A Comparative Study of Sediment Quality in Four Reservoirs.

DTIC Science & Technology

1984-02-01

same time as the reservoir samples. Precision for interstitial water samples was initially measured using soil - solution samples. As interstitial...Variable Composite Sample hean, ma&L Replicates Deviation, ma L Deviation. Ammonium nitrogen Soil solution 0.07 12 0.01 14 DeGray composite 2.00 10 0.01...0.5 Nitrate nitrite Filtered wastewater 0.04 10 0.01 25 nitrogen Soluble reactive Soil solution 0.04 12 0.01 25 phosphorus DeGray composite 0.16 10 0.01

Impact of sampling strategy on stream load estimates in till landscape of the Midwest

USGS Publications Warehouse

Vidon, P.; Hubbard, L.E.; Soyeux, E.

2009-01-01

Accurately estimating various solute loads in streams during storms is critical to accurately determine maximum daily loads for regulatory purposes. This study investigates the impact of sampling strategy on solute load estimates in streams in the US Midwest. Three different solute types (nitrate, magnesium, and dissolved organic carbon (DOC)) and three sampling strategies are assessed. Regardless of the method, the average error on nitrate loads is higher than for magnesium or DOC loads, and all three methods generally underestimate DOC loads and overestimate magnesium loads. Increasing sampling frequency only slightly improves the accuracy of solute load estimates but generally improves the precision of load calculations. This type of investigation is critical for water management and environmental assessment so error on solute load calculations can be taken into account by landscape managers, and sampling strategies optimized as a function of monitoring objectives. ?? 2008 Springer Science+Business Media B.V.

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

Tadayyon, Ghazal; Mazinani, Mohammad; Guo, Yina

Martensitic evolution in Ti-rich NiTi alloy, Ti50.5Ni49.5, has been investigated as a function of annealing, solution treatment and a combination thereof and a detailed electron microscopic investigation carried out. Self-accommodated martensite plates resulted in all heat treated samples. Martensitic < 011 > type II twins, which are common in NiTi shape memory alloys, was found in both as-received and heat-treated samples. Solution treated samples, additionally, showed {11-1} type I twinning was also found in samples that have been annealed after solution-treatment. Another common feature of the microstructure in both as-received and heat treated samples is the formation of Ti{sub 2}Nimore » precipitates. The size, number and dispersions of these precipitates can be controlled by resorting to a suitable heat treatment e.g. solution treatment.« less

Obtaining the Bidirectional Transfer Distribution Function ofIsotropically Scattering Materials Using an Integrating Sphere

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

Jonsson, Jacob C.; Branden, Henrik

2006-10-19

This paper demonstrates a method to determine thebidirectional transfer distribution function (BTDF) using an integratingsphere. Information about the sample's angle dependent scattering isobtained by making transmittance measurements with the sample atdifferent distances from the integrating sphere. Knowledge about theilluminated area of the sample and the geometry of the sphere port incombination with the measured data combines to an system of equationsthat includes the angle dependent transmittance. The resulting system ofequations is an ill-posed problem which rarely gives a physical solution.A solvable system is obtained by using Tikhonov regularization on theill-posed problem. The solution to this system can then be usedmore » to obtainthe BTDF. Four bulk-scattering samples were characterised using both twogoniophotometers and the described method to verify the validity of thenew method. The agreement shown is great for the more diffuse samples.The solution to the low-scattering samples contains unphysicaloscillations, butstill gives the correct shape of the solution. Theorigin of the oscillations and why they are more prominent inlow-scattering samples are discussed.« less

Efficient sample preparation method based on solvent-assisted dispersive solid-phase extraction for the trace detection of butachlor in urine and waste water samples.

PubMed

Aladaghlo, Zolfaghar; Fakhari, Alireza; Behbahani, Mohammad

2016-10-01

In this work, an efficient sample preparation method termed solvent-assisted dispersive solid-phase extraction was applied. The used sample preparation method was based on the dispersion of the sorbent (benzophenone) into the aqueous sample to maximize the interaction surface. In this approach, the dispersion of the sorbent at a very low milligram level was achieved by inserting a solution of the sorbent and disperser solvent into the aqueous sample. The cloudy solution created from the dispersion of the sorbent in the bulk aqueous sample. After pre-concentration of the butachlor, the cloudy solution was centrifuged and butachlor in the sediment phase dissolved in ethanol and determined by gas chromatography with flame ionization detection. Under the optimized conditions (solution pH = 7.0, sorbent: benzophenone, 2%, disperser solvent: ethanol, 500 μL, centrifuged at 4000 rpm for 3 min), the method detection limit for butachlor was 2, 3 and 3 μg/L for distilled water, waste water, and urine sample, respectively. Furthermore, the preconcentration factor was 198.8, 175.0, and 174.2 in distilled water, waste water, and urine sample, respectively. Solvent-assisted dispersive solid-phase extraction was successfully used for the trace monitoring of butachlor in urine and waste water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ISSUES RELATED TO SOLUTION CHEMISTRY IN MERCURY SAMPLING IMPINGERS

EPA Science Inventory

Analysis of mercury (Hg) speciation in combustion flue gases is often accomplished in standardized sampling trains in which the sample is passed sequentially through a series of aqueous solutions to capture and separate oxidized Hg (Hg2+) and elemental Hg (Hgo). Such methods incl...

Systems and methods for laser assisted sample transfer to solution for chemical analysis

DOEpatents

Van Berkel, Gary J.; Kertesz, Vilmos; Ovchinnikova, Olga S.

2014-06-03

Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

Systems and methods for laser assisted sample transfer to solution for chemical analysis

DOEpatents

Van Berkel, Gary J.; Kertesz, Vilmos; Ovchinnikova, Olga S.

2015-09-29

Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

Systems and methods for laser assisted sample transfer to solution for chemical analysis

DOEpatents

Van Berkel, Gary J; Kertesz, Vilmos; Ovchinnikova, Olga S

2013-08-27

Systems and methods are described for laser ablation of an analyte from a specimen and capturing of the analyte in a dispensed solvent to form a testing solution. A solvent dispensing and extraction system can form a liquid microjunction with the specimen. The solvent dispensing and extraction system can include a surface sampling probe. The laser beam can be directed through the surface sampling probe. The surface sampling probe can also serve as an atomic force microscopy probe. The surface sampling probe can form a seal with the specimen. The testing solution including the analyte can then be analyzed using an analytical instrument or undergo further processing.

[Study of methods of decalcification for making united slices of tooth and affiliated periodontic tissues].

PubMed

Wang, Yu; Mu, Ya-bing; Miao, Lei-ying; Sun, Hong-chen; Li, Cheng-ku

2007-03-01

To study the methods of decalcification for making united slices of tooth and affiliated periodontic tissues. Twenty-one samples containing dog molars and affiliated periodontic tissues were divided into seven mean groups. The pH value of solution, time of decalcification, weight and volume of samples, and content of decalcified calcium were detected. The slices were observed by HE, specific, and immunohistochemical stain. The velocity of decalcification increased with decrease of solution pH. The weight of samples lightened by 37.61%, the volume reduced by 25.97% on average, and calcium decalcified was 174.49 mg per gram humid samples. The EDTA decalcification was slowest, but it was best. Decalcification was fast in Plank-Rycho solution while the section was worst, and faster in the formyl solution containing aluminium chloride than in EDTA, and the section was better. The 50% formyl solution containing aluminium chloride is an ideal decalcifying solution.

Trace element analysis of extraterrestrial metal samples by inductively coupled plasma mass spectrometry: the standard solutions and digesting acids.

PubMed

Wang, Guiqin; Wu, Yangsiqian; Lin, Yangting

2016-02-28

Nearly 99% of the total content of extraterrestrial metals is composed of Fe and Ni, but with greatly variable trace element contents. The accuracy obtained in the inductively coupled plasma mass spectrometry (ICP-MS) analysis of solutions of these samples can be significantly influenced by matrix contents, polyatomic ion interference, and the concentrations of external standard solutions. An ICP-MS instrument (X Series 2) was used to determine 30 standard solutions with different concentrations of trace elements, and different matrix contents. Based on these measurements, the matrix effects were determined. Three iron meteorites were dissolved separately in aqua regia and HNO3. Deviations due to variation of matrix contents in the external standard solutions were evaluated and the analysis results of the two digestion methods for iron meteorites were assessed. Our results show obvious deviations due to unmatched matrix contents in the external standard solutions. Furthermore, discrepancy in the measurement of some elements was found between the sample solutions prepared with aqua regia and HNO3, due to loss of chloride during sample preparation and/or incomplete digestion of highly siderophile elements in iron meteorites. An accurate ICP-MS analysis method for extraterrestrial metal samples has been established using external standard solutions with matched matrix contents and digesting the samples with HNO3 and aqua regia. Using the data from this work, the Mundrabilla iron meteorite previously classified as IAB-ung is reclassified as IAB-MG. Copyright © 2016 John Wiley & Sons, Ltd.

Quantitative method of determining beryllium or a compound thereof in a sample

DOEpatents

McCleskey, T. Mark; Ehler, Deborah S.; John, Kevin D.; Burrell, Anthony K.; Collis, Gavin E.; Minogue, Edel M.; Warner, Benjamin P.

2006-10-31

A method of determining beryllium or a beryllium compound thereof in a sample, includes providing a sample suspected of comprising beryllium or a compound thereof, extracting beryllium or a compound thereof from the sample by dissolving in a solution, adding a fluorescent indicator to the solution to thereby bind any beryllium or a compound thereof to the fluorescent indicator, and determining the presence or amount of any beryllium or a compound thereof in the sample by measuring fluorescence.

Quantitative method of determining beryllium or a compound thereof in a sample

DOEpatents

McCleskey, T. Mark; Ehler, Deborah S.; John, Kevin D.; Burrell, Anthony K.; Collis, Gavin E.; Minogue, Edel M.; Warner, Benjamin P.

2010-08-24

A method of determining beryllium or a beryllium compound thereof in a sample, includes providing a sample suspected of comprising beryllium or a compound thereof, extracting beryllium or a compound thereof from the sample by dissolving in a solution, adding a fluorescent indicator to the solution to thereby bind any beryllium or a compound thereof to the fluorescent indicator, and determining the presence or amount of any beryllium or a compound thereof in the sample by measuring fluorescence.

Towards high concentration enhancement of microfluidic temperature gradient focusing of sample solutes using combined AC and DC field induced Joule heating.

PubMed

Ge, Zhengwei; Wang, Wei; Yang, Chun

2011-04-07

It is challenging to continuously concentrate sample solutes in microfluidic channels. We present an improved electrokinetic technique for enhancing microfluidic temperature gradient focusing (TGF) of sample solutes using combined AC and DC field induced Joule heating effects. The introduction of an AC electric field component services dual functions: one is to produce Joule heat for generating temperature gradient; the other is to suppress electroosmotic flow. Consequently the required DC voltages for achieving sample concentration by Joule heating induced TGF are reduced, thereby leading to smaller electroosmotic flow (EOF) and thus backpressure effects. As a demonstration, the proposed technique can lead to concentration enhancement of sample solutes of more than 2500-fold, which is much higher than the existing literature reported microfluidic concentration enhancement by utilizing the Joule heating induced TGF technique.

Aerosol dilution as a simple strategy for analysis of complex samples by ICP-MS.

PubMed

Barros, Ariane I; Pinheiro, Fernanda C; Amaral, Clarice D B; Lorençatto, Rodolfo; Nóbrega, Joaquim A

2018-02-01

This study investigated the capability of High Matrix Introduction (HMI) strategy for analysis of dialysis solution and urine samples using inductively coupled plasma mass spectrometry. The use of HMI enables the direct introduction of urine samples and dialysis solutions 2-fold diluted with 0.14molL -1 HNO 3 . Bismuth, Ge, Ir, Li, Pt, Rh, Sc and Tl were evaluated as internal standards for Al, Ag, As, Be, Cd, Cr, Pb, Sb, Se, Tl, and Hg determination in dialysis solution and As, Cd, Hg and Pb determination in urine samples. Helium collision cell mode (4.5mLmin -1 ) was efficient to overcome polyatomic interferences in As, Se and Cr determinations. Mercury memory effects were evaluated by washing with 0.12molL -1 HCl or an alkaline diluent solution prepared with n-butanol, NH 4 OH, EDTA, and Triton X-100. This later solution was efficient for avoiding Hg memory effects in 6h of analysis. Linear calibration curves were obtained for all analytes and detection limits were lower than maximum amounts allowed by Brazilian legislations. Recoveries for all analytes in dialysis solutions and urine samples ranged from 82% to 125% and relative standard deviations for all elements and samples were lower than 7%. Analysis of control internal urine samples was in agreement with certified values at 95% confidence level (t-test; p < 0.05). Copyright © 2017 Elsevier B.V. All rights reserved.

Accelerating Convergence in Molecular Dynamics Simulations of Solutes in Lipid Membranes by Conducting a Random Walk along the Bilayer Normal.

PubMed

Neale, Chris; Madill, Chris; Rauscher, Sarah; Pomès, Régis

2013-08-13

All molecular dynamics simulations are susceptible to sampling errors, which degrade the accuracy and precision of observed values. The statistical convergence of simulations containing atomistic lipid bilayers is limited by the slow relaxation of the lipid phase, which can exceed hundreds of nanoseconds. These long conformational autocorrelation times are exacerbated in the presence of charged solutes, which can induce significant distortions of the bilayer structure. Such long relaxation times represent hidden barriers that induce systematic sampling errors in simulations of solute insertion. To identify optimal methods for enhancing sampling efficiency, we quantitatively evaluate convergence rates using generalized ensemble sampling algorithms in calculations of the potential of mean force for the insertion of the ionic side chain analog of arginine in a lipid bilayer. Umbrella sampling (US) is used to restrain solute insertion depth along the bilayer normal, the order parameter commonly used in simulations of molecular solutes in lipid bilayers. When US simulations are modified to conduct random walks along the bilayer normal using a Hamiltonian exchange algorithm, systematic sampling errors are eliminated more rapidly and the rate of statistical convergence of the standard free energy of binding of the solute to the lipid bilayer is increased 3-fold. We compute the ratio of the replica flux transmitted across a defined region of the order parameter to the replica flux that entered that region in Hamiltonian exchange simulations. We show that this quantity, the transmission factor, identifies sampling barriers in degrees of freedom orthogonal to the order parameter. The transmission factor is used to estimate the depth-dependent conformational autocorrelation times of the simulation system, some of which exceed the simulation time, and thereby identify solute insertion depths that are prone to systematic sampling errors and estimate the lower bound of the amount of sampling that is required to resolve these sampling errors. Finally, we extend our simulations and verify that the conformational autocorrelation times estimated by the transmission factor accurately predict correlation times that exceed the simulation time scale-something that, to our knowledge, has never before been achieved.

Freeze chromatography method and apparatus

DOEpatents

Scott, C.D.

1987-04-16

A freeze chromatography method and apparatus are provided which enable separation of the solutes contained in a sample. The apparatus includes an annular column construction comprising cylindrical inner and outer surfaces defining an annular passage therebetween. One of the surfaces is heated and the other cooled while passing an eluent through the annular passageway so that the eluent in contact with the cooled surface freezes and forms a frozen eluent layer thereon. A mixture of solutes dissolved in eluent is passed through the annular passageway in contact with the frozen layer so that the sample solutes in the mixture will tend to migrate either toward or away the frozen layer. The rate at which the mixture flows through the annular passageway is controlled so that the distribution of the sample solutes approaches that at equilibrium and thus a separation between the sample solutes occurs. 3 figs.

Sonication standard laboratory module

DOEpatents

Beugelsdijk, Tony; Hollen, Robert M.; Erkkila, Tracy H.; Bronisz, Lawrence E.; Roybal, Jeffrey E.; Clark, Michael Leon

1999-01-01

A standard laboratory module for automatically producing a solution of cominants from a soil sample. A sonication tip agitates a solution containing the soil sample in a beaker while a stepper motor rotates the sample. An aspirator tube, connected to a vacuum, draws the upper layer of solution from the beaker through a filter and into another beaker. This beaker can thereafter be removed for analysis of the solution. The standard laboratory module encloses an embedded controller providing process control, status feedback information and maintenance procedures for the equipment and operations within the standard laboratory module.

Trace elemental analysis of glass and paint samples of forensic interest by ICP-MS using laser ablation solid sample introduction

NASA Astrophysics Data System (ADS)

Almirall, Jose R.; Trejos, Tatiana; Hobbs, Andria; Furton, Kenneth G.

2003-09-01

The importance of small amounts of glass and paint evidence as a means to associate a crime event to a suspect or a suspect to another individual has been demonstrated in many cases. Glass is a fragile material that is often found at the scenes of crimes such as burglaries, hit-and-run accidents and violent crime offenses. Previous work has demonstrated the utility of elemental analysis by solution ICP-MS of small amounts of glass for the comparison between a fragment found at a crime scene to a possible source of the glass. The multi-element capability and the sensitivity of ICP-MS combined with the simplified sample introduction of laser ablation prior to ion detection provides for an excellent and relatively non-destructive technique for elemental analysis of glass fragments. The direct solid sample introduction technique of laser ablation (LA) is reported as an alternative to the solution method. Direct solid sampling provides several advantages over solution methods and shows great potential for a number of solid sample analyses in forensic science. The advantages of laser ablation include the simplification of sample preparation, thereby reducing the time and complexity of the analysis, the elimination of handling acid dissolution reagents such as HF and the reduction of sources of interferences in the ionization plasma. Direct sampling also provides for essentially "non-destructive" sampling due to the removal of very small amounts of sample needed for analysis. The discrimination potential of LA-ICP-MS is compared with previously reported solution ICP-MS methods using external calibration with internal standardization and a newly reported solution isotope dilution (ID) method. A total of ninety-one different glass samples were used for the comparison study using the techniques mentioned. One set consisted of forty-five headlamps taken from a variety of automobiles representing a range of twenty years of manufacturing dates. A second set consisted of forty-six automotive glasses (side windows and windshields) representing casework glass from different vehicle manufacturers over several years was also characterized by RI and elemental composition analysis. The solution sample introduction techniques (external calibration and isotope dilution) provide for excellent sensitivity and precision but have the disadvantages of destroying the sample and also involve complex sample preparation. The laser ablation method was simpler, faster and produced comparable discrimination to the EC-ICP-MS and ID-ICP-MS. LA-ICP-MS can provide for an excellent alternative to solution analysis of glass in forensic casework samples. Paints and coatings are frequently encountered as trace evidence samples submitted to forensic science laboratories. A LA-ICP-MS method has been developed to complement the commonly used techniques in forensic laboratories in order to better characterize these samples for forensic purposes. Time-resolved plots of each sample can be compared to associate samples to each other or to discriminate between samples. Additionally, the concentration of lead and the ratios of other elements have been determined in various automotive paints by the reported method. A sample set of eighteen (18) survey automotive paint samples have been analyzed with the developed method in order to determine the utility of LA-ICP-MS and to compare the method to the more commonly used scanning electron microscopy (SEM) method for elemental characterization of paint layers in forensic casework.

Influence of ultrasound pretreatment on wood physiochemical structure.

PubMed

He, Zhengbin; Wang, Zhenyu; Zhao, Zijian; Yi, Songlin; Mu, Jun; Wang, Xiaoxu

2017-01-01

As an initial step to increase the use of renewable biomass resources, this study was aimed at investigating the effects of ultrasound pretreatment on structural changes of wood. Samples were pretreated by ultrasound with the power of 300W and frequency of 28kHz in aqueous soda solution, aqueous acetic acid, or distilled water, then pretreated and control samples were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results shown that ultrasound pretreatment is indeed effective in modifying the physiochemical structure of eucalyptus wood; the pretreatment decreased the quantity of alkali metals (e.g., potassium, calcium and magnesium) in the resulting material. Compared to the control group, the residual char content of samples pretreated in aqueous soda solution increased by 10.08%-20.12% and the reaction temperature decreased from 361°C to 341°C, however, in samples pretreated by ultrasound in acetic solution or distilled water, the residual char content decreased by 12.40%-21.45% and there were no significant differences in reactivity apart from a slightly higher maximum reaction rate. Ultrasound pretreatment increased the samples' crystallinity up to 35.5% and successfully removed cellulose, hemicellulose, and lignin from the samples; the pretreatment also increased the exposure of the sample to the treatment solutions, broke down sample pits, and generated collapses and microchannels on sample pits, and removed attachments in the samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of a novel antimicrobial coating on roast beef for inactivation and inhibition of Listeria monocytogenes during storage.

PubMed

Wang, Luxin; Zhao, Liang; Yuan, Jing; Jin, Tony Z

2015-10-15

The antilisterial efficacy of novel coating solutions made with organic acids, lauric arginate ester, and chitosan was evaluated in a three-stage study on inoculated roast beef for the first time. Ready-to-eat roast beef was specially ordered from the manufacturer. The meat surface was inoculated with five-strain Listeria monocytogenes cocktail inoculums at two different levels, ~3 and 6 Log CFU/cm(2) and treated with the stock solution (HAMS), the 1:5 diluted solution (MAMS), and the 1:10 diluted solution (LAMS) (stage 1). During the 20 min contact time, the antimicrobial coatings reduced the Listeria populations by approximately 0.9-0.3 Log CFU/cm(2). The higher the concentrations of the antimicrobial solution, the better the antilisterial effects were. The treated inoculated beef samples were then stored at 4 °C for 30 days. During storage, Listeria growth inhibition effects were seen. While no growth was seen from the HAMS-treated samples, a 1.6 Log CFU/cm(2) increase was seen for MAMS-treated samples, a 4.6 Log CFU/cm(2) increase was seen for LAMS-treated samples, and a 5.7 Log CFU/cm(2) increase was seen for NoAMS-treated samples on Day 30 (~3 Log CFU/cm(2) inoculation level). In the second stage, the impact of the roast beef storage time on solution's antilisterial effect was evaluated. Results showed that the effect of the antimicrobial solution was dependent on both the initial inoculation levels and storage times. In stage 3, the effect of the antimicrobial solution on roast beef quality was studied with both instrument measurement and sensory evaluation. Minor changes in color, pH, and water activity were found. However, only limited sensory differences were seen between the treated and untreated samples. When panels were able to accurately find color differences between samples, they preferred the treated samples. The findings of this research proved the antilisterial efficacy of the novel antimicrobial solution and showed its potential for being used as a roast beef cut surface coating to control Listeria contamination and for color protection. Copyright © 2015 Elsevier B.V. All rights reserved.

Nickel Nanocatalyst Ex-Solution from Ceria-Nickel Oxide Solid Solution for Low Temperature CO Oxidation.

PubMed

Singhania, Amit; Gupta, Shipra Mital

2018-07-01

In this work, in situ growth of Ni nanocatalysts to attach onto the ceria (CeO2) surface through direct Ni ex-solution from the NiO-CeO2 solid solution in a reducing atmosphere at high temperatures with an aim to improve the catalytic activity, and stability for low temperature carbon monoxide (CO) oxidation reaction have been reported. The NiO-CeO2 solid solutions were prepared by solution combustion method, and the results of XRD and RAMAN showed that doping of Ni increases the oxygen vacancies due to charge compensation. Ni is clearly visible in XRD and TEM of Ni ex-solved sample (R-UCe5Ni10) after reduction of NiO-CeO2 (UCe5Ni10) sample by 5% H2/Ar reduction at 1000 °C. TEM analysis revealed a size of 9.2 nm of Ni nanoparticle that is ex-solved on the surface CeO2. This ex-solved sample showed very high catalytic activity (T50 ~ 110 °C), and stability (100 h) for CO oxidation reaction as compared to prepared solid solution samples. This is due to the highly active metallic nano-phase which is ex-solved on the surface of CeO2 and strongly adherent to the support. The apparent activation energy Ni ex-solved sample is found out to be 48.4 kJ mol-1. Thus, the above Ni ex-solved sample shows a practical applicability for the CO reaction.

Influence of soil organic matter composition on the partition of organic compounds

USGS Publications Warehouse

Rutherford, D.W.; Chiou, C.T.; Klle, D.E.

1992-01-01

The sorption at room temperature of benzene and carbon tetrachloride from water on three high-organic-content soils (muck, peat, and extracted peat) and on cellulose was determined in order to evaluate the effect of sorbent polarity on the solute partition coefficients. The isotherms are highly linear for both solutes on all the organic matter samples, which is consistent with a partition model. For both solutes, the extracted peat shows the greatest sorption capacity while the cellulose shows the lowest capacity; the difference correlates with the polar-to-nonpolar group ratio [(O + N)/C] of the sorbent samples. The relative increase of solute partition coefficient (Kom) with a decrease of sample polar content is similar for both solutes, and the limiting sorption capacity on a given organic matter sample is comparable between the solutes. This observation suggests that one can estimate the polarity effect of a sample of soil organic matter (SOM) on Kom of various nonpolar solutes by determining the partition coefficient of single nonpolar solute when compositional analysis of the SOM is not available. The observed dependence of Kom on sample polarity is used to account for the variation of Kom values of individual compounds on different soils that results from change in the polar group content of SOM. On the assumption that the carbon content of SOM in "ordinary soils" is 53-63%, the calculated variation of Kom is a factor of ???3. This value is in agreement with the limit of variation of most Kom data with soils of relatively high SOM contents.

Multi-point objective-oriented sequential sampling strategy for constrained robust design

NASA Astrophysics Data System (ADS)

Zhu, Ping; Zhang, Siliang; Chen, Wei

2015-03-01

Metamodelling techniques are widely used to approximate system responses of expensive simulation models. In association with the use of metamodels, objective-oriented sequential sampling methods have been demonstrated to be effective in balancing the need for searching an optimal solution versus reducing the metamodelling uncertainty. However, existing infilling criteria are developed for deterministic problems and restricted to one sampling point in one iteration. To exploit the use of multiple samples and identify the true robust solution in fewer iterations, a multi-point objective-oriented sequential sampling strategy is proposed for constrained robust design problems. In this article, earlier development of objective-oriented sequential sampling strategy for unconstrained robust design is first extended to constrained problems. Next, a double-loop multi-point sequential sampling strategy is developed. The proposed methods are validated using two mathematical examples followed by a highly nonlinear automotive crashworthiness design example. The results show that the proposed method can mitigate the effect of both metamodelling uncertainty and design uncertainty, and identify the robust design solution more efficiently than the single-point sequential sampling approach.

Quantitative Analysis of Heavy Metals in Water Based on LIBS with an Automatic Device for Sample Preparation

NASA Astrophysics Data System (ADS)

Hu, Li; Zhao, Nanjing; Liu, Wenqing; Meng, Deshuo; Fang, Li; Wang, Yin; Yu, Yang; Ma, Mingjun

2015-08-01

Heavy metals in water can be deposited on graphite flakes, which can be used as an enrichment method for laser-induced breakdown spectroscopy (LIBS) and is studied in this paper. The graphite samples were prepared with an automatic device, which was composed of a loading and unloading module, a quantitatively adding solution module, a rapid heating and drying module and a precise rotating module. The experimental results showed that the sample preparation methods had no significant effect on sample distribution and the LIBS signal accumulated in 20 pulses was stable and repeatable. With an increasing amount of the sample solution on the graphite flake, the peak intensity at Cu I 324.75 nm accorded with the exponential function with a correlation coefficient of 0.9963 and the background intensity remained unchanged. The limit of detection (LOD) was calculated through linear fitting of the peak intensity versus the concentration. The LOD decreased rapidly with an increasing amount of sample solution until the amount exceeded 20 mL and the correlation coefficient of exponential function fitting was 0.991. The LOD of Pb, Ni, Cd, Cr and Zn after evaporating different amounts of sample solution on the graphite flakes was measured and the variation tendency of their LOD with sample solution amounts was similar to the tendency for Cu. The experimental data and conclusions could provide a reference for automatic sample preparation and heavy metal in situ detection. supported by National Natural Science Foundation of China (No. 60908018), National High Technology Research and Development Program of China (No. 2013AA065502) and Anhui Province Outstanding Youth Science Fund of China (No. 1108085J19)

Adaptive Peer Sampling with Newscast

NASA Astrophysics Data System (ADS)

Tölgyesi, Norbert; Jelasity, Márk

The peer sampling service is a middleware service that provides random samples from a large decentralized network to support gossip-based applications such as multicast, data aggregation and overlay topology management. Lightweight gossip-based implementations of the peer sampling service have been shown to provide good quality random sampling while also being extremely robust to many failure scenarios, including node churn and catastrophic failure. We identify two problems with these approaches. The first problem is related to message drop failures: if a node experiences a higher-than-average message drop rate then the probability of sampling this node in the network will decrease. The second problem is that the application layer at different nodes might request random samples at very different rates which can result in very poor random sampling especially at nodes with high request rates. We propose solutions for both problems. We focus on Newscast, a robust implementation of the peer sampling service. Our solution is based on simple extensions of the protocol and an adaptive self-control mechanism for its parameters, namely—without involving failure detectors—nodes passively monitor local protocol events using them as feedback for a local control loop for self-tuning the protocol parameters. The proposed solution is evaluated by simulation experiments.

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

PubMed Central

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

2016-01-01

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

Fully Integrated Microfluidic Device for Direct Sample-to-Answer Genetic Analysis

NASA Astrophysics Data System (ADS)

Liu, Robin H.; Grodzinski, Piotr

Integration of microfluidics technology with DNA microarrays enables building complete sample-to-answer systems that are useful in many applications such as clinic diagnostics. In this chapter, a fully integrated microfluidic device [1] that consists of microfluidic mixers, valves, pumps, channels, chambers, heaters, and a DNA microarray sensor to perform DNA analysis of complex biological sample solutions is present. This device can perform on-chip sample preparation (including magnetic bead-based cell capture, cell preconcentration and purification, and cell lysis) of complex biological sample solutions (such as whole blood), polymerase chain reaction, DNA hybridization, and electrochemical detection. A few novel microfluidic techniques were developed and employed. A micromix-ing technique based on a cavitation microstreaming principle was implemented to enhance target cell capture from whole blood samples using immunomagnetic beads. This technique was also employed to accelerate DNA hybridization reaction. Thermally actuated paraffin-based microvalves were developed to regulate flows. Electrochemical pumps and thermopneumatic pumps were integrated on the chip to provide pumping of liquid solutions. The device is completely self-contained: no external pressure sources, fluid storage, mechanical pumps, or valves are necessary for fluid manipulation, thus eliminating possible sample contamination and simplifying device operation. Pathogenic bacteria detection from ~mL whole blood samples and single-nucleotide polymorphism analysis directly from diluted blood were demonstrated. The device provides a cost-effective solution to direct sample-to-answer genetic analysis, and thus has a potential impact in the fields of point-of-care genetic analysis, environmental testing, and biological warfare agent detection.

Evaluation of a new tear osmometer for repeatability and accuracy, using 0.5-microL (500-Nanoliter) samples.

PubMed

Yildiz, Elvin H; Fan, Vincent C; Banday, Hina; Ramanathan, Lakshmi V; Bitra, Ratna K; Garry, Eileen; Asbell, Penny A

2009-07-01

To evaluate the repeatability and accuracy of a new tear osmometer that measures the osmolality of 0.5-microL (500-nanoliter) samples. Four standardized solutions were tested with 0.5-microL (500-nanoliter) samples for repeatability of measurements and comparability to standardized technique. Two known standard salt solutions (290 mOsm/kg H2O, 304 mOsm/kg H2O), a normal artificial tear matrix sample (306 mOsm/kg H2O), and an abnormal artificial tear matrix sample (336 mOsm/kg H2O) were repeatedly tested (n = 20 each) for osmolality with use of the Advanced Instruments Model 3100 Tear Osmometer (0.5-microL [500-nanoliter] sample size) and the FDA-approved Advanced Instruments Model 3D2 Clinical Osmometer (250-microL sample size). Four standard solutions were used, with osmolality values of 290, 304, 306, and 336 mOsm/kg H2O. The respective precision data, including the mean and standard deviation, were: 291.8 +/- 4.4, 305.6 +/- 2.4, 305.1 +/- 2.3, and 336.4 +/- 2.2 mOsm/kg H2O. The percent recoveries for the 290 mOsm/kg H2O standard solution, the 304 mOsm/kg H2O reference solution, the normal value-assigned 306 mOsm/kg H2O sample, and the abnormal value-assigned 336 mOsm/kg H2O sample were 100.3, 100.2, 99.8, and 100.3 mOsm/kg H2O, respectively. The repeatability data are in accordance with data obtained on clinical osmometers with use of larger sample sizes. All 4 samples tested on the tear osmometer have osmolality values that correlate well to the clinical instrument method. The tear osmometer is a suitable instrument for testing the osmolality of microliter-sized samples, such as tears, and therefore may be useful in diagnosing, monitoring, and classifying tear abnormalities such as the severity of dry eye disease.

Ethanol and sodium acetate as a preservation method to delay degradation of environmental DNA

USGS Publications Warehouse

Ladell, Bridget A.; Walleser, Liza R.; McCalla, S. Grace; Erickson, Richard A.; Amberg, Jon J.

2018-01-01

Environmental DNA (eDNA) samples that are collected from remote locations depend on rapid stabilization of the DNA. The degradation of eDNA in water samples is minimized when samples are stored at ≤ 4 °C. Developing a preservation technique to maintain eDNA integrity at room temperature would allow a wider range of locations to be sampled. We evaluated an ethanol and sodium acetate solution to maintain the integrity of the DNA samples for the time between collection and lab testing. For this evaluation, replicate water samples taken from a tank housing Asian carp were placed on ice or held at room temperature. At both temperatures, water samples were left untreated or were preserved with an ethanol and sodium acetate solution (EtOH–NaAc). Every day for 6 days following collection, a subset of the samples was removed from each preservation method and DNA was extracted and nuclear and mitochondrial markers were assayed with qPCR. Results showed comparable persistence of DNA between iced samples without the EtOH–NaAc treatment and samples that received EtOH–NaAc treatment that were kept at room temperature. We found that DNA can be amplified from preserved samples using an EtOH–NaAc solution after up to 7 days at room temperature.

The corrosion effect of ozonated seawater solution on titanium in polymer generated crevice environments

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

Leveillee, S.Y.

1998-01-01

Two different tests were designed to evaluate the reaction of various polymers and grade-2 titanium in ozonated seawater in conjunction with a comparative analysis in an aerated seawater solution. The first was a weight loss test measuring the weight change of Polyvinyl chloride (PVC), Polyethylene and Teflon{trademark} in both ozonated and aerated artificial seawater baths. The second test was designed to induce crevice corrosion on the titanium test samples using various crevice generating materials in both ozonated and aerated solutions. The materials used to create the crevices were grade-2 titanium washers, PVC, Polyethylene, Saran and Teflon{trademark}. The weight loss testmore » showed that all three polymers lost weight in the ozonated bath. The results of the titanium washer crevice test provided no indication of corrosion or surface discoloration in either the ozonated or aerated solutions. Energy dispersive spectrometry (EDS) analysis found no fluorine, chlorine or other corrosion product. The PVC samples in the aerated bath also showed no signs of corrosion, but the PVC samples in the ozonated tank had light brown rings of surface discoloration. One of the ozonated PVC samples did show evidence of chlorine in the corrosion product. The outer circumference of the ozonated PVC washers exhibited the same type bleaching effect as in the weight loss samples, but the whitening of these samples were more pronounced. The polyethylene samples under aeration showed no discoloration or presence of fluorine or chlorine. The polyethylene crevice samples in the ozonated solution all exhibited the distinct brilliant blue color of titanium oxide. Fluorine was found in the corrosion product on only one of the samples. Chlorine was found on the surface of one of the other corrosion coupons. The results of the Teflon{trademark} crevice samples substantiated the previous Rensselaer study.« less

Sample Results From Tank 48H Samples HTF-48-14-158, -159, -169, and -170

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

Peters, T.; Hang, T.

2015-04-28

Savannah River National Laboratory (SRNL) analyzed samples from Tank 48H in support of determining the cause for the unusually high dose rates at the sampling points for this tank. A set of two samples was taken from the quiescent tank, and two additional samples were taken after the contents of the tank were mixed. The results of the analyses of all the samples show that the contents of the tank have changed very little since the analysis of the previous sample in 2012. The solids are almost exclusively composed of tetraphenylborate (TPB) salts, and there is no indication of accelerationmore » in the TPB decomposition. The filtrate composition shows a moderate increase in salt concentration and density, which is attributable to the addition of NaOH for the purposes of corrosion control. An older modeling simulation of the TPB degradation was updated, and the supernate results from a 2012 sample were run in the model. This result was compared to the results from the 2014 recent sample results reported in this document. The model indicates there is no change in the TPB degradation from 2012 to 2014. SRNL measured the buoyancy of the TPB solids in Tank 48H simulant solutions. It was determined that a solution of density 1.279 g/mL (~6.5M sodium) was capable of indefinitely suspending the TPB solids evenly throughout the solution. A solution of density 1.296 g/mL (~7M sodium) caused a significant fraction of the solids to float on the solution surface. As the experiments could not include the effect of additional buoyancy elements such as benzene or hydrogen generation, the buoyancy measurements provide an upper bound estimate of the density in Tank 48H required to float the solids.« less

Surface analytical study of CuInSe[sub 2] treated in Cd-containing partial electrolyte solution

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

Asher, S.E.; Ramanathan, K.; Wiesner, H.

1999-03-01

Junction formation in CuInSe[sub 2] (CIS) has been studied by exposing thin films and single-crystal samples to solutions containing NH[sub 4]OH and CdSO[sub 4]. The treated samples were analyzed by secondary ion mass spectrometry to determine the amount and distribution of Cd deposited on the surface of the films. Cadmium is found to react with the surface for all the solution exposure times and temperatures studied. The reaction rapidly approaches the endpoint and remains relatively unchanged for subsequent solution exposure. Cadmium in-diffusion, as measured by secondary ion mass spectrometry, is obscured by topography effects in the thin-film samples and bymore » ion-beam mixing and topography in the single-crystal sample. [copyright] [ital 1999 American Institute of Physics.]« less

Surface analytical study of CuInSe{sub 2} treated in Cd-containing partial electrolyte solution

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

Asher, S.E.; Ramanathan, K.; Wiesner, H.

1999-03-01

Junction formation in CuInSe{sub 2} (CIS) has been studied by exposing thin films and single-crystal samples to solutions containing NH{sub 4}OH and CdSO{sub 4}. The treated samples were analyzed by secondary ion mass spectrometry to determine the amount and distribution of Cd deposited on the surface of the films. Cadmium is found to react with the surface for all the solution exposure times and temperatures studied. The reaction rapidly approaches the endpoint and remains relatively unchanged for subsequent solution exposure. Cadmium in-diffusion, as measured by secondary ion mass spectrometry, is obscured by topography effects in the thin-film samples and bymore » ion-beam mixing and topography in the single-crystal sample. {copyright} {ital 1999 American Institute of Physics.}« less

Development and Optimization of a Positron Annihilation Lifetime Spectrometer to Measure Nanoscale Defects in Solids and Borane Cage Molecules in Aqueous Nitrate Solutions

DTIC Science & Technology

2008-03-01

will be accomplished by the day prior to the sample transfer operation. i. The radiation hood lab bench tops where radioactive material will be...source container to a sample container in a single syringe transfer. (All other non- radioactive solutions will have been previously added to this... radioactive spill. 4. Procedure Checklist: a. Setup □ Tape down plastic liner and locate absorbent □ Lay out sample container holder, sample

The effect of solution concentration on the physical and electrochemical properties of vanadium oxide films deposited by spray pyrolysis

NASA Astrophysics Data System (ADS)

Mousavi, M.; Kompany, A.; Shahtahmasebi, N.; Bagheri-Mohagheghi, M. M.

2013-10-01

Vanadium oxide thin films were prepared on glass substrates by using the spray pyrolysis technique. The effect of solution concentration (0.1 M, 0.2 M and 0.3 M) on the nanostructural, electrical, optical, and electrochromic properties of deposited films were investigated using X-ray diffraction, scanning electron microscopy, UV—vis spectroscopy, and cyclic volta-metrics. The X-ray diffraction shows that only the sample at 0.1 M has a single β-V2O5 phase and the others have mixed phases of vanadium oxide. The lowest sheet resistance was obtained for the samples prepared at 0.3 M solution. It was also found that the optical transparency of the samples changes from 70% to 35% and the optical band gap of the samples was in the range of 2.20 to 2.41 eV, depending on the morality of solution. The cycle voltammogram shows that the sample prepared at 0.3 M has one-step electerochoromic but the other samples have two-step electerochoromic. The results show a correlation between the cycle voltammogram and the physical properties of the films.

Tests on the centrifugal flotation technique and its use in estimating the prevalence of Toxocara in soil samples from urban and suburban areas of Malaysia.

PubMed

Loh, A G; Israf, D A

1998-03-01

The influence of soil texture (silt, sand and laterite) and flotation solutions (saturated NaCl, sucrose, NaNO3, and ZnSO4) upon the recovery of Toxocara ova from seeded soil samples with the centrifugal flotation technique was investigated. Soil samples of different texture were artificially seeded with Toxocara spp. ova and subjected to a centrifugal flotation technique which used various flotation solutions. The results showed significant (P < 0.001) interactions between the soil types and the flotation solutions. The highest percentage of ova recovery was obtained with silty soil (34.9-100.8%) with saturated NaCl as the flotation solution (45.3-100.8%). A combination of washing of soil samples with 0.1% Tween 80, and flotation using saturated NaCl and a 30 min coverslip recovery period was used to study the prevalence of contamination of soil samples. Forty-six soil samples were collected from up to 24 public parks/playgrounds in urban areas of Petaling Jaya and suburban areas of Serdang. The prevalence of Toxocara species in the urban and suburban areas was 54.5% and 45.8% respectively.

Determination of lead and nickel in environmental samples by flame atomic absorption spectrometry after column solid-phase extraction on Ambersorb-572 with EDTA.

PubMed

Baytak, Sitki; Türker, A Rehber

2006-02-28

Lead and nickel were preconcentrated as their ethylenediaminetetraacedic acid (EDTA) complexes from aqueous sample solutions using a column containing Ambersorb-572 and determined by flame atomic absorption spectrometry (FAAS). pH values, amount of solid phase, elution solution and flow rate of sample solution have been optimized in order to obtain quantitative recovery of the analytes. The effect of interfering ions on the recovery of the analytes has also been investigated. The recoveries of Pb and Ni under the optimum conditions were 99 +/- 2 and 97 +/- 3%, respectively, at 95% confidence level. Seventy-five-fold (using 750 mL of sample solution and 10 mL of eluent) and 50-fold (using 500 mL of sample solution and 10 mL of eluent) preconcentration was obtained for Pb and Ni, respectively. Time of analysis is about 4.5 h (for obtaining enrichment factor of 75). By applying these enrichment factors, the analytical detection limits of Pb and Ni were found as 3.65 and 1.42 ng mL(-1), respectively. The capacity of the sorbent was found as 0.17 and 0.21 mmol g(-1) for Pb and Ni, respectively. The interferences of some cations, such as Mn2+, Co2+, Fe3+, Al3+, Zn2+, Cd2+, Ca2+, Mg2+, K+ and Na+ usually present in water samples were also studied. This procedure was applied to the determination of lead and nickel in parsley, green onion, sea water and waste water samples. The accuracy of the procedure was checked by determining Pb and Ni in standard reference tea leaves sample (GBW-07605). The results demonstrated good agreement with the certified values.

Solution and Aging of MAR-M246 Nickel-Based Superalloy

NASA Astrophysics Data System (ADS)

Baldan, Renato; da Silva, Antonio Augusto Araújo Pinto; Nunes, Carlos Angelo; Couto, Antonio Augusto; Gabriel, Sinara Borborema; Alkmin, Luciano Braga

2017-02-01

Solution and aging heat-treatments play a key role for the application of the superalloys. The aim of this work is to evaluate the microstructure of the MAR-M246 nickel-based superalloy solutioned at 1200 and 1250 °C for 330 min and aged at 780, 880 and 980 °C for 5, 20 and 80 h. The γ' solvus, solidus and liquidus temperatures were calculated with the aid of the JMatPro software (Ni database). The as-cast and heat-treated samples were characterized by SEM/EDS and SEM-FEG. The γ' size precipitated in the aged samples was measured and compared with JMatPro simulations. The results have shown that the sample solutioned at 1250 °C for 330 min showed a very homogeneous γ matrix with carbides and cubic γ' precipitates uniformly distributed. The mean γ' size of aged samples at 780 and 880 °C for 5, 20 and 80 h did not present significant differences when compared to the solutioned sample. However, a significant increasing in the γ' particles was observed at 980 °C, evidenced by the large mean size of these particles after 80 h of aging heat-treatment.

Considerations for sampling inorganic constituents in ground water using diffusion samplers

USGS Publications Warehouse

Vroblesky, D.A.; Petkewich, M.D.; Campbell, T.R.; ,

2002-01-01

Data indicate that nylon-screen and dialysis diffusion samplers are capable of obtaining concentrations of inorganic solutes in ground water from wells that closely correspond to concentrations obtained by low-flow sampling. Conservative solutes, such as chloride, can be sampled by filling the diffusion samplers with oxygenated water. The samplers should be filled with anaerobic water for sampling redoxsensitive solutes. Oxidation of iron within the samplers, either by using aerobic fill water or by in-well oxygenation events, can lead to erroneous iron concentrations. Lithologic and chemical heterogeneity and sampler placement depth can lead to differences between concentrations from diffusion samples and low-flow samples because of mixing during pumping. A disadvantage of regenerated cellulose dialysis samplers is that they can begin to biodegrade within the two weeks of deployment. Nylon-screen samplers buried beneath streambed sediment along the unnamed tributary in a discharge zone of arseniccontaminated ground water were useful in locating the specific discharge zone.

Sample Dimensionality Effects on d' and Proportion of Correct Responses in Discrimination Testing.

PubMed

Bloom, David J; Lee, Soo-Yeun

2016-09-01

Products in the food and beverage industry have varying levels of dimensionality ranging from pure water to multicomponent food products, which can modify sensory perception and possibly influence discrimination testing results. The objectives of the study were to determine the impact of (1) sample dimensionality and (2) complex formulation changes on the d' and proportion of correct response of the 3-AFC and triangle methods. Two experiments were conducted using 47 prescreened subjects who performed either triangle or 3-AFC test procedures. In Experiment I, subjects performed 3-AFC and triangle tests using model solutions with different levels of dimensionality. Samples increased in dimensionality from 1-dimensional sucrose in water solution to 3-dimensional sucrose, citric acid, and flavor in water solution. In Experiment II, subjects performed 3-AFC and triangle tests using 3-dimensional solutions. Sample pairs differed in all 3 dimensions simultaneously to represent complex formulation changes. Two forms of complexity were compared: dilution, where all dimensions decreased in the same ratio, and compensation, where a dimension was increased to compensate for a reduction in another. The proportion of correct responses decreased for both methods when the dimensionality was increased from 1- to 2-dimensional samples. No reduction in correct responses was observed from 2- to 3-dimensional samples. No significant differences in d' were demonstrated between the 2 methods when samples with complex formulation changes were tested. Results reveal an impact on proportion of correct responses due to sample dimensionality and should be explored further using a wide range of sample formulations. © 2016 Institute of Food Technologists®

Multiobjective sampling design for parameter estimation and model discrimination in groundwater solute transport

USGS Publications Warehouse

Knopman, Debra S.; Voss, Clifford I.

1989-01-01

Sampling design for site characterization studies of solute transport in porous media is formulated as a multiobjective problem. Optimal design of a sampling network is a sequential process in which the next phase of sampling is designed on the basis of all available physical knowledge of the system. Three objectives are considered: model discrimination, parameter estimation, and cost minimization. For the first two objectives, physically based measures of the value of information obtained from a set of observations are specified. In model discrimination, value of information of an observation point is measured in terms of the difference in solute concentration predicted by hypothesized models of transport. Points of greatest difference in predictions can contribute the most information to the discriminatory power of a sampling design. Sensitivity of solute concentration to a change in a parameter contributes information on the relative variance of a parameter estimate. Inclusion of points in a sampling design with high sensitivities to parameters tends to reduce variance in parameter estimates. Cost minimization accounts for both the capital cost of well installation and the operating costs of collection and analysis of field samples. Sensitivities, discrimination information, and well installation and sampling costs are used to form coefficients in the multiobjective problem in which the decision variables are binary (zero/one), each corresponding to the selection of an observation point in time and space. The solution to the multiobjective problem is a noninferior set of designs. To gain insight into effective design strategies, a one-dimensional solute transport problem is hypothesized. Then, an approximation of the noninferior set is found by enumerating 120 designs and evaluating objective functions for each of the designs. Trade-offs between pairs of objectives are demonstrated among the models. The value of an objective function for a given design is shown to correspond to the ability of a design to actually meet an objective.

Electro membrane extraction combined with capillary electrophoresis for the determination of amlodipine enantiomers in biological samples.

PubMed

Nojavan, Saeed; Fakhari, Ali Reza

2010-10-01

Electro membrane extraction as a new microextraction method was applied for the extraction of amlodipine (AM) enantiomers from biological samples. During the extraction time of 15  min, AM enantiomers migrated from a 3  mL sample solution, through a supported liquid membrane into a 20  μL acceptor solution presented inside the lumen of the hollow fiber. The driving force of the extraction was 200  V potential, with the negative electrode in the acceptor solution and the positive electrode in the sample solution. 2-Nitro phenyl octylether was used as the supported liquid membrane. Using 10  mM HCl as background electrolyte in the sample and acceptor solution, enrichment up to 124 times was achieved. Then, the extract was analyzed using CD modified CE method for separation of AM enantiomers. Best results were achieved using a phosphate running buffer (100  mM, pH 2.0) containing 5  mM hydroxypropyl-α-CD. The range of quantitation for both enantiomers was 10-500  ng/mL. Intra- and interday RSD (n=6) were less than 14%. The limits of quantitation and detection for both enantiomers were 10 and 3  ng/mL respectively. Finally, this procedure was applied to determine the concentration of AM enantiomers in plasma and urine samples.

Sampling design for groundwater solute transport: Tests of methods and analysis of Cape Cod tracer test data

USGS Publications Warehouse

Knopman, Debra S.; Voss, Clifford I.; Garabedian, Stephen P.

1991-01-01

Tests of a one-dimensional sampling design methodology on measurements of bromide concentration collected during the natural gradient tracer test conducted by the U.S. Geological Survey on Cape Cod, Massachusetts, demonstrate its efficacy for field studies of solute transport in groundwater and the utility of one-dimensional analysis. The methodology was applied to design of sparse two-dimensional networks of fully screened wells typical of those often used in engineering practice. In one-dimensional analysis, designs consist of the downstream distances to rows of wells oriented perpendicular to the groundwater flow direction and the timing of sampling to be carried out on each row. The power of a sampling design is measured by its effectiveness in simultaneously meeting objectives of model discrimination, parameter estimation, and cost minimization. One-dimensional models of solute transport, differing in processes affecting the solute and assumptions about the structure of the flow field, were considered for description of tracer cloud migration. When fitting each model using nonlinear regression, additive and multiplicative error forms were allowed for the residuals which consist of both random and model errors. The one-dimensional single-layer model of a nonreactive solute with multiplicative error was judged to be the best of those tested. Results show the efficacy of the methodology in designing sparse but powerful sampling networks. Designs that sample five rows of wells at five or fewer times in any given row performed as well for model discrimination as the full set of samples taken up to eight times in a given row from as many as 89 rows. Also, designs for parameter estimation judged to be good by the methodology were as effective in reducing the variance of parameter estimates as arbitrary designs with many more samples. Results further showed that estimates of velocity and longitudinal dispersivity in one-dimensional models based on data from only five rows of fully screened wells each sampled five or fewer times were practically equivalent to values determined from moments analysis of the complete three-dimensional set of 29,285 samples taken during 16 sampling times.

BioSAXS Sample Changer: a robotic sample changer for rapid and reliable high-throughput X-ray solution scattering experiments

PubMed Central

Round, Adam; Felisaz, Franck; Fodinger, Lukas; Gobbo, Alexandre; Huet, Julien; Villard, Cyril; Blanchet, Clement E.; Pernot, Petra; McSweeney, Sean; Roessle, Manfred; Svergun, Dmitri I.; Cipriani, Florent

2015-01-01

Small-angle X-ray scattering (SAXS) of macromolecules in solution is in increasing demand by an ever more diverse research community, both academic and industrial. To better serve user needs, and to allow automated and high-throughput operation, a sample changer (BioSAXS Sample Changer) that is able to perform unattended measurements of up to several hundred samples per day has been developed. The Sample Changer is able to handle and expose sample volumes of down to 5 µl with a measurement/cleaning cycle of under 1 min. The samples are stored in standard 96-well plates and the data are collected in a vacuum-mounted capillary with automated positioning of the solution in the X-ray beam. Fast and efficient capillary cleaning avoids cross-contamination and ensures reproducibility of the measurements. Independent temperature control for the well storage and for the measurement capillary allows the samples to be kept cool while still collecting data at physiological temperatures. The Sample Changer has been installed at three major third-generation synchrotrons: on the BM29 beamline at the European Synchrotron Radiation Facility (ESRF), the P12 beamline at the PETRA-III synchrotron (EMBL@PETRA-III) and the I22/B21 beamlines at Diamond Light Source, with the latter being the first commercial unit supplied by Bruker ASC. PMID:25615861

The factor structure and reliability of the Illness Attitude Scales in a student and a patient sample

PubMed Central

Crössmann, Alexander; Pauli, Paul

2006-01-01

Background The Illness Attitude Scales (IAS), designed by Kellner in 1986, assesses fears, beliefs, and attitudes associated with hypochondriasis and abnormal illness behaviour. However, its factor structure is, especially for translations of the IAS, not sufficiently explored. Thus, the present Study aimed to analyse the factor structure of the IAS in a German student and a patient population using exploratory factor analysis. Methods A mixed student (N = 296) and a mixed patient (N = 130) sample completed the IAS. The data was submitted to principal components analyses (PCA) with subsequent oblique rotations. From identified factor structures, scales were derived and submitted to reliability analyses as well as to a preliminary validity analysis. Results The PCA revealed a four-factor solution in the student sample: (1) fear of illness and death; (2) treatment experience; (3) hypochondriacal beliefs; and (4) effect of symptoms. In the patient sample, the data was best explained by a two-factor solution: (1) health related anxiety and (2) effect of symptoms and treatment experience. All scales reached good to acceptable reliability coefficients. The scales derived from the student sample and those derived from the patient sample were able to distinguish between pain patients and a matched group of normal controls. Conclusion Our data suggests that the IAS is in student samples best represented by a four factor-solution and in patient samples by a two-factor-solution. PMID:17067384

Delta 14CO2 Record from Vermunt, Austria, February 1959 - June 1983

DOE Data Explorer

Levin, Ingeborg [Institut fur Umweltphysik, University of Heidelberg, Germany; Kromer, Bernd [Institut fur Umweltphysik, University of Heidelberg, Germany; Schoch-Fischer, H. [Institut fur Umweltphysik, University of Heidelberg, Germany; Bruns, M. [Institut fur Umweltphysik, University of Heidelberg, Germany; Munnich, M. [Institut fur Umweltphysik, University of Heidelberg, Germany; Berdau, D. [Institut fur Umweltphysik, University of Heidelberg, Germany; Vogel, J. C. [Institut fur Umweltphysik, University of Heidelberg, Germany; Munnich, K. O. [Institut fur Umweltphysik, University of Heidelberg, Germany

1994-01-01

The sampling at Vermunt was discontinued in 1983. During sampling from 1959 to 1983, the sampling methods were modified twice (Levin et al. 1985). From 1959 through November 1965, three dishes with 1.5 L of 0.5 normal sodium hydroxide (NaOH) carbonate-free solution were exposed to the atmosphere for ~3 days, and the atmospheric CO2 absorbed during that time was recovered by acid evolution. From November 1965 through May 1975, samples were collected by pumping fresh air continuously for 10 days through a box containing 1.5 L of a 0.5 normal NaOH solution. The method has been described by Münnich and Vogel (1959). From May 1975 to the time sampling stopped, a technique described by Levin et al. (1980) was used. Air was pumped through a rotating glass tube filled with a packed bed of Raschig rings (hard glass) to enlarge the surface of the absorbing NaOH solution (200 ml of 4 normal NaOH). The CO2 absorption was quantitative and samples represent mean values of 10 days to 2 weeks. In the laboratory, the samples were extracted from the NaOH solution in a vacuum system by adding hydrochloric or sulfuric acid. The CO2 gas samples were purified over charcoal and counted in a proportional counter (Schoch et al. 1980). Delta 14C values are given relative to the NIST oxalic acid activity corrected for decay (Stuiver and Polach 1970).

Uncertainty of streamwater solute fluxes in five contrasting headwater catchments including model uncertainty and natural variability (Invited)

NASA Astrophysics Data System (ADS)

Aulenbach, B. T.; Burns, D. A.; Shanley, J. B.; Yanai, R. D.; Bae, K.; Wild, A.; Yang, Y.; Dong, Y.

2013-12-01

There are many sources of uncertainty in estimates of streamwater solute flux. Flux is the product of discharge and concentration (summed over time), each of which has measurement uncertainty of its own. Discharge can be measured almost continuously, but concentrations are usually determined from discrete samples, which increases uncertainty dependent on sampling frequency and how concentrations are assigned for the periods between samples. Gaps between samples can be estimated by linear interpolation or by models that that use the relations between concentration and continuously measured or known variables such as discharge, season, temperature, and time. For this project, developed in cooperation with QUEST (Quantifying Uncertainty in Ecosystem Studies), we evaluated uncertainty for three flux estimation methods and three different sampling frequencies (monthly, weekly, and weekly plus event). The constituents investigated were dissolved NO3, Si, SO4, and dissolved organic carbon (DOC), solutes whose concentration dynamics exhibit strongly contrasting behavior. The evaluation was completed for a 10-year period at five small, forested watersheds in Georgia, New Hampshire, New York, Puerto Rico, and Vermont. Concentration regression models were developed for each solute at each of the three sampling frequencies for all five watersheds. Fluxes were then calculated using (1) a linear interpolation approach, (2) a regression-model method, and (3) the composite method - which combines the regression-model method for estimating concentrations and the linear interpolation method for correcting model residuals to the observed sample concentrations. We considered the best estimates of flux to be derived using the composite method at the highest sampling frequencies. We also evaluated the importance of sampling frequency and estimation method on flux estimate uncertainty; flux uncertainty was dependent on the variability characteristics of each solute and varied for different reporting periods (e.g. 10-year, study period vs. annually vs. monthly). The usefulness of the two regression model based flux estimation approaches was dependent upon the amount of variance in concentrations the regression models could explain. Our results can guide the development of optimal sampling strategies by weighing sampling frequency with improvements in uncertainty in stream flux estimates for solutes with particular characteristics of variability. The appropriate flux estimation method is dependent on a combination of sampling frequency and the strength of concentration regression models. Sites: Biscuit Brook (Frost Valley, NY), Hubbard Brook Experimental Forest and LTER (West Thornton, NH), Luquillo Experimental Forest and LTER (Luquillo, Puerto Rico), Panola Mountain (Stockbridge, GA), Sleepers River Research Watershed (Danville, VT)

Biochemical composition of fluids for amnioinfusion during fetoscopy.

PubMed

Adama van Scheltema, P N; In't Anker, P S; Vereecken, A; Vandenbussche, F P H A; Deprest, J A; Devlieger, R

2008-01-01

To evaluate which of the commercially available solutions is best suited for amnioinfusion during fetoscopy, based on resemblance with the biochemical properties of amniotic fluid. Amniotic fluid samples from 10 pregnancies were studied. Specimens were obtained from 5 pathologic pregnancies (of which 3 were complicated by polyhydramnios) and 5 uncomplicated pregnancies. The concentrations of sodium, potassium, chloride, bicarbonate, calcium, glucose, osmolality, pH, total protein content and albumin were determined in each sample. A literature search (PubMed, Embase) was performed to identify commercially available fluids used for amnioinfusion in clinical practice. The composition of these infusion solutions was compared to the amniotic fluid samples mentioned above. We identified two different electrolyte solutions used in clinical practice for amnioinfusion. We identified four additional commercially available solutions that could potentially be used for amnioinfusion. Most of these infusion solutions differ considerably from midtrimester amniotic fluid samples both in electrolyte composition and pH, with the most striking difference in the latter. Lactated Ringer's solution approximates amniotic fluid the closest for both electrolyte composition and pH. This infusion solution seems to be the most suitable choice for amnioinfusion during fetoscopy. (c) 2008 S. Karger AG, Basel.

Improvement for identification of heterophile antibody interference and AFP hook effect in immunoassays with multiplex suspension bead array system.

PubMed

Wang, Yajie; Yu, Jinsheng; Ren, Yuan; Liu, Li; Li, Haowen; Guo, Anchen; Shi, Congning; Fang, Fang; Juehne, Twyla; Yao, Jianer; Yang, Enhuan; Zhou, Xuelei; Kang, Xixiong

2013-11-15

A variety of immunoassays including multiplex suspension bead array have been developed for tumor marker detections; however, these assays could be compromised in their sensitivity and specificity by well-known heterophile antibody interference and hook effect. Using Luminex® multiplex suspension bead arrays, we modified protocols with two newly-developed solutions that can identify heterophile antibody interference and AFP hook effect. Effectiveness of the two solutions was assessed in serum samples from patients. Concentrations of 9 tumor markers in heterophile antibody positive samples assayed with Solution A, containing murine monoclonal antibodies and mouse serum, were significantly reduced when compared with those false high signals assayed without Solution A (all p<0.01). With incorporation of Solution H (fluorescent beads linked with AFP antigen), a new strategy for identification of AFP hook effect was established, and with this strategy AFP hook effect was identified effectively in serum samples with very high levels of AFP. Two proprietary solutions improve the identification of heterophile antibody interference and AFP hook effect. With these solutions, multiplex suspension bead arrays provide more reliable testing results in tumor marker detection where complex clinical serum samples are used. © 2013.

A simple homogeneous model for regular and irregular metallic wire media samples

NASA Astrophysics Data System (ADS)

Kosulnikov, S. Y.; Mirmoosa, M. S.; Simovski, C. R.

2018-02-01

To simplify the solution of electromagnetic problems with wire media samples, it is reasonable to treat them as the samples of a homogeneous material without spatial dispersion. The account of spatial dispersion implies additional boundary conditions and makes the solution of boundary problems difficult especially if the sample is not an infinitely extended layer. Moreover, for a novel type of wire media - arrays of randomly tilted wires - a spatially dispersive model has not been developed. Here, we introduce a simplistic heuristic model of wire media samples shaped as bricks. Our model covers WM of both regularly and irregularly stretched wires.

Synthetic food colours in saffron solutions, saffron rice and saffron chicken from restaurants in Tehran, Iran.

PubMed

Moradi-Khatoonabadi, Zhila; Amirpour, Mansooreh; AkbariAzam, Maryam

2015-01-01

Saffron solutions, saffron rice and saffron chicken samples were considered for synthetic colours as additives, which are forbidden according to Iranian national standards. Samples were taken from restaurants of three locations and analysed by high-performance liquid chromatography. Of the total 573 samples, 52% were positive for at least one colour. The most prevalent colours were Tartrazine, Quinoline Yellow and Sunset Yellow, with 44%, 9.1% and 8.4% of the samples testing positive for these colours, respectively. Carmoisine and Ponceau were both detected only in 0.5% of the positive samples and found only in saffron solution. In conclusion, synthetic food colours, especially Tartrazine should be regarded as a potential risk in saffron and its related food. Therefore, new attempts for food safety and quality should be undertaken to eliminate the use of these colours in restaurants.

The preparation and degradation performance of CdS photocatalysts to methyl orange solution.

PubMed

Duan, Limei; Zhao, Weiqiang; Xu, Ling; Chen, Xiaohong; Lita, A; Liu, Zongrui

2013-03-01

In this paper, the CdS samples were prepared using thiourea or sodium sulfide as sulfur source by hydrothermal or solvothermal synthesis method, the results of XRD, TEM and SEM showed all the samples belong to hexagonal CdS nano-material with different morphologies. Using the degradation of methyl orange solution as a model reaction, the photocatalytic performance of different CdS samples was measured, and the samples prepared using thiourea as sulfur source exhibited better photocatalytic activity than those using sodium sulfide as sulfur source. The factors on degradation effect were discussed including the pH value of degradation system and the type of light source. The degradation effect of CdS samples increased with the pH value decreased, and the degradation effect was better when the methyl orange solution was irradiated under sunlight than under 250 W mercury lamp.

SAMPL5: 3D-RISM partition coefficient calculations with partial molar volume corrections and solute conformational sampling.

PubMed

Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C; Joyce, Kevin P; Kovalenko, Andriy

2016-11-01

Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing ([Formula: see text] for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining [Formula: see text] compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to [Formula: see text]. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple [Formula: see text] correction improved agreement with experiment from [Formula: see text] to [Formula: see text], despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.

SAMPL5: 3D-RISM partition coefficient calculations with partial molar volume corrections and solute conformational sampling

NASA Astrophysics Data System (ADS)

Luchko, Tyler; Blinov, Nikolay; Limon, Garrett C.; Joyce, Kevin P.; Kovalenko, Andriy

2016-11-01

Implicit solvent methods for classical molecular modeling are frequently used to provide fast, physics-based hydration free energies of macromolecules. Less commonly considered is the transferability of these methods to other solvents. The Statistical Assessment of Modeling of Proteins and Ligands 5 (SAMPL5) distribution coefficient dataset and the accompanying explicit solvent partition coefficient reference calculations provide a direct test of solvent model transferability. Here we use the 3D reference interaction site model (3D-RISM) statistical-mechanical solvation theory, with a well tested water model and a new united atom cyclohexane model, to calculate partition coefficients for the SAMPL5 dataset. The cyclohexane model performed well in training and testing (R=0.98 for amino acid neutral side chain analogues) but only if a parameterized solvation free energy correction was used. In contrast, the same protocol, using single solute conformations, performed poorly on the SAMPL5 dataset, obtaining R=0.73 compared to the reference partition coefficients, likely due to the much larger solute sizes. Including solute conformational sampling through molecular dynamics coupled with 3D-RISM (MD/3D-RISM) improved agreement with the reference calculation to R=0.93. Since our initial calculations only considered partition coefficients and not distribution coefficients, solute sampling provided little benefit comparing against experiment, where ionized and tautomer states are more important. Applying a simple pK_{ {a}} correction improved agreement with experiment from R=0.54 to R=0.66, despite a small number of outliers. Better agreement is possible by accounting for tautomers and improving the ionization correction.

Methods of synthesizing carbon-magnetite nanocomposites from renewable resource materials and application of same

DOEpatents

Viswanathan, Tito

2014-07-29

A method of synthesizing carbon-magnetite nanocomposites. In one embodiment, the method includes the steps of (a) dissolving a first amount of an alkali salt of lignosulfonate in water to form a first solution, (b) heating the first solution to a first temperature, (c) adding a second amount of iron sulfate (FeSO.sub.4) to the first solution to form a second solution, (d) heating the second solution at a second temperature for a first duration of time effective to form a third solution of iron lignosulfonate, (e) adding a third amount of 1N sodium hydroxide (NaOH) to the third solution of iron lignosulfonate to form a fourth solution with a first pH level, (f) heating the fourth solution at a third temperature for a second duration of time to form a first sample, and (g) subjecting the first sample to a microwave radiation for a third duration of time effective to form a second sample containing a plurality of carbon-magnetite nanocomposites.

Effects of forcefield and sampling method in all-atom simulations of inherently disordered proteins: Application to conformational preferences of human amylin

PubMed Central

Peng, Enxi; Todorova, Nevena

2017-01-01

Although several computational modelling studies have investigated the conformational behaviour of inherently disordered protein (IDP) amylin, discrepancies in identifying its preferred solution conformations still exist between various forcefields and sampling methods used. Human islet amyloid polypeptide has long been a subject of research, both experimentally and theoretically, as the aggregation of this protein is believed to be the lead cause of type-II diabetes. In this work, we present a systematic forcefield assessment using one of the most advanced non-biased sampling techniques, Replica Exchange with Solute Tempering (REST2), by comparing the secondary structure preferences of monomeric amylin in solution. This study also aims to determine the ability of common forcefields to sample a transition of the protein from a helical membrane bound conformation into the disordered solution state of amylin. Our results demonstrated that the CHARMM22* forcefield showed the best ability to sample multiple conformational states inherent for amylin. It is revealed that REST2 yielded results qualitatively consistent with experiments and in quantitative agreement with other sampling methods, however far more computationally efficiently and without any bias. Therefore, combining an unbiased sampling technique such as REST2 with a vigorous forcefield testing could be suggested as an important step in developing an efficient and robust strategy for simulating IDPs. PMID:29023509

Effects of forcefield and sampling method in all-atom simulations of inherently disordered proteins: Application to conformational preferences of human amylin.

PubMed

Peng, Enxi; Todorova, Nevena; Yarovsky, Irene

2017-01-01

Although several computational modelling studies have investigated the conformational behaviour of inherently disordered protein (IDP) amylin, discrepancies in identifying its preferred solution conformations still exist between various forcefields and sampling methods used. Human islet amyloid polypeptide has long been a subject of research, both experimentally and theoretically, as the aggregation of this protein is believed to be the lead cause of type-II diabetes. In this work, we present a systematic forcefield assessment using one of the most advanced non-biased sampling techniques, Replica Exchange with Solute Tempering (REST2), by comparing the secondary structure preferences of monomeric amylin in solution. This study also aims to determine the ability of common forcefields to sample a transition of the protein from a helical membrane bound conformation into the disordered solution state of amylin. Our results demonstrated that the CHARMM22* forcefield showed the best ability to sample multiple conformational states inherent for amylin. It is revealed that REST2 yielded results qualitatively consistent with experiments and in quantitative agreement with other sampling methods, however far more computationally efficiently and without any bias. Therefore, combining an unbiased sampling technique such as REST2 with a vigorous forcefield testing could be suggested as an important step in developing an efficient and robust strategy for simulating IDPs.

Method for chromium analysis and speciation

DOEpatents

Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

2004-11-02

A method of detecting a metal in a sample comprising a plurality of metal is disclosed. The method comprises providing the sample comprising a metal to be detected. The sample is added to a reagent solution comprising an enzyme and a substrate, where the enzyme is inhibited by the metal to be detected. An array of chelating agents is used to eliminate the inhibitory effects of additional metals in the sample. An enzymatic activity in the sample is determined and compared to an enzymatic activity in a control solution to detect the metal to be detected. A method of determining a concentration of the metal in the sample is also disclosed. A method of detecting a valence state of a metal is also disclosed.

Method for liquid chromatographic extraction of strontium from acid solutions

DOEpatents

Horwitz, E. Philip; Dietz, Mark L.

1992-01-01

A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

Reducing the risk of fatal and disabling hypoglycaemia: a comparison of arterial blood sampling systems.

PubMed

Brennan, K A; Eapen, G; Turnbull, D

2010-04-01

In 2008, the National Patient Safety Agency (NPSA) published a report after 42 incidents and two deaths where glucose-containing flush solutions were attached to the arterial line. The molar concentration of 5% glucose is 277 mmol litre(-1). Only a tiny amount of sample contamination will lead to an artificially high glucose. As the NPSA sought a solution, a bench model was constructed to compare the performance of three open and three closed arterial line systems in limiting sample contamination. All arterial line systems were set up in a standard manner and pressurized to 300 mm Hg with 5% glucose used as the flush solution. This was connected to the 'radial artery' using an 18 G needle representing the radial cannula. The radial artery was simulated using a wide-bore extension set with 'blood' flow at 60 ml min(-1). Blood was simulated by the addition of red dye to Hartmann's solution. Increasing multiples of arterial line dead space were aspirated and discarded. Blood samples were then obtained and glucose concentration was measured. Significant glucose contamination (3 mmol litre(-1) +/-3.4) was detected in all open arterial line systems up to an aspiration volume of five times the dead space. No samples from the closed systems recorded glucose concentration >1 mmol litre(-1). Recommended minimal discard volumes are inadequate in the presence of glucose as the flush solution and can lead to high blood glucose readings, inappropriate insulin use, and iatrogenic neuroglycopaenia. Our study demonstrates that the closed-loop arterial sampling system could be the universal solution sought by the NPSA.

