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PubMed2002

Vortex-enhanced capture of airborne particulates.

The study reported here sought to exploit aeroelastically-generated vortices for enhanced capture of airborne particles by horizontal, flat plate collectors. Elastically-supported bluff bodies of different cross-sections were screened for suitable plunge (transverse) oscillation at air velocities ranging from about 1 to 10 m s(-1). Both "D" shapes and trapezoidal prisms proved to be particularly effective; the "D" provided an increase in particle capture of 64% relative to the undisturbed flow over a flat plate at a mean air speed of 1.5 m s(-1). At higher velocities, a "T" shaped cross-section (producing mainly torsional oscillation) was found to be extremely effective at increasing capture for airborne particles with a mean diameter of 8 microm. Dynamic pressure measurements made downstream from the oscillators revealed that the torsional oscillation of the "T" produced a flow with multiple periodicities, whereas the plunge oscillators produced a wake that was more sharply periodic. These results indicate that aeroelastically intensified vortices, generated at Reynolds numbers ranging from about 2300 to 5200, can significantly improve particle removal from air streams. Furthermore, the effect can be exploited in both internal (duct) and external (free) flows.

Air Movements↗

PubMed2006

Estimating prevalence of injecting drug use: a comparison of multiplier and capture-recapture methods in cities in England and Russia.

We consider the question of what method should be recommended to estimate the prevalence of injecting drug use (IDU); and compare multiplier and capture-recapture (CRC) methods of estimating prevalence of injecting drug use (IDU). The prevalence of injecting drug use in four cities (Brighton, Liverpool, London and Togliatti) was estimated using similar methods: covariate capture-recapture (CRC) and multipliers. The multipliers, generated either from a community recruited survey or historical/literature-based, were applied to a range of 'benchmarks': specialist drug treatment, arrests, accident and emergency department (A&E), syringe exchange, HIV tests and opiate overdose deaths. The CRC estimates were assumed to be 'preferred/gold standard' [2,304 (95% confidence interval 1,514 - 3,737) in Brighton, 2,910 (2,546 - 4,977) in Liverpool, 16,782 (13,793 - 21,620) in 12 London boroughs and 15,039 (12,696 - 18,515) male IDU in Togliatti]. The ranges given by the multiplier estimates obtained through the community survey varied from 200 to 770 in Brighton, 530 to 1,300 in Liverpool, 2,900 to 10,600 in London and 12,400 to 91,000 in Togliatti. Several multipliers gave implausible results, lower than the observed data collected for another benchmark, and in the three English cities all these multiplier estimates were below the lower 95% confidence interval of the CRC estimate. In Togliatti, only one multiplier estimate was close to the preferred CRC estimates, with the rest implausibly high. The multiplier estimates based on historical/literature multipliers also ranged widely from 390 to 4,800 for Brighton, from 1,645 to 2,800 in Liverpool, from 4,650 to 12,600 in the 12 London boroughs and 12,800 to 32,000 in Togliatti. In the three UK cities the mortality multiplier estimates were closest to the capture-recapture estimates. The study was a practical demonstration comparing a range of multiplier estimates with a single CRC study. In almost all the individual comparisons the multiplier estimates performed poorly. CRC methods should be preferred as the means of estimating numbers of drug users with multiplier methods being used with caution and only where CRC is not possible.

AIDS Serodiagnosis↗

PubMed2000

Characterization of activated carbon fiber filters for pressure drop, submicrometer particulate collection, and mercury capture.

The use of activated carbon fiber (ACF) filters for the capture of particulate matter and elemental Hg is demonstrated. The pressure drop and particle collection efficiency characteristics of the ACF filters were established at two different face velocities and for two different aerosols: spherical NaCl and combustion-generated silica particles. The clean ACF filter specific resistance was 153 kg m-2 sec-1. The experimental specific resistance for cake filtration was 1.6 x 10(6) sec-1 and 2.4 x 10(5) sec-1 for 0.5- and 1.5-micron mass median diameter particles, respectively. The resistance factor R was approximately 2, similar to that for the high-efficiency particulate air filters. There was a discrepancy in the measured particle collection efficiencies and those predicted by theory. The use of the ACF filter for elemental Hg capture was illustrated, and the breakthrough characteristic was established. The capacity of the ACF filter for Hg capture was similar to other powdered activated carbons.

Air Pollution↗

PubMed2001

Electricity from fossil fuels without CO2 emissions: assessing the costs of carbon dioxide capture and sequestration in U.S. electricity markets.

