40 CFR Table 2 to Subpart Dddd of... - Model Rule-Emission Limitations

Code of Federal Regulations, 2012 CFR

2012-07-01

... part) Hydrogen chloride 62 parts per million by dry volume 3-run average (1 hour minimum sample time...) Sulfur dioxide 20 parts per million by dry volume 3-run average (1 hour minimum sample time per run...-8) or ASTM D6784-02 (Reapproved 2008).c Opacity 10 percent Three 1-hour blocks consisting of ten 6...

Optimization of Evans blue quantitation in limited rat tissue samples

PubMed Central

Wang, Hwai-Lee; Lai, Ted Weita

2014-01-01

Evans blue dye (EBD) is an inert tracer that measures plasma volume in human subjects and vascular permeability in animal models. Quantitation of EBD can be difficult when dye concentration in the sample is limited, such as when extravasated dye is measured in the blood-brain barrier (BBB) intact brain. The procedure described here used a very small volume (30 µl) per sample replicate, which enabled high-throughput measurements of the EBD concentration based on a standard 96-well plate reader. First, ethanol ensured a consistent optic path length in each well and substantially enhanced the sensitivity of EBD fluorescence spectroscopy. Second, trichloroacetic acid (TCA) removed false-positive EBD measurements as a result of biological solutes and partially extracted EBD into the supernatant. Moreover, a 1:2 volume ratio of 50% TCA ([TCA final] = 33.3%) optimally extracted EBD from the rat plasma protein-EBD complex in vitro and in vivo, and 1:2 and 1:3 weight-volume ratios of 50% TCA optimally extracted extravasated EBD from the rat brain and liver, respectively, in vivo. This procedure is particularly useful in the detection of EBD extravasation into the BBB-intact brain, but it can also be applied to detect dye extravasation into tissues where vascular permeability is less limiting. PMID:25300427

Optimization of Evans blue quantitation in limited rat tissue samples

NASA Astrophysics Data System (ADS)

Wang, Hwai-Lee; Lai, Ted Weita

2014-10-01

Evans blue dye (EBD) is an inert tracer that measures plasma volume in human subjects and vascular permeability in animal models. Quantitation of EBD can be difficult when dye concentration in the sample is limited, such as when extravasated dye is measured in the blood-brain barrier (BBB) intact brain. The procedure described here used a very small volume (30 µl) per sample replicate, which enabled high-throughput measurements of the EBD concentration based on a standard 96-well plate reader. First, ethanol ensured a consistent optic path length in each well and substantially enhanced the sensitivity of EBD fluorescence spectroscopy. Second, trichloroacetic acid (TCA) removed false-positive EBD measurements as a result of biological solutes and partially extracted EBD into the supernatant. Moreover, a 1:2 volume ratio of 50% TCA ([TCA final] = 33.3%) optimally extracted EBD from the rat plasma protein-EBD complex in vitro and in vivo, and 1:2 and 1:3 weight-volume ratios of 50% TCA optimally extracted extravasated EBD from the rat brain and liver, respectively, in vivo. This procedure is particularly useful in the detection of EBD extravasation into the BBB-intact brain, but it can also be applied to detect dye extravasation into tissues where vascular permeability is less limiting.

A High-Performance Liquid Chromatography-Based Screening Method for the Analysis of Atrazine, Alachlor, and Ten of Their Transformation Products

USGS Publications Warehouse

Schroyer, B.R.; Capel, P.D.

1996-01-01

A high-performance liquid Chromatography (HPLC) method is presented for the for the fast, quantitative analysis of the target analytes in water and in low organic-carbon, sandy soils that are known to be contaminated with the parent herbicides. Speed and ease of sample preparation was prioritized above minimizing detection limits. Soil samples were extracted using 80:20 methanol:water (volume:volume). Water samples (50 ??L) were injected directly into the HPLC without prior preparation. Method quantification limits for soil samples (10 g dry weight) and water samples ranged from 20 to 110 ng/g and from 20 to 110 ??g/L for atrazine and its transformation products and from 80 to 320 ng/g and from 80 to 320 ??g/L for alachlor and its transformation products, respectively.

Methods for the preparation and analysis of solids and suspended solids for total mercury

USGS Publications Warehouse

Olund, Shane D.; DeWild, John F.; Olson, Mark L.; Tate, Michael T.

2004-01-01

The methods documented in this report are utilized by the Wisconsin District Mercury Lab for analysis of total mercury in solids (soils and sediments) and suspended solids (isolated on filters). Separate procedures are required for the different sample types. For solids, samples are prepared by room-temperature acid digestion and oxidation with aqua regia. The samples are brought up to volume with a 5 percent bromine monochloride solution to ensure complete oxidation and heated at 50?C in an oven overnight. Samples are then analyzed with an automated flow injection system incorporating a cold vapor atomic fluorescence spectrometer. A method detection limit of 0.3 ng of mercury per digestion bomb was established using multiple analyses of an environmental sample. Based on the range of masses processed, the minimum sample reporting limit varies from 0.6 ng/g to 6 ng/g. Suspended solids samples are oxidized with a 5 percent bromine monochloride solution and held at 50?C in an oven for 5 days. The samples are then analyzed with an automated flow injection system incorporating a cold vapor atomic fluorescence spectrometer. Using a certified reference material as a surrogate for an environmental sample, a method detection limit of 0.059 ng of mercury per filter was established. The minimum sample reporting limit varies from 0.059 ng/L to 1.18 ng/L, depending on the volume of water filtered.

Ultrasensitive Detection of Shigella Species in Blood and Stool.

PubMed

Luo, Jieling; Wang, Jiapeng; Mathew, Anup S; Yau, Siu-Tung

2016-02-16

A modified immunosensing system with voltage-controlled signal amplification was used to detect Shigella in stool and blood matrixes at the single-digit CFU level. Inactivated Shigella was spiked in these matrixes and detected directly. The detection was completed in 78 min. Detection limits of 21 CFU/mL and 18 CFU/mL were achieved in stool and blood, respectively, corresponding to 2-7 CFUs immobilized on the detecting electrode. The outcome of the detection of extremely low bacterium concentration, i.e., below 100 CFU/mL, blood samples show a random nature. An analysis of the detection probabilities indicates the correlation between the sample volume and the success of detection and suggests that sample volume is critical for ultrasensitive detection of bacteria. The calculated detection limit is qualitatively in agreement with the empirically determined detection limit. The demonstrated ultrasensitive detection of Shigella on the single-digit CFU level suggests the feasibility of the direct detection of the bacterium in the samples without performing a culture.

Periodontitis is related to lung volumes and airflow limitation: a cross-sectional study.

PubMed

Holtfreter, Birte; Richter, Stefanie; Kocher, Thomas; Dörr, Marcus; Völzke, Henry; Ittermann, Till; Obst, Anne; Schäper, Christoph; John, Ulrich; Meisel, Peter; Grotevendt, Anne; Felix, Stephan B; Ewert, Ralf; Gläser, Sven

2013-12-01

This study aimed to assess the potential association of periodontal diseases with lung volumes and airflow limitation in a general adult population. Based on a representative population sample of the Study of Health in Pomerania (SHIP), 1463 subjects aged 25-86 years were included. Periodontal status was assessed by clinical attachment loss (CAL), probing depth and number of missing teeth. Lung function was measured using spirometry, body plethysmography and diffusing capacity of the lung for carbon monoxide. Linear regression models using fractional polynomials were used to assess associations between periodontal disease and lung function. Fibrinogen and high-sensitivity C-reactive protein (hs-CRP) were evaluated as potential intermediate factors. After full adjustment for potential confounders mean CAL was significantly associated with variables of mobile dynamic and static lung volumes, airflow limitation and hyperinflation (p<0.05). Including fibrinogen and hs-CRP did not change coefficients of mean CAL; associations remained statistically significant. Mean CAL was not associated with total lung capacity and diffusing capacity of the lung for carbon monoxide. Associations were confirmed for mean probing depth, extent measures of CAL/probing depth and number of missing teeth. Periodontal disease was significantly associated with reduced lung volumes and airflow limitation in this general adult population sample. Systemic inflammation did not provide a mechanism linking both diseases.

Determination of radionuclide concentrations in ground level air using the ASS-500 high volume sampler

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

Frenzel, E.; Arnold, D.; Wershofen, H.

1996-06-01

A method for determination of radionuclide concentrations in air aerosol samples collected by the high volume aerosol sampler ASS-500 was elaborated. The aerosol sampling station ASS-500 is a Stand alone, all-weather proofed instrument. It is designed for representative sampling of airborne radionuclides from ground level air at a height of about 1.5 m above ground level. The ASS-500 station enables continuous air monitoring both normal and emergency Situations. The collection of aerosols on the Petrianov FPP-15-1.5 type filter out of an air volume of about 100,000 m{sup 3} (sampling period 1 wk) or of about 250,000 m{sup 3} (sampling periodmore » 3 wk) admits accurate spectrometric low level measurements of natural and artificial radionuclides. The achieved detection limit is 0.5 {mu}Bq m{sup -3} and 0.2 {mu}Bq m{sup -3} for {sup 137}Cs, respectively. A new developed air flow Meter system allows to enhance the collected air volume to about 150,000 m{sup 3} per week and lowers the detection limit to <0.4 {mu}Bq m{sup -3} for {sup 137}Cs for weekly collected aerosol samples. In Poland the CLOR uses 9 Stations ASS-500 at different sites as atmospheric radioactivity control system. On the basis of spectrometric measurements of natural and artificial radionuclides in the collected aerosol samples at the different sites, CLOR establishes a weekly report about the radiological situation at Poland for responsible authorities. The very low achievable detection limit of the Station ASS-500 due 10 the high air flow fate and the long possible sampling period were the key argument for other government radiation protection authorities in Europe to introduce the Station ASS-500 into their low level radionuclide atmospheric monitoring programs (Austria, Belarus, France, Germany, Iceland, Spain, Switzerland, Ukraine).« less

Automatic transfer function generation for volume rendering of high-resolution x-ray 3D digital mammography images

NASA Astrophysics Data System (ADS)

Alyassin, Abdal M.

2002-05-01

3D Digital mammography (3DDM) is a new technology that provides high resolution X-ray breast tomographic data. Like any other tomographic medical imaging modalities, viewing a stack of tomographic images may require time especially if the images are of large matrix size. In addition, it may cause difficulty to conceptually construct 3D breast structures. Therefore, there is a need to readily visualize the data in 3D. However, one of the issues that hinder the usage of volume rendering (VR) is finding an automatic way to generate transfer functions that efficiently map the important diagnostic information in the data. We have developed a method that randomly samples the volume. Based on the mean and the standard deviation of these samples, the technique determines the lower limit and upper limit of a piecewise linear ramp transfer function. We have volume rendered several 3DDM data using this technique and compared visually the outcome with the result from a conventional automatic technique. The transfer function generated through the proposed technique provided superior VR images over the conventional technique. Furthermore, the improvement in the reproducibility of the transfer function correlated with the number of samples taken from the volume at the expense of the processing time.

Estimation of the rain signal in the presence of large surface clutter

NASA Technical Reports Server (NTRS)

Ahamad, Atiq; Moore, Richard K.

1994-01-01

The principal limitation for the use of a spaceborne imaging SAR as a rain radar is the surface-clutter problem. Signals may be estimated in the presence of noise by averaging large numbers of independent samples. This method was applied to obtain an estimate of the rain echo by averaging a set of N(sub c) samples of the clutter in a separate measurement and subtracting the clutter estimate from the combined estimate. The number of samples required for successful estimation (within 10-20%) for off-vertical angles of incidence appears to be prohibitively large. However, by appropriately degrading the resolution in both range and azimuth, the required number of samples can be obtained. For vertical incidence, the number of samples required for successful estimation is reasonable. In estimating the clutter it was assumed that the surface echo is the same outside the rain volume as it is within the rain volume. This may be true for the forest echo, but for convective storms over the ocean the surface echo outside the rain volume is very different from that within. It is suggested that the experiment be performed with vertical incidence over forest to overcome this limitation.

Ultimate detectability of volatile organic compounds: how much further can we reduce their ambient air sample volumes for analysis?

PubMed

Kim, Yong-Hyun; Kim, Ki-Hyun

2012-10-02

To understand the ultimately lowest detection range of volatile organic compounds (VOCs) in air, application of a high sensitivity analytical system was investigated by coupling thermal desorption (TD) technique with gas chromatography (GC) and time-of-flight (TOF) mass spectrometry (MS). The performance of the TD-GC/TOF MS system was evaluated using liquid standards of 19 target VOCs prepared in the range of 35 pg to 2.79 ng per μL. Studies were carried out using both total ion chromatogram (TIC) and extracted ion chromatogram (EIC) mode. EIC mode was used for calibration to reduce background and to improve signal-to-noise. The detectability of 19 target VOCs, if assessed in terms of method detection limit (MDL, per US EPA definition) and limit of detection (LOD), averaged 5.90 pg and 0.122 pg, respectively, with the mean coefficient of correlation (R(2)) of 0.9975. The minimum quantifiable mass of target analytes, when determined using real air samples by the TD-GC/TOF MS, is highly comparable to the detection limits determined experimentally by standard. In fact, volumes for the actual detection of the major aromatic VOCs like benzene, toluene, and xylene (BTX) in ambient air samples were as low as 1.0 mL in the 0.11-2.25 ppb range. It was thus possible to demonstrate that most target compounds including those in low abundance could be reliably quantified at concentrations down to 0.1 ppb at sample volumes of less than 10 mL. The unique sensitivity of this advanced analytical system can ultimately lead to a shift in field sampling strategy with smaller air sample volumes facilitating faster, simpler air sampling (e.g., use of gas syringes rather than the relative complexity of pumps or bags/canisters), with greatly reduced risk of analyte breakthrough and minimal interference, e.g., from atmospheric humidity. The improved detection limits offered by this system can also enhance accuracy and measurement precision.

Improved radiation dose efficiency in solution SAXS using a sheath flow sample environment

PubMed Central

Kirby, Nigel; Cowieson, Nathan; Hawley, Adrian M.; Mudie, Stephen T.; McGillivray, Duncan J.; Kusel, Michael; Samardzic-Boban, Vesna; Ryan, Timothy M.

2016-01-01

Radiation damage is a major limitation to synchrotron small-angle X-ray scattering analysis of biomacromolecules. Flowing the sample during exposure helps to reduce the problem, but its effectiveness in the laminar-flow regime is limited by slow flow velocity at the walls of sample cells. To overcome this limitation, the coflow method was developed, where the sample flows through the centre of its cell surrounded by a flow of matched buffer. The method permits an order-of-magnitude increase of X-ray incident flux before sample damage, improves measurement statistics and maintains low sample concentration limits. The method also efficiently handles sample volumes of a few microlitres, can increase sample throughput, is intrinsically resistant to capillary fouling by sample and is suited to static samples and size-exclusion chromatography applications. The method unlocks further potential of third-generation synchrotron beamlines to facilitate new and challenging applications in solution scattering. PMID:27917826

Low-Dead-Volume Inlet for Vacuum Chamber

NASA Technical Reports Server (NTRS)

Naylor, Guy; Arkin, C.

2010-01-01

Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead -volume. As a result, a high -vacuum gas inlet was developed with low dead -volume, allowing the use of a very low conductance limit interface. Gas flows through the ConFlat flange at a relatively high flow rate at orders of magnitude greater than through the conductance limit. The small flow goes through a conductance limit that is a double-sided ConFlat.

Low-Dead-Volume Inlet for Vacuum Chamber

NASA Technical Reports Server (NTRS)

Naylor, Guy; Arkin, C.

2011-01-01

Gas introduction from near-ambient pressures to high vacuum traditionally is accomplished either by multi-stage differential pumping that allows for very rapid response, or by a capillary method that allows for a simple, single-stage introduction, but which often has a delayed response. Another means to introduce the gas sample is to use the multi-stage design with only a single stage. This is accomplished by using a very small conductance limit. The problem with this method is that a small conductance limit will amplify issues associated with dead-volume. As a result, a high-vacuum gas inlet was developed with low dead-volume, allowing the use of a very low conductance limit interface. Gas flows through the ConFlat flange at a relatively high flow rate at orders of magnitude greater than through the conductance limit. The small flow goes through a conductance limit that is a double-sided ConFlat.

[Determination of short-chain chlorinated paraffins in ambient air using high-volume sampling combined with high resolutimi gas chromatography-electron capture negative ion-low resolution mass spectrometry].

PubMed

Shi, Loimeng; Gao, Yuan; Hou, Xiaohong; Zhang, Haijun; Zhang, Yichi; Chen, Jiping

2016-02-01

An analytical method for quantifying short-chain chlorinated paraffins (SCCPs) in ambient air using high-volume sampling combined with high resolution gas chromatography-electron capture negative ion-low resolution mass spectrometry ( HRGC-ECNI-LRMS) was developed. An acidified silica gel column and a basic alumina column were used to optimize the cleanup procedures. The results showed a good linearity (R2>0. 99) between the total response factors and the degree of chlorination of SCCPs in the content range of 58. 1%-63. 3%. The limits of detection (S/N ≥3) and the limits of quantification (S/N ≥ 10) were 4. 2 and 12 µg, respectively. The method detection limit (MDL) for SCCPs was 0. 34 ng/m3 (n = 7). The recoveries of SCCPs in air samples were in the range of 81. 9% to 94. 2%. It is demonstrated that the method is suitable for the quantitative analysis of SCCPs in air samples.

Amplification volume reduction on DNA database samples using FTA™ Classic Cards.

PubMed

Wong, Hang Yee; Lim, Eng Seng Simon; Tan-Siew, Wai Fun

2012-03-01

The DNA forensic community always strives towards improvements in aspects such as sensitivity, robustness, and efficacy balanced with cost efficiency. Therefore our laboratory decided to study the feasibility of PCR amplification volume reduction using DNA entrapped in FTA™ Classic Card and to bring cost savings to the laboratory. There were a few concerns the laboratory needed to address. First, the kinetics of the amplification reaction could be significantly altered. Second, an increase in sensitivity might affect interpretation due to increased stochastic effects even though they were pristine samples. Third, statics might cause FTA punches to jump out of its allocated well into another thus causing sample-to-sample contamination. Fourth, the size of the punches might be too small for visual inspection. Last, there would be a limit to the extent of volume reduction due to evaporation and the possible need of re-injection of samples for capillary electrophoresis. The laboratory had successfully optimized a reduced amplification volume of 10 μL for FTA samples. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Detection limit of Mycobacterium chimaera in water samples for monitoring medical device safety: insights from a pilot experimental series.

PubMed

Schreiber, P W; Köhler, N; Cervera, R; Hasse, B; Sax, H; Keller, P M

2018-07-01

A growing number of Mycobacterium chimaera infections after cardiosurgery have been reported by several countries. These potentially fatal infections were traced back to contaminated heater-cooler devices (HCDs), which use water as a heat transfer medium. Aerosolization of water contaminated with M. chimaera from HCDs enables airborne transmission to patients undergoing open chest surgery. Infection control teams test HCD water samples for mycobacterial growth to guide preventive measures. The detection limit of M. chimaera in water samples, however, has not previously been investigated. To determine the detection limit of M. chimaera in water samples using laboratory-based serial dilution tests. An M. chimaera strain representative of the international cardiosurgery-associated M. chimaera outbreak was used to generate a logarithmic dilution series. Two different water volumes, 50 and 1000mL, were inoculated, and, after identical processing (centrifugation, decantation, and decontamination), seeded on mycobacteria growth indicator tube (MGIT) and Middlebrook 7H11 solid media. MGIT consistently showed a lower detection limit than 7H11 solid media, corresponding to a detection limit of ≥1.44 × 10 4 cfu/mL for 50mL and ≥2.4cfu/mL for 1000mL water samples. Solid media failed to detect M. chimaera in 50mL water samples. Depending on water volume and culture method, major differences exist in the detection limit of M. chimaera. In terms of sensitivity, 1000mL water samples in MGIT media performed best. Our results have important implications for infection prevention and control strategies in mitigation of the M. chimaera outbreak and healthcare water safety in general. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Wider-Opening Dewar Flasks for Cryogenic Storage

NASA Technical Reports Server (NTRS)

Ruemmele, Warren P.; Manry, John; Stafford, Kristin; Bue, Grant; Krejci, John; Evernden, Bent

2010-01-01

Dewar flasks have been proposed as containers for relatively long-term (25 days) storage of perishable scientific samples or other perishable objects at a temperature of 175 C. The refrigeration would be maintained through slow boiling of liquid nitrogen (LN2). For the purposes of the application for which these containers were proposed, (1) the neck openings of commercial off-the-shelf (COTS) Dewar flasks are too small for most NASA samples; (2) the round shapes of the COTS containers give rise to unacceptably low efficiency of packing in rectangular cargo compartments; and (3) the COTS containers include metal structures that are too thermally conductive, such that they cannot, without exceeding size and weight limits, hold enough LN2 for the required long-term-storage. In comparison with COTS Dewar flasks, the proposed containers would be rectangular, yet would satisfy the long-term storage requirement without exceeding size and weight limits; would have larger neck openings; and would have greater sample volumes, leading to a packing efficiency of about double the sample volume as a fraction of total volume. The proposed containers would be made partly of aerospace- type composite materials and would include vacuum walls, multilayer insulation, and aerogel insulation.

A Fast, Accurate and Sensitive GC-FID Method for the Analyses of Glycols in Water and Urine

NASA Technical Reports Server (NTRS)

Kuo, C. Mike; Alverson, James T.; Gazda, Daniel B.

2017-01-01

Glycols, specifically ethylene glycol and 1,2-propanediol, are some of the major organic compounds found in the humidity condensate samples collected on the International Space Station. The current analytical method for glycols is a GC/MS method with direct sample injection. This method is simple and fast, but it is not very sensitive. Reporting limits for ethylene glycol and 1,2-propanediol are only 1 ppm. A much more sensitive GC/FID method was developed, in which glycols were derivatized with benzoyl chloride for 10 minutes before being extracted with hexane. Using 1,3-propanediol as an internal standard, the detection limits for the GC/FID method was determined to be 50 ppb and the analysis only takes 7 minutes. Data from the GC/MS and the new GC/FID methods shows excellent agreement with each other. Factors affecting the sensitivity, including sample volume, NaOH concentration and volume, volume of benzoyl chloride, reaction time and temperature, were investigated. Interferences during derivatization and possible method to reduce interferences were also investigated.

Enumerating Sparse Organisms in Ships’ Ballast Water: Why Counting to 10 Is Not So Easy

PubMed Central

2011-01-01

To reduce ballast water-borne aquatic invasions worldwide, the International Maritime Organization and United States Coast Guard have each proposed discharge standards specifying maximum concentrations of living biota that may be released in ships’ ballast water (BW), but these regulations still lack guidance for standardized type approval and compliance testing of treatment systems. Verifying whether BW meets a discharge standard poses significant challenges. Properly treated BW will contain extremely sparse numbers of live organisms, and robust estimates of rare events require extensive sampling efforts. A balance of analytical rigor and practicality is essential to determine the volume of BW that can be reasonably sampled and processed, yet yield accurate live counts. We applied statistical modeling to a range of sample volumes, plankton concentrations, and regulatory scenarios (i.e., levels of type I and type II errors), and calculated the statistical power of each combination to detect noncompliant discharge concentrations. The model expressly addresses the roles of sampling error, BW volume, and burden of proof on the detection of noncompliant discharges in order to establish a rigorous lower limit of sampling volume. The potential effects of recovery errors (i.e., incomplete recovery and detection of live biota) in relation to sample volume are also discussed. PMID:21434685

Enumerating sparse organisms in ships' ballast water: why counting to 10 is not so easy.

PubMed

Miller, A Whitman; Frazier, Melanie; Smith, George E; Perry, Elgin S; Ruiz, Gregory M; Tamburri, Mario N

2011-04-15

To reduce ballast water-borne aquatic invasions worldwide, the International Maritime Organization and United States Coast Guard have each proposed discharge standards specifying maximum concentrations of living biota that may be released in ships' ballast water (BW), but these regulations still lack guidance for standardized type approval and compliance testing of treatment systems. Verifying whether BW meets a discharge standard poses significant challenges. Properly treated BW will contain extremely sparse numbers of live organisms, and robust estimates of rare events require extensive sampling efforts. A balance of analytical rigor and practicality is essential to determine the volume of BW that can be reasonably sampled and processed, yet yield accurate live counts. We applied statistical modeling to a range of sample volumes, plankton concentrations, and regulatory scenarios (i.e., levels of type I and type II errors), and calculated the statistical power of each combination to detect noncompliant discharge concentrations. The model expressly addresses the roles of sampling error, BW volume, and burden of proof on the detection of noncompliant discharges in order to establish a rigorous lower limit of sampling volume. The potential effects of recovery errors (i.e., incomplete recovery and detection of live biota) in relation to sample volume are also discussed.

Development of a Pipeline for Exploratory Metabolic Profiling of Infant Urine

PubMed Central

Jackson, Frances; Georgakopoulou, Nancy; Kaluarachchi, Manuja; Kyriakides, Michael; Andreas, Nicholas; Przysiezna, Natalia; Hyde, Matthew J.; Modi, Neena; Nicholson, Jeremy K.; Wijeyesekera, Anisha; Holmes, Elaine

2017-01-01

Numerous metabolic profiling pipelines have been developed to characterize the composition of human biofluids and tissues, the vast majority of these being for studies in adults. To accommodate limited sample volume and to take into account the compositional differences between adult and infant biofluids, we developed and optimized sample handling and analytical procedures for studying urine from newborns. A robust pipeline for metabolic profiling using NMR spectroscopy was established, encompassing sample collection, preparation, spectroscopic measurement, and computational analysis. Longitudinal samples were collected from five infants from birth until 14 months of age. Methods of extraction and effects of freezing and sample dilution were assessed, and urinary contaminants from breakdown of polymers in a range of diapers and cotton wool balls were identified and compared, including propylene glycol, acrylic acid, and tert-butanol. Finally, assessment of urinary profiles obtained over the first few weeks of life revealed a dramatic change in composition, with concentrations of phenols, amino acids, and betaine altering systematically over the first few months of life. Therefore, neonatal samples require more stringent standardization of experimental design, sample handling, and analysis compared to that of adult samples to accommodate the variability and limited sample volume. PMID:27476583

Evaluation of counting methods for oceanic radium-228

NASA Astrophysics Data System (ADS)

Orr, James C.

1988-07-01

Measurement of open ocean 228Ra is difficult, typically requiring at least 200 L of seawater. The burden of collecting and processing these large-volume samples severely limits the widespread use of this promising tracer. To use smaller-volume samples, a more sensitive means of analysis is required. To seek out new and improved counting method(s), conventional 228Ra counting methods have been compared with some promising techniques which are currently used for other radionuclides. Of the conventional methods, α spectrometry possesses the highest efficiency (3-9%) and lowest background (0.0015 cpm), but it suffers from the need for complex chemical processing after sampling and the need to allow about 1 year for adequate ingrowth of 228Th granddaughter. The other two conventional counting methods measure the short-lived 228Ac daughter while it remains supported by 228Ra, thereby avoiding the complex sample processing and the long delay before counting. The first of these, high-resolution γ spectrometry, offers the simplest processing and an efficiency (4.8%) comparable to α spectrometry; yet its high background (0.16 cpm) and substantial equipment cost (˜30,000) limit its widespread use. The second no-wait method, β-γ coincidence spectrometry, also offers comparable efficiency (5.3%), but it possesses both lower background (0.0054 cpm) and lower initial cost (˜12,000). Three new (i.e., untried for 228Ra) techniques all seem to promise about a fivefold increase in efficiency over conventional methods. By employing liquid scintillation methods, both α spectrometry and β-γ coincidence spectrometry can improve their counter efficiency while retaining low background. The third new 228Ra counting method could be adapted from a technique which measures 224Ra by 220Rn emanation. After allowing for ingrowth and then counting for the 224Ra great-granddaughter, 228Ra could be back calculated, thereby yielding a method with high efficiency, where no sample processing is required. The efficiency and background of each of the three new methods have been estimated and are compared with those of the three methods currently employed to measure oceanic 228Ra. From efficiency and background, the relative figure of merit and the detection limit have been determined for each of the six counters. These data suggest that the new counting methods have the potential to measure most 228Ra samples with just 30 L of seawater, to better than 5% precision. Not only would this reduce the time, effort, and expense involved in sample collection, but 228Ra could then be measured on many small-volume samples (20-30 L) previously collected with only 226Ra in mind. By measuring 228Ra quantitatively on such small-volume samples, three analyses (large-volume 228Ra, large-volume 226Ra, and small-volume 226Ra) could be reduced to one, thereby dramatically improving analytical precision.

Automation of sample processing for ICP-MS determination of 90Sr radionuclide at ppq level for nuclear technology and environmental purposes.

PubMed

Kołacińska, Kamila; Chajduk, Ewelina; Dudek, Jakub; Samczyński, Zbigniew; Łokas, Edyta; Bojanowska-Czajka, Anna; Trojanowicz, Marek

2017-07-01

90 Sr is a widely determined radionuclide for environmental purposes, nuclear waste control, and can be also monitored in coolants in nuclear reactor plants. In the developed method, the ICP-MS detection was employed together with sample processing in sequential injection analysis (SIA) setup, equipped with a lab-on-valve with mechanized renewal of sorbent bed for solid-phase extraction. The optimized conditions of determination included preconcentration of 90 Sr on cation-exchange column and removal of different type of interferences using extraction Sr-resin. The limit of detection of the developed procedure depends essentially on the configuration of the employed ICP-MS spectrometer and on the available volume of the sample to be analyzed. For 1L initial sample volume, the method detection limit (MDL) value was evaluated as 2.9ppq (14.5BqL -1 ). The developed method was applied to analyze spiked river water samples, water reference materials, and also simulated and real samples of the nuclear reactor coolant. Copyright © 2016 Elsevier B.V. All rights reserved.

Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid micro-volume samples

PubMed Central

Schaper, J. Niklas; Pfeuffer, Kevin P.; Shelley, Jacob T.; Bings, Nicolas H.

2012-01-01

One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed “drop-on-demand” (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (~17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 µg/mL, without sample pretreatment, were obtained. PMID:23025277

On-line preconcentration and speciation of arsenic by flow injection hydride generation atomic absorption spectrophotometry.

PubMed

Narcise, Cristine Ingrid S; Coo, Lilibeth Dlc; Del Mundo, Florian R

2005-12-15

A flow injection-column preconcentration-hydride generation atomic absorption spectrophotometric (FI-column-HGAAS) method was developed for determining mug/l levels of As(III) and As(V) in water samples, with simultaneous preconcentration and speciation. The speciation scheme involved determining As(V) at neutral pH and As(III+V) at pH 12, with As(III) obtained by difference. The enrichment factor (EF) increased with increase in sample loading volume from 2.5 to 10ml, and for preconcentration using the chloride-form anion exchange column, EFs ranged from 5 to 48 for As(V) and 4 to 24 for As(III+V), with corresponding detection limits of 0.03-0.3 and 0.07-0.3mug/l. Linear concentration range (LCR) also varied with sample loading volume, and for a 5-ml sample was 0.3-5 and 0.2-8mug/l for As(V) and As(III+V), respectively. Sample throughput, which decreased with increase in sample volume, was 8-17 samples/h. For the hydroxide-form column, the EFS for 2.5-10ml samples were 3-23 for As(V) and 2-15 for As(III+V), with corresponding detection limits of 0.07-0.4 and 0.1-0.5mug/l. The LCR for a 5-ml sample was 0.3-10mug/l for As(V) and 0.2-20mug/l for As(III+V). Sample throughput was 10-20 samples/h. The developed method has been effectively applied to tap water and mineral water samples, with recoveries ranging from 90 to 102% for 5-ml samples passed through the two columns.

Rapid method for measuring rotenone in water at piscicidal concentrations

USGS Publications Warehouse

Dawson, V.K.; Harman, P.D.; Schultz, D.P.; Allen, J.L.

1983-01-01

A high-performance liquid chromatography (HPLC) procedure that is rapid, specific, and sensitive (limit of detection <0.005 mg/liter) was developed for monitoring application and degradation rates of rotenone. For analysis, a water sample is buffered to pH 5 and injected through a Sep Pak(R) C18 disposable cartridge. The cartridge adsorbs and retains the rotenone which then can be eluted quantitatively from the cartridge with a small volume of methanol. This step effectively concentrates the sample and provides sample cleanup. The methanol extract is analyzed directly by HPLC on an MCH 10 reverse-phase column; methanol: water (75:25, volume : volume) is the mobile phase and flow rate is 1.5 ml/minute. The rotenone is detected by ultraviolet spectrophotometry at a wavelength of 295 nm.

Lensfree diffractive tomography for the imaging of 3D cell cultures

NASA Astrophysics Data System (ADS)

Berdeu, Anthony; Momey, Fabien; Dinten, Jean-Marc; Gidrol, Xavier; Picollet-D'hahan, Nathalie; Allier, Cédric

2017-02-01

New microscopes are needed to help reaching the full potential of 3D organoid culture studies by gathering large quantitative and systematic data over extended periods of time while preserving the integrity of the living sample. In order to reconstruct large volumes while preserving the ability to catch every single cell, we propose new imaging platforms based on lens-free microscopy, a technic which is addressing these needs in the context of 2D cell culture, providing label-free and non-phototoxic acquisition of large datasets. We built lens-free diffractive tomography setups performing multi-angle acquisitions of 3D organoid cultures embedded in Matrigel and developed dedicated 3D holographic reconstruction algorithms based on the Fourier diffraction theorem. Nonetheless, holographic setups do not record the phase of the incident wave front and the biological samples in Petri dish strongly limit the angular coverage. These limitations introduce numerous artefacts in the sample reconstruction. We developed several methods to overcome them, such as multi-wavelength imaging or iterative phase retrieval. The most promising technic currently developed is based on a regularised inverse problem approach directly applied on the 3D volume to reconstruct. 3D reconstructions were performed on several complex samples such as 3D networks or spheroids embedded in capsules with large reconstructed volumes up to 25 mm3 while still being able to identify single cells. To our knowledge, this is the first time that such an inverse problem approach is implemented in the context of lens-free diffractive tomography enabling to reconstruct large fully 3D volumes of unstained biological samples.

40 CFR 63.1385 - Test methods and procedures.

Code of Federal Regulations, 2010 CFR

2010-07-01

... applicable emission limits: (1) Method 1 (40 CFR part 60, appendix A) for the selection of the sampling port location and number of sampling ports; (2) Method 2 (40 CFR part 60, appendix A) for volumetric flow rate.... Each run shall consist of a minimum run time of 2 hours and a minimum sample volume of 60 dry standard...

The local environment of ice particles in arctic mixed-phase clouds

NASA Astrophysics Data System (ADS)

Schlenczek, Oliver; Fugal, Jacob P.; Schledewitz, Waldemar; Borrmann, Stephan

2015-04-01

During the RACEPAC field campaign in April and May 2014, research flights were made with the Polar 5 and Polar 6 aircraft from the Alfred Wegener Institute in Arctic clouds near Inuvik, Northwest Territories, Canada. One flight with the Polar 6 aircraft, done on May 16, 2014, flew under precipitating, stratiform, mid-level clouds with several penetrations through cloud base. Measurements with HALOHolo, an airborne digital in-line holographic instrument for cloud particles, show ice particles in a field of other cloud particles in a local three-dimensional sample volume (~14x19x130 mm3 or ~35 cm^3). Each holographic sample volume is a snapshot of a 3-dimensional piece of cloud at the cm-scale with typically thousands of cloud droplets per sample volume, so each sample volume yields a statistically significant droplet size distribution. Holograms are recorded at a rate of six times per second, which provides one volume sample approx. every 12 meters along the flight path. The size resolution limit for cloud droplets is better than 1 µm due to advanced sizing algorithms. Shown are preliminary results of, (1) the ice/liquid water partitioning at the cloud base and the distribution of water droplets around each ice particle, and (2) spatial and temporal variability of the cloud droplet size distributions at cloud base.

Validation of dilution of plasma samples with phosphate buffered saline to eliminate the problem of small volumes associated with children infected with HIV-1 for viral load testing using Cobas AmpliPrep/COBAS TaqMan HIV-1 test, version 2.0 (CAP CTM HIV v2.0).

PubMed

Mine, Madisa; Nkoane, Tapologo; Sebetso, Gaseene; Sakyi, Bright; Makhaola, Kgomotso; Gaolathe, Tendani

2013-12-01

The sample requirement of 1 mL for the Roche COBAS AmpliPrep/COBAS TaqMan HIV-1 test, version 2.0 (CAP CTM HIV v2.0) limits its utility in measuring plasma HIV-1 RNA levels for small volume samples from children infected with HIV-1. Viral load monitoring is the standard of care for HIV-1-infected patients on antiretroviral therapy in Botswana. The study aimed to validate the dilution of small volume samples with phosphate buffered saline (1× PBS) when quantifying HIV-1 RNA in patient plasma. HIV RNA concentrations were determined in undiluted and diluted pairs of samples comprising panels of quality assessment standards (n=52) as well as patient samples (n=325). There was strong correlation (R(2)) of 0.98 and 0.95 within the dynamic range of the CAP CTM HIV v2.0 test between undiluted and diluted samples from quality assessment standards and patients, respectively. The difference between viral load measurements of diluted and undiluted pairs of quality assessment standards and patient samples using the Altman-Bland test showed that the 95% limits of agreement were between -0.40 Log 10 and 0.49 Log 10. This difference was within the 0.5 Log 10 which is generally considered as normal assay variation of plasma RNA levels. Dilution of samples with 1× PBS produced comparable viral load measurements to undiluted samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Dual dispersive liquid-liquid microextraction for determination of phenylpropenes in oils by gas chromatography-mass spectrometry.

PubMed

Tsai, Chia-Ju; Li, Jih-Heng; Feng, Chia-Hsien

2015-09-04

A novel, simple and quick sample preparation method was developed and used for pre-concentration and extraction of six phenylpropenes, including anethole, estragole, eugenol, methyl eugenol, safrole and myristicin, from oil samples by dual dispersive liquid-liquid microextraction. Gas chromatography-mass spectrometry was used for determination and separation of compounds. Several experimental parameters affecting extraction efficiency were evaluated and optimized, including forward-extractant type and volume, surfactant type and concentration, water volume, and back-extractant type and volume. For all analytes (10-1000ng/mL), the limits of detection (S/N≧3) ranged from 1.0 to 3.0ng/mL; the limits of quantification (S/N≧10) ranged from 2.5 to 10.0ng/mL; and enrichment factors ranged from 3.2 to 37.1 times. Within-run and between-run relative standard deviations (n=6) were less than 2.61% and less than 4.33%, respectively. Linearity was excellent with determination coefficients (r(2)) above 0.9977. The experiments showed that the proposed method is a simple, effective, and environmentally friendly method of analyzing phenylpropenes in oil samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Microscale depletion of high abundance proteins in human biofluids using IgY14 immunoaffinity resin: analysis of human plasma and cerebrospinal fluid.

PubMed

Hyung, Seok-Won; Piehowski, Paul D; Moore, Ronald J; Orton, Daniel J; Schepmoes, Athena A; Clauss, Therese R; Chu, Rosalie K; Fillmore, Thomas L; Brewer, Heather; Liu, Tao; Zhao, Rui; Smith, Richard D

2014-11-01

Removal of highly abundant proteins in plasma is often carried out using immunoaffinity depletion to extend the dynamic range of measurements to lower abundance species. While commercial depletion columns are available for this purpose, they generally are not applicable to limited sample quantities (<20 μL) due to low yields stemming from losses caused by nonspecific binding to the column matrix and concentration of large eluent volumes. Additionally, the cost of the depletion media can be prohibitive for larger-scale studies. Modern LC-MS instrumentation provides the sensitivity necessary to scale-down depletion methods with minimal sacrifice to proteome coverage, which makes smaller volume depletion columns desirable for maximizing sample recovery when samples are limited, as well as for reducing the expense of large-scale studies. We characterized the performance of a 346 μL column volume microscale depletion system, using four different flow rates to determine the most effective depletion conditions for ∼6-μL injections of human plasma proteins and then evaluated depletion reproducibility at the optimum flow rate condition. Depletion of plasma using a commercial 10-mL depletion column served as the control. Results showed depletion efficiency of the microscale column increased as flow rate decreased, and that our microdepletion was reproducible. In an initial application, a 600-μL sample of human cerebrospinal fluid (CSF) pooled from multiple sclerosis patients was depleted and then analyzed using reversed phase liquid chromatography-mass spectrometry to demonstrate the utility of the system for this important biofluid where sample quantities are more commonly limited.

Integrated hollow microneedle-optofluidic biosensor for therapeutic drug monitoring in sub-nanoliter volumes

NASA Astrophysics Data System (ADS)

Ranamukhaarachchi, Sahan A.; Padeste, Celestino; Dübner, Matthias; Häfeli, Urs O.; Stoeber, Boris; Cadarso, Victor J.

2016-07-01

Therapeutic drug monitoring (TDM) typically requires painful blood drawn from patients. We propose a painless and minimally-invasive alternative for TDM using hollow microneedles suitable to extract extremely small volumes (<1 nL) of interstitial fluid to measure drug concentrations. The inner lumen of a microneedle is functionalized to be used as a micro-reactor during sample collection to trap and bind target drug candidates during extraction, without requirements of sample transfer. An optofluidic device is integrated with this microneedle to rapidly quantify drug analytes with high sensitivity using a straightforward absorbance scheme. Vancomycin is currently detected by using volumes ranging between 50-100 μL with a limit of detection (LoD) of 1.35 μM. The proposed microneedle-optofluidic biosensor can detect vancomycin with a sample volume of 0.6 nL and a LoD of <100 nM, validating this painless point of care system with significant potential to reduce healthcare costs and patients suffering.

Integrated hollow microneedle-optofluidic biosensor for therapeutic drug monitoring in sub-nanoliter volumes

PubMed Central

Ranamukhaarachchi, Sahan A.; Padeste, Celestino; Dübner, Matthias; Häfeli, Urs O.; Stoeber, Boris; Cadarso, Victor J.

2016-01-01

Therapeutic drug monitoring (TDM) typically requires painful blood drawn from patients. We propose a painless and minimally-invasive alternative for TDM using hollow microneedles suitable to extract extremely small volumes (<1 nL) of interstitial fluid to measure drug concentrations. The inner lumen of a microneedle is functionalized to be used as a micro-reactor during sample collection to trap and bind target drug candidates during extraction, without requirements of sample transfer. An optofluidic device is integrated with this microneedle to rapidly quantify drug analytes with high sensitivity using a straightforward absorbance scheme. Vancomycin is currently detected by using volumes ranging between 50–100 μL with a limit of detection (LoD) of 1.35 μM. The proposed microneedle-optofluidic biosensor can detect vancomycin with a sample volume of 0.6 nL and a LoD of <100 nM, validating this painless point of care system with significant potential to reduce healthcare costs and patients suffering. PMID:27380889

Determination of formaldehyde by HPLC as the DNPH derivative following high-volume air sampling onto bisulfite-coated cellulose filters

NASA Astrophysics Data System (ADS)

de Andrade, Jailson B.; Tanner, Roger L.

A method is described for the specific collection of formaldehyde as hydroxymethanesulfonate on bisulfate-coated cellulose filters. Following extraction in aqueous acid and removal on unreacted bisulfite, the hydroxymethanesulfonate is decomposed by base, and HCHO is determined by DNPH (2,4-dinitrophenylhydrazine) derivatization and HPLC. Since the collection efficiency for formaldehyde is moderately high even when sampling ambient air at high-volume flow rates, a limit of detection of 0.2 ppbv is achieved with 30 min sampling times. Interference from acetaldehyde co-collected as 1-hydroxyethanesulfonate is <5% using this procedure. The technique shows promise for both short-term airborne sampling, and as a means of collecting mg-sized samples of HCHO on an inorganic matrix for carbon isotopic analyses.

Novel diamond cells for neutron diffraction using multi-carat CVD anvils.

PubMed

Boehler, R; Molaison, J J; Haberl, B

2017-08-01

Traditionally, neutron diffraction at high pressure has been severely limited in pressure because low neutron flux required large sample volumes and therefore large volume presses. At the high-flux Spallation Neutron Source at the Oak Ridge National Laboratory, we have developed new, large-volume diamond anvil cells for neutron diffraction. The main features of these cells are multi-carat, single crystal chemical vapor deposition diamonds, very large diffraction apertures, and gas membranes to accommodate pressure stability, especially upon cooling. A new cell has been tested for diffraction up to 40 GPa with an unprecedented sample volume of ∼0.15 mm 3 . High quality spectra were obtained in 1 h for crystalline Ni and in ∼8 h for disordered glassy carbon. These new techniques will open the way for routine megabar neutron diffraction experiments.

Optimization and determination of Cd (II) in different environmental water samples with dispersive liquid-liquid microextraction preconcentration combined with inductively coupled plasma optical emission spectrometry.

PubMed

Salahinejad, Maryam; Aflaki, Fereydoon

2011-06-01

Dispersive liquid-liquid microextraction followed by inductively coupled plasma-optical emission spectrometry has been investigated for determination of Cd(II) ions in water samples. Ammonium pyrrolidine dithiocarbamate was used as chelating agent. Several factors influencing the microextraction efficiency of Cd (II) ions such as extracting and dispersing solvent type and their volumes, pH, sample volume, and salting effect were optimized. The optimization was performed both via one variable at a time, and central composite design methods and the optimum conditions were selected. Both optimization methods showed nearly the same results: sample size 5 mL; dispersive solvent ethanol; dispersive solvent volume 2 mL; extracting solvent chloroform; extracting solvent volume 200 [Formula: see text]L; pH and salt amount do not affect significantly the microextraction efficiency. The limits of detection and quantification were 0.8 and 2.5 ng L( - 1), respectively. The relative standard deviation for five replicate measurements of 0.50 mg L( - 1) of Cd (II) was 4.4%. The recoveries for the spiked real samples from tap, mineral, river, dam, and sea waters samples ranged from 92.2% to 104.5%.

Immunocytometric quantitation of foeto-maternal haemorrhage with the Abbott Cell-Dyn CD4000 haematology analyser.

PubMed

Little, B H; Robson, R; Roemer, B; Scott, C S

2005-02-01

This study evaluated the extended use of a haematology analyser (Abbott Cell-Dyn CD4000) for the immunofluorescent enumeration of foeto-maternal haemorrhage (FMH) with fluorescein isothiocyanate-labelled monoclonal anti-RhD. Method performance was assessed with artificial FMH standards, and a series of 44 clinical samples. Within run precision was <15% (coefficient of variation, CV) for FMH volumes of 3 ml and above, 18.8% at an FMH volume of 2 ml and 31.7% at an FMH volume of 1 ml. Linearity analysis showed excellent agreement (observed FMH% = 0.98x expected FMH% + 0.02), and a close relationship (R(2) = 0.99) between observed and expected FMH percentages. The lower limit of quantification of the CD4000 (SRP-Ret) method with a maximum CV of 15% was 1.6 ml, and the limit of detection was <1 ml. Parallel Kleihauer-Betke test (KBT) assessments of FMH standards showed an overall trend for higher KBT values (observed = 1.25x expected - 0.38). At an FMH level of 4 ml, KBT observer estimates ranged from 0.57 to 11.94 ml with a mean inter-observer CV of 63%. For 44 clinical samples, there was decision point agreement between KBT and SRP-Ret results for 42 samples with an FMH of <2 ml. Analysis in the low FMH range (<1 ml) showed that small volume foetal leaks could be detected with the SRP-Ret method in most of 23 samples with negative KBT results. CD4000 SRP-Ret method performance for FMH determination was similar to that reported for flow cytometry.

Fabrication of graphene/Fe3O4@polythiophene nanocomposite and its application in the magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from environmental water samples.

PubMed

Mehdinia, Ali; Khodaee, Nader; Jabbari, Ali

2015-04-08

Polythiophene (PT) was used as a surface modifier of graphene/Fe3O4 (G/Fe3O4) composite to increase merit of it, and also overcome some limitations and disadvantages of using G/Fe3O4 alone as solid phase extraction (SPE) sorbent. An in-situ chemical polymerization method was employed to prepare G/Fe3O4@PT nanocomposites. Application of this newly designed material in the magnetic SPE (MSPE) of polycyclic aromatic hydrocarbons (PAHs), as model analytes, in the environmental water samples was investigated. The characterization of the hybrid material was performed using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, Fourier transform-infrared (FT-IR) spectroscopy and vibrating sample magnetometry. Seven important parameters, affecting the extraction efficiency of PAHs, including: amount of adsorbent, adsorption and desorption times, type and volume of the eluent solvent, initial sample volume and salt content of the sample were evaluated. The optimum extraction conditions were obtained as: 4 min for extraction time, 20 mg for sorbent amount, 100mL for initial sample volume, toluene as desorption solvent, 0.6 mL for desorption solvent volume, 6 min for desorption time and 30% (w/v) for NaCl concentration. Good performance data were obtained at the optimized conditions. Detection limits were in the range of 0.009-0.020 μg L(-1) in the real matrix. The calibration curves were linear over the concentration ranges from 0.03 to 80 μg L(-1) with correlation coefficients (R(2)) between 0.995 and 0.998 for all the analytes. Relative standard deviations were ranged from 4.3 to 6.3%. Appropriate recovery values, in the range of 83-107%, were also obtained for the real sample analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Impact of phase ratio, polydimethylsiloxane volume and size, and sampling temperature and time on headspace sorptive extraction recovery of some volatile compounds in the essential oil field.

PubMed

Bicchi, Carlo; Cordero, Chiara; Liberto, Erica; Rubiolo, Patrizia; Sgorbini, Barbara; Sandra, Pat

2005-04-15

This study evaluates concentration capability of headspace sorptive extraction (HSSE) and the influence of sampling conditions on HSSE recovery of an analyte. A standard mixture in water of six high-to-medium volatility analytes (isobutyl methyl ketone, 3-hexanol, isoamyl acetate, 1,8-cineole, linalool and carvone) was used to sample the headspace by HSSE with stir bars coated with different polydimethylsiloxane (PDMS) volumes (20, 40, 55 and 110 microL, respectively), headspace vial volumes (8, 21.2, 40, 250 and 1000 mL), sampling temperatures (25, 50 and 75 degrees C) and sampling times (30, 60 and 120 min, and 4, 8 and 16 h). The concentration factors (CFs) of HSSE versus static headspace (S-HS) were also determined. Analytes sampled by the PDMS stir bars were recovered by thermal desorption (TDS) and analysed by capillary GC-MS. This study demonstrates how analyte recovery depends on its physico-chemical characteristics and affinity for PDMS (octanol-water partition coefficients), sampling temperatures (50 degrees C) and times (60 min), the volumes of headspace (40 mL) and of PDMS (in particular, for high volatility analytes). HSSE is also shown to be very effective for trace analysis. The HSSE CFs calculated versus S-HS with a 1000 mL headspace volumes at 25 degrees C during 4 h sampling ranged between 10(3) and 10(4) times for all analytes investigated while the limits of quantitation determined under the same conditions were in the nmol/L range.

Chemical Method of Urine Volume Measurement

NASA Technical Reports Server (NTRS)

Petrack, P.

1967-01-01

A system has been developed and qualified as flight hardware for the measurement of micturition volumes voided by crewmen during Gemini missions. This Chemical Urine Volume Measurement System (CUVMS) is used for obtaining samples of each micturition for post-flight volume determination and laboratory analysis for chemical constituents of physiological interest. The system is versatile with respect to volumes measured, with a capacity beyond the largest micturition expected to be encountered, and with respect to mission duration of inherently indefinite length. The urine sample is used for the measurement of total micturition volume by a tracer dilution technique, in which a fixed, predetermined amount of tritiated water is introduced and mixed into the voided urine, and the resulting concentration of the tracer in the sample is determined with a liquid scintillation spectrometer. The tracer employed does not interfere with the analysis for the chemical constituents of the urine. The CUVMS hardware consists of a four-way selector valve in which an automatically operated tracer metering pump is incorporated, a collection/mixing bag, and tracer storage accumulators. The assembled system interfaces with a urine receiver at the selector valve inlet, sample bags which connect to the side of the selector valve, and a flexible hose which carries the excess urine to the overboard drain connection. Results of testing have demonstrated system volume measurement accuracy within the specification limits of +/-5%, and operating reliability suitable for system use aboard the GT-7 mission, in which it was first used.

A highly addressable static droplet array enabling digital control of a single droplet at pico-volume resolution.

PubMed

Jeong, Heon-Ho; Lee, Byungjin; Jin, Si Hyung; Jeong, Seong-Geun; Lee, Chang-Soo

2016-04-26

Droplet-based microfluidics enabling exquisite liquid-handling has been developed for diagnosis, drug discovery and quantitative biology. Compartmentalization of samples into a large number of tiny droplets is a great approach to perform multiplex assays and to improve reliability and accuracy using a limited volume of samples. Despite significant advances in microfluidic technology, individual droplet handling in pico-volume resolution is still a challenge in obtaining more efficient and varying multiplex assays. We present a highly addressable static droplet array (SDA) enabling individual digital manipulation of a single droplet using a microvalve system. In a conventional single-layer microvalve system, the number of microvalves required is dictated by the number of operation objects; thus, individual trap-and-release on a large-scale 2D array format is highly challenging. By integrating double-layer microvalves, we achieve a "balloon" valve that preserves the pressure-on state under released pressure; this valve can allow the selective releasing and trapping of 7200 multiplexed pico-droplets using only 1 μL of sample without volume loss. This selectivity and addressability completely arranged only single-cell encapsulated droplets from a mixture of droplet compositions via repetitive selective trapping and releasing. Thus, it will be useful for efficient handling of miniscule volumes of rare or clinical samples in multiplex or combinatory assays, and the selective collection of samples.

10 CFR Appendix B to Subpart C of... - Sampling Plan for Enforcement Testing of Covered Equipment and Certain Low-Volume Covered Products

Code of Federal Regulations, 2014 CFR

2014-01-01

... percent, one-sided confidence limit and a sample size of n1. (2) For an energy consumption standard (ECS..., where ECS is the energy consumption standard and t is a statistic based on a 97.5 percent, one-sided...

10 CFR Appendix B to Subpart C of... - Sampling Plan for Enforcement Testing of Covered Equipment and Certain Low-Volume Covered Products

Code of Federal Regulations, 2013 CFR

2013-01-01

... percent, one-sided confidence limit and a sample size of n1. (2) For an energy consumption standard (ECS..., where ECS is the energy consumption standard and t is a statistic based on a 97.5 percent, one-sided...

10 CFR Appendix B to Subpart C of... - Sampling Plan for Enforcement Testing of Covered Equipment and Certain Low-Volume Covered Products

Code of Federal Regulations, 2012 CFR

2012-01-01

... percent, one-sided confidence limit and a sample size of n1. (2) For an energy consumption standard (ECS..., where ECS is the energy consumption standard and t is a statistic based on a 97.5 percent, one-sided...

Impact of Non-Gaussian Error Volumes on Conjunction Assessment Risk Analysis

NASA Technical Reports Server (NTRS)

Ghrist, Richard W.; Plakalovic, Dragan

2012-01-01

An understanding of how an initially Gaussian error volume becomes non-Gaussian over time is an important consideration for space-vehicle conjunction assessment. Traditional assumptions applied to the error volume artificially suppress the true non-Gaussian nature of the space-vehicle position uncertainties. For typical conjunction assessment objects, representation of the error volume by a state error covariance matrix in a Cartesian reference frame is a more significant limitation than is the assumption of linearized dynamics for propagating the error volume. In this study, the impact of each assumption is examined and isolated for each point in the volume. Limitations arising from representing the error volume in a Cartesian reference frame is corrected by employing a Monte Carlo approach to probability of collision (Pc), using equinoctial samples from the Cartesian position covariance at the time of closest approach (TCA) between the pair of space objects. A set of actual, higher risk (Pc >= 10 (exp -4)+) conjunction events in various low-Earth orbits using Monte Carlo methods are analyzed. The impact of non-Gaussian error volumes on Pc for these cases is minimal, even when the deviation from a Gaussian distribution is significant.

XMM-Subaru:Complete High Precision Study of Galaxy Clusters for Modern Cosmology

NASA Astrophysics Data System (ADS)

Zhang, Yu-Ying

2011-10-01

We request 382 ks data for 12 clusters to complete our survey of a volume-limited sample of 55 clusters. We investigated the existing data, which hints a mass dependent bias in the X-ray to weak lensing mass ratios for disturbed ones. X-ray mass proxies, e.g., Yx, show low scatter, but the best fits, particularly the slopes, of the mass-observable relations may be biased due to this mass dependence. Our program will quantify any mass/radial dependent bias based on three independent probes (X-ray/lensing/velocity dispersion) for such a volume-limited sample, and deliver definitive constraints on systematics for upcoming cluster cosmology surveys. The dataset will be a major asset for programs aiming to measure dark energy and programs adding a multi-wavelength focus to studies of cluster physics.

Automated agar plate streaker: a linear plater on Society for Biomolecular Sciences standard plates.

PubMed

King, Gregory W; Kath, Gary S; Siciliano, Sal; Simpson, Neal; Masurekar, Prakash; Sigmund, Jan; Polishook, Jon; Skwish, Stephen; Bills, Gerald; Genilloud, Olga; Peláez, Fernando; Martín, Jesus; Dufresne, Claude

2006-09-01

Several protocols for bacterial isolation and techniques for aerobic plate counting rely on the use of a spiral plater to deposit concentration gradients of microbial suspensions onto a circular agar plate to isolate colony growth. The advantage of applying a gradient of concentrations across the agar surface is that the original microbiological sample can be applied at a single concentration rather than as multiple serial dilutions. The spiral plater gradually dilutes the sample across a compact area and therefore saves time preparing dilutions and multiple agar plates. Commercial spiral platers are not automated and require manual sample loading. Dispensing of the sample volume and rate of gradients are often very limited in range. Furthermore, the spiral sample application cannot be used with rectangular microplates. Another limitation of commercial spiral platers is that they are useful only for dilute, filtered suspensions and cannot plate suspensions of coarse organic particles therefore precluding the use of many kinds of microorganism-containing substrata. An automated agar plate spreader capable of processing 99 rectangular microplates in unattended mode is described. This novel instrument is capable of dispensing discrete volumes of sample in a linear pattern. It can be programmed to dispense a sample suspense at a uniform application rate or across a decreasing concentration gradient.

Evaluation of needle trap micro-extraction and automatic alveolar sampling for point-of-care breath analysis.

PubMed

Trefz, Phillip; Rösner, Lisa; Hein, Dietmar; Schubert, Jochen K; Miekisch, Wolfram

2013-04-01

Needle trap devices (NTDs) have shown many advantages such as improved detection limits, reduced sampling time and volume, improved stability, and reproducibility if compared with other techniques used in breath analysis such as solid-phase extraction and solid-phase micro-extraction. Effects of sampling flow (2-30 ml/min) and volume (10-100 ml) were investigated in dry gas standards containing hydrocarbons, aldehydes, and aromatic compounds and in humid breath samples. NTDs contained (single-bed) polymer packing and (triple-bed) combinations of divinylbenzene/Carbopack X/Carboxen 1000. Substances were desorbed from the NTDs by means of thermal expansion and analyzed by gas chromatography-mass spectrometry. An automated CO2-controlled sampling device for direct alveolar sampling at the point-of-care was developed and tested in pilot experiments. Adsorption efficiency for small volatile organic compounds decreased and breakthrough increased when sampling was done with polymer needles from a water-saturated matrix (breath) instead from dry gas. Humidity did not affect analysis with triple-bed NTDs. These NTDs showed only small dependencies on sampling flow and low breakthrough from 1-5 %. The new sampling device was able to control crucial parameters such as sampling flow and volume. With triple-bed NTDs, substance amounts increased linearly with increasing sample volume when alveolar breath was pre-concentrated automatically. When compared with manual sampling, automatic sampling showed comparable or better results. Thorough control of sampling and adequate choice of adsorption material is mandatory for application of needle trap micro-extraction in vivo. The new CO2-controlled sampling device allows direct alveolar sampling at the point-of-care without the need of any additional sampling, storage, or pre-concentration steps.

Novel diamond cells for neutron diffraction using multi-carat CVD anvils

DOE PAGES

Boehler, R.; Molaison, J. J.; Haberl, B.

2017-08-17

Traditionally, neutron diffraction at high pressure has been severely limited in pressure because low neutron flux required large sample volumes and therefore large volume presses. At the high-flux Spallation Neutron Source at the Oak Ridge National Laboratory, we have developed in this paper new, large-volume diamond anvil cells for neutron diffraction. The main features of these cells are multi-carat, single crystal chemical vapor deposition diamonds, very large diffraction apertures, and gas membranes to accommodate pressure stability, especially upon cooling. A new cell has been tested for diffraction up to 40 GPa with an unprecedented sample volume of ~0.15 mm 3.more » High quality spectra were obtained in 1 h for crystalline Ni and in ~8 h for disordered glassy carbon. Finally, these new techniques will open the way for routine megabar neutron diffraction experiments.« less

Empirically Optimized Flow Cytometric Immunoassay Validates Ambient Analyte Theory

PubMed Central

Parpia, Zaheer A.; Kelso, David M.

2010-01-01

Ekins’ ambient analyte theory predicts, counter intuitively, that an immunoassay’s limit of detection can be improved by reducing the amount of capture antibody. In addition, it also anticipates that results should be insensitive to the volume of sample as well as the amount of capture antibody added. The objective of this study is to empirically validate all of the performance characteristics predicted by Ekins’ theory. Flow cytometric analysis was used to detect binding between a fluorescent ligand and capture microparticles since it can directly measure fractional occupancy, the primary response variable in ambient analyte theory. After experimentally determining ambient analyte conditions, comparisons were carried out between ambient and non-ambient assays in terms of their signal strengths, limits of detection, and their sensitivity to variations in reaction volume and number of particles. The critical number of binding sites required for an assay to be in the ambient analyte region was estimated to be 0.1VKd. As predicted, such assays exhibited superior signal/noise levels and limits of detection; and were not affected by variations in sample volume and number of binding sites. When the signal detected measures fractional occupancy, ambient analyte theory is an excellent guide to developing assays with superior performance characteristics. PMID:20152793

Sequential injection spectrophotometric determination of oxybenzone in lipsticks.

PubMed

Salvador, A; Chisvert, A; Camarasa, A; Pascual-Martí, M C; March, J G

2001-08-01

A sequential injection (SI) procedure for the spectrophotometric determination of oxybenzone in lipsticks is reported. The colorimetric reaction between nickel and oxybenzone was used. SI parameters such as sample solution volume, reagent solution volume, propulsion flow rate and reaction coil length were studied. The limit of detection was 3 microg ml(-1). The sensitivity was 0.0108+/-0.0002 ml microg(-1). The relative standard deviations of the results were between 6 and 12%. The real concentrations of samples and the values obtained by HPLC were comparable. Microwave sample pre-treatment allowed the extraction of oxybenzone with ethanol, thus avoiding the use of toxic organic solvents. Ethanol was also used as carrier in the SI system. Seventy-two injections per hour can be performed, which means a sample frequency of 24 h(-1) if three replicates are measured for each sample.

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. I. Collection of Virus Samples

PubMed Central

Fout, G. Shay; Cashdollar, Jennifer L.; Varughese, Eunice A.; Parshionikar, Sandhya U.; Grimm, Ann C.

2015-01-01

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. The standardized sampling component of the method concentrates viruses that may be present in water by passage of a minimum specified volume of water through an electropositive cartridge filter. The minimum specified volumes for surface and finished/ground water are 300 L and 1,500 L, respectively. A major method limitation is the tendency for the filters to clog before meeting the sample volume requirement. Studies using two different, but equivalent, cartridge filter options showed that filter clogging was a problem with 10% of the samples with one of the filter types compared to 6% with the other filter type. Clogging tends to increase with turbidity, but cannot be predicted based on turbidity measurements only. From a cost standpoint one of the filter options is preferable over the other, but the water quality and experience with the water system to be sampled should be taken into consideration in making filter selections. PMID:25867928

Microvolume protein concentration determination using the NanoDrop 2000c spectrophotometer.

PubMed

Desjardins, Philippe; Hansen, Joel B; Allen, Michael

2009-11-04

Traditional spectrophotometry requires placing samples into cuvettes or capillaries. This is often impractical due to the limited sample volumes often used for protein analysis. The Thermo Scientific NanoDrop 2000c Spectrophotometer solves this issue with an innovative sample retention system that holds microvolume samples between two measurement surfaces using the surface tension properties of liquids, enabling the quantification of samples in volumes as low as 0.5-2 microL. The elimination of cuvettes or capillaries allows real time changes in path length, which reduces the measurement time while greatly increasing the dynamic range of protein concentrations that can be measured. The need for dilutions is also eliminated, and preparations for sample quantification are relatively easy as the measurement surfaces can be simply wiped with laboratory wipe. This video article presents modifications to traditional protein concentration determination methods for quantification of microvolume amounts of protein using A280 absorbance readings or the BCA colorimetric assay.

Generation of sub-femtoliter droplet by T-junction splitting on microfluidic chips

NASA Astrophysics Data System (ADS)

Yang, Yu-Jun; Feng, Xuan; Xu, Na; Pang, Dai-Wen; Zhang, Zhi-Ling

2013-03-01

In the paper, sub-femtoliter droplets were easily produced by droplet splitting at a simple T-junction with orifice, which did not need expensive equipments, complex photolithography skill, or high energy input. The volume of the daughter droplet was not limited by channel size but controlled by channel geometry and fluidic characteristic. Moreover, single bead sampling and bead quantification in different orders of magnitude of droplet volumes were investigated. The droplets split at our T-junction chip had small volume and monodispersed size and could be produced efficiently, orderly, and controllably.

40 CFR Table 1 to Subpart III of... - Emission Limitations

Code of Federal Regulations, 2011 CFR

2011-07-01

... determining compliance using this method Cadmium 0.004 milligrams per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Performance test (Method 29 of appendix A of part 60). Carbon monoxide 157 parts per million by dry volume 3-run average (1 hour minimum sample time per run) Performance...

40 CFR Table 1 to Subpart Eeee of... - Emission Limitations

Code of Federal Regulations, 2011 CFR

2011-07-01

... determiningcompliance using this method 1. Cadmium 18 micrograms per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Method 29 of appendix A of this part. 2. Carbon monoxide 40 parts per million by dry volume 3-run average (1 hour minimum sample time per run during performance test), and 12-hour...

40 CFR Table 1 to Subpart III of... - Emission Limitations

Code of Federal Regulations, 2010 CFR

2010-07-01

... determining compliance using this method Cadmium 0.004 milligrams per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Performance test (Method 29 of appendix A of part 60). Carbon monoxide 157 parts per million by dry volume 3-run average (1 hour minimum sample time per run) Performance...

40 CFR Table 1 to Subpart Eeee of... - Emission Limitations

Code of Federal Regulations, 2010 CFR

2010-07-01

... determiningcompliance using this method 1. Cadmium 18 micrograms per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Method 29 of appendix A of this part. 2. Carbon monoxide 40 parts per million by dry volume 3-run average (1 hour minimum sample time per run during performance test), and 12-hour...

10 CFR Appendix A to Subpart C of... - Sampling Plan for Enforcement Testing of Covered Consumer Products and Certain High-Volume...

Code of Federal Regulations, 2013 CFR

2013-01-01

... in Step (c). (6) For an energy or water consumption standard (ECS), compute the upper control limit (UCL2) for the mean of the combined first and second samples using the DOE ECS as the desired mean and a...)(1). (7) For an energy or water consumption standard (ECS), compare the combined sample mean (x2) to...

10 CFR Appendix A to Subpart C of... - Sampling Plan for Enforcement Testing of Covered Consumer Products and Certain High-Volume...

Code of Federal Regulations, 2014 CFR

2014-01-01

... in Step (c). (6) For an energy or water consumption standard (ECS), compute the upper control limit (UCL2) for the mean of the combined first and second samples using the DOE ECS as the desired mean and a...)(1). (7) For an energy or water consumption standard (ECS), compare the combined sample mean (x2) to...

10 CFR Appendix A to Subpart C of... - Sampling Plan for Enforcement Testing of Covered Consumer Products and Certain High-Volume...

Code of Federal Regulations, 2012 CFR

2012-01-01

... in Step (c). (6) For an energy or water consumption standard (ECS), compute the upper control limit (UCL2) for the mean of the combined first and second samples using the DOE ECS as the desired mean and a...)(1). (7) For an energy or water consumption standard (ECS), compare the combined sample mean (x2) to...

46 CFR Appendix D to Subpart C to... - Sampling and Analytical Methods for Benzene Monitoring-Measurement Procedures

Code of Federal Regulations, 2010 CFR

2010-10-01

... chromatograph. Detection limit: 0.04 ppm. Recommended air volume and sampling rate: 10 liter at 0.2 liter/min. 1... tube must be less than one inch of mercury at a flow rate of one liter per minute. 3.3. Gas... passed through any hose or tubing before entering the charcoal tube. 5.3.5. A sample size of 10 liters is...

46 CFR Appendix D to Subpart C to... - Sampling and Analytical Methods for Benzene Monitoring-Measurement Procedures

Code of Federal Regulations, 2011 CFR

2011-10-01

... chromatograph. Detection limit: 0.04 ppm. Recommended air volume and sampling rate: 10 liter at 0.2 liter/min. 1... tube must be less than one inch of mercury at a flow rate of one liter per minute. 3.3. Gas... passed through any hose or tubing before entering the charcoal tube. 5.3.5. A sample size of 10 liters is...

Glass frit nebulizer for atomic spectrometry

USGS Publications Warehouse

Layman, L.R.

1982-01-01

The nebuilizatlon of sample solutions Is a critical step In most flame or plasma atomic spectrometrlc methods. A novel nebulzatlon technique, based on a porous glass frit, has been Investigated. Basic operating parameters and characteristics have been studied to determine how thte new nebulizer may be applied to atomic spectrometrlc methods. The results of preliminary comparisons with pneumatic nebulizers Indicate several notable differences. The frit nebulizer produces a smaller droplet size distribution and has a higher sample transport efficiency. The mean droplet size te approximately 0.1 ??m, and up to 94% of the sample te converted to usable aerosol. The most significant limitations In the performance of the frit nebulizer are the stow sample equMbratton time and the requirement for wash cycles between samples. Loss of solute by surface adsorption and contamination of samples by leaching from the glass were both found to be limitations only In unusual cases. This nebulizer shows great promise where sample volume te limited or where measurements require long nebullzatlon times.

Direct filtration for recovery of Schistosoma mansoni cercariae in the field.

PubMed

Sandt, D G

1973-01-01

The recovery of schistosome cercariae from natural waters has been limited by variations in turbidity and in the accuracy of recovery with different techniques. A modification of the Rowan vacuum paper filtration method employing a battery-operated pumping system, a glass-silicone plate filter, and a specially designed filter holder is described and evaluated. Field tests on St Lucia indicate a mean filtration volume of 12.2 litres per filter at a mean turbidity of 20.3 Jackson turbidity units. Overall, 86% of the volumes filtered per filter were in excess of 6 litres. Particle size, rather than turbidity, was found to be the main factor influencing filter blockage, reading time, and accuracy. Recoveries of 0.01 cercaria (Schistosoma mansoni) per litre sampled were obtained, but the practical limit of the method is considered to be closer to 0.1 cercaria per litre sampled.

Signal enhancement for the sensitivity-limited solid state NMR experiments using a continuous, non-uniform acquisition scheme

NASA Astrophysics Data System (ADS)

Qiang, Wei

2011-12-01

We describe a sampling scheme for the two-dimensional (2D) solid state NMR experiments, which can be readily applied to the sensitivity-limited samples. The sampling scheme utilizes continuous, non-uniform sampling profile for the indirect dimension, i.e. the acquisition number decreases as a function of the evolution time ( t1) in the indirect dimension. For a beta amyloid (Aβ) fibril sample, we observed overall 40-50% signal enhancement by measuring the cross peak volume, while the cross peak linewidths remained comparable to the linewidths obtained by regular sampling and processing strategies. Both the linear and Gaussian decay functions for the acquisition numbers result in similar percentage of increment in signal. In addition, we demonstrated that this sampling approach can be applied with different dipolar recoupling approaches such as radiofrequency assisted diffusion (RAD) and finite-pulse radio-frequency-driven recoupling (fpRFDR). This sampling scheme is especially suitable for the sensitivity-limited samples which require long signal averaging for each t1 point, for instance the biological membrane proteins where only a small fraction of the sample is isotopically labeled.

Characterization and improvement of highly inclined optical sheet microscopy

NASA Astrophysics Data System (ADS)

Vignolini, T.; Curcio, V.; Gardini, L.; Capitanio, M.; Pavone, F. S.

2018-02-01

Highly Inclined and Laminated Optical sheet (HILO) microscopy is an optical technique that employs a highly inclined laser beam to illuminate the sample with a thin sheet of light that can be scanned through the sample volume1 . HILO is an efficient illumination technique when applied to fluorescence imaging of thick samples owing to the confined illumination volume that allows high contrast imaging while retaining deep scanning capability in a wide-field configuration. The restricted illumination volume is crucial to limit background fluorescence originating from portions of the sample far from the focal plane, especially in applications such as single molecule localization and super-resolution imaging2-4. Despite its widespread use, current literature lacks comprehensive reports of the actual advantages of HILO in these kinds of microscopies. Here, we thoroughly characterize the propagation of a highly inclined beam through fluorescently labeled samples and implement appropriate beam shaping for optimal application to single molecule and super-resolution imaging. We demonstrate that, by reducing the beam size along the refracted axis only, the excitation volume is consequently reduced while maintaining a field of view suitable for single cell imaging. We quantify the enhancement in signal-tobackground ratio with respect to the standard HILO technique and apply our illumination method to dSTORM superresolution imaging of the actin and vimentin cytoskeleton. We define the conditions to achieve localization precisions comparable to state-of-the-art reports, obtain a significant improvement in the image contrast, and enhanced plane selectivity within the sample volume due to the further confinement of the inclined beam.

Quantification of Protozoa and Viruses from Small Water Volumes

PubMed Central

Bonilla, J. Alfredo; Bonilla, Tonya D.; Abdelzaher, Amir M.; Scott, Troy M.; Lukasik, Jerzy; Solo-Gabriele, Helena M.; Palmer, Carol J.

2015-01-01

Large sample volumes are traditionally required for the analysis of waterborne pathogens. The need for large volumes greatly limits the number of samples that can be processed. The goals of this study were to compare extraction and detection procedures for quantifying protozoan parasites and viruses from small volumes of marine water. The intent was to evaluate a logistically simpler method of sample collection and processing that would facilitate direct pathogen measures as part of routine monitoring programs. Samples were collected simultaneously using a bilayer device with protozoa capture by size (top filter) and viruses capture by charge (bottom filter). Protozoan detection technologies utilized for recovery of Cryptosporidium spp. and Giardia spp. were qPCR and the more traditional immunomagnetic separation—IFA-microscopy, while virus (poliovirus) detection was based upon qPCR versus plaque assay. Filters were eluted using reagents consistent with the downstream detection technologies. Results showed higher mean recoveries using traditional detection methods over qPCR for Cryptosporidium (91% vs. 45%) and poliovirus (67% vs. 55%) whereas for Giardia the qPCR-based methods were characterized by higher mean recoveries (41% vs. 28%). Overall mean recoveries are considered high for all detection technologies. Results suggest that simultaneous filtration may be suitable for isolating different classes of pathogens from small marine water volumes. More research is needed to evaluate the suitability of this method for detecting pathogens at low ambient concentration levels. PMID:26114244

Quantification of Protozoa and Viruses from Small Water Volumes.

PubMed

Bonilla, J Alfredo; Bonilla, Tonya D; Abdelzaher, Amir M; Scott, Troy M; Lukasik, Jerzy; Solo-Gabriele, Helena M; Palmer, Carol J

2015-06-24

Large sample volumes are traditionally required for the analysis of waterborne pathogens. The need for large volumes greatly limits the number of samples that can be processed. The aims of this study were to compare extraction and detection procedures for quantifying protozoan parasites and viruses from small volumes of marine water. The intent was to evaluate a logistically simpler method of sample collection and processing that would facilitate direct pathogen measures as part of routine monitoring programs. Samples were collected simultaneously using a bilayer device with protozoa capture by size (top filter) and viruses capture by charge (bottom filter). Protozoan detection technologies utilized for recovery of Cryptosporidium spp. and Giardia spp. were qPCR and the more traditional immunomagnetic separation-IFA-microscopy, while virus (poliovirus) detection was based upon qPCR versus plaque assay. Filters were eluted using reagents consistent with the downstream detection technologies. Results showed higher mean recoveries using traditional detection methods over qPCR for Cryptosporidium (91% vs. 45%) and poliovirus (67% vs. 55%) whereas for Giardia the qPCR-based methods were characterized by higher mean recoveries (41% vs. 28%). Overall mean recoveries are considered high for all detection technologies. Results suggest that simultaneous filtration may be suitable for isolating different classes of pathogens from small marine water volumes. More research is needed to evaluate the suitability of this method for detecting pathogens at low ambient concentration levels.