Liquid chromatographic extraction medium

DOEpatents

Horwitz, E. Philip; Dietz, Mark L.

1994-01-01

A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

Use of on-site high performance liquid chromatography to evaluate the magnitude and extent of organic contaminants in aquifers

USGS Publications Warehouse

Goerlitz, D.F.; Franks, B.J.

1989-01-01

Appraisal of ground water contaminated by organic substances raises problems of difficult sample collection and timely chemical analysis. High-performance liquid chromatography was evaluated for on-site determination of specific organic contaminants in ground water samples and was used at three study sites. Organic solutes were determined directly in water samples, with little or no preparation, and usually in less than an hour after collection. This information improved sampling efficiency and was useful in screening for subsequent laboratory analysis. On two occasions, on-site analysis revealed that samples were undergoing rapid change, with major solutes being upgraded and alteration products being formed. In addition to sample stability, this technique proved valuable for monitoring other sampling factors such as compositional changes with respect to pumping, filtration, and cross contamination. -Authors

Microfluidics Meets Dilute Solution Viscometry: An Undergraduate Laboratory to Determine Polymer Molecular Weight Using a Microviscometer

ERIC Educational Resources Information Center

Pety, Stephen J.; Lu, Hang; Thio, Yonathan S.

2011-01-01

This paper describes a student laboratory experiment to determine the molecular weight of a polymer sample by measuring the viscosity of dilute polymer solutions in a PDMS microfluidic viscometer. Sample data are given for aqueous solutions of poly(ethylene oxide) (PEO). A demonstration of shear thinning behavior using the microviscometer is…

Students' Perceptions of a Self-Diagnosis Task

NASA Astrophysics Data System (ADS)

Safadi, Rafi'; Yerushalmi, Edit

2009-11-01

What happens when students are required to engage in a self-diagnosis task; in other words get time and credit for identifying mistakes they made assisted by a sample solution? We examine this question using data collected on 180 high school students in the Arab sector in Israel. Students were able to find significant differences between their solutions and the sample solution. Yet many did not provide self-explanations indicating that they acknowledged a conflict between their mental models and the scientific model. Further, students also addressed non-significant differences. They apparently referred to the sample solution as an ultimate template and identified external deviations from it as flaws or weaknesses. Students reflected on their personal solution process, and the materials used in the task. The findings suggest allocating time for scaffolding "self-diagnosis."

Enhanced conformational sampling using replica exchange with concurrent solute scaling and hamiltonian biasing realized in one dimension.

PubMed

Yang, Mingjun; Huang, Jing; MacKerell, Alexander D

2015-06-09

Replica exchange (REX) is a powerful computational tool for overcoming the quasi-ergodic sampling problem of complex molecular systems. Recently, several multidimensional extensions of this method have been developed to realize exchanges in both temperature and biasing potential space or the use of multiple biasing potentials to improve sampling efficiency. However, increased computational cost due to the multidimensionality of exchanges becomes challenging for use on complex systems under explicit solvent conditions. In this study, we develop a one-dimensional (1D) REX algorithm to concurrently combine the advantages of overall enhanced sampling from Hamiltonian solute scaling and the specific enhancement of collective variables using Hamiltonian biasing potentials. In the present Hamiltonian replica exchange method, termed HREST-BP, Hamiltonian solute scaling is applied to the solute subsystem, and its interactions with the environment to enhance overall conformational transitions and biasing potentials are added along selected collective variables associated with specific conformational transitions, thereby balancing the sampling of different hierarchical degrees of freedom. The two enhanced sampling approaches are implemented concurrently allowing for the use of a small number of replicas (e.g., 6 to 8) in 1D, thus greatly reducing the computational cost in complex system simulations. The present method is applied to conformational sampling of two nitrogen-linked glycans (N-glycans) found on the HIV gp120 envelope protein. Considering the general importance of the conformational sampling problem, HREST-BP represents an efficient procedure for the study of complex saccharides, and, more generally, the method is anticipated to be of general utility for the conformational sampling in a wide range of macromolecular systems.

Slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for steelmaking flue dust analysis

NASA Astrophysics Data System (ADS)

Coedo, A. G.; Dorado, T.; Padilla, I.; Maibusch, R.; Kuss, H.-M.

2000-02-01

A commercial atomic absorption graphite furnace (AAGF), with a self-made adapter and valve system, was used as a slurry sampling cell for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The system was applied to the determination of As, Sn, Sb, Se, Te, Bi, Cd, V, Ti and Mo in steelmaking flue dusts. Experimental conditions with respect to ETV and ICP-MS operating parameters were optimized. Compared to aqueous solutions, slurry samples were found to present better analyte transport. Microgram amounts of Rh were used to reduce the difference in analyte response in sensitivity for aqueous solutions of the tested analytes. No such increasing effect was observed for slurry samples and aqueous standards. An added quantity of Rh acting as modifier/carrier resulted in an increase for the same analytes in matrix-slurry solutions, even the addition of an extra Rh quantity has resulted in a decrease in the signals. The effect of Triton X-100 (used as a dispersant agent) on analyte intensity and precision was also studied. External calibration from aqueous standards spiked with 100 μg ml -1 Rh was performed to quantified 0.010 g/100 ml slurry samples. Results are presented for a certified reference electrical arc furnace flue dust (EAF): CRM-876-1 (Bureau of Analysis Samples Ltd., Cleveland, UK), a reference sample of coke ashes X-3705 (from AG der Dillinger Hüttenwerke, Germany), and a representative sample of EAF flue dust from a Spanish steelmaking company (CENIM-1). For the two reference materials an acceptable agreement with certificate values was achieved, and the results for the CENIM sample matched with those obtained from conventional nebulization solution.

Investigation of chemical modifiers for the direct determination of arsenic in fish oil using high-resolution continuum source graphite furnace atomic absorption spectrometry.

PubMed

Pereira, Éderson R; de Almeida, Tarcísio S; Borges, Daniel L G; Carasek, Eduardo; Welz, Bernhard; Feldmann, Jörg; Campo Menoyo, Javier Del

2016-04-01

High-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) has been applied for the development of a method for the determination of total As in fish oil samples using direct analysis. The method does not use any sample pretreatment, besides dilution with 1-propanole, in order to decrease the oil viscosity. The stability and sensitivity of As were evaluated using ruthenium and iridium as permanent chemical modifiers and palladium added in solution over the sample. The best results were obtained with ruthenium as the permanent modifier and palladium in solution added to samples and standard solutions. Under these conditions, aqueous standard solutions could be used for calibration for the fish oil samples diluted with 1-propanole. The pyrolysis and atomization temperatures were 1400 °C and 2300 °C, respectively, and the limit of detection and characteristic mass were 30 pg and 43 pg, respectively. Accuracy and precision of the method have been evaluated using microwave-assisted acid digestion of the samples with subsequent determination by HR-CS GF AAS and ICP-MS; the results were in agreement (95% confidence level) with those of the proposed method. Copyright © 2015 Elsevier B.V. All rights reserved.

The effect of pH and chloride concentration on the stability and antimicrobial activity of chlorine-based sanitizers.

PubMed

Waters, Brian W; Hung, Yen-Con

2014-04-01

Chlorinated water and electrolyzed oxidizing (EO) water solutions were made to compare the free chlorine stability and microbicidal efficacy of chlorine-containing solutions with different properties. Reduction of Escherichia coli O157:H7 was greatest in fresh samples (approximately 9.0 log CFU/mL reduction). Chlorine loss in "aged" samples (samples left in open bottles) was greatest (approximately 40 mg/L free chlorine loss in 24 h) in low pH (approximately 2.5) and high chloride (Cl(-) ) concentrations (greater than 150 mg/L). Reduction of E. coli O157:H7 was also negatively impacted (<1.0 log CFU/mL reduction) in aged samples with a low pH and high Cl(-) . Higher pH values (approximately 6.0) did not appear to have a significant effect on free chlorine loss or numbers of surviving microbial cells when fresh and aged samples were compared. This study found chloride levels in the chlorinated and EO water solutions had a reduced effect on both free chlorine stability and its microbicidal efficacy in the low pH solutions. Greater concentrations of chloride in pH 2.5 samples resulted in decreased free chlorine stability and lower microbicidal efficacy. © 2014 Institute of Food Technologists®

Electrodialytic in-line preconcentration for ionic solute analysis.

PubMed

Ohira, Shin-Ichi; Yamasaki, Takayuki; Koda, Takumi; Kodama, Yuko; Toda, Kei

2018-04-01

Preconcentration is an effective way to improve analytical sensitivity. Many types of methods are used for enrichment of ionic solute analytes. However, current methods are batchwise and include procedures such as trapping and elution. In this manuscript, we propose in-line electrodialytic enrichment of ionic solutes. The method can enrich ionic solutes within seconds by quantitative transfer of analytes from the sample solution to the acceptor solution under an electric field. Because of quantitative ion transfer, the enrichment factor (the ratio of the concentration in the sample and to that in the obtained acceptor solution) only depends on the flow rate ratio of the sample solution to the acceptor solution. The ratios of the concentrations and flow rates are equal for ratios up to 70, 20, and 70 for the tested ionic solutes of inorganic cations, inorganic anions, and heavy metal ions, respectively. The sensitivity of ionic solute determinations is also improved based on the enrichment factor. The method can also simultaneously achieve matrix isolation and enrichment. The method was successively applied to determine the concentrations of trace amounts of chloroacetic acids in tap water. The regulated concentration levels cannot be determined by conventional high-performance liquid chromatography with ultraviolet detection (HPLC-UV) without enrichment. However, enrichment with the present method is effective for determination of tap water quality by improving the limits of detection of HPLC-UV. The standard addition test with real tap water samples shows good recoveries (94.9-109.6%). Copyright © 2017 Elsevier B.V. All rights reserved.

Ethanol fuel improves pitfall traps through rapid sinking and death of captured orthopterans.

PubMed

Szinwelski, N; Yotoko, K S C; Solar, R; Seleme, L R; Sperber, C F

2013-08-01

The choice of killing solutions for pitfall traps can influence sampling and is highly dependent on the objectives of each study. It is becoming increasingly common, however, and is more environmentally friendly, to use the same organisms to extract information for different kinds of studies. The killing solution should, therefore, be able to sample local active organisms, as well as maintain the integrity of their organs, tissues, and macromolecules. In a previous work, we showed that using ethanol fuel as a killing solution maintains the integrity of the specimens and enhances the Orthoptera richness and abundance of samples. In the current study, we evaluated two explanations for this pattern. We set up a field experiment to test whether ethanol fuel is attractive for orthopterans, and we investigated in the laboratory whether individuals of Gryllus sp. sink or die faster in ethanol fuel than in other killing solutions. Our results allowed us to refute the hypotheses of attraction caused by ethanol fuel and showed that the higher sampling efficiency of ethanol fuel is directly linked to the specimens sinking and dying faster than in other killing solutions. Thus, in addition to taxonomic, anatomical, and molecular studies, we recommend ethanol fuel for sampling organisms active in the litter in ecological studies.

The 4D evolution of porosity during ongoing pressure-solution processes in NaCl using x-ray microtomography

NASA Astrophysics Data System (ADS)

Macente, Alice; Fusseis, Florian; Butler, Ian; Tudisco, Erika; Hall, Stephen; Andò, Edward

2016-04-01

Pressure-solution creep is a common deformation mechanism in the upper crust. It represents a mass transfer via dissolution-reprecipitation that critically affects the hydraulic properties of rocks. Successful management of safe radioactive storage sites in rock-salt deposits critically depends on an accurate knowledge of the hydro-mechanical behaviour of salt deposits. Despite numerous lab experiments that have been conducted, many aspects of pressure-solution are still poorly understood. There is little knowledge about the spatio-temporal evolution of porosity and permeability during pressure-solution creep. While rates of pressure-solution creep in silicates and carbonates are slow, which makes laboratory investigations of these materials impractical, compaction experiments have demonstrated that NaCl samples deform sufficiently fast to study pressure-solution creep in a lab environment at room temperature and modest loads. We present results from novel experiments that quantify the 4-dimensional (three spatial dimensions plus time) evolution of pressure-solution processes using in-situ x-ray microtomography. Our experiments are performed in custom made x-ray transparent presses. 5 mm diameter NaCl powder samples with a grain size of 250-300 μm are loaded dry into the press and pre-compacted to produce a starting aggregated material. The sample is then flooded with saturated NaCl solution and loaded uniaxially by means of a pneumatic actuator to a constant uniaxial stress. Different sample mixtures were tested, as well as different uniaxial loads. The resulting deformation of the samples is documented in 3-dimensional microtomographic datasets, acquired at regular time intervals. Image analysis allowed characterization of the microstructural evolution of the NaCl grains and the spatio-temporal distribution of porosity during ongoing mechanical and chemical compaction. The microtomography data have also been analysed with 3D Digital Image Correlation (3D-DIC or DVC) to quantify the fields of displacements in each direction, as well as volumetric and maximum shear strain fields. Following the approach described above, we have been able to quantify and characterize in 4D the evolution of pressure-solution creep and porosity distribution in relation to different sample materials and increasing uniaxial load. The presence of phyllosilicates (biotite) and more competent materials (glass beads) allowed pressure-solution to develop in a much shorter time compared to pure halite sample. The same trend is observed in samples experiencing bigger uniaxial loads (6.6 MPa v 1.6 MPa). We also found that, in the presence of phyllosilicates (biotite), pore size distribution clearly reflects the localisation of pressure-solution processes, as for natural stylolites. In the presence of glass beads, pressure-solution has a greater effect on the pore orientations rather than pore sizes. Our results extend the current understanding of the effect of pressure-solution creep on the mechanical and hydraulic properties of rocks, with implications for natural rock-salt, salt-based repository systems (nuclear and chemical waste storage) and salt mining.

Electro membrane extraction of sodium diclofenac as an acidic compound from wastewater, urine, bovine milk, and plasma samples and quantification by high-performance liquid chromatography.

PubMed

Davarani, Saied Saeed Hosseiny; Pourahadi, Ahmad; Nojavan, Saeed; Banitaba, Mohammad Hossein; Nasiri-Aghdam, Mahnaz

2012-04-13

Electro membrane extraction (EME) as a new microextraction method was applied for extraction of sodium diclofenac (SDF) as an acidic compound from wastewater, urine, bovine milk and plasma samples. Under applied potential of 20 V during the extraction, SDF migrated from a 2.1 mL of sample solution (1mM NaOH), through a supported liquid membrane (SLM), into a 30 μL acceptor solution (10 mM NaOH), exist inside the lumen of the hollow fiber. The negative electrode was placed in the donor solution, and the positive electrode was placed in the acceptor solution. 1-octanol was immobilized in the pores of a porous hollow fiber of polypropylene as SLM. Then the extract was analyzed by means of high-performance liquid chromatography (HPLC) with UV-detection for quantification of SDF. Best results were obtained using a phosphate running electrolyte (10 mM, pH 2.5). The ranges of quantitation for different samples were 8-500 ngmL(-1). Intra- and inter-day RSDs were less than 14.5%. Under the optimized conditions, the preconcentration factors were between 31 and 66 and also the limit of detections (LODs) ranged from 2.7 ng mL(-1) to 5 ng mL(-1) in different samples. This procedure was applied to determine SDF in wastewater, bovine milk, urine and plasma samples (spiked and real samples). Extraction recoveries for different samples were between 44-95% after 5 min of extraction. Copyright © 2012 Elsevier B.V. All rights reserved.

Processing of solid solution, mixed uranium/refractory metal carbides for advanced space nuclear power and propulsion systems

NASA Astrophysics Data System (ADS)

Knight, Travis Warren

Nuclear thermal propulsion (NTP) and space nuclear power are two enabling technologies for the manned exploration of space and the development of research outposts in space and on other planets such as Mars. Advanced carbide nuclear fuels have been proposed for application in space nuclear power and propulsion systems. This study examined the processing technologies and optimal parameters necessary to fabricate samples of single phase, solid solution, mixed uranium/refractory metal carbides. In particular, the pseudo-ternary carbide, UC-ZrC-NbC, system was examined with uranium metal mole fractions of 5% and 10% and corresponding uranium densities of 0.8 to 1.8 gU/cc. Efforts were directed to those methods that could produce simple geometry fuel elements or wafers such as those used to fabricate a Square Lattice Honeycomb (SLHC) fuel element and reactor core. Methods of cold uniaxial pressing, sintering by induction heating, and hot pressing by self-resistance heating were investigated. Solid solution, high density (low porosity) samples greater than 95% TD were processed by cold pressing at 150 MPa and sintering above 2600 K for times longer than 90 min. Some impurity oxide phases were noted in some samples attributed to residual gases in the furnace during processing. Also, some samples noted secondary phases of carbon and UC2 due to some hyperstoichiometric powder mixtures having carbon-to-metal ratios greater than one. In all, 33 mixed carbide samples were processed and analyzed with half bearing uranium as ternary carbides of UC-ZrC-NbC. Scanning electron microscopy, x-ray diffraction, and density measurements were used to characterize samples. Samples were processed from powders of the refractory mono-carbides and UC/UC 2 or from powders of uranium hydride (UH3), graphite, and refractory metal carbides to produce hypostoichiometric mixed carbides. Samples processed from the constituent carbide powders and sintered at temperatures above the melting point of UC showed signs of liquid phase sintering and were shown to be largely solid solutions. Pre-compaction of mixed carbide powders prior to sintering was shown to be necessary to achieve high densities. Hypostoichiometric, samples processed at 2500 K exhibited only the initial stage of sintering and solid solution formation. Based on these findings, a suggested processing methodology is proposed for producing high density, solid solution, mixed carbide fuels. Pseudo-binary, refractory carbide samples hot pressed at 3100 K and 6 MPa showed comparable densities (approximately 85% of the theoretical value) to samples processed by cold pressing and sintering at temperatures of 2800 K.

Liquid chromatographic extraction medium

DOEpatents

Horwitz, E.P.; Dietz, M.L.

1994-09-13

A method and apparatus are disclosed for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water. 1 fig.

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

Jinlong, Lv, E-mail: ljlbuaa@126.com; State Key Lab of New Ceramic and Fine Processing, Tsinghua University, Beijing 100084; Tongxiang, Liang, E-mail: ljltsinghua@126.com

The nanocrystalline pure nickels with different grain orientations were fabricated by direct current electrodeposition process. The grain size slightly decreased with the increasing of electrodeposition solution temperature. However, grain orientation was affected significantly. Comparing with samples obtained at 50 °C and 80 °C, sample obtained at 20 °C had the strongest (111) orientation plane which increased electrochemical corrosion resistance of this sample. At the same time, the lowest (111) orientation plane deteriorated electrochemical corrosion resistance of sample obtained at 50 °C. - Graphical abstract: The increased electrodeposition temperature promoted slightly grain refinement. The grain orientation was affected significantly by electrodepositionmore » solution temperature. The (111) orientation plane of sample increased significantly corrosion resistance. Display Omitted.« less

Acute toxic tests of rainwater samples using Daphnia magna.

PubMed

Sakai, Manabu

2006-06-01

Rainwater samples were collected at Isogo Ward of Yokohama City, Japan, from 23 June to 31 July 2003. The toxic potency of pollutants present in 13 rainwater samples was tested using Daphnia magna. Most test animals died within 48 h in five test solutions that were prepared from rainwater samples. On the other hand, when nonpolar compounds such as pesticides were removed from rainwater samples before the toxic tests, mortalities in all test solutions were less than 10%. Eight kinds of pesticides were detected in rainwater samples. The highest concentration was of dichlorvos, at 0.74 microg/L. Results indicated that insecticides in rainwater sometimes lethally affected D. magna and that toxic potency of insecticides that are present in rainwater constitutes an important problem for environmental protection.

In vitro corrosion behaviour and microhardness of high-copper amalgams with platinum and indium.

PubMed

Ilikli, B G; Aydin, A; Işimer, A; Alpaslan, G

1999-02-01

Samples prepared from Luxalloy, GS-80, Permite-C and Logic and polished after 24 h by traditional methods were stored in polypropylene tubes containing phosphate-buffered saline solutions (pH 3.5 and 6.5) and distilled water. The amounts of mercury, silver, tin, copper, zinc, platinum and indium in the test solutions were determined at the first, second, eighth, 52nd and 78th week by atomic absorption spectrometry. At the end of the eighth week the amalgam samples were removed from solutions and evaluated by Rockwell Super Scial Microhardness tester. Statistically significant low amounts of metal ions were measured for Permite-C containing indium and Logic containing platinum. The microhardness test results showed that there were statistically significant increases in the microhardness of Permite-C and Logic. As a result it was shown that the amalgam samples were affected from corrosion conditions to different degrees. Sample of the Logic group that was stored in distilled water, showed smoother surface properties than other amalgam samples containing high copper. However, it was observed that samples of Permite-C group had the smoothest surface properties.

A new device for collecting time-integrated water samples from springs and surface water bodies

USGS Publications Warehouse

Panno, S.V.; Krapac, I.G.; Keefer, D.A.

1998-01-01

A new device termed the 'seepage sampler' was developed to collect representative water samples from springs, streams, and other surface-water bodies. The sampler collects composite, time-integrated water samples over short (hours) or extended (weeks) periods without causing significant changes to the chemical composition of the samples. The water sample within the sampler remains at the ambient temperature of the water body and does not need to be cooled. Seepage samplers are inexpensive to construct and easy to use. A sampling program of numerous springs and/or streams can be designed at a relatively low cost through the use of these samplers. Transient solutes migrating through such flow systems, potentially unnoticed by periodic sampling, may be detected. In addition, the mass loading of solutes (e.g., agrichemicals) may be determined when seepage samplers are used in conjunction with discharge measurements.

Determination of arsenic in geological materials by electrothermal atomic-absorption spectrometry after hydride generation

USGS Publications Warehouse

Sanzolone, R.F.; Chao, T.T.; Welsch, E.P.

1979-01-01

Rock and soil samples are decomposed with HClO4-HNO3; after further treatment, arsine is generated and absorbed in a dilute silver nitrate solution. Aliquots of this solution are injected into a carbon rod atomizer. Down to 1 ppm As in samples can be determined and there are no significant interferences, even from chromium in soils. Good results were obtained for geochemical reference samples. ?? 1979.

Indirect Competitive Enzyme-Linked Immunosorbent Assay (ELISA).

PubMed

Kohl, Thomas O; Ascoli, Carl A

2017-07-05

The indirect competitive ELISA (indirect cELISA) pits plate-immobilized antigen against antigens in solution for binding to antigen-specific antibody. The antigens in solution are in the test sample and are first incubated with antigen-specific antibody. These antibody-antigen complexes are then added to microtiter plates whose wells have been coated with purified antigen. The wells are washed to remove unbound antigen-antibody complexes and free antigen. A reporter-labeled secondary antibody is then added followed by the addition of substrate. Substrate hydrolysis yields a signal that is inversely proportional to antigen concentration within the sample. This is because when antigen concentration is high in the test sample, most of the antibody is bound before adding the solution to the plate. Most of the antibody remains in solution (as complexes) and is thus washed away before the addition of the reporter-labeled secondary antibody and substrate. Thus, the higher the antigen concentration in the test sample, the weaker the resultant signal in the detection step. The indirect cELISA is often used for competitive detection and quantification of antibodies against viral diseases in biological samples. © 2017 Cold Spring Harbor Laboratory Press.

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

PubMed Central

Field, Christopher R.; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C.; Rose-Pehrsson, Susan L.

2014-01-01

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples. PMID:25145416

Quantitative detection of trace explosive vapors by programmed temperature desorption gas chromatography-electron capture detector.

PubMed

Field, Christopher R; Lubrano, Adam; Woytowitz, Morgan; Giordano, Braden C; Rose-Pehrsson, Susan L

2014-07-25

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Atomic absorption spectrometric determination of copper, zinc, and lead in geological materials

USGS Publications Warehouse

Sanzolone, R.F.; Chao, T.T.

1976-01-01

An atomic absorption spectrometric method is described for the determination of copper, zinc, and lead in geological materials. The sample is digested with HF-HCl-H2O2; the final solution for analysis is in 10 % (v/v) HCl. Copper and zinc are determined directly by aspirating the solution into an air-acetylene flame. A separate aliquot of the solution is used for determination of lead; lead is extracted into TOPO-MIBK from the acidic solution in the presence of iodide and ascorbic acid. For a 0.50-g sample, the limits of determination are 10-2000 p.p.m. for Cu and Zn, and 5-5000 p.p.m. for Pb. As much as 40 % Fe or Ca. and 10 % Al, Mg, or Mn in the sample do not interfere. The proposed method can be applied to the determination of copper, zinc, and lead in a wide range of geological materials including iron- and manganese-rich, calcareous and carbonate samples. ?? 1976.

Stability of pilocarpine hydrochloride and pilocarpine nitrate ophthalmic solutions submitted by U.S. hospitals.

PubMed

Kreienbaum, M A; Page, D P

1986-01-01

The stability of pilocarpine hydrochloride and pilocarpine nitrate ophthalmic solutions stored in hospital pharmacies across the United States was studied. Through a voluntary drug stability program, FDA selected 252 samples (representing 11 manufacturers) from pharmacies representing an adequate cross section of the country. The samples were analyzed for strength, identification, pH, and isopilocarpine and pilocarpic acid impurities. All samples of pilocarpine nitrate met USP requirements. Eight samples of pilocarpine hydrochloride had tablets that exceeded the USP upper limit for strength. All of these samples were in 1- and 2-mL bottles. The amount of isopilocarpine found ranged from 1 to 6.4%, and the amount of pilocarpic acid from 1.5 to 10.1%. Although pilocarpine salts in ophthalmic solution decompose into isopilocarpine and pilocarpic acid under various conditions of storage, an amount of pilocarpine is maintained that is within the compendial limits. However, there is a problem of evaporation from some of the 1- and 2-mL containers in which this product is supplied.

Efficacy of different washing solutions and contact times on the microbial quality and safety of fresh-cut paprika.

PubMed

Das, B Kumar; Kim, Ji Gang; Choi, Ji Weon

2011-10-01

The role of different washing solutions and contact times was investigated to determine their use as potential sanitizers for maintaining the microbial quality and food safety of fresh-cut paprika. Samples were cut into small pieces, washed for both 90 and 180 s by different washing solutions: tap water, chlorinated water (100 mg/L and pH 6.5-7), electrolyzed water (pH 7.2) and ozonized water (4 mg/L). Then, samples were packaged in 50 µm polypropylene bags and stored at 5 °C for 12 days, followed by an evaluation of the antimicrobial efficacy of the treatments. Various quality and safety parameters, such as gas composition, color, off-odor, electrical conductivity and microbial numbers, were evaluated during storage. Results revealed insignificant differences in gas composition, and no off-odor was observed in any of the samples during the storage period. However, longer contact time resulted in slightly lower hue angle value than a short one for all washing solutions. Moreover, samples washed with ozone washings showed lower electrolyte leakage than other washing solutions. Samples washed for longer contact time except those washed in ozonized water showed increased microbial numbers during storage. Hence, it has been concluded that longer contact time with ozone has positive effects, whereas the other washing solutions adversely affect the microbial quality and safety aspects of fresh-cut paprika.

Effects of pore-scale dispersion, degree of heterogeneity, sampling size, and source volume on the concentration moments of conservative solutes in heterogeneous formations

Treesearch

Daniele Tonina; Alberto Bellin

2008-01-01

Pore-scale dispersion (PSD), aquifer heterogeneity, sampling volume, and source size influence solute concentrations of conservative tracers transported in heterogeneous porous formations. In this work, we developed a new set of analytical solutions for the concentration ensemble mean, variance, and coefficient of variation (CV), which consider the effects of all these...

Characterization of solids deposited on the modular caustic-side solvent extraction unit (MCU) coalescer media removed in May and October 2014

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

Fondeur, F. F.

During routine maintenance, the coalescers utilized in the Modular Caustic-Side Solvent Extraction Unit (MCU) processing of Salt Batch 6 and a portion of Salt Batch 7 were sampled and submitted to the Savannah River National Laboratory (SRNL) for characterization, for the purpose of identifying solid phase constituents that may be accumulating in these coalescers. Specifically, two samples were received and characterized: A decontaminated salt solution (DSS) coalescer sample and a strip effluent (SE) coalescer sample. Aliquots of the samples were analyzed by XRD, Fourier Transform Infrared (FTIR) Spectroscopy, SEM, and EDS. Other aliquots of the samples were leached in acidmore » solution, and the leachates were analyzed by ICP-AES. In addition, modeling was performed to provide a basis for comparison of the analytical results.« less

Generalized essential energy space random walks to more effectively accelerate solute sampling in aqueous environment

NASA Astrophysics Data System (ADS)

Lv, Chao; Zheng, Lianqing; Yang, Wei

2012-01-01

Molecular dynamics sampling can be enhanced via the promoting of potential energy fluctuations, for instance, based on a Hamiltonian modified with the addition of a potential-energy-dependent biasing term. To overcome the diffusion sampling issue, which reveals the fact that enlargement of event-irrelevant energy fluctuations may abolish sampling efficiency, the essential energy space random walk (EESRW) approach was proposed earlier. To more effectively accelerate the sampling of solute conformations in aqueous environment, in the current work, we generalized the EESRW method to a two-dimension-EESRW (2D-EESRW) strategy. Specifically, the essential internal energy component of a focused region and the essential interaction energy component between the focused region and the environmental region are employed to define the two-dimensional essential energy space. This proposal is motivated by the general observation that in different conformational events, the two essential energy components have distinctive interplays. Model studies on the alanine dipeptide and the aspartate-arginine peptide demonstrate sampling improvement over the original one-dimension-EESRW strategy; with the same biasing level, the present generalization allows more effective acceleration of the sampling of conformational transitions in aqueous solution. The 2D-EESRW generalization is readily extended to higher dimension schemes and employed in more advanced enhanced-sampling schemes, such as the recent orthogonal space random walk method.

Kevlar reinforced neoprene composites

NASA Technical Reports Server (NTRS)

Penn, B. G.; Daniels, J. G.; White, W. T.; Thompson, L. M.; Clemons, L. M.

1985-01-01

Kevlar/neoprene composites were prepared by two techniques. One method involved the fabrication of a composite from a rubber prepreg prepared by coating Kevlar with viscous neoprene solution and then allowing the solvent to evaporate (solution impregnation technique). The second method involved heating a stack of Kevlar/neoprene sheets at a temperature sufficient to cause polymer flow (melt flow technique). There was no significant difference in the breaking strength and percent elongation for samples obtained by the two methods; however the shear strength obtained for samples fabricated by the solution impregnation technique (275 psi) was significantly higher than that found for the melt flow fabricated samples (110 psi).

Micelle to solvent stacking of organic cations in micellar electrokinetic chromatography with sodium dodecyl sulfate.

PubMed

Quirino, Joselito P; Aranas, Agnes T

2011-10-14

The on-line sample concentration technique, micelle to solvent stacking (MSS), was studied for small organic cations (quaternary ammonium herbicides, β-blocker drugs, and tricyclic antidepressant drugs) in reversed migration micellar electrokinetic chromatography. Electrokinetic chromatography was carried out in fused silica capillaries with a background solution of sodium dodecyl sulfate (SDS) in a low pH phosphate buffer. MSS was performed using anionic SDS micelles in the sample solution for analyte transport and methanol or acetonitrile as organic solvent in the background solution for analyte effective electrophoretic mobility reversal. The solvent also allowed for the separation of the analyte test mixtures. A model for focusing and separation was developed and the mobility reversal that involved micelle collapse was experimentally verified. The effect of analyte retention factor was observed by changing the % organic solvent in the background solution or the concentration of SDS in the sample matrix. With an injection length of 31.9 cm (77% of effective capillary length) for the 7 test drugs, the LODs (S/N=3) of 5-14 ng/mL were 101-346-fold better when compared to typical injection. The linearity (R(2), range=0.025-0.8 μg/mL), intraday and interday repeatability (%RSD, n=10) were ≥0.988, <6.0% and <8.5%, respectively. In addition, analysis of spiked urine samples after 10-fold dilution with the sample matrix yielded LODs=0.02-0.10 μg/mL. These LODs are comparable to published electrophoretic methods that required off-line sample concentration. However, the practicality of the technique for more complex samples will rely on dedicated sample preparation schemes. Copyright © 2011 Elsevier B.V. All rights reserved.

Automated MALDI Matrix Coating System for Multiple Tissue Samples for Imaging Mass Spectrometry

NASA Astrophysics Data System (ADS)

Mounfield, William P.; Garrett, Timothy J.

2012-03-01

Uniform matrix deposition on tissue samples for matrix-assisted laser desorption/ionization (MALDI) is key for reproducible analyte ion signals. Current methods often result in nonhomogenous matrix deposition, and take time and effort to produce acceptable ion signals. Here we describe a fully-automated method for matrix deposition using an enclosed spray chamber and spray nozzle for matrix solution delivery. A commercial air-atomizing spray nozzle was modified and combined with solenoid controlled valves and a Programmable Logic Controller (PLC) to control and deliver the matrix solution. A spray chamber was employed to contain the nozzle, sample, and atomized matrix solution stream, and to prevent any interference from outside conditions as well as allow complete control of the sample environment. A gravity cup was filled with MALDI matrix solutions, including DHB in chloroform/methanol (50:50) at concentrations up to 60 mg/mL. Various samples (including rat brain tissue sections) were prepared using two deposition methods (spray chamber, inkjet). A linear ion trap equipped with an intermediate-pressure MALDI source was used for analyses. Optical microscopic examination showed a uniform coating of matrix crystals across the sample. Overall, the mass spectral images gathered from tissues coated using the spray chamber system were of better quality and more reproducible than from tissue specimens prepared by the inkjet deposition method.

Automated MALDI matrix coating system for multiple tissue samples for imaging mass spectrometry.

PubMed

Mounfield, William P; Garrett, Timothy J

2012-03-01

Uniform matrix deposition on tissue samples for matrix-assisted laser desorption/ionization (MALDI) is key for reproducible analyte ion signals. Current methods often result in nonhomogenous matrix deposition, and take time and effort to produce acceptable ion signals. Here we describe a fully-automated method for matrix deposition using an enclosed spray chamber and spray nozzle for matrix solution delivery. A commercial air-atomizing spray nozzle was modified and combined with solenoid controlled valves and a Programmable Logic Controller (PLC) to control and deliver the matrix solution. A spray chamber was employed to contain the nozzle, sample, and atomized matrix solution stream, and to prevent any interference from outside conditions as well as allow complete control of the sample environment. A gravity cup was filled with MALDI matrix solutions, including DHB in chloroform/methanol (50:50) at concentrations up to 60 mg/mL. Various samples (including rat brain tissue sections) were prepared using two deposition methods (spray chamber, inkjet). A linear ion trap equipped with an intermediate-pressure MALDI source was used for analyses. Optical microscopic examination showed a uniform coating of matrix crystals across the sample. Overall, the mass spectral images gathered from tissues coated using the spray chamber system were of better quality and more reproducible than from tissue specimens prepared by the inkjet deposition method.

Determination of cadmium in grains by isotope dilution ICP-MS and coprecipitation using sample constituents as carrier precipitants.

PubMed

Inagaki, Kazumi; Narukawa, Tomohiro; Yarita, Takashi; Takatsu, Akiko; Okamoto, Kensaku; Chiba, Koichi

2007-10-01

A coprecipitation method using sample constituents as carrier precipitants was developed that can remove molybdenum, which interferes with the determination of cadmium in grain samples via isotope dilution inductively coupled plasma mass spectrometry (ID-ICPMS). Samples were digested with HNO3, HF, and HClO4, and then purified 6 M sodium hydroxide solution was added to generate colloidal hydrolysis compounds, mainly magnesium hydroxide. Cadmium can be effectively separated from molybdenum because the cadmium forms hydroxides and adsorbs onto and/or is occluded in the colloid, while the molybdenum does not form hydroxides or adsorb onto the hydrolysis colloid. The colloid was separated by centrifugation and then dissolved with 0.2 M HNO3 solution to recover the cadmium. The recovery of Cd achieved using the coprecipitation was >97%, and the removal efficiency of Mo was approximately 99.9%. An extremely low procedural blank (below the detection limit of ICPMS) was achieved by purifying the 6 M sodium hydroxide solution via Mg coprecipitation using Mg(NO3)2 solution. The proposed method was applied to two certified reference materials (NIST SRM 1567a wheat flour and SRM 1568a rice flour) and CCQM-P64 soybean powder. Good analytical results with small uncertainties were obtained for all samples. This method is simple and reliable for the determination of Cd in grain samples by ID-ICPMS.

Biocompatibility of hydroxyapatite coatings deposited by pulse electrodeposition technique on the Nitinol superelastic alloy.

PubMed

Marashi-Najafi, F; Khalil-Allafi, J; Etminanfar, M R

2017-07-01

The present study deals with pulse electrochemical deposition of HA on NiTi alloy and in vitro evaluation of coatings. At first step, a thermo-chemical surface modification process was applied to control the Ni release of the alloy. The electrochemical deposition of CaP coatings was examined at both dilute and concentrated solutions. The morphology and the composition of coatings were studied using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Plate like and needle like morphologies were formed for dilute and concentrated solution respectively and HA phase was formed by increasing the pulse current density for both electrolyte. The thickness of the samples was measured using cross sectioning technique. Fibroblast cell culture test on the coated samples revealed that the HA coating obtained by dilute solution shows the best biocompatibility. Also, MTT assay showed the highest cell density and cell proliferation after 5days for the HA coating of dilute solution. The contact angle of samples was measured and the coated samples showed a hydrophilic surface. Soaking the sample in SBF revealed that the crystallization rate of calcium-phosphate compounds is higher on the plate like HA coating as compared to the needle like morphology. The P release of the HA coated samples was measured in a physiological saline solution and the results show that the ions releasing in the plate like coating are less than the needle like coating. It seems that the stability of the plate like coating in biological environments is responsible for the better biocompatibility of the coating. Copyright © 2017 Elsevier B.V. All rights reserved.

Automated sample-changing robot for solution scattering experiments at the EMBL Hamburg SAXS station X33

PubMed Central

Round, A. R.; Franke, D.; Moritz, S.; Huchler, R.; Fritsche, M.; Malthan, D.; Klaering, R.; Svergun, D. I.; Roessle, M.

2008-01-01

There is a rapidly increasing interest in the use of synchrotron small-angle X-ray scattering (SAXS) for large-scale studies of biological macromolecules in solution, and this requires an adequate means of automating the experiment. A prototype has been developed of an automated sample changer for solution SAXS, where the solutions are kept in thermostatically controlled well plates allowing for operation with up to 192 samples. The measuring protocol involves controlled loading of protein solutions and matching buffers, followed by cleaning and drying of the cell between measurements. The system was installed and tested at the X33 beamline of the EMBL, at the storage ring DORIS-III (DESY, Hamburg), where it was used by over 50 external groups during 2007. At X33, a throughput of approximately 12 samples per hour, with a failure rate of sample loading of less than 0.5%, was observed. The feedback from users indicates that the ease of use and reliability of the user operation at the beamline were greatly improved compared with the manual filling mode. The changer is controlled by a client–server-based network protocol, locally and remotely. During the testing phase, the changer was operated in an attended mode to assess its reliability and convenience. Full integration with the beamline control software, allowing for automated data collection of all samples loaded into the machine with remote control from the user, is presently being implemented. The approach reported is not limited to synchrotron-based SAXS but can also be used on laboratory and neutron sources. PMID:25484841

Determination of variables in the prediction of strontium distribution coefficients for selected sediments

USGS Publications Warehouse

Pace, M.N.; Rosentreter, J.J.; Bartholomay, R.C.

2001-01-01

Idaho State University and the US Geological Survey, in cooperation with the US Department of Energy, conducted a study to determine and evaluate strontium distribution coefficients (Kds) of subsurface materials at the Idaho National Engineering and Environmental Laboratory (INEEL). The Kds were determined to aid in assessing the variability of strontium Kds and their effects on chemical transport of strontium-90 in the Snake River Plain aquifer system. Data from batch experiments done to determine strontium Kds of five sediment-infill samples and six standard reference material samples were analyzed by using multiple linear regression analysis and the stepwise variable-selection method in the statistical program, Statistical Product and Service Solutions, to derive an equation of variables that can be used to predict strontium Kds of sediment-infill samples. The sediment-infill samples were from basalt vesicles and fractures from a selected core at the INEEL; strontium Kds ranged from ???201 to 356 ml g-1. The standard material samples consisted of clay minerals and calcite. The statistical analyses of the batch-experiment results showed that the amount of strontium in the initial solution, the amount of manganese oxide in the sample material, and the amount of potassium in the initial solution are the most important variables in predicting strontium Kds of sediment-infill samples.

Effect of compost age and composition on the atrazine removal from solution.

PubMed

Tsui, Lo; Roy, William R

2007-01-02

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters.

Effect of compost age and composition on the atrazine removal from solution

USGS Publications Warehouse

Tsui, L.; Roy, W.R.

2007-01-01

Compost samples from two composting facilities, the Urbana (Illinois) Landscape Recycling Center (ULRC) and Illinois State University (ISU), were selected to examine the effect of compost age on atrazine removal from solution. The ULRC samples were made from yard waste without an additional nitrogen source. The ISU samples were made from yard waste or sawdust with the addition of manure. The 6-month-old ULRC compost had the greater capacity to remove atrazine from solution, which we attributed to its greater organic carbon content. The addition of nitrate into ULRC compost could influence the extent of atrazine removal, but did not have a significant impact on atrazine removal when applied to ISU compost, probably because manure was added to the yard waste to produce the compost. For both ULRC and ISU samples, the presence of sodium azide inhibited atrazine removal, suggesting that microbial activity contributed to the atrazine removal. Metabolic analysis demonstrated that hydroxyatrazine was the major identified metabolite that accumulated in solution before significant ring mineralization could occur. When compared with the ISU compost, the ULRC compost sample had a greater capacity to remove atrazine from solution during the 120 days of study because of the larger humic acid content. The experimental results suggested that less-mature compost may be better suited for environmental applications such as removing atrazine from tile-drainage waters. ?? 2006 Elsevier B.V. All rights reserved.

Compressive sampling of polynomial chaos expansions: Convergence analysis and sampling strategies

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

Hampton, Jerrad; Doostan, Alireza, E-mail: alireza.doostan@colorado.edu

2015-01-01

Sampling orthogonal polynomial bases via Monte Carlo is of interest for uncertainty quantification of models with random inputs, using Polynomial Chaos (PC) expansions. It is known that bounding a probabilistic parameter, referred to as coherence, yields a bound on the number of samples necessary to identify coefficients in a sparse PC expansion via solution to an ℓ{sub 1}-minimization problem. Utilizing results for orthogonal polynomials, we bound the coherence parameter for polynomials of Hermite and Legendre type under their respective natural sampling distribution. In both polynomial bases we identify an importance sampling distribution which yields a bound with weaker dependence onmore » the order of the approximation. For more general orthonormal bases, we propose the coherence-optimal sampling: a Markov Chain Monte Carlo sampling, which directly uses the basis functions under consideration to achieve a statistical optimality among all sampling schemes with identical support. We demonstrate these different sampling strategies numerically in both high-order and high-dimensional, manufactured PC expansions. In addition, the quality of each sampling method is compared in the identification of solutions to two differential equations, one with a high-dimensional random input and the other with a high-order PC expansion. In both cases, the coherence-optimal sampling scheme leads to similar or considerably improved accuracy.« less

Influence of crystal habit on the compression and densification mechanism of ibuprofen

NASA Astrophysics Data System (ADS)

Di Martino, Piera; Beccerica, Moira; Joiris, Etienne; Palmieri, Giovanni F.; Gayot, Anne; Martelli, Sante

2002-08-01

Ibuprofen was recrystallized from several solvents by two different methods: addition of a non-solvent to a drug solution and cooling of a drug solution. Four samples, characterized by different crystal habit, were selected: sample A, sample E and sample T, recrystallized respectively from acetone, ethanol and THF by addition of water as non-solvent and sample M recrystallized from methanol by temperature decrease. By SEM analysis, sample were characterized with the respect of their crystal habit, mean particle diameter and elongation ratio. Sample A appears stick-shaped, sample E acicular with lamellar characteristics, samples T and M polyhedral. DSC and X-ray diffraction studies permit to exclude a polymorphic modification of ibuprofen during crystallization. For all samples micromeritics properties, densification behaviour and compression ability was analysed. Sample M shows a higher densification tendency, evidenciated by its higher apparent and tapped particle density. The ability to densificate is also pointed out by D0' value of Heckel's plot, which indicate the rearrangement of original particles at the initial stage of compression. This fact is related to the crystal habit of sample M, which is characterized by strongly smoothed coins. The increase in powder bed porosity permits a particle-particle interaction of greater extent during the subsequent stage of compression, which allows higher tabletability and compressibility.

Protein crystallography prescreen kit

DOEpatents

Segelke, Brent W.; Krupka, Heike I.; Rupp, Bernhard

2007-10-02

A kit for prescreening protein concentration for crystallization includes a multiplicity of vials, a multiplicity of pre-selected reagents, and a multiplicity of sample plates. The reagents and a corresponding multiplicity of samples of the protein in solutions of varying concentrations are placed on sample plates. The sample plates containing the reagents and samples are incubated. After incubation the sample plates are examined to determine which of the sample concentrations are too low and which the sample concentrations are too high. The sample concentrations that are optimal for protein crystallization are selected and used.

Protein crystallography prescreen kit

DOEpatents

Segelke, Brent W.; Krupka, Heike I.; Rupp, Bernhard

2005-07-12

A kit for prescreening protein concentration for crystallization includes a multiplicity of vials, a multiplicity of pre-selected reagents, and a multiplicity of sample plates. The reagents and a corresponding multiplicity of samples of the protein in solutions of varying concentrations are placed on sample plates. The sample plates containing the reagents and samples are incubated. After incubation the sample plates are examined to determine which of the sample concentrations are too low and which the sample concentrations are too high. The sample concentrations that are optimal for protein crystallization are selected and used.

A novel LCD (coal tar) solution for psoriasis does not discolor naturally light or color-processed hair in an exaggerated exposure test model.

PubMed

Johnson, Colleen; Edison, Brenda; Brouda, Irina; Green, Barbara

2009-09-01

Scalp psoriasis is reported to occur in 50-80% of psoriasis sufferers. Treatment of scalp psoriasis requires special consideration of product esthetics and staining potential due to the presence of hair. To evaluate the potential of a new, marketed liquor carbonis distillate (LCD; coal tar) solution to discolor naturally light or color-processed hair under exaggerated exposure conditions. Samples of naturally light and color-processed hair from a single donor were exposed to LCD solution repeatedly over 14 days and via submergence for 24 h. Color of LCD-treated hair samples was compared with untreated control hair samples. LCD solution did not discolor naturally light or color-processed hair following repeated exposures and 24 h submergence. The marketed LCD solution does not appear to discolor naturally light or color-processed hair.

Properties of mixed molybdenum oxide iridium oxide thin films synthesized by spray pyrolysis

NASA Astrophysics Data System (ADS)

Patil, P. S.; Kawar, R. K.; Sadale, S. B.; Inamdar, A. I.; Deshmukh, H. P.

2006-09-01

Molybdenum-doped iridium oxide thin films have been deposited onto corning glass- and fluorine-doped tin oxide coated corning glass substrates at 350 °C by using a pneumatic spray pyrolysis technique. An aqueous solution of 0.01 M ammonium molybdate was mixed with 0.01 M iridium trichloride solution in different volume proportions and the resultant solution was used as a precursor solution for spraying. The as-deposited samples were annealed at 600 °C in air medium for 1 h. The structural, electrical and optical properties of as-deposited and annealed Mo-doped iridium oxide were studied and values of room temperature electrical resistivity, and thermoelectric power were estimated. The as-deposited samples with 2% Mo doping exhibit more pronounced electrochromism than other samples, including pristine Ir oxide.

Voltammetric analysis apparatus and method

DOEpatents

Almon, A.C.

1993-06-08

An apparatus and method is described for electrochemical analysis of elements in solution. An auxiliary electrode, a reference electrode, and five working electrodes are positioned in a container containing a sample solution. The working electrodes are spaced apart evenly from each other and the auxiliary electrode to minimize any inter-electrode interference that may occur during analysis. An electric potential is applied between the auxiliary electrode and each of the working electrodes. Simultaneous measurements taken of the current flow through each of the working electrodes for each given potential in a potential range are used for identifying chemical elements present in the sample solution and their respective concentrations. Multiple working electrodes enable a more positive identification to be made by providing unique data characteristic of chemical elements present in the sample solution.

No filters, no fridges: a method for preservation of water samples for eDNA analysis.

PubMed

Williams, Kelly E; Huyvaert, Kathryn P; Piaggio, Antoinette J

2016-06-08

Advancements in the detection of environmental DNA (eDNA) for detecting species of interest will likely allow for expanded use of these techniques in the field. One obstacle that continues to hinder applications in the field is the requirement of a cold chain of storage for water samples containing eDNA. While eDNA has been successfully preserved using Longmire's lysis buffer applied to filters, it has yet to be tried with freshwater samples collected for eDNA detection of an invasive species. We tested the utility of Longmire's solution (100 mM Tris, 100 mM EDTA, 10 mM NaCl, 0.5 % SDS, 0.2 % sodium azide) as an additive to freshwater samples for preservation of eDNA. Environmental DNA was effectively preserved in 15 mL water samples with Longmire's solution added; eDNA positive detection was comparable to freezing the samples at -80 °C and occurred out to 56 days at the highest concentration (5 mL Longmire's solution: 15 mL sample water). Medium and low concentrations of Longmire's solution added to 15 mL of sample water generally preserved eDNA out to 56 days but not as well as did freezing or application of the highest concentration of Longmire's lysis buffer. Treatment and degradation time had a significant effect on average DNA concentration of samples, although not the interaction of treatment and time. Perfect detection occurred out to 56 days with the high Longmire's treatment group but DNA concentration was significantly lower at this time point compared to 28 days. We conclude that Longmire's lysis buffer is a viable alternative to cold chain storage that can simplify the collection of eDNA by eliminating the need for filtering and allow more time for sample collection when added at our highest concentration (1 part Longmire's:3 parts water sample), which could translate to an increase in the chances of detecting a rare or elusive species.

TANK 26F SUPERNATANT AND 2F EVAPORATOR EDUCTOR PUMP SAMPLE CHARACTERIZATION RESULTS

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

King, W.; Hay, M.; Coleman, C.

2011-08-23

In an effort to understand the reasons for system plugging problems in the SRS 2F evaporator, supernatant samples were retrieved from the evaporator feed tank (Tank 26F) and solids were collected from the evaporator eductor feed pump for characterization. The variable depth supernatant samples were retrieved from Tank 26F in early December of 2010 and samples were provided to SRNL and the F/H Area laboratories for analysis. Inspection and analysis of the samples at SRNL was initiated in early March of 2011. During the interim period, samples were frequently exposed to temperatures as low as 12 C with daily temperaturemore » fluctuations as high as 10 C. The temperature at the time of sample collection from the waste tank was 51 C. Upon opening the supernatant bottles at SRNL, many brown solids were observed in both of the Tank 26F supernatant samples. In contrast, no solids were observed in the supernatant samples sent to the F/H Area laboratories, where the analysis was completed within a few days after receipt. Based on these results, it is believed that the original Tank 26F supernatant samples did not contain solids, but solids formed during the interim period while samples were stored at ambient temperature in the SRNL shielded cells without direct climate control. Many insoluble solids (>11 wt. % for one sample) were observed in the Tank 26F supernatant samples after three months of storage at SRNL which would not dissolve in the supernatant solution in two days at 51 C. Characterization of these solids along with the eductor pump solids revealed the presence of sodium oxalate and clarkeite (uranyl oxyhydroxide) as major crystalline phases. Sodium nitrate was the dominant crystalline phase present in the unwashed Eductor Pump solids. Crystalline sodium nitrate may have formed during the drying of the solids after filtration or may have been formed in the Tank 26F supernatant during storage since the solution was found to be very concentrated (9-12 M Na{sup +}). Concentrated mineral acids and elevated temperature were required to dissolve all of these solids. The refractory nature of some of the solids is consistent with the presence of metal oxides such as aluminosilicates (observed as a minor phase by XRD). Characterization of the water wash solutions and the digested solids confirmed the presence of oxalate salts in both solid samples. Sulfate enrichment was also observed in the Tank 26F solids wash solution, indicating the presence of sulfate precipitates such as burkeite. OLI modeling of the Tank 26F filtered supernatant composition revealed that sodium oxalate has a very low solubility in this solution. The model predicts that the sodium oxalate solubility in the Tank 26F supernatant is only 0.0011 M at 50 C. The results indicate that the highly concentrated nature of the evaporator feed solution and the addition of oxalate anion to the waste stream each contribute to the formation of insoluble solids in the 2F evaporator system.« less

Manufacturing and shear response characterization of carbon nanofiber modified CFRP using the out-of-autoclave-vacuum-bag-only cure process.

PubMed

McDonald, Erin E; Wallace, Landon F; Hickman, Gregory J S; Hsiao, Kuang-Ting

2014-01-01

The interlaminar shear response is studied for carbon nanofiber (CNF) modified out-of-autoclave-vacuum-bag-only (OOA-VBO) carbon fiber reinforced plastic (CFRP). Commercial OOA-VBO prepregs were coated with a CNF modified epoxy solution and a control epoxy solution without CNF to make CNF modified samples and control samples, respectively. Tensile testing was used to study the in-plane shear performance of [± 45°]4s composite laminates. Significant difference in failure modes between the control and CNF modified CFRPs was identified. The control samples experienced half-plane interlaminar delamination, whereas the CNF modified samples experienced a localized failure in the intralaminar region. Digital image correlation (DIC) surface strain results of the control sample showed no further surface strain increase along the delaminated section when the sample was further elongated prior to sample failure. On the other hand, the DIC results of the CNF modified sample showed that the surface strain increased relatively and uniformly across the CFRP as the sample was further elongated until sample failure. The failure mode evidence along with microscope pictures indicated that the CNF modification acted as a beneficial reinforcement inhibiting interlaminar delamination.

Manufacturing and Shear Response Characterization of Carbon Nanofiber Modified CFRP Using the Out-of-Autoclave-Vacuum-Bag-Only Cure Process

PubMed Central

McDonald, Erin E.; Wallace, Landon F.; Hickman, Gregory J. S.; Hsiao, Kuang-Ting

2014-01-01

The interlaminar shear response is studied for carbon nanofiber (CNF) modified out-of-autoclave-vacuum-bag-only (OOA-VBO) carbon fiber reinforced plastic (CFRP). Commercial OOA-VBO prepregs were coated with a CNF modified epoxy solution and a control epoxy solution without CNF to make CNF modified samples and control samples, respectively. Tensile testingwas used to study the in-plane shear performance of [±45°]4s composite laminates. Significant difference in failure modes between the control and CNF modified CFRPs was identified. The control samples experienced half-plane interlaminar delamination, whereas the CNF modified samples experienced a localized failure in the intralaminar region. Digital image correlation (DIC) surface strain results of the control sample showed no further surface strain increase along the delaminated section when the sample was further elongated prior to sample failure. On the other hand, the DIC results of the CNF modified sample showed that the surface strain increased relatively and uniformly across the CFRP as the sample was further elongated until sample failure. The failure mode evidence along with microscope pictures indicated that the CNF modification acted as a beneficial reinforcement inhibiting interlaminar delamination. PMID:24688435

Direct determination of lead in biological samples by electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS) after furnace-fusion in the sample cuvette-tungsten boat furnace.

PubMed

Okamoto, Y

2000-06-01

The newly conceived electrothermal vaporization (ETV) system using a tungsten boat furnace (TBF) sample cuvette was designed for the direct analysis of solid samples with detection by inductively coupled plasma mass spectrometry (ICP-MS). Into this small sample cuvette, a solid mixture of the biological samples and diammonium hydrogenphosphate powder as a fusion flux was placed and situated on a TBF. Tetramethylammonium hydroxide solution was added to the mixture. After the on-furnace digestion had been completed, the analyte in the cuvette was vaporized and introduced into the ICP mass spectrometer. The solid samples were analyzed by using a calibration curve prepared from the aqueous standard solutions. The detection limit was estimated to be 5.1 pg of lead, which corresponds to 10.2 ng g(-1) of lead in solid samples when a prepared sample amount of 1.0 mg was applied. The relative standard deviation for 8 replicate measurements obtained with 100 pg of lead was calculated to be 6.5%. The analytical results for various biological samples are described.

Lack of latex allergen contamination of solutions withdrawn from vials with natural rubber stoppers.

PubMed

Thomsen, D J; Burke, T G

2000-01-01

The effect on latex allergen contamination and microbial growth of a latex-allergy precaution technique for preparing injectable products was studied. The study consisted of three parts: (1) preparation of 20 samples from vials with latex-containing stoppers in accordance with conventional guidelines, (2) preparation of 20 samples in accordance with latex-allergy precaution guidelines, and (3) preparation of 5 latex-free samples and 1 latex-contaminated sample as negative and positive controls, respectively. The conventional method involved swabbing a vial top with an alcohol prep pad, puncturing the dry natural rubber stopper with an 18-gauge needle attached to a latex-free syringe, and withdrawing the contents of the vial into the syringe. The latex-allergy precaution preparation technique was similar, except that the stopper was removed before the vial contents were withdrawn. There was essentially no difference in latex allergen concentrations between the two drug preparation methods. None of the samples prepared with the standard method supported any microbial growth. One sample prepared with the latex-allergy precaution method grew bacteria. Removal of the dry rubber stopper from vials did not yield solutions with less latex allergen than solutions prepared according to conventional guidelines.

Performance evaluation soil samples utilizing encapsulation technology

DOEpatents

Dahlgran, J.R.

1999-08-17

Performance evaluation soil samples and method of their preparation uses encapsulation technology to encapsulate analytes which are introduced into a soil matrix for analysis and evaluation by analytical laboratories. Target analytes are mixed in an appropriate solvent at predetermined concentrations. The mixture is emulsified in a solution of polymeric film forming material. The emulsified solution is polymerized to form microcapsules. The microcapsules are recovered, quantitated and introduced into a soil matrix in a predetermined ratio to form soil samples with the desired analyte concentration. 1 fig.

Performance evaluation soil samples utilizing encapsulation technology

DOEpatents

Dahlgran, James R.

1999-01-01

Performance evaluation soil samples and method of their preparation using encapsulation technology to encapsulate analytes which are introduced into a soil matrix for analysis and evaluation by analytical laboratories. Target analytes are mixed in an appropriate solvent at predetermined concentrations. The mixture is emulsified in a solution of polymeric film forming material. The emulsified solution is polymerized to form microcapsules. The microcapsules are recovered, quantitated and introduced into a soil matrix in a predetermined ratio to form soil samples with the desired analyte concentration.

Stability of methacholine chloride in isotonic sodium chloride using a capillary electrophoresis assay.

PubMed

Henn, S; Monfort, P; Vigneron, J H; Hoffman, M A; Hoffman, M

1999-10-01

To investigate the stability of methacholine chloride in 0.9% sodium chloride solutions. Methacholine powder was mixed with diluent to a final concentration of 5 and 10 mg/ml. Duplicates of each admixture were divided and stored in glass vials at 25 degrees C, 4 degrees C and -20 degrees C for 12 months. At appropriate times intervals, samples were removed from solutions and analysed. Methacholine concentrations were measured using a high performance capillary electrophoresis assay. No colour or other visual changes were seen in any sample. However, an additional peak was observed in some samples. Methacholine chloride solutions 5 mg/ml were stable in isotonic sodium chloride after refrigeration or freezing over a period of one year; methacholine chloride solutions 10 mg/ml were stable for one year after freezing. The solutions stored at ambient temperature were stable for 35 days and for less than 14 days, respectively, for the 5 and the 10 mg/ml solutions.

Optical high acidity sensor

DOEpatents

Jorgensen, Betty S.; Nekimken, Howard L.; Carey, W. Patrick; O'Rourke, Patrick E.

1997-01-01

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and, a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber.

Optical high acidity sensor

DOEpatents

Jorgensen, B.S.; Nekimken, H.L.; Carey, W.P.; O`Rourke, P.E.

1997-07-22

An apparatus and method for determining acid concentrations in solutions having acid concentrations of from about 0.1 Molar to about 16 Molar is disclosed. The apparatus includes a chamber for interrogation of the sample solution, a fiber optic light source for passing light transversely through the chamber, a fiber optic collector for receiving the collimated light after transmission through the chamber, a coating of an acid resistant polymeric composition upon at least one fiber end or lens, the polymeric composition in contact with the sample solution within the chamber and having a detectable response to acid concentrations within the range of from about 0.1 Molar to about 16 Molar, a measurer for the response of the polymeric composition in contact with the sample solution, and a comparer of the measured response to predetermined standards whereby the acid molarity of the sample solution within the chamber can be determined. Preferably, a first lens is attached to the end of the fiber optic light source, the first lens adapted to collimate light from the fiber optic light source, and a second lens is attached to the end of the fiber optic collector for focusing the collimated light after transmission through the chamber. 10 figs.

Investigation of particle lateral migration in sample-sheath flow of viscoelastic fluid and Newtonian fluid.

PubMed

Yuan, Dan; Zhang, Jun; Yan, Sheng; Peng, Gangrou; Zhao, Qianbin; Alici, Gursel; Du, Hejun; Li, Weihua

2016-08-01

In this work, particle lateral migration in sample-sheath flow of viscoelastic fluid and Newtonian fluid was experimentally investigated. The 4.8-μm micro-particles were dispersed in a polyethylene oxide (PEO) viscoelastic solution, and then the solution was injected into a straight rectangular channel with a deionised (DI) water Newtonian sheath flow. Micro-particles suspended in PEO solution migrated laterally to a DI water stream, but migration in the opposite direction from a DI water stream to a PEO solution stream or from one DI water stream to another DI water stream could not be achieved. The lateral migration of particles depends on the viscoelastic properties of the sample fluids. Furthermore, the effects of channel length, flow rate, and PEO concentration were studied. By using viscoelastic sample flow and Newtonian sheath flow, a selective particle lateral migration can be achieved in a simple straight channel, without any external force fields. This particle lateral migration technique could be potentially used in solution exchange fields such as automated cell staining and washing in microfluidic platforms, and holds numerous biomedical applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An investigation into the stability and sterility of citric acid solutions used for cough reflex testing.

PubMed

Falconer, James R; Wu, Zimei; Lau, Hugo; Suen, Joanna; Wang, Lucy; Pottinger, Sarah; Lee, Elaine; Alazawi, Nawar; Kallesen, Molly; Gargiulo, Derryn A; Swift, Simon; Svirskis, Darren

2014-10-01

Citric acid is used in cough reflex testing in clinical and research settings to assess reflexive cough in patients at risk of swallowing disorders. To address a lack of knowledge in this area, this study investigated the stability and sterility of citric acid solutions. Triplicate solutions of citric acid (0.8 M) in isotonic saline were stored at 4 ± 2 °C for up to 28 days and analysed by high-performance liquid chromatography. Microbiological sterility of freshly prepared samples and bulk samples previously used for 2 weeks within the hospital was determined using a pour plate technique. Microbial survival in citric acid was determined by inoculating Staphylococcus aureus, Escherichia coli, or Candida albicans into citric acid solution and monitoring the number of colony-forming units/mL over 40 min. Citric acid solutions remained stable at 4 °C for 28 days (98.4 ± 1.8 % remained). The freshly prepared and clinical samples tested were sterile. However, viability studies revealed that citric acid solution allows for the survival of C. albicans but not for S. aureus or E. coli. The microbial survival study showed that citric acid kills S. aureus and E. coli but has no marked effect on C. albicans after 40 min. Citric acid samples at 0.8 M remained stable over the 4-week testing period, with viable microbial cells absent from samples tested. However, C. albicans has the ability to survive in citric acid solution if inadvertently introduced in practice. For this reason, in clinical and research practice it is suggested to use single-use aliquots prepared aseptically which can be stored for up to 28 days at 4 °C.

Investigation of hydrophobic substrates for solution residue analysis utilizing an ambient desorption liquid sampling-atmospheric pressure glow discharge microplasma.

PubMed

Paing, Htoo W; Marcus, R Kenneth

2018-03-12

A practical method for preparation of solution residue samples for analysis utilizing the ambient desorption liquid sampling-atmospheric pressure glow discharge optical emission spectroscopy (AD-LS-APGD-OES) microplasma is described. Initial efforts involving placement of solution aliquots in wells drilled into copper substrates, proved unsuccessful. A design-of-experiment (DOE) approach was carried out to determine influential factors during sample deposition including solution volume, solute concentration, number of droplets deposited, and the solution matrix. These various aspects are manifested in the mass of analyte deposited as well as the size/shape of the product residue. Statistical analysis demonstrated that only those initial attributes were significant factors towards the emission response of the analyte. Various approaches were investigated to better control the location/uniformity of the deposited sample. Three alternative substrates, a glass slide, a poly(tetrafluoro)ethylene (PTFE) sheet, and a polydimethylsiloxane (PDMS)-coated glass slide, were evaluated towards the microplasma analytical performance. Co-deposition with simple organic dyes provided an accurate means of determining the location of the analyte with only minor influence on emission responses. The PDMS-coated glass provided the best performance by virtue of its providing a uniform spatial distribution of the residue material. This uniformity yielded an improved limits of detection by approximately 22× for 20 μL and 4 x for 2 μL over the other two substrates. While they operate by fundamentally different processes, this choice of substrate is not restricted to the LS-APGD, but may also be applicable to other AD methods such as DESI, DART, or LIBS. Further developments will be directed towards a field-deployable ambient desorption OES source for quantitative analysis of microvolume solution residues of nuclear forensics importance.

Decision and function problems based on boson sampling

NASA Astrophysics Data System (ADS)

Nikolopoulos, Georgios M.; Brougham, Thomas

2016-07-01

Boson sampling is a mathematical problem that is strongly believed to be intractable for classical computers, whereas passive linear interferometers can produce samples efficiently. So far, the problem remains a computational curiosity, and the possible usefulness of boson-sampling devices is mainly limited to the proof of quantum supremacy. The purpose of this work is to investigate whether boson sampling can be used as a resource of decision and function problems that are computationally hard, and may thus have cryptographic applications. After the definition of a rather general theoretical framework for the design of such problems, we discuss their solution by means of a brute-force numerical approach, as well as by means of nonboson samplers. Moreover, we estimate the sample sizes required for their solution by passive linear interferometers, and it is shown that they are independent of the size of the Hilbert space.

Device for high spatial resolution chemical analysis of a sample and method of high spatial resolution chemical analysis

DOEpatents

Van Berkel, Gary J.

2015-10-06

A system and method for analyzing a chemical composition of a specimen are described. The system can include at least one pin; a sampling device configured to contact a liquid with a specimen on the at least one pin to form a testing solution; and a stepper mechanism configured to move the at least one pin and the sampling device relative to one another. The system can also include an analytical instrument for determining a chemical composition of the specimen from the testing solution. In particular, the systems and methods described herein enable chemical analysis of specimens, such as tissue, to be evaluated in a manner that the spatial-resolution is limited by the size of the pins used to obtain tissue samples, not the size of the sampling device used to solubilize the samples coupled to the pins.

Characterization of potassium bromide crystals grown in the aqueous solution of picric acid

NASA Astrophysics Data System (ADS)

Maheswari, J. Uma; Krishnan, C.; Kalyanaraman, S.; Selvarajan, P.

2016-12-01

Potassium bromide crystals were grown in the aqueous solution of picric acid by slow evaporation technique at room temperature. X-ray Diffraction (XRD) analysis ensures that the grown sample is in Fm3m space group and FCC structure. Energy Dispersive X-ray Spectroscopy (EDX) reveals the presence of elements in the title compound. UV-Vis-NIR spectrum reveals that the grown sample is a promising nonlinear optical (NLO) material. FTIR analysis confirms the functional groups present in the sample. The thermogravimetric (TG) and differential thermogravimetric (DTA) analyses ensure that the sample material is thermally stable up to 160 °C. The second harmonic efficiency of the sample is 1.3 times greater than that of standard KDP. The mechanical strength of the grown sample is estimated by Vickers microhardness tester. The electrical properties were investigated by impedance analysis and the results of various studies of the grown crystals are discussed.

On the continuous dependence with respect to sampling of the linear quadratic regulator problem for distributed parameter systems

NASA Technical Reports Server (NTRS)

Rosen, I. G.; Wang, C.

1990-01-01

The convergence of solutions to the discrete or sampled time linear quadratic regulator problem and associated Riccati equation for infinite dimensional systems to the solutions to the corresponding continuous time problem and equation, as the length of the sampling interval (the sampling rate) tends toward zero (infinity) is established. Both the finite and infinite time horizon problems are studied. In the finite time horizon case, strong continuity of the operators which define the control system and performance index together with a stability and consistency condition on the sampling scheme are required. For the infinite time horizon problem, in addition, the sampled systems must be stabilizable and detectable, uniformly with respect to the sampling rate. Classes of systems for which this condition can be verified are discussed. Results of numerical studies involving the control of a heat/diffusion equation, a hereditary of delay system, and a flexible beam are presented and discussed.

Glass frit nebulizer for atomic spectrometry

USGS Publications Warehouse

Layman, L.R.

1982-01-01

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

On the continuous dependence with respect to sampling of the linear quadratic regulator problem for distributed parameter system

NASA Technical Reports Server (NTRS)

Rosen, I. G.; Wang, C.

1992-01-01

The convergence of solutions to the discrete- or sampled-time linear quadratic regulator problem and associated Riccati equation for infinite-dimensional systems to the solutions to the corresponding continuous time problem and equation, as the length of the sampling interval (the sampling rate) tends toward zero(infinity) is established. Both the finite-and infinite-time horizon problems are studied. In the finite-time horizon case, strong continuity of the operators that define the control system and performance index, together with a stability and consistency condition on the sampling scheme are required. For the infinite-time horizon problem, in addition, the sampled systems must be stabilizable and detectable, uniformly with respect to the sampling rate. Classes of systems for which this condition can be verified are discussed. Results of numerical studies involving the control of a heat/diffusion equation, a hereditary or delay system, and a flexible beam are presented and discussed.

Automation of preparation of nonmetallic samples for analysis by atomic absorption and inductively coupled plasma spectrometry

NASA Technical Reports Server (NTRS)

Wittmann, A.; Willay, G.

1986-01-01

For a rapid preparation of solutions intended for analysis by inductively coupled plasma emission spectrometry or atomic absorption spectrometry, an automatic device called Plasmasol was developed. This apparatus used the property of nonwettability of glassy C to fuse the sample in an appropriate flux. The sample-flux mixture is placed in a composite crucible, then heated at high temperature, swirled until full dissolution is achieved, and then poured into a water-filled beaker. After acid addition, dissolution of the melt, and filling to the mark, the solution is ready for analysis. The analytical results obtained, either for oxide samples or for prereduced iron ores show that the solutions prepared with this device are undistinguished from those obtained by manual dissolutions done by acid digestion or by high temperature fusion. Preparation reproducibility and analytical tests illustrate the performance of Plasmasol.