The decoupling of fossil-fueled electricity production from atmospheric CO2 emissions via CO2 capture and sequestration (CCS) is increasingly regarded as an important means of mitigating climate change at a reasonable cost. Engineering analyses of CO2 mitigation typically compare the cost of electricity for a base generation technology to that for a similar plant with CO2 capture and then compute the carbon emissions mitigated per unit of cost. It can be hard to interpret mitigation cost estimates from this plant-level approach when a consistent base technology cannot be identified. In addition, neither engineering analyses nor general equilibrium models can capture the economics of plant dispatch. A realistic assessment of the costs of carbon sequestration as an emissions abatement strategy in the electric sector therefore requires a systems-level analysis. We discuss various frameworks for computing mitigation costs and introduce a simplified model of electric sector planning. Results from a "bottom-up" engineering-economic analysis for a representative U.S. North American Electric Reliability Council (NERC) region illustrate how the penetration of CCS technologies and the dispatch of generating units vary with the price of carbon emissions and thereby determine the relationship between mitigation cost and emissions reduction.

Air Pollution↗

PubMed2006

Feasibility study of using brine for carbon dioxide capture and storage from fixed sources.

A laboratory-scale reactor was developed to evaluate the capture of carbon dioxide (CO2) from a gas into a liquid as an approach to control greenhouse gases emitted from fixed sources. CO2 at 5-50% concentrations was passed through a gas-exchange membrane and transferred into liquid media--tap water or simulated brine. When using water, capture efficiencies exceeded 50% and could be enhanced by adding base (e.g., sodium hydroxide) or the combination of base and carbonic anhydrase, a catalyst that speeds the conversion of CO2 to carbonic acid. The transferred CO2 formed ions, such as bicarbonate or carbonate, depending on the amount of base present. Adding precipitating cations, like Ca++, produced insoluble carbonate salts. Simulated brine proved nearly as efficient as water in absorbing CO2, with less than a 6% reduction in CO2 transferred. The CO2 either dissolved into the brine or formed a mixture of gas and ions. If the chemistry was favorable, carbonate precipitate spontaneously formed. Energy expenditure of pumping brine up and down from subterranean depths was modeled. We conclude that using brine in a gas-exchange membrane system for capturing CO2 from a gas stream to liquid is technically feasible and can be accomplished at a reasonable expenditure of energy.

Carbon Dioxide↗

PubMedDate not supplied

Electronic data capture (EDC)--a new mantra for clinical trials.

Pharmaceutical companies, over a period of time, have attempted to use innovative and modern technologies for quicker and more efficient methods of clinical data capture and analysis. In today's scenario, Electronic Data Capture (EDC) is considered to be the preferred technology that can provide significant benefits over existing manual methods. This article highlights the lacunae of the traditional data capture method and discusses the advantages of using EDC for better data quality, improved performance and productivity, and reduced cost in clinical trial management. It also emphasizes the need for IT infrastructure, training, and 21 CFR Part 11 compliance issues. The authors have also described the challenges to be faced by the investigators and sponsors in implementing EDC. Finally, the article concludes emphasizing the fact that EDC is the future mantra for the clinical trials and all stake holders should face challenges of infrastructure, technology, regulations, and training to make it a success.

Clinical Trials as Topic↗

PubMed1995

Sandwich capture enzyme immunoassay for water soluble blood group B substance in secretor saliva.

Sandwich capture enzyme immunoassays (EIA I and EIA II) are described. Water soluble B substance was reacted simultaneously with affinity-purified dinitrophenyl goat anti-B IgG and affinity-purified goat anti-B IgG-peroxidase conjugate. The complex formed of B substance, dinitrophenyl IgG and IgG-peroxidase conjugate was trapped onto a polystyrene ball coated with affinity-purified goat anti-dinitrophenyl bovine serum albumin IgG. After washing, peroxidase activity bound to the ball was assayed by fluorometry (the sandwich capture EIA I). In the sandwich capture EIA II, the complex was, after thorough washing, eluted from the ball with dinitrophenyl-L-lysine, and then peroxidase activity in the eluate was assayed. The thorough washing and elution processes improved the sensitivity 3.3-fold, and B substance in saliva samples from type B and AB secretors could be detected 200- to 500-fold more sensitively than hemagglutination inhibition, a method commonly used in forensic practices.

ABO Blood-Group System↗

PubMed2004

Use of 19F-nuclear magnetic resonance and gas chromatography-electron capture detection in the quantitative analysis of fluorine-containing metabolites in urine of sevoflurane-anaesthetized patients.