How sampling and scale limit accuracy assessment of vegetation maps: A comment on Loehle et al. (2015)

Treesearch

David M. Bell; Matthew J. Gregory; Heather M. Roberts; Raymond J. Davis; Janet L. Ohmann

2015-01-01

Accuracy assessments of remote sensing products are necessary for identifying map strengths and weaknesses in scientific and management applications. However, not all accuracy assessments are created equal. Motivated by a recent study published in Forest Ecology and Management (Volume 342, pages 8–20), we explored the potential limitations of accuracy assessments...

Rugged large volume injection for sensitive capillary LC-MS environmental monitoring

NASA Astrophysics Data System (ADS)

Roberg-Larsen, Hanne; Abele, Silvija; Demir, Deniz; Dzabijeva, Diana; Amundsen, Sunniva F.; Wilson, Steven R.; Bartkevics, Vadims; Lundanes, Elsa

2017-08-01

A rugged and high throughput capillary column (cLC) LC-MS switching platform using large volume injection and on-line automatic filtration and filter back-flush (AFFL) solid phase extraction (SPE) for analysis of environmental water samples with minimal sample preparation is presented. Although narrow columns and on-line sample preparation are used in the platform, high ruggedness is achieved e.g. injection of 100 non-filtrated water samples would did not result in a pressure rise/clogging of the SPE/capillary columns (inner diameter 300 µm). In addition, satisfactory retention time stability and chromatographic resolution were also features of the system. The potential of the platform for environmental water samples was demonstrated with various pharmaceutical products, which had detection limits (LOD) in the 0.05 - 12.5 ng/L range. Between-day and within-day repeatability of selected analytes were < 20% RSD.

A Comparative Study of Serum Exosome Isolation Using Differential Ultracentrifugation and Three Commercial Reagents.

PubMed

Helwa, Inas; Cai, Jingwen; Drewry, Michelle D; Zimmerman, Arthur; Dinkins, Michael B; Khaled, Mariam Lotfy; Seremwe, Mutsa; Dismuke, W Michael; Bieberich, Erhard; Stamer, W Daniel; Hamrick, Mark W; Liu, Yutao

2017-01-01

Exosomes play a role in cell-to-cell signaling and serve as possible biomarkers. Isolating exosomes with reliable quality and substantial concentration is a major challenge. Our purpose is to compare the exosomes extracted by three different exosome isolation kits (miRCURY, ExoQuick, and Invitrogen Total Exosome Isolation Reagent) and differential ultracentrifugation (UC) using six different volumes of a non-cancerous human serum (5 ml, 1 ml, 500 μl, 250 μl, 100 μl, and 50 μl) and three different volumes (1 ml, 500 μl and 100 μl) of six individual commercial serum samples collected from human donors. The smaller starting volumes (100 μl and 50 μl) are used to mimic conditions of limited availability of heterogeneous biological samples. The isolated exosomes were characterized based upon size, quantity, zeta potential, CD63 and CD9 protein expression, and exosomal RNA (exRNA) quality and quantity using several complementary methods: nanoparticle tracking analysis (NTA) with ZetaView, western blot, transmission electron microscopy (TEM), the Agilent Bioanalyzer system, and droplet digital PCR (ddPCR). Our NTA results showed that all isolation techniques produced exosomes within the expected size range (40-150 nm). The three kits, though, produced a significantly higher yield (80-300 fold) of exosomes as compared to UC for all serum volumes, except 5 mL. We also found that exosomes isolated by the different techniques and serum volumes had similar zeta potentials to previous studies. Western blot analysis and TEM immunogold labelling confirmed the expression of two common exosomal protein markers, CD63 and CD9, in samples isolated by all techniques. All exosome isolations yielded high quality exRNA, containing mostly small RNA with a peak between 25 and 200 nucleotides in size. ddPCR results indicated that exosomes isolated from similar serum volumes but different isolation techniques rendered similar concentrations of two selected exRNA: hsa-miR-16 and hsa-miR-451. In summary, the three commercial exosome isolation kits are viable alternatives to UC, even when limited amounts of biological samples are available.

Quantifying viruses and bacteria in wastewater—Results, interpretation methods, and quality control

USGS Publications Warehouse

Francy, Donna S.; Stelzer, Erin A.; Bushon, Rebecca N.; Brady, Amie M.G.; Mailot, Brian E.; Spencer, Susan K.; Borchardt, Mark A.; Elber, Ashley G.; Riddell, Kimberly R.; Gellner, Terry M.

2011-01-01

Membrane bioreactors (MBR), used for wastewater treatment in Ohio and elsewhere in the United States, have pore sizes small enough to theoretically reduce concentrations of protozoa and bacteria, but not viruses. Sampling for viruses in wastewater is seldom done and not required. Instead, the bacterial indicators Escherichia coli (E. coli) and fecal coliforms are the required microbial measures of effluents for wastewater-discharge permits. Information is needed on the effectiveness of MBRs in removing human enteric viruses from wastewaters, particularly as compared to conventional wastewater treatment before and after disinfection. A total of 73 regular and 28 quality-control (QC) samples were collected at three MBR and two conventional wastewater plants in Ohio during 23 regular and 3 QC sampling trips in 2008-10. Samples were collected at various stages in the treatment processes and analyzed for bacterial indicators E. coli, fecal coliforms, and enterococci by membrane filtration; somatic and F-specific coliphage by the single agar layer (SAL) method; adenovirus, enterovirus, norovirus GI and GII, rotavirus, and hepatitis A virus by molecular methods; and viruses by cell culture. While addressing the main objective of the study-comparing removal of viruses and bacterial indicators in MBR and conventional plants-it was realized that work was needed to identify data analysis and quantification methods for interpreting enteric virus and QC data. Therefore, methods for quantifying viruses, qualifying results, and applying QC data to interpretations are described in this report. During each regular sampling trip, samples were collected (1) before conventional or MBR treatment (post-preliminary), (2) after secondary or MBR treatment (post-secondary or post-MBR), (3) after tertiary treatment (one conventional plant only), and (4) after disinfection (post-disinfection). Glass-wool fiber filtration was used to concentrate enteric viruses from large volumes, and small volume grab samples were collected for direct-plating analyses for bacterial indicators and coliphage. After filtration, the viruses were eluted from the filter and further concentrated. The final concentrated sample volume (FCSV) was used for enteric virus analysis by use of two methods-cell culture and a molecular method, polymerase chain reaction (PCR). Quantitative PCR (qPCR) for DNA viruses and quantitative reverse-transcriptase PCR (qRT-PCR) for RNA viruses were used in this study. To support data interpretations, the assay limit of detection (ALOD) was set for each virus assay and used to determine sample reporting limits (SRLs). For qPCR and qRT-PCR the ALOD was an estimated value because it was not established according to established method detection limit procedures. The SRLs were different for each sample because effective sample volumes (the volume of the original sample that was actually used in each analysis) were different for each sample. Effective sample volumes were much less than the original sample volumes because of reductions from processing steps and (or) from when dilutions were made to minimize the effects from PCR-inhibiting substances. Codes were used to further qualify the virus data and indicate the level of uncertainty associated with each measurement. Quality-control samples were used to support data interpretations. Field and laboratory blanks for bacteria, coliphage, and enteric viruses were all below detection, indicating that it was unlikely that samples were contaminated from equipment or processing procedures. The absolute value log differences (AVLDs) between concurrent replicate pairs were calculated to identify the variability associated with each measurement. For bacterial indicators and coliphage, the AVLD results indicated that concentrations <10 colony-forming units or plaque-forming units per 100 mL can differ between replicates by as much as 1 log, whereas higher concentrations can differ by as much as 0.3 log. The AVLD results for viruses indicated that differences between replicates can be as great as 1.2 log genomic copies per liter, regardless of the concentration of virus. Relatively large differences in molecular results for viruses between replicate pairs were likely due to lack of precision for samples with small effective volumes. Concentrations of E. coli, fecal coliforms, enterococci, and somatic and F-specific coliphage in post-secondary and post-tertiary samples in conventional plants were higher than those in post-MBR samples. In post-MBR and post-secondary samples, concentrations of somatic coliphage were higher than F-specific coliphage. In post-disinfection samples from two MBR plants (the third MBR plant had operational issues) and the ultraviolet conventional plant, concentrations for all bacterial indicators and coliphage were near or below detection; from the chlorine conventional plant, concentrations in post-disinfection samples were in the single or double digits. All of the plants met the National Pollutant Discharge Elimination System required effluent limits established for fecal coliforms. Norovirus GII and hepatitis A virus were not detected in any samples, and rotavirus was detected in one sample but could not be quantified. Adenovirus was found in 100 percent, enterovirus in over one-half, and norovirus GI in about one-half of post-preliminary wastewater samples. Adenovirus and enterovirus were detected throughout the treatment processes, and norovirus GI was detected less often than the other two enteric viruses. Culturable viruses were detected in post-preliminary samples and in only two post-treatment samples from the plant with operational issues.

The Surgeon Volume-outcome Relationship: Not Yet Ready for Policy.

PubMed

Modrall, J Gregory; Minter, Rebecca M; Minhajuddin, Abu; Eslava-Schmalbach, Javier; Joshi, Girish P; Patel, Shivani; Rosero, Eric B

2018-05-01

Increasing surgeon volume may improve outcomes for index operations. We hypothesized that there may be surrogate operative experiences that yield similar outcomes for surgeons with a low-volume experience with a specific index operation, such as esophagectomy. The relationship between surgeon volume and outcomes has potential implications for credentialing of surgeons. Restrictions of privileges based on surgeon volume are only reasonable if there is no substitute for direct experience with the index operation. This study was aimed at determining whether there are valid surrogates for direct experience with a sample index operation-open esophagectomy. The Nationwide Inpatient Sample (2003-2009) was utilized. Surgeons were stratified into low and high-volume groups based on annual volume of esophagectomy. Surrogate volume was defined as the aggregate annual volume per surgeon of upper gastrointestinal operations including excision of esophageal diverticulum, gastrectomy, gastroduodenectomy, and repair of diaphragmatic hernia. In all, 26,795 esophagectomies were performed nationwide (2003-2009), with a crude inhospital mortality rate of 5.2%. Inhospital mortality decreased with increasing volume of esophagectomies performed annually: 7.7% and 3.8% for low and high-volume surgeons, respectively (P < 0.0001). Among surgeons with a low-volume esophagectomy experience, increasing volume of surrogate operations improved the outcomes observed for esophagectomy: 9.7%, 7.1%, and 4.3% for low, medium, and high-surrogate-volume surgeons, respectively (P = 0.016). Both operation-specific volume and surrogate volume are significant predictors of inhospital mortality for esophagectomy. Based on these observations, it would be premature to limit hospital privileges based solely on operation-specific surgeon volume criteria.

Board-Foot and cubic-foot volume tables for Alaska-cedar in southeast Alaska.

Treesearch

Donald J. DeMars

1996-01-01

Four tables give cubic-foot and board-foot volume estimates for Alaska-cedar given breast-height diameter outside bark (DBHOB) and either total tree height or number of logs to a 6-inch top. The values for DBHOB and total tree height (or number of logs in the tree) that are in the tables have been limited to the ranges these variables had in the sample data.

Board-foot and cubic-foot volume tables for western red cedar in southeast Alaska.

Treesearch

Donald J. DeMars

1996-01-01

Four tables give cubic-foot and board-foot volume estimates for western redcedar given breast height diameter outside bark (DBHOB) and either total tree height or number of logs to a 6-inch top. The values for DBHOB and total tree height (or number of logs in the tree) that are in the tables have been limited to the ranges these variables had in the sample data.

40 CFR Table 2 to Subpart Ffff of... - Model Rule-Emission Limitations

Code of Federal Regulations, 2011 CFR

2011-07-01

... micrograms per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Method 29 of appendix A of this part. 2. Carbon monoxide 40 parts per million by dry volume 3-run average (1 hour minimum sample time per run during performance test), and 12-hour rolling averages measured using CEMS b...

40 CFR Table 1 to Subpart Cccc of... - Emission Limitations

Code of Federal Regulations, 2011 CFR

2011-07-01

... per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Performance test (Method 29 of appendix A of this part). Carbon monoxide 157 parts per million by dry volume 3-run average (1 hour minimum sample time per run) Performance test (Method 10, 10A, or 10B of appendix A of this...

40 CFR Table 2 to Subpart Ffff of... - Model Rule-Emission Limitations

Code of Federal Regulations, 2010 CFR

2010-07-01

... micrograms per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Method 29 of appendix A of this part. 2. Carbon monoxide 40 parts per million by dry volume 3-run average (1 hour minimum sample time per run during performance test), and 12-hour rolling averages measured using CEMS b...

40 CFR Table 1 to Subpart Cccc of... - Emission Limitations

Code of Federal Regulations, 2010 CFR

2010-07-01

... per dry standard cubic meter 3-run average (1 hour minimum sample time per run) Performance test (Method 29 of appendix A of this part). Carbon monoxide 157 parts per million by dry volume 3-run average (1 hour minimum sample time per run) Performance test (Method 10, 10A, or 10B of appendix A of this...

40 CFR Table 2 to Subpart Dddd of... - Model Rule-Emission Limitations

Code of Federal Regulations, 2010 CFR

2010-07-01

... meter 3-run average (1 hour minimum sample time per run) Performance test (Method 29 of appendix A of this part) Carbon monoxide 157 parts per million by dry volume 3-run average (1 hour minimum sample time per run) Performance test (Method 10, 10A, or 10B, of appendix A of this part) Dioxins/furans...

Simultaneous unbiased estimates of multiple downed wood attributes in perpendicular distance sampling

Treesearch

Mark J. Ducey; Jeffrey H. Gove; Harry T. Valentine

2008-01-01

Perpendicular distance sampling (PDS) is a fast probability-proportional-to-size method for inventory of downed wood. However, previous development of PDS had limited the method to estimating only one variable (such as volume per hectare, or surface area per hectare) at a time. Here, we develop a general design-unbiased estimator for PDS. We then show how that...

VizieR Online Data Catalog: Search for extraterrestrial intelligence (Isaacson+, 2017)

NASA Astrophysics Data System (ADS)

Isaacson, H.; Siemion, A. P. V.; Marcy, G. W.; Lebofsky, M.; Price, D. C.; MacMahon, D.; Croft, S.; Deboer, D.; Hickish, J.; Werthimer, D.; Sheikh, S.; Hellbourg, G.; Enriquez, J. E.

2017-08-01

The stellar sample is defined by two selection criteria. The first is a volume-limited sample of stars within 5pc of the Sun. The second is a spectral class complete sample consisting of stars across the main sequence and some giant branch stars, all within 50pc. We combined the two sub-samples (5pc and 5-50pc) to produce the final set of 1709 target stars that are listed in Table 1. (1 data file).

A rapid, highly sensitive and culture-free detection of pathogens from blood by positive enrichment.

PubMed

Vutukuru, Manjula Ramya; Sharma, Divya Khandige; Ragavendar, M S; Schmolke, Susanne; Huang, Yiwei; Gumbrecht, Walter; Mitra, Nivedita

2016-12-01

Molecular diagnostics is a promising alternative to culture based methods for the detection of bloodstream infections, notably due to its overall lower turnaround time when starting directly from patient samples. Whole blood is usually the starting diagnostic sample in suspected bloodstream infections. The detection of low concentrations of pathogens in blood using a molecular assay necessitates a fairly high starting volume of blood sample in the range of 5-10mL. This large volume of blood sample has a substantial accompanying human genomic content that interferes with pathogen detection. In this study, we have established a workflow using magnetic beads coated with Apolipoprotein H that makes it possible to concentrate pathogens from a 5.0mL whole blood sample, thereby enriching pathogens from whole blood background and also reducing the sample volume to ~200μL or less. We have also demonstrated that this method of enrichment allows detection of 1CFU/mL of Escherichia coli, Enterococcus gallinarum and Candida tropicalis from 5mL blood using quantitative PCR; a detection limit that is not possible in unenriched samples. The enrichment method demonstrated here took 30min to complete and can be easily integrated with various downstream molecular and microbiological techniques. Copyright © 2016 Elsevier B.V. All rights reserved.

Acoustically levitated droplets: a contactless sampling method for fluorescence studies.

PubMed

Leiterer, Jork; Grabolle, Markus; Rurack, Knut; Resch-Genger, Ute; Ziegler, Jan; Nann, Thomas; Panne, Ulrich

2008-01-01

Acoustic levitation is used as a new tool to study concentration-dependent processes in fluorescence spectroscopy. With this technique, small amounts of liquid and solid samples can be measured without the need for sample supports or containers, which often limits signal acquisition and can even alter sample properties due to interactions with the support material. We demonstrate that, because of the small sample volume, fluorescence measurements at high concentrations of an organic dye are possible without the limitation of inner-filter effects, which hamper such experiments in conventional, cuvette-based measurements. Furthermore, we show that acoustic levitation of liquid samples provides an experimentally simple way to study distance-dependent fluorescence modulations in semiconductor nanocrystals. The evaporation of the solvent during levitation leads to a continuous increase of solute concentration and can easily be monitored by laser-induced fluorescence.

Methods for the preparation and analysis of solids and suspended solids for methylmercury

USGS Publications Warehouse

DeWild, John F.; Olund, Shane D.; Olson, Mark L.; Tate, Michael T.

2004-01-01

This report presents the methods and method performance data for the determination of methylmercury concentrations in solids and suspended solids. Using the methods outlined here, the U.S. Geological Survey's Wisconsin District Mercury Laboratory can consistently detect methylmercury in solids and suspended solids at environmentally relevant concentrations. Solids can be analyzed wet or freeze dried with a minimum detection limit of 0.08 ng/g (as-processed). Suspended solids must first be isolated from aqueous matrices by filtration. The minimum detection limit for suspended solids is 0.01 ng per filter resulting in a minimum reporting limit ranging from 0.2 ng/L for a 0.05 L filtered volume to 0.01 ng/L for a 1.0 L filtered volume. Maximum concentrations for both matrices can be extended to cover nearly any amount of methylmercury by limiting sample size.

40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

Code of Federal Regulations, 2011 CFR

2011-07-01

... thoroughly mixed sample. Allow to settle undisturbed for 45 minutes. Gently stir along the inside surface of the cone with a stirring rod. Allow to settle undisturbed for 15 minutes longer. Record the volume of...

40 CFR 434.64 - Procedure and method detection limit for measurement of settleable solids.

Code of Federal Regulations, 2010 CFR

2010-07-01

... thoroughly mixed sample. Allow to settle undisturbed for 45 minutes. Gently stir along the inside surface of the cone with a stirring rod. Allow to settle undisturbed for 15 minutes longer. Record the volume of...

Robotic liquid handling and automation in epigenetics.

PubMed

Gaisford, Wendy

2012-10-01

Automated liquid-handling robots and high-throughput screening (HTS) are widely used in the pharmaceutical industry for the screening of large compound libraries, small molecules for activity against disease-relevant target pathways, or proteins. HTS robots capable of low-volume dispensing reduce assay setup times and provide highly accurate and reproducible dispensing, minimizing variation between sample replicates and eliminating the potential for manual error. Low-volume automated nanoliter dispensers ensure accuracy of pipetting within volume ranges that are difficult to achieve manually. In addition, they have the ability to potentially expand the range of screening conditions from often limited amounts of valuable sample, as well as reduce the usage of expensive reagents. The ability to accurately dispense lower volumes provides the potential to achieve a greater amount of information than could be otherwise achieved using manual dispensing technology. With the emergence of the field of epigenetics, an increasing number of drug discovery companies are beginning to screen compound libraries against a range of epigenetic targets. This review discusses the potential for the use of low-volume liquid handling robots, for molecular biological applications such as quantitative PCR and epigenetics.

Using large volume samplers for the monitoring of particle bound micro pollutants in rivers

NASA Astrophysics Data System (ADS)

Kittlaus, Steffen; Fuchs, Stephan

2015-04-01

The requirements of the WFD as well as substance emission modelling at the river basin scale require stable monitoring data for micro pollutants. The monitoring concepts applied by the local authorities as well as by many scientists use single sampling techniques. Samples from water bodies are usually taken in volumes of about one litre and depending on predetermined time steps or through discharge thresholds. For predominantly particle bound micro pollutants the small sample size of about one litre results in a very small amount of suspended particles. To measure micro pollutant concentrations in these samples is demanding and results in a high uncertainty of the measured concentrations, if the concentration is above the detection limit in the first place. In many monitoring programs most of the measured values were below the detection limit. This results in a high uncertainty if river loads were calculated from these data sets. The authors propose a different approach to gain stable concentration values for particle bound micro pollutants from river monitoring: A mixed sample of about 1000 L was pumped in a tank with a dirty-water pump. The sampling usually is done discharge dependant by using a gauge signal as input for the control unit. After the discharge event is over or the tank is fully filled, the suspended solids settle in the tank for 2 days. After this time a clear separation of water and solids can be shown. A sample (1 L) from the water phase and the total mass of the settled solids (about 10 L) are taken to the laboratory for analysis. While the micro pollutants can't hardly be detected in the water phase, the signal from the sediment is high above the detection limit, thus certain and very stable. From the pollutant concentration in the solid phase and the total tank volume the initial pollutant concentration in the sample can be calculated. If the concentration in the water phase is detectable, it can be used to correct the total load. This relatively low cost approach (less costs for analysis because of small sample number) allows to quantify the pollutant load, to derive dissolved-solid partition coefficients and to quantify the pollutant load in different particle size classes.

Normative morphometric data for cerebral cortical areas over the lifetime of the adult human brain.

PubMed

Potvin, Olivier; Dieumegarde, Louis; Duchesne, Simon

2017-08-01

Proper normative data of anatomical measurements of cortical regions, allowing to quantify brain abnormalities, are lacking. We developed norms for regional cortical surface areas, thicknesses, and volumes based on cross-sectional MRI scans from 2713 healthy individuals aged 18 to 94 years using 23 samples provided by 21 independent research groups. The segmentation was conducted using FreeSurfer, a widely used and freely available automated segmentation software. Models predicting regional cortical estimates of each hemisphere were produced using age, sex, estimated total intracranial volume (eTIV), scanner manufacturer, magnetic field strength, and interactions as predictors. The explained variance for the left/right cortex was 76%/76% for surface area, 43%/42% for thickness, and 80%/80% for volume. The mean explained variance for all regions was 41% for surface areas, 27% for thicknesses, and 46% for volumes. Age, sex and eTIV predicted most of the explained variance for surface areas and volumes while age was the main predictors for thicknesses. Scanner characteristics generally predicted a limited amount of variance, but this effect was stronger for thicknesses than surface areas and volumes. For new individuals, estimates of their expected surface area, thickness and volume based on their characteristics and the scanner characteristics can be obtained using the derived formulas, as well as Z score effect sizes denoting the extent of the deviation from the normative sample. Models predicting normative values were validated in independent samples of healthy adults, showing satisfactory validation R 2 . Deviations from the normative sample were measured in individuals with mild Alzheimer's disease and schizophrenia and expected patterns of deviations were observed. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

Abdominal fat volume estimation by stereology on CT: a comparison with manual planimetry.

PubMed

Manios, G E; Mazonakis, M; Voulgaris, C; Karantanas, A; Damilakis, J

2016-03-01

To deploy and evaluate a stereological point-counting technique on abdominal CT for the estimation of visceral (VAF) and subcutaneous abdominal fat (SAF) volumes. Stereological volume estimations based on point counting and systematic sampling were performed on images from 14 consecutive patients who had undergone abdominal CT. For the optimization of the method, five sampling intensities in combination with 100 and 200 points were tested. The optimum stereological measurements were compared with VAF and SAF volumes derived by the standard technique of manual planimetry on the same scans. Optimization analysis showed that the selection of 200 points along with the sampling intensity 1/8 provided efficient volume estimations in less than 4 min for VAF and SAF together. The optimized stereology showed strong correlation with planimetry (VAF: r = 0.98; SAF: r = 0.98). No statistical differences were found between the two methods (VAF: P = 0.81; SAF: P = 0.83). The 95% limits of agreement were also acceptable (VAF: -16.5%, 16.1%; SAF: -10.8%, 10.7%) and the repeatability of stereology was good (VAF: CV = 4.5%, SAF: CV = 3.2%). Stereology may be successfully applied to CT images for the efficient estimation of abdominal fat volume and may constitute a good alternative to the conventional planimetric technique. Abdominal obesity is associated with increased risk of disease and mortality. Stereology may quantify visceral and subcutaneous abdominal fat accurately and consistently. The application of stereology to estimating abdominal volume fat reduces processing time. Stereology is an efficient alternative method for estimating abdominal fat volume.

DNA methylation profiling of genomic DNA isolated from urine in diabetic chronic kidney disease: A pilot study

PubMed Central

Sexton-Oates, Alexandra; Carmody, Jake; Ekinci, Elif I.; Dwyer, Karen M.; Saffery, Richard

2018-01-01

Aim To characterise the genomic DNA (gDNA) yield from urine and quality of derived methylation data generated from the widely used Illuminia Infinium MethylationEPIC (HM850K) platform and compare this with buffy coat samples. Background DNA methylation is the most widely studied epigenetic mark and variations in DNA methylation profile have been implicated in diabetes which affects approximately 415 million people worldwide. Methods QIAamp Viral RNA Mini Kit and QIAamp DNA micro kit were used to extract DNA from frozen and fresh urine samples as well as increasing volumes of fresh urine. Matched buffy coats to the frozen urine were also obtained and DNA was extracted from the buffy coats using the QIAamp DNA Mini Kit. Genomic DNA of greater concentration than 20μg/ml were used for methylation analysis using the HM850K array. Results Irrespective of extraction technique or the use of fresh versus frozen urine samples, limited genomic DNA was obtained using a starting sample volume of 5ml (0–0.86μg/mL). In order to optimize the yield, we increased starting volumes to 50ml fresh urine, which yielded only 0–9.66μg/mL A different kit, QIAamp DNA Micro Kit, was trialled in six fresh urine samples and ten frozen urine samples with inadequate DNA yields from 0–17.7μg/mL and 0–1.6μg/mL respectively. Sufficient genomic DNA was obtained from only 4 of the initial 41 frozen urine samples (10%) for DNA methylation profiling. In comparison, all four buffy coat samples (100%) provided sufficient genomic DNA. Conclusion High quality data can be obtained provided a sufficient yield of genomic DNA is isolated. Despite optimizing various extraction methodologies, the modest amount of genomic DNA derived from urine, may limit the generalisability of this approach for the identification of DNA methylation biomarkers of chronic diabetic kidney disease. PMID:29462136

DNA methylation profiling of genomic DNA isolated from urine in diabetic chronic kidney disease: A pilot study.

PubMed

Lecamwasam, Ashani; Sexton-Oates, Alexandra; Carmody, Jake; Ekinci, Elif I; Dwyer, Karen M; Saffery, Richard

2018-01-01

To characterise the genomic DNA (gDNA) yield from urine and quality of derived methylation data generated from the widely used Illuminia Infinium MethylationEPIC (HM850K) platform and compare this with buffy coat samples. DNA methylation is the most widely studied epigenetic mark and variations in DNA methylation profile have been implicated in diabetes which affects approximately 415 million people worldwide. QIAamp Viral RNA Mini Kit and QIAamp DNA micro kit were used to extract DNA from frozen and fresh urine samples as well as increasing volumes of fresh urine. Matched buffy coats to the frozen urine were also obtained and DNA was extracted from the buffy coats using the QIAamp DNA Mini Kit. Genomic DNA of greater concentration than 20μg/ml were used for methylation analysis using the HM850K array. Irrespective of extraction technique or the use of fresh versus frozen urine samples, limited genomic DNA was obtained using a starting sample volume of 5ml (0-0.86μg/mL). In order to optimize the yield, we increased starting volumes to 50ml fresh urine, which yielded only 0-9.66μg/mL A different kit, QIAamp DNA Micro Kit, was trialled in six fresh urine samples and ten frozen urine samples with inadequate DNA yields from 0-17.7μg/mL and 0-1.6μg/mL respectively. Sufficient genomic DNA was obtained from only 4 of the initial 41 frozen urine samples (10%) for DNA methylation profiling. In comparison, all four buffy coat samples (100%) provided sufficient genomic DNA. High quality data can be obtained provided a sufficient yield of genomic DNA is isolated. Despite optimizing various extraction methodologies, the modest amount of genomic DNA derived from urine, may limit the generalisability of this approach for the identification of DNA methylation biomarkers of chronic diabetic kidney disease.

Sample preparation and liquid chromatography-tandem mass spectrometry for multiple steroids in mammalian and avian circulation.

PubMed

Koren, Lee; Ng, Ella S M; Soma, Kiran K; Wynne-Edwards, Katherine E

2012-01-01

Blood samples from wild mammals and birds are often limited in volume, allowing researchers to quantify only one or two steroids from a single sample by immunoassays. In addition, wildlife serum or plasma samples are often lipemic, necessitating stringent sample preparation. Here, we validated sample preparation for simultaneous liquid chromatography--tandem mass spectrometry (LC-MS/MS) quantitation of cortisol, corticosterone, 11-deoxycortisol, dehydroepiandrosterone (DHEA), 17β-estradiol, progesterone, 17α-hydroxyprogesterone and testosterone from diverse mammalian (7 species) and avian (5 species) samples. Using 100 µL of serum or plasma, we quantified (signal-to-noise (S/N) ratio ≥ 10) 4-7 steroids depending on the species and sample, without derivatization. Steroids were extracted from serum or plasma using automated solid-phase extraction where samples were loaded onto C18 columns, washed with water and hexane, and then eluted with ethyl acetate. Quantitation by LC-MS/MS was done in positive ion, multiple reaction-monitoring (MRM) mode with an atmospheric pressure chemical ionization (APCI) source and heated nebulizer (500°C). Deuterated steroids served as internal standards and run time was 15 minutes. Extraction recoveries were 87-101% for the 8 analytes, and all intra- and inter-run CVs were ≤ 8.25%. This quantitation method yields good recoveries with variable lipid-content samples, avoids antibody cross-reactivity issues, and delivers results for multiple steroids. Thus, this method can enrich datasets by providing simultaneous quantitation of multiple steroids, and allow researchers to reimagine the hypotheses that could be tested with their volume-limited, lipemic, wildlife samples.

Liquid Metering Centrifuge Sticks (LMCS): A Centrifugal Approach to Metering Known Sample Volumes for Colorimetric Solid Phase Extraction (C-SPE)

NASA Technical Reports Server (NTRS)

Gazda, Daniel B.; Schultz, John R.; Clarke, Mark S.

2007-01-01

Phase separation is one of the most significant obstacles encountered during the development of analytical methods for water quality monitoring in spacecraft environments. Removing air bubbles from water samples prior to analysis is a routine task on earth; however, in the absence of gravity, this routine task becomes extremely difficult. This paper details the development and initial ground testing of liquid metering centrifuge sticks (LMCS), devices designed to collect and meter a known volume of bubble-free water in microgravity. The LMCS uses centrifugal force to eliminate entrapped air and reproducibly meter liquid sample volumes for analysis with Colorimetric Solid Phase Extraction (C-SPE). C-SPE is a sorption-spectrophotometric platform that is being developed as a potential spacecraft water quality monitoring system. C-SPE utilizes solid phase extraction membranes impregnated with analyte-specific colorimetric reagents to concentrate and complex target analytes in spacecraft water samples. The mass of analyte extracted from the water sample is determined using diffuse reflectance (DR) data collected from the membrane surface and an analyte-specific calibration curve. The analyte concentration can then be calculated from the mass of extracted analyte and the volume of the sample analyzed. Previous flight experiments conducted in microgravity conditions aboard the NASA KC-135 aircraft demonstrated that the inability to collect and meter a known volume of water using a syringe was a limiting factor in the accuracy of C-SPE measurements. Herein, results obtained from ground based C-SPE experiments using ionic silver as a test analyte and either the LMCS or syringes for sample metering are compared to evaluate the performance of the LMCS. These results indicate very good agreement between the two sample metering methods and clearly illustrate the potential of utilizing centrifugal forces to achieve phase separation and metering of water samples in microgravity.

40 CFR Table 6 to Subpart Dddd of... - Model Rule-Emission Limitations That Apply to Incinerators on and After [Date to be specified in...

Code of Federal Regulations, 2013 CFR

2013-07-01

... per million dry volume 3-run average (1 hour minimum sample time per run) Performance test (Method 10..., appendix A-3 or appendix A-8). Sulfur dioxide 11 parts per million dry volume 3-run average (1 hour minimum... Apply to Incinerators on and After [Date to be specified in state plan] a 6 Table 6 to Subpart DDDD of...

40 CFR Table 6 to Subpart Dddd of... - Model Rule-Emission Limitations That Apply to Incinerators on and After [Date to be specified in...

Code of Federal Regulations, 2014 CFR

2014-07-01

... per million dry volume 3-run average (1 hour minimum sample time per run) Performance test (Method 10..., appendix A-3 or appendix A-8). Sulfur dioxide 11 parts per million dry volume 3-run average (1 hour minimum... Apply to Incinerators on and After [Date to be specified in state plan] a 6 Table 6 to Subpart DDDD of...

Microvolume Protein Concentration Determination using the NanoDrop 2000c Spectrophotometer

PubMed Central

Desjardins, Philippe; Hansen, Joel B.; Allen, Michael

2009-01-01

Traditional spectrophotometry requires placing samples into cuvettes or capillaries. This is often impractical due to the limited sample volumes often used for protein analysis. The Thermo Scientific NanoDrop 2000c Spectrophotometer solves this issue with an innovative sample retention system that holds microvolume samples between two measurement surfaces using the surface tension properties of liquids, enabling the quantification of samples in volumes as low as 0.5-2 μL. The elimination of cuvettes or capillaries allows real time changes in path length, which reduces the measurement time while greatly increasing the dynamic range of protein concentrations that can be measured. The need for dilutions is also eliminated, and preparations for sample quantification are relatively easy as the measurement surfaces can be simply wiped with laboratory wipe. This video article presents modifications to traditional protein concentration determination methods for quantification of microvolume amounts of protein using A280 absorbance readings or the BCA colorimetric assay. PMID:19890248

Fast automated dual-syringe based dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry for the determination of polycyclic aromatic hydrocarbons in environmental water samples.

PubMed

Guo, Liang; Tan, Shufang; Li, Xiao; Lee, Hian Kee

2016-03-18

An automated procedure, combining low density solvent based solvent demulsification dispersive liquid-liquid microextraction (DLLME) with gas chromatography-mass spectrometry analysis, was developed for the determination of polycyclic aromatic hydrocarbons (PAHs) in environmental water samples. Capitalizing on a two-rail commercial autosampler, fast solvent transfer using a large volume syringe dedicated to the DLLME process, and convenient extract collection using a small volume microsyringe for better GC performance were enabled. Extraction parameters including the type and volume of extraction solvent, the type and volume of dispersive solvent and demulsification solvent, extraction and demulsification time, and the speed of solvent injection were investigated and optimized. Under the optimized conditions, the linearity ranged from 0.1 to 50 μg/L, 0.2 to 50 μg/L, and 0.5 to 50 μg/L, depending on the analytes. Limits of detection were determined to be between 0.023 and 0.058 μg/L. The method was applied to determine PAHs in environmental water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Plenoptic Imaging of a Three Dimensional Cold Atom Cloud

NASA Astrophysics Data System (ADS)

Lott, Gordon

2017-04-01

A plenoptic imaging system is capable of sampling the rays of light in a volume, both spatially and angularly, providing information about the three dimensional (3D) volume being imaged. The extraction of the 3D structure of a cold atom cloud is demonstrated, using a single plenoptic camera and a single image. The reconstruction is tested against a reference image and the results discussed along with the capabilities and limitations of the imaging system. This capability is useful when the 3D distribution of the atoms is desired, such as determining the shape of an atom trap, particularly when there is limited optical access. Gratefully acknowledge support from AFRL.

Distance-limited perpendicular distance sampling for coarse woody debris: theory and field results

Treesearch

Mark J. Ducey; Micheal S. Williams; Jeffrey H. Gove; Steven Roberge; Robert S. Kenning

2013-01-01

Coarse woody debris (CWD) has been identified as an important component in many forest ecosystem processes. Perpendicular distance sampling (PDS) is one of the several efficient new methods that have been proposed for CWD inventory. One drawback of PDS is that the maximum search distance can be very large, especially if CWD diameters are large or the volume factor...

Effect of variable rates of daily sampling of fly larvae on decomposition and carrion insect community assembly: implications for forensic entomology field study protocols.

PubMed

Michaud, Jean-Philippe; Moreau, Gaétan

2013-07-01

Experimental protocols in forensic entomology successional field studies generally involve daily sampling of insects to document temporal changes in species composition on animal carcasses. One challenge with that method has been to adjust the sampling intensity to obtain the best representation of the community present without affecting the said community. To this date, little is known about how such investigator perturbations affect decomposition-related processes. Here, we investigated how different levels of daily sampling of fly eggs and fly larvae affected, over time, carcass decomposition rate and the carrion insect community. Results indicated that a daily sampling of <5% of the egg and larvae volumes present on a carcass, a sampling intensity believed to be consistent with current accepted practices in successional field studies, had little effect overall. Higher sampling intensities, however, slowed down carcass decomposition, affected the abundance of certain carrion insects, and caused an increase in the volume of eggs laid by dipterans. This study suggests that the carrion insect community not only has a limited resilience to recurrent perturbations but that a daily sampling intensity equal to or <5% of the egg and larvae volumes appears adequate to ensure that the system is representative of unsampled conditions. Hence we propose that this threshold be accepted as best practice in future forensic entomology successional field studies.

Analysis of polycyclic aromatic hydrocarbons in water and beverages using membrane-assisted solvent extraction in combination with large volume injection-gas chromatography-mass spectrometric detection.

PubMed

Rodil, Rosario; Schellin, Manuela; Popp, Peter

2007-09-07

Membrane-assisted solvent extraction (MASE) in combination with large volume injection-gas chromatography-mass spectrometry (LVI-GC-MS) was applied for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. The MASE conditions were optimized for achieving high enrichment of the analytes from aqueous samples, in terms of extraction conditions (shaking speed, extraction temperature and time), extraction solvent and composition (ionic strength, sample pH and presence of organic solvent). Parameters like linearity and reproducibility of the procedure were determined. The extraction efficiency was above 65% for all the analytes and the relative standard deviation (RSD) for five consecutive extractions ranged from 6 to 18%. At optimized conditions detection limits at the ng/L level were achieved. The effectiveness of the method was tested by analyzing real samples, such as river water, apple juice, red wine and milk.

Standardization and performance evaluation of "modified" and "ultrasensitive" versions of the Abbott RealTime HIV-1 assay, adapted to quantify minimal residual viremia.

PubMed

Amendola, Alessandra; Bloisi, Maria; Marsella, Patrizia; Sabatini, Rosella; Bibbò, Angela; Angeletti, Claudio; Capobianchi, Maria Rosaria

2011-09-01

Numerous studies investigating clinical significance of HIV-1 minimal residual viremia (MRV) suggest potential utility of assays more sensitive than those routinely used to monitor viral suppression. However currently available methods, based on different technologies, show great variation in detection limit and input plasma volume, and generally suffer from lack of standardization. In order to establish new tools suitable for routine quantification of minimal residual viremia in patients under virological suppression, some modifications were introduced into standard procedure of the Abbott RealTime HIV-1 assay leading to a "modified" and an "ultrasensitive" protocols. The following modifications were introduced: calibration curve extended towards low HIV-1 RNA concentration; 4 fold increased sample volume by concentrating starting material; reduced volume of internal control; adoption of "open-mode" software for quantification. Analytical performances were evaluated using the HIV-1 RNA Working Reagent 1 for NAT assays (NIBSC). Both tests were applied to clinical samples from virologically suppressed patients. The "modified" and the "ultrasensitive" configurations of the assay reached a limit of detection of 18.8 (95% CI: 11.1-51.0 cp/mL) and 4.8 cp/mL (95% CI: 2.6-9.1 cp/mL), respectively, with high precision and accuracy. In clinical samples from virologically suppressed patients, "modified" and "ultrasensitive" protocols allowed to detect and quantify HIV RNA in 12.7% and 46.6%, respectively, of samples resulted "not-detectable", and in 70.0% and 69.5%, respectively, of samples "detected <40 cp/mL" in the standard assay. The "modified" and "ultrasensitive" assays are precise and accurate, and easily adoptable in routine diagnostic laboratories for measuring MRV. Copyright © 2011 Elsevier B.V. All rights reserved.

Nanopore sensing at ultra-low concentrations using single-molecule dielectrophoretic trapping

NASA Astrophysics Data System (ADS)

Freedman, Kevin J.; Otto, Lauren M.; Ivanov, Aleksandar P.; Barik, Avijit; Oh, Sang-Hyun; Edel, Joshua B.

2016-01-01

Single-molecule techniques are being developed with the exciting prospect of revolutionizing the healthcare industry by generating vast amounts of genetic and proteomic data. One exceptionally promising route is in the use of nanopore sensors. However, a well-known complexity is that detection and capture is predominantly diffusion limited. This problem is compounded when taking into account the capture volume of a nanopore, typically 108-1010 times smaller than the sample volume. To rectify this disproportionate ratio, we demonstrate a simple, yet powerful, method based on coupling single-molecule dielectrophoretic trapping to nanopore sensing. We show that DNA can be captured from a controllable, but typically much larger, volume and concentrated at the tip of a metallic nanopore. This enables the detection of single molecules at concentrations as low as 5 fM, which is approximately a 103 reduction in the limit of detection compared with existing methods, while still maintaining efficient throughput.

Video-rate volumetric functional imaging of the brain at synaptic resolution.

PubMed

Lu, Rongwen; Sun, Wenzhi; Liang, Yajie; Kerlin, Aaron; Bierfeld, Jens; Seelig, Johannes D; Wilson, Daniel E; Scholl, Benjamin; Mohar, Boaz; Tanimoto, Masashi; Koyama, Minoru; Fitzpatrick, David; Orger, Michael B; Ji, Na

2017-04-01

Neurons and neural networks often extend hundreds of micrometers in three dimensions. Capturing the calcium transients associated with their activity requires volume imaging methods with subsecond temporal resolution. Such speed is a challenge for conventional two-photon laser-scanning microscopy, because it depends on serial focal scanning in 3D and indicators with limited brightness. Here we present an optical module that is easily integrated into standard two-photon laser-scanning microscopes to generate an axially elongated Bessel focus, which when scanned in 2D turns frame rate into volume rate. We demonstrated the power of this approach in enabling discoveries for neurobiology by imaging the calcium dynamics of volumes of neurons and synapses in fruit flies, zebrafish larvae, mice and ferrets in vivo. Calcium signals in objects as small as dendritic spines could be resolved at video rates, provided that the samples were sparsely labeled to limit overlap in their axially projected images.

Brain volumes in psychotic youth with schizophrenia and mood disorders

PubMed Central

El-Sayed, Mohamed; Steen, R. Grant; Poe, Michele D.; Bethea, T. Carter; Gerig, Guido; Lieberman, Jeffrey; Sikich, Linmarie

2010-01-01

Background We sought to test the hypothesis that deficits in grey matter volume are characteristic of psychotic youth with early-onset schizophrenia-spectrum disorders (EOSS) but not of psychotic youth with early-onset mood disorders (EOMD). Methods We used magnetic resonance imaging to examine brain volume in 24 psychotic youth (13 male, 11 female) with EOSS (n = 12) or EOMD (n = 12) and 17 healthy controls (10 male, 7 female). We measured the volume of grey and white matter using an automated segmentation program. Results After adjustment for age and intracranial volume, whole brain volume was lower in the EOSS patients than in the healthy controls (p = 0.001) and EOMD patients (p = 0.002). The EOSS patients had a deficit in grey matter volume (p = 0.005), especially in the frontal (p = 0.003) and parietal (p = 0.006) lobes, with no significant differences in white matter volume. Limitations The main limitations of our study were its small sample size and the inclusion of patients with depression and mania in the affective group. Conclusion Adolescents with EOSS have grey matter deficits compared with healthy controls and psychotic adolescents with EOMD. Our results suggest that grey matter deficits are not generally associated with psychosis but may be specifically associated with schizophrenia. Larger studies with consistent methods are needed to reconcile the contradictory findings among imaging studies involving psychotic youth. PMID:20569649

Strategies for Analyzing Sub-Micrometer Features with the FE-EPMA

NASA Astrophysics Data System (ADS)

McSwiggen, P.; Armstrong, J. T.; Nielsen, C.

2013-12-01

Changes in column design and electronics, as well as new types of spectrometers and analyzing crystals, have significantly advanced electron microprobes, in terms of stability, reproducibility and detection limits. A major advance in spatial resolution has occurred through the use of the field emission electron gun. The spatial resolution of an analysis is controlled by the diameter of the electron beam and the amount of scatter that takes place within the sample. The beam diameter is controlled by the column and type of electron gun being used. The accelerating voltage and the average atomic number/density of the sample control the amount of electron scatter within the sample. However a large electron interaction volume does not necessarily mean a large analytical volume. The beam electrons may spread out within a large volume, but if the electrons lack sufficient energy to produce the X-ray of interest, the analytical volume could be significantly smaller. Therefore there are two competing strategies for creating the smallest analytical volumes. The first strategy is to reduce the accelerating voltage to produce the smallest electron interaction volume. This low kV analytical approach is ultimately limited by the size of the electron beam itself. With a field emission gun, normally the smallest analytical area is achieved at around 5-7 kV. At lower accelerating voltages, the increase in the beam diameter begins to overshadow the reduction in internal scattering. For tungsten filament guns, the smallest analytical volume is reached at higher accelerating voltages. The second strategy is to minimize the overvoltage during the analysis. If the accelerating voltage is only 1-3 kV greater than the critical ionization energy for the X-ray line of interest, then even if the overall electron interaction volume is large, those electrons quickly loose sufficient energy to produce the desired X-rays. The portion of the interaction volume in which the desired X-rays will be produce will be very small and very near the surface. Both strategies have advantages and disadvantages depending on the ultimate goal of the analysis and the elements involved. This work will examine a number of considerations when attempting to decide which approach is best for a given analytical situation. These include: (1) the size of the analytical volumes, (2) minimum detection limits, (3) quality of the matrix corrections, (4) secondary fluorescence, (5) effects of surface contamination, oxide layers, and carbon coatings. This work is based on results largely from the Fe-Ni binary. A simple conclusion cannot be draw as to which strategy is better overall. The determination is highly system dependent. For many mineral systems, both strategies used in combination will produce the best results. Using multiple accelerating voltages to preform a single analysis allows the analyst to optimize their analytical conditions for each element individually.

Double-layer Tedlar bags: a means to limit humidity evolution of air samples and to dry humid air samples.

PubMed

Cariou, Stephane; Guillot, Jean-Michel

2006-01-01

Tedlar bags, which are widely used to collect air samples, especially VOCs and odorous atmospheres, can allow humidity to diffuse when relative humidity levels differ between the inside and outside. Starting with dry air inside the bag and humid air outside, we monitored equilibrium times under several conditions showing the evolution and influence of collected volumes and exposed surfaces. A double-film Tedlar bag was made, to limit the impact of external humidity on a sample at low humidity level. With the addition of a drying agent between both films, the evolution of humidity of a sample can be stopped for several hours. When a VOC mixture was monitored in a humid atmosphere, humidity was decreased but no significant evolution of VOC concentrations was observed.

Development of an online SPE-UHPLC-MS/MS method for the multiresidue analysis of the 17 compounds from the EU "Watch list".

PubMed

Gusmaroli, Lucia; Insa, Sara; Petrovic, Mira

2018-04-24

During the last decades, the quality of aquatic ecosystems has been threatened by increasing levels of pollutions, caused by the discharge of man-made chemicals, both via accidental release of pollutants as well as a consequence of the constant outflow of inadequately treated wastewater effluents. For this reason, the European Union is updating its legislations with the aim of limiting the release of emerging contaminants. The Commission Implementing Decision (EU) 2015/495 published in March 2015 drafts a "Watch list" of compounds to be monitored Europe-wide. In this study, a methodology based on online solid-phase extraction (SPE) ultra-high-performance liquid chromatography coupled to a triple-quadrupole mass spectrometer (UHPLC-MS/MS) was developed for the simultaneous determination of the 17 compounds listed therein. The proposed method offers advantages over already available methods, such as versatility (all 17 compounds can be analyzed simultaneously), shorter time required for analysis, robustness, and sensitivity. The employment of online sample preparation minimized sample manipulation and reduced dramatically the sample volume needed and time required, dramatically the sample volume needed and time required, thus making the analysis fast and reliable. The method was successfully validated in surface water and influent and effluent wastewater. Limits of detection ranged from sub- to low-nanogram per liter levels, in compliance with the EU limits, with the only exception of EE2. Graphical abstract Schematic of the workflow for the analysis of the Watch list compounds.

Imaging whole mouse brains with a dual resolution serial swept-source optical coherence tomography scanner

NASA Astrophysics Data System (ADS)

Lefebvre, Joël.; Castonguay, Alexandre; Lesage, Frédéric

2018-02-01

High resolution imaging of whole rodent brains using serial OCT scanners is a promising method to investigate microstructural changes in tissue related to the evolution of neuropathologies. Although micron to sub-micron sampling resolution can be obtained by using high numerical aperture objectives and dynamic focusing, such an imaging system is not adapted to whole brain imaging. This is due to the large amount of data it generates and the significant computational resources required for reconstructing such volumes. To address this limitation, a dual resolution serial OCT scanner was developed. The optical setup consists in a swept-source OCT made of two sample and reference arms, each arm being coupled with different microscope objectives (3X / 40X). Motorized flip mirrors were used to switch between each OCT arm, thus allowing low and high resolution acquisitions within the same sample. The low resolution OCT volumes acquired with the 3X arm were stitched together, providing a 3D map of the whole mouse brain. This brain can be registered to an OCT brain template to enable neurological structures localization. The high resolution volumes acquired with the 40X arm were also stitched together to create local high resolution 3D maps of the tissue microstructure. The 40X data can be acquired at any arbitrary location in the sample, thus limiting storage-heavy high resolution data to application restricted to specific regions of interest. By providing dual-resolution OCT data, this setup can be used to validate diffusion MRI with tissue microstructure derived metrics measured at any location in ex vivo brains.

High-throughput differentiation of heparin from other glycosaminoglycans by pyrolysis mass spectrometry.

PubMed

Nemes, Peter; Hoover, William J; Keire, David A

2013-08-06

Sensors with high chemical specificity and enhanced sample throughput are vital to screening food products and medical devices for chemical or biochemical contaminants that may pose a threat to public health. For example, the rapid detection of oversulfated chondroitin sulfate (OSCS) in heparin could prevent reoccurrence of heparin adulteration that caused hundreds of severe adverse events including deaths worldwide in 2007-2008. Here, rapid pyrolysis is integrated with direct analysis in real time (DART) mass spectrometry to rapidly screen major glycosaminoglycans, including heparin, chondroitin sulfate A, dermatan sulfate, and OSCS. The results demonstrate that, compared to traditional liquid chromatography-based analyses, pyrolysis mass spectrometry achieved at least 250-fold higher sample throughput and was compatible with samples volume-limited to about 300 nL. Pyrolysis yielded an abundance of fragment ions (e.g., 150 different m/z species), many of which were specific to the parent compound. Using multivariate and statistical data analysis models, these data enabled facile differentiation of the glycosaminoglycans with high throughput. After method development was completed, authentically contaminated samples obtained during the heparin crisis by the FDA were analyzed in a blinded manner for OSCS contamination. The lower limit of differentiation and detection were 0.1% (w/w) OSCS in heparin and 100 ng/μL (20 ng) OSCS in water, respectively. For quantitative purposes the linear dynamic range spanned approximately 3 orders of magnitude. Moreover, this chemical readout was successfully employed to find clues in the manufacturing history of the heparin samples that can be used for surveillance purposes. The presented technology and data analysis protocols are anticipated to be readily adaptable to other chemical and biochemical agents and volume-limited samples.

Quality of wet deposition in the Grand Calumet River watershed, northwestern Indiana, June 30, 1992-August 31, 1993

USGS Publications Warehouse

Willoughby, T.C.

1995-01-01

Northwestern Indiana is one of the most heavily industrialized and largest steel-producing areas in the United States. High temperature processes, such as fossil-fuel combustion and steel production, release contaminants to the atmosphere that may result in wet deposition being a major contributor to major ion and trace-metal loadings in north- western Indiana and Lake Michigan. A wet-deposition collection site was established at the Gary (Indiana) Regional Airport in June 1992 to monitor the chemical quality of wet deposition. Weekly samples were collected at this site from June 30, 1992, through August 31, 1993, and were analyzed for pH, specific conductance, and selected major ions and trace metals. Forty-eight samples collected during the study were of sufficient volumes for some of the determinations to be performed. Median constituent concentrations were determined for samples collected during warm weather and cold weather (November 1 through March 31). Median concentrations were substituted for missing values from samples with insufficient volumes for analysis of all the constituents of interest. Constituent concentrations were converted to weekly loadings. Two values were calculated to provide a range for the weekly loading for samples with measured concentrations of constituents less than the method reporting limit. The minimum weekly loading was computed by substituting zero for the constituent concentration; the maximum weekly loading was computed by substituting the method reporting limit for the concentration. If all of the sample concentrations measured were greater than the method reporting limit, an annual loading value was computed. The annual loadings could be used to assist in estimating the contribution of wet deposition to the total annual constituent loadings in the Grand Calumet River in northwestern Indiana.

Drop-on-demand sample introduction system coupled with the flowing atmospheric-pressure afterglow for direct molecular analysis of complex liquid microvolume samples.

PubMed

Schaper, J Niklas; Pfeuffer, Kevin P; Shelley, Jacob T; Bings, Nicolas H; Hieftje, Gary M

2012-11-06

One of the fastest developing fields in analytical spectrochemistry in recent years is ambient desorption/ionization mass spectrometry (ADI-MS). This burgeoning interest has been due to the demonstrated advantages of the method: simple mass spectra, little or no sample preparation, and applicability to samples in the solid, liquid, or gaseous state. One such ADI-MS source, the flowing atmospheric-pressure afterglow (FAPA), is capable of direct analysis of solids just by aiming the source at the solid surface and sampling the produced ions into a mass spectrometer. However, direct introduction of significant volumes of liquid samples into this source has not been possible, as solvent loads can quench the afterglow and, thus, the formation of reagent ions. As a result, the analysis of liquid samples is preferably carried out by analyzing dried residues or by desorbing small amounts of liquid samples directly from the liquid surface. In the former case, reproducibility of sample introduction is crucial if quantitative results are desired. In the present study, introduction of liquid samples as very small droplets helps overcome the issues of sample positioning and reduced levels of solvent intake. A recently developed "drop-on-demand" (DOD) aerosol generator is capable of reproducibly producing very small volumes of liquid (∼17 pL). In this paper, the coupling of FAPA-MS and DOD is reported and applications are suggested. Analytes representing different classes of substances were tested and limits of detections were determined. Matrix tolerance was investigated for drugs of abuse and their metabolites by analyzing raw urine samples and quantification without the use of internal standards. Limits of detection below 2 μg/mL, without sample pretreatment, were obtained.

Selenium analysis by an integrated microwave digestion-needle trap device with hydride sorption on carbon nanotubes and electrothermal atomic absorption spectrometry determination

NASA Astrophysics Data System (ADS)

Maratta Martínez, Ariel; Vázquez, Sandra; Lara, Rodolfo; Martínez, Luis Dante; Pacheco, Pablo

2018-02-01

An integrated microwave assisted digestion (MW-AD) - needle trap device (NTD) for selenium determination in grape pomace samples is presented. The NTD was filled with oxidized multiwall carbon nanotubes (oxMWCNTS) where Se hydrides were preconcentrated. Determination was carried out by flow injection-electrothermal atomic absorption spectrometry (FI-ETAAS). The variables affecting the system were established by a multivariate design (Plackett Burman), indicating that the following variables significantly affect the system: sample amount, HNO3 digestion solution concentration, NaBH4 volume and elution volume. A Box-Behnken design was implemented to determine the optimized values of these variables. The system improved Se atomization in the graphite furnace, since only trapped hydrides reached the graphite furnace, and the pyrolysis stage was eliminated according to the aqueous matrix of the eluate. Under optimized conditions the system reached a limit of quantification of 0.11 μg kg- 1, a detection limit of 0.032 μg kg- 1, a relative standard deviation of 4% and a preconcentration factor (PF) of 100, reaching a throughput sample of 5 samples per hour. Sample analysis show Se concentrations between 0.34 ± 0.03 μg kg- 1 to 0.48 ± 0.03 μg kg- 1 in grape pomace. This system provides minimal reagents and sample consumption, eliminates discontinuous stages between samples processing reaching a simpler and faster Se analysis.

Contrast-enhanced 3D micro-CT of plant tissues using different impregnation techniques.

PubMed

Wang, Zi; Verboven, Pieter; Nicolai, Bart

2017-01-01

X-ray micro-CT has increasingly been used for 3D imaging of plant structures. At the micrometer resolution however, limitations in X-ray contrast often lead to datasets with poor qualitative and quantitative measures, especially within dense cell clusters of plant tissue specimens. The current study developed protocols for delivering a cesium based contrast enhancing solution to varying plant tissue specimens for the purpose of improving 3D tissue structure characterization within plant specimens, accompanied by new image processing workflows to extract the additional data generated by the contrast enhanced scans. Following passive delivery of a 10% cesium iodide contrast solution, significant increases of 85.4 and 38.0% in analyzable cell volumes were observed in pear fruit hypanthium and tomato fruit outer mesocarp samples. A significant increase of 139.6% in the number of analyzable cells was observed in the pear fruit samples along the added ability to locate and isolate better brachysclereids and vasculature in the sample volume. Furthermore, contrast enhancement resulted in significant improvement in the definition of collenchyma and parenchyma in the petiolule of tomato leaflets, from which both qualitative and quantitative data can be extracted with respect to cell measures. However, contrast enhancement was not achieved in leaf vasculature and mesophyll tissue due to fundamental limitations. Active contrast delivery to apple fruit hypanthium samples did yield a small but insignificant increase in analyzable volume and cells, but data on vasculature can now be extracted better in correspondence to the pear hypanthium samples. Contrast delivery thus improved visualization and analysis the most in dense tissue types. The cesium based contrast enhancing protocols and workflows can be utilized to obtain detailed 3D data on the internal microstructure of plant samples, and can be adapted to additional samples of interest with minimal effort. The resulting datasets can therefore be utilized for more accurate downstream studies that requires 3D data.

What controls the maximum magnitude of injection-induced earthquakes?

NASA Astrophysics Data System (ADS)

Eaton, D. W. S.

2017-12-01

Three different approaches for estimation of maximum magnitude are considered here, along with their implications for managing risk. The first approach is based on a deterministic limit for seismic moment proposed by McGarr (1976), which was originally designed for application to mining-induced seismicity. This approach has since been reformulated for earthquakes induced by fluid injection (McGarr, 2014). In essence, this method assumes that the upper limit for seismic moment release is constrained by the pressure-induced stress change. A deterministic limit is given by the product of shear modulus and the net injected fluid volume. This method is based on the assumptions that the medium is fully saturated and in a state of incipient failure. An alternative geometrical approach was proposed by Shapiro et al. (2011), who postulated that the rupture area for an induced earthquake falls entirely within the stimulated volume. This assumption reduces the maximum-magnitude problem to one of estimating the largest potential slip surface area within a given stimulated volume. Finally, van der Elst et al. (2016) proposed that the maximum observed magnitude, statistically speaking, is the expected maximum value for a finite sample drawn from an unbounded Gutenberg-Richter distribution. These three models imply different approaches for risk management. The deterministic method proposed by McGarr (2014) implies that a ceiling on the maximum magnitude can be imposed by limiting the net injected volume, whereas the approach developed by Shapiro et al. (2011) implies that the time-dependent maximum magnitude is governed by the spatial size of the microseismic event cloud. Finally, the sample-size hypothesis of Van der Elst et al. (2016) implies that the best available estimate of the maximum magnitude is based upon observed seismicity rate. The latter two approaches suggest that real-time monitoring is essential for effective management of risk. A reliable estimate of maximum plausible magnitude would clearly be beneficial for quantitative risk assessment of injection-induced seismicity.

Nanoliter hemolymph sampling and analysis of individual adult Drosophila melanogaster.

PubMed

Piyankarage, Sujeewa C; Featherstone, David E; Shippy, Scott A

2012-05-15

The fruit fly (Drosophila melanogaster) is an extensively used and powerful, genetic model organism. However, chemical studies using individual flies have been limited by the animal's small size. Introduced here is a method to sample nanoliter hemolymph volumes from individual adult fruit-flies for chemical analysis. The technique results in an ability to distinguish hemolymph chemical variations with developmental stage, fly sex, and sampling conditions. Also presented is the means for two-point monitoring of hemolymph composition for individual flies.

Specificity of abnormal brain volume in major depressive disorder: a comparison with borderline personality disorder.

PubMed

Depping, Malte S; Wolf, Nadine D; Vasic, Nenad; Sambataro, Fabio; Thomann, Philipp A; Christian Wolf, R

2015-03-15

Abnormal brain volume has been frequently demonstrated in major depressive disorder (MDD). It is unclear if these findings are specific for MDD since aberrant brain structure is also present in disorders with depressive comorbidity and affective dysregulation, such as borderline personality disorder (BPD). In this transdiagnostic study, we aimed to investigate if regional brain volume loss differentiates between MDD and BPD. Further, we tested for associations between brain volume and clinical variables within and between diagnostic groups. 22 Females with a DSM-IV diagnosis of MDD, 17 females with a DSM-IV diagnosis of BPD and without comorbid posttraumatic stress disorder, and 22 age-matched female healthy controls (HC) were investigated using magnetic resonance imaging. High-resolution structural data were analyzed using voxel-based morphometry. A significant (p<0.05, cluster-corrected) volume decrease of the anterior cingulate cortex (ACC) was found in MDD compared to HC, as opposed to volume decreases of the amygdala in BPD compared to both HC and MDD. Sensitivity and specificity of regional gray matter volume for a diagnosis of MDD were modest to fair. Amygdala volume was related to depressive symptoms across the entire patient sample. Potential limitations of this study include the modest sample size and the heterogeneous psychotropic drug treatment. ACC volume reduction is more pronounced in MDD with an intermediate degree of volume loss in BPD compared to HC. In contrast, amygdala volume loss is more pronounced in BPD compared to MDD, yet amygdala volume is associated with affective symptom expression in both disorders. Copyright © 2014 Elsevier B.V. All rights reserved.

Topology Analysis of the Sloan Digital Sky Survey. I. Scale and Luminosity Dependence

NASA Astrophysics Data System (ADS)

Park, Changbom; Choi, Yun-Young; Vogeley, Michael S.; Gott, J. Richard, III; Kim, Juhan; Hikage, Chiaki; Matsubara, Takahiko; Park, Myeong-Gu; Suto, Yasushi; Weinberg, David H.; SDSS Collaboration

2005-11-01

We measure the topology of volume-limited galaxy samples selected from a parent sample of 314,050 galaxies in the Sloan Digital Sky Survey (SDSS), which is now complete enough to describe the fully three-dimensional topology and its dependence on galaxy properties. We compare the observed genus statistic G(νf) to predictions for a Gaussian random field and to the genus measured for mock surveys constructed from new large-volume simulations of the ΛCDM cosmology. In this analysis we carefully examine the dependence of the observed genus statistic on the Gaussian smoothing scale RG from 3.5 to 11 h-1 Mpc and on the luminosity of galaxies over the range -22.50

Simultaneous extraction and quantification of lamotrigine, phenobarbital, and phenytoin in human plasma and urine samples using solidified floating organic drop microextraction and high-performance liquid chromatography.

PubMed

Asadi, Mohammad; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Abbasi, Bijan

2015-07-01

A novel and simple method based on solidified floating organic drop microextraction followed by high-performance liquid chromatography with ultraviolet detection has been developed for simultaneous preconcentration and determination of phenobarbital, lamotrigine, and phenytoin in human plasma and urine samples. Factors affecting microextraction efficiency such as the type and volume of the extraction solvent, sample pH, extraction time, stirring rate, extraction temperature, ionic strength, and sample volume were optimized. Under the optimum conditions (i.e. extraction solvent, 1-undecanol (40 μL); sample pH, 8.0; temperature, 25°C; stirring rate, 500 rpm; sample volume, 7 mL; potassium chloride concentration, 5% and extraction time, 50 min), the limits of detection for phenobarbital, lamotrigine, and phenytoin were 1.0, 0.1, and 0.3 μg/L, respectively. Also, the calibration curves for phenobarbital, lamotrigine, and phenytoin were linear in the concentration range of 2.0-300.0, 0.3-200.0, and 1.0-200.0 μg/L, respectively. The relative standard deviations for six replicate extractions and determinations of phenobarbital, lamotrigine, and phenytoin at 50 μg/L level were less than 4.6%. The method was successfully applied to determine phenobarbital, lamotrigine, and phenytoin in plasma and urine samples. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Portable Immunoassay Platform for Multiplexed Detection of Biotoxins in Clinical and Environmental Samples

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

Koh, Chung-Yan; Piccini, Matthew Ernest; Schaff, Ulrich Y.

Multiple cases of attempted bioterrorism events using biotoxins have highlighted the urgent need for tools capable of rapid screening of suspect samples in the field (e.g., mailroom and public events). We present a portable microfluidic device capable of analyzing environmental (e.g., white powder), food (e.g., milk) and clinical (e.g., blood) samples for multiplexed detection of biotoxins. The device is rapid (<15-30 min sample-to-answer), sensitive (< 0.08 pg/mL detection limit for botulinum toxin), multiplexed (up to 64 parallel assays) and capable of analyzing small volume samples (< 20 μL total sample input). The immunoassay approach (SpinDx) is based on binding ofmore » toxins in a sample to antibody-laden capture particles followed by sedimentation of particles through a density-media in a microfluidic disk and quantification using a laser-induced fluorescence detector. A direct, blinded comparison with a gold standard ELISA revealed a 5-fold more sensitive detection limit for botulinum toxin while requiring 250-fold less sample volume and a 30 minute assay time with a near unity correlation. A key advantage of the technique is its compatibility with a variety of sample matrices with no additional sample preparation required. Ultrasensitive quantification has been demonstrated from direct analysis of multiple clinical, environmental and food samples, including white powder, whole blood, saliva, salad dressing, whole milk, peanut butter, half and half, honey, and canned meat. We believe that this device can met an urgent need in screening both potentially exposed people as well as suspicious samples in mail-rooms, airports, public sporting venues and emergency rooms. The general-purpose immunodiagnostics device can also find applications in screening of infectious and systemic diseases or serve as a lab device for conducting rapid immunoassays.« less

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods.

PubMed

Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Frache, Roberto

2003-01-01

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min(-1), elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L(-1) using ETAAS and 12, 122, 3.4, 17, and 21 ng L(-1) using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-microg L(-1) concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).

Determination of dissolved aluminum in water samples

USGS Publications Warehouse

Afifi, A.A.

1983-01-01

A technique has been modified for determination of a wide range of concentrations of dissolved aluminum (Al) in water and has been tested. In this technique, aluminum is complexed with 8-hydroxyquinoline at pH 8.3 to minimize interferences, then extracted with methyl isobutyl ketone (MIBK). The extract is analyzed colorimetrically at 395 nm. This technique is used to analyze two forms of monomeric Al, nonlabile (organic complexes) and labile (free, Al, Al sulfate, fluoride and hydroxide complexes). A detection limit 2 ug/L is possible with 25-ml samples and 10-ml extracts. The detection limit can be decreased by increasing the volume of the sample and (or) decreasing the volume of the methyl isobutyl ketone extract. The analytical uncertainty of this method is approximately + or - 5 percent. The standard addition technique provides a recovery test for this technique and ensures precision in samples of low Al concentrations. The average percentage recovery of the added Al plus the amount originally present was 99 percent. Data obtained from analyses of filtered standard solutions indicated that Al is adsorbed on various types of filters. However, the relationship between Al concentrations and adsorption remains linear. A test on standard solutions also indicated that Al is not adsorbed on nitric acid-washed polyethylene and polypropylene bottle wells. (USGS)

Evaluation of Bio-VOC Sampler for Analysis of Volatile Organic Compounds in Exhaled Breath

PubMed Central

Kwak, Jae; Fan, Maomian; Harshman, Sean W.; Garrison, Catherine E.; Dershem, Victoria L.; Phillips, Jeffrey B.; Grigsby, Claude C.; Ott, Darrin K.

2014-01-01

Monitoring volatile organic compounds (VOCs) from exhaled breath has been used to determine exposures of humans to chemicals. Prior to analysis of VOCs, breath samples are often collected with canisters or bags and concentrated. The Bio-VOC breath sampler, a commercial sampling device, has been recently introduced to the market with growing use. The main advantage for this sampler is to collect the last portion of exhaled breath, which is more likely to represent the air deep in the lungs. However, information about the Bio-VOC sampler is somewhat limited. Therefore, we have thoroughly evaluated the sampler here. We determined the volume of the breath air collected in the sampler was approximately 88 mL. When sampling was repeated multiple times, with the succeeding exhalations applied to a single sorbent tube, we observed linear relationships between the normalized peak intensity and the number of repeated collections with the sampler in many of the breath VOCs detected. No moisture effect was observed on the Tenax sorbent tubes used. However, due to the limitation in the collection volume, the use of the Bio-VOC sampler is recommended only for detection of VOCs present at high concentrations unless repeated collections of breath samples on the sampler are conducted. PMID:25532709

Dispersive liquid-liquid microextraction based on solidification of floating organic drop for preconcentration and determination of trace amounts of copper by flame atomic absorption spectrometry.

PubMed

Karadaş, Cennet; Kara, Derya

2017-04-01

A novel, simple, rapid, sensitive, inexpensive and environmentally friendly dispersive liquid-liquid microextraction method based on the solidification of a floating organic drop (DLLME-SFO) was developed for the determination of copper by flame atomic absorption spectrometry (FAAS). N-o-Vanillidine-2-amino-p-cresol was used as a chelating ligand and 1-undecanol was selected as an extraction solvent. The main parameters affecting the performance of DLLME-SFO, such as sample pH, volume of extraction solvent, extraction time, concentration of the chelating ligand, salt effect, centrifugation time and sample volume were investigated and optimized. The effect of interfering ions on the recovery of copper was also examined. Under the optimum conditions, the detection limit (3σ) was 0.93μgL -1 for Cu using a sample volume of 20mL, yielding a preconcentration factor of 20. The proposed method was successfully applied to the determination of Cu in tap, river and seawater, rice flour and black tea samples as well as certified reference materials. Copyright © 2016. Published by Elsevier Ltd.

Malaria PCR Detection in Cambodian Low-Transmission Settings: Dried Blood Spots versus Venous Blood Samples

PubMed Central

Canier, Lydie; Khim, Nimol; Kim, Saorin; Eam, Rotha; Khean, Chanra; Loch, Kaknika; Ken, Malen; Pannus, Pieter; Bosman, Philippe; Stassijns, Jorgen; Nackers, Fabienne; Alipon, SweetC; Char, Meng Chuor; Chea, Nguon; Etienne, William; De Smet, Martin; Kindermans, Jean-Marie; Ménard, Didier

2015-01-01

In the context of malaria elimination, novel strategies for detecting very low malaria parasite densities in asymptomatic individuals are needed. One of the major limitations of the malaria parasite detection methods is the volume of blood samples being analyzed. The objective of the study was to compare the diagnostic accuracy of a malaria polymerase chain reaction assay, from dried blood spots (DBS, 5 μL) and different volumes of venous blood (50 μL, 200 μL, and 1 mL). The limit of detection of the polymerase chain reaction assay, using calibrated Plasmodium falciparum blood dilutions, showed that venous blood samples (50 μL, 200 μL, 1 mL) combined with Qiagen extraction methods gave a similar threshold of 100 parasites/mL, ∼100-fold lower than 5 μL DBS/Instagene method. On a set of 521 field samples, collected in two different transmission areas in northern Cambodia, no significant difference in the proportion of parasite carriers, regardless of the methods used was found. The 5 μL DBS method missed 27% of the samples detected by the 1 mL venous blood method, but most of the missed parasites carriers were infected by Plasmodium vivax (84%). The remaining missed P. falciparum parasite carriers (N = 3) were only detected in high-transmission areas. PMID:25561570

An improved analytical strategy combining microextraction by packed sorbent combined with ultra high pressure liquid chromatography for the determination of fluoxetine, clomipramine and their active metabolites in human urine.

PubMed

Alves, Vera; Gonçalves, João; Conceição, Carlota; Teixeira, Helena M; Câmara, José S

2015-08-21

A powerful and sensitive method, by microextraction packed sorbent (MEPS), and ultra-high performance liquid chromatography (UHPLC) with a photodiode array (PDA) detection, is described for the determination of fluoxetine, clomipramine and their active metabolites in human urine samples. The MEPS variables, such as sample volume, pH, number of extraction cycles (draw-eject), and desorption conditions (solvent and solvent volume of elution) were optimized. The analysis were carried out using small sample volumes (500μL) and in a short time period (5min for the entire sample preparation step). Good linearity was obtained for all antidepressants with the correlation coefficients (R(2)) above 0.9965. The limits of detection (LOD) ranged from 0.068 to 0.087μgmL(-1). The recoveries were from 93% to 98%, with relative standard deviations less than 6%. The inter-day precision, expressed as the relative standard deviation, varied between 3.8% and 8.5% while the intra-day precision between 3.0% and 7.1%. In order to evaluate the proposed method for clinical use, the MEPS/UHPLC-PDA method was applied to analysis of urine samples from depressed patients. Copyright © 2015 Elsevier B.V. All rights reserved.

A highly selective and sensitive ultrasonic assisted dispersive liquid phase microextraction based on deep eutectic solvent for determination of cadmium in food and water samples prior to electrothermal atomic absorption spectrometry.

PubMed

Zounr, Rizwan Ali; Tuzen, Mustafa; Deligonul, Nihal; Khuhawar, Muhammad Yar

2018-07-01

A simple, fast, green, sensitive and selective ultrasonic assisted deep eutectic solvent liquid-phase microextraction technique was used for preconcentration and extraction of cadmium (Cd) in water and food samples by electrothermal atomic absorption spectrometry (ETAAS). In this technique, a synthesized reagent (Z)-N-(3,5-diphenyl-1H-pyrrol-2-yl)-3,5-diphenyl-2H-pyrrol-2-imine (Azo) was used as a complexing agent for Cd. The main factors effecting the pre-concentration and extraction of Cd such as effect of pH, type and composition of deep eutectic solvent (DES), volume of DES, volume of complexing agent, volume of tetrahydrofuran (THF) and ultrasonication time have been examined in detail. At optimum conditions the value of pH and molar ratio of DES were found to be 6.0 and 1:4 (ChCl:Ph), respectively. The detection limit (LOD), limit of quantification (LOQ), relative standard deviation (RSD) and preconcentration factor (PF) were observed as 0.023 ng L -1 , 0.161 ng L -1 , 3.1% and 100, correspondingly. Validation of the developed technique was observed by extraction of Cd in certified reference materials (CRMs) and observed results were successfully compared with certified values. The developed procedure was practiced to various food, beverage and water samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Micro-injector for capillary electrophoresis.

PubMed

Sáiz, Jorge; Koenka, Israel Joel; García-Ruiz, Carmen; Müller, Beat; Chwalek, Thomas; Hauser, Peter C

2015-08-01

A novel micro-injector for capillary electrophoresis for the handling of samples with volumes down to as little as 300 nL was designed and built in our laboratory for analyses in which the available volume is a limitation. The sample is placed into a small cavity located directly in front of the separation capillary, and the injection is then carried out automatically by controlled pressurization of the chamber with compressed air. The system also allows automated flushing of the injection chamber as well as of the capillary. In a trial with a capillary electrophoresis system with contactless conductivity detector, employing a capillary of 25 μm diameter, the results showed good stability of migration times and peak areas. To illustrate the technique, the fast separation of five inorganic cations (Na(+) , K(+) , NH4 (+) , Ca(2+) , and Mg(2+) ) was set up. This could be achieved in less than 3 min, with good limits of detection (10 μM) and linear ranges (between about 10 and 1000 μM). The system was demonstrated for the determination of the inorganic cations in porewater samples of a lake sediment core. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of a period of intense exercise on the marker approach to detect growth hormone doping in sports.

PubMed

Voss, Sven Christian; Robinson, Neil; Alsayrafi, Mohammed; Bourdon, Pitre C; Schumacher, Yorck Olaf; Saugy, Martial; Giraud, Sylvain

2014-06-01

The major objective of this study was to investigate the effects of several days of intense exercise on the growth hormone marker approach to detect doping with human growth hormone (hGH). In addition we investigated the effect of changes in plasma volume on the test. Fifteen male athletes performed a simulated nine-day cycling stage race. Blood samples were collected twice daily over a period of 15 days (stage race + three days before and after). Plasma volumes were estimated by the optimized CO Rebreathing method. IGF-1 and P-III-NP were analyzed by Siemens Immulite and Cisbio Assays, respectively. All measured GH 2000 scores were far below the published decision limits for an adverse analytical finding. The period of exercise did not increase the GH-scores; however the accompanying effect of the increase in Plasma Volume yielded in essentially lower GH-scores. We could demonstrate that a period of heavy, long-term exercise with changes in plasma volume does not interfere with the decision limits for an adverse analytical finding. Copyright © 2014 John Wiley & Sons, Ltd.

