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Sample records for optimized sample preparation

  1. [Optimized sample preparation for metabolome studies on Streptomyces coelicolor].

    Science.gov (United States)

    Li, Yihong; Li, Shanshan; Ai, Guomin; Wang, Weishan; Zhang, Buchang; Yang, Keqian

    2014-04-01

    Streptomycetes produce many antibiotics and are important model microorgansims for scientific research and antibiotic production. Metabolomics is an emerging technological platform to analyze low molecular weight metabolites in a given organism qualitatively and quantitatively. Compared to other Omics platform, metabolomics has greater advantage in monitoring metabolic flux distribution and thus identifying key metabolites related to target metabolic pathway. The present work aims at establishing a rapid, accurate sample preparation protocol for metabolomics analysis in streptomycetes. In the present work, several sample preparation steps, including cell quenching time, cell separation method, conditions for metabolite extraction and metabolite derivatization were optimized. Then, the metabolic profiles of Streptomyces coelicolor during different growth stages were analyzed by GC-MS. The optimal sample preparation conditions were as follows: time of low-temperature quenching 4 min, cell separation by fast filtration, time of freeze-thaw 45 s/3 min and the conditions of metabolite derivatization at 40 degrees C for 90 min. By using this optimized protocol, 103 metabolites were finally identified from a sample of S. coelicolor, which distribute in central metabolic pathways (glycolysis, pentose phosphate pathway and citrate cycle), amino acid, fatty acid, nucleotide metabolic pathways, etc. By comparing the temporal profiles of these metabolites, the amino acid and fatty acid metabolic pathways were found to stay at a high level during stationary phase, therefore, these pathways may play an important role during the transition between the primary and secondary metabolism. An optimized protocol of sample preparation was established and applied for metabolomics analysis of S. coelicolor, 103 metabolites were identified. The temporal profiles of metabolites reveal amino acid and fatty acid metabolic pathways may play an important role in the transition from primary to

  2. Optimization for Peptide Sample Preparation for Urine Peptidomics

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    Sigdel, Tara K.; Nicora, Carrie D.; Hsieh, Szu-Chuan; Dai, Hong; Qian, Weijun; Camp, David G.; Sarwal, Minnie M.

    2014-02-25

    when utilizing the conventional SPE method. In conclusion, the mSPE method was found to be superior to the conventional, standard SPE method for urine peptide sample preparation when applying LC-MS peptidomics analysis due to the optimized sample clean up that provided improved experimental inference from the confidently identified peptides.

  3. Optimization and validation of sample preparation for metagenomic sequencing of viruses in clinical samples.

    Science.gov (United States)

    Lewandowska, Dagmara W; Zagordi, Osvaldo; Geissberger, Fabienne-Desirée; Kufner, Verena; Schmutz, Stefan; Böni, Jürg; Metzner, Karin J; Trkola, Alexandra; Huber, Michael

    2017-08-08

    Sequence-specific PCR is the most common approach for virus identification in diagnostic laboratories. However, as specific PCR only detects pre-defined targets, novel virus strains or viruses not included in routine test panels will be missed. Recently, advances in high-throughput sequencing allow for virus-sequence-independent identification of entire virus populations in clinical samples, yet standardized protocols are needed to allow broad application in clinical diagnostics. Here, we describe a comprehensive sample preparation protocol for high-throughput metagenomic virus sequencing using random amplification of total nucleic acids from clinical samples. In order to optimize metagenomic sequencing for application in virus diagnostics, we tested different enrichment and amplification procedures on plasma samples spiked with RNA and DNA viruses. A protocol including filtration, nuclease digestion, and random amplification of RNA and DNA in separate reactions provided the best results, allowing reliable recovery of viral genomes and a good correlation of the relative number of sequencing reads with the virus input. We further validated our method by sequencing a multiplexed viral pathogen reagent containing a range of human viruses from different virus families. Our method proved successful in detecting the majority of the included viruses with high read numbers and compared well to other protocols in the field validated against the same reference reagent. Our sequencing protocol does work not only with plasma but also with other clinical samples such as urine and throat swabs. The workflow for virus metagenomic sequencing that we established proved successful in detecting a variety of viruses in different clinical samples. Our protocol supplements existing virus-specific detection strategies providing opportunities to identify atypical and novel viruses commonly not accounted for in routine diagnostic panels.

  4. Optimization of Proteomic Sample Preparation Procedures for Comprehensive Protein Characterization of Pathogenic Systems

    Science.gov (United States)

    Mottaz-Brewer, Heather M.; Norbeck, Angela D.; Adkins, Joshua N.; Manes, Nathan P.; Ansong, Charles; Shi, Liang; Rikihisa, Yasuko; Kikuchi, Takane; Wong, Scott W.; Estep, Ryan D.; Heffron, Fred; Pasa-Tolic, Ljiljana; Smith, Richard D.

    2008-01-01

    Mass spectrometry-based proteomics is a powerful analytical tool for investigating pathogens and their interactions within a host. The sensitivity of such analyses provides broad proteome characterization, but the sample-handling procedures must first be optimized to ensure compatibility with the technique and to maximize the dynamic range of detection. The decision-making process for determining optimal growth conditions, preparation methods, sample analysis methods, and data analysis techniques in our laboratory is discussed herein with consideration of the balance in sensitivity, specificity, and biomass losses during analysis of host-pathogen systems. PMID:19183792

  5. HPLC/DAD determination of rosmarinic acid in Salvia officinalis: sample preparation optimization by factorial design

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    Oliveira, Karina B. de [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Farmacia; Oliveira, Bras H. de, E-mail: bho@ufpr.br [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Dept. de Quimica

    2013-01-15

    Sage (Salvia officinalis) contains high amounts of the biologically active rosmarinic acid (RA) and other polyphenolic compounds. RA is easily oxidized, and may undergo degradation during sample preparation for analysis. The objective of this work was to develop and validate an analytical procedure for determination of RA in sage, using factorial design of experiments for optimizing sample preparation. The statistically significant variables for improving RA extraction yield were determined initially and then used in the optimization step, using central composite design (CCD). The analytical method was then fully validated, and used for the analysis of commercial samples of sage. The optimized procedure involved extraction with aqueous methanol (40%) containing an antioxidant mixture (ascorbic acid and ethylenediaminetetraacetic acid (EDTA)), with sonication at 45 deg C for 20 min. The samples were then injected in a system containing a C{sub 18} column, using methanol (A) and 0.1% phosphoric acid in water (B) in step gradient mode (45A:55B, 0-5 min; 80A:20B, 5-10 min) with flow rate of 1.0 mL min-1 and detection at 330 nm. Using this conditions, RA concentrations were 50% higher when compared to extractions without antioxidants (98.94 {+-} 1.07% recovery). Auto-oxidation of RA during sample extraction was prevented by the use of antioxidants resulting in more reliable analytical results. The method was then used for the analysis of commercial samples of sage. (author)

  6. Evaluation of sample preparation methods and optimization of nickel determination in vegetable tissues

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    Rodrigo Fernando dos Santos Salazar

    2011-02-01

    Full Text Available Nickel, although essential to plants, may be toxic to plants and animals. It is mainly assimilated by food ingestion. However, information about the average levels of elements (including Ni in edible vegetables from different regions is still scarce in Brazil. The objectives of this study were to: (a evaluate and optimize a method for preparation of vegetable tissue samples for Ni determination; (b optimize the analytical procedures for determination by Flame Atomic Absorption Spectrometry (FAAS and by Electrothermal Atomic Absorption (ETAAS in vegetable samples and (c determine the Ni concentration in vegetables consumed in the cities of Lorena and Taubaté in the Vale do Paraíba, State of São Paulo, Brazil. By means of the analytical technique for determination by ETAAS or FAAS, the results were validated by the test of analyte addition and recovery. The most viable method tested for quantification of this element was HClO4-HNO3 wet digestion. All samples but carrot tissue collected in Lorena contained Ni levels above the permitted by the Brazilian Ministry of Health. The most disturbing results, requiring more detailed studies, were the Ni concentrations measured in carrot samples from Taubaté, where levels were five times higher than permitted by Brazilian regulations.

  7. Optimized sample preparation of endoscopic collected pancreatic fluid for SDS-PAGE analysis.

    Science.gov (United States)

    Paulo, Joao A; Lee, Linda S; Wu, Bechien; Repas, Kathryn; Banks, Peter A; Conwell, Darwin L; Steen, Hanno

    2010-07-01

    The standardization of methods for human body fluid protein isolation is a critical initial step for proteomic analyses aimed to discover clinically relevant biomarkers. Several caveats have hindered pancreatic fluid proteomics, including the heterogeneity of samples and protein degradation. We aim to optimize sample handling of pancreatic fluid that has been collected using a safe and effective endoscopic collection method (endoscopic pancreatic function test). Using SDS-PAGE protein profiling, we investigate (i) precipitation techniques to maximize protein extraction, (ii) auto-digestion of pancreatic fluid following prolonged exposure to a range of temperatures, (iii) effects of multiple freeze-thaw cycles on protein stability, and (iv) the utility of protease inhibitors. Our experiments revealed that TCA precipitation resulted in the most efficient extraction of protein from pancreatic fluid of the eight methods we investigated. In addition, our data reveal that although auto-digestion of proteins is prevalent at 23 and 37 degrees C, incubation on ice significantly slows such degradation. Similarly, when the sample is maintained on ice, proteolysis is minimal during multiple freeze-thaw cycles. We have also determined the addition of protease inhibitors to be assay-dependent. Our optimized sample preparation strategy can be applied to future proteomic analyses of pancreatic fluid.

  8. Automation of sample preparation for mass cytometry barcoding in support of clinical research: protocol optimization.

    Science.gov (United States)

    Nassar, Ala F; Wisnewski, Adam V; Raddassi, Khadir

    2017-03-01

    Analysis of multiplexed assays is highly important for clinical diagnostics and other analytical applications. Mass cytometry enables multi-dimensional, single-cell analysis of cell type and state. In mass cytometry, the rare earth metals used as reporters on antibodies allow determination of marker expression in individual cells. Barcode-based bioassays for CyTOF are able to encode and decode for different experimental conditions or samples within the same experiment, facilitating progress in producing straightforward and consistent results. Herein, an integrated protocol for automated sample preparation for barcoding used in conjunction with mass cytometry for clinical bioanalysis samples is described; we offer results of our work with barcoding protocol optimization. In addition, we present some points to be considered in order to minimize the variability of quantitative mass cytometry measurements. For example, we discuss the importance of having multiple populations during titration of the antibodies and effect of storage and shipping of labelled samples on the stability of staining for purposes of CyTOF analysis. Data quality is not affected when labelled samples are stored either frozen or at 4 °C and used within 10 days; we observed that cell loss is greater if cells are washed with deionized water prior to shipment or are shipped in lower concentration. Once the labelled samples for CyTOF are suspended in deionized water, the analysis should be performed expeditiously, preferably within the first hour. Damage can be minimized if the cells are resuspended in phosphate-buffered saline (PBS) rather than deionized water while waiting for data acquisition.

  9. Dynamic simulation tools for the analysis and optimization of novel collection, filtration and sample preparation systems

    Energy Technology Data Exchange (ETDEWEB)

    Clague, D; Weisgraber, T; Rockway, J; McBride, K

    2006-02-12

    The focus of research effort described here is to develop novel simulation tools to address design and optimization needs in the general class of problems that involve species and fluid (liquid and gas phases) transport through sieving media. This was primarily motivated by the heightened attention on Chem/Bio early detection systems, which among other needs, have a need for high efficiency filtration, collection and sample preparation systems. Hence, the said goal was to develop the computational analysis tools necessary to optimize these critical operations. This new capability is designed to characterize system efficiencies based on the details of the microstructure and environmental effects. To accomplish this, new lattice Boltzmann simulation capabilities where developed to include detailed microstructure descriptions, the relevant surface forces that mediate species capture and release, and temperature effects for both liquid and gas phase systems. While developing the capability, actual demonstration and model systems (and subsystems) of national and programmatic interest were targeted to demonstrate the capability. As a result, where possible, experimental verification of the computational capability was performed either directly using Digital Particle Image Velocimetry or published results.

  10. Quality analysis of salmon calcitonin in a polymeric bioadhesive pharmaceutical formulation: sample preparation optimization by DOE.

    Science.gov (United States)

    D'Hondt, Matthias; Van Dorpe, Sylvia; Mehuys, Els; Deforce, Dieter; DeSpiegeleer, Bart

    2010-12-01

    A sensitive and selective HPLC method for the assay and degradation of salmon calcitonin, a 32-amino acid peptide drug, formulated at low concentrations (400 ppm m/m) in a bioadhesive nasal powder containing polymers, was developed and validated. The sample preparation step was optimized using Plackett-Burman and Onion experimental designs. The response functions evaluated were calcitonin recovery and analytical stability. The best results were obtained by treating the sample with 0.45% (v/v) trifluoroacetic acid at 60 degrees C for 40 min. These extraction conditions did not yield any observable degradation, while a maximum recovery for salmon calcitonin of 99.6% was obtained. The HPLC-UV/MS methods used a reversed-phase C(18) Vydac Everest column, with a gradient system based on aqueous acid and acetonitrile. UV detection, using trifluoroacetic acid in the mobile phase, was used for the assay of calcitonin and related degradants. Electrospray ionization (ESI) ion trap mass spectrometry, using formic acid in the mobile phase, was implemented for the confirmatory identification of degradation products. Validation results showed that the methodology was fit for the intended use, with accuracy of 97.4+/-4.3% for the assay and detection limits for degradants ranging between 0.5 and 2.4%. Pilot stability tests of the bioadhesive powder under different storage conditions showed a temperature-dependent decrease in salmon calcitonin assay value, with no equivalent increase in degradation products, explained by the chemical interaction between salmon calcitonin and the carbomer polymer.

  11. OPTIMAL METHOD FOR PREPARATION OF SILICATE ROCK SAMPLES FOR ANALYTICAL PURPOSES

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    Maja Vrkljan

    2004-12-01

    Full Text Available The purpose of this study was to determine an optimal dissolution method for silicate rock samples for further analytical purposes. Analytical FAAS method of determining cobalt, chromium, copper, nickel, lead and zinc content in gabbro sample and geochemical standard AGV-1 has been applied for verification. Dissolution in mixtures of various inorganic acids has been tested, as well as Na2CO3 fusion technique. The results obtained by different methods have been compared and dissolution in the mixture of HNO3 + HF has been recommended as optimal.

  12. Optimization of sample preparation for accurate results in quantitative NMR spectroscopy

    Science.gov (United States)

    Yamazaki, Taichi; Nakamura, Satoe; Saito, Takeshi

    2017-04-01

    Quantitative nuclear magnetic resonance (qNMR) spectroscopy has received high marks as an excellent measurement tool that does not require the same reference standard as the analyte. Measurement parameters have been discussed in detail and high-resolution balances have been used for sample preparation. However, the high-resolution balances, such as an ultra-microbalance, are not general-purpose analytical tools and many analysts may find those balances difficult to use, thereby hindering accurate sample preparation for qNMR measurement. In this study, we examined the relationship between the resolution of the balance and the amount of sample weighed during sample preparation. We were able to confirm the accuracy of the assay results for samples weighed on a high-resolution balance, such as the ultra-microbalance. Furthermore, when an appropriate tare and amount of sample was weighed on a given balance, accurate assay results were obtained with another high-resolution balance. Although this is a fundamental result, it offers important evidence that would enhance the versatility of the qNMR method.