1: The use of fluorine-19 nuclear magnetic resonance (19F-NMR) and gas chromatography-electron capture detection (GC-ECD) in the analysis of fluorine-containing products in the urine of sevoflurane-exposed patients was explored. 2: Ten patients were anaesthetized by sevoflurane for 135-660 min at a flow rate of 6 l min(-1). Urine samples were collected before, directly after and 24 h after discontinuation of anaesthesia. 3: 19F-NMR analysis of the urines showed the presence of several fluorine-containing metabolites. The main oxidative metabolite, hexafluoroisopropanol (HFIP)-glucuronide, showed two strong quartet signals in the 19F-NMR spectrum. HFIP concentrations after beta-glucuronidase treatment were quantified by (19)F-nuclear magnetic resonance. Concentrations directly after and 24 h after discontinuation of anaesthesia were 131 +/- 41 (mean +/- SEM) and 61 +/- 19 mol mg(-1) creatinine, respectively. Urinary HFIP excretions correlated with sevoflurane exposure. 4: Longer scanning times enabled the measurement of signals from two compound A-derived metabolites, i.e. compound A mercapturic acid I (CAMA-I) and compound A mercapturic acid II (CAMA-II), as well as products from beta-lyase activation of the respective cysteine conjugates of compound A. The signals of the mercapturic acids, 3,3,3-trifluoro-2-(fluoromethoxy)-propanoic acid and 3,3,3-trifluorolactic acid were visible after combining and concentrating the patient urines. CAMA-I and -II excretions in patients were completed after 24 h. 5: Since 19F-nuclear magnetic resonance is not sensitive enough, urinary mercapturic acids concentrations were quantified by gas chromatography-electron capture detection. CAMA-I and -II urinary concentrations were 2.3 +/- 0.7 and 1.4 +/- 0.4 mol mg(-1) creatinine, respectively. Urinary excretion of CAMA-I showed a correlation with sevoflurane exposure, whereas CAMA-II did not. 6. The results show that 19F-nuclear magnetic resonance is a very selective and convenient technique to detect and quantify HFIP in non-concentrated human urine. 19F-nuclear magnetic resonance can also be used to monitor the oxidative biotransformation of sevoflurane in anaesthetized patients. Compound A-derived mercapturic acids and 3,3,3-trifluoro-2-(fluoromethoxy)-propanoic acid and 3,3,3-trifluorolactic acid, however, require more sensitive techniques such as gas chromatography-electron capture detection and/or gas chromatography-mass spectrometry for quantification.

Anesthesia, Inhalation↗

PubMed2005

Influence of the washing buffer composition on the sensitivity of an enzyme-linked immunosorbent assay using mycobacterial glycolipids as capture antigens.

Immunogenic glycolipids from the cell wall of Mycobacterium tuberculosis are potential capture antigens in enzyme-linked immunosorbent assays (ELISAs) for the serodiagnostis of tuberculosis. Typically, washing steps in ELISAs are performed with buffers containing a detergent. However, Tween-20, the most commonly added detergent, was reported to be able to remove the coating of certain glycolipid antigens from microtitre wells. In order to determine the influence of the washing buffer composition on the results, we measured serum immunoglobulin G (IgG) against three mycobacterial glycolipids by ELISA, conducting three separate experiments with three different buffers: Tris-buffered saline (TBS), TBS plus 0.02% Tween-20 (TBS-Tween), or TBS plus 0.3% bovine serum albumin (TBS-BSA). The capture antigens applied were lipoarabinomannan with the basic arabinose-containing motif (AraLAM), the mannose-capped version of lipoarabinomannan (ManLAM), and trehalose-6,6'-dimycolate (cord factor). All ELISAs achieved acceptable specificities around 95%. The sensitivities, however, varied widely, depending upon the sort of washing buffer used. In 38 patients with sputum smear-positive pulmonary tuberculosis and control groups of 79 patients with non-tuberculosis lung disease and 92 healthy volunteers, the anti-cord factor ELISA achieved 100%, 31.6%, and 60.5% with TBS, TBS-Tween, and TBS-BSA, respectively. Corresponding sensitivity values for AraLAM were 39.5%, 26.3%, and 23.7%, and for ManLAM 94.7%, 65.8%, and 55.3%. We conclude that Tween-20 or BSA should be omitted from the washing buffer in ELISAs, when the capture antigen is of lipid nature.

Adolescent↗

PubMed2005

PI(4,5)P2-dependent microdomain assemblies capture microtubules to promote and control leading edge motility.