Optimizing Integrated Terminal Airspace Operations Under Uncertainty

NASA Technical Reports Server (NTRS)

Bosson, Christabelle; Xue, Min; Zelinski, Shannon

2014-01-01

In the terminal airspace, integrated departures and arrivals have the potential to increase operations efficiency. Recent research has developed geneticalgorithm- based schedulers for integrated arrival and departure operations under uncertainty. This paper presents an alternate method using a machine jobshop scheduling formulation to model the integrated airspace operations. A multistage stochastic programming approach is chosen to formulate the problem and candidate solutions are obtained by solving sample average approximation problems with finite sample size. Because approximate solutions are computed, the proposed algorithm incorporates the computation of statistical bounds to estimate the optimality of the candidate solutions. A proof-ofconcept study is conducted on a baseline implementation of a simple problem considering a fleet mix of 14 aircraft evolving in a model of the Los Angeles terminal airspace. A more thorough statistical analysis is also performed to evaluate the impact of the number of scenarios considered in the sampled problem. To handle extensive sampling computations, a multithreading technique is introduced.

Solution-based circuits enable rapid and multiplexed pathogen detection.

PubMed

Lam, Brian; Das, Jagotamoy; Holmes, Richard D; Live, Ludovic; Sage, Andrew; Sargent, Edward H; Kelley, Shana O

2013-01-01

Electronic readout of markers of disease provides compelling simplicity, sensitivity and specificity in the detection of small panels of biomarkers in clinical samples; however, the most important emerging tests for disease, such as infectious disease speciation and antibiotic-resistance profiling, will need to interrogate samples for many dozens of biomarkers. Electronic readout of large panels of markers has been hampered by the difficulty of addressing large arrays of electrode-based sensors on inexpensive platforms. Here we report a new concept--solution-based circuits formed on chip--that makes highly multiplexed electrochemical sensing feasible on passive chips. The solution-based circuits switch the information-carrying signal readout channels and eliminate all measurable crosstalk from adjacent, biomolecule-specific microsensors. We build chips that feature this advance and prove that they analyse unpurified samples successfully, and accurately classify pathogens at clinically relevant concentrations. We also show that signature molecules can be accurately read 2  minutes after sample introduction.

Factor analysis of Wechsler Adult Intelligence Scale-Revised in developmentally disabled persons.

PubMed

Di Nuovo, Santo F; Buono, Serafino

2006-12-01

The results of previous studies on the factorial structure of Wechsler Intelligence Scales are somewhat inconsistent across normal and pathological samples. To study specific clinical groups, such as developmentally disabled persons, it is useful to examine the factor structure in appropriate samples. A factor analysis was carried out using the principal component method and the Varimax orthogonal rotation on the Wechsler Adult Intelligence Scale (WAIS-R) in a sample of 203 developmentally disabled persons, with a mean age of 25 years 4 months. Developmental disability ranged from mild to moderate. Partially contrasting with previous studies on normal samples, results found a two-factor solution. Wechsler's traditional Verbal and Performance scales seems to be more appropriate for this sample than the alternative three-factor solution.

Does the Hertz solution estimate pressures correctly in diamond indentor experiments?

NASA Astrophysics Data System (ADS)

Bruno, M. S.; Dunn, K. J.

1986-05-01

The Hertz solution has been widely used to estimate pressures in a spherical indentor against flat matrix type high pressure experiments. It is usually assumed that the pressure generated when compressing a sample between the indentor and substrate is the same as that generated when compressing an indentor against a flat surface with no sample present. A non-linear finite element analysis of this problem has shown that the situation is far more complex. The actual peak pressure in the sample is highly dependent on plastic deformation and the change in material properties due to hydrostatic pressure. An analysis with two material models is presented and compared with the Hertz solution.

Association between an outbreak strain causing mycoplasma bovis mastitis and its asymptomatic carriage in the herd: a case study from Idaho, USA.

PubMed

Punyapornwithaya, V; Fox, L K; Hancock, D D; Gay, J M; Alldredge, J R

2010-01-01

The objective of this study was to determine the association between mycoplasma mastitis and colonization of mycoplasma organisms at body sites of asymptomatic carriers. The investigation was done in a dairy herd with a first outbreak of mycoplasma mastitis. Milk and swab solution specimens from accessible mucosal surfaces of body sites from cows and replacements were sampled at quarterly intervals (Herd Samplings 1-4). Samples were cultured and Mycoplasma spp. were isolated, speciated and fingerprinted. During Herd Sampling 1 two cows with mycoplasma bovis mastitis were identified and all swabbing solutions of body site samples from 18 of 84 cows and 36 of 77 replacements were positive to Mycoplasma bovis and fingerprinted as the same strain. A case of clinical M. bovis mastitis developed during Herd Sampling 3. During Herd Samplings 2-4, 4 lactating cows and 12 replacements were positive to M. bovis at various body sites with 4 different strains. Three isolates of Mycoplasma californicum were found from swabbing solutions of three cows during Herd Samplings 3 and 4. Only one strain of M. bovis caused mastitis although four strains were isolated from body sites of animals. Isolation of M. bovis from a body site never preceded mastitis. No lactating cow developed mastitis during Herd Sampling 4 although some animals were colonized with the organism. It appears that during the initial outbreak of M. bovis mastitis colonization of body sites by the outbreak strain may be common. However, the prevalence of colonization subsides and colonization does not appear to precede mastitis.

Characterization of long-term elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate beads in vitro by two distinct sample collection methods.

PubMed

Tulipan, Rachel J; Phillips, Heidi; Garrett, Laura D; Dirikolu, Levent; Mitchell, Mark A

2017-05-01

OBJECTIVE To characterize long-term elution of platinum from carboplatin-impregnated calcium sulfate hemihydrate (CI-CSH) beads in vitro by comparing 2 distinct sample collection methods designed to mimic 2 in vivo environments. SAMPLES 162 CI-CSH beads containing 4.6 mg of carboplatin (2.4 mg of platinum/bead). PROCEDURES For method 1, which mimicked an in vivo environment with rapid and complete fluid exchange, each of 3 plastic 10-mL conical tubes contained 3 CI-CSH beads and 5 mL of PBS solution. Eluent samples were obtained by evacuation of all fluid at 1, 2, 3, 6, 9, and 12 hours and 1, 2, 3, 6, 9, 12, 15, 18, 22, 26, and 30 days. Five milliliters of fresh PBS solution was then added to each tube. For method 2, which mimicked an in vivo environment with no fluid exchange, each of 51 tubes (ie, 3 tubes/17 sample collection times) contained 3 CI-CSH beads and 5 mL of PBS solution. Eluent samples were obtained from the assigned tubes for each time point. All samples were analyzed for platinum content by inductively coupled plasma-mass spectrometry. RESULTS Platinum was released from CI-CSH beads for 22 to 30 days. Significant differences were found in platinum concentration and percentage of platinum eluted from CI-CSH beads over time for each method. Platinum concentrations and elution percentages in method 2 samples were significantly higher than those of method 1 samples, except for the first hour measurements. CONCLUSIONS AND CLINICAL RELEVANCE Sample collection methods 1 and 2 may provide estimates of the minimum and maximum platinum release, respectively, from CI-CSH beads in vivo.

Glycan characterization of the NIST RM monoclonal antibody using a total analytical solution: From sample preparation to data analysis.

PubMed

Hilliard, Mark; Alley, William R; McManus, Ciara A; Yu, Ying Qing; Hallinan, Sinead; Gebler, John; Rudd, Pauline M

Glycosylation is an important attribute of biopharmaceutical products to monitor from development through production. However, glycosylation analysis has traditionally been a time-consuming process with long sample preparation protocols and manual interpretation of the data. To address the challenges associated with glycan analysis, we developed a streamlined analytical solution that covers the entire process from sample preparation to data analysis. In this communication, we describe the complete analytical solution that begins with a simplified and fast N-linked glycan sample preparation protocol that can be completed in less than 1 hr. The sample preparation includes labelling with RapiFluor-MS tag to improve both fluorescence (FLR) and mass spectral (MS) sensitivities. Following HILIC-UPLC/FLR/MS analyses, the data are processed and a library search based on glucose units has been included to expedite the task of structural assignment. We then applied this total analytical solution to characterize the glycosylation of the NIST Reference Material mAb 8761. For this glycoprotein, we confidently identified 35 N-linked glycans and all three major classes, high mannose, complex, and hybrid, were present. The majority of the glycans were neutral and fucosylated; glycans featuring N-glycolylneuraminic acid and those with two galactoses connected via an α1,3-linkage were also identified.

Amplifying Dynamic Nuclear Polarization of Frozen Solutions by Incorporating Dielectric Particles

PubMed Central

2014-01-01

There is currently great interest in understanding the limits on NMR signal enhancements provided by dynamic nuclear polarization (DNP), and in particular if the theoretical maximum enhancements can be achieved. We show that over a 2-fold improvement in cross-effect DNP enhancements can be achieved in MAS experiments on frozen solutions by simply incorporating solid particles into the sample. At 9.4 T and ∼105 K, enhancements up to εH = 515 are obtained in this way, corresponding to 78% of the theoretical maximum. We also underline that degassing of the sample is important to achieve highest enhancements. We link the amplification effect to the dielectric properties of the solid material, which probably gives rise to scattering, diffraction, and amplification of the microwave field in the sample. This is substantiated by simulations of microwave propagation. A reduction in sample heating at a given microwave power also likely occurs due to reduced dielectric loss. Simulations indicate that the microwave field (and thus the DNP enhancement) is inhomogeneous in the sample, and we deduce that in these experiments between 5 and 10% of the solution actually yields the theoretical maximum signal enhancement of 658. The effect is demonstrated for a variety of particles added to both aqueous and organic biradical solutions. PMID:25285480

optGpSampler: an improved tool for uniformly sampling the solution-space of genome-scale metabolic networks.

PubMed

Megchelenbrink, Wout; Huynen, Martijn; Marchiori, Elena

2014-01-01

Constraint-based models of metabolic networks are typically underdetermined, because they contain more reactions than metabolites. Therefore the solutions to this system do not consist of unique flux rates for each reaction, but rather a space of possible flux rates. By uniformly sampling this space, an estimated probability distribution for each reaction's flux in the network can be obtained. However, sampling a high dimensional network is time-consuming. Furthermore, the constraints imposed on the network give rise to an irregularly shaped solution space. Therefore more tailored, efficient sampling methods are needed. We propose an efficient sampling algorithm (called optGpSampler), which implements the Artificial Centering Hit-and-Run algorithm in a different manner than the sampling algorithm implemented in the COBRA Toolbox for metabolic network analysis, here called gpSampler. Results of extensive experiments on different genome-scale metabolic networks show that optGpSampler is up to 40 times faster than gpSampler. Application of existing convergence diagnostics on small network reconstructions indicate that optGpSampler converges roughly ten times faster than gpSampler towards similar sampling distributions. For networks of higher dimension (i.e. containing more than 500 reactions), we observed significantly better convergence of optGpSampler and a large deviation between the samples generated by the two algorithms. optGpSampler for Matlab and Python is available for non-commercial use at: http://cs.ru.nl/~wmegchel/optGpSampler/.

Characterization of friction and moisture of porcine lingual tissue in vitro in response to artificial saliva and mouthwash solutions.

PubMed

Zundel, J; Ansari, S A; Trivedi, H M; Masters, J G; Mascaro, S

2018-05-07

The purpose of this research is to characterize the effects of mouthwash solutions on oral friction and moisture using a quantitative in vitro approach. The frictional coefficient of in vitro porcine tongue samples was measured using a magnetic levitation haptic device equipped with a custom tactor designed to mimic human skin. A commercially available moisture meter was used to measure moisture content of the samples. Tongue samples were first tested before treatment, then after application of saliva (either human or artificial), and again after application of 1 of 11 different mouthwash solutions. The data indicate that the samples treated with artificial saliva vs real saliva have comparable friction coefficient and moisture content. Furthermore, the moisture and friction coefficient remain relatively constant for up to 60 minutes after exposure to ambient conditions. Samples treated with artificial saliva have an average friction coefficient in the range of 0.70-0.80. Application of mouthwash solutions produced an average friction coefficient of 0.39-0.49 but retained the high moisture content of the artificial salivary layer. Several mouthwash solutions resulted in statistically significant differences in the friction coefficient relative to each other. The results of this study demonstrate that a magnetic levitation device can be an effective tool for in vitro oral tribology and that artificial saliva is an effective substitute for real saliva in extended in vitro experiments. The application of mouthwash generally reduces the coefficient of friction of the tongue samples while preserving a relatively high moisture level, and some mouthwashes reduce friction significantly more than others. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A new approach for freezing of aqueous solutions under active control of the nucleation temperature.

PubMed

Petersen, Ansgar; Schneider, Hendrik; Rau, Guenter; Glasmacher, Birgit

2006-10-01

An experimental setup for controlled freezing of aqueous solutions is introduced. The special feature is a mechanism to actively control the nucleation temperature via electrofreezing: an ice nucleus generated at a platinum electrode by the application of an electric high voltage pulse initiates the crystallization of the sample. Using electrofreezing, the nucleation temperature in pure water can be precisely adjusted to a desired value over the whole temperature range between a maximum temperature Tn(max) close to the melting point and the temperature of spontaneous nucleation. However, the presence of additives can inhibit the nucleus formation. The influence of hydroxyethylstarch (HES), glucose, glycerol, additives commonly used in cryobiology, and NaCl on Tn(max) were investigated. While the decrease showed to be moderate for the non-ionic additives, the hindrance of nucleation by ionic NaCl makes the direct application of electrofreezing in solutions with physiological salt concentrations impossible. Therefore, in the multi-sample freezing device presented in this paper, the ice nucleus is produced in a separate volume of pure water inside an electrode cap. This way, the nucleus formation becomes independent of the sample composition. Using electrofreezing rather than conventional seeding methods allows automated freezing of many samples under equal conditions. Experiments performed with model solutions show the reliability and repeatability of this method to start crystallization in the test samples at different specified temperatures. The setup was designed to freeze samples of small volume for basic investigations in the field of cryopreservation and freeze-drying, but the mode of operation might be interesting for many other applications where a controlled nucleation of aqueous solutions is of importance.

A mini drivepoint sampler for measuring pore water solute concentrations in the hyporheic zone of sand-bottom streams

USGS Publications Warehouse

Duff, J.H.; Murphy, F.; Fuller, C.C.; Triska, F.J.

1998-01-01

A new method for collecting pore-water samples in sand and gravel streambeds is presented. We developed a mini drivepoint solution sampling (MINIPOINT) technique to collect pore-water samples at 2.5-cm vertical resolution. The sampler consisted of six small-diameter stainless steel drivepoints arranged in a 10-cm-diameter circular array. In a simple procedure, the sampler was installed in the streambed to preset drivepoint depths of 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 cm. Sampler performance was evaluated in the Shingobee River, Minnesota, and Pinal Creek, Arizona, by measuring the vertical gradient of chloride concentration in pore water beneath the streambed that was established by the uninterrupted injection to the stream for 3 d. Pore-water samples were withdrawn from all drivepoints simultaneously. In the first evaluation, the vertical chloride gradient was unchanged at withdrawal rates between 0.3 and 4.0 ml min-1 but was disturbed at higher rates. In the second evaluation, up to 70 ml of pore water was withdrawn from each drivepoint at a withdrawal rate of 2.5 ml min-1 without disturbing the vertical chloride gradient. Background concentrations of other solutes were also determined with MINIPOINT sampling. Steep vertical gradients were present for biologically reactive solutes such as DO, NH4/+, NO3/-, and dissolved organic C in the top 20 cm of the streambed. These detailed solute profiles in the hyporheic zone could not have been determined without a method for close interval vertical sampling that does not disturb natural hydrologic mixing between stream water and groundwater.

Behavior of an Aromatic Heterocyclic Polymer in Salt Solution.

DTIC Science & Technology

1983-08-01

corresponding to the LiCl concentrations in the PBI samples. Z9 fet The viscosities of the 20 samples were determined using a #50 Cannon- Fenske viscometer at... Fenske capillary viscometers thermostated at 30 C. From four to six readings were taken and averaged to determine the average flow time of each solution

Detection of novel visible-light region absorbance peaks in the urine after alkalization in patients with alkaptonuria.

PubMed

Tokuhara, Yasunori; Shukuya, Kenichi; Tanaka, Masami; Mouri, Mariko; Ohkawa, Ryunosuke; Fujishiro, Midori; Takahashi, Tomoo; Okubo, Shigeo; Yokota, Hiromitsu; Kurano, Makoto; Ikeda, Hitoshi; Yamaguchi, Seiji; Inagaki, Shinobu; Ishige-Wada, Mika; Usui, Hiromi; Yatomi, Yutaka; Shimosawa, Tatsuo

2014-01-01

Alkaptonuria, caused by a deficiency of homogentisate 1,2-dioxygenase, results in the accumulation of homogentisic acid (2,5-dihydroxyphenylacetic acid, HGA) in the urine. Alkaptonuria is suspected when the urine changes color after it is left to stand at room temperature for several hours to days; oxidation of homogentisic acid to benzoquinone acetic acid underlies this color change, which is accelerated by the addition of alkali. In an attempt to develop a facile screening test for alkaptonuria, we added alkali to urine samples obtained from patients with alkaptonuria and measured the absorbance spectra in the visible light region. We evaluated the characteristics of the absorption spectra of urine samples obtained from patients with alkaptonuria (n = 2) and compared them with those of urine specimens obtained from healthy volunteers (n = 5) and patients with phenylketonuria (n = 3), and also of synthetic homogentisic acid solution after alkalization. Alkalization of the urine samples and HGA solution was carried out by the addition of NaOH, KOH or NH4OH. The sample solutions were incubated at room temperature for 1 min, followed by measurement of the absorption spectra. Addition of alkali to alkaptonuric urine yielded characteristic absorption peaks at 406 nm and 430 nm; an identical result was obtained from HGA solution after alkalization. The absorbance values at both 406 nm and 430 nm increased in a time-dependent manner. In addition, the absorbance values at these peaks were greater in strongly alkaline samples (NaOH- KOH-added) as compared with those in weakly alkaline samples (NH4OH-added). In addition, the peaks disappeared following the addition of ascorbic acid to the samples. We found two characteristic peaks at 406 nm and 430 nm in both alkaptonuric urine and HGA solution after alkalization. This new quick and easy method may pave the way for the development of an easy method for the diagnosis of alkaptonuria.

Detection of Novel Visible-Light Region Absorbance Peaks in the Urine after Alkalization in Patients with Alkaptonuria

PubMed Central

Tokuhara, Yasunori; Shukuya, Kenichi; Tanaka, Masami; Mouri, Mariko; Ohkawa, Ryunosuke; Fujishiro, Midori; Takahashi, Tomoo; Okubo, Shigeo; Yokota, Hiromitsu; Kurano, Makoto; Ikeda, Hitoshi; Yamaguchi, Seiji; Inagaki, Shinobu; Ishige-Wada, Mika; Usui, Hiromi; Yatomi, Yutaka; Shimosawa, Tatsuo

2014-01-01

Background Alkaptonuria, caused by a deficiency of homogentisate 1,2-dioxygenase, results in the accumulation of homogentisic acid (2,5-dihydroxyphenylacetic acid, HGA) in the urine. Alkaptonuria is suspected when the urine changes color after it is left to stand at room temperature for several hours to days; oxidation of homogentisic acid to benzoquinone acetic acid underlies this color change, which is accelerated by the addition of alkali. In an attempt to develop a facile screening test for alkaptonuria, we added alkali to urine samples obtained from patients with alkaptonuria and measured the absorbance spectra in the visible light region. Methods We evaluated the characteristics of the absorption spectra of urine samples obtained from patients with alkaptonuria (n = 2) and compared them with those of urine specimens obtained from healthy volunteers (n = 5) and patients with phenylketonuria (n = 3), and also of synthetic homogentisic acid solution after alkalization. Alkalization of the urine samples and HGA solution was carried out by the addition of NaOH, KOH or NH4OH. The sample solutions were incubated at room temperature for 1 min, followed by measurement of the absorption spectra. Results Addition of alkali to alkaptonuric urine yielded characteristic absorption peaks at 406 nm and 430 nm; an identical result was obtained from HGA solution after alkalization. The absorbance values at both 406 nm and 430 nm increased in a time-dependent manner. In addition, the absorbance values at these peaks were greater in strongly alkaline samples (NaOH- KOH-added) as compared with those in weakly alkaline samples (NH4OH-added). In addition, the peaks disappeared following the addition of ascorbic acid to the samples. Conclusions We found two characteristic peaks at 406 nm and 430 nm in both alkaptonuric urine and HGA solution after alkalization. This new quick and easy method may pave the way for the development of an easy method for the diagnosis of alkaptonuria. PMID:24466168

Interaction of Sr-90 with site candidate soil for demonstration disposal facility at Serpong

NASA Astrophysics Data System (ADS)

Setiawan, Budi; Mila, Oktri; Safni

2014-03-01

Interaction of radiostrontium (Sr-90) with site candidate soil for demonstration disposal facility to be constructed in the near future at Serpong has been done. This activity is to anticipate the interim storage facility at Serpong nuclear area becomes full off condition, and show to the public how radioactive waste can be well managed with the existing technology. To ensure that the location is save, a reliability study of site candidate soil becomes very importance to be conducted through some experiments consisted some affected parameters such as contact time, effect of ionic strength, and effect of Sr+ ion in solution. Radiostrontium was used as a tracer on the experiments and has role as radionuclide reference in low-level radioactive waste due to its long half-live and it's easy to associate with organism in nature. So, interaction of radiostrontium and soil samples from site becomes important to be studied. Experiment was performed in batch method, and soil sample-solution containing radionuclide was mixed in a 20 ml of PE vial. Ratio of solid: liquid was 10-2 g/ml. Objective of the experiment is to collect the specific characteristics data of radionuclide sorption onto soil from site candidate. Distribution coefficient value was used as indicator where the amount of initial and final activities of radiostrontium in solution was compared. Result showed that equilibrium condition was reached after contact time 10 days with Kd values ranged from 1600-2350 ml/g. Increased in ionic strength in solution made decreased of Kd value into soil sample due to competition of background salt and radiostrontium into soil samples, and increased in Sr ion in solution caused decreased of Kd value in soil sample due to limitation of sorption capacity in soil samples. Fast condition in saturated of metal ion into soil samples was reached due to a simple reaction was occurred.

Effect of solution treatment on stress corrosion cracking behavior of an as-forged Mg-Zn-Y-Zr alloy

PubMed Central

Wang, S. D.; Xu, D. K.; Wang, B. J.; Sheng, L. Y.; Han, E. H.; Dong, C.

2016-01-01

Effect of solid solution treatment (T4) on stress corrosion cracking (SCC) behavior of an as-forged Mg-6.7%Zn-1.3%Y-0.6%Zr (in wt.%) alloy has been investigated using slow strain rate tensile (SSRT) testing in 3.5 wt.% NaCl solution. The results demonstrated that the SCC susceptibility index (ISCC) of as-forged samples was 0.95 and its elongation-to-failure (εf) was only 1.1%. After T4 treatment, the SCC resistance was remarkably improved. The ISCC and εf values of T4 samples were 0.86 and 3.4%, respectively. Fractography and surface observation indicated that the stress corrosion cracking mode for as-forged samples was dominated by transgranular and partially intergranular morphology, whereas the cracking mode for T4 samples was transgranular. In both cases, the main cracking mechanism was associated with hydrogen embrittlement (HE). Through alleviating the corrosion attack of Mg matrix, the influence of HE on the SCC resistance of T4 samples can be greatly suppressed. PMID:27387817

HydroCrowd: a citizen science snapshot to assess the spatial control of nitrogen solutes in surface waters

PubMed Central

Breuer, Lutz; Hiery, Noreen; Kraft, Philipp; Bach, Martin; Aubert, Alice H.; Frede, Hans-Georg

2015-01-01

We organized a crowdsourcing experiment in the form of a snapshot sampling campaign to assess the spatial distribution of nitrogen solutes, namely, nitrate, ammonium and dissolved organic nitrogen (DON), in German surface waters. In particular, we investigated (i) whether crowdsourcing is a reasonable sampling method in hydrology and (ii) what the effects of population density, soil humus content and arable land were on actual nitrogen solute concentrations and surface water quality. The statistical analyses revealed a significant correlation between nitrate and arable land (0.46), as well as soil humus content (0.37) but a weak correlation with population density (0.12). DON correlations were weak but significant with humus content (0.14) and arable land (0.13). The mean contribution of DON to total dissolved nitrogen was 22%. Samples were classified as water quality class II or above, following the European Water Framework Directive for nitrate and ammonium (53% and 82%, respectively). Crowdsourcing turned out to be a useful method to assess the spatial distribution of stream solutes, as considerable amounts of samples were collected with comparatively little effort. PMID:26561200

Effect of hydrogen peroxide on improving the heat stability of whey protein isolate solutions.

PubMed

Sutariya, Suresh; Patel, Hasmukh

2017-05-15

Whey protein isolate (WPI) solutions (12.8%w/w protein) were treated with varying concentrations of H 2 O 2 in the range of 0-0.144 H 2 O 2 to protein ratios (HTPR) by the addition of the required quantity of H 2 O 2 and deionized water. The samples were analyzed for heat stability, rheological properties, denaturation level of β-lactoglobulin (β-LG) and α-lactalbumin (α-LA). The samples treated with H 2 O 2 concentration >0.072 (HTPR) showed significant improvement in the heat stability, and decreased whey protein denaturation and aggregation. The WPI solution treated with H 2 O 2 (>0.072 HTPR) remained in the liquid state after heat treatment at 120°C, whereas the control samples formed gel upon heat treatment. Detailed analysis of these samples suggested that the improvement in the heat stability of H 2 O 2 treated WPI solution was attributed to the significant reduction in the sulfhydryl-disulfide interchange reaction during denaturation of β-LG and α-LA. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of Osmotic Drying with an Aqueous Poly(ethylene Glycol) Liquid Desiccant on Alumina Objects Gelcast with Gelatin

DOE PAGES

Hammel, E. C.; Campa, J. A.; Armbrister, C. E.; ...

2017-09-06

Gelcasting and liquid desiccant drying are novel forming and drying methods used to mitigate common issues associated with the fabrication of complex advanced ceramic objects. Here, the molecular weight and osmotic pressure of aqueous poly(ethylene glycol) (PEG) desiccant solutions were simultaneously varied to understand their influence on the net mass loss rates of gelcast alumina samples prepared using gelatin as a gelling agent. Additionally, the amount of PEG diffusion and water diffusion to and from the ceramic samples after 150 min of immersion in the liquid desiccant was correlated to the solution properties as was the final bulk density ofmore » the sintered samples. Furthermore, solutions with high molecular weight and low osmotic pressure resulted in low PEG gain and low water loss, while solutions with low molecular weight and high osmotic pressure resulted in high PEG gain and high water loss. In some cases, more than 40 wt% of the total water per sample was removed through the liquid desiccant drying process.« less

Bacterial community analysis of Tatsoi cultivated by hydroponics.

PubMed

Koo, Ok K; Kim, Hun; Kim, Hyun J; Baker, Christopher A; Ricke, Steven C

2016-07-02

Tatsoi (Brassica narinosa) is a popular Asian salad green that is mostly consumed as a source of fresh produce. The purpose of this study was to assess the microbial diversity of Tatsoi cultivated in a hydroponic system and of its ecosystem. Tatsoi leaves, nutrient solution, and perlite/earth samples from a trickle feed system (TFS) and an ebb-and-flow system (EFS) were collected and their microbial communities were analyzed by pyrosequencing analysis. The results showed that most bacteria in the leaves from the TFS contained genus Sporosarcina (99.6%), while Rhizobium (60.4%) was dominant in the leaves from the EFS. Genus Paucibacter (18.21%) and Pelomonas (12.37%) were the most abundant microbiota in the nutrient solution samples of the TFS. In the EFS, the nutrient solution samples contained mostly genus Rhodococcus and Acinetobacter. Potential microbial transfer between the leaves and the ecosystem was observed in the EFS, while samples in the TFS were found to share only one species between the leaves, nutrient solution, and earth. Together, these results show that the bacterial populations in Tatsoi and in its ecosystem are highly diverse based on the cultivation system.

Influence of Osmotic Drying with an Aqueous Poly(ethylene Glycol) Liquid Desiccant on Alumina Objects Gelcast with Gelatin

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

Hammel, E. C.; Campa, J. A.; Armbrister, C. E.

Gelcasting and liquid desiccant drying are novel forming and drying methods used to mitigate common issues associated with the fabrication of complex advanced ceramic objects. Here, the molecular weight and osmotic pressure of aqueous poly(ethylene glycol) (PEG) desiccant solutions were simultaneously varied to understand their influence on the net mass loss rates of gelcast alumina samples prepared using gelatin as a gelling agent. Additionally, the amount of PEG diffusion and water diffusion to and from the ceramic samples after 150 min of immersion in the liquid desiccant was correlated to the solution properties as was the final bulk density ofmore » the sintered samples. Furthermore, solutions with high molecular weight and low osmotic pressure resulted in low PEG gain and low water loss, while solutions with low molecular weight and high osmotic pressure resulted in high PEG gain and high water loss. In some cases, more than 40 wt% of the total water per sample was removed through the liquid desiccant drying process.« less

Voltametric analysis apparatus and method

DOEpatents

Almon, Amy C.

1993-01-01

An apparatus and method for electrochemical analysis of elements in solution. An auxiliary electrode 14, a reference electrode 18, and five working electrodes 20, 22, 26, 28, and 30 are positioned in a container 12 containing a sample solution 34. The working electrodes are spaced apart evenly from each other and auxiliary electrode 14 to minimize any inter-electrode interference that may occur during analysis. An electric potential is applied between auxiliary electrode 14 and each of the working electrodes 20, 22, 26, 28, and 30. Simultaneous measurements taken of the current flow through each of the working electrodes for each given potential in a potential range are used for identifying chemical elements present in sample solution 34 and their respective concentrations. Multiple working electrodes enable a more positive identification to be made by providing unique data characteristic of chemical elements present in the sample solution.

Recent developments and future trends in solid phase microextraction techniques towards green analytical chemistry.

PubMed

Spietelun, Agata; Marcinkowski, Łukasz; de la Guardia, Miguel; Namieśnik, Jacek

2013-12-20

Solid phase microextraction find increasing applications in the sample preparation step before chromatographic determination of analytes in samples with a complex composition. These techniques allow for integrating several operations, such as sample collection, extraction, analyte enrichment above the detection limit of a given measuring instrument and the isolation of analytes from sample matrix. In this work the information about novel methodological and instrumental solutions in relation to different variants of solid phase extraction techniques, solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE) and magnetic solid phase extraction (MSPE) is presented, including practical applications of these techniques and a critical discussion about their advantages and disadvantages. The proposed solutions fulfill the requirements resulting from the concept of sustainable development, and specifically from the implementation of green chemistry principles in analytical laboratories. Therefore, particular attention was paid to the description of possible uses of novel, selective stationary phases in extraction techniques, inter alia, polymeric ionic liquids, carbon nanotubes, and silica- and carbon-based sorbents. The methodological solutions, together with properly matched sampling devices for collecting analytes from samples with varying matrix composition, enable us to reduce the number of errors during the sample preparation prior to chromatographic analysis as well as to limit the negative impact of this analytical step on the natural environment and the health of laboratory employees. Copyright © 2013 Elsevier B.V. All rights reserved.

Neutral solute transport across osteochondral interface: A finite element approach.

PubMed

Arbabi, Vahid; Pouran, Behdad; Weinans, Harrie; Zadpoor, Amir A

2016-12-08

Investigation of the solute transfer across articular cartilage and subchondral bone plate could nurture the understanding of the mechanisms of osteoarthritis (OA) progression. In the current study, we approached the transport of neutral solutes in human (slight OA) and equine (healthy) samples using both computed tomography and biphasic-solute finite element modeling. We developed a multi-zone biphasic-solute finite element model (FEM) accounting for the inhomogeneity of articular cartilage (superficial, middle and deep zones) and subchondral bone plate. Fitting the FEM model to the concentration-time curves of the cartilage and the equilibrium concentration of the subchondral plate/calcified cartilage enabled determination of the diffusion coefficients in the superficial, middle and deep zones of cartilage and subchondral plate. We found slightly higher diffusion coefficients for all zones in the human samples as compared to the equine samples. Generally the diffusion coefficient in the superficial zone of human samples was about 3-fold higher than the middle zone, the diffusion coefficient of the middle zone was 1.5-fold higher than that of the deep zone, and the diffusion coefficient of the deep zone was 1.5-fold higher than that of the subchondral plate/calcified cartilage. Those ratios for equine samples were 9, 2 and 1.5, respectively. Regardless of the species considered, there is a gradual decrease of the diffusion coefficient as one approaches the subchondral plate, whereas the rate of decrease is dependent on the type of species. Copyright © 2016 Elsevier Ltd. All rights reserved.

XAS spectroelectrochemistry: reliable measurement of X-ray absorption spectra from redox manipulated solutions at room temperature.

PubMed

Best, Stephen P; Levina, Aviva; Glover, Chris; Johannessen, Bernt; Kappen, Peter; Lay, Peter A

2016-05-01

The design and operation of a low-volume spectroelectrochemical cell for X-ray absorption spectroscopy (XAS) of solutions at room temperature is described. Fluorescence XAS measurements are obtained from samples contained in the void space of a 50 µL reticulated vitreous carbon (sponge) working electrode. Both rapid electrosynthesis and control of the effects of photoreduction are achieved by control over the flow properties of the solution through the working electrode, where a good balance between the rate of consumption of sample and the minimization of decomposition was obtained by pulsing the flow of the solution by 1-2 µL with duty cycle of ∼3 s while maintaining a small net flow rate (26-100 µL h(-1)). The performance of the cell in terms of control of the redox state of the sample and minimization of the effects of photoreduction was demonstrated by XAS measurements of aqueous solutions of the photosensitive Fe(III) species, [Fe(C2O4)3](3-), together with that of the electrogenerated [Fe(C2O4)3](4-) product. The current response from the cell during the collection of XAS spectra provides an independent measure of the stability of the sample of the measurement. The suitability of the approach for the study of small volumes of mM concentrations of protein samples was demonstrated by the measurement of the oxidized and electrochemically reduced forms of cytochrome c.

Probing dissolved organic matter in the critical zone: a comparison between in situ sampling and aqueous soil extracts

NASA Astrophysics Data System (ADS)

Perdrial, J. N.; Perdrial, N.; Harpold, A. A.; Peterson, A. M.; Vasquez, A.; Chorover, J.

2011-12-01

Analyzing dissolved organic matter (DOM) of soil solution constitutes an integral activity in critical zone science as important insights to nutrient and carbon cycling and mineral weathering processes can be gained. Soil solution can be obtained by a variety of approaches such as by in situ zero-tension and tension samplers or by performing soil extracts in the lab. It is generally preferred to obtain soil solution in situ with the least amount of disturbance. However, in water limited environments, such as in southwestern US, in situ sampling is only possible during few hydrologic events and soil extracts are often employed. In order to evaluate the performance of different sampling approaches for OM analysis, results from aqueous soil extracts were compared with in situ samples obtained from suction cups and passive capillary wick samplers (PCAP's). Soil from an OA-horizon of mixed conifer forest Jemez River Basin Critical Zone Observatory (JRB-CZO) in NM was sampled twice and in situ samples from co-located suction cups and PCAPs were collected 7 times during the 2011 snowmelt period. Dissolved organic carbon and nitrogen concentrations (DOC and DN) as well as OM quality (FTIR, fluorescence spectroscopy and PARAFAC) were analyzed. The aqueous soil extracts (solid:solution = 1:5 mass basis) showed highest DOC and lowest DN concentrations whereas samples collected in-situ had lower DOC and higher DN concentrations. PARAFAC analysis using a four component model showed a dominance of fluorescence in region I and II (protein-like fluorescence) for samples collected in situ indicating the presence of more bio-molecules (proteins). In contrast, the dominant PARAFAC component of the soil extract was found in region 3 (fulvic acid-like fluorescence). FTIR analysis showed high intensity band at 1600 cm-1 in the case of the aqueous soil extract that correspond to asymmetric stretching of carboxyl groups. These preliminary results indicate that aqueous soil extracts likely lead to the underestimation of the amount of biomolecules and the overestimation of fulvic acid contents of soil solutions.

[Determination of calcium, magnesium and potassium in nurtured cell by AAS with quick-pulsed nebulization technique and NaOH base digestion].

PubMed

Shi, C; Gao, S; Gun, S

1997-06-01

The sample is digested with 6% NaOH solution and an amount of 50 microl is used for protein content analysis by the method of Comassie Brilliant Blue G250, the residual is diluted with equal 0.4% Lathanurm-EDTA solution. Its Calcium magensium and potassium content are determined by AAS. With quick-pulsed nebulization technique. When a self-made micro-sampling device is used, 20microl of sample volume is needed and it is only the 1/10 approximately 1/20 of the sample volume required for conventional determination. Sensitivity, precision and rate of recovery agree well with those using regular wet ashing method.

[Determination of total mass and morphology analysis of heavy metal in soil with potassium biphthalate-sodium hydroxide by ICP-AES].

PubMed

Qu, Jiao; Yuan, Xing; Cong, Qiao; Wang, Shuang

2008-11-01

Blank soil was used as quality controlling samples, soil sample dealt by potassium biphthalate-sodium hydroxide buffer solution was used as check sample, mixed acid HNO3-HF-HClO4 was chosen to nitrify soil samples, and plasma emission spectrometer (ICP-AES) was used as detecting method. The authors determined the total metal mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the extracted and dealt soil samples, and determined the mass of Mo, Pb, As, Hg, Cr, Cd, Zn, Cu and Ni in the three chemical morphologies, including acid extractable morphology, oxide associated morphology, and organics associated modality. The experimental results indicated that the different pH of potassium biphthalate-sodium hydroxide buffer solution had obvious influence on the total mass of heavy metal and morphology transformation. Except for metal element Pb and Zn, the addition of different pH potassium dihydrogen phosphate-sodium hydroxide buffer solution could accelerate the soil samples nitrification and the total mass determination of heavy metal in the soil samples. The potassium biphthalate-sodium hydroxide buffer solution could facilitate the acid extractable morphology of Cr, Cu, Hg and Pb, oxidation associated morphology of As, Hg, Pb and Zn and the organic associated morphology transforming of As and Hg. At pH 5.8, the maximum acid extractable morphology contents of Cu and Hg were 2.180 and 0.632 mg x kg(-1), respectively; at pH 6.2, the maximal oxidation associated morphology content of Pb could achieve 27.792 mg x kg(-1); at pH 6.0, the maximum organic associated morphology content of heavy metal Hg was 4.715 mg x kg(-1).

Determination of hexavalent chromium in industrial hygiene samples using ultrasonic extraction and flow injection analysis.

PubMed

Wang, J; Ashley, K; Kennedy, E R; Neumeister, C

1997-11-01

A simple, fast, and sensitive method was developed for the determination of hexavalent chromium (CrVI) in workplace samples. Ultrasonic extraction in alkaline solutions with 0.05 M (NH4)2SO4-0.05 M NH3 provided good extraction efficiency of CrVI from the sample and allowed the retention of CrVI on an ion-exchange resin (95%). The CrVI in the sample solution was then separated as an anion from trivalent chromium [CrIII] and other cations by elution from the anion-exchange resin with 0.5 M (NH4)2SO4 in 0.1 M NH3 (pH 8) buffer solution. The eluate was then acidified with hydrochloric acid and complexed with 1,5-diphenylcarbazide reagent prior to flow injection analysis. By analyzing samples with and without oxidation of CrIII to CrVI using CeIV, the method can measure CrVI and total Cr. For optimizing the separation and determination procedure, preliminary trials conducted with two certified reference materials (CRMs 013-050 and NIST 1633a) and three spiked samples (ammonia buffer solution, cellulose ester filters and acid washed sand) indicated that the recovery of CrVI was quantitative (> 90%) with this method. The limit of detection for FIA-UV/VIS determination of the Cr-diphenylcarbazone complex was in the sub-nanogram range (0.11 ng). The technique was also applied successfully to a workplace coal fly ash sample that was collected from a power plant and paint chips that were collected from a heating gas pipe and a university building. The principal advantages of this method are its simplicity, sensitivity, speed and potential portability for field analysis.

Rapid and high-precision measurement of sulfur isotope and sulfur concentration in sediment pore water by multi-collector inductively coupled plasma mass spectrometry.

PubMed

Bian, Xiao-Peng; Yang, Tao; Lin, An-Jun; Jiang, Shao-Yong

2015-01-01

We have developed a technique for the rapid, precise and accurate determination of sulfur isotopes (δ(34)S) by MC-ICP-MS applicable to a range of sulfur-bearing solutions of different sulfur content. The 10 ppm Alfa-S solution (ammonium sulfate solution, working standard of the lab of the authors) was used to bracket other Alfa-S solutions of different concentrations and the measured δ(34)SV-CDT values of Alfa-S solutions deviate from the reference value to varying degrees (concentration effect). The stability of concentration effect has been verified and a correction curve has been constructed based on Alfa-S solutions to correct measured δ(34)SV-CDT values. The curve has been applied to AS solutions (dissolved ammonium sulfate from the lab of the authors) and pore water samples successfully, validating the reliability of our analytical method. This method also enables us to measure the sulfur concentration simultaneously when analyzing the sulfur isotope composition. There is a strong linear correlation (R(2)>0.999) between the sulfur concentrations and the intensity ratios of samples and the standard. We have constructed a regression curve based on Alfa-S solutions and this curve has been successfully used to determine sulfur concentrations of AS solutions and pore water samples. The analytical technique presented here enable rapid, precise and accurate S isotope measurement for a wide range of sulfur-bearing solutions - in particular for pore water samples with complex matrix and varying sulfur concentrations. Also, simultaneous measurement of sulfur concentrations is available. Copyright © 2014 Elsevier B.V. All rights reserved.

Approaches to stream solute load estimation for solutes with varying dynamics from five diverse small watershed

USGS Publications Warehouse

Aulenbach, Brent T.; Burns, Douglas A.; Shanley, James B.; Yanai, Ruth D.; Bae, Kikang; Wild, Adam; Yang, Yang; Yi, Dong

2016-01-01

Estimating streamwater solute loads is a central objective of many water-quality monitoring and research studies, as loads are used to compare with atmospheric inputs, to infer biogeochemical processes, and to assess whether water quality is improving or degrading. In this study, we evaluate loads and associated errors to determine the best load estimation technique among three methods (a period-weighted approach, the regression-model method, and the composite method) based on a solute's concentration dynamics and sampling frequency. We evaluated a broad range of varying concentration dynamics with stream flow and season using four dissolved solutes (sulfate, silica, nitrate, and dissolved organic carbon) at five diverse small watersheds (Sleepers River Research Watershed, VT; Hubbard Brook Experimental Forest, NH; Biscuit Brook Watershed, NY; Panola Mountain Research Watershed, GA; and Río Mameyes Watershed, PR) with fairly high-frequency sampling during a 10- to 11-yr period. Data sets with three different sampling frequencies were derived from the full data set at each site (weekly plus storm/snowmelt events, weekly, and monthly) and errors in loads were assessed for the study period, annually, and monthly. For solutes that had a moderate to strong concentration–discharge relation, the composite method performed best, unless the autocorrelation of the model residuals was <0.2, in which case the regression-model method was most appropriate. For solutes that had a nonexistent or weak concentration–discharge relation (modelR2 < about 0.3), the period-weighted approach was most appropriate. The lowest errors in loads were achieved for solutes with the strongest concentration–discharge relations. Sample and regression model diagnostics could be used to approximate overall accuracies and annual precisions. For the period-weighed approach, errors were lower when the variance in concentrations was lower, the degree of autocorrelation in the concentrations was higher, and sampling frequency was higher. The period-weighted approach was most sensitive to sampling frequency. For the regression-model and composite methods, errors were lower when the variance in model residuals was lower. For the composite method, errors were lower when the autocorrelation in the residuals was higher. Guidelines to determine the best load estimation method based on solute concentration–discharge dynamics and diagnostics are presented, and should be applicable to other studies.

Testing the application of Teflon/quartz soil solution samplers for DOM sampling in the Critical Zone: Field and laboratory approaches

NASA Astrophysics Data System (ADS)

Dolan, E. M.; Perdrial, J. N.; Vazquez, A.; Hernández, S.; Chorover, J.

2010-12-01

Elizabeth Dolan1,2, Julia Perdrial3, Angélica Vázquez-Ortega3, Selene Hernández-Ruiz3, Jon Chorover3 1Deptartment of Soil, Environmental, and Atmospheric Science, University of Missouri. 2Biosphere 2, University of Arizona. 3Deptartment of Soil, Water, and Environmental Science, University of Arizona. Abstract: The behavior of dissolved organic matter (DOM) in soil is important to many biogeochemical processes. Extraction methods to obtain DOM from the unsaturated zone remain a current focus of research as different methods can influence the type and concentration of DOM obtained. Thus, the present comparison study involves three methods for soil solution sampling to assess their impact on DOM quantity and quality: 1) aqueous soil extracts, 2) solution yielded from laboratory installed suction cup samplers and 3) solutions from field installed suction cup samplers. All samples were analyzed for dissolved organic carbon and total nitrogen concentrations. Moreover, DOM quality was analyzed using fluorescence, UV-Vis and FTIR spectroscopies. Results indicate higher DOC values for laboratory extracted DOM: 20 mg/L for aqueous soil extracts and 31 mg/L for lab installed samplers compared to 12 mg/L for field installed samplers. Large variations in C/N ratios were also observed ranging from 1.5 in laboratory extracted DOM to 11 in field samples. Fluorescence excitation-emission matrices of DOM solutions obtained for the laboratory extraction methods showed higher intensities in regions typical for fulvic and humic acid-like materials relative to those extracted in the field. Similarly, the molar absorptivity calculated from DOC concentration normalization of UV-Vis absorbance of the laboratory-derived solutions was significantly higher as well, indicating greater aromaticity. The observed differences can be attributed to soil disturbance associated with obtaining laboratory derived solution samples. Our results indicate that laboratory extraction methods are not comparable to in-situ field soil solution extraction in terms of DOM.

From Field to the Web: Management and Publication of Geoscience Samples in CSIRO Mineral Resources

NASA Astrophysics Data System (ADS)

Devaraju, A.; Klump, J. F.; Tey, V.; Fraser, R.; Reid, N.; Brown, A.; Golodoniuc, P.

2016-12-01

Inaccessible samples are an obstacle to the reproducibility of research and may cause waste of time and resources through duplication of sample collection and management. Within the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mineral Resources there are various research communities who collect or generate physical samples as part of their field studies and analytical processes. Materials can be varied and could be rock, soil, plant materials, water, and even synthetic materials. Given the wide range of applications in CSIRO, each researcher or project may follow their own method of collecting, curating and documenting samples. In many cases samples and their documentation are often only available to the sample collector. For example, the Australian Resources Research Centre stores rock samples and research collections dating as far back as the 1970s. Collecting these samples again would be prohibitively expensive and in some cases impossible because the site has been mined out. These samples would not be easily discoverable by others without an online sample catalog. We identify some of the organizational and technical challenges to provide unambiguous and systematic access to geoscience samples, and present their solutions (e.g., workflow, persistent identifier and tools). We present the workflow starting from field sampling to sample publication on the Web, and describe how the International Geo Sample Number (IGSN) can be applied to identify samples along the process. In our test case geoscientific samples are collected as part of the Capricorn Distal Footprints project, a collaboration project between the CSIRO, the Geological Survey of Western Australia, academic institutions and industry partners. We conclude by summarizing the values of our solutions in terms of sample management and publication.

A Note on Sample Size and Solution Propriety for Confirmatory Factor Analytic Models

ERIC Educational Resources Information Center

Jackson, Dennis L.; Voth, Jennifer; Frey, Marc P.

2013-01-01

Determining an appropriate sample size for use in latent variable modeling techniques has presented ongoing challenges to researchers. In particular, small sample sizes are known to present concerns over sampling error for the variances and covariances on which model estimation is based, as well as for fit indexes and convergence failures. The…

Selective separation of iron from uranium in quantitative determination of traces of uranium by alpha spectrometry in soil/sediment sample.

PubMed

Singhal, R K; Narayanan, Usha; Karpe, Rupali; Kumar, Ajay; Ranade, A; Ramachandran, V

2009-04-01

During this work, controlled redox potential methodology was adopted for the complete separation of traces of uranium from the host matrix of mixed hydroxide of Iron. Precipitates of Fe(+2) and Fe(+3) along with other transuranic elements were obtained from acid leached solution of soil by raising the pH to 9 with 14N ammonia solution. The concentration of the uranium observed in the soil samples was 200-600 ppb, whereas in sediment samples, the concentration range was 61-400 ppb.

Sequential injection spectrophotometric determination of oxybenzone in lipsticks.

PubMed

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

2001-08-01

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

Fire Safety Aspects of Polymeric Materials. Volume 3. Smoke and Toxicity (Combustion Toxicology of Polymers)

DTIC Science & Technology

1978-01-01

Analytical Test Methodology Sampling and analysis of thermal decomposition products are formidable tasks (Rasbash, 1967; Gaskill, 1973; Bankston ...by a flowing solution. A Sample Gas Inlet B Alkali Solution Inlet C Gas and Solution Outlet D Specific Ion Electrode E Reference Electrode E D 1 0 1 2...of radiant heat (Zinn, Powell, Cassanova and Bankston , 1977) ° Seader and Ou have recently proposed a theory relating optical density to particulate

Small-angle solution scattering using the mixed-mode pixel array detector.

PubMed

Koerner, Lucas J; Gillilan, Richard E; Green, Katherine S; Wang, Suntao; Gruner, Sol M

2011-03-01

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 10(7) 10 keV X-rays, a maximum flux rate of 10(8) X-rays pixel(-1) s(-1), and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements.

Small-angle solution scattering using the mixed-mode pixel array detector

PubMed Central

Koerner, Lucas J.; Gillilan, Richard E.; Green, Katherine S.; Wang, Suntao; Gruner, Sol M.

2011-01-01

Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 107 10 keV X-rays, a maximum flux rate of 108 X-rays pixel−1 s−1, and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements. PMID:21335900

Effect of white tea and xylitol on structure and properties of demineralized enamel and jawbone

NASA Astrophysics Data System (ADS)

Auerkari, EI; Kiranahayu, R.; Emerita, D.; Sumariningsih, P.; Sarita, D.; Adiwirya, MS; Suhartono, AW

2018-05-01

White tea and xylitol have been suggested as potential agents to combat dental caries and osteoporosis through enhanced remineralization. This investigation aimed to determine the effects of exposure to white tea with and without xylitol on the structure, composition and hardness of demineralized human dental enamel. For control, samples of untreated and demineralized enamel and samples of untreated rat jawbone were subjected to similar measurements. For demineralization, the enamel samples were immersed for two days at 50°C in an acetate solution (pH 4.0). All samples were then soaked for two weeks at 37°C in a solution containing three different concentrations of white tea, xylitol or both, and an optional addition of the remineralization ingredients including Ca, P and F. For enamel samples without preceding demineralization and without added remineralization ingredients, the results showed highest mean hardness after immersion in a solution containing both white tea and xylitol, practically independently of their applied concentration level. However, for demineralized enamel samples with added remineralization ingredients, the resulting mean hardness was also dependent on concentration of white tea and xylitol. With sufficient concentration, hardness was again higher for combined white tea and xylitol than for either of these used alone.

Application of porous metal enrichment probe sampling to single cell analysis using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS).

PubMed

Fu, Qiang; Tang, Jun; Cui, Meng; Xing, Junpeng; Liu, Zhiqiang; Liu, Shuying

2016-01-01

There is an increasing need for analyzing metabolism in a single cell, which is important to understand the nature of cellular heterogeneity, disease, growth and specialization, etc. However, single cell analysis is often challenging for the traces of samples. In the present study, porous metal enrichment probe sampling combined with matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) has been applied for in situ analysis of live onion epidemic cell. Porous probe, treated by corroding copper wire with HCl, was directly inserted into a single cell to get cell solution. A self-made linear actuator was enough to control the penetration of probe into the target cell accurately. Then samples on the tip of probe were eluted and detected by a commercial MALDI-TOF-MS directly. The formation of porous microstructure on the probe surface increased the adsorptive capacity of cell solution. The sensitivity of porous probe sampling was 6 times higher than uncorroded probes generally. This method provides a sensitive and convenient way for the sampling and detection of single cell solution. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Self-Irradiation Effects on 99Mo Reagents and Products

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

Carson, S.D.; Garcia, M.J.; McDonald, M.J.

1998-10-07

produced in 1996 and shipped to pharmaceutical houses for evaluation of compatibility with oxime solution used to precipitate `?vfo as the oxime complex is both air and light-sensitive, and containing a black precipitate that forms during shipment, presumably as a result of self- irradiation. Addition of sodium hypochlorite to the product solution prior to shipment prevents precipitate formation, indicating the precipitate is a reduced form of `%lo. to remove any precipitate. Duplicate aliquots of the filtered samples were titrated to a phenolphthalein irradiation and afler standing at room temperature for 86.4 hours. Precipitates were washed to a FTIR analysis ofmore » the white precipitate showed it to be alpha benzoin oxime. Since the basic After 86.4 hours, no precipitate had formed in bottles containing sodium hypochlorite. Black precipitate had formed in all bottles that did not contain sodium hypochlorite after 14.4 hours. The precipitate appeared to initially form on the surface of the HDPE sample bottles and Black precipitate was first noticed in sample set 1 after 28.8 hrs' irradiation. No visible sample containing precipitate was kept at room temperature in the original bottle. Precipitate in sample sets 2 and 3. Since no precipitate formed in these bottles, this was equivalent to duplicate samples. Once the precipitate in the 20-mL aliquots that had been set aside had returned to sample sets 1 through 3 and the samples with redissolved precipitate all experienced an average decrease in base strength of 0.013 meq mL-l. Sample 1-C had a decrease of 0.004 meq mL-l and sample 1-D had returned to the initial value of 0.198 meq mL-l. Raman spectra for the black precipitate from samples l-C, 1-D and supplemental sample set 1 Fig. 2. Raman spectra of the black precipitate formed in 9%40 product solutions after 28.8,43.2, 72 and 86.4 hours of `oCo irradiation in Sandia's Gamma Irradiation Facility. increase with time, as seen in the titration of 1-C and 1-D samples. The precipitate does not expect to see precipitate in the glass bottles. The fact that no precipitate is observed when the no precipitate is observed in a glass container is an indication that the rates of molybdenum that precipitate does not form when the solution is in a glass bottle. A hydrogen source other« less

Method for detecting coliform organisms

NASA Technical Reports Server (NTRS)

Nishioka, K.; Nibley, D. A.; Jeffers, E. L.; Brooks, R. L. (Inventor)

1983-01-01

A method and apparatus are disclosed for determining the concentration of coliform bacteria in a sample. The sample containing the coliform bacteria is cultured in a liquid growth medium. The cultured bacteria produce hydrogen and the hydrogen is vented to a second cell containing a buffer solution in which the hydrogen dissolves. By measuring the potential change in the buffer solution caused by the hydrogen, as a function of time, the initial concentration of bacteria in the sample is determined. Alternatively, the potential change in the buffer solution can be compared with the potential change in the liquid growth medium to verify that the potential change in the liquid growth medium is produced primarily by the hydrogen gas produced by the coliform bacteria.

Trace-element analysis of 1000 environmental samples per year using instrumental neutron activation analysis

NASA Technical Reports Server (NTRS)

Sheibley, D. W.

1974-01-01

The technology and methods developed at the Plum Brook Reactor to analyze 1000 samples per year and report data on as many as 56 elements are described. The manpower for the complete analysis of 20 to 24 samples per week required only 3 to 3.5 hours per sample. The solutions to problems encountered in sample preparation, irradiation, and counting are discussed. The automation of data reduction is described. Typical data on various sample matrices are presented.

Radio Frequency Detection and Characterization of Water-Ethanol Solution through Spiral-Coupled Passive Micro-Resonator Sensor.

PubMed

Koirala, Gyan Raj; Dhakal, Rajendra; Kim, Eun-Seong; Yao, Zhao; Kim, Nam-Young

2018-04-03

We present a microfabricated spiral-coupled passive resonator sensor realized through integrated passive device (IPD) technology for the sensitive detection and characterization of water-ethanol solutions. In order to validate the performance of the proposed device, we explicitly measured and analyzed the radio frequency (RF) characteristics of various water-ethanol solution compositions. The measured results showed a drift in the resonance frequency from 1.16 GHz for deionized (DI) water to 1.68 GHz for the solution containing 50% ethanol, whereas the rejection level given by the reflection coefficient decreased from -29.74 dB to -14.81 dB. The obtained limit of detection was 3.82% volume composition of ethanol in solution. The derived loaded capacitance was 21.76 pF for DI water, which gradually decreased to 8.70 pF for the 50% ethanol solution, and the corresponding relative permittivity of the solution decreased from 80.14 to 47.79. The dissipation factor increased with the concentration of ethanol in the solution. We demonstrated the reproducibility of the proposed sensor through iterative measures of the samples and the study of surface morphology. Successive measurement of different samples had no overlapping and had very minimum bias between RF characteristics for each measured sample. The surface profile for bare sensors was retained after the sample test, resulting a root mean square (RMS) value of 11.416 nm as compared to 10.902 nm for the bare test. The proposed sensor was shown to be a viable alternative to existing sensors for highly sensitive water-ethanol concentration detection.

Influence of power ultrasound on the main quality properties and cell viability of osmotic dehydrated cranberries.

PubMed

Nowacka, Malgorzata; Fijalkowska, Aleksandra; Wiktor, Artur; Dadan, Magdalena; Tylewicz, Urszula; Dalla Rosa, Marco; Witrowa-Rajchert, Dorota

2018-02-01

The aim of the study was to investigate the effect of ultrasound treatment in two osmotic solutions, carried out at different time, on some physical properties, antioxidant activity and cell survival of cranberries. Ultrasound treatment was conducted at 21kHz for 30 and 60min in liquid medium: 61.5% sucrose solution and 30% sucrose solution with 0.1% steviol glycosides addition. Some samples before the ultrasound treatment were subjected to cutting or blanching. The results showed that dry matter content and concentration of the dissolved substances increased during ultrasound treatment in osmotic solution, however higher value was observed for treatment in 61.5% sucrose solution and for longer time. Water activity and volume of cranberries did not change after the ultrasonic treatment. Combined treatment led to colour and antioxidant activity alterations as well. A cell viability of whole and cut samples decreased after 60min of osmotic treatment and completely lost in the blanched samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Multiparametric Flow System for the Automated Determination of Sodium, Potassium, Calcium, and Magnesium in Large-Volume Parenteral Solutions and Concentrated Hemodialysis Solutions

PubMed Central

Pistón, Mariela; Dol, Isabel

2006-01-01

A multiparametric flow system based on multicommutation and binary sampling has been designed for the automated determination of sodium, potassium, calcium, and magnesium in large-volume parenteral solutions and hemodialysis concentrated solutions. The goal was to obtain a computer-controlled system capable of determining the four metals without extensive modifications. The system involved the use of five solenoid valves under software control, allowing the establishment of the appropriate flow conditions for each analyte, that is, sample size, dilution, reagent addition, and so forth. Detection was carried out by either flame atomic emission spectrometry (sodium, potassium) or flame atomic absorption spectrometry (calcium, magnesium). The influence of several operating parameters was studied. Validation was carried out by analyzing artificial samples. Figures of merit obtained include linearity, accuracy, precision, and sampling frequency. Linearity was satisfactory: sodium, r 2 >0.999 ( 0.5 – 3.5 g/L), potassium, r 2 >0.996 (50–150 mg/L), calcium, r 2 >0.999 (30–120 mg/L), and magnesium, r 2 >0.999 (20–40 mg/L). Precision ( s r , %, n=5 ) was better than 2.1 %, and accuracy (evaluated through recovery assays) was in the range of 99.8 %– 101.0 % (sodium), 100.8 – 102.5 % (potassium), 97.3 %– 101.3 % (calcium), and 97.1 %– 99.8 % (magnesium). Sampling frequencies ( h −1 ) were 70 (sodium), 75 (potassium), 70 (calcium), and 58 (magnesium). According to the results obtained, the use of an automated multiparametric system based on multicommutation offers several advantages for the quality control of large-volume parenteral solutions and hemodialysis concentrated solutions. PMID:17671619

[Stability study of oxaliplatin and doxorubicin for intraperitoneal administration with hyperthermia].

PubMed

Escudero-Ortiz, V; Duart-Duart, M J; Pérez-Ruixo, C; Pérez-Ruixo, J J; Valenzuela, B

2014-05-01

To evaluate the in vitro physicochemical stability of oxaliplatin and doxorubicin when the in vivo hyperthermic intraperitoneal conditions are reproduced. Three solutions were prepared, A (oxaliplatin 200 mg/L), B(doxorubicin 15 mg/L) and C (oxaliplatin 200 mg/L with doxorubicin 15mg/L) in glucose 5%. The three solutions were subjected to the maximum temperature reached in vivo (49° C) for two hours. Physical stability was focused on visual control of particles or precipitates in solutions, discharge of gases, odor and color. Samples were taken every 15 minutes and the chemical stability was evaluated by determining the concentration of oxaliplatin and doxorubicin remaining in the samples. Oxaliplatin concentrations were determined by atomic absorption graphite chamber while doxorubicin was determined by high performance liquid chromatography.The chemical stability criteria selected was the one described by the American Pharmacopoeia, which sets a permissible variation range between the 90-110% of the initial concentration. During the assay there was no appearance of particles, precipitates in the samples, discharge of gases, nor colour changes in the solutions. The samples showed a remaining concentration of oxaliplatin and doxorubicin within the 90-110% limit. The stability of the samples that follow to two cycles of freeze-thaw after hyperthermia was also found within the specified limits. A, B and c solutions in 5% glucose, are physically and chemically stable at 49° C for two hours. Under these conditions, these solutions could be used with guarantees of stability in patients with peritoneal carcinomatosis subsidiary of intraperitoneal hyperthermic chemotherapy based in these antineoplastic agents. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

Energy dispersive X-ray fluorescence determination of cadmium in uranium matrix using Cd Kα line excited by continuum

NASA Astrophysics Data System (ADS)

Dhara, Sangita; Misra, N. L.; Aggarwal, S. K.; Venugopal, V.

2010-06-01

An energy dispersive X-ray fluorescence method for determination of cadmium (Cd) in uranium (U) matrix using continuum source of excitation was developed. Calibration and sample solutions of cadmium, with and without uranium were prepared by mixing different volumes of standard solutions of cadmium and uranyl nitrate, both prepared in suprapure nitric acid. The concentration of Cd in calibration solutions and samples was in the range of 6 to 90 µg/mL whereas the concentration of Cd with respect to U ranged from 90 to 700 µg/g of U. From the calibration solutions and samples containing uranium, the major matrix uranium was selectively extracted using 30% tri-n-butyl phosphate in dodecane. Fixed volumes (1.5 mL) of aqueous phases thus obtained were taken directly in specially designed in-house fabricated leak proof Perspex sample cells for the energy dispersive X-ray fluorescence measurements and calibration plots were made by plotting Cd Kα intensity against respective Cd concentration. For the calibration solutions not having uranium, the energy dispersive X-ray fluorescence spectra were measured without any extraction and Cd calibration plots were made accordingly. The results obtained showed a precision of 2% (1 σ) and the results deviated from the expected values by < 4% on average.

Determination of phosphorus in small amounts of protein samples by ICP-MS.

PubMed

Becker, J Sabine; Boulyga, Sergei F; Pickhardt, Carola; Becker, J; Buddrus, Stefan; Przybylski, Michael

2003-02-01

Inductively coupled plasma mass spectrometry (ICP-MS) is used for phosphorus determination in protein samples. A small amount of solid protein sample (down to 1 micro g) or digest (1-10 micro L) protein solution was denatured in nitric acid and hydrogen peroxide by closed-microvessel microwave digestion. Phosphorus determination was performed with an optimized analytical method using a double-focusing sector field inductively coupled plasma mass spectrometer (ICP-SFMS) and quadrupole-based ICP-MS (ICP-QMS). For quality control of phosphorus determination a certified reference material (CRM), single cell proteins (BCR 273) with a high phosphorus content of 26.8+/-0.4 mg g(-1), was analyzed. For studies on phosphorus determination in proteins while reducing the sample amount as low as possible the homogeneity of CRM BCR 273 was investigated. Relative standard deviation and measurement accuracy in ICP-QMS was within 2%, 3.5%, 11% and 12% when using CRM BCR 273 sample weights of 40 mg, 5 mg, 1 mg and 0.3 mg, respectively. The lowest possible sample weight for an accurate phosphorus analysis in protein samples by ICP-MS is discussed. The analytical method developed was applied for the analysis of homogeneous protein samples in very low amounts [1-100 micro g of solid protein sample, e.g. beta-casein or down to 1 micro L of protein or digest in solution (e.g., tau protein)]. A further reduction of the diluted protein solution volume was achieved by the application of flow injection in ICP-SFMS, which is discussed with reference to real protein digests after protein separation using 2D gel electrophoresis.The detection limits for phosphorus in biological samples were determined by ICP-SFMS down to the ng g(-1) level. The present work discusses the figure of merit for the determination of phosphorus in a small amount of protein sample with ICP-SFMS in comparison to ICP-QMS.

Influence of pollution control on lead inhalation bioaccessibility in PM2.5: A case study of 2014 Youth Olympic Games in Nanjing.

PubMed

Li, Shi-Wei; Li, Hong-Bo; Luo, Jun; Li, Hui-Ming; Qian, Xin; Liu, Miao-Miao; Bi, Jun; Cui, Xin-Yi; Ma, Lena Q

2016-09-01

Pollution controls were implemented to improve the air quality for the 2014 Youth Olympic Games (YOG) in Nanjing. To investigate the influence of pollution control on Pb inhalation bioaccessibility in PM2.5, samples were collected before, during, and after YOG. The objectives were to identify Pb sources in PM2.5 using stable isotope fingerprinting technique and compare Pb inhalation bioaccessibility in PM2.5 using two simulated lung fluids. While artificial lysosomal fluid (ALF) simulates interstitial fluid at pH 7.4, Gamble's solution simulates fluid in alveolar macrophages at pH 4.5. The Pb concentration in PM2.5 samples during YOG (88.2ngm(-3)) was 44-48% lower than that in non-YOG samples. Based on stable Pb isotope ratios, Pb in YOG samples was mainly from coal combustion while Pb in non-YOG samples was from coal combustion and smelting activities. While Pb bioaccessibility in YOG samples was lower than those in non-YOG samples (59-79% vs. 55-87%) by ALF, it was higher than those in non-YOG samples (11-29% vs. 5.3-21%) based on Gamble's solution, attributing to the lower pH and organic acids in ALF. Different Pb bioaccessibility in PM2.5 between samples resulted from changes in Pb species due to pollution control. PbSO4 was the main Pb species in PM2.5 from coal combustion, which was less soluble in ALF than PbO from smelting activities, but more soluble in Gamble's solution. This study showed it is important to consider Pb bioaccessibility during pollution control as source control not only reduced Pb contamination in PM2.5 but also influenced Pb bioaccessibility. Published by Elsevier Ltd.

Validation of an automated fluorescein method for determining bromide in water

USGS Publications Warehouse

Fishman, M. J.; Schroder, L.J.; Friedman, L.C.

1985-01-01

Surface, atmospheric precipitation and deionized water samples were spiked with ??g l-1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0.015 to 0.5 mg l-1 of bromide. The correlation coefficient for the same sets of paired data is 0.9987. Recovery data, except for the surface water samples to which 0.005 mg l-1 of bromide was added, range from 89 to 112%. There appears to be no loss of bromide from solution in either type of container.Surface, atmospheric precipitation and deionized water samples were spiked with mu g l** minus **1 concentrations of bromide, and the solutions stored in polyethylene and polytetrafluoroethylene bottles. Bromide was determined periodically for 30 days. Automated fluorescein and ion chromatography methods were used to determine bromide in these prepared samples. Analysis of the data by the paired t-test indicates that the two methods are not significantly different at a probability of 95% for samples containing from 0. 015 to 0. 5 mg l** minus **1 of bromide. The correlation coefficient for the same sets of paired data is 0. 9987. Recovery data, except for the surface water samples to which 0. 005 mg l** minus **1 of bromide was added, range from 89 to 112%. Refs.

Salting-out assisted liquid-liquid extraction combined with gas chromatography-mass spectrometry for the determination of pyrethroid insecticides in high salinity and biological samples.

PubMed

Niu, Zongliang; Yu, Chunwei; He, Xiaowen; Zhang, Jun; Wen, Yingying

2017-09-05

A salting-out assisted liquid-liquid extraction (SALLE) combined with gas chromatography-mass spectrometry (GC-MS) method was developed for the determination of four pyrethroid insecticides (PYRs) in high salinity and biological samples. Several parameters including sample pH, salting-out solution volume and salting-out solution pH influencing the extraction efficiency were systematically investigated with the aid of orthogonal design. The optimal extraction conditions of SALLE were: 4mL of salting-out solution with pH=4 and the sample pH=3. Under the optimum extraction and determination conditions, good responses for four PYRs were obtained in a range of 5-5000ng/mL, with linear coefficients greater than 0.998. The recoveries of the four PYRs ranged from 74% to 110%, with standard deviations ranging from 1.8% to 9.8%. The limits of detection based on a signal-to-noise ratio of 3 were between 1.5-60.6ng/mL. The method was applied to the determination of PYRs in urine, seawater and wastewater samples with a satisfactory result. The results demonstrated that this SALLE-GC-MS method was successfully applied to determine PYRs in high salinity and biological samples. SALLE avoided the need for the elimination of salinity and protein in the sample matrix, as well as clean-up of the extractant. Most of all, no centrifugation or any special apparatus are required, make this a promising method for rapid sample preparation procedure. Copyright © 2017 Elsevier B.V. All rights reserved.

Liquid and gel electrodes for transverse free flow electrophoresis

DOEpatents

Jung, Byoungsok; Rose, Klint A; Shusteff, Maxim; Persat, Alexandre; Santiago, Juan

2015-04-07

The present invention provides a mechanism for separating or isolating charged particles under the influence of an electric field without metal electrodes being in direct contact with the sample solution. The metal electrodes normally in contact with the sample are replaced with high conductivity fluid electrodes situated parallel and adjacent to the sample. When the fluid electrodes transmit the electric field across the sample, particles within the sample migrate according to their electrophoretic mobility.

Fluid sampling system

DOEpatents

Houck, Edward D.

1994-01-01

An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank.

Fluid sampling system

DOEpatents

Houck, E.D.

1994-10-11

An fluid sampling system allows sampling of radioactive liquid without spillage. A feed tank is connected to a liquid transfer jet powered by a pumping chamber pressurized by compressed air. The liquid is pumped upwardly into a sampling jet of a venturi design having a lumen with an inlet, an outlet, a constricted middle portion, and a port located above the constricted middle portion. The liquid is passed under pressure through the constricted portion causing its velocity to increase and its pressure to be decreased, thereby preventing liquid from escaping. A septum sealing the port can be pierced by a two pointed hollow needle leading into a sample bottle also sealed by a pierceable septum affixed to one end. The bottle is evacuated by flow through the sample jet, cyclic variation in the sampler jet pressure periodically leaves the evacuated bottle with lower pressure than that of the port, thus causing solution to pass into the bottle. The remaining solution in the system is returned to the feed tank via a holding tank. 4 figs.

Comparative study on Ga1-xZnxN1-yOy oxynitride synthesized by different techniques for application in photocatalytic hydrogen production

NASA Astrophysics Data System (ADS)

Menon, Sumithra Sivadas; Baskar, K.; Singh, Shubra

2017-06-01

Hydrogen evolution by overall water splitting has emerged as a potential method for green energy generation due to the introduction of highly efficient photocatalysts active under visible region of spectra. In the present work, we focus on a comparative study of the properties of Ga1-xZnxN1-yOy oxynitride samples synthesized by two techniques and their effect on the sample properties. The samples were prepared by both traditional nitridation technique and solution combustion method. Room temperature photoluminescence studies revealed the introduction of additional energy levels above the valence band which in turns broadens the valence band and subsequently reduces the band gap. The band gap narrowing was further confirmed using diffuse reflectance spectroscopy and Valence band X-ray photoelectron spectroscopy (VB-XPS). It was also realized from VB XPS that the reduction of band gap in both the samples was due to upshift of valence band without affecting the conduction band. The presence of disorder activated modes in the samples was examined using temperature dependent Raman spectroscopy. In this work we corroborate the theoretical prediction reported by Al-Jassim et. al that the bandgap narrowing mechanism in ZnO rich solid solution and GaN rich solid solution is asymmetric and a significant bandgap reduction could be observed for ZnO rich solid solution than GaN rich.

