction for biomolecule detection assays  

PubMed Central

By combining photonic crystal label-free biosensor imaging with photonic crystal enhanced fluorescence, it is possible to selectively enhance the fluorescence emission from regions of the PC surface based upon the density of immobilized capture molecules. A label-free image of the capture molecules enables determination of optimal coupling conditions of the laser used for fluorescence imaging of the photonic crystal surface on a pixel-by-pixel basis, allowing maximization of fluorescence enhancement factor from regions incorporating a biomolecule capture spot and minimization of background autofluorescence from areas between capture spots. This capability significantly improves the contrast of enhanced fluorescent images, and when applied to an antibody protein microarray, provides a substantial advantage over conventional fluorescence microscopy. Using the new approach, we demonstrate detection limits as low as 0.97 pg/ml for a representative protein biomarker in buffer. PMID:22109210

Chaudhery, Vikram; Huang, Cheng-Sheng; Pokhriyal, Anusha; Polans, James; Cunningham, Brian T.

2011-01-01

421

Measuring the Cytochrome c Nitrite Reductase Activity—Practical Considerations on the Enzyme Assays  

PubMed Central

The cytochrome c nitrite reductase (ccNiR) from Desulfovibrio desulfuricans ATCC 27774 is able to reduce nitrite to ammonia in a six-electron transfer reaction. Although extensively characterized from the spectroscopic and structural points-of-view, some of its kinetic aspects are still under explored. In this work the kinetic behaviour of ccNiR has been evaluated in a systematic manner using two different spectrophotometric assays carried out in the presence of different redox mediators and a direct electrochemical approach. Solution assays have proved that the specific activity of ccNiR decreases with the reduction potential of the electronic carriers and ammonium is always the main product of nitrite reduction. The catalytic parameters were discussed on the basis of the mediator reducing power and also taking into account the location of their putative docking sites with ccNiR. Due to the fast kinetics of ccNiR, electron delivering from reduced electron donors is rate-limiting in all spectrophotometric assays, so the estimated kinetic constants are apparent only. Nevertheless, this limitation could be overcome by using a direct electrochemical approach which shows that the binding affinity for nitrite decreases whilst turnover increases with the reductive driving force. PMID:20689707

Silveira, Célia M.; Besson, Stéphane; Moura, Isabel; Moura, José J. G.; Almeida, M. Gabriela

2010-01-01

422

Novel Csbnd X⋯? halogen bonds in complexes of acetylene and its derivatives of Na and MPH3 (M = Cu, Ag, Au) with XCCF (X = Cl, Br, I)  

NASA Astrophysics Data System (ADS)

Ab initio calculations have been carried out for a variety of model systems with a T-shaped Csbnd X⋯? motif. The Csbnd X⋯? interaction of acetylene with the halogen donor molecule XCCF (X = Cl, Br, I) is invariably found to be weak with the interaction energy less than 11 kJ/mol in magnitude. Substitution of the two protons in acetylene with more electron-donating sodium atoms increases the ? electron density in the Ctbnd C bond and leads to a substantial enhancement in its interaction with the halogen donor. The calculated interaction energies increase to as much as 73 kJ/mol in the case of C2Na2-ICCF. The interaction of XCCF with a model coinage metal ethynide, H3PMCCMPH3 (M = Cu, Ag, Au), is intermediate between these two extremes, and the interaction energy is related to the nature of coinage metals. The Csbnd X⋯? halogen bonds have been analyzed with natural bond orbital, atoms in molecules, and energy decomposition.

Zhuo, Hongying; Liu, Mingjuan; Li, Qingzhong; Li, Wenzuo; Cheng, Jianbo

2014-06-01

423

Multiple Transformations of 2-Alkynyl-1,8-bis(dimethylamino)naphthalenes into Benzo[g]indoles. Pd/Cu-Dependent Switching of the Electrophilic and Nucleophilic Sites in Acetylenic Bond and a Puzzle of Porcelain Catalysis.  