The lipid second messenger PI(4,5)P(2) modulates actin dynamics, and its local accumulation at plasmalemmal microdomains (rafts) might mediate regulation of protrusive motility. However, how PI(4,5)P(2)-rich rafts regulate surface motility is not well understood. Here, we show that upon signals promoting cell surface motility, PI(4,5)P(2) directs the assembly of dynamic raft-rich plasmalemmal patches, which promote and sustain protrusive motility. The accumulation of PI(4,5)P(2) at rafts, together with Cdc42, promotes patch assembly through N-WASP. The patches exhibit locally regulated PI(4,5)P(2) turnover and reduced diffusion-mediated exchange with their environment. Patches capture microtubules (MTs) through patch IQGAP1, to stabilize MTs at the leading edge. Captured MTs in turn deliver PKA to patches to promote patch clustering through further PI(4,5)P(2) accumulation in response to cAMP. Patch clustering restricts, spatially confines, and polarizes protrusive motility. Thus, PI(4,5)P(2)-dependent raft-rich patches enhance local signaling for motility, and their assembly into clusters is regulated through captured MTs and PKA, coupling local regulation of motility to cell polarity, and organization.

Animals↗

PubMed2004

Differential contribution of Bud6p and Kar9p to microtubule capture and spindle orientation in S. cerevisiae.

In Saccharomyces cerevisiae, spindle orientation is controlled by a temporal and spatial program of microtubule (MT)-cortex interactions. This program requires Bud6p/Aip3p to direct the old pole to the bud and confine the new pole to the mother cell. Bud6p function has been linked to Kar9p, a protein guiding MTs along actin cables. Here, we show that Kar9p does not mediate Bud6p functions in spindle orientation. Based on live microscopy analysis, kar9Delta cells maintained Bud6p-dependent MT capture. Conversely, bud6Delta cells supported Kar9p-associated MT delivery to the bud. Moreover, additive phenotypes in bud6Delta kar9Delta or bud6Delta dyn1Delta mutants underscored the separate contributions of Bud6p, Kar9p, and dynein to spindle positioning. Finally, tub2C354S, a mutation decreasing MT dynamics, suppressed a kar9Delta mutation in a BUD6-dependent manner. Thus, Kar9p-independent capture at Bud6p sites can effect spindle orientation provided MT turnover is reduced. Together, these results demonstrate Bud6p function in MT capture at the cell cortex, independent of Kar9p-mediated MT delivery along actin cables.

Actins↗

PubMed2005

Microtubule capture by CENP-E silences BubR1-dependent mitotic checkpoint signaling.

The mitotic checkpoint is the major cell cycle control mechanism for maintaining chromosome content in multicellular organisms. Prevention of premature onset of anaphase requires activation at unattached kinetochores of the BubR1 kinase, which acts with other components to generate a diffusible "stop anaphase" inhibitor. Not only does direct binding of BubR1 to the centromere-associated kinesin family member CENP-E activate its essential kinase, binding of a motorless fragment of CENP-E is shown here to constitutively activate BubR1 bound at kinetochores, producing checkpoint signaling that is not silenced either by spindle microtubule capture or the tension developed at those kinetochores by other components. Using purified BubR1, microtubules, and CENP-E, microtubule capture by the CENP-E motor domain is shown to silence BubR1 kinase activity in a ternary complex of BubR1-CENP-E-microtubule. Together, this reveals that CENP-E is the signal transducing linker responsible for silencing BubR1-dependent mitotic checkpoint signaling through its capture at kinetochores of spindle microtubules.

Animals↗

PubMed2003

Antigen-capturing cells can masquerade as memory B cells.

As well as classically defined switched immunoglobulin isotype-expressing B cells, memory B cells are now thought to include IgM-expressing cells and memory cells that lack B cell lineage markers, such as B220 or CD19. We set out to compare the relative importance of memory B cell subsets with an established flow cytometry method to identify antigen-specific cells. After immunization with PE, we could detect B220+ and, as reported previously, B220- antigen-binding cells (McHeyzer-Williams, L.J., M. Cool, and M.G. McHeyzer-Williams. 2001. J. Immunol. 167:1393-1405). The B220-PE+ cells bore few markers typical of B cells, but resembled myeloid cells. Further analysis of the antigen-binding characteristics of these cells showed that, upon immunization with two fluorescent proteins, the B220- cells could bind both. Furthermore, this subpopulation was detected in RAG1-/- mice after transfer of anti-PE mouse serum. These data strongly suggest that these cells capture serum Ig, via Fc receptors, and thus appear antigen-specific. Investigation of these antigen-capturing cells in a variety of knockout mice indicates that they bind monomeric IgG in an FcgammaR1 (CD64)-dependent manner. We find no evidence of a B220- memory B cell population that is not explicable by antigen-capturing cells, and warn that care must be taken when using antigen-specificity or surface IgG as an indicator of B cell memory.

