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Sample records for rapid direct determination

  1. A direct and rapid method to determine cyanide in urine by capillary electrophoresis.

    PubMed

    Zhang, Qiyang; Maddukuri, Naveen; Gong, Maojun

    2015-10-02

    Cyanides are poisonous chemicals that widely exist in nature and industrial processes as well as accidental fires. Rapid and accurate determination of cyanide exposure would facilitate forensic investigation, medical diagnosis, and chronic cyanide monitoring. Here, a rapid and direct method was developed for the determination of cyanide ions in urinary samples. This technique was based on an integrated capillary electrophoresis system coupled with laser-induced fluorescence (LIF) detection. Cyanide ions were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) and a primary amine (glycine) for LIF detection. Three separate reagents, NDA, glycine, and cyanide sample, were mixed online, which secured uniform conditions between samples for cyanide derivatization and reduced the risk of precipitation formation of mixtures. Conditions were optimized; the derivatization was completed in 2-4min, and the separation was observed in 25s. The limit of detection (LOD) was 4.0nM at 3-fold signal-to-noise ratio for standard cyanide in buffer. The cyanide levels in urine samples from smokers and non-smokers were determined by using the method of standard addition, which demonstrated significant difference of cyanide levels in urinary samples from the two groups of people. The developed method was rapid and accurate, and is anticipated to be applicable to cyanide detection in waste water with appropriate modification.

  2. A Direct and Rapid Method to Determine Cyanide in Urine by Capillary Electrophoresis

    PubMed Central

    Zhang, Qiyang; Maddukuri, Naveen; Gong, Maojun

    2015-01-01

    Cyanides are poisonous chemicals that widely exist in nature and industrial processes as well as accidental fires. Rapid and accurate determination of cyanide exposure would facilitate forensic investigation, medical diagnosis, and chronic cyanide monitoring. Here, a rapid and direct method was developed for the determination of cyanide ions in urinary samples. This technique was based on an integrated capillary electrophoresis system coupled with laser-induced fluorescence (LIF) detection. Cyanide ions were derivatized with naphthalene-2,3-dicarboxaldehyde (NDA) and a primary amine (glycine) for LIF detection. Three separate reagents, NDA, glycine, and cyanide sample, were mixed online, which secured uniform conditions between samples for cyanide derivatization and reduced the risk of precipitation formation of mixtures. Conditions were optimized; the derivatization was completed in 2-4 minutes, and the separation was observed in 25 s. The limit of detection (LOD) was 4.0 nM at 3-fold signal-to-noise ratio for standard cyanide in buffer. The cyanide levels in urine samples from smokers and non-smokers were determined by using the method of standard addition, which demonstrated significant difference of cyanide levels in urinary samples from the two groups of people. The developed method was rapid and accurate, and is anticipated to be applicable to cyanide detection in waste water with appropriate modification. PMID:26342870

  3. Rapid determination of drugs and semivolatile organics by direct thermal desorption ion trap mass spectrometry

    SciTech Connect

    Wise, M.B.; Ilgner, R.H.; Buchanan, M.V.; Guerin, M.R.

    1991-01-01

    Direct thermal desorption of analytes into an ion trap mass spectrometer (ITMS) is being investigated as a technique for the rapid screening of a wide variety of samples for target semivolatile organic compounds. This includes the direct detection of drugs in physiological fluids, semivolatile organic pollutants in water and waste samples, and air pollutants collected on sorbent cartridges. In order to minimize the analysis time, chromatographic separation is not performed on the sample prior to introduction into the ITMS. Instead, selective chemical ionization and tandem mass spectrometry (MS/MS) are used achieve the specificity required for the target analytes. Detection limits are typically 10--50 ppb using a 1 uL aliquot of a liquid sample without preconcentration. Sample turn-around time is 2 to 5 minutes and 3 to 5 target analytes can be quantitatively determined simultaneously. 6 figs.

  4. Rapid determination of nicotine in urine by direct thermal desorption ion trap mass spectrometry

    SciTech Connect

    Wise, M.B.; Ilgner, R.H.; Guerin, M.R.

    1990-01-01

    The measurement of nicotine and cotinine in physiological fluids (urine, blood serum, and saliva) is widely used as a means of assessing human exposure to environmental tobacco smoke (ETS). Although numerous analytical methods exist for these measurements, they generally involve extensive sample preparation which increases cost and decreases sample throughput. We report the use of thermal desorption directly into an ion trap mass spectrometer (ITMS) for the rapid determination of nicotine and cotinine in urine. A 1{mu}L aliquot of urine is injected into a specially designed inlet and flash vaporized directly into an ITMS through an open-split capillary restrictor interface. Isobutane chemical ionization is used to generate (M+H){sup +} ions of the analytes and collision induced dissociation is used to generate characteristic fragment ions which are used to confirm their identity. Quantification is achieved by integrating the ion current for the characteristic ions and comparing with an external working curve. Detection limits are approximately 50 pg per analyte and the sample turnaround time is approximately 3 minutes without the need for extensive sample preparation. 12 refs., 5 figs.

  5. A fluorescence-based method for rapid and direct determination of polybrominated diphenyl ethers in water

    SciTech Connect

    Shan, Huimei; Liu, Chongxuan; Wang, Zheming; Ma, Teng; Shang, Jianying; Pan, Duoqiang

    2015-01-01

    A new method was developed for rapid and direct measurement of polybrominated diphenyl ethers (PBDEs) in aqueous samples using fluorescence spectroscopy. The fluorescence spectra of tri- to deca-BDE (BDE 28, 47, 99, 153, 190, and 209) commonly found in environment were measured at variable emission and excitation wavelengths. The results revealed that the PBDEs have distinct fluorescence spectral profiles and peak positions that can be exploited to identify these species and determine their concentrations in aqueous solutions. The detection limits as determined in deionized water spiked with PBDEs are 1.71-5.82 ng/L for BDE 28, BDE 47, BDE 190, and BDE 209 and 45.55–69.95 ng/L for BDE 99 and BDE 153. The effects of environmental variables including pH, humic substance, and groundwater chemical composition on PBDEs measurements were also investigated. These environmental variables affected fluorescence intensity, but their effect can be corrected through linear additivity and separation of spectral signal contribution. Compared with conventional GC-based analytical methods, the fluorescence spectroscopy method is more efficient as it only uses a small amount of samples (2-4 mL), avoids lengthy complicated concentration and extraction steps, and has a low detection limit of a few ng/L.

  6. A fluorescence-based method for rapid and direct determination of polybrominated diphenyl ethers in water

    DOE PAGES

    Shan, Huimei; Liu, Chongxuan; Wang, Zheming; ...

    2015-01-01

    A new method was developed for rapid and direct measurement of polybrominated diphenyl ethers (PBDEs) in aqueous samples using fluorescence spectroscopy. The fluorescence spectra of tri- to deca-BDE (BDE 28, 47, 99, 153, 190, and 209) commonly found in environment were measured at variable emission and excitation wavelengths. The results revealed that the PBDEs have distinct fluorescence spectral profiles and peak positions that can be exploited to identify these species and determine their concentrations in aqueous solutions. The detection limits as determined in deionized water spiked with PBDEs are 1.71-5.82 ng/L for BDE 28, BDE 47, BDE 190, and BDEmore » 209 and 45.55–69.95 ng/L for BDE 99 and BDE 153. The effects of environmental variables including pH, humic substance, and groundwater chemical composition on PBDEs measurements were also investigated. These environmental variables affected fluorescence intensity, but their effect can be corrected through linear additivity and separation of spectral signal contribution. Compared with conventional GC-based analytical methods, the fluorescence spectroscopy method is more efficient as it only uses a small amount of samples (2-4 mL), avoids lengthy complicated concentration and extraction steps, and has a low detection limit of a few ng/L.« less

  7. A Fluorescence-Based Method for Rapid and Direct Determination of Polybrominated Diphenyl Ethers in Water

    PubMed Central

    Shan, Huimei; Ma, Teng; Shang, Jianying; Pan, Duoqiang

    2015-01-01

    A new method was developed for rapid and direct measurement of polybrominated diphenyl ethers (PBDEs) in aqueous samples using fluorescence spectroscopy. The fluorescence spectra of tri- to deca-BDE (BDE 28, 47, 99, 153, 190, and 209) commonly found in environment were measured at variable emission and excitation wavelengths. The results revealed that the PBDEs have distinct fluorescence spectral profiles and peak positions that can be exploited to identify these species and determine their concentrations in aqueous solutions. The detection limits as determined in deionized water spiked with PBDEs are 1.71–5.82 ng/L for BDE 28, BDE 47, BDE 190, and BDE 209 and 45.55–69.95 ng/L for BDE 99 and BDE 153. The effects of environmental variables including pH, humic substance, and groundwater chemical composition on PBDEs measurements were also investigated. These environmental variables affected fluorescence intensity, but their effect can be corrected through linear additivity and separation of spectral signal contribution. Compared with conventional GC-based analytical methods, the fluorescence spectroscopy method is more efficient as it only uses a small amount of samples (2–4 mL), avoids lengthy complicated concentration and extraction steps, and has a low detection limit of a few ng/L. PMID:25705548

  8. Rapid, accurate, and direct determination of total lycopene content in tomato paste

    NASA Astrophysics Data System (ADS)

    Bicanic, D.; Anese, M.; Luterotti, S.; Dadarlat, D.; Gibkes, J.; Lubbers, M.

    2003-01-01

    Lycopene that imparts red color to the tomato fruit is the most potent antioxidant among carotenes, an important nutrient and also used as a color ingredient in many food formulations. Since cooked and processed foods derived from tomatoes were shown to provide optimal lycopene boost, products such as paste, puree, juice, etc. are nowadays gaining popularity as dietary sources. The analysis of lycopene in tomato paste (partially dehydrated product prepared by vacuum concentrating tomato juice) is carried out using either high pressure liquid chromatography (HPLC), spectrophotometry, or by evaluating the color. The instability of lycopene during processes of extraction, etc., handling, and disposal of organic solvents makes the preparation of a sample for the analysis a delicate task. Despite a recognized need for accurate and rapid assessment of lycopene in tomato products no such method is available at present. The study described here focuses on a direct determination of a total lycopene content in different tomato pastes by means of the laser optothermal window (LOW) method at 502 nm. The concentration of lycopene in tomato paste ranged between 25 and 150 mg per 100 g product; the results are in excellent agreement with those obtained by spectrophotometry. The time needed to complete LOW analysis is very short, so that decomposition of pigment and the formation of artifacts are minimized. Preliminary results indicate a good degree of reproducibility making the LOW method suitable for routine assays of lycopene content in tomato paste.

  9. Rapid and direct determination of fructose in food: a new osmium-polymer mediated biosensor.

    PubMed

    Antiochia, Riccarda; Vinci, Giuliana; Gorton, Lo

    2013-10-15

    This paper describes the development and performance of a new rapid amperometric biosensor for fructose monitoring in food analysis. The biosensor is based on the activity of fructose dehydrogenase (FDH) immobilised into a carbon nanotube paste electrode according to two different procedures. The direct wiring of the FDH in a highly original osmium-polymer hydrogel was found to offer a better enzyme entrapment compared to the immobilisation of the enzyme in an albumin hydrogel. The optimised biosensor required only 5U of FDH and kept the 80% of its initial sensitivity after 4months. During this time, the biosensor showed a detection limit for fructose of 1μM, a large linear range between 0.1 and 5mM, a high sensitivity (1.95μAcm(-2)mM), good reproducibility (RSD=2.1%) and a fast response time (4s). Finally, the biosensor was applied for specific determination of fructose in honey, fruit juices, soft and energy drinks. The results indicated a very good agreement with those obtained with a commercial reference kit. No significant interference was observed with the proposed biosensor.

  10. Rapid determination of molar mass in modified Archibald experiments using direct fitting of the Lamm equation.

    PubMed

    Schuck, P; Millar, D B

    1998-05-15

    A new method is described that allows measurement of the molar mass of the solute within 15 to 30 min after start of a conventional long-column sedimentation equilibrium experiment. A series of scans of the concentration distribution in close vicinity of the meniscus, taken in rapid succession after the start of the centrifuge run, is analyzed by direct fitting using the Lamm equation and the Svedberg equation. In case of a single solute, this analysis of the initial depletion at the meniscus reveals its buoyant molar mass and sedimentation coefficient with an accuracy of approximately 10% and provides gross information about sample heterogeneity. This method can be used to study macromolecules that do not possess the prolonged stability needed in conventional sedimentation equilibrium experiments and it can increase the efficiency of sedimentation equilibrium experiments of previously uncharacterized samples.

  11. Rapid, direct determination of organic sulfur in coal using electron-probe microanalysis

    SciTech Connect

    Raymond, R. Jr.

    1981-01-01

    Electron probe microanalysis (EPM) for organic sulfur content can be performed easily on -20 to -100 mesh coal samples. Samples need only be mounted in epoxy and polished as coal samples are commonly prepared for petrographic examination. 15 areas within non-contiguous vitrinite grains are analyzed with the EPM. Without the need to produce a photomosaic, the organic sulfur content of vitrinite, and therefore of a coal, may be determined in less than 10 minutes. To test the EPM method coals were analyzed for which the ASTM organic sulfur values were corrected for unextracted iron. Such a correction would take into account the effect of any pyrite that remained unextracted following the ASTM Standard Method D2492-68. As shown from the data the EPM organic sulfur contents are very close to those of the corrected ASTM values. Using the EPM method, the potential exists to achieve very rapid, multiple organic sulfur analyses, which in turn will allow for rapid, detailed measurements of variations in organic sulfur content occurring across coal seams.

  12. Rapid determination of cholesterol in milk and milk products by direct saponification and capillary gas chromatography.

    PubMed

    Fletouris, D J; Botsoglou, N A; Psomas, I E; Mantis, A I

    1998-11-01

    A simple method is described for the determination of cholesterol in milk and milk products. Samples (0.2 g) are saponified in capped tubes with 0.5 M methanolic KOH solution by heating for 15 min at 80 degrees C. Water is added to the mixtures, and the unsaponifiable fractions are extracted with hexane to be further analyzed by capillary gas chromatography. Because of the rapid sample preparation and gas chromatographic procedures, a single sample can be analyzed in 30 min. Overall recovery was 98.6%, and the linearity was excellent for the fortification range examined. Precision data that were based on the variation within and between days suggested an overall relative standard deviation value of 1.4%. The method has been successfully applied to quantitate cholesterol in a variety of milk products.

  13. Rapid analytical procedure for neomycin determination in ointments by CE with direct UV detection.

    PubMed

    Huidobro, A L; García, A; Barbas, C

    2009-07-12

    The purpose of this study was the development of an analytical methodology for the determination of neomycin in a complex pharmaceutical preparation. The simplified methodology consisted of a primary liquid-liquid extraction, employing a mixture of chloroform and water (1.25:1, v/v) and subsequent analysis by CE applying a capillary zone electrophoresis method with a 30 cm (effective length), 50 microm (internal diameter) polyacrylamide-coated silica capillary. The background electrolyte consisted of 35 mM phosphate and 15 mM acetate buffer set at pH 4.7, under normal polarity mode and direct UV detection at 200 nm. The separation of the target analyte from the complex matrix was accomplished in less than 3 min. The analytical method was successfully validated in order to verify its proper selectivity, linearity, accuracy and precision for the goal intended and its further implementation for the quantification of the active compound in the pharmaceutical speciality for quality control.

  14. Development of simple algorithm for direct and rapid determination of cotton maturity from FTIR spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Fourier transform infrared (FTIR) spectra of seed and lint cottons were collected to explore the potential for the discrimination of immature cottons from mature ones and also for the determination of actual cotton maturity. Spectral features of immature and mature cottons revealed large differences...

  15. Rapid determination of 1-deoxynojirimycin in Morus alba L. leaves by direct analysis in real time (DART) mass spectrometry.

    PubMed

    Xu, Bin; Zhang, Dong-Yang; Liu, Ze-Yu; Zhang, Ying; Liu, Li; Li, Long; Liu, Charles C; Wu, Guo-Hua

    2015-10-10

    A new method based on a Direct Analysis in Real Time (DART) ionization source coupled with triple quadrupole tandem mass spectrometry has been developed for rapid qualitative and quantitative analyses of 1-deoxynojirimycin (DNJ) in mulberry leaves. Two ions produced from DNJ, [M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162), are observed using DART-MS in the positive ion mode. The peak areas of the two selected ions monitoring (SIM) signals of ([M+H](+) (m/z 164) and [M-2H+H](+) (m/z 162)) are integrated to determine the peak area for quantitative analyses. A reasonable linear regression equation is obtained in the range of 1.01 to 40.50 μg/mL, with a linear coefficient (R(2)) of 0.996. The limits of detection (LOD) and quantification (LOQ) of the method are 0.25 and 0.80 μg/mL, respectively. The range of recovery is shown to be 87.73-95.61%. The results derived from the developed DART-MS method are in good agreement with those from the conventional HPLC-FLD method. By contrast, DART-MS in SIM mode is a simple, rapid and high-throughput approach for the determination of the DNJ content in mulberry leaves. The present method is advantageous for the rapid screening of mulberry leaves containing high DNJ contents.

  16. Codeine-binding RNA aptamers and rapid determination of their binding constants using a direct coupling surface plasmon resonance assay.

    PubMed

    Win, Maung Nyan; Klein, Joshua S; Smolke, Christina D

    2006-01-01

    RNA aptamers that bind the opium alkaloid codeine were generated using an iterative in vitro selection process. The binding properties of these aptamers, including equilibrium and kinetic rate constants, were determined through a rapid, high-throughput approach using surface plasmon resonance (SPR) analysis to measure real-time binding. The approach involves direct coupling of the target small molecule onto a sensor chip without utilization of a carrier protein. Two highest binding aptamer sequences, FC5 and FC45 with K(d) values of 2.50 and 4.00 microM, respectively, were extensively studied. Corresponding mini-aptamers for FC5 and FC45 were subsequently identified through the described direct coupling Biacore assays. These assays were also employed to confirm the proposed secondary structures of the mini-aptamers. Both aptamers exhibit high specificity to codeine over morphine, which differs from codeine by a methyl group. Finally, the direct coupling method was demonstrated to eliminate potential non-specific interactions that may be associated with indirect coupling methods in which protein linkers are commonly employed. Therefore, in addition to presenting the first RNA aptamers to a subclass of benzylisoquinoline alkaloid molecules, this work highlights a method for characterizing small molecule aptamers that is more robust, precise, rapid and high-throughput than other commonly employed techniques.

  17. Codeine-binding RNA aptamers and rapid determination of their binding constants using a direct coupling surface plasmon resonance assay

    PubMed Central

    Win, Maung Nyan; Klein, Joshua S.; Smolke, Christina D.

    2006-01-01

    RNA aptamers that bind the opium alkaloid codeine were generated using an iterative in vitro selection process. The binding properties of these aptamers, including equilibrium and kinetic rate constants, were determined through a rapid, high-throughput approach using surface plasmon resonance (SPR) analysis to measure real-time binding. The approach involves direct coupling of the target small molecule onto a sensor chip without utilization of a carrier protein. Two highest binding aptamer sequences, FC5 and FC45 with Kd values of 2.50 and 4.00 μM, respectively, were extensively studied. Corresponding mini-aptamers for FC5 and FC45 were subsequently identified through the described direct coupling Biacore assays. These assays were also employed to confirm the proposed secondary structures of the mini-aptamers. Both aptamers exhibit high specificity to codeine over morphine, which differs from codeine by a methyl group. Finally, the direct coupling method was demonstrated to eliminate potential non-specific interactions that may be associated with indirect coupling methods in which protein linkers are commonly employed. Therefore, in addition to presenting the first RNA aptamers to a subclass of benzylisoquinoline alkaloid molecules, this work highlights a method for characterizing small molecule aptamers that is more robust, precise, rapid and high-throughput than other commonly employed techniques. PMID:17038331

  18. Rapid and direct electrochemical determination of Ni(II) in industrial discharge water.

    PubMed

    Ferancová, Adriana; Hattuniemi, Maarit K; Sesay, Adama M; Räty, Jarkko P; Virtanen, Vesa T

    2016-04-05

    Industrial water contains a number of contaminants, such as organic pollutants and heavy metals, which can significantly affect the quality of soil, ground and environmental waters. We have successfully optimized and tested an electrochemical method and sensor modified with dimethylglyoxime for monitoring of nickel(II). The detection limit was 0.03mg/L and determination limit was 0.09mg/L. Linear concentration range was observed from 0.06 to 0.5mg/L Ni(II) and it is suitable for the analysis of environmental waters. The effect of all parameters important for on-site measurements (such as interferences, presence of dissolved oxygen, temperature) was investigated and considered in the analysis of mine discharge water. Water samples were analyzed without any pretreatment or filtration. A low level of error (5.6%) was observed for analysis demonstrating the usability of the optimized sensor and method for on-site measurements.

  19. Evaluation of X-ray fluorescence spectroscopy as a method for the rapid and direct determination of sodium in cheese.

    PubMed

    Stankey, J A; Akbulut, C; Romero, J E; Govindasamy-Lucey, S

    2015-08-01

    Cheese manufacturers indirectly determine Na in cheese by analysis of Cl using the Volhard method, assuming that all Cl came from NaCl. This method overestimates the actual Na content in cheeses when Na replacers (e.g., KCl) are used. A direct and rapid method for Na detection is needed. X-ray fluorescence spectroscopy (XRF), a mineral analysis technique used in the mining industry, was investigated as an alternative method of Na detection in cheese. An XRF method for the detection of Na in cheese was developed and compared with inductively coupled plasma optical emission spectroscopy (ICP-OES; the reference method for Na in cheese) and Cl analyzer. Sodium quantification was performed by multi-point calibration with cheese standards spiked with NaCl ranging from 0 to 4% Na (wt/wt). The Na concentration of each of the cheese standards (discs: 30mm×7mm) was quantified by the 3 methods. A single laboratory method validation was performed; linearity, precision, limit of detection, and limit of quantification were determined. An additional calibration graph was created using cheese standards made from natural or process cheeses manufactured with different ratios of Na:K. Both Na and K calibration curves were linear for the cheese standards. Sodium was quantified in a variety of commercial cheese samples. The Na data obtained by XRF were in agreement with those from ICP-OES and Cl analyzer for most commercial natural cheeses. The XRF method did not accurately determine Na concentration for several process cheese samples, compared with ICP-OES, likely due to the use of unknown types of Na-based emulsifying salts (ES). When a calibration curve was created for process cheese with the specific types of ES used for this cheese, Na content was successfully predicted in the samples. For natural cheeses, the limit of detection and limit of quantification for Na that can be determined with an acceptable level of repeatability, precision, and trueness was 82 and 246mg/100g of

  20. Diffusion-facilitated direct determination of intrinsic parameters for rapid photoinduced bimolecular electron-transfer reactions in nonpolar solvents.

    PubMed

    Scully, Andrew D; Ohtaka, Hiroyasu; Takezaki, Makoto; Tominaga, Toshihiro

    2015-03-26

    Bimolecular fluorescence-quenching reactions involving electron-transfer between electronically excited 5,10,15,20-tetraphenyl-21H,23H-porphine (TPP*) and 1,4-benzoquinone (BQ) or 1,4-naphthoquinone (NQ) were investigated using a set of alkane solvents that enabled the rapid reaction kinetics to be probed over a wide viscosity range, while minimizing changes in other relevant solvent parameters. Relative diffusion coefficients and reaction distances were recovered directly from analysis of fluorescence decay curves measured on a nanosecond time scale. The electron transfer from TPP* to BQ requires reactant contact, consistent with tightly associated exciplex formation in these nonpolar solvents. In contrast, electron transfer from TPP* to NQ displays a clear distance dependence, indicative of reaction via a much looser noncontact exciplex. This difference is attributed to the greater steric hindrance associated with contact between the TPP*/NQ pair. The diffusion coefficients recovered from fluorescence decay curve analysis are markedly smaller than the corresponding measured bulk relative diffusion coefficients. Classical hydrodynamics theory was found to provide a satisfactory resolution of this apparent discrepancy. The calculated hydrodynamic radii of TPP and NQ correlate very well with the van der Waals values. The hydrodynamic radius obtained for BQ is a factor of 6 times smaller than the van der Waals value, indicative of a possible tight cofacial geometry in the (TPP(+)/BQ(-))* exciplex. The present work demonstrates the utility of a straightforward methodology, based on widely available instrumentation and data analysis, that is broadly applicable for direct determination of kinetic parameter values for a wide variety of rapid bimolecular fluorescence quenching reactions in fluid solution.

  1. Rapid and direct determination of glyphosate, glufosinate, and aminophosphonic acid by online preconcentration CE with contactless conductivity detection.

    PubMed

    See, Hong Heng; Hauser, Peter C; Ibrahim, Wan Aini Wan; Sanagi, Mohd Marsin

    2010-01-01

    Rapid and direct online preconcentration followed by CE with capacitively coupled contactless conductivity detection (CE-C(4)D) is evaluated as a new approach for the determination of glyphosate, glufosinate (GLUF), and aminophosphonic acid (AMPA) in drinking water. Two online preconcentration techniques, namely large volume sample stacking without polarity switching and field-enhanced sample injection, coupled with CE-C(4)D were successfully developed and optimized. Under optimized conditions, LODs in the range of 0.01-0.1 microM (1.7-11.1 microg/L) and sensitivity enhancements of 48- to 53-fold were achieved with the large volume sample stacking-CE-C(4)D method. By performing the field-enhanced sample injection-CE-C(4)D procedure, excellent LODs down to 0.0005-0.02 microM (0.1-2.2 microg/L) as well as sensitivity enhancements of up to 245- to 1002-fold were obtained. Both techniques showed satisfactory reproducibility with RSDs of peak height of better than 10%. The newly established approaches were successfully applied to the analysis of glyphosate, glufosinate, and aminophosphonic acid in spiked tap drinking water.

  2. Rapid and direct estimation of active biomass on granular activated carbon through adenosine tri-phosphate (ATP) determination.

    PubMed

    Velten, Silvana; Hammes, Frederik; Boller, Markus; Egli, Thomas

    2007-05-01

    Granular activated carbon (GAC) filtration is used during drinking water treatment for the removal of micropollutants such as taste and odour compounds, halogenated hydrocarbons, pesticides and pharmaceuticals. In addition, the active microbial biomass established on GAC is responsible for the removal of biodegradable dissolved organic carbon compounds present in water or formed during oxidation (e.g., ozonation and chlorination) processes. In order to conduct correct kinetic evaluations of DOC removal during drinking water treatment, and to assess the state and performance of full-scale GAC filter installations, an accurate and sensitive method for active biomass determination on GAC is required. We have developed a straight-forward method based on direct measurement of the total adenosine tri-phosphate (ATP) content of a GAC sample and other support media. In this method, we have combined flow-cytometric absolute cell counting and ATP analysis to derive case-specific ATP/cell conversion values. In this study, we present the detailed standardisation of the ATP method. An uncertainty assessment has shown that heterogeneous colonisation of the GAC particles makes the largest contribution to the combined standard uncertainty of the method. The method was applied for the investigation of biofilm formation during the start-up period of a GAC pilot-scale plant treating Lake Zurich water. A rapid increase in the biomass of up to 1.1 x 10(10)cells/g GAC dry weight (DW) within the first 33 days was observed, followed by a slight decrease to an average steady-state concentration of 7.9 x 10(9)cells/g GAC DW. It was shown that the method can be used to determine the biomass attached to the GAC for both stable and developing biofilms.

  3. Rapid determination of benzodiazepines, zolpidem and their metabolites in urine using direct injection liquid chromatography-tandem mass spectrometry.

    PubMed

    Jeong, Yu-Dong; Kim, Min Kyung; Suh, Sung Ill; In, Moon Kyo; Kim, Jin Young; Paeng, Ki-Jung

    2015-12-01

    Benzodiazepines and zolpidem are generally prescribed as sedative, hypnotics, anxiolytics or anticonvulsants. These drugs, however, are frequently misused in drug-facilitated crime. Therefore, a rapid and simple liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for identification and quantification of benzodiazepines, zolpidem and their metabolites in urine using deuterium labeled internal standards (IS). Urine samples (120 μL) mixed with 80 μL of the IS solution were centrifuged. An aliquot (5 μL) of the sample solution was directly injected into the LC-MS/MS system for analysis. The mobile phases consisted of water and acetonitrile containing 2mM ammonium trifluoroacetate and 0.2% acetic acid. The analytical column was a Zorbax SB-C18 (100 mm × 2.1 mm i.d., 3.5 μm, Agilent). The separation and detection of 18 analytes were achieved within 10 min. Calibration curves were linear over the concentration ranges of 0.5-20 ng/mL (zolpidem), 1.0-40 ng/mL (flurazepam and temazepam), 2.5-100 ng/mL (7-aminoclonazepam, 1-hydroxymidazolam, midazolam, flunitrazepam and alprazolam), 5.0-200 ng/mL (zolpidem phenyl-4-carboxylic acid, α-hydroxyalprazolam, oxazepam, nordiazepam, triazolam, diazepam and α-hydroxytriazolam), 10-400 ng/mL (lorazepam and desalkylflurazepam) and 10-100 ng/mL (N-desmethylflunitrazepam) with the coefficients of determination (r(2)) above 0.9971. The dilution integrity of the analytes was examined for supplementation of short linear range. Dilution precision and accuracy were tested using two, four and ten-folds dilutions and they ranged from 3.7 to 14.4% and -12.8 to 12.5%, respectively. The process efficiency for this method was 63.0-104.6%. Intra- and inter-day precisions were less than 11.8% and 9.1%, while intra- and inter-day accuracies were less than -10.0 to 8.2%, respectively. The lower limits of quantification were lower than 10 ng/mL for each analyte. The applicability of the developed method was successfully

  4. Rapid determination of piracetam in human plasma and cerebrospinal fluid by micellar electrokinetic chromatography with sample direct injection.

    PubMed

    Yeh, Hsin-Hua; Yang, Yuan-Han; Ko, Ju-Yun; Chen, Su-Hwei

    2006-07-07

    A simple micellar electrokinetic chromatography (MEKC) method with UV detection at 200 nm for analysis of piracetam in plasma and in cerebrospinal fluid (CSF) by direct injection without any sample pretreatment is described. The separation of piracetam from biological matrix was performed at 25 degrees C using a background electrolyte consisting of Tris buffer with sodium dodecyl sulfate (SDS) as the electrolyte solution. Several parameters affecting the separation of the drug from biological matrix were studied, including the pH and concentrations of the Tris buffer and SDS. Under optimal MEKC condition, good separation with high efficiency and short analyses time is achieved. Using imidazole as an internal standard (IS), the linear ranges of the method for the determination of piracetam in plasma and in CSF were all between 5 and 500 microg/mL; the detection limit of the drug in plasma and in CSF (signal-to-noise ratio=3; injection 0.5 psi, 5s) was 1.0 microg/mL. The applicability of the proposed method for determination of piracetam in plasma and CSF collected after intravenous administration of 3g piracetam every 6h and oral administration 1.2g every 6h in encephalopathy patients with aphasia was demonstrated.

  5. A simple and rapid method for direct determination of Al(III) based on the enhanced resonance Rayleigh scattering of hemin-functionalized graphene-Al(III) system

    NASA Astrophysics Data System (ADS)

    Ling, Yu; Chen, Ling Xiao; Dong, Jiang Xue; Li, Nian Bing; Luo, Hong Qun

    2016-03-01

    A novel method for direct determination of Al(III) by using hemin-functionalized graphene (H-GO) has been established based on the enhancement of resonance Rayleigh scattering (RRS) intensity. The characteristics of RRS spectra, the optimum reaction conditions, and the reaction mechanism have been investigated. In this experiment, the Al(III) would exist in sol-gel Al(OH)3 species under the condition of pH 5.9 in aqueous solutions. When H-GO existed in the solution, the sol-gel Al(OH)3 would react with H-GO and result in enhancement of RRS intensity, owing to the enhanced hydrophobicity of H-GO surface. Therefore, a simple and rapid sensor for Al(III) was developed. The increased intensity of RRS is directly proportional to the concentration of Al(III) in the range of 10 nM-6 μM, along with a detection limit of 0.87 nM. Moreover, the sensor has been applied to determination of Al(III) concentration in real water and aspirin tablet samples with satisfactory results. Therefore, the proposed method is promising as an effective means for selective and sensitive determination of Al(III).

  6. Staph ID/R: a rapid method for determining staphylococcus species identity and detecting the mecA gene directly from positive blood culture.

    PubMed

    Pasko, Chris; Hicke, Brian; Dunn, John; Jaeckel, Heidi; Nieuwlandt, Dan; Weed, Diane; Woodruff, Evelyn; Zheng, Xiaotian; Jenison, Robert

    2012-03-01

    Rapid diagnosis of staphylococcal bacteremia directs appropriate antimicrobial therapy, leading to improved patient outcome. We describe herein a rapid test (<75 min) that can identify the major pathogenic strains of Staphylococcus to the species level as well as the presence or absence of the methicillin resistance determinant gene, mecA. The test, Staph ID/R, combines a rapid isothermal nucleic acid amplification method, helicase-dependent amplification (HDA), with a chip-based array that produces unambiguous visible results. The analytic sensitivity was 1 CFU per reaction for the mecA gene and was 1 to 250 CFU per reaction depending on the staphylococcal species present in the positive blood culture. Staph ID/R has excellent specificity as well, with no cross-reactivity observed. We validated the performance of Staph ID/R by testing 104 frozen clinical positive blood cultures and comparing the results with rpoB gene or 16S rRNA gene sequencing for species identity determinations and mecA gene PCR to confirm mecA gene results. Staph ID/R agreed with mecA gene PCR for all samples and agreed with rpoB/16S rRNA gene sequencing in all cases except for one sample that contained a mixture of two staphylococcal species, one of which Staph ID/R correctly identified, for an overall agreement of 99.0% (P < 0.01). Staph ID/R could potentially be used to positively affect patient management for Staphylococcus-mediated bacteremia.

  7. Staph ID/R: a Rapid Method for Determining Staphylococcus Species Identity and Detecting the mecA Gene Directly from Positive Blood Culture

    PubMed Central

    Pasko, Chris; Dunn, John; Jaeckel, Heidi; Nieuwlandt, Dan; Weed, Diane; Woodruff, Evelyn; Zheng, Xiaotian

    2012-01-01

    Rapid diagnosis of staphylococcal bacteremia directs appropriate antimicrobial therapy, leading to improved patient outcome. We describe herein a rapid test (<75 min) that can identify the major pathogenic strains of Staphylococcus to the species level as well as the presence or absence of the methicillin resistance determinant gene, mecA. The test, Staph ID/R, combines a rapid isothermal nucleic acid amplification method, helicase-dependent amplification (HDA), with a chip-based array that produces unambiguous visible results. The analytic sensitivity was 1 CFU per reaction for the mecA gene and was 1 to 250 CFU per reaction depending on the staphylococcal species present in the positive blood culture. Staph ID/R has excellent specificity as well, with no cross-reactivity observed. We validated the performance of Staph ID/R by testing 104 frozen clinical positive blood cultures and comparing the results with rpoB gene or 16S rRNA gene sequencing for species identity determinations and mecA gene PCR to confirm mecA gene results. Staph ID/R agreed with mecA gene PCR for all samples and agreed with rpoB/16S rRNA gene sequencing in all cases except for one sample that contained a mixture of two staphylococcal species, one of which Staph ID/R correctly identified, for an overall agreement of 99.0% (P < 0.01). Staph ID/R could potentially be used to positively affect patient management for Staphylococcus-mediated bacteremia. PMID:22170912

  8. Development and evaluation of a dot blot assay for rapid determination of invasion-associated gene ibeA directly in fresh bacteria cultures of E. coli.

    PubMed

    Niu, Chunling; Wang, Shaohui; Lu, Chengping

    2012-11-01

    The ibeA gene, one of the important invasion-associated genes in neonatal meningitis Escherichia coli (NMEC), has been recently detected in avian pathogenic E. coli (APEC). Thus, it is necessary to close monitor the possible contamination of the poultry farms and its products to people. Here, a dot blot method for detecting the ibeA gene in E. coli was developed and validated. For the present study, probe sequence was designed and optimized for the specificity of dot blot. A 342-bp conserved fragment of ibeA gene was selected and labeled with digoxigenin (DIG)-dUTP according to the manufacturer's guidelines, which indicated that this probe hybridizes with ibeA. In our established method, the bacteria culture samples were directly spotted on the membrane, following simple lyses on the membrane. Hence, the extraction of genomic DNA is not required, which reduces the workload and shortens the time. Furthermore, this assay was very sensitive, which could detect as few as 2.5 × 10(3) CFU bacteria. The diagnostic reliability of this dot blot was evaluated on 467 APEC bacteria samples by using PCR analysis. Both methods showed that the result was in complete concordance. The dot blot assay was proved to be a simple, rapid, highly accurate, and cost-effective method to identify invasion-associated genes ibeA, which could be applied for initial screening of a large number of clinical samples or direct detection of bacteria culture.

  9. Ultra trace determination of 31 pesticides in water samples by direct injection-rapid resolution liquid chromatography-electrospray tandem mass spectrometry.

    PubMed

    Díaz, Laura; Llorca-Pórcel, Julio; Valor, Ignacio

    2008-08-22

    A liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method for the detection of pesticides in tap and treated wastewater was developed and validated according to the ISO/IEC 17025:1999. Key features of this method include direct injection of 100 microL of sample, an 11 min separation by means of a rapid resolution liquid chromatography system with a 4.6 mm x 50 mm, 1.8 microm particle size reverse phase column and detection by electrospray ionization (ESI) MS-MS. The limits of detection were below 15 ng L(-1) and correlation coefficients for the calibration curves in the range of 30-2000 ng L(-1) were higher than 0.99. Precision was always below 20% and accuracy was confirmed by external evaluation. The main advantages of this method are direct injection of sample without preparative procedures and low limits of detection that fulfill the requirements established by the current European regulations governing pesticide detection.

  10. Rapid direct PCR for ABO blood typing.

    PubMed

    Lee, Hwan Young; Park, Myung Jin; Kim, Na Young; Yang, Woo Ick; Shin, Kyoung-Jin

    2011-01-01

    Many different molecular typing methods have been reported to complement routine serological ABO blood typing in forensics. However, these ABO genotyping methods are often time-consuming and call for an initial DNA isolation step that requires the use of expensive kits or reagents. We report here a rapid direct ABO genotyping method that eliminates the need for DNA extraction from fresh blood, hair, and body fluid stains before PCR. Using a fast PCR instrument and an optimized polymerase, the genotyping method-which employs a multiplex allele-specific primer set for the simultaneous detection of three single-nucleotide polymorphism (SNP) sites (nucleotides 261, 526, and 803)-identifies A, B, O01/O02, O03, and cis-AB01 alleles in around 70 min from sample collection to electropherogram. Not only will this ABO genotyping method be efficiently used in forensic practice for rapid screening of samples before full-blown multilocus short tandem repeat profiling, but it will also demonstrate an example of rapid direct genotyping of SNPs that offers the advantages of time- and cost-efficiency, convenience, and reduced contamination during DNA analysis.

  11. Determination of amphetamine and methadone in human urine by microextraction by packed sorbent coupled directly to mass spectrometry: an alternative for rapid clinical and forensic analysis.

    PubMed

    Vlčková, Hana; El-Beqqali, Aziza; Nováková, Lucie; Solich, Petr; Abdel-Rehim, Mohamed

    2014-11-01

    Speed and low cost, together with regulatory approval, are the most important requirements of clinical assays. Therefore, a fast and automated on-line sample preparation method is essential for the routine analysis of biological samples. Microextraction by packed sorbent is an option for optimal sample preparation due to its easy automation, minimal requirements for the sample and elution solvent volumes, elimination of evaporation and reconstitution steps, and ability to integrate sample preparation and injection into one step. The use of effective sample preparation steps circumvents the need for chromatographic separation and therefore allows more rapid and less expensive sample analysis in clinical and forensic practice. Two biologically active compounds, amphetamine and methadone, were chosen as representative drugs of abuse for the application of microextraction by packed sorbent coupled directly to mass spectrometry. The developed method was validated, with the results confirming the suitability of the combination of these techniques for the analysis of biological samples. The approach was confirmed to be appropriate for use in clinical and forensic practice with regard to cost and time requirements for analysis.

  12. Direct and rapid determination of ultratrace heavy metals in solid plant materials by ET-AAS ultrasonic-assisted slurry sampling.

    PubMed

    Sánchez-Moreno, Raúl A; Gismera, M Jesús; Sevilla, M Teresa; Procopio, Jesús R

    2010-01-01

    Plants can be used as bioindicators in the study of contamination processes by heavy metals. Most of the analytical methodologies used for determination of metals in plants are based on atomic techniques with previous wet digestion of the solid samples. Methodologies that allow direct metal measurements in solid samples are very attractive alternatives. To develop a new procedure for direct analysis of copper, nickel, cadmium and lead at very low concentration levels in leaves based on electrothermal atomic absorption spectroscopy (ET-AAS) with introduction of samples as a slurry. In order to obtain accurate and precise results even at very low concentrations, the different parameters that influence the sample slurry preparation such as acid percentage, presence of stabilising agents and ultrasonic probe operation were studied. Instrumental parameters such as chemical modifier and temperature and times for drying, pyrolysis and atomisation steps that influence ET-AAS measurement were optimised. Optimal slurry conditions for copper and nickel determination were 0.5% Tween 85 with 5% nitric acid. For lead and cadmium analysis the best results were obtained in 5% nitric acid without stabilising agents. The achieved detection limits were 0.023 mg/kg for copper, 0.018 mg/kg for nickel, 0.0002 mg/kg for cadmium and 0.009 mg/kg for lead. For validation purposes, the method was applied to metal analysis in a pine needles reference material. According to our knowledge, the detection limits obtained are the best reported in the literature. The methodology was successfully used in metal determinations in actual leaf samples.

  13. The rapid and direct determination of ATPase activity by ion exchange chromatography and the application to the activity of heat shock protein-90.

    PubMed

    Bartolini, Manuela; Wainer, Irving W; Bertucci, Carlo; Andrisano, Vincenza

    2013-01-25

    Adenosine nucleotides are involved as substrates or co-factors in several biochemical reactions, catalyzed by enzymes, which modulate energy production, signal transduction and cell proliferation. We here report the development and optimization of an ion exchange liquid chromatography (LC) method for the determination of ATP, ADP and AMP. This method is specifically aimed at the determination of the ATP-ase activity of human heat shock protein 90 (Hsp90), a molecular chaperone that has emerged as target enzyme in cancer therapy. Separation of the three nucleotides was achieved in a 15-min run by using a disk shaped monolithic ethylene diamine stationary phase of small dimensions (2mm×6mm i.d.), under a three-solvent gradient elution mode and UV detection at 256nm. The described direct LC method resulted highly specific as a consequence of the baseline separation of the three adenosine nucleotides and could be applied to the determination of the enzymatic activity of ADP/ATP generating or consuming enzymes (such as kinases). Furthermore, comparison of the LOD and LOQ values of the LC method with those obtained with the malachite green assay, which is one of the most used indirect screening methodologies for ATP-ase activity, showed that the LC method has a similar range of application without presenting the drawbacks related to contamination by inorganic phosphate ions and glycerol, which are present in Hsp90 commercial samples.

  14. Sorptive thin film microextraction followed by direct solid state spectrofluorimetry: A simple, rapid and sensitive method for determination of carvedilol in human plasma.

    PubMed

    Karimi, Shima; Talebpour, Zahra; Adib, Noushin

    2016-06-14

    A poly acrylate-ethylene glycol (PA-EG) thin film is introduced for the first time as a novel polar sorbent for sorptive extraction method coupled directly to solid-state spectrofluorimetry without the necessity of a desorption step. The structure, polarity, fluorescence property and extraction performance of the developed thin film were investigated systematically. Carvedilol was used as the model analyte to evaluate the proposed method. The entire procedure involved one-step extraction of carvedilol from plasma using PA-EG thin film sorptive phase without protein precipitation. Extraction variables were studied in order to establish the best experimental conditions. Optimum extraction conditions were the followings: stirring speed of 1000 rpm, pH of 6.8, extraction temperature of 60 °C, and extraction time of 60 min. Under optimal conditions, extraction of carvedilol was carried out in spiked human plasma; and the linear range of calibration curve was 15-300 ng mL(-1) with regression coefficient of 0.998. Limit of detection (LOD) for the method was 4.5 ng mL(-1). The intra- and inter-day accuracy and precision of the proposed method were evaluated in plasma sample spiked with three concentration levels of carvedilol; yielding a recovery of 91-112% and relative standard deviation of less than 8%, respectively. The established procedure was successfully applied for quantification of carvedilol in plasma sample of a volunteer patient. The developed PA-EG thin film sorptive phase followed by solid-state spectrofluorimetric method provides a simple, rapid and sensitive approach for the analysis of carvedilol in human plasma.

  15. RAPID DETERMINATION OF RADIOSTRONTIUM IN SEAWATER SAMPLES

    SciTech Connect

    Maxwell, S.

    2013-01-16

    A new method for the determination of radiostrontium in seawater samples has been developed at the Savannah River National Laboratory (SRNL) that allows rapid preconcentration and separation of strontium and yttrium isotopes in seawater samples for measurement. The new SRNL method employs a novel and effective pre-concentration step that utilizes a blend of calcium phosphate with iron hydroxide to collect both strontium and yttrium rapidly from the seawater matrix with enhanced chemical yields. The pre-concentration steps, in combination with rapid Sr Resin and DGA Resin cartridge separation options using vacuum box technology, allow seawater samples up to 10 liters to be analyzed. The total {sup 89}Sr + {sup 90}Sr activity may be determined by gas flow proportional counting and recounted after ingrowth of {sup 90}Y to differentiate {sup 89}Sr from {sup 90}Sr. Gas flow proportional counting provides a lower method detection limit than liquid scintillation or Cerenkov counting and allows simultaneous counting of samples. Simultaneous counting allows for longer count times and lower method detection limits without handling very large aliquots of seawater. Seawater samples up to 6 liters may be analyzed using Sr Resin for {sup 89}Sr and {sup 90}Sr with a Minimum Detectable Activity (MDA) of 1-10 mBq/L, depending on count times. Seawater samples up to 10 liters may be analyzed for {sup 90}Sr using a DGA Resin method via collection and purification of {sup 90}Y only. If {sup 89}Sr and other fission products are present, then {sup 91}Y (beta energy 1.55 MeV, 58.5 day half-life) is also likely to be present. {sup 91}Y interferes with attempts to collect {sup 90}Y directly from the seawater sample without initial purification of Sr isotopes first and {sup 90}Y ingrowth. The DGA Resin option can be used to determine {sup 90}Sr, and if {sup 91}Y is also present, an ingrowth option with using DGA Resin again to collect {sup 90}Y can be performed. An MDA for {sup 90}Sr of <1 m

  16. Rapid Decimation for Direct Volume Rendering

    NASA Technical Reports Server (NTRS)

    Gibbs, Jonathan; VanGelder, Allen; Verma, Vivek; Wilhelms, Jane

    1997-01-01

    An approach for eliminating unnecessary portions of a volume when producing a direct volume rendering is described. This reduction in volume size sacrifices some image quality in the interest of rendering speed. Since volume visualization is often used as an exploratory visualization technique, it is important to reduce rendering times, so the user can effectively explore the volume. The methods presented can speed up rendering by factors of 2 to 3 with minor image degradation. A family of decimation algorithms to reduce the number of primitives in the volume without altering the volume's grid in any way is introduced. This allows the decimation to be computed rapidly, making it easier to change decimation levels on the fly. Further, because very little extra space is required, this method is suitable for the very large volumes that are becoming common. The method is also grid-independent, so it is suitable for multiple overlapping curvilinear and unstructured, as well as regular, grids. The decimation process can proceed automatically, or can be guided by the user so that important regions of the volume are decimated less than unimportant regions. A formal error measure is described based on a three-dimensional analog of the Radon transform. Decimation methods are evaluated based on this metric and on direct comparison with reference images.

  17. Rapid direct antibiotic susceptibility testing in endophthalmitis.

    PubMed

    Miño de Kaspar, Herminia; Neubauer, Aljoscha S; Molnar, Alexander; Hoepfner, Angela S; Ta, Christopher N; Grasbon, Thomas; Engelbert, Michael; Thiel, Martin; Klauss, Volker; Kampik, Anselm

    2002-04-01

    To compare a new rapid antibiotic susceptibility test (RAST) to the conventional method in patients with endophthalmitis. Prospective nonrandomized comparative trial. Intraocular aspirates from 24 consecutive patients with endophthalmitis were tested. Approximately 0.25 ml of vitreous or anterior chamber aspirate was obtained and tested for antibiotic sensitivity using the Kirby-Bauer agar disk diffusion method. Using this conventional testing method, the aspirates were cultured for bacterial growth before antibiotic susceptibility testing (AST). In contrast, for direct RAST, the aspirates were inoculated directly onto agar plates with antibiotic disks without first culturing for bacterial growth. Of the 24 endophthalmitis aspirates studied, 4 (17%) could not be tested by direct RAST because either more than one bacterial species was present or no bacteria were cultured. The remaining 20 cases provided 467 antibiotic-microorganism combinations. The two methods yielded identical susceptibility results in 409 (88%) of the 467 tests. In 42 tests (9%), a minor discrepancy occurred between the conventional method and RAST, in which one resulted in intermediate susceptibility, whereas the other was either resistant or sensitive. Significant discrepancy, defined as a bacterial sample reported as sensitive in one method yet resistant in the other, occurred with 16 samples (3%). Results of the RAST were available within 6 to 10 hours compared with more than 24 hours for the conventional method. Of clinical significance, the results of the RAST revealed that in 11 cases of epidemic Stenotrophomonas maltophilia endophthalmitis, the bacteria were resistant to the antibiotics prescribed, and change of antibiotic therapy was made on the basis of the RAST results. RAST provided accurate antibiotic susceptibility results in a much shorter time than did the conventional method. We suggest that conventional AST be performed for confirmation of the RAST results, but initial

  18. Rapid determination of melamine and cyanuric acid in milk powder using direct analysis in real time-time-of-flight mass spectrometry.

    PubMed

    Vaclavik, Lukas; Rosmus, Jan; Popping, Bert; Hajslova, Jana

    2010-06-18

    The use of fast semi-automated method employing direct analysis in real time (DART) ion source coupled to time-of-flight mass spectrometry (TOFMS) for analysis of melamine (MEL) and cyanuric acid (CYA) in milk powder and milk based products has been demonstrated in this study. Simple sample extraction procedure employing methanol-5% aqueous formic acid mixture, which enabled disruption of melamine-cyanurate complex, was followed by direct, high-throughput (30s per run) examination of sample extracts spread on a glass rod by mass spectrometry under ambient conditions, without any prior chromatographic separation. After optimization of instrument parameter settings, limits of detection (LODs) 170 and 450microgkg(-1) were achieved for MEL and CYA, respectively. In the final phase of study, the possibility of minimizing spectral interference, thus improving method performance characteristics through the use of ultrahigh resolving power offered by Orbitrap based mass analyzer is demonstrated.

  19. Online coupling of in-tube solid-phase microextraction with direct analysis in real time mass spectrometry for rapid determination of triazine herbicides in water using carbon-nanotubes-incorporated polymer monolith.

    PubMed

    Wang, Xin; Li, Xianjiang; Li, Ze; Zhang, Yiding; Bai, Yu; Liu, Huwei

    2014-05-20

    Online coupling of in-tube solid phase microextraction (IT-SPME) with direct analysis in real time mass spectrometry (DART-MS) was realized for the first time and applied in the analysis of triazine herbicides in lake water and orange juice. We incorporated single-wall carbon nanotubes (SWNTs) into a polymer monolith containing methacrylic acid (MAA) and ethylene dimethacrylate (EDMA) to form a novel poly(methacrylic acid-co-ethylene dimethacrylate-co-single wall carbon nanotubes) (poly(MAA-EDMA-SWNT)) monolith, which was then used in IT-SPME for enrichment of six triazine herbicides from water samples. With the online combination of IT-SPME with DART-MS, the analytes desorbed from the monolith were directly ionized by DART and transferred into MS for detection, thus rapid determination was achieved. Compared with regular DART-MS method, this online IT-SPME-DART-MS method was more sensitive and reproducible, because of the IT-SPME procedures and the isotope-labeled internal standard used in the experiment. Six triazine herbicides were determined simultaneously using this method with good linearity (R(2) > 0.998). The limit of quantification (signal-to-noise ratio of S/N = 10) of the six herbicides were only 0.06-0.46 ng/mL. The proposed method has been applied to determine triazine herbicides in lake water and orange juice, showing satisfactory recovery (85%-106%) and reproducibility (relative standard deviation of RSD = 3.1%-10.9%).

  20. Rapid determination of actinides in seawater samples

    DOE PAGES

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.; ...

    2014-03-09

    A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti+3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used tomore » separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1–2 weeks and provide chemical yields of ~30–60 %. This new sample preparation method can be performed in 4–8 h with tracer yields of ~85–95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort.« less

  1. Rapid determination of actinides in seawater samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.; Utsey, Robin C.; McAlister, Daniel R.

    2014-03-09

    A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti+3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1–2 weeks and provide chemical yields of ~30–60 %. This new sample preparation method can be performed in 4–8 h with tracer yields of ~85–95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort.

  2. Rapid determination of actinides in asphalt samples

    DOE PAGES

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.

    2014-01-12

    A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organicsmore » present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well.« less

  3. Rapid determination of actinides in asphalt samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.

    2014-01-12

    A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organics present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well.

  4. Novel and rapid method for determination of organophosphorus pesticide residues in edible fungus using direct gas purge microsyringe extraction coupled on-line with gas chromatography-mass spectrometry.

    PubMed

    Nan, Jingxi; Wang, Juan; Piao, Xiangfan; Yang, Cui; Wu, Xue; Quinto, Maurizio; Li, Donghao

    2015-09-01

    In this work a new analytical method for a rapid and simultaneous determination of 28 organophosphorus pesticides (OPPs) residues in edible fungus using gas purge microsyringe extraction (GP-MSE), coupled with on-line gas chromatography-mass spectrometry (GP-MSE-GC-MS) has been developed and optimized. GP-MSE, a novel gas flow liquid-phase microextraction technique, has been then fruitfully used as innovative and one-step extraction procedure, allowing a direct injection into the gas chromatograph coupled with a mass spectrometry detector (GC-MS) system without any further cleaning step. Once optimized, the GP-MSE-GC-MS analysis procedure showed reproducibility values, resolutions, linear responses, detection and quantification limits that allowed to consider this method suitable for the analysis of the 28 OPPs in real samples. Furthermore, OPP recoveries and the relative standard deviations (RSDs) ranged from 85.26% to 100.21%, and from 1.6% to 6.9%, respectively. This procedure was then used for the analysis of real samples and the obtained results were compared with those of ultrasonic extraction-solid phase extraction. Among the 28 OPPs, 14 of them were found in Lentinus edodes and Enoki mushrooms fungus samples, with a total concentrations of 112.7 and 210.7 μg kg(-1), respectively. This work demonstrated then that GP-MSE-GC-MS provided a highly efficient, solvent-saving, accurate and sensitive quantitative analysis method for a rapid determination of OPPs in edible fungus. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Method for rapidly determining a pulp kappa number using spectrophotometry

    SciTech Connect

    Chai, Xin-Sheng; Zhu, Jun Yong

    2002-01-01

    A system and method for rapidly determining the pulp kappa number through direct measurement of the potassium permanganate concentration in a pulp-permanganate solution using spectrophotometry. Specifically, the present invention uses strong acidification to carry out the pulp-permanganate oxidation reaction in the pulp-permanganate solution to prevent the precipitation of manganese dioxide (MnO.sub.2). Consequently, spectral interference from the precipitated MnO.sub.2 is eliminated and the oxidation reaction becomes dominant. The spectral intensity of the oxidation reaction is then analyzed to determine the pulp kappa number.

  6. Evaluation of a Direct, Rapid Immunohistochemical Test for Rabies Diagnosis

    PubMed Central

    Lembo, Tiziana; Velasco-Villa, Andrés; Cleaveland, Sarah; Ernest, Eblate; Rupprecht, Charles E.

    2006-01-01

    A direct rapid immunohistochemical test (dRIT) was evaluated under field and laboratory conditions to detect rabies virus antigen in frozen and glycerol-preserved field brain samples from northwestern Tanzania. Compared to the direct fluorescent antibody test, the traditional standard in rabies diagnosis, the dRIT was 100% sensitive and specific. PMID:16494761

  7. Direct electrochemical determination of Candida albicans activity.

    PubMed

    Hassan, Rabeay Y A; Bilitewski, Ursula

    2013-11-15

    Despite advances made in the field, rapid detection methods for the human pathogen Candida albicans are still missing. In this regard, bio-electrochemical systems including electrochemical sensors and biosensors satisfy the increasing demand for rapid, reliable, and direct microbial analyses. In this study, the bioelectrochemical characteristics of C. albicans were investigated for use in an analytical system that determines the viability of the organisms. The electrochemical responses of viable and non-viable cells of C. albicans and Saccharomyces cerevisiae were monitored. Cyclic voltammograms (CV) showed an irreversible oxidation peak at about 750 mV that accounts for viable cells. The peak current increased at viable cell numbers ranging from 3 × 10(5) to 1.6 × 10(7)cells/ml, indicating that the amount of viable cells can be accurately quantified. To elucidate the underlying electron transfer processes, the influence of electron transfer chain (ETC) - inhibitors on the electrochemical behavior of the two organisms were investigated. Inhibition of the function of classical respiratory chain (CRC) led to a decrease in the electrochemical response, whereas the oxidation current increased when the alternative oxidase (AOX) pathway was blocked by salicylhydroxamic acid (SHA). Blocking the AOX pathway improved the electrochemical performance, suggesting an involvement in the CRC, with cytochrome c oxidase (COX) as a relevant protein complex. Mutants, in which components of COX were deleted, showed a lower electro-activity than the wild-type strain. Particularly, deletion of subunit COX5a almost completely abolished the electrochemical signal. We believe that this work can be utilized for the development of early detection assays and opens the door for new technological developments in the field of C. albicans.

  8. Rapid determination of 226Ra in environmental samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.

    2012-02-04

    A new rapid method for the determination of {sup 228}Ra in natural water samples has been developed at the SRNL/EBL (Savannah River National Lab/ Environmental Bioassay Laboratory) that can be used for emergency response or routine samples. While gamma spectrometry can be employed with sufficient detection limits to determine {sup 228}Ra in solid samples (via {sup 228}Ac) , radiochemical methods that employ gas flow proportional counting techniques typically provide lower MDA (Minimal Detectable Activity) levels for the determination of {sup 228}Ra in water samples. Most radiochemical methods for {sup 228}Ra collect and purify {sup 228}Ra and allow for {sup 228}Ac daughter ingrowth for ~36 hours. In this new SRNL/EBL approach, {sup 228}Ac is collected and purified from the water sample without waiting to eliminate this delay. The sample preparation requires only about 4 hours so that {sup 228}Ra assay results on water samples can be achieved in < 6 hours. The method uses a rapid calcium carbonate precipitation enhanced with a small amount of phosphate added to enhance chemical yields (typically >90%), followed by rapid cation exchange removal of calcium. Lead, bismuth, uranium, thorium and protactinium isotopes are also removed by the cation exchange separation. {sup 228}Ac is eluted from the cation resin directly onto a DGA Resin cartridge attached to the bottom of the cation column to purify {sup 228}Ac. DGA Resin also removes lead and bismuth isotopes, along with Sr isotopes and {sup 90}Y. La is used to determine {sup 228}Ac chemical yield via ICP-MS, but {sup 133}Ba can also be used instead if ICP-MS assay is not available. Unlike some older methods, no lead or strontium holdback carriers or continual readjustment of sample pH is required.

  9. Rapid analytical determination of glutaraldehyde concentrations

    NASA Technical Reports Server (NTRS)

    Frigerio, N. A.; Shaw, M. H.

    1971-01-01

    Technique utilizes the iodimetric procedure which adds unknown excess of bisulfite to glutaraldehyde /GA/ then titrates unreacted bisulfite with standard iodine isotope to determine GA concentrations. Technique may interest microscopists, food researchers, biochemical or medical laboratories, and drug manufacturers.

  10. Determining Directional Dependency in Causal Associations

    ERIC Educational Resources Information Center

    Pornprasertmanit, Sunthud; Little, Todd D.

    2012-01-01

    Directional dependency is a method to determine the likely causal direction of effect between two variables. This article aims to critique and improve upon the use of directional dependency as a technique to infer causal associations. We comment on several issues raised by von Eye and DeShon (2012), including: encouraging the use of the signs of…

  11. Rapid-Chill Cryogenic Coaxial Direct-Acting Solenoid Valve

    NASA Technical Reports Server (NTRS)

    Richard, James; Castor, Jim; Sheller, Richard

    2006-01-01

    A commercially available cryogenic direct- acting solenoid valve has been modified to incorporate a rapid-chill feature. The net effect of the modifications is to divert some of the cryogenic liquid to the task of cooling the remainder of the cryogenic liquid that flows to the outlet. Among the modifications are the addition of several holes and a gallery into a valve-seat retainer and the addition of a narrow vent passage from the gallery to the atmosphere.

  12. Rapid Modeling and Analysis Tools: Evolution, Status, Needs and Directions

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.; Stone, Thomas J.; Ransom, Jonathan B. (Technical Monitor)

    2002-01-01

    Advanced aerospace systems are becoming increasingly more complex, and customers are demanding lower cost, higher performance, and high reliability. Increased demands are placed on the design engineers to collaborate and integrate design needs and objectives early in the design process to minimize risks that may occur later in the design development stage. High performance systems require better understanding of system sensitivities much earlier in the design process to meet these goals. The knowledge, skills, intuition, and experience of an individual design engineer will need to be extended significantly for the next generation of aerospace system designs. Then a collaborative effort involving the designer, rapid and reliable analysis tools and virtual experts will result in advanced aerospace systems that are safe, reliable, and efficient. This paper discusses the evolution, status, needs and directions for rapid modeling and analysis tools for structural analysis. First, the evolution of computerized design and analysis tools is briefly described. Next, the status of representative design and analysis tools is described along with a brief statement on their functionality. Then technology advancements to achieve rapid modeling and analysis are identified. Finally, potential future directions including possible prototype configurations are proposed.

  13. Determining wave direction using curvature parameters.

    PubMed

    de Queiroz, Eduardo Vitarelli; de Carvalho, João Luiz Baptista

    2016-01-01

    The curvature of the sea wave was tested as a parameter for estimating wave direction in the search for better results in estimates of wave direction in shallow waters, where waves of different sizes, frequencies and directions intersect and it is difficult to characterize. We used numerical simulations of the sea surface to determine wave direction calculated from the curvature of the waves. Using 1000 numerical simulations, the statistical variability of the wave direction was determined. The results showed good performance by the curvature parameter for estimating wave direction. Accuracy in the estimates was improved by including wave slope parameters in addition to curvature. The results indicate that the curvature is a promising technique to estimate wave directions.•In this study, the accuracy and precision of curvature parameters to measure wave direction are analyzed using a model simulation that generates 1000 wave records with directional resolution.•The model allows the simultaneous simulation of time-series wave properties such as sea surface elevation, slope and curvature and they were used to analyze the variability of estimated directions.•The simultaneous acquisition of slope and curvature parameters can contribute to estimates wave direction, thus increasing accuracy and precision of results.

  14. Determining Directions of Ultrasound in Solids

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R.; Roth, Don J.

    1987-01-01

    Ultrasound shadows cast by grooves. Improved method for determining direction of ultrasound in materials is shadow method using Scanning laser acoustic microscopy (SLAM). Direction of ultrasound calculated from dimensions of groove and portion of surface groove shields from ultrasound. Method has variety of applications in nontraditional quality-control applications.

  15. Comparison of multiplex real-time PCR and PCR-reverse blot hybridization assay for the direct and rapid detection of bacteria and antibiotic resistance determinants in positive culture bottles.

    PubMed

    Wang, Hye-Young; Kim, Seoyong; Kim, Jungho; Park, Soon Deok; Kim, Hyo Youl; Uh, Young; Lee, Hyeyoung

    2016-09-01

    The aim of this study was to evaluate the performance of a commercially available multiplex real-time PCR assay and a PCR-reverse blot hybridization assay (PCR-REBA) for the rapid detection of bacteria and identification of antibiotic resistance genes directly from blood culture bottles and to compare the results of these molecular assays with conventional culture methods. The molecular diagnostic methods were used to evaluate 593 blood culture bottles from patients with bloodstream infections. The detection positivity of multiplex real-time PCR assay for Gram-positive bacteria, Gram-negative bacteria and Candida spp. was equivalent to PCR-REBA as 99.6 %, 99.1 % and 100 %, respectively. Using conventional bacterial cultures as the gold standard, the sensitivity, specificity, positive predictive value and negative predictive value of these two molecular methods were 99.5 % [95 % confidence interval (CI), 0.980-1.000; P<0.001), 100 % (95 % CI, 0.983-1.000; P<0.001), 100 % and 99 %, respectively. However, positivity of the Real-methicillin-resistant Staphylococcusaureus multiplex real-time PCR assay targeting the mecA gene to detect methicillin resistance was lower than that of the PCR-REBA method, detecting an overall positivity of 98.4 % (n=182; 95 % CI, 0.964-1.000; P<0.009) and 99.5 % (n=184; 95 % CI, 0.985-1.000; P<0.0001), respectively. The entire two methods take about 3 h, while results from culture can take up to 48-72 h. Therefore, the use of these two molecular methods was rapid and reliable for the characterization of causative pathogens in bloodstream infections.

  16. Flow direction determination of lava flows.

    NASA Technical Reports Server (NTRS)

    Smith, E. I.; Rhodes, R. C.

    1972-01-01

    The flow direction technique, previously applied to ash-flow sheets, can be used to determine direction of movement and locate eruptive centers for lava flows. The method provides statistically stronger and more consistent flow direction data for lava than ash-flow tuff. The accuracy and reliability of the technique was established on the porphyritic basaltic andesite of Mount Taylor, New Mexico, which erupted from a known center, the Mount Taylor Amphitheater. The technique was then applied to volcanic units with unknown sources: the John Kerr Peak Quartz Latite and mid-Tertiary andesite flows in the Mogollon Mountains, both in southwestern New Mexico. The flow direction technique indicated flow patterns and suggested source areas for each rock unit. In the Mogollon Mountains flow direction measurements were supported by independent directional criteria such as dips of cross beds, stratigraphic thickening, facies changes, and megascopic textures.-

  17. Print your own membrane: direct rapid prototyping of polydimethylsiloxane.

    PubMed

    Femmer, Tim; Kuehne, Alexander J C; Wessling, Matthias

    2014-08-07

    Polydimethylsiloxane is a translucent and biologically inert silicone material used in sealants, biomedical implants and microscale lab-on-a-chip devices. Furthermore, in membrane technology, polydimethylsiloxane represents a material for separation barriers as it has high permeabilities for various gases. The facile handling of two component formulations with a silicone base material, a catalyst and a small molecular weight crosslinker makes it widely applicable for soft-lithographic replication of two-dimensional device geometries, such as microfluidic chips or micro-contact stamps. Here, we develop a new technique to directly print polydimethylsiloxane in a rapid prototyping device, circumventing the need for masks or sacrificial mold production. We create a three-dimensional polydimethylsiloxane membrane for gas-liquid-contacting based on a Schwarz-P triple-periodic minimal-surface, which is inaccessible with common machining techniques. Direct 3D-printing of polydimethylsiloxane enables rapid production of novel chip geometries for a manifold of lab-on-a-chip applications.

  18. Rapid determination of fumigant and industrial chemical residues in food.

    PubMed

    Daft, J L

    1988-01-01

    micro-Florisil columns. Also, clear beverages (e.g., soda and tea) are extracted directly with isooctane. These extraction and cleanup techniques were tested on 231 different table-ready foods. Three-hundred incurred residues of 10 different fumigants were found in 138 items examined; 93 items had no detectable residues. The main advantage of the method is rapid semiquantitative determination of multiple fumigants from all food types.

  19. Rapid exploration of curvilinear grids using direct volume rendering

    NASA Technical Reports Server (NTRS)

    Vangelder, Allen; Wilhelms, Jane

    1993-01-01

    Fast techniques for direct volume rendering over curvilinear grids of hexahedral cells are developed. This type of 3D grid is common in computational fluid dynamics and finite element analysis. Four new projection methods are presented and compared with each other and with previous methods for tetrahedral grids and rectilinear grids. All four methods use polygon-rendering hardware for speed. A simplified algorithm for visibility ordering, which is based on a combination of breadth-first and depth-first searches, is described. A new multi-pass blending method is described that reduces visual artifacts that are introduced by linear interpolation in hardware where exponential interpolation is needed. Multi-pass blending is of equal interest to hardware-oriented projection methods used on rectilinear grids. Visualization tools that permit rapid data banding and cycling through transfer functions, as well as region restrictions, are described.

  20. Directed Assembly of Soft Colloids through Rapid Solvent Exchange.

    PubMed

    Nikoubashman, Arash; Lee, Victoria E; Sosa, Chris; Prud'homme, Robert K; Priestley, Rodney D; Panagiotopoulos, Athanassios Z

    2016-01-26

    We studied the directed assembly of soft nanoparticles through rapid micromixing of polymers in solution with a nonsolvent. Both experiments and computer simulations were performed to elucidate the underlying physics and to investigate the role of various process parameters. In particular, we discovered that no external stabilizing agents or charged end groups are required to keep the colloids separated from each other when water is used as the nonsolvent. Furthermore, the size of the nanoparticles can be reliably tuned through the mixing rate and the ratio between polymer solution and nonsolvent. Our results demonstrate that this mechanism is highly promising for the mass fabrication of uniformly sized colloidal particles, using a wide variety of polymeric feed materials.

  1. Practicality and accuracy of prehospital rapid venous blood glucose determination.

    PubMed

    Holstein, A; Kühne, D; Elsing, H G; Thiessen, E; Plaschke, A; Widjaja, A; Vogel, M Y; Egberts, E H

    2000-10-01

    Blood glucose testing plays an important role in emergency medicine. Although the use of visual reagent test strips is widely established in this setting, the accuracy of reflectometric blood glucose determinations under emergency conditions has rarely been investigated. In a prospective study, 522 of a total of 3,217 patients undergoing emergency blood glucose testing had parallel blood glucose measurements performed using a specific enzymatic method. These 522 patients (aged 61.4 years, 54% men, 90 cases of severe hypoglycemia) had an intravenous access placed at the scene of the emergency. Venous whole blood from the introducer needle of the access was applied to the test strip and the glucose measured with a GlucoTouch reflectometer (LifeScan, Inc.). A blood sample from the intravenous access was then immediately collected in a monovette for subsequent glucose determination in a chemical laboratory (hexokinase method) within 20 to 40 minutes. The emergency glucose measurements (mean: 7.3 mmol/L [95% confidence interval [CI] 6.9 to 7.7]; range: 0.55 to 27.7) correlated well with the reference laboratory results (Pearson's r = .98; linear regression analysis: slope 1.0, axial intercept 1.74). Error grid analysis also showed good agreement between corresponding measurements: zone A 96.7%, B 2.5%, C 0% and D 0.8%. The mean difference using the Bland-Altman method was 0.14 mmoVL; 2 SD 1.8 mmol/L; minimum -7.0 mmol/L; maximum 4.4 mmol/L. The accuracy of the rapid venous blood glucose determination by constantly changing emergency teams was high. Especially in 90 hypoglycemic patients, there were no deviations from the reference method that could have led to clinically relevant wrong decisions. The method of collecting whole blood directly from the venous access is simple and robust, and is independent of the hemodynamic status of the patient.

  2. Resistive graphene humidity sensors with rapid and direct electrical readout

    NASA Astrophysics Data System (ADS)

    Smith, Anderson D.; Elgammal, Karim; Niklaus, Frank; Delin, Anna; Fischer, Andreas C.; Vaziri, Sam; Forsberg, Fredrik; Råsander, Mikael; Hugosson, Håkan; Bergqvist, Lars; Schröder, Stephan; Kataria, Satender; Östling, Mikael; Lemme, Max C.