PubMed

By means of Sonogashira reaction, a series of 2-alkynyl- and 2,7-dialkynyl derivatives of 1,8-bis(dimethylamino)naphthalene ("proton sponge") have been obtained from the corresponding iodides. It was disclosed that changing the reaction conditions and isolation protocol or conducting the model experiments with the authentic acetylenes results in several types of palladium- and copper-assisted heterocyclizations with the participation of the C?C bond and 1-NMe2 group. These include: (i) a cyclization into isomeric 1H-benzo[g]indoles with [1,3] migration of the N-methyl group into the newly formed pyrrole ring; (ii) a similar cyclization with a loss of the methyl group; (iii) a tandem process of cyclization into benzo[g]indoles and their subsequent 3,3'-dimerization; and (iv) a copper-catalyzed oxidative transformation into 3-aroylbenzo[g]indoles. In most cases, the reactions occur in parallel, but under certain conditions, one of the above products becomes predominant or even the only one. Remarkably, in Pd-catalyzed cyclizations i-iii, the acetylenic bond behaves as an electrophile being attacked at the ?-position by the amine nitrogen atom. In contrast, in transformation iv, the C?C bond attacks by its C? atom on the aminomethyl radical functionality N(Me)-CH2· presumably arising at copper oxidation/deprotonation of the 1-NMe2 group. Studying rearrangement i, some evidence for the porcelain catalysis was obtained. PMID:25485741

Filatova, Ekaterina A; Pozharskii, Alexander F; Gulevskaya, Anna V; Ozeryanskii, Valery A

2015-01-16

424

Associative N 2 -fixation in plants growing in saline sodic soils and its relative quantification based on 15 N natural abundance  

Microsoft Academic Search

Saline-sodie soils are characterized by a very low nitrogen and organic matter content and thus are practically non fertile. However under these conditions, certain plants have been found to grow luxuriantly. One of such plants,Leptochloa fusca (Kallar grass) has exhibited nitrogenase activity associated with its roots as determined by acetylene reduction assay (ARA). Quantification of such nitrogen fixation was also

K. A. Malik; Rakhshanda Bilal; G. Rasul; K. Mahmood; M. I. Sajjad

1991-01-01

425

Dinitrogen (C 2 H 2 ) fixation in relation to nitrogen fertilization of grey alder [ Alnus incana (L.) Moench.] plantations in a peat bog  

Microsoft Academic Search

Nitrogenase activity was measured in young grey alder plantations in a peat bog in central Sweden. The stands were treated in three ways: (1) daily irrigation during the growing season with a complete nutrient solution, including N; (2) application of bark ash or wood ash before planting; and (3) fertilization every second year with solid PK fertilizers. Acetylene reduction assays

L. Rytter; A. S. Arveby; U. Granhall

1991-01-01

426

Ecological aspects of nitrogen fixation by Purshia tridentata  

Microsoft Academic Search

This study examines several aspects of nitrogen fixation by Purshia tridentata (Pursh) D.C., a rosaceous shrub widespread in the Central Oregon pumice region, especially as an understory species in Pinus ponderosa and Pinus contorta forests. Acetylene reduction was used to assay nodule activity in both field and greenhouse plants. The maximum rates were observed at 20°C, although summer soil temperatures

David A. Dalton; Donald B. Zobel

1977-01-01

427

Effect of various Rhizobium trifolii strains on nitrogenase (C 2 H 2 ) activity profiles of red clover ( Trifolium pratense cv. Venla)  

Microsoft Academic Search

The effect of variousRhizobium trifolii strains on the nitrogenase activity profiles of red clover (Trifolium pratense cv. Venla) was studied in greenhouse and field experiments. The nitrogenase activity of nodulated roots or whole plants was measured with the acetylene reduction assay at different stages of plant growth. The mean nitrogenase activity followed plant shoot growth rate from the time when

Kristina Lindström

1984-01-01

428

Population of aerobic heterotrophic nitrogen-fixing bacteria associated with wetland and dryland rice  

Microsoft Academic Search

Nitrogen-fixing activity and populations of nitrogen-fixing bacteria associated with two varieties of rice grown in dryland and wetland conditions were measured at various growth stages during the dry season. Acetylene reduction activities were measured both in the field and for the hydroponically grown rice, which was transferred from the field to water culture 1 day before assay. The activities measured

W. L. Barraquio; M. R. De Guzman; M. Barrion; I. Watanahe

1982-01-01

429

Nitrogen fixation in coarse woody debris of Thuja plicata and Tsuga heterophylla forests on northern Vancouver Island  