Animals↗

PubMed1988

Head phantom experiment and calculation for boron neutron capture therapy.

Head phantom experiments with various neutron beams and calculations were carried out in order to provide useful information for boron neutron capture therapy (BNCT). Thermal neutron beams for thermal neutron capture therapy were used for phantom experiments with various neutron collimator aperture sizes. The filtered beam neutrons of 24 and 144 keV generated with iron and silicon filters were also used to investigate the possible application of BNCT in the treatment of deep-seated cancers. Thermal neutron fluence and induced capture gamma dose distributions within the phantom were calculated with a transport code DOT 3.5 and compared with the experimental results. The results showed that the calculation used was consistent with the experimental results and provided useful information on BNCT. The filtered beam neutron may be very useful for the treatment of deep or widespread cancer, if there were a high power research reactor constructed for this purpose.

Brain Neoplasms↗

PubMed1995

A method for calculating the dose due to capture gamma rays in accelerator mazes.

An empirical technique for calculation of the capture gamma ray dose in the maze of high-energy medical accelerators is described. The total photon dose was measured along the maze centre line and by use of a graphical technique the capture gamma dose and the low-energy photon dose component were determined. Tenth-value lengths for both photon dose components are reported for four medical accelerators operating with megavoltages in the range 16.8-22.0 MV. The capture gamma dose and the low-energy photon dose in the maze were related to the following parameters: the room surface area, the distance from the isocentre to the inner maze entrance, and the neutron head leakage at a fixed distance from the target.

Gamma Rays↗

PubMed2004

Comparative sensitivity of the VecTest antigen-capture assay, reverse transcriptase-PCR, and cell culture for detection of West Nile virus in dead birds.

The sensitivity of the VecTest antigen-capture and RT-PCR assays were compared to brain tissue culture in Vero cells for the detection of WNV in a sample of dead birds collected in East Texas and southern Louisiana during the summer of 2003. Cell culture was used as the gold standard, because it yielded the most positives. Direct culture of brain tissue and the WNV antigen-capture assay, done on oropharyngeal swabs, gave statistically comparable results (46% and 40% positive, respectively). In contrast, RT-PCR done on brain homogenates was significantly less sensitive than direct tissue culture (33% compared to 46%, respectively). Results indicated that RT-PCR may not be consistently the most sensitive assay for detection of WNV in dead bird brain tissue and that the VecTest antigen-capture assay has a number of advantages over the other two detection techniques for routine surveillance activities.

Animals↗

PubMed2002

Kar9p-independent microtubule capture at Bud6p cortical sites primes spindle polarity before bud emergence in Saccharomyces cerevisiae.

Spindle orientation is critical for accurate chromosomal segregation in eukaryotic cells. In the yeast Saccharomyces cerevisiae, orientation of the mitotic spindle is achieved by a program of microtubule-cortex interactions coupled to spindle morphogenesis. We previously implicated Bud6p in directing microtubule capture throughout this program. Herein, we have analyzed cells coexpressing GFP:Bud6 and GFP:Tub1 fusions, providing a kinetic view of Bud6p-microtubule interactions in live cells. Surprisingly, even during the G1 phase, microtubule capture at the recent division site and the incipient bud is dictated by Bud6p. These contacts are eliminated in bud6 delta cells but are proficient in kar9 delta cells. Thus, Bud6p cues microtubule capture, as soon as a new cell polarity axis is established independent of Kar9p. Bud6p increases the duration of interactions and promotes distinct modes of cortical association within the bud and neck regions. In particular, microtubule shrinkage and growth at the cortex rarely occur away from Bud6p sites. These are the interactions selectively impaired at the bud cortex in bud6 delta cells. Finally, interactions away from Bud6p sites within the bud differ from those occurring at the mother cell cortex, pointing to the existence of an independent factor controlling cortical contacts in mother cells after bud emergence.

Anaphase↗

PubMed1995

Internal validity analysis: a method for adjusting capture-recapture estimates of prevalence.

The authors propose a method for adjusting results of log-linear multi-source capture-recapture estimates of total population. The method compares the totals in some subpopulations of known size with estimates derived from various capture-recapture approaches to these subpopulations. The authors term such an approach an "internal validity analysis". Trends in the ratios of the estimates to the known true values of these subpopulations provide a plausible indicator of the bias of some types of estimates of the total population especially when underlying assumptions of the methods used have not been met in analysis of the total population. The authors apply this method to published data on an open population of injection drug users that had been previously analyzed with a standard capture-recapture analysis as if it were a closed population. Internal validity analysis suggests that the size of this population is about 15% greater than that previously estimated.

Data Interpretation, Statistical↗