    2015-11-01

    We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N2), oxygen (O2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further investigate the sensitivity of the graphene devices towards water vapor. The interaction between the electrostatic dipole moment of the water and the impurity bands in the SiO2 substrate leads to electrostatic doping of the graphene layer. The proposed graphene sensor provides rapid response direct electrical readout and is compatible with back end of the line (BEOL) integration on top of CMOS-based integrated circuits.We demonstrate humidity sensing using a change of the electrical resistance of single-layer chemical vapor deposited (CVD) graphene that is placed on top of a SiO2 layer on a Si wafer. To investigate the selectivity of the sensor towards the most common constituents in air, its signal response was characterized individually for water vapor (H2O), nitrogen (N2), oxygen (O2), and argon (Ar). In order to assess the humidity sensing effect for a range from 1% relative humidity (RH) to 96% RH, the devices were characterized both in a vacuum chamber and in a humidity chamber at atmospheric pressure. The measured response and recovery times of the graphene humidity sensors are on the order of several hundred milliseconds. Density functional theory simulations are employed to further

  3. Rapid Screening Tests for Determining In Vitro Susceptibility of Herpes Simplex Virus Clinical Isolates

    PubMed Central

    de la Iglesia, Pedro; Melón, Santiago; López, Beatriz; Rodriguez, Mercedes; Blanco, Maria I.; Mellado, Purificación; de Oña, Maria

    1998-01-01

    The susceptibility of human herpes simplex virus (HSV) to acyclovir (ACV) was determined with the use of a single dose of the drug (1 and 2 μg of ACV per ml for HSV-1 and HSV-2, respectively) in two rapid assays: a rapid cytopathic effect inhibitory assay (Rapid CIA) and a rapid dye uptake assay (Rapid DUA). These tests allow the simultaneous determination of virus titer and susceptibility to ACV at a determined viral concentration (100 50% tissue culture infective doses and 100 50% dye uptake units). These tests were compared with a conventional susceptibility assay (dye uptake assay) and showed similar results. Indeterminate results with the Rapid CIA appeared in 3 of 30 samples. With the use of both Rapid CIA and Rapid DUA, we were able to determine the susceptibility of 100% of the isolates. The rapid tests, unlike conventional assays, are able to provide susceptibility results within 3 days after the virus has been isolated from a clinical specimen and could thus play a direct role in therapeutic decisions. PMID:9666034

  4. Rapid screening tests for determining in vitro susceptibility of herpes simplex virus clinical isolates.

    PubMed

    de la Iglesia, P; Melón, S; López, B; Rodriguez, M; Blanco, M I; Mellado, P; de Oña, M

    1998-08-01

    The susceptibility of human herpes simplex virus (HSV) to acyclovir (ACV) was determined with the use of a single dose of the drug (1 and 2 micrograms of ACV per ml for HSV-1 and HSV-2, respectively) in two rapid assays: a rapid cytopathic effect inhibitory assay (Rapid CIA) and a rapid dye uptake assay (Rapid DUA). These tests allow the simultaneous determination of virus titer and susceptibility to ACV at a determined viral concentration (100 50% tissue culture infective doses and 100 50% dye uptake units). These tests were compared with a conventional susceptibility assay (dye uptake assay) and showed similar results. Indeterminate results with the Rapid CIA appeared in 3 of 30 samples. With the use of both Rapid CIA and Rapid DUA, we were able to determine the susceptibility of 100% of the isolates. The rapid tests, unlike conventional assays, are able to provide susceptibility results within 3 days after the virus has been isolated from a clinical specimen and could thus play a direct role in therapeutic decisions.

  5. RAPID DETERMINATION OF {sup 210} PO IN WATER SAMPLES

    SciTech Connect

    Maxwell, S.

    2013-05-22

    A new rapid method for the determination of {sup 210}Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that can be used for emergency response or routine water analyses. If a radiological dispersive device (RDD) event or a radiological attack associated with drinking water supplies occurs, there will be an urgent need for rapid analyses of water samples, including drinking water, ground water and other water effluents. Current analytical methods for the assay of {sup 210}Po in water samples have typically involved spontaneous auto-deposition of {sup 210}Po onto silver or other metal disks followed by counting by alpha spectrometry. The auto-deposition times range from 90 minutes to 24 hours or more, at times with yields that may be less than desirable. If sample interferences are present, decreased yields and degraded alpha spectrums can occur due to unpredictable thickening in the deposited layer. Separation methods have focused on the use of Sr Resin, often in combination with 210Pb analysis. A new rapid method for {sup 210}Po in water samples has been developed at the Savannah River National Laboratory (SRNL) that utilizes a rapid calcium phosphate co-precipitation method, separation using DGA Resin (N,N,N,N-tetraoctyldiglycolamide extractant-coated resin, Eichrom Technologies or Triskem-International), followed by rapid microprecipitation of {sup 210}Po using bismuth phosphate for counting by alpha spectrometry. This new method can be performed quickly with excellent removal of interferences, high chemical yields and very good alpha peak resolution, eliminating any potential problems with the alpha source preparation for emergency or routine samples. A rapid sequential separation method to separate {sup 210} Po and actinide isotopes was also developed. This new approach, rapid separation with DGA Resin plus microprecipitation for alpha source preparation, is a significant advance in radiochemistry for the rapid

  6. Suitability of rapid energy magnitude determinations for emergency response purposes

    NASA Astrophysics Data System (ADS)

    Di Giacomo, Domenico; Parolai, Stefano; Bormann, Peter; Grosser, Helmut; Saul, Joachim; Wang, Rongjiang; Zschau, Jochen

    2010-01-01

    It is common practice in the seismological community to use, especially for large earthquakes, the moment magnitude Mw as a unique magnitude parameter to evaluate the earthquake's damage potential. However, as a static measure of earthquake size, Mw does not provide direct information about the released seismic wave energy and its high frequency content, which is the more interesting information both for engineering purposes and for a rapid assessment of the earthquake's shaking potential. Therefore, we recommend to provide to disaster management organizations besides Mw also sufficiently accurate energy magnitude determinations as soon as possible after large earthquakes. We developed and extensively tested a rapid method for calculating the energy magnitude Me within about 10-15 min after an earthquake's occurrence. The method is based on pre-calculated spectral amplitude decay functions obtained from numerical simulations of Green's functions. After empirical validation, the procedure has been applied offline to a large data set of 767 shallow earthquakes that have been grouped according to their type of mechanism (strike-slip, normal faulting, thrust faulting, etc.). The suitability of the proposed approach is discussed by comparing our rapid Me estimates with Mw published by GCMT as well as with Mw and Me reported by the USGS. Mw is on average slightly larger than our Me for all types of mechanisms. No clear dependence on source mechanism is observed for our Me estimates. In contrast, Me from the USGS is generally larger than Mw for strike-slip earthquakes and generally smaller for the other source types. For ~67 per cent of the event data set our Me differs <= +/-0.3 magnitude units (m.u.) from the respective Me values published by the USGS. However, larger discrepancies (up to 0.8 m.u.) may occur for strike-slip events. A reason of that may be the overcorrection of the energy flux applied by the USGS for this type of earthquakes. We follow the original

  7. Mass Determination Of Directly Imaged Planet Candidates

    NASA Astrophysics Data System (ADS)

    Schmidt, Tobias; Neuhauser, R.; Seifahrt, A.

    2011-09-01

    About 20 sub-stellar companions with large separations (> 50 AU) to their young primary stars and brown dwarfs are confirmed by both common proper motion and late-M / early-L type spectra. The origin and early evolution of these objects is still under debate. While often these sub-stellar companions are regarded as brown dwarfs, they could possibly also be massive planets, the mass estimates are very uncertain so far. They are companions to primary stars or brown dwarfs in young associations and star forming regions like Taurus, Upper Scorpius, the TW Hya association, Beta Pic moving group, TucHor association, Lupus, Ophiuchus, and Chamaeleon, hence their ages and distances are well known, in contrast to free-floating brown dwarfs. Here we present how mass estimates of such young directly imaged companions can be derived, using e.g. evolutionary models, which are however currently almost uncalibrated by direct mass measurements of young objects. An empirical classification by medium-resolution spectroscopy is currently not possible, because a spectral sequence that is taking the lower gravity into account, is not existing. This problem leads to an apparent mismatch between spectra of old field type objects and young low-mass companions at the same effective temperature, hampering a determination of temperature and surface gravity independent from models. We show that from spectra of the objects, using the advantages of light concentration by an AO-assisted integral field spectrograph, temperature, extinction, metallicity and surface gravity can be derived using non-equilibrium radiative transfer atmosphere models as comparison and that this procedure as well allows a mass determination in combination with the luminosities found by the direct observations, as has recently been done by us for several young sub-stellar companions, as e.g. GQ Lup, CT Cha or UScoCTIO 108.

  8. Rapid determination of 226Ra in emergency urine samples

    DOE PAGES

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.; ...

    2014-02-27

    A new method has been developed at the Savannah River National Laboratory (SRNL) that can be used for the rapid determination of 226Ra in emergency urine samples following a radiological incident. If a radiological dispersive device event or a nuclear accident occurs, there will be an urgent need for rapid analyses of radionuclides in urine samples to ensure the safety of the public. Large numbers of urine samples will have to be analyzed very quickly. This new SRNL method was applied to 100 mL urine aliquots, however this method can be applied to smaller or larger sample aliquots as needed.more » The method was optimized for rapid turnaround times; urine samples may be prepared for counting in <3 h. A rapid calcium phosphate precipitation method was used to pre-concentrate 226Ra from the urine sample matrix, followed by removal of calcium by cation exchange separation. A stacked elution method using DGA Resin was used to purify the 226Ra during the cation exchange elution step. This approach combines the cation resin elution step with the simultaneous purification of 226Ra with DGA Resin, saving time. 133Ba was used instead of 225Ra as tracer to allow immediate counting; however, 225Ra can still be used as an option. The rapid purification of 226Ra to remove interferences using DGA Resin was compared with a slightly longer Ln Resin approach. A final barium sulfate micro-precipitation step was used with isopropanol present to reduce solubility; producing alpha spectrometry sources with peaks typically <40 keV FWHM (full width half max). This new rapid method is fast, has very high tracer yield (>90 %), and removes interferences effectively. The sample preparation method can also be adapted to ICP-MS measurement of 226Ra, with rapid removal of isobaric interferences.« less

  9. Dark matter directional detection: comparison of the track direction determination

    NASA Astrophysics Data System (ADS)

    Couturier, C.; Zopounidis, J. P.; Sauzet, N.; Naraghi, F.; Santos, D.

    2017-01-01

    Several directional techniques have been proposed for a directional detection of Dark matter, among others anisotropic crystal detectors, nuclear emulsion plates, and low-pressure gaseous TPCs. The key point is to get access to the initial direction of the nucleus recoiling due to the elastic scattering by a WIMP. In this article, we aim at estimating, for each method, how the information of the recoil track initial direction is preserved in different detector materials. We use the SRIM simulation code to emulate the motion of the first recoiling nucleus in each material. We propose the use of a new observable, D, to quantify the preservation of the initial direction of the recoiling nucleus in the detector. We show that in an emulsion mix and an anisotropic crystal, the initial direction is lost very early, while in a typical TPC gas mix, the direction is well preserved.

  10. Determining the direction of a turbulent cascade

    NASA Astrophysics Data System (ADS)

    Goldburg, Walter; Cerbus, Rory

    2015-11-01

    In two-dimensional (2D) turbulence, one expects a cascade of energy to larger spatial scales, while the enstrophy cascade is to smaller ones. Here we present a new tool to study cascades using simple ideas borrowed from information theory. It is entirely unrelated to the Navier-Stoke's equations or any scaling arguments. We use the conditional entropy (conditioned uncertainty) of velocity fluctuations on one scale conditioned on another larger or smaller scale. If the entropy is larger after conditioning on larger scales rather than smaller ones, then the cascade is to smaller scales. By varying the scale of the velocity fluctuations used in the conditioning, we can test both direction and locality. We use these tools on experimental data taken from a flowing soap film, an approximately 2D turbulent flow. The Reynolds number is varied over a wide range to determine the entropy's scaling with Reynolds number OIST.

  11. Directed Random Markets: Connectivity Determines Money

    NASA Astrophysics Data System (ADS)

    Martínez-Martínez, Ismael; López-Ruiz, Ricardo

    2013-12-01

    Boltzmann-Gibbs (BG) distribution arises as the statistical equilibrium probability distribution of money among the agents of a closed economic system where random and undirected exchanges are allowed. When considering a model with uniform savings in the exchanges, the final distribution is close to the gamma family. In this paper, we implement these exchange rules on networks and we find that these stationary probability distributions are robust and they are not affected by the topology of the underlying network. We introduce a new family of interactions: random but directed ones. In this case, it is found the topology to be determinant and the mean money per economic agent is related to the degree of the node representing the agent in the network. The relation between the mean money per economic agent and its degree is shown to be linear.

  12. RAPID DETERMINATION OF RA-226 IN ENVIRONMENTAL SAMPLES

    SciTech Connect

    Maxwell, S.

    2012-01-03

    A new rapid method for the determination of {sup 226}Ra in environmental samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for emergency response or routine sample analyses. The need for rapid analyses in the event of a Radiological Dispersive Device or Improvised Nuclear Device event is well-known. In addition, the recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid analyses for radionuclides in environmental samples in the event of a nuclear accident. {sup 226}Ra (T1/2 = 1,620 years) is one of the most toxic of the long-lived alpha-emitters present in the environment due to its long life and its tendency to concentrate in bones, which increases the internal radiation dose of individuals. The new method to determine {sup 226}Ra in environmental samples utilizes a rapid sodium hydroxide fusion method for solid samples, calcium carbonate precipitation to preconcentrate Ra, and rapid column separation steps to remove interferences. The column separation process uses cation exchange resin to remove large amounts of calcium, Sr Resin to remove barium and Ln Resin as a final purification step to remove {sup 225}Ac and potential interferences. The purified {sup 226}Ra sample test sources are prepared using barium sulfate microprecipitation in the presence of isopropanol for counting by alpha spectrometry. The method showed good chemical recoveries and effective removal of interferences. The determination of {sup 226}Ra in environmental samples can be performed in less than 16 h for vegetation, concrete, brick, soil, and air filter samples with excellent quality for emergency or routine analyses. The sample preparation work takes less than 6 h. {sup 225}Ra (T1/2 = 14.9 day) tracer is used and the {sup 225}Ra progeny {sup 217}At is used to determine chemical yield via alpha spectrometry. The rapid fusion technique is a rugged sample digestion method that ensures that any

  13. Rapid Determination Of Radiostrontium In Large Soil Samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.; Shaw, Patrick J.

    2012-05-24

    A new method for the determination of radiostrontium in large soil samples has been developed at the Savannah River Environmental Laboratory (Aiken, SC, USA) that allows rapid preconcentration and separation of strontium in large soil samples for the measurement of strontium isotopes by gas flow proportional counting. The need for rapid analyses in the event of a Radiological Dispersive Device (RDD) or Improvised Nuclear Device (IND) event is well-known. In addition, the recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid analyses for radionuclides in environmental samples in the event of a nuclear accident. The method employs a novel pre-concentration step that utilizes an iron hydroxide precipitation (enhanced with calcium phosphate) followed by a final calcium fluoride precipitation to remove silicates and other matrix components. The pre-concentration steps, in combination with a rapid Sr Resin separation using vacuum box technology, allow very large soil samples to be analyzed for {sup 89,90}Sr using gas flow proportional counting with a lower method detection limit. The calcium fluoride precipitation eliminates column flow problems typically associated with large amounts of silicates in large soil samples.

  14. Instructional authoring by direct manipulation of simulations: Exploratory applications of RAPIDS. RAPIDS 2 authoring manual

    NASA Technical Reports Server (NTRS)

    1990-01-01

    RAPIDS II is a simulation-based intelligent tutoring system environment. It is a system for producing computer-based training courses that are built on the foundation of graphical simulations. RAPIDS II simulations can be animated and they can have continuously updating elements.

  15. Rapid optical determination of β-lactamase and antibiotic activity

    PubMed Central

    2014-01-01

    Background The absence of rapid tests evaluating antibiotic susceptibility results in the empirical prescription of antibiotics. This can lead to treatment failures due to escalating antibiotic resistance, and also furthers the emergence of drug-resistant bacteria. This study reports a rapid optical method to detect β-lactamase and thereby assess activity of β-lactam antibiotics, which could provide an approach for targeted prescription of antibiotics. The methodology is centred on a fluorescence quenching based probe (β-LEAF – β-Lactamase Enzyme Activated Fluorophore) that mimics the structure of β-lactam antibiotics. Results The β-LEAF assay was performed for rapid determination of β-lactamase production and activity of β-lactam antibiotic (cefazolin) on a panel of Staphylococcus aureus ATCC strains and clinical isolates. Four of the clinical isolates were determined to be lactamase producers, with the capacity to inactivate cefazolin, out of the twenty-five isolates tested. These results were compared against gold standard methods, nitrocefin disk test for β-lactamase detection and disk diffusion for antibiotic susceptibility, showing results to be largely consistent. Furthermore, in the sub-set of β-lactamase producers, it was demonstrated and validated that multiple antibiotics (cefazolin, cefoxitin, cefepime) could be assessed simultaneously to predict the antibiotic that would be most active for a given bacterial isolate. Conclusions The study establishes the rapid β-LEAF assay for β-lactamase detection and prediction of antibiotic activity using S. aureus clinical isolates. Although the focus in the current study is β-lactamase-based resistance, the overall approach represents a broad diagnostic platform. In the long-term, these studies form the basis for the development of assays utilizing a broader variety of targets, pathogens and drugs. PMID:24708478

  16. Rapid optical determination of β-lactamase and antibiotic activity.

    PubMed

    Khan, Shazia; Sallum, Ulysses W; Zheng, Xiang; Nau, Gerard J; Hasan, Tayyaba

    2014-04-04

    The absence of rapid tests evaluating antibiotic susceptibility results in the empirical prescription of antibiotics. This can lead to treatment failures due to escalating antibiotic resistance, and also furthers the emergence of drug-resistant bacteria. This study reports a rapid optical method to detect β-lactamase and thereby assess activity of β-lactam antibiotics, which could provide an approach for targeted prescription of antibiotics. The methodology is centred on a fluorescence quenching based probe (β-LEAF--β-Lactamase Enzyme Activated Fluorophore) that mimics the structure of β-lactam antibiotics. The β-LEAF assay was performed for rapid determination of β-lactamase production and activity of β-lactam antibiotic (cefazolin) on a panel of Staphylococcus aureus ATCC strains and clinical isolates. Four of the clinical isolates were determined to be lactamase producers, with the capacity to inactivate cefazolin, out of the twenty-five isolates tested. These results were compared against gold standard methods, nitrocefin disk test for β-lactamase detection and disk diffusion for antibiotic susceptibility, showing results to be largely consistent. Furthermore, in the sub-set of β-lactamase producers, it was demonstrated and validated that multiple antibiotics (cefazolin, cefoxitin, cefepime) could be assessed simultaneously to predict the antibiotic that would be most active for a given bacterial isolate. The study establishes the rapid β-LEAF assay for β-lactamase detection and prediction of antibiotic activity using S. aureus clinical isolates. Although the focus in the current study is β-lactamase-based resistance, the overall approach represents a broad diagnostic platform. In the long-term, these studies form the basis for the development of assays utilizing a broader variety of targets, pathogens and drugs.

  17. 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.

  18. 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.

  19. An instrument for rapid, accurate, determination of fuel moisture content

    Treesearch

    Stephen S. Sackett

    1980-01-01

    Moisture contents of dead and living fuels are key variables in fire behavior. Accurate, real-time fuel moisture data are required for prescribed burning and wildfire behavior predictions. The convection oven method has become the standard for direct fuel moisture content determination. Efforts to quantify fuel moisture through indirect methods have not been...

  20. Determining orientation and direction of DNA sequences

    DOEpatents

    Goodwin, Edwin H.; Meyne, Julianne

    2000-01-01

    Determining orientation and direction of DNA sequences. A method by which fluorescence in situ hybridization can be made strand specific is described. Cell cultures are grown in a medium containing a halogenated nucleotide. The analog is partially incorporated in one DNA strand of each chromatid. This substitution takes place in opposite strands of the two sister chromatids. After staining with the fluorescent DNA-binding dye Hoechst 33258, cells are exposed to long-wavelength ultraviolet light which results in numerous strand nicks. These nicks enable the substituted strand to be denatured and solubilized by heat, treatment with high or low pH aqueous solutions, or by immersing the strands in 2.times.SSC (0.3M NaCl+0.03M sodium citrate), to name three procedures. It is unnecessary to enzymatically digest the strands using Exo III or another exonuclease in order to excise and solubilize nucleotides starting at the sites of the nicks. The denaturing/solubilizing process removes most of the substituted strand while leaving the prereplication strand largely intact. Hybridization of a single-stranded probe of a tandem repeat arranged in a head-to-tail orientation will result in hybridization only to the chromatid with the complementary strand present.

  1. Rapid determination of global moment-tensor solutions

    USGS Publications Warehouse

    Sipkin, S.A.

    1994-01-01

    In an effort to improve data services, the National Earthquake Information Center has begun a program, in cooperation with the Incorporated Research Institutions for Seismology Data Management Center (IRIS DMC), to produce rapid estimates of the seismic moment tensor for most earthquakes with a bodywave magnitude of 5.8 or greater. An estimate of the moment tensor can usually be produced within 20 minutes of the arrival of the broadband P-waveform data from the IRIS DMC. The solutions do not vary significantly from the final solutions determined using the entire network. -from Author

  2. Simple and rapid determination of myristicin in human serum.

    PubMed

    Dawidowicz, Andrzej L; Dybowski, Michal P

    2013-01-01

    Myristicin (5-allyl-1-methoxy-2,3-methylenodioxybenzene) is the main component of nutmeg (Myristica fragrans Houtt.) essential oil. The increasing use of myristicin as a cheap hallucinogenic intoxicant, frequently causing fatal cases of myristicin poisoning, requires new methods for determination of this compound in blood. This report describes the rapid, simple, and useful procedure for myristicin analysis in human serum, involving myristicin-protein complex degradation before chromatographic analysis. The developed method is characterized by a high recovery (above 99 %), a low detection limit (6.0 ng/g) and good repeatability (average RDS of 2.01 %).

  3. Analysis of Pteridium ribosomal RNA sequences by rapid direct sequencing.

    PubMed

    Tan, M K

    1991-08-01

    A total of 864 bases from 5 regions interspersed in the 18S and 26S rRNA molecules from various clones of Pteridium covering the general geographical distribution of the genus was analysed using a rapid rRNA sequencing technique. No base difference has been detected amongst the three major lineages, two of which apparently separated before the breakup of the ancient supercontinent, Pangaea. These regions of the rRNA sequences have thus been conserved for at least 160 million years and are here compared with other eukaryotic, especially plant rRNAs.

  4. Rapid determination of total Kjeldahl nitrogen using microwave digestion.

    PubMed

    Lo, K V; Wong, W T; Liao, P H

    2005-01-01

    A closed-vessel microwave digestion process for the determination of total Kjeldahl nitrogen (TKN) has been developed for sewage and wastewater. TKN values obtained from the microwave digestion method were in excellent agreement with those of the thermal digestion method. The accuracy of both analytical methods is comparable. In comparison to the conventional thermal digestion, the microwave method shortened the time required for complete digestion from 4 h to 25 min, and also decreased the maximum digestion temperature from 380 degrees C to 200 degrees C. This developed method may contribute to a significant reduction in sample digestion time, resulting in an increase in analytical throughput. The microwave digestion method developed in this study could be a rapid and efficient means for TKN determination for sewage wastewater and sludge.

  5. A rapid liquid chromatography determination of free formaldehyde in cod.

    PubMed

    Storey, Joseph M; Andersen, Wendy C; Heise, Andrea; Turnipseed, Sherri B; Lohne, Jack; Thomas, Terri; Madson, Mark

    2015-01-01

    A rapid method for the determination of free formaldehyde in cod is described. It uses a simple water extraction of formaldehyde which is then derivatised with 2,4-dinitrophenylhydrazine (DNPH) to form a sensitive and specific chromophore for high-performance liquid chromatography (HPLC) detection. Although this formaldehyde derivative has been widely used in past tissue analysis, this paper describes an improved derivatisation procedure. The formation of the DNPH formaldehyde derivative has been shortened to 2 min and a stabilising buffer has been added to the derivative to increase its stability. The average recovery of free formaldehyde in spiked cod was 63% with an RSD of 15% over the range of 25-200 mg kg(-1) (n = 48). The HPLC procedure described here was also compared to a commercial qualitative procedure - a swab test for the determination of free formaldehyde in fish. Several positive samples were compared by both methods.

  6. Rapid determination of aflatoxins in corn and peanuts.

    PubMed

    Fu, Zhaohui; Huang, Xuexiang; Min, Shungeng

    2008-10-31

    A rapid and simple method using ultra-high-pressure liquid chromatography with UV detection for the determination of aflatoxins B1, B2, G1 and G2 in corn and peanuts has been developed. In this method, aflatoxins were extracted with a mixture of acetonitrile and water (86:14) and then purified by solid-phase clean-up with a MycoSep#226 AflaZon(+) column. The toxins were determined by UPLC-UV without derivatizing aflatoxins in real samples, which has not been used in other studies. The mean recoveries of aflatoxins from non-infected peanut and corn samples spiked with aflatoxins B1, B2, G1 and G2 at concentrations from 0.22 to 5 microg/kg were between 83.4% and 94.7%. The detection limits (S/N=3) for B1, B2, G1 and G2 were 0.32, 0.19, 0.32 and 0.19 microg/kg, and the corresponding quantification limits (S/N=10) were 1.07, 0.63, 1.07 and 0.63 microg/kg, respectively. We also applied this method on real samples. Among 16 peanut samples, 2 (12.5% incidence) were contaminated with aflatoxin; among 18 corn samples, 4 (22% incidence) were contaminated. The proposed method is rapid, simple and accurate for monitoring aflatoxins in corn and peanuts.

  7. Rapid determination of organic matter in spent sulfuric acid

    SciTech Connect

    Petrenko, V.G.; Takhtaeva, A.Ya.; Frolova, R.P.

    1981-01-01

    Ammonium sulfate is produced with the aid of spent sulfuric acid which averages 0.3 to 0.7% (and sometimes up to 2.5%) of carbon in the form of organic impurities. In the saturator, the latter upset the processing conditions and lower the quality (size analysis, etc.) of the ammonium sulfate. A rapid quality control procedure is essential to obtain timely warning of increased organic matter contents in the acid. On the other hand, the standard procedure in current use (TU38-2-3-1-68), based on the oxidation of organic substances with potassium bichromate in an acid medium, takes 3 hr to complete. Observations have revealed a correlation between the color of the acid and its organic impurity contents. On this basis, we have developed a rapid photocolorimetric procedure for determining the organic impurity contents of sulfuric acid, based on the known proportionality between optical density (light absorption) and solute (dye) content. A calibration curve is used to convert optical density readings to organic impurity contents. It should be pointed out that in contrast to the standard procedure, our procedure only determines the concentration of organic matter in solution in the acid. However, the amounts of insoluble organic matter are negligible compared with the amounts in solution and therefore do not affect the final results.

  8. Rapid infrared determination of the potency of chlorinated bactericides.

    PubMed

    Spagnolo, F; Cestaro, J P

    1971-06-01

    A rapid infrared reflectance method for evaluating the germicidal potency of synthetic materials containing various amounts of two chlorinated bactericides was developed. The dimeric product 2,2'-methylenebis (4,6-dichlorophenol) exhibited a characteristic C=C skeletal inplane stretching infrared absorption band at 1,640 cm(-1). The monomeric 2,4-dichlorophenol precursor showed a characteristic absorption band at 1,579 cm(-1). These characteristic infrared absorptions may be used for analysis of the potency of the manufactured chlorinated bactericide. For a series of samples known to vary in dimer content, the micrograms per milliliter required for a 100% bacterial kill is first determined by a standard American Petroleum Institute method. Then the area ratio of the infrared absorption bands characteristic of the chlorinated bactericides is measured for each sample and plotted versus the microgram per milliliter required for 100% bacterial kill. The potency of subsequent samples is simply and rapidly determined by measuring this ratio from the infrared absorption curve and calculating micrograms per milliliter required for 100% kill from the calibration curve. Analysis time is approximately 1 hr compared to biocidal tests in current use requiring approximately a 1-month incubation period.

  9. Rapid determination of nanogram amounts of tellurium in silicate rocks

    USGS Publications Warehouse

    Greenland, L.P.; Campbell, E.Y.

    1976-01-01

    A hydride-generation flameless atomic-absorption technique is used to determine as little as 5 ng g-1 tellurium in 0.25 g of silicate rock. After acid decomposition of the sample, tellurium hydride is generated with sodium borohydride and the vapor passed directly to a resistance-heated quartz cell mounted in an atomic-absorption spectrophotometer. Analyses of 11 U.S. Geological Survey standard rocks are presented. ?? 1976.

  10. Evaluation of a rapid Bauer-Kirby antibiotic susceptibility determination.

    PubMed

    Liberman, D F; Robertson, R G

    1975-03-01

    To reduce the incubation time requirement in the Bauer-Kirby antibiotic susceptibility test, comparisons were made of the test results at 18 to 20 h (standard) and 7 to 8 h (rapid) utilizing 100 recent clinical isolates. The zone diameters for 664 disks were monitored by using the standard classification: resistant, intermediate, or susceptible. The susceptibility determination was unchanged in 558 out of 664 instances (84.0%). An analysis of the remaining 106 sets revealed that an initial interpretation of intermediate in zone size, subsequently determined resistant or susceptible, accounted for 49 of the observed differences. The reverse changes, initial resistant or susceptible subsequently classified as intermediate, accounted for 20 of the changes. In five instances the interpretation changed from susceptible to resistant; in two cases the interpretation changed from resistant to susceptible. The remaining 30 determinations were classified as indeterminant due to (i) insufficient growth at the early (7 to 8 h) determination, and to (ii) zones which were so large that they could not be measured accurately. The data indicate that zone sizes when measured to the nearest 0.1 mm can be interpreted with reasonable accuracy and the results can be available 10 to 14 h sooner.

  11. On Directional Measurement Representation in Orbit Determination

    DTIC Science & Technology

    2016-09-13

    equirectangular projection distorts both distance and direction on a map . One technique is to weight the azimuth residuals by the cosine of the elevation, as in...directional measurements is equivalent to choosing a transformation from location on a sphere to location in a plane which has a long history in map ...The second approach is to preserve area in mapping the celestial sphere to the plane by weighting the azimuth residual by the length of the

  12. Rapid determination of plasmonic nanoparticle agglomeration status in blood.

    PubMed

    Jenkins, Samir V; Qu, Haiou; Mudalige, Thilak; Ingle, Taylor M; Wang, Rongrong; Wang, Feng; Howard, Paul C; Chen, Jingyi; Zhang, Yongbin

    2015-05-01

    Plasmonic nanomaterials as drug delivery or bio-imaging agents are typically introduced to biological systems through intravenous administration. However, the potential for agglomeration of nanoparticles in biological systems could dramatically affect their pharmacokinetic profile and toxic potential. Development of rapid screening methods to evaluate agglomeration is urgently needed to monitor the physical nature of nanoparticles as they are introduced into blood. Here, we establish novel methods using darkfield microscopy with hyperspectral detection (hsDFM), single particle inductively-coupled plasma mass spectrometry (spICP-MS), and confocal Raman microscopy (cRM) to discriminate gold nanoparticles (AuNPs) and their agglomerates in blood. Rich information about nanoparticle agglomeration in situ is provided by hsDFM monitoring of the plasmon resonance of primary nanoparticles and their agglomerates in whole blood; cRM is an effective complement to hsDFM to detect AuNP agglomerates in minimally manipulated samples. The AuNPs and the particle agglomerates were further distinguished in blood for the first time by quantification of particle mass using spICP-MS with excellent sensitivity and specificity. Furthermore, the agglomeration status of synthesized and commercial NPs incubated in blood was successfully assessed using the developed methods. Together, these complementary methods enable rapid determination of the agglomeration status of plasmonic nanomaterials in biological systems, specifically blood.

  13. Rapid Determination of Plasmonic Nanoparticle Agglomeration Status in Blood

    PubMed Central

    Jenkins, Samir V.; Qu, Haiou; Mudalige, Thilak; Ingle, Taylor; Wang, RongRong; Wang, Feng; Howard, Paul C.; Chen, Jingyi; Zhang, Yongbin

    2015-01-01

    Plasmonic nanomaterials as drug delivery or bio-imaging agents are typically introduced to biological systems through intravenous administration. However, the potential for agglomeration of nanoparticles in biological systems could dramatically affect their pharmacokinetic profile and toxic potential. Development of rapid screening methods to evaluate agglomeration is urgently needed to monitor the physical nature of nanoparticles as they are introduced into blood. Here, we establish novel methods using darkfield microscopy with hyperspectral detection (hsDFM), single particle inductively-coupled plasma mass spectrometry (spICP-MS), and confocal Raman microscopy (cRM) to discriminate gold nanoparticles (AuNPs) and their agglomerates in blood. Rich information about nanoparticle agglomeration in situ is provided by hsDFM monitoring of the plasmon resonance of primary nanoparticles and their agglomerates in whole blood; cRM is an effective complement to hsDFM to detect AuNP agglomerates in minimally manipulated samples. The AuNPs and the particle agglomerates were further distinguished in blood for the first time by quantification of particle mass using spICP-MS with excellent sensitivity and specificity. Furthermore, the agglomeration status of synthesized and commercial NPs incubated in blood was successfully assessed using the developed methods. Together, these complementary methods enable rapid determination of the agglomeration status of plasmonic nanomaterials in biological systems, specifically blood. PMID:25771013

  14. Rapid Detection and Identification of Respiratory Viruses by Direct Immunofluorescence

    PubMed Central

    D'Alessio, Donn; Williams, Stanley; Dick, Elliot C.

    1970-01-01

    The use of fluorescein-conjugated antiserum against respiratory syncytial (RS) and parainfluenza 1 and 3 viruses was compared with conventional techniques in the rapid detection of virus in tissue cultures inoculated with pharyngeal specimens known to contain these viruses. Twenty-three specimens were tested: 9 RS, 8 parainfluenza 1, and 6 parainfluenza 3. The fluorescent-antibody technique (FA) detected virus in 52% of the tissue cultures in 24 hr, and, by 72 hr, 22 of the 23 cultures were FA-positive whereas only 5 were positive by conventional techniques. Additionally, conjugated antisera were prepared against herpes simplex, influenza A2, and adenovirus type 5. All conjugates stained only the homologous virus and were 100- to 10,000-fold more sensitive than conventional techniques in detecting descending dilutions of virus inocula by 24 hr. With the procedures described, several antisera could be conjugated and ready for use within 24 hr. Serum fractionation was by ammonium sulfate precipitation, and with the procedure outlined virtually complete recovery of the globulin fraction and elimination of all of the albumin were accomplished. Images PMID:4098101

  15. Capillary-wave description of rapid directional solidification.

    PubMed

    Korzhenevskii, Alexander L; Bausch, Richard; Schmitz, Rudi

    2012-02-01

    A recently introduced capillary-wave description of binary-alloy solidification is generalized to include the procedure of directional solidification. For a class of model systems a universal dispersion relation of the unstable eigenmodes of a planar steady-state solidification front is derived, which readjusts previously known stability considerations. We moreover establish a differential equation for oscillatory motions of a planar interface that offers a limit-cycle scenario for the formation of solute bands and, taking into account the Mullins-Sekerka instability, of banded structures.

  16. Rapid determination of the presence of enteric bacteria in water.

    PubMed

    Kenard, R P; Valentine, R S

    1974-03-01

    A rapid and sensitive method is described for the detection of bacteria in water and various other natural substrates by the isolation of specific bacteriophage. By the addition of large numbers of the organism in question to the sample, the presence of virulent bacteriophage can be demonstrated in as little as 6 to 8 h. Fecal coliform, total coliform, and total coliphage counts were determined for over 150 water samples from several geographical areas over a period of 2 years. Computer analysis of the data shows a high degree of correlation between fecal coliforms and the coliphage present in the samples. With a high correlation coefficient between fecal coliform and coliphage counts, predictions of the fecal coliforms may be made by enumeration of the phage.

  17. [Rapid Determination of Seven Fungicides in Citrus Fruits].

    PubMed

    Yoshioka, Naoki; Hayashi, Sachiko; Inada, Tadaaki

    2015-01-01

    A rapid and simple determination method of seven fungicides, thiabendazole (TBZ), pyrimethanil (PYR), o-phenylphenol (OPP), fludioxonil (FLD), azoxystrobin (AZX), imazalil (IMZ) and diphenyl (DP) in citrus fruits by LC-MS and HPLC-FL was developed. The seven fungicides were extracted with acetonitrile from citrus fruits and cleaned up with Z-Sep/C18 cartridges. The LC separation was performed on a phenyl-hexyl column with methanol-acetonitrile-10 mmol/L ammonium formate (10 : 35 : 55) as a mobile phase. The recoveries from citrus fruits fortified with the compounds at the MRLs and at 0.1 μg/g ranged from 85.4 to 106.3% and from 75.8 to 99.7%, respectively. The quantitation limits (S/N=10) were 0.03-0.07 μg/g.

  18. A rapid gel electrophoretic chip for serum cholesterol determination.

    PubMed

    Kaminikado, Kenta; Ikeda, Ryuzo; Idegami, Koutaro; Nagatani, Naoki; Vestergaard, Mun'delanji C; Saito, Masato; Tamiya, Eiichi

    2011-05-07

    We present a rapid gel electrophoretic chip, composed of 2.5% (w/v) acrylamide and 1% (w/v) agarose gel, for serum cholesterol determination using a photo lithography technique. After optimizations, we determined the lipoprotein concentration of standard serum using a conventional enzyme method. The serum was diluted, stained and loaded for 15 min onto the chip. After loading, the intensities of low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) bands separated at the chip were estimated using an image analyzer. The intensities of these bands corresponded to concentrations obtained from a standard enzyme-based method. The detected LDL-C and HDL-C concentrations were linear up to 146 mg dL(-1) and 53 mg dL(-1) respectively. Finally, we carried out the cholesterol analysis using real biological samples obtained from nine volunteers using our electrophoretic chip. The LDL-C and HDL-C levels detected using our chip correlated well with the results obtained using the conventional enzyme-based method r(2) = 0.98 and r(2) = 0.86 for LDL-C and HDL-C, respectively. Although our sample size is small and confined only to health volunteers, we have demonstrated that this proof-of-concept gel electrophoretic chip can determine lipoproteins, simultaneously.

  19. Determination of methemoglobin and carboxyhemoglobin in blood by rapid colorimetry.

    PubMed

    Matsuoka, T

    1997-11-01

    A sensitive and rapid colorimetry for determination of methemoglobin (MetHb) in hemolysate of the test blood was devised by measurement of absorbance at 563 nm, the isosbestic point of spectra of cyanomethemoglobin and oxyhemoglobin, at pH 6.8. MetHb was determined as the difference in absorption caused by cyanide in the absence of potassium ferricyanide divided by the difference in absorption caused by cyanide in the presence of the ferricyanide. Carboxyhemoglobin (COHb) in the blood was also estimated from the absorbance values of the hemolysates with or without potassium ferricyanide after the addition of cyanide. The method requires only 3 microliters of test blood and 10 min for determinations of MetHb and COHb in blood. Results obtained by the method were in satisfactory agreement with theoretical results for mixture of MetHb, COHb, and oxyhemoglobin. The method was compared with two other methods using 55 forensic blood samples containing various amounts of MetHb and COHb, and proved to be suitable for practical samples.

  20. Motion Planning for a Direct Metal Deposition Rapid Prototyping System

    SciTech Connect

    AMES,ARLO L.; HENSINGER,DAVID M.; KUHLMANN,JOEL L.

    1999-10-18

    A motion planning strategy was developed and implemented to generate motion control instructions from solid model data for controlling a robotically driven solid free-form fabrication process. The planning strategy was tested using a PUMA type robot arm integrated into a LENS{trademark} (Laser Engineered Net Shape) system. Previous systems relied on a series of x, y, and z stages, to provide a minimal coordinated motion control capability. This limited the complexity of geometries that could be constructed. With the coordinated motion provided by a robotic arm, the system can produce three dimensional parts by ''writing'' material onto any face of existing material. The motion planning strategy relied on solid model geometry evaluation and exploited robotic positioning flexibility to allow the construction of geometrically complex parts. The integration of the robotic manipulator into the LENS{trademark} system was tested by producing metal parts directly from CAD models.

  1. Rapid direct methods for enumeration of specific, active bacteria in water and biofilms

    NASA Technical Reports Server (NTRS)

    McFeters, G. A.; Pyle, B. H.; Lisle, J. T.; Broadaway, S. C.

    1999-01-01

    Conventional methods for detecting indicator and pathogenic bacteria in water may underestimate the actual population due to sublethal environmental injury, inability of the target bacteria to take up nutrients and other physiological factors which reduce bacterial culturability. Rapid and direct methods are needed to more accurately detect and enumerate active bacteria. Such a methodological advance would provide greater sensitivity in assessing the microbiological safety of water and food. The principle goal of this presentation is to describe novel approaches we have formulated for the rapid and simultaneous detection of bacteria plus the determination of their physiological activity in water and other environmental samples. The present version of our method involves the concentration of organisms by membrane filtration or immunomagnetic separation and combines an intracellular fluorochrome (CTC) for assessment of respiratory activity plus fluorescent-labelled antibody detection of specific bacteria. This approach has also been successfully used to demonstrate spatial and temporal heterogeneities of physiological activities in biofilms when coupled with cryosectioning. Candidate physiological stains include those capable of determining respiratory activity, membrane potential, membrane integrity, growth rate and cellular enzymatic activities. Results obtained thus far indicate that immunomagnetic separation can provide a high degree of sensitivity in the recovery of seeded target bacteria (Escherichia coli O157:H7) in water and hamburger. The captured and stained target bacteria are then enumerated by either conventional fluorescence microscopy or ChemScan(R), a new instrument that is very sensitive and rapid. The ChemScan(R) laser scanning instrument (Chemunex, Paris, France) provides the detection of individual fluorescently labelled bacterial cells using three emission channels in less than 5 min. A high degree of correlation has been demonstrated between

  2. Rapid direct methods for enumeration of specific, active bacteria in water and biofilms

    NASA Technical Reports Server (NTRS)

    McFeters, G. A.; Pyle, B. H.; Lisle, J. T.; Broadaway, S. C.

    1999-01-01

    Conventional methods for detecting indicator and pathogenic bacteria in water may underestimate the actual population due to sublethal environmental injury, inability of the target bacteria to take up nutrients and other physiological factors which reduce bacterial culturability. Rapid and direct methods are needed to more accurately detect and enumerate active bacteria. Such a methodological advance would provide greater sensitivity in assessing the microbiological safety of water and food. The principle goal of this presentation is to describe novel approaches we have formulated for the rapid and simultaneous detection of bacteria plus the determination of their physiological activity in water and other environmental samples. The present version of our method involves the concentration of organisms by membrane filtration or immunomagnetic separation and combines an intracellular fluorochrome (CTC) for assessment of respiratory activity plus fluorescent-labelled antibody detection of specific bacteria. This approach has also been successfully used to demonstrate spatial and temporal heterogeneities of physiological activities in biofilms when coupled with cryosectioning. Candidate physiological stains include those capable of determining respiratory activity, membrane potential, membrane integrity, growth rate and cellular enzymatic activities. Results obtained thus far indicate that immunomagnetic separation can provide a high degree of sensitivity in the recovery of seeded target bacteria (Escherichia coli O157:H7) in water and hamburger. The captured and stained target bacteria are then enumerated by either conventional fluorescence microscopy or ChemScan(R), a new instrument that is very sensitive and rapid. The ChemScan(R) laser scanning instrument (Chemunex, Paris, France) provides the detection of individual fluorescently labelled bacterial cells using three emission channels in less than 5 min. A high degree of correlation has been demonstrated between

  3. Rapid screening of triazines and quantitative determination in drinking water.

    PubMed

    Hamada, Mazen; Wintersteiger, Reinhold

    2002-01-01

    A sensitive, rapid and inexpensive analysis method has been developed for the triazines most frequently used in Palestine; the method includes fluorodensitometric screening and densitometric determination of the individual substances. Terbutryn as a model substance was derivatized with dansyl chloride in sodium hydrogen-carbonate or phosphate buffer solution to yield a green-blue fluorescent compound. Derivatization occurred at 120 degrees C within maximum of 10-min reaction time. The fluorescent compound formed was separated from excess reagent and other by-products on silica gel TLC plates and was then determined fluorodensitometrically. A linearity range between 20 and 1200 pg/spot was achieved. The method was also applied to other triazine herbicides such as ametryn, atrazine, propazine, terbuthylazine and simazine. Drinking water samples spiked with triazines were extracted using RP-C18 polar plus cartridges, and the extract could be then dansylated as a total. Recoveries were between 88% and 95%; the detection limit was 10 pg/spot and could be further improved to 2 pg/spot by a dipping solution. For quantification, each of the six triazines can be separated on one of three different stationary phases after solid phase extraction and measured densitometrically. The LOD for each individual triazine was 100 ng/l.

  4. Rapid determination of enantiomeric excess: a focus on optical approaches.

    PubMed

    Leung, Diana; Kang, Sung Ok; Anslyn, Eric V

    2012-01-07

    High-throughput screening (HTS) methods are becoming increasingly essential in discovering chiral catalysts or auxiliaries for asymmetric transformations due to the advent of parallel synthesis and combinatorial chemistry. Both parallel synthesis and combinatorial chemistry can lead to the exploration of a range of structural candidates and reaction conditions as a means to obtain the highest enantiomeric excess (ee) of a desired transformation. One current bottleneck in these approaches to asymmetric reactions is the determination of ee, which has led researchers to explore a wide range of HTS techniques. To be truly high-throughput, it has been proposed that a technique that can analyse a thousand or more samples per day is needed. Many of the current approaches to this goal are based on optical methods because they allow for a rapid determination of ee due to quick data collection and their parallel analysis capabilities. In this critical review these techniques are reviewed with a discussion of their respective advantages and drawbacks, and with a contrast to chromatographic methods (180 references).

  5. Rapid determination of alpha emitters using Actinide resin.

    PubMed

    Navarro, N; Rodriguez, L; Alvarez, A; Sancho, C

    2004-01-01

    The European Commission has recently published the recommended radiological protection criteria for the clearance of building and building rubble from the dismantling of nuclear installations. Radionuclide specific clearance levels for actinides are very low (between 0.1 and 1 Bq g(-1)). The prevalence of natural radionuclides in rubble materials makes the verification of these levels by direct alpha counting impossible. The capability of Actinide resin (Eichrom Industries, Inc.) for extracting plutonium and americium from rubble samples has been tested in this work. Besides a strong affinity for actinides in the tri, tetra and hexavalent oxidation states, this extraction chromatographic resin presents an easy recovery of absorbed radionuclides. The retention capability was evaluated on rubble samples spiked with certified radionuclide standards (239Pu and 241Am). Samples were leached with nitric acid, passed through a chromatographic column containing the resin and the elution fraction was measured by LSC. Actinide retention varies from 60% to 80%. Based on these results, a rapid method for the verification of clearance levels for actinides in rubble samples is proposed.

  6. [Rapid determination of beet sugar content using near infrared spectroscopy].

    PubMed

    Yang, Yong; Ren, Jian; Zheng, Xi-Qun; Zhao, Li-Ying; Li, Mao-Mao

    2014-10-01

    In order to classify and set different prices on basis of difference of beet sugar content in the acquisition process and promote the development of beet sugar industry healthily, a fast, nondestructive, accurate method to detect sugar content of beet was determined by applying near infrared spectroscopy technology. Eight hundred twenty samples from 28 representative varieties of beet were collected as calibration set and 70 samples were chosen as prediction set. Then near infrared spectra of calibration set samples were collected by scanning, effective information was extracted from NIR spectroscopy, and the original spectroscopy data was optimized by data preprocessing methods appropriately. Then partial least square(PLS)regression was used to establish beet sugar quantitative prediction mathematical model. The performances of the models were evaluated by the root mean square of cross-validation (RMSECV), the coefficient of determination (R2) of the calibration model and the standard error of prediction (SEP), and the predicted results of these models were compared. Results show that the established mathematical model by using first derivative (FD) and standard normal variate transformation (SNV) coupled with partial least squares has good predictive ability. The R2 of calibration models of sugar content of beet is 0.908 3, and the RMSECV is 0.376 7. Using this model to forecast the prediction set including 70 samples, the correlation coefficient is 0.921 4 between predicted values and measured values, and the standard error of prediction (SEP) is 0.439, without significant difference (p > 0.05) between predicted values and measured values. These results demonstrated that NIRS can take advantage of simple, rapid, nondestructive and environmental detection method and could be applied to predict beet sugar content. This model owned high accuracy and can meet the precision need of determination of beet sugar content. This detection method could be used to classify

  7. Online mutability of step direction during rapid stepping reactions evoked by postural perturbation.

    PubMed

    Tripp, Bryan P; McIlroy, William E; Maki, Brian E

    2004-03-01

    Stepping reactions are often triggered rapidly in response to loss of balance. It has been unclear whether spatial step parameters are defined at time of step-initiation or whether they can be modulated online, during step execution, in response to sensory feedback about the evolving state of instability. This study explored the capacity to actively alter step direction subsequent to step initiation in six healthy young-adult subjects. To elicit forward-step reactions, subjects were released suddenly from a tethered forward lean. A second perturbation (medio-lateral support-surface translation) was applied at lags of 0-200 ms. Active reaction to the second perturbation was determined primarily through analysis of swing-leg hip-abductor activation. In addition, to gauge the biomechanical consequence of the changes in muscle activation, we compared the measured medio-lateral swing-foot displacement to that predicted by a simple passive mechanical model. Perturbations at 0-100 ms lag evoked active medio-lateral swing-foot deviation, allowing balance to be recovered with a single step. However, when the second perturbation occurred near foot-off (200-ms lag), there was no evidence of active alteration of step direction and subjects typically required additional steps to recover balance. The results suggest that step direction can be reparameterized during early stages of stepping reactions, but that step direction was not actively modulated in response to perturbation arising near start of swing phase.

  8. Procedure for rapid determination of nickel, cobalt, and chromium in airborne particulate samples

    NASA Technical Reports Server (NTRS)

    Davis, W. F.; Graab, J. W.

    1972-01-01

    A rapid, selective procedure for the determination of 1 to 20 micrograms of nickel, chromium, and cobalt in airborne particulates is described. The method utilizes the combined techniques of low temperature ashing and atomic absorption spectroscopy. The airborne particulates are collected on analytical filter paper. The filter papers are ashed, and the residues are dissolved in hydrochloric acid. Nickel, chromium, and cobalt are determined directly with good precision and accuracy by means of atomic absorption. The effects of flame type, burner height, slit width, and lamp current on the atomic absorption measurements are reported.

  9. Rapid method for proline determination in grape juice and wine.

    PubMed

    Long, Danfeng; Wilkinson, Kerry L; Poole, Kate; Taylor, Dennis K; Warren, Tristan; Astorga, Alejandra M; Jiranek, Vladimir

    2012-05-02

    Proline is typically the most abundant amino acid present in grape juice and wine. The amount present is influenced by viticultural and winemaking factors and can be of diagnostic importance. A method for rapid routine quantitation of proline would therefore be of benefit for wine researchers and the industry in general. Colorimetric determination utilizing isatin as a derivatizing agent has previously been applied to plant extracts, biological fluids, and protein hydrolysates. In the current study, this method has been successfully adapted to grape juice and wine and proved to be sensitive to milligram per liter amounts of proline. At sugar concentrations above 60 g/L, interference from the isatin-proline reaction was observed, such that proline concentrations were considerably underestimated in grape juice and dessert wine. However, the method was robust for the analysis of fermentation samples and table wines. Results were within ±10% agreement with data generated from typical HPLC-based analyses. The isatin method is therefore considered suitable for the routine analysis required to support research into the utilization or release of proline by yeast during fermentation.

  10. Naked-eye sensor for rapid determination of mercury ion.

    PubMed

    Liu, Jing; Wu, Dapeng; Yan, Xiaohui; Guan, Yafeng

    2013-11-15

    A naked-eye paper sensor for rapid determination of trace mercury ion in water samples was designed and demonstrated. The mercury-sensing rhodamine B thiolactone was immobilized in silica matrices and the silica matrices were impregnated firmly and uniformly in the filter paper. As water samples flow through the filter paper, the membrane color will change from white to purple red, which could be observed obviously with naked eye, when concentration of mercury ions equals to or exceeds 10nM, the maximum residue level in drinking water recommended by U.S. EPA. The color change can also be recorded by a flatbed scanner and then digitized, reducing the detection limit of Hg(2+) down to 1.2 nM. Moreover, this method is extremely specific for Hg(2+) and shows a high tolerance ratio of interferent coexisting ions. The presence of Na(+) (2 mM), K(+) (2 mM), Fe(3+) (0.1 mM), Zn(2+) (0.1 mM), Mg(2+) (0.1 mM), Ni(2+) (50 μM), Co(2+) (50 μM), Cd(2+) (50 μM), Pb(2+) (50 μM), Cu(2+) (50 μM) and Ag(+) (3.5 μM) did not interfere with the detection of Hg(2+) (25 nM). Finally, the present method was applied in the detection of Hg(2+) in mineral water, tap water and pond water.

  11. Rapid determination of serum myoglobin with a routine chemistry analyzer.

    PubMed

    Bakker, A J; Boymans, D A; Dijkstra, D; Gorgels, J P; Lerk, R

    1993-04-01

    A turbidimetric immunoassay system (Turbitime system, Behringwerke AG) allows rapid determination of myoglobin in serum. We adapted the reagents for this myoglobin assay (Turbiquant myoglobin) for use with a Hitachi 717 analyzer. No high-dose hook effect was observed up to 15,000 micrograms/L. Interassay CVs were 4.6% (mean = 72.0 micrograms/L; n = 9) and 2.5% (mean = 365.6 micrograms/L; n = 11). The calibration curve was stable for at least 1 month. Hemolysis did not interfere, and turbidity from lipemia interfered only when absorbance exceeded 2.0 A. Results of this method (y) correlated well with those by the Turbitime method (y = 1.256x - 44.1 micrograms/L; n = 91; r = 0.991) and by a commercially available radioimmunoassay (Byk-Sangtec; y = 0.739x - 42.2 micrograms/L; n = 94; r = 0.991). The upper limit (95th percentile) of the reference interval for myoglobin was estimated at 57.9 micrograms/L. The positive predictive value for results of myoglobin at admission was 89% with this upper reference limit and 99% with 100 micrograms/L, whereas the negative predictive value was about 60% for both limits.

  12. Rapid determination of total trihalomethanes index in drinking water.

    PubMed

    Serrano, A; Gallego, M

    2007-06-22

    A method for the rapid determination of total trihalomethanes (THMs) index in drinking water has been developed by using a headspace-mass spectrometry (HS-MS) system and partial least squares (PLS) multivariate regression approach. Due to the presence of residual amounts of chlorine and organic matter in the drinking water, the use of a quenching reagent in order to avoid THM generation during the sample manipulation is necessary. The optimization experiments revealed that ascorbic acid was the best quenching reagent compared with sodium thiosulfate and ammonium sulfate. The use of a classification chemometric technique as soft independent modeling of class analogy before the PLS regression improved the results obtained in the prediction of the total THMs index, lowering the relative standard error of prediction (RSEP) from 11.4% to lower than 6.0%. The results obtained by the proposed HS-MS method were compared with those provided by a conventional chromatographic method after analyzing 20 real drinking water samples. A good agreement in the results was observed and no systematic differences were found, which corroborates the good performance of the proposed method.

  13. Direct determination of diploid genome sequences

    PubMed Central

    Weisenfeld, Neil I.; Kumar, Vijay; Shah, Preyas; Church, Deanna M.; Jaffe, David B.

    2017-01-01

    Determining the genome sequence of an organism is challenging, yet fundamental to understanding its biology. Over the past decade, thousands of human genomes have been sequenced, contributing deeply to biomedical research. In the vast majority of cases, these have been analyzed by aligning sequence reads to a single reference genome, biasing the resulting analyses, and in general, failing to capture sequences novel to a given genome. Some de novo assemblies have been constructed free of reference bias, but nearly all were constructed by merging homologous loci into single “consensus” sequences, generally absent from nature. These assemblies do not correctly represent the diploid biology of an individual. In exactly two cases, true diploid de novo assemblies have been made, at great expense. One was generated using Sanger sequencing, and one using thousands of clone pools. Here, we demonstrate a straightforward and low-cost method for creating true diploid de novo assemblies. We make a single library from ∼1 ng of high molecular weight DNA, using the 10x Genomics microfluidic platform to partition the genome. We applied this technique to seven human samples, generating low-cost HiSeq X data, then assembled these using a new “pushbutton” algorithm, Supernova. Each computation took 2 d on a single server. Each yielded contigs longer than 100 kb, phase blocks longer than 2.5 Mb, and scaffolds longer than 15 Mb. Our method provides a scalable capability for determining the actual diploid genome sequence in a sample, opening the door to new approaches in genomic biology and medicine. PMID:28381613

  14. Rapid surface colony counts determination with three new miniaturised techniques.

    PubMed

    Malik, K A

    1977-01-01

    Three different miniaturised methods for the rapid surface viable counting are described. The methods were tried in parallel to seven different existing methods (Table 1) for viable counts and were found to be easier, quicker and insome cases more accurate. The techniques require about 10% of the material and time needed for conventional spread-plates method and the results were in no way inferior to that (Table 1 and 2). Mini agar discs were cut aseptically with an especially designed stainless steel agar disc cutter (25 mm internal and 28 mm external diameter, Fig. 1b) or with a test tube of similar diameter. The area of the resulted mini-agar-disc of 25 mm diameter was kept such (about 1/10th of the normal plate) that the ratio of the colony-bearing area to the inoculm remained the same as on big plates in spread-plate-method (Table 2). In normal Petri dishes (about 90 mm diameter) up to seven mini agar discs were possible to cut. Each small agar disc was seperated from the other mini-disc by a distance of at least 6 mm (Fig. 1a). The empty place around the disc was still enlarged during over drying of the plates and during incubation. This created complete isolation from the neighbouring disc. For micro-determination of surface viable counts 10 micronl from each dilution was delivered on a well-dired mini-disc with a piston micropipette. The inoculm was immediately spread on the whole mini-disc with a specially designed flame sterilizable platinum-Mini-spreader (Fig. 2a). No spinning of the plate was needed. Alternatively the dropping pipette and spreader was replaced by a calibrated platinum wire Loop-spreader (Fig. 2b). A loop of 3 mm internal diameter made from a platinum-iridium wire of 0.75 mm thickness proved most useful and carried a drop of 10 micronl. Differences especially in surface tension of various diluting fluids did not influence to drop of this size and no recalibration was needed for water and nutrient broth. The loop was further shaped to

  15. Direct Determination of Nonmetals in Solution with Atomic Spectrometry.

    ERIC Educational Resources Information Center

    McGregor, David A.; And Others

    1988-01-01

    Addresses solution nonmetal determinations on a fundamental level. Characterizes research in this area of chemical instrumentation. Discusses the fundamental limitations of nonmetal atomic spectrometry, the status of nonmetals and atomic spectroscopic techniques, and current directions in solution nonmetal determinations. (CW)

  16. Direct Observation of Extremely Rapid Oligomer Formation Via OH Radical Initiated Oxidation of Organic Aerosols

    NASA Astrophysics Data System (ADS)

    Smith, J. D.; Goaguen, E.; Ahmed, M.; Leone, S. R.; Wilson, K. R.

    2007-05-01

    Ambient aerosols are known to play a significant role in a variety of atmospheric processes such as direct and indirect effects on radiative forcing. Chemical composition can be an important factor in determining the magnitude of these effects (optical density, hygroscopicity, etc.) (1). However, a major fraction(80 - 90%) of organic aerosols can not be resolved on a molecular level. Recent identification of high mass oligomeric species as a major component in laboratory and ambient organic aerosols has received much attention due to the possibility that these species may account for much of the unknown organic mass in ambient aerosols (2, 3). Although, a few mechanisms have been proposed, the origin and formation processes of these compounds remain largely unknown. Here we provide strong evidence for a previously unidentified mechanism of extremely rapid oligomer formation, via OH radical initiated oxidation of organic aerosols. This process appears capable of converting a sizable fraction of an organic particle to higher mass oligomers within only a few hours of exposure to OH radicals at typical atmospheric concentrations. Furthermore, we have found that rapid volatilization, followed by oligomerization, is also important for specific reaction systems, and can lead to the loss of a large fraction (> 60%) of a particle within 15 minutes of exposure to atmospheric OH. We propose that such a rapid processing (oligomerization and volatilization) is possible due to a radical chain reaction which quickly propagates throughout the entire particle and is only initiated by the surface OH reaction. References 1. J. H. Seinfeld, S. N. Pandis, Atmospheric Chemistry and Physics (Wiley, New York, 1998). 2. M. Kalberer et al., Science 303, 1659 (2004). 3. V. Samburova et al., J Geophys Res-Atmos 110, D23210 (2005).

  17. RAPID METHOD FOR DETERMINATION OF RADIOSTRONTIUM IN EMERGENCY MILK SAMPLES

    SciTech Connect

    Maxwell, S.; Culligan, B.

    2008-07-17

    A new rapid separation method for radiostrontium in emergency milk samples was developed at the Savannah River Site (SRS) Environmental Bioassay Laboratory (Aiken, SC, USA) that will allow rapid separation and measurement of Sr-90 within 8 hours. The new method uses calcium phosphate precipitation, nitric acid dissolution of the precipitate to coagulate residual fat/proteins and a rapid strontium separation using Sr Resin (Eichrom Technologies, Darien, IL, USA) with vacuum-assisted flow rates. The method is much faster than previous method that use calcination or cation exchange pretreatment, has excellent chemical recovery, and effectively removes beta interferences. When a 100 ml sample aliquot is used, the method has a detection limit of 0.5 Bq/L, well below generic emergency action levels.

  18. Rapid process development of chromatographic process using direct analysis in real time mass spectrometry as a process analytical technology tool.

    PubMed

    Yan, Binjun; Chen, Teng; Xu, Zhilin; Qu, Haibin

    2014-06-01

    The concept of quality by design (QbD) is widely applied in the process development of pharmaceuticals. However, the additional cost and time have caused some resistance about QbD implementation. To show a possible solution, this work proposed a rapid process development method, which used direct analysis in real time mass spectrometry (DART-MS) as a process analytical technology (PAT) tool for studying the chromatographic process of Ginkgo biloba L., as an example. The breakthrough curves were fast determined by DART-MS at-line. A high correlation coefficient of 0.9520 was found between the concentrations of ginkgolide A determined by DART-MS and HPLC. Based on the PAT tool, the impacts of process parameters on the adsorption capacity were discovered rapidly, which showed a decreased adsorption capacity with the increase of the flow rate. This work has shown the feasibility and advantages of integrating PAT into QbD implementation for rapid process development.

  19. Determination of rapid chlorination rate constants by a stopped-flow spectrophotometric competition kinetics method.

    PubMed

    Song, Dean; Liu, Huijuan; Qiang, Zhimin; Qu, Jiuhui

    2014-05-15

    Free chlorine is extensively used for water and wastewater disinfection nowadays. However, it still remains a big challenge to determine the rate constants of rapid chlorination reactions although competition kinetics and stopped-flow spectrophotometric (SFS) methods have been employed individually to investigate fast reaction kinetics. In this work, we proposed an SFS competition kinetics method to determine the rapid chlorination rate constants by using a common colorimetric reagent, N,N-diethyl-p-phenylenediamine (DPD), as a reference probe. A kinetic equation was first derived to estimate the reaction rate constant of DPD towards chlorine under a given pH and temperature condition. Then, on that basis, an SFS competition kinetics method was proposed to determine directly the chlorination rate constants of several representative compounds including tetracycline, ammonia, and four α-amino acids. Although Cl2O is more reactive than HOCl, its contribution to the overall chlorination kinetics of the test compounds could be neglected in this study. Finally, the developed method was validated through comparing the experimentally measured chlorination rate constants of the selected compounds with those obtained or calculated from literature and analyzing with Taft's correlation as well. This study demonstrates that the SFS competition kinetics method can measure the chlorination rate constants of a test compound rapidly and accurately.

  20. An Extended Multilocus Sequence Typing (MLST) Scheme for Rapid Direct Typing of Leptospira from Clinical Samples

    PubMed Central

    Menezes, Angela; Woods, Kate; Chanthongthip, Anisone; Dittrich, Sabine; Opoku-Boateng, Agatha; Kimuli, Maimuna; Chalker, Victoria

    2016-01-01

    Background Rapid typing of Leptospira is currently impaired by requiring time consuming culture of leptospires. The objective of this study was to develop an assay that provides multilocus sequence typing (MLST) data direct from patient specimens while minimising costs for subsequent sequencing. Methodology and Findings An existing PCR based MLST scheme was modified by designing nested primers including anchors for facilitated subsequent sequencing. The assay was applied to various specimen types from patients diagnosed with leptospirosis between 2014 and 2015 in the United Kingdom (UK) and the Lao Peoples Democratic Republic (Lao PDR). Of 44 clinical samples (23 serum, 6 whole blood, 3 buffy coat, 12 urine) PCR positive for pathogenic Leptospira spp. at least one allele was amplified in 22 samples (50%) and used for phylogenetic inference. Full allelic profiles were obtained from ten specimens, representing all sample types (23%). No nonspecific amplicons were observed in any of the samples. Of twelve PCR positive urine specimens three gave full allelic profiles (25%) and two a partial profile. Phylogenetic analysis allowed for species assignment. The predominant species detected was L. interrogans (10/14 and 7/8 from UK and Lao PDR, respectively). All other species were detected in samples from only one country (Lao PDR: L. borgpetersenii [1/8]; UK: L. kirschneri [1/14], L. santarosai [1/14], L. weilii [2/14]). Conclusion Typing information of pathogenic Leptospira spp. was obtained directly from a variety of clinical samples using a modified MLST assay. This assay negates the need for time-consuming culture of Leptospira prior to typing and will be of use both in surveillance, as single alleles enable species determination, and outbreaks for the rapid identification of clusters. PMID:27654037

  1. Rapid determination of ethanol in fermentation liquor by full evaporation headspace gas chromatography.

    PubMed

    Li, Hailong; Chai, Xin-Sheng; Deng, Yulin; Zhan, Huaiyu; Fu, Shiyu

    2009-01-02

    This paper reports a full evaporation (FE) headspace gas chromatographic (GC) method for rapid determination of ethanol in fermentation liquor. The data show that ethanol in the fermentation liquor was transferred to the vapor phase (headspace) almost completely within 3 min at a temperature of 105 degrees C when a very small volume (< 50 microL) of sample was directly added to a sealed headspace sample vial (20 mL). The ethanol in the vapor phase was then measured by headspace GC using a flame ionization detector. The results show that the present method has an excellent measurement precision (RSD=1.62%) and accuracy (recovery=98.1 (+/-1.76%)) for the ethanol quantification in fermentation liquors. The method requires no sample pretreatment and is very simple and rapid.

  2. A rapid reproducible test for determining rabies neutralizing antibody*

    PubMed Central

    Smith, Jean S.; Yager, Pamela A.; Baer, George M.

    1973-01-01

    Rabies neutralizing antibody levels in human and animal sera were tested by a rapid fluorescent focus inhibition technique, in which BHK-21 cells were infected with tissue-culture-adapted rabiesvirus. The results, obtained in 24 hours, were comparable with those of the standard mouse neutralization test. ImagesFig. 1Fig. 2Fig. 3 PMID:4544144

  3. Initial neighborhood biases and the quality of motion stimulation jointly influence the rapid emergence of direction preference in visual cortex

    PubMed Central

    Van Hooser, Stephen D.; Li, Ye; Christensson, Maria; Smith, Gordon B.; White, Leonard E.; Fitzpatrick, David

    2012-01-01

    Visual experience plays a critical role in the development of direction selective responses in ferret visual cortex. In visually naïve animals, presentation of bidirectional `training' stimulus induces rapid increases in the direction selective responses of single neurons that can be predicted by small but significant direction biases that are present in vivo 2-photon imaging of calcium signals to further explore the contribution of visual experience to the emergence of direction selective responses in ferret visual cortex. The first set of experiments was designed to determine whether visual experience is required for the development of the initial neighborhood bias. In animals that were dark-reared until the time of eye-opening, we found that individual neurons exhibited weak direction selective responses accompanied by a reduced but statistically significant neighborhood bias, indicating that both features arise without the need for visual experience. The second set of experiments employed a unidirectional training stimulus to assess the relative roles of the neighborhood bias and visual experience in determining the direction preference that cortical neurons acquire during direction training. We found that neurons became more responsive to the trained direction even when they were located in regions of the cortex with an initial neighborhood bias for the direction opposite the training stimulus. Taken together, these results suggest an adaptive developmental strategy for the elaboration of direction selective responses, one in which experience-independent mechanisms provide a symmetry-breaking seed for the instructive effects of visual experience. PMID:22623671

  4. Rapid growth and formation mechanism of ultrafine structural oxide eutectic ceramics by laser direct forming

    NASA Astrophysics Data System (ADS)

    Su, H. J.; Zhang, J.; Liu, L.; Eckert, J.; Fu, H. Z.

    2011-11-01

    Melt growth of oxide eutectic is an important and fast-growing research topic in the fields of both applied physics and materials science. Rapid one-step fabrication of melt-grown oxide ceramics with large size is developed using laser direct forming. The near 100% density of Al2O3/YAG eutectic ceramic in situ composite free of pore and cracks is rapidly melted/solidified directly from Al2O3-Y2O3 powder without any preforming or sintering. Uniform three-dimensional network of ultrafine nanostructured eutectic microstructure is obtained. The direct experimental evidence of faceted-nonfaceted eutectic transition at high growth rate is presented and the physical model of the microstructural formation based on atom cluster elementary process is proposed. This technology provides a rapid freeform fabrication of high-performance complex shaped ceramics for various applications.

  5. Rapid distortion analysis and direct simulation of compressible homogeneous turbulence at finite Mach number

    NASA Technical Reports Server (NTRS)

    Cambon, C.; Coleman, G. N.; Mansour, N. N.

    1992-01-01

    The effect of rapid mean compression on compressible turbulence at a range of turbulent Mach numbers is investigated. Rapid distortion theory (RDT) and direct numerical simulation results for the case of axial (one-dimensional) compression are used to illustrate the existence of two distinct rapid compression regimes. These regimes are set by the relationships between the timescales of the mean distortion, the turbulence, and the speed of sound. A general RDT formulation is developed and is proposed as a means of improving turbulence models for compressible flows.

  6. Portable centrifugal analyzer for the determination of rapid reaction kinetics

    SciTech Connect

    Bostick, W.D.; Bauer, M.L.; McCracken, R.; Mrochek, J.E.

    1980-02-01

    A portable centrifugal analyzer prototype is capable of rapidly initiating reactions and monitoring 17 optical channels as they rotate past a stationary photodetector. An advanced rotor drive permits transfer of discretely loaded sample and reagent into a cuvette within 60 ms. Various rotor designs have been employed to ensure effieicnt mixing concurrent with solution transfer, thus permitting absorbance or luminescence measurements to be made almost immediately after solution contract. Dye-dillution studies have been used to investigate transfer and mixing efficiencies. Rotor designs with parallel access for sample and reagent into the cuvette were found to promote efficient mixing during liquid transfer. The hypochlorite-luminol chemiluminescent reaction served to demonstrate the utility of the system for performing rapid kinetic analyses. Appropriate adjustment of reaction conditions allows first-order reaction half-lives as short as 0.04 s to be measured. 13 figures, 3 tables.

  7. Rapid determination of color additives, using the C18 cartridge.

    PubMed

    Young, M L

    1984-01-01

    A reliable method has been developed for the rapid separation and identification of the 7 permitted FD&C dyes (Red Nos. 3 and 40; Blue Nos. 1 and 2; Yellow Nos. 5 and 6; Green No. 3) and the recently banned FD&C Red No. 2 in foods. The colors are separated by using the C18 cartridge, and their identity is confirmed by spectrophotometry.

  8. Rapid determination of antibiotic resistance in E. coli using dielectrophoresis

    NASA Astrophysics Data System (ADS)

    Hoettges, Kai F.; Dale, Jeremy W.; Hughes, Michael P.

    2007-09-01

    In recent years, infections due to antibiotic-resistant strains of bacteria such as methillicin-resistant Staphylococcus aureus and ciprofloxacin-resistant Escherichia coli are on the rise, and with them the demand for rapid antibiotic testing is also rising. Conventional tests, such as disc diffusion testing, require a primary sample to be tested in the presence of a number of antibiotics to verify which antibiotics suppress growth, which take approximately 24 h to complete and potentially place the patient at severe risk. In this paper we describe the use of dielectrophoresis as a rapid marker of cell death, by detecting changes in the electrophysiology of the cell caused by the administration of an antibiotic. In contrast to other markers, the electrophysiology of the cell changes rapidly during cell death allowing live cells to be distinguished from dead (or dying) cells without the need for culturing. Using polymyxin B as an example antibiotic, our studies indicate that significant changes in cell characteristics can be observed as soon as 1 h passes after isolating a culture from nutrient broth.

  9. Note: Non-invasive optical method for rapid determination of alignment degree of oriented nanofibrous layers

    SciTech Connect

    Pokorny, M.; Rebicek, J.; Klemes, J.; Kotzianova, A.; Velebny, V.

    2015-10-15

    This paper presents a rapid non-destructive method that provides information on the anisotropic internal structure of nanofibrous layers. A laser beam of a wavelength of 632.8 nm is directed at and passes through a nanofibrous layer prepared by electrostatic spinning. Information about the structural arrangement of nanofibers in the layer is directly visible in the form of a diffraction image formed on a projection screen or obtained from measured intensities of the laser beam passing through the sample which are determined by the dependency of the angle of the main direction of polarization of the laser beam on the axis of alignment of nanofibers in the sample. Both optical methods were verified on Polyvinyl alcohol (PVA) nanofibrous layers (fiber diameter of 470 nm) with random, single-axis aligned and crossed structures. The obtained results match the results of commonly used methods which apply the analysis of electron microscope images. The presented simple method not only allows samples to be analysed much more rapidly and without damaging them but it also makes possible the analysis of much larger areas, up to several square millimetres, at the same time.