Microsoft Academic Search

Asymbiotic nitrogenase activity in coarse woody debris was measured using the acetylene reduction assay un- der ambient conditions in three different stand ages (5, 53, and 88 years old) of an unmanaged second-growth Tsuga heterophylla (Raf.) Sarg. - Abies amabilis (Dougl. ex Loud.) Dougl. ex J. Forbes forest type and a Thuja plicata Donn. ex D. Don - Tsuga heterophylla

Andreas Brunner; J. P. Kimmins

2003-01-01

430

Nitrogen fixation, biomass production, and nutrient uptake by annual Sesbania species in an alkaline soil  

Microsoft Academic Search

In three field trials conducted during the summer season of 1986, 1987 and 1989 in an alkaline soil, 17 accessions of annual Sesbania spp. were evaluated for nodulation, N2 fixation (acetylene reduction assay), dry weight of roots and shoots, woody biomass production, and nutrient uptake. At 50 days after sowing all the accessions were effectively nodulated (average 36.4 root nodules

D. L. N. Rao; H. S. Gill

1993-01-01

431

Nuclear Resonance Fluorescence for Materials Assay  

SciTech Connect

This paper discusses the use of nuclear resonance fluorescence (NRF) techniques for the isotopic and quantitative assaying of radioactive material. Potential applications include age-dating of an unknown radioactive source, pre- and post-detonation nuclear forensics, and safeguards for nuclear fuel cycles Examples of age-dating a strong radioactive source and assaying a spent fuel pin are discussed. The modeling work has ben performed with the Monte Carlo radiation transport computer code MCNPX, and the capability to simulate NRF has bee added to the code. Discussed are the limitations in MCNPX?s photon transport physics for accurately describing photon scattering processes that are important contributions to the background and impact the applicability of the NRF assay technique.

Quiter, Brian J.; Ludewigt, Bernhard; Mozin, Vladimir; Prussin, Stanley

2009-06-29

432

Nuclear Resonance Fluorescence for Materials Assay  

SciTech Connect

This paper discusses the use of nuclear resonance fluorescence (NRF) techniques for the isotopic and quantitative assaying of radioactive material. Potential applications include age-dating of an unknown radioactive source, pre- and post-detonation nuclear forensics, and safeguards for nuclear fuel cycles Examples of age-dating a strong radioactive source and assaying a spent fuel pin are discussed. The modeling work has ben performed with the Monte Carlo radiation transport computer code MCNPX, and the capability to simulate NRF has bee added to the code. Discussed are the limitations in MCNPX's photon transport physics for accurately describing photon scattering processes that are important contributions to the background and impact the applicability of the NRF assay technique.

Quiter, Brian; Ludewigt, Bernhard; Mozin, Vladimir; Prussin, Stanley

2009-06-05

433

Microfluid Innovations AssayMarkTM Programmable Assay System IMPACT STATEMENT  

E-print Network

in software. System Overview The AssayMark System includes a patent-pending runtime system, instruction that empowers life scientists to write a few simple lines of code that result in complex processes. Control up mode allows assay pause, resume and manual step advance -Speed control -Manual mode allows individual

Ginzel, Matthew

434

Development of an improved microneutralization assay for respiratory syncytial virus by automated plaque counting using imaging analysis  

Microsoft Academic Search

BACKGROUND: Respiratory syncytial virus (RSV) is the major cause of lower respiratory tract infection in infants and young children. Although several experimental RSV vaccines are under investigation, immuno therapy is the only treatment currently available. In assessing the immunogenicity of various vaccine formulations, a plaque reduction neutralization assay for the evaluation of RSV neutralizing antibody has been widely used. The

Edyta Zielinska; Daiqing Liu; Hong-Yin Wu; Jorge Quiroz; Ruth Rappaport; Da-Ping Yang

2005-01-01

435

In vitro assay for sex pheromone biosynthesis by the female yellow mealworm beetle and identification of a regulated step.  