Comparison of laser ablation and dried solution aerosol as sampling systems in inductively coupled plasma mass spectrometry.

PubMed

Coedo, A G; Padilla, I; Dorado, M T

2004-12-01

This paper describes a study designed to determine the possibility of using a dried aerosol solution for calibration in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The relative sensitivities of tested materials mobilized by laser ablation and by aqueous nebulization were established, and the experimentally determined relative sensitivity factors (RSFs) were used in conjunction with aqueous calibration for the analysis of solid steel samples. To such a purpose a set of CRM carbon steel samples (SS-451/1 to SS-460/1) were sampled into an ICP-MS instrument by solution nebulization using a microconcentric nebulizer with membrane desolvating (D-MCN) and by laser ablation (LA). Both systems were applied with the same ICP-MS operating parameters and the analyte signals were compared. The RSF (desolvated aerosol response/ablated solid response) values were close to 1 for the analytes Cr, Ni, Co, V, and W, about 1.3 for Mo, and 1.7 for As, P, and Mn. Complementary tests were carried out using CRM SS-455/1 as a solid standard for one-point calibration, applying LAMTRACE software for data reduction and quantification. The analytical results are in good agreement with the certified values in all cases, showing that the applicability of dried aerosol solutions is a good alternative calibration system for laser ablation sampling.

Results of Hg speciation testing on MCU strip effluent hold tank (SEHT) and decontaminated salt solution hold tank (DSSHT) materials

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

Bannochie, C. J.

2015-09-17

The Savannah River National Laboratory (SRNL) was tasked with preparing and shipping samples for Hg speciation by Eurofins Frontier Global Sciences, Inc. in Seattle, WA on behalf of the Savannah River Remediation (SRR) Mercury Task Team.i,ii The tenth shipment of samples was designated to include Modular Caustic Side Solvent Extraction Unit (MCU) Strip Effluent Hold Tank (SEHT) and MCU Decontaminated Salt Solution Hold Tank (DSSHT) materials from processing Salt Batch 7b. The MCU SEHT (MCU-15-722) and DSSHT (MCU-15-709) samples were pulled on June 15, 2015. All MCU samples were received at SRNL on June 16, 2015. The DSSHT sample wasmore » moved the same day to refrigeration, while the SEHT sample was placed in the Shielded Cells. On July 9, 2015 it was opened and an aliquot diluted 1:100 with Eurofins deionized water and a portion of the diluted sample transferred to a Teflon® bottle prior to moving it to refrigeration that same day. All samples were kept in the dark and refrigerated until final dilutions were prepared for shipment to Eurofins.« less

Sample collection system for gel electrophoresis

DOEpatents

Olivares, Jose A.; Stark, Peter C.; Dunbar, John M.; Hill, Karen K.; Kuske, Cheryl R.; Roybal, Gustavo

2004-09-21

An automatic sample collection system for use with an electrophoretic slab gel system is presented. The collection system can be used with a slab gel have one or more lanes. A detector is used to detect particle bands on the slab gel within a detection zone. Such detectors may use a laser to excite fluorescently labeled particles. The fluorescent light emitted from the excited particles is transmitted to low-level light detection electronics. Upon the detection of a particle of interest within the detection zone, a syringe pump is activated, sending a stream of buffer solution across the lane of the slab gel. The buffer solution collects the sample of interest and carries it through a collection port into a sample collection vial.

Size exclusion chromatography for analyses of fibroin in silk: optimization of sampling and separation conditions

NASA Astrophysics Data System (ADS)

Pawcenis, Dominika; Koperska, Monika A.; Milczarek, Jakub M.; Łojewski, Tomasz; Łojewska, Joanna

2014-02-01

A direct goal of this paper was to improve the methods of sample preparation and separation for analyses of fibroin polypeptide with the use of size exclusion chromatography (SEC). The motivation for the study arises from our interest in natural polymers included in historic textile and paper artifacts, and is a logical response to the urgent need for developing rationale-based methods for materials conservation. The first step is to develop a reliable analytical tool which would give insight into fibroin structure and its changes caused by both natural and artificial ageing. To investigate the influence of preparation conditions, two sets of artificially aged samples were prepared (with and without NaCl in sample solution) and measured by the means of SEC with multi angle laser light scattering detector. It was shown that dialysis of fibroin dissolved in LiBr solution allows removal of the salt which destroys stacks chromatographic columns and prevents reproducible analyses. Salt rich (NaCl) water solutions of fibroin improved the quality of chromatograms.

Effect of preheat repetition on color stability of methacrylate- and silorane-based composite resins.

PubMed

Abed Kahnamouei, Mehdi; Gholizadeh, Sarah; Rikhtegaran, Sahand; Daneshpooy, Mehdi; Kimyai, Soodabeh; Alizadeh Oskoee, Parnian; Rezaei, Yashar

2017-01-01

Background. The aim of this study was to investigate the effect of preheating methacrylate- and silorane-based composite resins on their color stability up to 40 times at 55‒60°C. Methods. Seventy-six methacrylate and silorane-based composite resin samples, with a diameter of 10 mm and a height of 2 mm, were divided into 4 groups (n=19). After the samples were prepared, their color parameters were determined using a reflective spectrophotometer. The composite resin samples were separately stored in a solution of tea for 40 consecutive days. Then the samples underwent a color determination procedure again using a spectrophotometer and color changes were recorded. Finally two-way ANOVA was used to study the effect of composite temperature on its staining (P<0.05). Independent-samples t-test was used to evaluate changes in conversion rates of preheated composite resin samples compared to non-heated samples at P=0.005 and P=0.029 for silorane-based and Z250 composite resin samples, respectively. Results. Both composite resin type (P=0.014) and preheating (P<0.001) had significant effects on ΔE. Conclusion. Repeated preheating of methacrylate- and silorane-based composite resin samples, up to 55‒60°C for 40 rounds, resulted in more color changes compared with unheated composite resin samples. After storage in a solution of tea the color change rate in the composite resin samples of silorane-based was higher than the Z250 composite resin samples.

Effect of preheat repetition on color stability of methacrylate- and silorane-based composite resins

PubMed Central

Abed Kahnamouei, Mehdi; Gholizadeh, Sarah; Rikhtegaran, Sahand; Daneshpooy, Mehdi; Kimyai, Soodabeh; Alizadeh Oskoee, Parnian; Rezaei, Yashar

2017-01-01

Background. The aim of this study was to investigate the effect of preheating methacrylate- and silorane-based composite resins on their color stability up to 40 times at 55‒60°C. Methods. Seventy-six methacrylate and silorane-based composite resin samples, with a diameter of 10 mm and a height of 2 mm, were divided into 4 groups (n=19). After the samples were prepared, their color parameters were determined using a reflective spectrophotometer. The composite resin samples were separately stored in a solution of tea for 40 consecutive days. Then the samples underwent a color determination procedure again using a spectrophotometer and color changes were recorded. Finally two-way ANOVA was used to study the effect of composite temperature on its staining (P<0.05). Independent-samples t-test was used to evaluate changes in conversion rates of preheated composite resin samples compared to non-heated samples at P=0.005 and P=0.029 for silorane-based and Z250 composite resin samples, respectively. Results. Both composite resin type (P=0.014) and preheating (P<0.001) had significant effects on ΔE. Conclusion. Repeated preheating of methacrylate- and silorane-based composite resin samples, up to 55‒60°C for 40 rounds, resulted in more color changes compared with unheated composite resin samples. After storage in a solution of tea the color change rate in the composite resin samples of silorane-based was higher than the Z250 composite resin samples. PMID:29354248

Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions.

PubMed

Adams, Lori; Agrawal, Anoop; Cronin, John P; Ashley, Kevin

2017-01-01

Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1-3% (w˖w -1 ) aqueous ammonium bifluoride (NH 4 HF 2 ). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH 4 HF 2 solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels many-fold below those reported previously for this methodology. Notably, MDLs for Be of <0.01 ng l -1 / 0.1 ng per sample have been attained, which are superior to MDLs routinely reported for this element by means of the most widely used ultra-trace elemental measurement technique, inductively coupled plasma mass spectrometry (ICP-MS). Very low MDLs for Be are essential in consideration of reductions in OELs for this element in workplace air by health organizations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly-designed occupational air sampler inserts are illustrated.

Droplet-based microfluidic flow injection system with large-scale concentration gradient by a single nanoliter-scale injection for enzyme inhibition assay.

PubMed

Cai, Long-Fei; Zhu, Ying; Du, Guan-Sheng; Fang, Qun

2012-01-03

We described a microfluidic chip-based system capable of generating droplet array with a large scale concentration gradient by coupling flow injection gradient technique with droplet-based microfluidics. Multiple modules including sample injection, sample dispersion, gradient generation, droplet formation, mixing of sample and reagents, and online reaction within the droplets were integrated into the microchip. In the system, nanoliter-scale sample solution was automatically injected into the chip under valveless flow injection analysis mode. The sample zone was first dispersed in the microchannel to form a concentration gradient along the axial direction of the microchannel and then segmented into a linear array of droplets by immiscible oil phase. With the segmentation and protection of the oil phase, the concentration gradient profile of the sample was preserved in the droplet array with high fidelity. With a single injection of 16 nL of sample solution, an array of droplets with concentration gradient spanning 3-4 orders of magnitude could be generated. The present system was applied in the enzyme inhibition assay of β-galactosidase to preliminarily demonstrate its potential in high throughput drug screening. With a single injection of 16 nL of inhibitor solution, more than 240 in-droplet enzyme inhibition reactions with different inhibitor concentrations could be performed with an analysis time of 2.5 min. Compared with multiwell plate-based screening systems, the inhibitor consumption was reduced 1000-fold. © 2011 American Chemical Society

Enhanced Conformational Sampling of N-Glycans in Solution with Replica State Exchange Metadynamics.

PubMed

Galvelis, Raimondas; Re, Suyong; Sugita, Yuji

2017-05-09

Molecular dynamics (MD) simulation of a N-glycan in solution is challenging because of high-energy barriers of the glycosidic linkages, functional group rotational barriers, and numerous intra- and intermolecular hydrogen bonds. In this study, we apply different enhanced conformational sampling approaches, namely, metadynamics (MTD), the replica-exchange MD (REMD), and the recently proposed replica state exchange MTD (RSE-MTD), to a N-glycan in solution and compare the conformational sampling efficiencies of the approaches. MTD helps to cross the high-energy barrier along the ω angle by utilizing a bias potential, but it cannot enhance sampling of the other degrees of freedom. REMD ensures moderate-energy barrier crossings by exchanging temperatures between replicas, while it hardly crosses the barriers along ω. In contrast, RSE-MTD succeeds to cross the high-energy barrier along ω as well as to enhance sampling of the other degrees of freedom. We tested two RSE-MTD schemes: in one scheme, 64 replicas were simulated with the bias potential along ω at different temperatures, while simulations of four replicas were performed with the bias potentials for different CVs at 300 K. In both schemes, one unbiased replica at 300 K was included to compute conformational properties of the glycan. The conformational sampling of the former is better than the other enhanced sampling methods, while the latter shows reasonable performance without spending large computational resources. The latter scheme is likely to be useful when a N-glycan-attached protein is simulated.

Analytical solutions for one-, two-, and three-dimensional solute transport in ground-water systems with uniform flow

USGS Publications Warehouse

Wexler, Eliezer J.

1992-01-01

Analytical solutions to the advective-dispersive solute-transport equation are useful in predicting the fate of solutes in ground water. Analytical solutions compiled from available literature or derived by the author are presented for a variety of boundary condition types and solute-source configurations in one-, two-, and three-dimensional systems having uniform ground-water flow. A set of user-oriented computer programs was created to evaluate these solutions and to display the results in tabular and computer-graphics format. These programs incorporate many features that enhance their accuracy, ease of use, and versatility. Documentation for the programs describes their operation and required input data, and presents the results of sample problems. Derivations of selected solutions, source codes for the computer programs, and samples of program input and output also are included.

Stability of Hydrocortisone Preservative-Free Oral Solutions.

PubMed

Chappe, Julie; Osman, Névine; Cisternino, Salvatore; Fontan, Jean-Eudes; Schlatter, Joël

2015-01-01

The physical and chemical stability of a preservative-free oral solution of hydrocortisone succinate was studied at different pH values and storage temperatures. Oral solutions of hydrocortisone 1 mg/mL were prepared by dissolving hydrocortisone succinate powder in citrate buffers at pH 4.0, 5.5, and 6.5, or with sterile water (pH 7.4) stored in amber glass vials. Three identical samples of the formulations were prepared and stored under refrigeration (3-7°C), ambient temperature (20-22°C) and high temperature (29-31°C). A 200-μL sample was withdrawn from each of the 3 samples immediately after preparation and at 1, 7, 14, 21, and 35 days. Samples were assayed in duplicate using stability-indicating liquid chromatography. Stability was determined by evaluating the percentage of the initial concentration remaining at each time point; stability was defined as the retention of at least 90% of the initial concentration of hydrocortisone succinate. At least 92% of the initial hydrocortisone succinate concentration in solutions pH 5.5, 6.5, and 7.4 remained throughout the 14-day study period under refrigeration. There were no detectable changes in color, odor, or pH and no visible microbial growth in these samples. In other storage conditions, hydrocortisone succinate was rapidly degraded. The hydrocortisone succinate preservative-free oral solutions at pH 5.5, 6.5, or 7.4 are chemically stable when stored under refrigeration for at least 14 days. They provide flexible and convenient dosage forms without any preservatives for pediatric patients.

Influence of refrigeration and formalin on the floatability of Giardia duodenalis cysts.

PubMed

Moitinho, M d; Bertoli, M; Guedes, T A; Ferreira, C S

1999-01-01

Giardia duodenalis cysts obtained from fresh fecal samples, fecal samples kept under refrigeration and fecal samples treated with formalin were studied as to their floatability on sucrose solutions with the following specific gravities: 1,040 kg/m3; 1,050 kg/m3; 1, 060 kg/m3; 1,070 kg/m3; 1,080 kg/m3; 1,090 kg/m3; 1,100 kgm3; 1,150 kg/m3; 1,200 kg/m3; and 1,250 kg/m3, contained within counting-chambers 0.17 mm high. Cysts that floated on and those settled down as sediments were counted, and had their percentages estimated. Sucrose solutions of 1,200 kg/m3 specific gravity (the average specific gravity of diluting liquids employed in floatation techniques) caused to float 77.7%, 78.4% and 6.6% of the G. duodenalis cysts obtained, respectively, from fresh fecal samples, fecal samples kept under refrigeration, and fecal samples treated with formalin. Cysts obtained both from fresh fecal samples and fecal samples kept under refrigeration presented similar results concerning floatability. It was observed, however, that the treatment of feces with formalin diminished the cysts floatability under the various specific gravities studied. This results should influence, the recommendations for transport and storage of fecal samples used for parasitological coproscopy.

Challenges and solutions for the analysis of in situ , in crystallo micro-spectrophotometric data

DOE PAGES

Dworkowski, Florian S. N.; Hough, Michael A.; Pompidor, Guillaume; ...

2015-01-01

Combining macromolecular crystallography with in crystallo micro-spectrophotometry yields valuable complementary information on the sample, including the redox states of metal cofactors, the identification of bound ligands and the onset and strength of undesired photochemistry, also known as radiation damage. However, the analysis and processing of the resulting data differs significantly from the approaches used for solution spectrophotometric data. The varying size and shape of the sample, together with the suboptimal sample environment, the lack of proper reference signals and the general influence of the X-ray beam on the sample have to be considered and carefully corrected for. In the presentmore » article, we discuss how to characterize and treat these sample-dependent artefacts in a reproducible manner and we demonstrate the SLS-APE in situ, in crystallo optical spectroscopy data-analysis toolbox.« less

Calculations and experiments concerning lifting force and power in TEMPUS

NASA Technical Reports Server (NTRS)

Zong, J. H.; Szekely, J.; Lohofer, G.

1993-01-01

A critical comparison is reported between the theoretically predicted and experimentally measured values for the electromagnetic lifting force and the heating rates which may be achieved, under simulated microgravity conditions, using the TEMPUS electromagnetic levitation device. The experiments involved the suspending of a metallic sample from one arm of a recording balance, such that it was carefully positioned between the heating and the positioning coils of the levitation device. The net force exerted by the sample was measured as a function of position, the coil currents, and the nature of the sample. Some calculations are also reported regarding the power absorption by the sample. The theoretical predictions, based on the numerical solution of Maxwell's equations using the volume integral technique, were found to be in excellent agreement with the measurements. For the idealized case of a spherical sample, analytical solutions describing the lifting force were also found to agree very well with the computed results.

Sampling and counting genome rearrangement scenarios

PubMed Central

2015-01-01

Background Even for moderate size inputs, there are a tremendous number of optimal rearrangement scenarios, regardless what the model is and which specific question is to be answered. Therefore giving one optimal solution might be misleading and cannot be used for statistical inferring. Statistically well funded methods are necessary to sample uniformly from the solution space and then a small number of samples are sufficient for statistical inferring. Contribution In this paper, we give a mini-review about the state-of-the-art of sampling and counting rearrangement scenarios, focusing on the reversal, DCJ and SCJ models. Above that, we also give a Gibbs sampler for sampling most parsimonious labeling of evolutionary trees under the SCJ model. The method has been implemented and tested on real life data. The software package together with example data can be downloaded from http://www.renyi.hu/~miklosi/SCJ-Gibbs/ PMID:26452124

Local Structure Determination of Carbon/Nickel Ferrite Composite Nanofibers Probed by X-ray Absorption Spectroscopy.

PubMed

Nilmoung, Sukunya; Kidkhunthod, Pinit; Maensiri, Santi

2015-11-01

Carbon/NiFe2O4 composite nanofibers have been successfully prepared by electrospinning method using a various concentration solution of Ni and Fe nitrates dispersed into polyacrylonitride (PAN) solution in N,N' dimethylformamide. The phase and mophology of PAN/NiFe2O4 composite samples were characterized and investigated by X-ray diffraction and scanning electron microscopy. The magnetic properties of the prepared samples were measured at ambient temperature by a vibrating sample magnetometer. It is found that all composite samples exhibit ferromagnetism. This could be local-structurally explained by the existed oxidation states of Ni2+ and Fe3+ in the samples. Moreover, local environments around Ni and Fe ions could be revealed by X-ray absorption spectroscopy (XAS) measurement including X-ray absorption near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS).

Using machine learning to accelerate sampling-based inversion

NASA Astrophysics Data System (ADS)

Valentine, A. P.; Sambridge, M.

2017-12-01

In most cases, a complete solution to a geophysical inverse problem (including robust understanding of the uncertainties associated with the result) requires a sampling-based approach. However, the computational burden is high, and proves intractable for many problems of interest. There is therefore considerable value in developing techniques that can accelerate sampling procedures.The main computational cost lies in evaluation of the forward operator (e.g. calculation of synthetic seismograms) for each candidate model. Modern machine learning techniques-such as Gaussian Processes-offer a route for constructing a computationally-cheap approximation to this calculation, which can replace the accurate solution during sampling. Importantly, the accuracy of the approximation can be refined as inversion proceeds, to ensure high-quality results.In this presentation, we describe and demonstrate this approach-which can be seen as an extension of popular current methods, such as the Neighbourhood Algorithm, and bridges the gap between prior- and posterior-sampling frameworks.

MC ICP-MS δ(34)S(VCDT) measurement of dissolved sulfate in environmental aqueous samples after matrix separation by means of an anion exchange membrane.

PubMed

Hanousek, Ondrej; Berger, Torsten W; Prohaska, Thomas

2016-01-01

Analysis of (34)S/(32)S of sulfate in rainwater and soil solutions can be seen as a powerful tool for the study of the sulfur cycle. Therefore, it is considered as a useful means, e.g., for amelioration and calibration of ecological or biogeochemical models. Due to several analytical limitations, mainly caused by low sulfate concentration in rainwater, complex matrix of soil solutions, limited sample volume, and high number of samples in ecosystem studies, a straightforward analytical protocol is required to provide accurate S isotopic data on a large set of diverse samples. Therefore, sulfate separation by anion exchange membrane was combined with precise isotopic measurement by multicollector inductively coupled plasma mass spectrometry (MC ICP-MS). The separation method proved to be able to remove quantitatively sulfate from matrix cations (Ca, K, Na, or Li) which is a precondition in order to avoid a matrix-induced analytical bias in the mass spectrometer. Moreover, sulfate exchange on the resin is capable of preconcentrating sulfate from low concentrated solutions (to factor 3 in our protocol). No significant sulfur isotope fractionation was observed during separation and preconcentration. MC ICP-MS operated at edge mass resolution has enabled the direct (34)S/(32)S analysis of sulfate eluted from the membrane, with an expanded uncertainty U (k = 2) down to 0.3 ‰ (a single measurement). The protocol was optimized and validated using different sulfate solutions and different matrix compositions. The optimized method was applied in a study on solute samples retrieved in a beech (Fagus sylvatica) forest in the Vienna Woods. Both rainwater (precipitation and tree throughfall) and soil solution δ (34)SVCDT ranged between 4 and 6 ‰, the ratio in soil solution being slightly lower. The lower ratio indicates that a considerable portion of the atmospherically deposited sulfate is cycled through the organic S pool before being released to the soil solution. Nearly the same trends and variations were observed in soil solution and rainwater δ (34)SVCDT values showing that sulfate adsorption/desorption are not important processes in the studied soil.

Living cell manipulation, manageable sampling, and shotgun picoliter electrospray mass spectrometry for profiling metabolites.

PubMed

Gholipour, Yousef; Erra-Balsells, Rosa; Hiraoka, Kenzo; Nonami, Hiroshi

2013-02-01

A modified cell pressure probe and an online Orbitrap mass spectrometer were used to sample in situ plant single cells without any additional manipulation. The cell pressure probe, a quartz capillary tip filled with an oil mixture, was penetrated to various depths into parenchyma cells of tulip bulb scale, followed by a hydraulic continuity test to determine the exact location of the tip inside target cells. The operation was conducted under a digital microscope, and the capillary tip was photographed to calculate the volume of the cell sap sucked. The cell sap sample was then directly nebulized/ionized under high-voltage conditions at the entrance of the mass spectrometer. Several sugars, amino acids, organic acids, vitamins, fatty acids, and secondary metabolites were detected. Because picoliter solutions can be accurately handled and measured, known volumes of standard solutions can be added to cell sap samples inside the capillary tip to be used as references for metabolite characterization and relative quantitation. The high precision and sensitivity of the cell pressure probe and Orbitrap mass spectrometer allow for the manipulation and analysis of both femtoliter cell sap samples and standard solutions. Copyright © 2012 Elsevier Inc. All rights reserved.

Nanoprecipitates and Their Strengthening Behavior in Al-Mg-Si Alloy During the Aging Process

NASA Astrophysics Data System (ADS)

Li, Hui; Liu, Wenqing

2017-04-01

The different nanoprecipitates formed in a 6061 aluminum alloy during aging at 453 K (180 °C), with or without 168 hours of pre-natural aging (NA), and the age-hardening response of the alloy were investigated by atom probe tomography (APT) and hardness testing. A hardness plateau developed between 2 and 8 hours in both the artificial aging (AA) and artificial aging with pre-natural aging (NAAA) samples. The hardness of NAAA samples was lower than that of AA samples when artificially aged for the same time. A 168-hour NA led to the formation of solute atom clusters in the matrix. The NA accelerated the precipitation kinetics of the following AA. The solute atom clusters gave the highest hardness increment per unit volume fraction. The β″ precipitates were dominant in the samples at the hardness plateau. The average normalized Mg:Si ratios of the solute atom clusters and GP zones were near 1. The average Mg:Si ratio of β″ precipitates increased from 1.3 to 1.5 upon aging for 2 hours. The microstructural evolution of samples with or without NA and its influence on the strengthening effects are discussed based on the experimental results.

Drug Loading Capacity of Environmentally Sensitive Polymeric Microgels

NASA Astrophysics Data System (ADS)

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

2009-10-01

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

Improved Optics For Quasi-Elastic Light Scattering

NASA Technical Reports Server (NTRS)

Cheung, Harry Michael

1995-01-01

Improved optical train devised for use in light-scattering measurements of quasi-elastic light scattering (QELS) and laser spectroscopy. Measurements performed on solutions, microemulsions, micellular solutions, and colloidal dispersions. Simultaneous measurements of total intensity and fluctuations in total intensity of light scattered from sample at various angles provides data used, in conjunction with diffusion coefficients, to compute sizes of particles in sample.

Major-ion chemistry of the Rocky Mountain snowpack, USA

USGS Publications Warehouse

Turk, J.T.; Taylor, Howard E.; Ingersoll, G.P.; Tonnessen, K.A.; Clow, D.W.; Mast, M.A.; Campbell, D.H.; Melack, J.M.

2001-01-01

During 1993-97, samples of the full depth of the Rocky Mountain snowpack were collected at 52 sites from northern New Mexico to Montana and analyzed for major-ion concentrations. Concentrations of acidity, sulfate, nitrate, and calcium increased from north to south along the mountain range. In the northern part of the study area, acidity was most correlated (negatively) with calcium. Acidity was strongly correlated (positively) with nitrate and sulfate in the southern part and for the entire network. Acidity in the south exceeded the maximum acidity measured in snowpack of the Sierra Nevada and Cascade Mountains. Principal component analysis indicates three solute associations we characterize as: (1) acid (acidity, sulfate, and nitrate), (2) soil (calcium, magnesium, and potassium), and (3) salt (sodium, chloride, and ammonium). Concentrations of acid solutes in the snowpack are similar to concentrations in nearby wetfall collectors, whereas, concentrations of soil solutes are much higher in the snowpack than in wetfall. Thus, dryfall of acid solutes during the snow season is negligible, as is gypsum from soils. Snowpack sampling offers a cost-effective complement to sampling of wetfall in areas where wetfall is difficult to sample and where the snowpack accumulates throughout the winter. Copyright ?? 2001 .

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

USGS Publications Warehouse

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

2004-01-01

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

Microplates in liquid chromatography--new solution in clinical research? A review.

PubMed

Krcmova, Lenka; Solichova, Dagmar; Solich, Petr

2013-10-15

Microplates are routinely used in Radio- or Immuno-assays. Recently, microplates have found use not only in analytical but also in the pre-analytical phase in bioanalyses (sample storage, sample preparation). New connection of this technology to liquid chromatography could be economical, fast and simple solution for many routine laboratories handling large sequences of biological samples. This review summarises the application of microplates in bioanalytical laboratories. Different types of sorbents, materials and shapes of microplates are discussed, and the main advantages and disadvantages of microplates used in clinical research are presented. Copyright © 2013 Elsevier B.V. All rights reserved.

Solubility Limits of Dibutyl Phosphoric Acid in Uranium Solutions at SRS

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

Thompson, M.C.; Pierce, R.A.; Ray, R.J.

1998-06-01

The Savannah River Site has enriched uranium (EU) solution which has been stored for almost 10 years since being purified in the second uranium cycle of the H area solvent extraction process. The concentrations in solution are {tilde 6} g/L U and about 0.1 M nitric acid. Residual tributylphosphate in the solutions has slowly hydrolyzed to form dibutyl phosphoric acid (HDBP) at concentrations averaging 50 mg/L. Uranium is known to form compounds with DBP which have limited solubility. The potential to form uranium-DBP solids raises a nuclear criticality safety issue. SRTC tests have shown that U-DBP solids will precipitate atmore » concentrations potentially attainable during storage of enriched uranium solutions. Evaporation of the existing EUS solution without additional acidification could result in the precipitation of U-DBP solids if DBP concentration in the resulting solution exceeds 110 ppm at ambient temperature. The same potential exists for evaporation of unwashed 1CU solutions. The most important variables of interest for present plant operations are HNO{sub 3} and DBP concentrations. Temperature is also an important variable controlling precipitation. The data obtained in these tests can be used to set operating and safety limits for the plant. It is recommended that the data for 0 degrees C with 0.5 M HNO{sub 3} be used for setting the limits. The limit would be 80 mg/L which is 3 standard deviations below the average of 86 observed in the tests. The data shows that super-saturation can occur when the DBP concentration is as much as 50 percent above the solubility limit. However, super-saturation cannot be relied on for maintaining nuclear criticality safety. The analytical method for determining DBP concentration in U solutions was improved so that analyses for a solution are accurate to within 10 percent. However, the overall uncertainty of results for periodic samples of the existing EUS solutions was only reduced slightly. Thus, sampling appears to be the largest portion of the uncertainty for EUS sample results, although the number of samples analyzed here is low which could contribution to higher uncertainty. The analytical method can be transferred to the plant analytical labs for more routine analysis of samples.« less

OPC Paste Samples Exposed To Aggressive Solutions. Cementitious Barriers Partnership

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

Langton, C.

2014-11-01

The study presented in this report focused on a low-activity wasteform containing a high-pH pore solution with a significant level of sulfate. The purpose of the study was to improve understanding of the complex concrete/wasteform reactive transport problem, in particular, the role of pH in sulfate attack. Paste samples prepared at three different water-to-cement ratios were tested. The mixtures were prepared with ASTM Type I cement, without additional admixtures. The samples were exposed to two different sodium sulfate contact solutions. The first solution was prepared at 0.15M Na 2SO 4. The second solution also incorporated 0.5M NaOH, to mimic themore » high pH conditions found in Saltstone. The data collected indicated that, in Na 2SO 4 solution, damage occurs to the pastes. In the case of the high-pH sulfate solution (Na 2SO 4 + NaOH), no signs of damage were observed on any of the paste mixtures. These results indicate that the high sulfate content found in the wasteform pore solution will not necessarily lead to severe damage to concrete. Good-quality mixtures could thus prove durable over the long term, and act as an effective barrier to prevent radionuclides from reaching the environment.« less

Neutron activation analysis for antimetabolites. [in food samples

NASA Technical Reports Server (NTRS)

1973-01-01

Determination of metal ion contaminants in food samples is studied. A weighed quantity of each sample was digested in a concentrated mixture of nitric, hydrochloric and perchloric acids to affect complete solution of the food products. The samples were diluted with water and the pH adjusted according to the specific analysis performed. The samples were analyzed by neutron activation analysis, polarography, and atomic absorption spectrophotometry. The solid food samples were also analyzed by neutron activation analysis for increased sensitivity and lower levels of detectability. The results are presented in tabular form.

Determination of traces of palladium in stream sediment and auto catalyst by FI-ICP-OES using on-line separation and preconcentration with QuadraSil TA.

PubMed

Nakajima, Junichi; Ohno, Masashi; Chikama, Katsumi; Seki, Tatsuya; Oguma, Koichi

2009-09-15

A flow injection analysis (FIA) method using on-line separation and preconcentration with a novel metal scavenger beads, QuadraSil TA, has been developed for the ICP-OES determination of traces of palladium. QuadraSil TA contains diethylenetriamine as a functional group on spherical silica beads and shows the highest selectivity for Pd(II) at pH 1 (0.1 mol l(-1) hydrochloric acid) solution. An aliquot of the sample solution prepared as 0.1 mol l(-1) in hydrochloric acid was passed through the QuadraSil TA column. After washing the column with the carrier solution, the Pd(II) retained on the column was eluted with 0.05 mol l(-1) thiourea solution and the eluate was directly introduced into an ICP-OES. The proposed method was successfully applied to the determination of traces of palladium in JSd-2 stream sediment certified reference material [0.019+/-0.001 microg g(-1) (n=3); provisional value: 0.0212 microg g(-1)] and SRM 2556 used auto catalyst certified reference material [315+/-4 microg g(-1) (n=4); certified value: 326 microg g(-1)]. The detection limit (3 sigma) of 0.28 ng ml(-1) was obtained for 5 ml of sample solution. The sample through puts for 5 ml and 100 microl of the sample solutions were 10 and 15 h(-1), respectively.

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING LIGHT TRANSMISSION VISUALIZATION METHOD

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

Handwashing with soap or alcoholic solutions? A randomized clinical trial of its effectiveness.

PubMed

Zaragoza, M; Sallés, M; Gomez, J; Bayas, J M; Trilla, A

1999-06-01

The effectiveness of an alcoholic solution compared with the standard hygienic handwashing procedure during regular work in clinical wards and intensive care units of a large public university hospital in Barcelona was assessed. A prospective, randomized clinical trial with crossover design, paired data, and blind evaluation was done. Eligible health care workers (HCWs) included permanent and temporary HCWs of wards and intensive care units. From each category, a random sample of persons was selected. HCWs were randomly assigned to regular handwashing (liquid soap and water) or handwashing with the alcoholic solution by using a crossover design. The number of colony-forming units on agar plates from hands printing in 3 different samples was counted. A total of 47 HCWs were included. The average reduction in the number of colony-forming units from samples before handwashing to samples after handwashing was 49.6% for soap and water and 88.2% for the alcoholic solution. When both methods were compared, the average number of colony-forming units recovered after the procedure showed a statistically significant difference in favor of the alcoholic solution (P <.001). The alcoholic solution was well tolerated by HCWs. Overall acceptance rate was classified as "good" by 72% of HCWs after 2 weeks use. Of all HCWs included, 9.3% stated that the use of the alcoholic solution worsened minor pre-existing skin conditions. Although the regular use of hygienic soap and water handwashing procedures is the gold standard, the use of alcoholic solutions is effective and safe and deserves more attention, especially in situations in which the handwashing compliance rate is hampered by architectural problems (lack of sinks) or nursing work overload.

Maybe Small Is Too Small a Term: Introduction to Advancing Small Sample Prevention Science.

PubMed

Fok, Carlotta Ching Ting; Henry, David; Allen, James

2015-10-01

Prevention research addressing health disparities often involves work with small population groups experiencing such disparities. The goals of this special section are to (1) address the question of what constitutes a small sample; (2) identify some of the key research design and analytic issues that arise in prevention research with small samples; (3) develop applied, problem-oriented, and methodologically innovative solutions to these design and analytic issues; and (4) evaluate the potential role of these innovative solutions in describing phenomena, testing theory, and evaluating interventions in prevention research. Through these efforts, we hope to promote broader application of these methodological innovations. We also seek whenever possible, to explore their implications in more general problems that appear in research with small samples but concern all areas of prevention research. This special section includes two sections. The first section aims to provide input for researchers at the design phase, while the second focuses on analysis. Each article describes an innovative solution to one or more challenges posed by the analysis of small samples, with special emphasis on testing for intervention effects in prevention research. A concluding article summarizes some of their broader implications, along with conclusions regarding future directions in research with small samples in prevention science. Finally, a commentary provides the perspective of the federal agencies that sponsored the conference that gave rise to this special section.

Sampling with poling-based flux balance analysis: optimal versus sub-optimal flux space analysis of Actinobacillus succinogenes.

PubMed

Binns, Michael; de Atauri, Pedro; Vlysidis, Anestis; Cascante, Marta; Theodoropoulos, Constantinos

2015-02-18

Flux balance analysis is traditionally implemented to identify the maximum theoretical flux for some specified reaction and a single distribution of flux values for all the reactions present which achieve this maximum value. However it is well known that the uncertainty in reaction networks due to branches, cycles and experimental errors results in a large number of combinations of internal reaction fluxes which can achieve the same optimal flux value. In this work, we have modified the applied linear objective of flux balance analysis to include a poling penalty function, which pushes each new set of reaction fluxes away from previous solutions generated. Repeated poling-based flux balance analysis generates a sample of different solutions (a characteristic set), which represents all the possible functionality of the reaction network. Compared to existing sampling methods, for the purpose of generating a relatively "small" characteristic set, our new method is shown to obtain a higher coverage than competing methods under most conditions. The influence of the linear objective function on the sampling (the linear bias) constrains optimisation results to a subspace of optimal solutions all producing the same maximal fluxes. Visualisation of reaction fluxes plotted against each other in 2 dimensions with and without the linear bias indicates the existence of correlations between fluxes. This method of sampling is applied to the organism Actinobacillus succinogenes for the production of succinic acid from glycerol. A new method of sampling for the generation of different flux distributions (sets of individual fluxes satisfying constraints on the steady-state mass balances of intermediates) has been developed using a relatively simple modification of flux balance analysis to include a poling penalty function inside the resulting optimisation objective function. This new methodology can achieve a high coverage of the possible flux space and can be used with and without linear bias to show optimal versus sub-optimal solution spaces. Basic analysis of the Actinobacillus succinogenes system using sampling shows that in order to achieve the maximal succinic acid production CO₂ must be taken into the system. Solutions involving release of CO₂ all give sub-optimal succinic acid production.

A cell transportation solution that preserves live circulating tumor cells in patient blood samples.

PubMed

Stefansson, Steingrimur; Adams, Daniel L; Ershler, William B; Le, Huyen; Ho, David H

2016-05-06

Circulating tumor cells (CTCs) are typically collected into CellSave fixative tubes, which kills the cells, but preserves their morphology. Currently, the clinical utility of CTCs is mostly limited to their enumeration. More detailed investigation of CTC biology can be performed on live cells, but obtaining live CTCs is technically challenging, requiring blood collection into biocompatible solutions and rapid isolation which limits transportation options. To overcome the instability of CTCs, we formulated a sugar based cell transportation solution (SBTS) that stabilizes cell viability at ambient temperature. In this study we examined the long term viability of human cancer cell lines, primary cells and CTCs in human blood samples in the SBTS for transportation purposes. Four cell lines, 5 primary human cells and purified human PBMCs were tested to determine the viability of cells stored in the transportation solution at ambient temperature for up to 7 days. We then demonstrated viability of MCF-7 cells spiked into normal blood with SBTS and stored for up to 7 days. A pilot study was then run on blood samples from 3 patients with metastatic malignancies stored with or without SBTS for 6 days. CTCs were then purified by Ficoll separation/microfilter isolation and identified using CTC markers. Cell viability was assessed using trypan blue or CellTracker™ live cell stain. Our results suggest that primary/immortalized cell lines stored in SBTS remain ~90% viable for > 72 h. Further, MCF-7 cells spiked into whole blood remain viable when stored with SBTS for up to 7 days. Finally, live CTCs were isolated from cancer patient blood samples kept in SBTS at ambient temperature for 6 days. No CTCs were isolated from blood samples stored without SBTS. In this proof of principle pilot study we show that viability of cell lines is preserved for days using SBTS. Further, this solution can be used to store patient derived blood samples for eventual isolation of viable CTCs after days of storage. Therefore, we suggest an effective and economical transportation of cancer patient blood samples containing live CTCs can be achieved.

Representativeness of direct observations selected using a work-sampling equation.

PubMed

Sharp, Rebecca A; Mudford, Oliver C; Elliffe, Douglas

2015-01-01

Deciding on appropriate sampling to obtain representative samples of behavior is important but not straightforward, because the relative duration of the target behavior may affect its observation in a given sampling interval. Work-sampling methods, which offer a way to adjust the frequency of sampling according to a priori or ongoing estimates of the behavior to achieve a preselected level of representativeness, may provide a solution. Full-week observations of 7 behaviors were conducted for 3 students with autism spectrum disorder and intellectual disabilities. Work-sampling methods were used to select momentary time samples from the full time-of-interest, which produced representative samples. However, work sampling required impractically high numbers of time samples to obtain representative samples. More practical momentary time samples produced less representative samples, particularly for low-duration behaviors. The utility and limits of work-sampling methods for applied behavior analysis are discussed. © Society for the Experimental Analysis of Behavior.

Retention efficiency of Cd, Pb and Zn from agricultural by-products activated carbon and biochar under laboratory conditions

NASA Astrophysics Data System (ADS)

Coscione, Aline; Ramos, Barbara

2015-04-01

The immobilization of inorganic contaminants by using biochar in soils has played an increasingly important role and it is seen as an attractive alternative for the remediation of heavy metals. Although, the production of activated carbon (CA) from agricultural by-products has received special attention, the activation of the the organic source has been studied in order to increase its porposity, surface area and chemical polarity, resulting in higher adsorption of metals. Therefore, this study aimed to evaluate the effectiveness of BC and CA samples, obtained from a eucalyptus husks and cane sugar bagasse after activation with 20% phosphoric acid and pyrolyzed at 450oC in the retention of Zn, Cd and Pb using contaminated individual solutions. The experiment was performed using samples of activated carbon of eucalyptus husk (CCA), eucalyptus husk biochar (BC), activated carbon of sugar cane bagasse (CBA) and sugar cane bagasse biochar (BB) previously treated with Zn, Cd (range of tested solution from 0.1 up to 12 mmol L-1) and Pb (from 0.1 up 50 mmol L-1) which were submitted to stirring with ammonium acetate solution at pH 4.9 for 48 h. The results obtained were adjusted with Langmuir desorptiom isotherms. The pH of the resulting solution, were the meatls were analyse, was measure and remained in the range 4.9 - 5.0. The lower pH found in activated samples (range 2.4-2.5) resulted in larger desorption of metals than the biochar samples (pH of 9.7 for BC and 7.0 for BB). This result is surprising since for the biochar samples it was expected that any precipated metals were dissolved by the desorption solution in addition to metals released by ion exchange. Although the desorption results of activated samoels is still unclear, hich we belive may be explaibed by some adicitonal insterumental analysis, biochar samples showed better potential for application in contaminated soils than the previous.

Balancing a U-Shaped Assembly Line by Applying Nested Partitions Method

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

Bhagwat, Nikhil V.

2005-01-01

In this study, we applied the Nested Partitions method to a U-line balancing problem and conducted experiments to evaluate the application. From the results, it is quite evident that the Nested Partitions method provided near optimal solutions (optimal in some cases). Besides, the execution time is quite short as compared to the Branch and Bound algorithm. However, for larger data sets, the algorithm took significantly longer times for execution. One of the reasons could be the way in which the random samples are generated. In the present study, a random sample is a solution in itself which requires assignment ofmore » tasks to various stations. The time taken to assign tasks to stations is directly proportional to the number of tasks. Thus, if the number of tasks increases, the time taken to generate random samples for the different regions also increases. The performance index for the Nested Partitions method in the present study was the number of stations in the random solutions (samples) generated. The total idle time for the samples can be used as another performance index. ULINO method is known to have used a combination of bounds to come up with good solutions. This approach of combining different performance indices can be used to evaluate the random samples and obtain even better solutions. Here, we used deterministic time values for the tasks. In industries where majority of tasks are performed manually, the stochastic version of the problem could be of vital importance. Experimenting with different objective functions (No. of stations was used in this study) could be of some significance to some industries where in the cost associated with creation of a new station is not the same. For such industries, the results obtained by using the present approach will not be of much value. Labor costs, task incompletion costs or a combination of those can be effectively used as alternate objective functions.« less

IMPACT OF CRITICAL ANION SOIL SOLUTION CONCENTRATION ON ALUMINUM ACTIVITY IN ALPINE TUNDRA SOIL Andrew Evans, Jr.1 , Michael B. Jacobs2, and Jason R. Janke1, (1) Metropolitan State University of Denver, Dept. of Earth and Atmospheric Sciences, (2) Dept. of Chemistry, Denver, CO, United States.

NASA Astrophysics Data System (ADS)

Evans, A.

2015-12-01

Soil solution anionic composition can impact both plant and microbial activity in alpine tundra soils by altering biochemical cycling within the soil, either through base cation leaching, or shifts in aluminum controlling solid phases. Although anions play a critical role in the aqueous speciation of metals, relatively few high altitude field studies have examined their impact on aluminum controlling solid phases and aluminum speciation in soil water. For this study, thirty sampling sites were selected on Trail Ridge Road in Rocky Mountain National Park, Estes Park, CO, and sampled during July, the middle of the growing season. Sampling elevations ranged from approximately 3560 - 3710 m. Soil samples were collected to a depth of 15.24 cm, and the anions were extracted using a 2:1 D.I. water to soil ratio. Filtered extracts were analyzed using IC and ICP-MS. Soil solution NO3- concentrations were significantly higher for sampling locations east of Iceberg Pass (EIBP) (mean = 86.94 ± 119.8 mg/L) compared to locations west of Iceberg Pass (WIBP) (mean 1.481 ± 2.444 mg/L). Both F- and PO43- soil solution concentrations, 0.533 and 0.440 mg/L, respectively, were substantially lower, for sampling sites located EIBP, while locations WIBP averaged 0.773 and 0.829 mg/L respectively, for F- and PO43-. Sulfate concentration averaged 3.869 ± 3.059 mg/L for locations EIBP, and 3.891 ± 3.1970 for locations WIBP. Geochemical modeling of Al3+ in the soil solution indicated that a suite of aluminum hydroxyl sulfate minerals controlled Al3+ activity in the alpine tundra soil, with shifts between controlling solid phases occurring in the presence of elevated F- concentrations.

Preparing for chemical terrorism: stability of injectable atropine sulfate.

PubMed

Schier, Joshua G; Ravikumar, Padinjarekuttu R; Nelson, Lewis S; Heller, Michael B; Howland, Mary Ann; Hoffman, Robert S

2004-04-01

A massive nerve agent attack may rapidly deplete in-date supplies of atropine. The authors considered using atropine beyond its labeled shelf life. The objective was to determine the stability of premixed injectable atropine sulfate samples with different expiration dates. This was an in-vitro study using gas chromatography and mass spectrometry (GC/MS). Four atropine solutions (labeled concentration of 400 microg/mL) ranging from in date to 12 years beyond expiration (exp) and an additional sample of atropine sulfate (labeled concentration of 2,000 microg/mL) obtained from a World War II era autoinjector were assayed for atropine stability. Standards of atropine sulfate and tropine were prepared and quantified by GC/MS. Study samples were prepared by adding a buffer solution to free the base, extracting with an isopropanol/methylene chloride mixture and followed by evaporating the organic layer to dryness. Pentafluoropropionic anhydride and pentafluoropropanol were then added as derivatization reagents. Study samples were heated, the derivitization reagents were evaporated, and the remaining compound was reconstituted in ethyl acetate for injection into the GC/MS. All solutions were clear and colorless. Atropine concentrations were as follows: in date, 252 microg/mL; 2001 exp, 290 microg/mL; 1999 exp, 314 microg/mL; 1990 exp, 398 microg/mL; and WW II specimen, 1,475 microg/mL. Tropine was found in concentrations of <10 microg/mL in all study samples. Significant amounts of atropine were found in all study samples. All samples remained clear and colorless, and no substantial amount of tropine was found in any study sample. Further testing is needed to determine clinical effect.

Clinical evaluation of human papillomavirus detection by careHPV™ test on physician-samples and self-samples using the indicating FTA Elute® card.

PubMed

Wang, Shao-Ming; Hu, Shang-Ying; Chen, Feng; Chen, Wen; Zhao, Fang-Hui; Zhang, Yu-Qing; Ma, Xin-Ming; Qiao, You-Lin

2014-01-01

To make the clinical evaluation of a solid-state human papillomavirus (HPV) sampling medium in combination with an economical HPV testing method (careHPV™) for cervical cancer screening. 396 women aged 25-65 years were enrolled for cervical cancer screening, and four samples were collected. Two samples were collected by woman themselves, among which one was stored in DCM preservative solution (called "liquid sample") and the other was applied on the Whatman Indicating FTA Elute® card (FTA card). Another two samples were collected by physician and stored in DCM preservative solution and FTA card, respectively. All the samples were detected by careHPV™ test. All the women were administered a colposcopy examination, and biopsies were taken for pathological confirmation if necessary. FTA card demonstrated a comparable sensitivity of detecting high grade Cervical Intraepithelial Neoplasia (CIN) with the liquid sample carrier for self and physician-sampling, but showed a higher specificity than that of liquid sample carrier for self-sampling (FTA vs Liquid: 79.0% vs 71.6%, p=0.02). Generally, the FTA card had a comparable accuracy with that of Liquid-based medium by different sampling operators, with an area under the curve of 0.807 for physician and FTA, 0.781 for physician and Liquid, 0.728 for self and FTA, and 0.733 for self and Liquid (p>0.05). FTA card is a promising sample carrier for cervical cancer screening. With appropriate education programmes and further optimization of the experimental workflow, FTA card based self-collection in combination with centralized careHPV™ testing can help expand the coverage of cervical cancer screening in low-resource areas.

Flow-based ammonia gas analyzer with an open channel scrubber for indoor environments.

PubMed

Ohira, Shin-Ichi; Heima, Minako; Yamasaki, Takayuki; Tanaka, Toshinori; Koga, Tomoko; Toda, Kei

2013-11-15

A robust and fully automated indoor ammonia gas monitoring system with an open channel scrubber (OCS) was developed. The sample gas channel dimensions, hydrophilic surface treatment to produce a thin absorbing solution layer, and solution flow rate of the OCS were optimized to connect the OCS as in-line gas collector and avoid sample humidity effects. The OCS effluent containing absorbed ammonia in sample gas was injected into a derivatization solution flow. Derivatization was achieved with o-phthalaldehyde and sulfite in pH 11 buffer solution. The product, 1-sulfonateisoindole, is detected with a home-made fluorescence detector. The limit of detection of the analyzer based on three times the standard deviation of baseline noise was 0.9 ppbv. Sample gas could be analyzed 40 times per hour. Furthermore, relative humidity of up to 90% did not interfere considerably with the analyzer. Interference from amines was not observed. The developed gas analysis system was calibrated using a solution-based method. The system was used to analyze ammonia in an indoor environment along with an off-site method, traditional impinger gas collection followed by ion chromatographic analysis, for comparison. The results obtained using both methods agreed well. Therefore, the developed system can perform on-site monitoring of ammonia in indoor environments with improved time resolution compared with that of other methods. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

Identification of Rare Lewis Oligosaccharide Conformers in Aqueous Solution Using Enhanced Sampling Molecular Dynamics.

PubMed

Alibay, Irfan; Burusco, Kepa K; Bruce, Neil J; Bryce, Richard A

2018-03-08

Determining the conformations accessible to carbohydrate ligands in aqueous solution is important for understanding their biological action. In this work, we evaluate the conformational free-energy surfaces of Lewis oligosaccharides in explicit aqueous solvent using a multidimensional variant of the swarm-enhanced sampling molecular dynamics (msesMD) method; we compare with multi-microsecond unbiased MD simulations, umbrella sampling, and accelerated MD approaches. For the sialyl Lewis A tetrasaccharide, msesMD simulations in aqueous solution predict conformer landscapes in general agreement with the other biased methods and with triplicate unbiased 10 μs trajectories; these simulations find a predominance of closed conformer and a range of low-occupancy open forms. The msesMD simulations also suggest closed-to-open transitions in the tetrasaccharide are facilitated by changes in ring puckering of its GlcNAc residue away from the 4 C 1 form, in line with previous work. For sialyl Lewis X tetrasaccharide, msesMD simulations predict a minor population of an open form in solution corresponding to a rare lectin-bound pose observed crystallographically. Overall, from comparison with biased MD calculations, we find that triplicate 10 μs unbiased MD simulations may not be enough to fully sample glycan conformations in aqueous solution. However, the computational efficiency and intuitive approach of the msesMD method suggest potential for its application in glycomics as a tool for analysis of oligosaccharide conformation.

Concentration-dependent changes in apparent diffusion coefficients as indicator for colloidal stability of protein solutions.

PubMed

Bauer, Katharina Christin; Göbel, Mathias; Schwab, Marie-Luise; Schermeyer, Marie-Therese; Hubbuch, Jürgen

2016-09-10

The colloidal stability of a protein solution during downstream processing, formulation, and storage is a key issue for the biopharmaceutical production process. Thus, knowledge about colloidal solution characteristics, such as the tendency to form aggregates or high viscosity, at various processing conditions is of interest. This work correlates changes in the apparent diffusion coefficient as a parameter of protein interactions with observed protein aggregation and dynamic viscosity of the respective protein samples. For this purpose, the diffusion coefficient, the protein phase behavior, and the dynamic viscosity in various systems containing the model proteins α-lactalbumin, lysozyme, and glucose oxidase were studied. Each of these experiments revealed a wide range of variations in protein interactions depending on protein type, protein concentration, pH, and the NaCl concentration. All these variations showed to be mirrored by changes in the apparent diffusion coefficient in the respective samples. Whereas stable samples with relatively low viscosity showed an almost linear dependence, the deviation from the concentration-dependent linearity indicated both an increase in the sample viscosity and probability of protein aggregation. This deviation of the apparent diffusion coefficient from concentration-dependent linearity was independent of protein type and solution properties for this study. Thus, this single parameter shows the potential to act as a prognostic tool for colloidal stability of protein solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Analytical solutions for one-, two-, and three-dimensional solute transport in ground-water systems with uniform flow

USGS Publications Warehouse

Wexler, Eliezer J.

1989-01-01

Analytical solutions to the advective-dispersive solute-transport equation are useful in predicting the fate of solutes in ground water. Analytical solutions compiled from available literature or derived by the author are presented in this report for a variety of boundary condition types and solute-source configurations in one-, two-, and three-dimensional systems with uniform ground-water flow. A set of user-oriented computer programs was created to evaluate these solutions and to display the results in tabular and computer-graphics format. These programs incorporate many features that enhance their accuracy, ease of use, and versatility. Documentation for the programs describes their operation and required input data, and presents the results of sample problems. Derivations of select solutions, source codes for the computer programs, and samples of program input and output also are included.

Sequential determination of nickel and cadmium in tobacco, molasses and refill solutions for e-cigarettes samples by molecular fluorescence.

PubMed

Talio, María Carolina; Alesso, Magdalena; Acosta, Mariano; Wills, Verónica S; Fernández, Liliana P

2017-11-01

In this work, a new procedure was developed for separation and preconcentration of nickel(II) and cadmium(II) in several and varied tobacco samples. Tobacco samples were selected considering the main products consumed by segments of the population, in particular the age (youth) and lifestyle of the consumer. To guarantee representative samples, a randomized strategy of sampling was used. In the first step, a chemofiltration on nylon membrane is carried out employing eosin (Eo) and carbon nanotubes dispersed in sodium dodecylsulfate (SDS) solution (phosphate buffer pH 7). In this condition, Ni(II) was selectively retained on the solid support. After that, the filtrate liquid with Cd(II) was re-conditioned with acetic acid /acetate buffer solution (pH 5) and followed by detection. A spectrofluorimetric determination of both metals was carried out, on the solid support and the filtered aqueous solution, for Ni(II) and Cd(II), respectively. The solid surface fluorescence (SSF) determination was performed at λ em = 545nm (λ ex = 515nm) for Ni(II)-Eo complex and the fluorescence of Cd(II)-Eo was quantified in aqueous solution using λ em = 565nm (λ ex = 540nm). The calibration graphs resulted linear in a range of 0.058-29.35μgL -1 for Ni(II) and 0.124-56.20μgL -1 for Cd(II), with detection limits of 0.019 and 0.041μgL -1 (S/N = 3). The developed methodology shows good sensitivity and adequate selectivity, and it was successfully applied to the determination of trace amounts of nickel and cadmium present in tobacco samples (refill solutions for e-cigarettes, snuff used in narguille (molasses) and traditional tobacco) with satisfactory results. The new methodology was validated by ICP-MS with adequate agreement. The proposed methodology represents a novel fluorescence application to Ni(II) and Cd(II) quantification with sensitivity and accuracy similar to atomic spectroscopies, introducing for the first time the quenching effect on SSF. Copyright © 2017 Elsevier B.V. All rights reserved.

Electroerosion of metal in aqueous solution for sample introduction into an inductively coupled plasma mass spectrometer

NASA Astrophysics Data System (ADS)

Goltz, Douglas; Boileau, Michael; Reinfelds, Gundars

2003-07-01

When high current (1-10 A cm -2) is applied between two conductive samples (metals) in aqueous solution, electroerosion occurs on the surface as a result of electrolysis and possibly collisions of dissolved ions with the metal surface. The power supply for the electroerosion apparatus in this work was a modified spark source unit. Current could be varied in intervals of 2.5, 5 and 10 A in either half-wave (unipolar) or full-wave (bipolar) output. The electroeroded metal forms a colloidal suspension in aqueous solution with particle sizes of the order of 1-10 μm and possibly larger. The suspension is readily dissolved using a small amount (100 μl) of concentrated acid (HCl or HNO 3) prior to analysis. Electroerosion of steel and brass in aqueous solution is described both for rapid sample dissolution and as a solid sampling approach for ICP-MS. Some of the electroerosion properties described in this paper include rates of erosion as a function of gap between the conductive samples and solution conductivity. Rates of electroerosion decreased from 120 to 30 μg s -1 as the gap was increased from 2 to 5 mm. Rates of electroerosion also increased significantly from 200 to 1000 μg s -1 as the conductivity of the electroerosion solution increased from 0.01 to 0.05 M NaCl. Interfacing the electroerosion apparatus to an ICP-MS was straight forward, as no special equipment was required. Therefore, the electroerosion apparatus can be used for rapid 'on-line' sample dissolution prior to introduction into an ICP. ICP-MS time profiles of selected metals in stainless steel 308L illustrate the behavior of 52Cr +, 55Mn + and 60Ni + during a typical electroerosion cycle. Aspiration of the colloidal suspension into the ICP did not appear to load the plasma significantly, however, all of the metals produced noisy signals (±10%). A glass concentric nebulizer was used without clogging, so it is likely that the heterogeneous nature of the colloidal suspension caused this effect.

Metadata, Identifiers, and Physical Samples

NASA Astrophysics Data System (ADS)

Arctur, D. K.; Lenhardt, W. C.; Hills, D. J.; Jenkyns, R.; Stroker, K. J.; Todd, N. S.; Dassie, E. P.; Bowring, J. F.

2016-12-01

Physical samples are integral to much of the research conducted by geoscientists. The samples used in this research are often obtained at significant cost and represent an important investment for future research. However, making information about samples - whether considered data or metadata - available for researchers to enable discovery is difficult: a number of key elements related to samples are difficult to characterize in common ways, such as classification, location, sample type, sampling method, repository information, subsample distribution, and instrumentation, because these differ from one domain to the next. Unifying these elements or developing metadata crosswalks is needed. The iSamples (Internet of Samples) NSF-funded Research Coordination Network (RCN) is investigating ways to develop these types of interoperability and crosswalks. Within the iSamples RCN, one of its working groups, WG1, has focused on the metadata related to physical samples. This includes identifying existing metadata standards and systems, and how they might interoperate with the International Geo Sample Number (IGSN) schema (schema.igsn.org) in order to help inform leading practices for metadata. For example, we are examining lifecycle metadata beyond the IGSN `birth certificate.' As a first step, this working group is developing a list of relevant standards and comparing their various attributes. In addition, the working group is looking toward technical solutions to facilitate developing a linked set of registries to build the web of samples. Finally, the group is also developing a comparison of sample identifiers and locators. This paper will provide an overview and comparison of the standards identified thus far, as well as an update on the technical solutions examined for integration. We will discuss how various sample identifiers might work in complementary fashion with the IGSN to more completely describe samples, facilitate retrieval of contextual information, and access research work on related samples. Finally, we welcome suggestions and community input to move physical sample unique identifiers forward.

Using the Karolinska Scales of Personality on male juvenile delinquents: relationships between scales and factor structure.

PubMed

Dåderman, Anna M; Hellström, Ake; Wennberg, Peter; Törestad, Bertil

2005-01-01

The aim of the present study was to investigate relationships between scales from the Karolinska Scales of Personality (KSP) and the factor structure of the KSP in a sample of male juvenile delinquents. The KSP was administered to a group of male juvenile delinquents (n=55, mean age 17 years; standard deviation=1.2) from four Swedish national correctional institutions for serious offenders. As expected, the KSP showed appropriate correlations between the scales. Factor analysis (maximum likelihood) arrived at a four-factor solution in this sample, which is in line with previous research performed in a non-clinical sample of Swedish males. More research is needed in a somewhat larger sample of juvenile delinquents in order to confirm the present results regarding the factor solution.

[Fast optimization of stepwise gradient conditions for ternary mobile phase in reversed-phase high performance liquid chromatography].

PubMed

Shan, Yi-chu; Zhang, Yu-kui; Zhao, Rui-huan

2002-07-01

In high performance liquid chromatography, it is necessary to apply multi-composition gradient elution for the separation of complex samples such as environmental and biological samples. Multivariate stepwise gradient elution is one of the most efficient elution modes, because it combines the high selectivity of multi-composition mobile phase and shorter analysis time of gradient elution. In practical separations, the separation selectivity of samples can be effectively adjusted by using ternary mobile phase. For the optimization of these parameters, the retention equation of samples must be obtained at first. Traditionally, several isocratic experiments are used to get the retention equation of solute. However, it is time consuming especially for the separation of complex samples with a wide range of polarity. A new method for the fast optimization of ternary stepwise gradient elution was proposed based on the migration rule of solute in column. First, the coefficients of retention equation of solute are obtained by running several linear gradient experiments, then the optimal separation conditions are searched according to the hierarchical chromatography response function which acts as the optimization criterion. For each kind of organic modifier, two initial linear gradient experiments are used to obtain the primary coefficients of retention equation of each solute. For ternary mobile phase, only four linear gradient runs are needed to get the coefficients of retention equation. Then the retention times of solutes under arbitrary mobile phase composition can be predicted. The initial optimal mobile phase composition is obtained by resolution mapping for all of the solutes. A hierarchical chromatography response function is used to evaluate the separation efficiencies and search the optimal elution conditions. In subsequent optimization, the migrating distance of solute in the column is considered to decide the mobile phase composition and sustaining time of the latter steps until all the solutes are eluted out. Thus the first stepwise gradient elution conditions are predicted. If the resolution of samples under the predicted optimal separation conditions is satisfactory, the optimization procedure is stopped; otherwise, the coefficients of retention equation are adjusted according to the experimental results under the previously predicted elution conditions. Then the new stepwise gradient elution conditions are predicted repeatedly until satisfactory resolution is obtained. Normally, the satisfactory separation conditions can be found only after six experiments by using the proposed method. In comparison with the traditional optimization method, the time needed to finish the optimization procedure can be greatly reduced. The method has been validated by its application to the separation of several samples such as amino acid derivatives, aromatic amines, in which satisfactory separations were obtained with predicted resolution.

Efficient parallel implementations of QM/MM-REMD (quantum mechanical/molecular mechanics-replica-exchange MD) and umbrella sampling: isomerization of H2O2 in aqueous solution.

PubMed

Fedorov, Dmitri G; Sugita, Yuji; Choi, Cheol Ho

2013-07-03

An efficient parallel implementation of QM/MM-based replica-exchange molecular dynamics (REMD) as well as umbrella samplings techniques was proposed by adopting the generalized distributed data interface (GDDI). Parallelization speed-up of 40.5 on 48 cores was achieved, making our QM/MM-MD engine a robust tool for studying complex chemical dynamics in solution. They were comparatively used to study the torsional isomerization of hydrogen peroxide in aqueous solution. All results by QM/MM-REMD and QM/MM umbrella sampling techniques yielded nearly identical potentials of mean force (PMFs) regardless of the particular QM theories for solute, showing that the overall dynamics are mainly determined by solvation. Although the entropic penalty of solvent rearrangements exists in cisoid conformers, it was found that both strong intermolecular hydrogen bonding and dipole-dipole interactions preferentially stabilize them in solution, reducing the torsional free-energy barrier at 0° by about 3 kcal/mol as compared to that in gas phase.

Behavior of neutral solutes in pressurized flow driven electrochromatography using a mixed stationary phase of ODS and anion-exchange.

PubMed

Kitagawa, Shinya; Tsuda, Takao

2003-05-02

The behavior of neutral sample solutes in pressurized flow driven electrochromatography using a mixed stationary phase, which consisted of ODS and anion-exchange (ODS-SAX), was studied. Applications of both positive and negative voltage on a column induced increases in retention factors of sample solutes. The direction of an electroosmotic flow under applications of positive and negative voltage were the same, therefore, the sign of the surface charge density under positive and negative voltage was opposite. We proposed a new equation for the relationship between applied voltage and surface charge density, and the practical electroosmotic flow conformed to this equation. Studying the electroosmotic flow using our proposed equation revealed that the applied negative voltage accelerates the protonation of the quaternary ammonium group and dissociation of the silanol group on packing materials. The retention behavior of a neutral solute was affected by the existence of the charged functional groups. We propose that this phenomenon is applicable to the control of the retention behavior of a sample solute using an electric field.

Improved quantitative recovery of Listeria monocytogenes from stainless steel surfaces using a one-ply composite tissue.

PubMed

Vorst, Keith L; Todd, Ewen C D; Rysert, Elliot T

2004-10-01

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.

Part C: Geochemistry of Soil Samples from 50 Solution-Collapse Features on the Coconino Plateau, Northern Arizona

USGS Publications Warehouse

Van Gosen, Bradley S.; Wenrich, Karen J.

1991-01-01

Soil sampling surveys were conducted during 1984-1986 across 50 solution-collapse features exposed on the Coconino Plateau of northern Arizona in order to determine whether soil geochemistry can be used to distinguish mineralized breccia pipes from unmineralized collapse features. The 50 sampled features represent the variety of collapse features that crop out on plateau surfaces in northwestern Arizonaoodeeplyorooted solution-collapse breccia pipes, near-surface gypsum collapses, and sinkholes. Of the 50 features that were sampled in this study, 3 are confirmed breccia pipes that contain significant uranium and base-metal minerals, I is believed to be a sinkhole with no economic potential, and 4 are stratabound copper deposits whose possible relationship to breccia pipes is yet to be determined. The remaining collapse features are suspected to overlie breccia pipes, although some of these may represent near surface gypsum collapse features. However, no exploratory drilling results or breccia exposures exist to indicate their underlying structure. The low cost and ease of soil sampling suggested that this technique be evaluated for breccia pipe exploration. This report provides the locations and geochemical results for the soil sampling surveys and brief descriptions of the 50 collapse features. The analytical results of almost 2,000 soil samples are provided in tabular hardcopy and dBase III Plus diskcopy format. The analytical data is provided in digital format to allow the reader to choose their own methods for evaluating the effectiveness of soil sampling over known and suspected breccia pipes. A pilot survey conducted over 17 collapse features in 1984 suggested that soil sampling might be useful in distinguishing mineralized breccia pipes from other circular features. Followup detailed surveys in 1985 and 1986 used a radial sampling pattern at each of 50 sites; at least one third of the samples were collected from areas outside of the collapse feature to provide background data. Samples were consistently collected from 3-4 inches depth after the pilot survey showed that metal concentrations were similar in samples from 3-4 inches and 7-8 inches depth. The geochemical analyses of the <80 mesh fractions of the soil samples were performed by the U.S. Geological Survey Analytical Laboratories and Geochemical Services, Inc. The analytical methods applied to these samples by the U.S. Geological Survey laboratories included inductively coupled plasma-atomic emission spectroscopy, X-ray fluorescence spectrometry, neutron activation, atomic absorption, delayed neutron activation, and classical wet chemistry for carbon, fluorine, and sulfur. Geochemical Services, Inc. analyzed the soil samples by inductively coupled plasma emission spectroscopy.

Part B: Geochemistry of Soil Samples from 50 Solution-Collapse Features on the Coconino Plateau, Northern Arizona

USGS Publications Warehouse

Van Gosen, Bradley S.; Wenrich, Karen J.

1991-01-01

Soil sampling surveys were conducted during 1984-1986 across 50 solution-collapse features exposed on the Coconino Plateau of northern Arizona in order to determine whether soil geochemistry can be used to distinguish mineralized breccia pipes from unmineralized collapse features. The 50 sampled features represent the variety of collapse features that crop out on plateau surfaces in northwestern Arizonaoodeeplyorooted solution-collapse breccia pipes, near-surface gypsum collapses, and sinkholes. Of the 50 features that were sampled in this study, 3 are confirmed breccia pipes that contain significant uranium and base-metal minerals, I is believed to be a sinkhole with no economic potential, and 4 are stratabound copper deposits whose possible relationship to breccia pipes is yet to be determined. The remaining collapse features are suspected to overlie breccia pipes, although some of these may represent near surface gypsum collapse features. However, no exploratory drilling results or breccia exposures exist to indicate their underlying structure. The low cost and ease of soil sampling suggested that this technique be evaluated for breccia pipe exploration. This report provides the locations and geochemical results for the soil sampling surveys and brief descriptions of the 50 collapse features. The analytical results of almost 2,000 soil samples are provided in tabular hardcopy and dBase III Plus diskcopy format. The analytical data is provided in digital format to allow the reader to choose their own methods for evaluating the effectiveness of soil sampling over known and suspected breccia pipes. A pilot survey conducted over 17 collapse features in 1984 suggested that soil sampling might be useful in distinguishing mineralized breccia pipes from other circular features. Followup detailed surveys in 1985 and 1986 used a radial sampling pattern at each of 50 sites; at least one third of the samples were collected from areas outside of the collapse feature to provide background data. Samples were consistently collected from 3-4 inches depth after the pilot survey showed that metal concentrations were similar in samples from 3-4 inches and 7-8 inches depth. The geochemical analyses of the <80 mesh fractions of the soil samples were performed by the U.S. Geological Survey Analytical Laboratories and Geochemical Services, Inc. The analytical methods applied to these samples by the U.S. Geological Survey laboratories included inductively coupled plasma-atomic emission spectroscopy, X-ray fluorescence spectrometry, neutron activation, atomic absorption, delayed neutron activation, and classical wet chemistry for carbon, fluorine, and sulfur. Geochemical Services, Inc. analyzed the soil samples by inductively coupled plasma emission spectroscopy.

Geochemistry of Soil Samples from 50 Solution-Collapse Features on the Coconino Plateau, Northern Arizona

USGS Publications Warehouse

Van Gosen, Bradley S.; Wenrich, Karen J.

1991-01-01

Soil sampling surveys were conducted during 1984-1986 across 50 solution-collapse features exposed on the Coconino Plateau of northern Arizona in order to determine whether soil geochemistry can be used to distinguish mineralized breccia pipes from unmineralized collapse features. The 50 sampled features represent the variety of collapse features that crop out on plateau surfaces in northwestern Arizonaoodeeplyorooted solution-collapse breccia pipes, near-surface gypsum collapses, and sinkholes. Of the 50 features that were sampled in this study, 3 are confirmed breccia pipes that contain significant uranium and base-metal minerals, I is believed to be a sinkhole with no economic potential, and 4 are stratabound copper deposits whose possible relationship to breccia pipes is yet to be determined. The remaining collapse features are suspected to overlie breccia pipes, although some of these may represent near surface gypsum collapse features. However, no exploratory drilling results or breccia exposures exist to indicate their underlying structure. The low cost and ease of soil sampling suggested that this technique be evaluated for breccia pipe exploration. This report provides the locations and geochemical results for the soil sampling surveys and brief descriptions of the 50 collapse features. The analytical results of almost 2,000 soil samples are provided in tabular hardcopy and dBase III Plus diskcopy format. The analytical data is provided in digital format to allow the reader to choose their own methods for evaluating the effectiveness of soil sampling over known and suspected breccia pipes. A pilot survey conducted over 17 collapse features in 1984 suggested that soil sampling might be useful in distinguishing mineralized breccia pipes from other circular features. Followup detailed surveys in 1985 and 1986 used a radial sampling pattern at each of 50 sites; at least one third of the samples were collected from areas outside of the collapse feature to provide background data. Samples were consistently collected from 3-4 inches depth after the pilot survey showed that metal concentrations were similar in samples from 3-4 inches and 7-8 inches depth. The geochemical analyses of the <80 mesh fractions of the soil samples were performed by the U.S. Geological Survey Analytical Laboratories and Geochemical Services, Inc. The analytical methods applied to these samples by the U.S. Geological Survey laboratories included inductively coupled plasma-atomic emission spectroscopy, X-ray fluorescence spectrometry, neutron activation, atomic absorption, delayed neutron activation, and classical wet chemistry for carbon, fluorine, and sulfur. Geochemical Services, Inc. analyzed the soil samples by inductively coupled plasma emission spectroscopy.