  10. Rapid determination of oxygen saturation and vascularity for cancer detection.

    PubMed

    Hu, Fangyao; Vishwanath, Karthik; Lo, Justin; Erkanli, Alaattin; Mulvey, Christine; Lee, Walter T; Ramanujam, Nimmi

    2013-01-01

    A rapid heuristic ratiometric analysis for estimating tissue hemoglobin concentration and oxygen saturation from measured tissue diffuse reflectance spectra is presented. The analysis was validated in tissue-mimicking phantoms and applied to clinical measurements in head and neck, cervical and breast tissues. The analysis works in two steps. First, a linear equation that translates the ratio of the diffuse reflectance at 584 nm and 545 nm to estimate the tissue hemoglobin concentration using a Monte Carlo-based lookup table was developed. This equation is independent of tissue scattering and oxygen saturation. Second, the oxygen saturation was estimated using non-linear logistic equations that translate the ratio of the diffuse reflectance spectra at 539 nm to 545 nm into the tissue oxygen saturation. Correlations coefficients of 0.89 (0.86), 0.77 (0.71) and 0.69 (0.43) were obtained for the tissue hemoglobin concentration (oxygen saturation) values extracted using the full spectral Monte Carlo and the ratiometric analysis, for clinical measurements in head and neck, breast and cervical tissues, respectively. The ratiometric analysis was more than 4000 times faster than the inverse Monte Carlo analysis for estimating tissue hemoglobin concentration and oxygen saturation in simulated phantom experiments. In addition, the discriminatory power of the two analyses was similar. These results show the potential of such empirical tools to rapidly estimate tissue hemoglobin in real-time spectral imaging applications.

  11. Rapid Determination of Oxygen Saturation and Vascularity for Cancer Detection

    PubMed Central

    Hu, Fangyao; Vishwanath, Karthik; Lo, Justin; Erkanli, Alaattin; Mulvey, Christine; Lee, Walter T.; Ramanujam, Nimmi

    2013-01-01

    A rapid heuristic ratiometric analysis for estimating tissue hemoglobin concentration and oxygen saturation from measured tissue diffuse reflectance spectra is presented. The analysis was validated in tissue-mimicking phantoms and applied to clinical measurements in head and neck, cervical and breast tissues. The analysis works in two steps. First, a linear equation that translates the ratio of the diffuse reflectance at 584 nm and 545 nm to estimate the tissue hemoglobin concentration using a Monte Carlo-based lookup table was developed. This equation is independent of tissue scattering and oxygen saturation. Second, the oxygen saturation was estimated using non-linear logistic equations that translate the ratio of the diffuse reflectance spectra at 539 nm to 545 nm into the tissue oxygen saturation. Correlations coefficients of 0.89 (0.86), 0.77 (0.71) and 0.69 (0.43) were obtained for the tissue hemoglobin concentration (oxygen saturation) values extracted using the full spectral Monte Carlo and the ratiometric analysis, for clinical measurements in head and neck, breast and cervical tissues, respectively. The ratiometric analysis was more than 4000 times faster than the inverse Monte Carlo analysis for estimating tissue hemoglobin concentration and oxygen saturation in simulated phantom experiments. In addition, the discriminatory power of the two analyses was similar. These results show the potential of such empirical tools to rapidly estimate tissue hemoglobin in real-time spectral imaging applications. PMID:24358243

  12. Direct, Specific and Rapid Detection of Staphylococcal Proteins and Exotoxins Using a Multiplex Antibody Microarray

    PubMed Central

    Stieber, Bettina; Monecke, Stefan; Müller, Elke; Büchler, Joseph; Ehricht, Ralf

    2015-01-01

    Background S. aureus is a pathogen in humans and animals that harbors a wide variety of virulence factors and resistance genes. This bacterium can cause a wide range of mild to life-threatening diseases. In the latter case, fast diagnostic procedures are important. In routine diagnostic laboratories, several genotypic and phenotypic methods are available to identify S. aureus strains and determine their resistances. However, there is a demand for multiplex routine diagnostic tests to directly detect staphylococcal toxins and proteins. Methods In this study, an antibody microarray based assay was established and validated for the rapid detection of staphylococcal markers and exotoxins. The following targets were included: staphylococcal protein A, penicillin binding protein 2a, alpha- and beta-hemolysins, Panton Valentine leukocidin, toxic shock syndrome toxin, enterotoxins A and B as well as staphylokinase. All were detected simultaneously within a single experiment, starting from a clonal culture on standard media. The detection of bound proteins was performed using a new fluorescence reading device for microarrays. Results 110 reference strains and clinical isolates were analyzed using this assay, with a DNA microarray for genotypic characterization performed in parallel. The results showed a general high concordance of genotypic and phenotypic data. However, genotypic analysis found the hla gene present in all S. aureus isolates but its expression under given conditions depended on the clonal complex affiliation of the actual isolate. Conclusions The multiplex antibody assay described herein allowed a rapid and reliable detection of clinically relevant staphylococcal toxins as well as resistance- and species-specific markers. PMID:26624622

  13. Determination of the directive gain of antennas on the basis of field measurements in the near zone

    NASA Astrophysics Data System (ADS)

    Usin, V. A.; Anokhina, O. D.

    A method for determining antenna directive gain on the basis of near-field measurements on a cylindrical surface is described, and its practical implementation is discussed. The directive gain can be determined in two steps. Frist, rapid processing is carried out and information about the position of the directive-gain peak is obtained, and this information is then used to evaluate the directive gain in the total measurement cycle.

  14. Rapid determination of total benzalkonium chloride content in ophthalmic formulation.

    PubMed

    Labranche, Louis-Philippe; Dumont, Suzanne N; Levesque, Suzanne; Carrier, Alain

    2007-02-19

    A simple and rapid reversed-phase HPLC method was developed for routine analysis of total benzalkonium chloride in ophthalmic formulations. The analysis involves simple sample preparation using the mobile phase as the diluent. The method uses a Waters SymmetryShield RP-18 (75 mm x 4.6 mm, 3.5 microm particle size) column and a mobile phase consisting of a mixture of methanol-potassium phosphate (pH 3.0; 7.5 mM) (68:32, v/v). Using these conditions, three major homologs of the benzalkonium chloride (C(12), C(14) and C(16)) were separated in less then 7 min. Furthermore, recoveries ranging from 97% to 99% at three levels of the label claim of total benzalkonium chloride content were obtained for different ophthalmic formulations. Data supporting the development and validation of this method are presented.

  15. Estimation and modeling of direct rapid sand filtration for total fecal coliform removal from secondary clarifier effluents.

    PubMed

    Li, Yi; Yu, Jingjing; Liu, Zhigang; Ma, Tian

    2012-01-01

    The filtration of fecal coliform from a secondary clarifier effluent was investigated using direct rapid sand filters as tertiary wastewater treatment on a pilot scale. The effect of the flocculation dose, flow loading rate, and grain size on fecal coliform removal was determined. Direct rapid sand filters can remove 0.6-1.5 log-units of fecal coliform, depending on the loading rate and grain size distribution. Meanwhile, the flocculation dose has little effect on coliform removal, and increasing the loading rate and/or grain size decreases the bacteria removal efficiency. A model was then developed for the removal process. Bacteria elimination and inactivation both in the water phase and the sand bed can be described by first-order kinetics. Removal was successfully simulated at different loading rates and grain size distributions and compared with the data obtained using pilot-scale filters.

  16. Rapid Analysis of Microalgal Triacylglycerols with Direct-Infusion Mass Spectrometry

    SciTech Connect

    Christensen, Earl; Sudasinghe, Nilusha; Dandamudi, Kodanda Phani Raj; Sebag, Robert; Schaub, Tanner; Laurens, Lieve M. L.

    2015-09-01

    Cultivation of microalgae has the potential to provide lipid-derived feedstocks for conversion to liquid transportation fuels. Lipid extracts from microalgae are significantly more complex than those of traditional seed oils, and their composition changes significantly throughout the microalgal growth period. With three acyl side chains per molecule, triglycerides (TAGs) are an important fuel precursor, and the distribution of acyl chain composition for TAGs has a significant impact on fuel properties and processing. Therefore, determination of the distribution of microalgal TAG production is needed to assess the value of algal extracts designed for fuel production and to optimize strain, cultivation, and harvesting practices. Methods utilized for TAG speciation commonly involve complicated and time-consuming chromatographic techniques. Here we present a method for TAG speciation and quantification based on direct-infusion mass spectrometry, which provides rapid characterization of TAG profiles without chromatographic separation. Specifically, we utilize Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to provide a reference library of TAGs for the microalgae Nannochloropsis sp. that provides the basis for high-throughput TAG quantitation by time-of-flight mass spectrometry (TOF MS). In conclusion, we demonstrate the application of this novel approach for lipid characterization with respect to TAG compound distribution, which informs both immediate and future strain and process optimization strategies.

  17. Rapid Analysis of Microalgal Triacylglycerols with Direct-Infusion Mass Spectrometry

    DOE PAGES

    Christensen, Earl; Sudasinghe, Nilusha; Dandamudi, Kodanda Phani Raj; ...

    2015-09-01

    Cultivation of microalgae has the potential to provide lipid-derived feedstocks for conversion to liquid transportation fuels. Lipid extracts from microalgae are significantly more complex than those of traditional seed oils, and their composition changes significantly throughout the microalgal growth period. With three acyl side chains per molecule, triglycerides (TAGs) are an important fuel precursor, and the distribution of acyl chain composition for TAGs has a significant impact on fuel properties and processing. Therefore, determination of the distribution of microalgal TAG production is needed to assess the value of algal extracts designed for fuel production and to optimize strain, cultivation, andmore » harvesting practices. Methods utilized for TAG speciation commonly involve complicated and time-consuming chromatographic techniques. Here we present a method for TAG speciation and quantification based on direct-infusion mass spectrometry, which provides rapid characterization of TAG profiles without chromatographic separation. Specifically, we utilize Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to provide a reference library of TAGs for the microalgae Nannochloropsis sp. that provides the basis for high-throughput TAG quantitation by time-of-flight mass spectrometry (TOF MS). In conclusion, we demonstrate the application of this novel approach for lipid characterization with respect to TAG compound distribution, which informs both immediate and future strain and process optimization strategies.« less

  18. Measurement of impurities in plutonium metal by rapid ion exchange/direct current argon plasma spectrometry

    SciTech Connect

    Maxwell, S.L. III; Coleman, J.T.

    1989-01-01

    A rapid ion exchange/direct current argon plasma (DCAP) spectrometry method is now being applied at the Savannah River Site to provide faster, more reliable assay of key metallic impurities in plutonium metal. These measurements are essential for nuclear materials accountability and enhanced process control. Impurity assays must be performed to ensure that plutonium product specifications are met and to determine the 100% -- impurities plutonium assay used in shipper/receiver calculations. Separation of impurities from plutonium metal is required prior to measurement by spectral techniques since the complex emission spectra of plutonium interferes with the impurity emission lines. A modified commercial vacuum system is used to perform the ion exchange separation in a glovebox. Since column flow rates are 10--15 times that of conventional ion exchange, purification time is relatively short. Separation efficiency is maintained by using small particle resin. The DCAP method is faster and provides much better accuracy and precision than the previously used carrier distillation dc arc spectrographic technique. The DCAP instrument has a much greater linear dynamic range than dc arc, does not require plutonium matrix standards for instrument calibration, and requires much less space than a dc arc spectrograph. Sixteen key metallic impurities are routinely measured using the ion exchange/DCAP spectrometry method. 11 refs., 6 figs., 1 tab.

  19. A microfluidic chip for direct and rapid trapping of white blood cells from whole blood

    PubMed Central

    Chen, Jingdong; Chen, Di; Yuan, Tao; Xie, Yao; Chen, Xiang

    2013-01-01

    Blood analysis plays a major role in medical and science applications and white blood cells (WBCs) are an important target of analysis. We proposed an integrated microfluidic chip for direct and rapid trapping WBCs from whole blood. The microfluidic chip consists of two basic functional units: a winding channel to mix and arrays of two-layer trapping structures to trap WBCs. Red blood cells (RBCs) were eliminated through moving the winding channel and then WBCs were trapped by the arrays of trapping structures. We fabricated the PDMS (polydimethylsiloxane) chip using soft lithography and determined the critical flow velocities of tartrazine and brilliant blue water mixing and whole blood and red blood cell lysis buffer mixing in the winding channel. They are 0.25 μl/min and 0.05 μl/min, respectively. The critical flow velocity of the whole blood and red blood cell lysis buffer is lower due to larger volume of the RBCs and higher kinematic viscosity of the whole blood. The time taken for complete lysis of whole blood was about 85 s under the flow velocity 0.05 μl/min. The RBCs were lysed completely by mixing and the WBCs were trapped by the trapping structures. The chip trapped about 2.0 × 103 from 3.3 × 103 WBCs. PMID:24404026

  20. A microfluidic chip for direct and rapid trapping of white blood cells from whole blood.

    PubMed

    Chen, Jingdong; Chen, Di; Yuan, Tao; Xie, Yao; Chen, Xiang

    2013-01-01

    Blood analysis plays a major role in medical and science applications and white blood cells (WBCs) are an important target of analysis. We proposed an integrated microfluidic chip for direct and rapid trapping WBCs from whole blood. The microfluidic chip consists of two basic functional units: a winding channel to mix and arrays of two-layer trapping structures to trap WBCs. Red blood cells (RBCs) were eliminated through moving the winding channel and then WBCs were trapped by the arrays of trapping structures. We fabricated the PDMS (polydimethylsiloxane) chip using soft lithography and determined the critical flow velocities of tartrazine and brilliant blue water mixing and whole blood and red blood cell lysis buffer mixing in the winding channel. They are 0.25 μl/min and 0.05 μl/min, respectively. The critical flow velocity of the whole blood and red blood cell lysis buffer is lower due to larger volume of the RBCs and higher kinematic viscosity of the whole blood. The time taken for complete lysis of whole blood was about 85 s under the flow velocity 0.05 μl/min. The RBCs were lysed completely by mixing and the WBCs were trapped by the trapping structures. The chip trapped about 2.0 × 10(3) from 3.3 × 10(3) WBCs.

  1. Rapid selective metal patterning on polydimethylsiloxane (PDMS) fabricated by capillarity-assisted laser direct write

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Tsang; Lee, Daeho; Sherry, Alexander; Grigoropoulos, Costas P.

    2011-09-01

    In this study we demonstrate a novel approach for the rapid fabricating micro scale metal (silver) patterning directly on a polydimethylsiloxane (PDMS) substrate. Silver nanoparticles were sintered on PDMS to form conductive metal films using laser direct write (LDW) technology. To achieve good metal film quality, a capillarity-assisted laser direct writing (CALDW) of nanoparticle suspensions on a low surface energy material (PDMS) was utilized. Experimental results showed controllable electrical conductivities and good film properties of the sintered silver patterns. This study reveals an advanced method of metal patterning on PDMS, and proposes a new research application of LDW in a nanoparticle colloidal environment.

  2. Evaluating an alternative method for rapid urinary creatinine determination

    EPA Science Inventory

    Creatinine (CR) is an endogenously-produced chemical routinely assayed in urine specimens to assess kidney function, sample dilution. The industry-standard method for CR determination, known as the kinetic Jaffe (KJ) method, relies on an exponential rate of a colorimetric change,...

  3. Evaluating an alternative method for rapid urinary creatinine determination

    EPA Science Inventory

    Creatinine (CR) is an endogenously-produced chemical routinely assayed in urine specimens to assess kidney function, sample dilution. The industry-standard method for CR determination, known as the kinetic Jaffe (KJ) method, relies on an exponential rate of a colorimetric change,...

  4. Rapid determination of actinides and (90)Sr in river water.

    PubMed

    Habibi, A; Boulet, B; Gleizes, M; Larivière, D; Cote, G

    2015-07-09

    Nuclear accidents occurred in latest years highlighted the difficulty to achieve, in a short time, the quantification of alpha and beta emitters. Indeed, most of the existing methods, though displaying excellent performances, can be very long, taking up to several weeks for some radioisotopes, such as (90)Sr. This study focuses on alpha and beta radioisotopes which could be accidentally released from nuclear installations and which could be measured by inductively coupled plasma mass spectrometer (ICP-MS). Indeed, a new and rapid separation method was developed for (234,235,236,238)U, (230,232)Th, (239,240)Pu, (237)Np, (241)Am and (90)Sr. The main objective was to minimize the duration of the separation protocol by the development of a unique radiochemical procedure with elution media compatible with ICP-MS measurements. Excellent performances were obtained with spiked river water samples. These performances are characterized by total yields exceeding 80% for all monitored radionuclides, as well as good reproducibility (RSD≤10%, n=12). The proposed radiochemical separation (including counting time) required less than 7h for a batch of 8 samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Rapidly patterning micro/nano devices by directly assembling ions and nanomaterials.

    PubMed

    Liu, Na; Wang, Feifei; Liu, Lianqing; Yu, Haibo; Xie, Shaorong; Wang, Jun; Wang, Yuechao; Lee, Gwo-Bin; Li, Wen J

    2016-08-26

    The synthesis and assembly of components are key steps in micro/nano device manufacturing. In this article, we report an optically controlled assembly method that can rapidly pattern micro/nano devices by directly assembling ions and nanomaterials without expensive physical masks and complex etching processes. Utilizing this controllable process, different types of device components (e.g., metallic and semiconductor) can be fabricated and assembled in 10-30 seconds, which is far more rapid and cost-effective than any other micro/nano fabrication method.

  6. Rapidly patterning micro/nano devices by directly assembling ions and nanomaterials

    PubMed Central

    Liu, Na; Wang, Feifei; Liu, Lianqing; Yu, Haibo; Xie, Shaorong; Wang, Jun; Wang, Yuechao; Lee, Gwo-Bin; Li, Wen J.

    2016-01-01

    The synthesis and assembly of components are key steps in micro/nano device manufacturing. In this article, we report an optically controlled assembly method that can rapidly pattern micro/nano devices by directly assembling ions and nanomaterials without expensive physical masks and complex etching processes. Utilizing this controllable process, different types of device components (e.g., metallic and semiconductor) can be fabricated and assembled in 10–30 seconds, which is far more rapid and cost-effective than any other micro/nano fabrication method. PMID:27561917

  7. Rapid prototyping of three-dimensional microfluidic mixers in glass by femtosecond laser direct writing.

    PubMed

    Liao, Yang; Song, Jiangxin; Li, En; Luo, Yong; Shen, Yinglong; Chen, Danping; Cheng, Ya; Xu, Zhizhan; Sugioka, Koji; Midorikawa, Katsumi

    2012-02-21

    The creation of complex three-dimensional (3D) microfluidic systems has attracted significant attention from both scientific and applied research communities. However, it is still a formidable challenge to build 3D microfluidic structures with arbitrary configurations using conventional planar lithographic fabrication methods. Here, we demonstrate rapid fabrication of high-aspect-ratio microfluidic channels with various 3D configurations in glass substrates by femtosecond laser direct writing. Based on this approach, we demonstrate a 3D passive microfluidic mixer and characterize its functionalities. This technology will enable rapid construction of complex 3D microfluidic devices for a wide array of lab-on-a-chip applications.

  8. Rapid computation of directional wellbore drawdown in a confined aquifer via Poisson resummation

    NASA Astrophysics Data System (ADS)

    Blumenthal, Benjamin J.; Zhan, Hongbin

    2016-08-01

    We have derived a rapidly computed analytical solution for drawdown caused by a partially or fully penetrating directional wellbore (vertical, horizontal, or slant) via Green's function method. The mathematical model assumes an anisotropic, homogeneous, confined, box-shaped aquifer. Any dimension of the box can have one of six possible boundary conditions: 1) both sides no-flux; 2) one side no-flux - one side constant-head; 3) both sides constant-head; 4) one side no-flux; 5) one side constant-head; 6) free boundary conditions. The solution has been optimized for rapid computation via Poisson Resummation, derivation of convergence rates, and numerical optimization of integration techniques. Upon application of the Poisson Resummation method, we were able to derive two sets of solutions with inverse convergence rates, namely an early-time rapidly convergent series (solution-A) and a late-time rapidly convergent series (solution-B). From this work we were able to link Green's function method (solution-B) back to image well theory (solution-A). We then derived an equation defining when the convergence rate between solution-A and solution-B is the same, which we termed the switch time. Utilizing the more rapidly convergent solution at the appropriate time, we obtained rapid convergence at all times. We have also shown that one may simplify each of the three infinite series for the three-dimensional solution to 11 terms and still maintain a maximum relative error of less than 10-14.

  9. Rapid and direct screening of H:C ratio in Archean kerogen via microRaman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ferralis, N.; Matys, E. D.; Allwood, A.; Knoll, A. H.; Summons, R. E.

    2015-12-01

    Rapid evaluation of the preservation of biosignatures in ancient kerogens is essential for the evaluation of the usability of Earth analogues as proxies of Martian geological materials. No single, non-destructive and non-invasive technique currently exists to rapidly determine such state of preservation of the organic matter in relation to its geological and mineral environment. Due to its non-invasive nature, microRaman spectroscopy is emerging as a candidate technique for the qualitative determination maturity of organic matter, by correlating Raman spectral features and aromatic carbon cluster size. Here we will present a novel quantitative method in which before-neglected Raman spectral features are correlated directly and with excellent accuracy with the H:C ratio. In addition to providing a chemical justification of the found direct correlation, we will show its applicability and predictive capabilities in evaluating H:C in Archean kerogens. This novel method opens new opportunities for the use of Raman spectroscopy and mapping. This includes the non-invasively determination of kerogen preservation and microscale chemical diversity within a particular Earth analogue, to be potentially extended to evaluate Raman spectra acquired directly on Mars.

  10. A rapid geochemical spectrophotometric determination of tungsten with dithiol

    USGS Publications Warehouse

    Welsch, E.P.

    1983-01-01

    1-g sample is decomposed with nitric and hydrofluoric acids, and after evaporation of the solution to dryness the residue is dissolved in concentrated hydrochloric acid. A clear aliquot is treated with stannous chloride to inhibit interferences. The blue tungsten dithiol complex is developed at a temperature of 85?? over a half-hour period. The complex is extracted into 2 ml of heptane and the tungsten is determined spectrophotometrically with a sensitivity of 0.5 ppm. Fifty samples per man-day can be analysed in this manner. ?? 1983.

  11. Rapid determination of carboxyhemoglobin in blood by Oximeter.

    PubMed

    Brehmer, Cornelia; Iten, Peter X

    2003-04-23

    Different methods to determine carboxyhemoglobin (COHb) in blood are described in the literature. In our laboratory three methods to analyze COHb in post-mortem blood samples were compared: the spectrophotometric method of Maehly, a gas chromatographic method with a thermal conductivity detector (GC-TCD) and the Oximeter. Several COHb containing blood samples of deceased persons were analyzed. Results of all three methods were comparable for low concentrations (ca. 10% COHb) as well as for high concentrations (ca. 80% COHb) regardless of the viscosity of the blood samples. The advantages of the Oximeter when compared to Maehly's method and GC-TCD are extreme short time of analysis (<1min), very small blood volume required (<0.1ml) and easy handling. In our opinion application of the Oximeter is not limited to analyses of blood samples from living persons (e.g. in clinical toxicology); it can as well be used for the determination of COHb in post-mortem blood samples. Hence it is a useful and time saving tool in forensic toxicology.

  12. Novel spectrophotometric technique for rapid determination of extractable PHA using Sudan black dye.

    PubMed

    Porras, Mauricio A; Villar, Marcelo A; Cubitto, María A

    2017-08-10

    Classical techniques employed to determine the amount of extractable poly(hydroxyalkanoate)s (PHAs) from cells, are laborious and destructive. Sudan black staining is commonly used in the laboratory to investigate the presence of intracellular PHA. The aim of the present study was to develop a low-cost alternative technique to achieve a quick determination of extractable intracellular PHA. This methodology employs a basic laboratory spectroscopy equipment and Sudan black dye for spectra determination. The correlation between the content of PHA in cell samples taken directly from the culture flask and its spectra was determined using partial least square regression analysis and simple linear regression analysis. The best fit obtained for calibration correlation analysis (R(2)=0.944, RSE: 1.24%), together with the good extractable PHA predictions (RSE=0.51%) demonstrate that the proposed methodology constitutes a fast way with high potential for the determination of extractable PHA. Based on its simplicity and flexibility, its application would be suitable in routine monitoring and rapid quantification in large-scale processes involving PHA metabolism. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. A rapid and simultaneous determination of several analgesic antiinflammatory agents by capillary zone electrophoresis.

    PubMed

    Makino, Kazutaka; Yano, Takahisa; Maiguma, Takayoshi; Teshima, Daisuke; Sendo, Toshiaki; Itoh, Yoshinori; Oishi, Ryozo

    2003-10-01

    A rapid and simultaneous determination of several analgesic antiinflammatory agents--ibuprofen, acetaminophen, indomethacin, and salicylic acid--in human serum was developed by using capillary zone electrophoresis (CZE) coupled with diode-array ultraviolet detection. After precipitation of serum protein with acetonitrile containing 3-isobutyl-1-methylxanthine as the internal standard, an aliquot of deproteinized samples was applied directly to the CZE system. It enabled us to measure all of these four agents within 6 min, and there were no peaks interfering with the assay of these agents or 3-isobutyl-1-methylxanthine. Both the separation and quantification of these agents in human serum were reproducible after repeated analysis within a day or day-to-day analysis. In addition, there was a good correlation for each drug (r = 0.997-0.999) between the values in serum determined by CZE analysis and those measured either by high-performance liquid chromatography with ultraviolet detection (ibuprofen and indomethacin) or by fluorescence polarization immunoassay (acetaminophen and salicylic acid). Therefore, the present CZE analysis could provide a simple, rapid, and efficient method for the identification as well as monitoring of analgesic antiinflammatory agents, particularly in serum of patients suffering from intoxication by overdosage of these agents.

  14. A Graphene-Based Electrochemical Sensor for Rapid Determination of Phenols in Water

    PubMed Central

    Chen, Kun; Zhang, Zai-Li; Liang, Yong-Mei; Liu, Wei

    2013-01-01

    A glassy carbon electrode (GCE) coated with a graphene/polymer film was fabricated for rapid determination of phenols in aqueous solutions. The electrochemical behavior of different phenols at the graphene/polymer-coated GCE was also investigated. In PBS buffer solution with a pH of 6.5, hydroquinone exhibits a well-defined reduction peak at the modified GCE. Based on this, an electrochemical method for the direct determination of phenols is proposed. Investigating different parameters revealed the optimized detection conditions for the electrode are a scan rate of 50 mV/s, dosage of graphene-polyaniline of 8 μL, dosage of tyrosinase of 3 μL, and pH of 6.5. Under the optimal conditions, the reduction peak current varies linearly with the concentration of phenols, with a linear regression equation of I (10−6A) = −4.887 × 10−4C (mol/L)−5.331 × 10−6 with a correlation coefficient of 0.9963 and limit of detection (S/N = 3) of 2.00 × 10−4 mol/L. The electrochemical sensor is also used to detect phenols in actual samples, where it shows great promise for rapid, simple and quantitative detection of phenols. PMID:23669709

  15. A portable photoelectrochemical probe for rapid determination of chemical oxygen demand in wastewaters.

    PubMed

    Zhang, Shanqing; Li, Lihong; Zhao, Huijun

    2009-10-15

    A photoelectrochemical probe for rapid determination of chemical oxygen demand (COD) is developed using a nanostructured mixed-phase TiO2 photoanode, namely PeCOD probe. A UV-LED light source and a USB mircroelectrochemical station are powered and controlled by a laptop computer, which makes the probe portable for onsite COD analyses. The photoelectrochemical measurement of COD was optimized in terms of light intensity, applied bias, and pH. Under the optimized conditions, the net steady state currents originated from the oxidation of organic compounds were found to be directly proportional to COD concentrations. A practical detection limit of 0.2 ppm COD and a linear range of 0-120 ppm COD were achieved. The analytical method using the portable PeCOD probe has the advantages of being rapid, low cost, robust, user-friendly, and environmental friendly. It has been successfully applied to determine the COD values of the synthetic samples consisting of potassium hydrogen phthalate, D-glucose, glutamic acid, glutaric acid, succinic acid, and malonic acid, and real samples from various industries, such as bakery, oil and grease manufacturer, poultry, hotel, fine food factory, and fresh food producer, commercial bread manufacturer. Excellent agreement between the proposed method and the conventional COD method (dichromate) was achieved.

  16. How do dogs determine the direction of tracks?

    PubMed

    Steen, J B; Wilsson, E

    1990-08-01

    Two professional tracking dogs were brought in at right angles to 50-m-long tracks to try to identify the clues that the dogs used to determine the direction of the tracks. When the dogs were tested on tracks laid by a walking man, they took the direction that the track-maker had moved significantly more often than predicted by random choice regardless of whether the person had moved forwards or backwards. When tested on tracks laid by bicycling on grass or asphalt, the choice of direction was not significantly different from random, even though the dogs were always rewarded when making correct choices. When four leather strips were tied to the back tyre of the bicycle before laying the track, the one dog tested took the correct direction significantly more often than predicted by random choice. When the leather strips were smeared with sausage before laying the tracks, the dog took the wrong direction more often than predicted by random choice. However, when rewarded for making correct choices, the dog learned to choose the direction in which the bicycle had actually moved. We suggest that our dogs determined the direction of tracks by comparing the scents of consecutive prints and following the prints in the direction of increasing intensity.

  17. Direct derivatization and rapid GC-MS screening of nerve agent markers in aqueous samples.

    PubMed

    Subramaniam, Raja; Astot, Crister; Juhlin, Lars; Nilsson, Calle; Ostin, Anders

    2010-09-01

    A rapid screening and identification method based on derivatization and gas chromatography mass spectrometry (GC-MS) has been developed for the detection of alkylphosphonic acids (APAs), the degradation products of organophosphorus nerve agents. The novel method described involves rapid (5 min) and direct derivatization of 25 microL aqueous sample using highly fluorinated phenyldiazomethane reagents (e.g., 1-(diazomethyl)-3,5-bis(trifluoromethyl)benzene). The APA derivatives are then screened by GC-MS negative ion chemical ionization (NICI) and identified by electron ionization (EI) mode. The conditions for the derivatization were optimized using statistical experimental design and multivariate data analysis. Method robustness was evaluated using aqueous samples from an official OPCW Proficiency Test and all APAs present in the sample were conclusively identified. Limits of detection for rapid screening using SIM NICI were between 5 and 10 ng/mL APA in aqueous sample, and for identification using full scan EI 100 ng/mL.

  18. Rapid determination of vitamin B₂ (riboflavin) in plasma by HPLC.

    PubMed

    Petteys, Brian J; Frank, Elizabeth L

    2011-01-14

    Riboflavin (vitamin B₂), as the exclusive source for the coenzymes flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) in humans, is a water-soluble vitamin critical for metabolism and energy production. In its coenzyme forms, riboflavin is involved in essential oxidation-reduction reactions. Deficiency leads to skin and mucosal disorders. Measurement of plasma riboflavin can be used to assess vitamin B₂ status in at-risk individuals. Proteins are removed from plasma by acid precipitation. An aliquot of the resulting supernatant is analyzed by reversed-phase HPLC. Impurities are separated from riboflavin isocratically and the target material is detected fluorometrically (excitation 450 nm; emission 520 nm). The method was validated for linearity, limit of quantification, accuracy, precision, and interference. The method was accurate and correlated well (R² = 0.993) to expected concentrations of spiked pooled plasma samples. Imprecision was < 10%. Riboflavin concentrations were determined in samples obtained from self-reported healthy adults who were not taking vitamin supplements. The reference interval established by nonparametric analysis was 6.7-50.1 nmol/l. This HPLC method allows separation and measurement of riboflavin in plasma in 7 min. Results from the assay may be used for clinical diagnosis of deficiency and to monitor therapeutic vitamin supplementation regimes. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Upconversion fluorescent strip sensor for rapid determination of Vibrio anguillarum

    NASA Astrophysics Data System (ADS)

    Zhao, Peng; Wu, Yuanyuan; Zhu, Yihua; Yang, Xiaoling; Jiang, Xin; Xiao, Jingfan; Zhang, Yuanxing; Li, Chunzhong

    2014-03-01

    Here, we report a simple and ultrasensitive upconversion fluorescent strip sensor based on NaYF4:Yb,Er nanoparticles (NPs) and the lateral flow immunochromatographic assay (LFIA). Carboxyl-modified β-NaYF4:Yb,Er NPs were successfully synthesized by a facile one-pot solvothermal approach, upon further coupling with monoclonal antibody, the resultant UCNPs-antibody conjugates probes were used in LFIA and served as signal vehicles for the fluorescent reporters. V. anguillarum was used as a model analyte to demonstrate the use of this strip sensor. The limit of the detection for the fluorescent strip was determined as 102 CFU mL-1, which is 100 times lower than those displayed by enzyme-linked immunosorbent assays, while the time needed for the detection was only 15 min. Furthermore, no cross-reaction with other eight pathogens was found, indicating the good specificity of the strip. This developed LFIA would offer the potential as a useful tool for the quantification of pathogens analysis in the future.

  20. A general geometric theory of attitude determination from directional sensing

    NASA Technical Reports Server (NTRS)

    Fang, B. T.

    1976-01-01

    A general geometric theory of spacecraft attitude determination from external reference direction sensors was presented. Outputs of different sensors are reduced to two kinds of basic directional measurements. Errors in these measurement equations are studied in detail. The partial derivatives of measurements with respect to the spacecraft orbit, the spacecraft attitude, and the error parameters form the basis for all orbit and attitude determination schemes and error analysis programs and are presented in a series of tables. The question of attitude observability is studied with the introduction of a graphical construction which provides a great deal of physical insight. The result is applied to the attitude observability of the IMP-8 spacecraft.

  1. Initial neighborhood biases and the quality of motion stimulation jointly influence the rapid emergence of direction preference in visual cortex.

    PubMed

    Van Hooser, Stephen D; Li, Ye; Christensson, Maria; Smith, Gordon B; White, Leonard E; Fitzpatrick, David

    2012-05-23

    Visual experience plays a critical role in the development of direction-selective responses in ferret visual cortex. In visually naive animals, presentation of a bidirectional "training" stimulus induces rapid increases in the direction-selective responses of single neurons that can be predicted by small but significant direction biases that are present in neighboring neurons at the onset of stimulation. In this study we used in vivo two-photon imaging of calcium signals to further explore the contribution of visual experience to the emergence of direction- selective responses in ferret visual cortex. The first set of experiments was designed to determine whether visual experience is required for the development of the initial neighborhood bias. In animals that were dark-reared until the time of eye opening, we found that individual neurons exhibited weak direction-selective responses accompanied by a reduced but statistically significant neighborhood bias, indicating that both features arise without the need for visual experience. The second set of experiments used a unidirectional training stimulus to assess the relative roles of the neighborhood bias and visual experience in determining the direction preference that cortical neurons acquire during direction training. We found that neurons became more responsive to the trained direction even when they were located in regions of the cortex with an initial neighborhood bias for the direction opposite the training stimulus. Together, these results suggest an adaptive developmental strategy for the elaboration of direction-selective responses, one in which experience-independent mechanisms provide a symmetry-breaking seed for the instructive effects of visual experience.

  2. Plume propagation direction determination with SO2 cameras

    NASA Astrophysics Data System (ADS)

    Klein, Angelika; Lübcke, Peter; Bobrowski, Nicole; Kuhn, Jonas; Platt, Ulrich

    2017-03-01

    SO2 cameras are becoming an established tool for measuring sulfur dioxide (SO2) fluxes in volcanic plumes with good precision and high temporal resolution. The primary result of SO2 camera measurements are time series of two-dimensional SO2 column density distributions (i.e. SO2 column density images). However, it is frequently overlooked that, in order to determine the correct SO2 fluxes, not only the SO2 column density, but also the distance between the camera and the volcanic plume, has to be precisely known. This is because cameras only measure angular extents of objects while flux measurements require knowledge of the spatial plume extent. The distance to the plume may vary within the image array (i.e. the field of view of the SO2 camera) since the plume propagation direction (i.e. the wind direction) might not be parallel to the image plane of the SO2 camera. If the wind direction and thus the camera-plume distance are not well known, this error propagates into the determined SO2 fluxes and can cause errors exceeding 50 %. This is a source of error which is independent of the frequently quoted (approximate) compensation of apparently higher SO2 column densities and apparently lower plume propagation velocities at non-perpendicular plume observation angles.Here, we propose a new method to estimate the propagation direction of the volcanic plume directly from SO2 camera image time series by analysing apparent flux gradients along the image plane. From the plume propagation direction and the known location of the SO2 source (i.e. volcanic vent) and camera position, the camera-plume distance can be determined. Besides being able to determine the plume propagation direction and thus the wind direction in the plume region directly from SO2 camera images, we additionally found that it is possible to detect changes of the propagation direction at a time resolution of the order of minutes. In addition to theoretical studies we applied our method to SO2 flux

  3. Using Impedance Spectroscopy to Assess the Viability of the Rapid Chloride Test for Determining Concrete Conductivity

    PubMed Central

    Snyder, K. A.; Ferraris, C.; Martys, N. S.; Garboczi, E. J.

    2000-01-01

    The suitability of using the initial current from the rapid chloride test (ASTM C 1202) to determine specimen conductivity is tested using impedance spectroscopy with a frequency spectrum of 10 Hz to 1 MHz. The specimen conductivity has an analytical relationship to specimen diffusivity and so is a useful quantity in service life prediction. Measurements made on specimens of different lengths indicate that the total charge passed during the six hour conduction test carried out according to ASTM C 1202 is not a direct measure of specimen conductivity. Further, ohmic heating during the 6 hour test makes it nearly impossible to directly measure any specimen transport property from the results. The total charge passed during the 6 hour conduction test is, therefore, not a reliable quantity for service life prediction. Results indicate that the direct current (dc) measurement of resistance using a voltage of 60 V is sufficient to overwhelm polarization effects, thereby yielding an accurate estimate of the true specimen conductivity. Impedance spectroscopy measurements also indicate that corrosion may form on the brass electrodes, adding bias to a conductivity estimate based upon a dc measurement. PMID:27551618

  4. Method for determining shear direction using liquid crystal coatings

    NASA Technical Reports Server (NTRS)

    Reda, Daniel C.

    1995-01-01

    A method is provided for determining shear direction wherein a beam of white light is directed onto the surface of a liquid crystal coating to cause the white light to be dispersed (reflected) from the surface in a spectrum having bands of different colors in a fixed spatial 2 (angular) sequence. The system is calibrated by locating an observer, e.g., a video and movie camera, such that a particular color band (preferably at or near the center of the reflected spectrum) is observed to thereby provide a reference color band. Because the application of shear causes either clockwise or counterclockwise rotation of the reflected spectrum dependent on the direction of the shear, a determination is then made of the reflected color band observed by the observer when the surface of the liquid crystal is subjected to shear to thereby determine the direction of the shear based on the directional (rotation) relation of the observed color band with respect to the reference color band in the spatial sequence of color bands.

  5. What determines direction of asymmetry: genes, environment or chance?

    PubMed

    Palmer, A Richard

    2016-12-19

    Conspicuous asymmetries seen in many animals and plants offer diverse opportunities to test how the development of a similar morphological feature has evolved in wildly different types of organisms. One key question is: do common rules govern how direction of asymmetry is determined (symmetry is broken) during ontogeny to yield an asymmetrical individual? Examples from numerous organisms illustrate how diverse this process is. These examples also provide some surprising answers to related questions. Is direction of asymmetry in an individual determined by genes, environment or chance? Is direction of asymmetry determined locally (structure by structure) or globally (at the level of the whole body)? Does direction of asymmetry persist when an asymmetrical structure regenerates following autotomy? The answers vary greatly for asymmetries as diverse as gastropod coiling direction, flatfish eye side, crossbill finch bill crossing, asymmetrical claws in shrimp, lobsters and crabs, katydid sound-producing structures, earwig penises and various plant asymmetries. Several examples also reveal how stochastic asymmetry in mollusc and crustacean early cleavage, in Drosophila oogenesis, and in Caenorhabditis elegans epidermal blast cell movement, is a normal component of deterministic development. Collectively, these examples shed light on the role of genes as leaders or followers in evolution.This article is part of the themed issue 'Provocative questions in left-right asymmetry'. © 2016 The Author(s).

  6. Determination of Electromagnetic Source Direction as an Eigenvalue Problem

    NASA Astrophysics Data System (ADS)

    Martínez-Oliveros, Juan C.; Lindsey, Charles; Bale, Stuart D.; Krucker, Säm

    2012-07-01

    Low-frequency solar and interplanetary radio bursts are generated at frequencies below the ionospheric plasma cutoff and must therefore be measured in space, with deployable antenna systems. The problem of measuring both the general direction and polarization of an electromagnetic source is commonly solved by iterative fitting methods such as linear regression that deal simultaneously with both directional and polarization parameters. We have developed a scheme that separates the problem of deriving the source direction from that of determining the polarization, avoiding iteration in a multi-dimensional manifold. The crux of the method is to first determine the source direction independently of concerns as to its polarization. Once the source direction is known, its direct characterization in terms of Stokes vectors, in a single iteration if desired, is relatively simple. This study applies the source-direction determination to radio signatures of flares received by STEREO. We studied two previously analyzed radio type III bursts and found that the results of the eigenvalue decomposition technique are consistent with those obtained previously by Reiner et al. ( Solar Phys. 259, 255, 2009). For the type III burst observed on 7 December 2007, the difference in travel times from the derived source location to STEREO A and B is the same as the difference in the onset times of the burst profiles measured by the two spacecraft. This is consistent with emission originating from a single, relatively compact source. For the second event of 29 January 2008, the relative timing does not agree, suggesting emission from two sources separated by 0.1 AU, or perhaps from an elongated region encompassing the apparent source locations.

  7. False negative rate of cervical cytologic smear screening as determined by rapid rescreening.

    PubMed

    Renshaw, A A; Bellerose, B; DiNisco, S A; Minter, L J; Lee, K R

    1999-01-01

    To determine the reliability of the false negative rate (FNR) of cervical cytologic smear screening by rapid rescreening. A test set of 401 cases (311 originally diagnosed as negative, 74 as atypical squamous cells of undetermined significance [ASCUS], 14 as low grade squamous intraepithelial lesion [LSIL] and 2 as high grade squamous intraepithelial lesion [HSIL]) were rapidly (30 seconds each) rescreened by five cytotechnologists with no prior experience in rapid rescreening, and the FNRs of rapid rescreening and primary screening were determined. These results were compared with each other and with the FNR of primary screening as determined by routine rescreening of all cases with no time limit. All five observers detected a different group of abnormal cases; only 9% of all cases originally diagnosed as ASCUS or worse and 43% of all cases diagnosed as LSIL or worse were detected by all five observers. Nevertheless, using ASCUS as the threshold for an abnormal result, the FNR of rapid rescreening fell into a relatively narrow range, 61-74% (mean, 68.2 +/- 5.0); using LSIL as the threshold resulted in FNRs of rapid rescreening between 25% and 38% (30.0 +/- 4.7). Each observer, using rapid rescreening, detected between one and three false negative cases; routine rescreening of all cases without a time limit detected five cases. The FNR of cervical cytologic smear screening, as determined by rapid rescreening, was 18.4 +/- 6.1% as compared with 14.8% by routine rescreening without a time limit. The FNR of rapid rescreening is relatively reproducible even though the individual cases identified varied between reviewers. The FNR of rapid rescreening is similar to that of routine rescreening. Rapid prescreening may be the most logistically simple method to determine the true FNR of a laboratory.

  8. Rapid assessment of multi-directional 3D-flow fields using active heat pulse sensing in the streambed

    NASA Astrophysics Data System (ADS)

    Banks, Eddie W.; Shanafield, Margaret; McCallum, James; Noorduijn, Saskia; Lewandowski, Jorg; Batelaan, Okke

    2017-04-01

    Application of heat as a tracer to hydrological studies has rapidly progressed in the last few decades driven by the simplicity of the methodology and low cost of sensor technology. Vertical temperature profiles using the 1D analytical solution are now widely used to determine hyporheic flow patterns and hydraulic dynamics within the shallow streambed sediment. One of the challenges in using a limited number of measurements to characterize processes that are not entirely vertical has been the determination of the horizontal or lateral flow component and how these components vary spatially and also their relative magnitude in 3D space. This study used a homemade portable 56 sensor, 3D temperature array with 3 heat pulse sources (the hot rod) to measure the flow direction and magnitude up to 230 mm below the water-sediment interface at a scale of a few centimetres in a range of sedimentary environments from fine silt to coarse gravels. Short heat pulses, typically 1 minute in duration were injected into the stream sediment and the response was monitored over a period of 20-30 minutes. Breakthrough curves from each of the temperature sensors was analysed using a version of the heat transport equation and a calibration objective function was used to estimate the x, y and z flow vector to determine the dominant direction and magnitude at the point of observation. A GUI in Python was developed to provide a user-friendly interface for processing the field data. The robust design of the hot rod and use of short duration heat pulses provides a rapid assessment technique for different heterogeneous stream environments and conditions which are crucial to determining dynamic and multi-directional flow patterns and understanding biogeochemical processes at the water-streambed interface.

  9. Determining the direction of tooth grinding: an in vitro study.

    PubMed

    ten Berge, F; te Poel, J; Ranjitkar, S; Kaidonis, J A; Lobbezoo, F; Hughes, T E; Townsend, G C

    2012-08-01

    The analysis of microwear patterns, including scratch types and widths, has enabled reconstruction of the dietary habits and lifestyles of prehistoric and modern humans. The aim of this in vitro study was to determine whether an assessment of microwear features of experimental scratches placed on enamel, perpendicularly to the direction of grinding, could predict the grinding direction. Experimental scratches were placed using a scalpel blade on standardised wear facets that had been prepared by wearing opposing enamel surfaces in an electromechanical tooth wear machine. These control 'baseline' facets (with unworn experimental scratches) were subjected to 50 wear cycles, so that differential microwear could be observed on the leading and trailing edges of the 'final' facets. In Group 1 (n=28), the 'footprint' microwear patterns corresponding to the known grinding direction of specimens in the tooth wear machine were identified. Then, they were used to predict the direction of tooth grinding blindly in the same sample after a 2-week intermission period. To avoid overfitting the predictive model, its sensitivity was also cross-validated in a new sample (Group 2, n=14). A crescent-shaped characteristic observed in most experimental scratches matched the grinding direction on all occasions. The best predictor of the direction of grinding was a combined assessment of the leading edge microwear pattern and the crescent characteristic (82.1% in Group 1 and 92.9% in Group 2). In conclusion, a simple scratch test can determine the direction of tooth grinding with high reliability, although further improvement in sensitivity is desirable.

  10. Rapid Determination of Mercury in Seafood in an Introductory Environmental Science Class

    ERIC Educational Resources Information Center

    Rice, Jeanette K.; Jenkins, J. David; Manley, A. Citabria; Sorel, Eric; Smith, C. Jimmy

    2005-01-01

    An experiment is described which allows easy, rapid determination of mercury levels in commercially seafood samples from a contaminated area. Students gain experience in the preparation of a calibration curve, the determination of unknown concentrations, and risk assessment based on experimentally determined data.

  11. Rapid Determination of Mercury in Seafood in an Introductory Environmental Science Class

    ERIC Educational Resources Information Center

    Rice, Jeanette K.; Jenkins, J. David; Manley, A. Citabria; Sorel, Eric; Smith, C. Jimmy

    2005-01-01

    An experiment is described which allows easy, rapid determination of mercury levels in commercially seafood samples from a contaminated area. Students gain experience in the preparation of a calibration curve, the determination of unknown concentrations, and risk assessment based on experimentally determined data.

  12. High-performance liquid chromatography determination of direct and temporary dyes in natural hair colourings.

    PubMed

    Scarpi, C; Ninci, F; Centini, M; Anselmi, C

    1998-02-20

    A simple and reliable HPLC method is described for the simultaneous determination of nine direct and temporary hair dyes in hair colourings containing vegetal extracts. Detection was performed by a diode array detector and two different wavelengths, in the visible range (450 and 650 nm), were used for quantitation. The method does not involve any extraction procedure and it is sufficiently rapid and accurate for routine analyses. The method described was successfully applied to the identification of synthetic organic dyes in 13 direct and temporary hair dyeing formulations commercialized as 'natural'.

  13. Gas purge-microsyringe extraction: a rapid and exhaustive direct microextraction technique of polycyclic aromatic hydrocarbons from plants.

    PubMed

    Wang, Juan; Yang, Cui; Li, Huijie; Piao, Xiangfan; Li, Donghao

    2013-12-17

    Gas purge-microsyringe extraction (GP-MSE) is a rapid and exhaustive microextraction technique for volatile and semivolatile compounds. In this study, a theoretical system of GP-MSE was established by directly extracting and analyzing 16 kinds of polycyclic aromatic hydrocarbons (PAHs) from plant samples. On the basis of theoretical consideration, a full factorial experimental design was first used to evaluate the main effects and interactions of the experimental parameters affecting the extraction efficiency. Further experiments were carried out to determine the extraction kinetics and desorption temperature-dependent. The results indicated that three factors, namely desorption temperature (temperature of sample phase) Td, extraction time t, and gas flow rate u, had a significantly positive effect on the extraction efficiency of GP-MSE for PAHs. Extraction processes of PAHs in plant samples followed by first-order kinetics (relative coefficient R(2) of simulation curves were 0.731-1.000, with an average of 0.958 and 4.06% relative standard deviation), and obviously depended on the desorption temperature. Furthermore, the effect of the matrix was determined from the difference in Eapp,d. Finally, satisfactory recoveries of 16 PAHs were obtained using optimal parameters. The study demonstrated that GP-MSE could provide a rapid and exhaustive means of direct extraction of PAHs from plant samples. The extraction kinetics were similar that of the inverse process of the desorption kinetics of the sample phase.

  14. Challenges of direct photon production at forward rapidities and large pT

    NASA Astrophysics Data System (ADS)

    Krelina, Michal; Cepila, Jan; Nemchik, Jan

    2017-02-01

    Direct photons produced in interactions with nuclear targets represent a cleaner probe for investigation of nuclear effects than hadrons, since photons have no final state interaction and no energy loss or absorption is expected in the produced hot medium. Therefore, besides the Cronin enhancement at medium-high transverse momenta pT and isospin effects at larger pT , one should not expect any nuclear effects. However, this fact is in contrast to the PHENIX data providing an evidence for a significant large-pT suppression at mid rapidities in central d + Au and Au + Au collisions that cannot be induced by coherent phenomena (gluon shadowing, Color Glass Condensate). We demonstrate that such an unexpected results is subject to deficit of energy induced universally by multiple initial state interactions (ISI) towards the kinematic limits (large Feynman xF and/or large {x_T} = 2{p_T}/\\sqrt s ). For this reason, in order to enhance the effects of coherence, one should be cautious going to forward rapidities and higher energies. In the LHC kinematic region ISI corrections are irrelevant at mid rapidities but cause rather strong suppression at forward rapidities and large pT . Numerical calculations of invariant pT spectra and the nuclear modification factor were performed within two different models, the color dipole formalism and the model based on kT -factorization, which are successfully confronted with available data from the RHIC and LHC collider experiments. Finally, we perform also predictions for a strong onset of ISI corrections at forward rapidities and corresponding expected suppression can be verified by the future measurements at LHC.

  15. Rapid determination of sugar level in snack products using infrared spectroscopy.

    PubMed

    Wang, Ting; Rodriguez-Saona, Luis E

    2012-08-01

    Real-time spectroscopic methods can provide a valuable window into food manufacturing to permit optimization of production rate, quality and safety. There is a need for cutting edge sensor technology directed at improving efficiency, throughput and reliability of critical processes. The aim of the research was to evaluate the feasibility of infrared systems combined with chemometric analysis to develop rapid methods for determination of sugars in cereal products. Samples were ground and spectra were collected using a mid-infrared (MIR) spectrometer equipped with a triple-bounce ZnSe MIRacle attenuated total reflectance accessory or Fourier transform near infrared (NIR) system equipped with a diffuse reflection-integrating sphere. Sugar contents were determined using a reference HPLC method. Partial least squares regression (PLSR) was used to create cross-validated calibration models. The predictability of the models was evaluated on an independent set of samples and compared with reference techniques. MIR and NIR spectra showed characteristic absorption bands for sugars, and generated excellent PLSR models (sucrose: SEP < 1.7% and r > 0.96). Multivariate models accurately and precisely predicted sugar level in snacks allowing for rapid analysis. This simple technique allows for reliable prediction of quality parameters, and automation enabling food manufacturers for early corrective actions that will ultimately save time and money while establishing a uniform quality. The U.S. snack food industry generates billions of dollars in revenue each year and vibrational spectroscopic methods combined with pattern recognition analysis could permit optimization of production rate, quality, and safety of many food products. This research showed that infrared spectroscopy is a powerful technique for near real-time (approximately 1 min) assessment of sugar content in various cereal products. © 2012 Institute of Food Technologists®

  16. Direct determination of nonmetals in solution with atomic spectrometry

    SciTech Connect

    McGregor, D.A.; Cull, K.B.; Gehlhausen, J.M.; Viscomi, A.S.; Wu, M.; Zhang, L.; Carnahan, J.W.

    1988-10-01

    In a 1984 report, Browner and Boorn discussed factors associated with sample introduction in atomic spectroscopy. Because of inherent problems that often restrict detection limits and produce interference effects, the authors questioned whether sample introduction was the Achilles' heel of atomic spectroscopy. It is also well known, but less often discussed, that another chink exists in the armor of this class of techniques. This chink is characterized by the difficulty of nonmetal determinations with solution samples. In this article, solution nonmetal determinations are addressed on a fundamental level, research in this direction is characterized, and future implications are discussed.

  17. Direct determination of quantum efficiency of semiconducting films

    DOEpatents

    Faughnan, Brian W.; Hanak, Joseph J.

    1986-01-01

    Photovoltaic quantum efficiency of semiconductor samples is determined directly, without requiring that a built-in photovoltage be generated by the sample. Electrodes are attached to the sample so as to form at least one Schottky barrier therewith. When illuminated, the generated photocurrent carriers are collected by an external bias voltage impressed across the electrodes. The generated photocurrent is measured, and photovoltaic quantum efficiency is calculated therefrom.

  18. Direct determination of quantum efficiency of semiconducting films

    DOEpatents

    Faughnan, B.W.; Hanak, J.J.

    Photovoltaic quantum efficiency of semiconductor samples is determined directly, without requiring that a built-in photovoltage be generated by the sample. Electrodes are attached to the sample so as to form at least one Schottky barrier therewith. When illuminated, the generated photocurrent carriers are collected by an external bias voltage impressed across the electrodes. The generated photocurrent is measured, and photovoltaic quantum efficiency is calculated therefrom.

  19. [Rapid determination of cyclamate in foods by capillary zone electrophoresis with indirect ultraviolet detection].

    PubMed

    Chen, Tong; Ding, Xiaojing; Li, Yizheng; Zhao, Xudong; Zhao, Shan

    2014-06-01

    A new method for the rapid determination of cyclamate in foods by capillary zone electrophoresis (CZE) with indirect ultraviolet detection was developed. The separation was carried out with an uncoated fused-silica capillary (75 microm i.d., total length 80 cm, effective length 70 cm). The separation buffer consisted of 2 mmol/L sodium benzoate, 10 mmol/L sodium carbonate and 0.5 mmol/L hexadecyl trimethyl ammonium bromide. The separation voltage was -30 kV and the detection wavelength was 200 nm. The liquid samples could be directly injected after dilution with ultrapure water. The solid samples were first grounded or cut into pieces, and then extracted with ultrapure water. Then, the mixed solution was centrifuged. The supernatant was directly injected or injected after dilution with ultrapure water. The analytes were determined by external calibration. The limits of detection (S/N = 3) and the limits of quantification (S/N = 9) were 8.9 mg/kg and 26.7 mg/kg, respectively. The linear range between the corrected peak area and the mass concentration was from 1.2 mg/L to 80 mg/L with the correlation coefficient of 0.999 9. The average spiked recoveries of five replicates at three spiked levels (2.5, 10 and 20 mg/L) were 93.4%, 100.3% and 101.9% with the relative standard deviations of 6.7%, 2.0% and 2.2%, respectively. The intra- and inter-day precisions of the method were 2.6% and 4.5%, respectively. The method is simple and rapid with minimal sample pretreatment and reagent consumption. No solvent was needed throughout the whole process of analysis. The analysis could be completed within 11 min (6 min for rinsing and 5 min for separation). The newly established method was used for the determination of cyclamate in a proficiency test sample. The results were in good agreement with that of the National Standard method, which illustrated the accuracy of the present method. Then, seven food samples were analyzed using the current new method and satisfactory results

  20. Virtual directions in paleomagnetism: A global and rapid approach to evaluate the NRM components.

    NASA Astrophysics Data System (ADS)

    Ramón, Maria J.; Pueyo, Emilio L.; Oliva-Urcia, Belén; Larrasoaña, Juan C.

    2017-02-01

    We introduce a method and software to process demagnetization data for a rapid and integrative estimation of characteristic remanent magnetization (ChRM) components. The virtual directions (VIDI) of a paleomagnetic site are “all” possible directions that can be calculated from a given demagnetization routine of “n” steps (being m the number of specimens in the site). If the ChRM can be defined for a site, it will be represented in the VIDI set. Directions can be calculated for successive steps using principal component analysis, both anchored to the origin (resultant virtual directions RVD; m * (n2+n)/2) and not anchored (difference virtual directions DVD; m * (n2-n)/2). The number of directions per specimen (n2) is very large and will enhance all ChRM components with noisy regions where two components were fitted together (mixing their unblocking intervals). In the same way, resultant and difference virtual circles (RVC, DVC) are calculated. Virtual directions and circles are a global and objective approach to unravel different natural remanent magnetization (NRM) components for a paleomagnetic site without any assumption. To better constrain the stable components, some filters can be applied, such as establishing an upper boundary to the MAD, removing samples with anomalous intensities, or stating a minimum number of demagnetization steps (objective filters) or selecting a given unblocking interval (subjective but based on the expertise). On the other hand, the VPD program also allows the application of standard approaches (classic PCA fitting of directions a circles) and other ancillary methods (stacking routine, linearity spectrum analysis) giving an objective, global and robust idea of the demagnetization structure with minimal assumptions. Application of the VIDI method to natural cases (outcrops in the Pyrenees and u-channel data from a Roman dam infill in northern Spain) and their comparison to other approaches (classic end-point, demagnetization

  1. Rapid collection of iron hydroxide for determination of Th isotopes in seawater.

    PubMed

    Okubo, Ayako; Obata, Hajime; Magara, Masaaki; Kimura, Takaumi; Ogawa, Hiroshi

    2013-12-04

    This work introduces a novel method of recovery of iron hydroxide using a DIAION CR-20 chelating resin column to determine Th isotopes in seawater with a sector field (SF) inductively coupled plasma mass spectrometer (ICP-MS). Thorium isotopes in seawater were co-precipitated with iron hydroxide, and this precipitate was sent to chelating resin column. Ferric ions in the iron hydroxide were bonded to functional groups of the chelating resin directly, resulting in a pH increase of the effluent by release of hydroxide ion from the iron hydroxide. The co-precipitated thorium isotopes were quantitatively collected within the column, which indicated that thorium was retained on the iron hydroxide remaining on the chelating column. The chelating column quantitatively collected (232)Th with iron hydroxide in seawater at flow rates of 20-25 mL min(-1). Based on this flow rate, a 5 L sample was processed within 3-4 h. The >20 h aging of iron hydroxide tends to reduce the recovery of (232)Th. The rapid collection method was successfully applied to the determination of (230)Th and (232)Th in open-ocean seawater samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. A Rapid Method for Determining the Concentration of Recombinant Protein Secreted from Pichia pastoris

    NASA Astrophysics Data System (ADS)

    Sun, L. W.; Zhao, Y.; Niu, L. P.; Jiang, R.; Song, Y.; Feng, H.; feng, K.; Qi, C.

    2011-02-01

    Pichia secretive expression system is one of powerful eukaryotic expression systems in genetic engineering, which is especially suitable for industrial utilization. Because of the low concentration of the target protein in initial experiment, the methods and conditions for expression of the target protein should be optimized according to the protein yield repetitively. It is necessary to set up a rapid, simple and convenient analysis method for protein expression levels instead of the generally used method such as ultrafiltration, purification, dialysis, lyophilization and so on. In this paper, acetone precipitation method was chosen to concentrate the recombinant protein firstly after comparing with four different protein precipitation methods systematically, and then the protein was analyzed by SDS-Polyacrylamide Gel Electrophoresis. The recombinant protein was determined with the feature of protein band by the Automated Image Capture and 1-D Analysis Software directly. With this method, the optimized expression conditions of basic fibroblast growth factor secreted from pichia were obtained, which is as the same as using traditional methods. Hence, a convenient tool to determine the optimized conditions for the expression of recombinant proteins in Pichia was established.

  3. Consequences of statistical sense determination for WIMP directional detection

    NASA Astrophysics Data System (ADS)

    Green, Anne M.; Morgan, Ben

    2008-01-01

    We study the consequences of limited recoil sense reconstruction on the number of events required to reject isotropy and detect a WIMP signal using a directional detector. For a constant probability of determining the sense correctly, 3-d readout and zero background, we find that as the probability is decreased from 1.0 to 0.75 the number of events required increases by a factor of a few. As the probability is decreased further the number of events increases sharply, and isotropy can be rejected more easily by discarding the sense information and using axial statistics. This however requires an order of magnitude more events than vectorial data with perfect sense determination. We also consider energy dependent probabilities of correctly measuring the sense. Our main finding is that correctly determining the sense of the abundant, but less anisotropic, low energy recoils is most important.

  4. Direct atomic structure determination by the inspection of structural phase.

    PubMed

    Nakashima, Philip N H; Moodie, Alexander F; Etheridge, Joanne

    2013-08-27

    A century has passed since Bragg solved the first atomic structure using diffraction. As with this first structure, all atomic structures to date have been deduced from the measurement of many diffracted intensities using iterative and statistical methods. We show that centrosymmetric atomic structures can be determined without the need to measure or even record a diffracted intensity. Instead, atomic structures can be determined directly and quickly from the observation of crystallographic phases in electron diffraction patterns. Furthermore, only a few phases are required to achieve high resolution. This represents a paradigm shift in structure determination methods, which we demonstrate with the moderately complex α-Al2O3. We show that the observation of just nine phases enables the location of all atoms with a resolution of better than 0.1 Å. This level of certainty previously required the measurement of thousands of diffracted intensities.

  5. Direct atomic structure determination by the inspection of structural phase

    PubMed Central

    Nakashima, Philip N. H.; Moodie, Alexander F.; Etheridge, Joanne

    2013-01-01

    A century has passed since Bragg solved the first atomic structure using diffraction. As with this first structure, all atomic structures to date have been deduced from the measurement of many diffracted intensities using iterative and statistical methods. We show that centrosymmetric atomic structures can be determined without the need to measure or even record a diffracted intensity. Instead, atomic structures can be determined directly and quickly from the observation of crystallographic phases in electron diffraction patterns. Furthermore, only a few phases are required to achieve high resolution. This represents a paradigm shift in structure determination methods, which we demonstrate with the moderately complex α-Al2O3. We show that the observation of just nine phases enables the location of all atoms with a resolution of better than 0.1 Å. This level of certainty previously required the measurement of thousands of diffracted intensities. PMID:23940343

  6. Rapid Antimicrobial Susceptibility Determination of Uropathogens in Clinical Urine Specimens by Use of ATP Bioluminescence▿

    PubMed Central

    Ivančić, Vesna; Mastali, Mitra; Percy, Neil; Gornbein, Jeffrey; Babbitt, Jane T.; Li, Yang; Landaw, Elliot M.; Bruckner, David A.; Churchill, Bernard M.; Haake, David A.

    2008-01-01

    We describe the first direct testing of the antimicrobial susceptibilities of bacterial pathogens in human clinical fluid samples by the use of ATP bioluminescence. We developed an ATP bioluminescence assay that eliminates somatic sources of ATP to selectively quantify the bacterial load in clinical urine specimens with a sensitivity of <1,000 CFU per milliliter. There was a log-log relationship between light emission and the numbers of CFU in clinical urine specimens. A clinical study was performed to evaluate the accuracy of the ATP bioluminescence assay for determination of the antimicrobial susceptibilities of uropathogens in clinical urine specimens tested in a blinded manner. ATP bioluminescent bacterial density quantitation was used to determine the inoculation volume in growth medium with and without antibiotics. After incubation at 37°C for 120 min, the ATP bioluminescence assay was repeated to evaluate the uropathogen response to antibiotics. The ability of the ATP bioluminescence assay to discriminate between antimicrobial susceptibility and resistance was determined by comparison of the results obtained by the ATP bioluminescence assay with the results obtained by standard clinical microbiology methods. Receiver operator characteristic curves were used to determine the optimal threshold for discriminating between susceptibility and resistance. Susceptibility and resistance were correctly predicted in 87% and 95% of cases, respectively, for an overall unweighted accuracy of 91%, when the results were stratified by antibiotic. For samples in which the pathogen was susceptible, the accuracy improved to 95% when the results for samples with less than a 25-fold increase in the amount of bacterial ATP in the medium without antibiotics were excluded. These data indicate that a rapid bioluminescent antimicrobial susceptibility assay may be useful for the management of urinary tract infections. PMID:18272708

  7. Rapid antimicrobial susceptibility determination of uropathogens in clinical urine specimens by use of ATP bioluminescence.

    PubMed

    Ivancic, Vesna; Mastali, Mitra; Percy, Neil; Gornbein, Jeffrey; Babbitt, Jane T; Li, Yang; Landaw, Elliot M; Bruckner, David A; Churchill, Bernard M; Haake, David A

    2008-04-01

    We describe the first direct testing of the antimicrobial susceptibilities of bacterial pathogens in human clinical fluid samples by the use of ATP bioluminescence. We developed an ATP bioluminescence assay that eliminates somatic sources of ATP to selectively quantify the bacterial load in clinical urine specimens with a sensitivity of <1,000 CFU per milliliter. There was a log-log relationship between light emission and the numbers of CFU in clinical urine specimens. A clinical study was performed to evaluate the accuracy of the ATP bioluminescence assay for determination of the antimicrobial susceptibilities of uropathogens in clinical urine specimens tested in a blinded manner. ATP bioluminescent bacterial density quantitation was used to determine the inoculation volume in growth medium with and without antibiotics. After incubation at 37 degrees C for 120 min, the ATP bioluminescence assay was repeated to evaluate the uropathogen response to antibiotics. The ability of the ATP bioluminescence assay to discriminate between antimicrobial susceptibility and resistance was determined by comparison of the results obtained by the ATP bioluminescence assay with the results obtained by standard clinical microbiology methods. Receiver operator characteristic curves were used to determine the optimal threshold for discriminating between susceptibility and resistance. Susceptibility and resistance were correctly predicted in 87% and 95% of cases, respectively, for an overall unweighted accuracy of 91%, when the results were stratified by antibiotic. For samples in which the pathogen was susceptible, the accuracy improved to 95% when the results for samples with less than a 25-fold increase in the amount of bacterial ATP in the medium without antibiotics were excluded. These data indicate that a rapid bioluminescent antimicrobial susceptibility assay may be useful for the management of urinary tract infections.

  8. Rapid detection of chlorine-induced bacterial injury by the direct viable count method using image analysis.

    PubMed Central

    Singh, A; Yu, F P; McFeters, G A

    1990-01-01

    A modified direct viable count method to detect living bacteria was used with image analysis for the rapid enumeration of chlorine-injured cells in an Escherichia coli culture. The method was also used for determining chlorine-induced injury in coliform isolates and enteric pathogenic bacteria. Cultures were incubated in phosphate-buffered saline, containing 0.3% Casamino Acids (Difco Laboratories, Detroit, Mich.), 0.03% yeast extract, and optimal concentrations of nalidixic acid. Samples were withdrawn before and after incubation and stained with acridine orange, and cell lengths and breadths were measured by computerized image analysis. After incubation, cells which exceeded the mean preincubation length (viable cells) were enumerated and the results were compared with those obtained by the plate count method. Injury in the chlorine-exposed cell population was determined from the difference in viable count obtained with a nonselective Casamino Acids-yeast extract-nalidixic acid medium and a selective Casamino Acids-yeast extract-nalidixic acid medium containing sodium deoxycholate or sodium lauryl sulfate. The levels of injury determined by the direct viable count technique by using image analysis were comparable to those determined by the plate count method. The results showed that image analysis, under optimal conditions, enumerated significantly higher numbers of stressed E. coli than the plate count method did and detected injury in various cultures in 4 to 6 h. PMID:2407185

  9. Rapid sensory-directed methodology for the selection of high-quality aroma wines.

    PubMed

    Sáenz-Navajas, María-Pilar; Alegre, Yohanna; de-la-Fuente, Arancha; Ferreira, Vicente; García, David; Eizaguirre, Sara; Razquin, Iosu; Hernández-Orte, Purificación

    2016-09-01

    The present work contributes by developing a rapid sensory-directed methodology for the screening and selection of high-quality wines with different sensory profiles. Verdejo and Tempranillo musts were fermented with 50 different yeasts each under controlled laboratory conditions. Resulting samples were firstly categorised according to five levels of quality by a panel of wine professionals. Higher quality samples were described by flash profiling by a semi-trained panel and most distinctive samples were screened by gas chromatography-olfactometry (GC-O). Seven Verdejo and five Tempranillo samples were classified in the highest quality category, presenting different aroma profiles such as citrus, fruit in syrup, boxtree/vegetal, tropical or wet grain aromas for Verdejo and red fruit or fruit in syrup for Tempranillo. β-Damascenone, 3-mercaptohexyl acetate and ethyl butyrate appeared as distinctive quality compounds linked to dried, tropical and red fruit aromas, respectively. The categorisation task followed by flash profiling and GC-O analysis was shown to be a rapid and effective sensory-directed methodology for the screening of distinctive and quality wine aroma profiles in a case study of yeast selection. The wine industry could benefit from the use of this methodology as a complementary tool for optimising different technical processes. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  10. Technical note: Improved method for rapid DNA extraction of mastitis pathogens directly from milk.

    PubMed

    Cremonesi, P; Castiglioni, B; Malferrari, G; Biunno, I; Vimercati, C; Moroni, P; Morandi, S; Luzzana, M

    2006-01-01

    Efficient control against bovine mastitis requires sensitive, rapid, and specific tests to detect and identify the main bacteria that cause heavy losses to the dairy industry. Molecular detection of pathogenic microorganisms is based on DNA amplification of the target pathogen. Therefore, efficient extraction of DNA from pathogenic bacteria is a major step. In this study, we aimed to develop a specific, sensitive, and rapid method to extract DNA directly from the main gram-positive bacteria known to cause bovine mastitis (Staphylococcus aureus, Streptococcus agalactiae, Streptococcus dysgalactiae, and Streptococcus uberis) found in milk samples. The DNA extraction method is based on the lysing and nuclease-inactivating properties of the chaotropic agent, guanidinium thiocyanate, together with the nucleic acid-binding properties of the silica particles. An efficient protocol consisting of 6 basic steps (3 of which were done twice) was developed and applied directly to milk samples. Absence of PCR inhibitors and DNA quality were evaluated by PCR amplification of the species-specific DNA sequences of the target bacteria. The level of sensitivity achieved in our experiments is applicable to milk sample analysis without sample enrichment.

  11. Rapid Directional Change Degrades GPS Distance Measurement Validity during Intermittent Intensity Running

    PubMed Central

    Rawstorn, Jonathan C.; Maddison, Ralph; Ali, Ajmol; Foskett, Andrew; Gant, Nicholas

    2014-01-01

    Use of the Global Positioning System (GPS) for quantifying athletic performance is common in many team sports. The effect of running velocity on measurement validity is well established, but the influence of rapid directional change is not well understood in team sport applications. This effect was systematically evaluated using multidirectional and curvilinear adaptations of a validated soccer simulation protocol that maintained identical velocity profiles. Team sport athletes completed 90 min trials of the Loughborough Intermittent Shuttle-running Test movement pattern on curvilinear, and multidirectional shuttle running tracks while wearing a 5 Hz (with interpolated 15 Hz output) GPS device. Reference total distance (13 200 m) was systematically over- and underestimated during curvilinear (2.61±0.80%) and shuttle (−3.17±2.46%) trials, respectively. Within-epoch measurement uncertainty dispersion was widest during the shuttle trial, particularly during the jog and run phases. Relative measurement reliability was excellent during both trials (Curvilinear r = 1.00, slope = 1.03, ICC = 1.00; Shuttle r = 0.99, slope = 0.97, ICC = 0.99). Absolute measurement reliability was superior during the curvilinear trial (Curvilinear SEM = 0 m, CV = 2.16%, LOA ± 223 m; Shuttle SEM = 119 m, CV = 2.44%, LOA ± 453 m). Rapid directional change degrades the accuracy and absolute reliability of GPS distance measurement, and caution is recommended when using GPS to quantify rapid multidirectional movement patterns. PMID:24733158

  12. Quinine directly determined in serum or urine by separation fluoroimmunoassay.

    PubMed

    Sidki, A M; Al-Abdulla, I H; Rowell, F J

    1987-04-01

    We developed and validated a magnetizable solid-phase fluoroimmunoassay for directly determining quinine in serum or urine. We prepared the immunogen by coupling quinine hemisuccinate to keyhole-limpet hemocyanine, using this to immunize three sheep, and coupling the antisera to magnetizable solid-phase particles to facilitate separation of bound antigen from interfering components of serum or urine. We tested the stability of two fluorescein-labeled derivatives of quinine--one prepared by direct conjugation of quinine to dichlorotriazenyl aminofluorescein, the other by conjugating quinine hemisuccinate to fluorescein thiocarbamyl ethylenediamine. The latter was unstable. Using the former label and an 30-min incubation, we saw no interference by quinidine (an enantiomer of quinine) or other antimalarial drugs at their therapeutic concentrations.