  13. Optimized sample preparation for two-dimensional gel electrophoresis of soluble proteins from chicken bursa of Fabricius

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    Zheng Xiaojuan

    2009-10-01

    Full Text Available Abstract Background Two-dimensional gel electrophoresis (2-DE is a powerful method to study protein expression and function in living organisms and diseases. This technique, however, has not been applied to avian bursa of Fabricius (BF, a central immune organ. Here, optimized 2-DE sample preparation methodologies were constructed for the chicken BF tissue. Using the optimized protocol, we performed further 2-DE analysis on a soluble protein extract from the BF of chickens infected with virulent avibirnavirus. To demonstrate the quality of the extracted proteins, several differentially expressed protein spots selected were cut from 2-DE gels and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS. Results An extraction buffer containing 7 M urea, 2 M thiourea, 2% (w/v 3-[(3-cholamidopropyl-dimethylammonio]-1-propanesulfonate (CHAPS, 50 mM dithiothreitol (DTT, 0.2% Bio-Lyte 3/10, 1 mM phenylmethylsulfonyl fluoride (PMSF, 20 U/ml Deoxyribonuclease I (DNase I, and 0.25 mg/ml Ribonuclease A (RNase A, combined with sonication and vortex, yielded the best 2-DE data. Relative to non-frozen immobilized pH gradient (IPG strips, frozen IPG strips did not result in significant changes in the 2-DE patterns after isoelectric focusing (IEF. When the optimized protocol was used to analyze the spleen and thymus, as well as avibirnavirus-infected bursa, high quality 2-DE protein expression profiles were obtained. 2-DE maps of BF of chickens infected with virulent avibirnavirus were visibly different and many differentially expressed proteins were found. Conclusion These results showed that method C, in concert extraction buffer IV, was the most favorable for preparing samples for IEF and subsequent protein separation and yielded the best quality 2-DE patterns. The optimized protocol is a useful sample preparation method for comparative proteomics analysis of chicken BF tissues.

  14. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers

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    Tisdale, Evgenia; Kennedy, Devin; Wilkins, Charles, E-mail: cwilkins@uark.edu

    2014-01-15

    Graphical abstract: -- Highlights: •We optimized sample preparation for MALDI TOF poly(styrene-copentafluorostyrene) co-polymers. •Influence of matrix choice was investigated. •Influence of matrix/analyte ratio was examined. •Influence of analyte/salt ratio (for Ag+ salt) was studied. -- Abstract: The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr{sub 2}) than is the pentafluorostyrene component distribution.

  15. Optimization of crude enzyme preparation methods for analysis of glutamine synthetase activity in phytoplankton and field samples

    Institute of Scientific and Technical Information of China (English)

    WANG Yujue; WANG Dazhi; HONG Huasheng

    2009-01-01

    Glutamine synthetase (GS) is an important enzyme involved in nitrogen assimilation and metabolism in marine phytoplankton. However, little work has been done in situ due to the limitation of crude enzyme preparation methods. In this study, three enzyme preparation methods, high-speed centrifugation (HC, <10 000 g), ultracentrifugation (UC, 70 000 g), and ultrafiltration (UF) with 100 kμ, molecular weight cutoff, were compared using two diatom species (Asterionellopsis glacialis and Thalassiosira weissflogii), and two dinoflagellate species (Alexandrium catenella and Prorocentrum donghaiense) as experimental materials together with field samples collected from Xiamen Harbor, China. The results showed that HC is the best method to prepare crude enzymes for glutamine synthetase activity (GSA) in diatom species and diatom-dominant samples, while UF is the best method to extract GS from dinoflagellate species and dinoflagellate-dominant samples. For the HC method, the optimal centrifugal speed and time were 10 000 g and 35 min, respectively, and under these conditions, the highest GSA was obtained in all samples. This study indicates that both methods (HC and UF) overcome the limitation of centrifugal speed and could be applied to in situ GSA analysis, especially at sea.

  16. Hyphenation of optimized microfluidic sample preparation with nano liquid chromatography for faster and greener alkaloid analysis

    NARCIS (Netherlands)

    Shen, Y.; Beek, van T.A.; Zuilhof, H.; Chen, B.

    2013-01-01

    A glass liquid–liquid extraction (LLE) microchip with three parallel 3.5 cm long and 100 µm wide interconnecting channels was optimized in terms of more environmentally friendly (greener) solvents and extraction efficiency. In addition, the optimized chip was successfully hyphenated with nano-liquid

  17. Hyphenation of optimized microfluidic sample preparation with nano liquid chromatography for faster and greener alkaloid analysis

    NARCIS (Netherlands)

    Shen, Y.; Beek, van T.A.; Zuilhof, H.; Chen, B.

    2013-01-01

    A glass liquid–liquid extraction (LLE) microchip with three parallel 3.5 cm long and 100 µm wide interconnecting channels was optimized in terms of more environmentally friendly (greener) solvents and extraction efficiency. In addition, the optimized chip was successfully hyphenated with nano-liquid

  18. Optimizing Frozen Sample Preparation for Laser Microdissection: Assessment of CryoJane Tape-Transfer System®.

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    Yelena G Golubeva

    Full Text Available Laser microdissection is an invaluable tool in medical research that facilitates collecting specific cell populations for molecular analysis. Diversity of research targets (e.g., cancerous and precancerous lesions in clinical and animal research, cell pellets, rodent embryos, etc. and varied scientific objectives, however, present challenges toward establishing standard laser microdissection protocols. Sample preparation is crucial for quality RNA, DNA and protein retrieval, where it often determines the feasibility of a laser microdissection project. The majority of microdissection studies in clinical and animal model research are conducted on frozen tissues containing native nucleic acids, unmodified by fixation. However, the variable morphological quality of frozen sections from tissues containing fat, collagen or delicate cell structures can limit or prevent successful harvest of the desired cell population via laser dissection. The CryoJane Tape-Transfer System®, a commercial device that improves cryosectioning outcomes on glass slides has been reported superior for slide preparation and isolation of high quality osteocyte RNA (frozen bone during laser dissection. Considering the reported advantages of CryoJane for laser dissection on glass slides, we asked whether the system could also work with the plastic membrane slides used by UV laser based microdissection instruments, as these are better suited for collection of larger target areas. In an attempt to optimize laser microdissection slide preparation for tissues of different RNA stability and cryosectioning difficulty, we evaluated the CryoJane system for use with both glass (laser capture microdissection and membrane (laser cutting microdissection slides. We have established a sample preparation protocol for glass and membrane slides including manual coating of membrane slides with CryoJane solutions, cryosectioning, slide staining and dissection procedure, lysis and RNA extraction

  19. Sample preparation for an optimized extraction of localized metabolites in lichens: Application to Pseudevernia furfuracea.

    Science.gov (United States)

    Komaty, Sarah; Letertre, Marine; Dang, Huyen Duong; Jungnickel, Harald; Laux, Peter; Luch, Andreas; Carrié, Daniel; Merdrignac-Conanec, Odile; Bazureau, Jean-Pierre; Gauffre, Fabienne; Tomasi, Sophie; Paquin, Ludovic

    2016-04-01

    Lichens are symbiotic organisms known for producing unique secondary metabolites with attractive cosmetic and pharmacological properties. In this paper, we investigated three standard methods of preparation of Pseudevernia furfuracea (blender grinding, ball milling, pestle and mortar). The materials obtained were characterized by electronic microscopy, nitrogen adsorption and compared from the point of view of extraction. Their microscopic structure is related to extraction efficiency. In addition, it is shown using thalline reactions and mass spectrometry mapping (TOF-SIMS) that these metabolites are not evenly distributed throughout the organism. Particularly, atranorin (a secondary metabolite of interest) is mainly present in the cortex of P. furfuracea. Finally, using microwave assisted extraction (MAE) we obtained evidence that an appropriate preparation can increase the extraction efficiency of atranorin by a factor of five.

  20. Optimization of Sample Preparation and Instrumental Parameters for the Rapid Analysis of Drugs of Abuse in Hair samples by MALDI-MS/MS Imaging

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    Flinders, Bryn; Beasley, Emma; Verlaan, Ricky M.; Cuypers, Eva; Francese, Simona; Bassindale, Tom; Clench, Malcolm R.; Heeren, Ron M. A.

    2017-08-01

    Matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) has been employed to rapidly screen longitudinally sectioned drug user hair samples for cocaine and its metabolites using continuous raster imaging. Optimization of the spatial resolution and raster speed were performed on intact cocaine contaminated hair samples. The optimized settings (100 × 150 μm at 0.24 mm/s) were subsequently used to examine longitudinally sectioned drug user hair samples. The MALDI-MS/MS images showed the distribution of the most abundant cocaine product ion at m/z 182. Using the optimized settings, multiple hair samples obtained from two users were analyzed in approximately 3 h: six times faster than the standard spot-to-spot acquisition method. Quantitation was achieved using longitudinally sectioned control hair samples sprayed with a cocaine dilution series. A multiple reaction monitoring (MRM) experiment was also performed using the `dynamic pixel' imaging method to screen for cocaine and a range of its metabolites, in order to differentiate between contaminated hairs and drug users. Cocaine, benzoylecgonine, and cocaethylene were detectable, in agreement with analyses carried out using the standard LC-MS/MS method. [Figure not available: see fulltext.

  1. Optimization of Sample Preparation for the Identification and Quantification of Saxitoxin in Proficiency Test Mussel Sample using Liquid Chromatography-Tandem Mass Spectrometry

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    Kirsi Harju

    2015-11-01

    Full Text Available Saxitoxin (STX and some selected paralytic shellfish poisoning (PSP analogues in mussel samples were identified and quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS. Sample extraction and purification methods of mussel sample were optimized for LC-MS/MS analysis. The developed method was applied to the analysis of the homogenized mussel samples in the proficiency test (PT within the EQuATox project (Establishment of Quality Assurance for the Detection of Biological Toxins of Potential Bioterrorism Risk. Ten laboratories from eight countries participated in the STX PT. Identification of PSP toxins in naturally contaminated mussel samples was performed by comparison of product ion spectra and retention times with those of reference standards. The quantitative results were obtained with LC-MS/MS by spiking reference standards in toxic mussel extracts. The results were within the z-score of ±1 when compared to the results measured with the official AOAC (Association of Official Analytical Chemists method 2005.06, pre-column oxidation high-performance liquid chromatography with fluorescence detection (HPLC-FLD.

  2. An approach to optimize sample preparation for MALDI imaging MS of FFPE sections using fractional factorial design of experiments.

    Science.gov (United States)

    Oetjen, Janina; Lachmund, Delf; Palmer, Andrew; Alexandrov, Theodore; Becker, Michael; Boskamp, Tobias; Maass, Peter

    2016-09-01

    A standardized workflow for matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI imaging MS) is a prerequisite for the routine use of this promising technology in clinical applications. We present an approach to develop standard operating procedures for MALDI imaging MS sample preparation of formalin-fixed and paraffin-embedded (FFPE) tissue sections based on a novel quantitative measure of dataset quality. To cover many parts of the complex workflow and simultaneously test several parameters, experiments were planned according to a fractional factorial design of experiments (DoE). The effect of ten different experiment parameters was investigated in two distinct DoE sets, each consisting of eight experiments. FFPE rat brain sections were used as standard material because of low biological variance. The mean peak intensity and a recently proposed spatial complexity measure were calculated for a list of 26 predefined peptides obtained by in silico digestion of five different proteins and served as quality criteria. A five-way analysis of variance (ANOVA) was applied on the final scores to retrieve a ranking of experiment parameters with increasing impact on data variance. Graphical abstract MALDI imaging experiments were planned according to fractional factorial design of experiments for the parameters under study. Selected peptide images were evaluated by the chosen quality metric (structure and intensity for a given peak list), and the calculated values were used as an input for the ANOVA. The parameters with the highest impact on the quality were deduced and SOPs recommended.

  3. Automated sample preparation for CE-SDS.

    Science.gov (United States)

    Le, M Eleanor; Vizel, Alona; Hutterer, Katariina M

    2013-05-01

    Traditionally, CE with SDS (CE-SDS) places many restrictions on sample composition. Requirements include low salt content, known initial sample concentration, and a narrow window of final sample concentration. As these restrictions require buffer exchange for many sample types, sample preparation is often tedious and yields poor sample recoveries. To improve capacity and streamline sample preparation, an automated robotic platform was developed using the PhyNexus Micro-Extractor Automated Instrument (MEA) for both the reduced and nonreduced CE-SDS assays. This automated sample preparation normalizes sample concentration, removes salts and other contaminants, and adds the required CE-SDS reagents, essentially eliminating manual steps during sample preparation. Fc-fusion proteins and monoclonal antibodies were used in this work to demonstrate benefits of this approach when compared to the manual method. With optimized conditions, this application has demonstrated decreased analyst "hands on" time and reduced total assay time. Sample recovery greater than 90% can be achieved, regardless of initial composition and concentration of analyte.

  4. Optimal sampling of paid content

    OpenAIRE

    Halbheer, Daniel; Stahl, Florian; Koenigsberg, Oded; Lehmann, Donald R

    2011-01-01

    This paper analyzes optimal sampling and pricing of paid content for publishers of news websites. Publishers offer free content samples both to disclose journalistic quality to consumers and to generate online advertising revenues. We examine sampling where the publisher sets the number of free sample articles and consumers select the articles of their choice. Consumerslearn from the free samples in a Bayesian fashion and base their subscription decisions on posterior quality expectations. We...

  5. Sample preparation and biopharmaceutical analysis

    OpenAIRE

    Farrelly, Gillian

    1998-01-01

    In chapter 1, an overview is given of sample preparation methods and analytical techniques in use today. Each one is discussed, and relevant examples are given. In chapter 2, the development of a method for the HPLC analysis of taurine in human plasma using acetonitrile precipitation and pre-column derivatisation with fluorescamine is presented. This procedure was found to be faster and easier to use than previous taurine assays. In chapter 3, the evaluation of novel aspirin derivativ...

  6. Microfluidic Sample Preparation for Immunoassays

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    Visuri, S; Benett, W; Bettencourt, K; Chang, J; Fisher, K; Hamilton, J; Krulevitch, P; Park, C; Stockton, C; Tarte, L; Wang, A; Wilson, T

    2001-08-09

    Researchers at Lawrence Livermore National Laboratory are developing means to collect and identify fluid-based biological pathogens in the forms of proteins, viruses, and bacteria. to support detection instruments, they are developing a flexible fluidic sample preparation unit. The overall goal of this Microfluidic Module is to input a fluid sample, containing background particulates and potentially target compounds, and deliver a processed sample for detection. They are developing techniques for sample purification, mixing, and filtration that would be useful to many applications including immunologic and nucleic acid assays. Many of these fluidic functions are accomplished with acoustic radiation pressure or dielectrophoresis. They are integrating these technologies into packaged systems with pumps and valves to control fluid flow through the fluidic circuit.

  7. [Determination of 51 carbamate pesticide residues in vegetables by liquid chromatography-tandem mass spectrometry based on optimization of QuEChERS sample preparation method].

    Science.gov (United States)

    Wang, Lianzhu; Zhou, Yu; Huang, Xiaoyan; Wang, Ruilong; Lin, Zixu; Chen, Yong; Wang, Dengfei; Lin, Dejuan; Xu, Dunming

    2013-12-01

    The raw extracts of six vegetables (tomato, green bean, shallot, broccoli, ginger and carrot) were analyzed using gas chromatography-mass spectrometry (GC-MS) in full scan mode combined with NIST library search to confirm main matrix compounds. The effects of cleanup and adsorption mechanisms of primary secondary amine (PSA) , octadecylsilane (C18) and PSA + C18 on co-extractives were studied by the weight of evaporation residue for extracts before and after cleanup. The suitability of the two versions of QuEChERS method for sample preparation was evaluated for the extraction of 51 carbamate pesticides in the six vegetables. One of the QuEChERS methods was the original un-buffered method published in 2003, and the other was AOAC Official Method 2007.01 using acetate buffer. As a result, the best effects were obtained from using the combination of C18 and PSA for extract cleanup in vegetables. The acetate-buffered version was suitable for the determination of all pesticides except dioxacarb. Un-buffered QuEChERS method gave satisfactory results for determining dioxacarb. Based on these results, the suitable QuEChERS sample preparation method and liquid chromatography-positive electrospray ionization-tandem mass spectrometry under the optimized conditions were applied to determine the 51 carbamate pesticide residues in six vegetables. The analytes were quantified by matrix-matched standard solution. The recoveries at three levels of 10, 20 and 100 microg/kg spiked in six vegetables ranged from 58.4% to 126% with the relative standard deviations of 3.3%-26%. The limits of quantification (LOQ, S/N > or = 10) were 0.2-10 microg/kg except that the LOQs of cartap and thiofanox were 50 microg/kg. The method is highly efficient, sensitive and suitable for monitoring the 51 carbamate pesticide residues in vegetables.