Part D: Geochemistry of Soil Samples from 50 Solution-Collapse Features on the Coconino Plateau, Northern Arizona

USGS Publications Warehouse

Van Gosen, Bradley S.; Wenrich, Karen J.

1991-01-01

Soil sampling surveys were conducted during 1984-1986 across 50 solution-collapse features exposed on the Coconino Plateau of northern Arizona in order to determine whether soil geochemistry can be used to distinguish mineralized breccia pipes from unmineralized collapse features. The 50 sampled features represent the variety of collapse features that crop out on plateau surfaces in northwestern Arizonaoodeeplyorooted solution-collapse breccia pipes, near-surface gypsum collapses, and sinkholes. Of the 50 features that were sampled in this study, 3 are confirmed breccia pipes that contain significant uranium and base-metal minerals, I is believed to be a sinkhole with no economic potential, and 4 are stratabound copper deposits whose possible relationship to breccia pipes is yet to be determined. The remaining collapse features are suspected to overlie breccia pipes, although some of these may represent near surface gypsum collapse features. However, no exploratory drilling results or breccia exposures exist to indicate their underlying structure. The low cost and ease of soil sampling suggested that this technique be evaluated for breccia pipe exploration. This report provides the locations and geochemical results for the soil sampling surveys and brief descriptions of the 50 collapse features. The analytical results of almost 2,000 soil samples are provided in tabular hardcopy and dBase III Plus diskcopy format. The analytical data is provided in digital format to allow the reader to choose their own methods for evaluating the effectiveness of soil sampling over known and suspected breccia pipes. A pilot survey conducted over 17 collapse features in 1984 suggested that soil sampling might be useful in distinguishing mineralized breccia pipes from other circular features. Followup detailed surveys in 1985 and 1986 used a radial sampling pattern at each of 50 sites; at least one third of the samples were collected from areas outside of the collapse feature to provide background data. Samples were consistently collected from 3-4 inches depth after the pilot survey showed that metal concentrations were similar in samples from 3-4 inches and 7-8 inches depth. The geochemical analyses of the <80 mesh fractions of the soil samples were performed by the U.S. Geological Survey Analytical Laboratories and Geochemical Services, Inc. The analytical methods applied to these samples by the U.S. Geological Survey laboratories included inductively coupled plasma-atomic emission spectroscopy, X-ray fluorescence spectrometry, neutron activation, atomic absorption, delayed neutron activation, and classical wet chemistry for carbon, fluorine, and sulfur. Geochemical Services, Inc. analyzed the soil samples by inductively coupled plasma emission spectroscopy.

Results Of Routine Strip Effluent Hold Tank, Decontaminated Salt Solution Hold Tank, Caustic Wash Tank And Caustic Storage Tank Samples From Modular Caustic-Side Solvent Extraction Unit During Macrobatch 6 Operations

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

Peters, T. B.

Strip Effluent Hold Tank (SEHT), Decontaminated Salt Solution Hold Tank (DSSHT), Caustic Wash Tank (CWT) and Caustic Storage Tank (CST) samples from the Interim Salt Disposition Project (ISDP) Salt Batch (“Macrobatch”) 6 have been analyzed for 238Pu, 90Sr, 137Cs, and by Inductively Coupled Plasma Emission Spectroscopy (ICPES). The Pu, Sr, and Cs results from the current Macrobatch 6 samples are similar to those from comparable samples in previous Macrobatch 5. In addition the SEHT and DSSHT heel samples (i.e. ‘preliminary’) have been analyzed and reported to meet NGS Demonstration Plan requirements. From a bulk chemical point of view, the ICPESmore » results do not vary considerably between this and the previous samples. The titanium results in the DSSHT samples continue to indicate the presence of Ti, when the feed material does not have detectable levels. This most likely indicates that leaching of Ti from MST has increased in ARP at the higher free hydroxide concentrations in the current feed.« less

Stability of cyclosporine solutions stored in polypropylene-polyolefin bags and polypropylene syringes.

PubMed

Li, Mengqing; Forest, Jean-Marc; Coursol, Christian; Leclair, Grégoire

2011-09-01

The stability of cyclosporine diluted to 0.2 or 2.5 mg/mL with 0.9% sodium chloride injection or 5% dextrose injection and stored in polypropylene-polyolefin containers or polypropylene syringes was evaluated. Intravenous cyclosporine solutions (0.2 and 2.5 mg/mL) were aseptically prepared and transferred to 250-mL polypropylene-polyolefin bags or 60-mL polypropylene syringes. Chemical stability was measured using a stability-indicating high-performance liquid chromatography (HPLC) assay. Physical stability was assessed by visual inspection and a dynamic light scattering (DLS) method. After 14 days, HPLC assay showed that the samples of i.v. cyclosporine stored in polypropylene-polyolefin bags remained chemically stable (>98% of initial amount remaining); the physical stability of the samples was confirmed by DLS and visual inspection. The samples stored in polypropylene syringes were found to contain an impurity (attributed to leaching of a syringe component by the solution) that could be detected by HPLC after 1 day; on further investigation, no leaching was detected when the syringes were exposed to undiluted i.v. cyclosporine 50 mg/mL for 10 minutes. Samples of i.v. cyclosporine solutions of 0.2 and 2.5 mg/mL diluted in 0.9% sodium chloride injection or 5% dextrose injection and stored at 25 °C in polypropylene-polyolefin bags were physically and chemically stable for at least 14 days. When stored in polypropylene syringes, the samples were contaminated by an impurity within 1 day; however, the short-term (i.e., ≤10 minutes) use of the syringes for the preparation and transfer of i.v. cyclosporine solution is considered safe.

Impact of laminar flow velocity of different acids on enamel calcium loss.

PubMed

Attin, T; Becker, K; Wiegand, A; Tauböck, T T; Wegehaupt, F J

2013-03-01

The aim of the study was to evaluate the impact of flow velocity under laminar flow conditions of different acidic solutions on enamel erosion. A total of 240 bovine enamel specimens were prepared and allocated to 30 groups (n = 8 each). Samples of 18 groups were superfused in a flow chamber system with laminar flow behavior using 1 ml of citric acid or hydrochloric acid (HCl) of pH 2.0, 2.6 or 3.0. Flow rates in the sample chamber were adjusted to 10, 60 or 100 μl/min. To simulate turbulent flow behavior, samples of six groups were immersed in 1 ml of the respective solution, which was vortexed (15 min, 600 rpm). For simulating non-agitated conditions, specimens of the remaining six groups were immersed in 1 ml of the respective solution without stirring. Calcium in the solutions, released from the enamel samples, was determined using Arsenazo III method. For acidic solutions of pH 2.6 and 3.0, erosive potential of citric acid was equivalent to that of HCl at a flow of 100 μl/min. The same observation was made for the samples subjected to turbulent conditions at pH 3. At all other conditions, citric acid induced a significantly higher calcium loss than HCl. It is concluded that under slow laminar flow conditions, flow rate variations lead to higher erosive impact of citric acid compared to hydrochloric acid at pH 2.0, but not at pH ≥ 2.6 and increasing laminar flow or turbulent conditions. Erosive enamel dissolution under laminar flow conditions is a complex issue influenced by flow rate and acidic substrate.

Optical molecular fluorescence determination of ultra-trace beryllium in occupational and environmental samples using highly alkaline conditions

PubMed Central

Adams, Lori; Agrawal, Anoop; Cronin, John P.; Ashley, Kevin

2017-01-01

Exposures to beryllium (Be), even at extremely low levels, can cause severe health effects in a percentage of those exposed; consequently, occupational exposure limits (OELs) promulgated for this element are the lowest established for any element. This work describes the advantages of using highly alkaline dye solutions for determination of Be in occupational hygiene and environmental samples by means of an optical molecular fluorescence technique after sample extraction in 1–3% (w˖w−1) aqueous ammonium bifluoride (NH4HF2). Improved attributes include the ability to further enhance the detection limits of Be in extraction solutions of high acidity with minimal dilution, which is particularly beneficial when NH4HF2 solutions of higher concentration are used for extraction of Be from soil samples. Significant improvements in Be method detection limits (MDLs) are obtained at levels many-fold below those reported previously for this methodology. Notably, MDLs for Be of <0.01 ng l−1 / 0.1 ng per sample have been attained, which are superior to MDLs routinely reported for this element by means of the most widely used ultra-trace elemental measurement technique, inductively coupled plasma mass spectrometry (ICP-MS). Very low MDLs for Be are essential in consideration of reductions in OELs for this element in workplace air by health organizations and regulatory agencies in the USA and internationally. Applications of enhanced Be measurements to air filter samples, surface wipe samples, soils and newly-designed occupational air sampler inserts are illustrated. PMID:28626294

Finite element and analytical solutions for van der Pauw and four-point probe correction factors when multiple non-ideal measurement conditions coexist

NASA Astrophysics Data System (ADS)

Reveil, Mardochee; Sorg, Victoria C.; Cheng, Emily R.; Ezzyat, Taha; Clancy, Paulette; Thompson, Michael O.

2017-09-01

This paper presents an extensive collection of calculated correction factors that account for the combined effects of a wide range of non-ideal conditions often encountered in realistic four-point probe and van der Pauw experiments. In this context, "non-ideal conditions" refer to conditions that deviate from the assumptions on sample and probe characteristics made in the development of these two techniques. We examine the combined effects of contact size and sample thickness on van der Pauw measurements. In the four-point probe configuration, we examine the combined effects of varying the sample's lateral dimensions, probe placement, and sample thickness. We derive an analytical expression to calculate correction factors that account, simultaneously, for finite sample size and asymmetric probe placement in four-point probe experiments. We provide experimental validation of the analytical solution via four-point probe measurements on a thin film rectangular sample with arbitrary probe placement. The finite sample size effect is very significant in four-point probe measurements (especially for a narrow sample) and asymmetric probe placement only worsens such effects. The contribution of conduction in multilayer samples is also studied and found to be substantial; hence, we provide a map of the necessary correction factors. This library of correction factors will enable the design of resistivity measurements with improved accuracy and reproducibility over a wide range of experimental conditions.

Finite element and analytical solutions for van der Pauw and four-point probe correction factors when multiple non-ideal measurement conditions coexist.

PubMed

Reveil, Mardochee; Sorg, Victoria C; Cheng, Emily R; Ezzyat, Taha; Clancy, Paulette; Thompson, Michael O

2017-09-01

This paper presents an extensive collection of calculated correction factors that account for the combined effects of a wide range of non-ideal conditions often encountered in realistic four-point probe and van der Pauw experiments. In this context, "non-ideal conditions" refer to conditions that deviate from the assumptions on sample and probe characteristics made in the development of these two techniques. We examine the combined effects of contact size and sample thickness on van der Pauw measurements. In the four-point probe configuration, we examine the combined effects of varying the sample's lateral dimensions, probe placement, and sample thickness. We derive an analytical expression to calculate correction factors that account, simultaneously, for finite sample size and asymmetric probe placement in four-point probe experiments. We provide experimental validation of the analytical solution via four-point probe measurements on a thin film rectangular sample with arbitrary probe placement. The finite sample size effect is very significant in four-point probe measurements (especially for a narrow sample) and asymmetric probe placement only worsens such effects. The contribution of conduction in multilayer samples is also studied and found to be substantial; hence, we provide a map of the necessary correction factors. This library of correction factors will enable the design of resistivity measurements with improved accuracy and reproducibility over a wide range of experimental conditions.

Evaluation of field sampling and preservation methods for strontium-90 in ground water at the Idaho National Engineering Laboratory, Idaho

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

Cecil, L.D.; Knobel, L.L.; Wegner, S.J.

1989-09-01

From 1952 to 1988, about 140 curies of strontium-90 have been discharged in liquid waste to disposal ponds and wells at the INEL (Idaho National Engineering Laboratory). The US Geological Survey routinely samples ground water from the Snake River Plain aquifer and from discontinuous perched-water zones for selected radionuclides, major and minor ions, and chemical and physical characteristics. Water samples for strontium-90 analyses collected in the field are unfiltered and preserved to an approximate 2-percent solution with reagent-grade hydrochloric acid. Water from four wells completed in the Snake River Plain aquifer was sampled as part of the US Geological Survey'smore » quality-assurance program to evaluate the effect of filtration and preservation methods on strontium-90 concentrations in ground water at the INEL. The wells were selected for sampling on the basis of historical concentrations of strontium-90 in ground water. Water from each well was filtered through either a 0.45- or a 0.1-micrometer membrane filter; unfiltered samples also were collected. Two sets of filtered and two sets of unfiltered water samples were collected at each well. One set of water samples was preserved in the field to an approximate 2-percent solution with reagent-grade hydrochloric acid and the other set of samples was not acidified. 13 refs., 2 figs., 6 tabs.« less

Factor Covariance Analysis in Subgroups.

ERIC Educational Resources Information Center

Pennell, Roger

The problem considered is that of an investigator sampling two or more correlation matrices and desiring to fit a model where a factor pattern matrix is assumed to be identical across samples and we need to estimate only the factor covariance matrix and the unique variance for each sample. A flexible, least squares solution is worked out and…

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING A LIGHT TRANSMISSION VISUALIZATION METHOD - 3

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING A LIGHT TRANSMISSION VISUALIZATION METHOD - 2

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

THE QUANTIFICATION OF AQUEOUS TRACERS IN LABORATORY AQUIFER MODELS USING A LIGHT TRANSMISSION VISUALIZATION METHOD - 1

EPA Science Inventory

The quantification of solute concentrations in laboratory aquifer models has been largely limited to the use of sampling ports, from which samples are collected for external analysis. One of the drawbacks to this method is that the act of sampling may disturb plume dynamics and ...

Multi-elemental analysis of aqueous geochemical samples by quadrupole inductively coupled plasma-mass spectrometry (ICP-MS)

USGS Publications Warehouse

Wolf, Ruth E.; Adams, Monique

2015-01-01

Typically, quadrupole inductively coupled plasma-mass spectrometry (ICP-MS) is used to determine as many as 57 major, minor, and trace elements in aqueous geochemical samples, including natural surface water and groundwater, acid mine drainage water, and extracts or leachates from geological samples. The sample solution is aspirated into the inductively coupled plasma (ICP) which is an electrodeless discharge of ionized argon gas at a temperature of approximately 6,000 degrees Celsius. The elements in the sample solution are subsequently volatilized, atomized, and ionized by the ICP. The ions generated are then focused and introduced into a quadrupole mass filter which only allows one mass to reach the detector at a given moment in time. As the settings of the mass analyzer change, subsequent masses are allowed to impact the detector. Although the typical quadrupole ICP-MS system is a sequential scanning instrument (determining each mass separately), the scan speed of modern instruments is on the order of several thousand masses per second. Consequently, typical total sample analysis times of 2–3 minutes are readily achievable for up to 57 elements.

A new x-ray interface and surface scattering environmental cell design for in situ studies of radioactive and atmosphere-sensitive samples.

PubMed

Schmidt, M; Eng, P J; Stubbs, J E; Fenter, P; Soderholm, L

2011-07-01

We present a novel design of a purpose-built, portable sample cell for in situ x-ray scattering experiments of radioactive or atmosphere sensitive samples. The cell has a modular design that includes two independent layers of containment that are used simultaneously to isolate the sensitive samples. Both layers of containment can be flushed with an inert gas, thus serving a double purpose as containment of radiological material (either as a solid sample or as a liquid phase) and in separating reactive samples from the ambient atmosphere. A remote controlled solution flow system is integrated into the containment system that allows sorption experiments to be performed on the diffractometer. The cell's design is discussed in detail and we demonstrate the cell's performance by presenting first results of crystal truncation rod measurements. The results were obtained from muscovite mica single crystals reacted with 1 mM solutions of Th(IV) with 0.1 M NaCl background electrolyte. Data were obtained in specular as well as off-specular geometry.

Microwave-assisted extraction and mild saponification for determination of organochlorine pesticides in oyster samples.

PubMed

Carro, N; García, I; Ignacio, M-C; Llompart, M; Yebra, M-C; Mouteira, A

2002-10-01

A sample-preparation procedure (extraction and saponification) using microwave energy is proposed for determination of organochlorine pesticides in oyster samples. A Plackett-Burman factorial design has been used to optimize the microwave-assisted extraction and mild saponification on a freeze dried sample spiked with a mixture of aldrin, endrin, dieldrin, heptachlor, heptachorepoxide, isodrin, transnonachlor, p, p'-DDE, and p, p'-DDD. Six variables: solvent volume, extraction time, extraction temperature, amount of acetone (%) in the extractant solvent, amount of sample, and volume of NaOH solution were considered in the optimization process. The results show that the amount of sample is statistically significant for dieldrin, aldrin, p, p'-DDE, heptachlor, and transnonachlor and solvent volume for dieldrin, aldrin, and p, p'-DDE. The volume of NaOH solution is statistically significant for aldrin and p, p'-DDE only. Extraction temperature and extraction time seem to be the main factors determining the efficiency of extraction process for isodrin and p, p'-DDE, respectively. The optimized procedure was compared with conventional Soxhlet extraction.

Preparation and validation of gross alpha/beta samples used in EML`s quality assessment program

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

Scarpitta, S.C.

1997-10-01

A set of water and filter samples have been incorporated into the existing Environmental Measurements Laboratory`s (EML) Quality Assessment Program (QAP) for gross alpha/beta determinations by participating DOE laboratories. The participating laboratories are evaluated by comparing their results with the EML value. The preferred EML method for measuring water and filter samples, described in this report, uses gas flow proportional counters with 2 in. detectors. Procedures for sample preparation, quality control and instrument calibration are presented. Liquid scintillation (LS) counting is an alternative technique that is suitable for quantifying both the alpha ({sup 241}Am, {sup 230}Th and {sup 238}Pu) andmore » beta ({sup 90}Sr/{sup 90}Y) activity concentrations in the solutions used to prepare the QAP water and air filter samples. Three LS counting techniques (Cerenkov, dual dpm and full spectrum analysis) are compared. These techniques may be used to validate the activity concentrations of each component in the alpha/beta solution before the QAP samples are actually prepared.« less

Design and characterization of a mapping device optimized to collect XRD patterns from highly inhomogeneous and low density powder samples

NASA Astrophysics Data System (ADS)

D'Elia, A.; Cibin, G.; Robbins, P. E.; Maggi, V.; Marcelli, A.

2017-11-01

We report on the development of a device designed to improve X-ray Powder Diffraction data acquisition through mapping coupled to a rotational motion of the sample. The device and procedures developed aim at overcoming the experimental issues that accompany the analysis of inhomogeneous samples, such as powders, dust or aerosols deposited on a flat substrate. Introducing the mapping of the substrate on which powders are deposited and at the same time the rotation, we may overcome drawbacks associated to inhomogeneous distributions such as ring-like patterns due to the coffee stain effect generated by the evaporation of a solution. Experimental data have been collected from powders of a NIST standard soil sample (11 μg) and from an airborne dust extracted from deep ice cores in Antarctica (9.6 μg). Both particulate samples have been deposited on polycarbonate membranes from ultra-dilute solutions. Data show that this approach makes possible to collect XRD patterns useful to identify mineral fractions present in these low density samples.

Dust control at longwalls with water infusion and foam. Technical progress report through November 30, 1982

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

Not Available

1982-01-01

Foam spray equipment and materials for dust suppression on longwall double drum shearer faces have been procured. This equipment includes metering pumps, foam generators and mounting brackets, foam solutions, flow meters, real time and gravimetric sampling equipment, hoses and valve banks. Initial tests have been conducted in the laboratory with three types of generators and five types of foam solutions. Based on these tests, Senior Conflow's cluster spray and Onyx Chemical Company's millifoam solution have been selected. For pumping foam solution to the shearer, Jon Bean's 2 hp, 120 VAC single-phase ceramic lined piston pump has been selected. For fieldmore » tests, equipment has been installed underground in Dobbin mine in Upper Freeport seam on Eickhoff EDW 300 double drum shearer. Foamspray tests have been conducted. Real time and gravimetric dust samples have been collected. Real time sampling results indicate a dust level reduction of up to 37 percent with foam spray compared to the base case of water sprays.« less

Evaluation of atomic layer deposited alumina as a protective layer for domestic silver articles: Anti-corrosion test in artificial sweat

NASA Astrophysics Data System (ADS)

Park, Suk Won; Han, Gwon Deok; Choi, Hyung Jong; Prinz, Fritz B.; Shim, Joon Hyung

2018-05-01

This study evaluated the effectiveness of alumina fabricated by atomic layer deposition (ALD) as a protective coating for silver articles against the corrosion caused by body contact. An artificial sweat solution was used to simulate body contact. ALD alumina layers of varying thicknesses ranging from 20 to 80 nm were deposited on sputtered silver samples. The stability of the protective layer was evaluated by immersing the coated samples in the artificial sweat solution at 25 and 35 °C for 24 h. We confirmed that a sufficiently thick layer of ALD alumina is effective in protecting the shape and light reflectance of the underlying silver, whereas the uncoated bare silver is severely degraded by the artificial sweat solution. Inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy were used for in-depth analyses of the chemical stability of the ALD-coated silver samples after immersion in the sweat solution.

A SENSITIVE METHOD FOR THE DETERMINATION OF CARBOXYHAEMOGLOBIN IN A FINGER PRICK SAMPLE OF BLOOD

PubMed Central

Commins, B. T.; Lawther, P. J.

1965-01-01

About 0·01 ml. of blood taken from a finger prick is dissolved in 10 ml. of 0·04% ammonia solution. The solution is divided into two halves, and oxygen is bubbled through one half to convert any carboxyhaemoglobin into oxyhaemoglobin. The spectra of the two halves are then compared in a spectrophotometer, and the difference between them is used to estimate the carboxyhaemoglobin content of the blood either graphically or by calculation from a simple formula. Calibration is simple and need only be done once. A sample of blood can be analysed in about 20 minutes, which includes the time to collect the sample. The method is sensitive enough to be used for the analysis of solutions of blood containing less than 1% carboxyhaemoglobin. PMID:14278801

A novel method for the determination of synthetic colors in ice cream samples.

PubMed

Tripathi, Meenakshi; Khanna, Subhash K; Das, Mukul

2004-01-01

A simple method has been developed for the extraction, separation, and determination of synthetic colors in ice cream samples. The process involves the breakdown of emulsion by neutral detergents (Triton X-100 and Tween 20) followed by extraction with petroleum ether for removal of fat. The aqueous colored solution obtained is treated with 5% acetic acid, and the uptake of color is carried out by a wool-dyeing technique. The color is eluted from the wool with 5% ammonia solution, the solution is evaporated to dryness, and the residue is dissolved in 60% ethanol for paper chromatography using trisodium citrate-ammonia-water (2 + 5 + 95, w/v/v) as the mobile phase. The colored spots from the paper chromatogram are cut and eluted with 60% ethanol, and the absorbance is measured at the respective lambda maximum corresponding to the Rf value of the appropriate standard. The recoveries of 6 colors, including sunset yellow FCF (SSYFCF), tartrazine, carmoisine, ponceau 4R, brilliant blue FCF (BBFCF), and fast green FCF from spiked samples with either detergent were found to be >90%. However, recoveries of erythrosine were 21 and 65% with Triton X-100 and Tween 20, respectively. Indigo carmine could not be recovered at all because of its fugitive property in 5% ammonia solution, which is used to strip the color from the wool. The sensitivity of the method with the use of Tween 20 is 1 ppm (1 microg/g) for the colors in spiked ice cream samples. With this method, we analyzed samples of 20 branded colored ice cream. The results showed the presence of tartrazine (8.4-43.3 ppm), SSYFCF (23.5-117.6 ppm), carmoisine (traces-53.2 ppm), erythrosine (3.5 ppm), and BBFCF (4.1 ppm) in the ice cream samples. Apart from 2 samples of tuttifruity, all of the ice cream samples showed the presence of permitted synthetic colors below the permissible level of 100 ppm established by the Prevention of Food Adulteration Act of India.

Simulation of water-quality data at selected stream sites in the Missouri River Basin, Montana

USGS Publications Warehouse

Knapton, J.R.; Jacobson, M.A.

1980-01-01

Modification of sampling programs at some water-quality stations in the Missouri River basin in Montana has eliminated the means by which solute loads have been directly obtained in past years. To compensate for this loss, water-quality and streamflow data were statistically analyzed and solute loads were simulated using computer techniques.Functional relationships existing between specific conductance and solute concentration for monthly samples were used to develop linear regression models. The models were then used to simulate daily solute concentrations using daily specific conductance as the independent variable. Once simulated, the solute concentrations, in milligrams per liter, were transformed into daily solute loads, in tons, using mean daily streamflow records.Computer output was formatted into tables listing simulated mean monthly solute concentrations, in milligrams per liter, and the monthly and annual solute loads, in tons, for water years 1975-78.

A comparison of water solubility enhancements of organic solutes by aquatic humic materials and commercial humic acids

USGS Publications Warehouse

Chlou, C.T.; Kile, D.E.; Brinton, T.I.; Malcolm, R.L.; Leenheer, J.A.; MacCarthy, P.

1987-01-01

Water solubility enhancements of 1,1-bis(p-chloro-phenyl)-2,2,2-trichloroethane (p,p???-DDT), 2,4,5,2???,5???-pentachlorobiphenyl (2,4,5,2???,5???-PCB), and 2,4,4???-tri-chlorobiphenyl (2,4,4???-PCB) by dissolved organic matter have been studied with the following samples: (1) acidic water samples from the Suwannee River, Georgia, and the Sopchoppy River, Florida; (2) a humic extract of a nearly neutral pH water from the Calcasieu River, Louisiana; (3) commercial humic acids from the Aldrich Chemical Co. and Fluka-Tridom Chemical Corp. The calculated partition coefficients on a dissolved organic carbon basis (Kdoc) for organic solutes with water samples and aquatic humic extracts from this and earlier studies indicate that the enhancement effect varies with the molecular composition of the aquatic humic materials. The Kdoc values with water and aquatic humic samples are, however, far less than the observed Kdoc values obtained with the two commercial samples, by factors of about 4-20. In view of this finding, one should be cautious in interpreting the effects of the dissolved organic matter on solubility enhancement of organic solutes on the basis of the use of commercial humic acids.

General solution of undersampling frequency conversion and its optimization for parallel photodisplacement imaging.

PubMed

Nakata, Toshihiko; Ninomiya, Takanori

2006-10-10

A general solution of undersampling frequency conversion and its optimization for parallel photodisplacement imaging is presented. Phase-modulated heterodyne interference light generated by a linear region of periodic displacement is captured by a charge-coupled device image sensor, in which the interference light is sampled at a sampling rate lower than the Nyquist frequency. The frequencies of the components of the light, such as the sideband and carrier (which include photodisplacement and topography information, respectively), are downconverted and sampled simultaneously based on the integration and sampling effects of the sensor. A general solution of frequency and amplitude in this downconversion is derived by Fourier analysis of the sampling procedure. The optimal frequency condition for the heterodyne beat signal, modulation signal, and sensor gate pulse is derived such that undesirable components are eliminated and each information component is converted into an orthogonal function, allowing each to be discretely reproduced from the Fourier coefficients. The optimal frequency parameters that maximize the sideband-to-carrier amplitude ratio are determined, theoretically demonstrating its high selectivity over 80 dB. Preliminary experiments demonstrate that this technique is capable of simultaneous imaging of reflectivity, topography, and photodisplacement for the detection of subsurface lattice defects at a speed corresponding to an acquisition time of only 0.26 s per 256 x 256 pixel area.

Comparison of microdialysis sampling perfusion fluid components on the foreign body reaction in rat subcutaneous tissue.

PubMed

Keeler, Geoffrey D; Durdik, Jeannine M; Stenken, Julie A

2014-06-16

Microdialysis sampling is a commonly used technique for collecting solutes from the extracellular space of tissues in laboratory animals and humans. Large molecular weight solutes can be collected using high molecular weight cutoff (MWCO) membranes (100kDa or greater). High MWCO membranes require addition of high molecular weight dextrans or albumin to the perfusion fluid to prevent fluid loss via ultrafiltration. While these perfusion fluid additives are commonly used during microdialysis sampling, the tissue response to the loss of these compounds across the membrane is poorly understood. Tissue reactions to implanted microdialysis sampling probes containing different microdialysis perfusion fluids were compared over a 7-day time period in rats. The base perfusion fluid was Ringer's solution supplemented with either bovine serum albumin (BSA), rat serum albumin (RSA), Dextran-70, or Dextran-500. A significant inflammatory response to Dextran-70 was observed. No differences in the tissue response between BSA and RSA were observed. Among these agents, the BSA, RSA, and Dextran-500 produced a significantly reduced inflammatory response compared to the Dextran-70. This work demonstrates that use of Dextran-70 in microdialysis sampling perfusion fluids should be eliminated and replaced with Dextran-500 or other alternatives. Copyright © 2013 Elsevier B.V. All rights reserved.

Highly-transparent multi-layered spin-coated silk fibroin film

NASA Astrophysics Data System (ADS)

Wasapinyokul, Kamol; Kaewpirom, Supranee; Chuwongin, Santhad; Boonsang, Siridech

2017-10-01

In this study, the silk fibroin films with different numbers of layers were fabricated by the spin-coating method and their optical transmittances were observed. The process to synthesise the silk fibroin solution was explained - starting from the silk cocoon until the silk-fibroin solution, approximately 7.5% concentration wt/vol, was obtained. The solution was spin-coated onto clean glass substrates to fabricate samples. Totally 10 samples with different numbers of layers, from 1 to 5 layers, were obtained. All samples can be separated into two groups: those left dried at room temperature after spin-coating and those heated at 60°C. They were then measured for their transmittance over the visible-to-near-infrared region. All samples exhibited the high transmittance where the values were at 95% and 98%, for the samples at room temperature and those at 60°C, respectively. This was believed to be due to the heating effect that caused the silk fibroin to arrange itself after being heated, hence the higher transmittance. These high transmittances were maintained regardless of the number of layers and length of heating time. Results from this study could be used to fabricate a silk fibroin film with high optical transmittance and adjustable other properties.

Storage of cell samples for ToF-SIMS experiments-How to maintain sample integrity.

PubMed

Schaepe, Kaija; Kokesch-Himmelreich, Julia; Rohnke, Marcus; Wagner, Alena-Svenja; Schaaf, Thimo; Henss, Anja; Wenisch, Sabine; Janek, Jürgen

2016-06-25

In order to obtain comparable and reproducible results from time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of biological cells, the influence of sample preparation and storage has to be carefully considered. It has been previously shown that the impact of the chosen preparation routine is crucial. In continuation of this work, the impact of storage needs to be addressed, as besides the fact that degradation will unavoidably take place, the effects of different storage procedures in combination with specific sample preparations remain largely unknown. Therefore, this work examines different wet (buffer, water, and alcohol) and dry (air-dried, freeze-dried, and critical-point-dried) storage procedures on human mesenchymal stem cell cultures. All cell samples were analyzed by ToF-SIMS immediately after preparation and after a storage period of 4 weeks. The obtained spectra were compared by principal component analysis with lipid- and amino acid-related signals known from the literature. In all dry storage procedures, notable degradation effects were observed, especially for lipid-, but also for amino acid-signal intensities. This leads to the conclusion that dried samples are to some extent easier to handle, yet the procedure is not the optimal storage solution. Degradation proceeds faster, which is possibly caused by oxidation reactions and cleaving enzymes that might still be active. Just as well, wet stored samples in alcohol struggle with decreased signal intensities from lipids and amino acids after storage. Compared to that, the wet stored samples in a buffered or pure aqueous environment revealed no degradation effects after 4 weeks. However, this storage bears a higher risk of fungi/bacterial contamination, as sterile conditions are typically not maintained. Thus, regular solution change is recommended for optimized storage conditions. Not directly exposing the samples to air, wet storage seems to minimize oxidation effects, and hence, buffer or water storage with regular renewal of the solution is recommended for short storage periods.

Storage of cell samples for ToF-SIMS experiments—How to maintain sample integrity

PubMed Central

Schaepe, Kaija; Kokesch-Himmelreich, Julia; Rohnke, Marcus; Wagner, Alena-Svenja; Schaaf, Thimo; Henss, Anja; Wenisch, Sabine; Janek, Jürgen

2016-01-01

In order to obtain comparable and reproducible results from time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of biological cells, the influence of sample preparation and storage has to be carefully considered. It has been previously shown that the impact of the chosen preparation routine is crucial. In continuation of this work, the impact of storage needs to be addressed, as besides the fact that degradation will unavoidably take place, the effects of different storage procedures in combination with specific sample preparations remain largely unknown. Therefore, this work examines different wet (buffer, water, and alcohol) and dry (air-dried, freeze-dried, and critical-point-dried) storage procedures on human mesenchymal stem cell cultures. All cell samples were analyzed by ToF-SIMS immediately after preparation and after a storage period of 4 weeks. The obtained spectra were compared by principal component analysis with lipid- and amino acid-related signals known from the literature. In all dry storage procedures, notable degradation effects were observed, especially for lipid-, but also for amino acid-signal intensities. This leads to the conclusion that dried samples are to some extent easier to handle, yet the procedure is not the optimal storage solution. Degradation proceeds faster, which is possibly caused by oxidation reactions and cleaving enzymes that might still be active. Just as well, wet stored samples in alcohol struggle with decreased signal intensities from lipids and amino acids after storage. Compared to that, the wet stored samples in a buffered or pure aqueous environment revealed no degradation effects after 4 weeks. However, this storage bears a higher risk of fungi/bacterial contamination, as sterile conditions are typically not maintained. Thus, regular solution change is recommended for optimized storage conditions. Not directly exposing the samples to air, wet storage seems to minimize oxidation effects, and hence, buffer or water storage with regular renewal of the solution is recommended for short storage periods. PMID:26810048

Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 (13C) and hydrogen-1 (1H) nuclear magnetic resonance spectrometry

USGS Publications Warehouse

Thorn, Kevin A.; Folan, Daniel W.; MacCarthy, Patrick

1989-01-01

Standard and reference samples of the International Humic Substances Society have been characterized by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance (NMR) spectrometry. Samples included the Suwannee River, soil, and peat standard fulvic and humic acids, the Leonardite standard humic acid, the Nordic aquatic reference fulvic and humic acids, and the Summit Hill soil reference humic acid. Aqueous-solution carbon-13 NMR analyses included the measurement of spin-lattice relaxation times, measurement of nuclear Overhauser enhancement factors, measurement of quantitative carbon distributions, recording of attached proton test spectra, and recording of spectra under nonquantitative conditions. Distortionless enhancement by polarization transfer carbon-13 NMR spectra also were recorded on the Suwannee River fulvic acid in deuterated dimethyl sulfoxide. Hydrogen-1 NMR spectra were recorded on sodium salts of the samples in deuterium oxide. The carbon aromaticities of the samples ranged from 0.24 for the Suwannee River fulvic acid to 0.58 for the Leonardite humic acid.

Pulp tissue dissolution capacity of QMix 2in1 irrigation solution.

PubMed

Arslan, Dilara; Guneser, Mehmet Burak; Kustarci, Alper; Er, Kursat; Siso, Seyda Herguner

2015-01-01

The aim of this study was to evaluate the tissue dissolution efficacy of four root canal irrigation solutions (sodium hypochlorite [NaOCl], chlorhexidine gluconate [CHX], Octenidine [OCT], and QMix 2in1) on bovine pulp tissue. Fifty bovine pulp tissue samples, each weighing 6.55 mg, were prepared and randomly divided into four experimental groups and one control group (n = 10) according to the dissolution irrigants used: (1) 5.25% NaOCl group; (2) 2% CHX group; (3) OCT group; (4) QMix 2in1 group; and (5) control group (saline solution). These samples were then placed into special bovine dentin reservoir models and immersed for 1 h with each test solution (0.1 mL of each) at room temperature. The pulp samples were then blotted dry and weighed again. The percentage of weight loss was calculated. Statistically analyzed with one-way analysis of variance and post-hoc Tukey tests (P = 0.05). Saline solution did not dissolve the bovine pulp tissue. All groups, except OCT, dissolved pulp samples more effectively than the control group (P < 0.05). The highest tissue dissolution was observed in 5.25% NaOCl group (P < 0.05). No statistically significant difference was found between the tissue-dissolving effect between QMix 2in1 and those of 2% CHX. Within the limitations of this in vitro study, NaOCl exhibited the best tissue-dissolving effect out of all solutions tested. CHX and QMix 2in1 were able to dissolve pulp tissue but less than NaOCl. OCT and saline solutions could not exhibit significantly tissue-dissolving effectiveness. This study shown that QMix 2in1 has little capacity to dissolve pulp tissue therefore used alone is not sufficient for this purpose.

Pulp tissue dissolution capacity of QMix 2in1 irrigation solution

PubMed Central

Arslan, Dilara; Guneser, Mehmet Burak; Kustarci, Alper; Er, Kursat; Siso, Seyda Herguner

2015-01-01

Objective: The aim of this study was to evaluate the tissue dissolution efficacy of four root canal irrigation solutions (sodium hypochlorite [NaOCl], chlorhexidine gluconate [CHX], Octenidine [OCT], and QMix 2in1) on bovine pulp tissue. Materials and Methods: Fifty bovine pulp tissue samples, each weighing 6.55 mg, were prepared and randomly divided into four experimental groups and one control group (n = 10) according to the dissolution irrigants used: (1) 5.25% NaOCl group; (2) 2% CHX group; (3) OCT group; (4) QMix 2in1 group; and (5) control group (saline solution). These samples were then placed into special bovine dentin reservoir models and immersed for 1 h with each test solution (0.1 mL of each) at room temperature. The pulp samples were then blotted dry and weighed again. The percentage of weight loss was calculated. Statistically analyzed with one-way analysis of variance and post-hoc Tukey tests (P = 0.05). Results: Saline solution did not dissolve the bovine pulp tissue. All groups, except OCT, dissolved pulp samples more effectively than the control group (P < 0.05). The highest tissue dissolution was observed in 5.25% NaOCl group (P < 0.05). No statistically significant difference was found between the tissue-dissolving effect between QMix 2in1 and those of 2% CHX. Conclusions: Within the limitations of this in vitro study, NaOCl exhibited the best tissue-dissolving effect out of all solutions tested. CHX and QMix 2in1 were able to dissolve pulp tissue but less than NaOCl. OCT and saline solutions could not exhibit significantly tissue-dissolving effectiveness. This study shown that QMix 2in1 has little capacity to dissolve pulp tissue therefore used alone is not sufficient for this purpose. PMID:26430374

A Pilot Chemical and Physical Stability Study of Extemporaneously Compounded Levetiracetam Intravenous Solution.

PubMed

Raphael, Chenzira D; Zhao, Fang; Hughes, Susan E; Juba, Katherine M

2015-01-01

Levetiracetam is a commonly used antiepileptic medication for tumor-related epilepsy. However, the 100 mL intravenous (IV) infusion volume can be burdensome to imminently dying hospice patients. A reduced infusion volume would improve patient tolerability. The purpose of this study was to evaluate the stability of 1000 mg/25 mL (40 mg/mL) levetiracetam IV solution in sodium chloride 0.9%. We prepared levetiracetam 40 mg/mL IV solution and added it to polyvinyl chloride (PVC) bags, polyolefin bags, and polypropylene syringes. Triplicate samples of each product were stored at refrigeration (2-8°C) and analyzed on days 0, 1, 4, 7, and 14. Samples were subjected to visual inspection, pH measurement, and stability-indicating high-performance liquid chromatography (HPLC) analysis. Over the 2-week storage period, there was no significant change in visual appearance or pH for any of the stability samples. The HPLC results confirmed that all stability samples retained 94.2-101.3% of initial drug concentration and no degradation products or leachable material from the packaging materials were observed. We conclude that levetiracetam 1000 mg/25 mL IV solution in sodium chloride 0.9% is physically and chemically stable for up to 14 days under refrigeration in polypropylene syringes, PVC bags, and polyolefin bags.

High sensitive analysis of steroids in doping control using gas chromatography/time-of-flight mass-spectrometry.

PubMed

Revelsky, A I; Samokhin, A S; Virus, E D; Rodchenkov, G M; Revelsky, I A

2011-04-01

The method of high sensitive gas chromatographic/time-of-flight mass-spectrometric (GC/TOF-MS) analysis of steroids was developed. Low-resolution TOF-MS instrument (with fast spectral acquisition rate) was used. This method is based on the formation of the silyl derivatives of steroids; exchange of the reagent mixture (pyridine and N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)) for tert-butylmethylether; offline large sample volume injection of this solution based on sorption concentration of the respective derivatives from the vapour-gas mixture flow formed from the solution and inert gas flows; and entire analytes solvent-free concentrate transfer into the injector of the gas chromatograph. Detection limits for 100 µl sample solution volume were 0.5-2 pg/µl (depending on the component). Application of TOF-MS model 'TruTOF' (Leco, St Joseph, MO, USA) coupled with gas chromatograph and ChromaTOF software (Leco, St Joseph, MO, USA) allowed extraction of the full mass spectra and resolving coeluted peaks. Due to use of the proposed method (10 µl sample aliquot) and GC/TOF-MS, two times more steroid-like compounds were registered in the urine extract in comparison with the injection of 1 µl of the same sample solution. Copyright © 2010 John Wiley & Sons, Ltd.

Bi2MoxW1-xO6 solid solutions with tunable band structure and enhanced visible-light photocatalytic activities

NASA Astrophysics Data System (ADS)

Li, Wenqi; Ding, Xingeng; Wu, Huating; Yang, Hui

2018-07-01

Semiconductor photocatalysis is an effective green way to combat water pollution. For the first time, this study reports a novel method to develop Bi2MoxW1-xO6 solid solution with microsphere structure through anion-exchange method. All Bi2MoxW1-xO6 samples exhibit an Aurivillius-type crystal structure without any secondary phase, confirming that in complete solid solutions as the value of x increases, the band gap energy of Bi2MoxW1-xO6 solid solutions decreases, while the optical absorption edge moves to longer wavelength. The Raman spectra research shows an increase in orthorhombic distortion with progressive replacement of W sites in Bi2WO6 with Mo6+ ions. Compared to Bi2MoO6 and Bi2WO6 samples, Bi2Mo0.4W0.6O6 sample displayed best photocatalytic activity and cycling stability for degradation of RhB dye. The enhanced photocatalytic activity of Bi2Mo0.4W0.6O6 sample can be synergetically linked to hierarchical hollow structure, enhanced light absorbance, and high carrier-separation efficiency. Additionally, the hollow Bi2MoxW1-xO6 microspheres formation can be attributed to the Kirkendall effect.

Cloud point extraction of vanadium in pharmaceutical formulations, dialysate and parenteral solutions using 8-hydroxyquinoline and nonionic surfactant.

PubMed

Khan, Sumaira; Kazi, Tasneem G; Baig, Jameel A; Kolachi, Nida F; Afridi, Hassan I; Wadhwa, Sham Kumar; Shah, Abdul Q; Kandhro, Ghulam A; Shah, Faheem

2010-10-15

A cloud point extraction (CPE) method has been developed for the determination of trace quantity of vanadium ions in pharmaceutical formulations (PF), dialysate (DS) and parenteral solutions (PS). The CPE of vanadium (V) using 8-hydroxyquinoline (oxine) as complexing reagent and mediated by nonionic surfactant (Triton X-114) was investigated. The parameters that affect the extraction efficiency of CPE, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of CPE of V was checked by standard addition method in real samples. The extracted surfactant-rich phase was diluted with nitric acid in ethanol, prior to subjecting electrothermal atomic absorption spectrometry. Under these conditions, the preconcentration of 50 mL sample solutions, allowed raising an enrichment factor of 125-fold. The lower limit of detection obtained under the optimal conditions was 42 ng/L. The proposed method has been successfully applied to the determination of trace quantity of V in various pharmaceutical preparations with satisfactory results. The concentration ranges of V in PF, DS and PS samples were found in the range of 10.5-15.2, 0.65-1.32 and 1.76-6.93 microg/L, respectively. 2010 Elsevier B.V. All rights reserved.

Application of a thiourea-containing task-specific ionic liquid for the solid-phase extraction cleanup of lead ions from red lipstick, pine leaves, and water samples.

PubMed

Saljooqi, Asma; Shamspur, Tayebeh; Mohamadi, Maryam; Mostafavi, Ali

2014-07-01

Here, task-specific ionic liquid solid-phase extraction is proposed for the first time. In this approach, a thiourea-functionalized ionic liquid is immobilized on the solid sorbent, multiwalled carbon nanotubes. These modified nanotubes packed into a solid-phase extraction column are used for the selective extraction and preconcentration of ultra-trace amounts of lead(II) from aqueous samples prior to electrothermal atomic absorption spectroscopy determination. The thiourea functional groups act as chelating agents for lead ions retaining them and so, give the selectivity to the sorbent. Elution of the retained ions can be performed using an acidic thiourea solution. The effects of experimental parameters including pH of the aqueous solution, type and amount of eluent, and the flow rates of sample and eluent solutions on the separation efficiency are investigated. The linear dependence of absorbance of lead on its concentration in the initial solution is in the range of 0.5-40.0 ng/mL with the detection limit of 0.13 ng/mL (3(Sb)/m, n = 10). The proposed method is applicable to the analysis of red lipstick, pine leaves, and water samples for their lead contents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrasound-Assisted Emulsification Microextraction Based on Solidification Floating Organic Drop Trace Amounts of Manganese Prior to Graphite Furnace Atomic Absorption Spectrometry Determination

PubMed Central

Mohadesi, Alireza; Falahnejad, Masoumeh

2012-01-01

In the present study, an ultrasound-assisted emulsification microextraction based on solidification floating organic drop method is described for preconcentration of trace amounts of Mn (II). 2-(5-Bromo-2-pyridylazo)-5 diethylaminophenol was added to a solution of Mn+2 at ph = 10.0. After this, 1-undecanol was added to the solution as an extraction solvent, and solution was stirred. Several factors influencing the microextraction efficiency, such as pH, the amount of chelating agent, nature and volume of extraction solvent, the volume of sample solution, stirring rate, and extraction time were investigated and optimized. Then sample vial was cooled by inserting into an ice bath, and the solidified was transferred into a suitable vial for immediate melting. Finally the sample was injected into a graphite furnace atomic absorption spectrometry. Under the optimum condition the linear dynamic range was 0.50–10.0 ng mL−1 with a correlation coefficient of 0.9926, and the detection limit of 0.3 ng mL−1 was obtained. The enrichment factor was 160. The proposed method was successfully applied for separation and determination of manganese in sea, rain, tap, and river water samples. PMID:22645504

Micro-electromembrane extraction across free liquid membranes. Extractions of basic drugs from undiluted biological samples.

PubMed

Kubáň, Pavel; Boček, Petr

2014-04-11

This contribution describes properties and utilization of free liquid membranes (FLMs) in micro-electromembrane extraction (μ-EME) of analytes from samples with complex matrices. An FLM was formed as a plug of a selected organic solvent, 1-ethyl-2-nitrobenezene (ENB) or 2-nitrophenyloctyl ether, in a narrow bore polymeric tubing and was sandwiched between a plug of aqueous donor and aqueous acceptor solution. The FLM acted as a phase interface that enabled selective transfer of analytes from donor into acceptor solution. Acceptor solution after μ-EME was analysed by capillary electrophoresis (CE). Fundamental characteristics of FLMs were depicted and discussed by presenting experimental data on their performance for various basic operational parameters, such as composition and volume of donor/acceptor solution, applied extraction voltage, thickness of FLM and extraction time. Positively charged basic drugs (nortriptyline, haloperidol and loperamide) and their solutions in water, urine and blood serum served as model samples. It was shown that FLMs may offer fast, efficient and selective pretreatment of crude biological samples providing that basic operational parameters of μ-EME are set properly. At optimised conditions, basic drugs in 1.5μL of a biological sample were transferred across 1.5μL of FLM (ENB) into 1.5μL of acceptor solution in about 5min at an extraction voltage of 100V. Repeatability values of μ-EMEs and CE-UV analyses of the three basic drugs were better than 7.7% for peak areas, recoveries ranged between 19 and 52% and linear relationship was obtained for analytical signal vs. concentration in 1-50mgL(-1) range (r(2) better than 0.996). Limits of detection, defined as 3×S/N, were below 1mgL(-1) for all examined matrices. Copyright © 2014 Elsevier B.V. All rights reserved.

PHYSICO-CHEMICAL CHARACTERISATION OF DIFFERENT CLINDAMYCIN PHOSPHATE SAMPLES

PubMed Central

Vranić, Edina; Planinšek, Odon; Tivadar, Andrijana; Hadžović, Sabira; Srčič, Stanko

2007-01-01

For the majority of the pharmaceutical dosage forms, the substances that are used maintain solid state under the standard storage conditions, i.e. powders. The interactions of pharmaceutical powders (active ingredient(s) and excipients) with liquids and vapors (particularly aqueous solutions and their vapors) occur almost always during the production process. From the physical point of view, the interactions among individual components may differ from the expected because chemically identical substances obtained from different producers vary very much. These differences influence either the production process and/or the pharmaceutical form properties. In order to overcome these problems it is necessary to establish a control over the physico-chemical properties of the used materials. The aim of this work was to determine physico-chemical properties of three powder clindamycin phosphate samples (labeled as sample S1, S2 and S3) acquired through different suppliers. All the analysis were made for the purpose of establishing possible differences among the tested samples that showed variable physical stability in the solution: recrystallization of the S3 sample in the aqueous solution has been established during storage under standard conditions. On the basis of the obtained data it was possible to recognize the differences among the tested clindamycin phosphate samples and to explain the anomalous behavior of one sample. The surface free energy components for the investigated clindamycin phosphate samples were determined using Wu and Goodvan Oss method. The investigated clindamycin phosphate samples exhibit certain differences in surface free energy values as well as in surface morphology and thermal behavior. Comparison of γ+ and γ- values leads to the conclusion that all three clindamycin phosphate samples perform as monopolar, more electron acceptors, i.e. Lewis acids. However, an important difference exists between samples S1 and S2 on one and S3 on the other side. Sample S3 exhibits stronger acidic behavior, what could be connected with its recrystallization during the storage. The samples S1, S2 and S3 have different melting points e.g. “onset” temperatures. When the melting points move towards 200oC, the width of the “onset” temperature peak is especially important. In the case of wider peak, the potential for recrystallization seems to be higher. According to the stated, the sample S1 would be the “sample of choice” for the formulation of the stable pharmaceutical dosage form and has not shown any recrystallization tendencies during the storage period.

Physico-chemical characterisation of different clindamycin phosphate samples.

PubMed

Vranić, Edina; Planinsek, Odon; Tivadar, Andrijana; Hadzović, Sabira; Srcic, Stanko

2007-05-01

For the majority of the pharmaceutical dosage forms, the substances that are used maintain solid state under the standard storage conditions, i.e. powders. The interactions of pharmaceutical powders (active ingredient(s) and excipients) with liquids and vapors (particularly aqueous solutions and their vapors) occur almost always during the production process. From the physical point of view, the interactions among individual components may differ from the expected because chemically identical substances obtained from different producers vary very much. These differences influence either the production process and/or the pharmaceutical form properties. In order to overcome these problems it is necessary to establish a control over the physico-chemical properties of the used materials. The aim of this work was to determine physico-chemical properties of three powder clindamycin phosphate samples (labeled as sample S(1), S(2) and S(3)) acquired through different suppliers. All the analysis were made for the purpose of establishing possible differences among the tested samples that showed variable physical stability in the solution: recrystallization of the S(3) sample in the aqueous solution has been established during storage under standard conditions. On the basis of the obtained data it was possible to recognize the differences among the tested clindamycin phosphate samples and to explain the anomalous behavior of one sample. The surface free energy components for the investigated clindamycin phosphate samples were determined using Wu and Good- van Oss method. The investigated clindamycin phosphate samples exhibit certain differences in surface free energy values as well as in surface morphology and thermal behavior. Comparison of alpha + and alpha - values leads to the conclusion that all three clindamycin phosphate samples perform as monopolar, more electron acceptors, i.e. Lewis acids. However, an important difference exists between samples S(1) and S(2) on one and S(3) on the other side. Sample S(3) exhibits stronger acidic behavior, what could be connected with its recrystallization during the storage. The samples S(1), S(2) and S(3) have different melting points e.g. "onset" temperatures. When the melting points move towards 200 (o ) C, the width of the "onset" temperature peak is especially important. In the case of wider peak, the potential for recrystallization seems to be higher. According to the stated, the sample S1 would be the "sample of choice" for the formulation of the stable pharmaceutical dosage form and has not shown any recrystallization tendencies during the storage period.

The effect of acidified sample storage time on the determination of trace element concentration in ice cores by ICP-SFMS

NASA Astrophysics Data System (ADS)

Uglietti, C.; Gabrielli, P.; Lutton, A.; Olesik, J.; Thompson, L. G.

2012-12-01

Trace elements in micro-particles entrapped in ice cores are a valuable proxy of past climate and environmental variations. Inductively coupled plasma sector field mass spectrometry (ICP-SFMS) is generally recognized as a sensitive and accurate technique for the quantification of ultra-trace element concentrations in ice cores. Usually, ICP-SFMS analyses of ice core samples are performed by melting and acidifying aliquots. Acidification is important to transfer trace elements from particles into solution by partial and/or complete dissolution. Only elements in solution and in sufficiently small particles will be vaporized and converted to elemental ions in the plasma for detection by ICP-SFMS. However, experimental results indicate that differences in acidified sample storage time at room temperature may lead to the recovery of different trace element fractions. Moreover, different lithologies of the relatively abundant crustal material entrapped in the ice matrix could also influence the fraction of trace elements that are converted into elemental ions in the plasma. These factors might affect the determination of trace elements concentrations in ice core samples and hamper the comparison of results obtained from ice cores from different locations and/or epochs. In order to monitor the transfer of elements from particles into solution in acidified melted ice core samples during storage, a test was performed on sections from nine ice cores retrieved from low latitude drilling sites around the world. When compared to ice cores from polar regions, these samples are characterized by a relative high content of micro-particles that may leach trace elements into solution differently. Of the nine ice cores, five are from the Tibetan Plateau (Dasuopu, Guliya, Naimonanyi, Puruogangri and Dunde), two from the Andes (Quelccaya and Huascaran), one from Africa (Kilimanjaro) and one from the Eastern Alps (Ortles). These samples were decontaminated by triple rinsing, melted and stored in pre-cleaned low-density polyethylene bottles, and kept frozen until acidification (2% v/v ultra-pure HNO3). Determination of twenty trace elements (Ag, Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Pb, Rb, Sb, Sn, Ti, Tl, U, V, and Zn) was repeated at different times after acidification using the same aliquot. Analyses show a mean increase of 40-50% in trace element concentration in all the samples during the first 15 days of storage after acidification, except Al, Fe, V and Cr, which show a larger increase (90-100%). After 15 days the trace element concentrations reach generally stable values (with small increases within measurement uncertainty), except for the Naimonanyi and Kilimanjaro samples which continue to increase. In contrast, Ag concentration decreases after one week, likely due to its low stability in the acidified solution that may depend on the Cl- concentration. We froze the samples 43 days after the acidification. After two weeks the samples were melted and re-analyzed by ICP-SFMS in two different laboratories as an inter-calibration exercise. The results show a good correspondence between the measured concentrations determined by the two instruments and a consistent additional increase of 20-30% of measured trace element concentrations in almost all samples.

Quantitative analysis of fungicide azoxystrobin in agricultural samples with rapid, simple and reliable monoclonal immunoassay.

PubMed

Watanabe, Eiki; Miyake, Shiro

2013-01-15

This work presents analytical performance of a kit-based direct competitive enzyme-linked immunosorbent assay (dc-ELISA) for azoxystrobin detection in agricultural products. The dc-ELISA was sufficiently sensitive for analysis of residue levels close to the maximum residue limits. The dc-ELISA did not show cross-reactivity to other strobilurin analogues. Absorbance decreased with the increase of methanol concentration in sample solution from 2% to 40%, while the standard curve became most linear when the sample solution contained 10% methanol. Agricultural samples were extracted with methanol, and the extracts were diluted with water to 10% methanol adequate. No significant matrix interference was observed. Satisfying recovery was found for all of spiked samples and the results were well agreed with the analysis with liquid chromatography. These results clearly indicate that the kit-based dc-ELISA is suitable for the rapid, simple, quantitative and reliable determination of the fungicide. Copyright © 2012 Elsevier Ltd. All rights reserved.

Electrochemically Initiated Tagging of Thiols Using an Electrospray Ionization-Based Liquid Microjunction Surface Sampling Probe Two-Electrode Cell

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

Van Berkel, Gary J; Kertesz, Vilmos

2009-01-01

This paper reports on the conversion of a liquid microjunction surface sampling probe (LMJ-SSP) into a two electrode electrochemical cell using a conductive sample surface and the probe as the two electrodes with an appropriate battery powered circuit. With this LMJ-SSP, two-electrode cell arrangement, tagging of analyte thiol functionalities (in this case peptide cysteine residues) with hydroquinone tags was initiated electrochemically using a hydroquinone doped solution when the analyte either was initially in solution or was sampled from a surface. Efficient tagging (~90%), at flow rates of 5-10 L/min, could be achieved for up to at least two cysteines onmore » a peptide. The high tagging efficiency observed was explained with a simple kinetic model. In general, the incorporation of a two-electrode electrochemical cell, or other multiple electrode arrangement, into the LMJ-SSP is expected to add to the versatility of this approach for surface sampling and ionization coupled with mass spectrometric detection.« less

Multiscale microstructures and improved thermoelectric performance of Mg2(Si0.4Sn0.6)Sbx solid solutions

NASA Astrophysics Data System (ADS)

Zhang, Xin; Liu, Hongliang; Li, Songhao; Zhang, Feipeng; Lu, Qingmei; Li, Jingfeng

2014-03-01

A series of Sb-doped Mg2(Si0.4Sn0.6)Sbx (0 ≤ x ≤ 0.025) solid solutions were prepared by an induction melting, Melt Spinning (MS) and Spark Plasma Sintering (SPS) method, namely the non-equilibrium technique MS-SPS, using bulks of Magnesium, Silicon, Tin, and Antimony as raw materials. The non-equilibrium technique generates the unique multiscale microstructures of samples containing micronscale grains and nanoscale precipitates, the multiscale microstructures remarkably make the lattice thermal conductivities decreased, particularly for samples with the nanoscale precipitates having the size of 10-20 nm. Meanwhile, Sb-doping greatly increased the electrical performance of samples. Consequently, the Sb-doping combined with the multiscale microstructures strategy remarkably improves the overall thermoelectric (TE) performance of Sb doped samples, and a high dimensionless figure of merit (ZT) value of up to 1.25 at 723 K is obtained with Mg2(Si0.4Sn0.6)Sb0.02 sample in a relatively wide temperature range.

A Simple Method for Decreasing the Liquid Junction Potential in a Flow-through-Type Differential pH Sensor Probe Consisting of pH-FETs by Exerting Spatiotemporal Control of the Liquid Junction

PubMed Central

Yamada, Akira; Mohri, Satoshi; Nakamura, Michihiro; Naruse, Keiji

2015-01-01

The liquid junction potential (LJP), the phenomenon that occurs when two electrolyte solutions of different composition come into contact, prevents accurate measurements in potentiometry. The effect of the LJP is usually remarkable in measurements of diluted solutions with low buffering capacities or low ion concentrations. Our group has constructed a simple method to eliminate the LJP by exerting spatiotemporal control of a liquid junction (LJ) formed between two solutions, a sample solution and a baseline solution (BLS), in a flow-through-type differential pH sensor probe. The method was contrived based on microfluidics. The sensor probe is a differential measurement system composed of two ion-sensitive field-effect transistors (ISFETs) and one Ag/AgCl electrode. With our new method, the border region of the sample solution and BLS is vibrated in order to mix solutions and suppress the overshoot after the sample solution is suctioned into the sensor probe. Compared to the conventional method without vibration, our method shortened the settling time from over two min to 15 s and reduced the measurement error by 86% to within 0.060 pH. This new method will be useful for improving the response characteristics and decreasing the measurement error of many apparatuses that use LJs. PMID:25835300

Particulate contamination from siliconized rubber closures for freeze drying.

PubMed

Gebhardt, U; Grumbridge, N A; Knoch, A

1996-01-01

It can be shown that siliconized closures for freeze drying may cause the opalescence and turbidity observed in freeze-dried products after reconstitution. Closures of different rubber composition show different intensities of turbidity when treated identically with the same quantity and type of silicone oil. Clear solutions are obtained after reconstitution if ETFE-coated closures are used instead of siliconized closures. Samples stored at 4 degrees C for up to 6 months show no change in the intensity of turbidity, while the turbidity of samples manufactured with siliconized closures and stored at higher temperatures increase with time. Samples with ETFE-coated closures show clear solutions when stored at 25 degrees C and 37 degrees C for up to 6 months and at 45 degrees C for 3 months. After 6 months only a very weak opalescence could be observed in these samples.

Synthesis and thermoelectric properties of the (GeTe) 1-x(PbTe) x alloys

NASA Astrophysics Data System (ADS)

Li, S. P.; Li, J. Q.; Wang, Q. B.; Wang, L.; Liu, F. S.; Ao, W. Q.

2011-02-01

The Ge-rich (GeTe) 1-x(PbTe) x alloys with x = 0.10, 0.14, 0.18 and 0.22 were prepared by induction melting, ball milling and spark plasma sintering techniques. The thermoelectric properties of the samples were investigated. The experimental results show that all samples consist of the solid solutions of the two phases GeTe and PbTe. The samples are of p-type semiconductors. The existence of PbTe solution in GeTe increases its resistivity and Seebeck coefficient slightly, but reduces its thermal conductivity significantly. As result, the figures of merit for the materials can be enhanced. The maximum figure of merit ZT value of 0.81 was obtained in the sample (GeTe) 0.82(PbTe) 0.18 at 673K.

Leap-dynamics: efficient sampling of conformational space of proteins and peptides in solution.

PubMed

Kleinjung, J; Bayley, P; Fraternali, F

2000-03-31

A molecular simulation scheme, called Leap-dynamics, that provides efficient sampling of protein conformational space in solution is presented. The scheme is a combined approach using a fast sampling method, imposing conformational 'leaps' to force the system over energy barriers, and molecular dynamics (MD) for refinement. The presence of solvent is approximated by a potential of mean force depending on the solvent accessible surface area. The method has been successfully applied to N-acetyl-L-alanine-N-methylamide (alanine dipeptide), sampling experimentally observed conformations inaccessible to MD alone under the chosen conditions. The method predicts correctly the increased partial flexibility of the mutant Y35G compared to native bovine pancreatic trypsin inhibitor. In particular, the improvement over MD consists of the detection of conformational flexibility that corresponds closely to slow motions identified by nuclear magnetic resonance techniques.

Comparison of three methods of sampling for endometrial cytology in the mare. Preliminary study.

PubMed

Defontis, M; Vaillancourt, D; Grand, F X

2011-01-01

This prospective study aims to compare three different sampling techniques for the collection of endometrial cytological specimens in the mare: the guarded culture swab, the uterine cytobrush and the low volume uterine flush. The study population consisted of six healthy Standardbred mares in dioestrus. In each mare an acute endometritis was induced by performing a low- volume uterine flush 6days after ovulation using a sterile isotonic solution (lactated Ringer's solution or ViGro™ Complete Flush Solution). Two days after initiating inflammation, samples were collected from each mare using the three compared techniques: the double guarded cotton swab, the uterine cytobrush and the low volume uterine flush. The cytological evaluation of the samples was based on following criteria: the quality and cellularity of the samples and the number of neutrophils recovered. The uterine cytobrush yielded slides of significantly (p=0.02) better quality than the low volume uterine flush. There was no significant difference between the cytobrush and the double guarded swab technique for the quality. There was no difference between techniques in the number of endometrial cells (p=0.55) and neutrophils recovered (p=0.28). Endometrial cytology is a practical method for the diagnosis of acute endometrial inflammation in the mare. Since no difference in the number of neutrophils was found between the three techniques, the choice of the sampling method should be based on other factors such as practicability, costs and disadvantages of each technique.

On Two-Stage Multiple Comparison Procedures When There Are Unequal Sample Sizes in the First Stage.

ERIC Educational Resources Information Center

Wilcox, Rand R.

1984-01-01

Two stage multiple-comparison procedures give an exact solution to problems of power and Type I errors, but require equal sample sizes in the first stage. This paper suggests a method of evaluating the experimentwise Type I error probability when the first stage has unequal sample sizes. (Author/BW)

Randomization-Based Inference about Latent Variables from Complex Samples: The Case of Two-Stage Sampling

ERIC Educational Resources Information Center

Li, Tiandong

2012-01-01

In large-scale assessments, such as the National Assessment of Educational Progress (NAEP), plausible values based on Multiple Imputations (MI) have been used to estimate population characteristics for latent constructs under complex sample designs. Mislevy (1991) derived a closed-form analytic solution for a fixed-effect model in creating…

Sample Size Requirements for Structural Equation Models: An Evaluation of Power, Bias, and Solution Propriety

ERIC Educational Resources Information Center

Wolf, Erika J.; Harrington, Kelly M.; Clark, Shaunna L.; Miller, Mark W.

2013-01-01

Determining sample size requirements for structural equation modeling (SEM) is a challenge often faced by investigators, peer reviewers, and grant writers. Recent years have seen a large increase in SEMs in the behavioral science literature, but consideration of sample size requirements for applied SEMs often relies on outdated rules-of-thumb.…

Sampling in epidemiological research: issues, hazards and pitfalls.

PubMed

Tyrer, Stephen; Heyman, Bob

2016-04-01

Surveys of people's opinions are fraught with difficulties. It is easier to obtain information from those who respond to text messages or to emails than to attempt to obtain a representative sample. Samples of the population that are selected non-randomly in this way are termed convenience samples as they are easy to recruit. This introduces a sampling bias. Such non-probability samples have merit in many situations, but an epidemiological enquiry is of little value unless a random sample is obtained. If a sufficient number of those selected actually complete a survey, the results are likely to be representative of the population. This editorial describes probability and non-probability sampling methods and illustrates the difficulties and suggested solutions in performing accurate epidemiological research.

Sampling in epidemiological research: issues, hazards and pitfalls

PubMed Central

Tyrer, Stephen; Heyman, Bob

2016-01-01

Surveys of people's opinions are fraught with difficulties. It is easier to obtain information from those who respond to text messages or to emails than to attempt to obtain a representative sample. Samples of the population that are selected non-randomly in this way are termed convenience samples as they are easy to recruit. This introduces a sampling bias. Such non-probability samples have merit in many situations, but an epidemiological enquiry is of little value unless a random sample is obtained. If a sufficient number of those selected actually complete a survey, the results are likely to be representative of the population. This editorial describes probability and non-probability sampling methods and illustrates the difficulties and suggested solutions in performing accurate epidemiological research. PMID:27087985

Opto-electrochemical spectroscopy of metals in aqueous solutions

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

Habib, K., E-mail: khaledhabib@usa.net

In the present investigation, holographic interferometry was utilized for the first time to determine the rate change of the electrical resistance of aluminium samples during the initial stage of anodisation processes in aqueous solution. In fact, because the resistance values in this investigation were obtained by holographic interferometry, electromagnetic method rather than electronic method, the abrupt rate change of the resistance was called electrical resistance–emission spectroscopy. The anodisation process of the aluminium samples was carried out by electrochemical impedance spectroscopy (EIS) in different sulphuric acid concentrations (1.0%–2.5% H{sub 2}SO{sub 4}) at room temperature. In the meantime, the real time holographicmore » interferometry was used to determine the difference between the electrical resistance of two subsequent values, dR, as a function of the elapsed time of the EIS experiment for the aluminium samples in 1.0%, 1.5%, 2.0%, and 2.5% H{sub 2}SO{sub 4} solutions. The electrical resistance–emission spectra of the present investigation represent a detailed picture of not only the rate change of the electrical resistance throughout the anodisation processes but also the spectra represent the rate change of the growth of the oxide films on the aluminium samples in different solutions. As a result, a new spectrometer was developed based on the combination of the holographic interferometry and electrochemical impedance spectroscopy for studying in situ the electrochemical behavior of metals in aqueous solutions.« less

Determination of the herbicide benfuresate by its photo-induced chemiluminescence using flow multicommutation methodology.

PubMed

Albert-García, J R; Calatayud, J Martínez

2008-05-15

The present paper deals with an analytical strategy based on coupling photo-induced chemiluminescence in a multicommutation continuous-flow methodology for the determination of the herbicide benfuresate. The solenoid valve inserted as small segments of the analyte solution was sequentially alternated with segments of the NaOH solution for adjusting the medium for the photodegradation. Both flow rates (sample and medium) were adjusted to required time for photodegradation, 90 s; and then, the resulting solution was also sequentially inserted as segments alternated with segments of the oxidizing solution system, hexacyanoferrate (III) in alkaline medium. The calibration range from 1 microg L(-1) to 95 mg L(-1), resulted in a linear behaviour over the range 1 microg L(-1) to 4 mg L(-1) and fitting the linear equation: I=4555.7x+284.2, correlation coefficient 0.9999. The limit of detection was 0.1 microg L(-1) (n=5, criteria 3 sigma) and the sample throughput was 22 h(-1). The consumption of solutions was very small; per peak were 0.66 mL, 0.16 mL and 0. 32 mL sample, medium and oxidant, respectively. Inter- and intra-day reproducibility resulted in a R.S.D. of 3.9% and 3.4%, respectively. After testing the influence of a large series of potential interferents the method is applied to water samples obtained from different places, human urine and to one formulation.

Automatic sampling and analysis of organics and biomolecules by capillary action-supported contactless atmospheric pressure ionization mass spectrometry.

PubMed

Hsieh, Cheng-Huan; Meher, Anil Kumar; Chen, Yu-Chie

2013-01-01

Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (∼1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated.

Changes in apple liquid phase concentration throughout equilibrium in osmotic dehydration.

PubMed

Barat, J M; Barrera, C; Frías, J M; Fito, P

2007-03-01

Previous results on apple tissue equilibration during osmotic dehydration showed that, at very long processing times, the solute concentrations of the fruit liquid phase and the osmotic solution were the same. In the present study, changes in apple liquid phase composition throughout equilibrium in osmotic dehydration were analyzed and modeled. Results showed that, by the time osmosed samples reached the maximum weight and volume loss, solute concentration of the fruit liquid phase was higher than that of the osmotic solution. The reported overconcentration could be explained in terms of the apple structure shrinkage that occurred during the osmotic dehydration with highly concentrated osmotic solutions due to the elastic response of the food structure to the loss of water and intake of solutes. The fruit liquid phase overconcentration rate was observed to depend on the concentration of the osmotic solution, the processing temperature, the sample size, and shape of the cellular tissue.

Organic Carbon Release from Groundwater Sediments under Changing Geochemical Conditions

NASA Astrophysics Data System (ADS)

Tinnacher, R. M.; Bhattacharyya, A.; Fox, P. M.; Nico, P. S.