PubMed

Several pheromones are known to be involved in mediating the mating behavior of the yellow mealworm beetle, Tenebrio molitor (Coleoptera: Tenebrionidae). The only sex pheromone that has been identified to date in this species is the female-produced male attractant, 4-methylnonanol (MNol). The objective of this study was to develop an in vitro assay for the last biosynthetic step involved in MNol biosynthesis, the reduction of 4-methylnonanoic acid (MNA) to the corresponding pheromone product. In vitro assays were conducted by adding appropriate cofactors and radioactively labelled precursor. Radioactive pheromone product was separated from the radioactive precursor by column chromatography, and quantified through scintillation counting. The conversion of MNA to MNol was observed, and was comparable to that observed in vivo using the same radiolabelled substrate. In both the in vivo and in vitro assays, the (3)H-MNA was also converted to a nonpolar product, tentatively identified as a triacylglyerol (TAG) derivative. The reduction of (3)H-MNA to pheromone proceeded through the coenzyme A intermediate. Mature females reduced significantly more precursor to pheromone than the immature females and the males, both in vivo and in vitro, indicating that the reduction of MNA to MNol is a regulated step involved in pheromone production. Using the in vitro assay reported herein, studies are ongoing in our lab to purify and characterize the enzyme catalyzing the reduction. PMID:16651187

Mangat, Jaswinder; Langedock, Colin; Vanderwel, Désirée

2006-05-01

436

Forests and Poverty Reduction  

NSDL National Science Digital Library

"Close to 1.6 billion people - more than 25% of the world's population - rely on forest resources for their livelihoods and most of them (1.2 billion) use trees on farms to generate food and cash." Despite these figures, the Food and Agriculture Organization of the United Nations explains that data on these vital forest resources is "sketchy or not available." On the left hand side of the page visitors will find several interesting links including the FAO website which addresses the topic of forests and poverty reduction, the FAO forestry site which includes recent events and news topics, "Publications", information on "Workshops", and "Forestry and Poverty Reduction Strategies".

437

REDUCTIONS WITHOUT REGRET: SUMMARY  

SciTech Connect

This paper briefly summarizes the series in which we consider the possibilities for losing, or compromising, key capabilities of the U.S. nuclear force in the face of modernization and reductions. The first of the three papers takes an historical perspective, considering capabilities that were eliminated in past force reductions. The second paper is our attempt to define the needed capabilities looking forward in the context of the current framework for force modernization and the current picture of the evolving challenges of deterrence and assurance. The third paper then provides an example for each of our undesirable outcomes: the creation of roach motels, box canyons, and wrong turns.

Swegle, J.; Tincher, D.

2013-09-16

438

Stress and stress reduction.  

PubMed

Chronic stress contributes to preterm birth (PTB), through direct physiological mechanisms or behavioral pathways. This review identified interventions to prevent PTB through decreased maternal stress. Studies were grouped according to intervention: group prenatal care (11 studies), care coordination (8 studies), health insurance expansion (4 studies), expanded prenatal education/support in the clinic (8 studies), home visitation (9 studies), telephone contact (2 studies), or stress-reduction strategies (5 studies). Group prenatal care had the most evidence for PTB prevention. Comparative studies of PTB prevention through different models of prenatal care and maternal support, education, empowerment, stress-reduction, and coping strategies are needed. PMID:24979355

Straub, Heather; Qadir, Sameen; Miller, Greg; Borders, Ann

2014-09-01

439

Discrete reductive perturbation technique  

SciTech Connect

We expand a partial difference equation (P{delta}E) on multiple lattices and obtain the P{delta}E which governs its far field behavior. The perturbative-reductive approach is here performed on well-known nonlinear P{delta}Es, both integrable and nonintegrable. We study the cases of the lattice modified Korteweg-de Vries (mKdV) equation, the Hietarinta equation, the lattice Volterra-Kac-Van Moerbeke equation and a nonintegrable lattice KdV equation. Such reductions allow us to obtain many new P{delta}Es of the nonlinear Schroedinger type.