  13. Combination of SDS-PAGE and intact mass analysis for rapid determination of heterogeneities in monoclonal antibody therapeutics.

    PubMed

    Yamada, Hideaki; Matsumura, Chiemi; Yamada, Keita; Teshima, Koichiro; Hiroshima, Takashi; Kinoshita, Mitsuhiro; Suzuki, Shigeo; Kakehi, Kazuaki

    2017-05-01

    mAbs are currently mainstream in biopharmaceuticals, and their market has been growing due to their high target specificity. Characterization of heterogeneities in mAbs is performed to secure their quality and safety by physicochemical analyses. However, they require time-consuming task, which often strain the resources of drug development in pharmaceuticals. Rapid and direct method to determine the heterogeneities should be a powerful tool for pharmaceutical analysis. Considering the advantages of electrophoresis and MS, this study addresses the combination of SDS-PAGE and intact mass analysis, which provides direct, rapid, and orthogonal determination of heterogeneities in mAb therapeutics. mAb therapeutics that migrated in SDS-PAGE were recovered from gel by treatment with SDC-containing buffer. Usage of SDC-containing buffer as extraction solvent and ethanol-based staining solution enhanced the recovery of intact IgG from SDS-PAGE gels. Recovery of mAbs reached more than 86% with 0.2% SD. The heterogeneities, especially N-glycan variants in the recovered mAb therapeutics, were clearly determined by intact mass analysis. We believe that the study is important in pharmaceuticals‧ perspective since orthogonal combination of gel electrophoresis and intact mass analysis should be pivotal role for rapid and precise characterization of mAbs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. DPS - a rapid method for genome sequencing of DNA-containing bacteriophages directly from a single plaque.

    PubMed

    Kot, Witold; Vogensen, Finn K; Sørensen, Søren J; Hansen, Lars H

    2014-02-01

    Bacteriophages (phages) coexist with bacteria in all environments and influence microbial diversity, evolution and industrial production processes. As a result of this major impact of phages on microbes, tools that allow rapid characterization of phages are needed. Today, one of the most powerful methods for characterization of phages is determination of the whole genome using high throughput sequencing approaches. Here a direct plaque sequencing (DPS) is described, which is a rapid method that allows easy full genome sequencing of DNA-containing phages using the Nextera XT™ kit. A combination of host-DNA removal followed by purification and concentration of the viral DNA, allowed the construction of Illumina-compatible sequencing libraries using the Nextera™ XT technology directly from single phage plaques without any whole genome amplification step. This method was tested on three Caudovirales phages; ϕ29 Podoviridae, P113g Siphoviridae and T4 Myovirdae, which are representative of >96% of all known phages, and were sequenced using the Illumina MiSeq platform. Successful de novo assembly of the viral genomes was possible. Copyright © 2013 Elsevier B.V. All rights reserved.

  15. An immunomagnetic separation/loop-mediated isothermal amplification method for rapid direct detection of thermotolerant Campylobacter spp. during poultry production.

    PubMed

    Romero, M R; D'Agostino, M; Arias, A Pérez; Robles, S; Casado, C Fernández; Iturbe, L Orueta; Lerma, O Gurrutxaga; Andreou, M; Cook, N

    2016-02-01

    To develop a rapid test for thermotolerant Campylobacter in poultry faeces. The reported method is based on immunomagnetic separation and loop-mediated isothermal DNA amplification (IMS/LAMP). This LAMP assay is specific (demonstrated using 10 Campylobacter strains and 13 non-Campylobacter bacterial species) and sensitive (95% probability of detecting 22 genome copies). A competitive internal amplification control (IAC) has been incorporated to give unambiguous determination of negative results. Immunoseparation of Campylobacter allows direct LAMP detection from poultry boot swab samples in 90 min without enrichment or DNA purification (74% probability of detecting 10(4) CFU ml(-1) of a boot swab suspension). The analysis of 17 samples from commercial turkey farms showed 100% correlation with parallel results obtained by standard microbiological methods. A rapid test has been developed for direct detection of thermotolerant Campylobacter spp. in boot swab samples, thus bypassing culture enrichment or DNA extraction. The test has potential to be carried out by farm personnel on site. The method offers an inexpensive approach to monitor poultry infection in near real time, assisting flock management and controls to prevent introduction of Campylobacter into the food chain. © 2015 The Society for Applied Microbiology.

  16. Rapid and simultaneous determination of Strontium-89 and Strontium-90 in seawater.

    PubMed

    Tayeb, Michelle; Dai, Xiongxin; Sdraulig, Sandra

    2016-03-01

    A rapid method has been developed for the direct determination of radiostrontium ((89)Sr and (90)Sr) released in seawater in the early phase of an accident. The method employs a fast and effective pre-concentration of radiostrontium by Sr-Ca co-precipitation followed by separation of radiostrontium using extraction chromatography technique. Radiostrontium is effectively separated in the presence of excessive dominant salts of seawater. Čerenkov and liquid scintillation assay (LSA) techniques are used to determine (89)Sr and (90)Sr. Sample preparation time is approximately 4 h for a set of 10 samples. The method was validated using spiked seawater samples at various activity ratios of (89)Sr:(90)Sr ranging from 1:10 to 9:1. The mean chemical recovery of Sr was 85 ± 3%. (90)Sr showed variable relative bias which enhanced with increasing ratio of (89)Sr:(90)Sr and was in the range ± 21%. The highest biases of (90)Sr determination were due to lower activity concentrations of (90)Sr and are regarded as acceptable in emergency situations with elevated levels of radiostrontium in the sample. The minimum detectable concentration (MDC) of (90)Sr and (89)Sr varied at different (89)Sr:(90)Sr ratios. For 0.1 L seawater and 15 min counting time on a low background Hidex liquid scintillation counter (LSC), the MDC of (90)Sr was in the range of 1.7-3.5 Bq L(-1) and MDC of (89)Sr was in the range 0.5-2.4 Bq L(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. System for controllable magnetic measurement with direct field determination

    NASA Astrophysics Data System (ADS)

    Stupakov, O.

    2012-02-01

    This work describes a specially designed setup for magnetic hysteresis and Barkhausen noise measurements. The setup combines two main elements: an improved fast algorithm to control the waveform of magnetic induction and simultaneous direct determination of the magnetic field. The digital feedback algorithm uses only the previous measurement cycle to correct the magnetization voltage without any additional correlation parameter; it usually converges after several tens of cycles. The magnetic field is measured at the sample surface using a vertically mounted array of sensitive Hall sensors. Linear extrapolation of the tangential field profile to the sample surface determines the true waveform of the magnetic field. This unique combination of physically based control for both parameters of the magnetization process provides stable and reliable results, which are independent of a specified experimental configuration. This is illustrated for the industrially attractive measurements of non-oriented electrical steels with a 50 Hz sinusoidal induction waveform.

  18. Determination of sheep learning responses to a directional audio cue.

    PubMed

    Morris, Jessica E; Fisher, Andrew D; Doyle, Rebecca E; Bush, Russell D

    2010-01-01

    There are scientific opinions that a nonhuman animal cannot feel emotions, and, hence, positive experiences, without being cognitive. Therefore, determining an animal's cognitive capacity can be useful in supporting the existence of emotions. Research shows that sheep can perform tasks based on olfactory and visual stimuli; however, little research exists on determining the ability of sheep to perform such tasks based on auditory cues. This study demonstrates that sheep can perform a discriminant, operant task based on a visual cue (p < .001); however, sheep could not exhibit the desired response to a directional audio cue in 2 subsequent studies (p = .346; p = .031). Nonetheless, the study provides further evidence on the complex cognitive abilities of sheep and indicates the potential for sheep to use audio cues in their learning.

  19. [Rapid determination of total phosphorus by ultrasonic assisted sample digestion-spectrum analysis].

    PubMed

    Wei, Kang-Lin; Wang, Fei; Chen, Ming; Wen, Zhi-Yu; Mo, Zhi-Hong

    2014-01-01

    Aiming at the technological shortage of national standard method for the determination of total phosphorus, a rapid determination method of total phosphorus based on ultrasonic assisted sample digestion-spectrum analysis was put forward, and the on-line analysis experiment system was designed. Relying on the experiment system, the experimental method and technology was studied. In view of the actual environmental water samples, contrast test experiment with the national standard method for determination method of total phosphorus was carried on. The experimental results showed that the digestion rate of ultrasonic assisted sample digestion using fenton reagents could reach 97%-100% in 13.5 minutes, and the determination method could complete one copy of sample analysis within 16 minutes. This determination method can solve national standard method's technical problems. All of this research work provides the important experimental basis and technical support for the development of the rapid on-line monitoring instrument for determination of total phosphorus.

  20. Rapid directed evolution of stabilized proteins with cellular high-throughput encapsulation solubilization and screening (CHESS).

    PubMed

    Yong, K J; Scott, D J

    2015-03-01

    Directed evolution is a powerful method for engineering proteins towards user-defined goals and has been used to generate novel proteins for industrial processes, biological research and drug discovery. Typical directed evolution techniques include cellular display, phage display, ribosome display and water-in-oil compartmentalization, all of which physically link individual members of diverse gene libraries to their translated proteins. This allows the screening or selection for a desired protein function and subsequent isolation of the encoding gene from diverse populations. For biotechnological and industrial applications there is a need to engineer proteins that are functional under conditions that are not compatible with these techniques, such as high temperatures and harsh detergents. Cellular High-throughput Encapsulation Solubilization and Screening (CHESS), is a directed evolution method originally developed to engineer detergent-stable G proteins-coupled receptors (GPCRs) for structural biology. With CHESS, library-transformed bacterial cells are encapsulated in detergent-resistant polymers to form capsules, which serve to contain mutant genes and their encoded proteins upon detergent mediated solubilization of cell membranes. Populations of capsules can be screened like single cells to enable rapid isolation of genes encoding detergent-stable protein mutants. To demonstrate the general applicability of CHESS to other proteins, we have characterized the stability and permeability of CHESS microcapsules and employed CHESS to generate thermostable, sodium dodecyl sulfate (SDS) resistant green fluorescent protein (GFP) mutants, the first soluble proteins to be engineered using CHESS.

  1. Rapid Method for the Determination of the Stable Oxygen Isotope Ratio of Water in Alcoholic Beverages.

    PubMed

    Wang, Daobing; Zhong, Qiding; Li, Guohui; Huang, Zhanbin

    2015-10-28

    This paper demonstrates the first successful application of an online pyrolysis technique for the direct determination of oxygen isotope ratios (δ(18)O) of water in alcoholic beverages. Similar water concentrations in each sample were achieved by adjustment with absolute ethyl alcohol, and then a fixed GC split ratio can be used. All of the organic ingredients were successfully separated from the analyte on a CP-PoraBond Q column and subsequently vented out, whereas water molecules were transferred into the reaction furnace and converted to CO. With the system presented, 15-30 μL of raw sample was diluted and can be analyzed repeatedly; the analytical precision was better than 0.4‰ (n = 5) in all cases, and more than 50 injections can be made per day. No apparent memory effect was observed even if water samples were injected using the same syringe; a strong correlation (R(2) = 0.9998) was found between the water δ(18)O of measured sample and that of working standards. There was no significant difference (p > 0.05) between the mean δ(18)O value and that obtained by the traditional method (CO2-water equilibration/isotope ratio mass spectrometry) and the newly developed method in this study. The advantages of this new method are its rapidity and straightforwardness, and less test portion is required.

  2. Determination of very rapid molecular rotation by using the central electron paramagnetic resonance line.

    PubMed

    Kurban, Mark R

    2013-02-21

    Picosecond rotational correlation times of perdeuterated tempone (PDT) are found in alkane and aromatic liquids by directly using the spectral width of the central electron paramagnetic resonance line. This is done by mathematically eliminating the nonsecular spectral density from the spectral parameter equations, thereby removing the need to assume a particular form for it. This is preferable to fitting a constant correction factor to the spectral density, because such a factor does not fit well in the low picosecond range. The electron-nuclear spin dipolar interaction between the probe and solvent is shown to be negligible for the very rapid rotation of PDT in these liquids at the temperatures of the study. The rotational correlation times obtained with the proposed method generally agree to within experimental uncertainty with those determined by using the traditional parameters. Using the middle line width offers greater precision and smoother trends. Previous work with the central line width is discussed, and past discrepancies are explained as possibly resulting from residual inhomogeneous broadening. The rotational correlation time almost forms a common curve across all of the solvents when plotted with respect to isothermal compressibility, which shows the high dependence of rotation on liquid free volume.

  3. Rapid determination of picomolar titanium in seawater with catalytic cathodic stripping voltammetry.

    PubMed

    Croot, Peter L

    2011-08-15

    Titanium (Ti) is present as a trace element in seawater at extremely low concentrations (5-350 pM, where 1 pM = 10(-12) mol L(-1)) throughout the water column. Presently, little is known about the marine biogeochemistry of Ti and there is a distinct lack of oceanic measurements of Ti , because of the combined difficulties of trace-metal clean sampling for an element at such low levels and the lack of a suitable shipboard method of analysis. Here, a new cathodic stripping voltammetry procedure is presented for the rapid determination of Ti at pM concentrations in seawater that is capable of being used directly at sea. This method utilizes the catalytic enhancement of the reduction of the complex formed between Cupferron (N-nitrosophenylhydroxylamine) and Ti(IV). While Cupferron itself acts as both a complexing agent and an oxidizing agent, it was found that the optimal sensitivity was with bromate as an auxiliary oxidant. An advantage of this method is that it is useable over the pH range of 5.5-8. Under the conditions employed in this work, detection limits ranged from 5 pM to 12 pM. This new catalytic method is significantly more sensitive than existing methods and has been extensively tested at sea in the Atlantic and Southern Oceans.

  4. Advances in direct and diffraction methods for surface structural determination

    NASA Astrophysics Data System (ADS)

    Tong, S. Y.

    1999-08-01

    I describe recent advances in low-energy electron diffraction holography and photoelectron diffraction holography. These are direct methods for determining the surface structure. I show that for LEED and PD spectra taken in an energy and angular mesh, the relative phase between the reference wave and the scattered wave has a known geometric form if the spectra are always taken from within a small angular cone in the near backscattering direction. By using data in the backscattering small cone at each direction of interest, a simple algorithm is developed to invert the spectra and extract object atomic positions with no input of calculated dynamic factors. I also describe the use of a convergent iterative method of PD and LEED. The computation time of this method scales as N2, where N is the dimension of the propagator matrix, rather than N3 as in conventional Gaussian substitutional methods. Both the Rehr-Albers separable-propagator cluster approach and the slab-type non-separable approach can be cast in the new iterative form. With substantial savings in computational time and no loss in numerical accuracy, this method is very useful in applications of multiple scattering theory, particularly for systems involving either very large unit cells (>300 atoms) or where no long-range order is present.

  5. Marsh frogs, Pelophylax ridibundus, determine migratory direction by magnetic field.

    PubMed

    Shakhparonov, Vladimir V; Ogurtsov, Sergei V

    2017-01-01

    Orientation by magnetic cues appears to be adaptive during animal migrations. Whereas the magnetic orientation in birds, mammals, and urodele amphibians is being investigated intensively, the data about anurans are still scarce. This study tests whether marsh frogs could determine migratory direction between the breeding pond and the wintering site by magnetic cues in the laboratory. Adult frogs (N = 32) were individually tested in the T-maze 127 cm long inside the three-axis Helmholtz coil system (diameter 3 m). The arms of the maze were positioned parallel to the natural migratory route of this population when measured in accordance with magnetic field. The frogs were tested under two-motivational conditions mediated by temperature/light regime: the breeding migratory state and the wintering state. The frogs' choice in a T-maze was evident only when analyzed in accordance with the direction of the magnetic field: they moved along the migratory route to the breeding pond and followed the reversion of the horizontal component of the magnetic field. This preference has been detected in both sexes only in the breeding migratory state. This suggests that adult ranid frogs can obtain directional information from the Earth's magnetic field as was shown earlier in urodeles and anuran larvae.

  6. Direct comparison between confocal and multiphoton microscopy for rapid histopathological evaluation of unfixed human breast tissue

    NASA Astrophysics Data System (ADS)

    Yoshitake, Tadayuki; Giacomelli, Michael G.; Cahill, Lucas C.; Schmolze, Daniel B.; Vardeh, Hilde; Faulkner-Jones, Beverly E.; Connolly, James L.; Fujimoto, James G.

    2016-12-01

    Rapid histopathological examination of surgical specimen margins using fluorescence microscopy during breast conservation therapy has the potential to reduce the rate of positive margins on postoperative histopathology and the need for repeat surgeries. To assess the suitability of imaging modalities, we perform a direct comparison between confocal fluorescence microscopy and multiphoton microscopy for imaging unfixed tissue and compare to paraffin-embedded histology. An imaging protocol including dual channel detection of two contrast agents to implement virtual hematoxylin and eosin images is introduced that provides high quality imaging under both one and two photon excitation. Corresponding images of unfixed human breast tissue show that both confocal and multiphoton microscopy can reproduce the appearance of conventional histology without the need for physical sectioning. We further compare normal breast tissue and invasive cancer specimens imaged at multiple magnifications, and assess the effects of photobleaching for both modalities using the staining protocol. The results demonstrate that confocal fluorescence microscopy is a promising and cost-effective alternative to multiphoton microscopy for rapid histopathological evaluation of ex vivo breast tissue.

  7. A General-applications Direct Global Matrix Algorithm for Rapid Seismo-acoustic Wavefield Computations

    NASA Technical Reports Server (NTRS)

    Schmidt, H.; Tango, G. J.; Werby, M. F.

    1985-01-01

    A new matrix method for rapid wave propagation modeling in generalized stratified media, which has recently been applied to numerical simulations in diverse areas of underwater acoustics, solid earth seismology, and nondestructive ultrasonic scattering is explained and illustrated. A portion of recent efforts jointly undertaken at NATOSACLANT and NORDA Numerical Modeling groups in developing, implementing, and testing a new fast general-applications wave propagation algorithm, SAFARI, formulated at SACLANT is summarized. The present general-applications SAFARI program uses a Direct Global Matrix Approach to multilayer Green's function calculation. A rapid and unconditionally stable solution is readily obtained via simple Gaussian ellimination on the resulting sparsely banded block system, precisely analogous to that arising in the Finite Element Method. The resulting gains in accuracy and computational speed allow consideration of much larger multilayered air/ocean/Earth/engineering material media models, for many more source-receiver configurations than previously possible. The validity and versatility of the SAFARI-DGM method is demonstrated by reviewing three practical examples of engineering interest, drawn from ocean acoustics, engineering seismology and ultrasonic scattering.

  8. An automated robotic platform for rapid profiling oligosaccharide analysis of monoclonal antibodies directly from cell culture.

    PubMed

    Doherty, Margaret; Bones, Jonathan; McLoughlin, Niaobh; Telford, Jayne E; Harmon, Bryan; DeFelippis, Michael R; Rudd, Pauline M

    2013-11-01

    Oligosaccharides attached to Asn297 in each of the CH2 domains of monoclonal antibodies play an important role in antibody effector functions by modulating the affinity of interaction with Fc receptors displayed on cells of the innate immune system. Rapid, detailed, and quantitative N-glycan analysis is required at all stages of bioprocess development to ensure the safety and efficacy of the therapeutic. The high sample numbers generated during quality by design (QbD) and process analytical technology (PAT) create a demand for high-performance, high-throughput analytical technologies for comprehensive oligosaccharide analysis. We have developed an automated 96-well plate-based sample preparation platform for high-throughput N-glycan analysis using a liquid handling robotic system. Complete process automation includes monoclonal antibody (mAb) purification directly from bioreactor media, glycan release, fluorescent labeling, purification, and subsequent ultra-performance liquid chromatography (UPLC) analysis. The entire sample preparation and commencement of analysis is achieved within a 5-h timeframe. The automated sample preparation platform can easily be interfaced with other downstream analytical technologies, including mass spectrometry (MS) and capillary electrophoresis (CE), for rapid characterization of oligosaccharides present on therapeutic antibodies. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Rapid direct identification of Cryptococcus neoformans from pigeon droppings by nested PCR using CNLAC1 gene.

    PubMed

    Chae, H S; Park, G N; Kim, S H; Jo, H J; Kim, J T; Jeoung, H Y; An, D J; Kim, N H; Shin, B W; Kang, Y I; Chang, K S

    2012-08-01

    Isolation and identification of Cryptococcus neoformans and pathogenic yeast-like fungi from pigeon droppings has been taken for a long time and requires various nutrients for its growth. In this study, we attempted to establish a rapid direct identification method of Cr. neoformans from pigeon dropping samples by nested-PCR using internal transcribed spacer (ITS) CAP64 and CNLAC1 genes, polysaccharide capsule gene and laccase-associated gene to produce melanin pigment, respectively, which are common genes of yeasts. The ITS and CAP64 genes were amplified in all pathogenic yeasts, but CNLAC1 was amplified only in Cr. neoformans. The ITS gene was useful for yeast genotyping depending on nucleotide sequence. Homology of CAP64 genes among the yeasts were very high. The specificity of PCR using CNLAC1 was demonstrated in Cr. neoformans environmental strains but not in other yeast-like fungi. The CNLAC1 gene was detected in 5 serotypes of Cr. neoformans. The nested-PCR amplified up to 10(-11) μg of the genomic DNA and showed high sensitivity. All pigeon droppings among 31 Cr. neoformans-positive samples were positive and all pigeon droppings among 348 Cr. neoformans-negative samples were negative by the direct nested-PCR. In addition, after primary enrichment of pigeon droppings in Sabouraud dextrose broth, all Cr. neoformans-negative samples were negative by the nested-PCR, which showed high specificity. The nested-PCR showed high sensitivity without culture of pigeon droppings. Nested-PCR using CNLAC1 provides a rapid and reliable molecular diagnostic method to overcome weak points such as long culture time of many conventional methods.

  10. Ultra-rapid laser protein micropatterning: screening for directed polarization of single neurons.

    PubMed

    Scott, Mark A; Wissner-Gross, Zachary D; Yanik, Mehmet Fatih

    2012-06-21

    Protein micropatterning is a powerful tool for studying the effects of extracellular signals on cell development and regeneration. Laser micropatterning of proteins is the most flexible method for patterning many different geometries, protein densities, and concentration gradients. Despite these advantages, laser micropatterning remains prohibitively slow for most applications. Here, we take advantage of the rapid multi-photon induced photobleaching of fluorophores to generate sub-micron resolution patterns of full-length proteins on polymer monolayers, with sub-microsecond exposure times, i.e. one to five orders of magnitude faster than all previous laser micropatterning methods. We screened a range of different PEG monolayer coupling chemistries, chain-lengths and functional caps, and found that long-chain acrylated PEG monolayers are effective at resisting non-specific protein adhesion, while permitting efficient cross-linking of biotin-4-fluorescein to the PEG monolayers upon exposure to femtosecond laser pulses. We find evidence that the dominant photopatterning chemistry switches from a two-photon process to three- and four-photon absorption processes as the laser intensity increases, generating increasingly volatile excited triplet-state fluorophores, leading to faster patterning. Using this technology, we were able to generate over a hundred thousand protein patterns with varying geometries and protein densities to direct the polarization of hippocampal neurons with single-cell precision. We found that certain arrays of patterned triangles as small as neurite growth cones can direct polarization by impeding the elongation of reverse-projecting neurites, while permitting elongation of forward-projecting neurites. The ability to rapidly generate and screen such protein micropatterns can enable discovery of conditions necessary to create in vitro neural networks with single-neuron precision for basic discovery, drug screening, as well as for tissue scaffolding

  11. Ultra-Rapid Laser Protein Micropatterning: Screening For Directed Polarization of Single Neurons

    PubMed Central

    Scott, Mark A.; Wissner-Gross, Zachary D.; Yanik, Mehmet Fatih

    2012-01-01

    Protein micropatterning is a powerful tool for studying the effects of extracellular signals on cell development and regeneration. Laser micropatterning of proteins is the most flexible method for patterning many different geometries, protein densities, and concentration gradients. Despite these advantages, laser micropatterning remains prohibitively slow for most applications. Here, we take advantage of the rapid multi-photon induced photobleaching of fluorophores to generate sub-micron resolution patterns of full-length proteins on polymer monolayers, with sub-microsecond exposure times, i.e. one to five orders of magnitude faster than all previous laser micropatterning methods. We screened a range of different PEG monolayer coupling chemistries, chain-lengths and functional caps, and found that long-chain acrylated PEG monolayers are effective at resisting non-specific protein adhesion, while permitting efficient cross-linking of biotin-4-fluorescein to the PEG monolayers upon exposure to femtosecond laser pulses. We find evidence that the dominant photopatterning chemistry switches from a two-photon process to three- and four-photon absorption processes as the laser intensity increases, generating increasingly volatile excited triplet-state fluorophores, leading to faster patterning. Using this technology, we were able to generate over a hundred thousand protein patterns with varying geometries and protein densities to direct the polarization of hippocampal neurons with single-cell precision. We found that certain arrays of patterned triangles as small as neurite growth cones can direct polarization by impeding the elongation of reverse-projecting neurites, while permitting elongation of forward-projecting neurites. The ability to rapidly generate and screen such protein micropatterns can enable discovery of conditions necessary to create in vitro neural networks with single-neuron precision for basic discovery, drug screening, as well as for tissue scaffolding

  12. Rapid Microcystin Determination Using a Paper Spray Ionization Method with a Time-of-Flight Mass Spectrometry System.

    PubMed

    Zhu, Xiaoqiang; Huang, Zhengxu; Gao, Wei; Li, Xue; Li, Lei; Zhu, Hui; Mo, Ting; Huang, Bao; Zhou, Zhen

    2016-07-13

    The eutrophication of surface water sources and climate changes have resulted in an annual explosion of cyanobacterial blooms in many irrigating and drinking water resources. To decrease health risks to the public, a rapid real time method for the synchronous determination of two usually harmful microcystins (MC-RR and MC-LR) in environmental water samples was built by employing a paper spray ionization method coupled with a time-of-flight mass spectrometer system. With this approach, direct analysis of microcystin mixtures without sample preparation has been achieved. Rapid detection was performed, simulating the release process of microcystins in reservoir water samples, and the routine detection frequency was every three minutes. The identification time of microcystins was reduced from several hours to a few minutes. The limit of detection is 1 μg/L, and the limit of quantitation is 3 μg/L. This method displays the ability for carrying out rapid, direct, and high-throughput experiments for determination of microcystins, and it would be of significant interest for environmental and food safety applications.

  13. A protocol for direct and rapid multiplex PCR amplification on forensically relevant samples.

    PubMed

    Verheij, Saskia; Harteveld, Joyce; Sijen, Titia

    2012-03-01

    Forensic DNA typing involves a multi-step workflow. Steps include DNA isolation, quantification, amplification of a set of short tandem repeat (STR) markers, separation of polymerase chain reaction (PCR) products by capillary electrophoresis (CE) and DNA profile analysis and interpretation. With that, the process takes around 10-12h. For several scenarios it may be very valuable to speed up this process and obtain an interpretable DNA profile, suited to search a DNA database, within a few hours. For instance in cases of national security, abduction with danger of life, risk of repetition by a serial perpetrator or when custody time of suspects is limited. By a direct and rapid PCR approach we reduced the total DNA profiling time to 2-3h after which genotyping information for the 10 STR markers plus the amelogenin (AMEL) marker present in the commercially available AmpFℓSTR(®) SGM Plus™ (SGM+) profiling kit is obtained. This reduction in time is achieved by using the following elements: (1) the inhibitor tolerant, highly processive Phusion(®) Flash DNA polymerase; (2) a modified, non-adenylated allelic ladder; (3) the quick PIKO(®) thermal cycler system with ultra-thin walled reaction tubes; (4) profile interpretation guidelines with an increased allele calling threshold, modified stutter ratios and marked low-level artefact peaks and (5) regulation of sample input by the use of mini-tapes that lift a limited amount of cell material from swabs or fabrics. The procedure is specifically effective for high level DNA, single source samples such as samples containing saliva, blood, semen and hair roots. Success rates, defined as a complete DNA profile, depend on stain type and surface. Due to the use of tape lifting as the sampling technique, the swab or fabric remains dry and intact and can be analyzed at a later stage using regular procedures. Validation experiments were performed which showed that the protocol effectively instructs researchers unfamiliar with

  14. Rapid determination of vitamin B12 concentration with a chemiluminescence lab on a chip.

    PubMed

    Lok, Khoi Seng; Abdul Muttalib, Siti Zubaidah binte; Lee, Peter Peng Foo; Kwok, Yien Chian; Nguyen, Nam-Trung

    2012-07-07

    This paper reports a novel method for the rapid determination of vitamin B(12) concentration in a continuous-flow lab-on-a-chip system. This new method is based on luminol-peroxide chemiluminescence (CL) assays for the detection of cobalt(II) ions in vitamin B(12) molecules. The lab-on-a-chip device consisted of two passive micromixers acting as microreactors and a double spiral microchannel network serving as an optical detection region. This system could operate in two modes. In the first mode, samples are acidified and evaluated directly in the microchip. In the second mode, samples are treated externally by acidification prior to detection in the microchip. In the first mode, the linear range obtained was between 1.00 ng ml(-1) to 10 μg ml(-1), R(2) = 0.996, with a relative standard deviation (RSD) of 1.23 to 2.31% (n = 5) and a limit of detection (lod) of 0.368 pg ml(-1). The minimum sample volume required and the analytical time were 30 μl and 3.6 s, respectively. In the second mode, the linear range obtained was between 0.10 ng ml(-1) to 10 μg ml(-1), R(2) = 0.994, with the RSD of 0.90 to 2.32% (n = 6) and a lod of 0.576 pg ml(-1). The minimum sample and the analytical time required were 50 μl and 6 s, respectively. The lab on a chip working in mode II was successfully used for the determination of vitamin B(12) concentrations in nutritional supplemental tablets and hen egg yolks.

  15. Development of a new protocol for rapid bacterial identification and susceptibility testing directly from urine samples.

    PubMed

    Zboromyrska, Y; Rubio, E; Alejo, I; Vergara, A; Mons, A; Campo, I; Bosch, J; Marco, F; Vila, J

    2016-06-01

    The current gold standard method for the diagnosis of urinary tract infections (UTI) is urine culture that requires 18-48 h for the identification of the causative microorganisms and an additional 24 h until the results of antimicrobial susceptibility testing (AST) are available. The aim of this study was to shorten the time of urine sample processing by a combination of flow cytometry for screening and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) for bacterial identification followed by AST directly from urine. The study was divided into two parts. During the first part, 675 urine samples were processed by a flow cytometry device and a cut-off value of bacterial count was determined to select samples for direct identification by MALDI-TOF-MS at ≥5 × 10(6) bacteria/mL. During the second part, 163 of 1029 processed samples reached the cut-off value. The sample preparation protocol for direct identification included two centrifugation and two washing steps. Direct AST was performed by the disc diffusion method if a reliable direct identification was obtained. Direct MALDI-TOF-MS identification was performed in 140 urine samples; 125 of the samples were positive by urine culture, 12 were contaminated and 3 were negative. Reliable direct identification was obtained in 108 (86.4%) of the 125 positive samples. AST was performed in 102 identified samples, and the results were fully concordant with the routine method among 83 monomicrobial infections. In conclusion, the turnaround time of the protocol described to diagnose UTI was about 1 h for microbial identification and 18-24 h for AST.

  16. Rapid changes in gene expression direct rapid shifts in intestinal form and function in the Burmese python after feeding.

    PubMed

    Andrew, Audra L; Card, Daren C; Ruggiero, Robert P; Schield, Drew R; Adams, Richard H; Pollock, David D; Secor, Stephen M; Castoe, Todd A

    2015-05-01

    Snakes provide a unique and valuable model system for studying the extremes of physiological remodeling because of the ability of some species to rapidly upregulate organ form and function upon feeding. The predominant model species used to study such extreme responses has been the Burmese python because of the extreme nature of postfeeding response in this species. We analyzed the Burmese python intestine across a time series, before, during, and after feeding to understand the patterns and timing of changes in gene expression and their relationship to changes in intestinal form and function upon feeding. Our results indicate that >2,000 genes show significant changes in expression in the small intestine following feeding, including genes involved in intestinal morphology and function (e.g., hydrolases, microvillus proteins, trafficking and transport proteins), as well as genes involved in cell division and apoptosis. Extensive changes in gene expression occur surprisingly rapidly, within the first 6 h of feeding, coincide with changes in intestinal morphology, and effectively return to prefeeding levels within 10 days. Collectively, our results provide an unprecedented portrait of parallel changes in gene expression and intestinal morphology and physiology on a scale that is extreme both in the magnitude of changes, as well as in the incredibly short time frame of these changes, with up- and downregulation of expression and function occurring in the span of 10 days. Our results also identify conserved vertebrate signaling pathways that modulate these responses, which may suggest pathways for therapeutic modulation of intestinal function in humans.

  17. Rapid changes in gene expression direct rapid shifts in intestinal form and function in the Burmese python after feeding

    PubMed Central

    Andrew, Audra L.; Card, Daren C.; Ruggiero, Robert P.; Schield, Drew R.; Adams, Richard H.; Pollock, David D.; Secor, Stephen M.

    2015-01-01

    Snakes provide a unique and valuable model system for studying the extremes of physiological remodeling because of the ability of some species to rapidly upregulate organ form and function upon feeding. The predominant model species used to study such extreme responses has been the Burmese python because of the extreme nature of postfeeding response in this species. We analyzed the Burmese python intestine across a time series, before, during, and after feeding to understand the patterns and timing of changes in gene expression and their relationship to changes in intestinal form and function upon feeding. Our results indicate that >2,000 genes show significant changes in expression in the small intestine following feeding, including genes involved in intestinal morphology and function (e.g., hydrolases, microvillus proteins, trafficking and transport proteins), as well as genes involved in cell division and apoptosis. Extensive changes in gene expression occur surprisingly rapidly, within the first 6 h of feeding, coincide with changes in intestinal morphology, and effectively return to prefeeding levels within 10 days. Collectively, our results provide an unprecedented portrait of parallel changes in gene expression and intestinal morphology and physiology on a scale that is extreme both in the magnitude of changes, as well as in the incredibly short time frame of these changes, with up- and downregulation of expression and function occurring in the span of 10 days. Our results also identify conserved vertebrate signaling pathways that modulate these responses, which may suggest pathways for therapeutic modulation of intestinal function in humans. PMID:25670730

  18. Rapid, Time-Division Multiplexed, Direct Absorption- and Wavelength Modulation-Spectroscopy

    PubMed Central

    Klein, Alexander; Witzel, Oliver; Ebert, Volker

    2014-01-01

    We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique combines the benefits of absolute concentration measurements using calibration-free direct tunable diode laser absorption spectroscopy (dTDLAS) with the enhanced noise rejection of wavelength modulation spectroscopy (WMS). In this work we demonstrate for the first time a 125 Hz time division multiplexed (TDM-dTDLAS-WMS) spectroscopic scheme by alternating the modulation of a DFB-laser between a triangle-ramp (dTDLAS) and an additional 20 kHz sinusoidal modulation (WMS). The absolute concentration measurement via the dTDLAS-technique allows one to simultaneously calibrate the normalized 2f/1f-signal of the WMS-technique. A dTDLAS/WMS-spectrometer at 1.37 μm for H2O detection was built for experimental validation of the multiplexing scheme over a concentration range from 50 to 3000 ppmV (0.1 MPa, 293 K). A precision of 190 ppbV was achieved with an absorption length of 12.7 cm and an averaging time of two seconds. Our results show a five-fold improvement in precision over the entire concentration range and a significantly decreased averaging time of the spectrometer. PMID:25405508

  19. Piezoelectric immunosensor for direct and rapid detection of staphylococcal enterotoxin A (SEA) at the ng level.

    PubMed

    Salmain, Michèle; Ghasemi, Mahsa; Boujday, Souhir; Spadavecchia, Jolanda; Técher, Clarisse; Val, Florence; Le Moigne, Vincent; Gautier, Michel; Briandet, Romain; Pradier, Claire-Marie

    2011-11-15

    A direct, label-free immunosensor was designed for the rapid detection and quantification of staphylococcal enterotoxin A (SEA) in buffered solutions using quartz crystal microbalance with dissipation (QCM-D) as transduction method. The sensing layer including the anti-SEA antibody was constructed by chemisorption of a self-assembled monolayer of cysteamine on the gold electrodes placed over the quartz crystal sensor followed by activation of the surface amino groups with the rigid homobifunctional cross-linker 1,4-phenylene diisothiocyanate (PDITC) and covalent linking of binding protein (protein A or protein G). Four anti-SEA antibodies (two of which from commercial source) have been selected to set up the most sensitive detection device. With the optimized sensing layer, a standard curve for the direct assay of SEA was established from QCM-D responses within a working range of 50-1000 or 2000 ngml(-1) with a detection limit of 20 ngml(-1). The total time for analysis was 15 min. Using a sandwich type assay, the response was ca. twice higher and consequently the lowest measurable concentration dropped down to 7 ngml(-1) for a total assay time of 25 min.

  20. Rapid detection of haloarchaeal carotenoids via liquid-liquid microextraction enabled direct TLC MALDI-MS.

    PubMed

    Manikandan, Muthu; Hasan, Nazim; Wu, Hui-Fen

    2013-03-30

    For the first time, we demonstrate the use of TiO2 nanoparticles (NPs) for enhancing the carotenoid production by the extremophilic haloarchea, Haloferax mediterranei. TiO2 NPs at optimal concentration of 375 mg/L results in a 95% increase in the production of carotenoid pigment compared to the control (no TiO2 NPs). The carotenoid pigments extracted from TiO2 NPs treated H. mediterranei cells, were separated using thin layer chromatography (TLC). The separated carotenoid spots were subjected directly for MALDI MS detection. To limit the sample diffusion during matrix addition on TLC plates, a simple bordering mode was exercised. Using this method we were able to detect the pigments successfully using MALDI-MS, directly from TLC plates after separation. In addition, we also applied the Pt NPs capped with ODT via Liquid-liquid microextraction (LLME) for extracting the pigment molecules from the halobacteria in MALDI-MS. These novel NP approaches possess numerous advantages such as; rapidity, ease in synthesis, high sensitivity and low cost.

  1. Digital Direct-to-Consumer Advertising: A Perfect Storm of Rapid Evolution and Stagnant Regulation

    PubMed Central

    Mackey, Tim K.

    2016-01-01

    The adoption and use of digital forms of direct-to-consumer advertising (also known as "eDTCA") is on the rise. At the same time, the universe of eDTCA is expanding, as technology on Internet-based platforms continues to evolve, from static websites, to social media, and nearly ubiquitous use of mobile devices. However, little is known about how this unique form of pharmaceutical marketing impacts consumer behavior, public health, and overall healthcare utilization. The study by Kim analyzing US Food and Drug Administration (FDA) notices of violations (NOVs) and warning letters regarding online promotional activities takes us in the right direction, but study results raise as many questions as it does answers. Chief among these are unanswered concerns about the unique regulatory challenges posed by the "disruptive" qualities of eDTCA, and whether regulators have sufficient resources and oversight powers to proactively address potential violations. Further, the globalization of eDTCA via borderless Internet-based technologies raises larger concerns about the potential global impact of this form of health marketing unique to only the United States and New Zealand. Collectively, these challenges make it unlikely that regulatory science will be able to keep apace with the continued rapid evolution of eDTCA unless more creative policy solutions are explored. PMID:27239871

  2. Sensitive and rapid detection of Chlamydia trachomatis by recombinase polymerase amplification directly from urine samples.

    PubMed

    Krõlov, Katrin; Frolova, Jekaterina; Tudoran, Oana; Suhorutsenko, Julia; Lehto, Taavi; Sibul, Hiljar; Mäger, Imre; Laanpere, Made; Tulp, Indrek; Langel, Ülo

    2014-01-01

    Chlamydia trachomatis is the most common sexually transmitted human pathogen. Infection results in minimal to no symptoms in approximately two-thirds of women and therefore often goes undiagnosed. C. trachomatis infections are a major public health concern because of the potential severe long-term consequences, including an increased risk of ectopic pregnancy, chronic pelvic pain, and infertility. To date, several point-of-care tests have been developed for C. trachomatis diagnostics. Although many of them are fast and specific, they lack the required sensitivity for large-scale application. We describe a rapid and sensitive form of detection directly from urine samples. The assay uses recombinase polymerase amplification and has a minimum detection limit of 5 to 12 pathogens per test. Furthermore, it enables detection within 20 minutes directly from urine samples without DNA purification before the amplification reaction. Initial analysis of the assay from clinical patient samples had a specificity of 100% (95% CI, 92%-100%) and a sensitivity of 83% (95% CI, 51%-97%). The whole procedure is fairly simple and does not require specific machinery, making it potentially applicable in point-of-care settings.

  3. Direct typing of Canine parvovirus (CPV) from infected dog faeces by rapid mini sequencing technique.

    PubMed

    V, Pavana Jyothi; S, Akila; Selvan, Malini K; Naidu, Hariprasad; Raghunathan, Shwethaa; Kota, Sathish; Sundaram, R C Raja; Rana, Samir Kumar; Raj, G Dhinakar; Srinivasan, V A; Mohana Subramanian, B

    2016-12-01

    Canine parvovirus (CPV) is a non-enveloped single stranded DNA virus with an icosahedral capsid. Mini-sequencing based CPV typing was developed earlier to detect and differentiate all the CPV types and FPV in a single reaction. This technique was further evaluated in the present study by performing the mini-sequencing directly from fecal samples which avoided tedious virus isolation steps by cell culture system. Fecal swab samples were collected from 84 dogs with enteritis symptoms, suggestive of parvoviral infection from different locations across India. Seventy six of these samples were positive by PCR; the subsequent mini-sequencing reaction typed 74 of them as type 2a virus, and 2 samples as type 2b. Additionally, 25 of the positive samples were typed by cycle sequencing of PCR products. Direct CPV typing from fecal samples using mini-sequencing showed 100% correlation with CPV typing by cycle sequencing. Moreover, CPV typing was achieved by mini-sequencing even with faintly positive PCR amplicons which was not possible by cycle sequencing. Therefore, the mini-sequencing technique is recommended for regular epidemiological follow up of CPV types, since the technique is rapid, highly sensitive and high capacity method for CPV typing.

  4. Rapid, time-division multiplexed, direct absorption- and wavelength modulation-spectroscopy.

    PubMed

    Klein, Alexander; Witzel, Oliver; Ebert, Volker

    2014-11-14

    We present a tunable diode laser spectrometer with a novel, rapid time multiplexed direct absorption- and wavelength modulation-spectroscopy operation mode. The new technique allows enhancing the precision and dynamic range of a tunable diode laser absorption spectrometer without sacrificing accuracy. The spectroscopic technique combines the benefits of absolute concentration measurements using calibration-free direct tunable diode laser absorption spectroscopy (dTDLAS) with the enhanced noise rejection of wavelength modulation spectroscopy (WMS). In this work we demonstrate for the first time a 125 Hz time division multiplexed (TDM-dTDLAS-WMS) spectroscopic scheme by alternating the modulation of a DFB-laser between a triangle-ramp (dTDLAS) and an additional 20 kHz sinusoidal modulation (WMS). The absolute concentration measurement via the dTDLAS-technique allows one to simultaneously calibrate the normalized 2f/1f-signal of the WMS-technique. A dTDLAS/WMS-spectrometer at 1.37 µm for H2O detection was built for experimental validation of the multiplexing scheme over a concentration range from 50 to 3000 ppmV (0.1 MPa, 293 K). A precision of 190 ppbV was achieved with an absorption length of 12.7 cm and an averaging time of two seconds. Our results show a five-fold improvement in precision over the entire concentration range and a significantly decreased averaging time of the spectrometer.

  5. Direct determination of phosphatase activity from physiological substrates in cells.

    PubMed

    Ren, Zhongyuan; Do, Le Duy; Bechkoff, Géraldine; Mebarek, Saida; Keloglu, Nermin; Ahamada, Saandia; Meena, Saurabh; Magne, David; Pikula, Slawomir; Wu, Yuqing; Buchet, René

    2015-01-01

    A direct and continuous approach to determine simultaneously protein and phosphate concentrations in cells and kinetics of phosphate release from physiological substrates by cells without any labeling has been developed. Among the enzymes having a phosphatase activity, tissue non-specific alkaline phosphatase (TNAP) performs indispensable, multiple functions in humans. It is expressed in numerous tissues with high levels detected in bones, liver and neurons. It is absolutely required for bone mineralization and also necessary for neurotransmitter synthesis. We provided the proof of concept that infrared spectroscopy is a reliable assay to determine a phosphatase activity in the osteoblasts. For the first time, an overall specific phosphatase activity in cells was determined in a single step by measuring simultaneously protein and substrate concentrations. We found specific activities in osteoblast like cells amounting to 116 ± 13 nmol min(-1) mg(-1) for PPi, to 56 ± 11 nmol min(-1) mg(-1) for AMP, to 79 ± 23 nmol min(-1) mg(-1) for beta-glycerophosphate and to 73 ± 15 nmol min(-1) mg(-1) for 1-alpha-D glucose phosphate. The assay was also effective to monitor phosphatase activity in primary osteoblasts and in matrix vesicles. The use of levamisole--a TNAP inhibitor--served to demonstrate that a part of the phosphatase activity originated from this enzyme. An IC50 value of 1.16 ± 0.03 mM was obtained for the inhibition of phosphatase activity of levamisole in osteoblast like cells. The infrared assay could be extended to determine any type of phosphatase activity in other cells. It may serve as a metabolomic tool to monitor an overall phosphatase activity including acid phosphatases or other related enzymes.

  6. Direct Determination of the Intracellular Oxidation State of Plutonium

    PubMed Central

    Gorman-Lewis, Drew; Aryal, Baikuntha P.; Paunesku, Tatjana; Vogt, Stefan; Lai, Barry; Woloschak, Gayle E.; Jensen, Mark P.

    2013-01-01

    Microprobe X-ray absorption near edge structure (μ-XANES) measurements were used to determine directly, for the first time, the oxidation state of intracellular plutonium in individual 0.1 μm2 areas within single rat pheochromocytoma cells (PC12). The living cells were incubated in vitro for 3 hours in the presence of Pu added to the media in different oxidation states (Pu(III), Pu(IV), and Pu(VI)) and in different chemical forms. Regardless of the initial oxidation state or chemical form of Pu presented to the cells, the XANES spectra of the intracellular Pu deposits was always consistent with tetravalent Pu even though the intracellular milieu is generally reducing. PMID:21755934

  7. Rapid determination by reversed-phase high-performance liquid chromatography of Vitamins A and E in infant formulas.

    PubMed

    Rodas Mendoza, B; Morera Pons, S; Castellote Bargalló, A I; López-Sabater, M C

    2003-11-14

    A rapid, sensitive method has been developed for the simultaneous determination of retinol acetate, delta-, gamma-, alpha-tocopherol and alpha-tocopherol acetate. We compare two experimental procedures for simultaneous direct solvent extraction of these vitamins without previous saponification. Method I: the fat milk sample was extracted with ethanol-hexane and injected directly into the chromatographic column. Method II: the power milk sample was extracted with ethanol-hexane and also injected directly into the column. Under optimum conditions the limits of detection for retinol acetate, delta-, gamma-, alpha-tocopherol and alpha-tocopherol acetate were 0.33, 21.2, 32.9, 32.5 and 3.2 ng and the limits of quantification were 0.42, 25.3, 37.9, 36.8 and 6.3 ng, respectively. The precision results showed that the relative standard deviations of repeatability and reproducibility were between 0.74 and 5.7%.

  8. Direction sensitive laser velocimeter. [determining the direction of particles using a helium-neon laser

    NASA Technical Reports Server (NTRS)

    Franke, J. M. (Inventor)

    1981-01-01

    A laser velocimeter is described which determines the direction of movement of particles. A laser produces a transmitted beam that illuminates the volume under investigation. The backscattered light is divided into two equal intensity beams. A first part of a sample of the transmitted beam is mixed with one of the two equal intensity beams and applied to a first photodetector. A second part of the sample is phase shifted by 90 deg, mixed with the other of the two equal intensity beams and applied to a second photodetector. The output of the first photodetector is phase shifted by 90 deg and then multiplied with the output of the second photodetector to produce a signal indicative of direction of movement.

  9. Gold Nanoparticles as a Direct and Rapid Sensor for Sensitive Analytical Detection of Biogenic Amines

    NASA Astrophysics Data System (ADS)

    El-Nour, K. M. A.; Salam, E. T. A.; Soliman, H. M.; Orabi, A. S.

    2017-03-01

    A new optical sensor was developed for rapid screening with high sensitivity for the existence of biogenic amines (BAs) in poultry meat samples. Gold nanoparticles (GNPs) with particle size 11-19 nm function as a fast and sensitive biosensor for detection of histamine resulting from bacterial decarboxylation of histidine as a spoilage marker for stored poultry meat. Upon reaction with histamine, the red color of the GNPs converted into deep blue. The appearance of blue color favorably coincides with the concentration of BAs that can induce symptoms of poisoning. This biosensor enables a semi-quantitative detection of analyte in real samples by eye-vision. Quality evaluation is carried out by measuring histamine and histidine using different analytical techniques such as UV-vis, FTIR, and fluorescence spectroscopy as well as TEM. A rapid quantitative readout of samples by UV-vis and fluorescence methods with standard instrumentation were proposed in a short time unlike chromatographic and electrophoretic methods. Sensitivity and limit of detection (LOD) of 6.59 × 10-4 and 0.6 μM, respectively, are determined for histamine as a spoilage marker with a correlation coefficient ( R 2) of 0.993.

  10. Determining Charged Particle Flux Direction in MSL/RAD

    NASA Astrophysics Data System (ADS)

    Appel, J. K.; Kohler, J.; Guo, J.; Ehresmann, B.; Zeitlin, C. J.; Wimmer-Schweingruber, R. F.; Hassler, D.; Rafkin, S. C.; Boehm, E.; Böttcher, S. I.; Martin-Garcia, C.; Brinza, D. E.; Weigle, E.; Lohf, H.; Burmeister, S.; Reitz, G.; Matthiae, D.; Posner, A.; Martín-Torres, J.; Zorzano, M. P.

    2014-12-01

    The Radiation Assessment Detector (RAD) is an instrument onboard the Mars Science Laboratory (MSL) rover Curiosity, currently characterizing the radiation environment on the surface of Mars. The radiation entering the instrument from above consists mostly of Galactic Cosmic Rays (GCRs) modulated by the Martian atmosphere. From below, the instrument is exposed to secondary radiation produced by the interactions of the GCR with the soil. This secondary radiation gets further modulated going through the rover body before entering RAD. We developed a method of determining the direction of the charged particles measured by RAD. This method also extends the energy range possible for measurements with RAD beyond the intruments design limit. Using a combination of GEANT4 and Planetocosmics simulations, we reconstructed the expected charged particle spectra and intensities for upward and downward directed radiation which can be compared with observations. With the developed method, we are able to, for the first time, measure the upward charged particle flux with RAD both during the cruise phase and the surface science phase. Comparing the results of the simulations with the instrument data sets enables us to evaluate the simulation tools used to predict the Martian radiation envronment.

  11. Utility of the Determine Syphilis TP rapid test in commercial sex venues in Peru

    PubMed Central

    Campos, P E; Buffardi, A L; Chiappe, M; Buendía, C; Garcia, P J; Carcamo, C P; Garnett, G; White, P

    2006-01-01

    Objectives This study sought to evaluate the utility of the Determine Syphilis TP test performed in Peruvian commercial sex venues for the detection of active syphilis; and determine the feasibility of integrating rapid syphilis testing for female sex workers (FSW) into existing health outreach services. Methods We tested 3586 female sex workers for syphilis by Determine in the field using whole blood fingerstick, and by rapid plasma reagin (RPR) and Treponema pallidum haemagglutination assay (TPHA) in a central laboratory in Lima using sera. Results 97.4% of the FSW offered rapid syphilis testing participated; and among those who tested positive, 87% visited the local health centre for treatment. More than twice as many specimens were RPR reactive using serum in Lima (5.7%) than tested positive by whole blood Determine in the field (2.8%), and although most were confirmed by TPHA, only a small proportion (0.7%) were RPR reactive at ⩾1:8 dilutions, and likely indicating active syphilis. Sensitivity, specificity and positive predictive value of the Determine Syphilis TP test in whole blood when compared to serum RPR reactivity at any dilution confirmed by TPHA as the gold standard were 39.3%, 99.2% and 71.4%, respectively. Sensitivity improved to 64.0% when using serum RPR ⩾1:8 confirmed by TPHA. Invalid tests were rare (0.3%). Conclusions Rapid syphilis testing in sex work venues proved feasible, but Determine using whole blood obtained by fingerstick was substantially less sensitive than reported in previous laboratory‐based studies using serum. Although easy to perform in outreach venues, the utility of this rapid syphilis test was relatively low in settings where a large proportion of the targeted population has been previously tested and treated. PMID:17116642

  12. Utility of the Determine Syphilis TP rapid test in commercial sex venues in Peru.

    PubMed

    Campos, P E; Buffardi, A L; Chiappe, M; Buendía, C; Garcia, P J; Carcamo, C P; Garnett, G; White, P; Holmes, K K

    2006-12-01

    This study sought to evaluate the utility of the Determine Syphilis TP test performed in Peruvian commercial sex venues for the detection of active syphilis; and determine the feasibility of integrating rapid syphilis testing for female sex workers (FSW) into existing health outreach services. We tested 3586 female sex workers for syphilis by Determine in the field using whole blood fingerstick, and by rapid plasma reagin (RPR) and Treponema pallidum haemagglutination assay (TPHA) in a central laboratory in Lima using sera. 97.4% of the FSW offered rapid syphilis testing participated; and among those who tested positive, 87% visited the local health centre for treatment. More than twice as many specimens were RPR reactive using serum in Lima (5.7%) than tested positive by whole blood Determine in the field (2.8%), and although most were confirmed by TPHA, only a small proportion (0.7%) were RPR reactive at >or=1:8 dilutions, and likely indicating active syphilis. Sensitivity, specificity and positive predictive value of the Determine Syphilis TP test in whole blood when compared to serum RPR reactivity at any dilution confirmed by TPHA as the gold standard were 39.3%, 99.2% and 71.4%, respectively. Sensitivity improved to 64.0% when using serum RPR >or=1:8 confirmed by TPHA. Invalid tests were rare (0.3%). Rapid syphilis testing in sex work venues proved feasible, but Determine using whole blood obtained by fingerstick was substantially less sensitive than reported in previous laboratory-based studies using serum. Although easy to perform in outreach venues, the utility of this rapid syphilis test was relatively low in settings where a large proportion of the targeted population has been previously tested and treated.

  13. A Biosensor Platform for Rapid Antimicrobial Susceptibility Testing Directly From Clinical Samples

    PubMed Central

    Mach, Kathleen E.; Mohan, Ruchika; Baron, Ellen Jo; Shih, Mei-Chiung; Gau, Vincent; Wong, Pak Kin; Liao, Joseph C.

    2014-01-01

    Purpose A significant barrier to efficient antibiotic management of infection is that the standard diagnostic methodologies do not provide results at the point of care. The delays between sample collection and bacterial culture and antibiotic susceptibility reporting have led to empirical use of antibiotics, contributing to the emergence of drug resistant pathogens. As a key step toward the development of a point of care device for determining the antibiotic susceptibility of urinary tract pathogens, we report on a biosensor based antimicrobial susceptibility test. Materials and Methods For assay development bacteria were cultured with or without antibiotics, and growth was quantitated by determining viable counts and electrochemical biosensor measurement of bacterial 16S rRNA. To determine antibiotic susceptibility directly from patient samples, urine was cultured on antibiotic plates for 2.5 hours and growth was determined by electrochemical measurement of bacterial 16S rRNA. For assay validation 252 urine samples were collected from patients at the Spinal Cord Injury Service at Veterans Affairs Palo Alto Health Care System. The biosensor based antimicrobial susceptibility test was completed for samples containing gram-negative organisms. Pathogen identification and antibiotic susceptibility results were compared between our assay and standard microbiological analysis. Results A direct biosensor quantitation of bacterial 16S rRNA can be used to monitor bacterial growth for a biosensor based antimicrobial susceptibility test. Clinical validation of a biosensor based antimicrobial susceptibility test with patient urine samples demonstrated that this test was 94% accurate in 368 pathogen-antibiotic tests compared to standard microbiological analysis. Conclusions This biosensor based antimicrobial susceptibility test, in concert with our previously described pathogen identification assay, can provide culture and susceptibility information directly from a urine sample

  14. Extremely rapid directional change during Matuyama-Brunhes geomagnetic polarity reversal

    NASA Astrophysics Data System (ADS)

    Sagnotti, Leonardo; Scardia, Giancarlo; Giaccio, Biagio; Liddicoat, Joseph C.; Nomade, Sebastien; Renne, Paul R.; Sprain, Courtney J.

    2014-11-01

    We report a palaeomagnetic investigation of the last full geomagnetic field reversal, the Matuyama-Brunhes (M-B) transition, as preserved in a continuous sequence of exposed lacustrine sediments in the Apennines of Central Italy. The palaeomagnetic record provides the most direct evidence for the tempo of transitional field behaviour yet obtained for the M-B transition. 40Ar/39Ar dating of tephra layers bracketing the M-B transition provides high-accuracy age constraints and indicates a mean sediment accumulation rate of about 0.2 mm yr-1 during the transition. Two relative palaeointensity (RPI) minima are present in the M-B transition. During the terminus of the upper RPI minimum, a directional change of about 180 ° occurred at an extremely fast rate, estimated to be less than 2 ° per year, with no intermediate virtual geomagnetic poles (VGPs) documented during the transit from the southern to northern hemisphere. Thus, the entry into the Brunhes Normal Chron as represented by the palaeomagnetic directions and VGPs developed in a time interval comparable to the duration of an average human life, which is an order of magnitude more rapid than suggested by current models. The reported investigation therefore provides high-resolution integrated palaeomagnetic and radioisotopic data that document the fine details of the anatomy and tempo of the M-B transition in Central Italy that in turn are crucial for a better understanding of Earth's magnetic field, and for the development of more sophisticated models that are able to describe its global structure and behaviour.

  15. A critical analysis of methods for rapid and nondestructive determination of wood density in standing trees

    Treesearch

    Shan Gao; Xiping Wang; Michael C. Wiemann; Brian K. Brashaw; Robert J. Ross; Lihai Wang

    2017-01-01

    Key message Field methods for rapid determination of wood density in trees have evolved from increment borer, torsiometer, Pilodyn, and nail withdrawal into sophisticated electronic tools of resistance drilling measurement. A partial resistance drilling approach coupled with knowledge of internal tree density distribution may...

  16. A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella

    USDA-ARS?s Scientific Manuscript database

    Standard methods of determining the ionophore sensitivity of Eimeria rely on infecting chickens with an isolate or a mixture of Eimeria spp. oocysts in the presence of different anti-coccidial drugs. The purpose of this study was to develop a rapid in vitro method for assessing salinomycin and mone...

  17. Use of the rapid fermentation test in determining carbohydrate reactions of fastidious bacteria in clinical laboratories.

    PubMed Central

    Hollis, D G; Sottnek, F O; Brown, W J; Weaver, R E

    1980-01-01

    The rapid fermentation test was used to determine the carbohydrate reactions of some of the fastidious bacteria encountered in clinical laboratories, such as: Haemophilus species, including Haemophilus vaginalis; Actinobacillus actinomycetemcomitans; Cardiobacterium hominis; Kingella species; Corynebacterium species; Propionibacterium species; and Erysipelothrix rhusiopathiae. Results were usually obtained within 4 h by using inocula from 24- or 48-h blood or chocolate agar media. PMID:6999028

  18. Rapid fusion method for determination of plutonium isotopes in large rice samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.

    2013-04-30

    A new rapid fusion method for the determination of plutonium in large rice samples has been developed at the Savannah River National Laboratory (Aiken, SC, USA) that can be used to determine very low levels of plutonium isotopes in rice. The recent accident at Fukushima Nuclear Power Plant in March, 2011 reinforces the need to have rapid, reliable radiochemical analyses for radionuclides in environmental and food samples. Public concern regarding foods, particularly foods such as rice in Japan, highlights the need for analytical techniques that will allow very large sample aliquots of rice to be used for analysis so that very low levels of plutonium isotopes may be detected. The new method to determine plutonium isotopes in large rice samples utilizes a furnace ashing step, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with TEVA Resin cartridges. The method can be applied to rice sample aliquots as large as 5 kg. Plutonium isotopes can be determined using alpha spectrometry or inductively-coupled plasma mass spectrometry (ICP-MS). The method showed high chemical recoveries and effective removal of interferences. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory plutonium particles are effectively digested. The MDA for a 5 kg rice sample using alpha spectrometry is 7E-5 mBq g{sup -1}. The method can easily be adapted for use by ICP-MS to allow detection of plutonium isotopic ratios.

  19. Sex determination directs uniparental mitochondrial inheritance in Phycomyces.

    PubMed

    Shakya, Viplendra P S; Idnurm, Alexander

    2014-02-01

    Uniparental inheritance (UPI) of mitochondria is common among eukaryotes. The underlying molecular basis by which the sexes of the parents control this non-Mendelian pattern of inheritance is yet to be fully understood. Two major factors have complicated the understanding of the role of sex-specific genes in the UPI phenomenon: in many cases (i) fusion occurs between cells of unequal size or (ii) mating requires a large region of the genome or chromosome that includes genes unrelated to sex determination. The fungus Phycomyces blakesleeanus is a member of the Mucoromycotina and has a simple mating type locus encoding only one high-mobility group (HMG) domain protein, and mating occurs by fusion of isogamous cells, thus providing a model system without the limitations mentioned above. Analysis of more than 250 progeny from a series of genetic crosses between wild-type strains of Phycomyces revealed a correlation between the individual genes in the mating type locus and UPI of mitochondria. Inheritance is from the plus (+) sex type and is associated with degradation of the mtDNA from the minus (-) parent. These findings suggest that UPI can be directly controlled by genes that determine sex identity, independent of cell size or the complexity of the genetic composition of a sex chromosome.

  20. Direct determination of selenium in serum by electrothermal atomic absorption spectrometry using automated ultrasonic slurry sampling

    NASA Astrophysics Data System (ADS)

    Chen, Wen-Kang; Yen, Cheng-Chieh; Wei, Bai-Luh; Hu, Chao-Chin; Yu, Jya-Jyun; Chung, Chien; Kuo, Sheng-Chu

    1998-01-01

    Selenium concentration in body fluids is a good index to establish human selenium status. This work discusses the determination of selenium in serum by ETAAS using longitudinal Zeeman-effect background correction and combining the use of automated slurry sampling. The standard reference materials bovine serum (NIST, SRM 1598) and second-generation biological freeze-dried human serum are analyzed to verify the accuracy and precision of this technique. The direct method proposed in this study is used for the determination of selenium in human serum collected from healthy people of 19-25 years. The average accuracy values of certified reference serum samples and the recovery values of spiked samples indicate this method to be an efficient and rapid technique for determining selenium in biological samples.

  1. Evaluation of the direct nitrate reductase assay for rapid detection of extensively drug-resistant tuberculosis.

    PubMed

    Huang, Z-K; Luo, Q; Qing, C; Deng, Y-T; Xiong, G-L; Li, J-M

    2016-04-01

    Jiangxi, China. To evaluate the performance of the direct nitrate reductase assay (D-NRA) for rapid, low-cost detection of multidrug-resistant (MDR-) and extensively drug-resistant tuberculosis (XDR-TB) in high-burden, resource-limited settings. A total of 225 smear-positive sputum samples were collected from consecutive drug-resistant TB subjects. Samples were processed at the Province TB Reference Laboratory and tested for susceptibility to rifampicin (RMP), isoniazid (INH), ofloxacin (OFX), kanamycin (KM) and capreomycin (CPM) by D-NRA, using the indirect Löwenstein-Jensen proportion method (LJ-PM) as reference. Of the 225 smear-positive sputum samples, 214 isolates were identified as Mycobacterium tuberculosis and analysed for further comparison. The sensitivity of the D-NRA in the detection of resistance to RMP, INH, OFX, KM and CPM was respectively 95.1% (97/102), 93.1% (135/145), 97.4% (76/78), 88.9% (40/45) and 90.6% (29/32); specificity was respectively 100% (112/112), 97.1% (67/69), 100% (136/136), 98.8% (167/169) and 96.7% (176/182). The median time to culture positivity was significantly shorter for NRA than for the indirect LJ-PM (14 days vs. 70 days, P < 0.001). D-NRA showed high sensitivity and specificity in the rapid diagnosis of MDR- and XDR-TB in a high-burden, resource-limited setting.

  2. Evaluation of three rapid diagnostic methods for direct identification of microorganisms in positive blood cultures.

    PubMed

    Martinez, Raquel M; Bauerle, Elizabeth R; Fang, Ferric C; Butler-Wu, Susan M

    2014-07-01

    The identification of organisms from positive blood cultures generally takes several days. However, recently developed rapid diagnostic methods offer the potential for organism identification within only a few hours of blood culture positivity. In this study, we evaluated the performance of three commercial methods to rapidly identify organisms directly from positive blood cultures: QuickFISH (AdvanDx, Wolburn, MA), Verigene Gram-Positive Blood Culture (BC-GP; Nanosphere, Northbrook, IL), and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) with Sepsityper processing (Bruker Daltonics, Billerica, MA). A total of 159 blood cultures (VersaTREK Trek Diagnostic Systems, Cleveland, OH) positive for Gram-positive and Gram-negative bacteria as well as yeast were analyzed with QuickFISH and MALDI-TOF MS. In all, 102 blood cultures were analyzed using the BC-GP assay. For monomicrobial cultures, we observed 98.0% concordance with routine methods for both QuickFISH (143/146) and the BC-GP assay (93/95). MALDI-TOF MS demonstrated 80.1% (117/146) and 87.7% (128/146) concordance with routine methods to the genus and species levels, respectively. None of the methods tested were capable of consistently identifying polymicrobial cultures in their entirety or reliably differentiating Streptococcus pneumoniae from viridans streptococci. Nevertheless, the methods evaluated in this study are convenient and accurate for the most commonly encountered pathogens and have the potential to dramatically reduce turnaround time for the provision of results to the treating physician.

  3. Rapid quantification of free cholesterol in tears using direct insertion/electron ionization-mass spectrometry.

    PubMed

    Wei, Xiaojia Eric; Korth, John; Brown, Simon H J; Mitchell, Todd W; Truscott, Roger J W; Blanksby, Stephen J; Willcox, Mark D P; Zhao, Zhenjun

    2013-12-09

    To establish a simple and rapid analytical method, based on direct insertion/electron ionization-mass spectrometry (DI/EI-MS), for measuring free cholesterol in tears from humans and rabbits. A stable-isotope dilution protocol employing DI/EI-MS in selected ion monitoring mode was developed and validated. It was used to quantify the free cholesterol content in human and rabbit tear extracts. Tears were collected from adult humans (n = 15) and rabbits (n = 10) and lipids extracted. Screening, full-scan (m/z 40-600) DI/EI-MS analysis of crude tear extracts showed that diagnostic ions located in the mass range m/z 350 to 400 were those derived from free cholesterol, with no contribution from cholesterol esters. DI/EI-MS data acquired using selected ion monitoring (SIM) were analyzed for the abundance ratios of diagnostic ions with their stable isotope-labeled analogues arising from the D6-cholesterol internal standard. Standard curves of good linearity were produced and an on-probe limit of detection of 3 ng (at 3:1 signal to noise) and limit of quantification of 8 ng (at 10:1 signal to noise). The concentration of free cholesterol in human tears was 15 ± 6 μg/g, which was higher than in rabbit tears (10 ± 5 μg/g). A stable-isotope dilution DI/EI-SIM method for free cholesterol quantification without prior chromatographic separation was established. Using this method demonstrated that humans have higher free cholesterol levels in their tears than rabbits. This is in agreement with previous reports. This paper provides a rapid and reliable method to measure free cholesterol in small-volume clinical samples.

  4. Single-step blood direct PCR: A robust and rapid method to diagnose triplet repeat disorders.

    PubMed

    Singh, Inder; Swarup, Vishnu; Shakya, Sunil; Goyal, Vinay; Faruq, Mohammed; Srivastava, Achal Kumar

    2017-08-15

    DNA extraction prior to polymerase chain reaction (PCR) amplification in genetic diagnoses of triplet repeat disorders (TRDs) is tedious and labour-intensive and has the limitations of sample contamination with foreign DNA, including that from preceding samples. Therefore, we aimed to develop a rapid, robust, and cost-effective method for expeditious genetic investigation of TRDs from whole blood as a DNA template. Peripheral blood samples were collected from 70 clinically suspected patients of progressive ataxia. The conventional method using genomic DNA and single-step Blood-Direct PCR (BD-PCR) method with just 2μl of whole blood sample were tested to amplify triplet repeat expansion in genes related to spinocerebellar ataxia (SCA) types 1, 2, 3, 12 and Friedreich's ataxia (FRDA). Post-PCR, the allele sizes were mapped and repeat numbers were calculated using GeneMapper and macros run in Microsoft Excel programmes. Successful amplification of target regions was achieved in all samples by both methods. The frequency of the normal and mutated allele was concordant between both methods, diagnosing 37% positive for a mutation in either of the candidate genes. The BD-PCR resulted in higher intensities of product peaks of normal and pathogenic alleles. The nearly-accurate sizing of the normal and expanded allele was achieved in a shorter time (4-5h), without DNA extraction and any risk of cross contamination, which suggests the BD-PCR to be a reliable, inexpensive, and rapid method to confirm TRDs. This technique can be introduced in routine diagnostic procedures of other tandem repeat disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Application of a novel automatic disintegration apparatus for the development and evaluation of a direct compression rapidly disintegrating tablet.

    PubMed

    Jung, Huijeong Ashley; Augsburger, Larry L

    2012-07-01

    An automatic disintegration tester was developed and used to explore disintegration mechanism and times of rapidly disintegrating tablets. DT50, the time required for a tablet to decrease in its thickness by half, allowed an unbiased determination of disintegration time. Calcium silicate concentration, Explotab® concentration, DiPac®/Xylitab® ratio as fillers, and compression pressure were evaluated using a central composite model design analysis for their DT50, tensile strength, and friability. Tablets that could reasonably be handled (friability <10%) could be produced. The expansion coefficient (n) and the exponential rate constant (k) for disintegrating tablets, originally measured by Caramella et al. using force kinetics, could be determined from axial displacement data measured directly without the need to assume that disintegration force generation was indicative of changes in tablet volume. The n values of tablets containing calcium silicate, Ditab® and/or Xylitab®, magnesium stearate, and Explotab® suggested that the amount of Explotab® was not a significant factor in determining the disintegration mechanism; however, the type of disintegrant used did alter the n value. Primojel® and Explotab®, which are in the same class of disintegrants, exhibited similar DT50, n, and k. Polyplasdone® XL exhibited a much higher n, while yielding faster DT50, suggesting that its performance is more dependent on facilitating the interfacial separation of particles. AcDiSol® showed no apparent moisture sensitivity in regards to disintegration efficiency. The use of the novel apparatus proved to be useful in measuring disintegration efficiency of rapidly disintegrating tablets and in providing valuable information on the disintegration phenomena.

  6. Rapid determination of Faraday rotation in optical glasses by means of secondary Faraday modulator.

    PubMed

    Sofronie, M; Elisa, M; Sava, B A; Boroica, L; Valeanu, M; Kuncser, V

    2015-05-01

    A rapid high sensitive method for determining the Faraday rotation of optical glasses is proposed. Starting from an experimental setup based on a Faraday rod coupled to a lock-in amplifier in the detection chain, two methodologies were developed for providing reliable results on samples presenting low and large Faraday rotations. The proposed methodologies were critically discussed and compared, via results obtained in transmission geometry, on a new series of aluminophosphate glasses with or without rare-earth doping ions. An example on how the method can be used for a rapid examination of the optical homogeneity of the sample with respect to magneto-optical effects is also provided.

  7. Rapid method to determine actinides and 89/90Sr in limestone and marble samples

    DOE PAGES

    Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; ...

    2016-04-12

    A new method for the determination of actinides and radiostrontium in limestone and marble samples has been developed that utilizes a rapid sodium hydroxide fusion to digest the sample. Following rapid pre-concentration steps to remove sample matrix interferences, the actinides and 89/90Sr are separated using extraction chromatographic resins and measured radiometrically. The advantages of sodium hydroxide fusion versus other fusion techniques will be discussed. Lastly, this approach has a sample preparation time for limestone and marble samples of <4 hours.

  8. A simplified CARS measurement system for rapid determination of temperature and oxygen concentration

    NASA Technical Reports Server (NTRS)

    Fujii, Shoichi

    1987-01-01

    A new spectroscopic concept for the rapid determination of temperature and oxygen concentration by CARS (Coherent Anti-Stokes Raman Spectroscopy) was described. The ratio of two spectral regions in the broadband Q-branch spectrum was detected by photomultipliers in a monochromator, which ratio depends on temperature and species concentration. The comparison of the measured data with theory was made using a flat flame burner and an electric furnace, with reasonable results. Various optical techniques for alignment were introduced including a highly efficient, stable dye oscillator. The combination of the spectroscopic concept and the optical techniques will make the CARS measurement system rapid in data processing and simple in optical parts.