Analysis of microdialysate monoamines, including noradrenaline, dopamine and serotonin, using capillary ultra-high performance liquid chromatography and electrochemical detection.

PubMed

Ferry, Barbara; Gifu, Elena-Patricia; Sandu, Ioana; Denoroy, Luc; Parrot, Sandrine

2014-03-01

Electrochemical methods are very often used to detect catecholamine and indolamine neurotransmitters separated by conventional reverse-phase high performance liquid chromatography (HPLC). The present paper presents the development of a chromatographic method to detect monoamines present in low-volume brain dialysis samples using a capillary column filled with sub-2μm particles. Several parameters (repeatability, linearity, accuracy, limit of detection) for this new ultrahigh performance liquid chromatography (UHPLC) method with electrochemical detection were examined after optimization of the analytical conditions. Noradrenaline, adrenaline, serotonin, dopamine and its metabolite 3-methoxytyramine were separated in 1μL of injected sample volume; they were detected above concentrations of 0.5-1nmol/L, with 2.1-9.5% accuracy and intra-assay repeatability equal to or less than 6%. The final method was applied to very low volume dialysates from rat brain containing monoamine traces. The study demonstrates that capillary UHPLC with electrochemical detection is suitable for monitoring dialysate monoamines collected at high sampling rate. Copyright © 2014 Elsevier B.V. All rights reserved.

Digital Holographic Microscopy, a Method for Detection of Microorganisms in Plume Samples from Enceladus and Other Icy Worlds

PubMed Central

Bedrossian, Manuel; Lindensmith, Chris

2017-01-01

Abstract Detection of extant microbial life on Earth and elsewhere in the Solar System requires the ability to identify and enumerate micrometer-scale, essentially featureless cells. On Earth, bacteria are usually enumerated by culture plating or epifluorescence microscopy. Culture plates require long incubation times and can only count culturable strains, and epifluorescence microscopy requires extensive staining and concentration of the sample and instrumentation that is not readily miniaturized for space. Digital holographic microscopy (DHM) represents an alternative technique with no moving parts and higher throughput than traditional microscopy, making it potentially useful in space for detection of extant microorganisms provided that sufficient numbers of cells can be collected. Because sample collection is expected to be the limiting factor for space missions, especially to outer planets, it is important to quantify the limits of detection of any proposed technique for extant life detection. Here we use both laboratory and field samples to measure the limits of detection of an off-axis digital holographic microscope (DHM). A statistical model is used to estimate any instrument's probability of detection at various bacterial concentrations based on the optical performance characteristics of the instrument, as well as estimate the confidence interval of detection. This statistical model agrees well with the limit of detection of 103 cells/mL that was found experimentally with laboratory samples. In environmental samples, active cells were immediately evident at concentrations of 104 cells/mL. Published estimates of cell densities for Enceladus plumes yield up to 104 cells/mL, which are well within the off-axis DHM's limits of detection to confidence intervals greater than or equal to 95%, assuming sufficient sample volumes can be collected. The quantitative phase imaging provided by DHM allowed minerals to be distinguished from cells. Off-axis DHM's ability for rapid low-level bacterial detection and counting shows its viability as a technique for detection of extant microbial life provided that the cells can be captured intact and delivered to the sample chamber in a sufficient volume of liquid for imaging. Key Words: In situ life detection—Extant microorganisms—Holographic microscopy—Ocean Worlds—Enceladus—Imaging. Astrobiology 17, 913–925. PMID:28708412

Cortical Changes Across the Autism Lifespan.

PubMed

Osipowicz, Karol; Bosenbark, Danielle D; Patrick, Kristina E

2015-08-01

Although it is widely accepted that autism spectrum disorder (ASD) involves neuroanatomical abnormalities and atypical neurodevelopmental patterns, there is little consensus regarding the precise pattern of neuroanatomical differences or how these differences relate to autism symptomology. Furthermore, there is limited research related to neuroanatomical correlates of autism symptomology in individuals with ASD and the studies that do exist primarily include small samples. This study was the first to investigate gray matter (GM) changes throughout the ASD lifespan, using voxel-based morphometry to determine whether significant differences exist in the GM volumes of a large sample of individuals with ASD compared to age- and IQ-matched typical controls. We examined GM volume across the lifespan in 531 individuals diagnosed with ASD and 571 neurotypical controls, aged 7-64. We compared groups and correlated GM with age and autism severity in the ASD group. Findings suggest bilateral decreased GM volume for individuals with ASD in regions extending from the thalamus to the cerebellum, anterior medial temporal lobes, and orbitofrontal regions. Higher autism severity was associated with decreased GM volumes in prefrontal cortex, inferior parietal and temporal regions, and temporal poles. Similar relationships were found between GM volume and age. ASD diagnosis and severity were not associated with increased GM volumes in any region. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

Sensitive analysis of steroid estrogens and bisphenol a in small volumes of water using isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry.

PubMed

Chang, Hong; Shen, Xiaoyan; Shao, Bing; Wu, Fengchang

2018-04-01

An isotope-dilution ultra-performance liquid chromatography-electrospray tandem mass spectrometry method combined with dansylation was established to sensitively quantify four steroid estrogens (estrone, 17α-estradiol, 17β-estradiol and 17α-ethynylestradiol) and bisphenol A in sewage influent and effluent. A simple hexane extraction was performed from a small volume (10 mL), followed by dansyl chloride derivatization and purification with a silica cartridge. The method effectively reduced the matrix effects in sample extract and permitted the selective and sensitive determination of target compounds from complicated matrices. The detection limits of the method for steroid estrogens were 0.20-0.90 ng L -1 in influent and 0.10-0.20 ng L -1 in effluent samples. For bisphenol A, the limits detection of the method were 20 and 0.80 for influent and effluent samples, respectively. Recoveries of 85%-96% were observed in all matrices. The method was applied to analyze residual estrogens and bisphenol A in sewage influent and effluent samples from Beijing, China. The concentrations of bisphenol A (636-1200 ng L -1 ) were up to 250 times higher than those of steroid estrogens. Estrone was the dominant estrogen in influent and effluent samples, while similar concentrations of 17α-estradiol and 17β-estradiol were detected in all samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Wave optics theory and 3-D deconvolution for the light field microscope

PubMed Central

Broxton, Michael; Grosenick, Logan; Yang, Samuel; Cohen, Noy; Andalman, Aaron; Deisseroth, Karl; Levoy, Marc

2013-01-01

Light field microscopy is a new technique for high-speed volumetric imaging of weakly scattering or fluorescent specimens. It employs an array of microlenses to trade off spatial resolution against angular resolution, thereby allowing a 4-D light field to be captured using a single photographic exposure without the need for scanning. The recorded light field can then be used to computationally reconstruct a full volume. In this paper, we present an optical model for light field microscopy based on wave optics, instead of previously reported ray optics models. We also present a 3-D deconvolution method for light field microscopy that is able to reconstruct volumes at higher spatial resolution, and with better optical sectioning, than previously reported. To accomplish this, we take advantage of the dense spatio-angular sampling provided by a microlens array at axial positions away from the native object plane. This dense sampling permits us to decode aliasing present in the light field to reconstruct high-frequency information. We formulate our method as an inverse problem for reconstructing the 3-D volume, which we solve using a GPU-accelerated iterative algorithm. Theoretical limits on the depth-dependent lateral resolution of the reconstructed volumes are derived. We show that these limits are in good agreement with experimental results on a standard USAF 1951 resolution target. Finally, we present 3-D reconstructions of pollen grains that demonstrate the improvements in fidelity made possible by our method. PMID:24150383

Age-related differences in regional brain volumes: A comparison of optimized voxel-based morphometry to manual volumetry

PubMed Central

Kennedy, Kristen M.; Erickson, Kirk I.; Rodrigue, Karen M.; Voss, Michelle W.; Colcombe, Stan J.; Kramer, Arthur F.; Acker, James D.; Raz, Naftali

2009-01-01

Regional manual volumetry is the gold standard of in vivo neuroanatomy, but is labor-intensive, can be imperfectly reliable, and allows for measuring limited number of regions. Voxel-based morphometry (VBM) has perfect repeatability and assesses local structure across the whole brain. However, its anatomic validity is unclear, and with its increasing popularity, a systematic comparison of VBM to manual volumetry is necessary. The few existing comparison studies are limited by small samples, qualitative comparisons, and limited selection and modest reliability of manual measures. Our goal was to overcome those limitations by quantitatively comparing optimized VBM findings with highly reliable multiple regional measures in a large sample (N = 200) across a wide agespan (18–81). We report a complex pattern of similarities and differences. Peak values of VBM volume estimates (modulated density) produced stronger age differences and a different spatial distribution from manual measures. However, when we aggregated VBM-derived information across voxels contained in specific anatomically defined regions (masks), the patterns of age differences became more similar, although important discrepancies emerged. Notably, VBM revealed stronger age differences in the regions bordering CSF and white matter areas prone to leukoaraiosis, and VBM was more likely to report nonlinearities in age-volume relationships. In the white matter regions, manual measures showed stronger negative associations with age than the corresponding VBM-based masks. We conclude that VBM provides realistic estimates of age differences in the regional gray matter only when applied to anatomically defined regions, but overestimates effects when individual peaks are interpreted. It may be beneficial to use VBM as a first-pass strategy, followed by manual measurement of anatomically-defined regions. PMID:18276037

Installation Restoration Program. Phase 2. Confirmation/Quantification. Stage 1. Air Force Plant 4, Fort Worth, Texas. Volume 5. Appendix A-2.

DTIC Science & Technology

1987-12-01

Limit Spiked Samale Samole ISailced C" auod R sIus’lt (SSR) esult. (SR) A-dded ( .SA) Iels: I. I 1. A.luminum 75-125 - I Z. Antimony - 3. Arsenic " I...UntKtarix *s %Control Limit Spiked Samale Sample SieiCm.,ound _ _R R esult (SSR) Re t,.- (SR) Added (SA) Z,10 1. AUlunu m 7 I I I 2. Antimonyj ____ 3...No. DATE Lab Sample) ;S4 No Katrix waot, " . n ...Central L imi Spiked Samale Samale Spiked Comnpound M Rsult: (SSR) Result (SR) jAdded (SA) XR

Static SPME sampling of VOCs emitted from indoor building materials: prediction of calibration curves of single compounds for two different emission cells.

PubMed

Mocho, Pierre; Desauziers, Valérie

2011-05-01

Solid-phase microextraction (SPME) is a powerful technique, easy to implement for on-site static sampling of indoor VOCs emitted by building materials. However, a major constraint lies in the establishment of calibration curves which requires complex generation of standard atmospheres. Thus, the purpose of this paper is to propose a model to predict adsorption kinetics (i.e., calibration curves) of four model VOCs. The model is based on Fick's laws for the gas phase and on the equilibrium or the solid diffusion model for the adsorptive phase. Two samplers (the FLEC® and a home-made cylindrical emission cell), coupled to SPME for static sampling of material emissions, were studied. A good agreement between modeling and experimental data is observed and results show the influence of sampling rate on mass transfer mode in function of sample volume. The equilibrium model is adapted to quite large volume sampler (cylindrical cell) while the solid diffusion model is dedicated to small volume sampler (FLEC®). The limiting steps of mass transfer are the diffusion in gas phase for the cylindrical cell and the pore surface diffusion for the FLEC®. In the future, this modeling approach could be a useful tool for time-saving development of SPME to study building material emission in static mode sampling.

A simplified method to recover urinary vesicles for clinical applications, and sample banking.

PubMed

Musante, Luca; Tataruch, Dorota; Gu, Dongfeng; Benito-Martin, Alberto; Calzaferri, Giulio; Aherne, Sinead; Holthofer, Harry

2014-12-23

Urinary extracellular vesicles provide a novel source for valuable biomarkers for kidney and urogenital diseases: Current isolation protocols include laborious, sequential centrifugation steps which hampers their widespread research and clinical use. Furthermore, large individual urine sample volumes or sizable target cohorts are to be processed (e.g. for biobanking), the storage capacity is an additional problem. Thus, alternative methods are necessary to overcome such limitations. We have developed a practical vesicle isolation technique to yield easily manageable sample volumes in an exceptionally cost efficient way to facilitate their full utilization in less privileged environments and maximize the benefit of biobanking. Urinary vesicles were isolated by hydrostatic dialysis with minimal interference of soluble proteins or vesicle loss. Large volumes of urine were concentrated up to 1/100 of original volume and the dialysis step allowed equalization of urine physico-chemical characteristics. Vesicle fractions were found suitable to any applications, including RNA analysis. In the yield, our hydrostatic filtration dialysis system outperforms the conventional ultracentrifugation-based methods and the labour intensive and potentially hazardous step of ultracentrifugations are eliminated. Likewise, the need for trained laboratory personnel and heavy initial investment is avoided. Thus, our method qualifies as a method for laboratories working with urinary vesicles and biobanking.

A Simplified Method to Recover Urinary Vesicles for Clinical Applications, and Sample Banking

PubMed Central

Musante, Luca; Tataruch, Dorota; Gu, Dongfeng; Benito-Martin, Alberto; Calzaferri, Giulio; Aherne, Sinead; Holthofer, Harry

2014-01-01

Urinary extracellular vesicles provide a novel source for valuable biomarkers for kidney and urogenital diseases: Current isolation protocols include laborious, sequential centrifugation steps which hampers their widespread research and clinical use. Furthermore, large individual urine sample volumes or sizable target cohorts are to be processed (e.g. for biobanking), the storage capacity is an additional problem. Thus, alternative methods are necessary to overcome such limitations. We have developed a practical vesicle isolation technique to yield easily manageable sample volumes in an exceptionally cost efficient way to facilitate their full utilization in less privileged environments and maximize the benefit of biobanking. Urinary vesicles were isolated by hydrostatic dialysis with minimal interference of soluble proteins or vesicle loss. Large volumes of urine were concentrated up to 1/100 of original volume and the dialysis step allowed equalization of urine physico-chemical characteristics. Vesicle fractions were found suitable to any applications, including RNA analysis. In the yield, our hydrostatic filtration dialysis system outperforms the conventional ultracentrifugation-based methods and the labour intensive and potentially hazardous step of ultracentrifugations are eliminated. Likewise, the need for trained laboratory personnel and heavy initial investment is avoided. Thus, our method qualifies as a method for laboratories working with urinary vesicles and biobanking. PMID:25532487

Microscale depletion of high abundance proteins in human biofluids using IgY14 immunoaffinity resin: Analysis of human plasma and cerebrospinal fluid

DOE PAGES

Hyung, Seok Won; Piehowski, Paul D.; Moore, Ronald J.; ...

2014-09-06

Removal of highly abundant proteins in plasma is often carried out using immunoaffinity depletion to extend the dynamic range of measurements to lower abundance species. While commercial depletion columns are available for this purpose, they generally are not applicable to limited sample quantities (<20 µL) due to low yields stemming from losses caused by nonspecific binding to the column matrix. Additionally, the cost of the depletion media can be prohibitive for larger scale studies. Modern LC-MS instrumentation provides the sensitivity necessary to scale-down depletion methods with minimal sacrifice to proteome coverage, which makes smaller volume depletion columns desirable for maximizingmore » sample recovery when samples are limited, as well as for reducing the expense of large scale studies. We characterized the performance of a 346 µL column volume micro-scale depletion system, using four different flow rates to determine the most effective depletion conditions for ~6 μL injections of human plasma proteins and then evaluated depletion reproducibility at the optimum flow rate condition. Depletion of plasma using a commercial 10 mL depletion column served as the control. Results showed depletion efficiency of the micro-scale column increased as flow rate decreased, and that our micro-depletion was reproducible. We found, in an initial application, a 600 µL sample of human cerebral spinal fluid (CSF) pooled from multiple sclerosis patients was depleted and then analyzed using reversed phase liquid chromatography-mass spectrometry to demonstrate the utility of the system for this important biofluid where sample quantities are more commonly limited.« less

Personal exposure to aerosolized red tide toxins (brevetoxins).

PubMed

Cheng, Yung Sung; Zhou, Yue; Naar, Jerome; Irvin, C Mitch; Su, Wei-Chung; Fleming, Lora E; Kirkpatrick, Barbara; Pierce, Richard H; Backer, Lorraine C; Baden, Daniel G

2010-06-01

Florida red tides occur annually in the Gulf of Mexico from blooms of the marine dinoflagellate, Karenia brevis, which produces highly potent natural polyether toxins, brevetoxins. Several epidemiologic studies have demonstrated that human exposure to red tide aerosol could result in increased respiratory symptoms. Environmental monitoring of aerosolized brevetoxins was performed using a high-volume sampler taken hourly at fixed locations on Siesta Beach, Florida. Personal exposure was monitored using personal air samplers and taking nasal swab samples from the subjects who were instructed to spend 1 hr on Sarasota Beach during two sampling periods of an active Florida red tide event in March 2005, and in May 2008 when there was no red tide. Results showed that the aerosolized brevetoxins from the personal sampler were in modest agreement with the environmental concentration taken from a high-volume sampler. Analysis of nasal swab samples for brevetoxins demonstrated 68% positive samples in the March 2005 sampling period when air concentrations of brevetoxins were between 50 to 120 ng/m(3) measured with the high-volume sampler. No swab samples showed detectable levels of brevetoxins in the May 2008 study, when all personal samples were below the limit of detection. However, there were no statistical correlations between the amounts of brevetoxins detected in the swab samples with either the environmental or personal concentration. Results showed that the personal sample might provide an estimate of individual exposure level. Nasal swab samples showed that brevetoxins indeed were inhaled and deposited in the nasal passage during the March 2005 red tide event.

Distinct subcortical volume alterations in pediatric and adult OCD

PubMed Central

Boedhoe, Premika S.W.; Schmaal, Lianne; Abe, Yoshinari; Ameis, Stephanie H.; Arnold, Paul D.; Batistuzzo, Marcelo C.; Benedetti, Francesco; Beucke, Jan C.; Bollettini, Irene; Bose, Anushree; Brem, Silvia; Calvo, Anna; Cheng, Yuqi; Cho, Kang Ik K.; Dallaspezia, Sara; Denys, Damiaan; Fitzgerald, Kate D.; Fouche, Jean-Paul; Giménez, Mònica; Gruner, Patricia; Hanna, Gregory L.; Hibar, Derrek P.; Hoexter, Marcelo Q.; Huyser, Chaim; Ikari, Keisuke; Jahanshad, Neda; Kathmann, Norbert; Kaufmann, Christian; Koch, Kathrin; Kwon, Jun Soo; Lazaro, Luisa; Liu, Yanni; Lochner, Christine; Marsh, Rachel; Martínez-Zalacaín, Ignacio; Mataix-Cols, David; Menchón, José M.; Minuzzii, Luciano; Nakamae, Takashi; Nakao, Tomohiro; Narayanaswamy, Janardhanan C.; Piras, Fabrizio; Piras, Federica; Pittenger, Christopher; Reddy, Y.C. Janardhan; Sato, Joao R.; Simpson, H. Blair; Soreni, Noam; Soriano-Mas, Carles; Spalletta, Gianfranco; Stevens, Michael C.; Szeszko, Philip R.; Tolin, David F.; Venkatasubramanian, Ganesan; Walitza, Susanne; Wang, Zhen; van Wingen, Guido A.; Xu, Jian; Xu, Xiufeng; Yun, Je-Yeon; Zhao, Qing; Thompson, Paul M.; Stein, Dan J.; van den Heuvel, Odile A.

2016-01-01

Objective Structural brain imaging studies in Obsessive-Compulsive Disorder (OCD) have produced inconsistent findings. This may be partially due to limited statistical power from relatively small samples and clinical heterogeneity related to variation in disease profile and developmental stage. Methods To address these limitations, we conducted a meta- and mega-analysis of data from OCD sites worldwide. T1 images from 1,830 OCD patients and 1,759 controls were analyzed, using coordinated and standardized processing, to identify subcortical brain volumes that differ in OCD patients and healthy controls. We additionally examined potential modulating effects of clinical characteristics on morphological differences in OCD patients. Results The meta-analysis indicated that adult patients had significantly smaller hippocampal volumes (Cohen’s d=−0.13; p=5.1x10−3, % difference −2.80) and larger pallidum volumes (d=0.16; p=1.6x10−3, % difference 3.16) compared to adult controls. Both effects were stronger in medicated patients compared to controls (d=−0.29; p=2.4x10−5, % difference −4.18 and d=0.29; p=1.2x10−5, % difference 4.38, respectively). Unmedicated pediatric patients had larger thalamic volumes (d=0.38, p=2.1x10−3) compared to pediatric controls. None of these findings were mediated by sample characteristics such as mean age or field strength. Overall the mega-analysis yielded similar results. Conclusion Our study indicates a different pattern of subcortical abnormalities in pediatric versus adult OCD patients. The pallidum and hippocampus seem to be of importance in adult OCD, whereas the thalamus seems to be key in pediatric OCD. This highlights the potential importance of neurodevelopmental alterations in OCD, and suggests that further research on neuroplasticity in OCD may be useful. PMID:27609241

Distinct Subcortical Volume Alterations in Pediatric and Adult OCD: A Worldwide Meta- and Mega-Analysis.

PubMed

Boedhoe, Premika S W; Schmaal, Lianne; Abe, Yoshinari; Ameis, Stephanie H; Arnold, Paul D; Batistuzzo, Marcelo C; Benedetti, Francesco; Beucke, Jan C; Bollettini, Irene; Bose, Anushree; Brem, Silvia; Calvo, Anna; Cheng, Yuqi; Cho, Kang Ik K; Dallaspezia, Sara; Denys, Damiaan; Fitzgerald, Kate D; Fouche, Jean-Paul; Giménez, Mònica; Gruner, Patricia; Hanna, Gregory L; Hibar, Derrek P; Hoexter, Marcelo Q; Hu, Hao; Huyser, Chaim; Ikari, Keisuke; Jahanshad, Neda; Kathmann, Norbert; Kaufmann, Christian; Koch, Kathrin; Kwon, Jun Soo; Lazaro, Luisa; Liu, Yanni; Lochner, Christine; Marsh, Rachel; Martínez-Zalacaín, Ignacio; Mataix-Cols, David; Menchón, José M; Minuzzi, Luciano; Nakamae, Takashi; Nakao, Tomohiro; Narayanaswamy, Janardhanan C; Piras, Fabrizio; Piras, Federica; Pittenger, Christopher; Reddy, Y C Janardhan; Sato, Joao R; Simpson, H Blair; Soreni, Noam; Soriano-Mas, Carles; Spalletta, Gianfranco; Stevens, Michael C; Szeszko, Philip R; Tolin, David F; Venkatasubramanian, Ganesan; Walitza, Susanne; Wang, Zhen; van Wingen, Guido A; Xu, Jian; Xu, Xiufeng; Yun, Je-Yeon; Zhao, Qing; Thompson, Paul M; Stein, Dan J; van den Heuvel, Odile A

2017-01-01

Structural brain imaging studies in obsessive-compulsive disorder (OCD) have produced inconsistent findings. This may be partially due to limited statistical power from relatively small samples and clinical heterogeneity related to variation in illness profile and developmental stage. To address these limitations, the authors conducted meta- and mega-analyses of data from OCD sites worldwide. T 1 images from 1,830 OCD patients and 1,759 control subjects were analyzed, using coordinated and standardized processing, to identify subcortical brain volumes that differ between OCD patients and healthy subjects. The authors performed a meta-analysis on the mean of the left and right hemisphere measures of each subcortical structure, and they performed a mega-analysis by pooling these volumetric measurements from each site. The authors additionally examined potential modulating effects of clinical characteristics on morphological differences in OCD patients. The meta-analysis indicated that adult patients had significantly smaller hippocampal volumes (Cohen's d=-0.13; % difference=-2.80) and larger pallidum volumes (d=0.16; % difference=3.16) compared with adult controls. Both effects were stronger in medicated patients compared with controls (d=-0.29, % difference=-4.18, and d=0.29, % difference=4.38, respectively). Unmedicated pediatric patients had significantly larger thalamic volumes (d=0.38, % difference=3.08) compared with pediatric controls. None of these findings were mediated by sample characteristics, such as mean age or scanning field strength. The mega-analysis yielded similar results. The results indicate different patterns of subcortical abnormalities in pediatric and adult OCD patients. The pallidum and hippocampus seem to be of importance in adult OCD, whereas the thalamus seems to be key in pediatric OCD. These findings highlight the potential importance of neurodevelopmental alterations in OCD and suggest that further research on neuroplasticity in OCD may be useful.

A simple microviscometric approach based on Brownian motion tracking.

PubMed

Hnyluchová, Zuzana; Bjalončíková, Petra; Karas, Pavel; Mravec, Filip; Halasová, Tereza; Pekař, Miloslav; Kubala, Lukáš; Víteček, Jan

2015-02-01

Viscosity-an integral property of a liquid-is traditionally determined by mechanical instruments. The most pronounced disadvantage of such an approach is the requirement of a large sample volume, which poses a serious obstacle, particularly in biology and biophysics when working with limited samples. Scaling down the required volume by means of microviscometry based on tracking the Brownian motion of particles can provide a reasonable alternative. In this paper, we report a simple microviscometric approach which can be conducted with common laboratory equipment. The core of this approach consists in a freely available standalone script to process particle trajectory data based on a Newtonian model. In our study, this setup allowed the sample to be scaled down to 10 μl. The utility of the approach was demonstrated using model solutions of glycerine, hyaluronate, and mouse blood plasma. Therefore, this microviscometric approach based on a newly developed freely available script can be suggested for determination of the viscosity of small biological samples (e.g., body fluids).

Effect of Structure on the Initiation and Ignition Chemistry of Energetic Ionic Liquids

DTIC Science & Technology

2010-06-30

Thermolysis In the confined rapid thermolysis (CRT)/FTIR/ToFMS studies, the thermal decomposition is limited to a volume confined between two heated ...Jordan) is equipped with a 1m flight tube and a 44 mm microchannel plate (MCP) detector. Here, the recharging of the MCP detector limits the...conditions achieved by initially heating the sample at rates of approximately 2000 K/s. The products formed by decomposition under the afore

Relative importance of column and adsorption parameters on the productivity in preparative liquid chromatography II: Investigation of separation systems with competitive Langmuir adsorption isotherms.

PubMed

Forssén, Patrik; Samuelsson, Jörgen; Fornstedt, Torgny

2014-06-20

In this study we investigated how the maximum productivity for commonly used, realistic separation system with a competitive Langmuir adsorption isotherm is affected by changes in column length, packing particle size, mobile phase viscosity, maximum allowed column pressure, column efficiency, sample concentration/solubility, selectivity, monolayer saturation capacity and retention factor of the first eluting compound. The study was performed by generating 1000 random separation systems whose optimal injection volume was determined, i.e., the injection volume that gives the largest achievable productivity. The relative changes in largest achievable productivity when one of the parameters above changes was then studied for each system and the productivity changes for all systems were presented as distributions. We found that it is almost always beneficial to use shorter columns with high pressure drops over the column and that the selectivity should be greater than 2. However, the sample concentration and column efficiency have very limited effect on the maximum productivity. The effect of packing particle size depends on the flow rate limiting factor. If the pumps maximum flow rate is the limiting factor use smaller packing, but if the pressure of the system is the limiting factor use larger packing up to about 40μm. Copyright © 2014 Elsevier B.V. All rights reserved.

Sampling and Chemical Analysis of Potable Water for ISS Expeditions 12 and 13

NASA Technical Reports Server (NTRS)

Straub, John E. II; Plumlee, Deborah K.; Schultz, John R.

2007-01-01

The crews of Expeditions 12 and 13 aboard the International Space Station (ISS) continued to rely on potable water from two different sources, regenerated humidity condensate and Russian ground-supplied water. The Space Shuttle launched twice during the 12- months spanning both expeditions and docked with the ISS for delivery of hardware and supplies. However, no Shuttle potable water was transferred to the station during either of these missions. The chemical quality of the ISS onboard potable water supplies was verified by performing ground analyses of archival water samples at the Johnson Space Center (JSC) Water and Food Analytical Laboratory (WAFAL). Since no Shuttle flights launched during Expedition 12 and there was restricted return volume on the Russian Soyuz vehicle, only one chemical archive potable water sample was collected with U.S. hardware and returned during Expedition 12. This sample was collected in March 2006 and returned on Soyuz 11. The number and sensitivity of the chemical analyses performed on this sample were limited due to low sample volume. Shuttle flights STS-121 (ULF1.1) and STS-115 (12A) docked with the ISS in July and September of 2006, respectively. These flights returned to Earth with eight chemical archive potable water samples that were collected with U.S. hardware during Expedition 13. The average collected volume increased for these samples, allowing full chemical characterization to be performed. This paper presents a discussion of the results from chemical analyses performed on Expeditions 12 and 13 archive potable water samples. In addition to the results from the U.S. samples analyzed, results from pre-flight samples of Russian potable water delivered to the ISS on Progress vehicles and in-flight samples collected with Russian hardware during Expeditions 12 and 13 and analyzed at JSC are also discussed.

Simplification and validation of a large volume polyurethane foam sampler for the analysis of persistent hydrophobic compounds in drinking water.

PubMed

Choi, J W; Lee, J H; Moon, B S; Kannan, K

2008-08-01

The use of a large volume polyurethane foam (PUF) sampler was validated for rapid extraction of persistent organic pollutants (POPs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), in raw water and treated water from drinking water plants. To validate the recovery of target compounds in the sampling process, a (37)Cl-labeled standard was spiked into the 1st PUF plug prior to filtration. An accelerated solvent extraction method, as a pressurized liquid extractor (PLE), was optimized to extract the PUF plug. For sample preparation, tandem column chromatography (TCC) clean-up was used for rapid analysis. The recoveries of labeled compounds in the analytical method were 80-110% (n = 9). The optimized PUF-PLE-TCC method was applied in the analysis of raw water and treated potable water from seven drinking water plants in South Korea. The sample volume used was between 18 and 102 L for raw water at a flow rate of 0.4-2 L min(-1), 95 and 107 L for treated water at a flow rate of 1.5-2.2 L min(-1). Limit of quantitation (LOQ) was a function of sample volume and it decreased with increasing sample volume. The LOQ of PCDD/Fs in raw waters analyzed by this method was 3-11 times lower than that described using large-size disk-type solid phase extraction (SPE) method. The LOQ of PCDD/F congeners in raw water and treated water were 0.022-3.9 ng L(-1) and 0.018-0.74 ng L(-1), respectively. Octachlorinated dibenzo-p-dioxin (OCDD) was found in some raw water samples, while their concentrations were well below the tentative criterion set by the Japanese Environmental Ministry for drinking water. OCDD was below the LOQ in the treated drinking water.

The three-dimensional Multi-Block Advanced Grid Generation System (3DMAGGS)

NASA Technical Reports Server (NTRS)

Alter, Stephen J.; Weilmuenster, Kenneth J.

1993-01-01

As the size and complexity of three dimensional volume grids increases, there is a growing need for fast and efficient 3D volumetric elliptic grid solvers. Present day solvers are limited by computational speed and do not have all the capabilities such as interior volume grid clustering control, viscous grid clustering at the wall of a configuration, truncation error limiters, and convergence optimization residing in one code. A new volume grid generator, 3DMAGGS (Three-Dimensional Multi-Block Advanced Grid Generation System), which is based on the 3DGRAPE code, has evolved to meet these needs. This is a manual for the usage of 3DMAGGS and contains five sections, including the motivations and usage, a GRIDGEN interface, a grid quality analysis tool, a sample case for verifying correct operation of the code, and a comparison to both 3DGRAPE and GRIDGEN3D. Since it was derived from 3DGRAPE, this technical memorandum should be used in conjunction with the 3DGRAPE manual (NASA TM-102224).

Nanopore sensing at ultra-low concentrations using single-molecule dielectrophoretic trapping

PubMed Central

Freedman, Kevin J.; Otto, Lauren M.; Ivanov, Aleksandar P.; Barik, Avijit; Oh, Sang-Hyun; Edel, Joshua B.

2016-01-01

Single-molecule techniques are being developed with the exciting prospect of revolutionizing the healthcare industry by generating vast amounts of genetic and proteomic data. One exceptionally promising route is in the use of nanopore sensors. However, a well-known complexity is that detection and capture is predominantly diffusion limited. This problem is compounded when taking into account the capture volume of a nanopore, typically 108–1010 times smaller than the sample volume. To rectify this disproportionate ratio, we demonstrate a simple, yet powerful, method based on coupling single-molecule dielectrophoretic trapping to nanopore sensing. We show that DNA can be captured from a controllable, but typically much larger, volume and concentrated at the tip of a metallic nanopore. This enables the detection of single molecules at concentrations as low as 5 fM, which is approximately a 103 reduction in the limit of detection compared with existing methods, while still maintaining efficient throughput. PMID:26732171

Quantification of myo-inositol, 1,5-anhydro-D-sorbitol, and D-chiro-inositol using high-performance liquid chromatography with electrochemical detection in very small volume clinical samples

PubMed Central

Schimpf, Karen J.; Meek, Claudia C.; Leff, Richard D.; Phelps, Dale L.; Schmitz, Daniel J.; Cordle, Christopher T.

2015-01-01

Inositol is a six-carbon sugar alcohol and is one of nine biologically significant isomers of hexahydroxycyclohexane. Myo-inositol is the primary biologically active form and is present in higher concentrations in the fetus and newborn than in adults. It is currently being examined for the prevention of retinopathy of prematurity in newborn preterm infants. A robust method for quantifying myo-inositol (MI), D-chiro-inositol (DCI) and 1,5-anhydro-D-sorbitol (ADS) in very small-volume (25 μL) urine, blood serum and/or plasma samples was developed. Using a multiple-column, multiple mobile phase liquid chromatographic system with electrochemical detection, the method was validated with respect to (a) selectivity, (b) accuracy/recovery, (c) precision/reproducibility, (d) sensitivity, (e) stability and (f) ruggedness. The standard curve was linear and ranged from 0.5 to 30 mg/L for each of the three analytes. Above-mentioned performance measures were within acceptable limits described in the Food and Drug Administration’s Guidance for Industry: Bioanalytical Method Validation. The method was validated using blood serum and plasma collected using four common anticoagulants, and also by quantifying the accuracy and sensitivity of MI measured in simulated urine samples recovered from preterm infant diaper systems. The method performs satisfactorily measuring the three most common inositol isomers on 25 μL clinical samples of serum, plasma milk, and/or urine. Similar performance is seen testing larger volume samples of infant formulas and infant formula ingredients. MI, ADS and DCI may be accurately tested in urine samples collected from five different preterm infant diapers if the urine volume is greater than 2–5 mL. PMID:26010453

Ring-oven based preconcentration technique for microanalysis: simultaneous determination of Na, Fe, and Cu in fuel ethanol by laser induced breakdown spectroscopy.

PubMed

Cortez, Juliana; Pasquini, Celio

2013-02-05

The ring-oven technique, originally applied for classical qualitative analysis in the years 1950s to 1970s, is revisited to be used in a simple though highly efficient and green procedure for analyte preconcentration prior to its determination by the microanalytical techniques presently available. The proposed preconcentration technique is based on the dropwise delivery of a small volume of sample to a filter paper substrate, assisted by a flow-injection-like system. The filter paper is maintained in a small circular heated oven (the ring oven). Drops of the sample solution diffuse by capillarity from the center to a circular area of the paper substrate. After the total sample volume has been delivered, a ring with a sharp (c.a. 350 μm) circular contour, of about 2.0 cm diameter, is formed on the paper to contain most of the analytes originally present in the sample volume. Preconcentration coefficients of the analyte can reach 250-fold (on a m/m basis) for a sample volume as small as 600 μL. The proposed system and procedure have been evaluated to concentrate Na, Fe, and Cu in fuel ethanol, followed by simultaneous direct determination of these species in the ring contour, employing the microanalytical technique of laser induced breakdown spectroscopy (LIBS). Detection limits of 0.7, 0.4, and 0.3 μg mL(-1) and mean recoveries of (109 ± 13)%, (92 ± 18)%, and (98 ± 12)%, for Na, Fe, and Cu, respectively, were obtained in fuel ethanol. It is possible to anticipate the application of the technique, coupled to modern microanalytical and multianalyte techniques, to several analytical problems requiring analyte preconcentration and/or sample stabilization.

Fast vaporization solid phase microextraction and ion mobility spectrometry: A new approach for determination of creatinine in biological fluids.

PubMed

Jafari, Mostafa; Ebrahimzadeh, Homeira; Banitaba, Mohamma Hossein

2015-11-01

In this work a rapid and simple method for creatinine determination in urine and plasma samples based on aqueous derivatization of creatinine and complete vaporization of sample (as low as 10 µL), followed by ion mobility spectrometry analysis has been proposed. The effect of four important parameters (extraction temperature, total volume of solution, desorption temperature and extraction time) on ion mobility signal has been studied. Under the optimized conditions, the quantitative response of ion mobility spectrometry for creatinine was linear in the range of 0-500 mg L(-1) with a detection limit of 0.6 mg L(-1) in urine and 0-250 mg L(-1) with a detection limit of 2.6 mg L(-1) in plasma sample. The limit of quantitation of creatinine was 2.1 mg L(-1) and 8.7 mg L(-1) in urine and plasma samples, respectively. The relative standard deviation of the method was found to be 13%. The method was successfully applied to the analysis of creatinine in biological samples, showing recoveries from 92% to 104% in urine and 101-110% in plasma samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection of bacteria in suspension using a superconducting Quantum interference device

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

Grossman, H.L.; Myers, W.R.; Vreeland, V.J.

2003-06-09

We demonstrate a technique for detecting magnetically-labeled Listeria monocytogenes and for measuring the binding rate between antibody-linked magnetic particles and bacteria. This assay, which is both sensitive and straightforward to perform, can quantify specific bacteria in a sample without the need to immobilize the bacteria or wash away unbound magnetic particles. In the measurement, we add 50 nm diameter superparamagnetic particles, coated with antibodies, to a liquid sample containing L. monocytogenes. We apply a pulsed magnetic field to align the magnetic dipole moments and use a high transition temperature Superconducting Quantum Interference Device (SQUID), an extremely sensitive detector of magneticmore » flux, to measure the magnetic relaxation signal when the field is turned off. Unbound particles randomize direction by Brownian rotation too quickly to be detected. In contrast, particles bound to L. monocytogenes are effectively immobilized and relax in about 1 s by rotation of the internal dipole moment. This Neel relaxation process is detected by the SQUID. The measurements indicate a detection limit of (5.6 {+-} 1.1) x 10{sup 6} L. monocytogenes for a 20 {micro}L sample volume. If the sample volume were reduced to 1 nL, we estimate that the detection limit could be improved to 230 {+-} 40 L. monocytogenes cells. Time-resolved measurements yield the binding rate between the particles and bacteria.« less

Enhanced spectrophotometric detection of Hg in water samples by surface plasmon resonance of Au nanoparticles after preconcentration with vortex-assisted liquid-liquid microextraction

NASA Astrophysics Data System (ADS)

Martinis, Estefanía M.; Wuilloud, Rodolfo G.

2016-10-01

This article presents an efficient, simple, and cost-effective method for the determination of trace amounts of Hg by vortex-assisted liquid-liquid microextraction (VALLME) coupled to microvolume UV-Vis spectrophotometry. This method correlates changes in the intensity of localized surface plasmon resonance (LSPR) of tetraoctylammonium bromide (TOABr) coated Au nanoparticles (NPs) after interaction with Hg2+ ion. Spectroscopic measurements of the TOABr-coated Au NPs phase with particular absorption properties (strong and well-defined absorption bands) after analyte extraction by VALLME, provide an accurate and sensitive determination of Hg in water samples, comparable with measurements obtained by atomic absorption spectrometry (AAS). Different variables including sample volume, extraction time, and TOABr-coated Au NPs dispersion volume were carefully studied; final experimental conditions were 5 mL, 120 μL and 5 min respectively. The limit of detection (LOD) was 0.8 ng mL- 1. The calibration curve was linear at concentrations between the limit of quantification (LOQ) (4.9 ng mL- 1) and up to at least 120 ng mL- 1 of Hg. The relative standard deviation for six replicate determinations of 20 ng mL- 1 of Hg was 4.7%. This method exhibited an excellent analytical performance in terms of selectivity and sensitivity and it was finally applied for Hg determination in spiked tap and mineral water samples.

New approach to the fast screening of plant oil samples for F-, Cl-, Br- and S-organic compounds on the trace level.

PubMed

Chivarzin, M E; Revelsky, I A; Nikoshina, A V; Buldyzkova, A N; Chepeliansky, D A; Revelsky, A I; Buriak, A K

2016-04-01

The fast method of the simultaneous determination of F(-), Cl(-), Br(-) and SO4(2-) anions in the deionized water on the trace level by ion chromatography using thorough cleaning of respective water containers, 10 μM NaHCO3 water solution as eluent, short Metrohm (50 × 4 mm) separation column and a large water volume injection is proposed. Calculated detection limits are 10(-9)-10(-8)% depending on the element. The method for the fast screening of plant oil samples for the total fluorine-, chlorine-, bromine- and sulfur-organic compounds content (calculated for the respective elements) on the trace level is developed. It is based on the high temperature combustion of oil sample in oxygen flow, absorption of the conversion products in deionized water and whole absorbate volume analysis for F(-), Cl(-), Br(-) and SO4(2-) anions, corresponding to the respective elements, using the developed method of these anions analysis by ion chromatography. The samples of soya, olive, sunflower and cotton seed oil were analyzed. The method detection limits (for 1mg sample) were 2 × 10(-6)%, 2 × 10(-6)%, 5 × 10(-6)% and 5 × 10(-6)% for fluorine, chlorine, bromine and sulfur, respectively. The relative standard deviation was ≤ 15%. The method gives the compressed information about the total content of all target and nontarget fluorine-, chlorine-, bromine- and sulfur-organic compounds in plant oils. Copyright © 2015. Published by Elsevier B.V.

Comprehensive Monitoring Program: Final Biota Annual Report for 1989. Volume 2

DTIC Science & Technology

1990-06-01

samples from RMA lakes were highest in largemouth bass, a top predator . Largemouth bass and bluegill exhibited the widest geographic distribution...certification. BCtL = Siss examined with endrin concentrations below lower certified reporting limit of 0.0740 pg/g (MRI) or 0 036 pf (ESE) for aimal tipte and

Effects of Sampling and Spatio/Temporal Granularity in Traffic Monitoring on Anomaly Detectability

NASA Astrophysics Data System (ADS)

Ishibashi, Keisuke; Kawahara, Ryoichi; Mori, Tatsuya; Kondoh, Tsuyoshi; Asano, Shoichiro

We quantitatively evaluate how sampling and spatio/temporal granularity in traffic monitoring affect the detectability of anomalous traffic. Those parameters also affect the monitoring burden, so network operators face a trade-off between the monitoring burden and detectability and need to know which are the optimal paramter values. We derive equations to calculate the false positive ratio and false negative ratio for given values of the sampling rate, granularity, statistics of normal traffic, and volume of anomalies to be detected. Specifically, assuming that the normal traffic has a Gaussian distribution, which is parameterized by its mean and standard deviation, we analyze how sampling and monitoring granularity change these distribution parameters. This analysis is based on observation of the backbone traffic, which exhibits spatially uncorrelated and temporally long-range dependence. Then we derive the equations for detectability. With those equations, we can answer the practical questions that arise in actual network operations: what sampling rate to set to find the given volume of anomaly, or, if the sampling is too high for actual operation, what granularity is optimal to find the anomaly for a given lower limit of sampling rate.

High-throughput analysis using non-depletive SPME: challenges and applications to the determination of free and total concentrations in small sample volumes.

PubMed

Boyacı, Ezel; Bojko, Barbara; Reyes-Garcés, Nathaly; Poole, Justen J; Gómez-Ríos, Germán Augusto; Teixeira, Alexandre; Nicol, Beate; Pawliszyn, Janusz

2018-01-18

In vitro high-throughput non-depletive quantitation of chemicals in biofluids is of growing interest in many areas. Some of the challenges facing researchers include the limited volume of biofluids, rapid and high-throughput sampling requirements, and the lack of reliable methods. Coupled to the above, growing interest in the monitoring of kinetics and dynamics of miniaturized biosystems has spurred the demand for development of novel and revolutionary methodologies for analysis of biofluids. The applicability of solid-phase microextraction (SPME) is investigated as a potential technology to fulfill the aforementioned requirements. As analytes with sufficient diversity in their physicochemical features, nicotine, N,N-Diethyl-meta-toluamide, and diclofenac were selected as test compounds for the study. The objective was to develop methodologies that would allow repeated non-depletive sampling from 96-well plates, using 100 µL of sample. Initially, thin film-SPME was investigated. Results revealed substantial depletion and consequent disruption in the system. Therefore, new ultra-thin coated fibers were developed. The applicability of this device to the described sampling scenario was tested by determining the protein binding of the analytes. Results showed good agreement with rapid equilibrium dialysis. The presented method allows high-throughput analysis using small volumes, enabling fast reliable free and total concentration determinations without disruption of system equilibrium.

Combination of QuEChERS and DLLME for GC-MS determination of pesticide residues in orange samples.

PubMed

Andraščíková, Mária; Hrouzková, Svetlana; Cunha, Sara C

2013-01-01

A new method combining QuEChERS (quick, easy, cheap, effective, rugged and safe) and DLLME (dispersive liquid-liquid microextraction) followed by gas chromatography-mass spectrometry with selected ion monitoring (SIM) was developed for the simultaneous determination of 19 pesticides from nine chemical groups exhibiting or suspected to exhibit endocrine-disrupting properties in orange samples. Acetonitrile extract obtained from QuEChERS extraction was used for DLLME as dispersive solvent and carbon tetrachloride as extractive solvent to increase the enrichment factor of the extraction procedure. The effect of several extraction parameters, such as volume extract achieved by the QuEChERS method and subsequently used for DLLME, selection of extractive solvent and its volume, was tested. Under optimum conditions, good linearity, satisfactory recoveries and repeatability were obtained. Limits of quantification (LOQs) achieved (ranging from 0.02 to 47 ng/g) were below the maximum residue limits established by the European Union. The proposed method was applied to the monitoring of pesticide residue levels in oranges commercialised in Portugal.

Microextraction by packed sorbent: an emerging, selective and high-throughput extraction technique in bioanalysis.

PubMed

Pereira, Jorge; Câmara, José S; Colmsjö, Anders; Abdel-Rehim, Mohamed

2014-06-01

Sample preparation is an important analytical step regarding the isolation and concentration of desired components from complex matrices and greatly influences their reliable and accurate analysis and data quality. It is the most labor-intensive and error-prone process in analytical methodology and, therefore, may influence the analytical performance of the target analytes quantification. Many conventional sample preparation methods are relatively complicated, involving time-consuming procedures and requiring large volumes of organic solvents. Recent trends in sample preparation include miniaturization, automation, high-throughput performance, on-line coupling with analytical instruments and low-cost operation through extremely low volume or no solvent consumption. Micro-extraction techniques, such as micro-extraction by packed sorbent (MEPS), have these advantages over the traditional techniques. This paper gives an overview of MEPS technique, including the role of sample preparation in bioanalysis, the MEPS description namely MEPS formats (on- and off-line), sorbents, experimental and protocols, factors that affect the MEPS performance, and the major advantages and limitations of MEPS compared with other sample preparation techniques. We also summarize MEPS recent applications in bioanalysis. Copyright © 2014 John Wiley & Sons, Ltd.

Determination of polycyclic aromatic hydrocarbons in drinking water samples by solid-phase nanoextraction and high-performance liquid chromatography.

PubMed

Wang, Huiyong; Campiglia, Andres D

2008-11-01

A novel alternative is presented for the extraction and preconcentration of polycyclic aromatic hydrocarbons (PAH) from water samples. The new approachwhich we have named solid-phase nanoextraction (SPNE)takes advantage of the strong affinity that exists between PAH and gold nanoparticles. Carefully optimization of experimental parameters has led to a high-performance liquid chromatography method with excellent analytical figures of merit. Its most striking feature correlates to the small volume of water sample (500 microL) for complete PAH analyses. The limits of detection ranged from 0.9 (anthracene) to 58 ng.L (-1) (fluorene). The relative standard deviations at medium calibration concentrations vary from 3.2 (acenaphthene) to 9.1% (naphthalene). The analytical recoveries from tap water samples of the six regulated PAH varied from 83.3 +/- 2.4 (benzo[ k]fluoranthene) to 95.7 +/- 4.1% (benzo[ g,h,i]perylene). The entire extraction procedure consumes less than 100 microL of organic solvents per sample, which makes it environmentally friendly. The small volume of extracting solution makes SPNE a relatively inexpensive extraction approach.

Pore water sampling in acid sulfate soils: a new peeper method.

PubMed

Johnston, Scott G; Burton, Edward D; Keene, Annabelle F; Bush, Richard T; Sullivan, Leigh A; Isaacson, Lloyd

2009-01-01

This study describes the design, deployment, and application of a modified equilibration dialysis device (peeper) optimized for sampling pore waters in acid sulfate soils (ASS). The modified design overcomes the limitations of traditional-style peepers, when sampling firm ASS materials over relatively large depth intervals. The new peeper device uses removable, individual cells of 25 mL volume housed in a 1.5 m long rigid, high-density polyethylene rod. The rigid housing structure allows the device to be inserted directly into relatively firm soils without requiring a supporting frame. The use of removable cells eliminates the need for a large glove-box after peeper retrieval, thus simplifying physical handling. Removable cells are easily maintained in an inert atmosphere during sample processing and the 25-mL sample volume is sufficient for undertaking multiple analyses. A field evaluation of equilibration times indicates that 32 to 38 d of deployment was necessary. Overall, the modified method is simple and effective and well suited to acquisition and processing of redox-sensitive pore water profiles>1 m deep in acid sulfate soil or any other firm wetland soils.

Polymer monolithic capillary microextraction combined on-line with inductively coupled plasma MS for the determination of trace rare earth elements in biological samples.

PubMed

Zhang, Lin; Chen, Beibei; He, Man; Hu, Bin

2013-07-01

A rapid and sensitive method based on polymer monolithic capillary microextraction combined on-line with microconcentric nebulization inductively coupled plasma MS has been developed for the determination of trace/ultratrace rare earth elements in biological samples. For this purpose, the iminodiacetic acid modified poly(glycidyl methacrylate-trimethylolpropane trimethacrylate) monolithic capillary was prepared and characterized by SEM and FTIR spectroscopy. Factors affecting the extraction efficiency, such as sample pH, sample flow rate, sample/eluent volume, and coexisting ions were investigated in detail. Under the optimal conditions, the LODs for rare earth elements were in the range of 0.08 (Er) to 0.97 ng/L (Nd) with a sampling frequency of 8.5 h(-1), and the RSDs were between 1.5% (Sm) and 7.4% (Nd) (c = 20 ng/L, n = 7). The proposed method was successfully applied to the analysis of trace/ultratrace rare earth elements in human urine and serum samples, and the recoveries for the spiked samples were in the range of 82-105%. The developed method was simple, rapid, sensitive, and favorable for the analysis of trace/ultratrace rare earth elements in biological samples with limited sample volume. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Analysis of Scalable GPU-Based Ray-Guided Volume Rendering

PubMed Central

Fogal, Thomas; Schiewe, Alexander; Krüger, Jens

2014-01-01

Volume rendering continues to be a critical method for analyzing large-scale scalar fields, in disciplines as diverse as biomedical engineering and computational fluid dynamics. Commodity desktop hardware has struggled to keep pace with data size increases, challenging modern visualization software to deliver responsive interactions for O(N3) algorithms such as volume rendering. We target the data type common in these domains: regularly-structured data. In this work, we demonstrate that the major limitation of most volume rendering approaches is their inability to switch the data sampling rate (and thus data size) quickly. Using a volume renderer inspired by recent work, we demonstrate that the actual amount of visualizable data for a scene is typically bound considerably lower than the memory available on a commodity GPU. Our instrumented renderer is used to investigate design decisions typically swept under the rug in volume rendering literature. The renderer is freely available, with binaries for all major platforms as well as full source code, to encourage reproduction and comparison with future research. PMID:25506079

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by injector port silylation coupled with gas chromatography-tandem mass spectrometry for the determination of nine bisphenols in bottled carbonated beverages.

PubMed

Mandrah, Kapil; Satyanarayana, G N V; Roy, Somendu Kumar

2017-12-15

In the present study, a method has been efficiently developed for the first time to determine nine bisphenol analogues [bisphenol A (BPA), bisphenol C (BPC), bisphenol AF (BPAF), bisphenol E (BPE), bisphenol F (BPF), bisphenol G (BPG), bisphenol M (BPM), bisphenol S (BPS), and bisphenol Z (BPZ)] together in bottled carbonated beverages (collected from the local market of Lucknow, India) using dispersive liquid-liquid microextraction process. This is based on solidification of floating organic droplet (DLLME-SFO) followed by injector port silylation coupled with gas chromatography-tandem mass spectrometry. The process investigated parameters of DLLME-SFO (including the type of extraction and disperser solvents with their volumes, effect of pH, ionic strength, and the sample volume), factors influencing to injection port derivatization like, collision energy, injector port temperature, derivatizing reagent with sample injection volume, and type of organic solvent. BPA, BPF, BPZ, and BPS were detected in each sample; whereas, other bisphenols were also detected in some carbonated beverage samples. After optimizing the required conditions, good linearity of analytes was achieved in the range of 0.097-100ngmL -1 with coefficients of determination (R 2 )≥0.995. Intra-day and inter day precision of the method was good, with relative standard deviation (% RSD)≤10.95%. The limits of detection (LOD) and limits of quantification (LOQ) values of all bisphenols were ranged from 0.021 to 0.104ngmL -1 and 0.070 to 0.343ngmL -1 , respectively. The recovery of extraction was good (73.15-95.08%) in carbonated beverage samples and good enrichment factors (96.36-117.33) were found. Thus, the developed method of microextraction was highly precise, fast, and reproducible to determine the level of contaminants in bottled carbonated beverages. Copyright © 2017 Elsevier B.V. All rights reserved.

Feasibility of high-resolution one-dimensional relaxation imaging at low magnetic field using a single-sided NMR scanner applied to articular cartilage

NASA Astrophysics Data System (ADS)

Rössler, Erik; Mattea, Carlos; Stapf, Siegfried

2015-02-01

Low field Nuclear Magnetic Resonance increases the contrast of the longitudinal relaxation rate in many biological tissues; one prominent example is hyaline articular cartilage. In order to take advantage of this increased contrast and to profile the depth-dependent variations, high resolution parameter measurements are carried out which can be of critical importance in an early diagnosis of cartilage diseases such as osteoarthritis. However, the maximum achievable spatial resolution of parameter profiles is limited by factors such as sensor geometry, sample curvature, and diffusion limitation. In this work, we report on high-resolution single-sided NMR scanner measurements with a commercial device, and quantify these limitations. The highest achievable spatial resolution on the used profiler, and the lateral dimension of the sensitive volume were determined. Since articular cartilage samples are usually bent, we also focus on averaging effects inside the horizontally aligned sensitive volume and their impact on the relaxation profiles. Taking these critical parameters into consideration, depth-dependent relaxation time profiles with the maximum achievable vertical resolution of 20 μm are discussed, and are correlated with diffusion coefficient profiles in hyaline articular cartilage in order to reconstruct T2 maps from the diffusion-weighted CPMG decays of apparent relaxation rates.

Association of allostatic load with brain structure and cognitive ability in later life

PubMed Central

Booth, Tom; Royle, Natalie A.; Corley, Janie; Gow, Alan J.; Valdés Hernández, Maria del C.; Muñoz Maniega, Susana; Ritchie, Stuart J.; Bastin, Mark E.; Starr, John M.; Wardlaw, Joanna M.; Deary, Ian J.

2015-01-01

Allostatic load (AL) has been proposed as a general framework for understanding the cumulative effects of life stress on individuals. Despite growing interest in AL, limited research has been conducted on aging samples. We consider the association of AL (operationalized by a range of inflammatory, cardiovascular, and metabolic measures) with a range of brain volume measurements and cognitive ability in a large cohort sample of older adults (n = 658, mean age = 72.5 years, standard deviation = 0.7) using structural equation modeling. AL was significantly inversely associated with total brain volume (range of standardized β = −0.16 to −0.20) and white-matter volume (−0.35 to −0.36) and positively with hippocampal volume (0.10–0.15) but not gray-matter volume (0.04). AL was also significantly inversely associated with general cognitive ability (range β = −0.13 to −0.20), processing speed (−0.20 to −0.22), and knowledge (−0.18 to −0.20) but not memory or nonverbal reasoning. The associations of AL with cognitive abilities were not mediated by these brain volume measures. AL did not predict cognitive change from age 11 to approximately age 73. The findings suggest a link between AL and later life brain health and cognitive functioning. PMID:25659881

High-Field Liquid-State Dynamic Nuclear Polarization in Microliter Samples.

PubMed

Yoon, Dongyoung; Dimitriadis, Alexandros I; Soundararajan, Murari; Caspers, Christian; Genoud, Jeremy; Alberti, Stefano; de Rijk, Emile; Ansermet, Jean-Philippe

2018-05-01

Nuclear hyperpolarization in the liquid state by dynamic nuclear polarization (DNP) has been of great interest because of its potential use in NMR spectroscopy of small samples of biological and chemical compounds in aqueous media. Liquid state DNP generally requires microwave resonators in order to generate an alternating magnetic field strong enough to saturate electron spins in the solution. As a consequence, the sample size is limited to dimensions of the order of the wavelength, and this restricts the sample volume to less than 100 nL for DNP at 9 T (∼260 GHz). We show here a new approach that overcomes this sample size limitation. Large saturation of electron spins was obtained with a high-power (∼150 W) gyrotron without microwave resonators. Since high power microwaves can cause serious dielectric heating in polar solutions, we designed a planar probe which effectively alleviates dielectric heating. A thin liquid sample of 100 μm of thickness is placed on a block of high thermal conductivity aluminum nitride, with a gold coating that serves both as a ground plane and as a heat sink. A meander or a coil were used for NMR. We performed 1 H DNP at 9.2 T (∼260 GHz) and at room temperature with 10 μL of water, a volume that is more than 100× larger than reported so far. The 1 H NMR signal is enhanced by a factor of about -10 with 70 W of microwave power. We also demonstrated the liquid state of 31 P DNP in fluorobenzene containing triphenylphosphine and obtained an enhancement of ∼200.

Environmental Validation of Legionella Control in a VHA Facility Water System.

PubMed

Jinadatha, Chetan; Stock, Eileen M; Miller, Steve E; McCoy, William F

2018-03-01

OBJECTIVES We conducted this study to determine what sample volume, concentration, and limit of detection (LOD) are adequate for environmental validation of Legionella control. We also sought to determine whether time required to obtain culture results can be reduced compared to spread-plate culture method. We also assessed whether polymerase chain reaction (PCR) and in-field total heterotrophic aerobic bacteria (THAB) counts are reliable indicators of Legionella in water samples from buildings. DESIGN Comparative Legionella screening and diagnostics study for environmental validation of a healthcare building water system. SETTING Veterans Health Administration (VHA) facility water system in central Texas. METHODS We analyzed 50 water samples (26 hot, 24 cold) from 40 sinks and 10 showers using spread-plate cultures (International Standards Organization [ISO] 11731) on samples shipped overnight to the analytical lab. In-field, on-site cultures were obtained using the PVT (Phigenics Validation Test) culture dipslide-format sampler. A PCR assay for genus-level Legionella was performed on every sample. RESULTS No practical differences regardless of sample volume filtered were observed. Larger sample volumes yielded more detections of Legionella. No statistically significant differences at the 1 colony-forming unit (CFU)/mL or 10 CFU/mL LOD were observed. Approximately 75% less time was required when cultures were started in the field. The PCR results provided an early warning, which was confirmed by spread-plate cultures. The THAB results did not correlate with Legionella status. CONCLUSIONS For environmental validation at this facility, we confirmed that (1) 100 mL sample volumes were adequate, (2) 10× concentrations were adequate, (3) 10 CFU/mL LOD was adequate, (4) in-field cultures reliably reduced time to get results by 75%, (5) PCR provided a reliable early warning, and (6) THAB was not predictive of Legionella results. Infect Control Hosp Epidemiol 2018;39:259-266.

Ray Casting of Large Multi-Resolution Volume Datasets

NASA Astrophysics Data System (ADS)

Lux, C.; Fröhlich, B.

2009-04-01

High quality volume visualization through ray casting on graphics processing units (GPU) has become an important approach for many application domains. We present a GPU-based, multi-resolution ray casting technique for the interactive visualization of massive volume data sets commonly found in the oil and gas industry. Large volume data sets are represented as a multi-resolution hierarchy based on an octree data structure. The original volume data is decomposed into small bricks of a fixed size acting as the leaf nodes of the octree. These nodes are the highest resolution of the volume. Coarser resolutions are represented through inner nodes of the hierarchy which are generated by down sampling eight neighboring nodes on a finer level. Due to limited memory resources of current desktop workstations and graphics hardware only a limited working set of bricks can be locally maintained for a frame to be displayed. This working set is chosen to represent the whole volume at different local resolution levels depending on the current viewer position, transfer function and distinct areas of interest. During runtime the working set of bricks is maintained in CPU- and GPU memory and is adaptively updated by asynchronously fetching data from external sources like hard drives or a network. The CPU memory hereby acts as a secondary level cache for these sources from which the GPU representation is updated. Our volume ray casting algorithm is based on a 3D texture-atlas in GPU memory. This texture-atlas contains the complete working set of bricks of the current multi-resolution representation of the volume. This enables the volume ray casting algorithm to access the whole working set of bricks through only a single 3D texture. For traversing rays through the volume, information about the locations and resolution levels of visited bricks are required for correct compositing computations. We encode this information into a small 3D index texture which represents the current octree subdivision on its finest level and spatially organizes the bricked data. This approach allows us to render a bricked multi-resolution volume data set utilizing only a single rendering pass with no loss of compositing precision. In contrast most state-of-the art volume rendering systems handle the bricked data as individual 3D textures, which are rendered one at a time while the results are composited into a lower precision frame buffer. Furthermore, our method enables us to integrate advanced volume rendering techniques like empty-space skipping, adaptive sampling and preintegrated transfer functions in a very straightforward manner with virtually no extra costs. Our interactive volume ray tracing implementation allows high quality visualizations of massive volume data sets of tens of Gigabytes in size on standard desktop workstations.

Sampling Strategies and Processing of Biobank Tissue Samples from Porcine Biomedical Models.

PubMed

Blutke, Andreas; Wanke, Rüdiger

2018-03-06

In translational medical research, porcine models have steadily become more popular. Considering the high value of individual animals, particularly of genetically modified pig models, and the often-limited number of available animals of these models, establishment of (biobank) collections of adequately processed tissue samples suited for a broad spectrum of subsequent analyses methods, including analyses not specified at the time point of sampling, represent meaningful approaches to take full advantage of the translational value of the model. With respect to the peculiarities of porcine anatomy, comprehensive guidelines have recently been established for standardized generation of representative, high-quality samples from different porcine organs and tissues. These guidelines are essential prerequisites for the reproducibility of results and their comparability between different studies and investigators. The recording of basic data, such as organ weights and volumes, the determination of the sampling locations and of the numbers of tissue samples to be generated, as well as their orientation, size, processing and trimming directions, are relevant factors determining the generalizability and usability of the specimen for molecular, qualitative, and quantitative morphological analyses. Here, an illustrative, practical, step-by-step demonstration of the most important techniques for generation of representative, multi-purpose biobank specimen from porcine tissues is presented. The methods described here include determination of organ/tissue volumes and densities, the application of a volume-weighted systematic random sampling procedure for parenchymal organs by point-counting, determination of the extent of tissue shrinkage related to histological embedding of samples, and generation of randomly oriented samples for quantitative stereological analyses, such as isotropic uniform random (IUR) sections generated by the "Orientator" and "Isector" methods, and vertical uniform random (VUR) sections.

Reusable and Mediator-Free Cholesterol Biosensor Based on Cholesterol Oxidase Immobilized onto TGA-SAM Modified Smart Bio-Chips

PubMed Central

Rahman, Mohammed M.

2014-01-01

A reusable and mediator-free cholesterol biosensor based on cholesterol oxidase (ChOx) was fabricated based on self-assembled monolayer (SAM) of thioglycolic acid (TGA) (covalent enzyme immobilization by dropping method) using bio-chips. Cholesterol was detected with modified bio-chip (Gold/Thioglycolic-acid/Cholesterol-oxidase i.e., Au/TGA/ChOx) by reliable cyclic voltammetric (CV) technique at room conditions. The Au/TGA/ChOx modified bio-chip sensor demonstrates good linearity (1.0 nM to 1.0 mM; R = 0.9935), low-detection limit (∼0.42 nM, SNR∼3), and higher sensitivity (∼74.3 µAµM−1cm−2), lowest-small sample volume (50.0 μL), good stability, and reproducibility. To the best of our knowledge, this is the first statement with a very high sensitivity, low-detection limit, and low-sample volumes are required for cholesterol biosensor using Au/TGA/ChOx-chips assembly. The result of this facile approach was investigated for the biomedical applications for real samples at room conditions with significant assembly (Au/TGA/ChOx) towards the development of selected cholesterol biosensors, which can offer analytical access to a large group of enzymes for wide range of biomedical applications in health-care fields. PMID:24949733

Whole air canister sampling coupled with preconcentration GC/MS analysis of part-per-trillion levels of trimethylsilanol in semiconductor cleanroom air.

PubMed

Herrington, Jason S

2013-08-20

The costly damage airborne trimethylsilanol (TMS) exacts on optics in the semiconductor industry has resulted in the demand for accurate and reliable methods for measuring TMS at trace levels (i.e., parts per trillion, volume per volume of air [ppt(v)] [~ng/m(3)]). In this study I developed a whole air canister-based approach for field sampling trimethylsilanol in air, as well as a preconcentration gas chromatography/mass spectrometry laboratory method for analysis. The results demonstrate clean canister blanks (0.06 ppt(v) [0.24 ng/m(3)], which is below the detection limit), excellent linearity (a calibration relative response factor relative standard deviation [RSD] of 9.8%) over a wide dynamic mass range (1-100 ppt(v)), recovery/accuracy of 93%, a low selected ion monitoring method detection limit of 0.12 ppt(v) (0.48 ng/m(3)), replicate precision of 6.8% RSD, and stability (84% recovery) out to four days of storage at room temperature. Samples collected at two silicon wafer fabrication facilities ranged from 10.0 to 9120 ppt(v) TMS and appear to be associated with the use of hexamethyldisilazane priming agent. This method will enable semiconductor cleanroom managers to monitor and control for trace levels of trimethylsilanol.

Ultrasonic-energy enhance the ionic liquid-based dual microextraction to preconcentrate the lead in ground and stored rain water samples as compared to conventional shaking method.

PubMed

Nizamani, Sooraj; Kazi, Tasneem G; Afridi, Hassan I

2018-01-01

An efficient preconcentration technique based on ultrasonic-assisted ionic liquid-based dual microextraction (UA-ILDµE) method has been developed to preconcentrate the lead (Pb +2 ) in ground and stored rain water. In the current proposed method, Pb +2 was complexed with a chelating agent (dithizone), whereas an ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate) was used for extraction purpose. The ultrasonic irradiation and electrical shaking system were applied to enhance the dispersion and extraction of Pb +2 complex in aqueous samples. For second phase, dual microextraction (DµE phase), the enriched Pb +2 complex in ionic liquid, extracted back into the acidic aqueous solution and finally determined by flame atomic absorption spectrometry. Some major analytical parameters that influenced the extraction efficiency of developed method, such as pH, concentration of ligand, volume of ionic liquid and samples, time of shaking in thermostatic electrical shaker and ultrasonic bath, effect of back extracting HNO 3 volume, matrix effect, centrifugation time and rate were optimized. At the sample volume of 25mL, the calculated preconcentration factor was 62.2. The limit of detection of proposed procedure for Pb +2 ions was found to be 0.54μgL -1 . The validation of developed method was performed by the analysis of certified sample of water SRM 1643e and standard addition method in a real water sample. The extraction recovery of Pb +2 was enhanced≥2% with shaking time of 80s in ultrasonic bath as compared to used thermostatic electrical shaker, where for optimum recovery up to 10min was required. The developed procedure was successfully used for the enrichment of Pb +2 in ground and stored rain water (surface water) samples of an endemic region of Pakistan. The resulted data indicated that the ground water samples were highly contaminated with Pb +2 , while some of the surface water samples were also have higher values of Pb +2 than permissible limit of WHO. The concentration of Pb +2 in surface and ground water samples was found in the range of 17.5-24.5 and 25.6-99.1μgL - 1 respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Robust high-throughput batch screening method in 384-well format with optical in-line resin quantification.

PubMed

Kittelmann, Jörg; Ottens, Marcel; Hubbuch, Jürgen

2015-04-15

High-throughput batch screening technologies have become an important tool in downstream process development. Although continuative miniaturization saves time and sample consumption, there is yet no screening process described in the 384-well microplate format. Several processes are established in the 96-well dimension to investigate protein-adsorbent interactions, utilizing between 6.8 and 50 μL resin per well. However, as sample consumption scales with resin volumes and throughput scales with experiments per microplate, they are limited in costs and saved time. In this work, a new method for in-well resin quantification by optical means, applicable in the 384-well format, and resin volumes as small as 0.1 μL is introduced. A HTS batch isotherm process is described, utilizing this new method in combination with optical sample volume quantification for screening of isotherm parameters in 384-well microplates. Results are qualified by confidence bounds determined by bootstrap analysis and a comprehensive Monte Carlo study of error propagation. This new approach opens the door to a variety of screening processes in the 384-well format on HTS stations, higher quality screening data and an increase in throughput. Copyright © 2015 Elsevier B.V. All rights reserved.

On the universality of the two-point galaxy correlation function

NASA Technical Reports Server (NTRS)

Davis, Marc; Meiksin, Avery; Strauss, Michael A.; Da Costa, L. Nicolaci; Yahil, Amos

1988-01-01

The behavior of the two-point galaxy correlation function in volume-limited subsamples of three complete redshift surveys is investigated. The correlation length is shown to scale approximately as the square root of the distance limit in both the CfA and Southern Sky catalogs, but to be independent of the distance limit in the IRAS sample. This effect is found to be due to factors such as the large positive density fluctuations in the foreground of the optically selected catalogs biasing the correlation length estimate downward, and the brightest galaxies appearing to be more strongly clustered than the mean.

Statistical representative elementary volumes of porous media determined using greyscale analysis of 3D tomograms

NASA Astrophysics Data System (ADS)

Bruns, S.; Stipp, S. L. S.; Sørensen, H. O.

2017-09-01

Digital rock physics carries the dogmatic concept of having to segment volume images for quantitative analysis but segmentation rejects huge amounts of signal information. Information that is essential for the analysis of difficult and marginally resolved samples, such as materials with very small features, is lost during segmentation. In X-ray nanotomography reconstructions of Hod chalk we observed partial volume voxels with an abundance that limits segmentation based analysis. Therefore, we investigated the suitability of greyscale analysis for establishing statistical representative elementary volumes (sREV) for the important petrophysical parameters of this type of chalk, namely porosity, specific surface area and diffusive tortuosity, by using volume images without segmenting the datasets. Instead, grey level intensities were transformed to a voxel level porosity estimate using a Gaussian mixture model. A simple model assumption was made that allowed formulating a two point correlation function for surface area estimates using Bayes' theory. The same assumption enables random walk simulations in the presence of severe partial volume effects. The established sREVs illustrate that in compacted chalk, these simulations cannot be performed in binary representations without increasing the resolution of the imaging system to a point where the spatial restrictions of the represented sample volume render the precision of the measurement unacceptable. We illustrate this by analyzing the origins of variance in the quantitative analysis of volume images, i.e. resolution dependence and intersample and intrasample variance. Although we cannot make any claims on the accuracy of the approach, eliminating the segmentation step from the analysis enables comparative studies with higher precision and repeatability.

Comparison of brain volume abnormalities between ADHD and conduct disorder in adolescence

PubMed Central

Stevens, Michael C.; Haney-Caron, Emily

2012-01-01

Background Previous studies of brain structure abnormalities in conduct disorder and attention-deficit/hyperactivity disorder (ADHD) samples have been limited owing to cross-comorbidity, preventing clear understanding of which structural brain abnormalities might be specific to or shared by each disorder. To our knowledge, this study was the first direct comparison of grey and white matter volumes in diagnostically “pure” (i.e., no comorbidities) conduct disorder and ADHD samples. Methods Groups of adolescents with noncormobid conduct disorder and with noncomorbid, combined-subtype ADHD were compared with age- and sex-matched controls using DARTEL voxel-based analysis of T1-weighted brain structure images. Analysis of variance with post hoc analyses compared whole brain grey and white matter volumes among the groups. Results We included 24 adolescents in each study group. There was an overall 13% reduction in grey matter volume in adolescents with conduct disorder, reflecting numerous frontal, temporal, parietal and subcortical deficits. The same grey matter regions typically were not abnormal in those with ADHD. Deficits in frontal lobe regions previously identified in studies of patients with ADHD either were not detected, or group differences from controls were not as strong as those between the conduct disorder and control groups. White matter volume measurements did not differentiate conduct disorder and ADHD. Limitations Our modest sample sizes prevented meaningful examination of individual features of ADHD or conduct disorder, such as aggression, callousness, or hyperactive versus inattentive symptom subtypes. Conclusion The evidence supports theories of frontotemporal abnormalities in adolescents with conduct disorder, but raises questions about the prominence of frontal lobe and striatal structural abnormalities in those with noncomorbid, combined-subtype ADHD. The latter point is clinically important, given the widely held belief that ADHD is associated with numerous frontal lobe structural deficits, a conclusion that is not strongly supported following direct comparison of diagnostically pure groups. The results are important for future etiological studies, particularly those seeking to identify how early expression of specific brain structure abnormalities could potentiate the risk for antisocial behaviour. PMID:22663946

Immunochemistry for high-throughput screening of human exhaled breath condensate (EBC) media: implementation of automated Quanterix SIMOA instrumentation.

PubMed

Pleil, Joachim D; Angrish, Michelle M; Madden, Michael C

2015-12-11

Immunochemistry is an important clinical tool for indicating biological pathways leading towards disease. Standard enzyme-linked immunosorbent assays (ELISA) are labor intensive and lack sensitivity at low-level concentrations. Here we report on emerging technology implementing fully-automated ELISA capable of molecular level detection and describe application to exhaled breath condensate (EBC) samples. The Quanterix SIMOA HD-1 analyzer was evaluated for analytical performance for inflammatory cytokines (IL-6, TNF-α, IL-1β and IL-8). The system was challenged with human EBC representing the most dilute and analytically difficult of the biological media. Calibrations from synthetic samples and spiked EBC showed excellent linearity at trace levels (r(2)  >  0.99). Sensitivities varied by analyte, but were robust from ~0.006 (IL-6) to ~0.01 (TNF-α) pg ml(-1). All analytes demonstrated response suppression when diluted with deionized water and so assay buffer diluent was found to be a better choice. Analytical runs required ~45 min setup time for loading samples, reagents, calibrants, etc., after which the instrument performs without further intervention for up to 288 separate samples. Currently, available kits are limited to single-plex analyses and so sample volumes require adjustments. Sample dilutions should be made with assay diluent to avoid response suppression. Automation performs seamlessly and data are automatically analyzed and reported in spreadsheet format. The internal 5-parameter logistic (pl) calibration model should be supplemented with a linear regression spline at the very lowest analyte levels, (<1.3 pg ml(-1)). The implementation of the automated Quanterix platform was successfully demonstrated using EBC, which poses the greatest challenge to ELISA due to limited sample volumes and low protein levels.

Development of a new multi-residue laser diode thermal desorption atmospheric pressure chemical ionization tandem mass spectrometry method for the detection and quantification of pesticides and pharmaceuticals in wastewater samples.

PubMed

Boisvert, Michel; Fayad, Paul B; Sauvé, Sébastien

2012-11-19

A new solid phase extraction (SPE) method coupled to a high throughput sample analysis technique was developed for the simultaneous determination of nine selected emerging contaminants in wastewater (atrazine, desethylatrazine, 17β-estradiol, ethynylestradiol, norethindrone, caffeine, carbamazepine, diclofenac and sulfamethoxazole). We specifically included pharmaceutical compounds from multiple therapeutic classes, as well as pesticides. Sample pre-concentration and clean-up was performed using a mixed-mode SPE cartridge (Strata ABW) having both cation and anion exchange properties, followed by analysis by laser diode thermal desorption atmospheric pressure chemical ionization coupled to tandem mass spectrometry (LDTD-APCI-MS/MS). The LDTD interface is a new high-throughput sample introduction method, which reduces total analysis time to less than 15s per sample as compared to minutes with traditional liquid-chromatography coupled to tandem mass spectrometry (LC-MS/MS). Several SPE parameters were evaluated in order to optimize recovery efficiencies when extracting analytes from wastewater, such as the nature of the stationary phase, the loading flow rate, the extraction pH, the volume and composition of the washing solution and the initial sample volume. The method was successfully applied to real wastewater samples from the primary sedimentation tank of a municipal wastewater treatment plant. Recoveries of target compounds from wastewater ranged from 78% to 106%, the limit of detection ranged from 30 to 122ng L(-1) while the limit of quantification ranged from 90 to 370ng L(-1). Calibration curves in the wastewater matrix showed good linearity (R(2)≥0.991) for all target analytes and the intraday and interday coefficient of variation was below 15%, reflecting a good precision. Copyright © 2012 Elsevier B.V. All rights reserved.