Levi, Decio; Petrera, Matteo [Dipartimento di Ingegneria Elettronica, Universita degli Studi Roma Tre and Sezione INFN, Roma Tre, Via della Vasca Navale 84, 00146 Rome (Italy); Dipartimento di Fisica E. Amaldi, Universita degli Studi di Roma Tre and Sezione INFN, Roma Tre, Via della Vasca Navale 84, 00146 Rome (Italy)

2006-04-15

440

Rapid microplate assay for superoxide scavenging efficiency  

Microsoft Academic Search

Here we report a method to determine superoxide scavenging efficiency, using kinetic analysis of cytochrome c reduction and an automated UV\\/vis microtiter plate reader. Superoxide (O2?) was generated by xanthine oxidase metabolism of hypoxanthine, and quantified by following reduction of cytochrome c by O2? as increasing absorbance at 550 nm. Reaction conditions were established that provided a linear increase in

Kevin L. Quick; Joshua I. Hardt; Laura L. Dugan

2000-01-01

441

Assay of low-level plutonium effluents  

SciTech Connect

In the plutonium recovery section at the Los Alamos National Laboratory, an effluent solution is generated that contains low plutonium concentration and relatively high americium concentration. Nondestructive assay of this solution is demonstrated by measuring the passive L x-rays following alpha decay. Preliminary results indicate that an average deviation of 30% between L x-ray and alpha counting can be achieved for plutonium concentrations above 10 mg/L and Am/Pu ratios of up to 3; for plutonium concentrations less than 10 mg/L, the average deviation is 40%. The sensitivity of the L x-ray assay is approx. 1 mg Pu/L.

Hsue, S.T.; Hsue, F.; Bowersox, D.F.

1981-01-01

442

Enhanced Reverse Transcription-PCR Assay for Detection of Norovirus Genogroup I  

PubMed Central

We have developed a one-tube reverse transcription (RT)-PCR method using the real-time TaqMan PCR system for the detection of norovirus genogroup I (NV GGI). By introduction of a novel probe based on locked nucleic acid technology, we enhanced the sensitivity of the assay compared to those of conventional TaqMan probes. The sensitivity of the NV GGI RT-PCR was determined by probit analysis with defined RNA standards and quantified norovirus isolates to 711 copies/ml (95% detection limit). In order to detect PCR inhibition, we included a heterologous internal control (IC) system based on phage MS2. This internally controlled RT-PCR was tested on different real-time PCR platforms, LightCycler, Rotorgene, Mastercycler EP realplex, and ABI Prism. Compared to the assay without an IC, the duplex RT-PCR exhibited no reduction in sensitivity in clinical samples. In combination with an established NV GGII real-time RT-PCR, we used the novel assay in a routine assay for diagnosis of clinical and food-borne norovirus infection. We applied this novel assay to analyze outbreaks of nonbacterial acute gastroenteritis. Norovirus of GGI was detected in these outbreaks. Sequence and similarity plot analysis of open reading frame 1 (ORF1) and ORF2 showed two genotypes, GGI/2 and GGI/4, in semiclosed communities. PMID:16891482

Dreier, Jens; Störmer, Melanie; Mäde, Dietrich; Burkhardt, Sabine; Kleesiek, Knut

2006-01-01

443

Automatic on-chip RNA-DNA hybridization assay with integrated phase change microvalves  

NASA Astrophysics Data System (ADS)

An RNA-DNA hybridization assay microfluidic chip integrated with electrothermally actuated phase change microvalves for detecting pathogenic bacteria is presented in this paper. In order to realize the sequential loading and washing processes required in such an assay, gravity-based pressure-driven flow and phase-change microvalves were used in the microfluidic chip. Paraffin wax was used as the phase change material in the valves and thin film heaters were used to electrothermally actuate microvalves. Light absorption measured by a photodetector to determine the concentrations of the samples. The automatic control of the complete assay was implemented by a self-coded LabVIEW program. To examine the performance of this chip, Salmonella was used as a sample pathogen. Significantly, reduction in reagent/sample consumption (up to 20 folds) was achieved by this on-chip assay, compared with using the commercial test kit following the same protocol in conventional labs. The experimental results show that the quantitative detection can be obtained in approximately 26 min, and the detection limit is as low as 103 CFU ml-1. This RNA-DNA hybridization assay microfluidic chip shows an excellent potential in the development of a portable device for point-of-testing applications.