  9. Application of atomic force microscopy on rapid determination of microorganisms for food safety.

    PubMed

    Yang, H; Wang, Y

    2008-10-01

    Rapid detection and quantification of microorganisms is important for food quality, safety, and security. In this field, nanotechnology appears to be promising in its ability to characterize an individual microorganism and detect heterogeneous distribution of microbes in food samples. In this study, atomic force microscopy (AFM), a nanotechnology tool, was used to investigate Escherichia coli (E. coli) qualitatively and quantitatively. E. coli strains B and K12 were used as surrogates to represent pathogenic strains, such as E. coli O157: H7. The results from AFM were compared with those from scanning/transmission electron microscopy (SEM/TEM). The qualitative determination was obtained using morphology and characteristic parameters from AFM images, and the quantitative determination was obtained by calculating the microorganisms in AFM images. The results show that AFM provides a new approach for rapid determination of microorganisms for food safety.

  10. Rapid method for determination of carbonyl groups in lignin compounds by headspace gas chromatography.

    PubMed

    Li, Jing; Hu, Hui-Chao; Chai, Xin-Sheng

    2015-07-24

    The paper reports on a novel method for rapid determination of carbonyl in lignins by headspace gas chromatography (HS-GC). The method involves the quantitative carbonyl reduction for aldehydes in 2min at room temperature or for acetones in 30min at 80°C by sodium borohydride solution in a closed headspace sample vial. After the reaction, the solution was acidified by injecting sulfuric acid solution and the hydrogen released to the headspace was determined by GC using thermal-conductivity detector. The results showed that with the addition of SiO2 powder, the reduction reaction of carbonyl groups can be greatly facilitated. The method has a good measurement precision (RSD<7.74%) and accuracy (relative error <10% compared with a reference method) in the carbonyl quantification. It is suitable to be used for rapid determination of carbonyl content in lignin and related materials.

  11. Rapid titration of measles and other viruses: optimization with determination of replication cycle length.

    PubMed

    Grigorov, Boyan; Rabilloud, Jessica; Lawrence, Philip; Gerlier, Denis

    2011-01-01

    Measles virus (MV) is a member of the Paramyxoviridae family and an important human pathogen causing strong immunosuppression in affected individuals and a considerable number of deaths worldwide. Currently, measles is a re-emerging disease in developed countries. MV is usually quantified in infectious units as determined by limiting dilution and counting of plaque forming unit either directly (PFU method) or indirectly from random distribution in microwells (TCID50 method). Both methods are time-consuming (up to several days), cumbersome and, in the case of the PFU assay, possibly operator dependent. A rapid, optimized, accurate, and reliable technique for titration of measles virus was developed based on the detection of virus infected cells by flow cytometry, single round of infection and titer calculation according to the Poisson's law. The kinetics follow up of the number of infected cells after infection with serial dilutions of a virus allowed estimation of the duration of the replication cycle, and consequently, the optimal infection time. The assay was set up to quantify measles virus, vesicular stomatitis virus (VSV), and human immunodeficiency virus type 1 (HIV-1) using antibody labeling of viral glycoprotein, virus encoded fluorescent reporter protein and an inducible fluorescent-reporter cell line, respectively. Overall, performing the assay takes only 24-30 hours for MV strains, 12 hours for VSV, and 52 hours for HIV-1. The step-by-step procedure we have set up can be, in principle, applicable to accurately quantify any virus including lentiviral vectors, provided that a virus encoded gene product can be detected by flow cytometry.

  12. Rapid Titration of Measles and Other Viruses: Optimization with Determination of Replication Cycle Length

    PubMed Central

    Grigorov, Boyan; Rabilloud, Jessica; Lawrence, Philip; Gerlier, Denis

    2011-01-01

    Background Measles virus (MV) is a member of the Paramyxoviridae family and an important human pathogen causing strong immunosuppression in affected individuals and a considerable number of deaths worldwide. Currently, measles is a re-emerging disease in developed countries. MV is usually quantified in infectious units as determined by limiting dilution and counting of plaque forming unit either directly (PFU method) or indirectly from random distribution in microwells (TCID50 method). Both methods are time-consuming (up to several days), cumbersome and, in the case of the PFU assay, possibly operator dependent. Methods/Findings A rapid, optimized, accurate, and reliable technique for titration of measles virus was developed based on the detection of virus infected cells by flow cytometry, single round of infection and titer calculation according to the Poisson's law. The kinetics follow up of the number of infected cells after infection with serial dilutions of a virus allowed estimation of the duration of the replication cycle, and consequently, the optimal infection time. The assay was set up to quantify measles virus, vesicular stomatitis virus (VSV), and human immunodeficiency virus type 1 (HIV-1) using antibody labeling of viral glycoprotein, virus encoded fluorescent reporter protein and an inducible fluorescent-reporter cell line, respectively. Conclusion Overall, performing the assay takes only 24–30 hours for MV strains, 12 hours for VSV, and 52 hours for HIV-1. The step-by-step procedure we have set up can be, in principle, applicable to accurately quantify any virus including lentiviral vectors, provided that a virus encoded gene product can be detected by flow cytometry. PMID:21915289

  13. Rapid determination of seed vigor based on the level of superoxide generation during early imbibition.

    PubMed

    Liu, Xuejun; Xing, Da; Li, Lingling; Zhang, Lingrui

    2007-07-01

    It has been reported that a large amount of reactive oxygen species (ROS) is produced during seed imbibition and this ROS is related to seed vigor. To make this physiological mechanism clear, we have used 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo(1,2-alpha)pyrazin-3-one (MCLA) as a sensitive and physiologically compatible probe for the determination of superoxide anion (O(2)(*-)) production in vivo. Our results showed that dry rice (Oryzae sativa L.) seed embryo cells possessed the capacity to generate O(2)(*-). Conversely, the O(2)(*-) production of seed embryo cells was inhibited by quinacrine (QA) and diphenylene iodonium (DPI), two specific inhibitors of NADPH oxidase, and O(2)(*-) induced MCLA-mediated chemiluminescence was also blocked by superoxide dismutase (SOD). Additionally, O(2)(*-) -production ability increased dramatically in a NADPH-dependent way in the plasma membrane protein abstract from rice seed embryo cells, whereas SOD and the inhibitors mentioned above suppressed O(2)(*-) production. These preliminary results suggested that rice seeds contained intrinsic NADPH oxidase activity. To validate this conclusion, dichlorofluorescein (DCF) fluorescence staining was used (observed under a laser scanning microscope, LSM) to reflect the in situ assessment of O(2)(*-) -generation. The position of O(2)(*-) production located at the plasma membrane. Additionally the ability to synthesize O(2)(*-) was activated directly by calcium ions. These observations are in accord with the character of NADPH oxidase catalyzed O(2)(*-) -generation. All these results indicated that NADPH oxidase contribute to O(2)(*-) production and release to the outside. We concluded that NADPH oxidase plays an intrinsic role as an NADPH sensor, so, measuring the O(2)(*-) one can monitor the NADPH concentration, which is an index of seed vigor. Therefore the O(2)(*-) generation during early imbibition can serve as a rapid measurement of seed vigor.

  14. Atypical sensors for direct and rapid neuronal detection of bacterial pathogens.

    PubMed

    Lim, Ji Yeon; Choi, Seung-In; Choi, Geunyeol; Hwang, Sun Wook

    2016-03-09

    Bacterial infection can threaten the normal biological functions of a host, often leading to a disease. Hosts have developed complex immune systems to cope with the danger. Preceding the elimination of pathogens, selective recognition of the non-self invaders is necessary. At the forefront of the body's defenses are the innate immune cells, which are equipped with particular sensor molecules that can detect common exterior patterns of invading pathogens and their secreting toxins as well as with phagocytic machinery. Inflammatory mediators and cytokines released from these innate immune cells and infected tissues can boost the inflammatory cascade and further recruit adaptive immune cells to maximize the elimination and resolution. The nervous system also seems to interact with this process, mostly known to be affected by the inflammatory mediators through the binding of neuronal receptors, consequently activating neural circuits that tune the local and systemic inflammatory states. Recent research has suggested new contact points: direct interactions of sensory neurons with pathogens. Latest findings demonstrated that the sensory neurons not only share pattern recognition mechanisms with innate immune cells, but also utilize endogenous and exogenous electrogenic components for bacterial pathogen detection, by which the electrical firing prompts faster information flow than what could be achieved when the immune system is solely involved. As a result, rapid pain generation and active accommodation of the immune status occur. Here we introduced the sensory neuron-specific detector molecules for directly responding to bacterial pathogens and their signaling mechanisms. We also discussed extended issues that need to be explored in the future.

  15. Rapid Detection of Thrombin and Other Protease Activity Directly in Whole Blood

    NASA Astrophysics Data System (ADS)

    Yu, Johnson Chung Sing

    Thrombin is a serine protease that plays a key role in the clotting cascade to promote hemostasis following injury to the endothelium. From a clinical diagnostic perspective, in-vivo thrombin activity is linked to various blood clotting disorders, as well as cardiovascular disease (DVT, arteriosclerosis, etc). Thus, the ability to rapidly measure protease activity directly in whole blood will provide important new diagnostics, and clinical researchers with a powerful tool to further elucidate the relationship between circulating protease levels and disease. The ultimate goal is to design novel point of care (POC) diagnostic devices that are capable of monitoring protease activities directly in whole blood and biological sample. A charge-changing substrate specific to the thrombin enzyme was engineered and its functionality was confirmed by a series of experiments. This led to the preliminary design, construction, and testing of two device platforms deemed fully functional for the electrophoretic separation and focusing of charged peptide fragments. The concept of using the existing charge-changing substrate platform for bacterial protease detection was also investigated. Certain strains of E coli are associated with severe symptoms such as abdominal cramps, bloody diarrhea, and vomiting. The OmpT protease is expressed on the outer membrane of E coli and plays a role in the cleavage of antimicrobial peptides, the degradation of recombinant heterologous proteins, and the activation of plasminogen in the host. Thus, a synthetic peptide substrate specific to the OmpT protease was designed and modeled for the purpose of detecting E coli in biological sample.

  16. DIRECT BINDING OF GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE TO TELOMERIC DNA PROTECTS TELOMERES AGAINST CHEMOTHERAPY-INDUCED RAPID DEGRADATION

    PubMed Central

    Demarse, Neil A.; Ponnusamy, Suriyan; Spicer, Eleanor K.; Apohan, Elif; Baatz, John E.; Ogretmen, Besim; Davies, Christopher

    2009-01-01

    GAPDH (glyceraldehyde 3-phosphate dehydrogenase) is a glycolytic enzyme that displays several non-glycolytic activities, including the maintenance and/or protection of telomeres. In this study, we determined the molecular mechanism and biological role of the interaction between GAPDH and human telomeric DNA. Using gel shift assays, we show that recombinant GAPDH binds directly with high affinity (Kd = 45 nM) to a single-stranded oligonucleotide comprising three telomeric DNA repeats and that nucleotides T1, G5 and G6 of the TTAGGG repeat are essential for binding. The stoichiometry of the interaction is 2:1 (DNA: GAPDH), and GAPDH appears to form a high-molecular weight complex when bound to the oligonucleotide. Mutation of Asp32 and Cys149, which are localized to the NAD-binding site and the active site center of GAPDH, respectively, produced mutants that almost completely lost their telomere-binding functions both in vitro and in situ (in A549 human lung cancer cells). Treatment of A549 cells with the chemotherapeutic agents gemcitabine and doxorubicin resulted in increased nuclear localization of expressed wild-type GAPDH, where it protected telomeres against rapid degradation, concomitant with increased resistance to the growth inhibitory effects of these drugs. The non-DNA-binding mutants of GAPDH also localized to the nucleus when expressed in A549 cells, but did not confer any significant protection of telomeres against chemotherapy-induced degradation or growth inhibition, and this occurred without the involvement of caspase activation or apoptosis regulation. Overall, these data demonstrate that GAPDH binds telomeric DNA directly in vitro and may have a biological role in the protection of telomeres against rapid degradation in response to chemotherapeutic agents in A549 human lung cancer cells. PMID:19800890

  17. Rapid and simple spectrophotometric determination of persulfate in water by microwave assisted decolorization of Methylene Blue.

    PubMed

    Zhao, Lajuan; Yang, Shiying; Wang, Leilei; Shi, Chao; Huo, Meiqing; Li, Yan

    2015-05-01

    A rapid and simple method for determination of persulfate in aqueous solution was developed. The method is based on the rapid reaction of persulfate with Methylene Blue (MB) via domestic microwave activation, which can promote the activation of persulfate and decolorize MB quickly. The depletion of MB at 644 nm (the maximum absorption wavelength of MB) is in proportion to the increasing concentration of persulfate in aqueous solution. Linear calibration curve was obtained in the range 0-1.5 mmol/L, with a limit of detection of 0.0028 mmol/L. The reaction time is rapid (within 60 sec), which is much shorter than that used for conventional methods. Compared with existing analytical methods, it need not any additives, especially colorful Fe2+, and need not any pretreatment for samples, such as pH adjustment.

  18. Rapid and direct synthesis of complex perovskite oxides through a highly energetic planetary milling

    PubMed Central

    Lee, Gyoung-Ja; Park, Eun-Kwang; Yang, Sun-A; Park, Jin-Ju; Bu, Sang-Don; Lee, Min-Ku

    2017-01-01

    The search for a new and facile synthetic route that is simple, economical and environmentally safe is one of the most challenging issues related to the synthesis of functional complex oxides. Herein, we report the expeditious synthesis of single-phase perovskite oxides by a high-rate mechanochemical reaction, which is generally difficult through conventional milling methods. With the help of a highly energetic planetary ball mill, lead-free piezoelectric perovskite oxides of (Bi, Na)TiO3, (K, Na)NbO3 and their modified complex compositions were directly synthesized with low contamination. The reaction time necessary to fully convert the micron-sized reactant powder mixture into a single-phase perovskite structure was markedly short at only 30–40 min regardless of the chemical composition. The cumulative kinetic energy required to overtake the activation period necessary for predominant formation of perovskite products was ca. 387 kJ/g for (Bi, Na)TiO3 and ca. 580 kJ/g for (K, Na)NbO3. The mechanochemically derived powders, when sintered, showed piezoelectric performance capabilities comparable to those of powders obtained by conventional solid-state reaction processes. The observed mechanochemical synthetic route may lead to the realization of a rapid, one-step preparation method by which to create other promising functional oxides without time-consuming homogenization and high-temperature calcination powder procedures. PMID:28387324

  19. Recursive directional ligation by plasmid reconstruction allows rapid and seamless cloning of oligomeric genes.

    PubMed

    McDaniel, Jonathan R; Mackay, J Andrew; Quiroz, Felipe García; Chilkoti, Ashutosh

    2010-04-12

    This paper reports a new strategy, recursive directional ligation by plasmid reconstruction (PRe-RDL), to rapidly clone highly repetitive polypeptides of any sequence and specified length over a large range of molecular weights. In a single cycle of PRe-RDL, two halves of a parent plasmid, each containing a copy of an oligomer, are ligated together, thereby dimerizing the oligomer and reconstituting a functional plasmid. This process is carried out recursively to assemble an oligomeric gene with the desired number of repeats. PRe-RDL has several unique features that stem from the use of type IIs restriction endonucleases: first, PRe-RDL is a seamless cloning method that leaves no extraneous nucleotides at the ligation junction. Because it uses type IIs endonucleases to ligate the two halves of the plasmid, PRe-RDL also addresses the major limitation of RDL in that it abolishes any restriction on the gene sequence that can be oligomerized. The reconstitution of a functional plasmid only upon successful ligation in PRe-RDL also addresses two other limitations of RDL: the significant background from self-ligation of the vector observed in RDL, and the decreased efficiency of ligation due to nonproductive circularization of the insert. PRe-RDL can also be used to assemble genes that encode different sequences in a predetermined order to encode block copolymers or append leader and trailer peptide sequences to the oligomerized gene.

  20. Direct Blood Dry LAMP: A Rapid, Stable, and Easy Diagnostic Tool for Human African Trypanosomiasis

    PubMed Central

    Hayashida, Kyoko; Kajino, Kiichi; Hachaambwa, Lottie; Namangala, Boniface; Sugimoto, Chihiro

    2015-01-01

    Loop-mediated isothermal amplification (LAMP) is a rapid and sensitive tool used for the diagnosis of a variety of infectious diseases. One of the advantages of this method over the polymerase chain reaction is that DNA amplification occurs at a constant temperature, usually between 60–65°C; therefore, expensive devices are unnecessary for this step. However, LAMP still requires complicated sample preparation steps and a well-equipped laboratory to produce reliable and reproducible results, which limits its use in resource-poor laboratories in most developing countries. In this study, we made several substantial modifications to the technique to carry out on-site diagnosis of Human African Trypanosomiasis (HAT) in remote areas using LAMP. The first essential improvement was that LAMP reagents were dried and stabilized in a single tube by incorporating trehalose as a cryoprotectant to prolong shelf life at ambient temperature. The second technical improvement was achieved by simplifying the sample preparation step so that DNA or RNA could be amplified directly from detergent-lysed blood samples. With these modifications, diagnosis of HAT in local clinics or villages in endemic areas becomes a reality, which could greatly impact on the application of diagnosis not only for HAT but also for other tropical diseases. PMID:25769046

  1. Directed evolution can rapidly improve the activity of chimeric assembly-line enzymes

    PubMed Central

    Fischbach, Michael A.; Lai, Jonathan R.; Roche, Eric D.; Walsh, Christopher T.; Liu, David R.

    2007-01-01

    Nonribosomal peptides (NRPs) are produced by NRP synthetase (NRPS) enzymes that function as molecular assembly lines. The modular architecture of NRPSs suggests that a domain responsible for activating a building block could be replaced with a domain from a foreign NRPS to create a chimeric assembly line that produces a new variant of a natural NRP. However, such chimeric NRPS modules are often heavily impaired, impeding efforts to create novel NRP variants by swapping domains from different modules or organisms. Here we show that impaired chimeric NRPSs can be functionally restored by directed evolution. Using rounds of mutagenesis coupled with in vivo screens for NRP production, we rapidly isolated variants of two different chimeric NRPSs with ≈10-fold improvements in enzyme activity and product yield, including one that produces new derivatives of the potent NRP/polyketide antibiotic andrimid. Because functional restoration in these examples required only modest library sizes (103 to 104 clones) and three or fewer rounds of screening, our approach may be widely applicable even for NRPSs from genetically challenging hosts. PMID:17620609

  2. Total Antioxidant Capacity and Characterization of Nitraria tangutorum Fruit Extract by Rapid Bioassay-Directed Fractionation.

    PubMed

    Rana, Jat; Missler, Stephen R; Persons, Kathryn; Han, Johnson; Li, Teric

    2016-09-01

    In recent years, the role of reactive nitrogen and oxygen species (RNOS) in human disease has been the subject of considerable study. This has led to research on the potential benefit of natural products as dietary antioxidants to mitigate oxidative stress caused by increased RNOS associated with tissue damage. Five physiologically relevant reactive species include peroxyl radical, hydroxyl radical, peroxynitrite anion, superoxide radical anion, and singlet oxygen. Excessive amounts of these species can lead to the degradation of important biomolecules in vivo, and dietary antioxidants have been shown to inhibit damage both in vitro and in vivo. In this investigation, we have discovered that an extract of the fruit from Nitraria tangutorum Bobr. (Tangut white thorn) demonstrates significant antioxidant capacity against all five reactive species. Rapid bioassay-directed fractionation was used to identify antioxidant phytochemicals by collecting fractions from HPLC effluent into 96 well microplates and testing for antioxidant activity against the 2,2-diphenyl-1-picrylhydrazyl radical. Two different classes of phytochemicals, anthocyanins and flavonoids, were associated with antioxidant activity. Active components were further characterized by UV-Vis spectroscopy and high-resolution MS.

  3. Rapid Prototyping of Polymeric Nanopillars by 3D Direct Laser Writing for Controlling Cell Behavior.

    PubMed

    Buch-Månson, Nina; Spangenberg, Arnaud; Gomez, Laura Piedad Chia; Malval, Jean-Pierre; Soppera, Olivier; Martinez, Karen L

    2017-08-23

    Mammalian cells have been widely shown to respond to nano- and microtopography that mimics the extracellular matrix. Synthetic nano- and micron-sized structures are therefore of great interest in the field of tissue engineering, where polymers are particularly attractive due to excellent biocompatibility and versatile fabrication methods. Ordered arrays of polymeric pillars provide a controlled topographical environment to study and manipulate cells, but processing methods are typically either optimized for the nano- or microscale. Here, we demonstrate polymeric nanopillar (NP) fabrication using 3D direct laser writing (3D DLW), which offers a rapid prototyping across both size regimes. The NPs are interfaced with NIH3T3 cells and the effect of tuning geometrical parameters of the NP array is investigated. Cells are found to adhere on a wide range of geometries, but the interface depends on NP density and length. The Cell Interface with Nanostructure Arrays (CINA) model is successfully extended to predict the type of interface formed on different NP geometries, which is found to correlate with the efficiency of cell alignment along the NPs. The combination of the CINA model with the highly versatile 3D DLW fabrication thus holds the promise of improved design of polymeric NP arrays for controlling cell growth.

  4. A new rapid acquisition technique for direct sequence spread-spectrum communications

    NASA Astrophysics Data System (ADS)

    Davidovici, S.; Milstein, L. B.; Schilling, D. L.

    1984-11-01

    This paper describes a rapid acquisition technique which can be used in direct sequence spread-spectrum systems. It is sequential in nature and is based on a double threshold which defines when a decision can be made. The values of the thresholds change at every examination instant. The procedure makes use of a bound to the partial cross-correlation function of PN sequences which ensures that only the sequence length needs to be given as far as the PN sequence particulars are concerned. A decision is made only if the probability of error associated with a decision at that point is equal to or better than a prespecified value. Finally, it is shown that most of the computational difficulties associated with the bound as given by a recursive algorithm can be eliminated when using a low-order polynomial approximation to the bound. However, either by using the bound or its polynomial approximation, a significant improvement in the acquisition time is obtained.

  5. Rapid exploration of configuration space with diffusion-map-directed molecular dynamics.

    PubMed

    Zheng, Wenwei; Rohrdanz, Mary A; Clementi, Cecilia

    2013-10-24

    The gap between the time scale of interesting behavior in macromolecular systems and that which our computational resources can afford often limits molecular dynamics (MD) from understanding experimental results and predicting what is inaccessible in experiments. In this paper, we introduce a new sampling scheme, named diffusion-map-directed MD (DM-d-MD), to rapidly explore molecular configuration space. The method uses a diffusion map to guide MD on the fly. DM-d-MD can be combined with other methods to reconstruct the equilibrium free energy, and here, we used umbrella sampling as an example. We present results from two systems: alanine dipeptide and alanine-12. In both systems, we gain tremendous speedup with respect to standard MD both in exploring the configuration space and reconstructing the equilibrium distribution. In particular, we obtain 3 orders of magnitude of speedup over standard MD in the exploration of the configurational space of alanine-12 at 300 K with DM-d-MD. The method is reaction coordinate free and minimally dependent on a priori knowledge of the system. We expect wide applications of DM-d-MD to other macromolecular systems in which equilibrium sampling is not affordable by standard MD.

  6. Rapid and direct synthesis of complex perovskite oxides through a highly energetic planetary milling.

    PubMed

    Lee, Gyoung-Ja; Park, Eun-Kwang; Yang, Sun-A; Park, Jin-Ju; Bu, Sang-Don; Lee, Min-Ku

    2017-04-07

    The search for a new and facile synthetic route that is simple, economical and environmentally safe is one of the most challenging issues related to the synthesis of functional complex oxides. Herein, we report the expeditious synthesis of single-phase perovskite oxides by a high-rate mechanochemical reaction, which is generally difficult through conventional milling methods. With the help of a highly energetic planetary ball mill, lead-free piezoelectric perovskite oxides of (Bi, Na)TiO3, (K, Na)NbO3 and their modified complex compositions were directly synthesized with low contamination. The reaction time necessary to fully convert the micron-sized reactant powder mixture into a single-phase perovskite structure was markedly short at only 30-40 min regardless of the chemical composition. The cumulative kinetic energy required to overtake the activation period necessary for predominant formation of perovskite products was ca. 387 kJ/g for (Bi, Na)TiO3 and ca. 580 kJ/g for (K, Na)NbO3. The mechanochemically derived powders, when sintered, showed piezoelectric performance capabilities comparable to those of powders obtained by conventional solid-state reaction processes. The observed mechanochemical synthetic route may lead to the realization of a rapid, one-step preparation method by which to create other promising functional oxides without time-consuming homogenization and high-temperature calcination powder procedures.

  7. Rapid and direct synthesis of complex perovskite oxides through a highly energetic planetary milling

    NASA Astrophysics Data System (ADS)

    Lee, Gyoung-Ja; Park, Eun-Kwang; Yang, Sun-A.; Park, Jin-Ju; Bu, Sang-Don; Lee, Min-Ku

    2017-04-01

    The search for a new and facile synthetic route that is simple, economical and environmentally safe is one of the most challenging issues related to the synthesis of functional complex oxides. Herein, we report the expeditious synthesis of single-phase perovskite oxides by a high-rate mechanochemical reaction, which is generally difficult through conventional milling methods. With the help of a highly energetic planetary ball mill, lead-free piezoelectric perovskite oxides of (Bi, Na)TiO3, (K, Na)NbO3 and their modified complex compositions were directly synthesized with low contamination. The reaction time necessary to fully convert the micron-sized reactant powder mixture into a single-phase perovskite structure was markedly short at only 30-40 min regardless of the chemical composition. The cumulative kinetic energy required to overtake the activation period necessary for predominant formation of perovskite products was ca. 387 kJ/g for (Bi, Na)TiO3 and ca. 580 kJ/g for (K, Na)NbO3. The mechanochemically derived powders, when sintered, showed piezoelectric performance capabilities comparable to those of powders obtained by conventional solid-state reaction processes. The observed mechanochemical synthetic route may lead to the realization of a rapid, one-step preparation method by which to create other promising functional oxides without time-consuming homogenization and high-temperature calcination powder procedures.

  8. Discrimination and direct determination of cephalosporins by circular dichroism.

    PubMed

    Gortázar, P; Vázquez, J T

    1994-09-01

    The circular dichroism and ultraviolet spectra of 15 commercial cephalosporins in common clinical use are analyzed. Distinguishing between the beta-lactam antibiotics (penicillins, cephalosporins, and cephamycins) on the basis of their CD spectral data has been found to be straightforward. Furthermore, sufficient CD spectral dissimilarities are observed to discriminate among the cephalosporin homologues and to classify these antibiotics in five spectroscopic groups, on the basis of the wavelengths of their Cotton effects. In addition, some chemical structural characteristics for these spectroscopic groups are discussed. Besides molar absorptivity and CD data, the slopes and the intercepts of the equations of the regression line are calculated for each of these antibiotics, the correlation coefficients being higher than 0.9993. The validity of the proposed model is confirmed by analysis of the variance. The results demonstrated that the proposed method is accurate and precise. The method was successfully applied to the direct determination of these drugs in commercial oral suspensions, injections, and capsules. The principal advantages of this method are quickness and simplicity no derivatization or chromatographic separation steps being needed.

  9. Determination of neutral carbohydrates by CZE with direct UV detection.

    PubMed

    Rovio, Stella; Yli-Kauhaluoma, Jari; Sirén, Heli

    2007-08-01

    A new CZE method relying on in-capillary reaction and direct UV detection at the wavelength 270 nm is presented for the simultaneous separation of the neutral carbohydrates xylitol, D-(-)-mannitol, sucrose, D-(+)-fucose, D-(+)-cellobiose, D-(+)-galactose, D-(+)-glucose, L-rhamnose, D-(+)-mannose, D-(-)-arabinose, D-(+)-xylose, and D-(-)-ribose. The alkaline electrolyte solution was prepared of 130 mM sodium hydroxide and 36 mM disodium hydrogen phosphate dihydrate. Separation of the sample mixture was achieved within 35 min. Calibration plots were linear in the range of 0.05-3 mM. Reproducibility of migration times was between 0.3 and 1.1%, and the detection limits for the analytes were 0.02 and 0.05 mM. The optimized method was applied for the determination of neutral monosaccharides in lemon, pineapple, and orange juices and a cognac sample. The methodology is fast since no other sample preparation except dilution is required.

  10. Rapid determination of 226Ra in emergency urine samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.; Utsey, Robin C.; McAlister, Daniel R.

    2014-02-27

    A new method has been developed at the Savannah River National Laboratory (SRNL) that can be used for the rapid determination of 226Ra in emergency urine samples following a radiological incident. If a radiological dispersive device event or a nuclear accident occurs, there will be an urgent need for rapid analyses of radionuclides in urine samples to ensure the safety of the public. Large numbers of urine samples will have to be analyzed very quickly. This new SRNL method was applied to 100 mL urine aliquots, however this method can be applied to smaller or larger sample aliquots as needed. The method was optimized for rapid turnaround times; urine samples may be prepared for counting in <3 h. A rapid calcium phosphate precipitation method was used to pre-concentrate 226Ra from the urine sample matrix, followed by removal of calcium by cation exchange separation. A stacked elution method using DGA Resin was used to purify the 226Ra during the cation exchange elution step. This approach combines the cation resin elution step with the simultaneous purification of 226Ra with DGA Resin, saving time. 133Ba was used instead of 225Ra as tracer to allow immediate counting; however, 225Ra can still be used as an option. The rapid purification of 226Ra to remove interferences using DGA Resin was compared with a slightly longer Ln Resin approach. A final barium sulfate micro-precipitation step was used with isopropanol present to reduce solubility; producing alpha spectrometry sources with peaks typically <40 keV FWHM (full width half max). This new rapid method is fast, has very high tracer yield (>90 %), and removes interferences effectively. The sample preparation method can also be adapted to ICP-MS measurement of 226Ra, with rapid removal of isobaric interferences.

  11. Ultra-rapid earth rotation determination with VLBI during CONT11 and CONT14

    NASA Astrophysics Data System (ADS)

    Haas, Rüdiger; Hobiger, Thomas; Kurihara, Shinobu; Hara, Tetsuya

    2016-04-01

    In 2007 the Geospatial Information Authority of Japan (GSI) and the Onsala Space Observatory (OSO) started a collaboration project aiming at determining the earth rotation angle, usually expressed as UT1-UTC, in near real-time. In the beginning of this project dedicated one hour long one-baseline experiments were observed periodically using the VLBI stations Onsala (Sweden) and Tsukuba (Japan). The strategy is that the observed VLBI data are sent in real-time via the international optical fibre backbone to the correlator at Tsukuba where the data are correlated with a software correlator and analyzed in near-real time with the c5++ VLBI data analysis software, thus producing UT1-UTC results with very low latency. The latency between the observation at the stations and the determination of UT1-UTC is on the order of a few minutes, thus we can talk about an ultra-rapid determination of UT1-UTC. An offline version of this strategy was adopted in 2009 for the regular VLBI intensive series INT-2, organized by the International VLBI Service for Geodesy and Astrometry (IVS), that involves Wettzell (Germany) and Tsukuba. Since March 2010 the INT-2 is using real-time e-transfer, too, and since June 2010 also automated analysis. Starting in 2009 the ultra-rapid approach was applied to regular 24 hour long IVS VLBI-sessions that involve Tsukuba and Onsala, so that ultra-rapid UT1-UTC results can be produced already during ongoing VLBI-sessions. This strategy was successfully operated during the 15 days long continuous VLBI campaigns CONT11 and CONT14. In this presentation we give an overview of the ultra-rapid concept, present the results derived during CONT11 and CONT14, and compare these ultra-rapid results to results derived from post-processing.

  12. Rapid radiochemical method for determination of actinides in emergency concrete and brick samples.

    PubMed

    Maxwell, Sherrod L; Culligan, Brian K; Kelsey-Wall, Angel; Shaw, Patrick J

    2011-09-02

    A new rapid method for the determination of actinides in emergency concrete and brick samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations or for routine analysis. If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or nuclear accident occurs, there will be a urgent need for rapid analyses of many different environmental matrices, including building materials such as concrete and brick, to support dose mitigation and environmental clean-up. The new method for actinides in concrete and brick method utilizes a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation process with stacked TEVA, TRU and DGA Resin cartridges. Alpha emitters are prepared using rare earth microprecipitation for counting by alpha spectrometry. The method showed high chemical recoveries and effective removal of interferences. The determination of actinides in concrete and brick sample analysis can be performed in less than 8h with excellent quality for emergency samples. The rapid fusion technique is a rugged sample digestion method that ensures that any refractory actinide particles are effectively digested.

  13. Application of rapid cloud point extraction method for trace cobalt analysis coupled with spectrophotometric determination.

    PubMed

    Wen, Xiaodong; He, Lei; Shi, Chunsheng; Deng, Qingwen; Wang, Jiwei; Zhao, Xia

    2013-11-01

    In this work, the analytical performance of conventional spectrophotometer was improved through the coupling of effective preconcentration method with spectrophotometric determination. Rapidly synergistic cloud point extraction (RS-CPE) was used to pre-concentrate ultra trace cobalt and firstly coupled with spectrophotometric determination. The developed coupling was simple, rapid and efficient. The factors influencing RS-CPE and spectrophotometer were optimized. Under the optimal conditions, the limit of detection (LOD) was 0.6μgL(-1), with sensitivity enhancement factor of 23. The relative standard deviation (RSD) for seven replicate measurements of 50μgL(-1) of cobalt was 4.3%. The recoveries for the spiked samples were in the acceptable range of 93.8-105%. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Rapid determination of saponification value and polymer content of vegetable and fish oils by terahertz spectroscopy.

    PubMed

    Jiang, Feng Ling; Ikeda, Ikuo; Ogawa, Yuichi; Endo, Yasushi

    2012-01-01

    A rapid method for determining the saponification value (SV) and polymer content of vegetable and fish oils using the terahertz (THz) spectroscopy was developed. When the THz absorption spectra for vegetable and fish oils were measured in the range of 20 to 400 cm⁻¹, two peaks were seen at 77 and 328 cm⁻¹. The level of absorbance at 77 cm⁻¹ correlated well with the SV. When the THz absorption spectra of thermally treated high-oleic safflower oils were measured, the absorbance increased with heating time. The polymer content in thermally treated oil correlated with the absorbance at 77 cm⁻¹. These results demonstrate that the THz spectrometry is a suitable non-destructive technique for the rapid determination of the SV and polymer content of vegetable and fish oils.

  15. [Rapid determination of silicon content in black liquor of straw fibrous material].

    PubMed

    Li, Hai-Long; Chai, Xin-Sheng; Zhan, Huai-Yu; Liu, Meng-Ru; Fu, Shi-Yu; Sun, Li-Jin

    2012-06-01

    The present paper reports a novel method for the determination of silicon content in straw fibrous material black liquor based on alpha-Si--Mo heteropoly acid spectrophotometry. The selected conditions were as follows: detection wavelength 360 nm, pH 4.0, and reaction time 10 min. It was found that the acidic soluble lignin in the sample liquor was the major interference species in the silicon content determination. The interference of acidic soluble lignin can be eliminated by hydrogen peroxide-nitric acid digestion method. The present method is not only simple, rapid, stable and less interferential, but also of good measurement precision and accuracy, with the relative standard deviations of 0.9%, and recoveries of 99.0%-102%. It is suitable for use in high silicon content of black liquor routine rapid analyses.

  16. Rapid determination of ampicillin in bovine milk by liquid chromatography with fluorescence detection

    SciTech Connect

    Ang, C.Y.W.; Luo, Wenhong

    1997-01-01

    A rapid and sensitive liquid chromatographic (LC) method was developed for the determination of ampicillin residues in raw bovine milk, processed skim milk, and pasteurized, homogenized whole milk with vitamin D. Milk samples were deproteinized with trichloroacetic acid (TCA) and acetonictrile. After centrifugation, the clear supernatant was reacted with formaldehyde and TCA under heat. The major fluorescent derivative of ampicillin was then determined by reversed-phase LC with fluorescence detection. Average recoveries of ampicillin fortified at 5, 10, and 20 ppb (ng/mL) were all >85% with coefficients of variation <10%. Limits of detection ranged from 0.31 to 0.51 ppb and limits of quantitation, from 0.66 to 1.2 ppb. After appropriate validation, this method should be suitable for rapid analysis of milk for ampicillin residues at the tolerance level of 10 ppb. 16 refs., 4 figs., 3 tabs.

  17. Evaluation of methods for rapid determination of freezing point of aviation fuels

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, B.

    1982-01-01

    Methods for identification of the more promising concepts for the development of a portable instrument to rapidly determine the freezing point of aviation fuels are described. The evaluation process consisted of: (1) collection of information on techniques previously used for the determination of the freezing point, (2) screening and selection of these techniques for further evaluation of their suitability in a portable unit for rapid measurement, and (3) an extensive experimental evaluation of the selected techniques and a final selection of the most promising technique. Test apparatuses employing differential thermal analysis and the change in optical transparency during phase change were evaluated and tested. A technique similar to differential thermal analysis using no reference fuel was investigated. In this method, the freezing point was obtained by digitizing the data and locating the point of inflection. Results obtained using this technique compare well with those obtained elsewhere using different techniques. A conceptual design of a portable instrument incorporating this technique is presented.

  18. Rapid Intrinsic Fluorescence Method for Direct Identification of Pathogens in Blood Cultures

    PubMed Central

    Walsh, John D.; Hyman, Jay M.; Borzhemskaya, Larisa; Bowen, Ann; McKellar, Caroline; Ullery, Michael; Mathias, Erin; Ronsick, Christopher; Link, John; Wilson, Mark; Clay, Bradford; Robinson, Ron; Thorpe, Thurman; van Belkum, Alex; Dunne, W. Michael

    2013-01-01

    ABSTRACT A positive blood culture is a critical result that requires prompt identification of the causative agent. This article describes a simple method to identify microorganisms from positive blood culture broth within the time taken to perform a Gram stain (<20 min). The method is based on intrinsic fluorescence spectroscopy (IFS) of whole cells and required development of a selective lysis buffer, aqueous density cushion, optical microcentrifuge tube, and reference database. A total of 1,121 monomicrobial-positive broth samples from 751 strains were analyzed to build a database representing 37 of the most commonly encountered species in bloodstream infections or present as contaminants. A multistage algorithm correctly classified 99.6% of unknown samples to the Gram level, 99.3% to the family level, and 96.5% to the species level. There were no incorrect results given at the Gram or family classification levels, while 0.8% of results were discordant at the species level. In 8/9 incorrect species results, the misidentified isolate was assigned to a species of the same genus. This unique combination of selective lysis, density centrifugation, and IFS can rapidly identify the most common microbial species present in positive blood cultures. Faster identification of the etiologic agent may benefit the clinical management of sepsis. Further evaluation is now warranted to determine the performance of the method using clinical blood culture specimens. PMID:24255123

  19. Determinants of the electric field during transcranial direct current stimulation.

    PubMed

    Opitz, Alexander; Paulus, Walter; Will, Susanne; Antunes, Andre; Thielscher, Axel

    2015-04-01

    Transcranial direct current stimulation (tDCS) causes a complex spatial distribution of the electric current flow in the head which hampers the accurate localization of the stimulated brain areas. In this study we show how various anatomical features systematically shape the electric field distribution in the brain during tDCS. We constructed anatomically realistic finite element (FEM) models of two individual heads including conductivity anisotropy and different skull layers. We simulated a widely employed electrode montage to induce motor cortex plasticity and moved the stimulating electrode over the motor cortex in small steps to examine the resulting changes of the electric field distribution in the underlying cortex. We examined the effect of skull thickness and composition on the passing currents showing that thinner skull regions lead to higher electric field strengths. This effect is counteracted by a larger proportion of higher conducting spongy bone in thicker regions leading to a more homogenous current over the skull. Using a multiple regression model we could identify key factors that determine the field distribution to a significant extent, namely the thicknesses of the cerebrospinal fluid and the skull, the gyral depth and the distance to the anode and cathode. These factors account for up to 50% of the spatial variation of the electric field strength. Further, we demonstrate that individual anatomical factors can lead to stimulation "hotspots" which are partly resistant to electrode positioning. Our results give valuable novel insights in the biophysical foundation of tDCS and highlight the importance to account for individual anatomical factors when choosing an electrode montage.

  20. [Determination of major carbonyls in mainstream smoke by rapid column high performance liquid chromatography].

    PubMed

    Huang, Yun; Wang, Yigeng; Miao, Mingming; Zhao, Qihua; Yang, Guangyu

    2007-03-01

    Abstract: The determination of major carbonyl compounds in mainstream cigarette smoke by rapid column high performance liquid chromatography was investigated. The cigarette smoke was collected using a Cambridge filter treated with acidic solution of 2, 4-dinitrophenyl-hydrazine. Formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, crotonaldehyde, 2-butanone and butyraldehyde were extracted from the Cambridge filter with 50 mL of 2% pyridine acetonitrile solution. The carbonyl compounds in samples were separated on a ZORBAX Stable Bound rapid column (50 mm x 4. 6 mm, 1. 8 microm) in approximately seven minutes and then determined by high performance liquid chromatography with a diode array detector. The average recoveries were in the range of 89. 1% to 99. 2% and the relative standard deviations (RSDs) were generally below 6. 0%. The eight carbonyl compounds in the mainstream smoke of five brands of cigarettes were determined using this method. This method is faster, simpler and consumes less solvent. It is suitable for rapid analysis of carbonyl compounds in mainstream cigarette smoke.

  1. Nanocrystalline (Pr,Dy)-(Fe,Co)-Zr-Ti-B magnets produced directly by rapid solidification

    NASA Astrophysics Data System (ADS)

    Pawlik, P.; Pawlik, K.; Davies, H. A.; Wysłocki, J. J.; Kaszuwara, W.

    2009-01-01

    Hard magnetic thick ribbon samples of a series of Pr9-xDyxFe60Co13Zr1+yTi3-yB14 alloys (where x=0;1 and y=0;1) (having average thicknesses tr of~ 140 µm) were produced directly by the melt-spinning technique under an Ar atmosphere. The phase constitution of the samples in the as-cast state was determined by X-ray diffractomety and Mössbauer spectroscopy. Hysteresis loops measurements at room temperature indicated very good hard magnetic properties for the alloys, which the coercivity attaining a maximum values of 1.58 MA/m. This is comparable with the coercivities of commercial NdFeB magnets based on melt spun ribbon and with those for nanocrystalline Nd-Fe-B magnets produces by other processes such as mechanical alloying or HDDR.

  2. A novel, micro, rapid and direct assay to assess total antioxidant capacity of solid foods.

    PubMed

    Condezo-Hoyos, Luis; Abderrahim, Fatima; Arriba, Silvia M; Carmen González, M

    2015-06-01

    A novel, micro, rapid and direct procedure to measure the total antioxidant capacity of solid foods using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) (mR-QUENCHER-DPPH) was developed and validated. The mR-QUENCHER-DPPH assay was performed in semi-aqueous medium (methanol-Tris buffer) using very small sample amounts (below 3.6 µg), as estimated by a Bradford reagent-based chemical predictor, and it was completed in 10 min at room temperature. The total antioxidant capacity (TAC) of solid foods was expressed as scavenging capacity index (SCI, mmol DPPH scavenged per kg sample), a theoretical and stoichiometric parameter deduced in this study. SCI values measured by mR-QUENCHER-DPPH assay for cereals cous-cous (7.20±0.35), amaranth (7.99±0.35) and buckwheat (194.2±6.72); Goji fruit (91.27±3.98); lotus root (2402±168); and spices turmeric (3767±355), ginger (2493±283), and cinnamon (10461±2133) were further validated using Folin-Ciocalteau assay. Bland-Altman analysis showed that there were not statistically significant differences in TAC values as measured by both assays. In the same way, TAC values measured by mR-QUENCHER-DPPH were correlated with free (r=0.8088, P=0.0151), bound (r=0.9668, P<0.0001) and total (r=0.9067, P=0.0019) reducing capacity of extracts from solid foods as assessed by Folin-Ciocalteau assay. The mR-QUENCHER-DPPH assay allows to measure TAC values using micro-gram amounts in solid food samples with a wide content range of antioxidants (low, high and very high), and omitting the time-consuming dilution cellulose-step commonly employed in the traditional QUENCHER procedures.

  3. Rapid determination of cell mass and density using digitally controlled electric field in a microfluidic chip.

    PubMed

    Zhao, Yuliang; Lai, Hok Sum Sam; Zhang, Guanglie; Lee, Gwo-Bin; Li, Wen Jung

    2014-11-21

    The density of a single cell is a fundamental property of cells. Cells in the same cycle phase have similar volume, but the differences in their mass and density could elucidate each cell's physiological state. Here we report a novel technique to rapidly measure the density and mass of a single cell using an optically induced electrokinetics (OEK) microfluidic platform. Presently, single cellular mass and density measurement devices require a complicated fabrication process and their output is not scalable, i.e., it is extremely difficult to measure the mass and density of a large quantity of cells rapidly. The technique reported here operates on a principle combining sedimentation theory, computer vision, and microparticle manipulation techniques in an OEK microfluidic platform. We will show in this paper that this technique enables the measurement of single-cell volume, density, and mass rapidly and accurately in a repeatable manner. The technique is also scalable - it allows simultaneous measurement of volume, density, and mass of multiple cells. Essentially, a simple time-controlled projected light pattern is used to illuminate the selected area on the OEK microfluidic chip that contains cells to lift the cells to a particular height above the chip's surface. Then, the cells are allowed to "free fall" to the chip's surface, with competing buoyancy, gravitational, and fluidic drag forces acting on the cells. By using a computer vision algorithm to accurately track the motion of the cells and then relate the cells' motion trajectory to sedimentation theory, the volume, mass, and density of each cell can be rapidly determined. A theoretical model of micro-sized spheres settling towards an infinite plane in a microfluidic environment is first derived and validated experimentally using standard micropolystyrene beads to demonstrate the viability and accuracy of this new technique. Next, we show that the yeast cell volume, mass, and density could be rapidly

  4. Nanoparticle formation by block copolymer directed rapid precipitations---Flash NanoPrecipitaiton

    NASA Astrophysics Data System (ADS)

    Prud'Homme, Robert

    2011-03-01

    With widespread interest in the generic ``nano'' attention has been focused on strategies of making small particles. High-value applications that drive new process innovation include very hydrophobic pharmaceutical actives, dyes and pigments for ink jet printing, or the dispersal of highly toxic insecticides on carriers. While it is relatively easy to make inorganic nano-particles, for example CdS particles, it is much more challenging to make nanoparticles from low surface energy organic solids. Strategies for forming nano particles vary from supercritical spraying, supercritical freezing, milling, solvent exchange precipitation, and imbibing into polymeric micelles. The solute and process combine to give differences in crystalline/amorphous products, individual particles/agglomerates, and uniformity/polydispersity of sizes. We will give an overview of the techniques and the classes of products that each addresses. We have developed a new technology that has two components: (1) rapid and tailored micromxing in an impinging jet, and (2) novel block copolymer stabilizers. The impinging jet process allows the production of nano-particles by: 1) elimination of mass transfer limitations and compositional gradients within 10 ms as determined by independent measurements with competitive-parallel reactions, 2) production of high supersaturations and solute concentrations so that high production rates can be obtained, and 3) control of particle size by stabilization of the particle using block copolymer self-assembly. The process depends critically on control of three time scales: particle nucleation and growth, block copolymer micellization, and polymer adsorption on the particle to produce steric stabilization. We present data on characterization of the mixing times using competitive reactions, data on polymer micellization kinetics, and results on the successful production of β -carotene and taxol particles with control of the particle size between 40 nm to 600 nm. A

  5. A rapid, quantitative GLC method for the simultaneous determination of nicotine and cotinine.

    PubMed

    Verebey, K G; DePace, A; Mulé, S J; Kanzler, M; Jaffe, J H

    1982-01-01

    Published gas-liquid chromatographic (GLC) methods for the determination of nicotine and cotinine have proved impractical for the analysis of a large number of clinical samples. Significant improvements over other methods have been achieved, being low sample volume (0.5 mL plasma), rapid two-step extraction from plasma, no evaporation step, and good separation. The lower limits of sensitivity for nicotine and cotinine were 1 and 5 ng/mL, respectively. The method was validated by the analysis of plasma samples from cigarette-smoking volunteers. The method described permits the quick, routine determination of nicotine and cotinine in a large number of samples.

  6. Development of rapid determination of 18 phthalate esters in edible vegetable oils by gas chromatography tandem mass spectrometry.

    PubMed

    Liu, Yinping; Wang, Shuhui; Wang, Li

    2013-02-13

    A simultaneous and fast determination of 18 phthalic acid esters (PAEs) in edible vegetable oils was developed. After solvent extraction, the PAEs in the oil sample were further cleaned up by solid-phase extraction. After concentration, the extract was directly injected into gas chromatography tandem mass spectrometry (GC-MS/MS) in positive-ion electron impact (EI) mode. Method quantification limits of 18 PAEs were between 0.01 and 0.1 mg/kg. Quantitative recoveries ranging from 63.9 to 115.3% were obtained by analysis of spiked oil. The relative standard deviations were less than 15% (n = 6). The method could potentially overcome the interference from large amounts of lipids and pigment. It was applied to real sample and shown to be a rapid and reliable alternative for determination and confirmation of PAEs in routine analysis.

  7. A rapid ICP-OES strategy for determination of gold and silver in blister copper by nitric acid digestion

    NASA Astrophysics Data System (ADS)

    Zhang, Gai; Tian, Min

    2014-03-01

    A rapid strategy for the analysis of gold and silver in blister copper by inductively coupled plasma optical emission spectrometry (ICP-OES) was firstly proposed. Nitric acid was used to digest blister copper instead of commonly used sulfuric acid. This prevented forming the salt of copper sulfate in the filtration process when the volume of the mixture is very small. Thus, the time of filtration was saved. After filtrating, aqua regia was used to digest the residue and acidize the filter liquor. Two parts of gotten solution were directly determined by ICP-OES. The cycle of analysis was shortened compared with sulfuric acid-fire assay. The proposed method was successfully applied to determine gold and silver in blister copper, and the results were in good agreement with those obtained by lead fire assay.

  8. Rapid Determination of Ionization Constants (pK a) by UV Spectroscopy Using 96-Well Microtiter Plates.

    PubMed

    Martínez, Carlos H Ríos; Dardonville, Christophe

    2013-01-10

    We have developed a methodology that enables for the rapid measurement of ionization constants (pK a) of series of compounds by UV spectrophotometry. This protocol, which is straightforward to set up, takes advantage of the sensitivity of UV spectroscopy and the throughput enabled by the 96-well microplate (as opposed to the use of 1 cm quartz cuvette). The compounds, in stock solutions in DMSO, are dissolved in several aqueous buffer solutions directly in the microtiter plate, allowing the simultaneous determination of the UV spectra as a function of pH. Further treatment of the data provides the pK a values in a medium-throughput manner. The pK a values of 11 new antitrypanosomal dibasic compounds were determined using this methodology.

  9. Rapid and accurate determination of the lignin content of lignocellulosic biomass by solid-state NMR.

    PubMed

    Fu, Li; McCallum, Scott A; Miao, Jianjun; Hart, Courtney; Tudryn, Gregory J; Zhang, Fuming; Linhardt, Robert J

    2015-02-01

    Biofuels and biomaterials, produced from lignocellulosic feedstock, require facile access to cellulose and hemicellulose to be competitive with petroleum processing and sugar-based fermentation. Physical-chemical barriers resulting from lignin complicates the hydrolysis biomass into fermentable sugars. Thus, the amount of lignin within a substrate is critical in determining biomass processing. The application of (13)C cross-polarization, magic-angle spinning, and solid-state nuclear magnetic resonance for the direct quantification of lignin content in biomass is examined. Using a standard curve constructed from pristine lignin and cellulose, the lignin content of a biomass sample is accurately determined through direct measurement without chemical or enzymatic pre-treatment.

  10. Direct transfer of HRPII-magnetic bead complexes to malaria rapid diagnostic tests significantly improves test sensitivity.

    PubMed

    Ricks, Keersten M; Adams, Nicholas M; Scherr, Thomas F; Haselton, Frederick R; Wright, David W

    2016-08-05

    The characteristic ease of use, rapid time to result, and low cost of malaria rapid diagnostic tests (RDTs) promote their widespread use at the point-of-care for malaria detection and surveillance. However, in many settings, the success of malaria elimination campaigns depends on point-of-care diagnostics with greater sensitivity than currently available RDTs. To address this need, a sample preparation method was developed to deliver more biomarkers onto a malaria RDT by concentrating the biomarker from blood sample volumes that are too large to be directly applied to a lateral flow strip. In this design, Ni-NTA-functionalized magnetic beads captured the Plasmodium falciparum biomarker HRPII from a P. falciparum D6 culture spiked blood sample. This transfer of magnetic beads to the RDT was facilitated by an inexpensive 3D-printed apparatus that aligned the sample tube with the sample deposition pad and a magnet beneath the RDT. Biomarkers were released from the bead surface onto the lateral flow strip using imidazole-spiked running buffer. Kinetics of HRPII binding to the Ni-NTA beads as a function of blood sample volume were explored prior to determining the effect of the proposed method on the limit of detection of Paracheck RDTs. More than 80 % of HRPII biomarkers were extracted from blood sample volumes ranging from 25 to 250 µL. The time required to reach 80 % binding ranged from 5 to 60 min, depending on sample volume. Using 250 μL of blood and a 30-min biomarker binding time, the limit of detection of the Paracheck Pf RDT brand was improved by 21-fold, resulting in a limit of detection below 1 parasite/μL. This approach has the sensitivity and simplicity required to assist in malaria elimination campaigns in settings with limited access to clinical and laboratory resources.

  11. Rapid method to determine 89Sr/90Sr in large concrete samples

    DOE PAGES

    Maxwell, Sherrod L.; Culligan, Brian; Hutchison, Jay B.; ...

    2016-03-24

    Here, a new rapid method has been developed that provides high quality low-level measurements of 89,90Sr in concrete samples with an MDA (Minimum Detectable Activity) of <1 mBq g-1. The new method is fast, meets new decommissioning regulatory limits and is robust even if refractory particles are present. The method utilizes a rapid fusion to ensure total dissolution of samples and rapid preconcentration and separation of 89,90Sr from 5-10 g concrete samples. When, the 89Sr/90Sr ratio is high, Sr can be isolated from up to 5g concrete samples, total 89/90Sr measured, and then 90Sr determined via 90Y separated after amore » period of ingrowth. Another approach allows the immediate determination of 90Sr in 10 g concrete aliquots without waiting for 90Y ingrowth, in instances where the shorter lived 89Sr is unlikely to be encountered.« less

  12. Development and evaluation of a rapid strategy to determine enterotoxin gene content in Staphylococcus aureus.

    PubMed

    Fischer, Adrien; Francois, Patrice; Holtfreter, Silva; Broeker, Barbara; Schrenzel, Jacques

    2009-05-01

    Enterotoxins of S. aureus are important molecules displaying superantigenic properties. To date no less than 18 enterotoxins have been identified in S. aureus and their role has been documented in very diverse diseases. Using available nucleotide sequence information, we developed a rapid and automated PCR-based approach to evaluate enterotoxin content in S aureus. We studied a collection of S. aureus strains previously analyzed for enterotoxins gene content and report a perfect correlation between simplex and multiplex PCR assays for the presence of all enterotoxin genes described so far. The determination of enterotoxin content relies on 4 multiplex PCR tubes whose amplification products are resolved by a rapid microcapillary electrophoresis. Automated analysis of the PCR profiles evaluates for the presence of the 18 enterotoxin genes in less than 3 h and at moderate cost. Finally, the use of enterotoxin gene content for genotyping purpose was compared to multi-locus variable number of tandem repeat assay and spa genotyping. Analysis revealed an important homogeneity of the genetic backgrounds for strains harboring the egc cluster as well as a large diversity for strains harboring other enterotoxins but lacking the egc cluster. A combined genotyping method that includes rapid enterotoxin content determination appears informative for various epidemiological survey purposes.

  13. Rapid determination of radium-224/226 in seawater sample by alpha spectrometry.

    PubMed

    Song, Lijuan; Yang, Yonggang; Luo, Maoyi; Ma, Yan; Dai, Xiongxin

    2017-05-01

    A new radiochemical separation method has been developed for rapid determination of alpha-emitting radium isotopes in seawater samples. This method can be applied for the measurement of (226)Ra in seawater samples when (224)Ra is used as tracer for chemical recovery correction. Likewise, (226)Ra can also be added as tracer for the determination of (224)Ra in seawater sample. In the method, radium is first pre-concentrated with hydrous titanium oxide (HTiO) and is purified by combined anion/cation exchange column chromatographic separation. The radium in the eluate is then co-precipitated with HTiO, dissolved in 9 M H2SO4, and followed through a BaSO4 micro-precipitation step to prepare a thin-layer counting source to determine the activities of (224)Ra/(226)Ra by alpha spectrometry. Replicate spike and blank samples were measured to evaluate the performance of the procedure. The minimum detectable activity concentration was determined to be 0.5 mBq·L(-1) for (226)Ra and 0.4 mBq·L(-1) for (224)Ra in 1 L of seawater sample with a counting time of 48 h. The method is a promising candidate for rapid measurement for alpha-emitting Ra isotopes in a large population of environment water samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Development of a rapid and simple voltammetric method to determine total antioxidative capacity of edible oils.

    PubMed

    Gulaboski, Rubin; Mirčeski, Valentin; Mitrev, Saša

    2013-05-01

    In this work we report on a new, rapid and simple voltammetric method to determine the total antioxidant capacity (TAC) of the edible oils. The method explores the ABTS radical (2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid)) assay as a redox probe and it relays on measuring catalytic voltammetric currents. The electrocatalysis comprises redox regeneration of the electrochemically created ABTS(+) radical either by Trolox (6-hydroxy-2,5,7,8-tetramethychroman-2-carboxylic acid) or by antioxidants present in studied oils. The detection limit of the method is determined to be 0.5 mg/L of Trolox equivalent, being a slightly lower than the corresponding UV-VIS spectrophotometric method. Applying the proposed voltammetric method the total antioxidant capacity of three types of commercially available cold-pressed edible oils are determined, and the results are found to be in a very good agreement with those obtained by UV-VIS spectrophotometry. The reported voltammetric method is cheap, rapid and simple, and it can be used as a sustainable alternative to the UV-VIS methods for the determination of total antioxidant capacitance of oils and other liquid lipophilic nutrients. Potent antioxidant capacity of studied oils was also confirmed by electron paramagnetic resonance spectroscopy of superoxide anion produced by macrophages.

  15. A general method for rapid determination of antibiotic susceptibility and species in bacterial infections.

    PubMed

    Mezger, Anja; Gullberg, Erik; Göransson, Jenny; Zorzet, Anna; Herthnek, David; Tano, Eva; Nilsson, Mats; Andersson, Dan I

    2015-02-01

    To ensure correct antibiotic treatment and reduce the unnecessary use of antibiotics, there is an urgent need for new rapid methods for species identification and determination of antibiotic susceptibility in infectious pathogenic bacteria. We have developed a general method for the rapid identification of the bacterial species causing an infection and the determination of their antibiotic susceptibility profiles. An initial short cultivation step in the absence and presence of different antibiotics was combined with sensitive species-specific padlock probe detection of the bacterial target DNA to allow a determination of growth (i.e., resistance) and no growth (i.e., susceptibility). A proof-of-concept was established for urinary tract infections in which we applied the method to determine the antibiotic susceptibility profiles of Escherichia coli for two drugs with 100% accuracy in 3.5 h. The short assay time from sample to readout enables fast appropriate treatment with effective drugs and minimizes the need to prescribe broad-spectrum antibiotics due to unknown resistance profiles of the treated infection.

  16. Direct Determinations of the πNN Coupling Constants

    NASA Astrophysics Data System (ADS)

    Ericson, T. E. O.; Loiseau, B.

    1998-11-01

    A novel extrapolation method has been used to deduce directly the charged πN N coupling constant from backward np differential scattering cross sections. The extracted value, g2c = 14.52(0.26) is higher than the indirectly deduced values obtained in nucleon-nucleon energy-dependent partial-wave analyses. Our preliminary direct value from a reanalysis of the GMO sum-rule points to an intermediate value of g2c about 13.97(30).

  17. Direct, non-destructive, and rapid evaluation of developmental cotton fibers by ATR FT-IR spectroscopy

    USDA-ARS?s Scientific Manuscript database

    Chemical, compositional, and structural differences within the fibers at different growth stages have been investigated considerably through a number of methodologies. Due to its direct, non-destructive, and rapid attribute, this study reports the utilization of attenuated total reflection Fourier t...

  18. A preliminary report on the rapid fluorimetric determination of uranium in low-grade ores

    USGS Publications Warehouse

    Grimaldi, F.S.; Levine, Harry

    1950-01-01

    A simple and very rapid fluorimetric procedure is described for the determination of uranium in low-grade shale and phosphate ores. The best working range is from 0.001 to about 0.04 percent U. The procedure employs batch extraction of uranium nitrate by ethyl acetate, using aluminum nitrate as the salting agent, prior to the visual fluorimetric estimation. The procedure is especially designed to save reagents; only 9.5 g of aluminum nitrate and 10 ml of ethyl acetate being used for one analysis. The solution of the sample by means of a fusion with NaOH-NaNO3 flux is rapid. After fusion the sample is immediately extracted without removing silica and other hydrolytic precipitates. Aluminum nitrate very effectively ties up fluoride and phosphate, thus eliminating steps required for their removal.

  19. Development of a fluorescent microsphere technique for rapid histological determination of cerebral blood flow

    PubMed Central

    Eucker, Stephanie A.; Hoffman, Brenton D.; Natesh, Rahul; Ralston, Jill; Armstead, William M.; Margulies, Susan S.

    2010-01-01

    The purpose of this study was to develop a more efficient fluorescent microsphere method to facilitate the rapid use of the histological technique and to enable its use in large tissue regions. Using fluorescent plate/slide imaging technology and automated detection and analysis software, we were able to rapidly image, detect, and count 3 separate microsphere colors in 200 μm-thick tissue sections from piglet brain. In resting newborn piglets (n = 6) on isoflurane anesthesia, we measured a median total cerebral blood flow (CBF) of 105 ml/min/100g (range 27–206 ml/min/100g). Compared with other FM analysis methods, our method reduces the time required to determine blood flow, improves accuracy in lipid-rich tissues and large tissue regions and, unlike the radiolabeled microsphere method, can be combined with histological analysis. PMID:20193669

  20. Fuji apple storage time rapid determination method using Vis/NIR spectroscopy

    PubMed Central

    Liu, Fuqi; Tang, Xuxiang

    2015-01-01

    Fuji apple storage time rapid determination method using visible/near-infrared (Vis/NIR) spectroscopy was studied in this paper. Vis/NIR diffuse reflection spectroscopy responses to samples were measured for 6 days. Spectroscopy data were processed by stochastic resonance (SR). Principal component analysis (PCA) was utilized to analyze original spectroscopy data and SNR eigen value. Results demonstrated that PCA could not totally discriminate Fuji apples using original spectroscopy data. Signal-to-noise ratio (SNR) spectrum clearly classified all apple samples. PCA using SNR spectrum successfully discriminated apple samples. Therefore, Vis/NIR spectroscopy was effective for Fuji apple storage time rapid discrimination. The proposed method is also promising in condition safety control and management for food and environmental laboratories. PMID:25874818

  1. Development of a fluorescent microsphere technique for rapid histological determination of cerebral blood flow.

    PubMed

    Eucker, Stephanie A; Hoffman, Brenton D; Natesh, Rahul; Ralston, Jill; Armstead, William M; Margulies, Susan S

    2010-04-22

    The purpose of this study was to develop a more efficient fluorescent microsphere method to facilitate the rapid use of the histological technique and to enable its use in large tissue regions. Using fluorescent plate/slide imaging technology and automated detection and analysis software, we were able to rapidly image, detect, and count 3 separate microsphere colors in 200 microm thick tissue sections from piglet brain. In resting newborn piglets (n=6) on isoflurane anesthesia, we measured a median total cerebral blood flow (CBF) of 105 ml/min/100g (range 27-206 ml/min/100 g). Compared with other FM analysis methods, our method reduces the time required to determine blood flow, improves accuracy in lipid-rich tissues and large tissue regions and, unlike the radiolabeled microsphere method, can be combined with histological analysis. Copyright 2010 Elsevier B.V. All rights reserved.

  2. A hybrid approach for rapid, accurate, and direct kilovoltage radiation dose calculations in CT voxel space

    SciTech Connect

    Kouznetsov, Alexei; Tambasco, Mauro

    2011-03-15

    Purpose: To develop and validate a fast and accurate method that uses computed tomography (CT) voxel data to estimate absorbed radiation dose at a point of interest (POI) or series of POIs from a kilovoltage (kV) imaging procedure. Methods: The authors developed an approach that computes absorbed radiation dose at a POI by numerically evaluating the linear Boltzmann transport equation (LBTE) using a combination of deterministic and Monte Carlo (MC) techniques. This hybrid approach accounts for material heterogeneity with a level of accuracy comparable to the general MC algorithms. Also, the dose at a POI is computed within seconds using the Intel Core i7 CPU 920 2.67 GHz quad core architecture, and the calculations are performed using CT voxel data, making it flexible and feasible for clinical applications. To validate the method, the authors constructed and acquired a CT scan of a heterogeneous block phantom consisting of a succession of slab densities: Tissue (1.29 cm), bone (2.42 cm), lung (4.84 cm), bone (1.37 cm), and tissue (4.84 cm). Using the hybrid transport method, the authors computed the absorbed doses at a set of points along the central axis and x direction of the phantom for an isotropic 125 kVp photon spectral point source located along the central axis 92.7 cm above the phantom surface. The accuracy of the results was compared to those computed with MCNP, which was cross-validated with EGSnrc, and served as the benchmark for validation. Results: The error in the depth dose ranged from -1.45% to +1.39% with a mean and standard deviation of -0.12% and 0.66%, respectively. The error in the x profile ranged from -1.3% to +0.9%, with standard deviations of -0.3% and 0.5%, respectively. The number of photons required to achieve these results was 1x10{sup 6}. Conclusions: The voxel-based hybrid method evaluates the LBTE rapidly and accurately to estimate the absorbed x-ray dose at any POI or series of POIs from a kV imaging procedure.

  3. A hybrid approach for rapid, accurate, and direct kilovoltage radiation dose calculations in CT voxel space.

    PubMed

    Kouznetsov, Alexei; Tambasco, Mauro

    2011-03-01

    To develop and validate a fast and accurate method that uses computed tomography (CT) voxel data to estimate absorbed radiation dose at a point of interest (POI) or series of POIs from a kilovoltage (kV) imaging procedure. The authors developed an approach that computes absorbed radiation dose at a POI by numerically evaluating the linear Boltzmann transport equation (LBTE) using a combination of deterministic and Monte Carlo (MC) techniques. This hybrid approach accounts for material heterogeneity with a level of accuracy comparable to the general MC algorithms. Also, the dose at a POI is computed within seconds using the Intel Core i7 CPU 920 2.67 GHz quad core architecture, and the calculations are performed using CT voxel data, making it flexible and feasible for clinical applications. To validate the method, the authors constructed and acquired a CT scan of a heterogeneous block phantom consisting of a succession of slab densities: Tissue (1.29 cm), bone (2.42 cm), lung (4.84 cm), bone (1.37 cm), and tissue (4.84 cm). Using the hybrid transport method, the authors computed the absorbed doses at a set of points along the central axis and x direction of the phantom for an isotropic 125 kVp photon spectral point source located along the central axis 92.7 cm above the phantom surface. The accuracy of the results was compared to those computed with MCNP, which was cross-validated with EGSnrc, and served as the benchmark for validation. The error in the depth dose ranged from -1.45% to +1.39% with a mean and standard deviation of -0.12% and 0.66%, respectively. The error in the x profile ranged from -1.3% to +0.9%, with standard deviations of -0.3% and 0.5%, respectively. The number of photons required to achieve these results was 1 x 10(6). The voxel-based hybrid method evaluates the LBTE rapidly and accurately to estimate the absorbed x-ray dose at any POI or series of POIs from a kV imaging procedure.

  4. Simple and rapid determination of homozygous transgenic mice via in vivo fluorescence imaging.

    PubMed

    Lin, Xiaolin; Jia, Junshuang; Qin, Yujuan; Lin, Xia; Li, Wei; Xiao, Gaofang; Li, Yanqing; Xie, Raoying; Huang, Hailu; Zhong, Lin; Wu, Qinghong; Wang, Wanshan; Huang, Wenhua; Yao, Kaitai; Xiao, Dong; Sun, Yan

    2015-11-17

    Setting up breeding programs for transgenic mouse strains require to distinguish homozygous from the heterozygous transgenic animals. The combinational use of the fluorescence reporter transgene and small animal in-vivo imaging system might allow us to rapidly and visually determine the transgenic mice homozygous for transgene(s) by the in vivo fluorescence imaging. RLG, RCLG or Rm17LG transgenic mice ubiquitously express red fluorescent protein (RFP). To identify homozygous RLG transgenic mice, whole-body fluorescence imaging for all of newborn F2-generation littermates produced by mating of RFP-positive heterozygous transgenic mice (F1-generation) derived from the same transgenic founder was performed. Subsequently, the immediate data analysis of the in vivo fluorescence imaging was carried out, which greatly facilitated us to rapidly and readily distinguish RLG transgenic individual(s) with strong fluorescence from the rest of F2-generation littermates, followed by further determining this/these RLG individual(s) showing strong fluorescence to be homozygous, as strongly confirmed by mouse mating. Additionally, homozygous RCLG or Rm17LG transgenic mice were also rapidly and precisely distinguished by the above-mentioned optical approach. This approach allowed us within the shortest time period to obtain 10, 8 and 2 transgenic mice homozygous for RLG, RCLG and Rm17LG transgene, respectively, as verified by mouse mating, indicating the practicality and reliability of this optical method. Taken together, our findings fully demonstrate that the in vivo fluorescence imaging offers a visual, rapid and reliable alternative method to the traditional approaches (i.e., mouse mating and real-time quantitative PCR) in identifying homozygous transgenic mice harboring fluorescence reporter transgene under the control of a ubiquitous promoter in the situation mentioned in this study.

  5. Simple and rapid determination of homozygous transgenic mice via in vivo fluorescence imaging

    PubMed Central

    Li, Wei; Xiao, Gaofang; Li, Yanqing; Xie, Raoying; Huang, Hailu; Zhong, Lin; Wu, Qinghong; Wang, Wanshan; Huang, Wenhua; Yao, Kaitai; Xiao, Dong; Sun, Yan

    2015-01-01

    Setting up breeding programs for transgenic mouse strains require to distinguish homozygous from the heterozygous transgenic animals. The combinational use of the fluorescence reporter transgene and small animal in-vivo imaging system might allow us to rapidly and visually determine the transgenic mice homozygous for transgene(s) by the in vivo fluorescence imaging. RLG, RCLG or Rm17LG transgenic mice ubiquitously express red fluorescent protein (RFP). To identify homozygous RLG transgenic mice, whole-body fluorescence imaging for all of newborn F2-generation littermates produced by mating of RFP-positive heterozygous transgenic mice (F1-generation) derived from the same transgenic founder was performed. Subsequently, the immediate data analysis of the in vivo fluorescence imaging was carried out, which greatly facilitated us to rapidly and readily distinguish RLG transgenic individual(s) with strong fluorescence from the rest of F2-generation littermates, followed by further determining this/these RLG individual(s) showing strong fluorescence to be homozygous, as strongly confirmed by mouse mating. Additionally, homozygous RCLG or Rm17LG transgenic mice were also rapidly and precisely distinguished by the above-mentioned optical approach. This approach allowed us within the shortest time period to obtain 10, 8 and 2 transgenic mice homozygous for RLG, RCLG and Rm17LG transgene, respectively, as verified by mouse mating, indicating the practicality and reliability of this optical method. Taken together, our findings fully demonstrate that the in vivo fluorescence imaging offers a visual, rapid and reliable alternative method to the traditional approaches (i.e., mouse mating and real-time quantitative PCR) in identifying homozygous transgenic mice harboring fluorescence reporter transgene under the control of a ubiquitous promoter in the situation mentioned in this study. PMID:26472024

  6. Direct determination of cryptococcal antigen in transthoracic needle aspirate for diagnosis of pulmonary cryptococcosis.