Solid-contact potentiometric polymer membrane microelectrodes for the detection of silver ions at the femtomole level

PubMed Central

Rubinova, Nastassia; Chumbimuni-Torres, Karin; Bakker, Eric

2010-01-01

In recent years, ion-selective electrodes based on polymer membranes have been shown to exhibit detection limits that are often in the nanomolar concentration range, and thus drastically lower than traditionally accepted. Since potentiometry is less dependent on scaling laws that other established analytical techniques, their performance in confined sample volumes is explored here. Solid-contact silver-selective microelectrodes, with a sodium-selective microelectrode as a reference, were inserted into a micropipette tip used as a 50-μl sample. The observed potential stabilities, reproducibilities and detection limits were attractive and largely matched that for large 100-ml samples. This should pave the way for further experiments to detecting ultra-small total ion concentrations by potentiometry, especially when used as a transducer after an amplification step in bioanalysis. PMID:20543910

Investigation of dioxin concentrations in the lower Roanoke River basin, North Carolina, February 26-March 7, 2001

USGS Publications Warehouse

Miller, K.F.; Walters, D.A.

2001-01-01

Dioxin is a toxic chemical that, when present in the environment, can cause cancer and birth defects in humans. Dioxin is of particular concern because concentrations of dioxin that were released into the environment many years ago remain a contributing factor to current exposure. Dioxin exposure often occurs in surface-water systems downstream from contaminated sites and is detrimental to aquatic life. For these reasons and because the U.S. Geological Survey has expertise in conducting high-volume dioxin sampling, the U.S. Environmental Protection Agency and the State of North Carolina asked the U.S. Geological Survey to collect water samples in the lower Roanoke River to be analyzed for the presence of dioxin. Water quality of the lower Roanoke River Basin in North Carolina was assessed at eight sites during February 26-March 7, 2001. Water- quality samples were collected for analysis of suspended-sediment and dioxin concentrations; high-volume (750-liter) water samples were collected for dioxin analysis. Discharge measurements were made at or near the high-volume sampling sites. Suspended-sediment sampling and water-quality measurements of specific conductance, pH, water temperature, and dissolved-oxygen concentrations made at each sampling site included multidepth measurements at two cross-section transects and hourly measurements at the point of high-volume sampling. Multidepth measurements were made near the surface, mid-depth, and near the bottom of the water column. These values were averaged for each cross section. During the sampling period, all sites sampled had dioxin concentrations above detection limits (1 part per quintillion) for both suspended and dissolved dioxin. Suspended dioxin ranged from 5.1 to 900 femtograms per liter, and dissolved dioxin values ranged from 0.31 to 41 femtograms per liter. Suspended-sediment concentrations ranged from 1.1 to 14 milligrams per liter. Specific conductance values ranges from 111 to 340 microsiemens per centimeter at 25 degrees Celsius. The range of pH values at the sampling sites was from 6.6 to 7.7. Water temperatures ranged from 8.9 to 13 degrees Celsius. Dissolved-oxygen concentrations ranged from 7.3 to 10.9 milligrams per liter.

Assessment of left ventricular function and mass by MR imaging: a stereological study based on the systematic slice sampling procedure.

PubMed

Mazonakis, Michalis; Sahin, Bunyamin; Pagonidis, Konstantin; Damilakis, John

2011-06-01

The aim of this study was to combine the stereological technique with magnetic resonance (MR) imaging data for the volumetric and functional analysis of the left ventricle (LV). Cardiac MR examinations were performed in 13 consecutive subjects with known or suspected coronary artery disease. The end-diastolic volume (EDV), end-systolic volume, ejection fraction (EF), and mass were estimated by stereology using the entire slice set depicting LV and systematic sampling intensities of 1/2 and 1/3 that provided samples with every second and third slice, respectively. The repeatability of stereology was evaluated. Stereological assessments were compared with the reference values derived by manually tracing the endocardial and epicardial contours on MR images. Stereological EDV and EF estimations obtained by the 1/3 systematic sampling scheme were significantly different from those by manual delineation (P < .05). No difference was observed between the reference values and the LV parameters estimated by the entire slice set or a sampling intensity of 1/2 (P > .05). For these stereological approaches, a high correlation (r(2) = 0.80-0.93) and clinically acceptable limits of agreement were found with the reference method. Stereological estimations obtained by both sample sizes presented comparable coefficient of variation values of 2.9-5.8%. The mean time for stereological measurements on the entire slice set was 3.4 ± 0.6 minutes and it was reduced to 2.5 ± 0.5 minutes with the 1/2 systematic sampling scheme. Stereological analysis on systematic samples of MR slices generated by the 1/2 sampling intensity provided efficient and quick assessment of LV volumes, function, and mass. Copyright © 2011 AUR. Published by Elsevier Inc. All rights reserved.

RCRA Facility investigation report for Waste Area Grouping 6 at Oak Ridge National Laboratory, Oak Ridge, Tennessee. Volume 5, Technical Memorandums 06-09A, 06-10A, and 06-12A

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

None

This report provides a detailed summary of the activities carried out to sample groundwater at Waste Area Grouping (WAG) 6. The analytical results for samples collected during Phase 1, Activity 2 of the WAG 6 Resource Conservation and Recovery Act Facility Investigation (RFI) are also presented. In addition, analytical results for Phase 1, activity sampling events for which data were not previously reported are included in this TM. A summary of the groundwater sampling activities of WAG 6, to date, are given in the Introduction. The Methodology section describes the sampling procedures and analytical parameters. Six attachments are included. Attachmentsmore » 1 and 2 provide analytical results for selected RFI groundwater samples and ORNL sampling event. Attachment 3 provides a summary of the contaminants detected in each well sampled for all sampling events conducted at WAG 6. Bechtel National Inc. (BNI)/IT Corporation Contract Laboratory (IT) RFI analytical methods and detection limits are given in Attachment 4. Attachment 5 provides the Oak Ridge National Laboratory (ORNL)/Analytical Chemistry Division (ACD) analytical methods and detection limits and Resource Conservation and Recovery Act (RCRA) quarterly compliance monitoring (1988--1989). Attachment 6 provides ORNL/ACD groundwater analytical methods and detection limits (for the 1990 RCRA semi-annual compliance monitoring).« less

Enhancing Results of Microarray Hybridizations Through Microagitation

PubMed Central

Toegl, Andreas; Kirchner, Roland; Gauer, Christoph; Wixforth, Achim

2003-01-01

Protein and DNA microarrays have become a standard tool in proteomics/genomics research. In order to guarantee fast and reproducible hybridization results, the diffusion limit must be overcome. Surface acoustic wave (SAW) micro-agitation chips efficiently agitate the smallest sample volumes (down to 10 μL and below) without introducing any dead volume. The advantages are reduced reaction time, increased signal-to-noise ratio, improved homogeneity across the microarray, and better slide-to-slide reproducibility. The SAW micromixer chips are the heart of the Advalytix ArrayBooster, which is compatible with all microarrays based on the microscope slide format. PMID:13678150

An Ultra-Sensitive Method for the Analysis of Perfluorinated Alkyl Acids in Drinking Water using a Column Switching High-Performance Liquid Chromatography Tandem Mass Spectrometry

EPA Science Inventory

In epidemiological research, it has become increasingly important to assess subjects' exposure to different classes of chemicals in multiple environmental media. It is a common practice to aliquot limited volumes of samples into smaller quantities for specific trace level chemi...

The Complete Local-Volume Groups Sample (CLoGS): Early results from X-ray and radio observations

NASA Astrophysics Data System (ADS)

Vrtilek, Jan M.; O'Sullivan, Ewan; David, Laurence P.; Giacintucci, Simona; Kolokythas, Konstantinos

2017-08-01

Although the group environment is the dominant locus of galaxy evolution (in contrast to rich clusters, which contain only a few percent of galaxies), there has been a lack of reliable, representative group samples in the local Universe. In particular, X-ray selected samples are strongly biased in favor of the X-ray bright, centrally-concentrated cool-core systems. In response, we have designed the Complete Local-Volume Groups Sample (CLoGS), an optically-selected statistically-complete sample of 53 groups within 80 Mpc which is intended to overcome the limitations of X-ray selected samples and serve as a representative survey of groups in the local Universe. We have supplemented X-ray data from Chandra and XMM (70% complete to date, using both archival and new observations, with a 26-group high richness subsample 100% complete) with GMRT radio continuum observations (at 235 and 610 MHz, complete for the entire sample). CLoGS includes groups with a wide variety of properties in terms of galaxy population, hot gas content, and AGN power. We here describe early results from the survey, including the range of AGN activity observed in the dominant galaxies, the relative fraction of cool-core and non-cool-core groups in our sample, and the degree of disturbance observed in the IGM.

Analytical evaluation of BEA zeolite for the pre-concentration of polycyclic aromatic hydrocarbons and their subsequent chromatographic analysis in water samples.

PubMed

Wilson, Walter B; Costa, Andréia A; Wang, Huiyong; Dias, José A; Dias, Sílvia C L; Campiglia, Andres D

2012-07-06

The analytical performance of BEA - a commercial zeolite - is evaluated for the pre-concentration of fifteen Environmental Protection Agency - polycyclic aromatic hydrocarbons and their subsequent HPLC analysis in tap and lake water samples. The pre-concentration factors obtained with BEA have led to a method with excellent analytical figures of merit. One milliliter aliquots were sufficient to obtain excellent precision of measurements at the parts-per-trillion concentration level with relative standard deviations varying from 4.1% (dibenzo[a,h]anthracene) to 13.4% (pyrene). The limits of detection were excellent as well and varied between 1.1 (anthracene) and 49.9 ng L(-1) (indeno[1,2,3-cd]pyrene). The recovery values of all the studied compounds meet the criterion for regulated polycyclic aromatic hydrocarbons, which mandates relative standard deviations equal or lower than 25%. The small volume of organic solvents (100 μL per sample) and amount of BEA (2 mg per sample) makes sample pre-concentration environmentally friendly and cost effective. The extraction procedure is well suited for numerous samples as the small working volume (1 mL) facilitates the implementation of simultaneous sample extraction. These are attractive features when routine monitoring of numerous samples is contemplated. Copyright © 2012 Elsevier B.V. All rights reserved.

Sensitive determination of polycyclic aromatic hydrocarbons in water samples by HPLC coupled with SPE based on graphene functionalized with triethoxysilane.

PubMed

Huang, Ke-Jing; Li, Jing; Liu, Yan-Ming; Wang, Lan

2013-02-01

The graphene functionalized with (3-aminopropyl) triethoxysilane was synthesized by a simple hydrothermal reaction and applied as SPE sorbents to extract trace polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. These sorbents possess high adsorption capacity and extraction efficiency due to strong adsorption ability of carbon materials and large specific surface area of nanoparticles, and only 10 mg of sorbents are required to extract PAHs from 100 mL water samples. Several condition parameters, such as eluent and its volume, adsorbent amount, sample volume, sample pH, and sample flow rate, were optimized to achieve good sensitivity and precision. Under the optimized extraction conditions, the method showed good linearity in the range of 1-100 μg/L, repeatability of the extraction (the RSDs were between 1.8 and 2.9%, n = 6), and satisfactory detection limits of 0.029-0.1 μg/L. The recoveries of PAHs spiked in environmental water samples ranged from 84.6 to 109.5%. All these results demonstrated that this new SPE technique was a viable alternative to conventional enrichment techniques for the extraction and analysis of PAHs in complex samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conversion of a Capture ELISA to a Luminex xMAP Assay using a Multiplex Antibody Screening Method

PubMed Central

Baker, Harold N.; Murphy, Robin; Lopez, Erica; Garcia, Carlos

2012-01-01

The enzyme-linked immunosorbent assay (ELISA) has long been the primary tool for detection of analytes of interest in biological samples for both life science research and clinical diagnostics. However, ELISA has limitations. It is typically performed in a 96-well microplate, and the wells are coated with capture antibody, requiring a relatively large amount of sample to capture an antigen of interest . The large surface area of the wells and the hydrophobic binding of capture antibody can also lead to non-specific binding and increased background. Additionally, most ELISAs rely upon enzyme-mediated amplification of signal in order to achieve reasonable sensitivity. Such amplification is not always linear and can thus skew results. In the past 15 years, a new technology has emerged that offers the benefits of the ELISA, but also enables higher throughput, increased flexibility, reduced sample volume, and lower cost, with a similar workflow 1, 2. Luminex xMAP Technology is a microsphere (bead) array platform enabling both monoplex and multiplex assays that can be applied to both protein and nucleic acid applications 3-5. The beads have the capture antibody covalently immobilized on a smaller surface area, requiring less capture antibody and smaller sample volumes, compared to ELISA, and non-specific binding is significantly reduced. Smaller sample volumes are important when working with limiting samples such as cerebrospinal fluid, synovial fluid, etc. 6. Multiplexing the assay further reduces sample volume requirements, enabling multiple results from a single sample. Recent improvements by Luminex include: the new MAGPIX system, a smaller, less expensive, easier-to-use analyzer; Low-Concentration Magnetic MagPlex Microspheres which eliminate the need for expensive filter plates and come in a working concentration better suited for assay development and low-throughput applications; and the xMAP Antibody Coupling (AbC) Kit, which includes a protocol, reagents, and consumables necessary for coupling beads to the capture antibody of interest. (See Materials section for a detailed list of kit contents.) In this experiment, we convert a pre-optimized ELISA assay for TNF-alpha cytokine to the xMAP platform and compare the performance of the two methods 7-11. TNF-alpha is a biomarker used in the measurement of inflammatory responses in patients with autoimmune disorders. We begin by coupling four candidate capture antibodies to four different microsphere sets or regions. When mixed together, these four sets allow for the simultaneous testing of all four candidates with four separate detection antibodies to determine the best antibody pair, saving reagents, sample and time. Two xMAP assays are then constructed with the two most optimal antibody pairs and their performance is compared to that of the original ELISA assay in regards to signal strength, dynamic range, and sensitivity. PMID:22806215

Highly efficient and ultra-small volume separation by pressure-driven liquid chromatography in extended nanochannels.

PubMed

Ishibashi, Ryo; Mawatari, Kazuma; Kitamori, Takehiko

2012-04-23

The rapidly developing interest in nanofluidic analysis, which is used to examine liquids ranging in amounts from the attoliter to the femtoliter scale, correlates with the recent interest in decreased sample amounts, such as in the field of single-cell analysis. For general nanofluidic analysis, the fact that a pressure-driven flow does not limit the choice of solvents (aqueous or organic) is important. This study shows the first pressure-driven liquid chromatography technique that enables separation of atto- to femtoliter sample volumes, with a high separation efficiency within a few seconds. The apparent diffusion coefficient measurement of the unretentive sample suggests that there is no increase in the viscosity of toluene in the extended nanospace, unlike in aqueous solvents. Evaluation of the normal phase separation, therefore, should involve only the examination of the effect of the small size of the extended nanospace. Compared to a conventionally packed high-performance liquid chromatography column, the separation here results in a faster separation (4 s) by 2 orders of magnitude, a smaller injection volume (10(0) fL) by 9 orders, and a higher separation efficiency (440,000 plates/m) by 1 order. Moreover, the separation behavior agrees with the theory showing that this high efficiency was due to the small and controlled size of the separation channel, where the diffusion through the channel depth direction is fast enough to be neglected. Our chip-based platform should allow direct and real-time analysis or screening of ultralow volume of sample. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of spectroscopy technologies for improved monitoring of cell culture processes in miniature bioreactors

PubMed Central

van den Berg, Frans; Racher, Andrew J.; Martin, Elaine B.; Jaques, Colin

2017-01-01

Cell culture process development requires the screening of large numbers of cell lines and process conditions. The development of miniature bioreactor systems has increased the throughput of such studies; however, there are limitations with their use. One important constraint is the limited number of offline samples that can be taken compared to those taken for monitoring cultures in large‐scale bioreactors. The small volume of miniature bioreactor cultures (15 mL) is incompatible with the large sample volume (600 µL) required for bioanalysers routinely used. Spectroscopy technologies may be used to resolve this limitation. The purpose of this study was to compare the use of NIR, Raman, and 2D‐fluorescence to measure multiple analytes simultaneously in volumes suitable for daily monitoring of a miniature bioreactor system. A novel design‐of‐experiment approach is described that utilizes previously analyzed cell culture supernatant to assess metabolite concentrations under various conditions while providing optimal coverage of the desired design space. Multivariate data analysis techniques were used to develop predictive models. Model performance was compared to determine which technology is more suitable for this application. 2D‐fluorescence could more accurately measure ammonium concentration (RMSECV 0.031 g L−1) than Raman and NIR. Raman spectroscopy, however, was more robust at measuring lactate and glucose concentrations (RMSECV 1.11 and 0.92 g L−1, respectively) than the other two techniques. The findings suggest that Raman spectroscopy is more suited for this application than NIR and 2D‐fluorescence. The implementation of Raman spectroscopy increases at‐line measuring capabilities, enabling daily monitoring of key cell culture components within miniature bioreactor cultures. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:337–346, 2017 PMID:28271638

Comparison of use of an infrared anesthetic gas monitor and refractometry for measurement of anesthetic agent concentrations.

PubMed

Ambrisko, Tamas D; Klide, Alan M

2011-10-01

To assess agreement between anesthetic agent concentrations measured by use of an infrared anesthetic gas monitor (IAGM) and refractometry. SAMPLE-4 IAGMs of the same type and 1 refractometer. Mixtures of oxygen and isoflurane, sevoflurane, desflurane, or N(2)O were used. Agent volume percent was measured simultaneously with 4 IAGMs and a refractometer at the common gas outlet. Measurements obtained with each of the 4 IAGMs were compared with the corresponding refractometer measurements via the Bland-Altman method. Similarly, Bland-Altman plots were also created with either IAGM or refractometer measurements and desflurane vaporizer dial settings. Bias ± 2 SD for comparisons of IAGM and refractometer measurements was as follows: isoflurane, -0.03 ± 0.18 volume percent; sevoflurane, -0.19 ± 0.23 volume percent; desflurane, 0.43 ± 1.22 volume percent; and N(2)O, -0.21 ± 1.88 volume percent. Bland-Altman plots comparing IAGM and refractometer measurements revealed nonlinear relationships for sevoflurane, desflurane, and N(2)O. Desflurane measurements were notably affected; bias ± limits of agreement (2 SD) were small (0.1 ± 0.22 volume percent) at < 12 volume percent, but both bias and limits of agreement increased at higher concentrations. Because IAGM measurements did not but refractometer measurements did agree with the desflurane vaporizer dial settings, infrared measurement technology was a suspected cause of the nonlinear relationships. Given that the assumption of linearity is a cornerstone of anesthetic monitor calibration, this assumption should be confirmed before anesthetic monitors are used in experiments.

Injection-induced moment release can also be aseismic

USGS Publications Warehouse

McGarr, Arthur; Barbour, Andrew J.

2018-01-01

The cumulative seismic moment is a robust measure of the earthquake response to fluid injection for injection volumes ranging from 3100 to about 12 million m3. Over this range, the moment release is limited to twice the product of the shear modulus and the volume of injected fluid. This relation also applies at the much smaller injection volumes of the field experiment in France reported by Guglielmi, et al. (2015) and laboratory experiments to simulate hydraulic fracturing described by Goodfellow, et al. (2015). In both of these studies, the relevant moment release for comparison with the fluid injection was aseismic and consistent with the scaling that applies to the much larger volumes associated with injection-induced earthquakes with magnitudes extending up to 5.8. Neither the micro-earthquakes, at the site in France, nor the acoustic emission in the laboratory samples contributed significantly to the deformation due to fluid injection.

LOSS Revisited. II. The Relative Rates of Different Types of Supernovae Vary between Low- and High-mass Galaxies

NASA Astrophysics Data System (ADS)

Graur, Or; Bianco, Federica B.; Modjaz, Maryam; Shivvers, Isaac; Filippenko, Alexei V.; Li, Weidong; Smith, Nathan

2017-03-01

In Paper I of this series, we showed that the ratio between stripped-envelope (SE) supernova (SN) and Type II SN rates reveals a significant SE SN deficiency in galaxies with stellar masses ≲ {10}10 {M}⊙ . Here, we test this result by splitting the volume-limited subsample of the Lick Observatory Supernova Search (LOSS) SN sample into low- and high-mass galaxies and comparing the relative rates of various SN types found in them. The LOSS volume-limited sample contains 180 SNe and SN impostors and is complete for SNe Ia out to 80 Mpc and core-collapse SNe out to 60 Mpc. All of these transients were recently reclassified by us in Shivvers et al. We find that the relative rates of some types of SNe differ between low- and high-mass galaxies: SNe Ib and Ic are underrepresented by a factor of ˜3 in low-mass galaxies. These galaxies also contain the only examples of SN 1987A-like SNe in the sample and host about nine times as many SN impostors. Normal SNe Ia seem to be ˜30% more common in low-mass galaxies, making these galaxies better sources for homogeneous SN Ia cosmology samples. The relative rates of SNe IIb are consistent in both low- and high-mass galaxies. The same is true for broad-line SNe Ic, although our sample includes only two such objects. The results presented here are in tension with a similar analysis from the Palomar Transient Factory, especially as regards SNe IIb.

Determination of trace triclosan in environmental water by microporous bamboo-activated charcoal solid-phase extraction combined with HPLC-ESI-MS.

PubMed

Sun, Jing; Yi, Chun-Liang; Zhao, Ru-Song; Wang, Xia; Jiang, Wen-Qiang; Wang, Xi-Kui

2012-10-01

A sensitive and efficient analytical method for triclosan (TCS) determination in water, which involves enrichment with bamboo-activated charcoal and detection with HPLC-ESI-MS, was developed. The influence of several operational parameters, including the eluant and its volume, the flow rate, the volume andacidity of the sample, and the amount of bamboo-activated charcoal, were investigated and optimized. Under the optimum conditions, linearity of the method was observed in the range of 0.02-20 μg/L, with correlation coefficients (r(2) ) >0.9990. The limit of detection was 0.002 μg/L based on the ratio of chromatographic signal to baseline noise (S/N = 3). The spiked recoveries of TCS in real water samples were achieved in the range of 97.6-112.5%. The proposed method was applied to analyze TCS in real aqueous samples. All the surface water samples collected in Xiaoqing River had detectable levels of TCS with concentrations of 42-197 ng/L. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preconcentration and solid phase extraction method for the determination of Co, Cu, Ni, Zn and Cd in environmental and biological samples using activated carbon by FAAS.

PubMed

Kiran, K; Suresh Kumar, K; Suvardhan, K; Janardhanam, K; Chiranjeevi, P

2007-08-17

2-{[1-(2-Hydroxynaphthyl) methylidene] amino} benzoic acid (HNMABA) was synthesized for solid phase extraction (SPE) to the determination of Co, Cu, Ni, Zn and Cd in environmental and biological samples by flame atomic absorption spectrophotometry (FAAS). These metals were sorbed as HNMABA complexes on activated carbon (AC) at the pH range of 5.0+/-0.2 and eluted with 6 ml of 1M HNO3 in acetone. The effects of sample volume, eluent volume and recovery have been investigated to enhance the sensitivity and selectivity of proposed method. The effect of interferences on the sorption of metal ions was studied. The concentration of the metal ions detected after preconcentration was in agreement with the added amount. The detection limits for the metals studied were in the range of 0.75-3.82 microg ml(-1). The proposed system produced satisfactory results for the determination of Co, Cu, Ni, Zn and Cd metals in environmental and biological samples.

Integrating quantitative PCR and Bayesian statistics in quantifying human adenoviruses in small volumes of source water.

PubMed

Wu, Jianyong; Gronewold, Andrew D; Rodriguez, Roberto A; Stewart, Jill R; Sobsey, Mark D

2014-02-01

Rapid quantification of viral pathogens in drinking and recreational water can help reduce waterborne disease risks. For this purpose, samples in small volume (e.g. 1L) are favored because of the convenience of collection, transportation and processing. However, the results of viral analysis are often subject to uncertainty. To overcome this limitation, we propose an approach that integrates Bayesian statistics, efficient concentration methods, and quantitative PCR (qPCR) to quantify viral pathogens in water. Using this approach, we quantified human adenoviruses (HAdVs) in eighteen samples of source water collected from six drinking water treatment plants. HAdVs were found in seven samples. In the other eleven samples, HAdVs were not detected by qPCR, but might have existed based on Bayesian inference. Our integrated approach that quantifies uncertainty provides a better understanding than conventional assessments of potential risks to public health, particularly in cases when pathogens may present a threat but cannot be detected by traditional methods. © 2013 Elsevier B.V. All rights reserved.

Rapid analysis of ultraviolet filters using dispersive liquid-liquid microextraction coupled to headspace gas chromatography and mass spectrometry.

PubMed

Pierson, Stephen A; Trujillo-Rodríguez, María J; Anderson, Jared L

2018-05-29

An ionic-liquid-based in situ dispersive liquid-liquid microextraction method coupled to headspace gas chromatography and mass spectrometry was developed for the rapid analysis of ultraviolet filters. The chemical structures of five ionic liquids were specifically designed to incorporate various functional groups for the favorable extraction of the target analytes. Extraction parameters including ionic liquid mass, molar ratio of ionic liquid to metathesis reagent, vortex time, ionic strength, pH, and total sample volume were studied and optimized. The effect of the headspace temperature and volume during the headspace sampling step was also evaluated to increase the sensitivity of the method. The optimized procedure is fast as it only required ∼7-10 min per extraction and allowed for multiple extractions to be performed simultaneously. In addition, the method exhibited high precision, good linearity, and low limits of detection for six ultraviolet filters in aqueous samples. The developed method was applied to both pool and lake water samples attaining acceptable relative recovery values. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of ochratoxin A in fruit juice by high-performance liquid chromatography after vortex-assisted emulsification microextraction based on solidification of floating organic drop.

PubMed

Asadi, Mohammad

2018-03-01

A rapid, simple, and green vortex-assisted emulsification microextraction method based on solidification of floating organic drop was developed for the extraction and determination of ochratoxin A (OTA) with high-performance liquid chromatography. Some factors influencing the extraction efficiency of OTA such as the type and volume of extraction solvent, sample pH, salt concentration, vortex time, and sample volume were optimized. Under optimized conditions, the calibration curve exhibited linearity in the range of 50.0-500 ng L -1 with a coefficient of determination higher than 0.999. The limit of detection was 15.0 ng L -1 . The inter- and intra-assays relative standard deviations were in a range of 4.7-8.7%. The accuracy of the developed method was investigated through recovery experiments, and it was successfully used for the quantification of OTA in 40 samples of fruit juice.

Preparation and characterization of magnetic carboxylated nanodiamonds for vortex-assisted magnetic solid-phase extraction of ziram in food and water samples.

PubMed

Yılmaz, Erkan; Soylak, Mustafa

2016-09-01

A simple and rapid vortex-assisted magnetic solid phase extraction (VA-MSPE) method for the separation and preconcentration of ziram (zinc dimethyldithiocarbamate), subsequent detection of the zinc in complex structure of ziram by flame atomic absorption spectrometry (AAS) has been developed. The ziram content was calculated by using stoichiometric relationship between the zinc and ziram. Magnetic carboxylated nanodiamonds (MCNDs) as solid-phase extraction adsorbent was prepared and characterized by Fourier transform infrared (FT-IR) spectra, X-ray diffraction (XRD) spectrometry and scanning electron microscopy (SEM). These magnetic carboxylated nanodiamonds carrying the ziram could be easily separated from the aqueous solution by applying an external magnetic field; no filtration or centrifugation was necessary. Some important factors influencing the extraction efficiency of ziram such as pH of sample solution, amount of adsorbent, type and volume of eluent, extraction and desorption time and sample volume were studied and optimized. The total extraction and detection time was lower than 10min The preconcentration factor (PF), the precision (RSD, n=7), the limit of detection (LOD) and limit of quantification (LOQ) were 160, 7.0%, 5.3µgL(-1) and 17.5µgL(-1), respectively. The interference of various ions has been examined and the method has been applied for the determination of ziram in various waters, foodstuffs samples and synthetic mixtures. Copyright © 2016 Elsevier B.V. All rights reserved.

Analysis of plant hormones by microemulsion electrokinetic capillary chromatography coupled with on-line large volume sample stacking.

PubMed

Chen, Zongbao; Lin, Zian; Zhang, Lin; Cai, Yan; Zhang, Lan

2012-04-07

A novel method of microemulsion electrokinetic capillary chromatography (MEEKC) coupled with on-line large volume sample stacking was developed for the analysis of six plant hormones including indole-3-acetic acid, indole-3-butyric acid, indole-3-propionic acid, 1-naphthaleneacetic acid, abscisic acid and salicylic acid. Baseline separation of six plant hormones was achieved within 10 min by using the microemulsion background electrolyte containing a 97.2% (w/w) 10 mM borate buffer at pH 9.2, 1.0% (w/w) ethyl acetate as oil droplets, 0.6% (w/w) sodium dodecyl sulphate as surfactant and 1.2% (w/w) 1-butanol as cosurfactant. In addition, an on-line concentration method based on a large volume sample stacking technique and multiple wavelength detection was adopted for improving the detection sensitivity in order to determine trace level hormones in a real sample. The optimal method provided about 50-100 fold increase in detection sensitivity compared with a single MEEKC method, and the detection limits (S/N = 3) were between 0.005 and 0.02 μg mL(-1). The proposed method was simple, rapid and sensitive and could be applied to the determination of six plant hormones in spiked water samples, tobacco leaves and 1-naphthylacetic acid in leaf fertilizer. The recoveries ranged from 76.0% to 119.1%, and good reproducibilities were obtained with relative standard deviations (RSDs) less than 6.6%.

Rapid analysis of aflatoxins B1, B2, and ochratoxin A in rice samples using dispersive liquid-liquid microextraction combined with HPLC.

PubMed

Lai, Xian-Wen; Sun, Dai-Li; Ruan, Chun-Qiang; Zhang, He; Liu, Cheng-Lan

2014-01-01

A novel, simple, and rapid method is presented for the analysis of aflatoxin B1, aflatoxin B2, and ochratoxin A in rice samples by dispersive liquid-liquid microextraction combined with LC and fluorescence detection. After extraction of the rice samples with a mixture of acetonitrile/water/acetic acid, mycotoxins were rapidly partitioned into a small volume of organic solvent (chloroform) by dispersive liquid-liquid microextraction. The three mycotoxins were simultaneously determined by LC with fluorescence detection after precolumn derivatization for aflatoxin B1 and B2. Parameters affecting both extraction and dispersive liquid-liquid microextraction procedures, including the extraction solvent, the type and volume of extractant, the volume of dispersive solvent, the addition of salt, the pH and the extraction time, were optimized. The optimized protocol provided an enrichment factor of approximately 1.25 and with detection of limits (0.06-0.5 μg/kg) below the maximum levels imposed by current regulations for aflatoxins and ochratoxin A. The mean recovery of three mycotoxins ranged from 82.9-112%, with a RSD less than 7.9% in all cases. The method was successfully applied to measure mycotoxins in commercial rice samples collected from local supermarkets in China. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microfluidic-Based sample chips for radioactive solutions

DOE PAGES

Tripp, J. L.; Law, J. D.; Smith, T. E.; ...

2015-01-01

Historical nuclear fuel cycle process sampling techniques required sample volumes ranging in the tens of milliliters. The radiation levels experienced by analytical personnel and equipment, in addition to the waste volumes generated from analysis of these samples, have been significant. These sample volumes also impacted accountability inventories of required analytes during process operations. To mitigate radiation dose and other issues associated with the historically larger sample volumes, a microcapillary sample chip was chosen for further investigation. The ability to obtain microliter volume samples coupled with a remote automated means of sample loading, tracking, and transporting to the analytical instrument wouldmore » greatly improve analytical efficiency while reducing both personnel exposure and radioactive waste volumes. Sample chip testing was completed to determine the accuracy, repeatability, and issues associated with the use of microfluidic sample chips used to supply µL sample volumes of lanthanide analytes dissolved in nitric acid for introduction to an analytical instrument for elemental analysis.« less

Structural Magnetic Resonance Imaging Correlates of Aggression in Psychosis: A Systematic Review and Effect Size Analysis.

PubMed

Widmayer, Sonja; Sowislo, Julia F; Jungfer, Hermann A; Borgwardt, Stefan; Lang, Undine E; Stieglitz, Rolf D; Huber, Christian G

2018-01-01

Background: Aggression in psychoses is of high clinical importance, and volumetric MRI techniques have been used to explore its structural brain correlates. Methods: We conducted a systematic review searching EMBASE, ScienceDirect, and PsycINFO through September 2017 using thesauri representing aggression, psychosis, and brain imaging. We calculated effect sizes for each study and mean Hedge's g for whole brain (WB) volume. Methodological quality was established using the PRISMA checklist (PROSPERO: CRD42014014461). Results: Our sample consisted of 12 studies with 470 patients and 155 healthy controls (HC). After subtracting subjects due to cohort overlaps, 314 patients and 96 HC remained. Qualitative analyses showed lower volumes of WB, prefrontal regions, temporal lobe, hippocampus, thalamus and cerebellum, and higher volumes of lateral ventricles, amygdala, and putamen in violent vs. non-violent people with schizophrenia. In quantitative analyses, violent persons with schizophrenia exhibited a significantly lower WB volume than HC ( p = 0.004), and also lower than non-violent persons with schizophrenia ( p = 0.007). Conclusions: We reviewed evidence for differences in brain volume correlates of aggression in persons with schizophrenia. Our results point toward a reduced whole brain volume in violent as opposed to non-violent persons with schizophrenia. However, considerable sample overlap in the literature, lack of reporting of potential confounding variables, and missing research on affective psychoses limit our explanatory power. To permit stronger conclusions, further studies evaluating structural correlates of aggression in psychotic disorders are needed.

Quantifying Golgi structure using EM: combining volume-SEM and stereology for higher throughput.

PubMed

Ferguson, Sophie; Steyer, Anna M; Mayhew, Terry M; Schwab, Yannick; Lucocq, John Milton

2017-06-01

Investigating organelles such as the Golgi complex depends increasingly on high-throughput quantitative morphological analyses from multiple experimental or genetic conditions. Light microscopy (LM) has been an effective tool for screening but fails to reveal fine details of Golgi structures such as vesicles, tubules and cisternae. Electron microscopy (EM) has sufficient resolution but traditional transmission EM (TEM) methods are slow and inefficient. Newer volume scanning EM (volume-SEM) methods now have the potential to speed up 3D analysis by automated sectioning and imaging. However, they produce large arrays of sections and/or images, which require labour-intensive 3D reconstruction for quantitation on limited cell numbers. Here, we show that the information storage, digital waste and workload involved in using volume-SEM can be reduced substantially using sampling-based stereology. Using the Golgi as an example, we describe how Golgi populations can be sensed quantitatively using single random slices and how accurate quantitative structural data on Golgi organelles of individual cells can be obtained using only 5-10 sections/images taken from a volume-SEM series (thereby sensing population parameters and cell-cell variability). The approach will be useful in techniques such as correlative LM and EM (CLEM) where small samples of cells are treated and where there may be variable responses. For Golgi study, we outline a series of stereological estimators that are suited to these analyses and suggest workflows, which have the potential to enhance the speed and relevance of data acquisition in volume-SEM.

Solid phase microextraction Arrow for the sampling of volatile amines in wastewater and atmosphere.

PubMed

Helin, Aku; Rönkkö, Tuukka; Parshintsev, Jevgeni; Hartonen, Kari; Schilling, Beat; Läubli, Thomas; Riekkola, Marja-Liisa

2015-12-24

A new method is introduced for the sampling of volatile low molecular weight alkylamines in ambient air and wastewater by utilizing a novel SPME Arrow system, which contains a larger volume of sorbent compared to a standard SPME fiber. Parameters affecting the extraction, such as coating material, need for preconcentration, sample volume, pH, stirring rate, salt addition, extraction time and temperature were carefully optimized. In addition, analysis conditions, including desorption temperature and time as well as gas chromatographic parameters, were optimized. Compared to conventional SPME fiber, the SPME Arrow had better robustness and sensitivity. Average intermediate reproducibility of the method expressed as relative standard deviation was 12% for dimethylamine and 14% for trimethylamine, and their limit of quantification 10μg/L and 0.13μg/L respectively. Working range was from limits of quantification to 500μg/L for dimethylamine and to 130μg/L for trimethylamine. Several alkylamines were qualitatively analyzed in real samples, while target compounds dimethyl- and trimethylamines were quantified. The concentrations in influent and effluent wastewater samples were almost the same (∼80μg/L for dimethylamine, 120μg/L for trimethylamine) meaning that amines pass the water purification process unchanged or they are produced at the same rate as they are removed. For the air samples, preconcentration with phosphoric acid coated denuder was required and the concentration of trimethylamine was found to be around 1ng/m(3). The developed method was compared with optimized method based on conventional SPME and advantages and disadvantages of both approaches are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

Ultrasound-assisted dispersive magnetic solid phase extraction based on amino-functionalized Fe3O4 adsorbent for recovery of clomipramine from human plasma and its determination by high performance liquid chromatography: Optimization by experimental design.

PubMed

Hamidi, Fatemeh; Hadjmohammadi, Mohammad Reza; Aghaie, Ali B G

2017-09-15

The applicability of Amino-functionalized Fe 3 O 4 nanoparticles (NPs) as an effective adsorbent was developed for the extraction and determination of clomipramine (CLP) in plasma sample by ultrasound-assisted dispersive magnetic solid phase extraction (UADM-SPE) and high-performance liquid chromatography-ultraviolet (HPLC-UV) detection. Fabrication of the Fe 3 O 4 @SiO 2 -NH 2 magnetic nanoparticles confirmed by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of different extraction parameters (i.e. pH of the sample solution, the amount of magnetic nanoparticles (MNPs), sample volume, temperature and sonication time) on the extraction recovery of CLP were investigated by response surface methodology through central composite design (CCD). The optimum condition is obtained when the affecting parameters are set to: pH of the sample solution=9, the amount of MNPs=37mg, sample volume=23mL, 25°C temperature and sonication time=1min. Under the optimum condition, extraction recovery was 90.6% with relative standard deviation of 3.5%, and enrichment factor of 117. The linear range for determination of CLP was 0.017-0.70mgL -1 with a determination coefficient (R 2 ) of 0.999. Limit of detection (LOD) and limit of quantification (LOQ) were 0.005 and 0.0167mgL -1 , respectively. The established UADM-SPE-HPLC-UV method was rapid, simple and efficient for determination of CLP in human plasma samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Digital LAMP in a sample self-digitization (SD) chip

PubMed Central

Herrick, Alison M.; Dimov, Ivan K.; Lee, Luke P.; Chiu, Daniel T.

2012-01-01

This paper describes the realization of digital loop-mediated DNA amplification (dLAMP) in a sample self-digitization (SD) chip. Digital DNA amplification has become an attractive technique to quantify absolute concentrations of DNA in a sample. While digital polymerase chain reaction is still the most widespread implementation, its use in resource—limited settings is impeded by the need for thermal cycling and robust temperature control. In such situations, isothermal protocols that can amplify DNA or RNA without thermal cycling are of great interest. Here, we showed the successful amplification of single DNA molecules in a stationary droplet array using isothermal digital loop-mediated DNA amplification. Unlike most (if not all) existing methods for sample discretization, our design allows for automated, loss-less digitization of sample volumes on-chip. We demonstrated accurate quantification of relative and absolute DNA concentrations with sample volumes of less than 2 μl. We assessed the homogeneity of droplet size during sample self-digitization in our device, and verified that the size variation was small enough such that straightforward counting of LAMP-active droplets sufficed for data analysis. We anticipate that the simplicity and robustness of our SD chip make it attractive as an inexpensive and easy-to-operate device for DNA amplification, for example in point-of-care settings. PMID:22399016

Solid-phase extraction and separation procedure for trace aluminum in water samples and its determination by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS).

PubMed

Ciftci, Harun; Er, Cigdem

2013-03-01

In the present study, a separation/preconcentration procedure for determination of aluminum in water samples has been developed by using a new atomic absorption spectrometer concept with a high-intensity xenon short-arc lamp as continuum radiation source, a high-resolution double-echelle monochromator, and a charge-coupled device array detector. Sample solution pH, sample volume, flow rate of sample solution, volume, and concentration of eluent for solid-phase extraction of Al chelates with 4-[(dicyanomethyl)diazenyl] benzoic acid on polymeric resin (Duolite XAD-761) have been investigated. The adsorbed aluminum on resin was eluted with 5 mL of 2 mol L(-1) HNO(3) and its concentration was determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Under the optimal conditions, limit of detection obtained with HR-CS FAAS and Line Source FAAS (LS-FAAS) were 0.49 μg L(-1) and 3.91 μg L(-1), respectively. The accuracy of the procedure was confirmed by analyzing certified materials (NIST SRM 1643e, Trace elements in water) and spiked real samples. The developed procedure was successfully applied to water samples.

Characterization of Factors Affecting Nanoparticle Tracking Analysis Results With Synthetic and Protein Nanoparticles.

PubMed

Krueger, Aaron B; Carnell, Pauline; Carpenter, John F

2016-04-01

In many manufacturing and research areas, the ability to accurately monitor and characterize nanoparticles is becoming increasingly important. Nanoparticle tracking analysis is rapidly becoming a standard method for this characterization, yet several key factors in data acquisition and analysis may affect results. Nanoparticle tracking analysis is prone to user input and bias on account of a high number of parameters available, contains a limited analysis volume, and individual sample characteristics such as polydispersity or complex protein solutions may affect analysis results. This study systematically addressed these key issues. The integrated syringe pump was used to increase the sample volume analyzed. It was observed that measurements recorded under flow caused a reduction in total particle counts for both polystyrene and protein particles compared to those collected under static conditions. In addition, data for polydisperse samples tended to lose peak resolution at higher flow rates, masking distinct particle populations. Furthermore, in a bimodal particle population, a bias was seen toward the larger species within the sample. The impacts of filtration on an agitated intravenous immunoglobulin sample and operating parameters including "MINexps" and "blur" were investigated to optimize the method. Taken together, this study provides recommendations on instrument settings and sample preparations to properly characterize complex samples. Copyright © 2016. Published by Elsevier Inc.

Polyaniline-coated cigarette filters as a solid-phase extraction sorbent for the extraction and enrichment of polycyclic aromatic hydrocarbon in water samples.

PubMed

Bunkoed, Opas; Rueankaew, Thanaschaphorn; Nurerk, Piyaluk; Kanatharana, Proespichaya

2016-06-01

Polyaniline coated cigarette filters were successfully synthesized and used as a solid-phase extraction sorbent for the extraction and preconcentration of polycyclic aromatic hydrocarbons in water samples. The polyaniline helped to enhance the adsorption ability of polycyclic aromatic hydrocarbons on the sorbent through π-π interactions. The high porosity and large surface area of the cigarette filters helped to reduce backpressure and can be operated with high sample flow rate without loss of extraction efficiency. The developed sorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The parameters that affected the extraction efficiencies, i.e. polymerization time, type of desorption solvent and its volume, sample flow rate, sample volume, sample pH, ionic strength, and organic modifier were investigated. Under the optimal conditions, the method was linear over the range of 0.5-10 μg/L and a detection limit of 0.5 ng/L. This simple, rapid, and cost-effective method was successfully applied to the preconcentration of polycyclic aromatic hydrocarbons from water samples. The developed method provided a high enrichment factor with good extraction efficiency (85-98%) and a relative standard deviation <10%. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fast, sensitive and reliable multi-residue method for routine determination of 34 pesticides from various chemical groups in water samples by using dispersive liquid-liquid microextraction coupled with gas chromatography-mass spectrometry.

PubMed

Tankiewicz, Maciej; Biziuk, Marek

2018-02-01

A simple and efficient dispersive liquid-liquid microextraction technique (DLLME) was developed by using a mixture of two solvents: 40 μL of tetrachlorethylene (extraction solvent) and 1.0 mL of methanol (disperser solvent), which was rapidly injected with a syringe into 10 mL of water sample. Some important parameters affecting the extraction efficiency, such as type and volume of solvents, water sample volume, extraction time, temperature, pH adjustment and salt addition effect were investigated. Simultaneous determination of 34 commonly used pesticides was performed by using gas chromatography coupled with mass spectrometry (GC-MS). The procedure has been validated in order to obtain the highest efficiency at the lowest concentration levels of analytes to fulfill the requirements of regulations on maximum residue limits. Under the optimum conditions, the linearity range was within 0.0096-100 μg L -1 . The limits of detection (LODs) of the developed DLLME-GC-MS methodology for all investigated pesticides were in the range of 0.0032 (endrin)-0.0174 (diazinon) μg L -1 and limits of quantification (LOQs) from 0.0096 to 0.052 μg L -1 . At lower concentration of 1 μg L -1 for each pesticide, recoveries ranged between 84% (tebufenpyrad) and 108% (deltamethrin) with relative standard deviations (RSDs) (n = 7) from 1.1% (metconazole) to 11% (parathion-mehtyl). This methodology was successfully applied to check contamination of environmental samples. The procedure has proved to be selective, sensitive and precise for the simultaneous determination of various pesticides. The optimized analytical method is very simple and rapid (less than 5 min). Graphical abstract Analytical procedure for testing water samples consists of dispersive liquid-liquid microextraction (DLLME) and gas chromatography coupled with mass spectrometry (GC-MS).

Subcortical brain structure and suicidal behaviour in major depressive disorder: a meta-analysis from the ENIGMA-MDD working group.

PubMed

Rentería, M E; Schmaal, L; Hibar, D P; Couvy-Duchesne, B; Strike, L T; Mills, N T; de Zubicaray, G I; McMahon, K L; Medland, S E; Gillespie, N A; Hatton, S N; Lagopoulos, J; Veltman, D J; van der Wee, N; van Erp, T G M; Wittfeld, K; Grabe, H J; Block, A; Hegenscheid, K; Völzke, H; Veer, I M; Walter, H; Schnell, K; Schramm, E; Normann, C; Schoepf, D; Konrad, C; Zurowski, B; Godlewska, B R; Cowen, P J; Penninx, B W J H; Jahanshad, N; Thompson, P M; Wright, M J; Martin, N G; Christensen, H; Hickie, I B

2017-05-02

The aetiology of suicidal behaviour is complex, and knowledge about its neurobiological mechanisms is limited. Neuroimaging methods provide a noninvasive approach to explore the neural correlates of suicide vulnerability in vivo. The ENIGMA-MDD Working Group is an international collaboration evaluating neuroimaging and clinical data from thousands of individuals collected by research groups from around the world. Here we present analyses in a subset sample (n=3097) for whom suicidality data were available. Prevalence of suicidal symptoms among major depressive disorder (MDD) cases ranged between 29 and 69% across cohorts. We compared mean subcortical grey matter volumes, lateral ventricle volumes and total intracranial volume (ICV) in MDD patients with suicidal symptoms (N=451) vs healthy controls (N=1996) or MDD patients with no suicidal symptoms (N=650). MDD patients reporting suicidal plans or attempts showed a smaller ICV (P=4.12 × 10 -3 ) or a 2.87% smaller volume compared with controls (Cohen's d=-0.284). In addition, we observed a nonsignificant trend in which MDD cases with suicidal symptoms had smaller subcortical volumes and larger ventricular volumes compared with controls. Finally, no significant differences (P=0.28-0.97) were found between MDD patients with and those without suicidal symptoms for any of the brain volume measures. This is by far the largest neuroimaging meta-analysis of suicidal behaviour in MDD to date. Our results did not replicate previous reports of association between subcortical brain structure and suicidality and highlight the need for collecting better-powered imaging samples and using improved suicidality assessment instruments.

Enhancing concentration and mass sensitivities for liquid chromatography trace analysis of clopyralid in drinking water.

PubMed

Gu, Binghe; Meldrum, Brian; McCabe, Terry; Phillips, Scott

2012-01-01

A theoretical treatment was developed and validated that relates analyte concentration and mass sensitivities to injection volume, retention factor, particle diameter, column length, column inner diameter and detection wavelength in liquid chromatography, and sample volume and extracted volume in solid-phase extraction (SPE). The principles were applied to improve sensitivity for trace analysis of clopyralid in drinking water. It was demonstrated that a concentration limit of detection of 0.02 ppb (μg/L) for clopyralid could be achieved with the use of simple UV detection and 100 mL of a spiked drinking water sample. This enabled reliable quantitation of clopyralid at the targeted 0.1 ppb level. Using a buffered solution as the elution solvent (potassium acetate buffer, pH 4.5, containing 10% of methanol) in the SPE procedures was found superior to using 100% methanol, as it provided better extraction recovery (70-90%) and precision (5% for a concentration at 0.1 ppb level). In addition, the eluted sample was in a weaker solvent than the mobile phase, permitting the direct injection of the extracted sample, which enabled a faster cycle time of the overall analysis. Excluding the preparation of calibration standards, the analysis of a single sample, including acidification, extraction, elution and LC run, could be completed in 1 h. The method was used successfully for the determination of clopyralid in over 200 clopyralid monoethanolamine-fortified drinking water samples, which were treated with various water treatment resins. Copyright © 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

Preconcentration and determination of ceftazidime in real samples using dispersive liquid-liquid microextraction and high-performance liquid chromatography with the aid of experimental design.

PubMed

Razmi, Rasoul; Shahpari, Behrouz; Pourbasheer, Eslam; Boustanifar, Mohammad Hasan; Azari, Zhila; Ebadi, Amin

2016-11-01

A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid-liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001-10 μg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Drug Loading Capacity of Environmentally Sensitive Polymeric Microgels

NASA Astrophysics Data System (ADS)

McDonough, Ryan; Streletzky, Kiril; Bayachou, Mekki; Peiris, Pubudu

2009-10-01

Microgel nanoparticles consisting of cross-linked polymer hydroxypropyl cellulose chains have a temperature dependent volume phase transition, prompting the use of microgels for controlled drug transport. Drug particles aggregate in the slightly hydrophobic interior of microgels. Microgels are stored in equilibrium until the critical temperature (Tv) is reached and the volume phase transition limits available space, thus expelling the drugs. Our study was designed to test this property of microgels using amperometric electrochemical methods. A critical assumption was that small molecules inside microgels would not interact via diffusion with the electrode surface and thus total current would be decreased across the electrodes in a microgel sample. A room temperature (Troom) flow amperometric measurement comparing microgel/tylenol solution with control tylenol samples yielded about 20% tylenol concentration reduction of the microgel sample. Results from the steady state electrochemical experiment confirm the presence of about 20% tylenol concentration drop of the microgel sample compared to control sample at Troom. Using the steady-state experiment with a cyclic temperature ramp from Troom to beyond Tv showed that the tylenol concentration change between the temperature extremes was greater for the microgel solution than for the control solution.

Antibody Protein Array Analysis of the Tear Film Cytokines

PubMed Central

Li, Shimin; Sack, Robert; Vijmasi, Trinka; Sathe, Sonal; Beaton, Ann; Quigley, David; Gallup, Marianne; McNamara, Nancy A.

2013-01-01

Purpose Many bioactive proteins including cytokines are reported to increase in dry eye disease although the specific profile and concentration of inflammatory mediators varies considerably from study to study. In part this variability results from inherent difficulties in quantifying low abundance proteins in a limited sample volume using relatively low sensitivity dot ELISA methods. Additional complexity comes with the use of pooled samples collected using a variety of techniques and intrinsic variation in the diurnal pattern of individual tear proteins. The current study describes a recent advance in the area of proteomics that has allowed the identification of dozens of low abundance proteins in human tear samples. Methods Commercially available stationary phase antibody protein arrays were adapted to improve suitability for use in small volume biological fluid analysis with particular emphasis on tear film proteomics. Arrays were adapted to allow simultaneous screening for a panel of inflammatory cytokines in low volume tear samples collected from individual eyes. Results A preliminary study comparing tear array results in a small population of Sjögren’s syndrome patients was conducted. The multiplex microplate array assays of cytokines in tear fluid present an unanticipated challenge due to the unique nature of tear fluid. The presence of factors that exhibit an affinity for plastic, capture antibodies and IgG and create a complex series of matrix effects profoundly impacting the reliability of dot ELISA, including with elevated levels of background reactivity and reduction in capacity to bind targeted protein. Conclusions Preliminary results using tears collected from patients with Sjögren’s syndrome reveal methodological advantages of protein array technology and support the concept that autoimmune-mediated dry eye disease has an inflammatory component. They also emphasize the inherent difficulties one can face when interpreting the results of micro-well arrays that result from blooming effects, matrix effects, image saturation and cross-talk between capture and probe antibodies that can greatly reduce signal-to-noise and limit the ability to obtain meaningful results. PMID:18677223

Feasibility of high-resolution one-dimensional relaxation imaging at low magnetic field using a single-sided NMR scanner applied to articular cartilage.

PubMed

Rössler, Erik; Mattea, Carlos; Stapf, Siegfried

2015-02-01

Low field Nuclear Magnetic Resonance increases the contrast of the longitudinal relaxation rate in many biological tissues; one prominent example is hyaline articular cartilage. In order to take advantage of this increased contrast and to profile the depth-dependent variations, high resolution parameter measurements are carried out which can be of critical importance in an early diagnosis of cartilage diseases such as osteoarthritis. However, the maximum achievable spatial resolution of parameter profiles is limited by factors such as sensor geometry, sample curvature, and diffusion limitation. In this work, we report on high-resolution single-sided NMR scanner measurements with a commercial device, and quantify these limitations. The highest achievable spatial resolution on the used profiler, and the lateral dimension of the sensitive volume were determined. Since articular cartilage samples are usually bent, we also focus on averaging effects inside the horizontally aligned sensitive volume and their impact on the relaxation profiles. Taking these critical parameters into consideration, depth-dependent relaxation time profiles with the maximum achievable vertical resolution of 20 μm are discussed, and are correlated with diffusion coefficient profiles in hyaline articular cartilage in order to reconstruct T(2) maps from the diffusion-weighted CPMG decays of apparent relaxation rates. Copyright © 2014 Elsevier Inc. All rights reserved.

Gradient, contact-free volume transfers minimize compound loss in dose-response experiments.

PubMed

Harris, David; Olechno, Joe; Datwani, Sammy; Ellson, Richard

2010-01-01

More accurate dose-response curves can be constructed by eliminating aqueous serial dilution of compounds. Traditional serial dilutions that use aqueous diluents can result in errors in dose-response values of up to 4 orders of magnitude for a significant percentage of a compound library. When DMSO is used as the diluent, the errors are reduced but not eliminated. The authors use acoustic drop ejection (ADE) to transfer different volumes of model library compounds, directly creating a concentration gradient series in the receiver assay plate. Sample losses and contamination associated with compound handling are therefore avoided or minimized, particularly in the case of less water-soluble compounds. ADE is particularly well suited for assay miniaturization, but gradient volume dispensing is not limited to miniaturized applications.

Flux-limited sample of Galactic carbon stars

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

Claussen, M.J.; Kleinmann, S.G.; Joyce, R.R.

Published observational data (including IRAS observations) for a flux-limited sample of 215 Galactic carbon stars (CSs) selected from the 2-micron sky survey of Neugebauer and Leighton (1969) are compiled in extensive tables and graphs and analyzed statistically. The sample is found to penetrate a volume of radius 1.5 kpc, and the local CS space density and surface density are calculated as log rho0 (per cu kpc) = 2.0 + or - 0.4 and log N (per sq kpc) = 1.6 + or - 0.2, respectively. The total Galactic mass-return rate from these CSs is estimated as 0.013 solar mass/yr, implyingmore » a time scale of 0.1-1 Myr for the CS evolutionary phase and a mass of 1.2-1.6 solar mass for the (probably F-type) main-seqence progenitors of CSs. 81 references.« less

Asbestos Air Monitoring Results at Eleven Family Housing Areas throughout the United States.

DTIC Science & Technology

1991-05-23

limits varied depending on sampling volumes and grid openings scanned. Therefore, the detection limits presented in the results summary tables vary...1 f/10 grid squares) (855 mm 2) (1 liter) = 3054 liters (0.005 f/cc) (0.0056 mm 2) (1000 cc) Where: * 1 f/10 grid squares (the maximum recommended...diameter filter. * 0.0056 mm 2 is the area of each grid square (75 /Jm per side) in a 200 mesh electron microscope grid . This value will vary from 0.0056

A complete hard X-ray selected sample of local, luminous AGNs

NASA Astrophysics Data System (ADS)

Burtscher, Leonard; Davies, Ric; Lin, Ming-yi; Orban de Xivry, Gilles; Rosario, David

2016-08-01

Choosing a very well defined sample is essential for studying the AGN phenomenon. Only the most luminous AGNs can be expected to require a coherent feeding mechanism to sustain their activity and since host galaxy properties and AGN activity are essentially uncorrelated, nuclear scales must be resolved in order to shed light on the feeding mechanisms of AGNs. For these reasons we are compiling a sample of the most powerful, local AGNs. In this talk we present our on-going programme to observe a complete volume limited sample of nearby active galaxies selected by their 14-195 keV luminosity, and outline its rationale for studying the mechanisms regulating gas inflow and outflow.

Creating compact and microscale features in paper-based devices by laser cutting.

PubMed

Mahmud, Md Almostasim; Blondeel, Eric J M; Kaddoura, Moufeed; MacDonald, Brendan D

2016-11-14

In this work we describe a fabrication method to create compact and microscale features in paper-based microfluidic devices using a CO 2 laser cutting/engraving machine. Using this method we are able to produce the smallest features with the narrowest barriers yet reported for paper-based microfluidic devices. The method uses foil backed paper as the base material and yields inexpensive paper-based devices capable of using small fluid sample volumes and thus small reagent volumes, which is also suitable for mass production. The laser parameters (power and laser head speed) were adjusted to minimize the width of hydrophobic barriers and we were able to create barriers with a width of 39 ± 15 μm that were capable of preventing cross-barrier bleeding. We generated channels with a width of 128 ± 30 μm, which we found to be the physical limit for small features in the chromatography paper we used. We demonstrate how miniaturizing of paper-based microfluidic devices enables eight tests on a single bioassay device using only 2 μL of sample fluid volume.

Variability of bisphenol-A concentrations in first morning, bedtime, and 24-hour urine samples in 50 North Carolina adults over a six-week period

EPA Science Inventory

Bisphenol-A (BPA) is a high-production volume chemical that is used to make a number of consumer products and packaged goods. Many cross-sectional studies have frequently reported detecting BPA in urine. However, limited data exist on the temporal variability of urinary BPA conce...

40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

Code of Federal Regulations, 2010 CFR

2010-07-01

... percent reduction may be measured as total epoxide, total organic HAP, or as TOC minus methane and ethane... TOC (minus methane and ethane) concentrations in all process vent streams and primary and secondary... million by volume total epoxide or TOC limit in § 63.1425(b)(1)(ii) or (b)(2)(iii), the sampling site...

Phase 2 Site Investigations Report. Volume 1 of 3: General Annex-Wide Information

DTIC Science & Technology

1994-09-01

completeness PCB Polychlorinated Biphenyl PCE Tetrachloroethene or Perchloroethene PHC Petroleum hydrocarbons PID Photoionization Detector POLs Petroleum , Oil...TEPS Total Environmental Program Support TIC Tentatively Identified Compound TOC Total Organic Carbon TPHC Total Petroleum Hydrocarbons TRC Technical... hydrocarbons were identified within some soil and sediment samples near the detection limit. These could result from urban runoff. No petroleum

High-order graph matching based feature selection for Alzheimer's disease identification.

PubMed

Liu, Feng; Suk, Heung-Il; Wee, Chong-Yaw; Chen, Huafu; Shen, Dinggang

2013-01-01

One of the main limitations of l1-norm feature selection is that it focuses on estimating the target vector for each sample individually without considering relations with other samples. However, it's believed that the geometrical relation among target vectors in the training set may provide useful information, and it would be natural to expect that the predicted vectors have similar geometric relations as the target vectors. To overcome these limitations, we formulate this as a graph-matching feature selection problem between a predicted graph and a target graph. In the predicted graph a node is represented by predicted vector that may describe regional gray matter volume or cortical thickness features, and in the target graph a node is represented by target vector that include class label and clinical scores. In particular, we devise new regularization terms in sparse representation to impose high-order graph matching between the target vectors and the predicted ones. Finally, the selected regional gray matter volume and cortical thickness features are fused in kernel space for classification. Using the ADNI dataset, we evaluate the effectiveness of the proposed method and obtain the accuracies of 92.17% and 81.57% in AD and MCI classification, respectively.

A Modified LC/MS/MS Method with Enhanced Sensitivity for the Determination of Scopolamine in Human Plasma

NASA Technical Reports Server (NTRS)

Wang, Zuwei; Vaksman, Zalman; Putcha, Lakshmi

2008-01-01

Intranasal scopolamine is a choice drug for the treatment of motion sickness during space flight because of its quick onset of action, short half-life and favorable sideeffects profile. The dose administered usually ranges between 0.1 and 0.4 mg. Such small doses make it difficult to detect concentrations of scopolamine in biological fluids using existing sensitive LC/MS/MS method, especially when the biological sample volumes are limited. To measure scopolamine in human plasma to facilitate pharmacokinetic evaluation of the drug, we developed a sensitive LC/MS/MS method using 96 well micro elution plates for solid phase extraction (SPE) of scopolamine in human plasma. Human plasma (100-250 micro L) were loaded onto Waters Oasis HLB 96 well micro elution plate and eluted with 50 L of organic solvent without evaporation and reconstitution. HPLC separation of the eluted sample was performed using an Agilent Zorbax SB-CN column (50 x 2.1 mm) at a flow rate of 0.2 mL/min for 3 minutes. The mobile phase for separation was 80:20 (v/v) methanol: ammonium acetate (30 mM) in water. Concentrations of scopolamine were determined using a Micromass Quattro Micro(TM) mass spectrometer with electrospray ionization (ESI). ESI mass spectra were acquired in positive ion mode with multiple reaction monitoring for the determination of scopolamine m/z = 304.2 right arrow 138.1 and internal standard hyoscyamine m/z = 290.2 right arrow 124.1. The method is rapid, reproducible, specific and has the following parameters: scopolamine and the IS are eluted at about 1.1 and 1.7 min respectively. The linear range is 25-10000 pg/mL for scopolamine in human plasma with correlation coefficients greater than 0.99 and CV less than 0.5%. The intra-day and inter-day CVs are less than 15% for quality control samples with concentrations of 75,300, and 750 pg/mL of scopolamine in human plasma. SPE using 96 well micro elution plates allows rapid sample preparation and enhanced sensitivity for the LC/MS/MS determination of scopolamine in a small volume of biological samples. The new method is also cost effective since it uses a small volume of organic solvents compared to the methods using SPE cartridges or regular 96 well SPE plates. This method can be successfully used for bioavailability and pharmacokinetic evaluations of scopolamine, especially when volumes of biological samples are limited. Further investigation to use automated SPE system with 96 well micro elution plates is planned.

Polymeric ionic liquid-based portable tip microextraction device for on-site sample preparation of water samples.

PubMed

Chen, Lei; Pei, Junxian; Huang, Xiaojia; Lu, Min

2018-06-05

On-site sample preparation is highly desired because it avoids the transportation of large-volume samples and ensures the accuracy of the analytical results. In this work, a portable prototype of tip microextraction device (TMD) was designed and developed for on-site sample pretreatment. The assembly procedure of TMD is quite simple. Firstly, polymeric ionic liquid (PIL)-based adsorbent was in-situ prepared in a pipette tip. After that, the tip was connected with a syringe which was driven by a bidirectional motor. The flow rates in adsorption and desorption steps were controlled accurately by the motor. To evaluate the practicability of the developed device, the TMD was used to on-site sample preparation of waters and combined with high-performance liquid chromatography with diode array detection to measure trace estrogens in water samples. Under the most favorable conditions, the limits of detection (LODs, S/N = 3) for the target analytes were in the range of 4.9-22 ng/L, with good coefficients of determination. Confirmatory study well evidences that the extraction performance of TMD is comparable to that of the traditional laboratory solid-phase extraction process, but the proposed TMD is more simple and convenient. At the same time, the TMD avoids complicated sampling and transferring steps of large-volume water samples. Copyright © 2018 Elsevier B.V. All rights reserved.

An Ultra-Sensitive Method for the Analysis of Perfluorinated ...

EPA Pesticide Factsheets

In epidemiological research, it has become increasingly important to assess subjects' exposure to different classes of chemicals in multiple environmental media. It is a common practice to aliquot limited volumes of samples into smaller quantities for specific trace level chemical analysis. A novel method was developed for the determination of 14 perfluorinated alkyl acids (PFAAs) in small volumes (10 mL) of drinking water using off-line solid phase extraction (SPE) pre-treatment followed by on-line pre-concentration on WAX column before analysis on column-switching high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). In general, large volumes (100 - 1000 mL) have been used for the analysis of PFAAs in drinking water. The current method requires approximately 10 mL of drinking water concentrated by using an SPE cartridge and eluted with methanol. A large volume injection of the extract was introduced on to a column-switching HPLC-MS/MS using a mix-mode SPE column for the trace level analysis of PFAAs in water. The recoveries for most of the analytes in the fortified laboratory blanks ranged from 73±14% to 128±5%. The lowest concentration minimum reporting levels (LCMRL) for the 14 PFAAs ranged from 0.59 to 3.4 ng/L. The optimized method was applied to a pilot-scale analysis of a subset of drinking water samples from an epidemiological study. These samples were collected directly from the taps in the households of Ohio and Nor

Solid-phase extraction of iridium from soil and water samples by using activated carbon cloth prior to its spectrophotometric determination.

PubMed

Ozkantar, Nebiye; Yilmaz, Erkan; Soylak, Mustafa; Tuzen, Mustafa

2015-08-01

A solid-phase extraction method for separation and preconcentration of Ir(IV) ion by using activated carbon cloth (ACC) has been presented. Ir(IV) as their 1-(2-pyridylazo) 2-naphtol (PAN) chelate was adsorbed on ACC at pH 2.0 and was eluted from ACC with acidic dimethylformamide (DMF). The Ir(IV) concentration was determined at 536 nm as Ir(IV)-PAN complex by using UV-vis spectrophotometer. The analytical parameters including pH, sample and eluent flow rates, amount of PAN, eluent type, concentration, and sample volume were optimized. The effects of foreign ions on the recoveries of iridium were also investigated. The preconcentration factor was calculated as 60. The limit of detection (LOD) and the limit of quantification (LOQ) of the method were found as 0.039 and 0.129 μg L(-1), respectively. The method was applied to soil and water samples for iridium determination.

Smart fast blood counting of trace volumes of body fluids from various mammalian species using a compact custom-built microscope cytometer (Conference Presentation)

NASA Astrophysics Data System (ADS)

Smith, Zachary J.; Gao, Tingjuan; Lin, Tzu-Yin; Carrade-Holt, Danielle; Lane, Stephen M.; Matthews, Dennis L.; Dwyre, Denis M.; Wachsmann-Hogiu, Sebastian

2016-03-01

Cell counting in human body fluids such as blood, urine, and CSF is a critical step in the diagnostic process for many diseases. Current automated methods for cell counting are based on flow cytometry systems. However, these automated methods are bulky, costly, require significant user expertise, and are not well suited to counting cells in fluids other than blood. Therefore, their use is limited to large central laboratories that process enough volume of blood to recoup the significant capital investment these instruments require. We present in this talk a combination of a (1) low-cost microscope system, (2) simple sample preparation method, and (3) fully automated analysis designed for providing cell counts in blood and body fluids. We show results on both humans and companion and farm animals, showing that accurate red cell, white cell, and platelet counts, as well as hemoglobin concentration, can be accurately obtained in blood, as well as a 3-part white cell differential in human samples. We can also accurately count red and white cells in body fluids with a limit of detection ~3 orders of magnitude smaller than current automated instruments. This method uses less than 1 microliter of blood, and less than 5 microliters of body fluids to make its measurements, making it highly compatible with finger-stick style collections, as well as appropriate for small animals such as laboratory mice where larger volume blood collections are dangerous to the animal's health.

Grey matter, an endophenotype for schizophrenia? A voxel-based morphometry study in siblings of patients with schizophrenia

PubMed Central

van der Velde, Jorien; Gromann, Paula M.; Swart, Marte; de Haan, Lieuwe; Wiersma, Durk; Bruggeman, Richard; Krabbendam, Lydia; Aleman, André

2015-01-01

Background Grey matter, both volume and concentration, has been proposed as an endophenotype for schizophrenia given a number of reports of grey matter abnormalities in relatives of patients with schizophrenia. However, previous studies on grey matter abnormalities in relatives have produced inconsistent results. The aim of the present study was to examine grey matter differences between controls and siblings of patients with schizophrenia and to examine whether the age, genetic loading or subclinical psychotic symptoms of selected individuals could explain the previously reported inconsistencies. Methods We compared the grey matter volume and grey matter concentration of healthy siblings of patients with schizophrenia and healthy controls matched for age, sex and education using voxel-based morphometry (VBM). Furthermore, we selected subsamples based on age (< 30 yr), genetic loading and subclinical psychotic symptoms to examine whether this would lead to different results. Results We included 89 siblings and 69 controls in our study. The results showed that siblings and controls did not differ significantly on grey matter volume or concentration. Furthermore, specifically selecting participants based on age, genetic loading or subclinical psychotic symptoms did not alter these findings. Limitations The main limitation was that subdividing the sample resulted in smaller samples for the subanalyses. Furthermore, we used MRI data from 2 different scanner sites. Conclusion These results indicate that grey matter measured through VBM might not be a suitable endophenotype for schizophrenia. PMID:25768029

Rapid simultaneous determination of amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine, and 3,4-methylenedioxyethylamphetamine in urine by solid-phase extraction and GC-MS: a method optimized for high-volume laboratories.

PubMed

Stout, Peter R; Horn, Carl K; Klette, Kevin L

2002-01-01

To facilitate analysis of high sample volumes, an extraction, derivatization and gas chromatographic-mass spectrometric analysis method was developed to simultaneously determine amphetamine (AMP), methamphetamine (MAMP), 3,4-methylenedioxyamphetamine (MDA) 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxyethylamphetamine (MDEA) in urine. This method utilized a positive-pressure manifold cation-exchange polymer-based solid-phase extraction followed by elution directly into automated liquid sampler (ALS) vials. Rapid derivatization was accomplished using heptafluorobutyric anhydride (HFBA). Recoveries averaged 90% or greater for each of the compounds. Limits of detection were 62.5 ng/mL (AMP and MDEA), 15.6 ng/mL (MAMP), and 31.3 ng/mL (MDA and MDMA) using a 2-mL sample volume. The method was linear to 5000 ng/mL for all compounds using MDMA-d5 and MAMP-d14 as internal standards. Over 200 human urine samples previously determined to contain the target analytes were analyzed using the method. Excellent agreement was seen with previous quantitations. The method was challenged with 75 potentially interfering compounds and no interferences were seen. These interfering compounds included ephedrine, pseudoephedrine, phenylpropanolamine, and phenethylamine. The method resulted in dramatic reductions in processing time and waste production.

Tank Vapor Characterization Project: Tank 241-S-102 fourth temporal study: Headspace gas and vapor characterization results from samples collected on December 19, 1996

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

Pool, K.H.; Evans, J.C.; Olsen, K.B.

1997-08-01

This report presents the results from analyses of samples taken from the headspace of waste storage tank 241-S-102 (Tank S-102) at the Hanford Site in Washington State. Tank headspace samples collected by SGN Eurisys Service Corporation (SESC) were analyzed by Pacific Northwest National Laboratory (PNNL) to determine headspace concentrations of selected non-radioactive analytes. Analyses were performed by the Vapor Analytical Laboratory (VAL) at PNNL. Vapor concentrations from sorbent trap samples are based on measured sample volumes provided by SESC. Ammonia was determined to be above the immediate notification limit of 150 ppm as specified by the sampling and analysis planmore » (SAP). Hydrogen was the principal flammable constituent of the Tank S-102 headspace, determined to be present at approximately 2.410% of its lower flammability limit (LFL). Total headspace flammability was estimated to be <2.973% of its lower flammability limit (LFL). Total headspace flammability was estimated to be <2.973% of the LFL. Average measured concentrations of targeted gases, inorganic vapors, and selected organic vapors are provided in Table S.1. A summary of experimental methods, including sampling methodology, analytical procedures, and quality assurance and control methods are presented in Section 2.0. Detailed descriptions of the analytical results are provided in Section 3.0.« less

Sensitive indoor air monitoring of formaldehyde and other carbonyl compounds using the 2,4-dinitrophenylhydrazine method.

PubMed

Sandner, F; Dott, W; Hollender, J

2001-03-01

The toxic potential of formaldehyde and other aliphatic/aromatic carbonyl compounds requires the determination of even low amounts of these compounds in indoor air. The existing DFG-method for workplace monitoring using adsorption at 2,4-dinitrophenylhydrazine (DNPH)-coated sorbents followed by HPLC-UV/DAD analysis of the extract was modified in order to decrease detection limits. The improvement included an increase in volume and rate of the air sampling, testing applicability of different adsorption materials and a decrease of the extraction volume of the hydrazones. 13 DNPH-derivatives could be separated well on a RP18-column followed by UV/DAD-detection at 365 nm. Recovery rates of 70-100% were determined (apart from acetone with 19%) using dynamically produced artifical carbonyl atmospheres. Detection limits of 0.05-0.4 microgram/m3 were reached by this method which are sufficient for indoor air monitoring.

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

None

Volume II of the Site Environmental Report for 2006 is provided by Ernest Orlando Lawrence Berkeley National Laboratory as a supplemental appendix to Volume I, which contains the body of the report. Volume II contains the environmental monitoring and sampling data used to generate summary results of routine and nonroutine activities at the Laboratory (except for groundwater sampling data, which may be found in the reports referred to in Chapter 4). Volume I summarizes the results from analyses of the data. The results from sample collections are more comprehensive in Volume II than in Volume I: For completeness, all resultsmore » from sample collections that began or ended in calendar year (CY) 2006 are included in this volume. However, the samples representing CY 2005 data have not been used in the summary results that are reported in Volume I. (For example, although ambient air samples collected on January 2, 2006, are presented in Volume II, they represent December 2005 data and are not included in Table 4-2 in Volume I.)« less

40 CFR Table 1b to Subpart Ce of... - Emissions Limits for Small, Medium, and Large HMIWI at Designated Facilities as Defined in § 60...

Code of Federal Regulations, 2011 CFR

2011-07-01

....011) 3-run average (1-hour minimum sample time per run) EPA Reference Method 5 of appendix A-3 of part... by volume (ppmv) 20 5.5 11 3-run average (1-hour minimum sample time per run) EPA Reference Method 10... dscf) 16 (7.0) or 0.013 (0.0057) 0.85 (0.37) or 0.020 (0.0087) 9.3 (4.1) or 0.054 (0.024) 3-run average...

Multiplex gas chromatography: an alternative concept for gas chromatographic analysis of planetary atmospheres

NASA Technical Reports Server (NTRS)

Valentin, J. R.

1989-01-01

Gas chromatography (GC) is a powerful technique for analyzing gaseous mixtures. Applied to the earth's atmosphere, GC can be used to determine the permanent gases--such as carbon dioxide, nitrogen, and oxygen--and to analyze organic pollutants in air. The U.S. National Aeronautics and Space Administration (NASA) has used GC in spacecraft missions to Mars (the Viking Biology Gas Exchange Experiment [GEX] and the Viking Gas Chromatograph-Mass Spectrometer [GC-MS]) and to Venus (the Pioneer Venus Gas Chromatograph [PVGC] on board the Pioneer Venus sounder probe) for determining the atmospheric constituents of these two planets. Even though conventional GC was very useful in the Viking and Pioneer missions, spacecraft constraints and limitations intrinsic to the technique prevented the collection of more samples. With the Venus probe, for instance, each measurement took a relatively long time to complete (10 min), and successive samples could not be introduced until the previous samples had left the column. Therefore, while the probe descended through the Venusian atmosphere, only three samples were acquired at widely separated altitudes. With the Viking mission, the sampling rate was not a serious problem because samples were acquired over a period of one year. However, the detection limit was a major disadvantage. The GC-MS could not detect simple hydrocarbons and simple alcohols below 0.1 ppm, and the GEX could not detect them below 1 ppm. For more complex molecules, the detection limits were at the parts-per-billion level for both instruments. Finally, in both the Viking and Pioneer missions, the relatively slow rate of data acquisition limited the number of analyses, and consequently, the amount of information returned. Similar constraints are expected in future NASA missions. For instance, gas chromatographic instrumentation is being developed to collect and analyze organic gases and aerosols in the atmosphere of Titan (one of Saturn's satellites). The Titan-Cassini entry probe, which is being jointly planned by NASA and the European Space Agency (ESA), might be launched as early as 1994. As in the Pioneer mission, limited time--perhaps only 3-4 h--will be available for the completion of all analyses while the probe descends through the atmosphere. A conventional GC or GC-MS system would be able to analyze no more than two aerosol and two gas samples during the probe's descent. Conventional GC also is limited by the sensitivity of the detector and by the sample volume. For the Titan mission, the sensitivity problems will be worse because the atmospheric pressure at the time of instrument deployment is expected to be < 3 torr. Consequently, the sample volume might not be large enough to satisfy the detector sensitivity requirements. Because of such limitations, alternative GC analysis techniques have been investigated for future NASA missions. Multiplex gas chromatography has been investigated as a possible candidate for chemical analysis within a spacecraft or other restricted environment, and chemical modulators have been developed and used when needed with this technique to reduce the size and weight of the instrumentation. Also, several new multiplex techniques have been developed for use in specific applications.