2016-12-01

Due to climate change, local weather patterns are expected to change, especially with respect to precipitation, the frequency of extreme storm water events, and `drought-like' conditions. This in turn, may affect groundwater recharge, the geochemical conditions in natural groundwater systems, and the chemical and microbiological processes involved in organic matter degradation. Besides the complexity of organic matter structures and local limitations in nutrients, the association of organic carbon with sediment minerals can strongly limit organic matter bioaccessability and degradability. In this study, we investigate how variations in groundwater chemistry, e.g. with respect to dissolved CO2 concentrations, may potentially affect the release of natural organic carbon from groundwater sediments, and render organic matter more bioaccessible. In lab-scale experiments under anaerobic conditions, aquifer sediments from the floodplain of the Colorado River (Rifle, USA) were brought into contact with fresh, organic-carbon free groundwater solutions, at natural or reduced CO2 concentration levels. During the repeated exchange of solutions at two temperature settings (room-temperature and 4 °C), supernatant solutions were characterized in terms of pH, dissolved metal and organic carbon (OC) concentrations, and potential changes in released OC characteristics. Sediment samples were evaluated for possible differences in Fe-speciation before and after the experiment based on EXAFS (bulk Fe K-edge). Preliminary results for 20 exchanges of groundwater solutions show a repeated release of low OC concentrations ( 0.5-2 mg OC/g sediment; 0.05-0.2% of sediment-associated OC) without any apparent depletion in the overall source term over 50 days. After 14 days, room-temperature samples released slightly higher OC concentrations than samples kept at 4 °C. An increase in solution pH, after switching to a `CO2-free' groundwater solution, did not trigger a higher OC release. Last, specific UV absorbance measurements for room-temperature samples suggest changes in released OC characteristics due to repeated solution exchanges. Additional sample characterization is ongoing, with the goal to elucidate potential changes in released OC characteristics over the course of the experiment.

Calculating the refractive index for pediatric parenteral nutrient solutions.

PubMed

Nelson, Scott; Barrows, Jason; Haftmann, Richard; Helm, Michael; MacKay, Mark

2013-02-15

The utility of refractometric analysis for calculating the refractive index (RI) of compounded parenteral nutrient solutions for pediatric patients was examined. An equation for calculating the RI of parenteral nutrient solutions was developed by chemical and linear regression analysis of 154 pediatric parenteral nutrient solutions. This equation was then validated by analyzing 1057 pediatric parenteral nutrition samples. The RI for the parenteral nutrient solutions could be calculated by summing the RI contribution for each ingredient and then adding the RI of water. The RI contribution for each ingredient was determined by multiplying the RI of the manufacturer's concentrate by the volume of the manufacturer's concentrate mixed into the parenteral nutrient solution divided by the total volume of the parenteral nutrient solution. The calculated RI was highly correlated with the measured RI (R(2) = 0.94, p < 0.0001). Using a range of two standard deviations (±0.0045), 99.8% of the samples fell into the comparative range. RIs of electrolytes, vitamins, and trace elements in the concentrations used did not affect the RI, similar to the findings of other studies. There was no statistical difference between the calculated RI and the measured RI in the final product of a pediatric parenteral nutrient solution. This method of quality control can be used by personnel compounding parenteral nutrient solutions to confirm the compounding accuracy of dextrose and amino acid concentrations in the final product, and a sample can be sent to the hospital laboratory for electrolyte verification.

Influence of pH on the physical and electromagnetic properties of Mg–Mn ferrite synthesized by a solution combustion method

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

Lwin, Nilar, E-mail: nilarlwin111@gmail.com; School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang; Othman, Radzali, E-mail: radzali@utem.edu.my

The synthesis of nano-crystalline Mg–Mn ferrites by a solution combustion method using citric acid and ammonia was investigated by varying the pH of the precursor solution, which played an important role in controlling the morphology of the synthesized powders. The phase formation, microstructure and electromagnetic properties were studied using X-ray diffraction, scanning electron microscopy, impedance analyzer and vibrating sample magnetometer. Single phase pure spinel Mg–Mn ferrite powders were obtained for all the samples at different pH (< 1, 3, 5, 7, 9). The results showed that an increase of pH improves the crystallinity of the Mg–Mn ferrite nanoparticles. The averagemore » grain size of sintered samples was found to decrease from 2 μm to 0.5 μm with increasing pH values from pH < 1 to pH 9, respectively. The dielectric constant of the samples with different pH is in the range of 7–12 from frequencies of 1 MHz to 1 GHz. The highest saturation magnetization (30.04 emu/g) was obtained for the sample with pH < 1. - Highlights: • Mg–Mn ferrites were synthesized by a solution combustion method with different pH. • Auto-combustion process resulted in the formation of single phase spinel ferrite. • An increase of pH improves the crystallinity of the Mg–Mn ferrite nanoparticles. • pH variation has influence on phase formation and morphology of the ferrite.« less

Atmospheric Delta14C Record from Wellington (1954-1993)

DOE Data Explorer

Manning, M R. [National Institute of Water and Atmospheric Research, Ltd., Lower Hutt, New Zealand; Melhuish, W. H. [National Institute of Water and Atmospheric Research, Ltd., Lower Hutt, New Zealand

1994-09-01

Trays containing ~2 L of 5 normal NaOH carbonate-free solution are typically exposed for intervals of 1-2 weeks, and the atmospheric CO₂ absorbed during that time is recovered by acid evolution. Considerable fractionation occurs during absorption into the NaOH solution, and the standard fractionation correction (Stuiver and Polach 1977) is used to determine a δ 14C value corrected to δ 13C = -25 per mil. Some samples reported here were taken using BaOH solution or with extended tray exposure times. These variations in procedure do not appear to affect the results (Manning et al. 1990). A few early measurements were made by bubbling air through columns of NaOH for several hours. These samples have higher δ 13C values. Greater details on the sampling methods are provided in Manning et al. (1990) and Rafter and Fergusson (1959).

Corrosion behavior of heat-treated intermetallic titanium-nickel in hydrochloric acid solutions

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

Starosvetsky, D.; Khaselev, O.; Yahalom, J.

1998-07-01

Samples of 45% Ti-55% Ni alloy (Ti-Ni) were heat-treated in air at 450 C, and their anodic behavior in 0.3 M, 1 M, 2 M, and 4 M hydrochloric acid (HCl) solutions was studied. In 0.3 M HCl, heat-treated Ti-Ni was passive, and very low anodic currents were observed. In 1 M and 2 M HCl, heat-treated Ti-Ni was dissolved actively, while heat-treated and surface-ground Ti-Ni became passive. The effect was explained by selective oxidation of Ti-Ni and formation of a layered structure on its surface with discontinuous titanium oxide and a nickel-enriched zone underneath. The latter was dissolved inmore » the HCl solutions, thus accelerating failure of the Ti-Ni samples. In 4 M HCl, heat-treated and heat-treated/ground samples were dissolved readily.« less

Psychometric properties of the social phobia and social interaction anxiety scales: evidence of construct equivalence in an African American sample.

PubMed

Carter, Michele M; Sbrocco, Tracy; Tang, Dickson; Rekrut, Frances M; Condit, Caitlin

2014-10-01

This study evaluated the psychometric properties of the Social Phobia Scale and Social Interaction Anxiety scale in a community sample of African Americans. We conducted a confirmatory factor analysis of the combined scales comparing the data to 2- and 3-factor solutions commonly reported in the literature. The results indicated that neither solution produce an adequate fit to the data in this study. We then proceeded to conduct an exploratory factor analysis within a confirmatory framework of both scales. While we were able to extract a 2-factor solution from the data, the item composition of the factors was somewhat different for African Americans than what is typically reported in non-Hispanic White samples. While we conclude that use of the two social anxiety scales is warranted, we make recommendations regarding the interpretation of both scales with African Americans. Copyright © 2014 Elsevier Ltd. All rights reserved.

Influence of De-icers on the Corrosion and Fatigue Behavior of 4140 Steel

NASA Astrophysics Data System (ADS)

Dean, William P.; Sanford, Brittain J.; Wright, Matthew R.; Evans, Jeffrey L.

2012-11-01

The purpose of this test was to evaluate the effects of calcium magnesium acetate (CMA) and sodium chloride (NaCl)—two common substances used to de-ice roadways—on the corrosion and fatigue behavior of annealed AISI 4140 steel. When CMA-corroded, NaCl-corroded, and as-machined samples were tested using R = 0.1, and f = 20 Hz, it was found that, within the scope of this study, samples corroded in both 3.5% CMA solution and 3.5% NaCl solution exhibited a lower fatigue strength than samples tested in the as-machined, uncorroded condition. For the short lives tested in this study, the difference in the effects of CMA and NaCl is minimal. However, at longer lives it is suspected, based on the trends, that the CMA solution would be less detrimental to the fatigue life.

System and method for laser assisted sample transfer to solution for chemical analysis

DOEpatents

Van Berkel, Gary J; Kertesz, Vilmos

2014-01-28

A system and method for laser desorption of an analyte from a specimen and capturing of the analyte in a suspended solvent to form a testing solution are described. The method can include providing a specimen supported by a desorption region of a specimen stage and desorbing an analyte from a target site of the specimen with a laser beam centered at a radiation wavelength (.lamda.). The desorption region is transparent to the radiation wavelength (.lamda.) and the sampling probe and a laser source emitting the laser beam are on opposite sides of a primary surface of the specimen stage. The system can also be arranged where the laser source and the sampling probe are on the same side of a primary surface of the specimen stage. The testing solution can then be analyzed using an analytical instrument or undergo further processing.

Cloud point extraction thermospray flame quartz furnace atomic absorption spectrometry for determination of ultratrace cadmium in water and urine

NASA Astrophysics Data System (ADS)

Wu, Peng; Zhang, Yunchang; Lv, Yi; Hou, Xiandeng

2006-12-01

A simple, low cost and highly sensitive method based on cloud point extraction (CPE) for separation/preconcentration and thermospray flame quartz furnace atomic absorption spectrometry was proposed for the determination of ultratrace cadmium in water and urine samples. The analytical procedure involved the formation of analyte-entrapped surfactant micelles by mixing the analyte solution with an ammonium pyrrolidinedithiocarbamate (APDC) solution and a Triton X-114 solution. When the temperature of the system was higher than the cloud point of Triton X-114, the complex of cadmium-PDC entered the surfactant-rich phase and thus separation of the analyte from the matrix was achieved. Under optimal chemical and instrumental conditions, the limit of detection was 0.04 μg/L for cadmium with a sample volume of 10 mL. The analytical results of cadmium in water and urine samples agreed well with those by ICP-MS.

Framing Child Sexual Abuse: A Longitudinal Content Analysis of Newspaper and Television Coverage, 2002-2012.

PubMed

Weatherred, Jane Long

2017-01-01

The way in which the news media frame child sexual abuse can influence public perception. This content analysis of the child sexual abuse coverage of eight national news organizations in the United States from 2002 to 2012 includes the two dominant events of the Catholic Church and Pennsylvania State University child sexual abuse scandals. Census and systematic stratified sampling techniques were applied to articles obtained from the Lexis/Nexis Academic database, resulting in a sample of 503 articles. Intercoder reliability was ensured by double coding a randomly selected sample. Study findings indicate a shift in the attribution of responsibility of child sexual abuse among news organizations over the past decade from an individual-level problem with individual-level solutions to a societal-level problem with institutional culpability. Nevertheless, individual-level solutions continue to be framed as the best possible solution.

A 3-D Coupled CFD-DSMC Solution Method With Application to the Mars Sample Return Orbiter

NASA Technical Reports Server (NTRS)

Glass, Christopher E.; Gnoffo, Peter A.

2000-01-01

A method to obtain coupled Computational Fluid Dynamics-Direct Simulation Monte Carlo (CFD-DSMC), 3-D flow field solutions for highly blunt bodies at low incidence is presented and applied to one concept of the Mars Sample Return Orbiter vehicle as a demonstration of the technique. CFD is used to solve the high-density blunt forebody flow defining an inflow boundary condition for a DSMC solution of the afterbody wake flow. By combining the two techniques in flow regions where most applicable, the entire mixed flow field is modeled in an appropriate manner.

Bacteria detection instrument and method

NASA Technical Reports Server (NTRS)

Renner, W.; Fealey, R. D. (Inventor)

1972-01-01

A method and apparatus for screening a sample fluid for bacterial presence are disclosed wherein the fluid sample is mixed with culture media of sufficient quantity to permit bacterial growth in order to obtain a test solution. The concentration of oxygen dissolved in the test solution is then monitored using the potential difference between a reference electrode and a noble metal electrode which are in contact with the test solution. The change in oxygen concentration which occurs during a period of time as indicated by the electrode potential difference is compared with a detection criterion which exceeds the change which would occur absent bacteria.

Theoretical and experimental analysis of analyte transport in a fiber-optic, protein C immuno-biosensor.

PubMed

Tang, Liang; Kwon, Hyun J; Kang, Kyung A

2004-12-30

Protein C (PC) is an important anticoagulant in human blood plasma, and early diagnosis of PC deficiency is critical for preventing dangerous thromboembolic complications. A fiber-optic PC immuno-biosensor has been under development in our research group for real-time PC-deficiency diagnosis. The sensor has demonstrated a good sensitivity and specificity for quantifying PC in buffered solutions. However, for plasma samples, with a limited sample reaction time, the sensor produced only 30% of the signal intensity of PC in buffer. The high plasma viscosity (1.9 cP) was speculated as the major reason for signal intensity reduction. In this investigation, the sensing performance of the fiber-optic PC biosensor is systematically characterized in terms of physical and chemical properties of the sample media. Theoretical and experimental analyses indicate that the reduced diffusion rate of PC molecules in viscous samples caused the sensing system to be more mass-transfer-limited. Convective flow of sample/reagent solutions during immunoreactions can increase the rate of the analyte mass transport from the bulk solution to the sensor surface, with reaction kinetics changing from mass-transfer-limited to reaction-limited as flow velocity increases. It was shown that PC sensor performance was significantly improved for plasma samples with convection. The effect of the flow velocity and incubation times for samples and reagents on the sensor performance was also systematically analyzed to optimize the assay protocol for PC sensing. Currently, a 6-cm-long immuno-biosensor is capable of quantifying PC in plasma (1 mL) in the heterozygous PC deficiency range (0.5 to 2.5 microg/mL) within 5 minutes, at an average signal-to-noise ratio of 50. 2004 Wiley Periodicals, Inc.

Sampling in Developmental Science: Situations, Shortcomings, Solutions, and Standards.

PubMed

Bornstein, Marc H; Jager, Justin; Putnick, Diane L

2013-12-01

Sampling is a key feature of every study in developmental science. Although sampling has far-reaching implications, too little attention is paid to sampling. Here, we describe, discuss, and evaluate four prominent sampling strategies in developmental science: population-based probability sampling, convenience sampling, quota sampling, and homogeneous sampling. We then judge these sampling strategies by five criteria: whether they yield representative and generalizable estimates of a study's target population, whether they yield representative and generalizable estimates of subsamples within a study's target population, the recruitment efforts and costs they entail, whether they yield sufficient power to detect subsample differences, and whether they introduce "noise" related to variation in subsamples and whether that "noise" can be accounted for statistically. We use sample composition of gender, ethnicity, and socioeconomic status to illustrate and assess the four sampling strategies. Finally, we tally the use of the four sampling strategies in five prominent developmental science journals and make recommendations about best practices for sample selection and reporting.

Sampling in Developmental Science: Situations, Shortcomings, Solutions, and Standards

PubMed Central

Bornstein, Marc H.; Jager, Justin; Putnick, Diane L.

2014-01-01

Sampling is a key feature of every study in developmental science. Although sampling has far-reaching implications, too little attention is paid to sampling. Here, we describe, discuss, and evaluate four prominent sampling strategies in developmental science: population-based probability sampling, convenience sampling, quota sampling, and homogeneous sampling. We then judge these sampling strategies by five criteria: whether they yield representative and generalizable estimates of a study’s target population, whether they yield representative and generalizable estimates of subsamples within a study’s target population, the recruitment efforts and costs they entail, whether they yield sufficient power to detect subsample differences, and whether they introduce “noise” related to variation in subsamples and whether that “noise” can be accounted for statistically. We use sample composition of gender, ethnicity, and socioeconomic status to illustrate and assess the four sampling strategies. Finally, we tally the use of the four sampling strategies in five prominent developmental science journals and make recommendations about best practices for sample selection and reporting. PMID:25580049

Correlation Between Iron and alpha and pi Glutathione-S-Transferase Levels in Humans

DTIC Science & Technology

2012-09-01

assays were performed as described in the Biotrin High Sensitivity Alpha GST EIA kit protocol. First, serum samples were diluted 1:10 with wash solution...immunosorbent assays were performed as described in the Biotrin Pi GST EIA kit protocol. First, plasma samples were diluted 1:5 with sample diluent...immunosorbent assays were performed as described in the AssayMax Human Transferrin ELISA kit protocol. First, serum samples were diluted 1:2000 with MIX

Sample Preparation of Nano-sized Inorganic Materials for Scanning Electron Microscopy or Transmission Electron Microscopy: Scientific Operating Procedure SOP-P-2

DTIC Science & Technology

2015-07-01

samples must be thoroughly degreased and dried to eliminate any outgassing from organic contamination and water. Samples can be cleaned ultrasonically ...in an ultrasonic bath for at least 10 minutes to ensure separation of particles (University of California, Riverside, n.d.). These solutions can...be further agitated in the ultrasonic bath to separate particles. It should be noted that excessive ultrasonic agitation can damage samples

Reduced detection by Ziehl-Neelsen method of acid-fast bacilli in sputum samples preserved in cetylpyridinium chloride solution.

PubMed

Selvakumar, N; Sudhamathi, S; Duraipandian, M; Frieden, T R; Narayanan, P R

2004-02-01

Twelve health facilities implementing the DOTS strategy, and the Tuberculosis Research Centre (TRC), Chennai, India. To determine the detection rates using Ziehl-Neelsen (ZN) and auramine-phenol to stain acid-fast bacilli (AFB) in sputum samples stored in cetylpyridinium chloride (CPC) solution. Two smears were prepared from each of 988 sputum samples collected in CPC and randomly allocated, one to ZN and the other to auramine-phenol staining. All samples were processed for culture of Mycobacterium tuberculosis. A significantly higher proportion of samples were negative using the ZN method compared to the auramine-phenol method (74.5% vs. 61.8%, McNamara's paired chi2 test; P < 0.001). Among 377 samples that were positive using auramine-phenol, 44% were negative using ZN. There were more culture-positive, smear-negative samples in ZN (52.7%) than in auramine-phenol (30%); the difference attained statistical significance (McNemar's paired chi2 test; P < 0.00004). Using ZN, of the 104 smears made immediately after collection, 52 were positive for AFB, of which only 35 (67.3%) were positive after storage in CPC; the reduction in the number of positive smears attained statistical significance (McNemar's paired chi2 test; P = 0.004). Detection of AFB in sputum samples preserved in CPC is significantly reduced using ZN staining.

Impact of Processing Method on Recovery of Bacteria from Wipes Used in Biological Surface Sampling

PubMed Central

Olson, Nathan D.; Filliben, James J.; Morrow, Jayne B.

2012-01-01

Environmental sampling for microbiological contaminants is a key component of hygiene monitoring and risk characterization practices utilized across diverse fields of application. However, confidence in surface sampling results, both in the field and in controlled laboratory studies, has been undermined by large variation in sampling performance results. Sources of variation include controlled parameters, such as sampling materials and processing methods, which often differ among studies, as well as random and systematic errors; however, the relative contributions of these factors remain unclear. The objective of this study was to determine the relative impacts of sample processing methods, including extraction solution and physical dissociation method (vortexing and sonication), on recovery of Gram-positive (Bacillus cereus) and Gram-negative (Burkholderia thailandensis and Escherichia coli) bacteria from directly inoculated wipes. This work showed that target organism had the largest impact on extraction efficiency and recovery precision, as measured by traditional colony counts. The physical dissociation method (PDM) had negligible impact, while the effect of the extraction solution was organism dependent. Overall, however, extraction of organisms from wipes using phosphate-buffered saline with 0.04% Tween 80 (PBST) resulted in the highest mean recovery across all three organisms. The results from this study contribute to a better understanding of the factors that influence sampling performance, which is critical to the development of efficient and reliable sampling methodologies relevant to public health and biodefense. PMID:22706055

DISTRIBUTION COEFICIENTS (KD) GENERATED FROM A CORE SAMPLE COLLECTED FROM THE SALTSTONE DISPOSAL FACILITY

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

Almond, P.; Kaplan, D.

Core samples originating from Vault 4, Cell E of the Saltstone Disposal Facility (SDF) were collected in September of 2008 (Hansen and Crawford 2009, Smith 2008) and sent to SRNL to measure chemical and physical properties of the material including visual uniformity, mineralogy, microstructure, density, porosity, distribution coefficients (K{sub d}), and chemical composition. Some data from these experiments have been reported (Cozzi and Duncan 2010). In this study, leaching experiments were conducted with a single core sample under conditions that are representative of saltstone performance. In separate experiments, reducing and oxidizing environments were targeted to obtain solubility and Kd valuesmore » from the measurable species identified in the solid and aqueous leachate. This study was designed to provide insight into how readily species immobilized in saltstone will leach from the saltstone under oxidizing conditions simulating the edge of a saltstone monolith and under reducing conditions, targeting conditions within the saltstone monolith. Core samples were taken from saltstone poured in December of 2007 giving a cure time of nine months in the cell and a total of thirty months before leaching experiments began in June 2010. The saltstone from Vault 4, Cell E is comprised of blast furnace slag, class F fly ash, portland cement, and Deliquification, Dissolution, and Adjustment (DDA) Batch 2 salt solution. The salt solution was previously analyzed from a sample of Tank 50 salt solution and characterized in the 4QCY07 Waste Acceptance Criteria (WAC) report (Zeigler and Bibler 2009). Subsequent to Tank 50 analysis, additional solution was added to the tank solution from the Effluent Treatment Project as well as from inleakage from Tank 50 pump bearings (Cozzi and Duncan 2010). Core samples were taken from three locations and at three depths at each location using a two-inch diameter concrete coring bit (1-1, 1-2, 1-3; 2-1, 2-2, 2-3; 3-1, 3-2, 3-3) (Hansen and Crawford 2009). Leaching experiments were conducted with a section of core sample 3-2. All cores from location 3 were drilled without using water. Core sample 3-2 was drilled from approximately six inches to a depth of approximately 13 inches. Approximately six inches of the core was removed but it broke into two pieces during removal from the bit. At the time of drilling, core material appeared olive green in color (Smith 2008). The fact that the samples were cored as olive green and were received after storage with a gray outer layer is indicative that some oxidation had occurred prior to leaching studies.« less

Online-LASIL: Laser Ablation of Solid Samples in Liquid with online-coupled ICP-OES detection for direct determination of the stoichiometry of complex metal oxide thin layers.

PubMed

Bonta, Maximilian; Frank, Johannes; Taibl, Stefanie; Fleig, Jürgen; Limbeck, Andreas

2018-02-13

Advanced materials such as complex metal oxides are used in a wide range of applications and have further promising perspectives in the form of thin films. The exact chemical composition essentially influences the electronic properties of these materials which makes correct assessment of their composition necessary. However, due to high chemical resistance and in the case of thin films low absolute analyte amounts, this procedure is in most cases not straightforward and extremely time-demanding. Commonly applied techniques either lack in ease of use (i.e., solution-based analysis with preceding sample dissolution), or adequately accurate quantification (i.e., solid sampling techniques). An analysis approach which combines the beneficial aspects of solution-based analysis as well as direct solid sampling is Laser Ablation of a Sample in Liquid (LASIL). In this work, it is shown that the analysis of major as well as minor sample constituents is possible using a novel online-LASIL setup, allowing sample analysis without manual sample handling after placing it in an ablation chamber. Strontium titanate (STO) thin layers with different compositions were analyzed in the course of this study. Precision of the newly developed online-LASIL method is comparable to conventional wet chemical approaches. With only about 15-20 min required for the analysis per sample, time demand is significantly reduced compared to often necessary fusion procedures lasting multiple hours. Copyright © 2017 Elsevier B.V. All rights reserved.

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

PubMed

Ciftci, Harun; Er, Cigdem

2013-03-01

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

Improvement of the tetrachloromercurate absorption technique for measuring low atmospheric SO2 mixing ratios

NASA Astrophysics Data System (ADS)

Jaeschke, W.; Beltz, N.; Haunold, W.; Krischke, U.

1997-07-01

During the Gas-Phase Sulfur Intercomparison Experiment (GASIE) in 1994 an analytical system for measuring sulfur dioxide mixing ratios at low parts per trillion (pptv) levels was employed. It is based on the absorption of SO2 on a tetrachloromercurate(II)-impregnated filter. The subsequent analysis uses a chemiluminescence reaction by treating the resulting disulfitomercurate(II) complex with an acidic cerium sulfate solution. An improved sampling device has been introduced that increases the maximum sampling volume from 200 L to 500 L. It is also possible to determine the blank value accurately for each sample. The absorption efficiency of the sampling system is 98.7±6.4% at a nominal flow rate of 10 L/min. The calculated (3σ) detection limit is 3±1 pptv SO2. The sample solution is stable for up to 30 days, which allows the samples to be safely stored or shipped before analysis. This permits the use of a sensitive, compact, and reliable sampling system in the field with subsequent analysis under optimal conditions in the laboratory. A continuous flow chemiluminescence (CFCL) analyzer for on-line measurements is also presented. The system is based on the same chemical principles as the described filter technique.

Glass transition of aqueous solutions involving annealing-induced ice recrystallization resolves liquid-liquid transition puzzle of water

PubMed Central

Zhao, Li-Shan; Cao, Ze-Xian; Wang, Qiang

2015-01-01

Liquid-liquid transition of water is an important concept in condensed-matter physics. Recently, it was claimed to have been confirmed in aqueous solutions based on annealing-induced upshift of glass-liquid transition temperature, . Here we report a universal water-content, , dependence of for aqueous solutions. Solutions with vitrify/devitrify at a constant temperature, , referring to freeze-concentrated phase with left behind ice crystallization. Those solutions with totally vitrify at under conventional cooling/heating process though, of the samples annealed at temperatures   to effectively evoke ice recrystallization is stabilized at . Experiments on aqueous glycerol and 1,2,4-butanetriol solutions in literature were repeated, and the same samples subject to other annealing treatments equally reproduce the result. The upshift of by annealing is attributable to freeze-concentrated phase of solutions instead of ‘liquid II phase of water’. Our work also provides a reliable method to determine hydration formula and to scrutinize solute-solvent interaction in solution. PMID:26503911

Effect of trimetaphosphate and fluoride association on hydroxyapatite dissolution and precipitation in vitro.

PubMed

Delbem, Alberto Carlos Botazzo; Souza, José Antonio Santos; Zaze, Ana Carolina Soares Fraga; Takeshita, Eliana Mitsue; Sassaki, Kikue Takebayashi; Moraes, João Carlos Silos

2014-01-01

The present study analyzed the action of sodium trimetaphosphate (TMP) and/or fluoride on hydroxyapatite. Hydroxyapatite powder was suspended in different solutions: deionized water, 500 µg F/mL, 1,100 µg F/mL, 1%TMP, 3%TMP, 500 µg F/mL plus 1%TMP and 500 µg F/mL plus 3%TMP. The pH value of the solutions was reduced to 4.0 and after 30 min, raised to 7.0 (three times). After pH-cycling, the samples were analyzed by X-ray diffraction and infrared spectroscopy. The concentrations of calcium fluoride, fluoride, calcium and phosphorus were also determined. Adding 1% or 3% TMP to the solution containing 500 µg F/mL produced a higher quantity of calcium fluoride compared to samples prepared in a 1,100 µg F/mL solution. Regarding the calcium concentration, samples prepared in solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP were statistically similar and showed higher values. Using solutions of 1,100 µg F/mL and 500 µg F/mL plus TMP resulted in a calcium/phosphorus ratio close to that of hydroxyapatite. It is concluded that the association of TMP and fluoride favored the precipitation of a more stable hydroxyapatite.

Calibration of equipment for analysis of drinking water fluoride: a comparison study.

PubMed

Quock, Ryan L; Chan, Jarvis T

2012-03-01

Current American Dental Association evidence-based recommendations for prescription of dietary fluoride supplements are based in part on the fluoride concentration of a pediatric patient's drinking water. With these recommendations in mind, this study compared the relative accuracy of fluoride concentration analysis when a common apparatus is calibrated with different combinations of standard values. Fluoride solutions in increments of 0.1 ppm, from a range of 0.1 to 1.0 ppm fluoride, as well as 2.0 and 4.0 ppm, were gravimetrically prepared and fluoride concentration measured in pentad, using a fluoride ion-specific electrode and millivolt meter. Fluoride concentrations of these solutions were recorded after calibration with the following 3 different combinations of standard fluoride solutions: 0.1 ppm and 0.5 ppm, 0.1 ppm and 1.0 ppm, 0.5 ppm and 1.0 ppm. Statistical analysis showed significant differences in the fluoride content of water samples obtained with different two-standard fluoride solutions. Among the two-standard fluoride solutions tested, using 0.5 ppm and 1.0 ppm as two-standard fluoride solutions provided the most accurate fluoride measurement of water samples containing fluoride in the range of 0.1 ppm to 4.0 ppm. This information should be valuable to dental clinics or laboratories in fluoride analysis of drinking water samples.

Poisson-Box Sampling algorithms for three-dimensional Markov binary mixtures

NASA Astrophysics Data System (ADS)

Larmier, Coline; Zoia, Andrea; Malvagi, Fausto; Dumonteil, Eric; Mazzolo, Alain

2018-02-01

Particle transport in Markov mixtures can be addressed by the so-called Chord Length Sampling (CLS) methods, a family of Monte Carlo algorithms taking into account the effects of stochastic media on particle propagation by generating on-the-fly the material interfaces crossed by the random walkers during their trajectories. Such methods enable a significant reduction of computational resources as opposed to reference solutions obtained by solving the Boltzmann equation for a large number of realizations of random media. CLS solutions, which neglect correlations induced by the spatial disorder, are faster albeit approximate, and might thus show discrepancies with respect to reference solutions. In this work we propose a new family of algorithms (called 'Poisson Box Sampling', PBS) aimed at improving the accuracy of the CLS approach for transport in d-dimensional binary Markov mixtures. In order to probe the features of PBS methods, we will focus on three-dimensional Markov media and revisit the benchmark problem originally proposed by Adams, Larsen and Pomraning [1] and extended by Brantley [2]: for these configurations we will compare reference solutions, standard CLS solutions and the new PBS solutions for scalar particle flux, transmission and reflection coefficients. PBS will be shown to perform better than CLS at the expense of a reasonable increase in computational time.

Modeling of U-series Radionuclide Transport Through Soil at Pena Blanca, Chihuahua, Mexico

NASA Astrophysics Data System (ADS)

Pekar, K. E.; Goodell, P. C.; Walton, J. C.; Anthony, E. Y.; Ren, M.

2007-05-01

The Nopal I uranium deposit is located at Pena Blanca in Chihuahua, Mexico. Mining of high-grade uranium ore occurred in the early 1980s, with the ore stockpiled nearby. The stockpile was mostly cleared in the 1990s; however, some of the high-grade boulders have remained there, creating localized sources of radioactivity for a period of 25-30 years. This provides a unique opportunity to study radionuclide transport, because the study area did not have any uranium contamination predating the stockpile in the 1980s. One high-grade boulder was selected for study based upon its shape, location, and high activity. The presumed drip-line off of the boulder was marked, samples from the boulder surface were taken, and then the boulder was moved several feet away. Soil samples were taken from directly beneath the boulder, around the drip-line, and down slope. Eight of these samples were collected in a vertical profile directly beneath the boulder. Visible flakes of boulder material were removed from the surficial soil samples, because they would have higher concentrations of U-series radionuclides and cause the activities in the soil samples to be excessively high. The vertical sampling profile used 2-inch thicknesses for each sample. The soil samples were packaged into thin plastic containers to minimize the attenuation and to standardize sample geometry, and then they were analyzed by gamma-ray spectroscopy with a Ge(Li) detector for Th-234, Pa-234, U-234, Th-230, Ra-226, Pb-214, Bi-214, and Pb-210. The raw counts were corrected for self-attenuation and normalized using BL-5, a uranium standard from Beaverlodge, Saskatchewan. BL-5 allowed the counts obtained on the Ge(Li) to be referenced to a known concentration or activity, which was then applied to the soil unknowns for a reliable calculation of their concentrations. Gamma ray spectra of five soil samples from the vertical profile exhibit decreasing activities with increasing depth for the selected radionuclides. Independent multi-element analyses of three samples by ICP-MS show decreasing uranium concentration with depth as well. The transport of the radionuclides is evaluated using STANMOD, a Windows-based software package for evaluating solute transport in porous media using analytical solutions of the advection-dispersion solute transport equation. The package allows various one-dimensional, advection-dispersion parameters to be determined by fitting mathematical solutions of theoretical transport models to observed data. The results are promising for future work on the release rate of radionuclides from the boulder, the dominant mode of transport (e.g., particulate or dissolution), and the movement of radionuclides through porous media. The measured subsurface transport rates provide modelers with a model validation dataset.

Colloid mobilization and heavy metal transport in the sampling of soil solution from Duckum soil in South Korea.

PubMed

Lee, Seyong; Ko, Il-Won; Yoon, In-Ho; Kim, Dong-Wook; Kim, Kyoung-Woong

2018-03-24

Colloid mobilization is a significant process governing colloid-associated transport of heavy metals in subsurface environments. It has been studied for the last three decades to understand this process. However, colloid mobilization and heavy metal transport in soil solutions have rarely been studied using soils in South Korea. We investigated the colloid mobilization in a variety of flow rates during sampling soil solutions in sand columns. The colloid concentrations were increased at low flow rates and in saturated regimes. Colloid concentrations increased 1000-fold higher at pH 9.2 than at pH 7.3 in the absence of 10 mM NaCl solution. In addition, those were fourfold higher in the absence than in the presence of the NaCl solution at pH 9.2. It was suggested that the mobility of colloids should be enhanced in porous media under the basic conditions and the low ionic strength. In real field soils, the concentrations of As, Cr, and Pb in soil solutions increased with the increase in colloid concentrations at initial momentarily changed soil water pressure, whereas the concentrations of Cd, Cu, Fe, Ni, Al, and Co lagged behind the colloid release. Therefore, physicochemical changes and heavy metal characteristics have important implications for colloid-facilitated transport during sampling soil solutions.

Factorial Structure of the New Ecological Paradigm Scale in Two French Samples

ERIC Educational Resources Information Center

Fleury-Bahi, Ghozlane; Marcouyeux, Aurore; Renard, Elise; Roussiau, Nicolas

2015-01-01

The principal objective of this research is to test the factorial structure of the New Ecological Paradigm scale on a population of men and women residing in France. The tested model is a second-order factorial model. This factorial structure is evaluated on two separate samples to test the stability of the solution (a first sample of 253…

Kinetic Aspects of Leaching Zinc from Waste Galvanizing Zinc by Using Hydrochloric Acid Solutions

NASA Astrophysics Data System (ADS)

Sminčáková, Emília; Trpčevská, Jarmila; Pirošková, Jana

2017-10-01

In this work, the results of acid leaching of flux skimmings coming from two plants are presented. Sample A contained two phases, Zn(OH)Cl and NH4Cl. In sample B, the presence of three phases, Zn5(OH)8Cl2·H2O, (NH4)2(ZnCl4) and ZnCl2(NH3)2, was proved. The aqueous solution of hydrochloric acid and distilled water was used as the leaching medium. The effects of the leaching time, temperature and concentration of the leaching medium on the zinc extraction were investigated. The apparent activation energy, E a = 4.61 kJ mol-1, and apparent reaction order n = 0.18 for sample A, and the values E a = 6.28 kJ mol-1 and n = 0.33 for sample B were experimentally determined. Zinc leaching in acid medium is a diffusion-controlled process.

Method of detecting luminescent target ions with modified magnetic microspheres

DOEpatents

Shkrob, Ilya A; Kaminski, Michael D

2014-05-13

This invention provides methods of using modified magnetic microspheres to extract target ions from a sample in order to detect their presence in a microfluidic environment. In one or more embodiments, the microspheres are modified with molecules on the surface that allow the target ions in the sample to form complexes with specific ligand molecules on the microsphere surface. In one or more embodiments, the microspheres are modified with molecules that sequester the target ions from the sample, but specific ligand molecules in solution subsequently re-extract the target ions from the microspheres into the solution, where the complexes form independent of the microsphere surface. Once the complexes form, they are exposed to an excitation wavelength light source suitable for exciting the target ion to emit a luminescent signal pattern. Detection of the luminescent signal pattern allows for determination of the presence of the target ions in the sample.

Provenance establishment of coffee using solution ICP-MS and ICP-AES.

PubMed

Valentin, Jenna L; Watling, R John

2013-11-01

Statistical interpretation of the concentrations of 59 elements, determined using solution based inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma emission spectroscopy (ICP-AES), was used to establish the provenance of coffee samples from 15 countries across five continents. Data confirmed that the harvest year, degree of ripeness and whether the coffees were green or roasted had little effect on the elemental composition of the coffees. The application of linear discriminant analysis and principal component analysis of the elemental concentrations permitted up to 96.9% correct classification of the coffee samples according to their continent of origin. When samples from each continent were considered separately, up to 100% correct classification of coffee samples into their countries, and plantations of origin was achieved. This research demonstrates the potential of using elemental composition, in combination with statistical classification methods, for accurate provenance establishment of coffee. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effect of variation in indium concentration on the photosensitivity of chlorine doped In{sub 2}S{sub 3} thin films

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

Cherian, Angel Susan; Kartha, C. Sudha; Vijayakumar, K. P.

2014-01-28

Consequence of variation in Indium concentration in chlorine doped In2S{sub 3} thin films deposited by spray pyrolysis technique was studied. Chlorine was incorporated in the spray solution, using HCl and Indium concentration was varied by adjusting In/S ratio Interestingly, the photo response of all chlorine doped samples augmented compared to pristine samples; but the highest photosensitivity value of ∼2300 was obtained only when 36ml 0.5M HCl was added to the solution of In{sub 2}S{sub 3} having In/S=2/8. It was also observed that samples with high photosensitivity possess higher band gap and variation in sub band gap absoption levels were observedmore » with increase in Indium concentration. The present study proved that concentration of Indium plays an important role in controlling the crystallinity and photosensitivity of chlorine doped samples.« less

Density determination of nail polishes and paint chips using magnetic levitation

NASA Astrophysics Data System (ADS)

Huang, Peggy P.

Trace evidence is often small, easily overlooked, and difficult to analyze. This study describes a nondestructive method to separate and accurately determine the density of trace evidence samples, specifically nail polish and paint chip using magnetic levitation (MagLev). By determining the levitation height of each sample in the MagLev device, the density of the sample is back extrapolated using a standard density bead linear regression line. The results show that MagLev distinguishes among eight clear nail polishes, including samples from the same manufacturer; separates select colored nail polishes from the same manufacturer; can determine the density range of household paint chips; and shows limited levitation for unknown paint chips. MagLev provides a simple, affordable, and nondestructive means of determining density. The addition of co-solutes to the paramagnetic solution to expand the density range may result in greater discriminatory power and separation and lead to further applications of this technique.

Application of hollow cylindrical wheat stem for electromembrane extraction of thorium in water samples

NASA Astrophysics Data System (ADS)

Khajeh, Mostafa; Pedersen-Bjergaard, Stig; Barkhordar, Afsaneh; Bohlooli, Mousa

2015-02-01

In this study, wheat stem was used for electromembrane extraction (EME) for the first time. The EME technique involved the use of a wheat stem whose channel was filled with 3 M HCl, immersed in 10 mL of an aqueous sample solution. Thorium migrated from aqueous samples, through a thin layer of 1-octanol and 5%v/v Di-(2-ethylhexyl) phosphate (DEHP) immobilized in the pores of a porous stem, and into an acceptor phase solution present inside the lumen of the stem. The pH of donor and acceptor phases, extraction time, voltage, and stirring speed were optimized. At the optimum conditions, an enrichment factor of 50 and a limit of detection of 0.29 ng mL-1 was obtained for thorium. The developed procedure was then applied to the extraction and determination of thorium in water samples and in reference material.

FC and ZFC magnetic properties of ferro-spinels (MFe2O4) prepared by solution-combustion method

NASA Astrophysics Data System (ADS)

Aravind, G.; Kumar, R. Vijaya; Nathaniyal, V.; Rambabu, T.; Ravinder, D.

2017-07-01

Magnetic ferro-spinels MFe2O4 (M= Co and Ni) prepared by citrate-gel solution combustion method using metal nitrates with low sintering temperature (500°C). From the XRD and TEM studies confirm that a nano crystalline nature of the prepared samples. Field Cooled (FC) and Zero Field Cooled (ZFC) magnetic studies of the prepared ferro-spinels are measured by using vibrating sample magnetometer (VSM). The resultant magnetization of the prepared samples as a function of an applied magnetic field 10 T was measured at two different temperatures 5 K and 310 K. Field Cooled (FC) and Zero Field Cooled (ZFC) magnetization measurements under an applied field of 100 Oe and 1000 Oe in the temperature range of 5-375 K were carried out, which shows the blocking temperature of these two samples at around 350 K.

Accounting for between-study variation in incremental net benefit in value of information methodology.

PubMed

Willan, Andrew R; Eckermann, Simon

2012-10-01

Previous applications of value of information methods for determining optimal sample size in randomized clinical trials have assumed no between-study variation in mean incremental net benefit. By adopting a hierarchical model, we provide a solution for determining optimal sample size with this assumption relaxed. The solution is illustrated with two examples from the literature. Expected net gain increases with increasing between-study variation, reflecting the increased uncertainty in incremental net benefit and reduced extent to which data are borrowed from previous evidence. Hence, a trial can become optimal where current evidence is sufficient assuming no between-study variation. However, despite the expected net gain increasing, the optimal sample size in the illustrated examples is relatively insensitive to the amount of between-study variation. Further percentage losses in expected net gain were small even when choosing sample sizes that reflected widely different between-study variation. Copyright © 2011 John Wiley & Sons, Ltd.

Effect of dipping in pomegranate (Punica granatum) fruit juice phenolic solution on the shelf life of chicken meat under refrigerated storage (4°C).

PubMed

Vaithiyanathan, S; Naveena, B M; Muthukumar, M; Girish, P S; Kondaiah, N

2011-07-01

An experiment was conducted to evaluate the effect of dipping in pomegranate fruit juice phenolics (PFJP) solution on the shelf life of chicken meat held under refrigerated storage at 4°C. Breast muscle obtained from spent hens was dipped (1:2w/v; muscle: liquid) in sterile water or in sterile water with 0.02% (v/v) PFJP, packed, stored at 4°C for 28 days and samples were analyzed on 2 days of intervals. Thiobarbituric acid reactive substance values were lower in samples treated with PFJP. Total sulfhydryl and protein bound sulfhydryl content values were higher in samples treated with PFJP. Microbial quality evaluation showed that aerobic and psychrotrophic counts were higher in samples treated without PFJP. Sensory evaluation revealed that acceptability level of samples treated without PFJP decreased on 12th day of storage. It is concluded that spent hen breast meat samples dipped in 0.02% PFJP reduced protein oxidation and inhibited microbial growth and sensorily acceptable up to 12 days of refrigerated storage at 4°C. Copyright © 2011 Elsevier Ltd. All rights reserved.

Efficient sampling over rough energy landscapes with high barriers: A combination of metadynamics with integrated tempering sampling.

PubMed

Yang, Y Isaac; Zhang, Jun; Che, Xing; Yang, Lijiang; Gao, Yi Qin

2016-03-07

In order to efficiently overcome high free energy barriers embedded in a complex energy landscape and calculate overall thermodynamics properties using molecular dynamics simulations, we developed and implemented a sampling strategy by combining the metadynamics with (selective) integrated tempering sampling (ITS/SITS) method. The dominant local minima on the potential energy surface (PES) are partially exalted by accumulating history-dependent potentials as in metadynamics, and the sampling over the entire PES is further enhanced by ITS/SITS. With this hybrid method, the simulated system can be rapidly driven across the dominant barrier along selected collective coordinates. Then, ITS/SITS ensures a fast convergence of the sampling over the entire PES and an efficient calculation of the overall thermodynamic properties of the simulation system. To test the accuracy and efficiency of this method, we first benchmarked this method in the calculation of ϕ - ψ distribution of alanine dipeptide in explicit solvent. We further applied it to examine the design of template molecules for aromatic meta-C-H activation in solutions and investigate solution conformations of the nonapeptide Bradykinin involving slow cis-trans isomerizations of three proline residues.

Results Of Routine Strip Effluent Hold Tank, Decontaminated Salt Solution Hold Tank, And Caustic Wash Tank Samples From Modular Caustic-Side Solvent Extraction Unit During Macrobatch 4 Operations

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

Peters, T. B.; Fink, S. D.

Strip Effluent Hold Tank (SEHT), Decontaminated Salt Solution Hold Tank (DSSHT), and Caustic Wash Tank (CWT) samples from several of the ?microbatches? of Integrated Salt Disposition Project (ISDP) Salt Batch (?Macrobatch?) 4 have been analyzed for {sup 238}Pu, {sup 90}Sr, {sup 137}Cs, and by inductively-coupled plasma emission spectroscopy (ICPES). Furthermore, samples from the CWT have been analyzed by a variety of methods to investigate a decline in the decontamination factor (DF) of the cesium observed at MCU. The results indicate good decontamination performance within process design expectations. While the data set is sparse, the results of this set and themore » previous set of results for Macrobatch 3 samples indicate generally consistent operations. There is no indication of a disruption in plutonium and strontium removal. The average cesium DF and concentration factor (CF) for samples obtained from Macrobatch 4 are slightly lower than for Macrobatch 3, but still well within operating parameters. The DSSHT samples show continued presence of titanium, likely from leaching of the monosodium titanate in Actinide Removal Process (ARP).« less

Efficient sampling over rough energy landscapes with high barriers: A combination of metadynamics with integrated tempering sampling

NASA Astrophysics Data System (ADS)

Yang, Y. Isaac; Zhang, Jun; Che, Xing; Yang, Lijiang; Gao, Yi Qin

2016-03-01

In order to efficiently overcome high free energy barriers embedded in a complex energy landscape and calculate overall thermodynamics properties using molecular dynamics simulations, we developed and implemented a sampling strategy by combining the metadynamics with (selective) integrated tempering sampling (ITS/SITS) method. The dominant local minima on the potential energy surface (PES) are partially exalted by accumulating history-dependent potentials as in metadynamics, and the sampling over the entire PES is further enhanced by ITS/SITS. With this hybrid method, the simulated system can be rapidly driven across the dominant barrier along selected collective coordinates. Then, ITS/SITS ensures a fast convergence of the sampling over the entire PES and an efficient calculation of the overall thermodynamic properties of the simulation system. To test the accuracy and efficiency of this method, we first benchmarked this method in the calculation of ϕ - ψ distribution of alanine dipeptide in explicit solvent. We further applied it to examine the design of template molecules for aromatic meta-C—H activation in solutions and investigate solution conformations of the nonapeptide Bradykinin involving slow cis-trans isomerizations of three proline residues.

Developing a Vacuum Electrospray Source To Implement Efficient Atmospheric Sampling for Miniature Ion Trap Mass Spectrometer.

PubMed

Yu, Quan; Zhang, Qian; Lu, Xinqiong; Qian, Xiang; Ni, Kai; Wang, Xiaohao

2017-12-05

The performance of a miniature mass spectrometer in atmospheric analysis is closely related to the design of its sampling system. In this study, a simplified vacuum electrospray ionization (VESI) source was developed based on a combination of several techniques, including the discontinuous atmospheric pressure interface, direct capillary sampling, and pneumatic-assisted electrospray. Pulsed air was used as a vital factor to facilitate the operation of electrospray ionization in the vacuum chamber. This VESI device can be used as an efficient atmospheric sampling interface when coupled with a miniature rectilinear ion trap (RIT) mass spectrometer. The developed VESI-RIT instrument enables regular ESI analysis of liquid, and its qualitative and quantitative capabilities have been characterized by using various solution samples. A limit of detection of 8 ppb could be attained for arginine in a methanol solution. In addition, extractive electrospray ionization of organic compounds can be implemented by using the same VESI device, as long as the gas analytes are injected with the pulsed auxiliary air. This methodology can extend the use of the proposed VESI technique to rapid and online analysis of gaseous and volatile samples.

Efficient sampling over rough energy landscapes with high barriers: A combination of metadynamics with integrated tempering sampling

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

Yang, Y. Isaac; Zhang, Jun; Che, Xing

2016-03-07

In order to efficiently overcome high free energy barriers embedded in a complex energy landscape and calculate overall thermodynamics properties using molecular dynamics simulations, we developed and implemented a sampling strategy by combining the metadynamics with (selective) integrated tempering sampling (ITS/SITS) method. The dominant local minima on the potential energy surface (PES) are partially exalted by accumulating history-dependent potentials as in metadynamics, and the sampling over the entire PES is further enhanced by ITS/SITS. With this hybrid method, the simulated system can be rapidly driven across the dominant barrier along selected collective coordinates. Then, ITS/SITS ensures a fast convergence ofmore » the sampling over the entire PES and an efficient calculation of the overall thermodynamic properties of the simulation system. To test the accuracy and efficiency of this method, we first benchmarked this method in the calculation of ϕ − ψ distribution of alanine dipeptide in explicit solvent. We further applied it to examine the design of template molecules for aromatic meta-C—H activation in solutions and investigate solution conformations of the nonapeptide Bradykinin involving slow cis-trans isomerizations of three proline residues.« less

Circular birefringence/dichroism measurement of optical scattering samples using amplitude-modulation polarimetry

NASA Astrophysics Data System (ADS)

Liu, Wei-Chun; Lo, Yu-Lung; Phan, Quoc-Hung

2018-03-01

A method is proposed for extracting the circular birefringence (CB), circular dichroism (CD) and depolarization (Dep) properties of optical scattering samples using an amplitude-modulation polarimetry technique. The validity of the proposed method is demonstrated by extracting the CB property of pure glucose aqueous samples, the CB/Dep properties of glucose solutions containing 0.02% lipofundin particles, and the CD/Dep properties of chlorophyllin solutions containing suspended polystyrene microspheres. The results show that the proposed technique has the ability to detect pure glucose with a resolution of 66 mg/dL over a concentration range of 0-500 mg/dL. Moreover, the glucose concentration of the CB/Dep samples can be detected over the same range with a resolution of 168 mg/dL. Finally, the chlorophyllin concentration of the CD/Dep sample can be detected over the range of 0-200 μg/dL with a resolution of 6.5 × 10-5. In general, the results show that the proposed technique provides a reliable and accurate means of measuring the CB/CD properties of optical samples with scattering effects, and thus has significant potential for biological sensing applications.

Direct Compositional Characterization of (U,Th)O2 Powders, Microspheres, and Pellets Using TXRF.

PubMed

Dhara, Sangita; Prabhat, Parimal; Misra, N L

2015-10-20

A total reflection X-ray fluorescence (TXRF) analysis method for direct compositional characterization of sintered and green (U,Th)O2 samples in different forms (e.g., pellets, powders, and microspheres) without sample dissolution has been developed for the first time. The methodology involves transfer of only a few nanograms of the sample on the TXRF sample support by gently rubbing the samples on supports or taking their tiny uniform slurry in collodion on the sample support, drying them to make thin film, and measuring the TXRF spectra of the specimens thus prepared. This approach minimizes the matrix effects. Uranium determinations from the TXRF spectra of such specimens were made with respect to thorium, considering it as an internal standard. Samples having uranium atom percent (at%) from 0 to 100 in (U,Th)O2 were analyzed for uranium in comparison to thorium. The results showed an average precision of 2.6% (RSD, 2σ, n = 8). The TXRF-determined results deviated from expected values within 5%. The TXRF results were compared with those of biamperometry with good agreement. The lattice parameters of the solid solutions were calculated using their XRD patterns. A good correlation between lattice parameters and TXRF-determined U at% and between TXRF-determined U at% and expected U at%, calculated on the basis of preparation of (U,Th)O2 solid solutions, was obtained. The developed method is capable of analyzing (U,Th)O2 samples directly with almost negligible sample preparation and is well suited for radioactive samples. The present study suggests that this method can be extended for the determination of U,Th and Pu in other nuclear fuel materials (e.g., nitrides, carbides, etc.) in the form of pellets, powders, and microspheres after suitable modifications in sample handling procedure.

Effects of Temperature on Solute Transport Parameters in Differently-Textured Soils at Saturated Condition

NASA Astrophysics Data System (ADS)

Hamamoto, S.; Arihara, M.; Kawamoto, K.; Nishimura, T.; Komatsu, T.; Moldrup, P.

2014-12-01

Subsurface warming driven by global warming, urban heat islands, and increasing use of shallow geothermal heating and cooling systems such as the ground source heat pump, potentially causes changes in subsurface mass transport. Therefore, understanding temperature dependency of the solute transport characteristics is essential to accurately assess environmental risks due to increased subsurface temperature. In this study, one-dimensional solute transport experiments were conducted in soil columns under temperature control to investigate effects of temperature on solute transport parameters, such as solute dispersion and diffusion coefficients, hydraulic conductivity, and retardation factor. Toyoura sand, Kaolin clay, and intact loamy soils were used in the experiments. Intact loamy soils were taken during a deep well boring at the Arakawa Lowland in Saitama Prefecture, Japan. In the transport experiments, the core sample with 5-cm diameter and 4-cm height was first isotropically consolidated, whereafter 0.01M KCl solution was injected to the sample from the bottom. The concentrations of K+ and Cl- in the effluents were analyzed by an ion chromatograph to obtain solute breakthrough curves. The solute transport parameters were calculated from the breakthrough curves. The experiments were conducted under different temperature conditions (15, 25, and 40 oC). The retardation factor for the intact loamy soils decreased with increasing temperature, while water permeability increased due to reduced viscosity of water at higher temperature. Opposite, the effect of temperature on solute dispersivity for the intact loamy soils was insignificant. The effects of soil texture on the temperature dependency of the solute transport characteristics will be further investigated from comparison of results from differently-textured samples.

Effect of different solutions on color stability of acrylic resin-based dentures.

PubMed

Goiato, Marcelo Coelho; Nóbrega, Adhara Smith; dos Santos, Daniela Micheline; Andreotti, Agda Marobo; Moreno, Amália

2014-01-01

The aim of this study was to evaluate the effect of thermocycling and immersion in mouthwash or beverage solutions on the color stability of four different acrylic resin-based dentures (Onda Cryl, OC; QC20, QC; Classico, CL; and Lucitone, LU). The factors evaluated were type of acrylic resin, immersion time, and solution (mouthwash or beverage). A total of 224 denture samples were fabricated. For each type of resin, eight samples were immersed in mouthwashes (Plax-Colgate, PC; Listerine, LI; and Oral-B, OB), beverages (coffee, CP; cola, C; and wine, W), and artificial saliva (AS; control). The color change (DE) was evaluated before (baseline) and after thermocycling (T1), and after immersion in solution for 1 h (T2), 3 h (T3), 24 h (T4), 48 h (T5), and 96 h (T6). The CIE Lab system was used to determine the color changes. The thermocycling test was performed for 5000 cycles. Data were submitted to three-way repeated-measures analysis of variance and Tukey's test (p<0.05). When the samples were immersed in each mouthwash, all assessed factors, associated or not, significantly influenced the color change values, except there was no association between the mouthwash and acrylic resin. Similarly, when the samples were immersed in each beverage, all studied factors influenced the color change values. In general, regardless of the solution, LU exhibited the greatest DE values in the period from T1 to T5; and QC presented the greatest DE values at T6. Thus, thermocycling and immersion in the various solutions influenced the color stability of acrylic resins and QC showed the greatest color alteration.

Improving small-angle X-ray scattering data for structural analyses of the RNA world

PubMed Central

Rambo, Robert P.; Tainer, John A.

2010-01-01

Defining the shape, conformation, or assembly state of an RNA in solution often requires multiple investigative tools ranging from nucleotide analog interference mapping to X-ray crystallography. A key addition to this toolbox is small-angle X-ray scattering (SAXS). SAXS provides direct structural information regarding the size, shape, and flexibility of the particle in solution and has proven powerful for analyses of RNA structures with minimal requirements for sample concentration and volumes. In principle, SAXS can provide reliable data on small and large RNA molecules. In practice, SAXS investigations of RNA samples can show inconsistencies that suggest limitations in the SAXS experimental analyses or problems with the samples. Here, we show through investigations on the SAM-I riboswitch, the Group I intron P4-P6 domain, 30S ribosomal subunit from Sulfolobus solfataricus (30S), brome mosaic virus tRNA-like structure (BMV TLS), Thermotoga maritima asd lysine riboswitch, the recombinant tRNAval, and yeast tRNAphe that many problems with SAXS experiments on RNA samples derive from heterogeneity of the folded RNA. Furthermore, we propose and test a general approach to reducing these sample limitations for accurate SAXS analyses of RNA. Together our method and results show that SAXS with synchrotron radiation has great potential to provide accurate RNA shapes, conformations, and assembly states in solution that inform RNA biological functions in fundamental ways. PMID:20106957

Delta14 CO2 Atmospheric Record from Schauinsland, Germany

DOE Data Explorer

Levin, Ingeborg [Institut fur Umweltphysik, University of Heidelberg, Heidelberg, Germany; Kromer, Bernd [Institut fur Umweltphysik, University of Heidelberg, Heidelberg, Germany

1997-01-01

All air samples at Schauinsland have been collected from a ventilated intake stack approximately 7m above the ground. Bi-weekly integrated CO2 samples from about 15-20 m3 of air have been continuously collected by dynamic quantitative absorption in carbonate-free sodium hydroxide (NaOH) solution. Air has been pumped through a rotating glass tube filled with a packed bed of Raschig rings (hard glass) to enlarge the surface of the absorbing NaOH solution (200 ml of 4 normal NaOH). The CO2 absorption is quantitative and samples represent mean values of 10 days to 2 weeks. In the laboratory, the samples are extracted from the NaOH solution in a vacuum system by adding hydrochloric or sulfuric acid. 13C analyses of the CO2 are by mass spectrometry and 14C analyses are by high precision proportional counting, after purification of the CO2 sample over charcoal (Schoch et al. 1980, Kromer and Münnich 1992). δ13C values are given relative to the V-PDB standard (Hut 1987) with the overall precision of a single analysis reported to be +/- 0.15 per mil (Levin and Kromer 1997). δ14C data are given relative to the NIST oxalic acid activity corrected for decay (Stuiver and Polach 1977) with the precision of a single δ14C measurement reported to be +/- 3-5 per mil (Levin and Kromer 1997).

Self-sampling for human papillomavirus DNA detection: a preliminary study of compliance and feasibility in BOLIVIA.

PubMed

Surriabre, Pedro; Allende, Gustavo; Prado, Marcela; Cáceres, Leyddy; Bellot, Diego; Torrico, Andrea; Ustariz, Karina; Rojas, Shirley; Barriga, Jaime; Calle, Pamela; Villarroel, Ligia; Yañez, Rosse Mary; Baay, Marc; Rodriguez, Patricia; Fontaine, Véronique

2017-12-22

Cervical cancer incidence and mortality rates in Bolivia are among the highest in Latin America. This investigation aims to evaluate the possibility of using simple devices, e.g. a cotton swab and a glass slide, for self-sampling in order to detect human papillomavirus (HPV) DNA by PCR in cervico-vaginal cells. In the first phase of our study we evaluated the use of a glass slide as a transport medium for cervical cells. A physician took paired-cervical samples from 235 women. One sample was transported in Easyfix® solution and the other sample was smeared over a glass slide. Both were further analyzed and compared for human DNA recovery and HPV detection. A kappa value was determined to evaluate the agreement between the HPV DNA detection rates. In the second phase of the study, 222 women from the urban, peri-urban and rural regions of Cochabamba were requested to perform self-sampling using the following devices: a cotton swab combined with a glass slide, and a vaginal tampon. Women gave their opinion about the self-sampling technique. Finally, the agreement for high risk-HPV detection between self- and physician-collected samples was performed in 201 samples in order to evaluate the self-sampling technique. Firstly, the comparison between Easyfix® solution and the glass slide to transport clinical samples gave a good agreement for HPV DNA detection (κ = 0.71, 95% CI 0.60-0.81). Secondly, self-sampling, especially with cotton swab combined with glass slide, would generally be preferred over clinician sampling for a screening program based on HPV detection. Finally, we showed a good agreement between self- and physician collected samples for high risk-HPV detection (κ = 0.71, 95% CI 0.55-0.88). Simple devices such as a cotton swab and a glass slide can be used to perform self-sampling and HPV DNA detection. Furthermore, most Bolivian women preferred self-sampling over clinician-sampling for cervical cancer screening.

Acupuncture injection for field amplified sample stacking and glass microchip-based capillary gel electrophoresis.

PubMed

Ha, Ji Won; Hahn, Jong Hoon

2017-02-01

Acupuncture sample injection is a simple method to deliver well-defined nanoliter-scale sample plugs in PDMS microfluidic channels. This acupuncture injection method in microchip CE has several advantages, including minimization of sample consumption, the capability of serial injections of different sample solutions into the same microchannel, and the capability of injecting sample plugs into any desired position of a microchannel. Herein, we demonstrate that the simple and cost-effective acupuncture sample injection method can be used for PDMS microchip-based field amplified sample stacking in the most simplified straight channel by applying a single potential. We achieved the increase in electropherogram signals for the case of sample stacking. Furthermore, we present that microchip CGE of ΦX174 DNA-HaeⅢ digest can be performed with the acupuncture injection method on a glass microchip while minimizing sample loss and voltage control hardware. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Final Scientific Report - Wireless and Sensing Solutions Advancing Industrial Efficiency

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

Budampati, Rama; McBrady, Adam; Nusseibeh, Fouad

2009-09-28

The project team's goal for the Wireless and Sensing Solution Advancing Industrial Efficiency award (DE-FC36-04GO14002) was to develop, demonstrate, and test a number of leading edge technologies that could enable the emergence of wireless sensor and sampling systems for the industrial market space. This effort combined initiatives in advanced sensor development, configurable sampling and deployment platforms, and robust wireless communications to address critical obstacles in enabling enhanced industrial efficiency.

Studies on a novel approach for the separation of L-phenylalanine amino acid from fermentation broth using a newly developed charged ultrafiltration membrane. I. Single solute system

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

Agarwal, A.K.; Huang, R.Y.M.

A newly developed thin-film composite (TFC) ultrafiltration membrane made of sulfonated poly(phenylene oxide) (SPPO) was used to establish the feasibility of separating L-phenylalanine from the fermentation broth containing a number of dissolved inorganic and organic solutes as an alternative approach to the currently used complex and uneconomical conventional ion-exchange schemes. It was found that the rejection of inorganic salts in a single component system was highly dependent on the feed solution concentration and varied inversely with it. The pH of the feed solution was found to have a strong effect on the rejection of L-phenylalanine, changing it from - 10more » to 90%. This rejection behavior was identical for the two TFC-SPPO membrane samples which had molecular weight cutoff ratings of 10,000 and 20,000, respectively, although the permeate flux of the latter sample was almost twice that of the former sample. It was found that glucose molecules were not rejected by the membrane. 11 refs., 18 figs., 2 tab.« less

Solutions to inverse plume in a crosswind problem using a predictor - corrector method

NASA Astrophysics Data System (ADS)

Vanderveer, Joseph; Jaluria, Yogesh

2013-11-01

Investigation for minimalist solutions to the inverse convection problem of a plume in a crosswind has developed a predictor - corrector method. The inverse problem is to predict the strength and location of the plume with respect to a select few downstream sampling points. This is accomplished with the help of two numerical simulations of the domain at differing source strengths, allowing the generation of two inverse interpolation functions. These functions in turn are utilized by the predictor step to acquire the plume strength. Finally, the same interpolation functions with the corrections from the plume strength are used to solve for the plume location. Through optimization of the relative location of the sampling points, the minimum number of samples for accurate predictions is reduced to two for the plume strength and three for the plume location. After the optimization, the predictor-corrector method demonstrates global uniqueness of the inverse solution for all test cases. The solution error is less than 1% for both plume strength and plume location. The basic approach could be extended to other inverse convection transport problems, particularly those encountered in environmental flows.

Accumulation of deuterium oxide in body fluids after ingestion of D/sub 2/O-labeled beverages

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

Davis, J.M.; Lamb, D.R.; Burgess, W.A.

A simple low-cost procedure was developed to compare the temporal profiles of deuterium oxide (D/sub 2/O) accumulation in body fluids after ingestion of D/sub 2/O-labeled solutions. D/sub 2/O concentration was measured in plasma and saliva samples taken at various intervals after ingestion of 20 ml of D/sub 2/O mixed with five solutions differing in carbohydrate and electrolyte concentrations. An infrared spectrometer was used to measure D/sub 2/O in purified samples obtained after a 48-h incubation period during which the water (D/sub 2/O and H/sub 2/O) in the sample was equilibrated with an equal volume of distilled water in a sealedmore » diffusion dish. The procedure yields 100% recoveries of 60-500 ppm D/sub 2/O with an average precision of 5%. When compared with values for distilled water, D/sub 2/O accumulation in serial samples of plasma and saliva was slower for ingested solutions containing 40 and 15% glucose and faster for hypotonic saline and a 6% carbohydrate-electrolyte solution. These differences appear to reflect known differences in gastric emptying and intestinal absorption of these beverages. Therefore, this technique may provide a useful index of the rate of water uptake from ingested beverages into the body fluids.« less

Sodium Chloride Diffusion in Low-Acid Foods during Thermal Processing and Storage.

PubMed

Bornhorst, Ellen R; Tang, Juming; Sablani, Shyam S

2016-05-01

This study aimed at modeling sodium chloride (NaCl) diffusion in foods during thermal processing using analytical and numerical solutions and at investigating the changes in NaCl concentrations during storage after processing. Potato, radish, and salmon samples in 1% or 3% NaCl solutions were heated at 90, 105, or 121 °C for 5 to 240 min to simulate pasteurization and sterilization. Selected samples were stored at 4 or 22 °C for up to 28 d. Radish had the largest equilibrium NaCl concentrations and equilibrium distribution coefficients, but smallest effective diffusion coefficients, indicating that a greater amount of NaCl diffused into the radish at a slower rate. Effective diffusion coefficients determined using the analytical solution ranged from 0.2 × 10(-8) to 2.6 × 10(-8) m²/s. Numerical and analytical solutions showed good agreement with experimental data, with average coefficients of determination for samples in 1% NaCl at 121 °C of 0.98 and 0.95, respectively. During storage, food samples equilibrated to a similar NaCl concentration regardless of the thermal processing severity. The results suggest that sensory evaluation of multiphase (solid and liquid) products should occur at least 14 d after processing to allow enough time for the salt to equilibrate within the product. © 2016 Institute of Food Technologists®

Simultaneous separation and detection of actinides in acidic solutions using an extractive scintillating resin.

PubMed

Roane, J E; DeVol, T A

2002-11-01

An extractive scintillating resin was evaluated for the simultaneous separation and detection of actinides in acidic solutions. The transuranic extractive scintillating (TRU-ES) resin is composed of an inert macroporous polystyrene core impregnated with organic fluors (diphenyloxazole and 1,4-bis-(4-methyl-5-phenyl-2-oxazolyl)benzene) and an extractant (octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide in tributyl phosphate). The TRU-ES resin was packed into FEP Teflon tubing to produce a flow cell (0.2-mL free column volume), which is placed into a scintillation detection system to obtain pulse height spectra and time series data during loading and elution of actinides onto/from the resin. The alpha-particle absolute detection efficiencies ranged from 77% to 96.5%, depending on the alpha energy and quench. In addition to the on-line analyses, off-line analyses of the effluent can be conducted using conventional detection methods. The TRU-ES resin was applied to the quantification of a mixed radionuclide solution and two actual waste samples. The on-line characterization of the mixed radionuclide solution was within 10% of the reported activities whereas the agreement with the waste samples was not as good due to sorption onto the sample container walls and the oxidation state of plutonium. Agreement between the on-line and off-line analyses was within 35% of one another for both waste samples.

Environmentally-Friendly Dense and Porous Geopolymers Using Fly Ash and Rice Husk Ash as Raw Materials

PubMed Central

Ziegler, Daniele; Formia, Alessandra; Tulliani, Jean-Marc; Palmero, Paola

2016-01-01

This paper assesses the feasibility of two industrial wastes, fly ash (FA) and rice husk ash (RHA), as raw materials for the production of geopolymeric pastes. Three typologies of samples were thus produced: (i) halloysite activated with potassium hydroxide and nanosilica, used as the reference sample (HL-S); (ii) halloysite activated with rice husk ash dissolved into KOH solution (HL-R); (iii) FA activated with the alkaline solution realized with the rice husk ash (FA-R). Dense and porous samples were produced and characterized in terms of mechanical properties and environmental impact. The flexural and compressive strength of HL-R reached about 9 and 43 MPa, respectively. On the contrary, the compressive strength of FA-R is significantly lower than the HL-R one, in spite of a comparable flexural strength being reached. However, when porous samples are concerned, FA-R shows comparable or even higher strength than HL-R. Thus, the current results show that RHA is a valuable alternative to silica nanopowder to prepare the activator solution, to be used either with calcined clay and fly ash feedstock materials. Finally, a preliminary evaluation of the global warming potential (GWP) was performed for the three investigated formulations. With the mix containing FA and RHA-based silica solution, a reduction of about 90% of GWP was achieved with respect to the values obtained for the reference formulation. PMID:28773587

Flow injection trace gas analysis method for on-site determination of organoarsenicals

DOEpatents

Aldstadt, III, Joseph H.

1997-01-01

A method for real-time determination of the concentration of Lewisite in the ambient atmosphere, the method includes separating and collecting a Lewisite sample from the atmosphere in a collection chamber, converting the collected Lewisite to an arsenite ion solution sample, pumping the arsenite ion containing sample to an electrochemical detector connected to the collection chamber, and electrochemically detecting the converted arsenite ions in the sample, whereby the concentration of arsenite ions detected is proportional to the concentration of Lewisite in the atmosphere.

Hybrid selection for sequencing pathogen genomes from clinical samples

PubMed Central

2011-01-01

We have adapted a solution hybrid selection protocol to enrich pathogen DNA in clinical samples dominated by human genetic material. Using mock mixtures of human and Plasmodium falciparum malaria parasite DNA as well as clinical samples from infected patients, we demonstrate an average of approximately 40-fold enrichment of parasite DNA after hybrid selection. This approach will enable efficient genome sequencing of pathogens from clinical samples, as well as sequencing of endosymbiotic organisms such as Wolbachia that live inside diverse metazoan phyla. PMID:21835008

Temporal and spatial variability of chemical and isotopic composition of soil solutions from cambisols - field study and experiments.

PubMed

Schön, Walter; Mittermayr, Florian; Leis, Albrecht; Mischak, Irene; Dietzel, Martin

2016-12-01

The chemical and isotopic composition of soil solutions is highly relevant for environmental and forensic tasks. We investigated interstitial solutions from soil horizons of three cambisols in Styria (Austria). The soils consisted mainly of quartz, feldspar and clay minerals with a vertical variability. Two soil solution fractions from meso-, macro- and micropores (m) and micropores only (μ) were extracted at two subsequent hydraulic pressure steps corresponding to matrix potentials of up to pF 5.43 and from 5.43 to 5.73, respectively. While solute concentrations indicated diverse distribution in soil solution fractions m and μ, heavy stable hydrogen and oxygen isotopes of H 2 O (-92.5‰<δ 2 H<-34.4‰; -11.9‰<δ 18 O<-4.0‰, VSMOW) are clearly enriched in the μ versus m fractions. Principal component analysis on the hydrochemical data set indicates that the intensity of the overall silicate weathering is higher in autumn versus spring, whereas the anthropogenic impact on weathering behaves inversely. The anthropogenic impact is related to seasonal variability of nitrification of N-fertilizers. In consequence of evaluated signals for overall silicate weathering about three-fourths of the soil solutions sampled in autumn indicated elevated total dissolved solid concentration vs. those in spring accompanied with washing out solutes from the soil cover following precipitation events in autumn before sampling. Isotopic shift of soil solutions from the local meteoric water line in spring obviously followed an evaporation trend because of less precipitation and high evaporation before sampling. Experimentally simulated evaporation of soil samples confirmed the observed isotopic evaporation trend. Wetting experiments indicated the infiltration of water within minutes into the micropores of the soils. Exchange of water molecules between micro-, meso- and macropores is an almost instantaneous process and soil solutions in micropores are not as isolated from the soil water system as it was formerly suggested, e.g. for plant uptake. Highly dynamic and complex mechanisms in the gas-water-solid system of soils have to be considered for the application of elemental and isotope proxies related to environmental, forensic and agricultural tasks. Copyright © 2016 Elsevier B.V. All rights reserved.