    PubMed

    Liaw, Y S; Yang, P C; Yu, C J; Chang, D B; Wang, H J; Lee, L N; Kuo, S H; Luh, K T

    1995-06-01

    Pulmonary cryptococcosis causes significant morbidity and mortality in immunocompromised patients. Definitive diagnosis of pulmonary cryptococcosis is usually difficult. The use of direct determination of cryptococcal antigen in transthoracic needle aspirate to diagnose pulmonary cryptococcosis was investigated. Over a 2-year period, we studied a total of 41 patients with respiratory symptoms and pulmonary infiltrates of unknown etiology who were suspected of having pulmonary cryptococcosis. Twenty-two patients were immunocompetent patients and 19 patients were immunocompromised. A diagnosis of pulmonary cryptococcosis was based on cytological examination, culture for Cryptococcus neoformans, histopathologic examination, and clinical response to antifungal therapy. All patients underwent chest ultrasound and ultrasound-guided percutaneous transthoracic needle aspiration to obtain specimens for cryptococcal antigen determination. The presence of cryptococcal antigen was determined by the latex agglutination system (CALAS; Meridian Diagnostics, Cincinnati, Ohio). An antigen titer equal to or greater than 1:8 was considered positive. The specimens were also sent for cytological examination, fungal culture, and/or histopathologic examination. A final diagnosis of pulmonary cryptococcosis was made in eight patients. Direct determinations of cryptococcal antigen in lung aspirate were positive in all eight patients with pulmonary cryptococcosis (100% sensitivity, 97% specificity, a positive predictive value of 89%, and negative value of 100%), and there was only one false-positive in noncryptococcosis patients. The diagnostic accuracy was 97.5%. Serum cryptococcal antigen was positive in only three patients with pulmonary cryptococcosis (sensitivity, 37.5%). This study showed that direct measurement of cryptococcal antigen in lung aspirate can be a rapid and useful test for diagnosis of pulmonary cryptococcosis.

  7. Direct determination of cryptococcal antigen in transthoracic needle aspirate for diagnosis of pulmonary cryptococcosis.

    PubMed Central

    Liaw, Y S; Yang, P C; Yu, C J; Chang, D B; Wang, H J; Lee, L N; Kuo, S H; Luh, K T

    1995-01-01

    Pulmonary cryptococcosis causes significant morbidity and mortality in immunocompromised patients. Definitive diagnosis of pulmonary cryptococcosis is usually difficult. The use of direct determination of cryptococcal antigen in transthoracic needle aspirate to diagnose pulmonary cryptococcosis was investigated. Over a 2-year period, we studied a total of 41 patients with respiratory symptoms and pulmonary infiltrates of unknown etiology who were suspected of having pulmonary cryptococcosis. Twenty-two patients were immunocompetent patients and 19 patients were immunocompromised. A diagnosis of pulmonary cryptococcosis was based on cytological examination, culture for Cryptococcus neoformans, histopathologic examination, and clinical response to antifungal therapy. All patients underwent chest ultrasound and ultrasound-guided percutaneous transthoracic needle aspiration to obtain specimens for cryptococcal antigen determination. The presence of cryptococcal antigen was determined by the latex agglutination system (CALAS; Meridian Diagnostics, Cincinnati, Ohio). An antigen titer equal to or greater than 1:8 was considered positive. The specimens were also sent for cytological examination, fungal culture, and/or histopathologic examination. A final diagnosis of pulmonary cryptococcosis was made in eight patients. Direct determinations of cryptococcal antigen in lung aspirate were positive in all eight patients with pulmonary cryptococcosis (100% sensitivity, 97% specificity, a positive predictive value of 89%, and negative value of 100%), and there was only one false-positive in noncryptococcosis patients. The diagnostic accuracy was 97.5%. Serum cryptococcal antigen was positive in only three patients with pulmonary cryptococcosis (sensitivity, 37.5%). This study showed that direct measurement of cryptococcal antigen in lung aspirate can be a rapid and useful test for diagnosis of pulmonary cryptococcosis. PMID:7650192

  8. [Study on rapid determination and analysis of rocket kerosene by near infrared spectrum and chemometrics].

    PubMed

    Xia, Ben-Li; Cong, Ji-Xin; Li, Xia; Wang, Xuan-Jun

    2011-06-01

    The rocket kerosene quality properties such as density, distillation range, viscosity and iodine value were successfully measured based on their near-infrared spectrum (NIRS) and chemometrics. In the present paper, more than 70 rocket kerosene samples were determined by near infrared spectrum, the models were built using the partial least squares method within the appropriate wavelength range. The correlation coefficients (R2) of every rocket kerosene's quality properties ranged from 0.862 to 0.999. Ten unknown samples were determined with the model, and the result showed that the prediction accuracy of near infrared spectrum method accords with standard analysis requirements. The new method is well suitable for replacing the traditional standard method to rapidly determine the properties of the rocket kerosene.

  9. Microwave-assisted rapid determination of vitamins a and e in beverages.

    PubMed

    Höller, Ulrich; Wolter, Didier; Hofmann, Peter; Spitzer, Volker

    2003-03-12

    A new rapid procedure for the determination of vitamins A and E in beverages has been developed and validated. Key steps include a microwave-assisted saponification of the sample and a single-step extraction of the vitamins prior to HPLC analysis. All sample preparation steps are carried out consecutively in the same vial. The vitamins are determined using normal-phase (Si-60) HPLC with fluorescence detection. The method is applicable to beverages with a content of all-trans-retinol >0.14 mg/L and/or a content of alpha-tocopherol >1 mg/L. Recoveries determined by spiking experiments ranged from 91.3 to 106.3%. The precision of the method is characterized by relative standard deviations of <2% for alpha-tocopherol and <5% for all-trans-retinol.

  10. Rapid and reproducible determination of active gibberellins in citrus tissues by UPLC/ESI-MS/MS.

    PubMed

    Manzi, Matías; Gómez-Cadenas, Aurelio; Arbona, Vicent

    2015-09-01

    Phytohormone determination is crucial to explain the physiological mechanisms during growth and development. Therefore, rapid and precise methods are needed to achieve reproducible determination of phytohormones. Among many others, gibberellins (GAs) constitute a family of complex analytes as most of them share similar structure and chemical properties although only a few hold biological activity (namely GA1; GA3; GA4 and GA7). A method has been developed to extract GAs from plant tissues by mechanical disruption using ultrapure water as solvent and, in this way, ion suppression was reduced whereas sensitivity increased. Using this methodology, the four active GAs were separated and quantified by UPLC coupled to MS/MS using the isotope-labeled internal standards [(2)H2]-GA1 and [(2)H2]-GA4. To sum up, the new method provides a fast and reproducible protocol to determine bioactive GAs at low concentrations, using minimal amounts of sample and reducing the use of organic solvents.

  11. Simultaneous and rapid determination of multiple component concentrations in a Kraft liquor process stream

    DOEpatents

    Li, Jian; Chai, Xin Sheng; Zhu, Junyoung

    2008-06-24

    The present invention is a rapid method of determining the concentration of the major components in a chemical stream. The present invention is also a simple, low cost, device of determining the in-situ concentration of the major components in a chemical stream. In particular, the present invention provides a useful method for simultaneously determining the concentrations of sodium hydroxide, sodium sulfide and sodium carbonate in aqueous kraft pulping liquors through use of an attenuated total reflectance (ATR) tunnel flow cell or optical probe capable of producing a ultraviolet absorbency spectrum over a wavelength of 190 to 300 nm. In addition, the present invention eliminates the need for manual sampling and dilution previously required to generate analyzable samples. The inventive method can be used in Kraft pulping operations to control white liquor causticizing efficiency, sulfate reduction efficiency in green liquor, oxidation efficiency for oxidized white liquor and the active and effective alkali charge to kraft pulping operations.

  12. New and rapid analytical procedure for water content determination: microwave accelerated Dean-Stark.

    PubMed

    Veillet, Sébastien; Tomao, Valérie; Visinoni, Franco; Chemat, Farid

    2009-01-26

    Development of new procedures in analytical chemistry is currently increasingly focussed on reducing the time, cost and energy to carry out routine analyses. The conventional Dean-Stark (CDS) distillation to determine the water content is one of the most commonly used analytical methods and uses large amounts of solvent and energy. A new microwave accelerated Dean-Stark (MADS) distillation is presented as an alternative procedure. Microwaves were applied to a mixture of toluene, Weflon stir bar and olives, and the corresponding water was collected in a Dean-Stark receiver. This procedure permits fast and efficient determination of the water content of olives. Reliability and reproducibility were evaluated using statistical analyses. Different matrices were then used with MADS and the results were compared to CDS. Water determination from olives with MADS was better than that with CDS in terms of energy saving, rapidity (10 min versus 120 min), reproducibility, and cleanliness.

  13. Development of rapid slurry methods for flame and direct current plasma emission and graphite furnace atomic absorption analysis of solid animal tissue

    SciTech Connect

    Fietkau, R.

    1986-01-01

    Studies are presented describing developments in the rapid, direct atomic spectrochemical analysis of meat samples by the technique of slurry atomization. The number of elements that can be determined in meat slurry samples has been increased and the concentration range that can be detected extended to included analysis at the part per billion as well as the percent level. Slurry atomization involves the rapid preparation procedure whereby the sample is simple homogenized with deionized distilled water prior to analysis. In this manner, rapid, quantitative analysis of hot dogs (processed meat) for dietary salt (Na, K) was achieved by premixed air-natural gas flame emission spectrometry. Quantitative analysis of mechanically separated meat for residual bone fragments (as Ca) was attained using a simple photometer when the premixed air-acetylene flame was used. The phosphate interference of the Ca emission signal was overcome by placing an insert in the spray chamber which decreased the droplet size of the aerosol reaching the flame. Slight matrix modification in the form of 2% nitric acid was necessary to solubilize the Ca from the bone fragments. Determining elements present at very low concentrations i.e. part per billion levels, in homogenized beef liver was evaluated using graphite furnace atomic absorption and shown to be viable for determinations of Pb, Cd, Cr, and Ni. Qualitative multielement analysis of several types of meat slurries by direct current plasma (DCP) emission spectrometry using both photographic and electronic modes of detection was reported for the first time.

  14. Rapid method for design and fabrication of passive micromixers in microfluidic devices using a direct-printing process.

    PubMed

    Liu, Ai-Lin; He, Feng-yun; Wang, Kang; Zhou, Ting; Lu, Yu; Xia, Xing-hua

    2005-09-01

    We developed a facile and rapid one-step technique for design and fabrication of passive micromixers in microfluidic devices using a direct-printing process. A laser printing mechanism was dexterously adopted to pattern the microchannels with different gray levels using vector graphic software. With the present method, periodically ordered specific bas-relief microstructures can be easily fabricated on transparencies by a simple printing process. The size and shape of the resultant microstructures are determined by the gray level of the graphic software and the resolution of the laser printer. Patterns of specific bas-relief microstructures on the floor of a channel act as obstacles in the flow path for advection mixing, which can be used as efficient mixing elements. The mixing effect of the resultant micromixer in microfluidic devices was evaluated using CCD fluorescence spectroscopy. We found that the mixing performance depends strongly on the gray level values. Under optimal conditions, fast passive mixing with our periodic ordered patterns in microfluidic devices has been achieved at the very early stages of the laminar flow. In addition, fabrication of micromixers using the present versatile technique requires less than an hour. The present method is promising for fabrication of micromixers in microfluidic devices at low cost and without complicated devices and environment, providing a simple solution to mixing problems in the micro-total-analysis-systems field.

  15. Determination of wood grain direction from laser light scattering pattern

    NASA Astrophysics Data System (ADS)

    Simonaho, Simo-Pekka; Palviainen, Jari; Tolonen, Yrjö; Silvennoinen, Raimo

    2004-01-01

    Laser light scattering patterns from the grains of wood are investigated in detail to gain information about the characteristics of scattering patterns related to the direction of the grains. For this purpose, wood samples of Scots pine ( Pinus sylvestris L.) and silver birch ( Betula pubescens) were investigated. The orientation and shape of the scattering pattern of laser light in wood was found to correlate well with the direction of grain angles in a three-dimensional domain. The proposed method was also experimentally verified.

  16. A Design Methodology for Rapid Implementation of Active Control Systems Across Lean Direct Injection Combustor Platforms

    NASA Technical Reports Server (NTRS)

    Baumann, William T.; Saunders, William R.; Vandsburger, Uri; Saus, Joseph (Technical Monitor)

    2003-01-01

    The VACCG team is comprised of engineers at Virginia Tech who specialize in the subject areas of combustion physics, chemical kinetics, dynamics and controls, and signal processing. Currently, the team's work on this NRA research grant is designed to determine key factors that influence combustion control performance through a blend of theoretical and experimental investigations targeting design and demonstration of active control for three different combustors. To validiate the accuracy of conclusions about control effectiveness, a sequence of experimental verifications on increasingly complex lean, direct injection combustors is underway. During the work period January 1, 2002 through October 15, 2002, work has focused on two different laboratory-scale combustors that allow access for a wide variety of measurements. As the grant work proceeds, one key goal will be to obtain certain knowledge about a particular combustor process using a minimum of sophisticated measurements, due to the practical limitations of measurements on full-scale combustors. In the second year, results obtained in the first year will be validated on test combustors to be identified in the first quarter of that year. In the third year, it is proposed to validate the results at more realistic pressure and power levels by utilizing the facilities at the Glenn Research Center.

  17. Rapid, simultaneous determination of headspace oxygen and moisture in pharmaceutical packages using muGC.

    PubMed

    Xu, Hui; Templeton, Allen C; Zwierzynski, Marta; Mahajan, Rajiv; Reed, Robert A

    2005-06-15

    The rapid, accurate determination of headspace oxygen and moisture in various pharmaceutical packages is important for both product packaging development and the implementation of new packaging technologies. Current headspace oxygen measurement techniques suffer from serious drawbacks in terms of potential sampling contamination, lengthy analysis times, and large required analysis volumes. In addition, relatively few techniques currently exist for the convenient determination of headspace moisture in packaging systems. Efforts herein focused on the development and application of a new method for the rapid and simultaneous determination of headspace oxygen and moisture in pharmaceutical packages using micro-gas chromatography (muGC). Studies showed that both headspace oxygen and moisture could be simultaneously quantified in <90 s on sample volumes of 50-100 microL by employing muGC with dual chromatographic analysis modules. Sampling issues common to manual syringe-based injections were also alleviated in the current studies by use of the built-in diaphragm pump sampling interface of the portable muGC system. The performance of the analytical approach was evaluated and shown to exhibit excellent linearity, accuracy, and precision for both analytes. High sensitivity for headspace oxygen was demonstrated, allowing for levels of oxygen as low as 0.03% to be accurately quantified. The subject method was applied to measure the headspace oxygen and moisture in pharmaceutical blister packaging and glass vials.

  18. Determination of camptothecins in DMSO extracts of Nothapodytes foetida by direct injection capillary electrophoresis.

    PubMed

    Hsiao, Hsien-Yi; Cheng, Tzong-Jih; Yang, Ge-Ming; Huang, I-Jen; Chen, Richie L C

    2008-01-01

    A rapid capillary electrophoresis procedure was developed for determining the anti-cancer components, camptothecins, in Nothapodytes foetida. The hydrophobic compound was extracted from plant tissue (ca. 1 mL of DMSO for 100 mg of dried plant tissue) with a water-miscible organic solvent, DMSO, at elevated temperature (60 degrees C). The extract was directly injected into the separation capillary (untreated fused silica, 34 cm in length, 75 microm i.d.) and analysed in MEKC mode (369 nm). Within 5 min of migration, camptothecins were successfully separated and quantified by adding organic modifiers to the running buffer (20% DMSO, 90 mm SDS in 10 mm borate buffer, pH 8.60). The linear dynamic range for camptothecin was from 5 to 400 microg/mL. This method was proven to be very suitable for monitoring the amount of camptothecins during the cultivation of the medicinal plant. Copyright 2007 John Wiley & Sons, Ltd.

  19. Determining Wind Speed and Direction with Ocean Reflected GPS Signals

    NASA Technical Reports Server (NTRS)

    Zuffada, C.; Elfouhaily, T.

    2000-01-01

    The power received by a GPS receiver located on an airplane flying over the ocean and collecting the GPS signal reflected off the surface is estimated for varying wind speed and wind direction, platform altitude, satellite elevation angle, and receiver integration time.

  20. A Model for Determining New Directions for Women

    ERIC Educational Resources Information Center

    Wright, Margaret A.

    1975-01-01

    Many mature women reach a decision-making point where a desire to change the direction of their lives is quite evident, but how to implement that change is unclear. Presented is a five part guidance model which provides steps useful in working with the mature woman in her mid-life role change. (Author)

  1. Critical-Point Drying: Rapid Method for the Determination of Bacterial Extracellular Polymer and Surface Structures

    PubMed Central

    Cagle, Gerald D.

    1974-01-01

    The relative amount of extracellular polymer which remains about Azotobacter vinelandii, Zoogloea ramigera, Klebsiella pneumoniae, and Diplococcus pneumoniae after critical-point drying was studied by electron microscopy. The results obtained with this technique are compared to those obtained with methods that illustrate extracellular polymer, such as freeze-etching and ruthenium red staining. Comparative results indicate critical-point drying to be a rapid, reliable method for the determination of capsule-like polymer surrounding bacterial cells. In addition, critical-point drying can be used to observe morphogenetic changes, such as vesicle production. Images PMID:4136617

  2. Rapid method for the determination of 226Ra in hydraulic fracturing wastewater samples

    DOE PAGES

    Maxwell, Sherrod L.; Culligan, Brian K.; Warren, Richard A.; ...

    2016-03-24

    A new method that rapidly preconcentrates and measures 226Ra from hydraulic fracturing wastewater samples was developed in the Savannah River Environmental Laboratory. The method improves the quality of 226Ra measurements using gamma spectrometry by providing up to 100x preconcentration of 226Ra from this difficult sample matrix, which contains very high levels of calcium, barium, strontium, magnesium and sodium. The high chemical yield, typically 80-90%, facilitates a low detection limit, important for lower level samples, and indicates method ruggedness. Ba-133 tracer is used to determine chemical yield and correct for geometry-related counting issues. The 226Ra sample preparation takes < 2 hours.

  3. Rapid photometric determination of phosphorus in iron ores and related materials as phosphomolybdenum-blue.

    PubMed

    Bhargava, O P; Gmitro, M

    1984-04-01

    A rapid, simple and accurate method for determining phosphorus photometrically in iron ores and related materials, obviating the use of perchloric acid, is described. The sample is fused with sodium peroxide in a zirconium crucible and the melt dissolved in hydrochloric acid. The molybdenum-blue complex is developed by the addition of ammonium molybdate and hydrazine sulphate and the absorbance is measured at 725 nm. The range of the method is from 0.005 to 1.0% P. A batch of 6 samples can be analysed in about 2 hr.

  4. Ultra-rapid earth rotation determination with VLBI during CONT11 and CONT14

    NASA Astrophysics Data System (ADS)

    Haas, Rüdiger; Hobiger, Thomas; Kurihara, Shinobu; Hara, Tetsuya

    2017-07-01

    We present earth rotation results from the ultra-rapid operations during the continuous VLBI campaigns CONT11 and CONT14. The baseline Onsala-Tsukuba, i.e., using two out of the 13 and 17 stations contributing to CONT11 and CONT14, respectively, was used to derive UT1-UTC in ultra-rapid mode during the ongoing campaigns. The latency between a new observation and a new UT1-UTC result was less than 10 min for more than 95% of the observations. The accuracy of the derived ultra-rapid UT1-UTC results is approximately a factor of three worse than results from optimized one-baseline sessions and/or complete analysis of large VLBI networks. This is, however, due to that the one-baseline picked from the CONT campaigns is not optimized for earth rotation determination. Our results prove that the 24/7 operation mode planned for VGOS, the next-generation VLBI system, is possible already today. However, further improvements in data connectivity of stations and correlators as well in the automated analysis are necessary to realize the ambitious VGOS plans.

  5. Rapid detection and simultaneous antibiotic susceptibility analysis of Yersinia pestis directly from clinical specimens by use of reporter phage.

    PubMed

    Vandamm, J P; Rajanna, C; Sharp, N J; Molineux, I J; Schofield, D A

    2014-08-01

    Yersinia pestis is a tier 1 agent due to its contagious pneumopathogenicity, extremely rapid progression, and high mortality rate. As the disease is usually fatal without appropriate therapy, rapid detection from clinical matrices is critical to patient outcomes. We previously engineered the diagnostic phage ΦA1122 with luxAB to create a "light-tagged" reporter phage. ΦA1122::luxAB rapidly detects Y. pestis in pure culture and human serum by transducing a bioluminescent signal response. In this report, we assessed the analytical specificity of the reporter phage and investigated diagnostic utility (detection and antibiotic susceptibility analysis) directly from spiked whole blood. The bioreporter displayed 100% (n = 59) inclusivity for Y. pestis and consistent intraspecific signal transduction levels. False positives were not obtained from species typically associated with bacteremia or those relevant to plague diagnosis. However, some non-pestis Yersinia strains and Enterobacteriaceae did elicit signals, albeit at highly attenuated transduction levels. Diagnostic performance was assayed in simple broth-enriched blood samples and standard aerobic culture bottles. In blood, <10(2) CFU/ml was detected within 5 h. In addition, Y. pestis was identified directly from positive blood cultures within 20 to 45 min without further processing. Importantly, coincubation of blood samples with antibiotics facilitated simultaneous antimicrobial susceptibility profiling. Consequently, the reporter phage demonstrated rapid detection and antibiotic susceptibility profiling directly from clinical samples, features that may improve patient prognosis during plague outbreaks.

  6. Rapid Detection of Microorganisms--State of Art and Future Directions

    NASA Astrophysics Data System (ADS)

    Hong, George

    2008-03-01

    For the last several decades, nutrient-based culture growth methods have been accepted as the standard for microorganism detection and identification. However, since the discovery of nucleic acids and molecular breakthrough technologies such as restriction enzymes and polymerase chain reactions, the detection and identification of microorganisms have advanced to culture-independent methods that fall under the category of rapid microbial detections. Here, we present an overview of major rapid microbial detection technologies. These technologies will include both amplification and non-amplification based methods for the detection and identification of target microorganisms. The technologies described can be applied to detecting a wide variety of microorganisms, including bacteria, viruses, mycoplasma, and fungi and have the potential sensitivity to detect a single microorganism. Also in this presentation, we will present examples of real-life applications as well as future challenges for the advancement of the field of rapid microbiology.

  7. Comparison of cone directionality determined by psychophysical and reflectometric techniques

    SciTech Connect

    He, J.C.; Marcos, S.; Burns, S.A.

    1999-10-01

    We measured the directionality of the cones with both a psychophysical (Stiles{endash}Crawford I) technique and an optical technique. The two sets of measurements were made in the same subjects, with stimuli as similar as possible used. The two types of measurements gave similar estimates of the location in the pupil toward which the cones were optimally aligned. However, the two measurements gave quite dissimilar estimates of the width of the directional sensitivity. On average, optical measurements were half as broad as psychophysical measurements in the fovea, but there were substantial individual differences. At 2-deg retinal eccentricity the difference between techniques was even more marked. {copyright} 1999 Optical Society of America

  8. Ionized Gaseous Nebulae Abundance Determination from the Direct Method

    NASA Astrophysics Data System (ADS)

    Pérez-Montero, Enrique

    2017-04-01

    This tutorial explains the procedure used to analyze an optical emission-line spectrum produced by a nebula ionized by massive star formation. Particularly, the methodology used to derive physical properties, such as electron density and temperature, and the ionic abundances of the most representative elements whose emission lines are present in the optical spectrum is described. The main focus is on the direct method, which is based on the measurement of the electron temperature to derive the abundances, given that the ionization and thermal equilibrium of the ionized gas is dominated by the metallicity. The ionization correction factors used to obtain total abundances from the abundances of some of their ions are also given. Finally, some strong-line methods to derive abundances are described. Such methods are used when no estimation of the temperature can be derived, but which can be consistent with the direct method if they are empirically calibrated.

  9. Rapid determination of moisture content in paper materials by multiple headspace extraction gas chromatography.

    PubMed

    Xie, Wei-Qi; Chai, Xin-Sheng

    2016-04-22

    This paper describes a new method for the rapid determination of the moisture content in paper materials. The method is based on multiple headspace extraction gas chromatography (MHE-GC) at a temperature above the boiling point of water, from which an integrated water loss from the tested sample due to evaporation can be measured and from which the moisture content in the sample can be determined. The results show that the new method has a good precision (with the relative standard deviation <0.96%), high sensitivity (the limit of quantitation=0.005%) and good accuracy (the relative differences <1.4%). Therefore, the method is quite suitable for many uses in research and industrial applications.

  10. [Rapid determination of Sudan dyes adulterated in natural paprika red by FTIR].

    PubMed

    Zhang, Wei-wei; Liu, Ling-ling; Wu, Yan-wen; Ouyang, Jie; Sun, Su-qin

    2012-04-01

    How to rapidly determine synthesized pigments or dyes adulterated in natural pigments is a difficult problem for food analysts. Natural paprika red is widely used in foods because of its coloration and pharmaceutical effect, but it is sometimes adulterated with Sudan dyes for its poor stability under light or heat treatment. In the present paper, the macro-fingerprint characteristic of infrared spectroscopy was utilized to identify Sudan dyes adulterated in paprika red. The strong peaks at 1 621, 1 500 and 751 cm(-1) in FTIR spectra and at the fingerprint region of 753, 684 and 496 cm(-1) in the secondary deriative FTIR spectra were remarkable characteristics for Sudan dyes adulterated in paprika red, of which the limit of determination was about 1%.

  11. Rapid determination of formaldehyde in sanitary paper napkins for product quality control by headspace gas chromatography.

    PubMed

    Hu, Hui-Chao; Tian, Ying-Xin; Chai, Xin-Sheng

    2012-01-01

    This study reports on a headspace gas chromatographic method (HS-GC) for the determination of formaldehyde in sanitary napkin samples. The method is based on the reaction of formaldehyde and sodium borohydride in a concentrated potassium carbonate solution (824 g/L), in which formaldehyde is quantitatively converted to methanol at 105°C in 45 min. The methanol from the conversion is determined by HS-GC. The repeatability of the method had a relative standard deviation of less than 4.5%; the limit of quantification (LOQ) was 1.17 µg, and the recovery ranged from 96.8 - 106%. The present method is simple, rapid, and accurate. It is suitable for use in the batch testing for product quality control of tissue papers during the manufacturing process and in analysis of point-of-sale samples from commercial markets.

  12. Rapid and sensitive HPLC method for the simultaneous determination of paraquat and diquat in human serum.

    PubMed

    Hara, Shuuji; Sasaki, Noriaki; Takase, Daizi; Shiotsuka, Shouichi; Ogata, Kentaro; Futagami, Koujiro; Tamura, Kazuo

    2007-05-01

    A rapid and sensitive HPLC method for the simultaneous determination of paraquat and diquat in human serum has been developed. After deproteinization of the serum with 10% trichloroacetic acid, the samples were separated on a reversed-phase column, and subsequently reduced to their radicals with alkaline sodium hydrosulfite solution. These radicals were monitored with a UV detector at 391 nm. This method permitted the reliable quantification of paraquat over linear ranges of 50 ng - 10 microg/ml and 100 ng - 10 microg/ml for diquat in human serum. The within- and between-day variations are lower than 2.3 and 2.2%, respectively. This technique was also utilized to determine the paraquat and diquat serum levels in a patient who had ingested herbicide (Prigrox L) containing paraquat and diquat.

  13. Limits of rapid log P determination methods for highly lipophilic and flexible compounds.

    PubMed

    Martel, Sophie; Begnaud, Frédéric; Schuler, William; Gillerat, Fabrice; Oberhauser, Nils; Nurisso, Alessandra; Carrupt, Pierre-Alain

    2016-04-07

    Lipophilicity is of crucial importance in many fields including pharmaceutical, environmental, cosmetic and food industries. Whereas different experimental strategies have been developed for rapid lipophilicity determination of new chemical entities, log P determination of highly lipophilic compounds is always challenging. In this study, three published chromatographic methods have been compared on a series of phenylalkanoic acids including the pro-perfume HaloscentD (HD-C12). Different log P values were obtained depending on the chromatographic method used for log P estimation. Molecular modelling suggested that log P variations may be due to the chromatographic conditions applied (isocratic or gradient mode, ratio methanol/water in the mobile phase), responsible of specific conformations of the molecule in solution. Thus, for flexible compounds, published methods have to be used with caution and considered as a good tool to estimate a log P range, depending on the molecular conformational state.

  14. Directional Effects between Rapid Auditory Processing and Phonological Awareness in Children

    ERIC Educational Resources Information Center

    Johnson, Erin Phinney; Pennington, Bruce F.; Lee, Nancy Raitano; Boada, Richard

    2009-01-01

    Background: Deficient rapid auditory processing (RAP) has been associated with early language impairment and dyslexia. Using an auditory masking paradigm, children with language disabilities perform selectively worse than controls at detecting a tone in a backward masking (BM) condition (tone followed by white noise) compared to a forward masking…

  15. Directional Effects between Rapid Auditory Processing and Phonological Awareness in Children

    ERIC Educational Resources Information Center

    Johnson, Erin Phinney; Pennington, Bruce F.; Lee, Nancy Raitano; Boada, Richard

    2009-01-01

    Background: Deficient rapid auditory processing (RAP) has been associated with early language impairment and dyslexia. Using an auditory masking paradigm, children with language disabilities perform selectively worse than controls at detecting a tone in a backward masking (BM) condition (tone followed by white noise) compared to a forward masking…

  16. A Facile CD Protocol for Rapid Determination of Enantiomeric Excess and Concentration of Chiral Primary Amines

    PubMed Central

    Nieto, Sonia; Dragna, Justin M.; Anslyn, Eric V.

    2010-01-01

    A protocol for the rapid determination of the absolute configuration and enantiomeric excess of α-chiral primary amines with potential applications in asymmetric reaction discovery has been developed. The protocol requires derivatization of α-chiral primary amines via condensation with pyridine carboxaldehyde to quantitatively yield the corresponding imine. The Cu(I) complex with 2,2'-bis (diphenylphosphino)-1,1'-dinaphthyl (BINAP -CuI) with the imine yields a metal-to-ligand-charge-transfer band (MLCT) in the visible region of the circular dichroism spectrum upon binding. Diastereomeric host-guest complexes give CD signals of the same signs, but different amplitudes, allowing for differentiation of enantiomers. Processing the primary optical data from the CD spectrum with linear discriminant analysis (LDA) allows for the determination of absolute configuration and identification of the amines, and processing with a supervised multi-layer perceptron artifical neural network (MLP-ANN) allows for the simultaneous determination of ee and concentration. The primary optical data necessary to determine the ee of unknown samples is obtained in 2 minutes per sample. To demonstrate the utility of the protocol in asymmetric reaction discovery, the ee's and concentrations for an asymmetric metal catalyzed reaction are determined. The potential of the protocol's application in high-throughput screening (HTS) of ee is discussed. PMID:19946914

  17. Rapid determination of furfural in biomass hydrolysate by full evaporation headspace gas chromatography.

    PubMed

    Li, Hailong; Chai, Xin-Sheng; Zhan, Huaiyu; Fu, Shiyu

    2010-11-26

    This paper reports a full evaporation (FE) headspace gas chromatographic (HS-GC) method for rapid determination of furfural in the biomass hydrolysate. The data show that a near-complete mass transfer of furfural in the sample from biomass hydrolysate to the vapor phase (headspace) was achieved within 3 min at 105°C when a very small (<40 μL) sample was added to a 20 mL headspace sample vial. The acid-catalyzed furfural decomposition under these conditions was negligible. The furfural in the vapor phase was then determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD<0.5%) and accuracy (recovery=100.2±1.7%) for furfural quantification in carbohydrate hydrolysate samples. The method requires no sample pretreatment, so it is simple, rapid and accurate, and suitable for applications in lignocellulosic biomass conversion to fuel ethanol or other high value-added products.

  18. A RAPID SPECTROSCOPIC TECHNIQUE FOR DETERMINING THE POTENTIAL ALPHA ENERGY CONCENTRATION OF RADON DECAY PRODUCTS

    SciTech Connect

    Revzan, K. L.; Nazaroff, W. W.

    1981-07-01

    We consider the application of alpha spectroscopy to the rapid determination of the potential alpha energy concentration (PAEC) of radon decay products indoors. Two count totals are obtained after a single counting period. The PAEC is then estimated by a linear combination of the count totals, the two coefficients being determined by analysis of the dependence of the statistical and procedural errors on the equilibrium conditions and the sampling, delay, and counting times. For a total measurement time of 11 min, the procedural error is unlikely to exceed 20% for equilibrium conditions commonly found indoors; the statistical error is less than 20% at a PAEC of 0.005 WL, assuming a product of detector efficiency and flow rate of at least 1.0 l/min. An analysis is made of techniques based on a total alpha count, and the results are compared with those obtained with the rapid spectroscopic technique; the latter is clearly preferable when the measurement time does not exceed 15 min.

  19. NIR rapid assessments of Chinese material medica: simultaneous determination of three major active components of licorice

    NASA Astrophysics Data System (ADS)

    Wu, Zhisheng; Zhou, Xiangzhen; Yu, Fulai; Shi, Xinyuan; Wang, Wenquan; Qiao, Yanjiang

    2014-11-01

    Objective: A rapid and nondestructive method was used to quantitatively predict the content of three main active components (glycyrrhizin, liquiritin and isoliquiritin) in licorice by near infrared spectroscopy (NIRS). Methods: Diffuse reflectance spectra of licorice powder were obtained, the contents of glycyrrhizin, liquiritin and isoliquiritin were analyzed simultaneously by high-performance liquid chromatography (HPLC). The partial least squares (PLS) regression algorithm was used to establish the quantitative models. Several pretreatments such as multiplicative scatter correction (MSC), first derivative, second derivative and Savitzky-Golay (SG) smoothing were utilized to correct the scattering effect and eliminate the baseline shift in all spectra. The calibration equations produced the highest determination of coefficient values (R2), the lowest root mean square error of calibration (RMSEC) and the lowest root mean square error of prediction (RMSEP) were used for the determination of glycyrrhizin, liquiritin and isoliquiritin. Results: The R2 of glycyrrhizin, liquiritin and isoliquiritin were 0.999, 0.996 and 0.999, respectively. The RMSEC of glycyrrhizin, liquiritin and isoliquiritin were 1.14 mg/g, 0.77 mg/g and 0.068 mg/g respectively. The RMSEP of glycyrrhizin, liquiritin and isoliquiritin were 4.92 mg/g, 2.06 mg/g and 0.35 mg/g respectively. Conclusions: The results indicated that the NIRS method could be used for the rapid assessment of licorice.

  20. Direct PCR - A rapid method for multiplexed detection of different serotypes of Salmonella in enriched pork meat samples.

    PubMed

    Chin, Wai Hoe; Sun, Yi; Høgberg, Jonas; Quyen, Than Linh; Engelsmann, Pia; Wolff, Anders; Bang, Dang Duong

    2017-04-01

    Salmonellosis, an infectious disease caused by Salmonella spp., is one of the most common foodborne diseases. Isolation and identification of Salmonella by conventional bacterial culture method is time consuming. In response to the demand for rapid on line or at site detection of pathogens, in this study, we developed a multiplex Direct PCR method for rapid detection of different Salmonella serotypes directly from pork meat samples without any DNA purification steps. An inhibitor-resistant Phusion Pfu DNA polymerase was used to overcome PCR inhibition. Four pairs of primers including a pair of newly designed primers targeting Salmonella spp. at subtype level were incorporated in the multiplex Direct PCR. To maximize the efficiency of the Direct PCR, the ratio between sample and dilution buffer was optimized. The sensitivity and specificity of the multiplex Direct PCR were tested using naturally contaminated pork meat samples for detecting and subtyping of Salmonella spp. Conventional bacterial culture methods were used as reference to evaluate the performance of the multiplex Direct PCR. Relative accuracy, sensitivity and specificity of 98.8%; 97.6% and 100%, respectively, were achieved by the method. Application of the multiplex Direct PCR to detect Salmonella in pork meat at slaughter reduces the time of detection from 5 to 6 days by conventional bacterial culture and serotyping methods to 14 h (including 12 h enrichment time). Furthermore, the method poses a possibility of miniaturization and integration into a point-of-need Lab-on-a-chip system for rapid online pathogen detection. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Direct nitrate reductase assay versus microscopic observation drug susceptibility test for rapid detection of MDR-TB in Uganda.

    PubMed

    Bwanga, Freddie; Haile, Melle; Joloba, Moses L; Ochom, Emmanuel; Hoffner, Sven

    2011-05-09

    The most common method for detection of drug resistant (DR) TB in resource-limited settings (RLSs) is indirect susceptibility testing on Lowenstein-Jensen medium (LJ) which is very time consuming with results available only after 2-3 months. Effective therapy of DR TB is therefore markedly delayed and patients can transmit resistant strains. Rapid and accurate tests suitable for RLSs in the diagnosis of DR TB are thus highly needed. In this study we compared two direct techniques--Nitrate Reductase Assay (NRA) and Microscopic Observation Drug Susceptibility (MODS) for rapid detection of MDR-TB in a high burden RLS. The sensitivity, specificity, and proportion of interpretable results were studied. Smear positive sputum was collected from 245 consecutive re-treatment TB patients attending a TB clinic in Kampala, Uganda. Samples were processed at the national reference laboratory and tested for susceptibility to rifampicin and isoniazid with direct NRA, direct MODS and the indirect LJ proportion method as reference. A total of 229 specimens were confirmed as M. tuberculosis, of these interpretable results were obtained in 217 (95%) with either the NRA or MODS. Sensitivity, specificity and kappa agreement for MDR-TB diagnosis was 97%, 98% and 0.93 with the NRA; and 87%, 95% and 0.78 with the MODS, respectively. The median time to results was 10, 7 and 64 days with NRA, MODS and the reference technique, respectively. The cost of laboratory supplies per sample was low, around 5 USD, for the rapid tests. The direct NRA and MODS offered rapid detection of resistance almost eight weeks earlier than with the reference method. In the study settings, the direct NRA was highly sensitive and specific. We consider it to have a strong potential for timely detection of MDR-TB in RLS.

  2. The Organizing Circumstance: Environmental Determinants in Self-Directed Learning.

    ERIC Educational Resources Information Center

    Spear, George E.; Mocker, Donald W.

    A qualitative analysis of adults' descriptions of their learning activities was conducted to determine those factors that organize nonformal learning but which apparently lie beyond the consciousness of the learner. It was hypothesized that the organizing circumstance (organizing factors external to the learner), rather than preplanning by the…

  3. Direct detection of idiotypic determinants on blotted monoclonal antibodies.

    PubMed

    Petit, C; Sauron, M E; Gilbert, M; Thèze, J

    1982-01-01

    The protein-blotting technique has been tested as a mean to study the expression of idiotypic determinants. A monoclonal BALB/c antipoly (Glu60-Ala30-Tyr10) GAT antibody (G5) was caused to migrate on SDS gel and transferred to a nitrocellulose filter. To facilitate the renaturation of the idiotypic determinants, the blotted proteins were incubated in NP40 buffer, immediately after the transfer. The ability of two anti-idiotypic sera to detect two defined idiotypic specificities of the blotted G5 molecules was investigated. When G5 was electrophoresed on SDS gel under non-reducing conditions, a specific detection of two idiotypic specificities of the G5-blotted molecules was obtained. On the other hand, when G5 was migrated under reducing conditions, none of the two antiidiotypic sera gave a staining of the heavy and the light chains. This result indicates that molecules expressing conformational idiotypic determinants can be detected by protein-blotting technique after migration on SDS gel. Moreover, this suggests the possible interest of this technique to analyse non-antibody molecules bearing idiotypic determinants.

  4. Determine Earthquake Rupture Directivity Using Taiwan TSMIP Strong Motion Waveforms

    NASA Astrophysics Data System (ADS)

    Chang, Kaiwen; Chi, Wu-Cheng; Lai, Ying-Ju; Gung, YuanCheng

    2013-04-01

    Inverting seismic waveforms for the finite fault source parameters is important for studying the physics of earthquake rupture processes. It is also significant to image seismogenic structures in urban areas. Here we analyze the finite-source process and test for the causative fault plane using the accelerograms recorded by the Taiwan Strong-Motion Instrumentation Program (TSMIP) stations. The point source parameters for the mainshock and aftershocks were first obtained by complete waveform moment tensor inversions. We then use the seismograms generated by the aftershocks as empirical Green's functions (EGFs) to retrieve the apparent source time functions (ASTFs) of near-field stations using projected Landweber deconvolution approach. The method for identifying the fault plane relies on the spatial patterns of the apparent source time function durations which depend on the angle between rupture direction and the take-off angle and azimuth of the ray. These derived duration patterns then are compared with the theoretical patterns, which are functions of the following parameters, including focal depth, epicentral distance, average crustal 1D velocity, fault plane attitude, and rupture direction on the fault plane. As a result, the ASTFs derived from EGFs can be used to infer the ruptured fault plane and the rupture direction. Finally we used part of the catalogs to study important seismogenic structures in the area near Chiayi, Taiwan, where a damaging earthquake has occurred about a century ago. The preliminary results show a strike-slip earthquake on 22 October 1999 (Mw 5.6) has ruptured unilaterally toward SSW on a sub-vertical fault. The procedure developed from this study can be applied to other strong motion waveforms recorded from other earthquakes to better understand their kinematic source parameters.

  5. Determination fo the Rydberg constant by direct frequency measurement

    SciTech Connect

    Nez, F.; Plimmer, M.D.; Bourzeix, S.

    1994-12-31

    We have performed a pure frequency measurement of the 2S-8S/D two photon transition in atomic hydrogen, without any interferometry. The hydrogen frequencies are compared with the difference of two optical standards, the methane stabilized He-Ne laser and the iodine stabilized He-Ne laser. In this way, an optical frequency of atomic hydrogen is directly linked for the first time to the cesium clock. We deduce a new value for the Rydberg constant with an uncertainty of 2.2 parts in 10{sup 11}. This value is currently the most precise available.

  6. A method to provide rapid in situ determination of tip radius in dynamic atomic force microscopy.

    PubMed

    Santos, Sergio; Guang, Li; Souier, Tewfik; Gadelrab, Karim; Chiesa, Matteo; Thomson, Neil H

    2012-04-01

    We provide a method to characterize the tip radius of an atomic force microscopy in situ by monitoring the dynamics of the cantilever in ambient conditions. The key concept is that the value of free amplitude for which transitions from the attractive to repulsive force regimes are observed, strongly depends on the curvature of the tip. In practice, the smaller the value of free amplitude required to observe a transition, the sharper the tip. This general behavior is remarkably independent of the properties of the sample and cantilever characteristics and shows the strong dependence of the transitions on the tip radius. The main advantage of this method is rapid in situ characterization. Rapid in situ characterization enables one to continuously monitor the tip size during experiments. Further, we show how to reproducibly shape the tip from a given initial size to any chosen larger size. This approach combined with the in situ tip size monitoring enables quantitative comparison of materials measurements between samples. These methods are set to allow quantitative data acquisition and make direct data comparison readily available in the community.

  7. Commercialized rapid immunoanalytical tests for determination of allergenic food proteins: an overview.

    PubMed

    Schubert-Ullrich, Patricia; Rudolf, Judith; Ansari, Parisa; Galler, Brigitte; Führer, Manuela; Molinelli, Alexandra; Baumgartner, Sabine

    2009-09-01

    Food allergies have become an important health issue especially in industrialized countries. Undeclared allergenic ingredients or the presence of "hidden" allergens because of contamination during the food production process pose great health risks to sensitised individuals. The EU directive for food labelling lists allergenic foods that have to be declared on food products by the manufacturers. The list includes gluten-containing cereals, crustaceans, eggs, fish, peanuts, soybeans, milk, various nuts (e.g. almond, hazelnut, and walnut, etc.), celery, mustard, sesame seeds, lupin, and molluscs. Reliable methods for detection and quantification of food allergens are needed that can be applied in a fast and easy-to-use manner, are portable, and need only limited technical equipment. This review focuses on the latest developments in food allergen analysis with special emphasis on fast immunoanalytical methods such as rapid enzyme-linked immunosorbent assays (ELISA), lateral-flow immunochromatographic assays (LFA) and dipstick tests. Emerging technologies such as immunochemical microarrays and biosensors are also discussed and their application to food allergen analysis is reviewed. Finally, a comprehensive overview of rapid immunochemical test kits that are currently available commercially is given in tabular form.

  8. A method to provide rapid in situ determination of tip radius in dynamic atomic force microscopy

    SciTech Connect

    Santos, Sergio; Guang Li; Souier, Tewfik; Gadelrab, Karim; Chiesa, Matteo; Thomson, Neil H.

    2012-04-15

    We provide a method to characterize the tip radius of an atomic force microscopy in situ by monitoring the dynamics of the cantilever in ambient conditions. The key concept is that the value of free amplitude for which transitions from the attractive to repulsive force regimes are observed, strongly depends on the curvature of the tip. In practice, the smaller the value of free amplitude required to observe a transition, the sharper the tip. This general behavior is remarkably independent of the properties of the sample and cantilever characteristics and shows the strong dependence of the transitions on the tip radius. The main advantage of this method is rapid in situ characterization. Rapid in situ characterization enables one to continuously monitor the tip size during experiments. Further, we show how to reproducibly shape the tip from a given initial size to any chosen larger size. This approach combined with the in situ tip size monitoring enables quantitative comparison of materials measurements between samples. These methods are set to allow quantitative data acquisition and make direct data comparison readily available in the community.

  9. Airflow-directed in situ electrospinning of a medical glue of cyanoacrylate for rapid hemostasis in liver resection.

    PubMed

    Jiang, Kai; Long, Yun-Ze; Chen, Zhao-Jun; Liu, Shu-Liang; Huang, Yuan-Yuan; Jiang, Xingyu; Huang, Zhi-Qiang

    2014-07-21

    Rapid hemostasis of solitary organs is still a big challenge in surgical procedures or after major trauma in both civilians and on the battlefield. Here, we report the first use of an airflow-directed in situ electrospinning method to precisely and homogeneously deposit a medical glue of n-octyl-2-cyanoacrylate (OCA) ultrathin fibers onto a wound surface to realize rapid hemostasis in dozens of seconds. In vivo and in vitro experiments on pig liver resection demonstrate that the self-assembled electrospun OCA membrane with high strength, good flexibility and integrity is very compact and no fluid seeping is observed even under a pressure of 147 mm Hg. A similar effect has been achieved in an in vivo experiment on pig lung resection. The results provide a very promising alternative for rapid hemostasis of solitary organs as well as other traumas, providing evidence that the postoperative drainage tube may not be always necessary for surgery in the near future.

  10. Optimizing direct amplification of forensic commercial kits for STR determination.

    PubMed

    Caputo, M; Bobillo, M C; Sala, A; Corach, D

    2017-04-01

    Direct DNA amplification in forensic genotyping reduces analytical time when large sample sets are being analyzed. The amplification success depends mainly upon two factors: on one hand, the PCR chemistry and, on the other, the type of solid substrate where the samples are deposited. We developed a workflow strategy aiming to optimize times and cost when starting from blood samples spotted onto diverse absorbent substrates. A set of 770 blood samples spotted onto Blood cards, Whatman(®) 3 MM paper, FTA™ Classic cards, and Whatman(®) Grade 1 was analyzed by a unified working strategy including a low-cost pre-treatment, a PCR amplification volume scale-down, and the use of the 3500 Genetic Analyzer as the analytical platform. Samples were analyzed using three different commercial multiplex STR direct amplification kits. The efficiency of the strategy was evidenced by a higher percentage of high-quality profiles obtained (over 94%), a reduced number of re-injections (average 3.2%), and a reduced amplification failure rate (lower than 5%). Average peak height ratio among different commercial kits was 0.91, and the intra-locus balance showed values ranging from 0.92 to 0.94. A comparison with previously reported results was performed demonstrating the efficiency of the proposed modifications. The protocol described herein showed high performance, producing optimal quality profiles, and being both time and cost effective.

  11. Rapid and accurate determination of the lignin content of lignocellulosic biomass by solid-state NMR

    PubMed Central

    Fu, Li; McCallum, Scott A.; Miao, Jianjun; Hart, Courtney; Tudryn, Gregory J.; Zhang, Fuming; Linhardt, Robert J.

    2014-01-01

    Biofuels and biomaterials, produced from lignocellulosic feedstock, require facile access to cellulose and hemicellulose to be competitive with petroleum processing and sugar-based fermentation. Physical-chemical barriers resulting from lignin complicates the hydrolysis biomass into fermentable sugars. Thus, the amount of lignin within a substrate is critical in determining biomass processing. The application of 13C cross-polarization, magic-angle spinning, and solid-state nuclear magnetic resonance for the direct quantification of lignin content in biomass is examined. Using a standard curve constructed from pristine lignin and cellulose, the lignin content of a biomass sample is accurately determined through direct measurement without chemical or enzymatic pre-treatment. PMID:25404762

  12. Direct spectrophotometric determination of iron in non-ferrous alloys.

    PubMed

    Nan, Z; Yuan-Xiang, G; Qing, G Y; Xu-Zhang, Y; Zhi-Ren, L

    1989-08-01

    Disodium 3-(2-pyridyl)-1,2,4-triazine-5,6-di(4'-phenylsulphonate) is used for determination of iron in metal analysis. High selectivity is achieved by using a ligand buffer and substoichiometric masking. Interference from 0.9 mg of Cu(II) can be completely eliminated by combined reduction and masking with ascorbic acid and thiosemicarbazide. Beer's law is obeyed over the range 0.4-1.6 mug/ml iron in the final solution, with a standard deviation of 0.02 mug/ml. The method has been successfully applied to determination of iron (without preseparation) in a number of non-ferrous metals and alloys, with a coefficient of variation of 1.2-5.0%.

  13. Direct determination of the underlying Lie algebra in nonlinear optics

    NASA Astrophysics Data System (ADS)

    Arnold, J. M.

    1991-01-01

    It is shown that the equations of resonant nonlinear optics can be studied entirely within the framework of an underlying Lie algebra, in which the 2x2 su(2) Hamiltonian and density matrices of the quantum mechanical description of the atomic system transform directly to the 2x2 sl(2,R) matrices of the Ablowitz-Kaup-Newell-Segur (AKNS) scheme, and the AKNS eigenvalue is introduced naturally as a free parameter. The Lie algebra sl(2,R) is also the symmetry algebra of transformations between equivalence classes of AKNS systems under SL(2,R) gauge transformations. The Lie algebra formalism condenses much algebraic manipulation, and provides a natural basis for the perturbation theory of "nearly integrable" nonlinear wave systems.

  14. Direct determination of neutrino mass parameters at future colliders

    SciTech Connect

    Kadastik, M.; Raidal, M.; Rebane, L.

    2008-06-01

    If the observed light neutrino masses are induced by their Yukawa couplings to singlet right-handed neutrinos, the natural smallness of those makes direct collider tests of the electroweak scale neutrino mass mechanisms difficult in the simplest models. In the triplet Higgs seesaw scenario the smallness of light neutrino masses may come from the smallness of B-L breaking parameters, allowing sizable Yukawa couplings even for a TeV scale triplet. We show that, in this scenario, measuring the branching fractions of doubly charged Higgs to different same-charged lepton flavors at CERN LHC and/or ILC experiments will allow one to measure the neutrino mass parameters that neutrino oscillation experiments are insensitive to, including the neutrino mass hierarchy, lightest neutrino mass, and Majorana phases.

  15. Rapid intraoperative determination of intact parathyroid hormone during surgery for primary hyperparathyroidism. Experience at our center.

    PubMed

    García-Santos, Esther Pilar; Martín-Fernández, Jesús; Gil-Rendo, Aurora; Menchén-Trujillo, Bruno; Martínez de Paz, Fernando; Manzanares-Campillo, M Carmen; Muñoz-Atienza, Virginia; Sánchez-García, Susana

    2014-01-01

    Primary hyperparathyroidism (PHPT) is due to a single adenoma in 85%-95% of cases, and is often cured after adenoma removal. Intraoperative rapid determination of intact parathyroid hormone (PTHio) may be a tool for monitoring the effectiveness of PHPT surgery. The main objective of our study was to evaluate PTHio determination and to establish whether its successful implementation contributed to achieve minimally invasive surgery (MIS) and major ambulatory surgery (MAS) in the treatment of PHPT. Retrospective study of a consecutive series of patients diagnosed and operated on for PHPT at the University General Hospital of Ciudad Real between January 2005 and January 2012. In the study period, 91 patients underwent surgery. 39 (42.9%) under general anesthesia, while 52 (57.1%) were candidates for regional anesthesia by cervical block. Seventy-six of all patients (83.5%) were amenable to MIS using a unilateral approach. Classical cervicotomy was performed in all other patients. PTHio determination was done in 75 patients, showing cure in the same surgery in 68 of them. MAS was performed in 70.3% (64) of patients. Determination of PTHio may allow for changing the surgical approach to PHPT at our department, allowing for performance of MIS on an outpatient basis in a significant proportion of patients with some cosmetic improvement, probably less pain, shorter hospital stay, and less potential complications than bilateral cervical exploration. Copyright © 2013 SEEN. Published by Elsevier Espana. All rights reserved.

  16. Rapid determination of hydrogen peroxide using peroxidase immobilized on Amberlite IRA-743 and minerals in honey.

    PubMed

    Franchini, Rômulo Augusto de Abreu; de Souza, Cabrini Ferraz; Colombara, Rosana; Matos, Maria Auxiliadora Costa; Matos, Renato Camargo

    2007-08-22

    Hydrogen peroxide and trace metals (K+, Ca2+, Na+, Mg2+, Mn2+, and Li+) were determined in 14 samples of Brazilian commercial honeys. The method for the determination of H2O2 is based on selective oxidation of H2O2 using an on-line tubular reactor containing peroxidase immobilized on Amberlite IRA-743 resin. Reactors presented high stability for at least 2 weeks under intense use. The results show a simple, accurate, selective, and readily applied method to the determination of H2O2 in honey. The trace metals were determined by capillary zone electrophoresis. Mean contents of 656, 69.1, 71.8, 36.0, 21.4, and 1.70 mg/kg were found, respectively, for K+, Ca2+, Na+, Mg2+, Mn2+, and Li+ in the analyzed honeys. The cations were identified by comparison of the relative migration times of their peaks with the Ba2+ migration time used as reference. The electrophoretic analysis was simple and rapid and did not require any other preparation of sample than dilution and filtration.

  17. Method of rapid determination of MHD equilibrium properties with the modified version of the SURFAS code

    SciTech Connect

    Lee, D.K.; Hirshman, S.P.; Okabayashi, M.; Reusch, M.F.; Sun, Y.C.

    1993-09-01

    Rapid determination of MHD eqilibrium properties of tokamak plasmas is carried out by means of an approximation method based on the use of database files. These are computed a priori from MHD equilibrium solutions obtained by performing reconstruction to match experimental measurements, which include motional Stark effect (MSE) data. The procedure carries out a single iteration of Newton`s method to determine the poloidal variation of the toroidal plasma current density in the equilibrium form j{sub {phi}} = {minus}2{pi}({mu}{sub 0}Rp{prime} + FF{prime}/R) by representing p{prime}({psi}) and F({psi})F{prime}({psi}) in series expansions of Chebyshev polynomials. The polynominal expansion coefficients are obtained through a least-squares data fitting process similar to that used in the equilibrium reconstruction. Knowing the current density j{phi} allows the determination of the internal q-profile from the MSE data. This important stability parameter is generally unavailable from a current filament model. Numerical results calculated in this approach are compared with those determined from an accurate solution of the Grad-Shafranov equation, subject to a similar set of magnetic and pressure measurement constraints.

  18. Two-Component Direct Fluorescent-Antibody Assay for Rapid Identification of Bacillus Anthracis

    DTIC Science & Technology

    2002-10-01

    Bacillus spp. (n=56) Five closely related Bacillus species—B. cereus (n=23), B. megaterium (n=11), B. subtilis (n=9), B. thuringiensis (n=12), and B...Rapid Identification of Bacillus anthracis Barun K. De,* Sandra L. Bragg,* Gary N. Sanden,* Kathy E. Wilson,* Lois A. Diem,* Chung K. Marston...antibody (DFA) assay, using fluorescein-labeled monoclonal antibodies specific to the Bacillus anthracis cell wall (CW-DFA) and capsule (CAP-DFA

  19. Direct observation of rapid discrete spectral dynamics in single colloidal CdSe-CdS core-shell quantum dots.

    PubMed

    Beyler, Andrew P; Marshall, Lisa F; Cui, Jian; Brokmann, Xavier; Bawendi, Moungi G

    2013-10-25

    We measure the anomalous spectral diffusion of single colloidal quantum dots over eight temporal decades simultaneously by combining single-molecule spectroscopy and photon-correlation Fourier spectroscopy. Our technique distinguishes between discrete and continuous dynamics and directly reveals that the quasicontinuous spectral diffusion observed using conventional spectroscopy is composed of rapid, discrete spectral jumps. Despite their multiple time scales, these dynamics can be captured by a single mechanism whose parameters vary widely between dots and over time in individual dots.

  20. Stratospheric thickness determined directly from satellite radiance measurements.

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.; Gelman, M. E.

    1972-01-01

    Discussion of the use of satellite radiance data for determining the thickness of deep stratospheric layers. Empirical regression equations are shown to provide better estimates of stratospheric thickness than do mean weighted temperatures obtained from the Planck equation. The best regression equations were found for thick layers emitting a substantial portion of the CO2-band infrared radiation measured by satellites. By adding the layer thickness to the observed height field for the lower boundary, it is possible to construct constant-pressure maps at very high altitudes.

  1. Stratospheric thickness determined directly from satellite radiance measurements.

    NASA Technical Reports Server (NTRS)

    Quiroz, R. S.; Gelman, M. E.

    1972-01-01

    Discussion of the use of satellite radiance data for determining the thickness of deep stratospheric layers. Empirical regression equations are shown to provide better estimates of stratospheric thickness than do mean weighted temperatures obtained from the Planck equation. The best regression equations were found for thick layers emitting a substantial portion of the CO2-band infrared radiation measured by satellites. By adding the layer thickness to the observed height field for the lower boundary, it is possible to construct constant-pressure maps at very high altitudes.

  2. Direct determination of the Boltzmann constant by an optical method.

    PubMed

    Daussy, C; Guinet, M; Amy-Klein, A; Djerroud, K; Hermier, Y; Briaudeau, S; Bordé, Ch J; Chardonnet, C

    2007-06-22

    We have recorded the Doppler profile of a well-isolated rovibrational line in the nu(2) band of (14)NH(3). Ammonia gas was placed in an absorption cell thermalized by a water-ice bath. By extrapolating to zero pressure, we have deduced the Doppler width which gives a first measurement of the Boltzmann constant k(B) by laser spectroscopy. A relative uncertainty of 2 x 10(-4) has been obtained. The present determination should be significantly improved in the near future and contribute to a new definition of the kelvin.

  3. Rapid and simultaneous determination of lycopene and beta-carotene contents in tomato juice by infrared spectroscopy.

    PubMed

    De Nardo, Thais; Shiroma-Kian, Cecilia; Halim, Yuwana; Francis, David; Rodriguez-Saona, Luis E

    2009-02-25

    The rapid quantification of lycopene and beta-carotene in tomato juices by attenuated total reflectance (ATR) infrared spectroscopy combined with multivariate analysis was evaluated. Two sample preparation methods were compared: a direct measurement of the tomato paste and an extraction method using hexane to isolate carotenoids. HPLC was used as the reference method. Cross-validated (leave-one-out) partial least-squares regression (PLSR) was used to create calibration models to predict these phytonutrient concentrations in blind test samples. The infrared spectra showed unique marker bands at 957 and 968 cm(-1) for lycopene and beta-carotene, respectively. Multivariate analysis of the infrared spectral data gave correlation coefficients (r values) of >0.9 between the ATR-IR predicted and HPLC reference values, and standard errors of cross-validation (SECV) of 0.5 and 0.04 mg/100 g of juice for lycopene and beta-carotene, respectively. ATR-IR could provide the tomato industry with a simple, rapid, and high-throughput technique for the determination of tomato quality.

  4. Genetic determinants of depression: Recent findings and future directions

    PubMed Central

    Dunn, Erin C.; Brown, Ruth C.; Dai, Yael; Rosand, Jonathan; Nugent, Nicole R.; Amstadter, Ananda B.; Smoller, Jordan W.

    2014-01-01

    Depression is one of the most prevalent, disabling, and costly mental health conditions in the United States. One promising avenue for preventing depression and informing its clinical treatment lies in uncovering both the genetic and environmental determinants of the disorder as well as their interaction (i.e. gene-environment intervention; GxE). The overarching goal of this review paper is to translate recent findings from studies of genetic association and GxE related to depression, particularly for readers without in-depth knowledge of genetics or genetic methods. This review is organized into three major sections. In the first section, we summarize what is currently known about the genetic determinants of depression, focusing on findings from genome-wide association studies (GWAS). In the second section, we review findings from studies of GxE, which seek to simultaneously examine the role of genes and exposure to specific environments or experiences in the etiology of depression. In the third section, we describe the challenges to genetic discovery in depression and promising strategies for making progress. PMID:25563565

  5. Direct determination of oil/saline partition coefficients.

    PubMed

    Ionescu, P; Eger, E I; Trudell, J

    1994-12-01

    Oil/saline partition coefficients for inhaled compounds often are defined by the ratio of the separately determined oil/gas and saline/gas partition coefficients. This approach assumes that the concurrent presence of oil with saline has no effect on the characteristics of either solvent. To test this assumption, we measured the oil/gas and saline/gas partition coefficients for CF3(CCIF)2CF3 and 1,2-dichloroperfluorocyclobutane (C4Cl2F6) separately and with the two phases mixed in a common container. We chose these compounds because they have radically different oil/gas and saline/gas partition coefficients and thus would provide a severe test of the assumption. For CF3(CCIF)2CF3, olive oil/saline partition coefficients were, respectively, 13,200 and 13,300 when measured separately and in mixed phases, and the octanol/saline partition coefficients were 19,200 and 18,100. Similarly, olive oil/saline partition coefficients for 1,2-dichloroperfluorocyclobutane were 3660 and 3500 when measured separately and in mixed phases, respectively, and the octanol/saline partition coefficients were 5140 and 4560. We conclude that differences between separate and mixed-phase determinations of ratios are small or nonexistent.

  6. Admission cell free DNA as a prognostic factor in burns: quantification by use of a direct rapid fluorometric technique.

    PubMed

    Shoham, Yaron; Krieger, Yuval; Perry, Zvi H; Shaked, Gad; Bogdanov-Berezovsky, Alexander; Silberstein, Eldad; Sagi, Amiram; Douvdevani, Amos

    2014-01-01

    Despite great advances in the treatment of burn patients, useful prognostic markers are sparse. During the past years there has been increasing interest in circulating plasma cell free DNA as a potential marker for tissue injury. We have developed a rapid direct fluorescent assay for cell free DNA quantification that allows obtaining accurate, fast, and inexpensive measurements. To use this technique for measuring plasma cell free DNA levels in burn patients and to further explore the use of cell free DNA as a potential marker of patient outcome in burns. Cell free DNA levels obtained from 14 burn victims within 6 hours of injury and 14 healthy controls were quantified by a direct rapid fluorometric assay. Patient admission cell free DNA levels were significantly elevated compared with that of controls (1797 ± 1523 ng/mL versus 374 ± 245 ng/mL, P = 0.004). There are statistically significant correlations between cell free DNA admission levels and burn degree (Spearman's correlation = 0.78, P = 0.001), total body surface area (Spearman's correlation = 0.61, P = 0.02), and total burn volume (Spearman's correlation = 0.64, P = 0.014). Admission cell free DNA levels can serve as a prognostic factor in burns and future routine use can be made possible by use of our direct rapid fluorometric assay.

  7. Rapid determination of catecholamines in urine samples by nonaqueous microchip electrophoresis with LIF detection.

    PubMed

    Hu, Hongmei; Li, Zhenhua; Zhang, Xiaoning; Xu, Chunxiu; Guo, Yuanming

    2013-10-01

    A method was developed for the rapid separation of catecholamines by nonaqueous microchip electrophoresis (NAMCE) with LIF detection, A homemade pump-free negative pressure sampling device was used for rapid bias-free sampling in NAMCE, the injection time was 0.5 s and the electrophoresis separation conditions were optimized. Under the optimized conditions, the samples were separated completely in <1 min. The average migration times of the epinephrine (E), dopamine (DA), and norepinephrine (NE) were 34.26, 43.81, and 50.07 s, with an RSD of 1.05, 1.26, and 0.89% (n = 7), respectively. The linearity of the method ranged from 0.0125 to 2.0 mg/L for E and 0.025~4.0 mg/L for DA and NE, with correlation coefficients ranging between 0.9978 and 0.9986. The detection limits of E, DA, and NE were 2.5, 5.0, and 5.0 μg/L, respectively. The recoveries of E, DA, and NE in spiked urine samples were between 86 and 103%, with RSDs of 4.5~6.8% (n = 5). The proposed NAMCE with LIF detection combined with a pump-free negative pressure sampling device is a simple, inexpensive, energy efficient, miniaturized system that can be successfully applied for the determination of catecholamines in urine samples. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Development of a rapid RP-HPLC method for the determination of clonazepam in human plasma.

    PubMed

    Bares, Isabelle Forfar; Pehourcq, Fabienne; Jarry, Christian

    2004-11-19

    A rapid and sensitive high-performance liquid chromatography method with UV detection was developed for the determination of clonazepam in human plasma using 3-methylclonazepam, as internal standard. A one-step extraction of both compounds was performed with a mixture of hexane/ethyl acetate (90:10, v/v). The HPLC analysis was carried out on a Nova Pak((R)) C(18) reversed-phase column with a mobile phase of acetonitrile-0.01 M sodium acetate adjusted to pH 7 with dilute acetic acid (40:60, v/v). A linear response was observed over the concentration range 5-100 ng/mL. Intra- and inter-day assay precision and accuracy fulfilled the international requirements. The lower limit of quantification was 5 ng/mL without interference of endogenous components. For analytical purpose, the stability of clonazepam in bidistilled water and plasma has been studied. A rapid degradation was noticed when clonazepam was stored in bidistilled water at the daylight following a first-order kinetic rate with a 87 min half life whereas no significant degradation was observed in plasma. This method was applied to measure plasma concentrations of clonazepam either in patients receiving therapeutic doses or in poisoning cases.

  9. wzi Gene Sequencing, a Rapid Method for Determination of Capsular Type for Klebsiella Strains

    PubMed Central

    Passet, Virginie; Haugaard, Anita Björk; Babosan, Anamaria; Kassis-Chikhani, Najiby; Struve, Carsten; Decré, Dominique

    2013-01-01

    Pathogens of the genus Klebsiella have been classified into distinct capsular (K) types for nearly a century. K typing of Klebsiella species still has important applications in epidemiology and clinical microbiology, but the serological method has strong practical limitations. Our objective was to evaluate the sequencing of wzi, a gene conserved in all capsular types of Klebsiella pneumoniae that codes for an outer membrane protein involved in capsule attachment to the cell surface, as a simple and rapid method for the prediction of K type. The sequencing of a 447-nucleotide region of wzi distinguished the K-type reference strains with only nine exceptions. A reference wzi sequence database was created by the inclusion of multiple strains representing K types associated with high virulence and multidrug resistance. A collection of 119 prospective clinical isolates of K. pneumoniae were then analyzed in parallel by wzi sequencing and classical K typing. Whereas K typing achieved typeability for 81% and discrimination for 94.4% of the isolates, these figures were 98.1% and 98.3%, respectively, for wzi sequencing. The prediction of K type once the wzi allele was known was 94%. wzi sequencing is a rapid and simple method for the determination of the K types of most K. pneumoniae clinical isolates. PMID:24088853

  10. Determining Key Model Parameters of Rapidly Intensifying Hurricane Guillermo (1997) Using the Ensemble Kalman Filter

    NASA Astrophysics Data System (ADS)

    Godinez, Humberto C.; Reisner, Jon M.; Fierro, Alexandre O.; Guimond, Stephen R.; Kao, Jim

    2012-11-01

    In this work we determine key model parameters for rapidly intensifying Hurricane Guillermo (1997) using the Ensemble Kalman Filter (EnKF). The approach is to utilize the EnKF as a tool to only estimate the parameter values of the model for a particular data set. The assimilation is performed using dual-Doppler radar observations obtained during the period of rapid intensification of Hurricane Guillermo. A unique aspect of Guillermo was that during the period of radar observations strong convective bursts, attributable to wind shear, formed primarily within the eastern semicircle of the eyewall. To reproduce this observed structure within a hurricane model, background wind shear of some magnitude must be specified; as well as turbulence and surface parameters appropriately specified so that the impact of the shear on the simulated hurricane vortex can be realized. To identify the complex nonlinear interactions induced by changes in these parameters, an ensemble of model simulations have been conducted in which individual members were formulated by sampling the parameters within a certain range via a Latin hypercube approach. The ensemble and the data, derived latent heat and horizontal winds from the dual-Doppler radar observations, are utilized in the EnKF to obtain varying estimates of the model parameters. The parameters are estimated at each time instance, and a final parameter value is obtained by computing the average over time. Individual simulations were conducted using the estimates, with the simulation using latent heat parameter estimates producing the lowest overall model forecast error.

  11. Lethal toxin is a critical determinant of rapid mortality in rodent models of Clostridium sordellii endometritis.

    PubMed

    Hao, Yibai; Senn, Tennille; Opp, Judy S; Young, Vincent B; Thiele, Teri; Srinivas, Geetha; Huang, Steven K; Aronoff, David M

    2010-04-01

    The toxigenic anaerobe Clostridium sordellii is an uncommon but highly lethal cause of human infection and toxic shock syndrome, yet few studies have addressed its pathogenetic mechanisms. To better characterize the microbial determinants of rapid death from infection both in vitro and in vivo studies were performed to compare a clinical strain of C. sordellii (DA-108), isolated from a patient who survived a disseminated infection unaccompanied by toxic shock syndrome, to a virulent reference strain (ATCC9714). Rodent models of endometrial and peritoneal infection with C. sordellii ATCC9714 were rapidly lethal, while infections with DA-108 were not. Extensive genetic and functional comparisons of virulence factor and toxin expression between these two bacterial strains yielded many similarities, with the noted exception that strain DA-108 lacked the tcsL gene, which encodes the large clostridial glucosyltransferase enzyme lethal toxin (TcsL). The targeted removal by immunoprecipitation of TcsL protected animals from death following injection of crude culture supernatants from strain ATCC9714. Injections of a monoclonal anti-TcsL IgG protected animals from death during C. sordellii ATCC9714 infection, suggesting that such an approach might improve the treatment of patients with C. sordellii-induced toxic shock syndrome. Copyright 2009 Elsevier Ltd. All rights reserved.

  12. Bacillus anthracis diagnostic detection and rapid antibiotic susceptibility determination using 'bioluminescent' reporter phage.

    PubMed

    Schofield, David A; Sharp, Natasha J; Vandamm, Joshua; Molineux, Ian J; Spreng, Krista A; Rajanna, Chythanya; Westwater, Caroline; Stewart, George C

    2013-11-01

    Genetically modified phages have the potential to detect pathogenic bacteria from clinical, environmental, or food-related sources. Herein we assess an engineered 'bioluminescent' reporter phage (Wß::luxAB) as a clinical diagnostic tool for Bacillus anthracis, the etiological agent of anthrax. Wß::luxAB is able to rapidly (within minutes) detect a panel of B. anthracis strains by transducing a bioluminescent phenotype. The reporter phage displays species specificity by its inability, or significantly reduced ability, to detect members of the closely related Bacillus cereus group and other common bacterial pathogens. Using spiked clinical specimens, Wß::luxAB detects B. anthracis within 5 h at clinically relevant concentrations, and provides antibiotic susceptibility information that mirrors the CLSI method, except that data are obtained at least 5-fold faster. Although anthrax is a treatable disease, a positive patient prognosis is dependent on timely diagnosis and appropriate therapy. Wß::luxAB rapidly detects B. anthracis and determines antibiotic efficacy, properties that will help patient outcome.

  13. Direct experimental determination of spectral densities of molecular complexes

    SciTech Connect

    Pachón, Leonardo A.; Brumer, Paul

    2014-11-07

    Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need to be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.

  14. Direct determination of surface albedos from satellite imagery

    NASA Technical Reports Server (NTRS)

    Mekler, Y.; Joseph, J. H.

    1983-01-01

    An empirical method to measure the spectral surface albedo of surfaces from Landsat imagery is presented and analyzed. The empiricism in the method is due only to the fact that three parameters of the solution must be determined for each spectral photograph of an image on the basis of independently known albedos at three points. The approach is otherwise based on exact solutions of the radiative transfer equation for upwelling intensity. Application of the method allows the routine construction of spectral albedo maps from satelite imagery, without requiring detailed knowledge of the atmospheric aerosol content, as long as the optical depth is less than 0.75, and of the calibration of the satellite sensor.

  15. Direct determination of surface albedos from satellite imagery

    NASA Technical Reports Server (NTRS)

    Mekler, Y.; Joseph, J. H.

    1983-01-01

    An empirical method to measure the spectral surface albedo of surfaces from Landsat imagery is presented and analyzed. The empiricism in the method is due only to the fact that three parameters of the solution must be determined for each spectral photograph of an image on the basis of independently known albedos at three points. The approach is otherwise based on exact solutions of the radiative transfer equation for upwelling intensity. Application of the method allows the routine construction of spectral albedo maps from satelite imagery, without requiring detailed knowledge of the atmospheric aerosol content, as long as the optical depth is less than 0.75, and of the calibration of the satellite sensor.