Probing the statistics of primordial fluctuations and their evolution

NASA Technical Reports Server (NTRS)

Gaztanaga, Enrique; Yokoyama, Jun'ichi

1993-01-01

The statistical distribution of fluctuations on various scales is analyzed in terms of the counts in cells of smoothed density fields, using volume-limited samples of galaxy redshift catalogs. It is shown that the distribution on large scales, with volume average of the two-point correlation function of the smoothed field less than about 0.05, is consistent with Gaussian. Statistics are shown to agree remarkably well with the negative binomial distribution, which has hierarchial correlations and a Gaussian behavior at large scales. If these observed properties correspond to the matter distribution, they suggest that our universe started with Gaussian fluctuations and evolved keeping hierarchial form.

Defect evolution and impurity migration in Na-implanted ZnO

NASA Astrophysics Data System (ADS)

Neuvonen, Pekka T.; Vines, Lasse; Venkatachalapathy, Vishnukanthan; Zubiaga, Asier; Tuomisto, Filip; Hallén, Anders; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

2011-11-01

Secondary ion mass spectrometry (SIMS) and positron annihilation spectroscopy (PAS) have been applied to study impurity migration and open volume defect evolution in Na+ implanted hydrothermally grown ZnO samples. In contrast to most other elements, the presence of Na tends to decrease the concentration of open volume defects upon annealing and for temperatures above 600∘C, Na exhibits trap-limited diffusion correlating with the concentration of Li. A dominating trap for the migrating Na atoms is most likely Li residing on Zn site, but a systematic analysis of the data suggests that zinc vacancies also play an important role in the trapping process.

Evaluation of 1.0 mm i.d. column performances on ultra high pressure liquid chromatography instrumentation.

PubMed

Lestremau, François; Wu, Di; Szücs, Roman

2010-07-23

The present study focuses on the evaluation of 1.0 mm i.d. (internal diameter) columns on a commercial Ultra-High Pressure system. These systems have been developed specifically to operate columns with small volumes, typically 2.1 mm i.d., by reducing extra-column volume dispersion. The use of columns with smaller i.d. results in a reduced solvent consumption and required sample volume. The evaluation of the columns was carried out with samples containing neutral and pharmaceutical compounds. In isocratic mode, the extra-column volume produced additional band broadening leading to poor performances compared to equivalent 2.1 mm i.d. columns. By increasing the length of the column, the influence of the extra-column bandspreading could be reduced and 75,000 plates were obtained when four columns were coupled. In gradient mode, the effect of the extra-column contribution on efficiency was limited and about 80% of the performance of the 2.1 mm i.d. columns was obtained. Optimum conditions in gradient mode were further investigated by changing flow rate, gradient time and column length. A different approach of the calculation of peak capacity was also considered for the comparison of the influence of these different parameters. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Alginate Hydrogel Microencapsulation Inhibits Devitrification and Enables Large-Volume Low-CPA Cell Vitrification

PubMed Central

Huang, Haishui; Choi, Jung Kyu; Rao, Wei; Zhao, Shuting; Agarwal, Pranay; Zhao, Gang

2015-01-01

Cryopreservation of stem cells is important to meet their ever-increasing demand by the burgeoning cell-based medicine. The conventional slow freezing for stem cell cryopreservation suffers from inevitable cell injury associated with ice formation and the vitrification (i.e., no visible ice formation) approach is emerging as a new strategy for cell cryopreservation. A major challenge to cell vitrification is intracellular ice formation (IIF, a lethal event to cells) induced by devitrification (i.e., formation of visible ice in previously vitrified solution) during warming the vitrified cells at cryogenic temperature back to super-zero temperatures. Consequently, high and toxic concentrations of penetrating cryoprotectants (i.e., high CPAs, up to ~8 M) and/or limited sample volumes (up to ~2.5 μl) have been used to minimize IIF during vitrification. We reveal that alginate hydrogel microencapsulation can effectively inhibit devitrification during warming. Our data show that if ice formation were minimized during cooling, IIF is negligible in alginate hydrogel-microencapsulated cells during the entire cooling and warming procedure of vitrification. This enables vitrification of pluripotent and multipotent stem cells with up to ~4 times lower concentration of penetrating CPAs (up to 2 M, low CPA) in up to ~100 times larger sample volume (up to ~250 μl, large volume). PMID:26640426

Alginate Hydrogel Microencapsulation Inhibits Devitrification and Enables Large-Volume Low-CPA Cell Vitrification.

PubMed

Huang, Haishui; Choi, Jung Kyu; Rao, Wei; Zhao, Shuting; Agarwal, Pranay; Zhao, Gang; He, Xiaoming

2015-11-25

Cryopreservation of stem cells is important to meet their ever-increasing demand by the burgeoning cell-based medicine. The conventional slow freezing for stem cell cryopreservation suffers from inevitable cell injury associated with ice formation and the vitrification ( i.e. , no visible ice formation) approach is emerging as a new strategy for cell cryopreservation. A major challenge to cell vitrification is intracellular ice formation (IIF, a lethal event to cells) induced by devitrification ( i.e. , formation of visible ice in previously vitrified solution) during warming the vitrified cells at cryogenic temperature back to super-zero temperatures. Consequently, high and toxic concentrations of penetrating cryoprotectants ( i.e. , high CPAs, up to ~8 M) and/or limited sample volumes (up to ~2.5 μl) have been used to minimize IIF during vitrification. We reveal that alginate hydrogel microencapsulation can effectively inhibit devitrification during warming. Our data show that if ice formation were minimized during cooling, IIF is negligible in alginate hydrogel-microencapsulated cells during the entire cooling and warming procedure of vitrification. This enables vitrification of pluripotent and multipotent stem cells with up to ~4 times lower concentration of penetrating CPAs (up to 2 M, low CPA) in up to ~100 times larger sample volume (up to ~250 μl, large volume).

A micro-fluidic sub-microliter sample introduction system for direct analysis of Chinese rice wine by inductively coupled plasma mass spectrometry using external aqueous calibration

NASA Astrophysics Data System (ADS)

Cheng, Heyong; Liu, Jinhua; Xu, Zigang; Yin, Xuefeng

2012-07-01

A microfluidic sub-microliter sample introducing system was developed for direct analysis of Chinese rice wine by inductively coupled plasma mass spectrometry (ICP-MS). It consisted of a microfluidic chip integrating variable-volume sampling channels (0.1-0.8 μL), an eight-way multi-functional valve used in flow injection analysis (FIA), a syringe pump and a peristaltic pump of the Ar ICP-MS instrument. Three solutions, i.e., 15, 40 and 100 g L- 1 glucose in 20% ethanol were used to simulate Chinese rice wine of the dry type, the semidry type and the semisweet type, each. The effects of their volume introduced into ICP-MS on the plasma stability and ICP-MS intensities were studied. The experimental results showed that neither alteration of plasma stability nor carbon deposition was observed when the sampling volume of 20% ethanol containing 100 g L- 1 glucose was downscaled to 0.8 μL. Further reducing the sampling volume to 0.4 μL, no significant difference between the intensities of multi-element standard prepared in three simulated Chinese rice wine matrices and those in aqueous solution was observed. It indicated no negative effect of Chinese rice wine matrix on the ICP-MS intensities. A sampling volume of 0.4 μL was considered to be a good compromise between sensitivity and matrix effect. The flow rate of the carrier was chosen as 20 μL min- 1 for obtaining peaks with the highest peak height within the shortest time. Based on these observations, a microflow injection (μFI) method for the direct determination of cadmium and lead in Chinese rice wine by ICP-MS using an external aqueous calibration was developed. The sample throughput was 45 h- 1 with the detection limit of 19.8 and 10.4 ng L- 1 for Cd and Pb, respectively. The contents of Cd and Pb in 10 Chinese rice wine samples were measured. The results agreed well with those determined by ICP-MS with the conventional sampling system after microwave assisted digestion. The recoveries of three Chinese rice wine samples ranged between 95.5 and 102.8%. Furthermore, the determined contents of Cd and Pb in a certified reference material of red wine (GBW 10031) and a quality control test material of wine (FAPAS T07163QC) by the proposed method were in fairly good accordance with the certified/assigned values. All results verified the accuracy of our method.

One-step synthesis of magnetic graphene oxide nanocomposite and its application in magnetic solid phase extraction of heavy metal ions from biological samples.

PubMed

Sun, Jieping; Liang, Qionglin; Han, Qiang; Zhang, Xiaoqiong; Ding, Mingyu

2015-01-01

A novel magnetic graphene oxide nanocomposite was synthesized by one-step coprecipitation method and characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometer. The nanocomposite beard many intriguing properties, including chemical stability, high adsorption capacity, and superparamagnetic. These properties evoked great interest and desire of its exploration in magnetic solid-phase extraction of heavy metal ions from complex samples. Several parameters effecting the analytical performance, such as the sample pH, amounts of adsorbent, sample volumes, elution volumes, and coexisting ions, had been investigated in detail. The adsorbed metal ions were easy eluted by controlling the pH condition and the materials could be reused more than 20 times. Under the optimized conditions, the limits of detection were 0.016, 0.046, 0.395, 0.038, 0.157 μg L(-1) for Co(2+), Ni(2+), Cu(2+), Cd(2+), and Pb(2+), respectively. The intra-day relative standard deviations (n=5) were in the range of 1.8-5.5% at 10 μg L(-1). The proposed method was successfully applied to biological sample analysis and got excellent recoveries in the range of 81-113% even the matrix was complex. Copyright © 2014 Elsevier B.V. All rights reserved.

Modeling a CO2 mineralization experiment of fractured peridotite from the Semail ophiolite/ Oman

NASA Astrophysics Data System (ADS)

Muller, Nadja; Zhang, Guoxiang; van Noort, Reinier; Spiers, Chris; Ten Grotenhuis, Saskia; Hoedeman, Gerco

2010-05-01

Most geologic CO2 sequestration technologies focus on sedimentary rocks, where the carbon dioxide is stored in a fluid phase. A possible alternative is to trap it as a mineral in the subsurface (in-situ) in basaltic or even (ultra)mafic rocks. Carbon dioxide in aqueous solution reacts with Mg-, Ca-, and Fe-bearing silicate minerals, precipitates as (MgCa,Fe)CO3 (carbonate), and can thus be permanently sequestered. The cation donors are silicate minerals such as olivine and pyroxene which are abundant in (ultra)mafic rocks, such as peridotite. Investigations are underway to evaluate the sequestration potential of the Semail Ophiolite in Oman, utilizing the large volumes of partially serpentinized peridotite that are present. Key factors are the rate of mineralization due to dissolution of the peridotite and precipitation of carbonate, the extent of the natural and hydraulic fracture network and the accessibility of the rock to reactive fluids. To quantify the influence of dissolution rates on the overall CO2 mineralization process, small, fractured peridotite samples were exposed to supercritical CO2 and water in laboratory experiments. The samples are cored from a large rock sample in the dimension of small cylinders with 1 cm in height and diameter, with a mass of ~2g. Several experimental conditions were tested with different equipment, from large volume autoclave to small volume cold seal vessel. The 650 ml autoclave contained 400-500g of water and a sample under 10 MPa of partial CO2 pressure up to 150. The small capsules in the cold seal vessel held 1-1.5g of water and the sample under CO2 partial pressure from 15MPa to 70 MPa and temperature from 60 to 200°C. The samples remained for two weeks in the reaction vessels. In addition, bench acid bath experiments in 150 ml vials were performed open to the atmosphere at 50-80°C and pH of ~3. The main observation was that the peridotite dissolved two orders of magnitude slower in the high pressure and temperature cell of the cold seal vessel than comparative experiments in large volume autoclaves and bench acid bath vials under lower and atmospheric pressure conditions. We attributed this observation to the limited water availability in the cold seal vessel, limiting the aqueous reaction of bi-carbonate formation and magnesite precipitation. To test this hypothesis, one of the cold seal vessel experiments at 20 MPa and 100°C was simulated with a reactive transport model, using TOUGHREACT. To simulate the actual experimental conditions, the model used a grid on mm and 100's of μm scale and a fractured peridotite medium with serpentine filling the fractures. The simulation produced dissolution comparable to the experiment and showed an effective shut down of the bi-carbonation reaction within one day after the start of the experiment. If the conditions of limited water supply seen in our experiments are applicable in a field setting, we could expect dissolution may be limited by the buffering of the pH and shut down of the bi-carbonate formation. Under field conditions water and CO2 will only flow in hydraulic induced fractures and the natural fracture network that is filled with serpentine and some carbonate. The simulation result and potential implication for the field application will require further experimental investigation in the lab or field in the future.

Quantitative determination of atenolol in dried blood spot samples by LC-HRMS: a potential method for assessing medication adherence.

PubMed

Lawson, Graham; Cocks, Elizabeth; Tanna, Sangeeta

2012-05-15

The use of blood spot collection cards was investigated as a means of obtaining small volume samples for the quantification of therapeutic drugs for assessing medication adherence. A liquid chromatography-high resolution TOF mass spectrometry (LC-HRMS) method, based on the measurement at the accurate mass to charge ratio of the target analyte, was used to ensure specificity for atenolol in the dried blood spot (DBS) samples. A working method was developed and validated. For the preparation of DBS samples whole blood spiked with analyte was used to produce 30 μl blood spots on specimen collection cards. A 5mm disc was cut from the dried blood spot and extracted using methanol:water (60:40, v/v) containing the internal standard, atenolol-d(7). Extracts were vortexed, sonicated and then centrifuged. Gradient chromatographic elution was achieved using an Ascentis Express C18 100mm×2.1mm column and a mobile phase flow rate of 0.2 ml/min and the column oven temperature at 30 °C. MS detection was carried out in electrospray positive ion mode for target ions at accurate mass m/z 267.1703 for atenolol and 274.2143 for the IS. Drug extraction efficiency from spiked blood spots was demonstrated to be 96±5% and the drug was stable in DBS for at least 10 weeks. The developed LC-HRMS method was linear within the tested calibration range of 25-1500 ng/ml and validation showed the accuracy (relative error) and precision (coefficient of variation) values were within the pre-defined limits of ≤ 5% at all concentrations with a limit of quantification of 25 ng/ml. Factors with potential to affect drug quantification measurements such as the matrix effects, volume of blood applied onto the collection card and effect of different sampling cards were investigated. The developed LC-HRMS method was applied to blood spots on sampling card taken from adult healthy volunteers previously administered a 50mg atenolol tablet and a DBS concentration-time profile was obtained for atenolol. Requiring only a micro volume (30 μl) blood sample for analysis, the developed DBS based assay has the potential to assess patient adherence to atenolol. Copyright © 2012 Elsevier B.V. All rights reserved.

The effect of selenium on spoil suitability as root zone material at Navajo Mine, New Mexico

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

Lane, J.R.; Buchanan, B.A.; Ramsey, T.C.

1995-09-01

The root zone suitability limits for spoil Se at Navajo Mine in northwest New Mexico are currently 0.8 ppm total Se and 0.15 ppm hot-water soluble Se. These criteria were largely developed by the Office of Surface Mining using data from the Northern Great Plains. Applying these values, approximately 23% of the spoil volume and 47% of the spoil area sampled at Navajo Mine from 1985 to December 1993 were determined to be unsuitable as root zone material. Secondary Se accumulator plants (Atriplex canescens) growing in both undisturbed and reclaimed areas were randomly sampled for selenium from 1985 to Decembermore » 1993. In most cases the undisturbed soil and reclaimed spoil at these plant sampling sites were sampled for both total and hot-water soluble Se. Selenium values for Atriplex canescens samples collected on the undisturbed sites averaged 0.64 ppm and ranged from 0.20 ppm to 2.5 ppm. Selenium values for the plants growing on spoil ranged from 0.02 ppm to 7.75 ppm and averaged 1.07 ppm. Total and hot-water Se values for spoil averaged 0.66 ppm and 0.06 ppm respectively, and ranged from 0.0 to 14.2 for total Se and 0.0 ppm to 0.72 ppm for hot-water soluble Se. The plant Se values were poorly correlated to both total and hot-water soluble Se values for both soil and spoil. Therefore, predicting suitable guidelines using normal regression techniques was ineffective. Based on background Se levels in native soils, and levels found on reclaimed areas with Atriplex canescens, it is suggested that a total Se level of 2.0 ppm and a hot-water soluble Se level of 0.25 ppm should be used to represent the suitability limits for Se at Navajo Mine. If these Se values are used, it is estimated that less than 1% of the spoil volume would be unsuitable. This volume of spoil seems to be a more accurate estimate of the amount of spoil with unsuitable levels of Se than the estimated 23% using the current guidelines.« less

Determination of picomolar concentrations of carbonyl compounds in natural waters, including seawater, by liquid chromatography

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

Kieber, R.; Mopper, K.

1990-10-01

Low molecular weight carbonyl compounds in natural waters were determined at picomolar to nanomolar levels by derivatization with 2,4-dinitrophenylhydrazine followed by liquid chromatography. The uniqueness of the method is attributed to the extremely low blanks obtained and the minimal sample preparation involved. The detection limit for direct injection of derivatized natural water samples is 0.5 nM for aldehydes and 5 nM for ketones with a precision of {approximately}7% RSD at the 30 nM level for aldehydes. The detection limit can be further lowered by using off-line cartridge enrichment in which derivatized natural water is passed through a C18 extraction cartridge.more » Recoveries for the enrichment method were 95-105% for a sample volume of 20 mL and for concentrations of carbonyl compounds in the 1-30 nM range. A field procedure for storage of derivatized sample extracts for extended periods is also presented. Applications of enrichment and sample storage techniques to marine and estuarine waters are presented.« less

[Determination of lead in edible salt with solid-phase extraction and GFAAS].

PubMed

Zhao, Xin; Zhou, Shuang; Ma, Lan; Yang, Dajin

2013-01-01

Establishing a method for determination of lead in salt with solid-phase extraction and GFAAS. Salt sample was diluted to a certain volume directly with ammonium acetate, then the sample solution was filtered through the solid phase extraction column which has been pre-activated. Lead ions were retained, and the sodium chloride matrix was removed. After elution, the collected lead ions was determined by graphite furnace atomic absorption spectrometry in 257.4 nm. This method can be used effectively to wipe off the sodium chloride in matrix. The limit of detection was 0.7 microg/kg and the limit of quantification was 2 microg/kg. Solid phase extraction technique can be used effectively to reduce the interference in matrix and improves the accuracy and reproducibility of detection.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of arsenic and selenium in water and sediment by graphite furnace atomic absorption spectrometry

USGS Publications Warehouse

Jones, Sandra R.; Garbarino, John R.

1999-01-01

Graphite furnace-atomic absorption spectrometry (GF-AAS) is a sensitive, precise, and accurate technique that can be used to determine arsenic and selenium in samples of water and sediment. The GF-AAS method has been developed to replace the hydride generation-atomic absorption spectrometry (HG-AAS) methods because the method detection limits are similar, bias and variability are comparable, and interferences are minimal. Advantages of the GF-AAS method include shorter sample preparation time, increased sample throughput from simultaneous multielement analysis, reduced amount of chemical waste, reduced sample volume requirements, increased linear concentration range, and the use of a more accurate digestion procedure. The linear concentration range for arsenic and selenium is 1 to 50 micrograms per liter in solution; the current method detection limit for arsenic in solution is 0.9 microgram per liter; the method detection limit for selenium in solution is 1 microgram per liter. This report describes results that were obtained using stop-flow and low-flow conditions during atomization. The bias and variability of the simultaneous determination of arsenic and selenium by GF-AAS under both conditions are supported with results from standard reference materials--water and sediment, real water samples, and spike recovery measurements. Arsenic and selenium results for all Standard Reference Water Samples analyzed were within one standard deviation of the most probable values. Long-term spike recoveries at 6.25, 25.0, 37.5 micrograms per liter in reagent-, ground-, and surface-water samples for arsenic averaged 103 plus or minus 2 percent using low-flow conditions and 104 plus or minus 4 percent using stop-flow conditions. Corresponding recoveries for selenium were 98 plus or minus 13 percent using low-flow conditions and 87 plus or minus 24 percent using stop-flow conditions. Spike recoveries at 25 micrograms per liter in 120 water samples ranged from 97 to 99 percent for arsenic and from 82 to 93 percent for selenium, depending on the flow conditions used. Statistical analysis of dissolved and whole-water recoverable analytical results for the same set of water samples indicated that there is no significant difference between the GF-AAS and HG-AAS methods. Interferences related to various chemical constituents were also identified. Although sulfate and chloride in association with various cations might interfere with the determination of arsenic and selenium by GF-AAS, the use of a magnesium nitrate/palladium matrix modifier and low-flow argon during atomization helped to minimize such interferences. When using stabilized temperature platform furnace conditions where stop flow is used during atomization, the addition of hydrogen (5 percent volume/volume) to the argon minimized chemical interferences. Nevertheless, stop flow during atomization was found to be less effective than low flow in reducing interference effects.

Quantification of 226Ra at environmental relevant levels in natural waters by ICP-MS: Optimization, validation and limitations of an extraction and preconcentration approach.

PubMed

Lagacé, François; Foucher, Delphine; Surette, Céline; Clarisse, Olivier

2017-05-15

Radium (Ra) at environmental relevant levels in natural waters was determined by ICP-MS after an off-line pre-concentration procedure. The latter consisted of Ra selective elution from potential interfering elements (i.e. other alkaline earth cations: Ba 2+ , Sr 2+ , Ca 2+ , Mg 2+ ) on a series of two different ion exchange resins (AG50W-X8 and Sr-resin). The overall analytical method was optimized according to the instrumental performance, the volume of water sample loaded on resins, and the sample salinity. Longer acquisition time (up to 150 s) was required to ensure stable measurement of Ra by ICP-MS at ultra trace level (1.0pgL -1 ). For a synthetic groundwater spiked with Ra at 10.0pgL -1 , the analytical procedure demonstrated efficient separation of the analyte from its potential interfering elements and a complete recovery, independent of the sample volume tested from 10 up to 100mL. For synthetic seawater spiked at a level of 10.0pgL -1 of Ra, the total load of salts on the two resins should not exceed 0.35g in order to ensure a complete separation and recovery of Ra. The method was validated on natural waters (i.e. groundwater, freshwater and seawater samples) spiked with Ra at different levels (0.0, 0.5, 1.0 and 5.0pgL -1 ). Absolute Ra detection limits were determined at 0.020pgL -1 (0.73mBqL -1 ) and 0.12pgL -1 (4.4mBqL -1 ) respectively for 60.0mL of freshwater sample and for 10.0mL of seawater. Copyright © 2017 Elsevier B.V. All rights reserved.

Formaldehyde: a comparative evaluation of four monitoring methods

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

Coyne, L.B.; Cook, R.E.; Mann, J.R.

1985-10-01

The performances of four formaldehyde monitoring devices were compared in a series of laboratory and field experiments. The devices evaluated included the DuPont C-60 formaldehyde badge, the SKC impregnated charcoal tube, an impinger/polarographic method and the MDA Lion formaldemeter. The major evaluation parameters included: concentration range, effects of humidity, sample storage, air velocity, accuracy, precision, interferences from methanol, styrene, 1,3-butadiene, sulfur dioxide and dimethylamine. Based on favorable performances in the laboratory and field, each device was useful for monitoring formaldehyde in the industrial work environment; however, these devices were not evaluated for residential exposure assessment. The impinger/polarographic method had amore » sensitivity of 0.06 ppm, based on a 20-liter air sample volume, and accurately determined the short-term excursion limit (STEL). It was useful for area monitoring but was not very practical for time-weighted average (TWA) personal monitoring measurements. The DuPont badge had a sensitivity of 2.8 ppm-hr and accurately and simply determined TWA exposures. It was not sensitive enough to measure STEL exposures, however, and positive interferences resulted if 1,3-butadiene was present. The SKC impregnated charcoal tube measured both TWA and STEL concentrations and had a sensitivity of 0.06 ppm based on a 25-liter air sample volume. Lightweight and simple to use, the MDA Lion formaldemeter had a sensitivity of 0.2 ppm. It had the advantage of giving an instantaneous reading in the field; however, it must be used with caution because it responded to many interferences. The method of choice depended on the type of sampling required, field conditions encountered during sampling and an understanding of the limitations of each monitoring device.« less

Simultaneous Determination of Procainamide and N-acetylprocainamide in Rat Plasma by Ultra-High-Pressure Liquid Chromatography Coupled with a Diode Array Detector and Its Application to a Pharmacokinetic Study in Rats.

PubMed

Balla, Anusha; Cho, Kwan Hyung; Kim, Yu Chul; Maeng, Han-Joo

2018-03-30

A simple, sensitive, and reliable reversed-phase, Ultra-High-Pressure Liquid Chromatography (UHPLC) coupled with a Diode Array Detector (DAD) method for the simultaneous determination of Procainamide (PA) and its major metabolite, N -acetylprocainamide (NAPA), in rat plasma was developed and validated. A simple deproteinization method with methanol was applied to the rat plasma samples, which were analyzed using UHPLC equipped with DAD at 280 nm, and a Synergi™ 4 µm polar, reversed-phase column using 1% acetic acid (pH 5.5) and methanol (76:24, v / v ) as eluent in isocratic mode at a flow rate 0.2 mL/min. The method showed good linearity ( r ² > 0.998) over the concentration range of 20-100,000 and 20-10,000 ng/mL for PA and NAPA, respectively. Intra- and inter-day accuracies ranged from 97.7 to 110.9%, and precision was <10.5% for PA and 99.7 to 109.2 and <10.5%, respectively, for NAPA. The lower limit of quantification was 20 ng/mL for both compounds. This is the first report of the UHPLC-DAD bioanalytical method for simultaneous measurement of PA and NAPA. The most obvious advantage of this method over previously reported HPLC methods is that it requires small sample and injection volumes, with a straightforward, one-step sample preparation. It overcomes the limitations of previous methods, which use large sample volume and complex sample preparation. The devised method was successfully applied to the quantification of PA and NAPA after an intravenous bolus administration of 10 mg/kg procainamide hydrochloride to rats.

Detection methods for human enteric viruses in representative foods.

PubMed

Leggitt, P R; Jaykus, L A

2000-12-01

Although viral foodborne disease is a significant problem, foods are rarely tested for viral contamination, and when done, testing is limited to shellfish commodities. In this work, we report a method to extract and detect human enteric viruses from alternative food commodities using an elution-concentration approach followed by detection using reverse transcription-polymerase chain reaction (RT-PCR). Fifty-gram lettuce or hamburger samples were artificially inoculated with poliovirus type 1 (PV1), hepatitis A virus (HAV), or the Norwalk virus and processed by the sequential steps of homogenization, filtration, Freon extraction (hamburger), and polyethylene glycol (PEG) precipitation. To reduce volumes further and remove RT-PCR inhibitors, a secondary PEG precipitation was necessary, resulting in an overall 10- to 20-fold sample size reduction from 50 g to 3 to 5 ml. Virus recoveries in secondary PEG concentrates ranged from 10 to 70% for PV1 and 2 to 4% for HAV as evaluated by mammalian cell culture infectivity assay. Total RNA from PEG concentrates was extracted to a small volume (30 to 40 microl) and subjected to RT-PCR amplification of viral RNA sequences. Detection limit studies indicated that viral RNA was consistently detected by RT-PCR at initial inoculum levels > or =102 PFU/50-g food sample for PV1 and > or =10(3) PFU/50-g food sample for HAV. In similar studies with the Norwalk virus, detection at inoculum levels > or =1.5 X 10(3) PCR-amplifiable units/50-g sample for both food products was possible. All RT-PCR amplicons were confirmed by subsequent Southern hybridization. The procedure reported represents progress toward the development of methods to detect human enteric viral contamination in foods other than shellfish.

Endocrine, electrolyte, and fluid volume changes associated with Apollo missions

NASA Technical Reports Server (NTRS)

Leach, C. S.; Alexander, W. C.; Johnson, P. C.

1975-01-01

The endocrine and metabolic results obtained before and after the Apollo missions and the results of the limited in-flight sampling are summarized and discussed. The studies were designed to evaluate the biochemical changes in the returning Apollo crewmembers, and the areas studied included balance of fluids and electrolytes, regulation of calcium metabolism, adaptation to the environment, and regulation of metabolic processes.

The role of ventromedial prefrontal cortex volume in the association of expressive suppression and externally oriented thinking.

PubMed

Li, Xu; Lu, Jiamei; Li, Bingbing; Li, Haijiang; Jin, Li; Qiu, Jiang

2017-11-01

Studies have suggested that expressive suppression (ES) is linked to externally oriented thinking (EOT) through the ventromedial prefrontal cortex (vmPFC), and there are gender differences in their association. The present structural magnetic resonance imaging study was to investigate the neural bases of ES and EOT and their association in females versus males in a Chinese college sample. A total of 142 participants (83 females) were enrolled, and they completed the ES subscale of the Emotion Regulation Questionnaire, 20-item Toronto Alexithymia Scale, and anatomical scanning. Voxel-based morphometry, region of interest, and whole brain analyses with peak-level significance (family-wise error corrected at p < .05) were conducted to investigate the association of gray matter volume (GMV) variations with ES and EOT. A bootstrapping analysis was conducted to examine the role of vmPFC volume in the ES-EOT association. The ES scores were positively linked to the GMV of the vmPFC in females and negatively related to right dorsolateral PFC volume in males. The EOT scores were positively correlated with the GMV of the vmPFC in females and supplementary motor area in males. Furthermore, vmPFC volume mediated the relationship between ES and EOT LIMITATIONS: The cross-sectional design limited causal conclusions. The vmPFC may be the only neural base of ES and EOT and their association. In addition, these results were sex-specific. Copyright © 2017 Elsevier B.V. All rights reserved.

System and method for preconcentrating, identifying, and quantifying chemical and biological substances

DOEpatents

Yu, Conrad M.; Koo, Jackson C.

2000-01-01

A system and method for preconcentrating, identifying, and quantifying chemical and biological substances is disclosed. An input valve directs a first volume of a sample gas to a surface acoustic wave (SAW) device. The SAW device preconcentrates and detects a mass of a substance within the sample gas. An output valve receives a second volume of the sample gas containing the preconcentrated substance from the SAW device and directs the second volume to a gas chromatograph (GC). The GC identifies the preconcentrated substance within the sample gas. A shunt valve exhausts a volume of the sample gas equal to the first volume minus the second volume away from the SAW device and the GC. The method of the present invention includes the steps of opening an input valve for passing a first volume of a sample gas to a SAW device; preconcentrating and detecting a mass of a substance within the sample gas using the SAW device; opening an output valve for passing a second volume of the sample gas containing the preconcentrated substance to a gas chromatograph (GC); and then identifying the preconcentrated substance within the sample gas using the GC.

Subcortical brain structure and suicidal behaviour in major depressive disorder: a meta-analysis from the ENIGMA-MDD working group

PubMed Central

Rentería, M E; Schmaal, L; Hibar, D P; Couvy-Duchesne, B; Strike, L T; Mills, N T; de Zubicaray, G I; McMahon, K L; Medland, S E; Gillespie, N A; Hatton, S N; Lagopoulos, J; Veltman, D J; van der Wee, N; van Erp, T G M; Wittfeld, K; Grabe, H J; Block, A; Hegenscheid, K; Völzke, H; Veer, I M; Walter, H; Schnell, K; Schramm, E; Normann, C; Schoepf, D; Konrad, C; Zurowski, B; Godlewska, B R; Cowen, P J; Penninx, B W J H; Jahanshad, N; Thompson, P M; Wright, M J; Martin, N G; Christensen, H; Hickie, I B

2017-01-01

The aetiology of suicidal behaviour is complex, and knowledge about its neurobiological mechanisms is limited. Neuroimaging methods provide a noninvasive approach to explore the neural correlates of suicide vulnerability in vivo. The ENIGMA-MDD Working Group is an international collaboration evaluating neuroimaging and clinical data from thousands of individuals collected by research groups from around the world. Here we present analyses in a subset sample (n=3097) for whom suicidality data were available. Prevalence of suicidal symptoms among major depressive disorder (MDD) cases ranged between 29 and 69% across cohorts. We compared mean subcortical grey matter volumes, lateral ventricle volumes and total intracranial volume (ICV) in MDD patients with suicidal symptoms (N=451) vs healthy controls (N=1996) or MDD patients with no suicidal symptoms (N=650). MDD patients reporting suicidal plans or attempts showed a smaller ICV (P=4.12 × 10−3) or a 2.87% smaller volume compared with controls (Cohen’s d=−0.284). In addition, we observed a nonsignificant trend in which MDD cases with suicidal symptoms had smaller subcortical volumes and larger ventricular volumes compared with controls. Finally, no significant differences (P=0.28–0.97) were found between MDD patients with and those without suicidal symptoms for any of the brain volume measures. This is by far the largest neuroimaging meta-analysis of suicidal behaviour in MDD to date. Our results did not replicate previous reports of association between subcortical brain structure and suicidality and highlight the need for collecting better-powered imaging samples and using improved suicidality assessment instruments. PMID:28463239

Analysis of poly-beta-hydroxybutyrate in environmental samples by GC-MS/MS.

PubMed

Elhottová, D; Tríska, J; Petersen, S O; Santrůcková, H

2000-05-01

Application of gas chromatography-mass spectrometry (GC-MS) can significantly improve trace analyses of compounds in complex matrices from natural environments compared to gas chromatography only. A GC-MS/MS technique for determination of poly-beta-hydroxybutyrate (PHB), a bacterial storage compound, has been developed and used for analysis of two soils stored for up to 319 d, fresh samples of sewage sludge, as well as a pure culture of Bacillus megaterium. Specific derivatization of beta-hydroxybutyrate (3-OH C4:0) PHB monomer units by N-tert-butyl-dimethylsilyl-N-methyltrifluoracetamide (MTBSTFA) improved chromatographic and mass spectrometric properties of the analyte. The diagnostic fragmentation scheme of the derivates tert-butyldimethylsilyl ester and ether of beta-hydroxybutyric acid (MTBSTFA-HB) essential for the PHB identification was shown. The ion trap MS was used, therefore the scan gave the best sensitivity and with MS/MS the noise decreased, so the S/N was better and also with second fragmentation the amount of ions increased compared to SIM. The detection limit for MTBSTFA-HB by GC-MS/MS was about 10(-13) g microL(-1) of injected volume, while by GC (FID) and GC-MS (scan) it was around 10(-10) g microL(-1) of injected volume. Sensitivity of GC-MS/MS measurements of PHB in arable soil and activated sludge samples was down to 10 pg of PHB g(-1) dry matter. Comparison of MTBSTFA-HB detection in natural soil sample by GC (FID), GC-MS (scan) and by GC-MS/MS demonstrated potentials and limitations of the individual measurement techniques.

Additive gene-environment effects on hippocampal structure in healthy humans.

PubMed

Rabl, Ulrich; Meyer, Bernhard M; Diers, Kersten; Bartova, Lucie; Berger, Andreas; Mandorfer, Dominik; Popovic, Ana; Scharinger, Christian; Huemer, Julia; Kalcher, Klaudius; Pail, Gerald; Haslacher, Helmuth; Perkmann, Thomas; Windischberger, Christian; Brocke, Burkhard; Sitte, Harald H; Pollak, Daniela D; Dreher, Jean-Claude; Kasper, Siegfried; Praschak-Rieder, Nicole; Moser, Ewald; Esterbauer, Harald; Pezawas, Lukas

2014-07-23

Hippocampal volume loss has been related to chronic stress as well as genetic factors. Although genetic and environmental variables affecting hippocampal volume have extensively been studied and related to mental illness, limited evidence is available with respect to G × E interactions on hippocampal volume. The present MRI study investigated interaction effects on hippocampal volume between three well-studied functional genetic variants (COMT Val158Met, BDNF Val66Met, 5-HTTLPR) associated with hippocampal volume and a measure of environmental adversity (life events questionnaire) in a large sample of healthy humans (n = 153). All three variants showed significant interactions with environmental adversity with respect to hippocampal volume. Observed effects were additive by nature and driven by both recent as well as early life events. A consecutive analysis of hippocampal subfields revealed a spatially distinct profile for each genetic variant suggesting a specific role of 5-HTTLPR for the subiculum, BDNF Val66Met for CA4/dentate gyrus, and COMT Val158Met for CA2/3 volume changes. The present study underscores the importance of G × E interactions as determinants of hippocampal volume, which is crucial for the neurobiological understanding of stress-related conditions, such as mood disorders or post-traumatic stress disorder (PTSD). Copyright © 2014 the authors 0270-6474/14/349917-10$15.00/0.

Coupling nanoliter high-performance liquid chromatography to inductively coupled plasma mass spectrometry for arsenic speciation.

PubMed

Cheng, Heyong; Shen, Lihuan; Liu, Jinhua; Xu, Zigang; Wang, Yuanchao

2018-04-01

Nanoliter high-performance liquid chromatography shows low consumption of solvents and samples, offering one of the best choices for arsenic speciation in precious samples in combination with inuctively coupled plasma mass spectrometry. A systematic investigation on coupling nanoliter high-performance liquid chromatography to inductively coupled plasma mass spectrometry from instrument design to injected sample volume and mobile phase was performed in this study. Nanoflow mobile phase was delivered by flow splitting using a conventional high-pressure pump with reuse of mobile phase waste. Dead volume was minimized to 60 nL for the sheathless interface based on the previously developed nanonebulizer. Capillary columns for nanoliter high-performance liquid chromatography were found to be sensitive to sample loading volume. An apparent difference was also found between the mobile phases for nanoliter and conventional high-performance liquid chromatography. Baseline separation of arsenite, arsenate, monomethylarsenic, and dimethylarsenic was achieved within 11 min on a 15 cm C 18 capillary column and within 12 min on a 25 cm strong anion exchange column. Detection limits of 0.9-1.8 μg/L were obtained with precisions variable in the range of 1.6-4.2%. A good agreement between determined and certified values of a certified reference material of human urine (GBW 09115) validated its accuracy along with good recoveries (87-102%). © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

NanoDrop Microvolume Quantitation of Nucleic Acids

PubMed Central

Desjardins, Philippe; Conklin, Deborah

2010-01-01

Biomolecular assays are continually being developed that use progressively smaller amounts of material, often precluding the use of conventional cuvette-based instruments for nucleic acid quantitation for those that can perform microvolume quantitation. The NanoDrop microvolume sample retention system (Thermo Scientific NanoDrop Products) functions by combining fiber optic technology and natural surface tension properties to capture and retain minute amounts of sample independent of traditional containment apparatus such as cuvettes or capillaries. Furthermore, the system employs shorter path lengths, which result in a broad range of nucleic acid concentration measurements, essentially eliminating the need to perform dilutions. Reducing the volume of sample required for spectroscopic analysis also facilitates the inclusion of additional quality control steps throughout many molecular workflows, increasing efficiency and ultimately leading to greater confidence in downstream results. The need for high-sensitivity fluorescent analysis of limited mass has also emerged with recent experimental advances. Using the same microvolume sample retention technology, fluorescent measurements may be performed with 2 μL of material, allowing fluorescent assays volume requirements to be significantly reduced. Such microreactions of 10 μL or less are now possible using a dedicated microvolume fluorospectrometer. Two microvolume nucleic acid quantitation protocols will be demonstrated that use integrated sample retention systems as practical alternatives to traditional cuvette-based protocols. First, a direct A260 absorbance method using a microvolume spectrophotometer is described. This is followed by a demonstration of a fluorescence-based method that enables reduced-volume fluorescence reactions with a microvolume fluorospectrometer. These novel techniques enable the assessment of nucleic acid concentrations ranging from 1 pg/ μL to 15,000 ng/ μL with minimal consumption of sample. PMID:21189466

Simple hollow fiber renewal liquid membrane extraction method for pre-concentration of Cd(II) in environmental samples and detection by flame atomic absorption spectrometry.

PubMed

Carletto, Jeferson Schneider; Luciano, Raquel Medeiros; Bedendo, Gizelle Cristina; Carasek, Eduardo

2009-04-06

A hollow fiber renewal liquid membrane (HFRLM) extraction method to determine cadmium (II) in water samples using Flame Atomic Absorption Spectrometry (FAAS) was developed. Ammonium O,O-diethyl dithiophosphate (DDTP) was used to complex cadmium (II) in an acid medium to obtain a neutral hydrophobic complex (ML(2)). The organic solvent introduced to the sample extracts this complex from the aqueous solution and carries it over the poly(dimethylsiloxane) (PDMS) membrane, that had their walls previously filled with the same organic solvent. The organic solvent is solubilized inside the PDMS membrane, leading to a homogeneous phase. The complex strips the lumen of the membrane where, at higher pH, the complex Cd-DDTP is broken down and cadmium (II) is released into the stripping phase. EDTA was used to complex the cadmium (II), helping to trap the analyte in the stripping phase. A multivariate procedure was used to optimize the studied variables. The optimized variables were: sample (donor phase) pH 3.25, DDTP concentration 0.05% (m/v), stripping (acceptor phase) pH 8.75, EDTA concentration 1.5x10(-2) mol L(-1), extraction temperature 40 degrees C, extraction time 40 min, a solvent mixture N-butyl acetate and hexane (60/40%, v/v) with a volume of 100 microL, and addition of ammonium sulfate to saturate the sample. The sample volume used was 20 mL and the stripping volume was 165 microL. The analyte enrichment factor was 120, limit of detection (LOD) 1.3 microg L(-1), relative standard deviation (RSD) 5.5% and the working linear range 2-30 microg L(-1).

Ultrasound-assisted dispersive liquid-liquid microextraction for the determination of synthetic musk fragrances in aqueous matrices by gas chromatography-mass spectrometry.

PubMed

Homem, Vera; Alves, Alice; Alves, Arminda; Santos, Lúcia

2016-01-01

A rapid and simple method for the simultaneous determination of twelve synthetic musks in water samples, using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with gas chromatography-mass spectrometry (GC-MS) was successfully developed. The influence of seven factors (volume of the extraction solvent and disperser solvent, sample volume, extraction time, ionic strength, type of extraction and disperser solvent) affecting the UA-DLLME extraction efficiency was investigated using a screening design. The significant factors were selected and optimised employing a central composite design: 80 μL of chloroform, 880 μL of acetonitrile, 6 mL of sample volume, 3.5% (wt) of NaCl and 2 min of extraction time. Under the optimised conditions, this methodology was successfully validated for the analysis of 12 synthetic musk compounds in different aqueous samples (tap, sea and river water, effluent and influent wastewater). The proposed method showed enrichment factors between 101 and 115 depending on the analyte, limits of detection in the range of 0.004-54 ng L(-1) and good repeatability (most relative standard deviation values below 10%). No significant matrix effects were found, since recoveries ranged between 71% and 118%. Finally, the method was satisfactorily applied to the analysis of five different aqueous samples. Results demonstrated the existence of a larger amount of synthetic musks in wastewaters than in other water samples (average concentrations of 2800 ng L(-1) in influent and 850 ng L(-1) in effluent). Galaxolide, tonalide and exaltolide were the compounds most detected. Copyright © 2015 Elsevier B.V. All rights reserved.

The SDSS-IV MaNGA Sample: Design, Optimization, and Usage Considerations

NASA Astrophysics Data System (ADS)

Wake, David A.; Bundy, Kevin; Diamond-Stanic, Aleksandar M.; Yan, Renbin; Blanton, Michael R.; Bershady, Matthew A.; Sánchez-Gallego, José R.; Drory, Niv; Jones, Amy; Kauffmann, Guinevere; Law, David R.; Li, Cheng; MacDonald, Nicholas; Masters, Karen; Thomas, Daniel; Tinker, Jeremy; Weijmans, Anne-Marie; Brownstein, Joel R.

2017-09-01

We describe the sample design for the SDSS-IV MaNGA survey and present the final properties of the main samples along with important considerations for using these samples for science. Our target selection criteria were developed while simultaneously optimizing the size distribution of the MaNGA integral field units (IFUs), the IFU allocation strategy, and the target density to produce a survey defined in terms of maximizing signal-to-noise ratio, spatial resolution, and sample size. Our selection strategy makes use of redshift limits that only depend on I-band absolute magnitude (M I ), or, for a small subset of our sample, M I and color (NUV - I). Such a strategy ensures that all galaxies span the same range in angular size irrespective of luminosity and are therefore covered evenly by the adopted range of IFU sizes. We define three samples: the Primary and Secondary samples are selected to have a flat number density with respect to M I and are targeted to have spectroscopic coverage to 1.5 and 2.5 effective radii (R e ), respectively. The Color-Enhanced supplement increases the number of galaxies in the low-density regions of color-magnitude space by extending the redshift limits of the Primary sample in the appropriate color bins. The samples cover the stellar mass range 5× {10}8≤slant {M}* ≤slant 3× {10}11 {M}⊙ {h}-2 and are sampled at median physical resolutions of 1.37 and 2.5 kpc for the Primary and Secondary samples, respectively. We provide weights that will statistically correct for our luminosity and color-dependent selection function and IFU allocation strategy, thus correcting the observed sample to a volume-limited sample.

Application of an ETV-ICP system for the determination of elements in human hair*1

NASA Astrophysics Data System (ADS)

Plantikow-Voβgätter, F.; Denkhaus, E.

1996-01-01

When determining element contents in hair samples without sample digestion it is necessary to analyze large sample volumes in order to minimize problems of inhomogeneity of biological sample materials. Therefore an electrothermal vaporization system (ETV) is used for solid sample introduction into an inductively coupled plasma (ICP) for the determination of matrix and trace elements in hair. This paper concentrates on the instrumental aspects without time consuming sample preparation. The results obtained for optimization tests, ETV operating parameters and ICP operating parameters, are shown and discussed. Standard additions are used for calibration for the determination of Zn, Mg, and Mn in human hair. Studies including reproducibility and detection limits for chosen elements have been carried out on certified reference materials (CRMs). The determination of reproducibility (relative standard deviation (RSD) of n = 10) and detection limits (DLs) of Zn (RSD < 8.5%, DL < 0.8 μ g -1), Mn (RSD < 14.1%, DL < 0.3 μ g -1), and Mg (RSD < 7.4%, DL < 6.6 μ g -1) are satisfactory. The concentration values found show good agreement with the corresponding certified values. Further sample preparation steps, including hair sampling, washing procedure and homogenization for hair, relating to measurements of real hair samples are described.

Reconfirmation of frit 803 based on the January 2016 sludge batch 9 reprojection

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

Johnson, F.; Edwards, T.

2016-02-10

On January 11, 2016, Savannah River Remediation (SRR) provided the Savannah River National Laboratory (SRNL) with a Sludge Batch 9 (SB9) reprojection that was developed from the analyzed composition of a Tank 51 sample. This sample was collected after field washing had been completed in Tank 51 to support the alternate reductant task. Based on this reprojection, Frit 803 is still a viable option for the processing of SB9 under sludge-only operations and coupled (Actinide Removal Process (ARP) product with and without monosodium titanate (MST)) operations. The maximum projected volumes of ARP product that can be transferred from the Precipitatemore » Reactor Feed Tank (PRFT) per Sludge Receipt and Adjustment Tank (SRAT) batch and the resulting Na 2O concentrations in the SRAT for coupled operations were determined. The Na 2O concentrations in the SRAT resulting from the maximum projected ARP product transfer volumes are consistent with those from the previous assessments that were based on the August 2015 projections. Regardless of the presence or absence of MST in the ARP product, the contribution of Na 2O to the resulting glass will be similar at the same waste loading (WL). These projected volumes of ARP product are not anticipated to be an issue for SB9. The actual transfer volumes from the PRFT to the SRAT are determined based upon the analyzed Na 2O concentrations in the PRFT samples, which has resulted in larger transfer volumes than those allowed by the projections for Sludge Batch 8 (SB8). An operating window of 32-40% WL around the nominal WL of 36% is achievable for both sludge-only and coupled operations; however, each of the glass systems studied does become limited by waste form affecting constraints (durability) at higher volumes of ARP product and WLs of 41-42%.« less

CARMENES input catalogue of M dwarfs. II. High-resolution imaging with FastCam

NASA Astrophysics Data System (ADS)

Cortés-Contreras, M.; Béjar, V. J. S.; Caballero, J. A.; Gauza, B.; Montes, D.; Alonso-Floriano, F. J.; Jeffers, S. V.; Morales, J. C.; Reiners, A.; Ribas, I.; Schöfer, P.; Quirrenbach, A.; Amado, P. J.; Mundt, R.; Seifert, W.

2017-01-01

Aims: We search for low-mass companions of M dwarfs and characterize their multiplicity fraction with the purpose of helping in the selection of the most appropriate targets for the CARMENES exoplanet survey. Methods: We obtained high-resolution images in the I band with the lucky imaging instrument FastCam at the 1.5 m Telescopio Carlos Sánchez for 490 mid- to late-M dwarfs. For all the detected binaries, we measured angular separations, position angles, and magnitude differences in the I band. We also calculated the masses of each individual component and estimated orbital periods, using the available magnitude and colour relations for M dwarfs and our own MJ-spectral type and mass-MI relations. To avoid biases in our sample selection, we built a volume-limited sample of M0.0-M5.0 dwarfs that is complete up to 86% within 14 pc. Results: From the 490 observed stars, we detected 80 companions in 76 systems, of which 30 are new discoveries. Another six companion candidates require additional astrometry to confirm physical binding. The multiplicity fraction in our observed sample is 16.7 ± 2.0%. The bias-corrected multiplicity fraction in our volume-limited sample is 19.5 ± 2.3% for angular separations of 0.2 to 5.0 arcsec (1.4-65.6 au), with a peak in the distribution of the projected physical separations at 2.5-7.5 au. For M0.0-M3.5 V primaries, our search is sensitive to mass ratios higher than 0.3 and there is a higher density of pairs with mass ratios over 0.8 compared to those at lower mass ratios. Binaries with projected physical separations shorter than 50 au also tend to be of equal mass. For 26 of our systems, we estimated orbital periods shorter than 50 a, 10 of which are presented here for the first time. We measured variations in angular separation and position angle that are due to orbital motions in 17 of these systems. The contribution of binaries and multiples with angular separations shorter than 0.2 arcsec, longer than 5.0 arcsec, and of spectroscopic binaries identified from previous searches, although not complete, may increase the multiplicity fraction of M dwarfs in our volume-limited sample to at least 36%. Tables A.1-A.6 are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A47

Numerical evaluation of the limit of concentration of colloidal samples for their study with digital lensless holographic microscopy.

PubMed

Restrepo, John F; Garcia-Sucerquia, Jorge

2013-01-01

The number of colloidal particles per unit of volume that can be imaged correctly with digital lensless holographic microscopy (DLHM) is determined numerically. Typical in-line DLHM holograms with controlled concentration are modeled and reconstructed numerically. By quantifying the ratio of the retrieved particles from the reconstructed hologram to the number of the seeding particles in the modeled intensity, the limit of concentration of the colloidal suspensions up to which DLHM can operate successfully is found numerically. A new shadow density parameter for spherical illumination is defined. The limit of performance of DLHM is determined from a graph of the shadow density versus the efficiency of the microscope.

Salting-out assisted liquid-liquid extraction combined with capillary HPLC for the determination of sulfonylurea herbicides in environmental water and banana juice samples.

PubMed

Gure, Abera; Lara, Francisco J; Moreno-González, David; Megersa, Negussie; del Olmo-Iruela, Monsalud; García-Campaña, Ana M

2014-09-01

A salting-out assisted liquid-liquid extraction (SALLE) combined with capillary high performance liquid chromatography with diode array detector (capillary HPLC-DAD) was proposed for extraction and determination of residues of nine sulfonylurea herbicides (SUHs) in environmental water and banana juice samples. Various parameters affecting the extraction process such as the type and volume of the organic solvent, sample volume, type and amount of salt, pH of the sample and vortex time were optimized. Under optimum conditions, matrix matched calibration curves were established using river water and banana juice samples. Good linear relationships as well as low limits of detection, LODs (0.4-1.3 and 3-13 µg/L) and quantification, LOQs (1.3-4.3 and 10-43 µg/L) were obtained in water and banana juice samples, respectively. The precision (intra- and inter-day) of the peak areas expressed as relative standard deviations (%, RSD), at two concentration levels were below 10 % in both matrices. Recoveries obtained from spiked environmental waters (river water and groundwater) and banana juice samples, at two concentration levels, ranged from 72 to 115%. The results of the analysis revealed that the proposed SALLE-capillary HPLC method is simple, rapid, cheap and environmentally friendly, being successfully applicable for the determination of SUH residues in waters and banana juices. Copyright © 2014 Elsevier B.V. All rights reserved.

Determination of mercury by multisyringe flow injection system with cold-vapor atomic absorption spectrometry.

PubMed

Leal, L O; Elsholz, O; Forteza, R; Cerdà, V

2006-07-28

A new software-controlled time-based multisyringe flow injection system for mercury determination by cold-vapor atomic absorption spectrometry is proposed. Precise known volumes of sample, reducing agent (1.1% SnCl2 in 3% HCl) and carrier (3% HCl) are dispensed into a gas-liquid separation cell with a multisyringe burette coupled with one three-way solenoid valve. An argon flow delivers the reduced mercury to the spectrometer. The optimization of the system was carried out testing reaction coils and gas-liquid separators of different design as well as changing parameters, such as sample and reagents volumes, reagent concentrations and carrier gas flow rate, among others. The analytical curves were obtained within the range 50-5000 ng L(-1). The detection limit (3sigma(b)/S) achieved is 5 ng L(-1). The relative standard deviation (R.S.D.) was 1.4%, evaluated from 16 successive injections of 250 ng L(-1) Hg standard solution. The injection and sample throughput per hour were 44 and 11, respectively. This technique was validated by means of solid and water reference materials with good agreement with the certified values and was successfully applied to fish samples.

Biomonitoring of perfluorinated compounds in a drop of blood.

PubMed

Mao, Pan; Wang, Daojing

2015-06-02

Biomonitoring of pollutants and their metabolites and derivatives using biofluids provides new opportunities for spatiotemporal assessment of human risks to environmental exposures. Perfluorinated compounds (PFCs) have been used widely in industry and pose significant environmental concerns due to their stability and bioaccumulation in humans and animals. However, current methods for extraction and measurement of PFCs require relatively large volumes (over one hundred microliters) of blood samples, and therefore, are not suitable for frequent blood sampling and longitudinal biomonitoring of PFCs. We have developed a new microassay, enabled by our silicon microfluidic chip platform, for analyzing PFCs in small volumes (less than five microliters) of blood. Our assay integrates on-chip solid-phase extraction (SPE) with online nanoflow liquid chromatography-electrospray ionization-mass spectrometry (nanoLC-ESI-MS) detection. We demonstrated high sample recovery, excellent interday and intraday accuracy and precision, and a limit of detection down to 50 femtogram of PFCs, in one microliter of human plasma. We validated our assay performance using pooled human plasma and NIST SRM 1950 samples. Our microfluidic chip-based assay may enable frequent longitudinal biomonitoring of PFCs and other environmental toxins using a finger prick of blood, thereby providing new insights into their bioaccumulation, bioavailability, and toxicity.

N-point correlation functions in the CfA and SSRS redshift distribution of galaxies

NASA Technical Reports Server (NTRS)

Gaztanaga, Enrique

1992-01-01

Using counts in cells, we estimate the volume-average N-point galaxy correlation functions for N = 2, 3, and 4, in redshift samples of the CfA and SSRS catalogs. Volume-limited samples of different sizes are used to study the uncertainties at different scales, the shot noise, and the problem with the boundaries. The hierarchical constants S3 and S4 agree well in all samples in CfA and SSRS, with average S3 = 194 +/- 0.07 and S4 = 4.56 +/- 0.53. We compare these results with estimates obtained from angular catalogs and recent analysis over IRAS samples. The amplitudes SJ seem larger in real space than in redshift space, although the values from the angular analysis correspond to smaller scales, where we might expect larger nonperturbative effects. It is also found that S3 and S4 are smaller for IRAS than for optical galaxies. This, together with the fact that IRAS galaxies have smaller amplitude for the above correlation functions, indicates that the density fluctuations of IRAS galaxies cannot be simply proportional to the density fluctuations of optical galaxies, i.e., biasing has to be nonlinear between them.

Miniaturized blood sampling techniques to benefit reduction in mice and refinement in nonhuman primates: applications to bioanalysis in toxicity studies with antibody-drug conjugates.

PubMed

Caron, Alexis; Lelong, Christine; Pascual, Marie-Hélène; Benning, Véronique

2015-03-01

Minimizing the number of animals in regulatory toxicity studies while achieving study objectives to support the development of future medicines contributes to good scientific and ethical practices. Recent advances in technology have enabled the development of miniaturized blood sampling methods (including microsampling and dried blood spots) applicable to toxicokinetic determinations of small-molecule drugs. Implementation of miniaturized blood sampling methods in the context of biotherapeutic drugs is desirable because a limitation to this type of medicine remains the total blood volume needed from a single animal to support toxicokinetic determinations of several analytes (parent drug, metabolites[s], antidrug antibodies, and so forth). We describe here the technical details, applicability, and relevance of new miniaturized blood sampling procedures in mice and nonhuman primates in the context of the toxicologic evaluation of biotherapeutic drugs consisting of antibody-drug conjugates developed for oncology indications. These examples illustrate how these techniques can benefit the reduction of animal usage in mouse toxicity studies by decreasing the number of animals dedicated to toxicokinetic determinations and the refinement of practices in nonhuman primate toxicity studies by decreasing the blood volume repeatedly drawn for toxicokinetic determinations.

Miniaturized Blood Sampling Techniques to Benefit Reduction in Mice and Refinement in Nonhuman Primates: Applications to Bioanalysis in Toxicity Studies with Antibody–Drug Conjugates

PubMed Central

Caron, Alexis; Lelong, Christine; Pascual, Marie-Hélène; Benning, Véronique

2015-01-01

Minimizing the number of animals in regulatory toxicity studies while achieving study objectives to support the development of future medicines contributes to good scientific and ethical practices. Recent advances in technology have enabled the development of miniaturized blood sampling methods (including microsampling and dried blood spots) applicable to toxicokinetic determinations of small-molecule drugs. Implementation of miniaturized blood sampling methods in the context of biotherapeutic drugs is desirable because a limitation to this type of medicine remains the total blood volume needed from a single animal to support toxicokinetic determinations of several analytes (parent drug, metabolites[s], antidrug antibodies, and so forth). We describe here the technical details, applicability, and relevance of new miniaturized blood sampling procedures in mice and nonhuman primates in the context of the toxicologic evaluation of biotherapeutic drugs consisting of antibody–drug conjugates developed for oncology indications. These examples illustrate how these techniques can benefit the reduction of animal usage in mouse toxicity studies by decreasing the number of animals dedicated to toxicokinetic determinations and the refinement of practices in nonhuman primate toxicity studies by decreasing the blood volume repeatedly drawn for toxicokinetic determinations. PMID:25836960

Combination of micelle collapse and field-amplified sample stacking in capillary electrophoresis for determination of trimethoprim and sulfamethoxazole in animal-originated foodstuffs.

PubMed

Liu, Lihong; Wan, Qian; Xu, Xiaoying; Duan, Shunshan; Yang, Chunli

2017-03-15

An on-line preconcentration method combining micelle to solvent stacking (MSS) with field-amplified sample stacking (FASS) was employed for the analysis of trimethoprim (TMP) and sulfamethoxazole (SMZ) by capillary zone electrophoresis (CZE). The optimized experimental conditions were as followings: (1) sample matrix, 10.0mM SDS-5% (v/v) methanol; (2) trapping solution (TS), 35mM H 3 PO 4 -60% acetonitrile (CH 3 CN); (3) running buffer, 30mM Na 2 HPO 4 (pH=7.3); (4) sample solution volume, 168nL; TS volume, 168nL; and (5) 9kV voltage, 214nm UV detection. Under the optimized conditions, the limits of detection (LODs) for SMZ and TMP were 7.7 and 8.5ng/mL, and they were 301 and 329 times better compared to a typical injection, respectively. The contents of TMP and SMZ in animal foodstuffs such as dairy products, eggs and honey were analyzed, too. Recoveries of 80-104% were acquired with relative standard deviations of 0.5-5.4%. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cryogenic Liquid Sample Acquisition System for Remote Space Applications

NASA Technical Reports Server (NTRS)

Mahaffy, Paul; Trainer, Melissa; Wegel, Don; Hawk, Douglas; Melek, Tony; Johnson, Christopher; Amato, Michael; Galloway, John

2013-01-01

There is a need to acquire autonomously cryogenic hydrocarbon liquid sample from remote planetary locations such as the lakes of Titan for instruments such as mass spectrometers. There are several problems that had to be solved relative to collecting the right amount of cryogenic liquid sample into a warmer spacecraft, such as not allowing the sample to boil off or fractionate too early; controlling the intermediate and final pressures within carefully designed volumes; designing for various particulates and viscosities; designing to thermal, mass, and power-limited spacecraft interfaces; and reducing risk. Prior art inlets for similar instruments in spaceflight were designed primarily for atmospheric gas sampling and are not useful for this front-end application. These cryogenic liquid sample acquisition system designs for remote space applications allow for remote, autonomous, controlled sample collections of a range of challenging cryogenic sample types. The design can control the size of the sample, prevent fractionation, control pressures at various stages, and allow for various liquid sample levels. It is capable of collecting repeated samples autonomously in difficult lowtemperature conditions often found in planetary missions. It is capable of collecting samples for use by instruments from difficult sample types such as cryogenic hydrocarbon (methane, ethane, and propane) mixtures with solid particulates such as found on Titan. The design with a warm actuated valve is compatible with various spacecraft thermal and structural interfaces. The design uses controlled volumes, heaters, inlet and vent tubes, a cryogenic valve seat, inlet screens, temperature and cryogenic liquid sensors, seals, and vents to accomplish its task.

Site Environmental Report for 2009, Volume 2

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

Xu, Suying

2010-08-19

Volume II of the Site Environmental Report for 2009 is provided by Ernest Orlando Lawrence Berkeley National Laboratory as a supplemental appendix to Volume I, which contains the body of the report. Volume II contains the environmental monitoring and sampling data used to generate summary results of routine and nonroutine sampling at the Laboratory, except for groundwater sampling data, which may be found in the reports referred to in Chapter 4 of Volume I. The results from sample collections are more comprehensive in Volume II than in Volume I: for completeness, all results from sample collections that began or endedmore » in calendar year (CY) 2009 are included in this volume. However, the samples representing CY 2008 data have not been used in the summary results that are reported in Volume I. (For example, although ambient air samples collected on January 6, 2009, are presented in Volume II, they represent December 2008 data and are not included in Table 4-2 in Volume I.) When appropriate, sampling results are reported in both conventional and International System (SI) units. For some results, the rounding procedure used in data reporting may result in apparent differences between the numbers reported in SI and conventional units. (For example, stack air tritium results reported as < 1.5 Bq/m3 are shown variously as < 39 and < 41 pCi/m3. Both of these results are rounded correctly to two significant digits.)« less

Installation Restoration Program. Remedial Investigation Report. Minnesota Air National Guard Base Duluth International Airport, Duluth, Minnesota. Volume 4

DTIC Science & Technology

1990-01-01

DATA job No.: OROOl Calibration Date: 8-19-88 Instrument I.D.: Perkin Elmer 257 Client: ES Oak Ridge Grating Infrared Spectrophotometer Attn: Bill...ilh (2 2 ___ UPPER I LIMIT__ I/ LOWER I0 I 9 I LIMIT_ I -00 I o0 WW2 1EPA SAMPLE] I No. I I I---. ...I I .. .. - ==== =---I 01- J ox.9oJ wqIJ~%o S... Infrared Spectrophotometer Attn: Bill Hayden Address: 710 S. Illinois Avenue Unit: mg/L Suite F-103 Date Reported: 11-09-88 Oak Ridge, Tn. 37830 R

Geometrical optics, electrostatics, and nanophotonic resonances in absorbing nanowire arrays.

PubMed

Anttu, Nicklas

2013-03-01

Semiconductor nanowire arrays have shown promise for next-generation photovoltaics and photodetection, but enhanced understanding of the light-nanowire interaction is still needed. Here, we study theoretically the absorption of light in an array of vertical InP nanowires by moving continuously, first from the electrostatic limit to the nanophotonic regime and then to the geometrical optics limit. We show how the absorption per volume of semiconductor material in the array can be varied by a factor of 200, ranging from 10 times weaker to 20 times stronger than in a bulk semiconductor sample.

Relative toxicity of pyrolysis products of some foams and fabrics

NASA Technical Reports Server (NTRS)

Hilado, C. J.

1976-01-01

A limited number of foams and fabrics was evaluated in the course of developing test procedures for determining the relative toxicity of materials. The principal variable studied, heating rate, did not affect the relative ranking of the materials tested. Two pyrolysis test procedures using the same basic approach but employing different sample weights, chamber volumes, laboratory animals, heating rates, and upper temperature limits, resulted in identical rankings of relative toxicity. The data obtained show that modification of conventional flexible polyurethane foams with flame retardants to comply with California upholstered furniture flammability regulations seems to consistently reduce toxicity under pyrolysis conditions.

Paper-based Devices for Isolation and Characterization of Extracellular Vesicles

PubMed Central

Chen, Chihchen; Lin, Bo-Ren; Hsu, Min-Yen; Cheng, Chao-Min

2015-01-01

Extracellular vesicles (EVs), membranous particles released from various types of cells, hold a great potential for clinical applications. They contain nucleic acid and protein cargo and are increasingly recognized as a means of intercellular communication utilized by both eukaryote and prokaryote cells. However, due to their small size, current protocols for isolation of EVs are often time consuming, cumbersome, and require large sample volumes and expensive equipment, such as an ultracentrifuge. To address these limitations, we developed a paper-based immunoaffinity platform for separating subgroups of EVs that is easy, efficient, and requires sample volumes as low as 10 μl. Biological samples can be pipetted directly onto paper test zones that have been chemically modified with capture molecules that have high affinity to specific EV surface markers. We validate the assay by using scanning electron microscopy (SEM), paper-based enzyme-linked immunosorbent assays (P-ELISA), and transcriptome analysis. These paper-based devices will enable the study of EVs in the clinic and the research setting to help advance our understanding of EV functions in health and disease. PMID:25867034

Evaluation of environmental levels of aromatic hydrocarbons in gasoline service stations by gas chromatography.

PubMed

Periago, J F; Zambudio, A; Prado, C

1997-08-22

The volume of gasoline sold in refuelling operations and the ambient temperature, can increase significantly the environmental levels of aromatic hydrocarbon vapours and subsequently, the occupational risk of gasoline service station attendants, specially in the case of benzene. We have evaluated the occupational exposure to aromatic hydrocarbons by means of personal-breathing-zone samples of gasoline vapours in a service station attendant population. This evaluation was carried out using diffusive samplers, in two periods at quite different temperatures (March and July). A significant relationship between the volume of gasoline sold during the shift and the ambient concentration of benzene, toluene, and xylenes was found for each worker sampled. Furthermore a significant difference was found between the time-weighted average concentration of aromatic compounds measured in March, with ambient temperatures of 14-15 degrees C and July, with temperatures of 28-30 degrees C. In addition, 20% of the population sampled in the last period were exposed to a time-weighted average concentration of benzene above the proposed Threshold Limit Value of 960 micrograms/m(3) of the American Conference of Governmental Industrial Hygienists (ACGIH).

Ultrasound-assisted ionic liquid dispersive liquid-liquid microextraction combined with graphite furnace atomic absorption spectrometric for selenium speciation in foods and beverages.

PubMed

Tuzen, Mustafa; Pekiner, Ozlem Zeynep

2015-12-01

A rapid and environmentally friendly ultrasound assisted ionic liquid dispersive liquid liquid microextraction (USA-IL-DLLME) was developed for the speciation of inorganic selenium in beverages and total selenium in food samples by using graphite furnace atomic absorption spectrometry. Some analytical parameters including pH, amount of complexing agent, extraction time, volume of ionic liquid, sample volume, etc. were optimized. Matrix effects were also investigated. Enhancement factor (EF) and limit of detection (LOD) for Se(IV) were found to be 150 and 12 ng L(-1), respectively. The relative standard deviation (RSD) was found 4.2%. The accuracy of the method was confirmed with analysis of LGC 6010 Hard drinking water and NIST SRM 1573a Tomato leaves standard reference materials. Optimized method was applied to ice tea, soda and mineral water for the speciation of Se(IV) and Se(VI) and some food samples including beer, cow's milk, red wine, mixed fruit juice, date, apple, orange, grapefruit, egg and honey for the determination of total selenium. Copyright © 2015 Elsevier Ltd. All rights reserved.

Studies of minute quantities of natural abundance molecules using 2D heteronuclear correlation spectroscopy under 100kHz MAS

DOE PAGES

Nishiyama, Y.; Kobayashi, T.; Malon, M.; ...

2015-02-16

Two-dimensional 1H{ 13C} heteronuclear correlation solid-state NMR spectra of naturally abundant solid materials are presented, acquired using the 0.75-mm magic angle spinning (MAS) probe at spinning rates up to 100 kHz. In spite of the miniscule sample volume (290 nL), high-quality HSQC-type spectra of bulk samples as well as surface-bound molecules can be obtained within hours of experimental time. The experiments are compared with those carried out at 40 kHz MAS using a 1.6-mm probe, which offered higher overall sensitivity due to a larger rotor volume. The benefits of ultrafast MAS in such experiments include superior resolution in 1H dimensionmore » without resorting to 1H– 1H homonuclear RF decoupling, easy optimization, and applicability to mass-limited samples. As a result, the HMQC spectra of surface-bound species can be also acquired under 100 kHz MAS, although the dephasing of transverse magnetization has significant effect on the efficiency transfer under MAS alone.« less

Hydrodynamic injection with pneumatic valving for microchip electrophoresis with total analyte utilization

PubMed Central

Sun, Xuefei; Kelly, Ryan T.; Danielson, William F.; Agrawal, Nitin; Tang, Keqi; Smith, Richard D.

2011-01-01

A novel hydrodynamic injector that is directly controlled by a pneumatic valve has been developed for reproducible microchip capillary electrophoresis (CE) separations. The poly(dimethylsiloxane) (PDMS) devices used for evaluation comprise a separation channel, a side channel for sample introduction, and a pneumatic valve aligned at the intersection of the channels. A low pressure (≤ 3 psi) applied to the sample reservoir is sufficient to drive sample into the separation channel. The rapidly actuated pneumatic valve enables injection of discrete sample plugs as small as ~100 pL for CE separation. The injection volume can be easily controlled by adjusting the intersection geometry, the solution back pressure and the valve actuation time. Sample injection could be reliably operated at different frequencies (< 0.1 Hz to >2 Hz) with good reproducibility (peak height relative standard deviation ≤ 3.6%) and no sampling biases associated with the conventional electrokinetic injections. The separation channel was dynamically coated with a cationic polymer, and FITC-labeled amino acids were employed to evaluate the CE separation. Highly efficient (≥ 7.0 × 103 theoretical plates for the ~2.4 cm long channel) and reproducible CE separations were obtained. The demonstrated method has numerous advantages compared with the conventional techniques, including repeatable and unbiased injections, little sample waste, high duty cycle, controllable injected sample volume, and fewer electrodes with no need for voltage switching. The prospects of implementing this injection method for coupling multidimensional separations, for multiplexing CE separations and for sample-limited bioanalyses are discussed. PMID:21520147

Age-related effects in the neocortical organization of chimpanzees: gray and white matter volume, cortical thickness, and gyrification.

PubMed

Autrey, Michelle M; Reamer, Lisa A; Mareno, Mary Catherine; Sherwood, Chet C; Herndon, James G; Preuss, Todd; Schapiro, Steve J; Hopkins, William D

2014-11-01

Among primates, humans exhibit the most profound degree of age-related brain volumetric decline in particular regions, such as the hippocampus and the frontal lobe. Recent studies have shown that our closest living relatives, the chimpanzees, experience little to no volumetric decline in gray and white matter over the adult lifespan. However, these previous studies were limited with a small sample of chimpanzees of the most advanced ages. In the present study, we sought to further test for potential age-related decline in cortical organization in chimpanzees by expanding the sample size of aged chimpanzees. We used the BrainVisa software to measure total brain volume, gray and white matter volumes, gray matter thickness, and gyrification index in a cross-sectional sample of 219 captive chimpanzees (8-53 years old), with 38 subjects being 40 or more years of age. Mean depth and cortical fold opening of 11 major sulci of the chimpanzee brains were also measured. We found that chimpanzees showed increased gyrification with age and a cubic relationship between age and white matter volume. For the association between age and sulcus depth and width, the results were mostly non-significant with the exception of one negative correlation between age and the fronto-orbital sulcus. In short, results showed that chimpanzees exhibit few age-related changes in global cortical organization, sulcus folding and sulcus width. These findings support previous studies and the theory that the age-related changes in the human brain is due to an extended lifespan. Copyright © 2014 Elsevier Inc. All rights reserved.

Determination of decamethylcyclopentasiloxane in air using commercial solid phase extraction cartridges.

PubMed

Kierkegaard, Amelie; McLachlan, Michael S

2010-05-21

Decamethylcyclopentasiloxane (D(5)), a high production volume chemical used in personal care products, has been designated for regulation in Canada and is under review in the EU because of concerns about its persistence and potential for bioaccumulation in the environment. D(5) is a volatile compound expected to be found primarily in air, but there is little information on atmospheric concentrations due to the lack of sensitive analytical methods. Here a simple and sensitive method to determine D(5) in ambient air is presented. The challenge in the environmental analysis of D(5) is avoiding contamination. Our method is based on the high trapping efficiency of the sorbent Isolute ENV+, combined with a comparably high sampling rate. A small amount of sorbent (10 mg) is eluted in a small volume of n-hexane (0.1-0.6 mL), which is injected onto a GC/MS system without further processing. The simplicity of the method enables the use of a field blank for every sample to trace contamination. The method provides low limits of quantification (approximately 0.3 ng/m(3)), good repeatability and limited breakthrough (approximately 1%). By lowering the limit of quantification compared to published work by almost two orders of magnitude, it became possible to quantify D(5) in ambient air at locations remote from strong point sources. The concentrations at a rural Swedish site ranged from 0.7 to 8 ng/m(3) over a period of 4 months. 2010 Elsevier B.V. All rights reserved.

The Far-Field Hubble Constant

NASA Astrophysics Data System (ADS)

Lauer, Tod

1995-07-01

We request deep, near-IR (F814W) WFPC2 images of five nearby Brightest Cluster Galaxies (BCG) to calibrate the BCG Hubble diagram by the Surface Brightness Fluctuation (SBF) method. Lauer & Postman (1992) show that the BCG Hubble diagram measured out to 15,000 km s^-1 is highly linear. Calibration of the Hubble diagram zeropoint by SBF will thus yield an accurate far-field measure of H_0 based on the entire volume within 15,000 km s^-1, thus circumventing any strong biases caused by local peculiar velocity fields. This method of reaching the far field is contrasted with those using distance ratios between Virgo and Coma, or any other limited sample of clusters. HST is required as the ground-based SBF method is limited to <3,000 km s^-1. The high spatial resolution of HST allows precise measurement of the SBF signal at large distances, and allows easy recognition of globular clusters, background galaxies, and dust clouds in the BCG images that must be removed prior to SBF detection. The proposing team developed the SBF method, the first BCG Hubble diagram based on a full-sky, volume-limited BCG sample, played major roles in the calibration of WFPC and WFPC2, and are conducting observations of local galaxies that will validate the SBF zeropoint (through GTO programs). This work uses the SBF method to tie both the Cepheid and Local Group giant-branch distances generated by HST to the large scale Hubble flow, which is most accurately traced by BCGs.

Determination of Total Petroleum Hydrocarbons in Australian Groundwater Through the Improvised Gas Chromatography-Flame Ionization Detection Technique.