  8. β-NMR sample optimization

    CERN Document Server

    Zakoucka, Eva

    2013-01-01

    During my summer student programme I was working on sample optimization for a new β-NMR project at the ISOLDE facility. The β-NMR technique is well-established in solid-state physics and just recently it is being introduced for applications in biochemistry and life sciences. The β-NMR collaboration will be applying for beam time to the INTC committee in September for three nuclei: Cu, Zn and Mg. Sample optimization for Mg was already performed last year during the summer student programme. Therefore sample optimization for Cu and Zn had to be completed as well for the project proposal. My part in the project was to perform thorough literature research on techniques studying Cu and Zn complexes in native conditions, search for relevant binding candidates for Cu and Zn applicable for ß-NMR and eventually evaluate selected binding candidates using UV-VIS spectrometry.

  9. Determination of total iodine in serum and urine samples by ion chromatography with pulsed amperometric detection - studies on analyte loss, optimization of sample preparation procedures, and validation of analytical method.

    Science.gov (United States)

    Błażewicz, Anna; Klatka, Maria; Dolliver, Wojciech; Kocjan, Ryszard

    2014-07-01

    A fast, accurate and precise ion chromatography method with pulsed amperometric detection was applied to evaluate a variety of parameters affecting the determination of total iodine in serum and urine of 81 subjects, including 56 obese and 25 healthy Polish children. The sample pretreatment methods were carried out in a closed system and with the assistance of microwaves. Both alkaline and acidic digestion procedures were developed and optimized to find the simplest combination of reagents and the appropriate parameters for digestion that would allow for the fastest, least time consuming and most cost-effective way of analysis. A good correlation between the certified and the measured concentrations was achieved. The best recoveries (96.8% for urine and 98.8% for serum samples) were achieved using 1ml of 25% tetramethylammonium hydroxide solution within 6min for 0.1ml of serum/urine samples. Using 0.5ml of 65% nitric acid solution the best recovery (95.3%) was obtained when 7min of effective digestion time was used. Freeze-thaw stability and long-term stability were checked. After 24 weeks 14.7% loss of iodine in urine, and 10.9% in serum samples occurred. For urine samples, better correlation (R(2)=0.9891) of various sample preparation procedures (alkaline digestion and application of OnGuard RP cartidges) was obtained. Significantly lower iodide content was found in samples taken from obese children. Serum iodine content in obese children was markedly variable in comparison with the healthy group, whereas the difference was less evident when urine samples were analyzed. The mean content in serum was 59.12±8.86μg/L, and in urine 98.26±25.93 for obese children when samples were prepared by the use of optimized alkaline digestion reinforced by microwaves. In healthy children the mean content in serum was 82.58±6.01μg/L, and in urine 145.76±31.44μg/L.

  10. Sample Preparation for Bioanalytical and Pharmaceutical Analysis.

    Science.gov (United States)

    Clark, Kevin D; Zhang, Cheng; Anderson, Jared L

    2016-12-06

    Biological and pharmaceutical samples represent formidable challenges in sample preparation that hold important consequences for bioanalysis and genotoxic impurity quantification. This Feature will emphasize significant advances toward the development of rapid, sensitive, and selective sample preparation methods.

  11. METALLOGRAPHIC SAMPLE PREPARATION STATION-CONSTRUCTIVE CONCEPT

    Directory of Open Access Journals (Sweden)

    AVRAM Florin Timotei

    2016-11-01

    Full Text Available In this paper we propose to present the issues involved in the case of the constructive conception of a station for metallographic sample preparation. This station is destined for laboratory work. The metallographic station is composed of a robot ABB IRB1600, a metallographic microscope, a gripping device, a manipulator, a laboratory grinding and polishing machine. The robot will be used for manipulation of the sample preparation and the manipulator take the sample preparation for processing.

  12. Final Report BW Sample Collection& Preparation Device

    Energy Technology Data Exchange (ETDEWEB)

    Koopman, R P; Belgrader, P; Meyer, G; Benett, W J; Richards, J B; Hadley, D R; Stratton, P L; Milanovich, F P

    2002-01-31

    The objective of this project was to develop the technique needed to prepare a field collected sample for laboratory analysis and build a portable integrated biological detection instrument with new miniaturized and automated sample purification capabilities. The device will prepare bacterial spores, bacterial vegetative cells, and viral particles for PCR amplification.

  13. Modular microfluidic system for biological sample preparation

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Klint A.; Mariella, Jr., Raymond P.; Bailey, Christopher G.; Ness, Kevin Dean

    2015-09-29

    A reconfigurable modular microfluidic system for preparation of a biological sample including a series of reconfigurable modules for automated sample preparation adapted to selectively include a) a microfluidic acoustic focusing filter module, b) a dielectrophoresis bacteria filter module, c) a dielectrophoresis virus filter module, d) an isotachophoresis nucleic acid filter module, e) a lyses module, and f) an isotachophoresis-based nucleic acid filter.

  14. Sample preparation in biological mass spectrometry

    CERN Document Server

    Ivanov, Alexander R

    2011-01-01

    The aim of this book is to provide the researcher with important sample preparation strategies in a wide variety of analyte molecules, specimens, methods, and biological applications requiring mass spectrometric analysis as a detection end-point.

  15. Optimization of chemical analysis methods for coal and fly ash. 1. Sampling, sample preparation and 'proximate' analysis. Optimalisatie analysemethoden voor steenkool en vliegas. 1. Monstername, monsterverwerking en 'proximate' analyse

    Energy Technology Data Exchange (ETDEWEB)

    Hissink, M.

    1983-01-01

    To support the experiments in the atmospheric fluid bed boiler (AFBB) many analyses of samples of fuel, additions and waste are needed. Therefore it was necessary to obtain experience with regard to sampling, sample preparation and analysis of these materials. For a correct interpretation of the experiments in the AFBB a knowledge of the accuracy of the results of these analyses is essential. This accuracy depends largely on the sampling method. As a guide for the methods to be used the instructions in the relevant ISO Standards have been followed usually. A description is given of the procedures for sampling and analysis as well as of the equipment used. The accuracy that can be expected for the various results of analysis has been established experimentally. It was found in general that the requirements were met.

  16. Optimization of chemical analysis methods for coal and fly ash. 1. Sampling, sample preparation and proximate analysis. Optimalisatie analysemethoden voor steenkool en vliegas. 1. Monstername monsterverwerking en 'proximate' analyse

    Energy Technology Data Exchange (ETDEWEB)

    Hissink, M.

    1983-01-01

    To support the experiments in the atmospheric fluid bed boiler (AFBB), many analyses of samples of fuel, additives and waste are needed. Therefore it was necessary to obtain experience with regard to sampling, sample preparation and analysis of these materials. For a correct interpretation of the experiments in the AFBB, a knowledge of accuracy of the results of these analyses is essential. This accuracy depends largely on the sampling method. As a guide for the methods to be used, the instructions in the relevant ISO Standards have been followed usually. A description is given of the procedures for sampling and analysis as well as of the equipment used. The accuracy that can be expected for the various results of analysis has been established experimentally. It was found in general that the requirements were met. (In Dutch)

  17. Optimal preparation of graph states

    CERN Document Server

    Cabello, Adan; Lopez-Tarrida, Antonio J; Portillo, Jose R

    2010-01-01

    We show how to prepare any graph state of up to 12 qubits with: (a) the minimum number of controlled-Z gates, and (b) the minimum preparation depth. We assume only one-qubit and controlled-Z gates. The method exploits the fact that any graph state belongs to an equivalence class under local Clifford operations. We extend up to 12 qubits the classification of graph states according to their entanglement properties, and identify each class using only a reduced set of invariants. For any state, we provide a circuit with both properties (a) and (b), if it does exist, or, if it does not, one circuit with property (a) and one with property (b), including the explicit one-qubit gates needed.

  18. Molecularly imprinted polymers for bioanalytical sample preparation.

    Science.gov (United States)

    Gama, Mariana Roberto; Bottoli, Carla Beatriz Grespan

    2017-02-01

    Molecularly imprinted polymers (MIP) are stable polymers with molecular recognition abilities, provided by the presence of a template during their synthesis, and are excellent materials with high selectivity for sample preparation in bioanalytical methods. This short review discusses aspects of MIP preparation and its applications as a sorbent material in pharmaceutical and biomedical analysis. MIP in different extraction configurations, including classical solid-phase extraction, solid-phase microextraction, magnetic molecularly imprinted solid-phase extraction, microextraction by packed sorbent and solid-phase extraction in pipette tips, are used to illustrate the good performance of this type of sorbent for sample preparation procedures of complex matrices, especially prior to bioanalytical approaches.

  19. Sampling scheme optimization from hyperspectral data

    NARCIS (Netherlands)

    Debba, P.

    2006-01-01

    This thesis presents statistical sampling scheme optimization for geo-environ-menta] purposes on the basis of hyperspectral data. It integrates derived products of the hyperspectral remote sensing data into individual sampling schemes. Five different issues are being dealt with.First, the optimized

  20. Sampling scheme optimization from hyperspectral data

    NARCIS (Netherlands)

    Debba, P.

    2006-01-01

    This thesis presents statistical sampling scheme optimization for geo-environ-menta] purposes on the basis of hyperspectral data. It integrates derived products of the hyperspectral remote sensing data into individual sampling schemes. Five different issues are being dealt with.First, the optimized

  1. Sample preparation for SEM of plant surfaces

    OpenAIRE

    A.K. Pathan; Bond, J.; R.E. Gaskin

    2010-01-01

    Plant tissues must be dehydrated for observation in most electron microscopes. Although a number of sample processing techniques have been developed for preserving plant tissues in their original form and structure, none of them are guaranteed artefact-free. The current paper reviews common scanning electron microscopy techniques and the sample preparation methods employed for visualisation of leaves under specific types of electron microscopes. Common artefacts introduced by specific techniq...

  2. Sample preparation method for scanning force microscopy

    CERN Document Server

    Jankov, I R; Szente, R N; Carreno, M N P; Swart, J W; Landers, R

    2001-01-01

    We present a method of sample preparation for studies of ion implantation on metal surfaces. The method, employing a mechanical mask, is specially adapted for samples analysed by Scanning Force Microscopy. It was successfully tested on polycrystalline copper substrates implanted with phosphorus ions at an acceleration voltage of 39 keV. The changes of the electrical properties of the surface were measured by Kelvin Probe Force Microscopy and the surface composition was analysed by Auger Electron Spectroscopy.

  3. Optimal Bowel Preparation for Video Capsule Endoscopy

    Directory of Open Access Journals (Sweden)

    Hyun Joo Song

    2016-01-01

    Full Text Available During video capsule endoscopy (VCE, several factors, such as air bubbles, food material in the small bowel, and delayed gastric and small bowel transit time, influence diagnostic yield, small bowel visualization quality, and cecal completion rate. Therefore, bowel preparation before VCE is as essential as bowel preparation before colonoscopy. To date, there have been many comparative studies, consensus, and guidelines regarding different kinds of bowel cleansing agents in bowel preparation for small bowel VCE. Presently, polyethylene glycol- (PEG- based regimens are given primary recommendation. Sodium picosulphate-based regimens are secondarily recommended, as their cleansing efficacy is less than that of PEG-based regimens. Sodium phosphate as well as complementary simethicone and prokinetics use are considered. In this paper, we reviewed previous studies regarding bowel preparation for small bowel VCE and suggested optimal bowel preparation of VCE.

  4. Designing optimal sampling schemes for field visits

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2008-10-01

    Full Text Available This is a presentation of a statistical method for deriving optimal spatial sampling schemes. The research focuses on ground verification of minerals derived from hyperspectral data. Spectral angle mapper (SAM) and spectral feature fitting (SFF...

  5. Field sampling scheme optimization using simulated annealing

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2010-10-01

    Full Text Available to derive optimal sampling schemes. 2. Hyperspectral remote sensing In the study of electro-magnetic physics, when energy in the form of light interacts with a material, part of the energy at certain wavelength is absorbed, transmitted, emitted... in order to derive optimal sampling schemes. 2. Hyperspectral remote sensing In the study of electro-magnetic physics, when energy in the form of light interacts with a material, part of the energy at certain wavelength is absorbed, transmitted, emitted...

  6. New materials for sample preparation techniques in bioanalysis.

    Science.gov (United States)

    Nazario, Carlos Eduardo Domingues; Fumes, Bruno Henrique; da Silva, Meire Ribeiro; Lanças, Fernando Mauro

    2017-02-01

    The analysis of biological samples is a complex and difficult task owing to two basic and complementary issues: the high complexity of most biological matrices and the need to determine minute quantities of active substances and contaminants in such complex sample. To succeed in this endeavor samples are usually subject to three steps of a comprehensive analytical methodological approach: sample preparation, analytes isolation (usually utilizing a chromatographic technique) and qualitative/quantitative analysis (usually with the aid of mass spectrometric tools). Owing to the complex nature of bio-samples, and the very low concentration of the target analytes to be determined, selective sample preparation techniques is mandatory in order to overcome the difficulties imposed by these two constraints. During the last decade new chemical synthesis approaches has been developed and optimized, such as sol-gel and molecularly imprinting technologies, allowing the preparation of novel materials for sample preparation including graphene and derivatives, magnetic materials, ionic liquids, molecularly imprinted polymers, and much more. In this contribution we will review these novel techniques and materials, as well as their application to the bioanalysis niche. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Optimized Sample Preparation for Metabolome Studies on Streptomyces avermitilis by GC-MS%基于GC-MS的阿维链霉菌代谢物组学研究方法的建立

    Institute of Scientific and Technical Information of China (English)

    郭刚; 唐丹; 田萍萍; 石秀峰; 曹鹏; 高强

    2015-01-01

    We established a method for preparing metabolome sample of Streptomyces avermitilis, including cell separation, washing, quenching, disruption and extraction conditions based on GC-MS analysis system, and applied it in the analysis of the metabolome of industrial strain 9-39 and wild type strain. The optimal conditions for sample preparation were as follows: separating cells by centrifugation, washing 3 times, quenching 5 minutes with liquid nitrogen, cell disruption with bead mill(3 cycles and 48 seconds per each cycle), and extraction of metabolites(chloroform∶ethanol∶water = 2∶2∶1). By using this optimized protocol, 59 differential compounds were identified and quantified, including amino acids, organic acids, fatty acids and saccharides. Our established method can be used to effectively analyze the Streptomyces avermitilis metabolites.%基于GC-MS分析平台,建立了阿维链霉菌代谢物组样品制备过程中的菌体分离、细胞清洗、细胞淬灭及代谢物提取条件,并对阿维菌素高产菌株和野生菌株胞内代谢物组进行了初步分析.采用"冷冻离心-细胞清洗(3次)-液氮淬灭(5 min)-珠磨破壁(3个循环,每个循环48 s)-提取(氯仿∶乙醇∶水= 2∶2∶1)"的方法,可以定性和定量检测阿维链霉菌胞内包括氨基酸、有机酸、脂肪酸、糖类等59种差异化合物.建立的方法能够有效地用于阿维链霉菌胞内代谢物的分析.

  8. Scanning Electron Microscopy Sample Preparation and Imaging.

    Science.gov (United States)

    Nguyen, Jenny Ngoc Tran; Harbison, Amanda M

    2017-01-01

    Scanning electron microscopes allow us to reach magnifications of 20-130,000× and resolve compositional and topographical images with intense detail. These images are created by bombarding a sample with electrons in a focused manner to generate a black and white image from the electrons that bounce off of the sample. The electrons are detected using positively charged detectors. Scanning electron microscopy permits three-dimensional imaging of desiccated specimens or wet cells and tissues by using variable pressure chambers. SEM ultrastructural analysis and intracellular imaging supplement light microscopy for molecular profiling of prokaryotes, plants, and mammals. This chapter demonstrates how to prepare and image samples that are (a) desiccated and conductive, (b) desiccated and nonconductive but coated with an electron conductive film using a gold sputter coater, and (c) wet and maintained in a hydrated state using a Deben Coolstage.