Weng, Xuan; Jiang, Hai; Wang, Junsheng; Chen, Shu; Cao, Honghe; Li, Dongqing

2012-07-01

444

Rapid assay for insect juvenile hormone esterase activity  

Microsoft Academic Search

A rapid new assay is proposed for analyzing insect juvenile hormone esterase activity. The assay is based on >99% of radiolabeled juvenile hormone being extracted into an isooctane phase while >99% of the juvenile hormone acid remains in the basic aqueous-methanol phase. The assay is more rapid and less expensive than conventional chromatographic assays while yielding almost identical values of

B. D. Hammock; T. C. Sparks

1977-01-01

445

Economics of Grade Reduction  

E-print Network

A Study of the General Principles of the Economics to Be Effected By the Reduction of Grades, the Elimination of Rise and Fall and Curvature, and the Bettering of the Other Physical Condition on the ST. Louis & San Francisco Railroad Lines....

Neff, Paul J.

1914-02-10

446

Financing Class Size Reduction  

ERIC Educational Resources Information Center

Class size reduction has been shown to, among other things, improve academic achievement for all students and particularly for low-income and minority students. With the No Child Left Behind Act's heavy emphasis on scientifically based research, adequate yearly progress, and disaggregated results, one wonders why all children aren't enrolled in…

Achilles, C. M.

2005-01-01

447

Final reduction gear apparatus  

Microsoft Academic Search

A final reduction gear apparatus is described comprising: a differential carrier which houses a gear assembly; an oil seal attached to a side gear shaft opening in the differential carrier, the oil seal having a main lip which may contact a periphery of a side gear shaft; and a guide member located outside of the oil seal at the side

Y. Yasui; H. Hori

1987-01-01

448

Campus Ecology: Waste Reduction  

NSDL National Science Digital Library

This website showcases recycling and waste reduction projects from over 40 college campuses across the US. These activities involve a wide array of materials, ranging from common recyclables, to food and yard trimmings, construction debris and laboratory chemicals. The site has links to resources for how to start your own project and includes several ways to take action.

Federation, National W.

449

Bacillus Spore Inactivation Methods Affect Detection Assays  

Microsoft Academic Search

Detection of biological weapons is a primary concern in force protection, treaty verification, and safeguard- ing civilian populations against domestic terrorism. One great concern is the detection of Bacillus anthracis, the causative agent of anthrax. Assays for detection in the laboratory often employ inactivated preparations of spores or nonpathogenic simulants. This study uses several common biodetection platforms to detect B.

JESSICA L. DANG; KAREN HEROUX; JOHN KEARNEY; AMENEH ARASTEH; MARK GOSTOMSKI; PETER A. EMANUEL

2001-01-01

450

Sample & Assay Technologies Ni-NTA Superflow  

E-print Network

.) Benzonase® Nuclease is manufactured by Merck KGaA and its affiliates. The technology is covered by US PatentMarch 2007 Sample & Assay Technologies Ni-NTA Superflow Cartridge Handbook For manual or FPLCTM Compositions 25 Appendix B: Cleaning and Regeneration of Ni-NTA Superflow Cartridges 27 #12;4 Ni-NTA Superflow

Lebendiker, Mario

451

Whole worm glycerol assay Reagents needed  

E-print Network

Whole worm glycerol assay Reagents needed: 1. Dry Ice 2. Mortar and pestles 3. 1N Perchloric acid-biopharm) Protocol 1. Wash worms off plates w/ M9 (make sure osmolarity matches that of plate) 2. Wash twice 3. Resuspend worm pellet in 10 ml M9 and allow worms to evacuate bacteria for 15 minutes. 4. While worms

Lamitina, Todd

452

Cell death assays for drug discovery  

Microsoft Academic Search

Cell death has an important role in many human diseases, and strategies aimed at modulating the associated pathways have been successfully applied to treat various disorders. Indeed, several clinically promising cytotoxic and cytoprotective agents with potential applications in cancer, ischaemic and neurodegenerative diseases have recently been identified by high-throughput screening (HTS), based on appropriate cell death assays. Given that different

Oliver Kepp; Lorenzo Galluzzi; Marta Lipinski; Junying Yuan; Guido Kroemer

2011-01-01

453

Adaptive Active Classification of Cell Assay Images  

E-print Network

Adaptive Active Classification of Cell Assay Images Nicolas Cebron and Michael R. Berthold ALTANA propose a new adaptive active classification scheme which estab- lishes ties between the two opposing concepts of unsupervised clustering of the underlying data and the supervised task of classification. Based

Reiterer, Harald

454

Automated Protein Assay Using Flow Injection Analysis  

Microsoft Academic Search

The technique of flow injection analysis (FIA) is a common instrumental method used in detecting a variety of chemical and biological agents. This paper describes an undergraduate laboratory that uses FIA to perform a bicinchoninic acid (BCA) colorimetric assay for quantitating protein samples. The method requires less than 2 min per sample injection and gives a response over a broad

Carrie A. C. Wolfe; Matthew R. Oates; David S. Hage

1998-01-01

455

Assay for Angiotensin-Converting Enzyme.  