PubMed

Faustorilla, Maria Vilma; Chen, Zuliang; Dharmarajan, Rajarathnam; Naidu, Ravendra

2017-09-01

Assessment of total petroleum hydrocarbons (TPHs) from contaminated sites demands routine and reliable measurement at trace levels. However, the detection limits of these methods need to be improved. This study developed the programmable temperature vaporization-large volume injection (PTV-LVI) method to quantify TPHs through gas chromatography-flame ionization detection. This configuration enhances the method sensitivity for trace level detections through large volume injections and pre-concentration of analytes along the injection liner. The method was evaluated for the three commonly observed hydrocarbon fractions: C10-C14, C15-C28 and C29-C36. In comparison with conventional injection methods (splitless and pulsed splitless), PTV-LVI showed R2 values > 0.999 with enhanced limits of detection and limits of quantification values. The method was applied to real samples for routine environmental monitoring of TPHs in an Australian contaminated site characterized by refueling station. Analysis of groundwater samples in the area showed a wide range of TPH concentrations as follows: 66-1,546,000 (C10-C14), 216-22,762 (C15-C28) and 105-2,103 (C29-C36) μg/L. This method has detected trace levels, thereby measuring a wider concentration range of TPHs. These more accurate measurements can lead to the appropriate application of risk assessments and remediation techniques. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Extended two-photon microscopy in live samples with Bessel beams: steadier focus, faster volume scans, and simpler stereoscopic imaging.

PubMed

Thériault, Gabrielle; Cottet, Martin; Castonguay, Annie; McCarthy, Nathalie; De Koninck, Yves

2014-01-01

Two-photon microscopy has revolutionized functional cellular imaging in tissue, but although the highly confined depth of field (DOF) of standard set-ups yields great optical sectioning, it also limits imaging speed in volume samples and ease of use. For this reason, we recently presented a simple and retrofittable modification to the two-photon laser-scanning microscope which extends the DOF through the use of an axicon (conical lens). Here we demonstrate three significant benefits of this technique using biological samples commonly employed in the field of neuroscience. First, we use a sample of neurons grown in culture and move it along the z-axis, showing that a more stable focus is achieved without compromise on transverse resolution. Second, we monitor 3D population dynamics in an acute slice of live mouse cortex, demonstrating that faster volumetric scans can be conducted. Third, we acquire a stereoscopic image of neurons and their dendrites in a fixed sample of mouse cortex, using only two scans instead of the complete stack and calculations required by standard systems. Taken together, these advantages, combined with the ease of integration into pre-existing systems, make the extended depth-of-field imaging based on Bessel beams a strong asset for the field of microscopy and life sciences in general.

Development of a syringe pump assisted dynamic headspace sampling technique for needle trap device.

PubMed

Eom, In-Yong; Niri, Vadoud H; Pawliszyn, Janusz

2008-07-04

This paper describes a new approach that combines needle trap devices (NTDs) with a dynamic headspace sampling technique (purge and trap) using a bidirectional syringe pump. The needle trap device is a 22-G stainless steel needle 3.5-in. long packed with divinylbenzene sorbent particles. The same sized needle, without packing, was used for purging purposes. We chose an aqueous mixture of benzene, toluene, ethylbenzene, and p-xylene (BTEX) and developed a sequential purge and trap (SPNT) method, in which sampling (trapping) and purging cycles were performed sequentially by the use of syringe pump with different distribution channels. In this technique, a certain volume (1 mL) of headspace was sequentially sampled using the needle trap; afterwards, the same volume of air was purged into the solution at a high flow rate. The proposed technique showed an effective extraction compared to the continuous purge and trap technique, with a minimal dilution effect. Method evaluation was also performed by obtaining the calibration graphs for aqueous BTEX solutions in the concentration range of 1-250 ng/mL. The developed technique was compared to the headspace solid-phase microextraction method for the analysis of aqueous BTEX samples. Detection limits as low as 1 ng/mL were obtained for BTEX by NTD-SPNT.

Solid phase extraction of metal ions in environmental samples on 1-(2-pyridylazo)-2-naphthol impregnated activated carbon cloth.

PubMed

Alothman, Zeid A; Yilmaz, Erkan; Habila, Mohamed; Soylak, Mustafa

2015-02-01

1-(2-Pyridylazo)-2-naphthol impregnated activated carbon cloth (PAN-imp-ACC) was prepared as a solid phase sorbent and, for the first time, was used for the simultaneous separation and preconcentration of trace amounts of lead, cadmium and nickel in water, soil and sewage sludge samples prior to determination by flame atomic absorption spectrometry (FAAS). The parameters governing the efficiency of the method were optimized, including the pH, the eluent type and volume, the sample and eluent flow rates, diverse ions effects and the sample volume. A preconcentration factor of 100 was achieved for all the metal ions, with detection limits of 0.1-2.8 µg L(-1) and relative standard deviations below 6.3%. The adsorption capacity of the PAN-imp-ACC for Pb(II), Cd(II) and Ni(II) ions was found to be 45.0 mg g(-1), 45.0 mg g(-1) and 43.2 mg g(-1), respectively. The method was validated by the analysis of the certified reference materials TMDA-64.2 fortified Lake Ontario water and BCR-146R Sewage Sludge Amended Soil (Industrial Origin). The procedure was applied to determine the analytes content in real samples. Copyright © 2014 Elsevier Inc. All rights reserved.

Heat strain, volume depletion and kidney function in California agricultural workers.

PubMed

Moyce, Sally; Mitchell, Diane; Armitage, Tracey; Tancredi, Daniel; Joseph, Jill; Schenker, Marc

2017-06-01

Agricultural work can expose workers to increased risk of heat strain and volume depletion due to repeated exposures to high ambient temperatures, arduous physical exertion and limited rehydration. These risk factors may result in acute kidney injury (AKI). We estimated AKI cumulative incidence in a convenience sample of 283 agricultural workers based on elevations of serum creatinine between preshift and postshift blood samples. Heat strain was assessed based on changes in core body temperature and heart rate. Volume depletion was assessed using changes in body mass over the work shift. Logistic regression models were used to estimate the associations of AKI with traditional risk factors (age, diabetes, hypertension and history of kidney disease) as well as with occupational risk factors (years in farm work, method of payment and farm task). 35 participants were characterised with incident AKI over the course of a work shift (12.3%). Workers who experienced heat strain had increased adjusted odds of AKI (1.34, 95% CI 1.04 to 1.74). Piece rate work was associated with 4.24 odds of AKI (95% CI 1.56 to 11.52). Females paid by the piece had 102.81 adjusted odds of AKI (95% CI 7.32 to 1443.20). Heat strain and piece rate work are associated with incident AKI after a single shift of agricultural work, though gender differences exist. Modifications to payment structures may help prevent AKI. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Determination of trace metals in drinking water using solid-phase extraction disks and X-ray fluorescence spectrometry.

PubMed

Hou, Xiandeng; Peters, Heather L; Yang, Zheng; Wagner, Karl A; Batchelor, James D; Daniel, Meredith M; Jones, Bradley T

2003-03-01

A convenient method is described for monitoring Cd, Ni, Cu, and Pb at trace levels in drinking water samples. These metals are preconcentrated on a chelating solid-phase extraction disk and then determined by X-ray fluorescence spectrometry. The method tolerates a wide pH range (pH 6-14) and a large amount of alkaline and alkaline earth elements. The preconcentration factor is well over 1600, assuming a 1 L water sample volume. The limits of detection for Cd, Ni, Cu, and Pb are 3.8, 0.6, 0.4, and 0.3 ng/mL, respectively. These are well below the federal maximum contaminant level values, which are 5, 100, 1300, and 15 ng/mL, respectively. The proposed method has many advantages including ease of operation, multielement capability, nondestructiveness, high sensitivity, and relative cost efficiency. The solid-phase extraction step can be conducted in the field and then the disks can be mailed to a laboratory for the analysis, eliminating the cost of transporting large volumes of water samples. Furthermore, the color of the used extraction disk provides an initial estimate of the degree of contamination for some transition metals (for example, Ni and Cu). Thus, the overall cost for analysis of metals in drinking water can be minimized by implementing the method, and small water supply companies with limited budgets will be better able to comply with the Safe Drinking Water Act.

Scanner baseliner monitoring and control in high volume manufacturing

NASA Astrophysics Data System (ADS)

Samudrala, Pavan; Chung, Woong Jae; Aung, Nyan; Subramany, Lokesh; Gao, Haiyong; Gomez, Juan-Manuel

2016-03-01

We analyze performance of different customized models on baseliner overlay data and demonstrate the reduction in overlay residuals by ~10%. Smart Sampling sets were assessed and compared with the full wafer measurements. We found that performance of the grid can still be maintained by going to one-third of total sampling points, while reducing metrology time by 60%. We also demonstrate the feasibility of achieving time to time matching using scanner fleet manager and thus identify the tool drifts even when the tool monitoring controls are within spec limits. We also explore the scanner feedback constant variation with illumination sources.

Quantification of protein concentration using UV absorbance and Coomassie dyes.

PubMed

Noble, James E

2014-01-01

The measurement of a solubilized protein concentration in solution is an important assay in biochemistry research and development labs for applications ranging from enzymatic studies to providing data for biopharmaceutical lot release. Spectrophotometric protein quantification assays are methods that use UV and visible spectroscopy to rapidly determine the concentration of protein, relative to a standard, or using an assigned extinction coefficient. Where multiple samples need measurement, and/or the sample volume and concentration is limited, preparations of the Coomassie dye commonly known as the Bradford assay can be used. © 2014 Elsevier Inc. All rights reserved.

Long-range and wide field of view optical coherence tomography for in vivo 3D imaging of large volume object based on akinetic programmable swept source.

PubMed

Song, Shaozhen; Xu, Jingjiang; Wang, Ruikang K

2016-11-01

Current optical coherence tomography (OCT) imaging suffers from short ranging distance and narrow imaging field of view (FOV). There is growing interest in searching for solutions to these limitations in order to expand further in vivo OCT applications. This paper describes a solution where we utilize an akinetic swept source for OCT implementation to enable ~10 cm ranging distance, associated with the use of a wide-angle camera lens in the sample arm to provide a FOV of ~20 x 20 cm 2 . The akinetic swept source operates at 1300 nm central wavelength with a bandwidth of 100 nm. We propose an adaptive calibration procedure to the programmable akinetic light source so that the sensitivity of the OCT system over ~10 cm ranging distance is substantially improved for imaging of large volume samples. We demonstrate the proposed swept source OCT system for in vivo imaging of entire human hands and faces with an unprecedented FOV (up to 400 cm 2 ). The capability of large-volume OCT imaging with ultra-long ranging and ultra-wide FOV is expected to bring new opportunities for in vivo biomedical applications.

Long-range and wide field of view optical coherence tomography for in vivo 3D imaging of large volume object based on akinetic programmable swept source

PubMed Central

Song, Shaozhen; Xu, Jingjiang; Wang, Ruikang K.

2016-01-01

Current optical coherence tomography (OCT) imaging suffers from short ranging distance and narrow imaging field of view (FOV). There is growing interest in searching for solutions to these limitations in order to expand further in vivo OCT applications. This paper describes a solution where we utilize an akinetic swept source for OCT implementation to enable ~10 cm ranging distance, associated with the use of a wide-angle camera lens in the sample arm to provide a FOV of ~20 x 20 cm2. The akinetic swept source operates at 1300 nm central wavelength with a bandwidth of 100 nm. We propose an adaptive calibration procedure to the programmable akinetic light source so that the sensitivity of the OCT system over ~10 cm ranging distance is substantially improved for imaging of large volume samples. We demonstrate the proposed swept source OCT system for in vivo imaging of entire human hands and faces with an unprecedented FOV (up to 400 cm2). The capability of large-volume OCT imaging with ultra-long ranging and ultra-wide FOV is expected to bring new opportunities for in vivo biomedical applications. PMID:27896012

Analysis of nanoliter samples of electrolytes using a flow-through microfluorometer.

PubMed

Zhelyaskov, V R; Liu, S; Broderick, M P

2000-04-01

Several techniques have been developed to study the transport properties of nanoliter samples of renal tubule segments, such as continuous flow colorimetry and continuous fluorometry. We have extended the capability of the NANOFLO, a flow-through microfluorometer, designed for measurement of carbon dioxide, urea, ammonia, glucose, lactate, etc., to analyze sodium, calcium and chloride ions, using three commercially available fluorescent indicators for intracellular and extracellular measurements. The selection of fluorescent indicator for each electrolyte was dependent on the optimal match of the dissociation constant and the analyte concentration range of interest. Using Fluo-3 dye we achieved a detection limit for Ca2+ of 0.1 pmol and selectivity over Mg2+ of between 7:1 to 10:1. Using sodium green dye we achieved detection limit for Na+ of 12 pmol and a selectivity over K+ of 40:1. The detection limit for Cl- using lucigenin dye was 10 pmol. This technique can be readily adapted for the measurement of other physiologically important ultralow volume.

Investigation, development and application of optimal output feedback theory. Volume 2: Development of an optimal, limited state feedback outer-loop digital flight control system for 3-D terminal area operation

NASA Technical Reports Server (NTRS)

Broussard, J. R.; Halyo, N.

1984-01-01

This report contains the development of a digital outer-loop three dimensional radio navigation (3-D RNAV) flight control system for a small commercial jet transport. The outer-loop control system is designed using optimal stochastic limited state feedback techniques. Options investigated using the optimal limited state feedback approach include integrated versus hierarchical control loop designs, 20 samples per second versus 5 samples per second outer-loop operation and alternative Type 1 integration command errors. Command generator tracking techniques used in the digital control design enable the jet transport to automatically track arbitrary curved flight paths generated by waypoints. The performance of the design is demonstrated using detailed nonlinear aircraft simulations in the terminal area, frequency domain multi-input sigma plots, frequency domain single-input Bode plots and closed-loop poles. The response of the system to a severe wind shear during a landing approach is also presented.

Determination of Alternaria mycotoxins in wine and juice using ionic liquid modified countercurrent chromatography as a pretreatment method followed by high-performance liquid chromatography.

PubMed

Fan, Chen; Cao, Xueli; Liu, Man; Wang, Wei

2016-03-04

Alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA) are some of the main Alternaria mycotoxins that can be found as contaminants in food materials. The objective of this study was to develop a pretreatment method with countercurrent chromatography (CCC) for enrichment and cleanup of trace Alternaria mycotoxins in food samples prior to high-performance liquid chromatography (HPLC) analysis. An Analytical CCC instrument with a column volume 22.5mL was used, and a two-phase solvent system composed of ethyl acetate and water modified with 6% [HOOMIM][Cl] in mass to volume ratio was selected. Under the optimized CCC operation conditions, trace amounts of AOH, AME, and TeA in large volume of liquid sample were efficiently extracted and enriched in the stationary phase, and then eluted out just by reversing the stationary phase as mobile phase in the opposite flowing direction tail-to-head. The enrichment and elution strategies are unique and can be fulfilled online with high enrichment factors (87-114) and high recoveries (81.14-110.94%). The method has been successively applied to the determination of Alternaria mycotoxins in real apple juice and wine samples with the limits of detection (LOD) in the range of 0.03-0.14μgL(-1). Totally 12 wine samples and 15 apple juice samples from the local market were analyzed. The detection rate of AOH and AME in both kinds of the samples were more than 50%, while TeA was found in relatively high level of 1.75-49.61μgL(-1) in some of the apple juice samples. The proposed method is simple, rapid, and sensitive and could also be used for the analysis and monitoring of Alternaria mycotoxin in other food samples. Copyright © 2016 Elsevier B.V. All rights reserved.

A dilute-and-shoot sample preparation strategy for new and used lubricating oils for Ca, P, S and Zn determination by total reflection X-ray fluorescence

NASA Astrophysics Data System (ADS)

Mota, Mariana F. B.; Gama, Ednilton M.; Rodrigues, Gabrielle de C.; Rodrigues, Guilherme D.; Nascentes, Clésia C.; Costa, Letícia M.

2018-01-01

In this work, a dilute-and-shoot method was developed for Ca, P, S and Zn determination in new and used lubricating oil samples by total reflection X-ray fluorescence (TXRF). The oil samples were diluted with organic solvents followed by addition of yttrium as internal standard and the TXRF measurements were performed after solvent evaporation. The method was optimized using an interlaboratorial reference material. The experimental parameters evaluated were sample volume (50 or 100 μL), measurement time (250 or 500 s) and volume deposited on the quartz glass sample carrier (5 or 10 μL). All of them were evaluated and optimized using xylene, kerosene and hexane. Analytical figures of merit (accuracy, precision, limit of detection and quantification) were used to evaluate the performance of the analytical method for all solvents. The recovery rates varied from 99 to 111% and the relative standard deviation remained between 1.7% and 10% (n = 8). For all elements, the results obtained by applying the new method were in agreement with the certified value. After the validation step, the method was applied for Ca, P, S and Zn quantification in eight new and four used lubricating oil samples, for all solvents. The concentration of the elements in the samples varied in the ranges of 1620-3711 mg L- 1 for Ca, 704-1277 mg L- 1 for P, 2027-9147 mg L- 1 for S, and 898-1593 mg L- 1 for Zn. The association of TXRF with a dilute-and-shoot sample preparation strategy was efficient for Ca, P, S and Zn determination in lubricating oils, presenting accurate results. Additionally, the time required for analysis is short, the reagent volumes are low minimizing waste generation, and the technique does not require calibration curves.

Ratio of Cut Surface Area to Leaf Sample Volume for Water Potential Measurements by Thermocouple Psychrometers

PubMed Central

Walker, Sue; Oosterhuis, Derrick M.; Wiebe, Herman H.

1984-01-01

Evaporative losses from the cut edge of leaf samples are of considerable importance in measurements of leaf water potential using thermocouple psychrometers. The ratio of cut surface area to leaf sample volume (area to volume ratio) has been used to give an estimate of possible effects of evaporative loss in relation to sample size. A wide range of sample sizes with different area to volume ratios has been used. Our results using Glycine max L. Merr. cv Bragg indicate that leaf samples with area to volume values less than 0.2 square millimeter per cubic millimeter give psychrometric leaf water potential measurements that compare favorably with pressure chamber measurements. PMID:16663578

High performance liquid chromatographic assay for the quantitation of total glutathione in plasma

NASA Technical Reports Server (NTRS)

Abukhalaf, Imad K.; Silvestrov, Natalia A.; Menter, Julian M.; von Deutsch, Daniel A.; Bayorh, Mohamed A.; Socci, Robin R.; Ganafa, Agaba A.

2002-01-01

A simple and widely used homocysteine HPLC procedure was applied for the HPLC identification and quantitation of glutathione in plasma. The method, which utilizes SBDF as a derivatizing agent utilizes only 50 microl of sample volume. Linear quantitative response curve was generated for glutathione over a concentration range of 0.3125-62.50 micromol/l. Linear regression analysis of the standard curve exhibited correlation coefficient of 0.999. Limit of detection (LOD) and limit of quantitation (LOQ) values were 5.0 and 15 pmol, respectively. Glutathione recovery using this method was nearly complete (above 96%). Intra-assay and inter-assay precision studies reflected a high level of reliability and reproducibility of the method. The applicability of the method for the quantitation of glutathione was demonstrated successfully using human and rat plasma samples.

Measuring pedestrian volumes and conflicts. Volume 1, Pedestrian volume sampling

DOT National Transportation Integrated Search

1987-12-01

This final report presents the findings, conclusions, and recommendations of the study conducted to develop a model to predict pedestrian volumes using small sampling schemes. This research produced four pedestrian volume prediction models (i.e., 1-,...

HIGH VOLUME INJECTION FOR GCMS ANALYSIS OF PARTICULATE ORGANIC SPECIES IN AMBIENT AIR

EPA Science Inventory

Detection of organic species in ambient particulate matter typically requires large air sample volumes, frequently achieved by grouping samples into monthly composites. Decreasing the volume of air sample required would allow shorter collection times and more convenient sample c...

Using dried blood spot sampling to improve data quality and reduce animal use in mouse pharmacokinetic studies.

PubMed

Wickremsinhe, Enaksha R; Perkins, Everett J

2015-03-01

Traditional pharmacokinetic analysis in nonclinical studies is based on the concentration of a test compound in plasma and requires approximately 100 to 200 μL blood collected per time point. However, the total blood volume of mice limits the number of samples that can be collected from an individual animal-often to a single collection per mouse-thus necessitating dosing multiple mice to generate a pharmacokinetic profile in a sparse-sampling design. Compared with traditional methods, dried blood spot (DBS) analysis requires smaller volumes of blood (15 to 20 μL), thus supporting serial blood sampling and the generation of a complete pharmacokinetic profile from a single mouse. Here we compare plasma-derived data with DBS-derived data, explain how to adopt DBS sampling to support discovery mouse studies, and describe how to generate pharmacokinetic and pharmacodynamic data from a single mouse. Executing novel study designs that use DBS enhances the ability to identify and streamline better drug candidates during drug discovery. Implementing DBS sampling can reduce the number of mice needed in a drug discovery program. In addition, the simplicity of DBS sampling and the smaller numbers of mice needed translate to decreased study costs. Overall, DBS sampling is consistent with 3Rs principles by achieving reductions in the number of animals used, decreased restraint-associated stress, improved data quality, direct comparison of interanimal variability, and the generation of multiple endpoints from a single study.

A method for nitrate collection for δ15N and δ18O analysis from waters with low nitrate concentrations

USGS Publications Warehouse

Chang, Cecily C.Y.; Langston, J.; Riggs, M.; Campbell, D.H.; Silva, S.R.; Kendall, C.

1999-01-01

 Recently, methods have been developed to analyze NO3- for δ15N and δ18O, improving our ability to identify NO3- sources and transformations. However, none of the existing methods are suited for waters with low NO3- concentrations (0.7-10 µM). We describe an improved method for collecting and recovering NO3- on exchange columns. To overcome the lengthy collection loading times imposed by the large sample volumes (7-70 L), the sample was prefiltered (0.45 µm) with a large surface area filter. Switching to AG2X anion resin and using a coarser mesh size (100-200) than previous methods also enhanced sample flow. Placement of a cation column in front of the anion column minimized clogging of the anion column by dissolved organic carbon (DOC) accumulation. This also served to minimize transfer of unwanted oxygen atoms from DOC to the 18O portion of the NO3- sample, thereby contaminating the sample and shifting δ18O. The cat-AG2X method is suited for on-site sample collection, making it possible to collect and recover NO3- from low ionic strength waters with modest DOC concentrations (80-800 µM), relieves the investigator of transporting large volumes of water back to the laboratory, and offers a means of sampling rain, snow, snowmelt, and stream samples from access-limited sites.

Using Dried Blood Spot Sampling to Improve Data Quality and Reduce Animal Use in Mouse Pharmacokinetic Studies

PubMed Central

Wickremsinhe, Enaksha R; Perkins, Everett J

2015-01-01

Traditional pharmacokinetic analysis in nonclinical studies is based on the concentration of a test compound in plasma and requires approximately 100 to 200 µL blood collected per time point. However, the total blood volume of mice limits the number of samples that can be collected from an individual animal—often to a single collection per mouse—thus necessitating dosing multiple mice to generate a pharmacokinetic profile in a sparse-sampling design. Compared with traditional methods, dried blood spot (DBS) analysis requires smaller volumes of blood (15 to 20 µL), thus supporting serial blood sampling and the generation of a complete pharmacokinetic profile from a single mouse. Here we compare plasma-derived data with DBS-derived data, explain how to adopt DBS sampling to support discovery mouse studies, and describe how to generate pharmacokinetic and pharmacodynamic data from a single mouse. Executing novel study designs that use DBS enhances the ability to identify and streamline better drug candidates during drug discovery. Implementing DBS sampling can reduce the number of mice needed in a drug discovery program. In addition, the simplicity of DBS sampling and the smaller numbers of mice needed translate to decreased study costs. Overall, DBS sampling is consistent with 3Rs principles by achieving reductions in the number of animals used, decreased restraint-associated stress, improved data quality, direct comparison of interanimal variability, and the generation of multiple endpoints from a single study. PMID:25836959

Stereological estimation of cell wall density of DR12 tomato mutant using three-dimensional confocal imaging

PubMed Central

Legland, David; Guillon, Fabienne; Kiêu, Kiên; Bouchet, Brigitte; Devaux, Marie-Françoise

2010-01-01

Background and Aims The cellular structure of fleshy fruits is of interest to study fruit shape, size, mechanical behaviour or sensory texture. The cellular structure is usually not observed in the whole fruit but, instead, in a sample of limited size and volume. It is therefore difficult to extend measurements to the whole fruit and/or to a specific genotype, or to describe the cellular structure heterogeneity within the fruit. Methods An integrated method is presented to describe the cellular structure of the whole fruit from partial three-dimensional (3D) observations, involving the following steps: (1) fruit sampling, (2) 3D image acquisition and processing and (3) measurement and estimation of relevant 3D morphological parameters. This method was applied to characterize DR12 mutant and wild-type tomatoes (Solanum lycopersicum). Key Results The cellular structure was described using the total volume of the pericarp, the surface area of the cell walls and the ratio of cell-wall surface area to pericarp volume, referred to as the cell-wall surface density. The heterogeneity of cellular structure within the fruit was investigated by estimating variations in the cell-wall surface density with distance to the epidermis. Conclusions The DR12 mutant presents a greater pericarp volume and an increase of cell-wall surface density under the epidermis. PMID:19952012

Investigation of fluorine content in PM2.5 airborne particles of Istanbul, Turkey.

PubMed

Ozbek, Nil; Baltaci, Hakki; Baysal, Asli

2016-07-01

Fluorine determination in airborne samples is important due to its spread into the air from both natural and artificial sources. It can travel by wind over large distances before depositing on the Earth's surface. Its concentration in various matrices are limited and controlled by the regulations for causing health risks associated with environmental exposures. In this work, fluorine was determined in PM2.5 airborne samples by high-resolution continuum source electrothermal atomic absorption spectrometry. For these purpose, the PM2.5 airborne particulates were collected on quartz filters using high-volume samplers (500 L/min) in Istanbul (Turkey) for 96 h during January to June in 2 years. Then, instrumental and experimental parameters were optimized for the analyte in airborne samples. The validity of the method for the analyte was tested using standard reference material, and certified values were found in the limits of 95 % confidence level. The fluorine concentrations and meteorological conditions were compared statistically.

Nitrate and Nitrite Determination in Gunshot Residue Samples by Capillary Electrophoresis in Acidic Run Buffer.

PubMed

Erol, Özge Ö; Erdoğan, Behice Y; Onar, Atiye N

2017-03-01

Simultaneous determination of nitrate and nitrite in gunshot residue has been conducted by capillary electrophoresis using an acidic run buffer (pH 3.5). In previously developed capillary electrophoretic methods, alkaline pH separation buffers were used where nitrite and nitrate possess similar electrophoretic mobility. In this study, the electroosmotic flow has been reversed by using low pH running buffer without any additives. As a result of reversing the electroosmotic flow, very fast analysis has been actualized, well-defined and separated ion peaks emerge in less than 4 min. Besides, the limit of detection was improved by employing large volume sample stacking. Limit of detection values were 6.7 and 4.3 μM for nitrate and nitrite, respectively. In traditional procedure, mechanical agitation is employed for extraction, while in this work the extraction efficiency of ultrasound mixing for 30 min was found sufficient. The proposed method was successfully applied to authentic gunshot residue samples. © 2016 American Academy of Forensic Sciences.

A sensitive analytical procedure for monitoring acrylamide in environmental water samples by offline SPE-UPLC/MS/MS.

PubMed

Togola, Anne; Coureau, Charlotte; Guezennec, Anne-Gwenaëlle; Touzé, Solène

2015-05-01

The presence of acrylamide in natural systems is of concern from both environmental and health points of view. We developed an accurate and robust analytical procedure (offline solid phase extraction combined with UPLC/MS/MS) with a limit of quantification (20 ng L(-1)) compatible with toxicity threshold values. The optimized (considering the nature of extraction phases, sampling volumes, and solvent of elution) solid phase extraction (SPE) was validated according to ISO Standard ISO/IEC 17025 on groundwater, surface water, and industrial process water samples. Acrylamide is highly polar, which induces a high variability during the SPE step, therefore requiring the use of C(13)-labeled acrylamide as an internal standard to guarantee the accuracy and robustness of the method (uncertainty about 25 % (k = 2) at limit of quantification level). The specificity of the method and the stability of acrylamide were studied for these environmental media, and it was shown that the method is suitable for measuring acrylamide in environmental studies.

Comparison of spectroscopy technologies for improved monitoring of cell culture processes in miniature bioreactors.

PubMed

Rowland-Jones, Ruth C; van den Berg, Frans; Racher, Andrew J; Martin, Elaine B; Jaques, Colin

2017-03-01

Cell culture process development requires the screening of large numbers of cell lines and process conditions. The development of miniature bioreactor systems has increased the throughput of such studies; however, there are limitations with their use. One important constraint is the limited number of offline samples that can be taken compared to those taken for monitoring cultures in large-scale bioreactors. The small volume of miniature bioreactor cultures (15 mL) is incompatible with the large sample volume (600 µL) required for bioanalysers routinely used. Spectroscopy technologies may be used to resolve this limitation. The purpose of this study was to compare the use of NIR, Raman, and 2D-fluorescence to measure multiple analytes simultaneously in volumes suitable for daily monitoring of a miniature bioreactor system. A novel design-of-experiment approach is described that utilizes previously analyzed cell culture supernatant to assess metabolite concentrations under various conditions while providing optimal coverage of the desired design space. Multivariate data analysis techniques were used to develop predictive models. Model performance was compared to determine which technology is more suitable for this application. 2D-fluorescence could more accurately measure ammonium concentration (RMSE CV 0.031 g L -1 ) than Raman and NIR. Raman spectroscopy, however, was more robust at measuring lactate and glucose concentrations (RMSE CV 1.11 and 0.92 g L -1 , respectively) than the other two techniques. The findings suggest that Raman spectroscopy is more suited for this application than NIR and 2D-fluorescence. The implementation of Raman spectroscopy increases at-line measuring capabilities, enabling daily monitoring of key cell culture components within miniature bioreactor cultures. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:337-346, 2017. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers.

"Paper Machine" for Molecular Diagnostics.

PubMed

Connelly, John T; Rolland, Jason P; Whitesides, George M

2015-08-04

Clinical tests based on primer-initiated amplification of specific nucleic acid sequences achieve high levels of sensitivity and specificity. Despite these desirable characteristics, these tests have not reached their full potential because their complexity and expense limit their usefulness to centralized laboratories. This paper describes a device that integrates sample preparation and loop-mediated isothermal amplification (LAMP) with end point detection using a hand-held UV source and camera phone. The prototype device integrates paper microfluidics (to enable fluid handling) and a multilayer structure, or a "paper machine", that allows a central patterned paper strip to slide in and out of fluidic path and thus allows introduction of sample, wash buffers, amplification master mix, and detection reagents with minimal pipetting, in a hand-held, disposable device intended for point-of-care use in resource-limited environments. This device creates a dynamic seal that prevents evaporation during incubation at 65 °C for 1 h. This interval is sufficient to allow a LAMP reaction for the Escherichia coli malB gene to proceed with an analytical sensitivity of 1 double-stranded DNA target copy. Starting with human plasma spiked with whole, live E. coli cells, this paper demonstrates full integration of sample preparation with LAMP amplification and end point detection with a limit of detection of 5 cells. Further, it shows that the method used to prepare sample enables concentration of DNA from sample volumes commonly available from fingerstick blood draw.

Decreasing Irradiated Rat Lung Volume Changes Dose-Limiting Toxicity From Early to Late Effects

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

Veen, Sonja J. van der; Faber, Hette; Ghobadi, Ghazaleh

2016-01-01

Purpose: Technological developments in radiation therapy result in smaller irradiated volumes of normal tissue. Because the risk of radiation therapy-induced toxicity generally depends on irradiated volume, changing volume could change the dose-limiting toxicity of a treatment. Recently, in our rat model, we found that early radiation-induced lung dysfunction (RILD) was closely related to irradiated volume dependent vascular remodeling besides inflammation. The exact relationship between early and late RILD is still unknown. Therefore, in this preclinical study we investigated the dose-volume relationship of late RILD, assessed its dependence on early and late pathologies and studied if decreasing irradiated volume changed themore » dose-limiting toxicity. Methods and Materials: A volume of 25%, 32%, 50%, 63%, 88%, or 100% of the rat lung was irradiated using protons. Until 26 weeks after irradiation, respiratory rates were measured. Macrovascular remodeling, pulmonary inflammation, and fibrosis were assessed at 26 weeks after irradiation. For all endpoints dose-volume response curves were made. These results were compared to our previously published early lung effects. Results: Early vascular remodeling and inflammation correlated significantly with early RILD. Late RILD correlated with inflammation and fibrosis, but not with vascular remodeling. In contrast to the early effects, late vascular remodeling, inflammation and fibrosis showed a primarily dose but not volume dependence. Comparison of respiratory rate increases early and late after irradiation for the different dose-distributions indicated that with decreasing irradiated volumes, the dose-limiting toxicity changed from early to late RILD. Conclusions: In our rat model, different pathologies underlie early and late RILD with different dose-volume dependencies. Consequently, the dose-limiting toxicity changed from early to late dysfunction when the irradiated volume was reduced. In patients, early and late RILD are also due to different pathologies. As such, new radiation techniques reducing irradiated volume might change the dose-limiting toxicity of the radiation therapy treatment.« less

Paper-based microfluidic devices on the crime scene: A simple tool for rapid estimation of post-mortem interval using vitreous humour.

PubMed

Garcia, Paulo T; Gabriel, Ellen F M; Pessôa, Gustavo S; Santos Júnior, Júlio C; Mollo Filho, Pedro C; Guidugli, Ruggero B F; Höehr, Nelci F; Arruda, Marco A Z; Coltro, Wendell K T

2017-06-29

This paper describes for the first time the use of paper-based analytical devices at crime scenes to estimate the post-mortem interval (PMI), based on the colorimetric determination of Fe 2+ in vitreous humour (VH) samples. Experimental parameters such as the paper substrate, the microzone diameter, the sample volume and the 1,10-phenanthroline (o-phen) concentration were optimised in order to ensure the best analytical performance. Grade 1 CHR paper, microzone with diameter of 5 mm, a sample volume of 4 μL and an o-phen concentration of 0.05 mol/L were chosen as the optimum experimental conditions. A good linear response was observed for a concentration range of Fe 2+ between 2 and 10 mg/L and the calculated values for the limit of detection (LOD) and limit of quantification (LOQ) were 0.3 and 0.9 mg/L, respectively. The specificity of the Fe 2+ colorimetric response was tested in the presence of the main interfering agents and no significant differences were found. After selecting the ideal experimental conditions, four HV samples were investigated on paper-based devices. The concentration levels of Fe 2+ achieved for samples #1, #2, #3 and #4 were 0.5 ± 0.1, 0.7 ± 0.1, 1.2 ± 0.1 and 15.1 ± 0.1 mg/L, respectively. These values are in good agreement with those calculated by ICP-MS. It important to note that the concentration levels measured using both techniques are proportional to the PMI. The limitation of the proposed analytical device is that it is restricted to a PMI greater than 1 day. The capability of providing an immediate answer about the PMI on the crime scene without any sophisticated instrumentation is a great achievement in modern instrumentation for forensic chemistry. The strategy proposed in this study could be helpful in many criminal investigations. Copyright © 2017 Elsevier B.V. All rights reserved.

Micro-apparatus for rapid determinations of protein solubilities

NASA Technical Reports Server (NTRS)

Pusey, Marc L.; Munson, Sibyl

1991-01-01

We have developed a column-based micro-technique for rapid determinations of protein solubilities. While retaining a large crystal surface area, the column dead volume has been reduced to equal to or less than 5 micro liters. The technique was tested with tetragonal lysozyme (pH 4.5, 0.1 M acetate, 3.0 percent NaCl, 5-25 C) and column volumes of about 60, 300, and 900 micro liters. Identical solubility data were obtained, indicating that equilibration was obtained even in the smallest columns. In addition, solubility data for Br- and I- salts of lysozyme (pH 4.5, 0.1 M acetate buffer, 0.5 M salt concentrations) were obtained. It appears that the technique can be further miniaturized. The limit in further reducing the crystalline column volume is determined by the minimum solution sample size needed to determine the protein concentration.

Protein solubilities determined by a rapid technique and modification of that technique to a micro-method

NASA Technical Reports Server (NTRS)

Cacioppo, Elizabeth; Pusey, Marc Lee; Munson, Sibyl

1989-01-01

A simple, rapid method for determination of protein solubilities has been developed which is based upon maximization of the free solution volume to be brought into equilibrium. The tetragonal lysozome solubility diagram has been determined from pH 4.0 to 5.2 (0.1 M sodium acetate), 2-7 percent NaCl, 3-25 C, and portions of the orthorhombic solubility diagram using this technique. Both tetragonal and orthorhombic solubilities were found to increase smoothly with decreasing salt concentration and increasing temperature; no retrograde solubilities were observed. Using column volumes of 75, 300, and 900 microliters, identical tetragonal lysozyme solubility diagrams were obtained. Chymotrypsinogen solubilities have also been determined using this apparatus, being retrograde over the temperature range tested. It is noted that the primary limiting factor in reducing the crystalline volume is the minimum solution sample size needed to accurately quantitate the protein.

The cosmic X-ray background-IRAS galaxy correlation and the local X-ray volume emissivity

NASA Technical Reports Server (NTRS)

Miyaji, Takamitsu; Lahav, Ofer; Jahoda, Keith; Boldt, Elihu

1994-01-01

We have cross-correlated the galaxies from the IRAS 2 Jy redshift survey sample and the 0.7 Jy projected sample with the all-sky cosmic X-ray background (CXB) map obtained from the High Energy Astronomy Observatory (HEAO) 1 A-2 experiment. We have detected a significant correlation signal between surface density of IRAS galaxies and the X-ray background intensity, with W(sub xg) = (mean value of ((delta I)(delta N)))/(mean value of I)(mean value of N)) of several times 10(exp -3). While this correlation signal has a significant implication for the contribution of the local universe to the hard (E greater than 2 keV) X-ray background, its interpretation is model-dependent. We have developed a formulation to model the cross-correlation between CXB surface brightness and galaxy counts. This includes the effects of source clustering and the X-ray-far-infrared luminosity correlation. Using an X-ray flux-limited sample of active galactic nuclei (AGNs), which has IRAS 60 micrometer measurements, we have estimated the contribution of the AGN component to the observed CXB-IRAS galaxy count correlations in order to see whether there is an excess component, i.e., contribution from low X-ray luminosity sources. We have applied both the analytical approach and Monte Carlo simulations for the estimations. Our estimate of the local X-ray volume emissivity in the 2-10 keV band is rho(sub x) approximately = (4.3 +/- 1.2) x 10(exp 38) h(sub 50) ergs/s/cu Mpc, consistent with the value expected from the luminosity function of AGNs alone. This sets a limit to the local volume emissivity from lower luminosity sources (e.g., star-forming galaxies, low-ionization nuclear emission-line regions (LINERs)) to rho(sub x) less than or approximately = 2 x 10(exp 38) h(sub 50) ergs/s/cu Mpc.

Accumulation of polycyclic aromatic hydrocarbons by Neocalanus copepods in Port Valdez, Alaska.

PubMed

Carls, Mark G; Short, Jeffrey W; Payne, James

2006-11-01

Sampling zooplankton is a useful strategy for observing trace hydrocarbon concentrations in water because samples represent an integrated average over a considerable effective sampling volume and are more representative of the sampled environment than discretely collected water samples. We demonstrate this method in Port Valdez, Alaska, an approximately 100 km(2) basin that receives about 0.5-2.4 kg of polynuclear aromatic hydrocarbons (PAH) per day. Total PAH (TPAH) concentrations (0.61-1.31 microg/g dry weight), composition, and spatial distributions in a lipid-rich copepod, Neocalanus were consistent with the discharge as the source of contamination. Although Neocalanus acquire PAH from water or suspended particulate matter, total PAH concentrations in these compartments were at or below method detection limits, demonstrating plankton can amplify trace concentrations to detectable levels useful for study.

A systematic investigation of sample diluents in modern supercritical fluid chromatography.

PubMed

Desfontaine, Vincent; Tarafder, Abhijit; Hill, Jason; Fairchild, Jacob; Grand-Guillaume Perrenoud, Alexandre; Veuthey, Jean-Luc; Guillarme, Davy

2017-08-18

This paper focuses on the possibility to inject large volumes (up to 10μL) in ultra-high performance supercritical fluid chromatography (UHPSFC) under generic gradient conditions. Several injection and method parameters have been individually evaluated (i.e. analyte concentration, injection volume, initial percentage of co-solvent in the gradient, nature of the weak needle wash solvent, nature of the sample diluent, nature of the column and of the analyte). The most critical parameters were further investigated using in a multivariate approach. The overall results suggested that several aprotic solvents including methyl tert-butyl ether (MTBE), dichloromethane, acetonitrile or cyclopentyl methyl ether (CPME) were well adapted for the injection of large volume in UHPSFC, while MeOH was generally the worst alternative. However, the nature of the stationary phase also had a strong impact and some of these diluents did not perform equally on each column. This was due to the existence of a competition in the adsorption of the analyte and the diluent on the stationary phase. This observation introduced the idea that the sample diluent should not only be chosen according to the analyte but also to the column chemistry to limit the interactions between the diluent and the ligands. Other important characteristics of the "ideal" SFC sample diluent were finally highlighted. Aprotic solvents with low viscosity are preferable to avoid strong solvent effects and viscous fingering, respectively. In the end, the authors suggest that the choice of the sample diluent should be part of the method development, as a function of the analyte and the selected stationary phase. Copyright © 2017 Elsevier B.V. All rights reserved.

A new solid phase microextraction method using organic ligand in micropipette tip syringe system packed with modified carbon cloth for preconcentration of cadmium in drinking water and blood samples of kidney failure patients.

PubMed

Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Salma Aslam; Naeemullah; Brahman, Kapil Dev; Arain, Mariam Shahzadi

2015-03-05

A simple and efficient miniaturized solid phase microextraction (M-SPμE) in a syringe system was developed for preconcentration of cadmium (Cd) in environmental and biological samples, followed by flame atomic absorption technique. The syringe system contains the micropipette tip packed with activated carbon cloth, coated with modified magnetic nanoparticles of iron oxide Triton X114 (ACC-NPs). Scanning electron microscopy and energy dispersive spectroscopy used for characterization of the size, morphology and elemental composition of ACC-NPs. The sample solution treated with a complexing reagent 8-hydroxyqunilone (8-HQ), and drawn into the syringe, filled with ACC-MNPs and dispensed manually for 2-10 drawing/discharging cycles. The analyte retained on ACC-NPs in micropipette tip-syringe system were then eluted with different volume of 1.5molL(-1) HCl by 1-5 drawing/discharging cycles. The syringe system directly couple with FAAS for analysis. The influence of different variables on the extraction efficiency of Cd, including adsorbent dosage, pH, sample volume, eluent volume and drawing/discharging cycles of syringe system were optimized. At optimized extraction conditions, the method showed good linearity in the range of 5-250μgL(-1), with a limit of detection 0.15μgL(-1). Repeatability of the extraction (%RSD) was <5%, n=5. The validity and accuracy of the method was checked by the certified reference materials. The proposed method was successfully applied for the determination of Cd in different drinking water and biological samples of kidney failure patients and healthy controls. Copyright © 2014 Elsevier B.V. All rights reserved.

A new solid phase microextraction method using organic ligand in micropipette tip syringe system packed with modified carbon cloth for preconcentration of cadmium in drinking water and blood samples of kidney failure patients

NASA Astrophysics Data System (ADS)

Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Salma Aslam; Naeemullah; Brahman, Kapil Dev; Arain, Mariam Shahzadi

2015-03-01

A simple and efficient miniaturized solid phase microextraction (M-SPμE) in a syringe system was developed for preconcentration of cadmium (Cd) in environmental and biological samples, followed by flame atomic absorption technique. The syringe system contains the micropipette tip packed with activated carbon cloth, coated with modified magnetic nanoparticles of iron oxide Triton X114 (ACC-NPs). Scanning electron microscopy and energy dispersive spectroscopy used for characterization of the size, morphology and elemental composition of ACC-NPs. The sample solution treated with a complexing reagent 8-hydroxyqunilone (8-HQ), and drawn into the syringe, filled with ACC-MNPs and dispensed manually for 2-10 drawing/discharging cycles. The analyte retained on ACC-NPs in micropipette tip-syringe system were then eluted with different volume of 1.5 mol L-1 HCl by 1-5 drawing/discharging cycles. The syringe system directly couple with FAAS for analysis. The influence of different variables on the extraction efficiency of Cd, including adsorbent dosage, pH, sample volume, eluent volume and drawing/discharging cycles of syringe system were optimized. At optimized extraction conditions, the method showed good linearity in the range of 5-250 μg L-1, with a limit of detection 0.15 μg L-1. Repeatability of the extraction (%RSD) was <5%, n = 5. The validity and accuracy of the method was checked by the certified reference materials. The proposed method was successfully applied for the determination of Cd in different drinking water and biological samples of kidney failure patients and healthy controls.

A novel method for the rapid determination of polyethoxylated tallow amine surfactants in water and sediment using large volume injection with high performance liquid chromatography and tandem mass spectrometry.

PubMed

Ross, Andrew R S; Liao, Xiangjun

2015-08-19

Polyethoxylated tallow amine (POEA) surfactants have been used in many glyphosate-based herbicide formulations for agricultural, industrial and residential weed control. The potential for release of these compounds into the environment is of increasing concern due to their toxicity towards aquatic organisms. Current methods for analysis of POEA surfactants require significant time and effort to achieve limits of quantification that are often higher than the concentrations at which biological effects have been observed (as low as 2 ng mL(-1)). We have developed a rapid and robust method for quantifying the POEA surfactant mixture MON 0818 at biologically relevant concentrations in fresh water, sea water and lake sediment using reversed phase high-performance liquid chromatography and electrospray ionization-tandem mass spectrometry. Water samples preserved by 1:1 v/v dilution with methanol are analyzed directly following centrifugation. Sediment samples undergo accelerated solvent extraction in aqueous methanol prior to analysis. Large volume (100 μL) sample injection and multiple reaction monitoring of a subset of the most abundant POEA homologs provide limits of quantification of 0.5 and 2.9 ng mL(-1) for MON 0818 in fresh water and sea water, respectively, and 2.5 ng g(-1) for total MON 0818 in lake sediment. Average recoveries of 93 and 75% were achieved for samples of water and sediment, respectively spiked with known amounts of MON 0818. Precision and accuracy for the analysis of water and sediment samples were within 10 and 16%, respectively based upon replicate analyses of calibration standards and representative samples. Results demonstrate the utility of the method for quantifying undegraded MON 0818 in water and sediment, although a more comprehensive method may be needed to identify and determine other POEA mixtures and degradation profiles that might occur in the environment. Crown Copyright © 2015. Published by Elsevier B.V. All rights reserved.

The white dwarfs within 25 pc of the Sun: Kinematics and spectroscopic subtypes

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

Sion, Edward M.; McCook, George P.; Wasatonic, Richard

2014-06-01

We present the fractional distribution of spectroscopic subtypes, range and distribution of surface temperatures, and kinematical properties of the white dwarfs (WDs) within 25 pc of the Sun. There is no convincing evidence of halo WDs in the total 25 pc sample of 224 WDs. There is also little to suggest the presence of genuine thick disk subcomponent members within 25 pc. It appears that the entire 25 pc sample likely belongs to the thin disk. We also find no significant kinematic differences with respect to spectroscopic subtypes. The total DA to non-DA ratio of the 25 pc sample ismore » 1.8, a manifestation of deepening envelope convection, which transforms DA stars with sufficiently thin H surface layers into non-DAs. We compare this ratio with the results of other studies. We find that at least 11% of the WDs within 25 pc of the Sun (the DAZ and DZ stars) have photospheric metals that likely originate from accretion of circumstellar material (debris disks) around them. If this interpretation is correct, then it suggests the possibility that a similar percentage have planets, asteroid-like bodies, or debris disks orbiting them. Our volume-limited sample reveals a pileup of DC WDs at the well-known cutoff in DQ WDs at T {sub eff} ∼ 6000 K. Mindful of small number statistics, we speculate on its possible evolutionary significance. We find that the incidence of magnetic WDs in the 25 pc sample is at least 8% in our volume-limited sample, dominated by cool WDs. We derive approximate formation rates of DB and DQ degenerates and present a preliminary test of the evolutionary scenario that all cooling DB stars become DQ WDs via helium convective dredge-up with the diffusion tail of carbon extending upward from their cores.« less

Adequacy in voided urine cytology specimens: The role of volume and a repeat void upon predictive values for high-grade urothelial carcinoma.

PubMed

VandenBussche, Christopher J; Rosenthal, Dorothy L; Olson, Matthew T

2016-03-01

Adequacy assessment is one of the most controversial and overlooked components in the daily practice of cytopathology, because it is generally determined from limited samples. Because voided urine varies widely in terms of its volume and cellularity, there is little consensus about the proper role for these variables in assessing specimen adequacy. In this study, the authors explored the role of volume in voided urine specimens to determine whether it plays a role in determining adequacy for the detection of high-grade urothelial carcinoma. Voided urine specimens received at the authors' laboratory over the 9.5 years since the introduction of the Johns Hopkins Template for Reporting Urinary Cytopathology were analyzed for correlations between volume, specimen adequacy, and the diagnosis of high-grade malignancy. The same data set also was queried to determine whether a patient who provided a voided low-volume specimen could yield a higher volume specimen and thereby increase adequacy. In total, 15,731 voided urine specimens with a cumulative volume of 891 liters originating from 8594 individual patients were analyzed. Specimen adequacy increased linearly for each increment of volume submitted to the laboratory up to 30 mL, after which the correlation was nonlinear. Low-volume specimens below this cutoff also had lower fractions of specimens that were diagnosed as malignant or suspicious. Volume is an important component in the evaluation of adequacy for voided urine cytology specimens. © 2015 American Cancer Society.

Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization.

PubMed

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei; Wang, Ruikang K

2013-02-01

Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo. Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations can result in local contrast degradation and non-uniform micro-angiogram images. In this paper, we propose a post-processing method that uses Rayleigh contrast-limited adaptive histogram equalization to increase the contrast and improve the overall appearance and uniformity of optical micro-angiograms without saturating the vessel intensity and changing the physical meaning of the micro-angiograms. The qualitative and quantitative performance of the proposed method is compared with those of common histogram equalization and contrast enhancement methods. We demonstrate that the proposed method outperforms other existing approaches. The proposed method is not limited to optical microangiography and can be used in other image modalities such as photo-acoustic tomography and scanning laser confocal microscopy.

Whispering gallery mode resonators for rapid label-free biosensing in small volume droplets.

PubMed

Wildgen, Sarah M; Dunn, Robert C

2015-03-23

Rapid biosensing requires fast mass transport of the analyte to the surface of the sensing element. To optimize analysis times, both mass transport in solution and the geometry and size of the sensing element need to be considered. Small dielectric spheres, tens of microns in diameter, can act as label-free biosensors using whispering gallery mode (WGM) resonances. WGM resonances are sensitive to the effective refractive index, which changes upon analyte binding to recognition sites on functionalized resonators. The spherical geometry and tens of microns diameter of these resonators provides an efficient target for sensing while their compact size enables detection in limited volumes. Here, we explore conditions leading to rapid analyte detection using WGM resonators as label-free sensors in 10 μL sample droplets. Droplet evaporation leads to potentially useful convective mixing, but also limits the time over which analysis can be completed. We show that active droplet mixing combined with initial binding rate measurements is required for accurate nanomolar protein quantification within the first minute following injection.

Copper(II)-rubeanic acid coprecipitation system for separation-preconcentration of trace metal ions in environmental samples for their flame atomic absorption spectrometric determinations.

PubMed

Soylak, Mustafa; Erdogan, Nilgun D

2006-09-21

A simple and facile preconcentration procedure based on the coprecipitation of trace heavy metal ions with copper(II)-rubeanic acid complex has been developed. The analytical parameters including pH, amounts of rubeanic acid, sample volume, etc. was investigated for the quantitative recoveries of Pb(II), Fe(III), Cd(II), Au(III), Pd(II) and Ni(II). No interferic effects were observed from the concomitant ions. The detection limits for analyte ions by 3 sigma were in the range of 0.14 microg/l for iron-3.4 microg/l for lead. The proposed coprecipitation method was successfully applied to water samples from Palas Lake-Kayseri, soil and sediment samples from Kayseri and Yozgat-Turkey.

A disposable sampling device to collect volume-measured DBS directly from a fingerprick onto DBS paper.

PubMed

Lenk, Gabriel; Sandkvist, Sören; Pohanka, Anton; Stemme, Göran; Beck, Olof; Roxhed, Niclas

2015-01-01

DBS samples collected from a fingerprick typically vary in volume and homogeneity and hence make an accurate quantitative analysis of DBS samples difficult. We report a prototype which first defines a precise liquid volume and subsequently stores it to a conventional DBS matrix. Liquid volumes of 2.2 µl ± 7.1% (n = 21) for deionized water and 6.1 µl ± 8.8% (n = 15) for whole blood have been successfully metered and stored in DBS paper. The new method of collecting a defined volume of blood by DBS sampling has the potential to reduce assay bias for the quantitative evaluation of DBS samples while maintaining the simplicity of conventional DBS sampling.

Brain Structure and Function Associated with a History of Sport Concussion: A Multi-Modal Magnetic Resonance Imaging Study.

PubMed

Churchill, Nathan; Hutchison, Michael; Richards, Doug; Leung, General; Graham, Simon; Schweizer, Tom A

2017-02-15

There is growing concern about the potential long-term consequences of sport concussion for young, currently active athletes. However, there remains limited information about brain abnormalities associated with a history of concussion and how they relate to clinical factors. In this study, advanced MRI was used to comprehensively describe abnormalities in brain structure and function associated with a history of sport concussion. Forty-three athletes (21 male, 22 female) were recruited from interuniversity teams at the beginning of the season, including 21 with a history of concussion and 22 without prior concussion; both groups also contained a balanced sample of contact and noncontact sports. Multi-modal MRI was used to evaluate abnormalities in brain structure and function. Athletes with a history of concussion showed frontal decreases in brain volume and blood flow. However, they also demonstrated increased posterior cortical volume and elevated markers of white matter microstructure. A greater number of prior concussions was associated with more extensive decreases in cerebral blood flow and insular volume, whereas recovery time from most recent concussion was correlated with reduced frontotemporal volume. White matter showed limited correlations with clinical factors, predominantly in the anterior corona radiata. This study provides the first evidence of the long-term effects of concussion on gray matter volume, blood flow, and white matter microstructure within a single athlete cohort. This was examined for a mixture of male and female athletes in both contact and noncontact sports, demonstrating the relevance of these findings for the overall sporting community.

EVALUATION OF VAPOR EQUILIBRATION AND IMPACT OF PURGE VOLUME ON SOIL-GAS SAMPLING RESULTS

EPA Science Inventory

Sequential sampling was utilized at the Raymark Superfund site to evaluate attainment of vapor equilibration and the impact of purge volume on soil-gas sample results. A simple mass-balance equation indicates that removal of three to five internal volumes of a sample system shou...

Measuring DAC metal-silicate partitioning experiments by electron microprobe: Thickness, fluorescence, and oxide spheres

NASA Astrophysics Data System (ADS)

Jennings, E. S.; Wade, J.; Laurenz, V.; Kearns, S.; Buse, B.; Rubie, D. C.

2017-12-01

The process by which the Earth's core segregated, and its resulting composition, can be inferred from the composition of the bulk silicate Earth if the partitioning of various elements into metal at relevant conditions is known. As such, partitioning experiments between liquid metal and liquid silicate over a wide range of pressures and temperatures are frequently performed to constrain the partitioning behaviour of many elements. The use of diamond anvil cell experiments to access more extreme conditions than those achievable by larger volume presses is becoming increasingly common. With a volume several orders of magnitude smaller than conventional samples, these experiments present unique analytical challenges. Typically, sample preparation is performed by FIB as a 2 mm thick slice, containing a small iron ball surrounded by a layer of silicate melt. This implies that analyses made by EPMA will be made near boundaries where fluoresced X-rays from the neighbouring phase may be significant. By measuring and simulating synthetic samples, we investigate thickness and fluorescence limitations. We find that for typical sample geometries, a thickness of 2 μm contains the entire analytical volume for standard 15kV analyses of metals. Fluoresced X-rays from light elements into the metal are below detection limits if there is no direct electron interaction with the silicate. Continuum fluorescence from higher atomic number elements from the metal into silicate poses significant difficulties [1]. This can cause metal-silicate partition coefficients of siderophile elements to be underestimated. Finally, we examine the origin and analytical consequences of oxide-rich exsolutions that are frequently found in the metal phase of such experiments. These are spherical with diameters of 100 nm and can be sparsely to densely packed. They appear to be carbon-rich and result in low analytical totals by violating the assumption of homogeneity in matrix corrections (e.g. φρz), which results in incorrect relative abundances. Using low kV analysis, we explore their origin i.e. whether they originate from quench exsolution or dynamic processes. Identifying their composition is key to understanding their origin and the interpretation of DAC experimental results.[1] Wade J & Wood B. J. (2012) PEPI 192-193, 54-58.

Pattern recognition of estradiol, testosterone and dihydrotestosterone in children's saliva samples using stochastic microsensors

NASA Astrophysics Data System (ADS)

Staden, Raluca-Ioana Stefan-Van; Gugoaşă, Livia Alexandra; Calenic, Bogdan; Legler, Juliette

2014-07-01

Stochastic microsensors based on diamond paste and three types of electroactive materials (maltodextrin (MD), α-cyclodextrin (α-CD) and 5,10,15,20-tetraphenyl-21H,23H porphyrin (P)) were developed for the assay of estradiol (E2), testosterone (T2) and dihydrotestosterone (DHT) in children's saliva. The main advantage of utilization of such tools is the possibility to identify and quantify all three hormones within minutes in small volumes of childen's saliva. The limits of quantification obtained for DHT, T2, and E2 (1 fmol/L for DHT, 1 pmol/L for T2, and 66 fmol/L for E2) determined using the proposed tools allows the utilization of these new methods with high reliability for the screening of saliva samples from children. This new method proposed for the assay of the three hormones overcomes the limitations (regarding limits of determination) of ELISA method which is the standard method used in clinical laboratories for the assay of DHT, T2, and E2 in saliva samples. The main feature of its utilization for children's saliva is to identify earlier problems related to early puberty and obesity.

A specific and sensitive HPLC-MS/MS micromethod for milrinone plasma levels determination after inhalation in cardiac patients.

PubMed

Gavra, Paul; Nguyen, Anne Q-N; Theoret, Yves; Litalien, Catherine; Denault, André Y; Varin, France

2014-10-01

Milrinone administered through inhalation is an emerging method aimed at specifically reducing pulmonary hypertension without affecting systemic pressures. Its administration has been shown to be useful both in patients undergoing cardiac surgery and for persistent pulmonary hypertension of the newborn. These populations are prone to receive many concomitant medications and/or blood sampling may require a low volume quantification method. To address these issues in view of pharmacokinetic studies, this article aims to develop and validate a specific and sensitive analytical assay using high performance liquid chromatography (HPLC) and tandem mass spectrometry (MS/MS) detection for the quantification of milrinone plasma concentrations after inhalation in patients undergoing cardiac surgery. Plasma samples (50 μL) were extracted using ethyl acetate. Milrinone was separated on a C18 analytical column at 50°C. The mobile phase consisted of methanol and 10 mM ammonium acetate (45:55 vol/vol). The electrospray was operated in the negative ionization mode and monitored the following mass transitions: m/z 212.1 → 140.0 at 36 eV for milrinone and m/z 252.1 → 156.1 at 32 eV for olprinone. Calibration curves followed a quadratic regression in the concentration range of 0.3125-640 ng/mL. The lower limit of quantification is 0.3125 ng/mL and is based on a low plasma volume of 50 μL. Mean drug recovery and accuracy were ≥72.3% and 96.0%, respectively. Intraday and interday precision coefficient of variation (%) was ≤7.4% and ≤11.5%, respectively. The specificity allowed milrinone quantification in the multidrug administration conditions of cardiopulmonary bypass. This validated micromethod proved to be highly sensitive and specific while using a low volume of plasma. Its low volume and its lower limit of quantification indicate that this approach is suitable for further characterization of milrinone pharmacokinetics in both adults (inhalation) and neonates.

Rheology of Foam Near the Order-Disorder Transition

NASA Technical Reports Server (NTRS)

Holt, R. Glynn; McDaniel, J. Gregory

2001-01-01

The first part of our research results are summarized in the recent journal publication: J. Gregory McDaniel and R. Glynn Holt, 'Measurement of aqueous foam rheology by acoustic levitation', Phys. Rev. E 61, 2204 (2000). This aspect of the work was a combination of experiment and analysis. We built a levitation system capable of acoustically levitating small samples of aqueous foam of arbitrary gas and liquid volume fractions. We then modulated the acoustic field to induce normal mode oscillations of the foam samples. The observables from the experiment were frequency and mode number. For dry (roughly > 70% gas by volume) foams and small deformations, we developed an effective medium, normal-modes analysis which took the frequency and mode number from experiment, and gave us the shear elastic modulus of the foam as a function of Poisson's ratio. The second part of our results may be found in a soon-to-be submitted manuscript 'Dynamics of aqueous foam drops', I.Sh. Akhatov, J.G. McDaniel and R.G. Holt, describing our modeling in the wet foam limit by considering the acoustic problem. This aspect of the research is purely theoretical. Beginning from a mass-conserving mixture law, the fully nonlinear equations of motion for a wet (roughly < 10% gas by volume) foam drop of initially spherical shape were derived. The frequencies for normal mode oscillations were derived in the linear inviscid limit. The nonlinear equations were numerically solved to elicit the motion of a foam drop under acoustic excitation. The role of the time-varying void fraction in breathing-mode oscillations is of particular interest. As of the end of the current (NAG#3-2121) grant, this work was not yet concluded. We continue to work on this aspect in order to extend the analysis to cover the transition regime of gas volume fractions, as well as to compare to experiments in the wet regime.

Simple semi-automated portable capillary electrophoresis instrument with contactless conductivity detection for the determination of β-agonists in pharmaceutical and pig-feed samples.

PubMed

Nguyen, Thi Anh Huong; Pham, Thi Ngoc Mai; Doan, Thi Tuoi; Ta, Thi Thao; Sáiz, Jorge; Nguyen, Thi Quynh Hoa; Hauser, Peter C; Mai, Thanh Duc

2014-09-19

An inexpensive, robust and easy to use portable capillary electrophoresis instrument with miniaturized high-voltage capacitively coupled contactless conductivity detection was developed. The system utilizes pneumatic operation to manipulate the solutions for all flushing steps. The different operations, i.e. capillary flushing, interface rinsing, and electrophoretic separation, are easily activated by turning an electronic switch. To allow the analysis of samples with limited available volume, and to render the construction less complicated compared to a computer-controlled counterpart, sample injection is carried out hydrodynamically directly from the sample vial into the capillary by manual syphoning. The system is a well performing solution where the financial means for the highly expensive commercial instruments are not available and where the in-house construction of a sophisticated automated instrument is not possible due to limited mechanical and electronic workshop facilities and software programming expertise. For demonstration, the system was employed successfully for the determination of some β-agonists, namely salbutamol, metoprolol and ractopamine down to 0.7ppm in pharmaceutical and pig-feed sample matrices in Vietnam. Copyright © 2014 Elsevier B.V. All rights reserved.

Procedure for chromatography involving sample solvent with higher elution strength than the mobile phase.

PubMed

Patil, Nitin S; Mendhe, Rakesh B; Sankar, Ajeet A; Iyer, Harish

2008-01-11

In preparative chromatography, often the solubility of the sample in the mobile phase is limited, making the mobile phase unsuitable as a solvent for preparation of load. Generally, solvents that have high solubility for the sample also have higher elution strengths than the mobile phase. Additionally, at high loading volumes, these strong sample solvents are known to adversely affect the band profiles leading to poor chromatographic performance. Here, we show that controlling the mobile phase strength during loading and post-load elution resulted in improved band profiles when the sample solvent was stronger than the mobile phase. Such an approach improves performance in preparative chromatography by allowing either higher sample loading or higher organic content in mobile phase (without loss of yield). Alternately, the approach can be used for improvement in performance by increase in yield or product purity.

Standard error of estimated average timber volume per acre under point sampling when trees are measured for volume on a subsample of all points.

Treesearch

Floyd A. Johnson

1961-01-01

This report assumes a knowledge of the principles of point sampling as described by Grosenbaugh, Bell and Alexander, and others. Whenever trees are counted at every point in a sample of points (large sample) and measured for volume at a portion (small sample) of these points, the sampling design could be called ratio double sampling. If the large...

Two-dimensional Topology of the Sloan Digital Sky Survey

NASA Astrophysics Data System (ADS)

Hoyle, Fiona; Vogeley, Michael S.; Gott, J. Richard, III; Blanton, Michael; Tegmark, Max; Weinberg, David H.; Bahcall, N.; Brinkmann, J.; York, D.

2002-12-01

We present the topology of a volume-limited sample of 11,884 galaxies, selected from an apparent magnitude limited sample of over 100,000 galaxies observed as part of the Sloan Digital Sky Survey (SDSS). The data currently cover three main regions on the sky: one in the Galactic north and one in the south, both at zero degrees declination, and one area in the north at higher declination. Each of these areas covers a wide range of survey longitude but a narrow range of survey latitude, allowing the two-dimensional genus to be measured. The genus curves of the SDSS subsamples are similar, after appropriately normalizing these measurements for the different areas. We sum the genus curves from the three areas to obtain the total genus curve of the SDSS. The total curve has a shape similar to the genus curve derived from mock catalogs drawn from the Hubble volume ΛCDM simulation and is similar to that of a Gaussian random field. Likewise, comparison with the genus of the Two-Degree Field Galaxy Redshift Survey, after normalization for the difference in area, reveals remarkable similarity in the topology of these samples. We test for the effects of galaxy-type segregation by splitting the SDSS data into thirds, based on the u*-r* colors of the galaxies, and measure the genus of the reddest and bluest subsamples. This red/blue split in u*-r* is essentially a split by morphology, as explained by Strateva and coworkers. We find that the genus curve for the reddest galaxies exhibits a ``meatball'' shift of the topology-reflecting the concentration of red galaxies in high-density regions-compared to the bluest galaxies and the full sample, in agreement with predictions from simulations.

[Determination of four phenolic endocrine disruptors in environmental water samples by high performance liquid chromatography-fluorescence detection using dispersive liquid-liquid microextraction coupled with derivatization].

PubMed

Wang, Xiaoyan; Qi, Weimei; Zhao, Xian'en; Lü, Tao; Wang, Xiya; Zheng, Longfang; Yan, Yehao; You, Jinmao

2014-06-01

To achieve accurate, fast and sensitive detection of phenolic endocrine disruptors in small volume of environmental water samples, a method of dispersive liquid-liquid microextraction (DLLME) coupled with fluorescent derivatization was developed for the determination of bisphenol A, nonylphenol, octylphenol and 4-tert-octylphenol in environmental water samples by high performance liquid chromatography-fluorescence detection (HPLC-FLD). The DLLME and derivatization conditions were investigated, and the optimized DLLME conditions for small volume of environmental water samples (pH 4.0) at room temperature were as follows: 70 microL chloroform as extraction solvent, 400 microL acetonitrile as dispersing solvent, vortex mixing for 3 min, and then high-speed centrifugation for 2 min. Using 2-[2-(7H-dibenzo [a, g] carbazol-7-yl)-ethoxy] ethyl chloroformate (DBCEC-Cl) as precolumn derivatization reagent, the stable derivatives of the four phenolic endocrine disruptors were obtained in pH 10.5 Na2CO3-NaHCO3 buffer/acetonitrile at 50 degrees C for 3 min, and then separated within 10 min by HPLC-FLD. The limits of detection (LODs) were in the range of 0.9-1.6 ng/L, and the limits of quantification (LOQs) were in the range of 3.8-7.1 ng/L. This method had perfect linearity, precision and recovery results, and showed obvious advantages and practicality comparing to the previously reported methods. It is a convenient and validated method for the routine analysis of phenolic endocrine disruptors in waste water of paper mill, lake water, domestic wastewater, tap water, etc.

Concentration of Enteroviruses, Adenoviruses, and Noroviruses from Drinking Water by Use of Glass Wool Filters▿

PubMed Central

Lambertini, Elisabetta; Spencer, Susan K.; Bertz, Phillip D.; Loge, Frank J.; Kieke, Burney A.; Borchardt, Mark A.

2008-01-01

Available filtration methods to concentrate waterborne viruses are either too costly for studies requiring large numbers of samples, limited to small sample volumes, or not very portable for routine field applications. Sodocalcic glass wool filtration is a cost-effective and easy-to-use method to retain viruses, but its efficiency and reliability are not adequately understood. This study evaluated glass wool filter performance to concentrate the four viruses on the U.S. Environmental Protection Agency contaminant candidate list, i.e., coxsackievirus, echovirus, norovirus, and adenovirus, as well as poliovirus. Total virus numbers recovered were measured by quantitative reverse transcription-PCR (qRT-PCR); infectious polioviruses were quantified by integrated cell culture (ICC)-qRT-PCR. Recovery efficiencies averaged 70% for poliovirus, 14% for coxsackievirus B5, 19% for echovirus 18, 21% for adenovirus 41, and 29% for norovirus. Virus strain and water matrix affected recovery, with significant interaction between the two variables. Optimal recovery was obtained at pH 6.5. No evidence was found that water volume, filtration rate, and number of viruses seeded influenced recovery. The method was successful in detecting indigenous viruses in municipal wells in Wisconsin. Long-term continuous filtration retained viruses sufficiently for their detection for up to 16 days after seeding for qRT-PCR and up to 30 days for ICC-qRT-PCR. Glass wool filtration is suitable for large-volume samples (1,000 liters) collected at high filtration rates (4 liters min−1), and its low cost makes it advantageous for studies requiring large numbers of samples. PMID:18359827

Methods to enhance seismic faults and construct fault surfaces

NASA Astrophysics Data System (ADS)

Wu, Xinming; Zhu, Zhihui

2017-10-01

Faults are often apparent as reflector discontinuities in a seismic volume. Numerous types of fault attributes have been proposed to highlight fault positions from a seismic volume by measuring reflection discontinuities. These attribute volumes, however, can be sensitive to noise and stratigraphic features that are also apparent as discontinuities in a seismic volume. We propose a matched filtering method to enhance a precomputed fault attribute volume, and simultaneously estimate fault strikes and dips. In this method, a set of efficient 2D exponential filters, oriented by all possible combinations of strike and dip angles, are applied to the input attribute volume to find the maximum filtering responses at all samples in the volume. These maximum filtering responses are recorded to obtain the enhanced fault attribute volume while the corresponding strike and dip angles, that yield the maximum filtering responses, are recoded to obtain volumes of fault strikes and dips. By doing this, we assume that a fault surface is locally planar, and a 2D smoothing filter will yield a maximum response if the smoothing plane coincides with a local fault plane. With the enhanced fault attribute volume and the estimated fault strike and dip volumes, we then compute oriented fault samples on the ridges of the enhanced fault attribute volume, and each sample is oriented by the estimated fault strike and dip. Fault surfaces can be constructed by directly linking the oriented fault samples with consistent fault strikes and dips. For complicated cases with missing fault samples and noisy samples, we further propose to use a perceptual grouping method to infer fault surfaces that reasonably fit the positions and orientations of the fault samples. We apply these methods to 3D synthetic and real examples and successfully extract multiple intersecting fault surfaces and complete fault surfaces without holes.

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

Egorov, Oleg; O'Hara, Matthew J.; Grate, Jay W.

An automated fluidic instrument is described that rapidly determines the total 99Tc content of aged nuclear waste samples, where the matrix is chemically and radiologically complex and the existing speciation of the 99Tc is variable. The monitor links microwave-assisted sample preparation with an automated anion exchange column separation and detection using a flow-through solid scintillator detector. The sample preparation steps acidify the sample, decompose organics, and convert all Tc species to the pertechnetate anion. The column-based anion exchange procedure separates the pertechnetate from the complex sample matrix, so that radiometric detection can provide accurate measurement of 99Tc. We developed amore » preprogrammed spike addition procedure to automatically determine matrix-matched calibration. The overall measurement efficiency that is determined simultaneously provides a self-diagnostic parameter for the radiochemical separation and overall instrument function. Continuous, automated operation was demonstrated over the course of 54 h, which resulted in the analysis of 215 samples plus 54 hly spike-addition samples, with consistent overall measurement efficiency for the operation of the monitor. A sample can be processed and measured automatically in just 12.5 min with a detection limit of 23.5 Bq/mL of 99Tc in low activity waste (0.495 mL sample volume), with better than 10% RSD precision at concentrations above the quantification limit. This rapid automated analysis method was developed to support nuclear waste processing operations planned for the Hanford nuclear site.« less

Dispersive liquid-liquid microextraction of lead(II) as 5-(4-dimethylaminobenzylidene) rhodanine chelates from food and water samples.

PubMed

Alothman, Zeid A; Al-Shaalan, Nora H; Habila, Mohamed A; Unsal, Yunus E; Tuzen, Mustafa; Soylak, Mustafa

2015-02-01

A dispersive liquid-liquid microextraction procedure for lead(II) as its 5-(4-dimethylaminobenzylidene) rhodanine complex has been established prior to its microsampling flame atomic absorption spectrometric determination. The influences of various analytical parameters including pH, solvent type and volume, dispersive solvent type and volume, 5-(4-dimethylaminobenzylidene) rhodanine amount, salt effect, and centrifugation time and speed were investigated. The effects of certain alkali, alkaline earth, and transition metal ions on the quantitative extraction of lead(II) were also studied. Quantitative recoveries were obtained at pH 6. The enrichment factor was calculated as 125. The detection limit for lead is 1.1 μg/L. The accuracy of the method was tested with the additions recovery test and analysis of the standard reference materials (SPS-WW2 waste water, NIST SRM 1515 apple leaves, and TMDA-51.3 fortified water). Applications of the present procedure were tested by analyzing water and food samples.

RELIABILITY OF THE DETECTION OF THE BARYON ACOUSTIC PEAK

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

MartInez, Vicent J.; Arnalte-Mur, Pablo; De la Cruz, Pablo

2009-05-01

The correlation function of the distribution of matter in the universe shows, at large scales, baryon acoustic oscillations, which were imprinted prior to recombination. This feature was first detected in the correlation function of the luminous red galaxies of the Sloan Digital Sky Survey (SDSS). Recently, the final release (DR7) of the SDSS has been made available, and the useful volume is about two times bigger than in the old sample. We present here, for the first time, the redshift-space correlation function of this sample at large scales together with that for one shallower, but denser volume-limited subsample drawn frommore » the Two-Degree Field Redshift Survey. We test the reliability of the detection of the acoustic peak at about 100 h {sup -1} Mpc and the behavior of the correlation function at larger scales by means of careful estimation of errors. We confirm the presence of the peak in the latest data although broader than in previous detections.« less

Exchange coupling interaction in L10-FePd/α-Fe nanocomposite magnets with large maximum energy products.

PubMed

Sakuma, Noritsugu; Ohshima, Tsubasa; Shoji, Tetsuya; Suzuki, Yoshihito; Sato, Ryota; Wachi, Ayako; Kato, Akira; Kawai, Yoichiro; Manabe, Akira; Teranishi, Toshiharu

2011-04-26

Nanocomposite magnets (NCMs) consisting of hard and soft magnetic phases are expected to be instrumental in overcoming the current theoretical limit of magnet performance. In this study, structural analyses were performed on L1(0)-FePd/α-Fe NCMs with various hard/soft volume fractions, which were formed by annealing Pd/γ-Fe(2)O(3) heterostructured nanoparticles and pure Pd nanoparticles. The sample with a hard/soft volume ratio of 82/18 formed by annealing at 773 K had the largest maximum energy product (BH(max) = 10.3 MGOe). In such a sample, the interface between the hard and soft phases was coherent and the phase sizes were optimized, both of which effectively induced exchange coupling. This exchange coupling was directly observed by visualizing the magnetic interaction between the hard and soft phases using a first-order reversal curve diagram, which is a valuable tool to improve the magnetic properties of NCMs.

Pyridine-functionalized Fe₃O₄ nanoparticles as a novel sorbent for the preconcentration of lead and cadmium ions in tree leaf as a bioindicator of urban traffic pollution.

PubMed

Sayar, Omid; Zhad, Hamid Reza Lotfi Zadeh; Sadeghi, Omid; Amani, Vahid; Najafi, Ezzatolla; Tavassoli, Najmeh

2012-12-01

We have developed a facile and highly sensitive sorbent for cadmium and lead ions. It is based on Fe₃O₄ nanoparticles functionalized with a derivative of picoline and was characterized by scanning electron microscopy, differential thermographic analysis, and elemental analysis. The material can be applied to the preconcentration of lead and cadmium ions. Factors such as the type, concentration and volume of eluent, the pH of the sample solution, the time for extraction, and the volume of the sample were studied. The effects of a variety of ions on preconcentration and recovery of these ions were also investigated. The ions were determined by FAAS, and the limits of detection are <0.8 and <0.061 μg L⁻¹ for lead and cadmium, respectively. Recoveries and precisions are >98.0 % and <1.3 %, respectively. The method was validated by analyzing several certified leaf reference materials.