  9. HASE - The Helsinki adaptive sample preparation line

    Energy Technology Data Exchange (ETDEWEB)

    Palonen, V., E-mail: vesa.palonen@helsinki.fi [Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 (Finland); Pesonen, A. [Laboratory of Chronology, Finnish Museum of Natural History, P.O. Box 64, FI-00014 (Finland); Herranen, T.; Tikkanen, P. [Department of Physics, University of Helsinki, P.O. Box 43, FI-00014 (Finland); Oinonen, M. [Laboratory of Chronology, Finnish Museum of Natural History, P.O. Box 64, FI-00014 (Finland)

    2013-01-15

    We have designed and built an adaptive sample preparation line with separate modules for combustion, molecular sieve handling, CO{sub 2} gas cleaning, CO{sub 2} storage, and graphitization. The line is also connected to an elemental analyzer. Operation of the vacuum equipment, a flow controller, pressure sensors, ovens, and graphitization reactors are automated with a reliable NI-cRIO real-time system. Stepped combustion can be performed in two ovens at temperatures up to 900 Degree-Sign C. Depending on the application, CuO or O{sub 2}-flow combustion can be used. A flow controller is used to adjust the O{sub 2} flow and pressure during combustion. For environmental samples, a module for molecular sieve regeneration and sample desorption is attached to the line replacing the combustion module. In the storage module, CO{sub 2} samples can be stored behind a gas-tight diaphragm valve and either stored for later graphitization or taken for measurements with separate equipment (AMS gas ion source or a separate mass spectrometer). The graphitization module consists of four automated reactors, capable of graphitizing samples with masses from 3 mg down to 50 {mu}g.

  10. Analysis and optimization of weighted ensemble sampling

    CERN Document Server

    Aristoff, David

    2016-01-01

    We give a mathematical framework for weighted ensemble (WE) sampling, a binning and resampling technique for efficiently computing probabilities in molecular dynamics. We prove that WE sampling is unbiased in a very general setting that includes adaptive binning. We show that when WE is used for stationary calculations in tandem with a Markov state model (MSM), the MSM can be used to optimize the allocation of replicas in the bins.

  11. Sample preparation for SEM of plant surfaces

    Directory of Open Access Journals (Sweden)

    A.K. Pathan

    2010-01-01

    Full Text Available Plant tissues must be dehydrated for observation in most electron microscopes. Although a number of sample processing techniques have been developed for preserving plant tissues in their original form and structure, none of them are guaranteed artefact-free. The current paper reviews common scanning electron microscopy techniques and the sample preparation methods employed for visualisation of leaves under specific types of electron microscopes. Common artefacts introduced by specific techniques on different leaf types are discussed. Comparative examples are depicted from our lab using similar techniques; the pros and cons for specific techniques are discussed. New promising techniques and microscopes, which can alleviate some of the problems encountered in conventional methods of leaf sample processing and visualisation, are also discussed. It is concluded that the choice of technique for a specific leaf sample is dictated by the surface features that need to be preserved (such as trichomes, epidermal cells or wax microstructure, the resolution to be achieved, availability of the appropriate processing equipment and the technical capabilities of the available electron microscope.

  12. Technological Optimization of the Preparation of Imidacloprid

    Institute of Scientific and Technical Information of China (English)

    闻建平; 王长林

    2003-01-01

    In order to reduce the production cost of imidacloprid, the preparation technology for the direct combination of 2-chloro-5-chloromethylpyridine and 2-nitryliminoglyoxaline has been optimized in a 10L stirred tank reactor with a new solvent, butanone, and a new catalyst, benzyl triethyl-ammonium chloride (BTEAC), which was proved to be more profitable for the production of imidacloprid. Three main affecting factors (the reaction temperature, the molar ratio of BTEAC to 2-nitryliminoglyoxaline and the concentration of 2-nitryliminoglyoxaline) for the production of imidacloprid were investigated and the optimum operating conditions were found. Based on the above technological optimization, an industrial process for imidacloprid with a production capacity of 50 tons per year was put in operation using a 2500 L stirred tank reactor under the same operating conditions. Good yield and purity of imidacloprid was also obtained ia the industrial production.

  13. Optimizing Human Bile Preparation for Two-Dimensional Gel Electrophoresis

    Directory of Open Access Journals (Sweden)

    Hao-Tsai Cheng

    2016-01-01

    Full Text Available Aims. Bile is an important body fluid which assists in the digestion of fat and excretion of endogenous and exogenous compounds. In the present study, an improved sample preparation for human bile was established. Methods and Material. The method involved acetone precipitation followed by protein extraction using commercially available 2D Clean-Up kit. The effectiveness was evaluated by 2-dimensional electrophoresis (2DE profiling quality, including number of protein spots and spot distribution. Results. The total protein of bile fluid in benign biliary disorders was 0.797 ± 0.465 μg/μL. The sample preparation method using acetone precipitation first followed by 2D Clean-Up kit protein extraction resulted in better quality of 2DE gel images in terms of resolution as compared with other sample preparation methods. Using this protocol, we obtained approximately 558 protein spots on the gel images and with better protein spots presentation of haptoglobin, serum albumin, serotransferrin, and transthyretin. Conclusions. Protein samples of bile prepared using acetone precipitation followed by 2D Clean-Up kit exhibited high protein resolution and significant protein profile. This optimized protein preparation protocol can effectively concentrate bile proteins, remove abundant proteins and debris, and yield clear presentation of nonabundant proteins and its isoforms on 2-dimensional electrophoresis gel images.

  14. Thompson Sampling: An Optimal Finite Time Analysis

    CERN Document Server

    Kaufmann, Emilie; Munos, Rémi

    2012-01-01

    The question of the optimality of Thompson Sampling for solving the stochastic multi-armed bandit problem had been open since 1933. In this paper we answer it positively for the case of Bernoulli rewards by providing the first finite-time analysis that matches the asymptotic rate given in the Lai and Robbins lower bound for the cumulative regret. The proof is accompanied by a numerical comparison with other optimal policies, experiments that have been lacking in the literature until now for the Bernoulli case.

  15. FISHprep: A Novel Integrated Device for Metaphase FISH Sample Preparation

    DEFF Research Database (Denmark)

    Shah, Pranjul Jaykumar; Vedarethinam, Indumathi; Kwasny, Dorota;

    2011-01-01

    We present a novel integrated device for preparing metaphase chromosomes spread slides (FISHprep). The quality of cytogenetic analysis from patient samples greatly relies on the efficiency of sample pre-treatment and/or slide preparation. In cytogenetic slide preparation, cell cultures are routin...... with minimal handling for metaphase FISH slide preparation....

  16. Congener Production in Blood Samples During Preparation and Storage

    DEFF Research Database (Denmark)

    Felby, Søren; Nielsen, Erik

    1995-01-01

    Retsmedicin, congener production, preparation, head space GC, acetone, isobutanol, storage, blood samples, n-propanol, methanol, methylethylketone......Retsmedicin, congener production, preparation, head space GC, acetone, isobutanol, storage, blood samples, n-propanol, methanol, methylethylketone...

  17. Method of 14C Sample Preparation for AMS Measurement

    Directory of Open Access Journals (Sweden)

    YANG Xu-ran

    2015-02-01

    Full Text Available In order to carry out the application research of 14C by accelerator mass spectrometry (AMS, the principle of sample preparation were systematically studied and more attention was paid to improve the preparation process efficiently. The set of integrated system of sample preparation was built up on the research. The experimental results showed that the sample preparation scheme was able to meet the demand of AMS measurement.

  18. Optimization of Eosine Analyses in Water Samples

    Science.gov (United States)

    Kola, Liljana

    2010-01-01

    The fluorescence ability of Eosine enables its using as artificial tracer in the water system studies. The fluorescence intensity of fluorescent dyes in water samples depends on their physical and chemical properties, such as pH, temperature, presence of oxidants, etc. This paper presents the experience of the Center of Applied Nuclear Physics, Tirana, in this field. The problem is dealt with in relation to applying Eosine to trace and determine water movements within the karstic system and underground waters. We have used for this study the standard solutions of Eosine. The method we have elaborated to this purpose made it possible to optimize procedures we use to analyze samples for the presence of Eosine and measure its content, even in trace levels, by the means of a Perkin Elmer LS 55 Luminescence Spectrometer.

  19. Selecting Sample Preparation Workflows for Mass Spectrometry-Based Proteomic and Phosphoproteomic Analysis of Patient Samples with Acute Myeloid Leukemia

    Directory of Open Access Journals (Sweden)

    Maria Hernandez-Valladares

    2016-08-01

    Full Text Available Global mass spectrometry (MS-based proteomic and phosphoproteomic studies of acute myeloid leukemia (AML biomarkers represent a powerful strategy to identify and confirm proteins and their phosphorylated modifications that could be applied in diagnosis and prognosis, as a support for individual treatment regimens and selection of patients for bone marrow transplant. MS-based studies require optimal and reproducible workflows that allow a satisfactory coverage of the proteome and its modifications. Preparation of samples for global MS analysis is a crucial step and it usually requires method testing, tuning and optimization. Different proteomic workflows that have been used to prepare AML patient samples for global MS analysis usually include a standard protein in-solution digestion procedure with a urea-based lysis buffer. The enrichment of phosphopeptides from AML patient samples has previously been carried out either with immobilized metal affinity chromatography (IMAC or metal oxide affinity chromatography (MOAC. We have recently tested several methods of sample preparation for MS analysis of the AML proteome and phosphoproteome and introduced filter-aided sample preparation (FASP as a superior methodology for the sensitive and reproducible generation of peptides from patient samples. FASP-prepared peptides can be further fractionated or IMAC-enriched for proteome or phosphoproteome analyses. Herein, we will review both in-solution and FASP-based sample preparation workflows and encourage the use of the latter for the highest protein and phosphorylation coverage and reproducibility.

  20. FISH检测中标本切片预处理的优化方案的探索%Exploration on optimal approach for sample preparation in the process of FISH evaluation

    Institute of Scientific and Technical Information of China (English)

    温韵洁; 王晓丹; 黎相照; 杨芝洁; 孙宇超; 梁莉

    2014-01-01

    目的 探索荧光标记原位杂交技术(FISH)检测中标本切片预处理的优化方案.方法 收集300例明确诊断为肺结核的患者作为阳性对照组,300例健康志愿者(明确排除肺结核患者)作为阴性对照组.收集800例新收临床疑似肺结核患者作为研究组.收集该800例患者的肺活检标本以及同期的痰液标本,其中痰液进行涂片、结核杆菌分离培养、结核杆菌DNA荧光定量PCR检测以及FISH检测.采用两种石蜡包埋组织切片的预处理方案,方案1为自主设计的病理组织切片预处理方法,方案2为参考常用石蜡包埋组织切片预处理方法而设计的方案,比较两种方案对肺结核诊断阳性符合率和阴性符合率.结果 (1)方案1检测结核杆菌阳性符合率为98.7%,方案2检测结核杆菌阳性符合率为97.9%,两种方法阳性符合率差异无统计学意义(P=0.148).(2)方案1检测结核杆菌阴性符合率为97.8%,方案2检测结核杆菌阴性符合率为96.1%,两种方法阴性符合率差异有统计学意义(P=0.036).结论 采用FISH技术诊断肺结核具有较高的价值;与此同时,探索实验条件的优化能够进一步提高FISH诊断的阳性符合率和阴性符合率.%Objective To investigate the optimal approach for sample preparation in the process of FISH evaluation.Methods 300 patients diagnosed as pulmonary tuberculosis and 300 subjects with ruled-out pulmonary tuberculosis were enrolled and served as positive and negative groups respectively.800 suspected patients of pulmonary tuberculosis were also enrolled as research group and underwent sputum smear,culture for mycobacterium tuberculosis,real-time PCR and FISH evaluation.Two approaches of paraffin embedding for pulmonary tissues were used.The first one was self-created novel method and the second one was as traditional process.The sensitivity and specificity of these two methods were compared.Results (1) The positive rate of the first approach

  1. Homogeneous sample preparation of raw shrimp using dry ice.

    Science.gov (United States)

    Bunch, E A; Altwein, D M; Johnson, L E; Farley, J R; Hammersmith, A A

    1995-01-01

    Sample homogeneity is critical to accurate and reproducible analysis of trace residues in foods. A method of uniform sample preparation using dry ice is described for shrimp. Other sample preparation techniques for raw shrimp produce nonhomogeneous samples. Sample homogeneity was determined through analysis of chloramphenicol added to intact tiger or white shrimp prior to sample preparation. Simulated chloramphenicol residue levels were 50, 15, 10, and 5 ppb. No significant differences were noted when analyses of shrimp inoculated with chlor-amphenicol prior to sample preparation with dry ice were compared with analyses of shrimp spiked after grinding with dry ice. Grinding shrimp with dry ice produced samples with homogeneous chloramphenicol residues. This technique should be applicable to other tissues and vegetable products.

  2. Universal Sample Preparation Module for Molecular Analysis in Space Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lynntech proposes to develop and demonstrate the ability of a compact, light-weight, and automated universal sample preparation module (USPM) to process samples from...

  3. Preparation of protein samples for gel electrophoresis by sequential extraction

    Institute of Scientific and Technical Information of China (English)

    钟伯雄; 翁宏飚; 等

    2002-01-01

    Since preparation and solubilization of protein samples are crucial factors in proteome research,the authors established a sequential extraction technique to prepare protein samples from the body wall of the 5th instar larvae of silkworm.Bombyx mori.Two kinds of protein samples were obtained from the body wall using the method.Between the two types of samples only about 15% proteins were identical;the majority were different,indicating that more species of proteins could be obtained with the sequential extraction method;which will be useful for preparation of protein samples for proteome study.

  4. Preparation of protein samples for gel electrophoresis by sequential extraction

    Institute of Scientific and Technical Information of China (English)

    钟伯雄; 翁宏飚; 方维焕

    2002-01-01

    Since preparation and solubilization of protein samples are crucial factors in proteome research, the authors established a sequential extraction technique to prepare protein samples from the body wall of the 5th instar larvae of silkworm, Bombyx mori. Two kinds of protein samples were obtained from the body wall using the method. Between the two types of samples only about 15% proteins were identical; the majority were different, indicating that more species of proteins could be obtained with the sequential extraction method; which will be useful for preparation of protein samples for proteome study.

  5. Sample preparation issues in NMR-based plant metabolomics: optimisation for Vitis wood samples.

    Science.gov (United States)

    Halabalaki, Maria; Bertrand, Samuel; Stefanou, Anna; Gindro, Katia; Kostidis, Sarantos; Mikros, Emmanuel; Skaltsounis, Leandros A; Wolfender, Jean-Luc

    2014-01-01

    Nuclear magnetic resonance (NMR) is one of the most commonly used analytical techniques in plant metabolomics. Although this technique is very reproducible and simple to implement, sample preparation procedures have a great impact on the quality of the metabolomics data. Investigation of different sample preparation methods and establishment of an optimised protocol for untargeted NMR-based metabolomics of Vitis vinifera L. wood samples. Wood samples from two different cultivars of V. vinifera with well-defined phenotypes (Gamaret and 2091) were selected as reference materials. Different extraction solvents (successively, dichloromethane, methanol and water, as well as ethyl acetate and 7:3 methanol-water (v/v)) and deuterated solvents (methanol-d4, 7:3 chloroform-d-methanol-d4 (v/v), dimethylsulphoxide-d6 and 9:1 dimethylsulphoxide-d6-water-d2 (v/v)) were evaluated for NMR acquisition, and the spectral quality was compared. The optimal extract concentration, chemical shift stability and peak area repeatability were also investigated. Ethyl acetate was found to be the most satisfactory solvent for the extraction of all representative chemical classes of secondary metabolites in V. vinifera wood. The optimal concentration of dried extract was 10 mg/mL and 7:3 chloroform-d-methanol-d4 (v/v) was the most suitable solvent system for NMR analysis. Multivariate data analysis was used to estimate the biological variation and clustering between different cultivars. Close attention should be paid to all required procedures before NMR analysis, especially to the selection of an extraction solvent and a deuterated solvent system to perform an extensive metabolomic survey of the specific matrix. Copyright © 2014 John Wiley & Sons, Ltd.

  6. Alternative sample preparation methods for MALDI-MS

    Energy Technology Data Exchange (ETDEWEB)

    Hurst, G.B.; Buchanan, M.V. [Oak Ridge National Lab., TN (United States); Czartoski, T.J. [Kenyon College, Gambier, OH (United States)

    1994-12-31

    Since the introduction of matrix-assisted laser desorption and ionization (MALDI), sample preparation has been a limiting step in the applicability of this important technique for mass spectrometric analysis of biomolecules. A number of variations on the original sample preparation method for have been described. The {open_quotes}standard{close_quotes} method of MALDI sample preparation requires mixing a solution containing the analyte and a large excess of matrix, and allowing a small volume of this solution to dry on a probe tip before insertion into the mass spectrometer. The resulting sample can fairly inhomogeneous. As a result, the process of aiming the desorption laser at a favorable spot on the dried sample can be tedious and time-consuming. The authors are evaluating several approaches to MALDI sample preparation, with the goal of developing a faster and more reproducible method.