Physicochemical, bioactive, and sensory properties of persimmon-based ice cream: technique for order preference by similarity to ideal solution to determine optimum concentration.

PubMed

Karaman, Safa; Toker, Ömer Said; Yüksel, Ferhat; Çam, Mustafa; Kayacier, Ahmed; Dogan, Mahmut

2014-01-01

In the present study, persimmon puree was incorporated into the ice cream mix at different concentrations (8, 16, 24, 32, and 40%) and some physicochemical (dry matter, ash, protein, pH, sugar, fat, mineral, color, and viscosity), textural (hardness, stickiness, and work of penetration), bioactive (antiradical activity and total phenolic content), and sensory properties of samples were investigated. The technique for order preference by similarity to ideal solution approach was used for the determination of optimum persimmon puree concentration based on the sensory and bioactive characteristics of final products. Increase in persimmon puree resulted in a decrease in the dry matter, ash, fat, protein contents, and viscosity of ice cream mix. Glucose, fructose, sucrose, and lactose were determined to be major sugars in the ice cream samples including persimmon and increase in persimmon puree concentration increased the fructose and glucose content. Better melting properties and textural characteristics were observed for the samples with the addition of persimmon. Magnesium, K, and Ca were determined to be major minerals in the samples and only K concentration increased with the increase in persimmon content. Bioactive properties of ice cream samples improved and, in general, acetone-water extracts showed higher bioactivity compared with ones obtained using methanol-water extracts. The technique for order preference by similarity to ideal solution approach showed that the most preferred sample was the ice cream containing 24% persimmon puree. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Comparison of Fecal Collection Methods for Microbiota Studies in Bangladesh

PubMed Central

Chen, Jun; Kibriya, Muhammad G.; Chen, Yu; Islam, Tariqul; Eunes, Mahbubul; Ahmed, Alauddin; Naher, Jabun; Rahman, Anisur; Amir, Amnon; Shi, Jianxin; Abnet, Christian C.; Nelson, Heidi; Knight, Rob; Chia, Nicholas; Ahsan, Habibul; Sinha, Rashmi

2017-01-01

ABSTRACT To our knowledge, fecal microbiota collection methods have not been evaluated in low- and middle-income countries. Therefore, we evaluated five different fecal sample collection methods for technical reproducibility, stability, and accuracy within the Health Effects of Arsenic Longitudinal Study (HEALS) in Bangladesh. Fifty participants from the HEALS provided fecal samples in the clinic which were aliquoted into no solution, 95% ethanol, RNAlater, postdevelopment fecal occult blood test (FOBT) cards, and fecal immunochemical test (FIT) tubes. Half of the aliquots were frozen immediately at −80°C (day 0) and the remaining samples were left at ambient temperature for 96 h and then frozen (day 4). Intraclass correlation coefficients (ICC) were calculated for the relative abundances of the top three phyla, for two alpha diversity measures, and for four beta diversity measures. The duplicate samples had relatively high ICCs for technical reproducibility at day 0 and day 4 (range, 0.79 to 0.99). The FOBT card and samples preserved in RNAlater and 95% ethanol had the highest ICCs for stability over 4 days. The FIT tube had lower stability measures overall. In comparison to the “gold standard” method using immediately frozen fecal samples with no solution, the ICCs for many of the microbial metrics were low, but the rank order appeared to be preserved as seen by the Spearman correlation. The FOBT cards, 95% ethanol, and RNAlater were effective fecal preservatives. These fecal collection methods are optimal for future cohort studies, particularly in low- and middle-income countries. IMPORTANCE The collection of fecal samples in prospective cohort studies is essential to provide the opportunity to study the effect of the human microbiota on numerous health conditions. However, these collection methods have not been adequately tested in low- and middle-income countries. We present estimates of technical reproducibility, stability at ambient temperature for 4 days, and accuracy comparing a “gold standard” for fecal samples in no solution, 95% ethanol, RNAlater, postdevelopment fecal occult blood test cards, and fecal immunochemical test tubes in a study conducted in Bangladesh. Fecal occult blood test cards and fecal samples stored in 95% ethanol or RNAlater adequately preserve fecal samples in this setting. Therefore, new studies in low- and middle-income countries should include collection of fecal samples using fecal occult blood test cards, 95% ethanol, or RNAlater for prospective cohort studies. PMID:28258145

Free-energy analyses of a proton transfer reaction by simulated-tempering umbrella sampling and first-principles molecular dynamics simulations.

PubMed

Mori, Yoshiharu; Okamoto, Yuko

2013-02-01

A simulated tempering method, which is referred to as simulated-tempering umbrella sampling, for calculating the free energy of chemical reactions is proposed. First principles molecular dynamics simulations with this simulated tempering were performed to study the intramolecular proton transfer reaction of malonaldehyde in an aqueous solution. Conformational sampling in reaction coordinate space can be easily enhanced with this method, and the free energy along a reaction coordinate can be calculated accurately. Moreover, the simulated-tempering umbrella sampling provides trajectory data more efficiently than the conventional umbrella sampling method.

Measurement of complex permittivities of biological materials and human skin in vivo in the frequency band

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

Ghodgaonkar, D.K.

1987-01-01

A new method, namely, modified infinite sample method, has been developed which is particularly suitable for millimeter-wave dielectric measurements of biological materials. In this method, an impedance transformer is used which reduces the reflectivity of the biological sample. Because of the effect of introducing impendance transformer, the measured reflection coefficients are more sensitive to the complex permittivities of biological samples. For accurate measurement of reflection coefficients, two automated measurment systems were developed which cover the frequencies range of 26.5-60 GHz. An uncertainty analysis was performed to get an estimate of the errors in the measured complex permittivities. The dielectric propertiesmore » were measured for 10% saline solution, whole human blood, 200 mg/ml bovine serum albumin (BSA) solution and suspension of Saccharomyces cerevisiae cells. The Maxwell-Fricke equation, which is derived from dielectric mixture theory, was used for determination bound water in BSA solution. The results of all biological samples were interpreted by fitting Debye relaxation and Cole-Cole model. It is observed that the dielectric data for the biological materials can be explained on the basis of Debye relaxation of water molecule.« less

Micro-structural characterization of precipitation-synthesized fluorapatite nano-material by transmission electron microscopy using different sample preparation techniques.

PubMed

Chinthaka Silva, G W; Ma, Longzhou; Hemmers, Oliver; Lindle, Dennis

2008-01-01

Fluorapatite is a naturally occurring mineral of the apatite group and it is well known for its high physical and chemical stability. There is a recent interest in this ceramic to be used as a radioactive waste form material due to its intriguing chemical and physical properties. In this study, the nano-sized fluorapatite particles were synthesized using a precipitation method and the material was characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Two well-known methods, called solution-drop and the microtome cutting, were used to prepare the sample for TEM analysis. It was found that the microtome cutting technique is advantageous for examining the particle shape and cross-sectional morphology as well as for obtaining ultra-thin samples. However, this method introduces artifacts and strong background contrast for high-resolution transmission electron microscopy (HRTEM) observation. On the other hand, phase image simulations showed that the solution-drop method is reliable and stable for HRTEM analysis. Therefore, in order to comprehensively analyze the microstructure and morphology of the nano-material, it is necessary to combine both solution-drop and microtome cutting techniques for TEM sample preparation.

Moist heat intraluminal disinfection of CAPD connectors.

PubMed

Fessia, S L; Grabowy, R S; Bousquet, G G

1990-01-01

A moist heat technique for disinfecting the inner lumen of commercially available connectology used in the exchange process for Continuous Ambulatory Peritoneal Dialysis (CAPD) was evaluated. Moist heat was generated by a device (PDM-1) that directed microwave energy to heat a sample solution containing a concentration of 10(6) microorganisms inside a pair of mated plastic CAPD connectors. Microorganisms tested included those most prevalent and most problematic in causing peritonitis. Testing, performed according to F.D.A. approved standards, involved heating a sample solution and then placing the sample solution into vials which were then sealed and incubated. Absolute determination of growth versus no growth was measured by macroscopic observation. Positive control samples were performed in the same manner but were not exposed to heat. Negative controls were performed in the same manner in the absence of test organisms. At temperatures of approximately 100 degrees C a D-value of 6.6 seconds was determined using the organism found the most thermoresistant. A cycle time of 54 seconds appeared sufficient to achieve a 10(6) population reduction of all microorganisms tested. The moist heat technique offers a safe, effective method for disinfection of the inner lumen of CAPD connectors.

Recovering fluorophore concentration profiles from confocal images near lateral refractive index step changes.

PubMed

Jonášová, Eleonóra Parelius; Bjørkøy, Astrid; Stokke, Bjørn Torger

2016-12-01

Optical aberrations due to refractive index mismatches occur in various types of microscopy due to refractive differences between the sample and the immersion fluid or within the sample. We study the effects of lateral refractive index differences by fluorescence confocal laser scanning microscopy due to glass or polydimethylsiloxane cuboids and glass cylinders immersed in aqueous fluorescent solution, thereby mimicking realistic imaging situations in the proximity of these materials. The reduction in fluorescence intensity near the embedded objects was found to depend on the geometry and the refractive index difference between the object and the surrounding solution. The observed fluorescence intensity gradients do not reflect the fluorophore concentration in the solution. It is suggested to apply a Gaussian fit or smoothing to the observed fluorescence intensity gradient and use this as a basis to recover the fluorophore concentration in the proximity of the refractive index step change. The method requires that the reference and sample objects have the same geometry and refractive index. The best results were obtained when the sample objects were also used for reference since small differences such as uneven surfaces will result in a different extent of aberration.

Electrochemical Behavior Assessment of Micro- and Nano-Grained Commercial Pure Titanium in H2SO4 Solutions

NASA Astrophysics Data System (ADS)

Fattah-alhosseini, Arash; Ansari, Ali Reza; Mazaheri, Yousef; Karimi, Mohsen

2017-02-01

In this study, the electrochemical behavior of commercial pure titanium with both coarse-grained (annealed sample with the average grain size of about 45 µm) and nano-grained microstructure was compared by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and Mott-Schottky analysis. Nano-grained Ti, which typically has a grain size of about 90 nm, is successfully made by six-cycle accumulative roll-bonding process at room temperature. Potentiodynamic polarization plots and impedance measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure Ti in H2SO4 solutions. Mott-Schottky analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and grain refinement did not change the semiconductor type of passive films. Also, Mott-Schottky analysis showed that the donor densities decreased as the grain size of the samples reduced. Finally, all electrochemical tests showed that the electrochemical behavior of the nano-grained sample was improved compared to that of annealed pure Ti, mainly due to the formation of thicker and less defective oxide film.

Measurement of the Water Relaxation Time of ɛ-Polylysine Aqueous Solutions

NASA Astrophysics Data System (ADS)

Shirakashi, Ryo; Amano, Yuki; Yamada, Jun

2017-05-01

ɛ-Polylysine is an effective food preservative. In this paper, the β-relaxation time of ɛ-polylysine aqueous solutions, which represents the rotational speed of a single water molecule, was measured by broadband dielectric spectroscopy at various temperatures and concentrations. The broadband dielectric spectrum of each sample containing water ranging from 35 wt% to 75 wt% at temperatures ranging from 0°C to 25°C was measured using a co-axial semirigid cable probe. The measured dielectric spectra of the samples were composed of several Debye relaxation peaks, including a shortest single molecular rotational relaxation time of water, the β-relaxation time, longer than that of pure water. This result represents that ɛ-polylysine suppresses the molecular kinetics of water. It is also found that the β-relaxation time of an ɛ-polylysine solution that contained more than 35 wt% water showed a typical Arrhenius plot in the temperature range from 0°C to 25°C. The activation energy of each sample depends on the water content ratio of the sample. As indicated by its long β-relaxation time, ɛ-polylysine is expected to possess high abilities of suppressing freezing and ice coarsening.

Determination of 10 sulfonamide residues in meat samples by liquid chromatography with ultraviolet detection.

PubMed

Di Sabatino, Marcello; Di Pietra, Anna Maria; Benfenati, Luigi; Di Simone, Bruno

2007-01-01

A liquid chromatography (LC) method is described for the simultaneous determination of 10 commonly used sulfonamide drug residues in meat. The 10 sulfonamide drugs of interest were sulfadiazine, sulfathiazole, sulfamerazine, sulfadimidine, sulfamethizole, sulfamonomethoxine, sulfachloropyridazine, sulfadoxine, sulfadimethoxine, and sulfaquinoxaline. The residues were extracted with acetone-chloroform (1 + 1). Sulfonamides were quantitatively retained in the extracting solution and afterwards eluted from a cation-exchanger solid-phase extraction cartridge with a solution of methanol-aqueous ammonia. The solution was dried, reconstituted with 5 mL methanol and filtered before analysis by LC-ultraviolet using a C18 column with a mobile phase gradient of potassium dihydrogen phosphate buffer, pH 2.5, and methanol-acetonitrile (30 + 70, v/v). The method was applied to cattle, swine, chicken, and sheep muscle tissues. The validation was performed with a fortified cattle meat sample at level of 100 ppb, which is the administrative maximum residue limit for sulfonamides in the European Union. The limit of quantitation for all sulfonamides was between 3 and 14 ppb. Recovery was evaluated for different meat matrixes. The mean recovery values were between 66.3% for pork meat samples and 71.5% for cattle meat samples.

DMA Modulus as a Screening Parameter for Compatibility of Polymeric Containment Materials with Various Solutions for use in Space Shuttle Microgravity Protein Crystal Growth (PCG) Experiments

NASA Technical Reports Server (NTRS)

Wingard, Charles Doug; Munafo, Paul M. (Technical Monitor)

2002-01-01

Protein crystals are grown in microgravity experiments inside the Space Shuttle during orbit. Such crystals are basically grown in a five-component system containing a salt, buffer, polymer, organic and water. During these experiments, a number of different polymeric containment materials must be compatible with up to hundreds of different PCG solutions in various concentrations for durations up to 180 days. When such compatibility experiments are performed at NASA/MSFC (Marshall Space Flight Center) simultaneously on containment material samples immersed in various solutions in vials, the samples are rather small out of necessity. DMA4 modulus was often used as the primary screening parameter for such small samples as a pass/fail criterion for incompatibility issues. In particular, the TA Instruments DMA 2980 film tension clamp was used to test rubber O-rings as small in I.D. as 0.091 in. by cutting through the cross-section at one place, then clamping the stretched linear cord stock at each end. The film tension clamp was also used to successfully test short length samples of medical/surgical grade tubing with an O.D. of 0.125 in.

In vitro degradation of ZM21 magnesium alloy in simulated body fluids.

PubMed

Witecka, Agnieszka; Bogucka, Aleksandra; Yamamoto, Akiko; Máthis, Kristián; Krajňák, Tomáš; Jaroszewicz, Jakub; Święszkowski, Wojciech

2016-08-01

In vitro degradation behavior of squeeze cast (CAST) and equal channel angular pressed (ECAP) ZM21 magnesium alloy (2.0wt% Zn-0.98wt% Mn) was studied using immersion tests up to 4w in three different biological environments. Hanks' Balanced Salt Solution (Hanks), Earle's Balanced Salt Solution (Earle) and Eagle minimum essential medium supplemented with 10% (v/v) fetal bovine serum (E-MEM+10% FBS) were used to investigate the effect of carbonate buffer system, organic compounds and material processing on the degradation behavior of the ZM21 alloy samples. Corrosion rate of the samples was evaluated by their Mg(2+) ion release, weight loss and volume loss. In the first 24h, the corrosion rate sequence of the CAST samples was as following: Hanks>E-MEM+10% FBS>Earle. However, in longer immersion periods, the corrosion rate sequence was Earle>E-MEM+10% FBS≥Hanks. Strong buffering effect provided by carbonate buffer system helped to maintain the pH avoiding drastic increase of the corrosion rate of ZM21 in the initial stage of immersion. Organic compounds also contributed to maintain the pH of the fluid. Moreover, they adsorbed on the sample surface and formed an additional barrier on the insoluble salt layer, which was effective to retard the corrosion of CAST samples. In case of ECAP, however, this effect was overcome by the occurrence of strong localized corrosion due to the lower pH of the medium. Corrosion of ECAP samples was much greater than that of CAST, especially in Hanks, due to higher sensitivity of ECAP to localized corrosion and the presence of Cl(-). The present work demonstrates the importance of using an appropriate solution for a reliable estimation of the degradation rate of Mg-base degradable implants in biological environments, and concludes that the most appropriate solution for this purpose is E-MEM+10% FBS, which has the closest chemical composition to human blood plasma. Copyright © 2016 Elsevier B.V. All rights reserved.

Use of Chelex-100 for selectively removing Y-90 from its parent Sr-90

DOEpatents

Huntley, Mark W.

1996-01-01

A method for selectively removing yttrium-90 from its parent strontium-90 contained in an environmental sample includes loading the sample onto a column containing a chelating ion-exchange resin capable of retaining yttrium-90; washing the column with a solution capable of removing strontium, calcium, and other contaminants from the yttrium-90 fraction retained on the column; removing excess acetate salts from the column; eluting yttrium-90 solution from the column and adjusting the pH of this solution to about 2.7; filtering the yttrium-90 solution and weighing this solution for gravimetric yield; and, counting the yttrium-90 containing solution with a radiological counter for a time sufficient to achieve the statistical accuracy desired. It is preferred that the chelating ion-exchange resin is a bidente ligand having the chemical name iminodiacetic acid mounted on a divinyl benzene substrate, converted from sodium form to ammonia form.

Use of Chelex-100 for selectively removing Y-90 from its parent Sr-90

DOEpatents

Huntley, M.W.

1996-02-27

A method for selectively removing yttrium-90 from its parent strontium-90 contained in an environmental sample includes loading the sample onto a column containing a chelating ion-exchange resin capable of retaining yttrium-90; washing the column with a solution capable of removing strontium, calcium, and other contaminants from the yttrium-90 fraction retained on the column; removing excess acetate salts from the column; eluting yttrium-90 solution from the column and adjusting the pH of this solution to about 2.7; filtering the yttrium-90 solution and weighing this solution for gravimetric yield; and, counting the yttrium-90 containing solution with a radiological counter for a time sufficient to achieve the statistical accuracy desired. It is preferred that the chelating ion-exchange resin is a ligand having the chemical name iminodiacetic acid mounted on a divinyl benzene substrate, converted from sodium form to ammonia form.

Microfluidic-Based sample chips for radioactive solutions

DOE PAGES

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

2015-01-01

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

Bioassays for Evaluating Water Quality-Technical Brief

EPA Pesticide Factsheets

Bioassays are a potential solution for assessing complex samples since they screen for total bioactivity for a given pathway or mode of action (MOA), such as estrogen receptor activation, in the samples. EPA has made considerable progress in the developmen

MIGRATION OF HAZARDOUS SUBSTANCES THROUGH SOIL

EPA Science Inventory

Factorlally designed column and batch leaching studies were conducted on samples of various Industrial wastes, flue gas desulfurlzatlon sludges, and coal fly ash to determine the effect of leaching solution composition on release of hazardous substances from waste samples, and t...

Two-photon fluorescence anisotropy imaging

NASA Astrophysics Data System (ADS)

Li, Wei; Wang, Yi; Shao, Hanrong; He, Yonghong; Ma, Hui

2006-09-01

We have developed a novel method for imaging the fluorescence intensity and anisotropy by two-photon fluorescence microscopy and tested its capability in biological application. This method is applied to model sample including FITC and FITC-CD44 antibody solution and also FITC-CD44 stained cells. The fluorescence anisotropy (FA) of FITC-CD44ab solution is higher than the FITC solution with the same concentration. The fluorescence in cell sample has even higher FA than in solution because the rotation diffusion is restrained in membrane. The method is employed to study the effect of berberine a kind of Chinese medicine, on tumor metastasis. The results indicated that tumor cell membrane fluidity is decreasing with increasing the concentration of berberine in culture medium.

Guide for SDEC Set up

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

Bibby, R; Guthrie, E

2009-01-30

The instrument has four collection vials that must be filled with ethylene glycol before operation. Each of the four vials should be labeled 1 through 4 and the empty weights recorded. Fill each vial with 80 mL of ethylene glycol and record the weight again. In order for the instrument to operate properly, the collection vials should always have less than 160 mL of total liquid in them. After completing a sample run, remove the collection vials, use a transfer pipette to remove any liquid that might still be on the air paddler, wipe off any condensation from the exteriormore » of the collection vial and record weight. From the instrument, record the ending volume and the time of operation. The solution mixed in the scintillation vial will be 2 ml of a 95% to 50% ethylene glycol to water mixture. To determine the efficiency of counting at all of these concentrations, a series of vials should be set up that consist of 18 ml of Ultima Gold LLT cocktail mixed with standard, regular deionized water and ethylene glycol. The efficiency curve should be counted in the 'Low Level' count mode with the Luminescence Correction ON and the Color Quench Correction ON. Once the tSIE values are determined, chart the cpm against the tSIE numbers and find the best fit for the data. The resulting equation is to be used to converting tSIE values from the collection vials to efficiency. To determine the background cpm value of the ethylene glycol, count a 2 ml sample of ethylene glycol with 18 ml of Ultima Gold for 100 minutes. To determine the total activity of the sample, take two 2 ml aliquots of sample from the first vial and place in separate scintillation vials. Record the weight of each aliquot. Determine the percentage of total sample each aliquot represents by dividing the aliquot weight by the total solution weight from the vial. Also, determine the percentage of ethylene glycol in the sample by dividing the initial solution weight by the final solution weight and multiplying by 100. Add 18 ml of Ultima Gold to each vial and proceed to count for 100 minutes in a 'Low Level' count mode. Before performing a calculation on the dpm value of each aliquot, a subtraction should be made for the background count rate of the ethylene glycol. Based on the background cpm, multiply the background cpm value by the percentage of ethylene glycol in the collection vial. Once the background value is subtracted, calculate the dpm value of the sample based on the tSIE conversion to efficiency. This will produce a dpm value. To convert this to a total activity of the sample, divide the aliquot dpm value by the decimal percentage of total sample the aliquot represents. This gives the total activity of the sample solution. Take the average of both aliquots as a final result. To convert the total activity from the solution in vial one to activity in air, an empirical formula is used to convert activity/gram from vial one to total activity introduced into the system. After calculation the final result for the vial, divide the total by the mass of the sample in vial one. This gives dpm/g (labeled C{sub m}). To convert this to total dpm measured, C = (128.59 * Cm + 10.837)/V Where: C = Tritium concentration in air (dpm/m{sup 3}) C{sub m} = measured tritium concentration from vial 1 (dpm/g) V = Volume of air sampled through instrument (m{sup 3}). C is the final value of tritium concentration in air.« less

Salt weathering in Egyptian limestone after laboratory simulations with continuous flow of salt solutions at different temperatures

NASA Astrophysics Data System (ADS)

Aly, Nevin; Gomez-Heras, Miguel; Hamed, Ayman; Alvarez de Buergo, Monica

2013-04-01

weathering in Egyptian limestone after laboratory simulations with continuous flow of salt solutions at different temperatures Nevin Aly Mohamed (1), Miguel Gomez - Heras(2), Ayman Hamed Ahmed (1), and Monica Alvarez de Buergo(2). (1) Faculty of Pet. & Min. Engineering- Suez Canal University, Suez, Egypt, (2) Instituto de Geociencias (CSIC-UCM) Madrid. Spain. Limestone is one of the most frequent building stones in Egypt and is used since the time of ancient Egyptians and salt weathering is one of the main threats to its conservation. Most of the limestone used in historical monuments in Cairo is a biomicrite extracted from the Mid-Eocene Mokattam Group. During this work, cylindrical samples (2.4 cm diameter and approx. 4.8 cm length) were subjected, in a purpose-made simulation chamber, to simulated laboratory weathering tests with fixed salt concentration (10% weight NaCl solution), at different temperatures, which were kept constant throughout each test (10, 20, 30, 40 oC). During each test, salt solutions flowed continuously imbibing samples by capilarity. Humidity within the simulation chamber was reduced using silica gel to keep it low and constant to increase evaporation rate. Temperature, humidity inside the simulation chamber and samples weight were digitally monitored during each test. Results show the advantages of the proposed experimental methodology using a continuous flow of salt solutions and shed light on the effect of temperature on the dynamics of salt crystallization on and within samples. Research funded by mission sector of high education ministry, Egypt and Geomateriales S2009/MAT-1629.

An improved method for total organic iodine in drinking water.

PubMed

Sayess, Rassil; Reckhow, David A

2017-01-01

A concise, rapid, and sensitive method is developed to measure organically-bound iodine in water. Total organic iodine (TOI) is used as an integrative surrogate that reflects the amount of iodinated organics in a water sample and is quantified using a refined method that builds on previous adsorption and detection approaches. The proposed method combines adsorption, combustion, and trapping of combustion products, with an offline inductively coupled plasma/mass spectrometer (ICP-MS) for iodide detection. During method development, three analytical variables (factors) were varied across two levels each in order to optimize the method for iodine recovery: 1) the sample pH prior to adsorption on the granular activated carbon (GAC); 2) the amount of base addition to the trap solution; and 3) composition of the ICP-MS wash solution. These factors were tested with solutions of eight iodinated model organic compounds, two iodinated inorganic compounds, and field water samples using a full factorial experimental design. An analysis of variance (ANOVA) and related statistical methods were deployed to identify the best combination of conditions (i.e., treatment) that results in the most complete recovery of iodine from the model compounds and the highest rejection of inorganic iodine. The chosen treatment for TOI measurement incorporates a sample pH of less than 1 prior to adsorption onto the GAC, a solution of 2% (v/v) tetramethyl ammonium hydroxide (TMAH) for trapping of combustion products, and a TMAH wash solution of 0.1% (v/v) for the ICP-MS. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of calcination temperatures on microstructures and photocatalytic activity of tungsten trioxide hollow microspheres.

PubMed

Yu, Jiaguo; Qi, Lifang; Cheng, Bei; Zhao, Xiufeng

2008-12-30

Tungsten trioxide hollow microspheres were prepared by immersing SrWO4 microspheres in a concentrated HNO3 solution, and then calcined at different temperatures. The prepared tungsten oxide samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectra, differential thermal analysis-thermogravimetry, UV-visible spectrophotometry, scanning electron microscopy, N2 adsorption/desorption measurements. The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of rhodamine B aqueous solution under visible-light irradiation. It was found that with increasing calcination temperatures, the average crystallite size and average pore size increased, on the contrary, Brunauer-Emmett-Teller-specific surface areas decreased. However, pore volume and porosity increased firstly, and then decreased. Increasing calcination temperatures resulted in the changes of surface morphology of hollow microspheres. The un-calcined and 300 degrees C-calcined samples showed higher photocatalytic activity than other samples. At 400 degrees C, the photocatalytic activity decreased greatly due to the decrease of specific surface areas. At 500 degrees C, the photocatalytic activity of the samples increased again due to the junction effect of two phases.

Simultaneous trace multielement determination by ICP-OES after solid phase extraction with modified octadecyl silica gel.

PubMed

Karbasi, Mohamad-Hadi; Jahanparast, Babak; Shamsipur, Mojtaba; Hassan, Jalal

2009-10-15

Multielement simultaneous determination of 35 trace elements in environmental samples was carried out by inductively coupled plasma emission spectrometry (ICP-OES) after preconcentration with octadecyl silicagel, modified with aurin tricarboxylic acid (Aluminon). Optimal experimental conditions including pH of sample solution, sample volume, sample and eluent flow rate, type, concentration and volume of eluent and foreign ions effect were investigated and established. Trace element ions in aqueous solution were quantitatively adsorbed onto octadecyl silicagel modified with aurin tricarboxylic acid at pH 8.0 with a flow rate of 11.0 mL min(-1). The adsorbed element ions were eluted with 3-5 mL of 0.5 mol L(-1) HNO(3) at a flow rate of 10.0 mL min(-1) and analyzed by ICP-OES simultaneously. The proposed method has at least preconcentration factor of 100 in water samples, which results high sensitive detection of ultra-trace and trace analysis. The present methodology gave recoveries better than 70% and RSD less than 16%.

Colorimetric measurement of carbohydrates in biological wastewater treatment systems: A critical evaluation.

PubMed

Le, Chencheng; Stuckey, David C

2016-05-01

Four laboratory preparations and three commercially available assay kits were tested on the same carbohydrate samples with the addition of 14 different interfering solutes typically found in wastewater treatment plants. This work shows that a wide variety of solutes can interfere with these assays. In addition, a comparative study on the use of these assays with different carbohydrate samples was also carried out, and the metachromatic response was clearly influenced by variation in sample composition. The carbohydrate content in the supernatant of a submerged anaerobic membrane bioreactor (SAMBR) was also measured using these assays, and the amount in the different supernatant samples, with and without a standard addition of glucose to the samples, showed substantial differences. We concluded that the carbohydrates present in wastewater measured using these colorimetric methods could be seriously under- or over-estimated. A new analytical method needs to be developed in order to better understand the biological transformations occurring in anaerobic digestion that leads to the production of soluble microbial products (SMPs) and extracellular polymeric substance (EPS). Copyright © 2016 Elsevier Ltd. All rights reserved.

Formation and identification of nitrosylmyoglobin by Staphylococcus xylosus in raw meat batters: a potential solution for nitrite substitution in meat products.

PubMed

Li, Peijun; Kong, Baohua; Chen, Qian; Zheng, Dongmei; Liu, Ning

2013-01-01

Staphylococcus xylosus and Pediococcus pentosaceus isolated from Chinese dried sausage were assessed for their ability to convert metmyoglobin into nitrosylmyoglobin in Mann-Rogosa-Sharp broth model systems and raw pork meat batters without the addition of nitrite. The results showed that samples in model systems with S. xylosus cultures had an absorption spectra that is typical of nitrosylmyoglobin, an obvious pink colour (judged by visual inspection) and a significantly higher a-value than the control samples or samples inoculated with P. pentosaceus. In raw meat batters, the a-values of the S. xylosus samples were almost the same as those for the meat with nitrite added. The complementary analysis of meat batter samples by photochemical information from UV-vis, electron spin resonance and resonance Raman spectroscopy revealed that the existing status of the myoglobin in meat batters inoculated with S. xylosus was mainly pentacoordinate nitrosylmyoglobin. This study provides a potential solution for nitrite substitute in meat products. Copyright © 2012 Elsevier Ltd. All rights reserved.

Applicability of refractometry for fast routine checking of hospital preparations.

PubMed

Hendrickx, Stijn; Verón, Aurora Monteagudo; Van Schepdael, Ann; Adams, Erwin

2016-04-30

Quality control of hospital pharmacy formulations is of the utmost importance to ensure constant quality and to avoid potential mistakes before administration to the patient. In this study we investigated the applicability of refractometry as a fast, inexpensive and easy-to-use quality control measurement. Refractive indices (RI) of a multitude of different hospital formulations with varying concentrations of active compound were measured. The samples consisted of a number of binary aqueous solutions (one compound in water), complex aqueous solutions (multiple compounds in water or in a constant matrix), two suspensions and one emulsion. For all these formulations, linear regression analysis was performed, quality control limits determined and accuracy and repeatability were checked. Subsequently, actual hospital pharmacy samples were analyzed to check whether they were within the specified limits. For both binary and complex aqueous formulations, repeatability was good and a linear correlation for all samples could be observed on condition that the concentration of the active compound was sufficiently high. The refractometer was not sensitive enough for solutions of folic acid and levothyroxine, which had too low a concentration of active compound. Due to lack of homogeneity and light scattering, emulsions and suspensions do not seem suitable for quality control by refractometry. A mathematical equation was generated to predict the refractive index of an aqueous solution containing clonidine HCl as active compound. Values calculated from the equation were compared with measured values and deviations of all samples were found to be lower than 1.3%. In order to use refractometry in a hospital pharmacy for quality control of multicomponent samples, additional intermediate measurements would be required, to overcome the fact that refractometry is not compound specific. In conclusion, we found that refractometry could potentially be useful for daily, fast quality measurements of relatively concentrated binary and more complex aqueous solutions in the hospital pharmacy. Copyright © 2016 Elsevier B.V. All rights reserved.

Terahertz microfluidic chips for detection of amino acids in aqueous solutions

NASA Astrophysics Data System (ADS)

Su, Bo; Zhang, Cong; Fan, Ning; Zhang, Cunlin

2016-11-01

Microfluidic technology can control the fluidic thickness accurately in less than 100 micrometers. So the combination of terahertz (THz) and microfluidic technology becomes one of the most interesting directions towards biological detection. We designed microfluidic chips for terahertz spectroscopy of biological samples in aqueous solutions. Using the terahertz time-domain spectroscopy (THz-TDS) system, we experimentally measured the transmittance of the chips and the THz absorption spectra of L-threonine and L-arginine, respectively. The results indicated the feasibility of performing high sensitivity THz spectroscopy of amino acids solutions. Therefore, the microfluidic chips can realize real-time and label-free measurement for biochemistry samples in THz-TDS system.

Determination of Picloram in Soil and Water by Reversed-Phase Liquid Chromatography

Treesearch

M.J.M. Wells; J.L. Michael; D.G. Neary

1984-01-01

A reversed-phase liquid chromatographic method is presneted for the determination of picloram in the parts per billion (ppb) range in soil, soil solution, and stream samples. Quanitification is effected by UV absorpation at 254 nm. Derivatization is not necessary. The method permits 92% ± 7.1 recovery from water samples and 61.8% ± 11.1 recovery from soil samples....

Demonstration/Validation of the Snap Sampler Passive Ground Water Sampling Device for Sampling Inorganic Analytes at the Former Pease Air Force Base

DTIC Science & Technology

2009-07-01

viii Unit Conversion Factors...sampler is also an economic alternative for sampling for inorganic analytes. ERDC/CRREL TR-09-12 xii Unit Conversion Factors Multiply By To Obtain...head- space and then covered with two layers of tightly fitting aluminum foil. To dissolve the analytes, the solutions were stirred for approximately

Effects of nitrate and water on the oxygen isotopic analysis of barium sulfate precipitated from water samples

USGS Publications Warehouse

Hannon, Janet E.; Böhlke, John Karl; Mroczkowski, Stanley J.

2008-01-01

BaSO4 precipitated from mixed salt solutions by common techniques for SO isotopic analysis may contain quantities of H2O and NO that introduce errors in O isotope measurements. Experiments with synthetic solutions indicate that δ18O values of CO produced by decomposition of precipitated BaSO4 in a carbon reactor may be either too low or too high, depending on the relative concentrations of SO and NO and the δ18O values of the H2O, NO, and SO. Typical δ18O errors are of the order of 0.5 to 1‰ in many sample types, and can be larger in samples containing atmospheric NO, which can cause similar errors in δ17O and Δ17O. These errors can be reduced by (1) ion chromatographic separation of SO from NO, (2) increasing the salinity of the solutions before precipitating BaSO4 to minimize incorporation of H2O, (3) heating BaSO4under vacuum to remove H2O, (4) preparing isotopic reference materials as aqueous samples to mimic the conditions of the samples, and (5) adjusting measured δ18O values based on amounts and isotopic compositions of coexisting H2O and NO. These procedures are demonstrated for SO isotopic reference materials, synthetic solutions with isotopically known reagents, atmospheric deposition from Shenandoah National Park, Virginia, USA, and sulfate salt deposits from the Atacama Desert, Chile, and Mojave Desert, California, USA. These results have implications for the calibration and use of O isotope data in studies of SO sources and reaction mechanisms.

Layered zinc hydroxide nanocones: synthesis, facile morphological and structural modification, and properties

NASA Astrophysics Data System (ADS)

Ma, Wei; Ma, Renzhi; Liang, Jianbo; Wang, Chengxiang; Liu, Xiaohe; Zhou, Kechao; Sasaki, Takayoshi

2014-10-01

Layered zinc hydroxide nanocones intercalated with DS- have been synthesized for the first time via a convenient synthetic approach, using homogeneous precipitation in the presence of urea and sodium dodecyl sulfate (SDS). SDS plays a significant role in controlling the morphologies of as-synthesized samples. Conical samples intercalated with various anions were transformed through an anion-exchange route in ethanol solution, and the original conical structure was perfectly maintained. Additionally, these DS--inserted nanocones can be transformed into square-like nanoplates in aqueous solution at room temperature, fulfilling the need for different morphology-dependent properties. Corresponding ZnO nanocones and nanoplates have been further obtained through the thermal calcination of NO3--intercalating zinc hydroxide nanocones/nanoplates. These ZnO nanostructures with different morphologies exhibit promising photocatalytic properties.Layered zinc hydroxide nanocones intercalated with DS- have been synthesized for the first time via a convenient synthetic approach, using homogeneous precipitation in the presence of urea and sodium dodecyl sulfate (SDS). SDS plays a significant role in controlling the morphologies of as-synthesized samples. Conical samples intercalated with various anions were transformed through an anion-exchange route in ethanol solution, and the original conical structure was perfectly maintained. Additionally, these DS--inserted nanocones can be transformed into square-like nanoplates in aqueous solution at room temperature, fulfilling the need for different morphology-dependent properties. Corresponding ZnO nanocones and nanoplates have been further obtained through the thermal calcination of NO3--intercalating zinc hydroxide nanocones/nanoplates. These ZnO nanostructures with different morphologies exhibit promising photocatalytic properties. Electronic supplementary information (ESI) available: Typical SEM images, TGA curves and XRD patterns of as-prepared samples. See DOI: 10.1039/c4nr04166f

ABSORPTION ANALYZER

DOEpatents

Brooksbank, W.A. Jr.; Leddicotte, G.W.; Strain, J.E.; Hendon, H.H. Jr.

1961-11-14

A means was developed for continuously computing and indicating the isotopic assay of a process solution and for automatically controlling the process output of isotope separation equipment to provide a continuous output of the desired isotopic ratio. A counter tube is surrounded with a sample to be analyzed so that the tube is exactly in the center of the sample. A source of fast neutrons is provided and is spaced from the sample. The neutrons from the source are thermalized by causing them to pass through a neutron moderator, and the neutrons are allowed to diffuse radially through the sample to actuate the counter. A reference counter in a known sample of pure solvent is also actuated by the thermal neutrons from the neutron source. The number of neutrons which actuate the detectors is a function of a concentration of the elements in solution and their neutron absorption cross sections. The pulses produced by the detectors responsive to each neu tron passing therethrough are amplified and counted. The respective times required to accumulate a selected number of counts are measured by associated timing devices. The concentration of a particular element in solution may be determined by utilizing the following relation: T2/Ti = BCR, where B is a constant proportional to the absorption cross sections, T2 is the time of count collection for the unknown solution, Ti is the time of count collection for the pure solvent, R is the isotopic ratlo, and C is the molar concentration of the element to be determined. Knowing the slope constant B for any element and when the chemical concentration is known, the isotopic concentration may be readily determined, and conversely when the isotopic ratio is known, the chemical concentrations may be determined. (AEC)

Comparison of soil solution sampling techniques to assess metal fluxes from contaminated soil to groundwater.

PubMed

Coutelot, F; Sappin-Didier, V; Keller, C; Atteia, O

2014-12-01

The unsaturated zone plays a major role in elemental fluxes in terrestrial ecosystems. A representative chemical analysis of soil pore water is required for the interpretation of soil chemical phenomena and particularly to assess Trace Elements (TEs) mobility. This requires an optimal sampling system to avoid modification of the extracted soil water chemistry and allow for an accurate estimation of solute fluxes. In this paper, the chemical composition of soil solutions sampled by Rhizon® samplers connected to a standard syringe was compared to two other types of suction probes (Rhizon® + vacuum tube and Rhizon® + diverted flow system). We investigated the effects of different vacuum application procedures on concentrations of spiked elements (Cr, As, Zn) mixed as powder into the first 20 cm of 100-cm columns and non-spiked elements (Ca, Na, Mg) concentrations in two types of columns (SiO2 sand and a mixture of kaolinite + SiO2 sand substrates). Rhizon® was installed at different depths. The metals concentrations showed that (i) in sand, peak concentrations cannot be correctly sampled, thus the flux cannot be estimated, and the errors can easily reach a factor 2; (ii) in sand + clay columns, peak concentrations were larger, indicating that they could be sampled but, due to sorption on clay, it was not possible to compare fluxes at different depths. The different samplers tested were not able to reflect the elemental flux to groundwater and, although the Rhizon® + syringe device was more accurate, the best solution remains to be the use of a lysimeter, whose bottom is kept continuously at a suction close to the one existing in the soil.

Multi-volatile method for aroma analysis using sequential dynamic headspace sampling with an application to brewed coffee.

PubMed

Ochiai, Nobuo; Tsunokawa, Jun; Sasamoto, Kikuo; Hoffmann, Andreas

2014-12-05

A novel multi-volatile method (MVM) using sequential dynamic headspace (DHS) sampling for analysis of aroma compounds in aqueous sample was developed. The MVM consists of three different DHS method parameters sets including choice of the replaceable adsorbent trap. The first DHS sampling at 25 °C using a carbon-based adsorbent trap targets very volatile solutes with high vapor pressure (>20 kPa). The second DHS sampling at 25 °C using the same type of carbon-based adsorbent trap targets volatile solutes with moderate vapor pressure (1-20 kPa). The third DHS sampling using a Tenax TA trap at 80 °C targets solutes with low vapor pressure (<1 kPa) and/or hydrophilic characteristics. After the 3 sequential DHS samplings using the same HS vial, the three traps are sequentially desorbed with thermal desorption in reverse order of the DHS sampling and the desorbed compounds are trapped and concentrated in a programmed temperature vaporizing (PTV) inlet and subsequently analyzed in a single GC-MS run. Recoveries of the 21 test aroma compounds for each DHS sampling and the combined MVM procedure were evaluated as a function of vapor pressure in the range of 0.000088-120 kPa. The MVM provided very good recoveries in the range of 91-111%. The method showed good linearity (r2>0.9910) and high sensitivity (limit of detection: 1.0-7.5 ng mL(-1)) even with MS scan mode. The feasibility and benefit of the method was demonstrated with analysis of a wide variety of aroma compounds in brewed coffee. Ten potent aroma compounds from top-note to base-note (acetaldehyde, 2,3-butanedione, 4-ethyl guaiacol, furaneol, guaiacol, 3-methyl butanal, 2,3-pentanedione, 2,3,5-trimethyl pyrazine, vanillin, and 4-vinyl guaiacol) could be identified together with an additional 72 aroma compounds. Thirty compounds including 9 potent aroma compounds were quantified in the range of 74-4300 ng mL(-1) (RSD<10%, n=5). Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Ultra-trace determination of Strontium-90 in environmental soil samples from Qatar by collision/reaction cell-inductively coupled plasma mass spectrometry (CRC-ICP-MS/MS)

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

Al-Meer, S. H.; Amr, M. A.; Helal, A.I.

Because of the very low level of {sup 90}Sr in the environmental soil samples and its determination by beta counting may take several weeks, we developed a procedure for ultra-trace determination of {sup 90}Sr using collision reaction cell-inductively coupled plasma tandem mass spectrometry (CRC-ICP-MS/MS, Agilent 8800). Soil samples were dried at 105 deg. C and then heated in a furnace at 550 deg. C to remove any organics present. 500 g of each soil samples were aliquoted into 2000 ml glass beakers. Each Soils samples were soaked in 2 ppm Sr solution carrier to allow determination of chemical yield. Themore » solid to liquid ratio was 1:1. Finally the soil samples were dried at 105 deg. C. Five hundred milliliters concentrated nitric acid and 250 ml hydrochloric acid volumes were added on 500 g soil samples. The samples were digested on hot plate at 80 deg. C to prevent spraying with continuous manual mixing. The leachate solution was separated. The solids were rinsed with 500 ml deionized water, warmed on a hot plate and the leachate plus previous leachate were filtered and the total volume was reduced to 500 ml by evaporation. Final leachate volume was transferred to a centrifuge tubes. The centrifuge tubes were centrifuged at 3,500 rpm for 10 min. The leachate was transferred to a 1 L beaker and heated on a hot plate to evaporate the leachate to dryness. The reside was re-dissolved in 100 ml of 2% HNO{sub 3} and reduced by evaporation to 10 mL. The solution was measured directly by CRC-ICP-MS/MS by setting the first quadruple analyzer to m/z 90 and introducing oxygen gas into the reaction cell for elimination isobar interference from zirconium-90. The method was validated by measurements of standard reference materials and applied on environmental soil samples. The overall time requirement for the measurement of strontium-90 by CRC-ICP-MS/MS is 2 days, significantly shorter than any radioanalytical protocol currently available. (authors)« less

A rapid and high-precision method for sulfur isotope δ(34)S determination with a multiple-collector inductively coupled plasma mass spectrometer: matrix effect correction and applications for water samples without chemical purification.

PubMed

Lin, An-Jun; Yang, Tao; Jiang, Shao-Yong

2014-04-15

Previous studies have indicated that prior chemical purification of samples, although complex and time-consuming, is essential in obtaining precise and accurate results for sulfur isotope ratios using multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). In this study, we introduce a new, rapid and precise MC-ICP-MS method for sulfur isotope determination from water samples without chemical purification. The analytical work was performed on an MC-ICP-MS instrument with medium mass resolution (m/Δm ~ 3000). Standard-sample bracketing (SSB) was used to correct samples throughout the analytical sessions. Reference materials included an Alfa-S (ammonium sulfate) standard solution, ammonium sulfate provided by the lab of the authors and fresh seawater from the South China Sea. A range of matrix-matched Alfa-S standard solutions and ammonium sulfate solutions was used to investigate the matrix (salinity) effect (matrix was added in the form of NaCl). A seawater sample was used to confirm the reliability of the method. Using matrix-matched (salinity-matched) Alfa-S as the working standard, the measured δ(34)S value of AS (-6.73 ± 0.09‰) was consistent with the reference value (-6.78 ± 0.07‰) within the uncertainty, suggesting that this method could be recommended for the measurement of water samples without prior chemical purification. The δ(34)S value determination for the unpurified seawater also yielded excellent results (21.03 ± 0.18‰) that are consistent with the reference value (20.99‰), thus confirming the feasibility of the technique. The data and the results indicate that it is feasible to use MC-ICP-MS and matrix-matched working standards to measure the sulfur isotopic compositions of water samples directly without chemical purification. In comparison with the existing MC-ICP-MS techniques, the new method is better for directly measuring δ(34)S values in water samples with complex matrices; therefore, it can significantly accelerate analytical turnover. Copyright © 2014 John Wiley & Sons, Ltd.

Frontally eluted components procedure with thin layer chromatography as a mode of sample preparation for high performance liquid chromatography quantitation of acetaminophen in biological matrix.

PubMed

Klimek-Turek, A; Sikora, M; Rybicki, M; Dzido, T H

2016-03-04

A new concept of using thin-layer chromatography to sample preparation for the quantitative determination of solute/s followed by instrumental techniques is presented Thin-layer chromatography (TLC) is used to completely separate acetaminophen and its internal standard from other components (matrix) and to form a single spot/zone containing them at the solvent front position (after the final stage of the thin-layer chromatogram development). The location of the analytes and internal standard in the solvent front zone allows their easy extraction followed by quantitation by HPLC. The exctraction procedure of the solute/s and internal standard can proceed from whole solute frontal zone or its part without lowering in accuracy of quantitative analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

Highly sensitive oligosaccharide analysis in capillary electrophoresis using large-volume sample stacking with an electroosmotic flow pump.

PubMed

Kawai, Takayuki; Watanabe, Masato; Sueyoshi, Kenji; Kitagawa, Fumihiko; Otsuka, Koji

2012-04-06

To obtain high sensitivity in capillary electrophoresis of oligosaccharide without reducing the high resolution with an easy experimental procedure, large-volume sample stacking with an electroosmotic flow pump (LVSEP) was investigated. As a fundamental study, effect of the conductivity of a sample solution in LVSEP was examined. It was revealed that LVSEP was successfully carried out even in using a sample solution with the ionic strength of 150 μM and the conductivity ratio of 20, indicating a good applicability of LVSEP to the analysis of real samples containing salts. When glucose oligomer was analyzed as a model sample in LVSEP-capillary zone electrophoresis (CZE), all peaks were well resolved with decreasing only 5% of the peak-to-peak distance, which suggested 95% of the whole capillary could be used for the effective separation. In the analysis of maltoheptaose, a good calibration line with correlation coefficient of 0.9995 was obtained. The limit of detection was estimated as 2 pM, which was 500-fold lower than that in the conventional CZE. N-linked glycans released from three glycoproteins, bovine ribonuclease B, bovine fetuin, and human α(1)-acid glycoprotein were also analyzed by LVSEP-CZE. By the sample purification with a gel filtration column, further sample dilution to reduce the sample conductivity for LVSEP was not needed. All glycan samples were well concentrated and separated with up to a 770-fold sensitivity increase. The run-to-run repeatabilities of the migration time, peak height, and peak area were good with relative standard deviations of 0.1-1.3%, 1.2-1.7%, and 2.8-4.9%, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Results for the first quarter calendar year 2017 tank 50H salt solution sample

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

Crawford, C. L.

2017-04-12

In this memorandum, the chemical and radionuclide contaminant results from the First Quarter Calendar Year 2017 (CY17) sample of Tank 50H salt solution are presented in tabulated form. The First Quarter CY17 Tank 50H samples [a 200 mL sample obtained 6” below the surface (HTF-50-17-7) and a 1 L sample obtained 66” from the tank bottom (HTF-50-17-8)] were obtained on January 15, 2017 and received at Savannah River National Laboratory (SRNL) on January 16, 2017. Prior to obtaining the samples from Tank 50H, a single pump was run at least 4.4 hours and the samples were pulled immediately after pumpmore » shut down. All volatile organic analysis (VOA) and semi-volatile organic analysis (SVOA) were performed on the surface sample and all other analyses were performed on the variable depth sample. The information from this characterization will be used by Savannah River Remediation (SRR) for the transfer of aqueous waste from Tank 50H to the Saltstone Production Facility, where the waste will be treated and disposed of in the Saltstone Disposal Facility. This memorandum compares results, where applicable, to Saltstone Waste Acceptance Criteria (WAC) limits and targets. The chemical and radionuclide contaminant results from the characterization of the First Quarter CY17 sampling of Tank 50H were requested by SRR personnel and details of the testing are presented in the SRNL Task Technical and Quality Assurance Plan (TTQAP). This memorandum is part of Deliverable 2 from SRR request. Data pertaining to the regulatory limits for Resource Conservation and Recovery Act (RCRA) metals will be documented at a later time per the TTQAP for the Tank 50H saltstone task.« less

System and process for dissolution of solids

DOEpatents

Liezers, Martin; Farmer, III, Orville T.

2017-10-10

A system and process are disclosed for dissolution of solids and "difficult-to-dissolve" solids. A solid sample may be ablated in an ablation device to generate nanoscale particles. Nanoparticles may then swept into a coupled plasma device operating at atmospheric pressure where the solid nanoparticles are atomized. The plasma exhaust may be delivered directly into an aqueous fluid to form a solution containing the atomized and dissolved solids. The composition of the resulting solution reflects the composition of the original solid sample.

GLIMMPSE Lite: Calculating Power and Sample Size on Smartphone Devices

PubMed Central

Munjal, Aarti; Sakhadeo, Uttara R.; Muller, Keith E.; Glueck, Deborah H.; Kreidler, Sarah M.

2014-01-01

Researchers seeking to develop complex statistical applications for mobile devices face a common set of difficult implementation issues. In this work, we discuss general solutions to the design challenges. We demonstrate the utility of the solutions for a free mobile application designed to provide power and sample size calculations for univariate, one-way analysis of variance (ANOVA), GLIMMPSE Lite. Our design decisions provide a guide for other scientists seeking to produce statistical software for mobile platforms. PMID:25541688

Local structure of high-coercivity Fe-Ni-Al alloys

NASA Astrophysics Data System (ADS)

Menushenkov, A. P.; Menushenkov, V. P.; Chernikov, R. V.; Sviridova, T. A.; Grishina, O. V.; Sidorov, V. V.

2011-04-01

Results of hard magnetic Fe-Ni-Al alloys after various thermal processing local structure researches by method of EXAFS-spectroscopy with use of synchrotron radiation at temperature 77 K are presented. It is established, that during cooling a firm solution with critical speed reorganization of a local environment of nickel relative to quickly tempered sample owing to stratification of a firm solution is observed. The subsequent aging at 780°C practically restores local structure, characteristic for quickly tempered sample, keeping thus rather high coercitive force.

Comparison of variants of carbol-fuchsin solution in Ziehl-Neelsen for detection of acid-fast bacilli.

PubMed

Selvakumar, N; Sekar, M Gomathi; Rahman, F; Syamsunder, A; Duraipandian, M; Wares, F; Narayanan, P R

2005-02-01

To evaluate Ziehl-Neelsen (ZN) staining using variants of carbol-fuchsin solution, duplicate smears from 416 samples were stained with ZN, one set with 1% basic fuchsin and the other 0.3%. Another set of duplicate smears from 398 samples were stained with ZN, one with 1% basic fuchsin and the other 0.1%. The coded smears were read and discrepancies resolved. All samples underwent mycobacterial culture. The sensitivity of ZN using 0.3% (65%) and 1% basic fuchsin (62%) was comparable, while it was reduced using 0.1% (74%) compared to 1% basic fuchsin (83%). Reducing the concentration of basic fuchsin below 0.3% in ZN staining was found to significantly reduce its sensitivity.

Factor structure and invariance test of the alcohol use disorder identification test (AUDIT): Comparison and further validation in a U.S. and Philippines college student sample.

PubMed

Tuliao, Antover P; Landoy, Bernice Vania N; McChargue, Dennis E

2016-01-01

The Alcohol Use Disorder Identification Test's factor structure varies depending on population and culture. Because of this inconsistency, this article examined the factor structure of the test and conducted a factorial invariance test between a U.S. and a Philippines college sample. Confirmatory factor analyses indicated that a three-factor solution outperforms the one- and two-factor solution in both samples. Factorial invariance analyses further supports the confirmatory findings by showing that factor loadings were generally invariant across groups; however, item intercepts show non-invariance. Country differences between factors show that Filipino consumption factor mean scores were significantly lower than their U.S. counterparts.

A general method to determine sampling windows for nonlinear mixed effects models with an application to population pharmacokinetic studies.

PubMed

Foo, Lee Kien; McGree, James; Duffull, Stephen

2012-01-01

Optimal design methods have been proposed to determine the best sampling times when sparse blood sampling is required in clinical pharmacokinetic studies. However, the optimal blood sampling time points may not be feasible in clinical practice. Sampling windows, a time interval for blood sample collection, have been proposed to provide flexibility in blood sampling times while preserving efficient parameter estimation. Because of the complexity of the population pharmacokinetic models, which are generally nonlinear mixed effects models, there is no analytical solution available to determine sampling windows. We propose a method for determination of sampling windows based on MCMC sampling techniques. The proposed method attains a stationary distribution rapidly and provides time-sensitive windows around the optimal design points. The proposed method is applicable to determine sampling windows for any nonlinear mixed effects model although our work focuses on an application to population pharmacokinetic models. Copyright © 2012 John Wiley & Sons, Ltd.

Note: Four-port microfluidic flow-cell with instant sample switching

NASA Astrophysics Data System (ADS)

MacGriff, Christopher A.; Wang, Shaopeng; Tao, Nongjian

2013-10-01

A simple device for high-speed microfluidic delivery of liquid samples to a surface plasmon resonance sensor surface is presented. The delivery platform is comprised of a four-port microfluidic cell, two ports serve as inlets for buffer and sample solutions, respectively, and a high-speed selector valve to control the alternate opening and closing of the two outlet ports. The time scale of buffer/sample switching (or sample injection rise and fall time) is on the order of milliseconds, thereby minimizing the opportunity for sample plug dispersion. The high rates of mass transport to and from the central microfluidic sensing region allow for SPR-based kinetic analysis of binding events with dissociation rate constants (kd) up to 130 s-1. The required sample volume is only 1 μL, allowing for minimal sample consumption during high-speed kinetic binding measurement.

On-line double isotope dilution laser ablation inductively coupled plasma mass spectrometry for the quantitative analysis of solid materials.

PubMed

Fernández, Beatriz; Rodríguez-González, Pablo; García Alonso, J Ignacio; Malherbe, Julien; García-Fonseca, Sergio; Pereiro, Rosario; Sanz-Medel, Alfredo

2014-12-03

We report on the determination of trace elements in solid samples by the combination of on-line double isotope dilution and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The proposed method requires the sequential analysis of the sample and a certified natural abundance standard by on-line IDMS using the same isotopically-enriched spike solution. In this way, the mass fraction of the analyte in the sample can be directly referred to the certified standard so the previous characterization of the spike solution is not required. To validate the procedure, Sr, Rb and Pb were determined in certified reference materials with different matrices, including silicate glasses (SRM 610, 612 and 614) and powdered samples (PACS-2, SRM 2710a, SRM 1944, SRM 2702 and SRM 2780). The analysis of powdered samples was carried out both by the preparation of pressed pellets and by lithium borate fusion. Experimental results for the analysis of powdered samples were in agreement with the certified values for all materials. Relative standard deviations in the range of 6-21% for pressed pellets and 3-21% for fused solids were obtained from n=3 independent measurements. Minimal sample preparation, data treatment and consumption of the isotopically-enriched isotopes are the main advantages of the method over previously reported approaches. Copyright © 2014 Elsevier B.V. All rights reserved.

Results Of Routine Strip Effluent Hold Tank, Decontaminated Salt Solution Hold Tank, Caustic Wash Tank And Caustic Storage Tank Samples From Modular Caustic-Side Solvent Extraction Unit During Macrobatch 6 Operations

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

Peters, T. B.

Strip Effluent Hold Tank (SEHT), Decontaminated Salt Solution Hold Tank (DSSHT), Caustic Wash Tank (CWT) and Caustic Storage Tank (CST) samples from several of the ''microbatches'' of Integrated Salt Disposition Project (ISDP) Salt Batch (''Macrobatch'') 6 have been analyzed for {sup 238}Pu, {sup 90}Sr, {sup 137}Cs, and by Inductively Coupled Plasma Emission Spectroscopy (ICPES). The results from the current microbatch samples are similar to those from comparable samples in Macrobatch 5. From a bulk chemical point of view, the ICPES results do not vary considerably between this and the previous macrobatch. The titanium results in the DSSHT samples continue tomore » indicate the presence of Ti, when the feed material does not have detectable levels. This most likely indicates that leaching of Ti from MST in ARP continues to occur. Both the CST and CWT samples indicate that the target Free OH value of 0.03 has been surpassed. While at this time there is no indication that this has caused an operational problem, the CST should be adjusted into specification. The {sup 137}Cs results from the SRNL as well as F/H lab data indicate a potential decline in cesium decontamination factor. Further samples will be carefully monitored to investigate this.« less

Surface complexation and precipitate geometry for aqueous Zn(II) sorption on ferrihydrite I: X-ray absorption extended fine structure spectroscopy analysis

USGS Publications Warehouse

Waychunas, G.A.; Fuller, C.C.; Davis, J.A.

2002-01-01

"Two-line" ferrihydrite samples precipitated and then exposed to a range of aqueous Zn solutions (10-5 to 10-3 M), and also coprecipitated in similar Zn solutions (pH 6.5), have been examined by Zn and Fe K-edge X-ray absorption spectroscopy. Typical Zn complexes on the surface have Zn-O distances of 1.97(0.2) A?? and coordination numbers of about 4.0(0.5), consistent with tetrahedral oxygen coordination. This contrasts with Zn-O distances of 2.11(.02) A?? and coordination numbers of 6 to 7 in the aqueous Zn solutions used in sample preparation. X-ray absorption extended fine structure spectroscopy (EXAFS) fits to the second shell of cation neighbors indicate as many as 4 Zn-Fe neighbors at 3.44(.04) A?? in coprecipitated samples, and about two Zn-Fe neighbors at the same distance in adsorption samples. In both sets of samples, the fitted coordination number of second shell cations decreases as sorption density increases, indicating changes in the number and type of available complexing sites or the onset of competitive precipitation processes. Comparison of our results with the possible geometries for surface complexes and precipitates suggests that the Zn sorption complexes are inner sphere and at lowest adsorption densities are bidentate, sharing apical oxygens with adjacent edge-sharing Fe(O,OH)6 octahedra. Coprecipitation samples have complexes with similar geometry, but these are polydentate, sharing apices with more than two adjacent edge-sharing Fe(O,OH)6 polyhedra. The results are inconsistent with Zn entering the ferrihydrite structure (i.e., solid solution formation) or formation of other Zn-Fe precipitates. The fitted Zn-Fe coordination numbers drop with increasing Zn density with a minimum of about 0.8(.2) at Zn/(Zn + Fe) of 0.08 or more. This change appears to be attributable to the onset of precipitation of zinc hydroxide polymers with mainly tetrahedral Zn coordination. At the highest loadings studied, the nature of the complexes changes further, and a second type of precipitate forms. This has a structure based on a brucite layer topology, with mainly octahedral Zn coordination. Amorphous zinc hydroxide samples prepared for comparison had a closely similar local structure. Analysis of the Fe K-edge EXAFS is consistent with surface complexation reactions and surface precipitation at high Zn loadings with little or no Fe-Zn solid solution formation. The formation of Zn-containing precipitates at solution conditions two or more orders of magnitude below their solubility limit is compared with other sorption and spectroscopic studies that describe similar behavior. Copyright ?? 2002 Elsevier Science Ltd.

Simultaneous extraction and HPLC determination of 3-indole butyric acid and 3-indole acetic acid in pea plant by using ionic liquid-modified silica as sorbent.

PubMed

Sheikhian, Leila; Bina, Sedigheh

2016-01-15

In this study, ionic liquid-modified silica was used as sorbent for simultaneous extraction and preconcentration of 3-indole butyric acid and 3-indole acetic acid in pea plants. The effect of some parameters such as pH and ionic strength of sample solution, amount of sorbent, flow rate of aqueous sample solution and eluent solution, concentration of eluent solution, and temperature were studied for each hormone solution. Percent extraction of 3-indole butyric acid and 3-indole acetic acid was strongly affected by pH of aqueous sample solution. Ionic strength of aqueous phase and temperature showed no serious effects on extraction efficiency of studied plant hormones. Obtained breakthrough volume was 200mL for each of studied hormones. Preconcentration factor for spectroscopic and chromatographic determination of studied hormones was 100 and 4.0×10(3) respectively. Each solid sorbent phase was reusable for almost 10 times of extraction/stripping procedure. Relative standard deviations of extraction/stripping processes of 3-indole butyric acid and 3-indole acetic acid were 2.79% and 3.66% respectively. The calculated limit of detections for IBA and IAA were 9.1×10(-2)mgL(-1) and 1.6×10(-1)mgL(-1) respectively. Copyright © 2015 Elsevier B.V. All rights reserved.

Planetary Sample Caching System Design Options

NASA Technical Reports Server (NTRS)

Collins, Curtis; Younse, Paulo; Backes, Paul

2009-01-01

Potential Mars Sample Return missions would aspire to collect small core and regolith samples using a rover with a sample acquisition tool and sample caching system. Samples would need to be stored in individual sealed tubes in a canister that could be transfered to a Mars ascent vehicle and returned to Earth. A sample handling, encapsulation and containerization system (SHEC) has been developed as part of an integrated system for acquiring and storing core samples for application to future potential MSR and other potential sample return missions. Requirements and design options for the SHEC system were studied and a recommended design concept developed. Two families of solutions were explored: 1)transfer of a raw sample from the tool to the SHEC subsystem and 2)transfer of a tube containing the sample to the SHEC subsystem. The recommended design utilizes sample tool bit change out as the mechanism for transferring tubes to and samples in tubes from the tool. The SHEC subsystem design, called the Bit Changeout Caching(BiCC) design, is intended for operations on a MER class rover.

Micro-scale NMR Experiments for Monitoring the Optimization of Membrane Protein Solutions for Structural Biology.

PubMed

Horst, Reto; Wüthrich, Kurt

2015-07-20

Reconstitution of integral membrane proteins (IMP) in aqueous solutions of detergent micelles has been extensively used in structural biology, using either X-ray crystallography or NMR in solution. Further progress could be achieved by establishing a rational basis for the selection of detergent and buffer conditions, since the stringent bottleneck that slows down the structural biology of IMPs is the preparation of diffracting crystals or concentrated solutions of stable isotope labeled IMPs. Here, we describe procedures to monitor the quality of aqueous solutions of [ 2 H, 15 N]-labeled IMPs reconstituted in detergent micelles. This approach has been developed for studies of β-barrel IMPs, where it was successfully applied for numerous NMR structure determinations, and it has also been adapted for use with α-helical IMPs, in particular GPCRs, in guiding crystallization trials and optimizing samples for NMR studies (Horst et al ., 2013). 2D [ 15 N, 1 H]-correlation maps are used as "fingerprints" to assess the foldedness of the IMP in solution. For promising samples, these "inexpensive" data are then supplemented with measurements of the translational and rotational diffusion coefficients, which give information on the shape and size of the IMP/detergent mixed micelles. Using microcoil equipment for these NMR experiments enables data collection with only micrograms of protein and detergent. This makes serial screens of variable solution conditions viable, enabling the optimization of parameters such as the detergent concentration, sample temperature, pH and the composition of the buffer.

The Solar Swan Dive.

ERIC Educational Resources Information Center

Dilsaver, John S.; Siler, Joseph R.

1991-01-01

Solutions for a problem in which the time necessary for an object to fall into the sun from the average distance from the earth to the sun are presented. Both calculus- and noncalculus-based solutions are presented. A sample computer solution is included. (CW)

Microwave temperature-jump nuclear magnetic resonance system for aqueous solutions

NASA Astrophysics Data System (ADS)

Kawakami, Masaru; Akasaka, Kazuyuki

1998-09-01

A microwave temperature-jump nuclear magnetic resonance (NMR) system suitable for aqueous solutions has been developed. A microwave pulse of a desired length is generated at a frequency of 2.46 GHz from a 1.3 kW magnetron, and is delivered through a waveguide and a coaxial cable to a coupling loop which works as an antenna to the dielectric resonator in the NMR probe. Inside the dielectric resonator, the microwave power is efficiently absorbed by the sample solution (about 100 μl) contained in a glass tube, causing a temperature jump by about 25 °C in less than 20 ms. The temperature after the jump can be maintained by applying intermittent microwave pulses of shorter length. A saddle-type radio-frequency coil is placed around the sample tube inside the hollow of the dielectric resonator to excite spins and detect NMR signals. Both the microwave pulses and the radio-frequency pulses are gated by a pulse programmer of the NMR spectrometer to form a desired temperature-jump pulse sequence. A mechanical mixing device is introduced, which significantly reduces the temperature gradient of the sample solution well within 100 ms after the jump. Application to an aqueous solution of ribonuclease A showed that the protein unfolds within 20 ms of microwave heating.

Use of marker ion and cationic surfactant plastic membrane electrode for potentiometric titration of cationic polyelectrolytes.

PubMed

Masadome, Takashi; Imato, Toshihiko

2003-07-04

A plasticized poly (vinyl chloride) (PVC) membrane electrode sensitive to stearyltrimethylammonium (STA) ion is applied to the determination of cationic polyelectrolytes such as poly (diallyldimethylammonium chloride) (Cat-floc) by potentiometric titration, using a potassium poly (vinyl sulfate) (PVSK) solution as a titrant. The end-point of the titration is detected as the potential change of the plasticized PVC membrane electrode caused by decrease in the concentration of STA ion added to the sample solution as a marker ion due to the ion association reaction between the STA ion and PVSK. The effects of the concentration of STA ion, coexisting electrolytes in the sample solution and pH of the sample on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of cationic polyelectrolyte and the end-point volume of the titrant exists in the concentration range from 2x10(-5) to 4x10(-4) N for Cat-floc, glycol chitosan, and methylglycol chitosan.

Efficient electromagnetic source imaging with adaptive standardized LORETA/FOCUSS.

PubMed

Schimpf, Paul H; Liu, Hesheng; Ramon, Ceon; Haueisen, Jens

2005-05-01

Functional brain imaging and source localization based on the scalp's potential field require a solution to an ill-posed inverse problem with many solutions. This makes it necessary to incorporate a priori knowledge in order to select a particular solution. A computational challenge for some subject-specific head models is that many inverse algorithms require a comprehensive sampling of the candidate source space at the desired resolution. In this study, we present an algorithm that can accurately reconstruct details of localized source activity from a sparse sampling of the candidate source space. Forward computations are minimized through an adaptive procedure that increases source resolution as the spatial extent is reduced. With this algorithm, we were able to compute inverses using only 6% to 11% of the full resolution lead-field, with a localization accuracy that was not significantly different than an exhaustive search through a fully-sampled source space. The technique is, therefore, applicable for use with anatomically-realistic, subject-specific forward models for applications with spatially concentrated source activity.

Effect of ascorbic acid on storage of Greyhound erythrocytes.

PubMed

Fontes, Jorge A; Banerjee, Uddyalok; Iazbik, M Cristina; Marín, Liliana M; Couto, C Guillermo; Palmer, Andre F

2015-09-01

To assess changes in biochemical and biophysical properties of canine RBCs during cold (1° to 6°C) storage in a licensed RBC additive solution (the RBC preservation solution designated AS-1) supplemented with ascorbic acid. Blood samples from 7 neutered male Greyhounds; all dogs had negative results when tested for dog erythrocyte antigen 1.1. Blood was collected into citrate-phosphate-dextrose and stored in AS-1. Stored RBCs were supplemented with 7.1mM ascorbic acid or with saline (0.9% NaCl) solution (control samples). Several biochemical and biophysical properties of RBCs were measured, including percentage hemolysis, oxygen-hemoglobin equilibrium, and the kinetic rate constants for O2 dissociation, carbon monoxide association, and nitric oxide dioxygenation. Greyhound RBCs stored in AS-1 supplemented with ascorbic acid did not have significantly decreased hemolysis, compared with results for the control samples, during the storage period. In this study, ascorbic acid did not reduce hemolysis during storage. Several changes in stored canine RBCs were identified as part of the hypothermic storage lesion.

Conformational free energies of methyl-α-L-iduronic and methyl-β-D-glucuronic acids in water

NASA Astrophysics Data System (ADS)

Babin, Volodymyr; Sagui, Celeste

2010-03-01

We present a simulation protocol that allows for efficient sampling of the degrees of freedom of a solute in explicit solvent. The protocol involves using a nonequilibrium umbrella sampling method, in this case, the recently developed adaptively biased molecular dynamics method, to compute an approximate free energy for the slow modes of the solute in explicit solvent. This approximate free energy is then used to set up a Hamiltonian replica exchange scheme that samples both from biased and unbiased distributions. The final accurate free energy is recovered via the weighted histogram analysis technique applied to all the replicas, and equilibrium properties of the solute are computed from the unbiased trajectory. We illustrate the approach by applying it to the study of the puckering landscapes of the methyl glycosides of α-L-iduronic acid and its C5 epimer β-D-glucuronic acid in water. Big savings in computational resources are gained in comparison to the standard parallel tempering method.

Conformational free energies of methyl-alpha-L-iduronic and methyl-beta-D-glucuronic acids in water.