Selective extraction based on poly(MAA-VB-EGMDA) monolith followed by HPLC for determination of hordenine in plasma and urine samples.

PubMed

Chen, Yonggang; Meng, Junhua; Zou, Jili; An, Jing

2015-06-01

Hordenine is an active compound found in several foods, herbs and beer. In this work, a novel sorbent was fabricated for selective solid-phase extraction (SPE) of hordenine in biological samples. The organic polymer sorbent was synthesized in one step in the plastic barrel of a syringe by a pre-polymerization solution consisting of methacrylic acid (MAA), 4-vinylphenylboronic acid (VB) and ethylene glycol dimethacrylate (EGDMA). The conditions for preparation were optimized to generate a poly(MAA-VB-EGMDA) monolith with good permeability. The monolith exhibited good enrichment efficiency towards hordenine. By using tyramine as the internal standard, a poly(MAA-VB-EGMDA)-based SPE-HPLC method was established for analysis of hordenine. Conditions for SPE, including volume of eluting solvent, pH of sample solution, sampling rate and sample volume, were optimized. The proposed SPE-HPLC method presented good linearity (R(2)  = 0.9992) within 10-2000 ng/mL and the detection limits was 3 ng/mL, which is significantly more sensitive than reported methods. The method was also applied in plasma and urine samples; good capability of removing matrices was observed, while hordenine in low content was well extracted and enriched. The recoveries were from 90.6 to 94.7% and from 89.3 to 91.5% for the spiked plasma and urine samples, respectively, with the relative standard deviations <4.7%. Copyright © 2014 John Wiley & Sons, Ltd.

Simple and quick determination of analgesics and other contaminants of emerging concern in environmental waters by on-line solid phase extraction coupled to liquid chromatography-tandem mass spectrometry.

PubMed

Ferrer-Aguirre, Alejandra; Romero-González, Roberto; Vidal, J L Martínez; Frenich, Antonia Garrido

2016-05-13

A simple and quick analytical method has been developed for the determination of pharmaceutical compounds in water. An on-line solid-phase extraction (SPE) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been optimized to determine 7 contaminants of emerging concern in environmental waters at ngL(-1) levels. This procedure requires minimal sample handling and small sample volume (900μL) with a total running time of 18min. Several SPE parameters were evaluated and optimized in order to achieve a high sample throughput. Therefore sample volume, carryover and reusability of the cartridges were evaluated. Performance characteristics were evaluated and good linearity was obtained (R(2)>0.98). Recoveries were evaluated in spiked samples at three concentrations and the values ranged from 71 to 104%. Intra and inter-day precision was lower than 10 and 13% respectively. Limits of quantification were equal to or lower than 10ngL(-1), except for 1,7-dimethylxanthine (20ngL(-1)) and ibuprofen (50ngL(-1)). The method was applied to 20 environmental water samples, and ibuprofen was the compound most widely detected at concentrations up to 42.06μgL(-1), whereas the other compounds were detected in fewer samples at lower concentrations (up to 15.99μgL(-1)). Copyright © 2016 Elsevier B.V. All rights reserved.

Sample preconcentration with chemical derivatization in capillary electrophoresis. Capillary as preconcentrator, microreactor and chiral selector for high-throughput metabolite screening.

PubMed

Ptolemy, Adam S; Britz-McKibbin, Philip

2006-02-17

New strategies for integrating sample pretreatment with chemical analyses under a single format is required for rapid, sensitive and enantioselective analyses of low abundance metabolites in complex biological samples. Capillary electrophoresis (CE) offers a unique environment for controlling analyte/reagent band dispersion and electromigration properties using discontinuous electrolyte systems. Recent work in our laboratory towards developing a high-throughput CE platform for low abundance metabolites via on-line sample preconcentration with chemical derivatization (SPCD) is primarily examined in this review, as there have been surprisingly only a few strategies reported in the literature to date. In-capillary sample preconcentration serves to enhance concentration sensitivity via electrokinetic focusing of long sample injection volumes for lower detection limits, whereas chemical derivatization by zone passing is used to expand detectability and selectivity, notably for enantiomeric resolution of metabolites lacking intrinsic chromophores using nanolitre volumes of reagent. Together, on-line SPCD-CE can provide over a 100-fold improvement in concentration sensitivity, shorter total analysis times, reduced sample handling and improved reliability for a variety of amino acid and amino sugar metabolites, which is also amenable to automated high-throughput screening. This review will highlight basic method development and optimization parameters relevant to SPCD-CE, including applications to bacterial metabolite flux and biomarker analyses. Insight into the mechanism of analyte focusing and labeling by SPCD-CE is also discussed, as well as future directions for continued research.

Dielectric Spectroscopy of Semiconductors.

DTIC Science & Technology

1985-05-01

PRGRAM ELEMET.PROJCT AScong. 4AREA AWORK UNIT NUNSCrS Chelsa Cble" .11. 02AUniversity of London 110B5-3 London, UK _ _ _ _ _ _ _ 11. CONTROLLING OFFICE...volume of the material in which "incomplete dc transport" is taking place, charges beirg prevented from freely crossing the sample from one electrode...process. The limitation of the method arises from the dark current and from the need to cool to sufficiently low temperature to prevent re-emission

Dependence of Some Properties of Groups on Group Local Number Density

NASA Astrophysics Data System (ADS)

Deng, Xin-Fa; Wu, Ping

2014-09-01

In this study we investigate the dependence of projected size Sizesky, and rms deviation σR of projected distance in the sky from the group center, rms velocities σV , and virial radius RVir of groups on group local number density. In the volume-limited group samples, it is found that groups in high density regions preferentially have larger Sizesky, σR , σV , and RVir than ones in low density regions.

17 CFR 240.6a-1 - Application for registration as a national securities exchange or exemption from registration...

Code of Federal Regulations, 2010 CFR

2010-04-01

... as a national securities exchange or exemption from registration based on limited volume. 240.6a-1... national securities exchange or exemption from registration based on limited volume. (a) An application for registration as a national securities exchange, or for exemption from such registration based on limited volume...

17 CFR 240.6a-1 - Application for registration as a national securities exchange or exemption from registration...

Code of Federal Regulations, 2011 CFR

2011-04-01

... as a national securities exchange or exemption from registration based on limited volume. 240.6a-1... national securities exchange or exemption from registration based on limited volume. (a) An application for registration as a national securities exchange, or for exemption from such registration based on limited volume...

Active sampling technique to enhance chemical signature of buried explosives

NASA Astrophysics Data System (ADS)

Lovell, John S.; French, Patrick D.

2004-09-01

Deminers and dismounted countermine engineers commonly use metal detectors, ground penetrating radar and probes to locate mines. Many modern landmines have a very low metal content, which severely limits the effectiveness of metal detectors. Canines have also been used for landmine detection for decades. Experiments have shown that canines smell the explosives which are known to leak from most types of landmines. The fact that dogs can detect landmines indicates that vapor sensing is a viable approach to landmine detection. Several groups are currently developing systems to detect landmines by "sniffing" for the ultra-trace explosive vapors above the soil. The amount of material that is available to passive vapor sensing systems is limited to no more than the vapor in equilibrium with the explosive related chemicals (ERCs) distributed in the surface soils over and near the landmine. The low equilibrium vapor pressure of TNT in the soil/atmosphere boundary layer and the limited volume of the boundary layer air imply that passive chemical vapor sensing systems require sensitivities in the picogram range, or lower. ADA is working to overcome many of the limitations of passive sampling methods, by the use of an active sampling method that employs a high-powered (1,200+ joules) strobe lamp to create a highly amplified plume of vapor and/or ERC-bearing fine particulates. Initial investigations have demonstrated that this approach can amplify the detectability of TNT by two or three orders of magnitude. This new active sampling technique could be used with any suitable explosive sensor.

An assessment of the potential of laser-induced breakdown spectroscopy (LIBS) for the analysis of cesium in liquid samples of biological origin.

PubMed

Metzinger, Anikó; Kovács-Széles, Eva; Almási, István; Galbács, Gábor

2014-01-01

The present study describes the development of an analytical method for the determination of cesium in biological fluid samples (human urine and blood samples) by laser-induced breakdown spectroscopy (LIBS). The developed method is based on sample presentation by liquid-to-solid conversion, enhancing the emission signal by drying the liquid into small "pockets" created in a metal support (zinc plate), and allows the analysis to be carried out on as little as 1 μL of sample volume, in a closed sample cell. Absolute detection limits on the Cs I 852.1 nm spectral line were calculated by the IUPAC 3σ method to be 6 ng in the urine sample and 27 ng in the blood serum sample. It is estimated that LIBS may be used to detect highly elevated concentration levels of Cs in fluid samples taken from people potentially exposed to surges of Cs from non-natural sources.

Chapter 3. Determination of semivolatile organic compounds and polycyclic aromatic hydrocarbons in solids by gas chromatography/mass spectrometry

USGS Publications Warehouse

Zaugg, Steven D.; Burkhardt, Mark R.; Burbank, Teresa L.; Olson, Mary C.; Iverson, Jana L.; Schroeder, Michael P.

2006-01-01

A method for the determination of 38 polycyclic aromatic hydrocarbons (PAHs) and semivolatile organic compounds in solid samples is described. Samples are extracted using a pressurized solvent extraction system. The compounds of interest are extracted from the solid sample twice at 13,800 kilopascals; first at 120 degrees Celsius using a water/isopropyl alcohol mixture (50:50, volume-to-volume ratio), and then the sample is extracted at 200 degrees Celsius using a water/isopropyl alcohol mixture (80:20, volume-to-volume ratio). The compounds are isolated using disposable solid-phase extraction (SPE) cartridges containing divinylbenzene-vinylpyrrolidone copolymer resin. The cartridges are dried with nitrogen gas, and then sorbed compounds are eluted from the SPE material using a dichloromethane/diethyl ether mixture (80:20, volume-to-volume ratio) and passed through a sodium sulfate/Florisil SPE cartridge to remove residual water and to further clean up the extract. The concentrated extract is solvent exchanged into ethyl acetate and the solvent volume reduced to 0.5 milliliter. Internal standard compounds are added prior to analysis by capillary-column gas chromatography/mass spectrometry. Comparisons of PAH data for 28 sediment samples extracted by Soxhlet and the accelerated solvent extraction (ASE) method described in this report produced similar results. Extraction of PAH compounds from standard reference material using this method also compared favorably with Soxhlet extraction. The recoveries of PAHs less than molecular weight 202 (pyrene or fluoranthene) are higher by up to 20 percent using this ASE method, whereas the recoveries of PAHs greater than or equal to molecular weight 202 are equivalent. This ASE method of sample extraction of solids has advantages over conventional Soxhlet extraction by increasing automation of the extraction process, reducing extraction time, and using less solvent. Extract cleanup also is greatly simplified because SPE replaces commonly used gel permeation chromatography. The performance of the method (as expressed by mean recoveries and mean precision) was determined using Ottawa sand, a commercially available topsoil, and an environmental stream sediment, fortified at 1.5 and 15 micrograms per compound. Recoveries of PAH and semivolatile compounds in Ottawa sand samples fortified at 1.5 micrograms averaged 88 percent ? 9.4 percent relative standard deviation, and calculated initial method detection limits per compound averaged 14 micrograms per kilogram, assuming a 25-gram sample size. The recovery for 1,2,4-trichlorobenzene is less than 60 percent; thus, the concentration of this compound will always be reported as estimated with the E remark code. The analysis of 25 alkylated PAH homolog groups also can be determined with this method with extra data analysis and review, but because of the lack of authentic reference standard compounds, these results are considered to be semiquantitative. The PAH homolog groups are quantitated using the response factor of a parent PAH method compound, if available. Precision data for the alkylated PAH homologs detected in a marine sediment standard reference material (SRM 1944) also are presented to document and demonstrate method capability.

Perils of categorical thinking: "Oxic/anoxic" conceptual model in environmental remediation

USGS Publications Warehouse

Bradley, Paul M.

2012-01-01

Given ambient atmospheric oxygen concentrations of about 21 percent (by volume), the lower limit for reliable quantitation of dissolved oxygen concentrations in groundwater samples is in the range of 0.1–0.5 mg/L. Frameworks for assessing in situ redox condition are often applied using a simple two-category (oxic/anoxic) model of oxygen condition. The "oxic" category defines the environmental range in which dissolved oxygen concentrations are clearly expected to impact contaminant biodegradation, either by supporting aerobic biodegradation of electron-donor contaminants like petroleum hydrocarbons or by inhibiting anaerobic biodegradation of electron-acceptor contaminants like chloroethenes. The tendency to label the second category "anoxic" leads to an invalid assumption that oxygen is insignificant when, in fact, the dissolved oxygen concentration is less than detection but otherwise unknown. Expressing dissolved oxygen concentrations as numbers of molecules per volume, dissolved oxygen concentrations that fall below the 0.1 mg/L field detection limit range from 1 to 1017 molecules/L. In light of recent demonstrations of substantial oxygen-linked biodegradation of chloroethene contaminants at dissolved oxygen concentrations well below the 0.1–0.5 mg/L field detection limit, characterizing "less than detection" oxygen concentrations as "insignificant" is invalid.

Hydrodynamic injection with pneumatic valving for microchip electrophoresis with total analyte utilization

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

Sun, Xuefei; Kelly, Ryan T.; Danielson, William F.

2011-04-26

A novel hydrodynamic injector that is directly controlled by a pneumatic valve has been developed for reproducible microchip capillary electrophoresis (CE) separations. The poly(dimethylsiloxane) (PDMS) devices used for evaluation comprise a separation channel, a side channel for sample introduction, and a pneumatic valve aligned at the intersection of the channels. A low pressure (≤ 3 psi) applied to the sample reservoir is sufficient to drive sample into the separation channel. The rapidly actuated pneumatic valve enables injection of discrete sample plugs as small as ~100 pL for CE separation. The injection volume can be easily controlled by adjusting the intersectionmore » geometry, the solution back pressure and the valve actuation time. Sample injection could be reliably operated at different frequencies (< 0.1 Hz to >2 Hz) with good reproducibility (peak height relative standard deviation ≤ 3.6%) and no sampling biases associated with the conventional electrokinetic injections. The separation channel was dynamically coated with a cationic polymer, and FITC-labeled amino acids were employed to evaluate the CE separation. Highly efficient (≥ 7.0 × 103 theoretical plates for the ~2.4 cm long channel) and reproducible CE separations were obtained. The demonstrated method has numerous advantages compared with the conventional techniques, including repeatable and unbiased injections, no sample waste, high duty cycle, controllable injected sample volume, and fewer electrodes with no need for voltage switching. The prospects of implementing this injection method for coupling multidimensional separations, for multiplexing CE separations and for sample-limited bioanalyses are discussed.« less

Earth Entry Vehicle Design for Sample Return Missions Using M-SAPE

NASA Technical Reports Server (NTRS)

Samareh, Jamshid

2015-01-01

Most mission concepts that return sample material to Earth share one common element: an Earth entry vehicle (EEV). The primary focus of this paper is the examination of EEV design space for relevant sample return missions. Mission requirements for EEV concepts can be divided into three major groups: entry conditions (e.g., velocity and flight path angle), payload (e.g., mass, volume, and g-load limit), and vehicle characteristics (e.g., thermal protection system, structural topology, and landing concepts). The impacts of these requirements on the EEV design have been studied with an integrated system analysis tool, and the results will be discussed in details. In addition, through sensitivities analyses, critical design drivers that have been identified will be reviewed.

Fishing in the Water: Effect of Sampled Water Volume on Environmental DNA-Based Detection of Macroinvertebrates.

PubMed

Mächler, Elvira; Deiner, Kristy; Spahn, Fabienne; Altermatt, Florian

2016-01-05

Accurate detection of organisms is crucial for the effective management of threatened and invasive species because false detections directly affect the implementation of management actions. The use of environmental DNA (eDNA) as a species detection tool is in a rapid development stage; however, concerns about accurate detections using eDNA have been raised. We evaluated the effect of sampled water volume (0.25 to 2 L) on the detection rate for three macroinvertebrate species. Additionally, we tested (depending on the sampled water volume) what amount of total extracted DNA should be screened to reduce uncertainty in detections. We found that all three species were detected in all volumes of water. Surprisingly, however, only one species had a positive relationship between an increased sample volume and an increase in the detection rate. We conclude that the optimal sample volume might depend on the species-habitat combination and should be tested for the system where management actions are warranted. Nevertheless, we minimally recommend sampling water volumes of 1 L and screening at least 14 μL of extracted eDNA for each sample to reduce uncertainty in detections when studying macroinvertebrates in rivers and using our molecular workflow.

High sensitive analysis of steroids in doping control using gas chromatography/time-of-flight mass-spectrometry.

PubMed

Revelsky, A I; Samokhin, A S; Virus, E D; Rodchenkov, G M; Revelsky, I A

2011-04-01

The method of high sensitive gas chromatographic/time-of-flight mass-spectrometric (GC/TOF-MS) analysis of steroids was developed. Low-resolution TOF-MS instrument (with fast spectral acquisition rate) was used. This method is based on the formation of the silyl derivatives of steroids; exchange of the reagent mixture (pyridine and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)) for tert-butylmethylether; offline large sample volume injection of this solution based on sorption concentration of the respective derivatives from the vapour-gas mixture flow formed from the solution and inert gas flows; and entire analytes solvent-free concentrate transfer into the injector of the gas chromatograph. Detection limits for 100 µl sample solution volume were 0.5-2 pg/µl (depending on the component). Application of TOF-MS model 'TruTOF' (Leco, St Joseph, MO, USA) coupled with gas chromatograph and ChromaTOF software (Leco, St Joseph, MO, USA) allowed extraction of the full mass spectra and resolving coeluted peaks. Due to use of the proposed method (10 µl sample aliquot) and GC/TOF-MS, two times more steroid-like compounds were registered in the urine extract in comparison with the injection of 1 µl of the same sample solution. Copyright © 2010 John Wiley & Sons, Ltd.

Ultrasound-Assisted Emulsification Microextraction Based on Solidification Floating Organic Drop Trace Amounts of Manganese Prior to Graphite Furnace Atomic Absorption Spectrometry Determination

PubMed Central

Mohadesi, Alireza; Falahnejad, Masoumeh

2012-01-01

In the present study, an ultrasound-assisted emulsification microextraction based on solidification floating organic drop method is described for preconcentration of trace amounts of Mn (II). 2-(5-Bromo-2-pyridylazo)-5 diethylaminophenol was added to a solution of Mn+2 at ph = 10.0. After this, 1-undecanol was added to the solution as an extraction solvent, and solution was stirred. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction solvent, the volume of sample solution, stirring rate, and extraction time were investigated and optimized. Then sample vial was cooled by inserting into an ice bath, and the solidified was transferred into a suitable vial for immediate melting. Finally the sample was injected into a graphite furnace atomic absorption spectrometry. Under the optimum condition the linear dynamic range was 0.50–10.0 ng mL−1 with a correlation coefficient of 0.9926, and the detection limit of 0.3 ng mL−1 was obtained. The enrichment factor was 160. The proposed method was successfully applied for separation and determination of manganese in sea, rain, tap, and river water samples. PMID:22645504

Microfluidic LC Device with Orthogonal Sample Extraction for On-Chip MALDI-MS Detection

PubMed Central

Lazar, Iulia M.; Kabulski, Jarod L.

2013-01-01

A microfluidic device that enables on-chip matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) detection for liquid chromatography (LC) separations is described. The device comprises an array of functional elements to carry out LC separations, integrates a novel microchip-MS interface to facilitate the orthogonal transposition of the microfluidic LC channel into an array of reservoirs, and enables sensitive MALDI-MS detection directly from the chip. Essentially, the device provides a snapshot MALDI-MS map of the content of the separation channel present on the chip. The detection of proteins with biomarker potential from MCF10A breast epithelial cell extracts, and detection limits in the low fmol range, are demonstrated. In addition, the design of the novel LC-MALDI-MS chip entices the promotion of a new concept for performing sample separations within the limited time-frame that accompanies the dead-volume of a separation channel. PMID:23592150

Detection limits of 405 nm and 633 nm excited PpIX fluorescence for brain tumor detection during stereotactic biopsy

NASA Astrophysics Data System (ADS)

Markwardt, Niklas; Götz, Marcus; Haj-Hosseini, Neda; Hollnburger, Bastian; Sroka, Ronald; Stepp, Herbert; Zelenkov, Petr; Rühm, Adrian

2016-04-01

5-aminolevulinic-acid-(5-ALA)-induced protoporphyrin IX (PpIX) fluorescence may be used to improve stereotactic brain tumor biopsies. In this study, the sensitivity of PpIX-based tumor detection has been investigated for two potential excitation wavelengths (405 nm, 633 nm). Using a 200 μm fiber in contact with semi-infinite optical phantoms containing ink and Lipovenös, PpIX detection limits of 4.0 nM and 200 nM (relating to 1 mW excitation power) were determined for 405 nm and 633 nm excitation, respectively. Hence, typical PpIX concentrations in glioblastomas of a few μM should be well detectable with both wavelengths. Additionally, blood layers of selected thicknesses were placed between fiber and phantom. Red excitation was shown to be considerably less affected by blood interference: A 50 μm blood layer, for instance, blocked the 405- nm-excited fluorescence completely, but reduced the 633-nm-excited signal by less than 50%. Ray tracing simulations demonstrated that - without blood layer - the sensitivity advantage of 405 nm rises for decreasing fluorescent volume from 50-fold to a maximum of 100-fold. However, at a tumor volume of 1 mm3, which is a typical biopsy sample size, the 633-nm-excited fluorescence signal is only reduced by about 10%. Further simulations revealed that with increasing fiber-tumor distance, the signal drops faster for 405 nm. This reduces the risk of detecting tumor tissue outside the needle's coverage, but diminishes the overlap between optically and mechanically sampled volumes. While 405 nm generally offers a higher sensitivity, 633 nm is more sensitive to distant tumors and considerably superior in case of blood-covered tumor tissue.

Determination of nanomolar chromate in drinking water with solid phase extraction and a portable spectrophotometer.

PubMed

Ma, Jian; Yang, Bo; Byrne, Robert H

2012-06-15

Determination of chromate at low concentration levels in drinking water is an important analytical objective for both human health and environmental science. Here we report the use of solid phase extraction (SPE) in combination with a custom-made portable light-emitting diode (LED) spectrophotometer to achieve detection of chromate in the field at nanomolar levels. The measurement chemistry is based on a highly selective reaction between 1,5-diphenylcarbazide (DPC) and chromate under acidic conditions. The Cr-DPC complex formed in the reaction can be extracted on a commercial C18 SPE cartridge. Concentrated Cr-DPC is subsequently eluted with methanol and detected by spectrophotometry. Optimization of analytical conditions involved investigation of reagent compositions and concentrations, eluent type, flow rate (sample loading), sample volume, and stability of the SPE cartridge. Under optimized conditions, detection limits are on the order of 3 nM. Only 50 mL of sample is required for an analysis, and total analysis time is around 10 min. The targeted analytical range of 0-500 nM can be easily extended by changing the sample volume. Compared to previous SPE-based spectrophotometric methods, this analytical procedure offers the benefits of improved sensitivity, reduced sample consumption, shorter analysis time, greater operational convenience, and lower cost. Copyright © 2012 Elsevier B.V. All rights reserved.

Reversed-phase single drop microextraction followed by high-performance liquid chromatography with fluorescence detection for the quantification of synthetic phenolic antioxidants in edible oil samples.

PubMed

Farajmand, Bahman; Esteki, Mahnaz; Koohpour, Elham; Salmani, Vahid

2017-04-01

The reversed-phase mode of single drop microextraction has been used as a preparation method for the extraction of some phenolic antioxidants from edible oil samples. Butylated hydroxyl anisole, tert-butylhydroquinone and butylated hydroxytoluene were employed as target compounds for this study. High-performance liquid chromatography followed by fluorescence detection was applied for final determination of target compounds. The most interesting feature of this study is the application of a disposable insulin syringe with some modification for microextraction procedure that efficiently improved the volume and stability of the solvent microdrop. Different parameters such as the type and volume of solvent, sample stirring rate, extraction temperature, and time were investigated and optimized. Analytical performances of the method were evaluated under optimized conditions. Under the optimal conditions, relative standard deviations were between 4.4 and 10.2%. Linear dynamic ranges were 20-10 000 to 2-1000 μg/g (depending on the analytes). Detection limits were 5-670 ng/g. Finally, the proposed method was successfully used for quantification of the antioxidants in some edible oil samples prepared from market. Relative recoveries were achieved from 88 to 111%. The proposed method had a simplicity of operation, low cost, and successful application for real samples. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extended two-photon microscopy in live samples with Bessel beams: steadier focus, faster volume scans, and simpler stereoscopic imaging

PubMed Central

Thériault, Gabrielle; Cottet, Martin; Castonguay, Annie; McCarthy, Nathalie; De Koninck, Yves

2014-01-01

Two-photon microscopy has revolutionized functional cellular imaging in tissue, but although the highly confined depth of field (DOF) of standard set-ups yields great optical sectioning, it also limits imaging speed in volume samples and ease of use. For this reason, we recently presented a simple and retrofittable modification to the two-photon laser-scanning microscope which extends the DOF through the use of an axicon (conical lens). Here we demonstrate three significant benefits of this technique using biological samples commonly employed in the field of neuroscience. First, we use a sample of neurons grown in culture and move it along the z-axis, showing that a more stable focus is achieved without compromise on transverse resolution. Second, we monitor 3D population dynamics in an acute slice of live mouse cortex, demonstrating that faster volumetric scans can be conducted. Third, we acquire a stereoscopic image of neurons and their dendrites in a fixed sample of mouse cortex, using only two scans instead of the complete stack and calculations required by standard systems. Taken together, these advantages, combined with the ease of integration into pre-existing systems, make the extended depth-of-field imaging based on Bessel beams a strong asset for the field of microscopy and life sciences in general. PMID:24904284

Comparison of the solid-phase extraction efficiency of a bounded and an included cyclodextrin-silica microporous composite for polycyclic aromatic hydrocarbons determination in water samples.

PubMed

Mauri-Aucejo, Adela; Amorós, Pedro; Moragues, Alaina; Guillem, Carmen; Belenguer-Sapiña, Carolina

2016-08-15

Solid-phase extraction is one of the most important techniques for sample purification and concentration. A wide variety of solid phases have been used for sample preparation over time. In this work, the efficiency of a new kind of solid-phase extraction adsorbent, which is a microporous material made from modified cyclodextrin bounded to a silica network, is evaluated through an analytical method which combines solid-phase extraction with high-performance liquid chromatography to determine polycyclic aromatic hydrocarbons in water samples. Several parameters that affected the analytes recovery, such as the amount of solid phase, the nature and volume of the eluent or the sample volume and concentration influence have been evaluated. The experimental results indicate that the material possesses adsorption ability to the tested polycyclic aromatic hydrocarbons. Under the optimum conditions, the quantification limits of the method were in the range of 0.09-2.4μgL(-1) and fine linear correlations between peak height and concentration were found around 1.3-70μgL(-1). The method has good repeatability and reproducibility, with coefficients of variation under 8%. Due to the concentration results, this material may represent an alternative for trace analysis of polycyclic aromatic hydrocarbons in water trough solid-phase extraction. Copyright © 2016 Elsevier B.V. All rights reserved.

An ionic liquid as a solvent for headspace single drop microextraction of chlorobenzenes from water samples.

PubMed

Vidal, Lorena; Psillakis, Elefteria; Domini, Claudia E; Grané, Nuria; Marken, Frank; Canals, Antonio

2007-02-12

A headspace single-drop microextraction (HS-SDME) procedure using room temperature ionic liquid and coupled to high-performance liquid chromatography capable of quantifying trace amounts of chlorobenzenes in environmental water samples is proposed. A Plackett-Burman design for screening was carried out in order to determine the significant experimental conditions affecting the HS-SDME process (namely drop volume, aqueous sample volume, stirring speed, ionic strength, extraction time and temperature), and then a central composite design was used to optimize the significant conditions. The optimum experimental conditions found from this statistical evaluation were: a 5 microL microdrop of 1-butyl-3-methylimidazolium hexafluorophosphate, exposed for 37 min to the headspace of a 10 mL aqueous sample placed in a 15 mL vial, stirred at 1580 rpm at room temperature and containing 30% (w/v) NaCl. The calculated calibration curves gave a high level of linearity for all target analytes with correlation coefficients ranging between 0.9981 and 0.9997. The repeatability of the proposed method, expressed as relative standard deviation, varied between 1.6 and 5.1% (n=5). The limits of detection ranged between 0.102 and 0.203 microg L(-1). Matrix effects upon extraction were evaluated by analysing spiked tap and river water as well as effluent water samples originating from a municipal wastewater treatment plant.

Ultra preconcentration of polycyclic aromatic hydrocarbons in smoked bacon by a combination of SPE and DLLME.

PubMed

Liu, Xiaofang; Zhou, Shu; Zhu, Quanfei; Ye, Yong; Chen, Huaixia

2014-09-01

A sample pretreatment method, solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME), was established for the sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in smoked bacon samples. In the SPE-DLLME process, three PAHs including naphthalene (Naph), phenanthrene (Phen) and pyrene (Pyr) were extracted from samples and transferred into C18 SPE cartridge. The target analytes were subsequently eluted with 1.2 ml of acetonitrile-dichloromethane (5:1, v/v) mixture solution. The eluent was injected directly into the 5.0 ml ultrapure water in the subsequent DLLME procedure. The sedimented phase was concentrated under a gentle nitrogen flow to 120.0 µl. Finally, the analytes in the extraction solvent were determined by high-performance liquid chromatography with a ultra-violet detector. Some important extraction parameters affecting the performance, such as the sample solution flow rate, breakthrough volume, salt addition as well as the type and volume of the elution solvent were optimized. The developed method provided an ultra enrichment factors for PAHs ranged from 3478 to 3824. The method was applied for the selective extraction and sensitive determination of PAHs in smoked bacon samples. The limits of detection (S/N = 3) were 0.05, 0.01, 0.02 μg kg(-1) for Naph, Phen, Pyr, respectively. © The Author [2013]. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements

NASA Astrophysics Data System (ADS)

Palonen, V.

2015-12-01

We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

A portable molecular-sieve-based CO2 sampling system for radiocarbon measurements.

PubMed

Palonen, V

2015-12-01

We have developed a field-capable sampling system for the collection of CO2 samples for radiocarbon-concentration measurements. Most target systems in environmental research are limited in volume and CO2 concentration, making conventional flask sampling hard or impossible for radiocarbon studies. The present system captures the CO2 selectively to cartridges containing 13X molecular sieve material. The sampling does not introduce significant under-pressures or significant losses of moisture to the target system, making it suitable for most environmental targets. The system also incorporates a significantly larger sieve container for the removal of CO2 from chambers prior to the CO2 build-up phase and sampling. In addition, both the CO2 and H2O content of the sample gas are measured continuously. This enables in situ estimation of the amount of collected CO2 and the determination of CO2 flux to a chamber. The portable sampling system is described in detail and tests for the reliability of the method are presented.

Evaluation of a solid-phase extraction method for benzoylecgonine urine analysis in a high-throughput forensic urine drug-testing laboratory.

PubMed

Stout, Peter R; Gehlhausen, Jay M; Horn, Carl K; Klette, Kevin L

2002-10-01

A novel extraction and derivatization procedure for the cocaine metabolite benzoylecgonine (BZE) was developed and evaluated for use in a high-volume forensic urine analysis laboratory. Extractions utilized a Speedisk 48 positive pressure extraction manifold and polymer-based cation-exchange extraction columns. Samples were derivatized by the addition of pentafluoropropionic anhydride and pentafluoropropanol. All analyses were performed in selected ion monitoring mode; ions included m/z 421, 300, 272, 429, and 303 with m/z 421 to 429 ratio used for quantitation. The average extraction efficiency was 80%. Seventy-five common over-the-counter products, including prescription drugs, drug metabolites, and other drugs of abuse, demonstrated no significant interference with respect to chromatography or quantitation. The limit of detection and limit of quantitation were calculated at 12.5 ng/mL, and the assay was linear from 12.5 to 20,000 ng/mL with an r2 of 0.99932. A series of 20 precision samples (100 ng/mL) produced an average response of 97.8 ng/mL and a percent coefficient of variation of 4.1%. A set of 79 archived human urine samples that had previously been found to contain BZE were analyzed by 3 separate laboratories. The results did not differ significantly from prior quantitation or between laboratories. The Speedisk has proven viable for a high-volume production facility reducing overall cost of analysis by decreasing analysis time and minimizing waste production while meeting strict forensic requirements.

Preconcentration of Trace Neonicotinoid Insecticide Residues Using Vortex-Assisted Dispersive Micro Solid-Phase Extraction with Montmorillonite as an Efficient Sorbent.

PubMed

Moyakao, Khwankaew; Santaladchaiyakit, Yanawath; Srijaranai, Supalax; Vichapong, Jitlada

2018-04-11

In this work, we investigated montmorillonite for adsorption of neonicotinoid insecticides in vortex-assisted dispersive micro-solid phase extraction (VA-d-μ-SPE). High-performance liquid chromatography with photodiode array detection was used for quantification and determination of neonicotinoid insecticide residues, including thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid. In this method, the solid sorbent was dispersed into the aqueous sample solution and vortex agitation was performed to accelerate the extraction process. Finally, the solution was filtered from the solid sorbent with a membrane filter. The parameters affecting the extraction efficiency of the proposed method were optimized, such as amount of sorbent, sample volume, salt addition, type and volume of extraction solvent, and vortex time. The adsorbing results show that montmorillonite could be reused at least 4 times and be used as an effective adsorbent for rapid extraction/preconcentration of neonicotinoid insecticide residues. Under optimum conditions, linear dynamic ranges were achieved between 0.5 and 1000 ng mL -1 with a correlation of determination ( R² ) greater than 0.99. Limit of detection (LOD) ranged from 0.005 to 0.065 ng mL -1 , while limit of quantification (LOQ) ranged from 0.008 to 0.263 ng mL -1 . The enrichment factor (EF) ranged from 8 to 176-fold. The results demonstrated that the proposed method not only provided a more simple and sensitive method, but also can be used as a powerful alternative method for the simultaneous determination of insecticide residues in natural surface water and fruit juice samples.

Development of Capabilities for New Experimental Studies on the Elasticity and Rheology of Lower Mantle Minerals

NASA Astrophysics Data System (ADS)

Triplett, R.; Weidner, D.; Whitaker, M. L.; Chen, H.; Li, L.

2017-12-01

Key mineralogical components of the mid-mantle of the Earth have historically been difficult to obtain elasticity data on because they either cannot be recovered to ambient conditions (e.g. calcium silicate perovskite) or back-transform during experimental preparation (e.g. magnesium silicate perovskite). Recently the conditions of the mid-mantle (14+ GPa, 1500+ K) and even of the lower mantle (24+ GPa, 1800+ K) have become reachable using multi-anvil apparatuses (MAA) with in-situ synchrotron x-ray capabilities, but the capabilities of these facilities have not yet fully matured. Examples include that reaching such pressures typically results in samples that are too small for ultrasonics, the few ultrasonics experiments done at these conditions have extremely limited x-ray visibility, and rheological experiments that apply differential stress have not been done at these conditions on large volume samples. The pressure reachable in a Large Volume Press (LVP) is limited by the properties of available ultra-hard (UH) materials such as tungsten carbide (WC) and x-ray transparent polycrystalline diamond (PCD) and cubic boron nitride (cBN). A key factor is the interaction of 1st stage anvils and anvils of UH materials; obtaining WC anvils of larger size is prohibitive in both capability and cost, and anvils of hardened steel are limited in the tonnage that can be applied before damage occurs. Other complications include the difference in compressibility between WC and PCD/cBN anvils and the availability of WC with simultaneous high compressive strength (pressure gain per tonnage) and high transverse rupture strength (lower chance of blowout and reusability). The DT25 press to be used at the new NSLS-II beamline XPD-D is a Kawaii-style LVP MAA which accepts 25 mm UH 2nd-stage anvils and has the capability to apply a differential load while at extreme conditions. We report on our development of techniques to do new and expanded experiments at lower mantle conditions utilizing the large anvil size and advances in UH materials, in particular ultrasonic studies and rheological experiments, with our goal being to routinely reach lower mantle pressures and temperatures with large volume samples while retaining the ability to gather x-ray diffraction data along a majority of the circumference of the Debye-Scherrer rings.

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

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

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.

2016-02-22

The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors.more » Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less

Development of a bar adsorptive micro-extraction-large-volume injection-gas chromatography-mass spectrometric method for pharmaceuticals and personal care products in environmental water matrices.

PubMed

Neng, N R; Nogueira, J M F

2012-01-01

The combination of bar adsorptive micro-extraction using activated carbon (AC) and polystyrene-divinylbenzene copolymer (PS-DVB) sorbent phases, followed by liquid desorption and large-volume injection gas chromatography coupled to mass spectrometry, under selected ion monitoring mode acquisition, was developed for the first time to monitor pharmaceutical and personal care products (PPCPs) in environmental water matrices. Assays performed on 25 mL water samples spiked (100 ng L(-1)) with caffeine, gemfibrozil, triclosan, propranolol, carbamazepine and diazepam, selected as model compounds, yielded recoveries ranging from 74% to 99% under optimised experimental conditions (equilibrium time, 16 h (1,000 rpm); matrix characteristics: pH 5, 5% NaCl for AC phase; LD: methanol/acetonitrile (1:1), 45 min). The analytical performance showed good precision (RSD < 18%), convenient detection limits (5-20 ng L(-1)) and excellent linear dynamic range (20-800 ng L(-1)) with remarkable determination coefficients (r(2) > 0.99), where the PS-DVB sorbent phase showed a much better efficiency. By using the standard addition methodology, the application of the present analytical approach on tap, ground, sea, estuary and wastewater samples allowed very good performance at the trace level. The proposed method proved to be a suitable sorption-based micro-extraction alternative for the analysis of priority pollutants with medium-polar to polar characteristics, showing to be easy to implement, reliable, sensitive and requiring a low sample volume to monitor PPCPs in water matrices.

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

NASA Astrophysics Data System (ADS)

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; Barnett, Scott A.; Wang, Jun

2016-02-01

The coarsening of Ni in Ni-yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors. Here, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. The finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.

Discontinuous atmospheric pressure interface for mass spectrometry using a solenoid pulse valve.

PubMed

Usmanov, Dilshadbek T; Hiraoka, Kenzo

2016-08-30

For the development of on-site mass spectrometry for security and safety, point-of-care analysis, etc., the gas volume introduced into the vacuum should be reduced to a minimum. To cope with this demand, a discontinuous atmospheric pressure interface using a solenoid pulse valve was developed. The sample gas was introduced discontinuously into the ionization cell with a volume of 0.17 cm(3) . The sampled gas in the cell was ionized by an alternating current (ac) corona discharge. The generated ions were sampled through a 0.25 mm i.d. and 12 mm long nickel capillary into the vacuum of a time-of-flight mass spectrometer. A gas flow rate of ~25 mL/min was achieved with the 1 Hz pulse valve operation and 20 ms valve opening time. Sub-ng limits of detection for less volatile compounds such as explosives and drugs were obtained. Due to its compact size and low gas load to the vacuum, this new interface may be useful for applications in miniaturized mass spectrometry. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Analysis of Androgenic Steroids in Environmental Waters by Large-volume Injection Liquid Chromatography Tandem Mass Spectrometry

PubMed Central

Backe, Will J.; Ort, Christoph; Brewer, Alex J.; Field, Jennifer A.

2014-01-01

A new method was developed for the analysis of natural and synthetic androgenic steroids and their selected metabolites in aquatic environmental matrices using direct large-volume injection (LVI) high performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). Method accuracy ranged from 88 to 108% for analytes with well-matched internal standards. Precision, quantified by relative standard deviation (RSD), was less than 12%. Detection limits for the method ranged from 1.2 to 360 ng/L. The method was demonstrated on a series of 1-hr composite wastewater influent samples collected over a day with the purpose of assessing temporal profiles of androgen loads in wastewater. Testosterone, androstenedione, boldenone, and nandrolone were detected in the sample series at concentrations up to 290 ng/L and loads up to 535 mg. Boldenone, a synthetic androgen, had a temporal profile that was strongly correlated to testosterone, a natural human androgen, suggesting its source may be endogenous. An analysis of the sample particulate fraction revealed detectable amounts of sorbed testosterone and androstenedione. Androstenedione sorbed to the particulate fraction accounted for an estimated five to seven percent of the total androstenedione mass. PMID:21391574

Analysis of androgenic steroids in environmental waters by large-volume injection liquid chromatography tandem mass spectrometry.

PubMed

Backe, Will J; Ort, Christoph; Brewer, Alex J; Field, Jennifer A

2011-04-01

A new method was developed for the analysis of natural and synthetic androgenic steroids and their selected metabolites in aquatic environmental matrixes using direct large-volume injection (LVI) high-performance liquid chromatography (HPLC) tandem mass spectrometry (MS/MS). Method accuracy ranged from 87.6 to 108% for analytes with well-matched internal standards. Precision, quantified by relative standard deviation (RSD), was less than 12%. Detection limits for the method ranged from 1.2 to 360 ng/L. The method was demonstrated on a series of 1 h composite wastewater influent samples collected over a day with the purpose of assessing temporal profiles of androgen loads in wastewater. Testosterone, androstenedione, boldenone, and nandrolone were detected in the sample series at concentrations up to 290 ng/L and loads up to 535 mg/h. Boldenone, a synthetic androgen, had a temporal profile that was strongly correlated to testosterone, a natural human androgen, suggesting its source may be endogenous. An analysis of the sample particulate fraction revealed detectable amounts of sorbed testosterone and androstenedione. Androstenedione sorbed to the particulate fraction accounted for an estimated 5 to 7% of the total androstenedione mass.

Switchable polarity solvent for liquid phase microextraction of Cd(II) as pyrrolidinedithiocarbamate chelates from environmental samples.

PubMed

Yilmaz, Erkan; Soylak, Mustafa

2015-07-30

A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO2 (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L(-1) (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Simultaneous extraction and quantification of albendazole and triclabendazole using vortex-assisted hollow-fiber liquid-phase microextraction combined with high-performance liquid chromatography.

PubMed

Asadi, Mohammad; Haji Shabani, Ali Mohammad; Dadfarnia, Shayessteh

2016-06-01

A novel, simple, and rapid vortex-assisted hollow-fiber liquid-phase microextraction method was developed for the simultaneous extraction of albendazole and triclabendazole from various matrices before their determination by high-performance liquid chromatography with fluorescence detection. Several factors influencing the microextraction efficiency including sample pH, nature and volume of extraction solvent, ionic strength, vortex time, and sample volume were investigated and optimized. Under the optimal conditions, the limits of detection were 0.08 and 0.12 μg/L for albendazole and triclabendazole, respectively. The calibration curves were linear in the concentration ranges of 0.3-50.0 and 0.4-50.0 μg/L with the coefficients of determination of 0.9999 and 0.9995 for albendazole and triclabendazole, respectively. The interday and intraday relative standard deviations for albendazole and triclabendazole at three concentration levels (1.0, 10.0, and 30.0 μg/L) were in the range of 6.0-11.0 and 5.0-7.9%, respectively. The developed method was successfully applied to determine albendazole and triclabendazole in water, milk, honey, and urine samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coupling of solvent-based de-emulsification dispersive liquid-liquid microextraction with high performance liquid chromatography for simultaneous simple and rapid trace monitoring of 2,4-dichlorophenoxyacetic acid and 2-methyl-4-chlorophenoxyacetic acid.

PubMed

Behbahani, Mohammad; Najafi, Fatemeh; Bagheri, Saman; Bojdi, Majid Kalate; Hassanlou, Parmoon Ghareh; Bagheri, Akbar

2014-04-01

A simple, rapid, and efficient sample pretreatment technique, based on solvent-based de-emulsification dispersive liquid-liquid microextraction (SD-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for simultaneous preconcentration and trace detection of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxyacetic acid (MCPA) in water and urine samples. Some parameters such as acidity of solution, the amount of salt, type, and volume of extraction solvents, type of disperser/de-emulsifier solvent, and its volume were investigated and optimized. Under optimum extraction conditions, the limits of detections (LODs) of this method for MCPA and 2,4-D were 0.2 and 0.6 μg L(-1) (based on 3S(b)/m) in water and 0.4 and 1.6 μg L(-1) in urine, respectively. Furthermore, dynamic linear range of this method for MCPA and 2,4-D was 1-300 and 2-400 μg L(-1), repectively. Finally, the applicability of the proposed method was evaluated by extraction and determination of the herbicides in urine and different water samples.

Dispersive liquid-liquid microextraction for the determination of nitrophenols in soils by microvial insert large volume injection-gas chromatography-mass spectrometry.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2016-07-22

A rapid and sensitive procedure for the determination of six NPs in soils by gas chromatography and mass spectrometry (GC-MS) is proposed. Ultrasound assisted extraction (UAE) is used for NP extraction from soil matrices to an organic solvent, while the environmentally friendly technique dispersive liquid-liquid microextraction (DLLME) is used for the preconcentration of the resulting UAE extracts. NPs were derivatized by applying an "in-situ" acetylation procedure, before being injected into the GC-MS system using microvial insert large volume injection (LVI). Several parameters affecting UAE, DLLME, derivatization and injection steps were investigated. The optimized procedure provided recoveries of 86-111% from spiked samples. Precision values of the procedure (expressed as relative standard deviation, RSD) lower than 12%, and limits of quantification ranging from 1.3 to 2.6ngg(-1), depending on the compound, were obtained. Twenty soil samples, obtained from military, industrial and agricultural areas, were analyzed by the proposed method. Two of the analytes were quantified in two of the samples obtained from industrial areas, at concentrations in the 4.8-9.6ngg(-1) range. Copyright © 2016 Elsevier B.V. All rights reserved.

Breakthrough during air sampling with polyurethane foam: What do PUF 2/PUF 1 ratios mean?

PubMed

Bidleman, Terry F; Tysklind, Mats

2018-02-01

Frontal chromatography theory is applied to describe movement of gaseous semivolatile organic compounds (SVOCs) through a column of polyurethane foam (PUF). Collected mass fractions (F C ) are predicted for sample volume/breakthrough volume ratios (τ = V S /V B ) up to 6.0 and PUF bed theoretical plate numbers (N) from 2 to 16. The predictions assume constant air concentrations and temperatures. Extension of the calculations is done to relate the collection efficiency of a 2-PUF train (F C1+2 ) to the PUF 2/PUF 1 ratio. F C1+2 exceeds 0.9 for PUF 2/PUF 1 ≤ 0.5 and lengths of PUF commonly used in air samplers. As the PUF 2/PUF 1 ratio approaches unity, confidence in these predictions is limited by the analytical ability to distinguish residues on the two PUFs. Field data should not be arbitrarily discarded because some analytes broke through to the backup PUF trap. The fractional collection efficiencies can be used to estimate air concentrations from quantities retained on the PUF trap when sampling is not quantitative. Copyright © 2017 Elsevier Ltd. All rights reserved.

Polypyrrole/multi-walled carbon nanotube composite for the solid phase extraction of lead(II) in water samples.

PubMed

Sahmetlioglu, Ertugrul; Yilmaz, Erkan; Aktas, Ece; Soylak, Mustafa

2014-02-01

A multi-walled carbon nanotubes-polypyrrole conducting polymer nanocomposite has been synthesized, characterized and used for the separation and preconcentration of lead at trace levels in water samples prior to its flame atomic absorption spectrometric detection. The analytical parameters like pH, sample volume, eluent, sample flow rate that were affected the retentions of lead(II) on the new nanocomposite were optimized. Matrix effects were also investigated. Limit of detection and preconcentration factors were 1.1 µg L(-1) and 200, respectively. The adsorption capacity of the nanocomposite was 25.0mg lead(II) per gram composite. The validation of the method was checked by using SPS-WW2 Waste water Level 2 certified reference material. The method was applied to the determination of lead in water samples with satisfactory results. © 2013 Elsevier B.V. All rights reserved.

Volumetric mammographic density: heritability and association with breast cancer susceptibility loci.

PubMed

Brand, Judith S; Humphreys, Keith; Thompson, Deborah J; Li, Jingmei; Eriksson, Mikael; Hall, Per; Czene, Kamila

2014-12-01

Mammographic density is a strong heritable trait, but data on its genetic component are limited to area-based and qualitative measures. We studied the heritability of volumetric mammographic density ascertained by a fully-automated method and the association with breast cancer susceptibility loci. Heritability of volumetric mammographic density was estimated with a variance component model in a sib-pair sample (N pairs = 955) of a Swedish screening based cohort. Associations with 82 established breast cancer loci were assessed in an independent sample of the same cohort (N = 4025 unrelated women) using linear models, adjusting for age, body mass index, and menopausal status. All tests were two-sided, except for heritability analyses where one-sided tests were used. After multivariable adjustment, heritability estimates (standard error) for percent dense volume, absolute dense volume, and absolute nondense volume were 0.63 (0.06) and 0.43 (0.06) and 0.61 (0.06), respectively (all P < .001). Percent and absolute dense volume were associated with rs10995190 (ZNF365; P = 9.0 × 10(-6) and 8.9 × 10(-7), respectively) and rs9485372 (TAB2; P = 1.8 × 10(-5) and 1.8 × 10(-3), respectively). We also observed associations of rs9383938 (ESR1) and rs2046210 (ESR1) with the absolute dense volume (P = 2.6 × 10(-4) and 4.6 × 10(-4), respectively), and rs6001930 (MLK1) and rs17356907 (NTN4) with the absolute nondense volume (P = 6.7 × 10(-6) and 8.4 × 10(-5), respectively). Our results support the high heritability of mammographic density, though estimates are weaker for absolute than percent dense volume. We also demonstrate that the shared genetic component with breast cancer is not restricted to dense tissues only. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Effects of exchanged cation on the microporosity of montmorillonite

USGS Publications Warehouse

Rutherford, David W.; Chiou, Cary T.; Eberl, Dennis D.

1997-01-01

The micropore volumes of 2 montmorillonites (SAz-1 and SWy-1), each exchanged with Ca, Na, K, Cs and tetramethylammonium (TMA) ions, were calculated from the measured vapor adsorption data of N2 and neo-hexane by use of t- and αs-plots. The corresponding surface areas of the exchanged clays were determined from Brunauer-Emmett-Teller (BET) plots of N2 adsorption data. Micropore volumes and surface areas of the samples increased with the size of exchanged cation: TMA > Cs > K > Ca > Na. The SAz-1 exchanged clays showed generally greater micropore volumes and surface areas than the corresponding SWy-1 clays. The vapor adsorption data and d(001) measurements for dry clay samples were used together to evaluate the likely locations and accessibility of clay micropores, especially the relative accessibility of their interlayer spacing. For both source clays exchanged with Na, Ca and K ions, the interlayer spacing appeared to be too small to admit nonpolar gases and the accessible micropores appeared to have dimensions greater than 5.0 Å, the limiting molecular dimension of neo-hexane. In these systems, there was a good consistency of micropore volumes detected by N2 and neo-hexane. When the clays were intercalated with relatively large cations (TMA and possibly Cs), the large layer expansion created additional microporosity, which was more readily accessible to small N2 than to relatively large neo-hexane. Hence, the micropore volume as detected by N2 was greater than that detected by neo-hexane. The micropore volumes with pore dimensions greater than 5 Å determined for clays exchanged with Na, Ca and K likely resulted from the pores on particle edges and void created by overlap regions of layers. The increase in micropore volumes with pore dimensions less than 5 Å determined for clays exchanged with TMA and possibly Cs could be caused by opening of the interlayer region by the intercalation of these large cations.

Sampling and detection of airborne influenza virus towards point-of-care applications.

PubMed

Ladhani, Laila; Pardon, Gaspard; Meeuws, Hanne; van Wesenbeeck, Liesbeth; Schmidt, Kristiane; Stuyver, Lieven; van der Wijngaart, Wouter

2017-01-01

Airborne transmission of the influenza virus contributes significantly to the spread of this infectious pathogen, particularly over large distances when carried by aerosol droplets with long survival times. Efficient sampling of virus-loaded aerosol in combination with a low limit of detection of the collected virus could enable rapid and early detection of airborne influenza virus at the point-of-care setting. Here, we demonstrate a successful sampling and detection of airborne influenza virus using a system specifically developed for such applications. Our system consists of a custom-made electrostatic precipitation (ESP)-based bioaerosol sampler that is coupled with downstream quantitative polymerase chain reaction (qPCR) analysis. Aerosolized viruses are sampled directly into a miniaturized collector with liquid volume of 150 μL, which constitutes a simple and direct interface with subsequent biological assays. This approach reduces sample dilution by at least one order of magnitude when compared to other liquid-based aerosol bio-samplers. Performance of our ESP-based sampler was evaluated using influenza virus-loaded sub-micron aerosols generated from both cultured and clinical samples. Despite the miniaturized collection volume, we demonstrate a collection efficiency of at least 10% and sensitive detection of a minimum of 3721 RNA copies. Furthermore, we show that an improved extraction protocol can allow viral recovery of down to 303 RNA copies and a maximum sampler collection efficiency of 47%. A device with such a performance would reduce sampling times dramatically, from a few hours with current sampling methods down to a couple of minutes with our ESP-based bioaerosol sampler.

Catalog of Apollo 17 rocks. Volume 1: Stations 2 and 3 (South Massif)

NASA Technical Reports Server (NTRS)

Ryder, Graham

1993-01-01

The Catalog of Apollo 17 Rocks is a set of volumes that characterize each of 334 individually numbered rock samples (79 larger than 100 g) in the Apollo 17 collection, showing what each sample is and what is known about it. Unconsolidated regolith samples are not included. The catalog is intended to be used by both researchers requiring sample allocations and a broad audience interested in Apollo 17 rocks. The volumes are arranged geographically, with separate volumes for the South Massif and Light Mantle, the North Massif, and two volumes for the mare plains. Within each volume, the samples are arranged in numerical order, closely corresponding with the sample collection stations. The present volume, for the South Massif and Light Mantle, describes the 55 individual rock fragments collected at Stations two, two-A, three, and LRV-five. Some were chipped from boulders, others collected as individual rocks, some by raking, and a few by picking from the soil in the processing laboratory. Information on sample collection, petrography, chemistry, stable and radiogenic isotopes, rock surface characteristics, physical properties, and curatorial processing is summarized and referenced as far as it is known up to early 1992. The intention has been to be comprehensive: to include all published studies of any kind that provide information on the sample, as well as some unpublished information. References which are primarily bulk interpretations of existing data or mere lists of samples are not generally included. Foreign language journals were not scrutinized, but little data appears to have been published only in such journals. We have attempted to be consistent in format across all of the volumes, and have used a common reference list that appears in all volumes. Where possible, ages based on Sr and Ar isotopes have been recalculated using the 'new' decay constants recommended by Steiger and Jager; however, in many of the reproduced diagrams the ages correspond with the 'old' decay constants. In this volume, mg' or Mg' = atomic Mg/(Mg +Fe).

Accuracy and variability of tumor burden measurement on multi-parametric MRI

NASA Astrophysics Data System (ADS)

Salarian, Mehrnoush; Gibson, Eli; Shahedi, Maysam; Gaed, Mena; Gómez, José A.; Moussa, Madeleine; Romagnoli, Cesare; Cool, Derek W.; Bastian-Jordan, Matthew; Chin, Joseph L.; Pautler, Stephen; Bauman, Glenn S.; Ward, Aaron D.

2014-03-01

Measurement of prostate tumour volume can inform prognosis and treatment selection, including an assessment of the suitability and feasibility of focal therapy, which can potentially spare patients the deleterious side effects of radical treatment. Prostate biopsy is the clinical standard for diagnosis but provides limited information regarding tumour volume due to sparse tissue sampling. A non-invasive means for accurate determination of tumour burden could be of clinical value and an important step toward reduction of overtreatment. Multi-parametric magnetic resonance imaging (MPMRI) is showing promise for prostate cancer diagnosis. However, the accuracy and inter-observer variability of prostate tumour volume estimation based on separate expert contouring of T2-weighted (T2W), dynamic contrastenhanced (DCE), and diffusion-weighted (DW) MRI sequences acquired using an endorectal coil at 3T is currently unknown. We investigated this question using a histologic reference standard based on a highly accurate MPMRIhistology image registration and a smooth interpolation of planimetric tumour measurements on histology. Our results showed that prostate tumour volumes estimated based on MPMRI consistently overestimated histological reference tumour volumes. The variability of tumour volume estimates across the different pulse sequences exceeded interobserver variability within any sequence. Tumour volume estimates on DCE MRI provided the lowest inter-observer variability and the highest correlation with histology tumour volumes, whereas the apparent diffusion coefficient (ADC) maps provided the lowest volume estimation error. If validated on a larger data set, the observed correlations could support the development of automated prostate tumour volume segmentation algorithms as well as correction schemes for tumour burden estimation on MPMRI.

Regional brain volumes and cognition in childhood epilepsy: does size really matter?

PubMed

Zelko, Frank A; Pardoe, Heath R; Blackstone, Sarah R; Jackson, Graeme D; Berg, Anne T

2014-05-01

Recent studies have correlated neurocognitive function and regional brain volumes in children with epilepsy. We tested whether brain volume differences between children with and without epilepsy explained differences in neurocognitive function. The study sample included 108 individuals with uncomplicated non-syndromic epilepsy (NSE) and 36 healthy age- and gender-matched controls. Participants received a standardized cognitive battery. Whole brain T1-weighted MRI was obtained and volumes analyzed with FreeSurfer (TM). Total brain volume (TBV) was significantly smaller in cases. After adjustment for TBV, cases had significantly larger regional grey matter volumes for total, frontal, parietal, and precentral cortex. Cases had poorer performance on neurocognitive indices of intelligence and variability of sustained attention. In cases, TBV showed small associations with intellectual indices of verbal and perceptual ability, working memory, and overall IQ. In controls, TBV showed medium associations with working memory and variability of sustained attention. In both groups, small associations were seen between some TBV-adjusted regional brain volumes and neurocognitive indices, but not in a consistent pattern. Brain volume differences did not account for cognitive differences between the groups. Patients with uncomplicated NSE have smaller brains than controls but areas of relative grey matter enlargement. That this relative regional enlargement occurs in the context of poorer overall neurocognitive functioning suggests that it is not adaptive. However, the lack of consistent associations between case-control differences in brain volumes and cognitive functioning suggests that brain volumes have limited explanatory value for cognitive functioning in childhood epilepsy. Copyright © 2014 Elsevier B.V. All rights reserved.

On the predictivity of pore-scale simulations: Estimating uncertainties with multilevel Monte Carlo

NASA Astrophysics Data System (ADS)

Icardi, Matteo; Boccardo, Gianluca; Tempone, Raúl

2016-09-01

A fast method with tunable accuracy is proposed to estimate errors and uncertainties in pore-scale and Digital Rock Physics (DRP) problems. The overall predictivity of these studies can be, in fact, hindered by many factors including sample heterogeneity, computational and imaging limitations, model inadequacy and not perfectly known physical parameters. The typical objective of pore-scale studies is the estimation of macroscopic effective parameters such as permeability, effective diffusivity and hydrodynamic dispersion. However, these are often non-deterministic quantities (i.e., results obtained for specific pore-scale sample and setup are not totally reproducible by another ;equivalent; sample and setup). The stochastic nature can arise due to the multi-scale heterogeneity, the computational and experimental limitations in considering large samples, and the complexity of the physical models. These approximations, in fact, introduce an error that, being dependent on a large number of complex factors, can be modeled as random. We propose a general simulation tool, based on multilevel Monte Carlo, that can reduce drastically the computational cost needed for computing accurate statistics of effective parameters and other quantities of interest, under any of these random errors. This is, to our knowledge, the first attempt to include Uncertainty Quantification (UQ) in pore-scale physics and simulation. The method can also provide estimates of the discretization error and it is tested on three-dimensional transport problems in heterogeneous materials, where the sampling procedure is done by generation algorithms able to reproduce realistic consolidated and unconsolidated random sphere and ellipsoid packings and arrangements. A totally automatic workflow is developed in an open-source code [1], that include rigid body physics and random packing algorithms, unstructured mesh discretization, finite volume solvers, extrapolation and post-processing techniques. The proposed method can be efficiently used in many porous media applications for problems such as stochastic homogenization/upscaling, propagation of uncertainty from microscopic fluid and rock properties to macro-scale parameters, robust estimation of Representative Elementary Volume size for arbitrary physics.

Determination of acrylamide in drinking water by large-volume direct injection and ion-exclusion chromatography-mass spectrometry.

PubMed

Cavalli, S; Polesello, S; Saccani, G

2004-06-11

Acrylamide, a known neurotoxin and putative human carcinogen, has been included among the substances to be monitored in drinking water according to the European Union Directive 98/83 on potable water. This paper reports a new method based on the combination of ion-exclusion chromatographic separation and MS detection. Samples of drinking water have been directly injected in the microbore ICE-AS1 column and detected in the selected-ion monitoring mode by a single quadrupole system with electrospray ionization. Chromatographic conditions, such as eluent composition and flow rate, have been optimized by a central composite design experiment. Statistical analysis of data showed that the amount of acetonitrile fraction in the eluent mixture, composed by acetonitrile and formic acid solution, is the variable that most influences retention of the acrylamide peak. After optimization of MS detection parameters, this method has been validated for spiked drinking water samples. The effect of large-volume injection (up to 500 microl) has been also explored. Linearity was evaluated from 0.5 to 5 microg l(-1). Repeatability, expressed as R.S.D., was 16 and 12% at 0.5 and 1 microg l(-1) respectively. The limit of detection was 0.20 ppb with 500 microl injection volume.

Heat capacity measurements of sub-nanoliter volumes of liquids using bimaterial microchannel cantilevers

NASA Astrophysics Data System (ADS)

Khan, M. F.; Miriyala, N.; Lee, J.; Hassanpourfard, M.; Kumar, A.; Thundat, T.

2016-05-01

Lab-on-a-Chip compatible techniques for thermal characterization of miniaturized volumes of liquid analytes are necessary in applications such as protein blotting, DNA melting, and drug development, where samples are either rare or volume-limited. We developed a closed-chamber calorimeter based on a bimaterial microchannel cantilever (BMC) for sub-nanoliter level thermal analysis. When the liquid-filled BMC is irradiated with infrared (IR) light at a specific wavelength, the IR absorption by the liquid analyte results in localized heat generation and the subsequent deflection of the BMC, due to a thermal expansion mismatch between the constituent materials. The time constant of the deflection, which is dependent upon the heat capacity of the liquid analyte, can be directly measured by recording the time-dependent bending of the BMC. We have used the BMC to quantitatively measure the heat capacity of five volatile organic compounds. With a deflection noise level of ˜10 nm and a signal-to-noise ratio of 68:1, the BMC offers a sensitivity of 30.5 ms/(J g-1 K-1) and a resolution of 23 mJ/(g K) for ˜150 pl liquid for heat capacity measurements. This technique can be used for small-scale thermal characterization of different chemical and biological samples.

Poly(1-vinylimidazole) functionalized magnetic ion imprinted polymer for fast and selective extraction of trace gold in geological, environmental and biological samples followed by graphite furnace atomic absorption spectrometry detection

NASA Astrophysics Data System (ADS)

Zhao, Bingshan; He, Man; Chen, Beibei; Xu, Hongrun; Hu, Bin

2018-05-01

In this study, poly(1-vinylimidazole) functionalized gold ion imprinted polymer coated magnetic nanoparticles (MNPs@PVIM-Au-IIP) were prepared and characterized. The adsorption behaviors of the prepared MNPs@PVIM-Au-IIP toward gold ions (Au(III)) were studied, it was found that MNPs@PVIM-Au-IIP has good selectivity, high adsorption capacity (185.4 mg g-1) and fast adsorption kinetic for Au(III). Based on it, a new method of ion imprinted magnetic solid phase extraction (II-MSPE) coupled with graphite furnace atomic absorption spectrometry (GFAAS) detection was proposed for the analysis of trace Au(III) in real samples with complicated matrix. Factors affecting MSPE including sample pH, desorption reagent, elution concentration and volume, elution time, sample volume and adsorption time were optimized. With high enrichment factor of 100-fold, the detection limit of the proposed method is 7.9 ng L-1 for Au(III) with the relative standard deviation of 7.4% (c = 50 ng L-1, n = 7). In order to validate the accuracy of the proposed method, the Certified Reference Material of GBW07293 geological sample (platinpalladium ore) was analyzed, and the determined value was in good agreement with the certified value. The proposed II-MSPE-GFAAS method is simple, fast, selective, sensitive and has been successfully applied in the determination of trace Au in ore, sediment, environmental water and human urine samples with satisfactory results.

40 CFR Table 1 to Subpart Ddddd of... - Emission Limits for New or Reconstructed Boilers and Process Heaters

Code of Federal Regulations, 2014 CFR

2014-07-01

... fossil fuel a. Filterable PM (or TSM) 1.1E-03 lb per MMBtu of heat input; or (2.3E-05 lb per MMBtu of... designed to burn coal/solid fossil fuel a. Carbon monoxide (CO) (or CEMS) 130 ppm by volume on a dry basis... minimum sampling time. 4. Stokers designed to burn coal/solid fossil fuel a. CO (or CEMS) 130 ppm by...

Multiplexed aberration measurement for deep tissue imaging in vivo

PubMed Central

Wang, Chen; Liu, Rui; Milkie, Daniel E.; Sun, Wenzhi; Tan, Zhongchao; Kerlin, Aaron; Chen, Tsai-Wen; Kim, Douglas S.; Ji, Na

2014-01-01

We describe a multiplexed aberration measurement method that modulates the intensity or phase of light rays at multiple pupil segments in parallel to determine their phase gradients. Applicable to fluorescent-protein-labeled structures of arbitrary complexity, it allows us to obtain diffraction-limited resolution in various samples in vivo. For the strongly scattering mouse brain, a single aberration correction improves structural and functional imaging of fine neuronal processes over a large imaging volume. PMID:25128976

A Combined Hazard Index Fire Test Methodology for Aircraft Cabin Materials. Volume I.

DTIC Science & Technology

1982-04-01

PROGRAM TEST PANEL NO. 1 ....... 52 5 SUMARY OF EXPERIMTAL CHAS/SATS DATA FOR CI PRGRAM TEST PANEL 2, 3 & 4...As indicated in Figure 2, the dose of each hazard building up in CHI zone 13 is approaching an "effective dose" limit which prevents occupant escape...per minute. During a test, flow into SATS was stopped when CO reached peak concentrations to prevent dilution thereafter at decreasing sample CO

Geometric k-nearest neighbor estimation of entropy and mutual information

NASA Astrophysics Data System (ADS)

Lord, Warren M.; Sun, Jie; Bollt, Erik M.

2018-03-01

Nonparametric estimation of mutual information is used in a wide range of scientific problems to quantify dependence between variables. The k-nearest neighbor (knn) methods are consistent, and therefore expected to work well for a large sample size. These methods use geometrically regular local volume elements. This practice allows maximum localization of the volume elements, but can also induce a bias due to a poor description of the local geometry of the underlying probability measure. We introduce a new class of knn estimators that we call geometric knn estimators (g-knn), which use more complex local volume elements to better model the local geometry of the probability measures. As an example of this class of estimators, we develop a g-knn estimator of entropy and mutual information based on elliptical volume elements, capturing the local stretching and compression common to a wide range of dynamical system attractors. A series of numerical examples in which the thickness of the underlying distribution and the sample sizes are varied suggest that local geometry is a source of problems for knn methods such as the Kraskov-Stögbauer-Grassberger estimator when local geometric effects cannot be removed by global preprocessing of the data. The g-knn method performs well despite the manipulation of the local geometry. In addition, the examples suggest that the g-knn estimators can be of particular relevance to applications in which the system is large, but the data size is limited.

Microfluidic viscometers for shear rheology of complex fluids and biofluids

PubMed Central

Wang, William S.; Vanapalli, Siva A.

2016-01-01

The rich diversity of man-made complex fluids and naturally occurring biofluids is opening up new opportunities for investigating their flow behavior and characterizing their rheological properties. Steady shear viscosity is undoubtedly the most widely characterized material property of these fluids. Although widely adopted, macroscale rheometers are limited by sample volumes, access to high shear rates, hydrodynamic instabilities, and interfacial artifacts. Currently, microfluidic devices are capable of handling low sample volumes, providing precision control of flow and channel geometry, enabling a high degree of multiplexing and automation, and integrating flow visualization and optical techniques. These intrinsic advantages of microfluidics have made it especially suitable for the steady shear rheology of complex fluids. In this paper, we review the use of microfluidics for conducting shear viscometry of complex fluids and biofluids with a focus on viscosity curves as a function of shear rate. We discuss the physical principles underlying different microfluidic viscometers, their unique features and limits of operation. This compilation of technological options will potentially serve in promoting the benefits of microfluidic viscometry along with evincing further interest and research in this area. We intend that this review will aid researchers handling and studying complex fluids in selecting and adopting microfluidic viscometers based on their needs. We conclude with challenges and future directions in microfluidic rheometry of complex fluids and biofluids. PMID:27478521

Monitoring well utility in a heterogeneous DNAPL source zone area: Insights from proximal multilevel sampler wells and sampling capture-zone modelling

NASA Astrophysics Data System (ADS)

McMillan, Lindsay A.; Rivett, Michael O.; Wealthall, Gary P.; Zeeb, Peter; Dumble, Peter

2018-03-01

Groundwater-quality assessment at contaminated sites often involves the use of short-screen (1.5 to 3 m) monitoring wells. However, even over these intervals considerable variation may occur in contaminant concentrations in groundwater adjacent to the well screen. This is especially true in heterogeneous dense non-aqueous phase liquid (DNAPL) source zones, where cm-scale contamination variability may call into question the effectiveness of monitoring wells to deliver representative data. The utility of monitoring wells in such settings is evaluated by reference to high-resolution multilevel sampler (MLS) wells located proximally to short-screen wells, together with sampling capture-zone modelling to explore controls upon well sample provenance and sensitivity to monitoring protocols. Field data are analysed from the highly instrumented SABRE research site that contained an old trichloroethene source zone within a shallow alluvial aquifer at a UK industrial facility. With increased purging, monitoring-well samples tend to a flow-weighted average concentration but may exhibit sensitivity to the implemented protocol and degree of purging. Formation heterogeneity adjacent to the well-screen particularly, alongside pump-intake position and water level, influence this sensitivity. Purging of low volumes is vulnerable to poor reproducibility arising from concentration variability predicted over the initial 1 to 2 screen volumes purged. Marked heterogeneity may also result in limited long-term sample concentration stabilization. Development of bespoke monitoring protocols, that consider screen volumes purged, alongside water-quality indicator parameter stabilization, is recommended to validate and reduce uncertainty when interpreting monitoring-well data within source zone areas. Generalised recommendations on monitoring well based protocols are also developed. A key monitoring well utility is their proportionately greater sample draw from permeable horizons constituting a significant contaminant flux pathway and hence representative fraction of source mass flux. Acquisition of complementary, high-resolution, site monitoring data, however, vitally underpins optimal interpretation of monitoring-well datasets and appropriate advancement of a site conceptual model and remedial implementation.

Clinical impact of leak compensation during non-invasive ventilation.

PubMed

Storre, Jan Hendrik; Bohm, Philipp; Dreher, Michael; Windisch, Wolfram

2009-10-01

This study aimed to assess the impact of leak compensation capabilities during pressure- and volume-limited non-invasive positive-pressure ventilation (NPPV) in COPD patients. Fourteen patients with stable hypercapnic COPD who were receiving long-term NPPV were included in the study. For both modes of NPPV, a full face mask and an artificial leak in the ventilatory circuit were used at three different settings, and applied during daytime NPPV, either without leakage (setting I), with leakage during inspiration only (setting II), and with leakage during inspiration and expiration (setting III). Ventilation pattern was pneumotachy-graphically recorded. NPPV was feasible with negligible leak volumes, indicating optimal mask fitting during the daytime (setting I). In the presence of leakage (settings II and III), the attempt to compensate for leak was only evident during pressure-limited NPPV, since inspiratory volumes delivered by the ventilator increased from 726+/-129 (setting I) to 1104+/-164 (setting II), and to 1257+/-166 (setting III) ml during pressure-limited NPPV, respectively (all p<0.001); however, they remained stable during volume-limited NPPV. Leak compensation resulted in a decrease in leakage-induced dyspnea. However, 83%/87% (setting II/III) of the additionally-delivered inspiratory volume during pressure-limited NPPV was also lost via leakage. Expiratory volume was higher in setting II compared to setting III (both p<0.001), indicating the presence of significant expiratory leakage. The attempt at leak compensation largely feeds the leakage itself and only results in a marginal increase of tidal volume. However, pressure-limited--but not volume-limited--NPPV results in a clinically-important leak compensation in vivo. www.uniklinik-freiburg.de/zks/live/uklregister/Oeffentlich.html Identifier: UKF001272.

Highly sensitive oligosaccharide analysis in capillary electrophoresis using large-volume sample stacking with an electroosmotic flow pump.

PubMed

Kawai, Takayuki; Watanabe, Masato; Sueyoshi, Kenji; Kitagawa, Fumihiko; Otsuka, Koji

2012-04-06

To obtain high sensitivity in capillary electrophoresis of oligosaccharide without reducing the high resolution with an easy experimental procedure, large-volume sample stacking with an electroosmotic flow pump (LVSEP) was investigated. As a fundamental study, effect of the conductivity of a sample solution in LVSEP was examined. It was revealed that LVSEP was successfully carried out even in using a sample solution with the ionic strength of 150 μM and the conductivity ratio of 20, indicating a good applicability of LVSEP to the analysis of real samples containing salts. When glucose oligomer was analyzed as a model sample in LVSEP-capillary zone electrophoresis (CZE), all peaks were well resolved with decreasing only 5% of the peak-to-peak distance, which suggested 95% of the whole capillary could be used for the effective separation. In the analysis of maltoheptaose, a good calibration line with correlation coefficient of 0.9995 was obtained. The limit of detection was estimated as 2 pM, which was 500-fold lower than that in the conventional CZE. N-linked glycans released from three glycoproteins, bovine ribonuclease B, bovine fetuin, and human α(1)-acid glycoprotein were also analyzed by LVSEP-CZE. By the sample purification with a gel filtration column, further sample dilution to reduce the sample conductivity for LVSEP was not needed. All glycan samples were well concentrated and separated with up to a 770-fold sensitivity increase. The run-to-run repeatabilities of the migration time, peak height, and peak area were good with relative standard deviations of 0.1-1.3%, 1.2-1.7%, and 2.8-4.9%, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

A New Technique for In Situ X-ray Microtomography Under High Pressure

NASA Astrophysics Data System (ADS)

Uchida, T.; Wang, Y.; Westferro, F.; Gebhardt, J.; Rivers, M. L.; Sutton, S. R.

2004-12-01

We have developed a new technique for in situ synchrotron microtomography to study texture evolution in multi-phase specimens under high pressure and temperature. Two critical issues in performing tomography experiments under pressure are (1) the limited X-ray access to the sample because of the highly absorbing materials, such as tungsten carbide and tool steel, typically used in the pressure vessel and (2) a high pressure compatible rotation mechanism to collect projections of the sample continuously from 0 to 180° . We addressed these issues by (1) employing an opposed-anvil high pressure cell, known as the Drickamer cell, with an X-ray transparent containment ring, to allow panoramic X-ray access, and (2) rotating the Dricakmer cell by Harmonic DriveTM gear reducers, with thrust bearings supporting the hydraulic load. The design of the rotation mechanism benefited from the rotational deformation apparatus developed by Yamazaki and Karato (Rev. Sci. Instrum., 72, 4207, 2001). We report results obtained from a test run performed under pressure with monochromatic synchrotron radiation. A sapphire sphere (1.0 mm dia.) was embedded in a powdered mixture of Fe and 9 wt.% S alloy. The diameter of the sample chamber was 2 mm. Under pressure, the entire Drickamer cell was rotated to collect radiographs of the sample at various angles from 0 to 179.5° in 0.5° step size. Computational reconstruction of these projections provided three dimensional (3D) distribution of linear attenuation coefficient of the sample with a spatial resolution of 6 microns. The shape change in the sapphire sphere during compression was clearly observed. Using the program Blob3d, reconstructed 3D images of the sphere were separated from the surrounding Fe-S alloy. Volumes of the sphere were then accurately determined from the extracted images, by carefully defining the image intensity threshold. The errors in the volume measurement are about 0.3 to 0.7%, mostly due to shadowing by anvil deformation. The results, although performed using a solid sample, demonstrate the potential of measuring melt volume. Previous density measurements using X-ray radiography with only one dimensional data assumed that the shape of the sample remained unchanged throughout the experiment. In our new technique, this assumption is no longer required and density of melts can be inferred directly from the sample volume even when the molten sample is distorted. Other applications of this apparatus will be also discussed.