  7. Snow White Trench Prepared for Sample Collection

    Science.gov (United States)

    2008-01-01

    The informally named 'Snow White' trench is the source for the next sample to be acquired by NASA's Phoenix Mars Lander for analysis by the wet chemistry lab. The Surface Stereo Imager on Phoenix took this shadow-enhanced image of the trench, on the eastern end of Phoenix's work area, on Sol 103, or the 103rd day of the mission, Sept. 8, 2008. The trench is about 23 centimeters (9 inches) wide. The wet chemistry lab is part of Phoenix's Microscopy, Electrochemistry and Conductivity suite of instruments. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  8. Automated acoustic matrix deposition for MALDI sample preparation.

    Science.gov (United States)

    Aerni, Hans-Rudolf; Cornett, Dale S; Caprioli, Richard M

    2006-02-01

    Novel high-throughput sample preparation strategies for MALDI imaging mass spectrometry (IMS) and profiling are presented. An acoustic reagent multispotter was developed to provide improved reproducibility for depositing matrix onto a sample surface, for example, such as a tissue section. The unique design of the acoustic droplet ejector and its optimization for depositing matrix solution are discussed. Since it does not contain a capillary or nozzle for fluid ejection, issues with clogging of these orifices are avoided. Automated matrix deposition provides better control of conditions affecting protein extraction and matrix crystallization with the ability to deposit matrix accurately onto small surface features. For tissue sections, matrix spots of 180-200 microm in diameter were obtained and a procedure is described for generating coordinate files readable by a mass spectrometer to permit automated profile acquisition. Mass spectral quality and reproducibility was found to be better than that obtained with manual pipet spotting. The instrument can also deposit matrix spots in a dense array pattern so that, after analysis in a mass spectrometer, two-dimensional ion images may be constructed. Example ion images from a mouse brain are presented.

  9. Biodiversity optimal sampling: an algorithmic solution

    Directory of Open Access Journals (Sweden)

    Alessandro Ferrarini

    2012-03-01

    Full Text Available Biodiversity sampling is a very serious task. When biodiversity sampling is not representative of the biodiversity spatial pattern due to few data or uncorrected sampling point locations, successive analyses, models and simulations are inevitably biased. In this work, I propose a new solution to the problem of biodiversity sampling. The proposed approach is proficient for habitats, plant and animal species, in addition it is able to answer the two pivotal questions of biodiversity sampling: 1 how many sampling points and 2 where are the sampling points.

  10. A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-mechanical degradation mechanisms of poly (ethylene terephthalate)

    Energy Technology Data Exchange (ETDEWEB)

    Badia, J.D. [Instituto de Tecnologia de Materiales (ITM), Universidad Politecnica de Valencia Camino de Vera s/n, E-46022 Valencia (Spain); Stroemberg, E. [School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH - Royal Institute of Technology, Teknikringen 56-58, SE-10044 Stockholm (Sweden); Ribes-Greus, A. [Instituto de Tecnologia de Materiales (ITM), Universidad Politecnica de Valencia Camino de Vera s/n, E-46022 Valencia (Spain); Karlsson, S., E-mail: sigbritt.karlsson@his.se [School of Chemical Science and Engineering, Fibre and Polymer Technology, KTH - Royal Institute of Technology, Teknikringen 56-58, SE-10044 Stockholm (Sweden)

    2011-04-29

    The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measure of PET stated that the best combination of factors and levels was the following: matrix (dithranol), proportion analyte/matrix/cationization agent (1/15/1, V/V/V), and concentration of cationization agent (2 g L{sup -1}). In a second part, multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PET under mechanical recycling. The application of MALDI-TOF-MS showed that thermo-mechanical degradation primarily affected initially predominant cyclic species. Several degradation mechanisms were proposed, remarking intramolecular transesterification and hydrolysis. The ether links of the glycol unit in PET were shown to act as potential reaction sites, driving the main reactions of degradation.

  11. A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-mechanical degradation mechanisms of poly (ethylene terephthalate).

    Science.gov (United States)

    Badía, J D; Strömberg, E; Ribes-Greus, A; Karlsson, S

    2011-04-29

    The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individually or in combination, to the signal. The application of DoE for the improvement of the MALDI measure of PET stated that the best combination of factors and levels was the following: matrix (dithranol), proportion analyte/matrix/cationization agent (1/15/1, V/V/V), and concentration of cationization agent (2 g L(-1)). In a second part, multiple processing by means of successive injection cycles was used to simulate the thermo-mechanical degradation effects on the oligomeric distribution of PET under mechanical recycling. The application of MALDI-TOF-MS showed that thermo-mechanical degradation primarily affected initially predominant cyclic species. Several degradation mechanisms were proposed, remarking intramolecular transesterification and hydrolysis. The ether links of the glycol unit in PET were shown to act as potential reaction sites, driving the main reactions of degradation.

  12. Sample preparation for atomic spectroscopy: evolution and future trends

    Directory of Open Access Journals (Sweden)

    Oliveira Elisabeth de

    2003-01-01

    Full Text Available Sample preparation is the critical step of any analytical protocol, and involves steps from simple dilution to partial or total dissolution. The methods include dry or wet decomposition of the samples in open or closed systems, using thermal, ultrasonic or radiant (infrared, ultraviolet and microwaves energy. This review emphasizes sample preparation for atomic spectroscopy. The present and future tendencies for sample preparation also involve on-line dissolution, extraction of the analytes, speciation, solid sample and slurry analysis, in situ and in vivo procedures, etc. Nowadays the goals are the best result, in the shortest time, with minimum contamination, using the smallest quantities of reagents and samples, and having low residue and waste generation, as well as maintaining the integrity of the sample and the traceability of the results, to have quality and confidence in the measurements as the primordial attributes required by the community and by the users.

  13. γ-ray spectrometry results versus sample preparation methods

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    According to recommended conditions two bio-samples, tea leave and flour, are prepared with different methods: grounding into powder and reducing to ash, then they were analyzed by γ ray spectrometry. Remarkable difference was shown between the measured values of tea samples prepared with these different methods. One of the reasons may be that the method of reducing to ash makes some nuclides lost. Compared with the "non-destructive"method of grounding into powder, the method of reducing to ash can be much more sensible to the loss of some nuclides. The probable reasons are discussed for the varied influences of different preparation methods of tea leave and flour samples.

  14. Microscale sample preparation for PCR of C. difficile infected stool

    Science.gov (United States)

    Gillers, Sara; Atkinson, Christopher D.; Bartoo, Aaron C.; Mahalanabis, Madhumita; Boylan, Michael O.; Schwartz, John H.; Klapperich, Catherine; Singh, Satish K.

    2015-01-01

    In this paper, we describe the design of a microfluidic sample preparation chip for human stool samples infected with Clostridium difficile. We established a polymerase chain reaction able to distinguish C. difficile in the presence of several other organisms found in the normal intestinal flora. A protocol for on-chip extraction of nucleic acids from clinical samples is described that can detect target DNA down to 5.0×10−3 ng of template. The assay and sample preparation chip were then validated using known positive and known negative clinical samples. The work presented has potential applications in both the developed and developing world. PMID:19505511

  15. The effect of sample preparation and testing procedure on the ...

    African Journals Online (AJOL)

    The effect of sample preparation and testing procedure on the geotechnical ... of conventional laboratory testing, classification and evaluation systems, which were ... It should not be used to classify them based on conventional methods ...

  16. Preparation of Cytology Samples: Tricks of the Trade.

    Science.gov (United States)

    Moore, A Russell

    2017-01-01

    General principles and techniques for collection, preparation, and staining of cytologic samples in the general practice setting are reviewed. Tips for collection of digital images are also discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Modern methods of sample preparation for GC analysis

    OpenAIRE

    de Koning; Janssen, H.-G.; Brinkman, U.A.T.

    2009-01-01

    Today, a wide variety of techniques is available for the preparation of (semi-) solid, liquid and gaseous samples, prior to their instrumental analysis by means of capillary gas chromatography (GC) or, increasingly, comprehensive two-dimensional GC (GC × GC). In the past two decades, a large number of ‘modern’ sample-preparation techniques has been introduced, which have partly superseded their ‘classical’ counterparts. These novel techniques include off-line and on-line (sometimes semi- or f...

  18. Curatorial Works for the Hayabusa-Returned Sample and Preparation for Hayabusa2 Sample Curation

    Science.gov (United States)

    Yada, T.; Abe, M.; Okada, T.; Yurimoto, H.; Uesugi, M.; Karouji, Y.; Nakato, A.; Hashiguchi, M.; Nishimura, M.; Kumagai, K.; Matsui, S.; Yoshitake, M.; Sakamoto, K.; Nakano, Y.; Kawasaki, N.; Fujimoto, M.

    2016-08-01

    We continue describing Hayabusa-returned samples after its return in 2010. The number of described particles reaches around 650 and >540 of them are identified as Itokawa origin. We also start preparation for Hayabusa2 sample curation.

  19. Quantitating morphological changes in biological samples during scanning electron microscopy sample preparation with correlative super-resolution microscopy.

    Science.gov (United States)

    Zhang, Ying; Huang, Tao; Jorgens, Danielle M; Nickerson, Andrew; Lin, Li-Jung; Pelz, Joshua; Gray, Joe W; López, Claudia S; Nan, Xiaolin

    2017-01-01

    Sample preparation is critical to biological electron microscopy (EM), and there have been continuous efforts on optimizing the procedures to best preserve structures of interest in the sample. However, a quantitative characterization of the morphological changes associated with each step in EM sample preparation is currently lacking. Using correlative EM and superresolution microscopy (SRM), we have examined the effects of different drying methods as well as osmium tetroxide (OsO4) post-fixation on cell morphology during scanning electron microscopy (SEM) sample preparation. Here, SRM images of the sample acquired under hydrated conditions were used as a baseline for evaluating morphological changes as the sample went through SEM sample processing. We found that both chemical drying and critical point drying lead to a mild cellular boundary retraction of ~60 nm. Post-fixation by OsO4 causes at least 40 nm additional boundary retraction. We also found that coating coverslips with adhesion molecules such as fibronectin prior to cell plating helps reduce cell distortion from OsO4 post-fixation. These quantitative measurements offer useful information for identifying causes of cell distortions in SEM sample preparation and improving current procedures.

  20. Effect of sample preparation methods on photometric determination of the tellurium and cobalt content in the samples of copper concentrates

    Directory of Open Access Journals (Sweden)

    Viktoriya Butenko

    2016-03-01

    Full Text Available Methods of determination of cobalt and nickel in copper concentrates currently used in factory laboratories are very labor intensive and time consuming. The limiting stage of the analysis is preliminary chemical sample preparation. Carrying out the decomposition process of industrial samples with concentrated mineral acids in open systems does not allow to improve the metrological characteristics of the methods, for this reason improvement the methods of sample preparation is quite relevant and has a practical interest. The work was dedicated to the determination of the optimal conditions of preliminary chemical preparation of copper concentrate samples for the subsequent determination of cobalt and tellurium in the obtained solution using tellurium-spectrophotometric method. Decomposition of the samples was carried out by acid dissolving in individual mineral acids and their mixtures by heating in an open system as well as by using ultrasonification and microwave radiation in a closed system. In order to select the optimal conditions for the decomposition of the samples in a closed system the phase contact time and ultrasonic generator’s power were varied. Intensification of the processes of decomposition of copper concentrates with nitric acid (1:1, ultrasound and microwave radiation allowed to transfer quantitatively cobalt and tellurium into solution spending 20 and 30 min respectively. This reduced the amount of reactants used and improved the accuracy of determination by running the process in strictly identical conditions.

  1. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...

  2. Sample Preparation (SS): SE51_SS01 [Metabolonote[Archive

    Lifescience Database Archive (English)

    Full Text Available e Master NEO, BMS, Tokyo, Japan), and the seed powder was extracted with 1 mL of extraction buffer (0.1% HCO...trifugation (4 ℃, 10,000 rpm, 5 min), the sample tubes were subjected to sample preparation (buffer transfer

  3. Optimizing sampling approaches along ecological gradients

    DEFF Research Database (Denmark)

    Schweiger, Andreas; Irl, Severin D. H.; Steinbauer, Manuel

    2016-01-01

    1. Natural scientists and especially ecologists use manipulative experiments or field observations along gradients to differentiate patterns driven by processes from those caused by random noise. A well-conceived sampling design is essential for identifying, analysing and reporting underlying...... patterns in a statistically solid and reproducible manner, given the normal restrictions in labour, time and money. However, a technical guideline about an adequate sampling design to maximize prediction success under restricted resources is lacking. This study aims at developing such a solid...... and reproducible guideline for sampling along gradients in all fields of ecology and science in general. 2. We conducted simulations with artificial data for five common response types known in ecology, each represented by a simple function (no response, linear, exponential, symmetric unimodal and asymmetric...

  4. Optimization and Sampling for NLP from a Unified Viewpoint

    NARCIS (Netherlands)

    Dymetman, M.; Bouchard, G.; Carter, S.; Bhattacharyya, B.; Ekbal, A.; Saha, S.; Johnson, M.; Molla-Aliod, D.; Dras, M.

    2012-01-01

    The OS* algorithm is a unified approach to exact optimization and sampling, based on incremental refinements of a functional upper bound, which combines ideas of adaptive rejection sampling and of A* optimization search. We first give a detailed description of OS*. We then explain how it can be

  5. Microfluidic Sample Preparation Methods for the Analysis of Milk Contaminants

    Directory of Open Access Journals (Sweden)

    Andrea Adami

    2016-01-01

    Full Text Available In systems for food analysis, one of the major challenges is related to the quantification of specific species into the complex chemical and physical composition of foods, that is, the effect of “matrix”; the sample preparation is often the key to a successful application of biosensors to real measurements but little attention is traditionally paid to such aspects in sensor research. In this critical review, we discuss several microfluidic concepts that can play a significant role in sample preparation, highlighting the importance of sample preparation for efficient detection of food contamination. As a case study, we focus on the challenges related to the detection of aflatoxin M1 in milk and we evaluate possible approaches based on inertial microfluidics, electrophoresis, and acoustic separation, compared with traditional laboratory and industrial methods for phase separation as a baseline of thrust and well-established techniques.

  6. Fluidics platform and method for sample preparation and analysis

    Energy Technology Data Exchange (ETDEWEB)

    Benner, W. Henry; Dzenitis, John M.; Bennet, William J.; Baker, Brian R.

    2014-08-19

    Herein provided are fluidics platform and method for sample preparation and analysis. The fluidics platform is capable of analyzing DNA from blood samples using amplification assays such as polymerase-chain-reaction assays and loop-mediated-isothermal-amplification assays. The fluidics platform can also be used for other types of assays and analyzes. In some embodiments, a sample in a sealed tube can be inserted directly. The following isolation, detection, and analyzes can be performed without a user's intervention. The disclosed platform may also comprises a sample preparation system with a magnetic actuator, a heater, and an air-drying mechanism, and fluid manipulation processes for extraction, washing, elution, assay assembly, assay detection, and cleaning after reactions and between samples.