  16. Direct gravimetric determination of aerosol mass concentration in central antarctica.

    PubMed

    Annibaldi, Anna; Truzzi, Cristina; Illuminati, Silvia; Scarponi, Giuseppe

    2011-01-01

    In Antarctica, experimental difficulties due to extreme conditions have meant that aerosol mass has rarely been measured directly by gravimetry, and only in coastal areas where concentrations were in the range of 1-7 μg m(-3). The present work reports on a careful differential weighing methodology carried out for the first time on the plateau of central Antarctica (Dome C, East Antarctica). To solve problems of accurate aerosol mass measurements, a climatic room was used for conditioning and weighing filters. Measurements were carried out in long stages of several hours of readings with automatic recording of temperature/humidity and mass. This experimental scheme allowed us to sample from all the measurements (up to 2000) carried out before and after exposure, those which were recorded under the most stable humidity conditions and, even more importantly, as close to each other as possible. The automatic reading of the mass allowed us in any case to obtain hundreds of measurements from which to calculate average values with uncertainties sufficiently low to meet the requirements of the differential weighing procedure (±0.2 mg in filter weighing, between ±7% and ±16% both in aerosol mass and concentration measurements). The results show that the average summer aerosol mass concentration (aerodynamic size ≤10 μm) in central Antarctica is about 0.1 μg m(-3), i.e., about 1/10 of that of coastal Antarctic areas. The concentration increases by about 4-5 times at a site very close to the station.

  17. Photoneutron logging system for direct uranium ore-grade determination

    SciTech Connect

    Baker, M.P.; Marks, T.

    1982-06-01

    A prototype photoneutron probe for direct uranium assay in exploratory boreholes has been built and field tested. An approx. 10-Ci /sup 124/Sb gamma-ray source together with a beryllium converter is used to produce neutrons that diffuse into the surrounding formation and cause fissions in any /sup 235/U present. The fission neutrons that return to the probe are energy analyzed and counted by a high-pressure helium detector, thus indicating the concentration of uranium. The response of the probe was measured in concrete models at the US Department of Energy (Grand Junction, Colorado) calibration facility and found to be approx. 35 counts/s for an 1% U/sub 3/O/sub 8/ concentration in an 11.4-cm-diam water-filled borehole (4.5 in.). The response is linear up to a concentration of at least 0.25% by weight U/sub 3/O/sub 8/. Effects resulting from changes in formation density, porosity, and neutron absorber content were also quantified, as well as the tool response as a function of borehole diameter and fluid. A logging vehicle was outfitted, and the photoneutron-based logging system was field tested at an exploration site near Canon City, Colorado. Logging data obtained in several open holes at this site are presented and compared to core chemical analyses and results obtained in the same holes using other logging methods. In about 1 month of field testing, the photoneutron-based uranium exploration system has proved to be simple to use and very reliable. 22 figures, 12 tables.

  18. Direct spectrophotometric determination of bitterness in virgin olive oil without prior isolation by pH gradient.

    PubMed

    Mateos, Raquel; García-Ortíz Civantos, Concepción; Castro, Juan; Garcia-Mesa, José A

    2005-11-30

    Bitter taste, an organoleptic characteristic of virgin olive oil, has been related to phenolic compound composition. The usual method to assess this attribute is by a sensorial panel of tasters, while in the laboratory; methods based on physicochemical properties have been assayed as K225, the most widely used one. However, a direct determination of bitterness in virgin olive oil is useful for quality-control purposes. The proposed method is supported by the observable spectral change undergone by the compounds responsible for bitterness as pH varied. This measurement was carried out directly in the oil, without prior isolation of bitter analytes. The difference of absorbance between alkaline and neutral medium showed a highly significant correlation (r = 0.988, p < 0.0001) with the conventional parameter (K225). The method was rapid, required a small sample, allowed direct determination of bitterness in virgin olive oil, and could be easily automated.

  19. Statistical decision theory and the selection of rapid, goal-directed movements

    NASA Astrophysics Data System (ADS)

    Trommershauser, Julia; Maloney, Laurence T.; Landy, Michael S.

    2003-07-01

    We present two experiments that test the range of applicability of a movement planning model (MEGaMove) based on statistical decision theory. Subjects attempted to earn money by rapidly touching a green target region on a computer screen while avoiding nearby red penalty regions. In two experiments we varied the magnitudes of penalties, the degree of overlap of target and penalty regions, and the number of penalty regions. Overall, subjects acted so as to maximize gain in a wide variety of stimulus configurations, in good agreement with predictions of the model. 2003 Optical Society of America

  20. [The direction of rapid eye movements as an indication of hemispheric asymmetry during REM sleep. II].

    PubMed

    De Gennaro, L; Violani, C; Capogna, M

    1984-08-31

    The hypothesis of right hemisphere predominance in REM sleep and of an increase in left activity throughout the night have been tested by analyzing the distribution of vertical and of horizontal rapid eye movements (REMs) to the right and to the left during the first and the last REM periods in 5 right-handed subjects. Neither the expected superiority of REMs to the left nor variations along the REM periods were found. For vertical eye movements our data suggest a superiority of upward movements during REM. In waking some empirical evidences suggest a relationship between upward eye movements and right hemisphere functioning although to date no hemispheric model can explain it.

  1. Rapid method for determination of content of unsaturated hydrocarbons in naphtha cuts

    SciTech Connect

    Mozhaiko, V.N.; Seleznev, V.D.

    1988-03-01

    The method to determine total content of unsaturated hydrocarbons in naphtha cuts from reforming, cracking, and pyrolysis consisted of exhaustive catalytic hydrogenation of the unsaturated hydrocarbons, with detection of the hydrogen consumed in the hydrogenation reaction. The analyses were performed in a KhL-4 chromatography; the gas flow plan is shown. Preliminary experiments with saturated hydrocarbons (hexane, octane, decane) were performed. Naphthene experiments (methylcyclopentane, cyclohexane) showed no peak to indicate an increase in hydrogen concentration. No hydrogenation was observed in experiments with benzene and toluene. A comparison was made from analyses using the GOST 2070-82 and the rapid method as applied to IBP-180/sup 0/C cuts from reformer naphthas produced under varying conditions of severity.

  2. Rapid method for determining concentrations of Bayer 73 in water during lampricide treatments

    USGS Publications Warehouse

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

    1978-01-01

    Two simple, rapid, sensitive methods were developed for determining the concentration of the lampricide 2',5-dichloro-4'-nitrosalicylanilide (Bayer 73) in stream water. Bayer 73 was extracted from acidified water samples with chloroform and then hydrolyzed to 2-chloro-4-nitroaniline (CNA) with either acid or base. The CNA was diazotized with sodium nitrite, and an azo dye was formed with either N-( 1-naphthyl) ethylenediamine dihydrochloride (after acid hydrolysis) or 1-naphthol (after base hydrolysis). There was no interference from the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) in either method. Standard curves were prepared with untreated water to compensate for interfering substances that occurred naturally in some streams. The methods were sensitive to about 0.005 mg/L (ppm). Time required for analysis of a sample ranged from 25 min to 1 h.

  3. Rapid method for the determination of 226Ra in hydraulic fracturing wastewater samples

    SciTech Connect

    Maxwell, Sherrod L.; Culligan, Brian K.; Warren, Richard A.; McAlister, Daniel R.

    2016-03-24

    A new method that rapidly preconcentrates and measures 226Ra from hydraulic fracturing wastewater samples was developed in the Savannah River Environmental Laboratory. The method improves the quality of 226Ra measurements using gamma spectrometry by providing up to 100x preconcentration of 226Ra from this difficult sample matrix, which contains very high levels of calcium, barium, strontium, magnesium and sodium. The high chemical yield, typically 80-90%, facilitates a low detection limit, important for lower level samples, and indicates method ruggedness. Ba-133 tracer is used to determine chemical yield and correct for geometry-related counting issues. The 226Ra sample preparation takes < 2 hours.

  4. Rapid determination of ions by combined solid-phase extraction--diffuse reflectance spectroscopy

    NASA Technical Reports Server (NTRS)

    Fritz, James S.; Arena, Matteo P.; Steiner, Steven A.; Porter, Marc D.

    2003-01-01

    We introduce colorimetric solid-phase extraction (C-SPE) for the rapid determination of selected ions. This new technique links the exhaustive concentration of an analyte by SPE onto a membrane disk surface for quantitative measurement with a hand-held diffuse reflectance spectrometer. The concentration/measurement procedure is complete in approximately 1 min and can be performed almost anywhere. This method has been used to monitor iodine and iodide in spacecraft water in the 0.1-5.0 ppm range and silver(I) in the range of 5.0-1000 microg/l. Applications to the trace analysis of copper(II), nickel(II), iron(III) and chromium(VI) are described. Studies on the mechanism of extraction showed that impregnation of the disk with a surfactant as well as a complexing reagent results in uptake of additional water, which markedly improves the extraction efficiency.

  5. A rapid liquid chromatography method for determination of glufosinate residue in maize after derivatisation.

    PubMed

    Qian, Kun; He, Shun; Tang, Tao; Shi, Tianyu; Li, Jianqiang; Cao, Yongsong

    2011-07-15

    A rapid liquid chromatographic method for glufosinate analysis in maize samples after derivatisation has been developed. The labelled glufosinate was separated on a Kromasil C(18) column (250mm×4.6mm, 5μm) and UV detection was applied at 360nm. The optimisation of derivatisation conditions and the influence of different ion-pair reagents on the separation were discussed. The method linearity correlation coefficient was 0.9998 in concentrations ranging from 0.1 to 20mgL(-1). The level of quantification was set to 0.02mgkg(-1), and reached pesticide EU-MRLs for glufosinate in the maize samples. The proposed method was applied to the quantitative determination of glufosinate in samples with recoveries of 98.0-100.5% and RSDs of 2.13-4.13%. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers

    SciTech Connect

    Snyder, E.A.; Palmes, E.D.

    1985-06-01

    A rapid air titration method for determining SO/sub 2/ concentration in inhalation chambers has been validated using the pararosaniline-formaldehyde (PRA) method of West and Gaeke. This air-titration (iodate) method is an adaptation of iodometric methods using a starch indicator. Potassium iodate and an excess of potassium iodide are used in the reaction. Sampling is completed in ten minutes or less and concentration is calculated by use of a simple formula. Linear equations were derived over the range of concentrations from 0.5 to 100 ppm SO/sub 2/ for uncorrected iodate bubbler results, data corrected for tandem bubbler concentrations and data corrected for mean iodate bubbler efficiency. Linear correlation with the PRA method over this range was 0.999 for all three sets of data.

  7. A rapid method for determining the antimicrobial activity of novel natural molecules.

    PubMed

    Barreteau, H; Mandoukou, L; Adt, I; Gaillard, I; Courtois, B; Courtois, J

    2004-09-01

    Preservatives used in the Agro-food industries may be of natural origin or obtained chemically. Because of the increasing interest of consumers in food products that contain only natural ingredients, studies on preservative molecules of natural origin, such as organic acids or peptides, have been reported in the past several years. Such studies, which require numerous assays, may be limited by the large amount of molecules required. Microscale assays provide an opportunity for testing natural components available in low quantity. This study examined a rapid method that used microplates for the evaluation of anti-microbial substances. The method was validated using five foodborne pathogens. It required a low amount of product and was convenient for the determination of correlations between the bacterial growth inhibition and concentration of the antimicrobial substance.

  8. Technique of determining the parameters of rapid strengthening of an aluminum alloy during hot rolling

    NASA Astrophysics Data System (ADS)

    Loginov, Yu. N.; Golovnin, M. A.

    2017-03-01

    A new estimation procedure for estimating the influence of rapid strengthening on the strain resistance is proposed using a 6061 aluminum alloy (AD33, 1330) as an example. To implement this procedure, it is suggested to mathematically process the data of a system for monitoring a hot rolling mill. Attention is paid to the fact that the roll force in each pass increases with the rolling speed. On the basis of the determined strain resistance at a known roll force, it is possible to plot strain resistance as a function of the rolling speed. It has been revealed that the results of data processing are reliable for roll passes from 6 to 12, which is confirmed by the results of dispersion analysis. The obtained results have been compared with the published laboratory data, and they are found to agree with each other. The results obtained can be applied for everyday operation of rolling-mill shops.

  9. Rapid determination of ions by combined solid-phase extraction--diffuse reflectance spectroscopy

    NASA Technical Reports Server (NTRS)

    Fritz, James S.; Arena, Matteo P.; Steiner, Steven A.; Porter, Marc D.

    2003-01-01

    We introduce colorimetric solid-phase extraction (C-SPE) for the rapid determination of selected ions. This new technique links the exhaustive concentration of an analyte by SPE onto a membrane disk surface for quantitative measurement with a hand-held diffuse reflectance spectrometer. The concentration/measurement procedure is complete in approximately 1 min and can be performed almost anywhere. This method has been used to monitor iodine and iodide in spacecraft water in the 0.1-5.0 ppm range and silver(I) in the range of 5.0-1000 microg/l. Applications to the trace analysis of copper(II), nickel(II), iron(III) and chromium(VI) are described. Studies on the mechanism of extraction showed that impregnation of the disk with a surfactant as well as a complexing reagent results in uptake of additional water, which markedly improves the extraction efficiency.

  10. Sensitive and rapid determination of quinoline yellow in drinks using polyvinylpyrrolidone-modified electrode.

    PubMed

    Zhang, Shenghui; Shi, Zhen; Wang, Jinshou

    2015-04-15

    A novel electrochemical sensor using polyvinylpyrrolidone (PVP)-modified carbon paste electrode was developed for the sensitive and rapid determination of quinoline yellow. In 0.1M, pH 6.5 phosphate buffer, an irreversible oxidation wave at 0.97 V was observed for quinoline yellow. PVP exhibited strong accumulation ability to quinoline yellow, and consequently increased the oxidation peak current of quinoline yellow remarkably. The effects of pH value, amount of PVP, accumulation potential and time were studied on the oxidation signals of quinoline yellow. The linear range was from 5×10(-8) to 1×10(-6) M, and the limit of detection was evaluated to be 2.7×10(-8) M. It was used to detect quinoline yellow in different drink samples, and the results consisted with the values that obtained by high-performance liquid chromatography. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Visual Stimulus Speed Does Not Influence the Rapid Emergence of Direction Selectivity in Ferret Visual Cortex

    PubMed Central

    Ritter, Neil J.

    2017-01-01

    Sensory experience is necessary for the development of some receptive field properties of neurons in primary sensory cortical areas. However, it remains unclear whether the parameters of an individual animal's experience play an instructive role and influence the tuning parameters of cortical sensory neurons as selectivity emerges, or rather whether experience merely permits the completion of processes that are fully seeded at the onset of experience. Here we have examined whether the speed of visual stimuli that are presented to visually naive ferrets can influence the parameters of speed tuning and direction selectivity in cortical neurons. Visual experience is necessary for the development of direction selectivity in carnivores. If, during development, cortical neurons had the flexibility to choose from among different inputs with a range of spatial positions and temporal delays, then correlation-based plasticity mechanisms could instruct the precise spatiotemporal selectivity that underlies speed tuning and direction selectivity, and the parameters of an individual animal's experience would influence the tuning that emerges. Alternatively, the tuning parameters of these neurons may already be established at the onset of visual experience, and experience may merely permit the expression of this tuning. We found that providing different groups of animals with either slow (12.5 deg/s) or fast (50 deg/s) visual stimuli resulted in emergence of direction selectivity, but that speed tuning and direction selectivity were similar in the two groups. These results are more consistent with a permissive role for experience in the development of direction selectivity. SIGNIFICANCE STATEMENT The proper development of brain circuits and neural response properties depends on both nature (factors independent of experience) and nurture (factors dependent on experience). In this study, we examined whether the quality of visual experience of an individual animal influences the

  12. Visual Stimulus Speed Does Not Influence the Rapid Emergence of Direction Selectivity in Ferret Visual Cortex.

    PubMed

    Ritter, Neil J; Anderson, Nora M; Van Hooser, Stephen D

    2017-02-08

    Sensory experience is necessary for the development of some receptive field properties of neurons in primary sensory cortical areas. However, it remains unclear whether the parameters of an individual animal's experience play an instructive role and influence the tuning parameters of cortical sensory neurons as selectivity emerges, or rather whether experience merely permits the completion of processes that are fully seeded at the onset of experience. Here we have examined whether the speed of visual stimuli that are presented to visually naive ferrets can influence the parameters of speed tuning and direction selectivity in cortical neurons. Visual experience is necessary for the development of direction selectivity in carnivores. If, during development, cortical neurons had the flexibility to choose from among different inputs with a range of spatial positions and temporal delays, then correlation-based plasticity mechanisms could instruct the precise spatiotemporal selectivity that underlies speed tuning and direction selectivity, and the parameters of an individual animal's experience would influence the tuning that emerges. Alternatively, the tuning parameters of these neurons may already be established at the onset of visual experience, and experience may merely permit the expression of this tuning. We found that providing different groups of animals with either slow (12.5 deg/s) or fast (50 deg/s) visual stimuli resulted in emergence of direction selectivity, but that speed tuning and direction selectivity were similar in the two groups. These results are more consistent with a permissive role for experience in the development of direction selectivity.SIGNIFICANCE STATEMENT The proper development of brain circuits and neural response properties depends on both nature (factors independent of experience) and nurture (factors dependent on experience). In this study, we examined whether the quality of visual experience of an individual animal influences the

  13. A Rapid Blood Test To Determine the Active Status and Duration of Acute Viral Infection.

    PubMed

    Zheng, Tianyu; Finn, Caroline; Parrett, Christopher J; Dhume, Kunal; Hwang, Ji Hae; Sidhom, David; Strutt, Tara M; Li Sip, Yuen Yee; McKinstry, Karl K; Huo, Qun

    2017-09-20

    The ability to rapidly detect and diagnose acute viral infections is crucial for infectious disease control and management. Serology testing for the presence of virus-elicited antibodies in blood is one of the methods used commonly for clinical diagnosis of viral infections. However, standard serology-based tests have a significant limitation: they cannot easily distinguish active from past, historical infections. As a result, it is difficult to determine whether a patient is currently infected with a virus or not, and on an optimal course of action, based off of positive serology testing responses. Here, we report a nanoparticle-enabled blood test that can help overcome this major challenge. The new test is based on the analysis of virus-elicited immunoglobulin G (IgG) antibody present in the protein corona of a gold nanoparticle surface upon mixing the gold nanoparticles with blood sera. Studies conducted on mouse models of influenza A virus infection show that the test gives positive responses only in the presence of a recent acute viral infection, approximately between day 14 and day 21 following the infection, and becomes negative thereafter. When used together with the traditional serology testing, the nanoparticle test can determine clearly whether a positive serology response is due to a recent or historical viral infection. This new blood test can provide critical clinical information needed to optimize further treatment and/or to determine if further quarantining should be continued.

  14. A biofilm reactor-based approach for rapid on-line determination of biodegradable organic pollutants.

    PubMed

    Liu, Changyu; Zhao, Huijun; Zhong, Lijie; Liu, Chang; Jia, Jianbo; Xu, Xiaolong; Liu, Ling; Dong, Shaojun

    2012-04-15

    A new analytical approach utilizing a biofilm reactor (BFR) for rapid online determination of biochemical oxygen demand (BOD) was proposed and experimentally validated. The BFR was fabricated via a cultivation process using naturally occurring microbial seeds from locally collected wastewaters. The resultant BFR displays a remarkable rate of biodegradation towards a wide spectrum of organic substrates, capable of degrading over 20% of biodegradable organic substrates within 100 s. More importantly, the BFR exhibits a superior indiscriminative biodegradation feature, enabling a precise prediction of BOD values of total biodegradable organics based on experimentally determined BOD values from partial degradation processes without a need for on-going calibration. The proposed approach was systematically validated using a range of individual organic substrates, their mixtures, synthetic samples and wastewaters. Highly significant linear correlations between the BFR and the standard BOD(5) methods were obtained from diversified synthetic samples (r=0.988, p=0.000, n=45) and wastewaters (r=0.983, p=0.000, n=40). Near unity slope values of the principal axis of the correlation ellipse were obtained from all tested samples, suggesting both methods were essentially measuring the same BOD value. The reported method could be a useful online monitoring tool for determination of biodegradable organic pollutants. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Rapid shape determination of tissue transglutaminase using high-throughput computing.

    PubMed

    Lammie, Donna; Osborne, James; Aeschlimann, Daniel; Wess, Timothy J

    2007-09-01

    Small-angle X-ray scattering can be used to determine the molecular shape of macromolecules in solution which are otherwise refractory to conventional high-resolution studies. DAMMIN and GASBOR are applications that utilize ab initio methods to build models of proteins using simulated annealing; both DAMMIN and GASBOR have to be run numerous times on the same input data to generate the most likely protein shape. Condor is a specialized workload-management system for PC computation-intensive tasks. Using Condor, DAMMIN and GASBOR can be run a number of times simultaneously on the same input data, allowing the shape of proteins to be determined in a fraction of the time it would have taken to have run DAMMIN and GASBOR sequentially. The main advantage of this approach is that it allows quicker data processing; therefore, results are obtained promptly and without undue delay. Tissue transglutaminase is a multidomain enzyme that catalyses the formation of isopeptide bonds between polypeptide chains. This reaction requires the enzyme to undergo a series of conformational changes that are not well understood in order to allow the sequential interaction with the two substrate proteins and their subsequent release when cross-linked. Condor was applied to determine the solution shape of tissue transglutaminase in a rapid fashion. Eventually, the next step will be to move towards online analysis at synchrotron sources by developing a graphical user interface that will enable remote access, allowing users to submit jobs to Condor whilst at synchrotrons.

  16. Validation of Rapid Assessment Methods to Determine Streamflow Duration Classes in the Pacific Northwest, USA

    NASA Astrophysics Data System (ADS)

    Nadeau, Tracie-Lynn; Leibowitz, Scott G.; Wigington, Parker J.; Ebersole, Joseph L.; Fritz, Ken M.; Coulombe, Robert A.; Comeleo, Randy L.; Blocksom, Karen A.

    2015-07-01

    United States Supreme Court rulings have created uncertainty regarding U.S. Clean Water Act (CWA) authority over certain waters, and established new data and analytical requirements for determining CWA jurisdiction. Thus, rapid assessment methods are needed that can differentiate between ephemeral, intermittent, and perennial streams. We report on the validation of several methods. The first (Interim Method) was developed through best professional judgment (BPJ); an alternative (Revised Method) resulted from statistical analysis. We tested the Interim Method on 178 study reaches in Oregon, and constructed the Revised Method based on statistical analysis of the Oregon data. Next, we evaluated the regional applicability of the methods on 86 study reaches across a variety of hydrologic landscapes in Washington and Idaho. During the second phase, we also compared the Revised Method with a similar approach (Combined Method) based on combined field data from Oregon, Washington, and Idaho. We further compared field-based methods with a GIS-based approach (GIS Method) that used the National Hydrography Dataset and a synthetic stream network. Evaluations of all methods compared results with actual streamflow duration classes. The Revised Method correctly determined known streamflow duration 83.9 % of the time, versus 62.3 % accuracy of the Interim Method and 43.6 % accuracy for the GIS-based approach. The Combined Method did not significantly outperform the Revised Method. Analysis showed biological indicators most accurately discriminate streamflow duration classes. While BPJ established a testable hypothesis, this study illustrates the importance of quantitative field testing of rapid assessment methods. Results support a consistent method applicable across the Pacific Northwest.

  17. Direct determination of photoresist composition changes during UV exposure

    NASA Astrophysics Data System (ADS)

    Houle, Frances A.; Deline, Vaughn R.; Truong, Hoa; Sooriyakumaran, Ratnam

    2006-03-01

    Exposure of photoresists to ultraviolet light results in outgassing of species that have the potential to contaminate surrounding optical surfaces. Of particular concern are silicon-containing products which cannot be cleaned and permanently detune optical coatings. Collection and identification of those species and quantification of the amounts formed is a difficult analytical problem because of the number and variety of products. We describe a general methodology for determining acidolytic decomposition pathways and absolute elemental composition changes induced in photoresists during exposure. Two silicon-containing 193 nm resists that differ in the mode of attachment of trimethylsilyl to the polymer have been investigated. Elemental abundances are measured in post-apply baked, exposed and post-expose baked films by secondary ion mass spectrometry (SIMS), thus probing volatile product formation from all photochemical and thermal decomposition pathways. Complementary data on primary thermal acidolytic deprotection pathways during post-exposure bake are obtained by mass spectrometry, enabling SIMS elemental abundance changes to be interpreted. The results show that decomposition of both the polymer protecting groups through room temperature acidolysis and the photoacid generator by photolysis lead to volatile product formation during exposure. Silicon bound through oxygen is acid labile while silicon bound through carbon is not, resulting in very low to no silicon outgassing from the latter polymer. Sulfur-containing products formed from PAGs outgas in significant amounts from the photoresists investigated, supporting recent mass spectrometric observations of sulfur outgassing by R. Kunz and coworkers.

  18. Direct determination of liquid phase coexistence by Monte Carlo simulations.

    PubMed

    Zweistra, Henk J A; Besseling, N A M

    2006-07-01

    A formalism to determine coexistence points by means of Monte Carlo simulations is presented. The general idea of the method is to perform a simulation simultaneously in several unconnected boxes which can exchange particles. At equilibrium, most of the boxes will be occupied by a homogeneous phase. The compositions of these boxes yield coexisting points on the binodal. However, since the overall composition is fixed, at least one of the boxes will contain an interface. We show that this does not affect the results, provided that the interface has no net curvature. We coin the name "Helmholtz-ensemble method," because the method is related to the well-known Gibbs-ensemble method, but the volume of the boxes is constant. Since the box volumes are constant, we expect that this method will be particularly useful for lattice models. The accuracy of the Helmholtz-ensemble method is benchmarked against known coexistence curves of the three-dimensional Ising model with excellent results.

  19. Direct imprinting of porous substrates: a rapid and low-cost approach for patterning porous nanomaterials.

    PubMed

    Ryckman, Judson D; Liscidini, Marco; Sipe, J E; Weiss, S M

    2011-05-11

    This work describes a technique for one-step, direct patterning of porous nanomaterials, including insulators, semiconductors, and metals without the need for intermediate polymer processing or dry etching steps. Our process, which we call "direct imprinting of porous substrates (DIPS)", utilizes reusable stamps with micro- and nanoscale features that are applied directly to a porous material to selectively compress or crush the porous network. The stamp pattern is transferred to the porous material with high fidelity, vertical resolution below 5 nm, and lateral resolution below 100 nm. The process is performed in less than one minute at room temperature and at standard atmospheric pressure. We have demonstrated structures ranging from subwavelength optical components to microparticles and present exciting avenues for applications including surface-enhanced Raman spectroscopy (SERS), label-free biosensors, and drug delivery.

  20. Direct and rapid discrimination of aflatoxigenic strains based on fibre-optic room temperature phosphorescence detection.

    PubMed

    Rojas-Durán, T; Sánchez-Barragán, I; Costa-Fernández, J M; Sanz-Medel, A

    2007-04-01

    An innovative analytical methodology for the rapid identification of aflatoxin-producing moulds belonging to Aspergillus genus is presented here. The procedure is based on the measurement, using a fibre-optic luminometer, of the room temperature phosphorescence (RTP) emitted by aflatoxins produced by isolated aflatoxigenic strains, cultured in a special culture medium consisting of malt extract agar modified with beta-cyclodextrin and sodium deoxycholate for RTP induction. Unequivocal detection of the presence of aflatoxins in the culture medium is achieved within the first 36 h of incubation at 32 degrees C, owing to the selectivity and sensitivity of the RTP emission, as compared with the minimum of 72 h needed using a conventional microbiological method. In a first step, the capability of aflatoxin standard solutions to emit analytically useful RTP was evaluated. In this line all experimental conditions were optimised for in vitro induction of RTP from aflatoxins. In a second step, a simple analytical test was developed and it has been evaluated for the rapid identification of aflatoxigenic strains, as a discriminating assay from non-aflatoxigenic strains based on the measurement of experimental RTP emission observed. Confirmation of aflatoxin production on the studied culture plates was accomplished by means of an HPLC/fluorescence reference method.

  1. A direct and rapid leaf water extraction method for isotopic analysis.

    PubMed

    Peters, L I; Yakir, D

    2008-09-01

    Isotopic measurements of leaf water have provided insights into a range of ecophysiological and biogeochemical processes, but require an extraction step which often constitutes the major analytical bottleneck in large-scale studies. Current standard procedures for leaf water analysis are based on cryogenic vacuum or azeotrophic distillation, and are laborious, require sophisticated distillation lines and the use of toxic materials. We report a rapid technique based on centrifugation/filtration of leaf samples pulverised in their original sampling tubes, using a specifically adapted, simple apparatus. The leaf water extracts produced are suitable for isotopic analysis via pyrolysis gas chromatography isotope ratio mass spectrometry (PYR/GC/IRMS). The new method was validated against cryogenic vacuum distillation and showed an overall accuracy of +/-0.5 per thousand (nine grouped comparisons, n = 110) over a range of 21 per thousand. Effects due to the presence of soluble carbohydrates were near the detection limits for most samples analysed, and these effects could be corrected for (the extracted soluble organics could also be used for isotopic analysis). The extraction time for a routine eight-sample subset was reduced from 4 h (cryogenic distillation) to 45 min, limited only by the size of the centrifuge(s) used. This method provides a rapid, low-cost and reliable alternative to conventional vacuum and other distillation methods that can alleviate current restrictions on ecosystem- and global-scale studies that require high-throughput leaf water isotopic analysis. Copyright (c) 2008 John Wiley & Sons, Ltd.

  2. Directed ortho,ortho'-dimetalation of hydrobenzoin: Rapid access to hydrobenzoin derivatives useful for asymmetric synthesis.

    PubMed

    Cho, Inhee; Meimetis, Labros; Belding, Lee; Katz, Michael J; Dudding, Travis; Britton, Robert

    2011-01-01

    A variety of ortho,ortho'-disubstituted hydrobenzoin derivatives are readily accessible through a directed ortho,ortho'-dimetalation strategy in which the alcohol functions in hydrobenzoin are deprotonated by n-BuLi and the resulting lithium benzyl alkoxides serve as directed metalation groups. The optimization and scope of this reaction are discussed, and the utility of this process is demonstrated in the one-pot preparation of a number of chiral diols as well as a short synthesis of the chiral ligand Vivol.

  3. Rapid Quantitative Determination of Squalene in Shark Liver Oils by Raman and IR Spectroscopy.

    PubMed

    Hall, David W; Marshall, Susan N; Gordon, Keith C; Killeen, Daniel P

    2016-01-01

    Squalene is sourced predominantly from shark liver oils and to a lesser extent from plants such as olives. It is used for the production of surfactants, dyes, sunscreen, and cosmetics. The economic value of shark liver oil is directly related to the squalene content, which in turn is highly variable and species-dependent. Presented here is a validated gas chromatography-mass spectrometry analysis method for the quantitation of squalene in shark liver oils, with an accuracy of 99.0 %, precision of 0.23 % (standard deviation), and linearity of >0.999. The method has been used to measure the squalene concentration of 16 commercial shark liver oils. These reference squalene concentrations were related to infrared (IR) and Raman spectra of the same oils using partial least squares regression. The resultant models were suitable for the rapid quantitation of squalene in shark liver oils, with cross-validation r (2) values of >0.98 and root mean square errors of validation of ≤4.3 % w/w. Independent test set validation of these models found mean absolute deviations of the 4.9 and 1.0 % w/w for the IR and Raman models, respectively. Both techniques were more accurate than results obtained by an industrial refractive index analysis method, which is used for rapid, cheap quantitation of squalene in shark liver oils. In particular, the Raman partial least squares regression was suited to quantitative squalene analysis. The intense and highly characteristic Raman bands of squalene made quantitative analysis possible irrespective of the lipid matrix.

  4. Determining the relative sensitivity of benthic diatoms to atrazine using rapid toxicity testing: a novel method.

    PubMed

    Wood, Rebecca J; Mitrovic, Simon M; Kefford, Ben J

    2014-07-01

    Herbicides pose a potential threat to aquatic ecosystems, especially to phototrophic organisms such as benthic diatoms. Benthic diatoms may be a valuable indicator of the toxic impacts of herbicides in aquatic systems. However, this requires information on the herbicide sensitivity of a wide range of freshwater benthic diatom taxa. Unfortunately this information is only available for a limited number of species as current methods of developing new algae toxicity tests on individual taxa are lengthy and costly. To address this issue, we developed a new rapid toxicity test method to test natural benthic communities, from which the relative herbicide sensitivity of many individual taxa can be derived. This involved the collection of natural benthic communities from rocks in situ, which were placed directly into laboratory toxicity tests. Sensitivity data for several diatom genera in a 48 hour exposure toxicity test were produced, without the need for cultures or multiple site visits. After exposure to the highest treatment of atrazine (500 μg L(-1)) there were significant declines of healthy cells in the most sensitive genera: Gomphonema declined by 74%, Amphora by 62%, Cymbella by 54% and Ulnaria by 34% compared to control levels. In contrast, the genera, Eunotia, Achnanthidium and Navicula, had no statistically significant decline in cell health. This method can identify the diatom taxa most at risk of herbicide toxicity within the natural benthic diatom community. The rapid toxicity testing method presented is a simple and effective method to obtain sensitivity data for multiple taxa within a natural benthic diatom community in a relatively short period of time.

  5. 36 CFR 216.4 - Determining the need for formal public review of proposed Manual directives.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... determination: (1) Direct written or oral communication with those known to be interested in the proposal; (2... from current direction; (4) The extent of recent news media coverage on subjects related to...

  6. Synergistic action of thermoresponsive and hygroresponsive elements elicits rapid and directional response of a bilayer actuator.

    PubMed

    Zhang, Lidong; Desta, Israel; Naumov, Panče

    2016-05-01

    A bilayer actuator composed of thermoresponsive and thermo/hygroresponsive elements is developed, which undergoes fast, directional and autonomous curling with a speed of up to 0.7 m s(-1) and recovers its shape by hydration. In situ tensile testing of the thermal response of individual layers provided insights into the mechanism of actuation of thermo/hygromorphic bilayers.

  7. Morphological evidence and direct estimates of rapid melting beneath Totten Glacier Ice Shelf, East Antarctica

    NASA Astrophysics Data System (ADS)

    Greenbaum, Jamin; Schroeder, Dustin; Grima, Cyril; Habbal, Feras; Dow, Christine; Roberts, Jason; Gwyther, David; van Ommen, Tas; Siegert, Martin; Blankenship, Donald

    2017-04-01

    Totten Glacier drains at least 3.5 meters of eustatic sea level potential from marine-based ice in the Aurora Subglacial Basin (ASB) in East Antarctica, more than the combined total of all glaciers in West Antarctica. Totten Glacier has been the most rapidly thinning glacier in East Antarctica since satellite altimetry time series began and the nature of the thinning suggests that it is driven by enhanced basal melting due to ocean processes. While grounded ice thinning rates have been steady, recent work has shown that Totten's floating ice shelf may not have the same thinning behavior; as a result, it is critical to observe ice shelf and cavity boundary conditions and basal processes to understand this apparent discrepancy. Warm Modified Circumpolar Deep Water (MCDW), which has been linked to glacier retreat in West Antarctica, has been observed in summer and winter on the nearby Sabrina Coast continental shelf and deep depressions in the seafloor provide access for MCDW to reach the ice shelf cavity. Given its northern latitude, numerical ice sheet modeling indicates that Totten Glacier may be prone to retreat caused by hydrofracture in a warming climate, so it is important to understand how intruding MCDW is affecting thinning of Totten Glacier's ice shelf. Here we use post-processed, focused airborne radar observations of the Totten Glacier Ice Shelf to delineate multi-km wide basal channels and flat basal terraces associated with high basal reflectivity and specularity (flatness) anomalies and correspondingly large ice surface depressions that indicate active basal melting. Using a simple temperature-attenuation model, and basal roughness corrections, we present basal melt rates associated with the radar reflection and specularity anomalies and compare them to those derived from numerical ocean circulation modeling and an ice flow divergence calculation. Sub-ice shelf ocean circulation modeling and under-ice robotic observations of Pine Island Glacier Ice

  8. Rapid and direct quantitative detection of viable bifidobacteria in probiotic yogurt by combination of ethidium monoazide and real-time PCR using a molecular beacon approach.

    PubMed

    Meng, X C; Pang, R; Wang, C; Wang, L Q

    2010-11-01

    The potential of ethidium monoazide (EMA) real-time PCR method based on molecular beacon probe for rapid detection of viable bifidobacteria present in probiotic yogurt was evaluated in this work. A real-time PCR with molecular beacon assay was developed to determine genus Bifidobacterium quantitatively in order to increase the sensitivity and specificity of assay. EMA was used to treat probiotic yogurt prior to DNA extraction and real-time PCR detection to allow detection of only viable bacteria. The primer set of Bif-F/Bif-R which is genus-specific for Bifid. was designed. The specificity of the probes ensures that no signal is generated by non-target amplicons. Linear regression analysis demonstrated a good correlation (R² = 0·9948) between the EMA real-time PCR results and the plate counting, and real-time quantitative PCR results correlated adequately with enumeration of bifidobacteria by culture for commercial probiotic yogurt. This culture-independent approach is promising for the direct and rapid detection of viable bifidobacteria in commercial probiotic yogurt, and the detection can be carried out within 4 h. The detection limit for this method is about 10⁴ cell/ml. In conclusion, the direct quantitative EMA real-time PCR assay based on molecular beacon described in this research is a rapid and quantitative method.

  9. Direct determination of anabolic steroids in pig urine by a new SPME-GC-MS method.

    PubMed

    Zhang, Zhuomin; Duan, Hongbin; Zhang, Lan; Chen, Xi; Liu, Wei; Chen, Guonan

    2009-05-15

    A new solid phase microextraction (SPME) method coupled with gas chromatography-mass spectrometry (GC-MS) was developed for rapid determination of four anabolic steroids such as 3alpha-hydroxy-5alpha-androstane-17-one (HA), dihydrotestosterone (DHT), androstenedione (AD) and methyltestosterone (MT) in pig urine. SPME was used to extract the four anabolic compounds directly without derivatization. The optimum SPME sampling conditions were based on the home-made carbowax-divinylbenzene (CW-DVB) fiber coating during extraction at 40 degrees C for 50 min with 0.18 g/mL NaCl solution and 750 rpm stirring speed. The linear ranges of the proposed method were in the range of 8-640 pg/mL for HA and DHT and 16-510 pg/mL for AD and MT, respectively. The detection limits (S/N=3) were from 2 to 8 pg/mL for the four anabolic steroids. This SPME method provided very high enrichment factors for the four anabolic steroids, which were 1063-fold and 965-fold for HA and DHT at the concentration of 8 pg/mL and 207-fold and 451-fold for AD and MT at the concentration of 16 pg/mL, respectively. The recoveries ranged from 71.3 to 121%, and the RSDs were lower than 12.9%. The method was sensitive and reliable for determination of trace anabolic steroids in biological samples.

  10. The direct determination of trace arsenic and lead in gasoline by GFAAS

    SciTech Connect

    Moseley, R.Z.; Dulude, G.R.; Martin, S.E.

    1994-12-31

    Two potential problems in the determination of trace metals in gasoline are the high volatility of the analyte and the difficulty in sample handling. In this work, sample pretreatment with iodine was investigated for its ability to break down volatile organo-metallic complexes prior to the analytical step. Sample handling was also investigated using two distinct approaches; discrete droplet injection and aerosol deposition. The advantage of aerosol deposition for this application is that the sample is first converted to a mist and then dried continuously on a heated graphite surface. This facilitates sample handling as opposed to discrete sample introduction systems which suffer from both vapor pressure and surface tension problems. Furnace parameters were optimized for the two metals individually. From these results, a single method was generated which allowed the investigation of the simultaneous determination of arsenic and lead in gasoline. The AA spectrometer employed a dual galvanometer drive system to control the rapidly alternating selection of both source and wavelength. Using this device, up to four elements at a time can be measured in single furnace atomization. Direct analysis results will be compared to those obtained via the method of standard additions.

  11. Rapid, Direct Fluorescent-Antibody Method for the Detection of Salmonellae in Food and Feeds

    PubMed Central

    Insalata, N. F.; Mahnke, C. W.; Dunlap, W. G.

    1972-01-01

    An improved immunofluorescent-antibody (FA) method for the detection of salmonellae in foods and feeds was developed. This FA method combines a rapid cultural phase and a serological phase that allow for propagation of salmonellae in a minimum time, employing the industrial 8-hr work day as a guide. Two hundred fifty naturally contaminated human food and animal feed samples, representing 647 trials, were tested by the FA method. A total of 18 different food and feed samples was used. The method used by the Association of Official Analytical Chemists (AOAC) for the detection of salmonellae was the control method. The percent agreement when comparing the FA slide method to the AOAC method ranged from 87.1 to 95.3%, depending upon the conjugated antisera used in comparative studies. PMID:4564047

  12. A sphere-scanning radiometer for rapid directional measurements of sky and ground radiance

    NASA Astrophysics Data System (ADS)

    Deering, D. W.; Leone, P.

    1986-02-01

    The development of the Portable Apparatus for Rapid Acquisition of Bidirectional Observations of the Land and Atmosphere (PARABOLA) and a transportable platform system is examined. The PARABOLA is a three channel rotating head radiometer which samples in 15 deg instantaneous field-of-view sectors using a sensor head, data recording unit, and an internal power pack. The composition and operation of the sensor scan, data, and power systems are described. The calibration and laboratory testing of the instrument is discussed. The field testing of a tripod-and-boom mount apparatus, a boom-equipped instrument van, and a hot-air balloon mount, in order to select the proper support device for the PARABOLA sensor head is analyzed. The design and functions of the Transportable Pickup Mount System, which is a lightweight, collapsible boom apparatus, are described.

  13. Refueling while flying: foraging bats combust food rapidly and directly to power flight.

    PubMed

    Voigt, Christian C; Sörgel, Karin; Dechmann, Dina K N

    2010-10-01

    Flying vertebrates, such as bats, face exceptionally high energy costs during active flapping flight. Once airborne, energy turnover may exceed basal metabolic rate by a factor of up to 15. Here, we asked whether fuel that powers flight originates from exogenous (dietary nutrients), endogenous sources (mostly body lipids or glycogen), or a combination of both. Since most insectivorous bats fly continuously over relatively long time periods during foraging, we assumed that slowly mobilized glycogen, although suitable for supporting brief sallying flights, is inadequate to power aerial insect-hunting of bats. We hypothesized that the insect-feeding Noctilio albiventris rapidly mobilizes and combusts nutrients from insects it has just eaten instead of utilizing endogenous lipids. We used the stable carbon isotope ratio in the bats' exhaled breath (delta13C(brth)) to assess the origin of metabolized substrates of resting and flying N. albiventris in two nutritional conditions: fasted and recently fed. The breath of fasted resting bats was depleted in 13C in relation to their insect diet (delta13C(diet)), indicating the combustion of 13C depleted body lipids. In contrast to this, delta13C(brth) of bats that had recently fed closely matched delta13C(diet) in both resting and flying bats, suggesting a quick mobilization of ingested nutrients for metabolism. In contrast to most non-volant mammals, bats have evolved the ability to fuel their high energy expenditure rates through the rapid combustion of exogenous nutrients, enabling them to conquer the nocturnal niche of aerial insectivory.

  14. Development of a rapid multiplexed assay for the direct screening of antimicrobial residues in raw milk.

    PubMed

    McGrath, Terry F; McClintock, Laura; Dunn, John S; Husar, Gregory M; Lochhead, Michael J; Sarver, Ronald W; Klein, Frank E; Rice, Jennifer A; Campbell, Katrina; Elliott, Christopher T

    2015-06-01

    Antimicrobial residues found to be present in milk can have both health and economic impacts. For these reasons, the widespread routine testing of milk is required. Due to delays with sample handling and test scheduling, laboratory-based tests are not always suited for making decisions about raw material intake and product release, especially when samples require shipping to a central testing facility. Therefore, rapid on-site screening tests that can produce results within a matter of minutes are required to facilitate rapid intake and product release processes. Such tests must be simple for use by non-technical staff. There is increasing momentum towards the development and implementation of multiplexing tests that can detect a range of important antimicrobial residues simultaneously. A simple in situ multiplexed planar waveguide device that can simultaneously detect chloramphenicol, streptomycin and desfuroylceftiofur in raw dairy milk, without sample preparation, has been developed. Samples are simply mixed with antibody prior to an aliquot being passed through the detection cartridge for 5 min before reading on a field-deployable portable instrument. Multiplexed calibration curves were produced in both buffer and raw milk. Buffer curves, for chloramphenicol, streptomycin and desfuroylceftiofur, showed linear ranges (inhibitory concentration (IC)20-IC80) of 0.1-0.9, 3-129 and 12-26 ng/ml, whilst linear range in milk was 0.13-0.74, 11-376 and 2-12 ng/ml, respectively, thus meeting European legislated concentration requirements for both chloramphenicol and streptomycin, in milk, without the need for any sample preparation. Desfuroylceftiofur-contaminated samples require only simple sample dilution to bring positive samples within the range of quantification. Assay repeatability and reproducibility were lower than 12 coefficient of variation (%CV), whilst blank raw milk samples (n = 9) showed repeatability ranging between 4.2 and 8.1%CV when measured on all

  15. Evaluation of Direct Colorimetric MTT Assay for Rapid Detection of Rifampicin and Isoniazid Resistance in Mycobacterium tuberculosis.

    PubMed

    Hundie, Gadissa Bedada; Woldemeskel, Dawit; Gessesse, Amare

    2016-01-01

    With the spread of multidrug-resistant tuberculosis (MDR-TB) strains there is an increasing need for new accurate and cost-effective methods for a rapid diagnostic and drug susceptibility testing (DST), particularly in low-income countries where tuberculosis is hyperendemic. A colorimetric assay using 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MTT) has been suggested as a promising method for DST, especially to rifampicin. In this study, we standardized and evaluated the MTT assay for a rapid direct detection of rifampicin and isoniazid resistant Mycobacterium tuberculosis strains from sputum specimens using Lowenstein-Jensen (LJ) culture medium as a gold standard. The MTT assay sensitivity, specificity, positive and negative predictive values for rifampicin were 100%, 86%, 100%, 99%, respectively. For isoniazid, the MTT assay had a 100% sensitivity, specificity, positive and negative predictive values. Interestingly, the MTT assay gave interpretable results within two weeks for 94% of the samples compared to 7-14 weeks for LJ media. Overall, an excellent agreement was observed between MTT assay and LJ proportion method (Kappa, 0.91 for rifampicin and 1.00 for isoniazid). In conclusion, the direct colorimetric MTT assay simultaneously detects susceptible and resistant strains of M. tuberculosis within three weeks. It significantly shortens the time required to obtain a DST result and could be a reliable alternative method for rapid detection of drug-resistant TB strains in high-TB-burden resource-limited settings.

  16. Evaluation of Direct Colorimetric MTT Assay for Rapid Detection of Rifampicin and Isoniazid Resistance in Mycobacterium tuberculosis

    PubMed Central

    Woldemeskel, Dawit; Gessesse, Amare

    2016-01-01

    With the spread of multidrug-resistant tuberculosis (MDR-TB) strains there is an increasing need for new accurate and cost-effective methods for a rapid diagnostic and drug susceptibility testing (DST), particularly in low-income countries where tuberculosis is hyperendemic. A colorimetric assay using 3-(4, 5-dimethylthiazol-2-yl)-2, 5- diphenyltetrazolium bromide (MTT) has been suggested as a promising method for DST, especially to rifampicin. In this study, we standardized and evaluated the MTT assay for a rapid direct detection of rifampicin and isoniazid resistant Mycobacterium tuberculosis strains from sputum specimens using Lowenstein-Jensen (LJ) culture medium as a gold standard. The MTT assay sensitivity, specificity, positive and negative predictive values for rifampicin were 100%, 86%, 100%, 99%, respectively. For isoniazid, the MTT assay had a 100% sensitivity, specificity, positive and negative predictive values. Interestingly, the MTT assay gave interpretable results within two weeks for 94% of the samples compared to 7–14 weeks for LJ media. Overall, an excellent agreement was observed between MTT assay and LJ proportion method (Kappa, 0.91 for rifampicin and 1.00 for isoniazid). In conclusion, the direct colorimetric MTT assay simultaneously detects susceptible and resistant strains of M. tuberculosis within three weeks. It significantly shortens the time required to obtain a DST result and could be a reliable alternative method for rapid detection of drug-resistant TB strains in high-TB-burden resource-limited settings. PMID:28030634

  17. Development of a rapid PCR assay specific for Staphylococcus saprophyticus and application to direct detection from urine samples.

    PubMed

    Martineau, F; Picard, F J; Ménard, C; Roy, P H; Ouellette, M; Bergeron, M G

    2000-09-01

    Staphylococcus saprophyticus is one of the most frequently encountered microorganisms associated with acute urinary tract infections (UTIs) in young, sexually active female outpatients. Conventional identification methods based on biochemical characteristics can efficiently identify S. saprophyticus, but the rapidities of these methods need to be improved. Rapid and direct identification of this bacterium from urine samples would be useful to improve time required for the diagnosis of S. saprophyticus infections in the clinical microbiology laboratory. We have developed a PCR-based assay for the specific detection of S. saprophyticus. An arbitrarily primed PCR amplification product of 380 bp specific for S. saprophyticus was sequenced and used to design a set of S. saprophyticus-specific PCR amplification primers. The PCR assay was specific for S. saprophyticus when tested with DNA from 49 gram-positive and 31 gram-negative bacterial species. This assay was also able to amplify efficiently DNA from all 60 strains of S. saprophyticus from various origins tested. This assay was adapted for direct detection from urine samples. The sensitivity levels achieved with urine samples was 19 CFU with 30 cycles of amplification and 0.5 CFU with 40 cycles of amplification. This PCR assay for the specific detection of S. saprophyticus is simple and rapid (approximately 90 min, including the time for urine specimen preparation).

  18. Rapid spectrophotometric method for determining surface free energy of microalgal cells.

    PubMed

    Zhang, Xinru; Jiang, Zeyi; Li, Mengyin; Zhang, Xinxin; Wang, Ge; Chou, Aihui; Chen, Liang; Yan, Hai; Zuo, Yi Y

    2014-09-02

    Microalgae are one of the most promising renewable energy sources with environmental sustainability. The surface free energy of microalgal cells determines their biofouling and bioflocculation behavior and hence plays an important role in microalgae cultivation and harvesting. To date, the surface energetic properties of microalgal cells are still rarely studied. We developed a novel spectrophotometric method for directly determining the surface free energy of microalgal cells. The principles of this method are based on analyzing colloidal stability of microalgae suspensions. We have shown that this method can effectively differentiate the surface free energy of four microalgal strains, i.e., marine Chlorella sp., marine Nannochloris oculata, freshwater autotrophic Chlorella sp., and freshwater heterotrophic Chlorella sp. With advantages of high-throughput and simplicity, this new spectrophotometric method has the potential to evolve into a standard method for measuring the surface free energy of cells and abiotic particles.

  19. Rapid fabrication of cylindrical microlens array by shaped femtosecond laser direct writing

    NASA Astrophysics Data System (ADS)

    Luo, Zhi; Wang, Cong; Yin, Kai; Dong, Xinran; Chu, Dongkai; Duan, Ji'an

    2016-07-01

    In this study, a remarkable spatial shaping approach is proposed to transform Gaussian femtosecond laser into quasi-Bessel optical field with compressed central lobe and amplified side lobes of the spatial intensity profile. Based on this technique, inward bulge trench (IBT) structures are fabricated with high efficiency on the surface of PMMA by a single illumination step, whose cross-sectional profile is opposite to the results fabricated by Gaussian beam. And plano-convex cylindrical microlens array, which is consistent in size and shape throughout a large sample area, is formed through simply piecing together the IBT structures during fabricating process. Furthermore, numerical simulations of optical field in radial direction and on-axial direction are exploited to rationalize the dependence of the patterned microstructures on the spatial intensity distribution of femtosecond laser.

  20. A rapid, simple method for determining formaldehyde in drinking water using colorimetric-solid phase extraction.

    PubMed

    Hill, April A; Lipert, Robert J; Fritz, James S; Porter, Marc D

    2009-02-15

    Formaldehyde has been detected in drinking water supplies across the globe and on board NASA spacecraft. A rapid, simple, microgravity-compatible technique for measuring this contaminant in water supplies using colorimetric-solid phase extraction (C-SPE) is described. This method involves collecting a water sample into a syringe by passage through a cartridge that contains sodium hydroxide, to adjust pH, and Purpald, which is a well-established colorimetric reagent for aldehydes. After completing the reaction in the syringe by agitating for 2 min on a shaker at 400 rpm, the 1.0-mL alkaline sample is passed through an extraction disk that retains the purple product. The amount of concentrated product is then measured on-disk using diffuse reflectance spectroscopy, and compared to a calibration plot generated from Kubelka-Munk transformations of the reflectance data at 700 nm to determine the formaldehyde concentration. This method is capable of determining formaldehyde concentrations from 0.08 to 20 ppm with a total work-up time of less than 3 min using only 1-mL samples.

  1. An improved method for the rapid determination of (90)Sr in cow's milk.

    PubMed

    Guérin, Nicolas; Riopel, Remi; Rao, Ray; Kramer-Tremblay, Sheila; Dai, Xiongxin

    2017-09-01

    An improved method was developed to rapidly determine strontium-90 ((90)Sr) in cow's milk samples in the event of a nuclear emergency. To perform this method, no heating or ashing steps were needed and all of the material used was disposable. Stable Sr tracer was added to each 40 mL milk sample. Hydrochloric acid (HCl) and trichloroacetic acid (TCA) were added to the sample to flocculate the suspended fat and proteins in the milk. The sample was centrifuged and the strontium in the supernatant was precipitated with carbonate. The resulting precipitate was dissolved in 8 M HNO3 and the solution was passed through a Sr resin to remove potential interferents. Strontium was eluted from the resin using a small volume of water. Strontium-90 was measured by liquid-scintillation counting (LSC) and the tracer by inductively coupled plasma mass spectrometry (ICP-MS). The figures of merit of the method were determined and the method was validated using spiked samples. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  2. Rapid determination of octanol-water partition coefficient using vortex-assisted liquid-liquid microextraction.

    PubMed

    Román, Iván P; Mastromichali, Anna; Tyrovola, Konstantina; Canals, Antonio; Psillakis, Elefteria

    2014-02-21

    Vortex-assisted liquid-liquid microextraction (VALLME) coupled with high-performance liquid chromatography (HPLC) is proposed here for the rapid determination of octanol-water partitioning coefficients (Kow). VALLME uses vortex agitation, a mild emulsification procedure, to disperse microvolumes of octanol in the aqueous phase thus increasing the interfacial contact area and ensuring faster partitioning rates. With VALLME, 2min were enough to achieve equilibrium conditions between the octanolic and aqueous phases. Upon equilibration, separation was achieved using centrifugation and the octanolic microdrop was collected and analyzed in a HPLC system. Six model compounds with logKow values ranging between ∼0.5 and 3.5 were used during the present investigations. The proposed method produced logKow values that were consistent with previously published values and the recorded uncertainty was well within the acceptable log unit range. Overall, the key features of the proposed Kow determination procedure comprised speed, reliability, simplicity, low cost and minimal solvent consumption. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Evaluation of a rapid physical-chemical method for the determination of extant soluble COD.

    PubMed

    Hu, Zhiqiang; Chandran, Kartik; Smets, Barth F; Grasso, Domenico

    2002-02-01

    Characterization of total chemical oxygen demand (COD) in wastewater is critical for accurate modeling of constituent biotransformation steps. We evaluated the accuracy and precision of a commonly used soluble COD determination technique (coagulation using ZnSO4 at pH 10.5) in relation to three other physical-chemical separation techniques: destabilization with a non-hydrolyzing trivalent cation (LaCl3), sequential filtration, and ultracentrifugation. Samples of deionized water and domestic wastewater were spiked with aliquots of synthetic soluble COD and recoveries using the different separation methods were compared. Although mechanisms of coagulation using LaCl3 and ZnSO4 are different, the mean COD recoveries using these methods were in close agreement. Further, sorption of soluble COD onto zinc hydroxide precipitate flocs appeared to be negligible. The two coagulation methods yielded statistically different (p = 0.05) soluble COD values when applied to nine independent wastewater samples (obtained on nine different days). but the difference was less than 10%. The COD quantified by the coagulation techniques corresponded most closely with the < 1,000 Da molecular weight fraction defined as "truly soluble COD". Centrifugation of wastewater samples amended with mercuric chloride (HgCl2) at 10 mg/L overestimated the soluble COD concentration. Our results confirm that coagulation using either ZnSO4 or LaCI3 is appropriate for the rapid determination of soluble COD fraction in wastewater matrices.

  4. A rapid and sensitive alcohol oxidase/catalase conductometric biosensor for alcohol determination.

    PubMed

    Hnaien, M; Lagarde, F; Jaffrezic-Renault, N

    2010-04-15

    A new conductometric biosensor has been developed for the determination of short chain primary aliphatic alcohols. The biosensor assembly was prepared through immobilization of alcohol oxidase from Hansenula sp. and bovine liver catalase in a photoreticulated poly(vinyl alcohol) membrane at the surface of interdigitated microelectrodes. The local conductivity increased rapidly after alcohol addition, reaching steady-state within 10 min. The sensitivity was maximal for methanol (0.394+/-0.004 microS microM(-1), n=5) and decreased by increasing the alcohol chain length. The response was linear up to 75 microM for methanol, 70 microM for ethanol and 65 microM for 1-propanol and limits of detection were 0.5 microM, 1 microM and 3 microM, respectively (S/N=3). No significant loss of the enzyme activities was observed after 3 months of storage at 4 degrees C in a 20mM phosphate buffer solution pH 7.2 (two or three measurements per week). After 4 months, 95% of the initial signal still remained. The biosensor response to ethanol was not significantly affected by acetic, lactic, ascorbic, malic, oxalic, citric, tartaric acids or glucose. The bi-enzymatic sensor was successfully applied to the determination of ethanol in different alcoholic beverages. (c) 2009 Elsevier B.V. All rights reserved.

  5. Ultrasensitive electrochemical immunoassay based on graphene oxide-Ag composites for rapid determination of clenbuterol.

    PubMed

    Bai, Jing; Lai, Yanjun; Jiang, Dawei; Zeng, Yanbo; Xian, Yuezhong; Xiao, Fei; Zhang, Ningdan; Hou, Jie; Jin, Litong

    2012-09-21

    We report the development of an ultrasensitive amperometric biosensor based on Ag nanoparticles-decorated graphene oxide nanosheets (GO) (Ag-GO) for the rapid detection of clenbuterol (CLB). The morphology and structure of the Ag-GO labeled CLB (Ag-GO-CLB) were characterized by transmission electron microscope (TEM), atomic force microscope (AFM), and ultraviolet-visible spectroscope (UV-vis). The immunosensor was prepared by covalently immobilizing capture antibodies on a multi-walled carbon nanotubes-modified glassy carbon electrode. Through competitive immunoreactions, the Ag-GO-CLB nanocomposites were captured on the immunosensor and the silver was measured by positive differential pulse voltammetry (DPV) in KCl solution for the detection of antigen. The experimental results show a linear response over the range from 0.01 to 10.0 ng mL(-1) with a lower detection limit of 6.8 pg mL(-1) (signal-to-noise ratio of 3). The Ag-GO based immunosensor offers a simple and convenient route for metal-immunoassay labels, which can avoid the complicated and time-consuming dissolving of metal component for ultrasensitive determination. Moreover, the electrochemical immunoassay shows acceptable specificity and stability and is suitable for the determination of CLB in real samples.

  6. Automated and Rapid Determinations of Earthquake Source Parameters in Indonesia: Comparisons with Global CMT Solutions

    NASA Astrophysics Data System (ADS)

    Nakano, M.; Yamashina, T.; Kumagai, H.; Inoue, H.; S.; F.

    2008-12-01

    Rapid determinations of the earthquake source parameters are important for early disaster response and tsunami warning issue. After the devastation of the 2004 great Sumatra-Andaman earthquake, a nationwide broadband seismograph network in Indonesia has been developed by international cooperations among Meteorological and Geophysical Agency of Indonesia (BMG), GeoForschungsZentrum Potsdam, Germany (GFZ), the China Earthquake Administration (CEA), and the National Research Institute for Earth Science and Disaster Prevention, Japan (NIED). This seismic network is intended to improve the capabilities for monitoring seismic activity and tsunami generation in Indonesia, and is a part of the Indonesia Tsunami Early Warning System (InaTEWS). We developed an automated system for rapid determinations of the earthquake source parameters called SWIFT (Source parameter determinations based on Waveform Inversion of Fourier Transformed seismograms) using data from the seismic network in Indonesia. This paper describes the SWIFT system and its performance. We also compare the obtained source parameters with those obtained by the Global Centroid Moment Tensor (GCMT) project (http://www.globalcmt.org/). The SWIFT system is based on the waveform inversion method of Nakano et al. (2008, GJI, 173, 1000-1011). In this method, waveform inversion is carried out in the frequency domain to rapidly and routinely estimate both the focal mechanism and moment function. A pure double-couple focal mechanism from a point source is assumed in order to stabilize the inversion using data from a small number of seismic stations. The fault and slip orientation angles are estimated by a grid search with respect to the dip, strike, and rake angles. The source centroid location is determined by a spatial grid search, in which we adopt adaptive grid spacings for an efficient search. The moment function is reconstructed from its bandpassed form obtained from the inversion. This system is triggered by

  7. Development of Rapid Pipe Moulding Process for Carbon Fiber Reinforced Thermoplastics by Direct Resistance Heating

    NASA Astrophysics Data System (ADS)

    Tanaka, Kazuto; Harada, Ryuki; Uemura, Toshiki; Katayama, Tsutao; Kuwahara, Hideyuki

    To deal with environmental issues, the gasoline mileage of passenger cars can be improved by reduction of the car weight. The use of car components made of Carbon Fiber Reinforced Plastics (CFRP) is increasing because of its superior mechanical properties and relatively low density. Many vehicle structural parts are pipe-shaped, such as suspension arms, torsion beams, door guard bars and impact beams. A reduction of the car weight is expected by using CFRP for these parts. Especially, when considering the recyclability and ease of production, Carbon Fiber Reinforced Thermoplastics are a prime candidate. On the other hand, the moulding process of CFRTP pipes for mass production has not been well established yet. For this pipe moulding process an induction heating method has been investigated already, however, this method requires a complicated coil system. To reduce the production cost, another system without such complicated equipment is to be developed. In this study, the pipe moulding process of CFRTP using direct resistance heating was developed. This heating method heats up the mould by Joule heating using skin effect of high-frequency current. The direct resistance heating method is desirable from a cost perspective, because this method can heat the mould directly without using any coils. Formerly developed Non-woven Stitched Multi-axial Cloth (NSMC) was used as semi-product material. NSMC is very suitable for the lamination process due to the fact that non-crimp stitched carbon fiber of [0°/+45°/90°/-45°] and polyamide 6 non-woven fabric are stitched to one sheet, resulting in a short production cycle time. The use of the pipe moulding process with the direct resistance heating method in combination with the NSMC, has resulted in the successful moulding of a CFRTP pipe of 300 mm in length, 40 mm in diameter and 2 mm in thickness.

  8. Rapid mortality of pest arthropods by direct exposure to a dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Bures, Brian Lee

    The spread of arthropods due to trade of agricultural commodities and travel of humans is a significant problem in many countries. Limiting the movement of pest species is commonly achieved by the use of chemical pesticides at quarantine facilities. One potential alternative to chemical pesticides is direct exposure of contaminated commodities to ambient pressure electrical discharges. The arthropods are directly exposed to a 5.0 cm helium discharge with power densities on the order of 60 mW/cm3. Direct measurement of chemical species and ambient gas temperature shows the DBD treatment remains effective when the chemically reactive species are suppressed by helium, and when the ambient gas temperature of the discharge is below 40°C. In addition to gas temperature measurements and chemical species identification, the electron temperature and electron density were measured using the neutral bremsstrahlung continuum technique. This study is the first successful implementation of the neutral bremsstrahlung continuum emission diagnostic to a barrier discharge. The primary advantages of the diagnostic for barrier discharges are the measurement is passive and the spatial resolution is only limited by the collimation of the light and the sensitivity of the detector. Although the electron temperature (1.0--1.5 eV) and electron density (˜108 cm-3) are modest, non-chemical dielectric barrier discharge (DBD) treatment of arthropods has proven effective in significantly reducing the population of some arthropods including human body lice, green peach aphids, and western flower thrips. However, the treatment was not universally effective on all arthropod species. German cockroaches and citrus mealy bugs showed substantial resistance to the treatment. The study has shown the treatment does not always induce instant mortality: however, the mortality increases over a 24 hr-period after treatment. Based upon visual observation and the time after treatment to reach maximum

  9. The Impact of Direct Cardiac Output Determination On Using A Widely Available Direct Continuous Oxygen Consumption Measuring Device On The Hemodynamic Assessment of Aortic Valve

    PubMed Central

    Fanari, Zaher; Grove, Matthew; Rajamanickam, Anitha; Hammami, Sumaya; Walls, Cassie; Kolm, Paul; Saltzberg, Mitchell; Weintraub, William S.; Doorey, Andrew J.

    2016-01-01

    Background Accurate assessment of cardiac output (CO) is essential for the hemodynamic assessment of aortic valve area (AVA). Estimation of oxygen consumption (VO2) and Thermodilution (TD) is employed in many cardiac catheterization laboratories (CCL) given the historically cumbersome nature of direct continuous VO2 measurement, the “gold standard” for this technique. A portable facemask device simplifies the direct continuous measurement of VO2, allowing for relatively rapid and continuous assessment of CO and AVA. Methods and Materials Seventeen consecutive patients undergoing right heart catheterization had simultaneous determination of CO by both direct continuous and assumed VO2 and TD. Assessments were only made when a plateau of VO2 had occurred. All measurements of direct continuous and assumed VO2, as well as, TD CO were obtained in triplicate. Results Direct continuous VO2 CO and assumed VO2 CO correlated poorly (R= 0.57; ICC =0.59). Direct continuous VO2 CO and TD CO also correlated poorly (R= 0.51; ICC=0.60). Similarly AVA derived from direct continuous VO2 correlated poorly with those of assumed VO2 (R= 0.68; ICC=0.55) and TD (R=0.66, ICC=0.60). Repeated direct continuous VO2 CO and AVA measurements were extremely correlated and reproducible [(R=0.93; ICC=0.96) and (R=0.99; ICC>0.99) respectively], suggesting that this was the most reliable measurement of CO. Conclusions CO calculated from direct continuous VO2 measurement varies substantially from both assumed VO2 and TD based CO, which are widely used in most CCL. These differences may significantly impact the CO and AVA measurements. Furthermore, continuous, rather than average, measurement of VO2 appears to give highly reproducible results. PMID:27904163

  10. Determination of forces on a split palatal screw after rapid maxillary expansion.

    PubMed

    García, Valentin Javier; López-Cancelos, Rubén; Riveiro, Antonio; Comesaña, Rafael; Ustrell I Torrent, Josep Maria; Kasem, Khaled; Badaoui, Aida; Manzanares-Céspedes, Mª Cristina; Carvalho-Lobato, Patricia

    2017-04-12

    Aim of this study was to develop a finite element model of the forces that patients with rapid maxillary expansion bear and to validate it by a mechanical test. Computer-aided design models of the metallic screw and polymeric splint were modelled and discretized. Two forces were generated and considered independently: F1 at the temporary molar (2.5 N) and F2 at the permanent molar (2.5 N). The results of the finite element analysis were used to define the strain values which the anterior and posterior arms of the rapid maxillary expansion appliance bore as a linear function of F1-F2 by calculating the strain-force coefficient δ ij . Two strain gauge rosettes were attached to an appliance which was placed in an XY motorized stage to reproduce the same forces used in the finite element analysis. Once the system was validated, the matrix was inverted to determine forces F1 and F2 that a group of 40 patients underwent (median age 8.33 years, standard deviation 1.86 years) for 75 days, using their strain values. The parents of the patients activated a quarter turn (0.20 mm) twice a day until 50% transversal overcorrection was achieved. Finite element analysis showed that the effects of the forces on stress at the location of the arms were notably different. There was a satisfactory correlation between finite element analysis predictions and in vitro values. Dissipation of F1 and F2 in patients was predicted to be 62.5 and 80%, respectively, after 75 days of retention. These results back the finite element analysis model for force prediction.

  11. Rapid determination of catecholamines in urine samples by nonaqueous microchip electrophoresis with LIF detection.

    PubMed

    Hu, Hongmei; Li, Zhenhua; Zhang, Xiaoning; Xu, Chunxiu; Guo, Yuanming

    2013-08-14

    A method was developed for the rapid separation of catecholamines by nonaqueous microchip electrophoresis with LIF detection, A homemade pump-free negative pressure sampling device was used for rapid bias-free sampling in nonaqueous microchip electrophoresis, the injection time was 0.5 s and the electrophoresis separation conditions were optimized. Under the optimized conditions, the samples were separated completely in less than 1 min. The average migration times of the epinephrine, dopamine, and norepinephrine were 34.26, 43.81, and 50.07 s, with a relative standard deviation of 1.05, 1.26 and 0.89% (n = 7), respectively. The linearity of the method ranged from 0.0125 to 2.0 mg/L for epinephrine and 0.025∼4.0 mg/L for dopamine, and norepinephrine, with correlation coefficients ranging between 0.9978 and 0.9986. The detection limits of epinephrine, dopamine, and norepinephrine were 2.5, 5.0 and 5.0 μg/L, respectively. The recoveries of epinephrine, dopamine, and norepinephrine in spiked urine samples were between 86 and 103%, with relative standard deviations of 4.5∼6.8% (n = 5). The proposed nonaqueous microchip electrophoresis with laser induced fluorescence detection system combined with a pump-free negative pressure sampling device was a simple, inexpensive, energy efficient, miniaturized system that can be successfully applied for the determination of catecholamines in urine samples. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  12. All-in-one nanowire-decorated multifunctional membrane for rapid cell lysis and direct DNA isolation.

    PubMed

    So, Hongyun; Lee, Kunwoo; Murthy, Niren; Pisano, Albert P

    2014-12-10

    This paper describes a handheld device that uses an all-in-one membrane for continuous mechanical cell lysis and rapid DNA isolation without the assistance of power sources, lysis reagents, and routine centrifugation. This nanowire-decorated multifunctional membrane was fabricated to isolate DNA by selective adsorption to silica surface immediately after disruption of nucleus membranes by ultrasharp tips of nanowires for a rapid cell lysis, and it can be directly assembled with commercial syringe filter holders. The membrane was fabricated by photoelectrochemical etching to create microchannel arrays followed by hydrothermal synthesis of nanowires and deposition of silica. The proposed membrane successfully purifies high-quality DNA within 5 min, whereas a commercial purification kit needs more than an hour.

  13. Rapid, microscale, acetyl bromide-based method for high-throughput determination of lignin content in Arabidopsis thaliana.

    PubMed

    Chang, Xue Feng; Chandra, Richard; Berleth, Thomas; Beatson, Rodger P

    2008-08-27

    The acetyl bromide method has been modified to enable the rapid microscale determination of lignin content in Arabidopsis with the goal of determining the genes that control lignin in plants. Modifications include reduction in sample size, use of a microball mill, adoption of a modified rapid method of extraction, use of an ice-bath to stabilize solutions and reduction in the volume of solutions. The microscale method was shown to be rapid, accurate and precise with values in agreement with those determined by the full-scale acetyl bromide method. The extinction coefficient for Arabidopsis lignin, dissolved using acetyl bromide, was determined to be 23.35 g(-1) L cm(-1) at 280 nm. This value is independent of the Arabidopsis accession, environmental growth conditions and is insensitive to lignin structure. The newly developed method can be used to determine lignin content in the inflorescence stems of Arabidopsis for mapping of lignin-related genes.

  14. An ELISA Based Binding and Competition Method to Rapidly Determine Ligand-receptor Interactions.

    PubMed

    Syedbasha, Mohameedyaseen; Linnik, Janina; Santer, Deanna; O'Shea, Daire; Barakat, Khaled; Joyce, Michael; Khanna, Nina; Tyrrell, D Lorne; Houghton, Michael; Egli, Adrian

    2016-03-14

    A comprehensive understanding of signaling pathways requires detailed knowledge regarding ligand-receptor interaction. This article describes two fast and reliable point-by-point protocols of enzyme-linked immunosorbent assays (ELISAs) for the investigation of ligand-receptor interactions: the direct ligand-receptor interaction assay (LRA) and the competition LRA. As a case study, the ELISA based analysis of the interaction between different lambda interferons (IFNLs) and the alpha subunit of their receptor (IL28RA) is presented: the direct LRA is used for the determination of dissociation constants (KD values) between receptor and IFN ligands, and the competition LRA for the determination of the inhibitory capacity of an oligopeptide, which was designed to compete with the IFNLs at their receptor binding site. Analytical steps to estimate KD and half maximal inhibitory concentration (IC50) values are described. Finally, the discussion highlights advantages and disadvantages of the presented method and how the results enable a better molecular understanding of ligand-receptor interactions.

  15. Development of a versatile, easy and rapid atmospheric monitor for benzene, toluene, ethylbenzene and xylenes determination in air.