Fe induced optical limiting properties of Zn1-xFexS nanospheres

NASA Astrophysics Data System (ADS)

Vineeshkumar, T. V.; Raj, D. Rithesh; Prasanth, S.; Unnikrishnan, N. V.; Mahadevan Pillai, V. P.; Sudarasanakumar, C.

2018-02-01

Zn1-xFexS (x = 0.00, 0.01, 0.03, 0.05) nanospheres were synthesized by polyethylene glycol assisted hydrothermal method. XRD studies revealed that samples of all concentrations exhibited cubic structure with crystallite grain size 7-9 nm. TEM and SEM show the formation of nanospheres by dense aggregation of smaller particles. Increasing Zn/Fe ratio tune the band gap from 3.4 to 3.2 eV and also quenches the green luminescence. FTIR spectra reveal the presence of capping agent, intensity variation and shifting of LO and TO phonon modes confirm the presence of Fe ions. Nonlinear optical properties were measured using open and closed aperture z-scan techniques, employing frequency doubled 532 nm pumping sources which indicated reverse saturable absorption (RSA) process. The nonlinear optical coefficients are obtained by two photon absorption (2PA). Composition dependent nonlinear optical coefficients ;β;, nonlinear refractive index, third order susceptibility and optical limiting threshold were estimated. The sample shows good nonlinear absorption and enhancement of optical limiting behavior with increasing Fe volume fraction. Contribution of RSA on optical nonlinearity of Zn1-xFexS nanospheres are also investigated using three different input energies. Zn1-xFexS with comparatively small limiting threshold value is a promising candidate for optical power limiting applications.

Weighting factors for computing the relation between tree volume and d.b.h. in the Pacific Northwest.

Treesearch

Donald R. Gedney; Floyd A. Johnson

1959-01-01

Timber cruising is frequently made easier through use of local volume tables based on d.b.h. alone. These tables are made by establishing the relation between volume and d.b.h. from measurements (including height) made on sample trees in the stand. The sample-tree measurements are converted to volumes through use of standard volume tables, and a volume-diameter curve...

Observations on the use of membrane filtration and liquid impingement to collect airborne microorganisms in various atmospheric environments

USGS Publications Warehouse

Griffin, Dale W.; Gonzalez, C.; Teigell, N.; Petrosky, T.; Northup, D.E.; Lyles, M.

2011-01-01

The influence of sample-collection-time on the recovery of culturable airborne microorganisms using a low-flow-rate membrane-filtration unit and a high-flow-rate liquid impinger were investigated. Differences in recoveries were investigated in four different atmospheric environments, one mid-oceanic at an altitude of ~10.0 m, one on a mountain top at an altitude of ~3,000.0 m, one at ~1.0 m altitude in Tallahassee, Florida, and one at ~1.0 m above ground in a subterranean-cave. Regarding use of membrane filtration, a common trend was observed: the shorter the collection period, the higher the recovery of culturable bacteria and fungi. These data also demonstrated that lower culturable counts were common in the more remote mid-oceanic and mountain-top atmospheric environments with bacteria, fungi, and total numbers averaging (by sample time or method categories) <3.0 colony-forming units (CFU) m -3. At the Florida and subterranean sites, the lowest average count noted was 3.5 bacteria CFU m-3, and the highest averaged 140.4 total CFU m-3. When atmospheric temperature allowed use, the high-volume liquid impinger utilized in this study resulted in much higher recoveries, as much as 10?? greater in a number of the categories (bacterial, fungal, and total CFU). Together, these data illustrated that (1) the high-volume liquid impinger is clearly superior to membrane filtration for aeromicrobiology studies if start-up costs are not an issue and temperature permits use; (2) although membrane filtration is more cost friendly and has a 'typically' wider operational range, its limits include loss of cell viability with increased sample time and issues with effectively extracting nucleic acids for community-based analyses; (3) the ability to recover culturable microorganisms is limited in 'extreme' atmospheric environments and thus the use of a 'limited' methodology in these environments must be taken into account; and (4) the atmosphere culls, i.e., everything is not everywhere. ?? 2010 US Government.

Simultaneous determination of fluoroquinolones in environmental water by liquid chromatography-tandem mass spectrometry with direct injection: A green approach.

PubMed

Denadai, Marina; Cass, Quezia Bezerra

2015-10-30

This work describes an on-line multi-residue method for simultaneous quantification of ciprofloxacin, enrofloxacin, gemifloxacin, moxifloxacin, norfloxacin and ofloxacin in superficial and wastewater samples. For that, an octyl restricted-access media bovine serum albumin column (RAM-BSA C8) was used for sample clean-up, enrichment and analysis with quantitation carried out by tandem mass spectrometry. For water samples volumes of only 500μL the method provided good selectivity, extraction efficiency, accuracy, and precision with quantification limits in the order of 20-150ngL(-1). Out of the six fluoroquinolones only ciprofloxacin (195ngL(-1)) and norfloxacin (270ngL(-1)) were quantified in an influent sample of the wastewater treatment plant (WWTP) of São Carlos (SP, Brazil). None were found in the superficial water samples analyzed. The capability of injecting native sample in an automated mode provides high productivity and represents a greener approach in environmental sample analysis. Copyright © 2015 Elsevier B.V. All rights reserved.

Price-volume multifractal analysis and its application in Chinese stock markets

NASA Astrophysics Data System (ADS)

Yuan, Ying; Zhuang, Xin-tian; Liu, Zhi-ying

2012-06-01

An empirical research on Chinese stock markets is conducted using statistical tools. First, the multifractality of stock price return series, ri(ri=ln(Pt+1)-ln(Pt)) and trading volume variation series, vi(vi=ln(Vt+1)-ln(Vt)) is confirmed using multifractal detrended fluctuation analysis. Furthermore, a multifractal detrended cross-correlation analysis between stock price return and trading volume variation in Chinese stock markets is also conducted. It is shown that the cross relationship between them is also found to be multifractal. Second, the cross-correlation between stock price Pi and trading volume Vi is empirically studied using cross-correlation function and detrended cross-correlation analysis. It is found that both Shanghai stock market and Shenzhen stock market show pronounced long-range cross-correlations between stock price and trading volume. Third, a composite index R based on price and trading volume is introduced. Compared with stock price return series ri and trading volume variation series vi, R variation series not only remain the characteristics of original series but also demonstrate the relative correlation between stock price and trading volume. Finally, we analyze the multifractal characteristics of R variation series before and after three financial events in China (namely, Price Limits, Reform of Non-tradable Shares and financial crisis in 2008) in the whole period of sample to study the changes of stock market fluctuation and financial risk. It is found that the empirical results verified the validity of R.

Microvolume trace environmental analysis using peak-focusing online solid-phase extraction-nano-liquid chromatography-high-resolution mass spectrometry.

PubMed

Stravs, Michael A; Mechelke, Jonas; Ferguson, P Lee; Singer, Heinz; Hollender, Juliane

2016-03-01

Online solid-phase extraction was combined with nano-liquid chromatography coupled to high-resolution mass spectrometry (HRMS) for the analysis of micropollutants in environmental samples from small volumes. The method was validated in surface water, Microcystis aeruginosa cell lysate, and spent Microcystis growth medium. For 41 analytes, quantification limits of 0.1-28 ng/L (surface water) and 0.1-32 ng/L (growth medium) were obtained from only 88 μL of sample. In cell lysate, quantification limits ranged from 0.1-143 ng/L or 0.33-476 ng/g dry weight from a sample of 88 μL, or 26 μg dry weight, respectively. The method matches the sensitivity of established online and offline solid-phase extraction-liquid chromatography-mass spectrometry methods but requires only a fraction of the sample used by those techniques, and is among the first applications of nano-LC-MS for environmental analysis. The method was applied to the determination of bioconcentration in Microcystis aeruginosa in a laboratory experiment, and the benefit of coupling to HRMS was demonstrated in a transformation product screening.

A Simple Approach for Obtaining High Resolution, High Sensitivity ¹H NMR Metabolite Spectra of Biofluids with Limited Mass Supply

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

Hu, Jian Zhi; Rommereim, Donald N.; Wind, Robert A.

2006-11-01

A simple approach is reported that yields high resolution, high sensitivity ¹H NMR spectra of biofluids with limited mass supply. This is achieved by spinning a capillary sample tube containing a biofluid at the magic angle at a frequency of about 80Hz. A 2D pulse sequence called ¹H PASS is then used to produce a high-resolution ¹H NMR spectrum that is free from magnetic susceptibility induced line broadening. With this new approach a high resolution ¹H NMR spectrum of biofluids with a volume less than 1.0 µl can be easily achieved at a magnetic field strength as low as 7.05T.more » Furthermore, the methodology facilitates easy sample handling, i.e., the samples can be directly collected into inexpensive and disposable capillary tubes at the site of collection and subsequently used for NMR measurements. In addition, slow magic angle spinning improves magnetic field shimming and is especially suitable for high throughput investigations. In this paper first results are shown obtained in a magnetic field of 7.05T on urine samples collected from mice using a modified commercial NMR probe.« less

Combined use of irreversible binding and MRM technology for low- and ultralow copy-number protein detection and quantitation.

PubMed

Kopylov, Arthur T; Zgoda, Victor G; Lisitsa, Andrew V; Archakov, Alexander I

2013-03-01

In this paper, we present a method for the determination of low- and ultralow copy-number proteins in biomaterials based on a combination of concentrating the protein from the sample onto cyanogen bromide-activated Sepharose 4B (via nonspecific binding of free amino groups) and MRM. The detection limit and the dependence of the MRM peak areas on the concentration of protein in the sample were determined using the proteins CYP102 and BSA, as a model system, both in solution and after their addition to human plasma. Nonspecific protein enrichment of proteins from diluted sample volumes of 10-50 mL was found to increase the range of linear dependence of the chromatographic peak area on concentration by more than three orders of magnitude, allowing a lower LOD limit (LLOD) of as low as 10(-18) M. At this LLOD, at least two tryptic peptides of CYP102 and BSA could be detected with S/N of ≥7.0. The results were equally good for samples containing pure protein mixtures and proteins spiked into diluted depleted human blood plasma. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light sheet theta microscopy for rapid high-resolution imaging of large biological samples.

PubMed

Migliori, Bianca; Datta, Malika S; Dupre, Christophe; Apak, Mehmet C; Asano, Shoh; Gao, Ruixuan; Boyden, Edward S; Hermanson, Ola; Yuste, Rafael; Tomer, Raju

2018-05-29

Advances in tissue clearing and molecular labeling methods are enabling unprecedented optical access to large intact biological systems. These developments fuel the need for high-speed microscopy approaches to image large samples quantitatively and at high resolution. While light sheet microscopy (LSM), with its high planar imaging speed and low photo-bleaching, can be effective, scaling up to larger imaging volumes has been hindered by the use of orthogonal light sheet illumination. To address this fundamental limitation, we have developed light sheet theta microscopy (LSTM), which uniformly illuminates samples from the same side as the detection objective, thereby eliminating limits on lateral dimensions without sacrificing the imaging resolution, depth, and speed. We present a detailed characterization of LSTM, and demonstrate its complementary advantages over LSM for rapid high-resolution quantitative imaging of large intact samples with high uniform quality. The reported LSTM approach is a significant step for the rapid high-resolution quantitative mapping of the structure and function of very large biological systems, such as a clarified thick coronal slab of human brain and uniformly expanded tissues, and also for rapid volumetric calcium imaging of highly motile animals, such as Hydra, undergoing non-isomorphic body shape changes.

The relationship between limit of Dysphagia and average volume per swallow in patients with Parkinson's disease.

PubMed

Belo, Luciana Rodrigues; Gomes, Nathália Angelina Costa; Coriolano, Maria das Graças Wanderley de Sales; de Souza, Elizabete Santos; Moura, Danielle Albuquerque Alves; Asano, Amdore Guescel; Lins, Otávio Gomes

2014-08-01

The goal of this study was to obtain the limit of dysphagia and the average volume per swallow in patients with mild to moderate Parkinson's disease (PD) but without swallowing complaints and in normal subjects, and to investigate the relationship between them. We hypothesize there is a direct relationship between these two measurements. The study included 10 patients with idiopathic PD and 10 age-matched normal controls. Surface electromyography was recorded over the suprahyoid muscle group. The limit of dysphagia was obtained by offering increasing volumes of water until piecemeal deglutition occurred. The average volume per swallow was calculated by dividing the time taken by the number of swallows used to drink 100 ml of water. The PD group showed a significantly lower dysphagia limit and lower average volume per swallow. There was a significantly moderate direct correlation and association between the two measurements. About half of the PD patients had an abnormally low dysphagia limit and average volume per swallow, although none had spontaneously related swallowing problems. Both measurements may be used as a quick objective screening test for the early identification of swallowing alterations that may lead to dysphagia in PD patients, but the determination of the average volume per swallow is much quicker and simpler.

Pulsed Direct Current Electrospray: Enabling Systematic Analysis of Small Volume Sample by Boosting Sample Economy.

PubMed

Wei, Zhenwei; Xiong, Xingchuang; Guo, Chengan; Si, Xingyu; Zhao, Yaoyao; He, Muyi; Yang, Chengdui; Xu, Wei; Tang, Fei; Fang, Xiang; Zhang, Sichun; Zhang, Xinrong

2015-11-17

We had developed pulsed direct current electrospray ionization mass spectrometry (pulsed-dc-ESI-MS) for systematically profiling and determining components in small volume sample. Pulsed-dc-ESI utilized constant high voltage to induce the generation of single polarity pulsed electrospray remotely. This method had significantly boosted the sample economy, so as to obtain several minutes MS signal duration from merely picoliter volume sample. The elongated MS signal duration enable us to collect abundant MS(2) information on interested components in a small volume sample for systematical analysis. This method had been successfully applied for single cell metabolomics analysis. We had obtained 2-D profile of metabolites (including exact mass and MS(2) data) from single plant and mammalian cell, concerning 1034 components and 656 components for Allium cepa and HeLa cells, respectively. Further identification had found 162 compounds and 28 different modification groups of 141 saccharides in a single Allium cepa cell, indicating pulsed-dc-ESI a powerful tool for small volume sample systematical analysis.

An inexpensive and portable microvolumeter for rapid evaluation of biological samples.

PubMed

Douglass, John K; Wcislo, William T

2010-08-01

We describe an improved microvolumeter (MVM) for rapidly measuring volumes of small biological samples, including live zooplankton, embryos, and small animals and organs. Portability and low cost make this instrument suitable for widespread use, including at remote field sites. Beginning with Archimedes' principle, which states that immersing an arbitrarily shaped sample in a fluid-filled container displaces an equivalent volume, we identified procedures that maximize measurement accuracy and repeatability across a broad range of absolute volumes. Crucial steps include matching the overall configuration to the size of the sample, using reflected light to monitor fluid levels precisely, and accounting for evaporation during measurements. The resulting precision is at least 100 times higher than in previous displacement-based methods. Volumes are obtained much faster than by traditional histological or confocal methods and without shrinkage artifacts due to fixation or dehydration. Calibrations using volume standards confirmed accurate measurements of volumes as small as 0.06 microL. We validated the feasibility of evaluating soft-tissue samples by comparing volumes of freshly dissected ant brains measured with the MVM and by confocal reconstruction.

Uranium in US surface, ground, and domestic waters. Volume 2

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

Drury, J.S.; Reynolds, S.; Owen, P.T.

1981-04-01

The report Uranium in US Surface, Ground, and Domestic Waters comprises four volumes. Volumes 2, 3, and 4 contain data characterizing the location, sampling date, type, use, and uranium conentrations of 89,994 individual samples presented in tabular form. The tabular data in volumes 2, 3, and 4 are summarized in volume 1 in narrative form and with maps and histograms.

Uniform enhancement of optical micro-angiography images using Rayleigh contrast-limited adaptive histogram equalization

PubMed Central

Yousefi, Siavash; Qin, Jia; Zhi, Zhongwei

2013-01-01

Optical microangiography is an imaging technology that is capable of providing detailed functional blood flow maps within microcirculatory tissue beds in vivo. Some practical issues however exist when displaying and quantifying the microcirculation that perfuses the scanned tissue volume. These issues include: (I) Probing light is subject to specular reflection when it shines onto sample. The unevenness of the tissue surface makes the light energy entering the tissue not uniform over the entire scanned tissue volume. (II) The biological tissue is heterogeneous in nature, meaning the scattering and absorption properties of tissue would attenuate the probe beam. These physical limitations can result in local contrast degradation and non-uniform micro-angiogram images. In this paper, we propose a post-processing method that uses Rayleigh contrast-limited adaptive histogram equalization to increase the contrast and improve the overall appearance and uniformity of optical micro-angiograms without saturating the vessel intensity and changing the physical meaning of the micro-angiograms. The qualitative and quantitative performance of the proposed method is compared with those of common histogram equalization and contrast enhancement methods. We demonstrate that the proposed method outperforms other existing approaches. The proposed method is not limited to optical microangiography and can be used in other image modalities such as photo-acoustic tomography and scanning laser confocal microscopy. PMID:23482880

In-vivo digital wavefront sensing using swept source OCT

PubMed Central

Kumar, Abhishek; Wurster, Lara M.; Salas, Matthias; Ginner, Laurin; Drexler, Wolfgang; Leitgeb, Rainer A.

2017-01-01

Sub-aperture based digital adaptive optics is demonstrated in a fiber based point scanning optical coherence tomography system using a 1060 nm swept source laser. To detect optical aberrations in-vivo, a small lateral field of view of ~150×150 μm2 is scanned on the sample at a high volume rate of 17 Hz (~1.3 kHz B-scan rate) to avoid any significant lateral and axial motion of the sample, and is used as a “guide star” for the sub-aperture based DAO. The proof of principle is demonstrated using a micro-beads phantom sample, wherein a significant root mean square wavefront error (RMS WFE) of 1.48 waves (> 1μm) is detected. In-vivo aberration measurement with a RMS WFE of 0.33 waves, which is ~5 times higher than the Marechal’s criterion of 1/14 waves for the diffraction limited performance, is shown for a human retinal OCT. Attempt has been made to validate the experimental results with the conventional Shack-Hartmann wavefront sensor within reasonable limitations. PMID:28717573

Impact of Use of Smaller Volume, Smaller Vacuum Blood Collection Tubes on Hemolysis in Emergency Department Blood Samples.

PubMed

Phelan, Michael P; Reineks, Edmunds Z; Berriochoa, Jacob P; Schold, Jesse D; Hustey, Fredric M; Chamberlin, Janelle; Kovach, Annmarie

2017-10-01

Hemolyzed blood samples commonly occur in hospital emergency departments (EDs). Our objective was to determine whether replacing standard large-volume/high-vacuum sample tubes with low-volume/low-vacuum tubes would significantly affect ED hemolysis. This was a prospective intervention of the use of small-volume/vacuum collection tubes. We evaluated all potassium samples in ED patients and associated hemolysis. We used χ2 tests to compare hemolysis incidence prior to and following utilization of small tubes for chemistry collection. There were 35,481 blood samples collected during the study period. Following implementation of small-volume tubes, overall hemolysis decreased from a baseline of 11.8% to 2.9% (P < .001) with corresponding reductions in hemolysis with comment (8.95% vs 1.99%; P < .001) gross hemolysis (2.84% vs 0.90%; P < .007). This work demonstrates that significant improvements in ED hemolysis can be achieved by utilization of small-volume/vacuum sample collection tubes. © American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Purge-and-trap ion chromatography for the determination of trace ammonium ion in high-salinity water samples.

PubMed

Wang, Po-Yen; Wu, Jing-Yi; Chen, Hung-Jhen; Lin, Tzung-Yi; Wu, Chien-Hou

2008-04-25

It has always been assumed that purge-and-trap (P&T) method is only used for the analysis of volatile organic compounds (VOCs) in aqueous samples. In this paper, a novel P&T preconcentrator has been developed for the determination of trace amounts of ammonium ion in high-salinity water samples by ion chromatography (IC). Method performance is evaluated as a function of concentration of assistant purging material, purging time, and flow rate. Under the optimum P&T conditions with the purified nitrogen gas at flow rate 40 mL/min for 15.0 min at 40 degrees C, the overall collection efficiency is independent of the concentration of ammonium over the range 1.2-5.9 microM. The enrichment factor (EF) of ammonium correlates the ratio of the sample volume to the acceptor solution volume in the trap vessel, providing potentially unlimited increase of the ammonium signal. Our results indicate that environmental samples with low levels of ammonium in matrices with high concentrations of sodium can be easily analyzed and the detection limit down to 75 nM (1.35 ppb) level, corresponding to picomole of ammonia in the injected sample. Calibration graph was constructed with ammonium standards ranging from 0.05 to 6.0 microM and the linearity of the present method was good as suggested by the square of correlation coefficients being better than 0.997. Thus, we have demonstrated that the P&T-IC method allows the routine determination of ammonium ion in seawater samples without cation interferences.

Major depressive episodes over the course of 7 years and hippocampal subfield volumes at 7 tesla MRI: the PREDICT-MR study.

PubMed

Wisse, L E M; Biessels, G J; Stegenga, B T; Kooistra, M; van der Veen, P H; Zwanenburg, J J M; van der Graaf, Y; Geerlings, M I

2015-04-01

Smaller hippocampal volumes have been associated with major depressive disorder (MDD). The hippocampus consists of several subfields that may be differentially related to MDD. We investigated the association of occurrence of major depressive episodes (MDEs), assessed five times over seven years, with hippocampal subfield and entorhinal cortex volumes at 7 tesla MRI. In this prospective study of randomly selected general practice attendees, MDEs according to DSM-IV-R criteria were assessed at baseline and after 6, 12, 39 and 84 months follow-up. At the last follow-up, a T2 (0.7 mm(3)) 7 tesla MRI scan was obtained in 47 participants (60±10 years). The subiculum, cornu ammonis (CA) 1 to 3, dentate gyrus&CA4 and entorhinal cortex volumes were manually segmented according a published protocol. Of the 47 participants, 13 had one MDE and 5 had multiple MDEs. ANCOVAs, adjusted for age, sex, education and intracranial volume, revealed no significant differences in hippocampal subfield or entorhinal cortex volumes between participants with and without an MDE in the preceding 84 months. Multiple episodes were associated with smaller subiculum volumes (B=-0.03 mL/episode; 95% CI -0.06; -0.003), but not with the other hippocampal subfield volumes, entorhinal cortex, or total hippocampal volume. A limitation of this study is the small sample size which makes replication necessary. In this exploratory study, we found that an increasing number of major depressive episodes was associated with smaller subiculum volumes in middle-aged and older persons, but not with smaller volumes in other hippocampal subfields or the entorhinal cortex. Copyright © 2014 Elsevier B.V. All rights reserved.

Nanotechnology: moving from microarrays toward nanoarrays.

PubMed

Chen, Hua; Li, Jun

2007-01-01

Microarrays are important tools for high-throughput analysis of biomolecules. The use of microarrays for parallel screening of nucleic acid and protein profiles has become an industry standard. A few limitations of microarrays are the requirement for relatively large sample volumes and elongated incubation time, as well as the limit of detection. In addition, traditional microarrays make use of bulky instrumentation for the detection, and sample amplification and labeling are quite laborious, which increase analysis cost and delays the time for obtaining results. These problems limit microarray techniques from point-of-care and field applications. One strategy for overcoming these problems is to develop nanoarrays, particularly electronics-based nanoarrays. With further miniaturization, higher sensitivity, and simplified sample preparation, nanoarrays could potentially be employed for biomolecular analysis in personal healthcare and monitoring of trace pathogens. In this chapter, it is intended to introduce the concept and advantage of nanotechnology and then describe current methods and protocols for novel nanoarrays in three aspects: (1) label-free nucleic acids analysis using nanoarrays, (2) nanoarrays for protein detection by conventional optical fluorescence microscopy as well as by novel label-free methods such as atomic force microscopy, and (3) nanoarray for enzymatic-based assay. These nanoarrays will have significant applications in drug discovery, medical diagnosis, genetic testing, environmental monitoring, and food safety inspection.

Quantification of the xenoestrogens 4-tert.-octylphenol and bisphenol A in water and in fish tissue based on microwave assisted extraction, solid-phase extraction and liquid chromatography-mass spectrometry.

PubMed

Pedersen, S N; Lindholst, C

1999-12-09

Extraction methods were developed for quantification of the xenoestrogens 4-tert.-octylphenol (tOP) and bisphenol A (BPA) in water and in liver and muscle tissue from the rainbow trout (Oncorhynchus mykiss). The extraction of tOP and BPA from tissue samples was carried out using microwave-assisted solvent extraction (MASE) followed by solid-phase extraction (SPE). Water samples were extracted using only SPE. For the quantification of tOP and BPA, liquid chromatography mass spectrometry (LC-MS) equipped with an atmospheric pressure chemical ionisation interface (APCI) was applied. The combined methods for tissue extraction allow the use of small sample amounts of liver or muscle (typically 1 g), low volumes of solvent (20 ml), and short extraction times (25 min). Limits of quantification of tOP in tissue samples were found to be approximately 10 ng/g in muscle and 50 ng/g in liver (both based on 1 g of fresh tissue). The corresponding values for BPA were approximately 50 ng/g in both muscle and liver tissue. In water, the limit of quantification for tOP and BPA was approximately 0.1 microg/l (based on 100 ml sample size).

Integrated chemical/biochemical sample collection, pre-concentration, and analysis on a digital microfluidic lab-on-a-chip platform

NASA Astrophysics Data System (ADS)

Fair, Richard B.; Khlystov, A.; Srinivasan, Vijay; Pamula, Vamsee K.; Weaver, Kathryn N.

2004-12-01

An ideal on-site chemical/biochemical analysis system must be inexpensive, sensitive, fully automated and integrated, reliable, and compatible with a broad range of samples. The advent of digital microfluidic lab-on-a-chip (LoC) technology offers such a detection system due to the advantages in portability, reduction of the volumes of the sample and reagents, faster analysis times, increased automation, low power consumption, compatibility with mass manufacturing, and high throughput. We describe progress towards integrating sample collection onto a digital microfluidic LoC that is a component of a cascade impactor device. The sample collection is performed by impacting airborne particles directly onto the surface of the chip. After the collection phase, the surface of the chip is washed with a micro-droplet of solvent. The droplet will be digitally directed across the impaction surface, dissolving sample constituents. Because of the very small droplet volume used for extraction of the sample from a wide colection area, the resulting solution is realatively concentrated and the analytes can be detected after a very short sampling time (1 min) due to such pre-concentration. After the washing phase, the droplet is mixed with specific reagents that produce colored reaction products. The concentration of the analyte is quantitatively determined by measuring absorption at target wavelengths using a simple light emitting diode and photodiode setup. Specific applications include automatic measurements of major inorganic ions in aerosols, such as sulfate, nitrate and ammonium, with a time resolution of 1 min and a detection limit of 30 nm/m3. We have already demonstrated the detection and quantification of nitroaromatic explosives without integrating the sample collection. Other applications being developed include airborne bioagent detection.

Integration of 3D intraoperative ultrasound for enhanced neuronavigation

NASA Astrophysics Data System (ADS)

Paulsen, Keith D.; Ji, Songbai; Hartov, Alex; Fan, Xiaoyao; Roberts, David W.

2012-03-01

True three-dimensional (3D) volumetric ultrasound (US) acquisitions stand to benefit intraoperative neuronavigation on multiple fronts. While traditional two-dimensional (2D) US and its tracked, hand-swept version have been recognized for many years to advantage significantly image-guided neurosurgery, especially when coregistered with preoperative MR scans, its unregulated and incomplete sampling of the surgical volume of interest have limited certain intraoperative uses of the information that are overcome through direct volume acquisition (i.e., through 2D scan-head transducer arrays). In this paper, we illustrate several of these advantages, including image-based intraoperative registration (and reregistration) and automated, volumetric displacement mapping for intraoperative image updating. These applications of 3D US are enabled by algorithmic advances in US image calibration, and volume rasterization and interpolation for multi-acquisition synthesis that will also be highlighted. We expect to demonstrate that coregistered 3D US is well worth incorporating into the standard neurosurgical navigational environment relative to traditional tracked, hand-swept 2D US.

Liquid scintillation sample analysis in microcentrifuge tubes.

PubMed

Elliott, J C

1993-01-01

Local regulations prohibiting drain disposal of "biodegradable" liquid scintillation cocktails prompted investigation of volume reduction for these materials. Microcentrifuge tubes were used with aqueous and filter media samples of 3H, 14C, 32P, and 125I. Backgrounds, counting efficiencies, figures of merit, and spectral distributions obtained for microcentrifuge tubes compared favorably to conventional vials. Differences in 32P spectra for solid support samples appeared related to filter material and sample volume. Decreases in sample costs and waste volume and disposal costs were approximately 50-75%.

Developmentally stable whole-brain volume reductions and developmentally sensitive caudate and putamen volume alterations in those with attention-deficit/hyperactivity disorder and their unaffected siblings.

PubMed

Greven, Corina U; Bralten, Janita; Mennes, Maarten; O'Dwyer, Laurence; van Hulzen, Kimm J E; Rommelse, Nanda; Schweren, Lizanne J S; Hoekstra, Pieter J; Hartman, Catharina A; Heslenfeld, Dirk; Oosterlaan, Jaap; Faraone, Stephen V; Franke, Barbara; Zwiers, Marcel P; Arias-Vasquez, Alejandro; Buitelaar, Jan K

2015-05-01

Attention-deficit/hyperactivity disorder (ADHD) is a heritable neurodevelopmental disorder. It has been linked to reductions in total brain volume and subcortical abnormalities. However, owing to heterogeneity within and between studies and limited sample sizes, findings on the neuroanatomical substrates of ADHD have shown considerable variability. Moreover, it remains unclear whether neuroanatomical alterations linked to ADHD are also present in the unaffected siblings of those with ADHD. To examine whether ADHD is linked to alterations in whole-brain and subcortical volumes and to study familial underpinnings of brain volumetric alterations in ADHD. In this cross-sectional study, we included participants from the large and carefully phenotyped Dutch NeuroIMAGE sample (collected from September 2009-December 2012) consisting of 307 participants with ADHD, 169 of their unaffected siblings, and 196 typically developing control individuals (mean age, 17.21 years; age range, 8-30 years). Whole-brain volumes (total brain and gray and white matter volumes) and volumes of subcortical regions (nucleus accumbens, amygdala, caudate nucleus, globus pallidus, hippocampus, putamen, thalamus, and brainstem) were derived from structural magnetic resonance imaging scans using automated tissue segmentation. Regression analyses revealed that relative to control individuals, participants with ADHD had a 2.5% smaller total brain (β = -31.92; 95% CI, -52.69 to -11.16; P = .0027) and a 3% smaller total gray matter volume (β = -22.51; 95% CI, -35.07 to -9.96; P = .0005), while total white matter volume was unaltered (β = -10.10; 95% CI, -20.73 to 0.53; P = .06). Unaffected siblings had total brain and total gray matter volumes intermediate to participants with ADHD and control individuals. Significant age-by-diagnosis interactions showed that older age was linked to smaller caudate (P < .001) and putamen (P = .01) volumes (both corrected for total brain volume) in control individuals, whereas age was unrelated to these volumes in participants with ADHD and their unaffected siblings. Attention-deficit/hyperactivity disorder was not significantly related to the other subcortical volumes. Global differences in gray matter volume may be due to alterations in the general mechanisms underlying normal brain development in ADHD. The age-by-diagnosis interaction in the caudate and putamen supports the relevance of different brain developmental trajectories in participants with ADHD vs control individuals and supports the role of subcortical basal ganglia alterations in the pathophysiology of ADHD. Alterations in total gray matter and caudate and putamen volumes in unaffected siblings suggest that these volumes are linked to familial risk for ADHD.

The Neutron Tomography Studies of the Rocks from the Kola Superdeep Borehole

NASA Astrophysics Data System (ADS)

Kichanov, S. E.; Kozlenko, D. P.; Ivankina, T. I.; Rutkauskas, A. V.; Lukin, E. V.; Savenko, B. N.

The volume morphology of a gneiss sample K-8802 recovered from the deep of 8802 m of the Kola Superdeep Borehole and its surface homologue sample PL-36 have been studied by means of neutron radiography and tomography methods. The volumes and size distributions of a biotite-muscovite grains as well as grains orientation distribution have been obtained from experimental data. It was found that the average volumes of the biotite-muscovite grains in surface homologue sample is noticeably larger than the average volume of grains in the deep-seated gneiss sample K-8802. This drastically differences in grains volumes can be explained by the recrystallization processes in deep of the Kola Superdeep Borehole at high temperatures and high pressures.

Whispering Gallery Mode Resonators for Rapid Label-Free Biosensing in Small Volume Droplets

PubMed Central

Wildgen, Sarah M.; Dunn, Robert C.

2015-01-01

Rapid biosensing requires fast mass transport of the analyte to the surface of the sensing element. To optimize analysis times, both mass transport in solution and the geometry and size of the sensing element need to be considered. Small dielectric spheres, tens of microns in diameter, can act as label-free biosensors using whispering gallery mode (WGM) resonances. WGM resonances are sensitive to the effective refractive index, which changes upon analyte binding to recognition sites on functionalized resonators. The spherical geometry and tens of microns diameter of these resonators provides an efficient target for sensing while their compact size enables detection in limited volumes. Here, we explore conditions leading to rapid analyte detection using WGM resonators as label-free sensors in 10 μL sample droplets. Droplet evaporation leads to potentially useful convective mixing, but also limits the time over which analysis can be completed. We show that active droplet mixing combined with initial binding rate measurements is required for accurate nanomolar protein quantification within the first minute following injection. PMID:25806835

Reflotron cholesterol measurement in general practice: accuracy and detection of errors.

PubMed

Ball, M J; Robertson, I K; Woods, M

1994-11-01

Comparison of cholesterol determinations by nurses using a Reflotron analyser in a general practice setting showed a good correlation with plasma cholesterol determinations by wet chemistry in a clinical biochemistry laboratory. A limited number of comparisons did, however, give a much lower result on the Reflotron. In an experimental situation, small sample volumes (which could result from poor technique) were shown to produce falsely low readings. A simple method which may immediately detect falsely low Reflotron readings is discussed.

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

Erchinger, J. L.; Orrell, John L.; Aalseth, C. E.

The Ultra-Low Background Liquid Scintillation Counter developed by Pacific Northwest National Laboratory will expand the application of liquid scintillation counting by enabling lower detection limits and smaller sample volumes. By reducing the overall count rate of the background environment approximately 2 orders of magnitude below that of commercially available systems, backgrounds on the order of tens of counts per day over an energy range of ~3–3600 keV can be realized. Finally, initial test results of the ULB LSC show promising results for ultra-low background detection with liquid scintillation counting.

Técnica de Construcción de Catálogos Sintéticos

NASA Astrophysics Data System (ADS)

Díaz, M. E.; Muriel, H.; Merchán, M.

We present a mock catalogue construction technic which enable us to mimic simultaniously several observational properties, such as spectral types, angular positions, redshifts distribution, aparent and absolut magnitudes and gravitational evolution. We analyze some prescriptions for volume and flux limited samples. As an aplication, we present a mock catalogue of the 2dF redshift survey and the corresponding comparison between the observational properties of the real data and the corresponding to the mock catalogue constructed in this work.

Digital visual communications using a Perceptual Components Architecture

NASA Technical Reports Server (NTRS)

Watson, Andrew B.

1991-01-01

The next era of space exploration will generate extraordinary volumes of image data, and management of this image data is beyond current technical capabilities. We propose a strategy for coding visual information that exploits the known properties of early human vision. This Perceptual Components Architecture codes images and image sequences in terms of discrete samples from limited bands of color, spatial frequency, orientation, and temporal frequency. This spatiotemporal pyramid offers efficiency (low bit rate), variable resolution, device independence, error-tolerance, and extensibility.

High-accuracy measurements of N2O concentration and site-specific nitrogen isotopes in small or high concentration samples

NASA Astrophysics Data System (ADS)

Palmer, M. R.; Arata, C.; Huang, K.

2014-12-01

Nitrous oxide (N2O) gas is among the major contributors to global warming and ozone depletion in stratosphere. Quantitative estimate of N­2O production in various pathways and N­2O fluxes across different reservoirs is the key to understanding the role of N­2O in the global change. To achieve this goal, accurate and concurrent measurement of both N2O concentration ([N2O]) and its site-specific isotopic composition (SP-δ15N), namely δ15Nα and δ15Nβ, is desired. Recent developments in Cavity Ring-Down Spectroscopy (CRDS) have enabled high precision measurements of [N2O] and SP-δ15N of a continuous gas flow. However, many N­­2O samples are discrete with limited volume (< 500 ml), and/or high [N2O] (> 2 ppm), and are not suitable for direct measurements by CRDS. Here we present results of a Small Sample Isotope Module 2 (SSIM2) which is coupled to and automatically coordinated with a Picarro isotopic N2O CRDS analyzer to handle and measure high concentration and/or small volume samples. The SSIM2 requires 20 ml of sample per analysis, and transfers the sample to the CRDS for high precision measurement. When the sample injection is < 20 ml, a zero gas is optionally filled to make up the volume. We used the SSIM2 to dilute high [N2O] samples and < 20 ml samples, and tested the effect of dilution on the measured SP-δ15N. In addition, we employed and tested a newly developed double injection method for samples adequate for two 20 ml injections. After the SSIM2 and the CRDS cavity was primed with the first injection, the second injection, which has negligible dilution of the sample, can be accurately measured for both [N2O] and SP-δ15N. Results of these experiments indicate that the precision of SSIM2-CRDS is similar to that of the continuous measurements using the CRDS alone, and that dilution has minimal effect on SP-δ15N, as along as the [N2O] is > 300 ppb after dilution. Overall, the precision of SP-δ15N measured using the SSIM2 is < 0.5 ‰.

The ATLAS3D project - I. A volume-limited sample of 260 nearby early-type galaxies: science goals and selection criteria

NASA Astrophysics Data System (ADS)

Cappellari, Michele; Emsellem, Eric; Krajnović, Davor; McDermid, Richard M.; Scott, Nicholas; Verdoes Kleijn, G. A.; Young, Lisa M.; Alatalo, Katherine; Bacon, R.; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, M.; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Khochfar, Sadegh; Kuntschner, Harald; Lablanche, Pierre-Yves; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Serra, Paolo; Weijmans, Anne-Marie

2011-05-01

The ATLAS3D project is a multiwavelength survey combined with a theoretical modelling effort. The observations span from the radio to the millimetre and optical, and provide multicolour imaging, two-dimensional kinematics of the atomic (H I), molecular (CO) and ionized gas (Hβ, [O III] and [N I]), together with the kinematics and population of the stars (Hβ, Fe5015 and Mg b), for a carefully selected, volume-limited (1.16 × 105 Mpc3) sample of 260 early-type (elliptical E and lenticular S0) galaxies (ETGs). The models include semi-analytic, N-body binary mergers and cosmological simulations of galaxy formation. Here we present the science goals for the project and introduce the galaxy sample and the selection criteria. The sample consists of nearby (D < 42 Mpc, |δ- 29°| < 35°, |b| > 15°) morphologically selected ETGs extracted from a parent sample of 871 galaxies (8 per cent E, 22 per cent S0 and 70 per cent spirals) brighter than MK < -21.5 mag (stellar mass M★≳ 6 ×109 M⊙). We analyse possible selection biases and we conclude that the parent sample is essentially complete and statistically representative of the nearby galaxy population. We present the size-luminosity relation for the spirals and ETGs and show that the ETGs in the ATLAS3D sample define a tight red sequence in a colour-magnitude diagram, with few objects in the transition from the blue cloud. We describe the strategy of the SAURON integral field observations and the extraction of the stellar kinematics with the pPXF method. We find typical 1σ errors of ΔV≈ 6 km s-1, Δσ≈ 7 km s-1, Δh3≈Δh4≈ 0.03 in the mean velocity, the velocity dispersion and Gauss-Hermite (GH) moments for galaxies with effective dispersion σe≳ 120 km s-1. For galaxies with lower σe (≈40 per cent of the sample) the GH moments are gradually penalized by pPXF towards zero to suppress the noise produced by the spectral undersampling and only V and σ can be measured. We give an overview of the characteristics of the other main data sets already available for our sample and of the ongoing modelling projects.

Concentrations of tritium and strontium-90 in water from selected wells at the Idaho National Engineering Laboratory after purging one, two, and three borehole volumes

USGS Publications Warehouse

Bartholomay, R.C.

1993-01-01

Water from 11 wells completed in the Snake River Plain aquifer at the Idaho National Engineering Laboratory was sampled as part of the U.S. Geological Survey's quality assurance program to determine the effect of purging different borehole volumes on tritium and strontium-90 concentrations. Wells were selected for sampling on the basis of the length of time it took to purge a borehole volume of water. Samples were collected after purging one, two, and three borehole volumes. The U.S. Department of Energy's Radiological and Environmental Sciences Laboratory provided analytical services. Statistics were used to determine the reproducibility of analytical results. The comparison between tritium and strontium-90 concentrations after purging one and three borehole volumes and two and three borehole volumes showed that all but two sample pairs with defined numbers were in statistical agreement. Results indicate that concentrations of tritium and strontium-90 are not affected measurably by the number of borehole volumes purged.

Using Hematology Data from Malaria Vaccine Research Trials in Humans and Rhesus Macaques (Macaca mulatta) To Guide Volume Limits for Blood Withdrawal.

PubMed

Hegge, Sara R; Hickey, Bradley W; Mcgrath, Shannon M; Stewart, V Ann

2016-12-01

Guidelines on safe volume limits for blood collection from research participants in both humans and laboratory animals vary widely between institutions. The main adverse event that may be encountered in large blood volume withdrawal is iron-deficiency anemia. Monitoring various parameters in a standard blood panel may help to prevent this outcome. To this end, we analyzed the Hgb and MCV values from 43 humans and 46 macaques in malaria vaccine research trials. Although the percentage of blood volume removed was greater for macaques than humans, macaques demonstrated an overall increase of MCV over time, indicating the ability to respond appropriately to frequent volume withdrawals. In contrast, humans showed a consistent declining trend in MCV. These declines in human MCV and Hgb were significant from the beginning to end of the study despite withdrawals that were smaller than recommended volume limits. Limiting the volume withdrawn to no more than 12.5% seemed to be sufficient for macaques, and at 14% or more individual animals tended to fail to respond appropriately to large-volume blood loss, as demonstrated by a decrease in MCV. The overall positive erythropoietic response seen in macaques was likely due to the controlled, iron-fortified diet they received. The lack of erythropoietic response in the human subjects may warrant iron supplementation or reconsideration of current blood volume withdrawal guidelines.

Random Numbers and Monte Carlo Methods

NASA Astrophysics Data System (ADS)

Scherer, Philipp O. J.

Many-body problems often involve the calculation of integrals of very high dimension which cannot be treated by standard methods. For the calculation of thermodynamic averages Monte Carlo methods are very useful which sample the integration volume at randomly chosen points. After summarizing some basic statistics, we discuss algorithms for the generation of pseudo-random numbers with given probability distribution which are essential for all Monte Carlo methods. We show how the efficiency of Monte Carlo integration can be improved by sampling preferentially the important configurations. Finally the famous Metropolis algorithm is applied to classical many-particle systems. Computer experiments visualize the central limit theorem and apply the Metropolis method to the traveling salesman problem.

Characterization and optimization of low cost microfluidic thread based electroanalytical device for micro flow injection analysis.

PubMed

Agustini, Deonir; Bergamini, Márcio F; Marcolino-Junior, Luiz Humberto

2017-01-25

The micro flow injection analysis (μFIA) is a powerful technique that uses the principles of traditional flow analysis in a microfluidic device and brings a number of improvements related to the consumption of reagents and samples, speed of analysis and portability. However, the complexity and cost of manufacturing processes, difficulty in integrating micropumps and the limited performance of systems employing passive pumps are challenges that must be overcome. Here, we present the characterization and optimization of a low cost device based on cotton threads as microfluidic channel to perform μFIA based on passive pumps with good analytical performance in a simple, easy and inexpensive way. The transport of solutions is made through cotton threads by capillary force facilitated by gravity. After studying and optimizing several features related to the device, were obtained a flow rate of 2.2 ± 0.1 μL s -1 , an analytical frequency of 208 injections per hour, a sample injection volume of 2.0 μL and a waste volume of approximately 40 μL per analysis. For chronoamperometric determination of naproxen, a detection limit of 0.29 μmol L -1 was reached, with a relative standard deviation (RSD) of 1.69% between injections and a RSD of 3.79% with five different devices. Thus, based on the performance presented by proposed microfluidic device, it is possible to overcome some limitations of the μFIA systems based on passive pumps and allow expansion in the use of this technique. Copyright © 2016 Elsevier B.V. All rights reserved.

Cleaning verification: A five parameter study of a Total Organic Carbon method development and validation for the cleaning assessment of residual detergents in manufacturing equipment.

PubMed

Li, Xue; Ahmad, Imad A Haidar; Tam, James; Wang, Yan; Dao, Gina; Blasko, Andrei

2018-02-05

A Total Organic Carbon (TOC) based analytical method to quantitate trace residues of clean-in-place (CIP) detergents CIP100 ® and CIP200 ® on the surfaces of pharmaceutical manufacturing equipment was developed and validated. Five factors affecting the development and validation of the method were identified: diluent composition, diluent volume, extraction method, location for TOC sample preparation, and oxidant flow rate. Key experimental parameters were optimized to minimize contamination and to improve the sensitivity, recovery, and reliability of the method. The optimized concentration of the phosphoric acid in the swabbing solution was 0.05M, and the optimal volume of the sample solution was 30mL. The swab extraction method was 1min sonication. The use of a clean room, as compared to an isolated lab environment, was not required for method validation. The method was demonstrated to be linear with a correlation coefficient (R) of 0.9999. The average recoveries from stainless steel surfaces at multiple spike levels were >90%. The repeatability and intermediate precision results were ≤5% across the 2.2-6.6ppm range (50-150% of the target maximum carry over, MACO, limit). The method was also shown to be sensitive with a detection limit (DL) of 38ppb and a quantitation limit (QL) of 114ppb. The method validation demonstrated that the developed method is suitable for its intended use. The methodology developed in this study is generally applicable to the cleaning verification of any organic detergents used for the cleaning of pharmaceutical manufacturing equipment made of electropolished stainless steel material. Copyright © 2017 Elsevier B.V. All rights reserved.

Permeability of gypsum samples dehydrated in air

NASA Astrophysics Data System (ADS)

Milsch, Harald; Priegnitz, Mike; Blöcher, Guido

2011-09-01

We report on changes in rock permeability induced by devolatilization reactions using gypsum as a reference analog material. Cylindrical samples of natural alabaster were dehydrated in air (dry) for up to 800 h at ambient pressure and temperatures between 378 and 423 K. Subsequently, the reaction kinetics, so induced changes in porosity, and the concurrent evolution of sample permeability were constrained. Weighing the heated samples in predefined time intervals yielded the reaction progress where the stoichiometric mass balance indicated an ultimate and complete dehydration to anhydrite regardless of temperature. Porosity showed to continuously increase with reaction progress from approximately 2% to 30%, whilst the initial bulk volume remained unchanged. Within these limits permeability significantly increased with porosity by almost three orders of magnitude from approximately 7 × 10-19 m2 to 3 × 10-16 m2. We show that - when mechanical and hydraulic feedbacks can be excluded - permeability, reaction progress, and porosity are related unequivocally.

Humidity sensitive polymers In solution processed adjustable pore-volume Cu(In,Ga)S2 photocathodes for solar hydrogen production

NASA Astrophysics Data System (ADS)

Zhang, Chuan; Luo, Wenjun; Wen, Xin; Guan, Zhongjie; Zou, Zhigang

2017-11-01

P-type Cu(In,Ga)S2 semiconductors are promising candidates to be used as photocathodes for solar water splitting. Porous structures have been widely used to improve the performances of photoelectrodes due to good minority carrier transport. However, a porous photoelectrode has longer transport distance of majority carriers, which limits its performance. Controlling pore volume of a photoelectrode can balance minority and majority carrier transport and improve the performance. Here, a porous Cu(In,Ga)S2 film is prepared by facile spin-coating method. The pore volume of Cu(In,Ga)S2 film is controlled by adjusting relative humidity (RH) of air during spin-coating process. Further studies suggest that polyvinyl acetate (PVAc) in precursor solution is a humidity sensitive polymer and plays a key role to form different pore volume. The 40% RH sample has the best performance due to its optimum pore volume. After further coated with CdS surface passivation layer and Pt electrocatalyst on the surface, a 40% RH Cu(In,Ga)S2 photocathode indicates a photocurrent density of 8.6 mA cm-2 at 0 V RHE, which is one of the highest photocurrents of Cu(In,Ga)S2 photocathodes. This new strategy for adjusting pore volume is also suitable to prepare other solution-processed inorganic materials.

Determination of chloropropanols in foods by one-step extraction and derivatization using pressurized liquid extraction and gas chromatography-mass spectrometry.

PubMed

Racamonde, I; González, P; Lorenzo, R A; Carro, A M

2011-09-28

3-Chloropropane-1,2-diol (3-MCPD) and 1,3-dichloro-2-propanol (1,3-DCP) were determined for the first time in bakery foods using pressurized liquid extraction (PLE) combined with in situ derivatization and GC-MS analysis. This one-step protocol uses N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) as silylation reagent. Initially, screening experimental design was applied to evaluate the effects of the variables potentially affecting the extraction process, namely extraction time (min) and temperature (°C), number of cycles, dispersant reagent (diatomaceous earth in powder form and as particulate matter with high pore volume Extrelut NT) and percent of flush ethyl acetate volume (%). To reduce the time of analysis and improve the sensitivity, derivatization of the compounds was performed in the cell extraction. Conditions, such as the volume of BSTFA, temperature and time for the in situ derivatization of analytes using PLE, were optimized by a screening design followed to a Doehlert response surface design. The effect of the in-cell dispersants/adsorbents with diatomaceous earth, Florisil and sodium sulfate anhydrous was investigated using a Box-Behnken design. Using the final best conditions, 1 g of sample dispersed with 0.1 g of sodium sulfate anhydrous and 2.5 g diatomaceous earth was extracted with ethyl acetate. 1 g of Florisil, as clean-up adsorbent, and 70 μL of BSTFA were used for 3 min at 70°C. Under the optimum conditions, the calibration curves showed good linearity (R(2)>0.9994) and precision (relative standard deviation, RSD≤2.4%) within the tested ranges. The limits of quantification for 1,3-DCP and 3-MCDP, 1.6 and 1.7 μg kg(-1), respectively, are far below the established limits in the European and American legislations. The accuracy, precision, linearity, and limits of quantification provided make this analytical method suitable for routine control. The method was applied to the analysis of several toasted bread, snacks, cookies and cereal samples, none of which contained chloropropanols at concentrations above the legislation levels. Copyright © 2011 Elsevier B.V. All rights reserved.

Application of a surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for micro-volume based spectrophotometric determination of low level of Cr(VI) ions in aquatic samples.

PubMed

Sobhi, Hamid Reza; Azadikhah, Efat; Behbahani, Mohammad; Esrafili, Ali; Ghambarian, Mahnaz

2018-05-09

A fast, simple, low cost surfactant-assisted dispersive liquid-liquid microextraction method along with central composite design for the determination of low level of Cr(VI) ions in several aquatic samples has been developed. Initially, Cr(VI) ions present in the aqueous sample were readily reacted with 1,5‑diphenylcarbazide (DPC) in acidic medium through complexation. Sodium dodecyl sulfate (SDS), as an anionic surfactant, was then employed as an ion-pair agent to convert the cationic complex into the neutral one. Following on, the whole aqueous phase underwent a dispersive liquid-liquid microextraction (DLLME) leading to the transfer of the neutral complex into the fine droplet of organic extraction phase. A micro-volume spectrophotometer was used to determine Cr(VI) concentrations. Under the optimized conditions predicted by the statistical design, the limit of quantification (LOQ) obtained was reported to be 5.0 μg/L, and the calibration curve was linear over the concentration range of 5-100 μg/L. Finally, the method was successfully implemented for the determination of low levels of Cr(VI) ions in various real aquatic samples and the accuracies fell within the range of 83-102%, while the precision varied in the span of 1.7-5.2%. Copyright © 2018. Published by Elsevier B.V.

Temporal and spatial resolution required for imaging myocardial function

NASA Astrophysics Data System (ADS)

Eusemann, Christian D.; Robb, Richard A.

2004-05-01

4-D functional analysis of myocardial mechanics is an area of significant interest and research in cardiology and vascular/interventional radiology. Current multidimensional analysis is limited by insufficient temporal resolution of x-ray and magnetic resonance based techniques, but recent improvements in system design holds hope for faster and higher resolution scans to improve images of moving structures allowing more accurate functional studies, such as in the heart. This paper provides a basis for the requisite temporal and spatial resolution for useful imaging during individual segments of the cardiac cycle. Multiple sample rates during systole and diastole are compared to determine an adequate sample frequency to reduce regional myocardial tracking errors. Concurrently, out-of-plane resolution has to be sufficiently high to minimize partial volume effect. Temporal resolution and out-of-plane spatial resolution are related factors that must be considered together. The data used for this study is a DSR dynamic volume image dataset with high temporal and spatial resolution using implanted fiducial markers to track myocardial motion. The results of this study suggest a reduced exposure and scan time for x-ray and magnetic resonance imaging methods, since a lower sample rate during systole is sufficient, whereas the period of rapid filling during diastole requires higher sampling. This could potentially reduce the cost of these procedures and allow higher patient throughput.

Inkjet Printed Surface Enhanced Raman Spectroscopy Array on Cellulose Paper

PubMed Central

Yu, Wei W.; White, Ian M.

2011-01-01

A novel, ultra low-cost surface enhanced Raman spectroscopy (SERS) substrate has been developed by modifying the surface chemistry of cellulose paper and patterning nanoparticle arrays, all with a consumer inkjet printer. Micro/nanofabrication of SERS substrates for on-chip chemical and biomolecular analysis has been under intense investigation. However, the high cost of producing these substrates and the limited shelf life severely limit their use, especially for routine laboratory analysis and for point-of-sample analysis in the field. Paper-based microfluidic biosensing systems have shown great potential as low-cost disposable analysis tools. In this work, this concept is extended to SERS-based detection. Using an inexpensive consumer inkjet printer, cellulose paper substrates are modified to be hydrophobic in the sensing regions. Synthesized silver nanoparticles are printed onto this hydrophobic paper substrate with microscale precision to form sensing arrays. The hydrophobic surface prevents the aqueous sample from spreading throughout the paper and thus concentrates the analyte within the sensing region. A SERS fingerprint signal for Rhodamine 6G dye was observed for samples with as low as 10 femtomoles of analyte in a total sample volume of 1 μL. This extraordinarily simple technique can be used to construct SERS microarrays immediately before sample analysis, enabling ultra low-cost chemical and biomolecular detection in the lab as well as in the field at the point of sample collection. PMID:21058689

An on-line pre-concentration system for determination of cadmium in drinking water using FAAS.

PubMed

dos Santos, Walter N L; Costa, Jorge L O; Araujo, Rennan G O; de Jesus, Djane S; Costa, Antônio C S

2006-10-11

In the present paper, a minicolumn of polyurethane foam loaded with 4-(2-pyridylazo)-resorcinol (PAR) is proposed as pre-concentration system for cadmium determination in drinking water samples by flame atomic absorption spectrometry. The optimization step was performed using two-level full factorial design and Doehlert matrix, involving the variables: sampling flow rate, elution concentration, buffer concentration and pH. Using the established experimental conditions in the optimization step of: pH 8.2, sampling flow rate 8.5 mL min(-1), buffer concentration 0.05 mol L(-1) and elution concentration of 1.0 mol L(-1), this system allows the determination of cadmium with detection limit (LD) (3sigma/S) of 20.0 ng L(-1) and quantification limit (LQ) (10sigma/S) of 64 ng L(-1), precision expressed as relative standard deviation (R.S.D.) of 5.0 and 4.7% for cadmium concentration of 5.0 and 40.0 microg L(-1), respectively, and a pre-concentration factor of 158 for a sample volume of 20.0 mL. The accuracy was confirmed by cadmium determination in the standard reference material, NIST SRM 1643d trace elements in natural water. This procedure was applied for cadmium determination in drinking water samples collected from Salvador City, Bahia, Brazil. For five samples analyzed, the achieved concentrations varied from 0.31 to 0.86 microg L(-1).

Future use of tritium in mapping pre-bomb groundwater volumes.

PubMed

Eastoe, C J; Watts, C J; Ploughe, M; Wright, W E

2012-01-01

The tritium input to groundwater, represented as volume-weighted mean tritium concentrations in precipitation, has been close to constant in Tucson and Albuquerque since 1992, and the decrease in tritium concentrations at the tail end of the bomb tritium pulse has ceased. To determine the future usefulness of tritium measurements in southwestern North America, volume-weighted mean tritium levels in seasonal aggregate precipitation samples have been gathered from 26 sites. The averages range from 2 to 9 tritium units (TU). Tritium concentrations increase with site latitude, and possibly with distance from the coast and with site altitude, reflecting local ratios of combination of low-tritium moisture advected from the oceans with high-tritium moisture originating near the tropopause. Tritium used alone as a tool for mapping aquifer volumes containing only pre-bomb recharge to groundwater will become ambiguous when the tritium in precipitation at the end of the bomb tritium pulse decays to levels close to the analytical detection limit. At such a time, tritium in precipitation from the last one to two decades of the bomb pulse will become indistinguishable from pre-bomb recharge. The threshold of ambiguity has already arrived in coastal areas with a mean of 2 TU in precipitation and will follow in the next three decades throughout the study region. Where the mean tritium level is near 5 TU, the threshold will occur between 2025 and 2030, given a detection limit of 0.6 TU. Similar thresholds of ambiguity, with different local timing possible, apply globally. © 2011, The Author(s). Ground Water © 2011, National Ground Water Association.

Solid phase extraction of trace amounts of Ag, Cd, Cu, and Zn in environmental samples using magnetic nanoparticles coated by 3-(trimethoxysilyl)-1-propantiol and modified with 2-amino-5-mercapto-1,3,4-thiadiazole and their determination by ICP-OES.

PubMed

Mashhadizadeh, Mohammad Hossein; Karami, Zahra

2011-06-15

A fast, sensitive, and simple method using magnetic nanoparticles (MNPs) coated by 3-(trimethoxysilyl)-1-propantiol and modified with 2-amino-5-mercapto-1,3,4-thiadiazole, as an adsorbent has been successfully developed for extraction, preconcentration, and determination of trace amounts of Ag, Cd, Cu, and Zn from environmental samples. The prepared nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). These magnetic nanoparticles can be easily dispersed in aqueous samples and retrieved by the application of external magnetic field via a piece of permanent magnet. The main factors affecting the extraction efficiency such as pH value, sample volume, eluent concentration and volume, ultrasonication time, and coexisting ions have been investigated and established. Under the optimal conditions, high concentration factors (194, 190, 170, and 182) were achieved for Ag, Cd, Cu, and Zn with relative standard deviations of 5.31%, 4.03%, 3.62%, and 4.20%, respectively. The limits of detection for Ag, Cd, Cu, and Zn were as low as 0.12, 0.12, 0.13 and 0.11 ng mL(-1). The prepared sorbent was applied for preconcentration of trace amounts of Ag, Cd, Cu, and Zn in the various water samples with satisfactory results. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of gas chromatography-flame ionization detection system with a single column and liquid nitrogen-free for measuring atmospheric C2-C12 hydrocarbons.

PubMed

Liu, Chengtang; Mu, Yujing; Zhang, Chenglong; Zhang, Zhibo; Zhang, Yuanyuan; Liu, Junfeng; Sheng, Jiujiang; Quan, Jiannong

2016-01-04

A liquid nitrogen-free GC-FID system equipped with a single column has been developed for measuring atmospheric C2-C12 hydrocarbons. The system is consisted of a cooling unit, a sampling unit and a separation unit. The cooling unit is used to meet the temperature needs of the sampling unit and the separation unit. The sampling unit includes a dehydration tube and an enrichment tube. No breakthrough of the hydrocarbons was detected when the temperature of the enrichment tube was kept at -90 °C and sampling volume was 400 mL. The separation unit is a small round oven attached on the cooling column. A single capillary column (OV-1, 30 m × 0.32 mm I.D.) was used to separate the hydrocarbons. An optimal program temperature (-60 ∼ 170 °C) of the oven was achieved to efficiently separate C2-C12 hydrocarbons. There were good linear correlations (R(2)=0.993-0.999) between the signals of the hydrocarbons and the enrichment amount of hydrocarbons, and the relative standard deviation (RSD) was less than 5%, and the method detection limits (MDLs) for the hydrocarbons were in the range of 0.02-0.10 ppbv for sampling volume of 400 mL. Field measurements were also conducted and more than 50 hydrocarbons from C2 to C12 were detected in Beijing city. Copyright © 2015 Elsevier B.V. All rights reserved.

In-Syringe Micro Solid-Phase Extraction Method for the Separation and Preconcentration of Parabens in Environmental Water Samples.

PubMed

Mashile, Geaneth Pertunia; Mpupa, Anele; Nomngongo, Philiswa Nosizo

2018-06-14

In this study, a simple, rapid and effective in-syringe micro-solid phase extraction (MSPE) method was developed for the separation and preconcetration of parabens (methyl, ethyl, propyl and butyl paraben) in environmental water samples. The parabens were determined and quantified using high performance liquid chromatography and a photo diode array detector (HPLC-PDA). Chitosan-coated activated carbon (CAC) was used as the sorbent in the in-syringe MSPE device. A response surface methodology based on central composite design was used for the optimization of factors (eluent solvent type, eluent volume, number of elution cycles, sample volume, sample pH) affecting the extraction efficiency of the preconcentration procedure. The adsorbent used displayed excellent absorption performance and the adsorption capacity ranged from 227⁻256 mg g −1 . Under the optimal conditions the dynamic linear ranges for the parabens were between 0.04 and 380 µg L −1 . The limits of detection and quantification ranged from 6⁻15 ng L −1 and 20⁻50 ng L −1 , respectively. The intraday (repeatability) and interday (reproducibility) precisions expressed as relative standard deviations (%RSD) were below 5%. Furthermore, the in-syringe MSPE/HPLC procedure was validated using spiked wastewater and tap water samples and the recoveries ranged between from 96.7 to 107%. In conclusion, CAC based in-syringe MSPE method demonstrated great potential for preconcentration of parabens in complex environmental water.

Application of 1-(2-pyridylazo)-2-naphthol-modified nanoporous silica as a technique in simultaneous trace monitoring and removal of toxic heavy metals in food and water samples.

PubMed

Abolhasani, Jafar; Behbahani, Mohammad

2015-01-01

Solid-phase extraction is one the most useful and efficient techniques for sample preparation, purification, cleanup, preconcentration, and determination of heavy metals at trace levels. In this paper, functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was applied for trace determination of copper, lead, cadmium, and nickel in water and seafood samples. The experimental conditions such as pH, sample and eluent flow rate, type, concentration and volume of the eluent, breakthrough volume, and effect of coexisting ions were optimized for efficient solid-phase extraction of trace heavy metals in different water and seafood samples. The content of solutions containing the mentioned heavy metals was determined by flame atomic absorption spectrometry (FAAS), and the limits of detection were 0.3, 0.4, 0.6, and 0.9 ng mL(-1) for cadmium, copper, nickel, and lead, respectively. Recoveries and precisions were >98.0 and <4%, respectively. The adsorption capacity of the modified nanoporous silica was 178 mg g(-1) for cadmium, 110 mg g(-1) for copper, 98 mg g(-1) for nickel, and 210 mg g(-1) for lead, respectively. The functionalized MCM-48 nanoporous silica with 1-(2-pyridylazo)-2-naphthol was characterized by thermogravimetry analysis (TGA), differential thermal analysis (DTA), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), elemental analysis (CHN), and N2 adsorption surface area measurement.

Innovative flow controller for time integrated passive sampling using SUMMA canisters

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

Simon, P.; Farant, J.P.; Cole, H.

1996-12-31

To restrict the entry of gaseous contaminants inside evacuated vessels such as SUMMA canisters, mechanical flow controllers are used to collect integrated atmospheric samples. From the passive force generated by the pressure gradient, the motion of gas can be controlled to obtain a constant flow rate. Presently, devices based on the principle of critical orifices are used and they are all limited to an upper integrated sampling time. A novel flow controller which can be designed to achieve any desired sampling time when used on evacuated vessels was recently developed. It can extend the sampling time for hours, days, weeksmore » or even months for the benefits of environmental, engineering and toxicological professionals. The design of the controller is obtained from computer simulations done with an original set of equations derived from fluid mechanic and gas kinetic laws. To date, the experimental results have shown excellent agreement, with predictions obtained from the mathematical model. This new controller has already found numerous applications. Units able to deliver a constant sampling rate between vacuum and approximately -10 inches Hg during continuous long term duration have been used with SUMMA canisters of different volumes (500 ml, 1 litre and 61). Essentially, any combination of sampling time and sampler volume is possible. The innovative flow controller has contributed to an air quality assessment around a sanitary landfill (indoor/outdoor), and inside domestic wastewater and pulpmill sludge treatment facilities. It is presently being used as an alternative methodology for atmospheric sampling in the Russian orbital station Mir. This device affords true long term passive monitoring of selected gaseous air pollutants for environmental studies. 14 refs., 3 figs.« less

Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

PubMed

van Boxtel, Niels; Wolfs, Kris; Van Schepdael, Ann; Adams, Erwin

2015-12-18

The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10μL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous. Copyright © 2015 Elsevier B.V. All rights reserved.

Attomole-level protein fingerprinting based on intrinsic peptide fluorescence.

PubMed

Okerberg, E; Shear, J B

2001-04-01

Protein identification has relied heavily on proteolytic analysis, but current techniques are often slow and generally consume large quantities of valuable protein sample. We report the development of a rapid, ultralow volume protein analysis strategy based on tryptic digestion within the tip of a 1.5-microm capillary channel followed by separation of the proteolytic fragments using capillary electrophoresis (CE). Two-photon excitation is used to probe the intrinsic fluorescence of peptide fragments through "deep-UV" excitation of aromatic amino acid residues at the outlet of the CE channel. Detection limits using this technique are 0.7, 2.4, and 23 amol for the aromatic amino acids tryptophan, tyrosine, and phenylalanine, respectively. In these studies, we demonstrate the capacity to differentiate bovine and yeast cytochrome c variants using less than 15 amol of protein through tryptic fingerprinting. Moreover, the detection of a single amino acid substitution between bovine and canine cytochrome c illustrates the sensitivity of this approach to minor differences in protein sequence. The 2-pL sample volume required for this on-column tryptic digestion is, to our knowledge, the smallest yet reported for a proteolytic assay.

A quantitative approach to the topology of large-scale structure. [for galactic clustering computation

NASA Technical Reports Server (NTRS)

Gott, J. Richard, III; Weinberg, David H.; Melott, Adrian L.

1987-01-01

A quantitative measure of the topology of large-scale structure: the genus of density contours in a smoothed density distribution, is described and applied. For random phase (Gaussian) density fields, the mean genus per unit volume exhibits a universal dependence on threshold density, with a normalizing factor that can be calculated from the power spectrum. If large-scale structure formed from the gravitational instability of small-amplitude density fluctuations, the topology observed today on suitable scales should follow the topology in the initial conditions. The technique is illustrated by applying it to simulations of galaxy clustering in a flat universe dominated by cold dark matter. The technique is also applied to a volume-limited sample of the CfA redshift survey and to a model in which galaxies reside on the surfaces of polyhedral 'bubbles'. The topology of the evolved mass distribution and 'biased' galaxy distribution in the cold dark matter models closely matches the topology of the density fluctuations in the initial conditions. The topology of the observational sample is consistent with the random phase, cold dark matter model.

Solid phase microextraction of diclofenac using molecularly imprinted polymer sorbent in hollow fiber combined with fiber optic-linear array spectrophotometry.

PubMed

Pebdani, Arezou Amiri; Shabani, Ali Mohammad Haji; Dadfarnia, Shayessteh; Khodadoust, Saeid

2015-08-05

A simple solid phase microextraction method based on molecularly imprinted polymer sorbent in the hollow fiber (MIP-HF-SPME) combined with fiber optic-linear array spectrophotometer has been applied for the extraction and determination of diclofenac in environmental and biological samples. The effects of different parameters such as pH, times of extraction, type and volume of the organic solvent, stirring rate and donor phase volume on the extraction efficiency of the diclofenac were investigated and optimized. Under the optimal conditions, the calibration graph was linear (r(2)=0.998) in the range of 3.0-85.0 μg L(-1) with a detection limit of 0.7 μg L(-1) for preconcentration of 25.0 mL of the sample and the relative standard deviation (n=6) less than 5%. This method was applied successfully for the extraction and determination of diclofenac in different matrices (water, urine and plasma) and accuracy was examined through the recovery experiments. Copyright © 2015 Elsevier B.V. All rights reserved.

Design considerations of a hollow microneedle-optofluidic biosensing platform incorporating enzyme-linked assays

NASA Astrophysics Data System (ADS)

Ranamukhaarachchi, Sahan A.; Padeste, Celestino; Häfeli, Urs O.; Stoeber, Boris; Cadarso, Victor J.

2018-02-01

A hollow metallic microneedle is integrated with microfluidics and photonic components to form a microneedle-optofluidic biosensor suitable for therapeutic drug monitoring (TDM) in biological fluids, like interstitial fluid, that can be collected in a painless and minimally-invasive manner. The microneedle inner lumen surface is bio-functionalized to trap and bind target analytes on-site in a sample volume as small as 0.6 nl, and houses an enzyme-linked assay on its 0.06 mm2 wall. The optofluidic components are designed to rapidly quantify target analytes present in the sample and collected in the microneedle using a simple and sensitive absorbance scheme. This contribution describes how the biosensor components were optimized to detect in vitro streptavidin-horseradish peroxidase (Sav-HRP) as a model analyte over a large detection range (0-7.21 µM) and a very low limit of detection (60.2 nM). This biosensor utilizes the lowest analyte volume reported for TDM with microneedle technology, and presents significant avenues to improve current TDM methods for patients, by potentially eliminating blood draws for several drug candidates.

Transrectal real-time elastography of the prostate: Normal patterns

PubMed Central

Goddi, A.; Sacchi, A.; Magistretti, G.; Almolla, J.

2011-01-01

Introduction Given the growing importance in clinical practice of transrectal real-time sonoelastography of the prostate, it is important to define normal patterns correlated to volume growth and reconsider the technical problems. Materials and methods We selected a sample of 100 men aged 30 to 87 with prostate volumes ranging from 20 to 100 cc. Strain images were obtained using an end-fire convex probe. The elasticity patterns of the various anatomical zones of the prostate were compared with the volume. Results The peripheral zone showed intermediate elasticity in 100% of cases regardless of the volume. We found some rare small areas of more limited elasticity in 23% of cases, among patients over 40. The posterior side of the central zone exhibited intermediate elasticity, and relative inelasticity was observed on the lateral side and at the base in 79% of cases. The entire central zone appeared compliant in 15% of cases and inelastic in 6%. The transition zone findings were stratified according to gland volume. When the volume was less than 45 cc, the transition zone was elastic in 67% of cases, inhomogeneously inelastic in 22%, and uniformly inelastic in 11%. In glands larger than 45 cc, the appearance was mainly elastic in 31% of cases, inhomogeneously inelastic in 57%, and uniformly inelastic in 12%. Conclusions Real-time elastography can distinguish the elastic properties of the prostate and define the normal patterns associated with increases in gland volume. PMID:23396618

Iron oxide functionalized graphene oxide as an efficient sorbent for dispersive micro-solid phase extraction of sulfadiazine followed by spectrophotometric and mode-mismatched thermal lens spectrometric determination.

PubMed

Kazemi, Elahe; Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Abbasi, Amir; Rashidian Vaziri, Mohammad Reza; Behjat, Abbas

2016-01-15

A simple and rapid dispersive micro-solid phase extraction (DMSPE) combined with mode-mismatched thermal lens spectrometry as well as fiber optic linear array spectrophotometry was developed for the separation, extraction and determination of sulfadiazine. Graphene oxide was synthesized using the modified Hummers method and functionalized with iron oxide nanoparticles by means of a simple one step chemical coprecipitation method. The synthesized iron oxide functionalized graphene oxide was utilized as an efficient sorbent in DMSPE of sulfadiazine. The retained analyte was eluted by using 180µL of a 6:4 mixture of methanol/acetic acid solution and was spectrophotometrically determined based on the formation of an azo dye through coupling with thenoyltrifluoroacetone. Under the optimized conditions, with the application of spectrophotometry technique and with a sample volume of 100mL, the method exhibited a linear dynamic range of 3-80µg L(-1) with a detection limit of 0.82µg L(-1), an enrichment factor of 200 as well as the relative standard deviations of 2.6% and 4.3% (n=6) at 150µg L(-1) level of sulfadiazine for intra- and inter-day analyses, respectively. Whereas, through the application of the thermal lens spectrometry and a sample volume of 10mL, the method exhibited a linear dynamic range of 1-800µg L(-1) with a detection limit of 0.34µg L(-1) and the relative standard deviations of 3.1% and 5.4% (n=6) at 150µg L(-1) level of sulfadiazine for intra- and inter-day analyses, respectively. The method was successfully applied to the determination of sulfadiazine in milk, honey and water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

A rapid MCM-41 dispersive micro-solid phase extraction coupled with LC/MS/MS for quantification of ketoconazole and voriconazole in biological fluids.

PubMed

Yahaya, Noorfatimah; Sanagi, Mohd Marsin; Abd Aziz, Noorizan; Wan Ibrahim, Wan Aini; Nur, Hadi; Loh, Saw Hong; Kamaruzaman, Sazlinda

2017-02-01

A rapid dispersive micro-solid phase extraction (D-μ-SPE) combined with LC/MS/MS method was developed and validated for the determination of ketoconazole and voriconazole in human urine and plasma samples. Synthesized mesoporous silica MCM-41 was used as sorbent in d-μ-SPE of the azole compounds from biological fluids. Important D-μ-SPE parameters, namely type desorption solvent, extraction time, sample pH, salt addition, desorption time, amount of sorbent and sample volume were optimized. Liquid chromatographic separations were carried out on a Zorbax SB-C 18 column (2.1 × 100 mm, 3.5 μm), using a mobile phase of acetonitrile-0.05% formic acid in 5 mm ammonium acetate buffer (70:30, v/v). A triple quadrupole mass spectrometer with positive ionization mode was used for the determination of target analytes. Under the optimized conditions, the calibration curves showed good linearity in the range of 0.1-10,000 μg/L with satisfactory limit of detection (≤0.06 μg/L) and limit of quantitation (≤0.3 μg/L). The proposed method also showed acceptable intra- and inter-day precisions for ketoconazole and voriconazole from urine and human plasma with RSD ≤16.5% and good relative recoveries in the range 84.3-114.8%. The MCM-41-D-μ-SPE method proved to be rapid and simple and requires a small volume of organic solvent (200 μL); thus it is advantageous for routine drug analysis. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

DOE PAGES

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.; ...

2016-02-25

The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors.more » Here in this paper, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. In conclusion, the finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less

Effect of Ni content on the morphological evolution of Ni-YSZ solid oxide fuel cell electrodes

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

Chen-Wiegart, Yu-chen Karen; Kennouche, David; Scott Cronin, J.

The coarsening of Ni in Ni–yttria-stabilized zirconia (YSZ) anodes is a potential cause of long term solid oxide fuel cells (SOFC) performance degradation. The specifics of the Ni-YSZ structure—including Ni/YSZ ratio, porosity, and particle size distributions—are normally selected to minimize anode polarization resistance, but they also impact long-term stability. A better understanding of how these factors influence long-term stability is important for designing more durable anodes. The effect of structural details, e.g., Ni-YSZ ratio, on Ni coarsening has not been quantified. Furthermore, prior measurements have been done by comparing evolved structures with control samples, such that sample-to-sample variations introduce errors.more » Here in this paper, we report a four dimensional (three spatial dimensions and time) study of Ni coarsening in Ni-YSZ anode functional layers with different Ni/YSZ ratios, using synchrotron x-ray nano-tomography. The continuous structural evolution was observed and analyzed at sub-100 nm resolution. It is shown quantitatively that increasing the Ni/YSZ ratio increases the Ni coarsening rate. This is due to both increased pore volume and a decrease in the YSZ volume fraction, such that there is more free volume and a less obtrusive YSZ network, both of which allow greater Ni coarsening. The results are shown to be in good agreement with a power-law coarsening model. In conclusion, the finding is critical for informing the design of SOFC electrode microstructures that limit coarsening and performance degradation.« less

36 CFR 228.59 - Negotiated or noncompetitive sales.

Code of Federal Regulations, 2010 CFR

2010-07-01

... noncompetitive sales. (a) Volume limitations. When it is determined by the authorized officer to be in the public... yards in volume (or weight equivalent) may be sold in any one sale at not less than the appraised value... the noncompetitive sale of mineral materials in excess of the volume limitations in paragraphs (a), (b...