  7. Preparation and investigation of bulk and thin film samples of strontium ferrite

    Directory of Open Access Journals (Sweden)

    A Poorbafrani

    2008-07-01

    Full Text Available   In this article, bulk and thin film samples of strontium ferrite have been studied. Due to the high electrical resistivity in strontium ferrite, energy loss due to eddy currents reduces and because of this, it can be used in high frequency magnetic circuits. On the other hand, strontium ferrite has attracted much attention as a permanent magnet. At first, we study the preparation process of bulk samples of strontium ferrite by a solid state reaction technique. In preparation of samples, to optimize the magnetic properties, we have used the stoichiometry factor (n = Fe2O3 / SrO of 5.25. In addition, we have used additives such as CaO and SiO2 to control grain growth. The samples have been prepared in two series: Isotropic and Anisotropic. For preparation of anisotropic samples, the magnetic field of 1T has been used for orientation of the grains during the press. Then, X-ray diffraction, Scanning Electron Microscopy (SEM, EDAX analysis and Magnetometer, was used for analyzing and comparing of structural and magnetic properties of isotropic and anisotropic samples. The results indicate that, due to the applied magnetic field, the structural and Magnetic properties of anisotropic samples improved efficiently because of the orientation of the grains during the press. In the next stage, we used bulk samples to prepare strontium ferrite thin films by Pulsed Laser Deposition technique (PLD. The Si (111 substrate has been used to prepare the thin films. Then we have studied the microstructure of thin films by X-ray diffraction, SEM and EDAX analysis. These studies on different samples show that for the preparation of crystalline phase of strontium ferrite thin films, the substrate temperature must be higher than 800˚C. The optimum conditions for preparation of strontium, ferrite thin films have been achieved on the substrate temperature of 840˚C and oxygen pressure of 75 mtorr.

  8. The cognitive mechanisms of optimal sampling.

    Science.gov (United States)

    Lea, Stephen E G; McLaren, Ian P L; Dow, Susan M; Graft, Donald A

    2012-02-01

    How can animals learn the prey densities available in an environment that changes unpredictably from day to day, and how much effort should they devote to doing so, rather than exploiting what they already know? Using a two-armed bandit situation, we simulated several processes that might explain the trade-off between exploring and exploiting. They included an optimising model, dynamic backward sampling; a dynamic version of the matching law; the Rescorla-Wagner model; a neural network model; and ɛ-greedy and rule of thumb models derived from the study of reinforcement learning in artificial intelligence. Under conditions like those used in published studies of birds' performance under two-armed bandit conditions, all models usually identified the more profitable source of reward, and did so more quickly when the reward probability differential was greater. Only the dynamic programming model switched from exploring to exploiting more quickly when available time in the situation was less. With sessions of equal length presented in blocks, a session-length effect was induced in some of the models by allowing motivational, but not memory, carry-over from one session to the next. The rule of thumb model was the most successful overall, though the neural network model also performed better than the remaining models. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Sample preparation for quantitation of tritium by accelerator mass spectrometry.

    Science.gov (United States)

    Chiarappa-Zucca, Marina L; Dingley, Karen H; Roberts, Mark L; Velsko, Carol A; Love, Adam H

    2002-12-15

    The capability to prepare samples accurately and reproducibly for analysis of tritium (3H) content by accelerator mass spectrometry (AMS) greatly facilitates isotopic tracer studies in which attomole levels of 3H can be measured in milligram-sized samples. A method has been developed to convert the hydrogen of organic samples to a solid, titanium hydride, which can be analyzed by AMS. Using a two-step process, the sample is first oxidized to carbon dioxide and water. In the second step, the water is transferred within a heated manifold into a quartz tube, reduced to hydrogen gas using zinc, and reacted with titanium powder. The 3H/1H ratio of the titanium hydride is measured by AMS and normalized to standards whose ratios were determined by decay counting to calculate the amount of 3H in the original sample. Water, organic compounds, and biological samples with 3H activities measured by liquid scintillation counting were utilized to develop and validate the method. The 3H/1H ratios were quantified in samples that spanned 5 orders of magnitude, from 10(-10) to 10(-15), with a detection limit of 3.0 x 10(-15), which is equivalent to 0.02 dpm tritium/mg of material. Samples smaller than 2 mg were analyzed following addition of 2 mg of a tritium-free-hydrogen carrier. Preparation of organic standards containing both 14C and 3H in 2-mg organic samples demonstrated that this sample preparation methodology can also be applied to quantify both of these isotopes from a single sample.

  10. Basic tree-ring sample preparation techniques for aging aspen

    Science.gov (United States)

    Lance A. Asherin; Stephen A. Mata

    2001-01-01

    Aspen is notoriously difficult to age because of its light-colored wood and faint annual growth rings. Careful preparation and processing of aspen ring samples can overcome these problems, yield accurate age and growth estimates, and concisely date disturbance events present in the tree-ring record. Proper collection of aspen wood is essential in obtaining usable ring...

  11. Expanding the application of the tablet processing workstation to support the sample preparation of oral suspensions.

    Science.gov (United States)

    Opio, Alex Manuel; Nickerson, Beverly; Xue, Gang; Warzeka, John; Norris, Ken

    2011-06-01

    Sample preparation is the most time-consuming part of the analytical method for powder for oral suspension (POS) assay, purity, and preservative analysis, as this involves multiple dilution and filtration steps. The Tablet Processing Workstation (TPW) was used to automate the sample preparation of a POS formulation. Although the TPW is typically used to automate the preparation of solid oral dosage forms and powders, it contains all of the necessary components to perform POS sample preparation. The TPW exhibited acceptable repeatability in testing 3 lots using 10 replicate preparations per lot. Acceptable linearity of the drug and preservative in the presence of excipients was demonstrated over the range corresponding to 50-150% of intent. Accuracy showed suitable recoveries for all points evaluated. TPW results were shown to correlate to results obtained with the manual method. The TPW method was used to prepare samples in support of manufacturing scale-up efforts. With the efficiencies gained using the TPW, it was possible to analyze a large number of samples generated during process development activities for the POS formulation with minimal human intervention. The extensive data enabled trending of the manufacturing development runs and helped to identify optimization strategies for the process.

  12. Optimizing sparse sampling for 2D electronic spectroscopy

    Science.gov (United States)

    Roeding, Sebastian; Klimovich, Nikita; Brixner, Tobias

    2017-02-01

    We present a new data acquisition concept using optimized non-uniform sampling and compressed sensing reconstruction in order to substantially decrease the acquisition times in action-based multidimensional electronic spectroscopy. For this we acquire a regularly sampled reference data set at a fixed population time and use a genetic algorithm to optimize a reduced non-uniform sampling pattern. We then apply the optimal sampling for data acquisition at all other population times. Furthermore, we show how to transform two-dimensional (2D) spectra into a joint 4D time-frequency von Neumann representation. This leads to increased sparsity compared to the Fourier domain and to improved reconstruction. We demonstrate this approach by recovering transient dynamics in the 2D spectrum of a cresyl violet sample using just 25% of the originally sampled data points.

  13. Using remote sensing images to design optimal field sampling schemes

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2008-08-01

    Full Text Available At this presentation, the author discussed a statistical method for deriving optimal spatial sampling schemes. First I focus on ground verification of minerals derived from hyperspectral data. Spectral angle mapper (SAM) and spectral feature fitting...

  14. Optimal sampling schemes for vegetation and geological field visits

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2012-07-01

    Full Text Available The presentation made to Wits Statistics Department was on common classification methods used in the field of remote sensing, and the use of remote sensing to design optimal sampling schemes for field visits with applications in vegetation...

  15. Applications of Liquid-Phase Microextraction in the Sample Preparation of Environmental Solid Samples

    Directory of Open Access Journals (Sweden)

    Helena Prosen

    2014-05-01

    Full Text Available Solvent extraction remains one of the fundamental sample preparation techniques in the analysis of environmental solid samples, but organic solvents are toxic and environmentally harmful, therefore one of the possible greening directions is its miniaturization. The present review covers the relevant research from the field of application of microextraction to the sample preparation of environmental solid samples (soil, sediments, sewage sludge, dust etc. published in the last decade. Several innovative liquid-phase microextraction (LPME techniques that have emerged recently have also been applied as an aid in sample preparation of these samples: single-drop microextraction (SDME, hollow fiber-liquid phase microextraction (HF-LPME, dispersive liquid-liquid microextraction (DLLME. Besides the common organic solvents, surfactants and ionic liquids are also used. However, these techniques have to be combined with another technique to release the analytes from the solid sample into an aqueous solution. In the present review, the published methods were categorized into three groups: LPME in combination with a conventional solvent extraction; LPME in combination with an environmentally friendly extraction; LPME without previous extraction. The applicability of these approaches to the sample preparation for the determination of pollutants in solid environmental samples is discussed, with emphasis on their strengths, weak points and environmental impact.

  16. Applications of reversible covalent chemistry in analytical sample preparation.

    Science.gov (United States)

    Siegel, David

    2012-12-07

    Reversible covalent chemistry (RCC) adds another dimension to commonly used sample preparation techniques like solid-phase extraction (SPE), solid-phase microextraction (SPME), molecular imprinted polymers (MIPs) or immuno-affinity cleanup (IAC): chemical selectivity. By selecting analytes according to their covalent reactivity, sample complexity can be reduced significantly, resulting in enhanced analytical performance for low-abundance target analytes. This review gives a comprehensive overview of the applications of RCC in analytical sample preparation. The major reactions covered include reversible boronic ester formation, thiol-disulfide exchange and reversible hydrazone formation, targeting analyte groups like diols (sugars, glycoproteins and glycopeptides, catechols), thiols (cysteinyl-proteins and cysteinyl-peptides) and carbonyls (carbonylated proteins, mycotoxins). Their applications range from low abundance proteomics to reversible protein/peptide labelling to antibody chromatography to quantitative and qualitative food analysis. In discussing the potential of RCC, a special focus is on the conditions and restrictions of the utilized reaction chemistry.

  17. Smart AMS : Optimizing the measurement procedure for small radiocarbon samples

    NARCIS (Netherlands)

    Vries de, Hendrik

    2010-01-01

    Abstract In order to improve the measurement efficiency of radiocarbon samples, particularly small samples (< 300 µg C), the measurement procedure was optimized using Smart AMS, which is the name of the new control system of the AMS. The system gives the

  18. Wrapped Progressive Sampling Search for Optimizing Learning Algorithm Parameters

    NARCIS (Netherlands)

    Bosch, Antal van den

    2005-01-01

    We present a heuristic meta-learning search method for finding a set of optimized algorithmic parameters for a range of machine learning algo- rithms. The method, wrapped progressive sampling, is a combination of classifier wrapping and progressive sampling of training data. A series of experiments

  19. Wrapped Progressive Sampling Search for Optimizing Learning Algorithm Parameters

    NARCIS (Netherlands)

    Bosch, Antal van den

    2005-01-01

    We present a heuristic meta-learning search method for finding a set of optimized algorithmic parameters for a range of machine learning algo- rithms. The method, wrapped progressive sampling, is a combination of classifier wrapping and progressive sampling of training data. A series of experiments

  20. On Optimal, Minimal BRDF Sampling for Reflectance Acquisition

    DEFF Research Database (Denmark)

    Nielsen, Jannik Boll; Jensen, Henrik Wann; Ramamoorthi, Ravi

    2015-01-01

    , such as the MERL BRDF database. We optimize for the best sampling directions, and explicitly provide the optimal set of incident and outgoing directions in the Rusinkiewicz parameterization for n = {1, 2, 5, 10, 20} samples. Based on the principal components, we describe a method for accurately reconstructing BRDF...... demonstrate how this method can be used to find optimal sampling directions when imaging a sphere of a homogeneous material; in this case, only two images are often adequate for high accuracy.......The bidirectional reflectance distribution function (BRDF) is critical for rendering, and accurate material representation requires data-driven reflectance models. However, isotropic BRDFs are 3D functions, and measuring the reflectance of a flat sample can require a million incident and outgoing...

  1. Optimal sampling strategies for detecting zoonotic disease epidemics.

    Science.gov (United States)

    Ferguson, Jake M; Langebrake, Jessica B; Cannataro, Vincent L; Garcia, Andres J; Hamman, Elizabeth A; Martcheva, Maia; Osenberg, Craig W

    2014-06-01

    The early detection of disease epidemics reduces the chance of successful introductions into new locales, minimizes the number of infections, and reduces the financial impact. We develop a framework to determine the optimal sampling strategy for disease detection in zoonotic host-vector epidemiological systems when a disease goes from below detectable levels to an epidemic. We find that if the time of disease introduction is known then the optimal sampling strategy can switch abruptly between sampling only from the vector population to sampling only from the host population. We also construct time-independent optimal sampling strategies when conducting periodic sampling that can involve sampling both the host and the vector populations simultaneously. Both time-dependent and -independent solutions can be useful for sampling design, depending on whether the time of introduction of the disease is known or not. We illustrate the approach with West Nile virus, a globally-spreading zoonotic arbovirus. Though our analytical results are based on a linearization of the dynamical systems, the sampling rules appear robust over a wide range of parameter space when compared to nonlinear simulation models. Our results suggest some simple rules that can be used by practitioners when developing surveillance programs. These rules require knowledge of transition rates between epidemiological compartments, which population was initially infected, and of the cost per sample for serological tests.

  2. Preparation of SELEX Samples for Next-Generation Sequencing.

    Science.gov (United States)

    Tolle, Fabian; Mayer, Günter

    2016-01-01

    Fuelled by massive whole genome sequencing projects such as the human genome project, enormous technological advancements and therefore tremendous price drops could be achieved, rendering next-generation sequencing very attractive for deep sequencing of SELEX libraries. Herein we describe the preparation of SELEX samples for Illumina sequencing, based on the already established whole genome sequencing workflow. We describe the addition of barcode sequences for multiplexing and the adapter ligation, avoiding associated pitfalls.

  3. Recent advances in sample preparation techniques for effective bioanalytical methods.

    Science.gov (United States)

    Kole, Prashant Laxman; Venkatesh, Gantala; Kotecha, Jignesh; Sheshala, Ravi

    2011-01-01

    This paper reviews the recent developments in bioanalysis sample preparation techniques and gives an update on basic principles, theory, applications and possibilities for automation, and a comparative discussion on the advantages and limitation of each technique. Conventional liquid-liquid extraction (LLE), protein precipitation (PP) and solid-phase extraction (SPE) techniques are now been considered as methods of the past. The last decade has witnessed a rapid development of novel sample preparation techniques in bioanalysis. Developments in SPE techniques such as selective sorbents and in the overall approach to SPE, such as hybrid SPE and molecularly imprinted polymer SPE, have been addressed. Considerable literature has been published in the area of solid-phase micro-extraction and its different versions, e.g. stir bar sorptive extraction, and their application in the development of selective and sensitive bioanalytical methods. Techniques such as dispersive solid-phase extraction, disposable pipette extraction and micro-extraction by packed sorbent offer a variety of extraction phases and provide unique advantages to bioanalytical methods. On-line SPE utilizing column-switching techniques is rapidly gaining acceptance in bioanalytical applications. PP sample preparation techniques such as PP filter plates/tubes offer many advantages like removal of phospholipids and proteins in plasma/serum. Newer approaches to conventional LLE techniques (salting-out LLE) are also covered in this review article.

  4. An Optimization-Based Sampling Scheme for Phylogenetic Trees

    Science.gov (United States)

    Misra, Navodit; Blelloch, Guy; Ravi, R.; Schwartz, Russell

    Much modern work in phylogenetics depends on statistical sampling approaches to phylogeny construction to estimate probability distributions of possible trees for any given input data set. Our theoretical understanding of sampling approaches to phylogenetics remains far less developed than that for optimization approaches, however, particularly with regard to the number of sampling steps needed to produce accurate samples of tree partition functions. Despite the many advantages in principle of being able to sample trees from sophisticated probabilistic models, we have little theoretical basis for concluding that the prevailing sampling approaches do in fact yield accurate samples from those models within realistic numbers of steps. We propose a novel approach to phylogenetic sampling intended to be both efficient in practice and more amenable to theoretical analysis than the prevailing methods. The method depends on replacing the standard tree rearrangement moves with an alternative Markov model in which one solves a theoretically hard but practically tractable optimization problem on each step of sampling. The resulting method can be applied to a broad range of standard probability models, yielding practical algorithms for efficient sampling and rigorous proofs of accurate sampling for some important special cases. We demonstrate the efficiency and versatility of the method in an analysis of uncertainty in tree inference over varying input sizes. In addition to providing a new practical method for phylogenetic sampling, the technique is likely to prove applicable to many similar problems involving sampling over combinatorial objects weighted by a likelihood model.

  5. Optimization of technological parameters for preparation of lycopene microcapsules

    OpenAIRE

    Guo, Hui; Huang, Ying; Qian, Jun-qing; Gong, Qiu-yi; Tang, Ying

    2012-01-01

    Lycopene belongs to the carotenoid family with high degree of unsaturation and all-trans form. Lycopene is easy to isomerize and auto oxide by heat, light, oxygen and different food matrices. With an increasing understanding of the health benefit of lycopene, to enhance stability and bioavailability of lycopene, ultrasonic emulsification was used to prepare lycopene microcapsules in this article. The results optimized by response surface methodology (RSM) for microcapsules consisted of four m...