    PubMed

    Esteve-Turrillas, Francesc A; Ly-Verdú, Saray; Pastor, Agustín; de la Guardia, Miguel

    2009-11-27

    A new procedure for the passive sampling in air of benzene, toluene, ethylbenzene and xylene isomers (BTEX) is proposed. A low-density polyethylene layflat tube filled with a mixture of solid phases provided a high versatility tool for the sampling of volatile compounds from air. Several solid phases were assayed in order to increase the BTEX absorption in the sampler and a mixture of florisil and activated carbon provided the best results. Direct head-space-gas chromatography-mass spectrometry (HS-GC-MS) measurement of the whole deployed sampler was employed for a fast determination of BTEX. Absorption isotherms were used to develop simple mathematical models for the estimation of BTEX time-weighted average concentrations in air. The proposed samplers were used to determine BTEX in indoor air environments and results were compared with those found using two reference methodologies: triolein-containing semipermeable membrane devices (SPMDs) and diffusive Radiello samplers. In short, the developed sampling system and analytical strategy provides a versatile, easy and rapid atmospheric monitor (VERAM).

  16. Rapid determination of radon daughters and of artificial radionuclides in air by online gamma-ray spectrometry.

    PubMed

    Hötzl, H; Winkler, R

    1993-01-01

    For the determination of airborne radionuclide concentrations in real time, a fixed filter device was constructed which fits directly onto a germanium detector with standard nuclear electronics and a multichannel analyzer buffer connected via a data line to a personal computer for remote control and on-line spectrum evaluation. The on-line gamma-ray spectrometer was applied to the study of radon decay product concentrations in ground-level air and to the rapid detection of any contamination of the environmental air by artificial radionuclides. At Munich-Neuherberg, depending on the meterological conditions, the measured air concentrations of 214Pb, the first gamma-ray-emitting member of the 222Rn decay series, varied from about 1 to 50 Bq m-3. For the artificial radionuclides 60Co, 131I and 137Cs the detection limits were determined as a function of the varying natural radon daughter concentrations at sampling and counting times of 1 h or 1 day. For these radionuclides minimum detectable air activity concentrations of 0.3 or 0.001 Bq m-3, respectively, were obtained at low radon daughter levels. At high radon daughter levels the respective detection limits were found to be higher by a factor of only about 2.

  17. Preparation of molecularly imprinted polymer with double templates for rapid simultaneous determination of melamine and dicyandiamide in dairy products.

    PubMed

    Liu, Jiang; Song, Han; Liu, Jie; Liu, Yuan; Li, Le; Tang, Hui; Li, Yingchun

    2015-03-01

    In this study, a rapid and accurate determination strategy was established for simultaneous measurement of melamine (MLM) and dicyandiamide (DCD) directly in powdered milk by coupling molecularly imprinted solid-phase extraction (MISPE) with high performance liquid chromatography (HPLC). A novel double-template technique was adopted for preparing SPE packing agent and the obtained double-templated (MLM and DCD) molecularly imprinted polymers (MD-MIPs) was characterized by Fourier-transform infrared spectroscopy and scanning electron microscope (SEM). The molecular recognition ability and the binding capability of the as-prepared polymers towards MLM and DCD were evaluated via static and dynamic binding tests, and it was found that the MD-MIPs showed better affinity and selectivity for both templates compared with single-templated MIPs and non-imprinted polymers (NIPs). An approach based on MISPE and HPLC was then developed and optimized to detect MLM and DCD in powdered milk. The detection limit of the method (S/N=3) were 0.13 μg/g for MLM and 0.07 μg/g for DCD, and the relative standard deviation (RSD) of intra-day and inter-day determination for MLM was 3.3% and 4.7%, and 3.5% and 5.9% for DCD. The recoveries in MLM and DCD analysis at three spiked levels were 93.1-100.1% and 75.7-82.5%, respectively, with all RSD less than 5.2%.

  18. Fast Moment Magnitude Determination from P-wave Trains for Bucharest Rapid Early Warning System (BREWS)

    NASA Astrophysics Data System (ADS)

    Lizurek, Grzegorz; Marmureanu, Alexandru; Wiszniowski, Jan

    2017-03-01

    Bucharest, with a population of approximately 2 million people, has suffered damage from earthquakes in the Vrancea seismic zone, which is located about 170 km from Bucharest, at a depth of 80-200 km. Consequently, an earthquake early warning system (Bucharest Rapid earthquake Early Warning System or BREWS) was constructed to provide some warning about impending shaking from large earthquakes in the Vrancea zone. In order to provide quick estimates of magnitude, seismic moment was first determined from P-waves and then a moment magnitude was determined from the moment. However, this magnitude may not be consistent with previous estimates of magnitude from the Romanian Seismic Network. This paper introduces the algorithm using P-wave spectral levels and compares them with catalog estimates. The testing procedure used waveforms from about 90 events with catalog magnitudes from 3.5 to 5.4. Corrections to the P-wave determined magnitudes according to dominant intermediate depth events mechanism were tested for November 22, 2014, M5.6 and October 17, M6 events. The corrections worked well, but unveiled overestimation of the average magnitude result of about 0.2 magnitude unit in the case of shallow depth event ( H < 60 km). The P-wave spectral approach allows for the relatively fast estimates of magnitude for use in BREWS. The average correction taking into account the most common focal mechanism for radiation pattern coefficient may lead to overestimation of the magnitude for shallow events of about 0.2 magnitude unit. However, in case of events of intermediate depth of M6 the resulting M w is underestimated at about 0.1-0.2. We conclude that our P-wave spectral approach is sufficiently robust for the needs of BREWS for both shallow and intermediate depth events.

  19. Addressing social determinants of health inequities through settings: a rapid review.

    PubMed

    Newman, Lareen; Baum, Fran; Javanparast, Sara; O'Rourke, Kerryn; Carlon, Leanne

    2015-09-01

    Changing settings to be more supportive of health and healthy choices is an optimum way to improve population health and health equity. This article uses the World Health Organisation's (1998) (WHO Health Promotion Glossary. WHO Collaborating Centre for Health Promotion, Department of Public Health and Community Medicine, University of Sydney, NSW) definition of settings approaches to health promotion as those focused on modifying settings' structure and nature. A rapid literature review was undertaken in the period June-August 2014, combining a systematically conducted search of two major databases with targeted searches. The review focused on identifying what works in settings approaches to address the social determinants of health inequities, using Fair Foundations: the VicHealth framework for health equity. This depicts the social determinants of health inequities as three layers of influence, and entry points for action to promote health equity. The evidence review identified work in 12 settings (cities; communities and neighbourhoods; educational; healthcare; online; faith-based; sports; workplaces; prisons; and nightlife, green and temporary settings), and work at the socioeconomic, political and cultural context layer of the Fair Foundations framework (governance, legislation, regulation and policy). It located a relatively small amount of evidence that settings themselves are being changed in ways which address the social determinants of health inequities. Rather, many initiatives focus on individual behaviour change within settings. There is considerable potential for health promotion professionals to focus settings work more upstream and so replace or integrate individual approaches with those addressing daily living conditions and higher level structures, and a significant need for programmes to be evaluated for differential equity impacts and published to provide a more solid evidence base. © The Author 2015. Published by Oxford University Press. All

  20. Rapid identification of a Mycobacterium tuberculosis full genetic drug resistance profile through whole genome sequencing directly from sputum.

    PubMed

    Nimmo, Camus; Doyle, Ronan; Burgess, Carrie; Williams, Rachel; Gorton, Rebecca; McHugh, Timothy D; Brown, Mike; Morris-Jones, Stephen; Booth, Helen; Breuer, Judith

    2017-09-01

    Resistance to second-line tuberculosis drugs is common, but slow to diagnose with phenotypic drug sensitivity testing. Rapid molecular tests speed up diagnosis, but can only detect limited mutations. Whole genome sequencing (WGS) of culture isolates can generate a complete genetic drug resistance profile, but is delayed by the initial culture step. In the case presented here, successful WGS directly from sputum was achieved using targeted enrichment. A 29-year-old Nigerian woman was diagnosed with tuberculosis. Xpert MTB/RIF and Hain line probe assays identified rpoB and inhA mutations consistent with rifampicin and intermediate isoniazid resistance, and a further possible mutation conferring fluoroquinolone resistance. WGS directly from sputum identified a further inhA mutation consistent with high-level isoniazid resistance and confirmed the absence of fluoroquinolone resistance. Isoniazid was stopped, and the patient has completed 18 months of a fluoroquinolone-based regimen without relapse. Compared to rapid molecular tests (which can only examine a limited number of mutations) and WGS of culture isolates (which requires a culture step), WGS directly from sputum can quickly generate a complete genetic drug resistance profile. In this case, WGS altered the clinical management of drug-resistant tuberculosis and demonstrated potential for guiding individualized drug treatment where second-line drug resistance is common. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

  1. Prospective multicentre evaluation of the direct nitrate reductase assay for the rapid detection of extensively drug-resistant tuberculosis.

    PubMed

    Martin, Anandi; Imperiale, Belen; Ravolonandriana, Pascaline; Coban, Ahmet Yilmaz; Akgunes, Alper; Ikram, Aamer; Satti, Luqman; Odoun, Mathieu; Pandey, Pooja; Mishra, Manvi; Affolabi, Dissou; Singh, Urvashi; Rasolofo, Voahangy; Morcillo, Nora; Vandamme, Peter; Palomino, Juan Carlos

    2014-02-01

    To perform a multicentre study evaluating the performance of the direct nitrate reductase assay (NRA) for the detection of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis in sputum samples. The study was conducted in six laboratories performing tuberculosis diagnosis that were located in six different countries. The NRA was performed directly on sputum samples in parallel with the reference method used at each site. Detection of resistance was performed for rifampicin, isoniazid, ofloxacin and kanamycin. Excellent agreement was obtained for all drugs tested at the majority of sites. The accuracy was 93.7%-100% for rifampicin, 88.2%-100% for isoniazid, 94.6%-100% for ofloxacin and 100% for kanamycin. The majority of NRA results were available at day 21 for sites 1, 2 and 5. Site 3 had a turnaround time of 13.9 days, at site 4 it was 18.4 days and at site 6 it was 16.2 days. The contamination rate ranged between 2.5% and 12%. Rapid detection of drug resistance by the direct NRA on sputum smear-positive samples was accurate and easy to implement in clinical diagnostic laboratories, making it a good alternative for rapid screening for MDR and XDR tuberculosis.

  2. Rapid High-throughput Species Identification of Botanical Material Using Direct Analysis in Real Time High Resolution Mass Spectrometry.

    PubMed

    Lesiak, Ashton D; Musah, Rabi A

    2016-10-02

    We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, and that these chemical fingerprints can be used for plant species identification. The mass spectral data can be acquired rapidly and in a high throughput manner without the need for sample extraction, derivatization or pH adjustment steps. The use of this technique bypasses challenges presented by more conventional techniques including lengthy chromatography analysis times and resource intensive methods. The high throughput capabilities of the direct analysis in real time-high resolution mass spectrometry protocol, coupled with multivariate statistical analysis processing of the data, provide not only class characterization of plants, but also yield species and varietal information. Here, the technique is demonstrated with two psychoactive plant products, Mitragyna speciosa (Kratom) and Datura (Jimsonweed), which were subjected to direct analysis in real time-high resolution mass spectrometry followed by statistical analysis processing of the mass spectral data. The application of these tools in tandem enabled the plant materials to be rapidly identified at the level of variety and species.

  3. Rapid High-throughput Species Identification of Botanical Material Using Direct Analysis in Real Time High Resolution Mass Spectrometry

    PubMed Central

    Lesiak, Ashton D.; Musah, Rabi A.

    2016-01-01

    We demonstrate that direct analysis in real time-high resolution mass spectrometry can be used to produce mass spectral profiles of botanical material, and that these chemical fingerprints can be used for plant species identification. The mass spectral data can be acquired rapidly and in a high throughput manner without the need for sample extraction, derivatization or pH adjustment steps. The use of this technique bypasses challenges presented by more conventional techniques including lengthy chromatography analysis times and resource intensive methods. The high throughput capabilities of the direct analysis in real time-high resolution mass spectrometry protocol, coupled with multivariate statistical analysis processing of the data, provide not only class characterization of plants, but also yield species and varietal information. Here, the technique is demonstrated with two psychoactive plant products, Mitragyna speciosa (Kratom) and Datura (Jimsonweed), which were subjected to direct analysis in real time-high resolution mass spectrometry followed by statistical analysis processing of the mass spectral data. The application of these tools in tandem enabled the plant materials to be rapidly identified at the level of variety and species. PMID:27768072

  4. Rapid Immunoassay for detection of Escherichia coli O157 directly from stool specimens.

    PubMed Central

    Park, C H; Vandel, N M; Hixon, D L

    1996-01-01

    A new and rapid ( < 1 h) enzyme-linked immunosorbent assay (ELISA) was compared with conventional sorbitol-MacConkey agar (SMAC) culture for the detection of Escherichia coli O157 from stool specimens. Among 34 positive specimens, confirmed by colony-sweeping and immunofluorescence stain methods, 6 did not exhibit visible sorbitol-negative colonies on SMAC. These six specimens would have been considered to be negative if SMAC alone had been used. The ELISA detected 31 of the 34 positive samples, including 5 of the above-mentioned 6 false-negative samples, resulting in a sensitivity and specificity of 91.2 and 99.5%, respectively. Cross-reactivity with other enteric pathogens was not noted by ELISA. The SMAC method had a sensitivity and specificity of 82.4 and 100%, respectively. The ELISA-negative specimens do not require culture confirmation, whereas positive results must be considered to be presumptive until confirmed by culture. The test is accurate and is easy to perform, making it a very efficient method for screening stool specimens for E. coli O157. PMID:8815126

  5. Smokefree cars in New Zealand: rapid research among stakeholders on attitudes and future directions.

    PubMed

    Tapp, Dylan; Thomson, George

    2009-09-25

    To conduct a rapid appraisal of the attitudes of New Zealand decision makers and tobacco control stakeholders on enacting a smokefree cars law. A media and document search was made for relevant official and other statements. In early 2008, nine semi-structured interviews were carried out involving three MPs, two officials of government health agencies and four members of NGOs with a stake in tobacco control. Interviews were audiotaped, transcribed, and analysed for themes. In official statements, and amongst the interview sample, there was general opposition to giving smokefree car legislation a current high priority. Reasons given for opposition to such a law included the suboptimal use of advocacy capital compared with other initiatives (e.g. tobacco display bans), the perceived success of relevant health marketing campaigns, and concerns over the current political will to enact legislation that targets smoker freedoms. More information on the extent of current child exposure to tobacco smoke in New Zealand cars, and on the reach and effectiveness of the New Zealand smokefree cars media campaign would help advocates and policymakers. Wider dissemination to policymakers of New Zealand public and smoker support for banning smoking in cars, and of the progress overseas on smokefree car laws, appears to be essential.

  6. Direct rapid prototyping of PDMS from a photomask film for micropatterning of biomolecules and cells.

    PubMed

    Hwang, Hyundoo; Kang, Gyumin; Yeon, Ju Hun; Nam, Yoonkey; Park, Je-Kyun

    2009-01-07

    The soft lithographic technique is a collection of simple and cost-effective patterning techniques which applies an elastomeric stamp to transfer a nano/micro-scale pattern. Patterning biological materials using soft lithography provides procedurally simple control of the surface chemistry and the cell environments. However, conventional methods for generating microstructures on a substrate require expensive clean room facilities and skillful training. Here we report a simple and inexpensive clean-room free process using a conventional photomask film as a master to fabricate elastomeric stamps or microfluidic channels. This ultra rapid prototyping technique was applied to print FITC labeled poly-L-lysine with a 10 microm feature size on a glass substrate using soft lithographic processes, such as micro-contact printing and micromolding in capillaries, for patterning human hepatocellular carcinoma cells, human skin fibroblasts and hippocampal neurons from E-18 Sprague-Dawley rat. This novel technique using a photomask film as a master would be very useful 'hands-on' tool for the generation of micro-patterned chemical or biological assays using cells and proteins.

  7. Rapid, Portable, Multiplexed Detection of Bacterial Pathogens Directly from Clinical Sample Matrices

    PubMed Central

    Phaneuf, Christopher R.; Mangadu, Betty; Piccini, Matthew E.; Singh, Anup K.; Koh, Chung-Yan

    2016-01-01

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. This platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated in diarrheal and enteric diseases in less than 20 min. PMID:27669320

  8. Rapid, portable, multiplexed detection of bacterial pathogens directly from clinical sample matrices

    SciTech Connect

    Phaneuf, Christopher R.; Mangadu, Betty Lou Bosano; Piccini, Matthew E.; Singh, Anup K.; Koh, Chung -Yan

    2016-09-23

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. Furthermore, this platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated in diarrheal and enteric diseases in less than 20 min.

  9. Aligned carbon nanotube, graphene and graphite oxide thin films via substrate-directed rapid interfacial deposition.

    PubMed

    D'Arcy, Julio M; Tran, Henry D; Stieg, Adam Z; Gimzewski, James K; Kaner, Richard B

    2012-05-21

    A procedure for depositing thin films of carbon nanostructures is described that overcomes the limitations typically associated with solution based methods. Transparent and conductively continuous carbon coatings can be grown on virtually any type of substrate within seconds. Interfacial surface tension gradients result in directional fluid flow and film spreading at the water/oil interface. Transparent films of carbon nanostructures are produced including aligned ropes of single-walled carbon nanotubes and assemblies of single sheets of chemically converted graphene and graphite oxide. Process scale-up, layer-by-layer deposition, and a simple method for coating non-activated hydrophobic surfaces are demonstrated.

  10. Relative Motion Between the Rivera and North American Plates Determined from the Slip Directions of Earthquakes

    NASA Astrophysics Data System (ADS)

    Suárez, Gerardo; Jaramillo, Said H.; Bandy, W. L.

    2013-12-01

    So far, the direction and rate of relative motion between the Rivera and the North American plates (RIV-NAM) has been determined by the combination of two Euler poles: Rivera (RIV), with respect to Pacific (PAC), and PAC with respect to North America. Here, we estimate the relative motion of this plate pair (RIV-NAM) assuming that the horizontal projection of the direction of slip of the earthquakes occurring on the RIV-NAM boundaries reflect their relative plate motion. A catalog of earthquakes for which focal mechanisms are reported since 1976 is used in the analysis. Earthquakes were considered in the three segments of the RIV-NAM plate boundary: the subduction zone of the Rivera plate beneath the Jalisco block, the Tres Marias Escarpment and the events associated with the Tamayo Fracture Zone. The best fitting Euler pole is determined using a grid search of 64 potential poles. The slip direction predicted for each grid point is compared to the slip direction of the focal mechanisms of the earthquakes on the plate boundary. The best fitting Euler pole, determined in a root mean square sense (RMS), is located at 21.8°N, 107.6°W. A rate of rotation of 5.3°/year is estimated assuming the seismic earthquake cycle of the 1932 and 1995 great earthquakes represents a lower bound of the rate of plate motion in the subduction zone. The best fitting Euler pole shows that the subduction of the Rivera plate takes place in a direction perpendicular to the trench with a relative velocity of 4.3 cm/year, offshore Manzanillo. The rate of relative motion RIV-NAM decreases from SE to NW. North of approximately 21°N, the subduction of the Rivera plate becomes oblique to the trench and the relative velocity between the two plates decreases to an average of 1.9 cm/year. This slow rate of convergence may explain the rapid decrease of seismicity in the trench and the apparent absence of large earthquakes in this region. In the Tres Marias Escarpment, our best-fitting pole suggests

  11. Airflow-directed in situ electrospinning of a medical glue of cyanoacrylate for rapid hemostasis in liver resection

    NASA Astrophysics Data System (ADS)

    Jiang, Kai; Long, Yun-Ze; Chen, Zhao-Jun; Liu, Shu-Liang; Huang, Yuan-Yuan; Jiang, Xingyu; Huang, Zhi-Qiang

    2014-06-01

    Rapid hemostasis of solitary organs is still a big challenge in surgical procedures or after major trauma in both civilians and on the battlefield. Here, we report the first use of an airflow-directed in situ electrospinning method to precisely and homogeneously deposit a medical glue of n-octyl-2-cyanoacrylate (OCA) ultrathin fibers onto a wound surface to realize rapid hemostasis in dozens of seconds. In vivo and in vitro experiments on pig liver resection demonstrate that the self-assembled electrospun OCA membrane with high strength, good flexibility and integrity is very compact and no fluid seeping is observed even under a pressure of 147 mm Hg. A similar effect has been achieved in an in vivo experiment on pig lung resection. The results provide a very promising alternative for rapid hemostasis of solitary organs as well as other traumas, providing evidence that the postoperative drainage tube may not be always necessary for surgery in the near future.Rapid hemostasis of solitary organs is still a big challenge in surgical procedures or after major trauma in both civilians and on the battlefield. Here, we report the first use of an airflow-directed in situ electrospinning method to precisely and homogeneously deposit a medical glue of n-octyl-2-cyanoacrylate (OCA) ultrathin fibers onto a wound surface to realize rapid hemostasis in dozens of seconds. In vivo and in vitro experiments on pig liver resection demonstrate that the self-assembled electrospun OCA membrane with high strength, good flexibility and integrity is very compact and no fluid seeping is observed even under a pressure of 147 mm Hg. A similar effect has been achieved in an in vivo experiment on pig lung resection. The results provide a very promising alternative for rapid hemostasis of solitary organs as well as other traumas, providing evidence that the postoperative drainage tube may not be always necessary for surgery in the near future. Electronic supplementary information (ESI) available

  12. Direct, Label-Free, and Rapid Transistor-Based Immunodetection in Whole Serum.

    PubMed

    Gutiérrez-Sanz, Óscar; Andoy, Nesha M; Filipiak, Marcin S; Haustein, Natalie; Tarasov, Alexey

    2017-09-22

    Transistor-based biosensors fulfill many requirements posed upon transducers for future point-of-care diagnostic devices such as scalable fabrication and label-free and real-time quantification of chemical and biological species with high sensitivity. However, the short Debye screening length in physiological samples (<1 nm) has been a major drawback so far, preventing direct measurements in serum. In this work, we demonstrate how tailoring the sensing surface with short specific biological receptors and a polymer polyethylene glycol (PEG) can strongly enhance the sensor response. In addition, the sensor performance can be dramatically improved if the measurements are performed at elevated temperatures (37 °C instead of 21 °C). With this novel approach, highly sensitive and selective detection of a representative immunosensing parameter-human thyroid-stimulating hormone-is shown over a wide measuring range with subpicomolar detection limits in whole serum. To the best of our knowledge, this is the first demonstration of direct immunodetection in whole serum using transistor-based biosensors, without the need for sample pretreatment, labeling, or washing steps. The presented sensor is low-cost, can be easily integrated into portable diagnostics devices, and offers a competitive performance compared to state-of-the-art central laboratory analyzers.

  13. Rapid extraction of melamine in powdered milk for direct electrospray ionization tandem mass spectrometry analysis.

    PubMed

    Domingo, Elisângela do Carmo; Tireli, Aline Auxiliadora; Nunes, Cleiton Antonio; Batista, Alexandre Vieira; Guerreiro, Mário César; Pinto, Sandra Maria

    2015-01-01

    A combination of a simple pretreatment for melamine extraction and direct analysis in electrospray ionization tandem mass spectrometry (ESI-MS/MS) is proposed. Three pretreatments were evaluated. The first was based on suppressing interference using acetonitrile. The second used sulphuric acid and trichloroacetic acid to suppress interference and for melamine extraction, respectively. The third used sulphuric acid to suppress milk interference, trichloroacetic acid for melamine precipitation, and ethyl acetate for melamine extraction. However, only the last pretreatment suppressed milk interference in melamine detection and a good linearity (R(2)=0.99) was obtained. The presence of MS/MS 85 on melamine fragmentation spectrum showed the selectivity of this method. The limit of detection and limit of quantification were 0.269 µg L(-1) and 0.897 µg L(-1), respectively. The recoveries and relative standard deviation (RDS) of method were lower than 114% and 7.86%, respectively. Further, the research was extended to elucidate the nature of the melamine in the extract through infrared spectroscopy and microscopy analyses. The precipitate was characterized as melaminium bis(trichloroacetate) dihydrate, which is generated through hydrogen bound formation in an interaction between melamine and trichloroacetic acid. Therefore, a simple, fast, and easy method for melamine extraction and direct ESI-MS/MS analysis was developed. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Rapid simultaneous determination of amines and organic acids in citrus using high-performance liquid chromatography.

    PubMed

    Uckoo, Ram M; Jayaprakasha, Guddadarangavvanahally K; Nelson, Shad D; Patil, Bhimanagouda S

    2011-01-15

    Rapid analytical method for the simultaneous separation and determination of amines and organic acids is a vital interest for quality control of citrus and their products. In the present study, a simultaneous high performance liquid chromatography (HPLC) method for the rapid separation of three amines and two organic acids was developed. Chromatographic separation of compounds was achieved using Xbridge C(18) column at ambient temperature, with an isocratic mobile phase of 3mM phosphoric acid at a flow rate of 1.0 mL min(-1). A photodiode array (PDA) detector was used to monitor the eluent at 223 nm and 254 nm with a total analysis time of 10 min. Extraction of amines and organic acids from citrus juice was optimized. The method was validated by tests of linearity, recovery, precision and ruggedness. The limit of detection (LOD) and limit of quantification (LOQ) for amines and ascorbic acid were determined to be 5 ng and 9.8 ng, respectively. All calibration curves showed good linearity (R(2) ≥ 0.9999) within the test ranges. The recoveries of the amines and organic acids ranged between 84% and 117%. The identity of each peak was confirmed by mass spectral (MS) analysis. The developed method was successfully applied to analyze the content of amines and organic acids in six different species and two varieties of citrus. Results indicate that mandarin and Marrs sweet orange contain high level of amines, while pummelo and Rio Red grapefruit had high content of ascorbic acid (137-251 μg mL(-1)) and citric acid (5-22 mg mL(-1)). Synephrine was the major amine present in Clementine (114 μg mL(-1)) and Marrs sweet orange (85 μg mL(-1)). To the best of our knowledge, this is the first report on simultaneous separation and quantification of amines and organic acids in Marrs sweet orange, Meyer lemon, Nova tangerine, Clementine, Ugli tangelo and Wekiwa tangelo.

  15. Rapid Screening of Immobilized Amine CO2 Sorbents for Steam Stability by Their Direct Contact with Liquid H2 O.

    PubMed

    Wilfong, Walter Christopher; Kail, Brian W; Gray, McMahan L

    2015-06-22

    Rapid testing of hydrophilic and hydrophobic basic immobilized amine sorbents (BIAS) for CO2 capture stability under practical conditions was achieved by direct contact of the sorbents with flowing liquid water. Losses in both CO2 capture capacity and amine content of sorbents after exposure to 0.5 mL min(-1) of H2 O at 25 °C for 40 min followed similar trends as losses observed after exposure to N2 /steam (105 °C, 7 % H2 O) for 10 h. We also found that hydrophobic TMPED helped stabilize sorbents to H2 O, which was confirmed by DRIFTS and combined TGA-DSC.

  16. A rapid, quantitative assay for direct detection of microRNAs and other small RNAs using splinted ligation

    PubMed Central

    Maroney, Patricia A.; Chamnongpol, Sangpen; Souret, Frédéric; Nilsen, Timothy W.

    2007-01-01

    The discovery and characterization of microRNAs (miRNAs) and other families of short RNAs has led to a rapid expansion of research directed at elucidating their expression patterns and regulatory functions. Here, we describe a convenient, sensitive, and straightforward method to detect and quantitate specific miRNA levels in unfractionated total RNA samples. The method, based on splinted ligation, does not require specialized equipment or any amplification step, and is significantly faster and more sensitive than Northern blotting. We demonstrate that the method can be used to detect various classes of small regulatory RNAs from different organisms. PMID:17456563

  17. Rapid low dose electron tomography using a direct electron detection camera

    PubMed Central

    Migunov, Vadim; Ryll, Henning; Zhuge, Xiaodong; Simson, Martin; Strüder, Lothar; Batenburg, K. Joost; Houben, Lothar; Dunin-Borkowski, Rafal E.

    2015-01-01

    We demonstrate the ability to record a tomographic tilt series containing 3487 images in only 3.5 s by using a direct electron detector in a transmission electron microscope. The electron dose is lower by at least one order of magnitude when compared with that used to record a conventional tilt series of fewer than 100 images in 15–60 minutes and the overall signal-to-noise ratio is greater than 4. Our results, which are illustrated for an inorganic nanotube, are important for ultra-low-dose electron tomography of electron-beam-sensitive specimens and real-time dynamic electron tomography of nanoscale objects with sub-ms temporal resolution. PMID:26434767

  18. Rapid, portable, multiplexed detection of bacterial pathogens directly from clinical sample matrices

    DOE PAGES

    Phaneuf, Christopher R.; Mangadu, Betty Lou Bosano; Piccini, Matthew E.; ...

    2016-09-23

    Enteric and diarrheal diseases are a major cause of childhood illness and death in countries with developing economies. Each year, more than half of a million children under the age of five die from these diseases. We have developed a portable, microfluidic platform capable of simultaneous, multiplexed detection of several of the bacterial pathogens that cause these diseases. Furthermore, this platform can perform fast, sensitive immunoassays directly from relevant, complex clinical matrices such as stool without extensive sample cleanup or preparation. Using only 1 µL of sample per assay, we demonstrate simultaneous multiplexed detection of four bacterial pathogens implicated inmore » diarrheal and enteric diseases in less than 20 min.« less

  19. Direct, rapid and sustainable vermicomposting of the leaf litter of neem (Azadirachta indica).

    PubMed

    Nayeem-Shah, M; Gajalakshmi, S; Abbasi, S A

    2015-01-01

    The recently developed concept of high rate vermicomposting was successfully used to enable direct vermicomoposting of neem leaves-without any pre-composting or cow dung supplementation as previously reported processes had necessitated. All the three epigeic species of earthworms that were explored, Eudrilus eugeniae, Eisenia fetida and Perionyx excavatus, provided efficient vermicast production with no mortality, persistent gain in body mass and good fecundity over the 16 months long period of reactor operation. In this period, all reactors were pulse-fed at the solid retention time of 20 days and were operated in the pseudo discretized continuous operation protocol developed earlier by the authors. With this, it was possible to almost completely dampen the influence of natural biodegradation of the feed or grazing by the earthworm born in the vermireactors. The findings, thus, conclusively prove that, all-through, the brisk vermicomposting was caused almost entirely by the action of the 'parent' earthworms on fresh feed.

  20. Rapid detection of NBOME's and other NPS on blotter papers by direct ATR-FTIR spectrometry.

    PubMed

    Coelho Neto, José

    2015-07-01

    Blotter paper is among the most common forms of consumption of new psychotropic substances (NPS), formerly referred as designer drugs. In many cases, users are misled to believe they are taking LSD when, in fact, they are taking newer and less known drugs like the NBOMEs or other substituted phenethylamines. We report our findings in quick testing of blotter papers for illicit substances like NBOMEs and other NPS by taking ATR-FTIR spectra directly from blotters seized on the streets, without any sample preparation. Both sides (front and back) of each blotter were tested. Collected data were analyzed by single- and multi-component spectral matching and submitted to chemometric discriminant analysis. Our results showed that, on 66.7% of the cases analyzed, seized blotters contained one or more types of NBOMEs, confirming the growing presence of this novel substances on the market. Matching IR signals were detected on both or just one side of the blotters and showed variable strength. Although no quantitative analysis was made, detection of these substances by the proposed approach serves as indication of variable and possibly higher dosages per blotter when compared to LSD, which showed to be below the detection limit of the applied method. Blotters containing a mescaline-like compound, later confirmed by GC-MS and LC-MS to be MAL (methallylescaline), a substance very similar to mescaline, were detected among the samples tested. Validity of direct ATR-FTIR testing was confirmed by checking the obtained results against independent GC-MS or LC-MS results for the same cases/samples. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  1. Rapid Screening for CRISPR-Directed Editing of the Drosophila Genome Using white Coconversion

    PubMed Central

    Ge, Daniel Tianfang; Tipping, Cindy; Brodsky, Michael H.; Zamore, Phillip D.

    2016-01-01

    Adoption of a streamlined version of the bacterial clustered regular interspersed short palindromic repeat (CRISPR)/Cas9 defense system has accelerated targeted genome engineering. The Streptococcus pyogenes Cas9 protein, directed by a simplified, CRISPR-like single-guide RNA, catalyzes a double-stranded DNA break at a specific genomic site; subsequent repair by end joining can introduce mutagenic insertions or deletions, while repair by homologous recombination using an exogenous DNA template can incorporate new sequences at the target locus. However, the efficiency of Cas9-directed mutagenesis is low in Drosophila melanogaster. Here, we describe a strategy that reduces the time and effort required to identify flies with targeted genomic changes. The strategy uses editing of the white gene, evidenced by altered eye color, to predict successful editing of an unrelated gene-of-interest. The red eyes of wild-type flies are readily distinguished from white-eyed (end-joining-mediated loss of White function) or brown-eyed (recombination-mediated conversion to the whitecoffee allele) mutant flies. When single injected G0 flies produce individual G1 broods, flies carrying edits at a gene-of-interest were readily found in broods in which all G1 offspring carried white mutations. Thus, visual assessment of eye color substitutes for wholesale PCR screening of large numbers of G1 offspring. We find that end-joining-mediated mutations often show signatures of microhomology-mediated repair and that recombination-based mutations frequently involve donor plasmid integration at the target locus. Finally, we show that gap repair induced by two guide RNAs more reliably converts the intervening target sequence, whereas the use of Lig4169 mutants to suppress end joining does not improve recombination efficacy. PMID:27543296

  2. Rapid Screening for CRISPR-Directed Editing of the Drosophila Genome Using white Coconversion.

    PubMed

    Ge, Daniel Tianfang; Tipping, Cindy; Brodsky, Michael H; Zamore, Phillip D

    2016-10-13

    Adoption of a streamlined version of the bacterial clustered regular interspersed short palindromic repeat (CRISPR)/Cas9 defense system has accelerated targeted genome engineering. The Streptococcus pyogenes Cas9 protein, directed by a simplified, CRISPR-like single-guide RNA, catalyzes a double-stranded DNA break at a specific genomic site; subsequent repair by end joining can introduce mutagenic insertions or deletions, while repair by homologous recombination using an exogenous DNA template can incorporate new sequences at the target locus. However, the efficiency of Cas9-directed mutagenesis is low in Drosophila melanogaster Here, we describe a strategy that reduces the time and effort required to identify flies with targeted genomic changes. The strategy uses editing of the white gene, evidenced by altered eye color, to predict successful editing of an unrelated gene-of-interest. The red eyes of wild-type flies are readily distinguished from white-eyed (end-joining-mediated loss of White function) or brown-eyed (recombination-mediated conversion to the white(coffee) allele) mutant flies. When single injected G0 flies produce individual G1 broods, flies carrying edits at a gene-of-interest were readily found in broods in which all G1 offspring carried white mutations. Thus, visual assessment of eye color substitutes for wholesale PCR screening of large numbers of G1 offspring. We find that end-joining-mediated mutations often show signatures of microhomology-mediated repair and that recombination-based mutations frequently involve donor plasmid integration at the target locus. Finally, we show that gap repair induced by two guide RNAs more reliably converts the intervening target sequence, whereas the use of Lig4(169) mutants to suppress end joining does not improve recombination efficacy.

  3. One-day pulsed-field gel electrophoresis protocol for rapid determination of emetic Bacillus cereus isolates.

    PubMed

    Kaminska, Paulina S; Fiedoruk, Krzysztof; Jankowska, Dominika; Mahillon, Jacques; Nowosad, Karol; Drewicka, Ewa; Zambrzycka, Monika; Swiecicka, Izabela

    2015-04-01

    Bacillus cereus, the Gram-positive and spore-forming ubiquitous bacterium, may cause emesis as the result of food intoxication with cereulide, a heat-stable emetic toxin. Rapid determination of cereulide-positive B. cereus isolates is of highest importance due to consequences of this intoxication for human health and life. Here we present a 1-day pulsed-field gel electrophoresis for emetic B. cereus isolates, which allows rapid and efficient determination of their genomic relatedness and helps determining the source of intoxication in case of outbreaks caused by these bacilli.

  4. Application of ring lasers to determine the directions to the poles of Earth's rotation

    SciTech Connect

    Golyaev, Yu D; Kolbas, Yu Yu

    2012-10-31

    Application of a ring laser to determine the directions to the poles of Earth's rotation is considered. The maximum accuracy of determining the directions is calculated, physical and technical mechanisms that limit the accuracy are analysed, and the instrumental errors are estimated by the example of ring He - Ne lasers with Zeeman biasing. (laser applications and other topics in quantum electronics)

  5. Microwave dielectric method for the rapid, non-destructive determination of bulk density and moisture content of peanut hull pellets

    USDA-ARS?s Scientific Manuscript database

    A dielectric-based method was used to determine rapidly and nondestructively moisture content and bulk density of peanut-hull pellets from free-space measurement of their dielectric properties at microwave frequencies. For moisture content determination, a permittivity-based function which allows mo...

  6. Rapid fabrication of microdevices using laser direct writing and replica moulding technique

    NASA Astrophysics Data System (ADS)

    Antończak, A. J.; Stepak, B. D.; Abramski, K. M.

    2016-03-01

    This paper presents a method that enables fast and low-cost fabrication of microchannels with oval cross-section. The procedure is based on formation of a concave meniscus at the interface between an initially cured PDMS and a polymeric mould fabricated using excimer laser. The replica is formed by expanding gas trapped within the structures of the mould during thermal curing. A second shaping factor is connected with surface phenomena at the interface between the mould, gas and partially cured PDMS. The final shape of the meniscus is determined when the PDMS reaches the high cure extent.

  7. Rapid determination of sulbactam and tazobactam in human serum by high-performance liquid chromatography.

    PubMed

    Guillaume, Y; Peyrin, E; Guinchard, C

    1995-03-24

    A simple and rapid HPLC method for the determination of tazobactam and sulbactam, two beta-lactamase inhibitors, in serum for the therapeutic follow-up of patients is described. The effect of the pH of the aqueous mobile phase and column temperature on column efficiency and retention were examined and equations for their dependences were derived. The use of a chromatographic response function showed that methanol-buffer (5:95, v/v) (pH 6.3) as the mobile phase and a 45 degrees C column temperature were optimum values for chromatographic separation. The analytical method was linear from 10 to 200 micrograms/ml. This assay limit range is sufficient for the analysis of human serum. The limit of detection was 10 micrograms/ml for sulbactam and 5 micrograms/ml for tazobactam. The coefficient of variation was less than 5%. The speed at which this assay can be performed makes it especially useful for estimating the levels of these drugs in human serum.

  8. Rapid determination of methanol content in paper materials by alkaline extraction, coupled with headspace analysis.

    PubMed

    Zhang, Chun-Yun; Li, Ling-Ling; Chai, Xin-Sheng; Barnes, Donald G

    2014-07-11

    This study reports on a rapid method for the determination of methanol in paper-based materials by alkaline extraction, coupled with headspace analysis. Methanol partition equilibria between solid-liquid phases and vapor-liquid phases were conducted in two separate containers, from which an equation for calculating the total methanol content in the original paper sample was derived. It was found that the extraction equilibrium of methanol from solid sample could be achieved within 5min at room temperature using a high-speed disintegrator, and a subsequent neutralization step is an effective way to prevent methanol from being regenerated at high temperature during headspace equilibration. The results showed that the relative standard deviations for reproducibility tests were in the range of 1.86-6.03%, and the recoveries were in the range of 92.3-107%. The present method is simple and practical; it can be an efficient tool for quantifying the methanol content in paper-based materials and thus play an important role in the investigation of methanol migration behavior in food and beverage packaging.

  9. SIS Mixer Design for a Broadband Millimeter Spectrometer Suitable for Rapid Line Surveys and Redshift Determinations

    NASA Technical Reports Server (NTRS)

    Rice, F.; Sumner, M.; Zmuidzinas, J.; Hu, R.; LeDuc, H.; Harris, A.; Miller, D.

    2004-01-01

    We present some detail of the waveguide probe and SIS mixer chip designs for a low-noise 180-300 GHz double- sideband receiver with an instantaneous RF bandwidth of 24 GHz. The receiver's single SIS junction is excited by a broadband, fixed-tuned waveguide probe on a silicon substrate. The IF output is coupled to a 6-18 GHz MMIC low- noise preamplifier. Following further amplification, the output is processed by an array of 4 GHz, 128-channel analog autocorrelation spectrometers (WASP 11). The single-sideband receiver noise temperature goal of 70 Kelvin will provide a prototype instrument capable of rapid line surveys and of relatively efficient carbon monoxide (CO) emission line searches of distant, dusty galaxies. The latter application's goal is to determine redshifts by measuring the frequencies of CO line emissions from the star-forming regions dominating the submillimeter brightness of these galaxies. Construction of the receiver has begun; lab testing should begin in the fall. Demonstration of the receiver on the Caltech Submillimeter Observatory (CSO) telescope should begin in spring 2003.

  10. Determination of aflatoxins in grains and raw peanuts by a rapid procedure with fluorometric analysis.

    PubMed

    Malone, B R; Humphrey, C W; Romer, T R; Richard, J L

    2000-01-01

    A rapid, quantitative, inexpensive, and efficient method was developed to determine aflatoxins in corn, corn meal, popcorn, rice, wheat, cottonseed, and peanuts. Samples are ground and extracted with methanol-water (80 + 20). A portion of the extract is cleaned up by passage through a solid-phase separatory column, 500 microL purified extract is derivatized with a bromine reagent, and fluorescence of the solution is immediately quantified with a calibrated fluorometer containing a broad wavelength pulsed xenon light source. This method can quantify aflatoxin from 5 to 5000 ppb without dilution and was linear when applied to samples of noncontaminated corn spiked at 0 to 5000 micrograms aflatoxin B1/g. Correlation coefficients of the method with LC for multiple analyses for corn (n = 34), cottonseed (n = 32), and peanuts (n = 11) were 0.999, 0.995, and 0.980, respectively. Individual analyses may be conducted in less than 5 min, and grouping of samples is unnecessary. The sensitivity of the method for corn is 5 ppb and the fluorometer, under the operating conditions, has a limit of detection of 0.6 ng aflatoxin B1.

  11. Rapid fusion method for the determination of refractory thorium and uranium isotopes in soil samples

    SciTech Connect

    Maxwell, Sherrod L.; Hutchison, Jay B.; McAlister, Daniel R.

    2015-02-14

    Recently, approximately 80% of participating laboratories failed to accurately determine uranium isotopes in soil samples in the U.S Department of Energy Mixed Analyte Performance Evaluation Program (MAPEP) Session 30, due to incomplete dissolution of refractory particles in the samples. Failing laboratories employed acid dissolution methods, including hydrofluoric acid, to recover uranium from the soil matrix. The failures illustrate the importance of rugged soil dissolution methods for the accurate measurement of analytes in the sample matrix. A new rapid fusion method has been developed by the Savannah River National Laboratory (SRNL) to prepare 1-2 g soil sample aliquots very quickly, with total dissolution of refractory particles. Soil samples are fused with sodium hydroxide at 600 ºC in zirconium crucibles to enable complete dissolution of the sample. Uranium and thorium are separated on stacked TEVA and TRU extraction chromatographic resin cartridges, prior to isotopic measurements by alpha spectrometry on cerium fluoride microprecipitation sources. Plutonium can also be separated and measured using this method. Batches of 12 samples can be prepared for measurement in <5 hours.

  12. Rapid fusion method for the determination of refractory thorium and uranium isotopes in soil samples

    DOE PAGES

    Maxwell, Sherrod L.; Hutchison, Jay B.; McAlister, Daniel R.

    2015-02-14

    Recently, approximately 80% of participating laboratories failed to accurately determine uranium isotopes in soil samples in the U.S Department of Energy Mixed Analyte Performance Evaluation Program (MAPEP) Session 30, due to incomplete dissolution of refractory particles in the samples. Failing laboratories employed acid dissolution methods, including hydrofluoric acid, to recover uranium from the soil matrix. The failures illustrate the importance of rugged soil dissolution methods for the accurate measurement of analytes in the sample matrix. A new rapid fusion method has been developed by the Savannah River National Laboratory (SRNL) to prepare 1-2 g soil sample aliquots very quickly, withmore » total dissolution of refractory particles. Soil samples are fused with sodium hydroxide at 600 ºC in zirconium crucibles to enable complete dissolution of the sample. Uranium and thorium are separated on stacked TEVA and TRU extraction chromatographic resin cartridges, prior to isotopic measurements by alpha spectrometry on cerium fluoride microprecipitation sources. Plutonium can also be separated and measured using this method. Batches of 12 samples can be prepared for measurement in <5 hours.« less

  13. Rapid determination of lamivudine in human plasma by high-performance liquid chromatography.

    PubMed

    Alebouyeh, Mahmoud; Amini, Hossein

    2015-01-15

    A simple and rapid high-performance liquid chromatographic method with spectrophotometric detection was developed for the determination of lamivudine in human plasma. Sample preparation was accomplished through protein precipitation with acetonitrile followed by aqueous phase separation using dichloromethane. Lamivudine and the internal standard acyclovir were well separated from endogenous plasma peaks on a Chromolith RP-18e column under isocratic elution with 50 mM sodium dihydrogen phosphate-triethylamine (996:4, v/v), pH 3.2 at 20 °C. Total run time at a flow-rate of 1.5 ml/min was less than 5 min. Detection was made at 278 nm. The method was specific and sensitive, with a lower quantification limit of 40 ng/ml and a detection limit of 10 ng/ml. The absolute recovery was 97.7%, while the within- and between-day coefficient of variation and percent error values of the assay method were all less than 7%. The linearity was assessed in the range of 40-2560 in plasma, with a correlation coefficient of greater than 0.999. The method was successfully applied to a bioequivalence study in healthy volunteers.

  14. Rapid determination of nine barbiturates in human whole blood by liquid chromatography-tandem mass spectrometry.

    PubMed

    Zhang, Xinyu; Lin, Zebin; Li, Jiaolun; Huang, Zhibin; Rao, Yulan; Liang, Hao; Yan, Jie; Zheng, Feng

    2017-04-01

    A rapid, simple and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the qualitative and quantitative analysis of nine barbiturates (barbital, phenobarbital, pentobarbital, amobarbital, secobarbital, thiopental, butalbital, butabarbital, and hexobarbital) in human whole blood. Barbiturates were extracted from 100 μL of human whole blood samples using a simple liquid-liquid extraction (LLE) procedure, and detected by LC-MS/MS. An UPLC C18 (2.1 mm × 100 mm, 1.7 µm) column was used at 40 °C for the separation and acetonitrile/water system was used as the mobile phase with gradient elution. This method showed excellent accuracy (86-111%) and precision (relative standard deviation <15%). The limits of detection (LODs) were 0.2 ng/mL for barbital and secobarbital and 0.5 ng/mL for the other barbiturates. The linearity ranged from 2 ng/mL to 2000 ng/mL, with r(2)  > 0.99 over the range. This method achieved the separation and detection of pentobarbital and amobarbital at the same time in a convenient way. Moreover, it was both simple and sensitive for the determination of nine most commonly used barbiturate drugs, which was meaningful in the field of clinical and forensic toxicology. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  15. Rapid determination of carboxyhemoglobin by absorbance difference between double wave length.

    PubMed

    Sakata, M; Haga, M

    1980-05-01

    A spectrophotometric determination of CO-Hb content was investigated on the basis of double wavelength spectrophotometry. Absorbance differences at the two wavelengths at which O2-Hb has the same absorbance reflect only the CO-Hb component because the O2-Hb component is nulled out from the mixture of O2-Hb and CO-Hb. After measurement of absorbance difference, the measuring solution was saturated with pure CO and remeasured. CO-Hb % was calculated from the ratio of the absorbance differences. Since temperature significantly influences the spectrum of hemoglobin pigment, the wavelength pair changed with temperature. For accurate measurement, it was necessary to control temperature of diluting solution before dilution. Liberation of CO fro CO-Hb was observed at more than 80% CO-Hb, and 5% and 2% liberation from 100% CO-Hb occured at 100-fold dilution with 10 mm cuvette and 20-fold dilution with 2 mm cuvette respectively. Advantages of this method are that the standard curve or equation for calculation and accurate dilution are not necessary because the interfering component is nulled out and 100% CO-Hb of the standard sample is made with the same sample; and measurement is very rapid, taking less than 2 min.

  16. Final Progress Report: Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes Feasibility Study

    SciTech Connect

    Rawool-Sullivan, Mohini; Bounds, John Alan; Brumby, Steven P.; Prasad, Lakshman; Sullivan, John P.

    2012-04-30

    This is the final report of the project titled, 'Isotope Identification Algorithm for Rapid and Accurate Determination of Radioisotopes,' PMIS project number LA10-HUMANID-PD03. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). It summarizes work performed over the FY10 time period. The goal of the work was to demonstrate principles of emulating a human analysis approach towards the data collected using radiation isotope identification devices (RIIDs). Human analysts begin analyzing a spectrum based on features in the spectrum - lines and shapes that are present in a given spectrum. The proposed work was to carry out a feasibility study that will pick out all gamma ray peaks and other features such as Compton edges, bremsstrahlung, presence/absence of shielding and presence of neutrons and escape peaks. Ultimately success of this feasibility study will allow us to collectively explain identified features and form a realistic scenario that produced a given spectrum in the future. We wanted to develop and demonstrate machine learning algorithms that will qualitatively enhance the automated identification capabilities of portable radiological sensors that are currently being used in the field.

  17. Rapid determination of carbohydrates in heroin drug seizures using capillary electrophoresis with short-end injection.

    PubMed

    Anastos, Nicole; Barnett, Neil W; Lewis, Simon W; Pearson, James R; Kirkbride, K Paul

    2005-09-01

    A simple and rapid method for the analysis of carbohydrates in heroin samples by capillary electrophoresis utilizing a borate complexation method is described. Separations were performed using an uncoated fused silica capillary, 50 cm x 50 micro I.D. x 360 microm O.D. with an effective separation length of 9 cm. The system was run at 60 degrees C with an applied voltage of -8 kilovolts. Injection of each sample was for 1 sec at -50 mbar. UV detection was employed with the wavelength set at 195 nm. The background electrolyte consisted of 65 mM borate, pH 12.0. Samples and standards were prepared in the run buffer containing 2 mg/mL of mannose as an internal standard. Under these conditions a test mixture containing glucose, sucrose, lactose, mannitol and mannose as an internal standard was resolved within 5 min. The method was used to determine the concentration of carbohydrates in heroin seizure samples and synthetic heroin samples. The results were in good agreement with the reported values.

  18. Validated flow-injection method for rapid aluminium determination in anti-perspirants.

    PubMed

    López-Gonzálvez, A; Ruiz, M A; Barbas, C

    2008-09-29

    A flow-injection (FI) method for the rapid determination of aluminium in anti-perspirants has been developed. The method is based on the spectrophotometric detection at 535nm of the complex formed between Al ions and the chromogenic reagent eriochrome cyanine R. Both the batch and FI methods were validated by checking the parameters included in the ISO-3543-1 regulation. Variables involved in the FI method were optimized by using appropriate statistical tools. The method does not exhibit interference from other substances present in anti-perspirants and it shows a high precision with a R.S.D. value (n=6) of 0.9%. Moreover, the accuracy of the method was evaluated by comparison with a back complexometric titration method, which is currently used for routine analysis in pharmaceutical laboratories. The Student's t-test showed that the results obtained by both methods were not significantly different for a significance level of 95%. A response time of 12s and a sample analysis time, by performing triplicate injections, of 60s were achieved. The analytical figures of merit make the method highly appropriate to substitute the time-consuming complexometric method for this kind of analysis.

  19. Development of a rapid qualitative assay for determining elevated antibody levels to periodontopathic organisms.

    PubMed

    Mealey, B L; Ebersole, J L

    1991-05-01

    To allow more widespread use of systemic antibody analysis in clinical settings, a rapid test for determining elevated antibody to periodontitis-associated bacteria was developed. The technique utilizes dot-immunoblotting (DIB) on nitrocellulose paper with whole formalinized Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia. An ELISA was used to compare IgG antibody levels to these organisms in venous serum and peripheral capillary blood from 44 subjects. Correlation between serum and capillary levels ranged from r = 0.760 to 0.900 (P less than 0.00001). Capillary blood antibody levels averaged 55% of those detected in serum. The assay was developed using a variety of antigen and reagent concentrations and multiple chromogenic enzyme-substrate systems. Subsequently, 34 periodontally diseased and 10 periodontally healthy subjects were analyzed for serum IgG antibodies using a quantitative ELISA. The qualitative DIB was performed using capillary blood obtained by digi-puncture and results were compared in a blind fashion to the ELISA data. Relative to its ability to detect elevated antibody levels to these 3 organisms, the DIB had an overall sensitivity of 93% and a specificity of 87% (P less than 0.000001). Using peripheral capillary blood and the DIB, detection of elevated systemic antibody levels can be performed in approximately 2 hours. The DIB may be a useful aid in assessing the host response to putative periodontopathic microorganisms.

  20. SIS Mixer Design for a Broadband Millimeter Spectrometer Suitable for Rapid Line Surveys and Redshift Determinations

    NASA Technical Reports Server (NTRS)

    Rice, F.; Sumner, M.; Zmuidzinas, J.; Hu, R.; LeDuc, H.; Harris, A.; Miller, D.

    2004-01-01

    We present some detail of the waveguide probe and SIS mixer chip designs for a low-noise 180-300 GHz double- sideband receiver with an instantaneous RF bandwidth of 24 GHz. The receiver's single SIS junction is excited by a broadband, fixed-tuned waveguide probe on a silicon substrate. The IF output is coupled to a 6-18 GHz MMIC low- noise preamplifier. Following further amplification, the output is processed by an array of 4 GHz, 128-channel analog autocorrelation spectrometers (WASP 11). The single-sideband receiver noise temperature goal of 70 Kelvin will provide a prototype instrument capable of rapid line surveys and of relatively efficient carbon monoxide (CO) emission line searches of distant, dusty galaxies. The latter application's goal is to determine redshifts by measuring the frequencies of CO line emissions from the star-forming regions dominating the submillimeter brightness of these galaxies. Construction of the receiver has begun; lab testing should begin in the fall. Demonstration of the receiver on the Caltech Submillimeter Observatory (CSO) telescope should begin in spring 2003.

  1. Whole-exome sequencing enables rapid determination of xeroderma pigmentosum molecular etiology.

    PubMed

    Ortega-Recalde, Oscar; Vergara, Jéssica Inés; Fonseca, Dora Janeth; Ríos, Xiomara; Mosquera, Hernando; Bermúdez, Olga María; Medina, Claudia Liliana; Vargas, Clara Inés; Pallares, Argemiro Enrique; Restrepo, Carlos Martín; Laissue, Paul

    2014-01-01

    Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder characterized by extreme sensitivity to actinic pigmentation changes in the skin and increased incidence of skin cancer. In some cases, patients are affected by neurological alterations. XP is caused by mutations in 8 distinct genes (XPA through XPG and XPV). The XP-V (variant) subtype of the disease results from mutations in a gene (XPV, also named POLH) which encodes for Polη, a member of the Y-DNA polymerase family. Although the presence and severity of skin and neurological dysfunctions differ between XP subtypes, there are overlapping clinical features among subtypes such that the sub-type cannot be deduced from the clinical features. In this study, in order to overcome this drawback, we undertook whole-exome sequencing in two XP sibs and their father. We identified a novel homozygous nonsense mutation (c.897T>G, p.Y299X) in POLH which causes the disease. Our results demonstrate that next generation sequencing is a powerful approach to rapid determination of XP genetic etiology.

  2. Reversed phase-HPLC for rapid determination of polyphenols in flowers of rose species.

    PubMed

    Kumar, Neeraj; Bhandari, Pamita; Singh, Bikram; Gupta, Ajai P; Kaul, Vijay K

    2008-02-01

    A rapid, simple, sensitive, robust, and improved HPLC method was developed and validated for determination of 10 polyphenols, namely gallic acid, catechin, epicatechin, rutin, m-coumaric acid, quercitrin, myricetin, quercetin, apigenin, and kaempferol in fresh flowers of Rosa bourboniana and R. brunonii and in both fresh flowers and marc (left after industrial distillation of rose oil) of R. damascena. Six polyphenols, gallic acid, rutin, quercitrin, myricetin, quercetin, and kaempferol, were detected and quantified in all extracts. The chromatographic separation of 10 polyphenols was achieved in less than 16 min by RP-HPLC (Phenomenex, Luna C18 (2) column, 5 microm, 250 mm x 4.6 mm) using linear gradient elution of water and acetonitrile (0.02% trifluroacetic acid) with a flow rate of 1 mL/min at lambda 280 nm. Standard calibration curves were linear in the range of 0.39-500 microg/mL. Good results were achieved with respect to repeatability (RSD <3%) and recovery (98.6-100.8%). The method was validated for linearity, accuracy, repeatability, LOD, and LOQ.

  3. Experimental results for the rapid determination of the freezing point of fuels

    NASA Technical Reports Server (NTRS)

    Mathiprakasam, B.

    1984-01-01

    Two methods for the rapid determination of the freezing point of fuels were investigated: an optical method, which detected the change in light transmission from the disappearance of solid particles in the melted fuel; and a differential thermal analysis (DTA) method, which sensed the latent heat of fusion. A laboratory apparatus was fabricated to test the two methods. Cooling was done by thermoelectric modules using an ice-water bath as a heat sink. The DTA method was later modified to eliminate the reference fuel. The data from the sample were digitized and a point of inflection, which corresponds to the ASTM D-2386 freezing point (final melting point), was identified from the derivative. The apparatus was modifified to cool the fuel to -60 C and controls were added for maintaining constant cooling rate, rewarming rate, and hold time at minimum temperature. A parametric series of tests were run for twelve fuels with freezing points from -10 C to -50 C, varying cooling rate, rewarming rate, and hold time. Based on the results, an optimum test procedure was established. The results showed good agreement with ASTM D-2386 freezing point and differential scanning calorimetry results.

  4. Rapid determination of total aflatoxins and ochratoxins A in meat products by immuno-affinity fluorimetry.

    PubMed

    Abd-Elghany, Samir Mohammed; Sallam, Khalid Ibrahim

    2015-07-15

    Total aflatoxins (AFT) and ochratoxin A (OTA) levels were estimated using the VICAM AflaTest and OchraTest immunoaffinity fluorometric method in a total of 50 meat products (25 each of beef luncheon and beef burger) purchased from different supermarkets in Mansoura city, Egypt. All the meat samples analyzed were contaminated with both AFT and OTA with mean values of 1.1 μg/kg and 5.23 μg/kg, respectively, for beef luncheon and mean values of 3.22 μg/kg and 4.55 μg/kg, respectively, for beef burger. None of the beef luncheon and burger samples analyzed exceeded the permissible limits set by FDA for AFT, but 40% of beef burgers exceeded the FAO AFT permissible limit. Similarly, 52% and 36% of beef luncheon and beef burger samples exceeded the FAO OTA permissible limit. Application of the immunoaffinity fluorometric method is an accurate, safe and rapid method for mycotoxins determination in meat products to ensure their safety for human consumption.

  5. Highly-sensitive and rapid determination of sunset yellow using functionalized montmorillonite-modified electrode.

    PubMed

    Songyang, Yiyan; Yang, Xiaoqing; Xie, Shunlan; Hao, Haohua; Song, Jinchun

    2015-04-15

    Montmorillonite calcium (MMT-Ca) was functionalized with cetyltrimethylammonium bromide (CTAB) via cationic exchange effects. Compared with MMT-Ca, the resulting CTAB functionalized MMT-Ca (CTAB/MMT-Ca) greatly increased the oxidation peak current of sunset yellow, indicative of strong signal enhancement effects. The oxidation mechanism was studied, and one electron was transferred during the oxidation of sunset yellow. The influences of pH value, mass ratio of CTAB to MMT-Ca, amount of CTAB/MMT-Ca, and accumulation time were studied on the oxidation signal of sunset yellow. As a result, a highly-sensitive, rapid and simple electrochemical method was newly developed for the determination of sunset yellow. The linear ranger was from 2.5 to 200 nM, and the detection limit was as low as 0.71 nM after 1-min accumulation. This method was applied in soft drink samples, and the detected results consisted with the values that obtained by high-performance liquid chromatography. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. The Calgary Biofilm Device: New Technology for Rapid Determination of Antibiotic Susceptibilities of Bacterial Biofilms

    PubMed Central

    Ceri, H.; Olson, M. E.; Stremick, C.; Read, R. R.; Morck, D.; Buret, A.

    1999-01-01

    Determination of the MIC, based on the activities of antibiotics against planktonic bacteria, is the standard assay for antibiotic susceptibility testing. Adherent bacterial populations (biofilms) present with an innate lack of antibiotic susceptibility not seen in the same bacteria grown as planktonic populations. The Calgary Biofilm Device (CBD) is described as a new technology for the rapid and reproducible assay of biofilm susceptibilities to antibiotics. The CBD produces 96 equivalent biofilms for the assay of antibiotic susceptibilities by the standard 96-well technology. Biofilm formation was followed by quantitative microbiology and scanning electron microscopy. Susceptibility to a standard group of antibiotics was determined for National Committee for Clinical Laboratory Standards (NCCLS) reference strains: Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Staphylococcus aureus ATCC 29213. Growth curves demonstrated that biofilms of a predetermined size could be formed on the CBD at specific time points and, furthermore, that no significant difference (P > 0.1) was seen between biofilms formed on each of the 96 pegs. The antibiotic susceptibilities for planktonic populations obtained by the NCCLS method or from the CBD were similar. Minimal biofilm eradication concentrations, derived by using the CBD, demonstrated that for biofilms of the same organisms, 100 to 1,000 times the concentration of a certain antibiotic were often required for the antibiotic to be effective, while other antibiotics were found to be effective at the MICs. The CBD offers a new technology for the rational selection of antibiotics effective against microbial biofilms and for the screening of new effective antibiotic compounds. PMID:10325322

  7. Directing the self-assembly of block copolymers into a metastable complex network phase via a deep and rapid quench.

    PubMed

    Müller, Marcus; Sun, De-Wen

    2013-12-27

    The free-energy landscape of self-assembling block copolymer systems is characterized by a multitude of metastable minima. Using particle-based simulations of a soft, coarse-grained model, we explore opportunities to reproducibly direct the spontaneous ordering of these self-assembling systems into a metastable complex network morphology--specifically, Schoen's I-WP periodic minimal surface--starting from a highly unstable state that is generated by a rapid expansion. This process-directed self-assembly provides an alternative to fine-tuning molecular architecture or blending for fabricating complex network structures. Comparing our particle-based simulation results to recently developed free-energy techniques, we critically assess their ability to predict spontaneous formation and highlight the importance of nonequilibrium molecular conformations in the starting state and the local conservation of density.

  8. Rapid and high-throughput determination of endogenous cytokinins in Oryza sativa by bare Fe3O4 nanoparticles-based magnetic solid-phase extraction.

    PubMed

    Cai, Bao-Dong; Zhu, Jiu-Xia; Gao, Qiang; Luo, Dan; Yuan, Bi-Feng; Feng, Yu-Qi

    2014-05-02

    A rapid method was developed for determination of endogenous cytokinins (CKs) based on magnetic solid-phase extraction (MSPE) followed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). We illustrated the hydrophilic character of bare Fe3O4 nanoparticles that were directly used as a MSPE sorbent for rapid enrichment of endogenous CKs from complex plant extract. To the best of our knowledge, this is the first report of bare Fe3O4 directly used as efficient extraction sorbent to enrich target CKs based on hydrophilic interaction. Under the optimized conditions, a rapid, sensitive and high-throughput method for the determination of 16 CKs was established by combination of MSPE with UPLC-MS/MS. Good linearity was obtained with correlation coefficients (r) from 0.9902 to 0.9998. The limits of detection (LODs) and quantification (LOQs) ranged from 1.2 pg mL(-1) to 391.3 pg mL(-1) and 4.1 pg mL(-1) to 1304.3 pg mL(-1), respectively. 16 CKs could be successfully determined in spiked sample with 80.6-117.3% recoveries and the relative standard deviations (RSDs) were less than 16.6%. Finally, 10 endogenous CKs were successfully quantified in 50mg Oryza sativa sample using the developed MSPE-UPLC-MS/MS method. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. A rapid direct solvent extraction method for the extraction of 2-dodecylcyclobutanone from irradiated ground beef patties using acetonitrile.

    PubMed

    Hijaz, Faraj; Kumar, Amit; Smith, J Scott

    2010-08-01

    The amount of irradiated beef in the U.S. market is growing, and a reliable, rapid method is needed to detect irradiated beef and quantify the irradiation dose. The official analytical method (BS EN 1785 2003) that has been adopted by the European Union is time consuming. The objective of this study was to develop a rapid method for the analysis of 2-dodecylcyclobutanone (2-DCB) in irradiated beef. A 5 g sample of commercially irradiated ground beef patty (90/10) was extracted with n-hexane using a Soxhlet apparatus or with acetonitrile via direct solvent extraction. The Soxhlet hexane extract was evaporated to dryness, and the sample was dissolved in a mixture of ethyl acetate and acetonitrile (1:1). The defatted extract was purified with a 1 g silica cartridge. Another 5 g aliquot of the same patty was mixed with 50 mL acetonitrile and either blended for 1 min with a hand blender or crushed for 10 min with a glass rod. The extraction procedure was repeated 3 times, and the acetonitrile was collected and evaporated to dryness. Eluants from both methods were concentrated under nitrogen and injected into a gas chromatography-mass spectrometry. The 2-DCB concentration in the commercial samples was 0.031 +/- 0.0026 ppm (n = 5) for the Soxhlet method and 0.031 +/- 0.0025 ppm (n = 10) for direct solvent extraction. Recovery of 2-DCB from spiked beef samples in the direct solvent extraction method was 93.2 +/- 9.0% (n = 7). This study showed that the direct solvent extraction method is simple and as efficient and reproducible as the Soxhlet method.

  10. Direct Microscopic And Microholographic Observations Of The Solidification Of Particles From Rapidly Stirred Melts

    NASA Astrophysics Data System (ADS)

    Smeulders, R. J.; Mischgofsky, F. H.; Frankena, H. J.

    1983-06-01

    A microscopic set-up to observe fast moving solidifying particles during stir casting is described. The set-up consists of a Ruby laser and a frequency doubled Nd3+:YAG laser, a model device of an actual stir casting apparatus filled with a transparent organic alloy, melting at a low temperature and three different recording systems. Using a neopentyl alcohol alloy as a model substance for metal alloys, the crystallization process is studied by direct observation. Pulses from both lasers are used to provide a sufficiently short exposure time to take (simultaneously) holograms, microphotographs and videorecordings of the fast moving (flow rates up to 10 ms-1) small particles with sizes in the order of 10-103 μm. Primarily solidified particles appear to have equiaxed dendritic shapes. The longest diameter of these particles attain a maximum for low stirring rates and high cooling rates. After a period of stirring, some of the dendrite tips grow and transform the particle shapes into more spherical ones. At this stage the morphology of the solidified particles shows a good similarity with stir casted metal alloys.

  11. Rapid Leptospira identification by direct sequencing of the diagnostic PCR products in New Caledonia

    PubMed Central

    2010-01-01

    Background Most of the current knowledge of leptospirosis epidemiology originates from serological results obtained with the reference Microscopic Agglutination Test (MAT). However, inconsistencies and weaknesses of this diagnostic technique are evident. A growing use of PCR has improved the early diagnosis of leptospirosis but a drawback is that it cannot provide information on the infecting Leptospira strain which provides important epidemiologic data. Our work is aimed at evaluating if the sequence polymorphism of diagnostic PCR products could be used to identify the infecting Leptospira strains in the New Caledonian environment. Results Both the lfb1 and secY diagnostic PCR products displayed a sequence polymorphism that could prove useful in presumptively identifying the infecting leptospire. Using both this polymorphism and MLST results with New Caledonian isolates and clinical samples, we confirmed the epidemiological relevance of the sequence-based identification of Leptospira strains. Additionally, we identified one cluster of L. interrogans that contained no reference strain and one cluster of L. borgpetersenii found only in the introduced Rusa deer Cervus timorensis russa that is its probable reservoir. Conclusions The sequence polymorphism of diagnostic PCR products proved useful in presumptively identifying the infecting Leptospira strains. This could contribute to a better understanding of leptospirosis epidemiology by providing epidemiological information that cannot be directly attained from the use of PCR as an early diagnostic test for leptospirosis. PMID:21176235

  12. Rapid prototyping of microstructures in polydimethylsiloxane (PDMS) by direct UV-lithography.

    PubMed

    Scharnweber, Tim; Truckenmüller, Roman; Schneider, Andrea M; Welle, Alexander; Reinhardt, Martina; Giselbrecht, Stefan

    2011-04-07

    Microstructuring of polydimethylsiloxane (PDMS) is a key step for many lab-on-a-chip (LOC) applications. In general, the structure is generated by casting the liquid prepolymer against a master. The production of the master in turn calls for special equipment and know how. Furthermore, a given master only allows the reproduction of the defined structure. We report on a simple, cheap and practical method to produce microstructures in already cured PDMS by direct UV-lithography followed by chemical development. Due to the available options during the lithographic process like multiple exposures, the method offers a high design flexibility granting easy access to complex and stepped structures. Furthermore, no master is needed and the use of pre-cured PDMS allows processing at ambient (light) conditions. Features down to approximately 5 µm and a depth of 10 µm can be realised. As a proof of principle, we demonstrate the feasibility of the process by applying the structures to various established soft lithography techniques.

  13. An electrochemical clamp assay for direct, rapid analysis of circulating nucleic acids in serum

    NASA Astrophysics Data System (ADS)

    Das, Jagotamoy; Ivanov, Ivaylo; Montermini, Laura; Rak, Janusz; Sargent, Edward H.; Kelley, Shana O.

    2015-07-01

    The analysis of cell-free nucleic acids (cfNAs), which are present at significant levels in the blood of cancer patients, can reveal the mutational spectrum of a tumour without the need for invasive sampling of the tissue. However, this requires differentiation between the nucleic acids that originate from healthy cells and the mutated sequences shed by tumour cells. Here we report an electrochemical clamp assay that directly detects mutated sequences in patient serum. This is the first successful detection of cfNAs without the need for enzymatic amplification, a step that normally requires extensive sample processing and is prone to interference. The new chip-based assay reads out the presence of mutations within 15 minutes using a collection of oligonucleotides that sequester closely related sequences in solution, and thus allow only the mutated sequence to bind to a chip-based sensor. We demonstrate excellent levels of sensitivity and specificity and show that the clamp assay accurately detects mutated sequences in a collection of samples taken from lung cancer and melanoma patients.

  14. Strategy for rapid identification and antibiotic susceptibility testing of gram-negative bacteria directly recovered from positive blood cultures using the Bruker MALDI Biotyper and the BD Phoenix system.

    PubMed

    Wimmer, Jana L; Long, S Wesley; Cernoch, Patricia; Land, Geoffrey A; Davis, James R; Musser, James M; Olsen, Randall J

    2012-07-01

    Decreasing the time to species identification and antibiotic susceptibility determination of strains recovered from patients with bacteremia significantly decreases morbidity and mortality. Herein, we validated a method to identify Gram-negative bacteria directly from positive blood culture medium using the Bruker MALDI Biotyper and to rapidly perform susceptibility testing using the BD Phoenix.

  15. A rapid method for determining salinomycin and monensin sensitivity in Eimeria tenella.

    PubMed

    Jenkins, M C; O'Brien, C N; Fuller, L; Mathis, G F; Fetterer, R

    2014-12-15

    Standard methods of determining the ionophore sensitivity of Eimeria rely on infecting chickens with an isolate or a mixture of Eimeria spp. oocysts in the presence of different anti-coccidial drugs. The purpose of this study was to develop a rapid in vitro method for assessing salinomycin and monensin sensitivity in Eimeria tenella. Cultures of MDBK cells were grown to 85% confluency, and then inoculated with excysted E. tenella laboratory strain (APU-1) sporozoites in the presence of different concentrations of salinomycin or monensin. At various timepoints, the monolayers were fixed for counting intraceullar sporozoites, or were subjected to DNA extraction, followed by molecular analysis using quantitative (qPCR) or semi-quantitative PCR (sqPCR). Preliminary experiments showed that 24h was the optimum time for harvesting the E. tenella-infected cell cultures. The average number of E. tenella sporozoites relative to untreated controls displayed a linear decrease between 0.3 and 33.0 μg/ml salinomycin and between 0.3 and 3.3 μg/ml monensin. A similar pattern was observed in the relative amount of E. tenella DNA as measured by sqPCR. A linear decrease in the relative amount of E. tenella DNA was observed over the entire range of salinomycin and monensin concentrations as measured by qPCR possibly reflecting the greater sensitivity of this assay. Comparison of sporozoite counting, sqPCR, and qPCR signals using a criterion of 50% inhibition in sporozoite numbers or level of PCR amplification product showed good agreement between the three assays. E. tenella field isolates (FS-1 and FS-2) displaying resistance to salinomycin and monensin were evaluated in the in vitro assay using qPCR and sqPCR. Compared to E. tenella APU-1, the E. tenella FS-1 and FS-2 isolates showed higher levels of E. tenella DNA at 24h by both qPCR and sqPCR. This in vitro assay represents a significant advance in developing rapid, cost-effective methods for assessing ionophore sensitivity in E

  16. Development of rapidly fermenting strains of Saccharomyces diastaticus for direct conversion of starch and dextrins to ethanol

    SciTech Connect

    Laluce, C.; Mattoon, J.R.

    1984-07-01

    Alcoholic fermentation, growth, and glucoamylase production by 12 strains of Saccharomyces diastaticus were compared by using starch and dextrins as substrates. Haploid progeny produced from a rapidly fermenting strain, SD2, were used for hybridization with other S. diastaticus and