ERIC Educational Resources Information Center

Describes a three-hour experiment designed to introduce students to chemistry of the angiotensis-converting enzyme, illustrate design of a quenched fluorescence substrate, and examine considerations necessary in designing a clinical assay. Includes background information on the biochemistry of hypertension, reagents/materials needed, procedures…

Russo, Salvatore F.

1983-01-01

456

Three-dimensional colorimetric assay assemblies  

DOEpatents

A direct assay is described using novel three-dimensional polymeric assemblies which change from a blue to red color when exposed to an analyte, in one case a flue virus. The assemblies are typically in the form of liposomes which can be maintained in a suspension, and show great intensity in their color changes. Their method of production is also described.

Charych, Deborah (Albany, CA); Reichert, Anke (Albany, CA)

2001-01-01

457

DEVELOPMENT OF AN 'IN VITRO' NEUROTOXICITY ASSAY  

EPA Science Inventory

The aim of this research project was to investigate the possibility of developing the neurotoxic esterase (NTE) assay into a totally in vitro system to enable neurotoxicity assessment to be carried out rapidly on large numbers of compounds. The purified enzyme was to be immobiliz...

458

A versatile electrowetting-based digital microfluidic platform for quantitative homogeneous and heterogeneous bio-assays  

NASA Astrophysics Data System (ADS)

Electrowetting-on-dielectric (EWOD) lab-on-a-chip systems have already proven their potential within a broad range of bio-assays. Nevertheless, research on the analytical performance of those systems is limited, yet crucial for a further breakthrough in the diagnostic field. Therefore, this paper presents the intrinsic possibilities of an EWOD lab-on-a-chip as a versatile platform for homogeneous and heterogeneous bio-assays with high analytical performance. Both droplet dispensing and splitting cause variations in droplet size, thereby directly influencing the assay's performance. The extent to which they influence the performance is assessed by a theoretical sensitivity analysis, which allows the definition of a basic framework for the reduction of droplet size variability. Taking advantage of the optimized droplet manipulations, both homogeneous and heterogeneous bio-assays are implemented in the EWOD lab-on-a-chip to demonstrate the analytical capabilities and versatility of the device. A fully on-chip enzymatic assay is realized with high analytical performance. It demonstrates the promising capabilities of an EWOD lab-on-a-chip in food-related and medical applications, such as nutritional and blood analyses. Further, a magnetic bio-assay for IgE detection using superparamagnetic nanoparticles is presented whereby the nanoparticles are used as solid carriers during the bio-assay. Crucial elements are the precise manipulation of the superparamagnetic nanoparticles with respect to dispensing and separation. Although the principle of using nano-carriers is demonstrated for protein detection, it can be easily extended to a broader range of bio-related applications like DNA sensing. In heterogeneous bio-assays the chip surface is actively involved during the execution of the bio-assay. Through immobilization of specific biological compounds like DNA, proteins and cells a reactive chip surface is realized, which enhances the bio-assay performance. To demonstrate this potential, on-chip adhesion islands are fabricated to immobilize MCF-7 human breast cancer cells. Viability studies are performed to assess the functionalization efficiency.