  6. Localized Multiple Kernel Learning Via Sample-Wise Alternating Optimization.

    Science.gov (United States)

    Han, Yina; Yang, Kunde; Ma, Yuanliang; Liu, Guizhong

    2014-01-01

    Our objective is to train support vector machines (SVM)-based localized multiple kernel learning (LMKL), using the alternating optimization between the standard SVM solvers with the local combination of base kernels and the sample-specific kernel weights. The advantage of alternating optimization developed from the state-of-the-art MKL is the SVM-tied overall complexity and the simultaneous optimization on both the kernel weights and the classifier. Unfortunately, in LMKL, the sample-specific character makes the updating of kernel weights a difficult quadratic nonconvex problem. In this paper, starting from a new primal-dual equivalence, the canonical objective on which state-of-the-art methods are based is first decomposed into an ensemble of objectives corresponding to each sample, namely, sample-wise objectives. Then, the associated sample-wise alternating optimization method is conducted, in which the localized kernel weights can be independently obtained by solving their exclusive sample-wise objectives, either linear programming (for l1-norm) or with closed-form solutions (for lp-norm). At test time, the learnt kernel weights for the training data are deployed based on the nearest-neighbor rule. Hence, to guarantee their generality among the test part, we introduce the neighborhood information and incorporate it into the empirical loss when deriving the sample-wise objectives. Extensive experiments on four benchmark machine learning datasets and two real-world computer vision datasets demonstrate the effectiveness and efficiency of the proposed algorithm.

  7. Using remotely-sensed data for optimal field sampling

    CSIR Research Space (South Africa)

    Debba, Pravesh

    2008-09-01

    Full Text Available to carry out a fieldwork sample is an important issue as it avoids subjective judgement and can save on time and costs in the field. STATISTICAL SAMPLING, USING DATA OBTAINED FROM REMOTE SENSING, FINDS APPLICATION IN A VARIETY OF FIELDS... M B E R 2 0 0 8 15 USING REMOTELY- SENSED DATA FOR OPTIMAL FIELD SAMPLING BY DR PRAVESH DEBBA STATISTICS IS THE SCIENCE pertaining to the collection, summary, analysis, interpretation and presentation of data. It is often impractical...

  8. Optimization of sampling and counting times for gamma-ray spectrometric measurements of short-lived gamma-ray emitters in aqueous samples.

    Science.gov (United States)

    Korun, M

    2008-01-01

    A method to determine the optimal sampling and counting regimes for water monitoring is presented. It is assumed that samples are collected at a constant rate. The collection time is followed by a sample preparation time that is proportional to the sample quantity collected, and then by the counting time. In the optimal regime these times are chosen in such a way that the minimum detectable concentration is the lowest. Two cases are presented: the case when the background originates from the spectrometer background, which is constant in time and independent of the sample properties, and the case when the background originates from the radioactivity present in the sample.

  9. Optimal linear shrinkage corrections of sample LMMSE and MVDR estimators

    OpenAIRE

    2012-01-01

    La proposició d'estimadors shrinkage òptims que corregeixen la degradació dels mètodes sample LMMSE i sample MUDR en el règim on el número de mostres és petit en comparació a la dimensió de les observacions. [ANGLÈS] This master thesis proposes optimal shrinkage estimators that counteract the performance degradation of the sample LMMSE and sample MVDR methods in the regime where the sample size is small compared to the observation dimension. [CASTELLÀ] Esta máster tesis propone estimado...

  10. Radiocarbon accelerator mass spectrometry (AMS) sample preparation laboratory in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Macario, Kita D.; Gomes, Paulo R. S.; Anjos, Roberto M. dos; Linares, Roberto; Queiroz, Eduardo; Oliveira, Fabiana M. de; Cardozo, Laio [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil); Carvalho, Carla R.A. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

    2011-07-01

    Full text: For decades Accelerator Mass Spectrometry has been widely used for radiocarbon measurements all over the world with application in several fields of science from archaeology to geosciences. This technique provides ultrasensitive analysis of reduced size samples or even specific compounds since sample atoms are accelerated to high energies and measured using nuclear particle detectors. Sample preparation is extremely important for accurate radiocarbon measurement and includes chemical pre-treatment to remove all possible contaminants. For beam extraction in the accelerator ion source, samples are usually converted to graphite. In this work we report a new radiocarbon sample preparation facility installed at the Physics Institute of Universidade Federal Fluminense (UFF), in Brazil. At the Nuclear Chronology Laboratory (LACRON) samples are chemically treated and converted to carbon dioxide by hydrolysis or combustion. A stainless steel based vacuum line was constructed for carbon dioxide separation and graphitization is performed in sealed quartz tubes in a muffle oven. Successful graphite production is important to provide stable beam currents and to minimize isotopic fractionation. Performance tests for graphite production are currently under way and isotopic analysis will soon be possible with the acquisition of a Single Stage AMS System by our group. The Single Stage Accelerator produced by National Electrostatic Corporation is a 250 kV air insulated accelerator especially constructed to measure the amount of {sup 14}C in small modern graphite samples to a precision of 0.3 % or better. With the installation of such equipment in the first half of 2012, UFF will be ready to perform the 14C -AMS technique. (author)

  11. Optimization of enrichment processes of pentachlorophenol (PCP) from water samples

    Institute of Scientific and Technical Information of China (English)

    LI Ping; LIU Jun-xin

    2004-01-01

    The method of enriching PCP (pentachlorophenol) from aquatic environment by solid phase extraction (SPE) was studied.Several factors affecting the recoveries of PCP, including sample pH, eluting solvent, eluting volume and flow rate of water sample, were optimized by orthogonal array design(OAD). The optimized results were sample pH 4; eluting solvent, 100% methanol; eluting solvent volume, 2 mi and flow rate of water sample, 4 mi/min. A comparison is made between SPE and liquid-liquid extraction(LLE) method. The recoveries of PCP were in the range of 87.6 % 133.6 % and 79 %- 120.3 % for S PE and LLE, respectively. Important advantages of the SPE compared with the LLE include the short extraction time and reduced consumption of organic solvents. SPE can replace LLE for isolating and concentrating PCP from water samples.

  12. Gel-aided sample preparation (GASP)--a simplified method for gel-assisted proteomic sample generation from protein extracts and intact cells.

    Science.gov (United States)

    Fischer, Roman; Kessler, Benedikt M

    2015-04-01

    We describe a "gel-assisted" proteomic sample preparation method for MS analysis. Solubilized protein extracts or intact cells are copolymerized with acrylamide, facilitating denaturation, reduction, quantitative cysteine alkylation, and matrix formation. Gel-aided sample preparation has been optimized to be highly flexible, scalable, and to allow reproducible sample generation from 50 cells to milligrams of protein extracts. This methodology is fast, sensitive, easy-to-use on a wide range of sample types, and accessible to nonspecialists. © 2014 The Authors. PROTEOMICS published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Stability of optimal-wave-front-sample coupling under sample translation and rotation

    CERN Document Server

    Anderson, Benjamin R; Eilers, Hergen

    2015-01-01

    The method of wavefront shaping to control optical properties of opaque media is a promising technique for authentication applications. One of the main challenges of this technique is the sensitivity of the wavefront-sample coupling to translation and/or rotation. To better understand how translation and rotation affect the wavefront- sample coupling we perform experiments in which we first optimize reflection from an opaque surface--to obtain an optimal wavefront--and then translate or rotate the surface and measure the new reflected intensity pattern. By using the correlation between the optimized and translated or rotated patterns we determine how sensitive the wavefront-sample coupling is. These experiments are performed for different spatial-light-modulator (SLM) bin sizes, beam-spot sizes, and nanoparticle concentrations. We find that all three parameters affect the different positional changes, implying that an optimization scheme can be used to maximize the stability of the wavefront-sample coupling. ...

  14. Amorphous semiconductor sample preparation for transmission EXAFS measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ridgway, M.C.; Glover, C.J.; Tan, H.H. [Australian National Univ., Canberra (Australia). Dept. of Electronic Materials Engineering] [and others

    1998-12-31

    A novel methodology has been developed for the preparation of amorphous semiconductor samples for use in transmission extended x-ray absorption fine structure (EXAFS) measurements. Epitaxial heterostructures were fabricated by metal organic chemical vapor deposition (group III-Vs) or molecular beam epitaxy (group IVs). An epitaxial layer of {approximately} 2 {micro}m thickness was separated from the underlying substrate by selective chemical etching of an intermediate sacrificial layer. Ion implantation was utilized to amorphize the epitaxial layer either before or after selective chemical etching. The resulting samples were both stoichiometric and homogeneous in contrast to those produced by conventional techniques. The fabrication of amorphous GaAs, InP, In{sub 0.53}Ga{sub 0.47}As and Si{sub x}Ge{sub 1{minus}x} samples is described. Furthermore, EXAFS measurements comparing both fluorescence and transmission detection, and crystalline and amorphized GaAs, are shown.

  15. Hands-free sample preparation platform for nucleic acid analysis.

    Science.gov (United States)

    Baier, T; Hansen-Hagge, T E; Gransee, R; Crombé, A; Schmahl, S; Paulus, C; Drese, K S; Keegan, H; Martin, C; O'Leary, J J; Furuberg, L; Solli, L; Grønn, P; Falang, I M; Karlgård, A; Gulliksen, A; Karlsen, F

    2009-12-07

    A Lab-On-Chip system with an instrument is presented which is capable of performing total sample preparation and automated extraction of nucleic acid from human cell samples fixed in a methanol based solution. The target application is extraction of mRNA from cervical liquid based cytology specimens for detection of transformed HPV-infections. The device accepts 3 ml of sample and performs the extraction in a disposable polymer chip of credit card size. All necessary reagents for cell lysis, washing, and elution are stored on-chip and the extraction is performed in two filter stages; one for cell pre-concentration and the other for nucleic acid capture. Tests performed using cancer cell lines and cervical liquid based cytology specimens confirm the extraction of HPV-mRNA by the system.

  16. Geostatistical sampling optimization and waste characterization of contaminated premises

    Energy Technology Data Exchange (ETDEWEB)

    Desnoyers, Y.; Jeannee, N. [GEOVARIANCES, 49bis avenue Franklin Roosevelt, BP91, Avon, 77212 (France); Chiles, J.P. [Centre de geostatistique, Ecole des Mines de Paris (France); Dubot, D. [CEA DSV/FAR/USLT/SPRE/SAS (France); Lamadie, F. [CEA DEN/VRH/DTEC/SDTC/LTM (France)

    2009-06-15

    At the end of process equipment dismantling, the complete decontamination of nuclear facilities requires a radiological assessment of the building structure residual activity. From this point of view, the set up of an appropriate evaluation methodology is of crucial importance. The radiological characterization of contaminated premises can be divided into three steps. First, the most exhaustive facility analysis provides historical and qualitative information. Then, a systematic (exhaustive) control of the emergent signal is commonly performed using in situ measurement methods such as surface controls combined with in situ gamma spectrometry. Finally, in order to assess the contamination depth, samples are collected at several locations within the premises and analyzed. Combined with historical information and emergent signal maps, such data allow the definition of a preliminary waste zoning. The exhaustive control of the emergent signal with surface measurements usually leads to inaccurate estimates, because of several factors: varying position of the measuring device, subtraction of an estimate of the background signal, etc. In order to provide reliable estimates while avoiding supplementary investigation costs, there is therefore a crucial need for sampling optimization methods together with appropriate data processing techniques. The initial activity usually presents a spatial continuity within the premises, with preferential contamination of specific areas or existence of activity gradients. Taking into account this spatial continuity is essential to avoid bias while setting up the sampling plan. In such a case, Geostatistics provides methods that integrate the contamination spatial structure. After the characterization of this spatial structure, most probable estimates of the surface activity at un-sampled locations can be derived using kriging techniques. Variants of these techniques also give access to estimates of the uncertainty associated to the spatial

  17. Optimizing the atmospheric sampling sites using fuzzy mathematic methods

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A new approach applying fuzzy mathematic theorems, including the Primary Matrix Element Theorem and the Fisher ClassificationMethod, was established to solve the optimization problem of atmospheric environmental sampling sites. According to its basis, an applicationin the optimization of sampling sites in the atmospheric environmental monitoring was discussed. The method was proven to be suitable andeffective. The results were admitted and applied by the Environmental Protection Bureau (EPB) of many cities of China. A set of computersoftware of this approach was also completely compiled and used.

  18. Optimization of fast dissolving etoricoxib tablets prepared by sublimation technique

    Directory of Open Access Journals (Sweden)

    Patel D

    2008-01-01

    Full Text Available The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 3 2 full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q 30 and dissolution efficiency after 30 min (DE 30 . From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent.

  19. Optimization of fast dissolving etoricoxib tablets prepared by sublimation technique.

    Science.gov (United States)

    Patel, D M; Patel, M M

    2008-01-01

    The purpose of this investigation was to develop fast dissolving tablets of etoricoxib. Granules containing etoricoxib, menthol, crospovidone, aspartame and mannitol were prepared by wet granulation technique. Menthol was sublimed from the granules by exposing the granules to vacuum. The porous granules were then compressed in to tablets. Alternatively, tablets were first prepared and later exposed to vacuum. The tablets were evaluated for percentage friability and disintegration time. A 3(2) full factorial design was applied to investigate the combined effect of 2 formulation variables: amount of menthol and crospovidone. The results of multiple regression analysis indicated that for obtaining fast dissolving tablets; optimum amount of menthol and higher percentage of crospovidone should be used. A surface response plots are also presented to graphically represent the effect of the independent variables on the percentage friability and disintegration time. The validity of a generated mathematical model was tested by preparing a checkpoint batch. Sublimation of menthol from tablets resulted in rapid disintegration as compared with the tablets prepared from granules that were exposed to vacuum. The optimized tablet formulation was compared with conventional marketed tablets for percentage drug dissolved in 30 min (Q(30)) and dissolution efficiency after 30 min (DE(30)). From the results, it was concluded that fast dissolving tablets with improved etoricoxib dissolution could be prepared by sublimation of tablets containing suitable subliming agent.

  20. Variance optimal sampling based estimation of subset sums

    CERN Document Server

    Cohen, Edith; Kaplan, Haim; Lund, Carsten; Thorup, Mikkel

    2008-01-01

    From a high volume stream of weighted items, we want to maintain a generic sample of a certain limited size $k$ that we can later use to estimate the total weight of arbitrary subsets. This is the classic context of on-line reservoir sampling, thinking of the generic sample as a reservoir. We present a reservoir sampling scheme providing variance optimal estimation of subset sums. More precisely, if we have seen $n$ items of the stream, then for any subset size $m$, our scheme based on $k$ samples minimizes the average variance over all subsets of size $m$. In fact, the optimality is against any off-line sampling scheme tailored for the concrete set of items seen: no off-line scheme based on $k$ samples can perform better than our on-line scheme when it comes to average variance over any subset size. Our scheme has no positive covariances between any pair of item estimates. Also, our scheme can handle each new item of the stream in $O(\\log k)$ time, which is optimal even on the word RAM.

  1. A fast method to prepare water samples for 15N analysis

    Institute of Scientific and Technical Information of China (English)

    肖化云; 刘丛强

    2001-01-01

    Automatic element analyser is often used to prepare organic matters tor 15N analysis. It is seldom used to prepare water samples. Water samples are conventionally dealt with by Kjeldahl-Rittenberg technique. But it requires tedious and labor-intensive sample preparation. A fast and reliable method is proposed in this paper to prepare water samples for 15N analysis.

  2. Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community

    KAUST Repository

    Xue, Zheng

    2014-07-15

    Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses, storage time at 4°C, and DNA extraction method) on the downstream analysis of nitrifying biofilms grown on ultrafiltration membranes. Both rinse and storage affected biofilm structure, as suggested by their strong correlation with total biovolume, biofilm thickness, roughness and the spatial distribution of EPS. Significant variations in DNA yields and microbial community diversity were also observed among samples treated by different rinses, storage and DNA extraction methods. For the tested biofilms, two rinses, no storage and DNA extraction with both mechanical and chemical cell lysis from attached biofilm were the optimal sample preparation procedures for obtaining accurate information about biofilm structure, EPS distribution and the microbial community. © 2014 © 2014 Taylor & Francis.