PubMed

Babin, Volodymyr; Sagui, Celeste

2010-03-14

We present a simulation protocol that allows for efficient sampling of the degrees of freedom of a solute in explicit solvent. The protocol involves using a nonequilibrium umbrella sampling method, in this case, the recently developed adaptively biased molecular dynamics method, to compute an approximate free energy for the slow modes of the solute in explicit solvent. This approximate free energy is then used to set up a Hamiltonian replica exchange scheme that samples both from biased and unbiased distributions. The final accurate free energy is recovered via the weighted histogram analysis technique applied to all the replicas, and equilibrium properties of the solute are computed from the unbiased trajectory. We illustrate the approach by applying it to the study of the puckering landscapes of the methyl glycosides of alpha-L-iduronic acid and its C5 epimer beta-D-glucuronic acid in water. Big savings in computational resources are gained in comparison to the standard parallel tempering method.

Browning control of fresh-cut lettuce by phytoncide treatment.

PubMed

Kim, Do-Hee; Kim, Han-Bit; Chung, Hun-Sik; Moon, Kwang-Deog

2014-09-15

Phytoncide essential oil derived from pine leaves was applied for the control of enzymatic browning of fresh-cut lettuce. Changes in the browning characteristics of cut lettuce treated with phytoncide in an water or ethanol solution (1%, v/v) at 10°C were investigated for 12days at 4°C. Other samples dipped in distilled water or 95% ethanol were used as the controls. The samples treated with phytoncide in an ethanol solution showed significantly higher L* values and lower a* values, ΔE values, browning index, phenolic compounds, and enzyme activities (PPO, POD, PAL) related to browning. The samples dipped in distilled water showed the opposite tendency. On the basis of changes in the browning characteristics, anti-browning effects of each treatment, phytoncide in an ethanol solution was the most effective treatment applied. These results suggest that phytoncide treatment could be used as an effective method for controlling enzymatic browning in fresh-cut lettuce. Copyright © 2014 Elsevier Ltd. All rights reserved.

A novel solution blending method for using olive oil and corn oil as plasticizers in chitosan based organoclay nanocomposites.

PubMed

Giannakas, A; Patsaoura, A; Barkoula, N-M; Ladavos, A

2017-02-10

In the current study a novel reflux-solution blending method is being followed with the introduction of small ethanol volumes into chitosan acetic acid aquatic solution in order to incorporate olive oil and corn oil in chitosan and its organoclay nanocomposites. Ethanol enables the direct interaction of chitosan with oils and results in effective plasticization of chitosan/oil films with remarkable increase of the strain at break from 8% of chitosan and chitosan/oil aquatic samples to app. 22% for chitosan/oil ethanol samples. Compared with olive oil, corn oil is less effective as plasticizer (max strain at break app. 14%). Addition of oils is beneficial for water sorption, water vapor permeability and oxygen permeability response of the obtained films. Barrier properties are further improved after the use of OrgMMT, however OrgMMT results in significant reduction of strain at break of all oil containing samples (app. 8%) acting as stress concentrator upon deformation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Monitoring the chemical production of citrus-derived bioactive 5-demethylnobiletin using surface enhanced Raman spectroscopy

PubMed Central

Zheng, Jinkai; Fang, Xiang; Cao, Yong; Xiao, Hang; He, Lili

2013-01-01

To develop an accurate and convenient method for monitoring the production of citrus-derived bioactive 5-demethylnobiletin from demethylation reaction of nobiletin, we compared surface enhanced Raman spectroscopy (SERS) methods with a conventional HPLC method. Our results show that both the substrate-based and solution-based SERS methods correlated with HPLC method very well. The solution method produced lower root mean square error of calibration and higher correlation coefficient than the substrate method. The solution method utilized an ‘affinity chromatography’-like procedure to separate the reactant nobiletin from the product 5-demthylnobiletin based on their different binding affinity to the silver dendrites. The substrate method was found simpler and faster to collect the SERS ‘fingerprint’ spectra of the samples as no incubation between samples and silver was needed and only trace amount of samples were required. Our results demonstrated that the SERS methods were superior to HPLC method in conveniently and rapidly characterizing and quantifying 5-demethylnobiletin production. PMID:23885986

Monitoring of oxidation steps of ascorbic acid redox reaction by kinetics-sensitive voltcoulometry in unsupported and supported aqueous solutions and real samples.

PubMed

Orlický, Jozef; Gmucová, Katarína; Thurzo, Ilja; Pavlásek, Juraj

2003-04-01

Aqueous solutions of ascorbic acid in unsupported and supported aqueous solutions and real samples were studied by the kinetics-sensitive double-step voltcoulommetric method with the aim to contribute to a better understanding of its behavior in biological systems. The data obtained from measurements made on analytes prepared in the laboratory, as well as those made on real samples (some commercial orange drinks, flash of the fresh fruits) point to the redox reaction of L-ascorbic acid (L-AH2) being very sensitive to both the presence of dissolved gaseous species (O2, CO2) and the ionic strenght in the analyte. Either the dissolved gaseous species, or the higher ionic strength caused by both the presence of supporting electrolyte and increased total concentration of ascorbic acid, respectively, give birth to the degradation of L-AH2. Naturally, the highest percentage of L-AH2 was spotted in fresh fruit.

Effect of silver additive on physicochemical properties of hydroxyapatite applied to reconstructive surgery

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

Zhuk, I. V., E-mail: zhukiv1993@mail.ru; Rasskazova, L. A., E-mail: ly-2207@mail.ru; Korotchenko, N. M., E-mail: korotch@mail.ru

The effect of silver adding to hydroxyapatite (HA) in its solubility in physiological solution and biological activity was investigated. Samples of HA containing silver (AgHA) obtained by liquid-phase method in the conditions of microwave exposure. Solubility (C{sub Ca}{sup 2+}·10{sup 3}, mol/l) of the powders AgHA was determined by chemical methods according trilonometric titration of the calcium ions in physiological solution at 25 and 37 °C. To investigate the biological activity of the samples, a series of experiments on the formation of the calcium-phosphate layer on the surface of the SBF-solution at 37 °C for 28 days. Electronic micrographs of samplesmore » taken at the end of each 7 days of the experiment, indicate the formation of calcium-phosphate layer (CPL) in the samples, the kinetics of which is shown as a function of cumulative concentrations of calcium and magnesium ions from time.« less

Hyperbaric hydrothermal atomic force microscope

DOEpatents

Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

2002-01-01

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

Hyperbaric Hydrothermal Atomic Force Microscope

DOEpatents

Knauss, Kevin G.; Boro, Carl O.; Higgins, Steven R.; Eggleston, Carrick M.

2003-07-01

A hyperbaric hydrothermal atomic force microscope (AFM) is provided to image solid surfaces in fluids, either liquid or gas, at pressures greater than normal atmospheric pressure. The sample can be heated and its surface imaged in aqueous solution at temperatures greater than 100.degree. C. with less than 1 nm vertical resolution. A gas pressurized microscope base chamber houses the stepper motor and piezoelectric scanner. A chemically inert, flexible membrane separates this base chamber from the sample cell environment and constrains a high temperature, pressurized liquid or gas in the sample cell while allowing movement of the scanner. The sample cell is designed for continuous flow of liquid or gas through the sample environment.

New biosensors for food safety screening solutions

NASA Astrophysics Data System (ADS)

Dyer, Maureen A.; Oberholtzer, Jennifer A.; Mulligan, David C.; Hanson, William P.

2009-05-01

Hanson Technologies has developed the automated OmniFresh 1000 system to sample large volumes of produce wash water, collect the pathogens, and detect their presence. By collecting a continuous sidestream of wash water, the OmniFresh uses a sample that represent the entire lot of produce being washed. The OmniFresh does not require bacterial culture or enrichment, and it detects both live and dead bacteria in the collected sample using an in-line sensor. Detection occurs in an array biosensor capable of handling large samples with complex matrices. Additionally, sample can be sent for traditional confirming tests after the screening performed by the OmniFresh.

Method of high-precision microsampled blood and plasma mass densitometry

NASA Technical Reports Server (NTRS)

Hinghofer-Szalkay, H.

1986-01-01

The reliability of the mechanical oscillator technique for blood and plasma density measurements on samples of volumes less than 0.1 ml is examined, and a precision of 0.001 g/l is found if plasma-isodensic heparin solution and siliconized densitometers are employed. Sources of measurement errors in the density determinations include storage of plasma samples, inhomogeneity of blood samples, and density reading before adequate temperature equilibration. In tests of plasma sample storage, the best reproducibility was obtained with samples kept at 4 C. Linear correlations were found between plasma density and plasma protein concentration, blood density and blood hemoglobin concentration, and erythrocyte density and MCHC.

Design of the sample cell in near-field surface-enhanced Raman scattering by finite difference time domain method

NASA Astrophysics Data System (ADS)

Li, Yaqin; Jian, Guoshu; Wu, Shifa

2006-11-01

The rational design of the sample cell may improve the sensitivity of surface-enhanced Raman scattering (SERS) detection in a high degree. Finite difference time domain (FDTD) simulations of the configuration of Ag film-Ag particles illuminated by plane wave and evanescent wave are performed to provide physical insight for design of the sample cell. Numerical solutions indicate that the sample cell can provide more "hot spots' and the massive field intensity enhancement occurs in these "hot spots'. More information on the nanometer character of the sample can be got because of gradient-field Raman (GFR) of evanescent wave.

Determination of preservatives in cosmetics, cleaning agents and pharmaceuticals using fast liquid chromatography.

PubMed

Baranowska, Irena; Wojciechowska, Iwona; Solarz, Natalia; Krutysza, Ewa

2014-01-01

This paper reports the development of a method for simultaneously determining five preservatives in cosmetics, cleaning agents and pharmaceuticals by fast liquid chromatography. Methylisothiazolinone, methylchloroisothiazolinone, benzyl alcohol, sodium benzoate and methylparaben were separated on a Chromolith Fast Gradient reversed-phase 18e column using gradient elution with acetonitrile and a 0.1% aqueous solution of formic acid, with a run time of 3 min. The preparation of solid and liquid samples included ultrasonic extraction with methanol with recoveries ranging from 69 to 119%. The developed method was used to analyze samples of cosmetics (66 samples), cleaning agents (five samples) and pharmaceutical industry products (17 samples).

Determination of actinides in urine and fecal samples

DOEpatents

McKibbin, Terry T.

1993-01-01

A method of determining the radioactivity of specific actinides that are carried in urine or fecal sample material is disclosed. The samples are ashed in a muffle furnace, dissolved in an acid, and then treated in a series of steps of reduction, oxidation, dissolution, and precipitation, including a unique step of passing a solution through a chloride form anion exchange resin for separation of uranium and plutonium from americium.

Determination of actinides in urine and fecal samples

DOEpatents

McKibbin, T.T.

1993-03-02

A method of determining the radioactivity of specific actinides that are carried in urine or fecal sample material is disclosed. The samples are ashed in a muffle furnace, dissolved in an acid, and then treated in a series of steps of reduction, oxidation, dissolution, and precipitation, including a unique step of passing a solution through a chloride form anion exchange resin for separation of uranium and plutonium from americium.

Immunoassay of paralytic shellfish toxins by moving magnetic particles in a stationary liquid-phase lab-on-a-chip.

PubMed

Kim, Myoung-Ho; Choi, Suk-Jung

2015-04-15

In this study, we devised a stationary liquid-phase lab-on-a-chip (SLP LOC), which was operated by moving solid-phase magnetic particles in the stationary liquid phase. The SLP LOC consisted of a sample chamber to which a sample and reactants were added, a detection chamber containing enzyme substrate solution, and a narrow channel connecting the two chambers and filled with buffer. As a model system, competitive immunoassays of saxitoxin (STX), a paralytic shellfish toxin, were conducted in the SLP LOC using protein G-coupled magnetic particles (G-MPs) as the solid phase. Anti-STX antibodies, STX-horseradish peroxidase conjugate, G-MPs, and a STX sample were added to the sample chamber and reacted by shaking. While liquids were in the stationary state, G-MPs were transported from the sample chamber to the detection chamber by moving a magnet below the LOC. After incubation to allow the enzymatic reaction to occur, the absorbance of the detection chamber solution was found to be reciprocally related to the STX concentration of the sample. Thus, the SLP LOC may represent a novel, simple format for point-of-care testing applications of enzyme-linked immunosorbent assays by eliminating complicated liquid handling steps. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of calcination temperature on the microstructure and photocatalytic activity of TiO2-based composite nanotubes prepared by an in situ template dissolution method

NASA Astrophysics Data System (ADS)

Fan, Jiajie; Zhao, Li; Yu, Jiaguo; Liu, Gang

2012-09-01

TiO2-based composite nanotubes, based on an in situ template dissolution method, were one-step fabricated in a mixed aqueous solution of ammonium hexafluorotitanate and boric acid using ZnO nanorods as templates, and then the samples were calcined at different temperatures. The photocatalytic activity of the samples was evaluated by photocatalytic decoloration of Methyl Orange (MO) aqueous solution at ambient temperature under UV light. The results showed that the prepared sample possessed nanoscale tubular morphology with a wall thickness of ca. 30-50 nm, inner diameters of ca. 50-150 nm and lengths of ca. 400-2000 nm. The calcined samples exhibited excellent stabilization of the anatase phase in a wide temperature range of 300-800 °C. The un-calcined and calcined samples possessed hierarchically macro-mesoporous structures. The sample calcined at 600 °C exhibited the highest photocatalytic activity, corresponding to the maximal formation rate of \\z.rad OH on the photocatalyst. This is attributed to the improvement of anatase TiO2 crystallization, the formation of multi-phase structures including anatase, cubic Zn2TiO4, hexagonal ZnTiO3 and cubic ZnTiO3, and the presence of hierarchically macro-mesoporous structures.

Phenanthrene sorption with heterogeneous organic matter in a landfill aquifer material

USGS Publications Warehouse

Karapanagioti, H.K.; Sabatini, D.A.; Kleineidam, S.; Grathwohl, P.; Ligouis, B.

1999-01-01

Phenanthrene was used as a model chemical to study the sorption properties of Canadian River Alluvium aquifer material. Both equilibrium and kinetic sorption processes were evaluated through batch studies. The bulk sample was divided into subsamples with varying properties such as particle size, organic content, equilibration time, etc. in order to determine the effect of these properties on resulting sorption parameters. The data have been interpreted and the effect of experimental variables was quantified using the Freundlich isotherm model and a numerical solution of Fick's 2nd law in porous media. Microscopic organic matter characterization proved to be a valuable tool for explaining the results. Different organic matter properties and sorption mechanisms were observed for each soil subsample. Samples containing coal particles presented high Koc values. Samples with organic matter dominated by organic coatings on quartz grains presented low Koc values and contained a high percentage of fast sorption sites. The numerical solution of Fick's 2ndlaw requires the addition of two terms (fast and slow) in order to fit the kinetics of these heterogeneous samples properly. These results thus demonstrate the need for soil organic matter characterization in order to predict and explain the sorption properties of a soil sample containing heterogeneous organic matter and also the difficulty and complexity of modeling sorption in such samples.

Determination of volatile bases in seafood using the ammonia ion selective electrode: collaborative study.

PubMed

Ellis, P C; Pivarnik, L F; Thiam, M; Ellis, P C; Pivarnik, L F; Thiam, M

2000-01-01

Nine collaborating laboratories tested a combination of 23 seafood samples for volatile bases using an ammonia ion selective electrode. Results were reported as mg NH3/100 g fish, but the method reflected levels of both ammonia and trimethylamine, which permeated the ammonia membrane. The 23 samples were broken down into 8 blind duplicate pairs, 2 Youden matched pairs, and 3 single samples covering fresh to spoiled product ranging from 8 to 82 mg NH3/100 g. Seven species were evaluated: Atlantic cod, squid, Atlantic halibut, gray sole, monkfish, dogfish, and Atlantic mackerel. The ammonia electrode assay was performed on an aqueous homogenate consisting of 95 mL distilled water and 5.0 g sample tissue. Alkaline ion strength adjusting solution (2 mL) was added to the homogenate to liberate ammonia that was sensed by the ion specific electrode and measured on a precalibrated portable meter. Repeatability standard deviations (RSDr) ranged from 4.2 to 17%; reproducibility standard deviations (RSDR) ranged from 8.8 to 21%. A standard ammonium chloride solution was provided to all laboratories to spike 3 different samples at 10 mg NH3/100 g. Recoveries of added ammonia as ammonium chloride for fresh, borderline, and spoiled samples were 88.6, 107, and 128%, respectively.

Oxidative stress, d-ROMs test, and ceruloplasmin.

PubMed

Colombini, Francesco; Carratelli, Mauro; Alberti, Angelo

2016-01-01

Human serum samples were evaluated for oxidative stress with the d-ROMs test. The ceruloplasmin (CP) and copper contents of the samples was independently measured and compared to those calculated on the basis of the d-ROMs test results for pure CP solutions. The d-ROMs readings did not show any significant correlation with either the CP or copper contents of the samples. Critical interference of CP on the d-ROMs test was therefore excluded and the usefulness of the test in the evaluation of global oxidative status of a biological sample could be reassessed.

Study of morphological changes in scattering and optically anisotropic medium through correlation images

NASA Astrophysics Data System (ADS)

Jain, Neha; Shukla, Prashant; Singh, Jai

2018-05-01

Correlation images are very useful in determining the morphological changes. We have investigated the correlation image analysis on depolarization and retardance matrices of polystyrene and gelatine samples respectively. We observed that that correlation images have a potential to show a significant variation with change in the concentration of samples (polystyrene and gelatine). For polystyrene microspheres the correlation value decreases with increasing scattering coefficient. In gelatine samples the correlation also decreases with sample concentration. This variation in correlation for retardance shows the change in a birefringence property of gelatine solution.

Flow injection trace gas analysis method for on-site determination of organoarsenicals

DOEpatents

Aldstadt, J.H. III

1997-06-24

A method is described for real-time determination of the concentration of Lewisite in the ambient atmosphere, the method includes separating and collecting a Lewisite sample from the atmosphere in a collection chamber, converting the collected Lewisite to an arsenite ion solution sample, pumping the arsenite ion containing sample to an electrochemical detector connected to the collection chamber, and electrochemically detecting the converted arsenite ions in the sample, whereby the concentration of arsenite ions detected is proportional to the concentration of Lewisite in the atmosphere. 2 figs.

Determination of Os by isotope dilution-inductively coupled plasma-mass spectrometry with the combination of laser ablation to introduce chemically separated geological samples

NASA Astrophysics Data System (ADS)

Sun, Yali; Ren, Minghao; Xia, Xiaoping; Li, Congying; Sun, Weidong

2015-11-01

A method was developed for the determination of trace Os in geological samples by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) with the combination of chemical separation and preconcentration. Samples are digested using aqua regia in Carius tubes, and the Os analyte is converted into volatile OsO4, which is distilled and absorbed with HBr. The HBr solution is concentrated for further Os purification using the microdistillation technique. The purified Os is dissolved in 10 μl of 0.02% sucrose-0.005% H3PO4 solution and then evaporated on pieces of perfluoroalkoxy (PFA) film, resulting in the formation of a tiny object (< 3 × 104 μm2 superficial area). Using LA-ICP-MS measurements, the object can give Os signals at least 100 times higher than those provided by routine solution-ICP-MS while successfully avoiding the memory effect. The procedural blank and detection limit in the developed technique are 3.0 pg and 1.8 pg for Os, respectively when 1 g of samples is taken. Reference materials (RM) are analyzed, and their Os concentrations obtained by isotope dilution are comparable to reference or literature values. Based on the individual RM results, the precision is estimated within the range of 0.6 to 9.4% relative standard deviation (RSD), revealing that this method is applicable to the determination of trace Os in geological samples.

The effect of different drinks on tooth color after home bleaching

PubMed Central

Karadas, Muhammet; Seven, Nilgun

2014-01-01

Objective: This study evaluated the influence of coffee, tea, cola, and red wine staining on the color of teeth after home bleaching. Materials and Methods: A total of 45 samples were obtained from 45 sound maxillary central incisors. The home bleaching procedure was performed using 10% carbamide peroxide gel applied to the sample surface for a period of 6 h each day, for 14 days. After bleaching, baseline color measurements were taken, and the samples were immersed in four staining solutions (coffee, tea, cola, and red wine) or artificial saliva (n = 9). Following 15 min and 6 h of immersion on the first day and next day, respectively, the samples were washed with distilled water for 10 s. After 15 min, 6 h, 1 week, and 1 month immersions, the color values of each sample were remeasured and the color change values (∆E) were calculated. Color change analysis was performed using a spectrophotometer. The results were analyzed using analysis of variance and Tukey's honestly significant difference test (P <0.05). Results: Of all the staining solutions, the lowest ∆E values were observed with coffee staining versus artificial saliva (control group), for all time intervals evaluated after whitening. Although no statistically differences were observed between the coffee and control group at all the time points evaluated, there were statistically significant differences between the red wine, cola, and tea solutions. Conclusion: Following tooth whitening, patients should avoid drinks that cause tooth staining, particularly red wine, tea and cola. PMID:24966778

Removal of sulfa drugs by sewage treatment in aqueous solution systems: activated carbon treatment and ozone oxidation.

PubMed

Ogata, Fumihiko; Tominaga, Hisato; Kangawa, Moe; Inoue, Kenji; Kawasaki, Naohito

2012-01-01

This study investigates the activated carbon (AC) treatment and ozone oxidation of the sulfa drugs--sulfamethoxazole (SMX), sulfamonomethoxine (SMM), sulfadimidine (SDD), and sulfadimethoxine (SDM)--in aqueous solution systems. Three AC samples were prepared from Shirasagi (AC1 and AC2) and coal (AC3), and the surface functional groups, solution pH, specific surface areas, pore volumes, and morphologies of the three samples were evaluated. The specific surface areas were in the following order: AC1 (1391 m²/g) > AC2 (1053 m²/g) > AC3 (807 m²/g). The pore volume and mean pore diameter of AC3 were greater than those of AC1 and AC2. The concentration of sulfa drugs adsorbed onto the AC samples reached equilibrium within 150 h. Experimental data of the adsorption rate were fitted to a pseudo-second-order model. The amount of sulfa drugs adsorbed onto the AC samples was in the order of SDM < SMM < SDD < SMX; the mechanism of adsorption of the sulfa drugs onto the AC samples depended on the hydrophobicity of the AC surface. The adsorption isotherm data were fitted to Freundlich and Langmuir models. Ozone was generated from oxygen gas using an A-27 ozone generator, and the complete degradation of the sulfa drugs by ozone treatment at 60 mL/min was achieved within 50 min. Ozone treatment caused the structure of the sulfa drugs to decompose via ozone oxidation.

Controlled in situ boron doping of diamond thin films using solution phase

NASA Astrophysics Data System (ADS)

Roy, M.; Dua, A. K.; Nuwad, J.; Girija, K. G.; Tyagi, A. K.; Kulshreshtha, S. K.

2006-12-01

Controlled boron doping of diamond film using nontoxic reagents is a challenge in itself. During the present study, attempts have been made to dope diamond films in situ with boron from a solution of boric acid (H3BO3) in methanol (CH3OH) using a specially designed bubbler that ensured continuous and controlled flow of vapors of boron precursors during deposition. The samples are thoroughly characterized using a host of techniques comprising of x-ray photoelectron spectroscopy, Raman, x-ray diffraction, and current-voltage measurements (I-V). Cross-sectional micro-Raman spectroscopy has been used to obtain depth profile of boron in diamond films. Boron concentration ([B]) in the films is found to vary linearly on a semilog scale with molarity (M) of H3BO3 in CH3OH. Lattice constant of our samples is smaller than the reported American society for testing and materials (ASTM) values due to oxygen incorporation and it increases with [B] in the diamond samples. Heavily boron doped samples exhibit Fano deformation of the Raman line shape and negative and/zero activation barrier in temperature dependent I-V measurements that indicate the formation of metallic phase in the samples. The present study illustrates the feasibility of safe and controlled boron doping of diamond films using a solution of H3BO3 in CH3OH over a significant range of [B] from semiconductor to metallic regime but with a little adverse effect due to unintentional but unavoidable incorporation of oxygen.

Side illuminated optical fiber as a multiplexing element for spectroscopic systems

NASA Astrophysics Data System (ADS)

Egalon, Claudio O.; Matta, Michael P.; Lavezzari, Delbert C.; Insley, Robert Y.; Jaring, Carolyn C.; Quiday, Marie F.

2013-09-01

A new type of colorimeter with multiple channels was demonstrated using a side illuminated optical fiber. When different spots of a properly modified fiber are side illuminated, multiple signals are generated and guided by the waveguide: the essence of multiplexing. This configuration is simple, low cost, does not require a sensitive coating and can analyze several samples along the fiber with a single detector: the most expensive component. Since regular colorimeters use one detector per sample, our new configuration considerably lowers the cost of analyzing multiple samples. This system consists of a fiber mounted over a support, three LEDs, an LED driver, a photo diode and a read-out: to increase the signal, the fiber was tapered. For calibration purposes, six solutions of different concentrations of food dye were prepared, placed inside cuvettes along the fiber length and illuminated by the LEDs. This light passes through the solution, strikes the fiber and is guided to the detector: the darker the solution the lower the signal intensity. Several calibration curves were obtained using different light intensities: it was found that the greater the intensity, the higher the colorimeter sensitivity. This simple capability can be used to easily control the device's sensitivity and its resolution. Although built for three samples only, this device can be modified to accommodate more. With cuvettes measuring 1 cm, it is possible to accommodate one sample per cm of fiber. Also, with minor modifications, this colorimeter can be used for fluorescence, scattering and index of refraction measurements.

Electromembrane extraction of biogenic amines in food samples by a microfluidic-chip system followed by dabsyl derivatization prior to high performance liquid chromatography analysis.

PubMed

Zarghampour, Fereshteh; Yamini, Yadollah; Baharfar, Mahroo; Faraji, Mohammad

2018-06-29

In the present research, an on-chip electromembrane extraction coupled with high performance liquid chromatography was developed for monitoring the trace levels of biogenic amines (BAs), including histamine, tryptamine, putrescine, cadaverine and spermidine in food samples. A porous polypropylene sheet membrane impregnated with an organic solvent was placed between the two parts of the chip device to separate the channels. Two platinum electrodes were mounted at the bottom of these channels, which were connected to a power supply, providing the electrical driving force for migration of ionized analytes from the sample solution through the porous sheet membrane into the acceptor phase. BAs were extracted from 2 mL aqueous sample solutions at neutral pH into 50 μL of acidified (HCl 90 mM) acceptor solution. Supported liquid membrane including NPOE containing 10% DEHP was used to ensure efficient extraction. Low voltage of 40 V was applied over the SLMs during extraction time. The influences of fundamental parameters affecting the transport of BAs were optimized. Under the optimized conditions, the relative standard deviations based on four replicate measurements were less than 8.0% and limit of detections were in range of 3.0-8.0 μg L -1 . Finally, the method was successfully applied to determinate BAs in the food samples and satisfactory results (recovery > 95.6) were obtained. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast Filtration of Bacterial or Mammalian Suspension Cell Cultures for Optimal Metabolomics Results

PubMed Central

Bordag, Natalie; Janakiraman, Vijay; Nachtigall, Jonny; González Maldonado, Sandra; Bethan, Bianca; Laine, Jean-Philippe; Fux, Elie

2016-01-01

The metabolome offers real time detection of the adaptive, multi-parametric response of the organisms to environmental changes, pathophysiological stimuli or genetic modifications and thus rationalizes the optimization of cell cultures in bioprocessing. In bioprocessing the measurement of physiological intracellular metabolite levels is imperative for successful applications. However, a sampling method applicable to all cell types with little to no validation effort which simultaneously offers high recovery rates, high metabolite coverage and sufficient removal of extracellular contaminations is still missing. Here, quenching, centrifugation and fast filtration were compared and fast filtration in combination with a stabilizing washing solution was identified as the most promising sampling method. Different influencing factors such as filter type, vacuum pressure, washing solutions were comprehensively tested. The improved fast filtration method (MxP® FastQuench) followed by routine lipid/polar extraction delivers a broad metabolite coverage and recovery reflecting well physiological intracellular metabolite levels for different cell types, such as bacteria (Escherichia coli) as well as mammalian cells chinese hamster ovary (CHO) and mouse myeloma cells (NS0).The proposed MxP® FastQuench allows sampling, i.e. separation of cells from medium with washing and quenching, in less than 30 seconds and is robustly designed to be applicable to all cell types. The washing solution contains the carbon source respectively the 13C-labeled carbon source to avoid nutritional stress during sampling. This method is also compatible with automation which would further reduce sampling times and the variability of metabolite profiling data. PMID:27438065

Salting-out assisted liquid-liquid extraction with the aid of experimental design for determination of benzimidazole fungicides in high salinity samples by high-performance liquid chromatography.

PubMed

Wen, Yingying; Li, Jinhua; Yang, Fangfang; Zhang, Weiwei; Li, Weiran; Liao, Chunyang; Chen, Lingxin

2013-03-15

A novel method for the simultaneous separation and determination of four benzimidazole fungicides (i.e., carbendazim, fuberidazole, thiophanate-methyl and thiophanate) in high salinity samples was developed by using salting-out assisted liquid-liquid extraction (SALLE) via water-miscible acetonitrile as the extractant coupled with high-performance liquid chromatography. Box-Behnken design and response surface were employed to assist the optimization of SALLE conditions, including volume of salting-out solvent, the pH of sample solution and salting-out solvent as variable factors. The optimal salting-out parameters were obtained as follows: 2 mL of acetonitrile was added to 2 mL of sample solution with pH=4 and then 2 mL salting-out solvent containing 5 mol L(-1) sodium chloride at a pH of 7 was added to the solution for extraction. This procedure afforded a convenient and cost-saving operation with good cleanup ability for the benzimidazole fungicides, such as good linear relationships (R>0.996) between peak area and concentration from 2.5 ng mL(-1) to 500 ng mL(-1), low limits of detection between 0.14 ng mL(-1) and 0.38 ng mL(-1) and the intra-day precisions of retention time below 1.0%. The method recoveries obtained at fortified three concentrations for three seawater samples ranged from 60.4% to 99.1%. The simple, rapid and eco-benign SALLE based method proved potentially applicable for trace benzimidazole fungicides analysis in high salinity samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of a sequential injection-square wave voltammetry method for determination of paraquat in water samples employing the hanging mercury drop electrode.

PubMed

dos Santos, Luciana B O; Infante, Carlos M C; Masini, Jorge C

2010-03-01

This work describes the development and optimization of a sequential injection method to automate the determination of paraquat by square-wave voltammetry employing a hanging mercury drop electrode. Automation by sequential injection enhanced the sampling throughput, improving the sensitivity and precision of the measurements as a consequence of the highly reproducible and efficient conditions of mass transport of the analyte toward the electrode surface. For instance, 212 analyses can be made per hour if the sample/standard solution is prepared off-line and the sequential injection system is used just to inject the solution towards the flow cell. In-line sample conditioning reduces the sampling frequency to 44 h(-1). Experiments were performed in 0.10 M NaCl, which was the carrier solution, using a frequency of 200 Hz, a pulse height of 25 mV, a potential step of 2 mV, and a flow rate of 100 µL s(-1). For a concentration range between 0.010 and 0.25 mg L(-1), the current (i(p), µA) read at the potential corresponding to the peak maximum fitted the following linear equation with the paraquat concentration (mg L(-1)): i(p) = (-20.5 ± 0.3)C (paraquat) - (0.02 ± 0.03). The limits of detection and quantification were 2.0 and 7.0 µg L(-1), respectively. The accuracy of the method was evaluated by recovery studies using spiked water samples that were also analyzed by molecular absorption spectrophotometry after reduction of paraquat with sodium dithionite in an alkaline medium. No evidence of statistically significant differences between the two methods was observed at the 95% confidence level.

MicroRaman measurements for nuclear fuel reprocessing applications

DOE PAGES

Casella, Amanda; Lines, Amanda; Nelson, Gilbert; ...

2016-12-01

Treatment and reuse of used nuclear fuel is a key component in closing the nuclear fuel cycle. Solvent extraction reprocessing methods that have been developed contain various steps tailored to the separation of specific radionuclides, which are highly dependent upon solution properties. The instrumentation used to monitor these processes must be robust, require little or no maintenance, and be able to withstand harsh environments such as high radiation fields and aggressive chemical matrices. Our group has been investigating the use of optical spectroscopy for the on-line monitoring of actinides, lanthanides, and acid strength within fuel reprocessing streams. This paper willmore » focus on the development and application of a new MicroRaman probe for on-line real-time monitoring of the U(VI)/nitrate ion/nitric acid in solutions relevant to used nuclear fuel reprocessing. Previous research has successfully demonstrated the applicability on the macroscopic scale, using sample probes requiring larger solution volumes. In an effort to minimize waste and reduce dose to personnel, we have modified this technique to allow measurement at the microfluidic scale using a Raman microprobe. Under the current sampling environment, Raman samples typically require upwards of 10 mL and larger. Using the new sampling system, we can sample volumes at 10 μL or less, which is a scale reduction of over 1,000 fold in sample size. Finally, this paper will summarize our current work in this area including: comparisons between the macroscopic and microscopic probes for detection limits, optimized channel focusing, and application in a flow cell with varying levels of HNO 3, and UO 2(NO 3) 2.« less

Screen-printed electrode based electrochemical detector coupled with ionic liquid dispersive liquid-liquid microextraction and microvolume back-extraction for determination of mercury in water samples.

PubMed

Fernández, Elena; Vidal, Lorena; Martín-Yerga, Daniel; Blanco, María del Carmen; Canals, Antonio; Costa-García, Agustín

2015-04-01

A novel approach is presented, whereby gold nanostructured screen-printed carbon electrodes (SPCnAuEs) are combined with in-situ ionic liquid formation dispersive liquid-liquid microextraction (in-situ IL-DLLME) and microvolume back-extraction for the determination of mercury in water samples. In-situ IL-DLLME is based on a simple metathesis reaction between a water-miscible IL and a salt to form a water-immiscible IL into sample solution. Mercury complex with ammonium pyrrolidinedithiocarbamate is extracted from sample solution into the water-immiscible IL formed in-situ. Then, an ultrasound-assisted procedure is employed to back-extract the mercury into 10 µL of a 4 M HCl aqueous solution, which is finally analyzed using SPCnAuEs. Sample preparation methodology was optimized using a multivariate optimization strategy. Under optimized conditions, a linear range between 0.5 and 10 µg L(-1) was obtained with a correlation coefficient of 0.997 for six calibration points. The limit of detection obtained was 0.2 µg L(-1), which is lower than the threshold value established by the Environmental Protection Agency and European Union (i.e., 2 µg L(-1) and 1 µg L(-1), respectively). The repeatability of the proposed method was evaluated at two different spiking levels (3 and 10 µg L(-1)) and a coefficient of variation of 13% was obtained in both cases. The performance of the proposed methodology was evaluated in real-world water samples including tap water, bottled water, river water and industrial wastewater. Relative recoveries between 95% and 108% were obtained. Copyright © 2014 Elsevier B.V. All rights reserved.

Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill samples from the Powder River basin, Wyoming

USGS Publications Warehouse

See, R.B.; Reddy, K.J.; Vance, G.F.; Fadlelmawla, A.A.; Blaylock, M.J.

1995-01-01

Geochemical processes and the effects of natural organic solutes on the solubility of selenium in coal-mine backfill aquifers were investigated. Backfill and ground-water samples were collected at coal mines in the Powder River Basin, Wyoming. Backfill was generally dominated by aluminum (14,400 to 49,000 mg/kg (milligrams per kilogram)), iron (3,330 to 23,200 mg/kg), and potassium (7,950 to 18,000 mg/kg). Backfill saturated-paste selenium concentrations ranged from 1 to 156 mg/kg (microsiemens per kilogram). Ground-water total selenium concentrations ranged from 3 to 125 mg/L. Dissolved organic carbon in all ground-water samples was dominated by hydrophobic and hydrophilic acids (38 to 84 percent). Selenite sorption/desorption experiments were conducted using background solutions of distilled-deionized water, 0.1 molar calcium chloride, and isolated hydrophobic and hydrophilic acids. Selenite sorption was larger when 0.1 molar calcium chloride was used. The addition of hydrophilic acid decreased selenite sorption more than the addition of hydrophobic acids. Geochemical modelling was used to predict the solid phases controlling dissolved selenium concentrations and to evaluate the effects of dissolved organic carbon on selenium solubility. Results suggested that 55 to 90 percent of selenium in backfill precipitation/dissolution extracts was dominated by magnesium selenate ion pairs. Dissolved organic carbon had little effect on selenium speciation. A redox chamber was constructed to control Eh and pH in water and backfill-core sample suspensions. The response of selenite and selenate in water samples to redox conditions did not follow thermodynamic predictions. Reduction of selenate in water samples did not occur at any of the redox levels tested.

Determination of fluorine in herbs and water samples by molecular absorption spectrometry after preconcentration on nano-TiO2 using ultrasound-assisted dispersive micro solid phase extraction.

PubMed

Krawczyk-Coda, Magdalena; Stanisz, Ewa

2017-11-01

This work presents ultrasound-assisted dispersive micro solid phase extraction (USA DMSPE) for preconcentration of fluorine (F) in water and herb samples. TiO 2 nanoparticles (NPs) were used as an adsorbent. The determination with slurry sampling was performed via molecular absorption of calcium monofluoride (CaF) at 606.440 nm using a high-resolution continuum source electrothermal absorption spectrometry (HR-CS ET MAS). Several factors influencing the efficiency of the preconcentration technique, such as the amount of TiO 2 , pH of sample solution, ultrasonication and centrifugation time and TiO 2 slurry solution preparation before injection to HR-CS ET MAS, were investigated in detail. The conditions of detection step (wavelength, calcium amount, pyrolysis and molecule-forming temperatures) were also studied. After extraction, adsorbent with the analyte was mixed with 200 μL of H 2 O to prepare a slurry solution. The concentration limit of detection was 0.13 ng mL -1 . The achieved preconcentration factor was 7. The relative standard deviations (RSDs, %) for F in real samples were 3-15%. The accuracy of this method was evaluated by analyses of certified reference materials after spiking: INCT-MPH-2 (Mixed Polish Herbs), INCT-SBF-4 (Soya Bean Flour), ERM-CAO11b (Hard Drinking Water) and TMDA-54.5 (Lake Ontario Water). The measured F contents in reference materials were in satisfactory agreement with the added amounts, and the recoveries were found to be 97-109%. Under the developed extraction conditions, the proposed method has been successfully applied for the determination of F in real water samples (lake, sea, tap water) and herbs.

Characterization of Laboratory Prepared Concrete Pastes Exposed to High Alkaline and High Sodium Salt Solutions

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

Langton, C. A.

The objective of this study was to identify potential chemical degradation mechanisms for the Saltstone Disposal Unit (SDU) concretes, which over the performance life of the structures may be exposed to highly alkaline sodium salt solutions containing sulfate, hydroxide, and other potentially corrosive chemicals in salt solution and saltstone flush water, drain water, leachate and / or pore solution. The samples analyzed in this study were cement pastes prepared in the SIMCO Technologies, Inc. concrete laboratory. They were based on the paste fractions of the concretes used to construct the Saltstone Disposal Units (SDUs). SDU 1 and 4 concrete pastesmore » were represented by the PV1 test specimens. The paste in the SDU 2, 3, 5, and 6 concrete was represented by the PV2 test specimens. SIMCO Technologies, Inc. selected the chemicals and proportions in the aggressive solutions to approximate proportions in the saltstone pore solution [2, 3, 5, and 6]. These test specimens were cured for 56 days in curing chamber before being immersed in aggressive solutions. After exposure, the samples were frozen to prevent additional chemical transport and reaction. Selected archived (retrieved from the freezer) samples were sent to the Savannah River National Laboratory (SRNL) for additional characterization using x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) spectroscopy. Characterization results are summarized in this report. In addition, a correlation between the oxide composition of the pastes and their chemical durability in the alkaline salt solutions is provided.« less

Extraction of DNA from human embryos after long-term preservation in formalin and Bouin's solutions.

PubMed

Nagai, Momoko; Minegishi, Katsura; Komada, Munekazu; Tsuchiya, Maiko; Kameda, Tomomi; Yamada, Shigehito

2016-05-01

The "Kyoto Collection of Human Embryos" at Kyoto University was begun in 1961. Although morphological analyses of samples in the Kyoto Collection have been performed, these embryos have been considered difficult to genetically analyze because they have been preserved in formalin or Bouin's solution for 20-50 years. Owing to the recent advances in molecular biology, it has become possible to extract DNA from long-term fixed tissues. The purpose of this study was to extract DNA from wet preparations of human embryo samples after long-term preservation in fixing solution. We optimized the DNA extraction protocol to be suitable for tissues that have been damaged by long-term fixation, including DNA-protein crosslinking damage. Diluting Li2 CO3 with 70% ethanol effectively removed picric acid from samples fixed in Bouin's solution. Additionally, 20.0 mg/mL proteinase was valuable to lyse the long-term fixed samples. The extracted DNA was checked with PCR amplification using several sets of primers and sequence analysis. The PCR products included at least 295- and 838-bp amplicons. These results show that the extracted DNA is applicable for genetic analyses, and indicate that old embryos in the Kyoto Collection should be made available for future studies. The protocol described in this study can successfully extract DNA from old specimens and, with improvements, should be applicable in research aiming to understand the molecular mechanisms of human congenital anomalies. © 2015 Japanese Teratology Society.

The Reduction of Cr(VI) to Cr(III) by Natural Fe-Bearing Minerals: A Synchrotron XAS Study

NASA Astrophysics Data System (ADS)

Xu, H.; Guo, X.; Ding, M.; Migdissov, A. A.; Boukhalfa, H.; Sun, C.; Roback, R. C.; Reimus, P. W.; Katzman, D.

2017-12-01

Cr(VI) in the form of CrO42- is a pollutant species in groundwater and soils that can pose health and environmental problems. Cr(VI) associated with use as a corrosion inhibitor at a power plant from 1956-1972 is present in a deep groundwater aquifer at Los Alamos National Laboratory. A potential remediation strategy for the Cr contamination is reduction of Cr(VI) to Cr(III) via the acceptance of electrons from naturally occurring or induced Fe(II) occurring in Fe-bearing minerals. In this work, using synchrotron-based X-ray techniques, we investigated the Cr reduction behavior by Fe-bearing minerals from outcrop and core samples representative of the contaminated portion of the aquifer. Samples were exposed to solutions with a range of known Cr (VI) concentrations. XANES and EXAFS spectra showed that all the Cr(VI) had been reduced to Cr(III), and micro XRF mapping revealed close correlation of Cr and Fe distribution, implying that Fe(II) in minerals reduced Cr(VI) in the solution. Similar behavior was observed from in-situ XANES measurements on Cr reduction and adsorption by mineral separates from the rock samples in Cr(VI)-bearing solutions. In addition, to obtain reference parameters for interpreting the data of natural samples, we collected Cr and Fe EXAFS spectra of Cr(III)-Fe(III) hydroxide solid solutions, which show progressive changes in the local structure around Cr and Fe over the whole series.

Visual detection of copper(II) ions in blood samples by controlling the leaching of protein-capped gold nanoparticles.

PubMed

Lee, Yen-Fei; Deng, Ting-Wei; Chiu, Wei-Jane; Wei, Tsao-Yen; Roy, Prathik; Huang, Chih-Ching

2012-04-21

We have developed a simple, low-cost, paper-based probe for the selective colorimetric detection of copper ions (Cu(2+)) in aqueous solutions. The bovine serum albumin (BSA)-modified 13.3-nm Au nanoparticle (BSA-Au NP) probe was designed to detect Cu(2+) ions using lead ions (Pb(2+)) and 2-mercaptoethanol (2-ME) as leaching agents in a glycine-NaOH (pH 12.0) solution. In addition, a nitrocellulose membrane (NCM) was used to trap the BSA-Au NPs, leading to the preparation of a nanocomposite film consisting of a BSA-Au NP-decorated membrane (BSA-Au NPs/NCM). The BSA-Au NPs probe operates on the principle that Cu deposition on the surface of the BSA-Au NPs inhibits their leaching ability, which is accelerated by Pb(2+) ions in the presence of 2-ME. Under optimal solution conditions (5 mM glycine-NaOH (pH 12.0), Pb(2+) (50 μM), and 2-ME (1.0 M)), the Pb(2+)/2-ME-BSA-Au NPs/NCM enabled the detection of Cu(2+) at nanomolar concentrations in aqueous solutions by the naked eye with high selectivity (at least 100-fold over other metal ions). In addition, this cost-effective probe allowed for the rapid and simple determination of Cu(2+) ions in not only natural water samples but also in a complex biological sample (in this case, blood sample).

The Classification of Ground Roasted Decaffeinated Coffee Using UV-VIS Spectroscopy and SIMCA Method

NASA Astrophysics Data System (ADS)

Yulia, M.; Asnaning, A. R.; Suhandy, D.

2018-05-01

In this work, an investigation on the classification between decaffeinated and non- decaffeinated coffee samples using UV-VIS spectroscopy and SIMCA method was investigated. Total 200 samples of ground roasted coffee were used (100 samples for decaffeinated coffee and 100 samples for non-decaffeinated coffee). After extraction and dilution, the spectra of coffee samples solution were acquired using a UV-VIS spectrometer (Genesys™ 10S UV-VIS, Thermo Scientific, USA) in the range of 190-1100 nm. The multivariate analyses of the spectra were performed using principal component analysis (PCA) and soft independent modeling of class analogy (SIMCA). The SIMCA model showed that the classification between decaffeinated and non-decaffeinated coffee samples was detected with 100% sensitivity and specificity.

Thermal nonlinear optical response of meso-tetraphenylporphyrin under aggregation conditions versus that in the absence of aggregation

NASA Astrophysics Data System (ADS)

Rasouli, Saifollah; Sakha, Fereshteh; Mojarrad, Aida G.; Zakavi, Saeed

2018-05-01

In this work, measurement of thermally induced nonlinear refractive index of meso-tetraphenylporphyrin (H2TPP) at different concentrations in 1,2-dicoloroethane using a double-grating interferometer set-up in a pump-probe configuration is reported. The formation of aggregates of H2TPP at concentrations greater than ca. 5 × 10-5 M was evident by deviation from Beer's law. An almost focused pump beam passes through the solution. A part of the pump beam energy is absorbed by the sample and therefore a thermal lens is generated in the sample. An expanded probe beam propagates through the sample and indicates the sample refractive index changes. Just after the sample a band-pass filter cuts off the pump beam from the path but the distorted probe beam passes through a double-grating interferometer consisting of two similar diffraction gratings with a few centimetres distance. A CCD camera is installed after the interferometer in which on its sensitive area two diffraction orders of the gratings are overlying and producing interference pattern. The refractive index changes of the sample are obtained from the phase distribution of the successive interference patterns recorded at different times after turning on of the pump beam using Fourier transform method. In this study, for different concentrations of H2TPP in 1,2-dichloroethane solution the thermal nonlinear refractive index is determined. Also, we present the measurement of the temperature changes induced by the pump beam in the solution. We found that value of nonlinear refractive index increased by increasing the concentration up to a concentration of 5 × 10-4 M and then decreased at higher concentrations. In addition, we have investigated the stability of the observed thermal nonlinearity after a period of two weeks from the sample preparation.

LOGISTICS OF ECOLOGICAL SAMPLING ON LARGE RIVERS

EPA Science Inventory

The objectives of this document are to provide an overview of the logistical problems associated with the ecological sampling of boatable rivers and to suggest solutions to those problems. It is intended to be used as a resource for individuals preparing to collect biological dat...

31. VIEW FROM SOUTHWEST TO CORNER WHERE SAMPLING/CRUSHING ADDITIONS ABUT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

31. VIEW FROM SOUTHWEST TO CORNER WHERE SAMPLING/CRUSHING ADDITIONS ABUT CRUSHED OXIDIZED ORE BIN. INTACT BARREN SOLUTION TANK VISIBLE IN FRONT OF CRUSHED ORE BIN. - Bald Mountain Gold Mill, Nevada Gulch at head of False Bottom Creek, Lead, Lawrence County, SD

Effect of template in MCM-41 on the adsorption of aniline from aqueous solution.

PubMed

Yang, Xinxin; Guan, Qingxin; Li, Wei

2011-11-01

The effect of the surfactant template cetyltrimethylammonium bromide (CTAB) in MCM-41 on the adsorption of aniline was investigated. Various MCM-41 samples were prepared by controlling template removal using an extraction method. The samples were then used as adsorbents for the removal of aniline from aqueous solution. The results showed that the MCM-41 samples with the template partially removed (denoted as C-MCM-41) exhibited better adsorption performance than MCM-41 with the template completely removed (denoted as MCM-41). The reason for this difference may be that the C-MCM-41 samples had stronger hydrophobic properties and selectivity for aniline because of the presence of the template. The porosity and cationic sites generated by the template play an important role in the adsorption process. The optimal adsorbent with moderate template was achieved by changing the ratio of extractant; it has the potential for promising applications in the field of water pollution control. Copyright © 2011 Elsevier Ltd. All rights reserved.

Using the Semiconductors Materials of InSb-ZnTe System in Sensors for Gas Control

NASA Astrophysics Data System (ADS)

Shubenkova, E. G.

2017-04-01

The samples of thin film semiconductor compounds InSb, ZnTe and solid solutions based on them were obtained by vapor deposition of components on a dielectric substrate in a vacuum, followed by annealing and their surface properties in CO, O2 and NH3 gas atmospheres were investigated. Identification of the samples was carried out by X-ray diffraction techniques. In the temperature range 253 ÷ 403 K and a pressure range of 1÷12 Pa the gas adsorption was measured by piezoelectric microbalance technique. In order to establish the basic regularities of processes flowing on samples surface in addition to the electrophisical were used Infrared and Raman spectroscopic measurements. The resulting addiction “surface property - composition” is extreme and have allowed to determine solid solution InSb0,95-ZnTe0,05 as the most sensitive to the presence of ammonia, selective and this sample exhibits a negligible oxidation of surface.

Effect of solution treatment on the fatigue behavior of an as-forged Mg-Zn-Y-Zr alloy

NASA Astrophysics Data System (ADS)

Wang, S. D.; Xu, D. K.; Wang, B. J.; Han, E. H.; Dong, C.

2016-04-01

Through investigating and comparing the fatigue behavior of an as-forged Mg-6.7Zn-1.3Y-0.6Zr (wt.%) alloy before and after solid solution treatment (T4) in laboratory air, the effect of T4 treatment on fatigue crack initiation was disclosed. S-N curves illustrated that the fatigue strength of as-forged samples was 110 MPa, whereas the fatigue strength of T4 samples was only 80 MPa. Observations to fracture surfaces demonstrated that for as-forged samples, fatigue crack initiation sites were covered with a layer of oxide film. However, due to the coarse grain structure and the dissolution of MgZn2 precipitates, the activation and accumulation of {10-12} twins in T4 samples were much easier, resulting in the preferential fatigue crack initiation at cracked twin boundaries (TBs). Surface characterization demonstrated that TB cracking was mainly ascribed to the incompatible plastic deformation in the twinned area and nearby α-Mg matrix.

Multirate sampled-data yaw-damper and modal suppression system design

NASA Technical Reports Server (NTRS)

Berg, Martin C.; Mason, Gregory S.

1990-01-01

A multirate control law synthesized algorithm based on an infinite-time quadratic cost function, was developed along with a method for analyzing the robustness of multirate systems. A generalized multirate sampled-data control law structure (GMCLS) was introduced. A new infinite-time-based parameter optimization multirate sampled-data control law synthesis method and solution algorithm were developed. A singular-value-based method for determining gain and phase margins for multirate systems was also developed. The finite-time-based parameter optimization multirate sampled-data control law synthesis algorithm originally intended to be applied to the aircraft problem was instead demonstrated by application to a simpler problem involving the control of the tip position of a two-link robot arm. The GMCLS, the infinite-time-based parameter optimization multirate control law synthesis method and solution algorithm, and the singular-value based method for determining gain and phase margins were all demonstrated by application to the aircraft control problem originally proposed for this project.

Evaluation of Commercial-off-the-Shelf Materials for the Preservation of Bacillus anthracis Vegetative Cells for Forensic Analysis.

PubMed

Angelini, Daniel J; Harris, Jacquelyn V; Burton, Laura L; Rastogi, Pooja R; Smith, Lisa S; Rastogi, Vipin K

2018-03-01

Environmental surface sampling is crucial in determining the zones of contamination and overall threat assessment. Viability retention of sampled material is central to such assessments. A systematic study was completed to determine viability of vegetative cells under nonpermissive storage conditions. Despite major gains in nucleic acid sequencing technologies, initial positive identification of threats must be made through direct culture of the sampled material using classical microbiological methods. Solutions have been developed to preserve the viability of pathogens contained within clinical samples, but many have not been examined for their ability to preserve biological agents. The purpose of this study was to systematically examine existing preservation materials that can retain the viability of Bacillus anthracis vegetative cells stored under nonpermissive temperatures. The results show effectiveness of five of seventeen solutions, which are capable of retaining viability of a sporulation deficient strain of B. anthracis Sterne when stored under nonrefrigerated conditions. © 2017 American Academy of Forensic Sciences.

Synthesis carbon foams prepared from gelatin (CFG) for cadmium ion adsorption

NASA Astrophysics Data System (ADS)

Ulfa, M.; Ulfa, D. K.

2018-01-01

In this paper, carbon foam from gelatin (CFG) was synthesized by acid-catalyzed carbonization of gelatin solution on mild condition by the simple method. Gelatin (Ge) were used as sacrificial template and source of carbon. Sulphuric acid was used as acid catalyst. Carbon foam CFG sample were characterized by scanning electron microscope (SEM), nitrogen adsorption desorption and FTIR for knowing textural and structural properties of the sample. Carbon foam CFG sample demonstrated macro pipes-channel like with pore size that varies between 30-40 μ and surface area m 60-100 m2g-1. The carbon foams CFG sample were tested by using adsorption process for obtained their performance for decreasing Cd(II) ions from aqueous solutions. The adsorption capacities for cadmium was 46.7 mg/g obtained by using adsorbent dose 50 mg, initial concentration 50 ppm, contact time, 3 h; room temperature, stirring rate 150 rpm) which reached equilibrium at 55 min. Adsorption process fits using using Lagergren and Ho and McKay equation and measuring data

Influence of Chloride Ions as Contaminants on the Corrosion Behavior of Alloy 718 in Pool Water of Nuclear Power Plants

NASA Astrophysics Data System (ADS)

Hugues, Jonathan; Andrieu, Eric; Blanc, Christine; Cloué, Jean-Marc

The electrochemical behavior of alloy 718 in a chloride-containing boric acid solution was studied to determine the influence of chloride ions as contaminants of pool water of nuclear power plants on the corrosion behavior of the alloy. Experiments were performed at 20°C and 60°C with chloride concentrations from 1.5 to 15 000 ppm, using stationary measurements i.e. OCP versus time measurements and plotting of current-potential curves. After the electrochemical tests, the samples were observed using optical microscopy. Immersion tests in chloride-containing boric acid solutions were also carried out: samples were immersed for a time as long as 17 weeks at open circuit potential and their residual mechanical properties were measured. Results showed that, whatever the chloride concentration, there was no corrosion for samples immersed at open circuit potential. However, when the samples were polarized at high potentials, intergranular corrosion might be observed in occluded zones.

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

Not Available

This volume contains the interim change notice for sample preparation methods. Covered are: acid digestion for metals analysis, fusion of Hanford tank waste solids, water leach of sludges/soils/other solids, extraction procedure toxicity (simulate leach in landfill), sample preparation for gamma spectroscopy, acid digestion for radiochemical analysis, leach preparation of solids for free cyanide analysis, aqueous leach of solids for anion analysis, microwave digestion of glasses and slurries for ICP/MS, toxicity characteristic leaching extraction for inorganics, leach/dissolution of activated metal for radiochemical analysis, extraction of single-shell tank (SST) samples for semi-VOC analysis, preparation and cleanup of hydrocarbon- containing samples for VOCmore » and semi-VOC analysis, receiving of waste tank samples in onsite transfer cask, receipt and inspection of SST samples, receipt and extrusion of core samples at 325A shielded facility, cleaning and shipping of waste tank samplers, homogenization of solutions/slurries/sludges, and test sample preparation for bioassay quality control program.« less

Concurrent DNA Preconcentration and Separation in Bipolar Electrode-Based Microfluidic Device

PubMed Central

Song, Hongjun; Wang, Yi; Garson, Charles; Pant, Kapil

2015-01-01

This paper presents a bipolar electrode (BPE) device in a microfluidic dual-channel design for concurrent preconcentration and separation of composite DNA containing samples. The novelty of the present effort relies on the combination of BPE-induced ion concentration polarization (ICP) and end-labeled free-solution electrophoresis (ELFSE). The ion concentration polarization effect arising from the faradaic reaction on the BPE is utilized to exert opposing electrophoretic and electroosmotic forces on the DNA samples. Meanwhile, end-labeled free-solution electrophoresis alters the mass-charge ratio to enable simultaneous DNA separation in free solution. The microfluidic device was fabricated using standard and soft lithography techniques to form gold-on-glass electrode capped with a PDMS microfluidic channel. Experimental testing with various DNA samples was carried out over a range of applied electric field. Concentration ratios up to 285× within 5 minutes for a 102-mer DNA, and concurrent preconcentration and free-solution separation of binary mixture of free and bound 102-mer DNA within 6 minutes was demonstrated. The effect of applied electric field was also interrogated with respect to pertinent performance metrics of preconcentration and separation. PMID:26005497

A Method for Estimating View Transformations from Image Correspondences Based on the Harmony Search Algorithm.

PubMed

Cuevas, Erik; Díaz, Margarita

2015-01-01

In this paper, a new method for robustly estimating multiple view relations from point correspondences is presented. The approach combines the popular random sampling consensus (RANSAC) algorithm and the evolutionary method harmony search (HS). With this combination, the proposed method adopts a different sampling strategy than RANSAC to generate putative solutions. Under the new mechanism, at each iteration, new candidate solutions are built taking into account the quality of the models generated by previous candidate solutions, rather than purely random as it is the case of RANSAC. The rules for the generation of candidate solutions (samples) are motivated by the improvisation process that occurs when a musician searches for a better state of harmony. As a result, the proposed approach can substantially reduce the number of iterations still preserving the robust capabilities of RANSAC. The method is generic and its use is illustrated by the estimation of homographies, considering synthetic and real images. Additionally, in order to demonstrate the performance of the proposed approach within a real engineering application, it is employed to solve the problem of position estimation in a humanoid robot. Experimental results validate the efficiency of the proposed method in terms of accuracy, speed, and robustness.

ECLSS Sustaining Compatibility Testing on Urine Processor Assembly Nonmetallic Materials for Reformulation of Pretreated Urine Solution

NASA Technical Reports Server (NTRS)

Wingard, C. D.

2015-01-01

On International Space Station (ISS), the Urine Processor Assembly (UPA) converts human urine and flush water into potable water. The urine is acid-pretreated primarily to control microbial growth. In recent years, the sulfuric acid (H2SO4) pretreatment was believed to be largely responsible for producing salt crystals capable of plugging filters in UPA components and significantly reducing the percentage of water recovery from urine. In 2012, ISS management decided to change the acid pretreatment for urine from sulfuric to phosphoric with the goal of eliminating or minimizing formation of salt crystals. In 2013-2014, as part of the qualification of the phosphoric acid (H3PO4) formulation, samples of 12 nonmetallic materials used in UPA components were immersed for up to one year in pretreated urine and brine solutions made with the new H3PO4 formulation. Dynamic mechanical analysis (DMA) was used to measure modulus (stiffness) of the immersed samples compared to virgin control samples. Such compatibility data obtained by DMA for the H3PO4-based solutions were compared to DMA data obtained for the H2SO4-based solutions in 2002-2003.

Simultaneous Spectrophotometric Determination of Rifampicin, Isoniazid and Pyrazinamide in a Single Step

PubMed Central

Asadpour-Zeynali, Karim; Saeb, Elhameh

2016-01-01

Three antituberculosis medications are investigated in this work consist of rifampicin, isoniazid and pyrazinamide. The ultra violet (UV) spectra of these compounds are overlapped, thus use of suitable chemometric methods are helpful for simultaneous spectrophotometric determination of them. A generalized version of net analyte signal standard addition method (GNASSAM) was used for determination of three antituberculosis medications as a model system. In generalized net analyte signal standard addition method only one standard solution was prepared for all analytes. This standard solution contains a mixture of all analytes of interest, and the addition of such solution to sample, causes increases in net analyte signal of each analyte which are proportional to the concentrations of analytes in added standards solution. For determination of concentration of each analyte in some synthetic mixtures, the UV spectra of pure analytes and each sample were recorded in the range of 210 nm-550 nm. The standard addition procedure was performed for each sample and the UV spectrum was recorded after each addition and finally the results were analyzed by net analyte signal method. Obtained concentrations show acceptable performance of GNASSAM in these cases. PMID:28243267

Comparison of the Electrochemical Behavior of Ti and Nanostructured Ti-Coated AISI 304 Stainless Steel in Strongly Acidic Solutions

NASA Astrophysics Data System (ADS)

Attarzadeh, Farid Reza; Elmkhah, Hassan; Fattah-Alhosseini, Arash

2017-02-01

In this study, the electrochemical behaviors of pure titanium (Ti) and nanostructured (NS) Ti-coated AISI 304 stainless steel (SS) in strongly acidic solutions of H2SO4 were investigated and compared. A type of physical vapor deposition method, cathodic arc evaporation, was applied to deposit NS Ti on 304 SS. Scanning electron microscope and X-ray diffraction were used to characterize surface coating morphology. Potentiodynamic polarization, electrochemical impedance spectroscopy, and Mott-Schottky (M-S) analysis were used to evaluate the passive behavior of the samples. Electrochemical measurements revealed that the passive behavior of NS Ti coating was better than that of pure Ti in 0.1 and 0.01 M H2SO4 solutions. M-S analysis indicated that the passive films behaved as n-type semiconductors in H2SO4 solutions and the deposition method did not affect the semiconducting type of passive films formed on the coated samples. In addition, this analysis showed that the NS Ti coating had lower donor densities. Finally, all electrochemical tests showed that the passive behavior of the Ti-coated samples was superior, mainly due to the formation of thicker, yet less defective passive films.

Simply enhancing throughput of free-flow electrophoresis via organic-aqueous environment for purification of weak polarity solute of phenazine-1-carboxylic acid in fermentation of Pseudomonas sp. M18.

PubMed

Yang, Jing-Hua; Shao, Jing; Wang, Hou-Yu; Dong, Jing-Yu; Fan, Liu-Yin; Cao, Cheng-Xi; Xu, Yu-Quan

2012-09-01

Herein, a simple novel free-flow electrophoresis (FFE) method was developed via introduction of organic solvent into the electrolyte system, increasing the solute solubility and throughput of the sample. As a proof of concept, phenazine-1-carboxylic acid (PCA) from Pseudomonas sp. M18 was selected as a model solute for the demonstration on feasibility of novel FFE method on account of its faint solubility in aqueous circumstance. In the developed method, the organic solvent was added into not only the sample buffer to improve the solubility of the solute, but also the background buffer to construct a uniform aqueous-organic circumstance. These factors of organic solvent percentage and types as well as pH value of background buffer were investigated for the purification of PCA in the FFE device via CE. The experiments revealed that the percentage and the types of organic solvent exerted major influence on the purification of PCA. Under the optimized conditions (30 mM phosphate buffer in 60:40 (v/v) water-methanol at an apparent pH 7.0, 3.26 mL/min background flux, 10-min residence time of injected sample, and 400 V), PCA could be continuously purified from its impurities. The flux of sample injection was 10.05 μL/min, and the recovery was up to 93.7%. An 11.9-fold improvement of throughput was found with a carrier buffer containing 40% (v/v) methanol, compared with the pure aqueous phase. The developed procedure is of evident significance for the purification of weak polarity solute via FFE. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The effect of 8.25% sodium hypochlorite on dental pulp dissolution and dentin flexural strength and modulus.

PubMed

Cullen, James K T; Wealleans, James A; Kirkpatrick, Timothy C; Yaccino, John M

2015-06-01

The purpose of this study was to evaluate the effect of various concentrations of sodium hypochlorite (NaOCl), including 8.25%, on dental pulp dissolution and dentin flexural strength and modulus. Sixty dental pulp samples and 55 plane parallel dentin bars were retrieved from extracted human teeth. Five test groups (n = 10) were formed consisting of a pulp sample and dentin bar immersed in various NaOCl solutions. The negative control group (n = 5) consisted of pulp samples and dentin bars immersed in saline. The positive control group (n = 5) consisted of pulp samples immersed in 8.25% NaOCl without a dentin bar. Every 6 minutes for 1 hour, the solutions were refreshed. The dentin bars were tested for flexural strength and modulus with a 3-point bend test. The time until total pulp dissolution and any changes in dentin bar flexural strength and modulus for the different NaOCl solutions were statistically analyzed. An increase in NaOCl concentration showed a highly significant decrease in pulp dissolution time. The pulp dissolution property of 8.25% NaOCl was significantly faster than any other tested concentration of NaOCl. The presence of dentin did not have a significant effect on the dissolution capacity of NaOCl if the solutions were refreshed. NaOCl concentration did not have a statistically significant effect on dentin flexural strength or modulus. Dilution of NaOCl decreases its pulp dissolution capacity. Refreshing the solution is essential to counteract the effects of dentin. In this study, NaOCl did not have a significant effect on dentin flexural strength or modulus. Published by Elsevier Inc.

Measurements of atmospheric nitrous acid and nitric acid

NASA Astrophysics Data System (ADS)

Huang, Gu; Zhou, Xianliang; Deng, Guohong; Qiao, Huancheng; Civerolo, Kevin

A highly sensitive technique for the measurement of atmospheric HONO and HNO 3 is reported. The technique is based on aqueous scrubbing using two coil samplers, followed by conversion of HNO 3 to nitrite, derivatization of nitrite to a highly light-absorbing azo dye with sulfanilamide (SA) and N-(1-naphthyl) ethylenediamine (NED), and high performance liquid chromatography (HPLC) analysis. HNO 3 concentration was obtained by the difference of the two channels. Two scrubbing solutions were used for sampling the two species: a 1-mM phosphate buffer solution (pH 7) for the measurement of HONO and a 180 mM NH 4Cl/NH 3 buffer solution (pH 8.5) for the measurement of HONO+HNO 3. The scrubbing solution flow rate was 0.24 ml min -1 and the gas sampling flow rate was 2 l min -1. HNO 3 in the NH 4Cl/NH 3 buffer solution was quantitatively reduced to nitrite along an on-line 0.8-cm Cd reductor column. Nitrite in both channels was derivatized with 2 mM SA and 0.2 mM NED in 25 mM HCl. Quantitative derivatization was achieved within 5 min at 55°C. The azo dye derivative was then separated from the SA/NED reagent by reversed-phase HPLC and detected with a UV-vis detector at 540 nm. With an on-line SEP-PAK C-18 cartridge for the reagent purification, the method detection limit is estimated to be better than 1 pptv for HONO and about 20 pptv for HNO 3. The sample integration time was about 2 min and the sampling frequency is every 10 min. Data collected in downtown Albany and Whiteface Mountain, NY, are shown as examples of applications of this technique in both urban and remote clean environments.

Sampling Molecular Conformers in Solution with Quantum Mechanical Accuracy at a Nearly Molecular-Mechanics Cost.

PubMed

Rosa, Marta; Micciarelli, Marco; Laio, Alessandro; Baroni, Stefano

2016-09-13

We introduce a method to evaluate the relative populations of different conformers of molecular species in solution, aiming at quantum mechanical accuracy, while keeping the computational cost at a nearly molecular-mechanics level. This goal is achieved by combining long classical molecular-dynamics simulations to sample the free-energy landscape of the system, advanced clustering techniques to identify the most relevant conformers, and thermodynamic perturbation theory to correct the resulting populations, using quantum-mechanical energies from density functional theory. A quantitative criterion for assessing the accuracy thus achieved is proposed. The resulting methodology is demonstrated in the specific case of cyanin (cyanidin-3-glucoside) in water solution.

Liquid chromatographic determination of sennosides in Cassia angustifolia leaves.

PubMed

Srivastava, Alpuna; Pandey, Richa; Verma, Ram K; Gupta, Madan M

2006-01-01

A simple liquid chromatographic method was developed for the determination of sennosides B and A in leaves of Cassia angustifolia. These compounds were extracted from leaves with a mixture of methanol-water (70 + 30, v/v) after defatting with hexane. Analyte separation and quantitation were achieved by gradient reversed-phase liquid chromatography and UV absorbance at 270 nm using a photodiode array detector. The method involves the use of an RP-18 Lichrocart reversed-phase column (5 microm, 125 x 4.0 mm id) and a binary gradient mobile-phase profile. The various other aspects of analysis, namely, peak purity, similarity, recovery, repeatability, and robustness, were validated. Average recoveries of 98.5 and 98.6%, with a coefficient of variation of 0.8 and 0.3%, were obtained by spiking sample solution with 3 different concentration solutions of standards (60, 100, and 200 microg/mL). Detection limits were 10 microg/mL for sennoside B and 35 microg/mL for sennoside A, present in the sample solution. The quantitation limits were 28 and 100 microg/mL. The analytical method was applied to a large number of senna leaf samples. The new method provides a reliable tool for rapid screening of C. angustifolia samples in large numbers, which is needed in breeding/genetic engineering and genetic mapping experiments.

Effect of two storage solutions on surface topography of two root-end fillings.

PubMed

Asgary, Saeed; Eghbal, Mohammad Jafar; Parirokh, Masoud; Ghoddusi, Jamileh

2009-12-01

The effect of different storage solutions on surface topography of mineral trioxide aggregate (MTA) and new experimental cement (NEC) as root-end fillings was investigated. Twenty-four single-rooted teeth were cleaned, shaped and obturated in a same manner. After root-end resection, 3-mm deep root-end cavities were ultrasonically prepared. Samples were randomly divided into four test groups (A1-A2-B1-B2, n = 6). Root-end cavities in groups A and B were filled with MTA and NEC, respectively, and were then stored in 100% humidity for 24 h. The samples of groups 1 and 2 were, respectively, immersed in normal saline (NS) and phosphate buffer saline solutions for 1 week. The samples were imaged under stereomicroscope before and after immersion and were then investigated and analysed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA). Results showed significant difference among studied groups. Surface topography of all samples was altered by crystal formation and precipitation on root-end fillings except for group A1 (MTA-NS). SEM and EDXA results showed that the composition and structure of precipitated crystals were comparable with that of standard hydroxyapatite. It was concluded that biocompatibility, sealing ability, and cementogenic activity of MTA and probably NEC may be attributed to this fundamental bioactive reaction.

Ocean wavenumber estimation from wave-resolving time series imagery

USGS Publications Warehouse

Plant, N.G.; Holland, K.T.; Haller, M.C.

2008-01-01

We review several approaches that have been used to estimate ocean surface gravity wavenumbers from wave-resolving remotely sensed image sequences. Two fundamentally different approaches that utilize these data exist. A power spectral density approach identifies wavenumbers where image intensity variance is maximized. Alternatively, a cross-spectral correlation approach identifies wavenumbers where intensity coherence is maximized. We develop a solution to the latter approach based on a tomographic analysis that utilizes a nonlinear inverse method. The solution is tolerant to noise and other forms of sampling deficiency and can be applied to arbitrary sampling patterns, as well as to full-frame imagery. The solution includes error predictions that can be used for data retrieval quality control and for evaluating sample designs. A quantitative analysis of the intrinsic resolution of the method indicates that the cross-spectral correlation fitting improves resolution by a factor of about ten times as compared to the power spectral density fitting approach. The resolution analysis also provides a rule of thumb for nearshore bathymetry retrievals-short-scale cross-shore patterns may be resolved if they are about ten times longer than the average water depth over the pattern. This guidance can be applied to sample design to constrain both the sensor array (image resolution) and the analysis array (tomographic resolution). ?? 2008 IEEE.