Vergauwe, Nicolas; Witters, Daan; Ceyssens, Frederik; Vermeir, Steven; Verbruggen, Bert; Puers, Robert; Lammertyn, Jeroen

2011-05-01

459

Nitrogenase Activity (Acetylene Reduction) of Root-Associated, Cold-Climate Azospirillum, Enterobacter, Klebsiella, and Pseudomonas Species During Growth on Various Carbon Sources and at Various Partial Pressures of Oxygen  

PubMed Central

A comprehensive view of the diazotrophic bacterial flora of plants requires that attention be paid to the appropriate carbon and oxygen requirements during isolation of the bacteria. Twenty compounds (monosaccharides, disaccharides, polyols, and organic acids) were therefore examined as carbon and energy sources for nitrogenase activity in semisolid stab cultures at pO2 values of 0.21, 0.02, and ?0.002 with 12 strains of diazotrophic root-associated bacteria. With the facultatively anaerobic bacteria of the genera Klebsiella and Enterobacter, the best substrate was sucrose, followed by fructose and mannitol, whereas among the organic acids, only malic and fumaric acids supported any activity. With the obligately aerobic bacteria of the genera Azospirillum and Pseudomonas, disaccharides were not utilized for nitrogen fixation, but several organic acids were accepted in addition to monosaccharides and polyols; malate and glucose were the best substrates. The patterns of the carbon sources utilized for nitrogen fixation were coherent within the species, with the exception of one Klebsiella pneumoniae and one Enterobacter agglomerans strain, both isolated from the same individual grass plant, which were unable to utilize lactose. Anaerobic conditions (pO2 value of ?0.002) were required for maximum nitrogenase activity with the facultatively anaerobic bacteria, with the exception of one strain of E. agglomerans, which required atmospheric oxygen (pO2 value of 0.21). Also, the obligately aerobic diazotrophs required atmospheric oxygen for maximum nitrogenase activity. The maximum specific nitrogenase activities (expressed as micromoles of C2H4 · milligram of bacterial protein?1 · hour?1) noted during the exponential growth phase of the bacteria were the following: 2.68 with Azospirillum lipoferum on malate, 2.41 with K. pneumoniae and 1.58 with E. agglomerans on sucrose, and 0.95 with Pseudomonas sp. on malate. PMID:16346205

Haahtela, Kielo; Kari, Kirsti; Sundman, Veronica

1983-01-01

460

Research highlights: digital assays on chip.  

PubMed

The ability to break up a volume of fluid into smaller pieces that are confined or separated to prevent molecular communication/transport is a key capability intrinsic to microfluidic systems. This capability has been used to develop or implement digital versions of traditional molecular analysis assays, including digital PCR and digital immunoassays/ELISA. In these digital versions, the concentration of the target analyte is in a range such that, when sampled into smaller fluid volumes, either a single molecule or no molecule may be present. Subsequent amplification is sensitive enough to obtain a digital readout of the presence of these target molecules. Advantages of such approaches that are claimed include quantification without calibration and robustness to variations in reaction conditions or times because the digital readout is less sensitive to absolute signal intensity levels. Weaknesses of digital approaches include a lower dynamic range of concentrations over which the assay is sensitive, which depends on the total volume that can be analyzed. We highlight recent efforts to expand the dynamic range of digital assays based on exploiting reaction/diffusion phenomena. A side-by-side study that evaluates the strengths of digital assays reveals that the majority of these claims are supported, with specific caveats. Finally, we highlight approaches to apply digital assays to analyze new types of reactions, including the active transport of protons across membranes by ATPases at the single protein level - perhaps opening up new biophysical understanding and screening opportunities, similar to widely deployed single-molecule ion channel analysis. PMID:25410901

Kim, Donghyuk; Wei, Qingshan; Kong, Janay Elise; Ozcan, Aydogan; Di Carlo, Dino

2015-01-01

461

Production and assay of forskolin antibodies  

SciTech Connect

Forskolin (Fo), a cardiovascular active diterpene of plant origin, has been widely used as a research tool in regulation of the catalytic activity of adenylate cyclase (AC). A linear relationship of Fo binding to plasma membrane with activation of AC has been reported. The present abstract describes the production and assay of Fo antibodies (AB). 7-0-Hemisuccinyl-7-deacetyl Fo, coupled to either human serum albumin or goat IgG, was injected into goats to elicit AB to Fo haptan. AB to Fo in antiserum or an isolated IgG fraction was tested by two assay methods, a radioimmunoassay using /sup 3/H-Fo as a tracer and a colorimetric enzyme-linked immunosorbent assay (ELISA) using horse radish peroxidase-rabbit anti goat IgG as indicator. The titers for Fo antiserum were 4000-10,000. In the defined ass