  3. Membrane biofouling characterization: effects of sample preparation procedures on biofilm structure and the microbial community.

    Science.gov (United States)

    Xue, Zheng; Lu, Huijie; Liu, Wen-Tso

    2014-01-01

    Ensuring the quality and reproducibility of results from biofilm structure and microbial community analysis is essential to membrane biofouling studies. This study evaluated the impacts of three sample preparation factors (ie number of buffer rinses, storage time at 4°C, and DNA extraction method) on the downstream analysis of nitrifying biofilms grown on ultrafiltration membranes. Both rinse and storage affected biofilm structure, as suggested by their strong correlation with total biovolume, biofilm thickness, roughness and the spatial distribution of EPS. Significant variations in DNA yields and microbial community diversity were also observed among samples treated by different rinses, storage and DNA extraction methods. For the tested biofilms, two rinses, no storage and DNA extraction with both mechanical and chemical cell lysis from attached biofilm were the optimal sample preparation procedures for obtaining accurate information about biofilm structure, EPS distribution and the microbial community.

  4. spsann - optimization of sample patterns using spatial simulated annealing

    Science.gov (United States)

    Samuel-Rosa, Alessandro; Heuvelink, Gerard; Vasques, Gustavo; Anjos, Lúcia

    2015-04-01

    There are many algorithms and computer programs to optimize sample patterns, some private and others publicly available. A few have only been presented in scientific articles and text books. This dispersion and somewhat poor availability is holds back to their wider adoption and further development. We introduce spsann, a new R-package for the optimization of sample patterns using spatial simulated annealing. R is the most popular environment for data processing and analysis. Spatial simulated annealing is a well known method with widespread use to solve optimization problems in the soil and geo-sciences. This is mainly due to its robustness against local optima and easiness of implementation. spsann offers many optimizing criteria for sampling for variogram estimation (number of points or point-pairs per lag distance class - PPL), trend estimation (association/correlation and marginal distribution of the covariates - ACDC), and spatial interpolation (mean squared shortest distance - MSSD). spsann also includes the mean or maximum universal kriging variance (MUKV) as an optimizing criterion, which is used when the model of spatial variation is known. PPL, ACDC and MSSD were combined (PAN) for sampling when we are ignorant about the model of spatial variation. spsann solves this multi-objective optimization problem scaling the objective function values using their maximum absolute value or the mean value computed over 1000 random samples. Scaled values are aggregated using the weighted sum method. A graphical display allows to follow how the sample pattern is being perturbed during the optimization, as well as the evolution of its energy state. It is possible to start perturbing many points and exponentially reduce the number of perturbed points. The maximum perturbation distance reduces linearly with the number of iterations. The acceptance probability also reduces exponentially with the number of iterations. R is memory hungry and spatial simulated annealing is a

  5. Sample Preparation (SS) - Metabolonote | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available 908/lsdba.nbdc01324-008 Description of data contents Detailed information regarding sample preparations comm...ed to by S (Sample information). Data file File name: metabolonote_sample_preparation..._details.zip File URL: ftp://ftp.biosciencedbc.jp/archive/metabolonote/LATEST/metabolonote_sample_preparation..._details.zip File size: 13 KB Simple search URL http://togodb.biosciencedbc.jp/togodb/view/metabolonote_sample_preparation... Preparation ID are merged into ID in the Simple search.) Sample Preparation ID The sample preparation detai

  6. Optimizing Soil Moisture Sampling Locations for Validation Networks for SMAP

    Science.gov (United States)

    Roshani, E.; Berg, A. A.; Lindsay, J.

    2013-12-01

    Soil Moisture Active Passive satellite (SMAP) is scheduled for launch on Oct 2014. Global efforts are underway for establishment of soil moisture monitoring networks for both the pre- and post-launch validation and calibration of the SMAP products. In 2012 the SMAP Validation Experiment, SMAPVEX12, took place near Carman Manitoba, Canada where nearly 60 fields were sampled continuously over a 6 week period for soil moisture and several other parameters simultaneous to remotely sensed images of the sampling region. The locations of these sampling sites were mainly selected on the basis of accessibility, soil texture, and vegetation cover. Although these criteria are necessary to consider during sampling site selection, they do not guarantee optimal site placement to provide the most efficient representation of the studied area. In this analysis a method for optimization of sampling locations is presented which combines the state-of-art multi-objective optimization engine (non-dominated sorting genetic algorithm, NSGA-II), with the kriging interpolation technique to minimize the number of sampling sites while simultaneously minimizing the differences between the soil moisture map resulted from the kriging interpolation and soil moisture map from radar imaging. The algorithm is implemented in Whitebox Geospatial Analysis Tools, which is a multi-platform open-source GIS. The optimization framework is subject to the following three constraints:. A) sampling sites should be accessible to the crew on the ground, B) the number of sites located in a specific soil texture should be greater than or equal to a minimum value, and finally C) the number of sampling sites with a specific vegetation cover should be greater than or equal to a minimum constraint. The first constraint is implemented into the proposed model to keep the practicality of the approach. The second and third constraints are considered to guarantee that the collected samples from each soil texture categories

  7. On sample preparation and dielectric breakdown in nanostructured epoxy resins

    Energy Technology Data Exchange (ETDEWEB)

    Reading, M; Xu, Z; Lewin, P L; Vaughan, A S, E-mail: asv@ecs.soton.ac.uk [Tony Davies High Voltage Laboratory, University of Southampton (United Kingdom)

    2011-08-12

    There are many methods available to achieve a good dispersion of fillers within a polymeric matrix. This investigation considered several methods of dispersing three chosen fillers within an epoxy resin; the same processes were also performed on unfilled materials to investigate any effects they may have on the host material. For this investigation, the epoxy system (EP) was combined with sodium montmorillonite (MMT), micrometric silicon dioxide (SD) or nanometric silicon dioxide (NSD) as fillers. The effect of the different sample preparation routes on breakdown behaviour was then evaluated. While more thorough mixing protocols were found to lead to improved breakdown behaviour in the case of the various filled systems, surprisingly, an entirely equivalent form of behaviour was also seen in the unfilled epoxy. The influence of changes in sample geometry on the breakdown strength was established.

  8. Standardized Sample Preparation Using a Drop-on-Demand Printing Platform

    Directory of Open Access Journals (Sweden)

    Paul M. Pellegrino

    2013-05-01

    Full Text Available Hazard detection systems must be evaluated with appropriate test material concentrations under controlled conditions in order to accurately identify and quantify unknown residues commonly utilized in theater. The existing assortment of hazard reference sample preparation methods/techniques presents a range of variability and reproducibility concerns, making it increasingly difficult to accurately assess optically- based detection technologies. To overcome these challenges, we examined the optimization, characterization, and calibration of microdroplets from a drop-on-demand microdispenser that has a proven capability for the preparation of energetic reference materials. Research presented herein focuses on the development of a simplistic instrument calibration technique and sample preparation protocol for explosive materials testing based on drop-on-demand technology. Droplet mass and reproducibility were measured using ultraviolet-visible (UV-Vis absorption spectroscopy. The results presented here demonstrate the operational factors that influence droplet dispensing for specific materials (e.g., energetic and interferents. Understanding these parameters permits the determination of droplet and sample uniformity and reproducibility (typical R2 values of 0.991, relative standard deviation or RSD ≤ 5%, and thus the demonstrated maturation of a successful and robust methodology for energetic sample preparation.

  9. Optimizing Sampling Efficiency for Biomass Estimation Across NEON Domains

    Science.gov (United States)

    Abercrombie, H. H.; Meier, C. L.; Spencer, J. J.

    2013-12-01

    Over the course of 30 years, the National Ecological Observatory Network (NEON) will measure plant biomass and productivity across the U.S. to enable an understanding of terrestrial carbon cycle responses to ecosystem change drivers. Over the next several years, prior to operational sampling at a site, NEON will complete construction and characterization phases during which a limited amount of sampling will be done at each site to inform sampling designs, and guide standardization of data collection across all sites. Sampling biomass in 60+ sites distributed among 20 different eco-climatic domains poses major logistical and budgetary challenges. Traditional biomass sampling methods such as clip harvesting and direct measurements of Leaf Area Index (LAI) involve collecting and processing plant samples, and are time and labor intensive. Possible alternatives include using indirect sampling methods for estimating LAI such as digital hemispherical photography (DHP) or using a LI-COR 2200 Plant Canopy Analyzer. These LAI estimations can then be used as a proxy for biomass. The biomass estimates calculated can then inform the clip harvest sampling design during NEON operations, optimizing both sample size and number so that standardized uncertainty limits can be achieved with a minimum amount of sampling effort. In 2011, LAI and clip harvest data were collected from co-located sampling points at the Central Plains Experimental Range located in northern Colorado, a short grass steppe ecosystem that is the NEON Domain 10 core site. LAI was measured with a LI-COR 2200 Plant Canopy Analyzer. The layout of the sampling design included four, 300 meter transects, with clip harvests plots spaced every 50m, and LAI sub-transects spaced every 10m. LAI was measured at four points along 6m sub-transects running perpendicular to the 300m transect. Clip harvest plots were co-located 4m from corresponding LAI transects, and had dimensions of 0.1m by 2m. We conducted regression analyses

  10. Preparation and Optimization of Nanoemulsions for targeting Drug Delivery

    Directory of Open Access Journals (Sweden)

    Navneet Sharma

    2013-12-01

    Full Text Available Nanoemulsions have appeared as a novel drug delivery system which allows sustained or controlled release of drug, biological active ingredient and genetic material. Nanoemulsion is a dispersion consisting of oil, surfactant and an aqueous phase, which is a isotropically clear and thermo-dynamically or kinetically stable liquid solution, usually with droplet diameter within the range of 10-500nm. Although interest in nano-emulsions was developed for more than two decades now, mainly for nanoparticle preparation, it is in the last few years that direct applications of nano-emulsions in consumer products are being developed, mainly in pharmacy and cosmetics. These recent applications have made that studies on optimization methods for nano-emulsion preparation be a requirement. The design of effective formulations for drugs has long been a major task, because drug efficacy can severely limited by instability or poor solubility in the vehicle. Nanoemulsion is being applied to enhance the solubility and bioavailability of water insoluble drugs. The nanosized droplets leading to an enormous increase in interfacial areas associated with nanoemulsion would influence the transport properties of the drug [1, 2]. Recently, there has been a considerable attraction for this formulation, for the delivery of hydrophilic as well as hydrophobic drug as drug carriers because of its improved drug solubilization capacity, long shelf life, ease of preparation and improvement of bioavailability of drugs. This review is focused on the most recent literature on developments of nano-emulsions as final application products and on the optimization of their preparation.

  11. Ad-Hoc vs. Standardized and Optimized Arthropod Diversity Sampling

    Directory of Open Access Journals (Sweden)

    Pedro Cardoso

    2009-09-01

    Full Text Available The use of standardized and optimized protocols has been recently advocated for different arthropod taxa instead of ad-hoc sampling or sampling with protocols defined on a case-by-case basis. We present a comparison of both sampling approaches applied for spiders in a natural area of Portugal. Tests were made to their efficiency, over-collection of common species, singletons proportions, species abundance distributions, average specimen size, average taxonomic distinctness and behavior of richness estimators. The standardized protocol revealed three main advantages: (1 higher efficiency; (2 more reliable estimations of true richness; and (3 meaningful comparisons between undersampled areas.

  12. Preparation of tissue samples for X-ray fluorescence microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chwiej, Joanna [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland)]. E-mail: jchwiej@novell.ftj.agh.edu.pl; Szczerbowska-Boruchowska, Magdalena [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Lankosz, Marek [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Wojcik, Slawomir [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Falkenberg, Gerald [Hamburger Synchrotronstrahlungslabor at Deutsches Elektronen-Synchrotron, Notkestr. 85, Hamburg (Germany); Stegowski, Zdzislaw [Faculty of Physics and Applied Computer Science, AGH-University of Science and Technology, Al. Mickiewicza 30, 30-059 Cracow (Poland); Setkowicz, Zuzanna [Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Ingardena 6, 30-060 Cracow (Poland)

    2005-12-15

    As is well-known, trace elements, especially metals, play an important role in the pathogenesis of many disorders. The topographic and quantitative elemental analysis of pathologically changed tissues may shed some new light on processes leading to the degeneration of cells in the case of selected diseases. An ideal and powerful tool for such purpose is the Synchrotron Microbeam X-ray Fluorescence technique. It enables the carrying out of investigations of the elemental composition of tissues even at the single cell level. The tissue samples for histopathological investigations are routinely fixed and embedded in paraffin. The authors try to verify the usefulness of such prepared tissue sections for elemental analysis with the use of X-ray fluorescence microscopy. Studies were performed on rat brain samples. Changes in elemental composition caused by fixation in formalin or paraformaldehyde and embedding in paraffin were examined. Measurements were carried out at the bending magnet beamline L of the Hamburger Synchrotronstrahlungslabor HASYLAB in Hamburg. The decrease in mass per unit area of K, Br and the increase in P, S, Fe, Cu and Zn in the tissue were observed as a result of the fixation. For the samples embedded in paraffin, a lower level of most elements was observed. Additionally, for these samples, changes in the composition of some elements were not uniform for different analyzed areas of rat brain.

  13. Preparation, sintering and leaching of optimized uranium thorium dioxides

    Science.gov (United States)

    Hingant, N.; Clavier, N.; Dacheux, N.; Barre, N.; Hubert, S.; Obbade, S.; Taborda, F.; Abraham, F.

    2009-03-01

    Mixed actinide dioxides are currently studied as potential fuels for several concepts associated to the fourth generation of nuclear reactors. These solids are generally obtained through dry chemistry processes from powder mixtures but could present some heterogeneity in the distribution of the cations in the solid. In this context, wet chemistry methods were set up for the preparation of U1-xThxO2 solid solutions as model compounds for advanced dioxide fuels. Two chemical routes of preparation, involving the precipitation of crystallized precursor, were investigated: on the one hand, a mixture of acidic solutions containing cations and oxalic acid was introduced in an open vessel, leading to a poorly-crystallized precipitate. On the other hand, the starting mixture was placed in an acid digestion bomb then set in an oven in order to reach hydrothermal conditions. By this way, small single-crystals were obtained then characterized by several techniques including XRD and SEM. The great differences in terms of morphology and crystallization state of the samples were correlated to an important variation of the specific surface area of the oxides prepared after heating, then the microstructure of the sintered pellets prepared at high temperature. Preliminary leaching tests were finally undertaken in dynamic conditions (i.e. with high renewal of the leachate) in order to evaluate the influence of the sample morphology on the chemical durability of the final cohesive materials.

  14. Optimal Design and Purposeful Sampling: Complementary Methodologies for Implementation Research.

    Science.gov (United States)

    Duan, Naihua; Bhaumik, Dulal K; Palinkas, Lawrence A; Hoagwood, Kimberly

    2015-09-01

    Optimal design has been an under-utilized methodology. However, it has significant real-world applications, particularly in mixed methods implementation research. We review the concept and demonstrate how it can be used to assess the sensitivity of design decisions and balance competing needs. For observational studies, this methodology enables selection of the most informative study units. For experimental studies, it entails selecting and assigning study units to intervention conditions in the most informative manner. We blend optimal design methods with purposeful sampling to show how these two concepts balance competing needs when there are multiple study aims, a common situation in implementation research.

  15. Optimal allocation of point-count sampling effort

    Science.gov (United States)

    Barker, R.J.; Sauer, J.R.; Link, W.A.

    1993-01-01

    Both unlimited and fixedradius point counts only provide indices to population size. Because longer count durations lead to counting a higher proportion of individuals at the point, proper design of these surveys must incorporate both count duration and sampling characteristics of population size. Using information about the relationship between proportion of individuals detected at a point and count duration, we present a method of optimizing a pointcount survey given a fixed total time for surveying and travelling between count points. The optimization can be based on several quantities that measure precision, accuracy, or power of tests based on counts, including (1) meansquare error of estimated population change; (2) mean-square error of average count; (3) maximum expected total count; or (4) power of a test for differences in average counts. Optimal solutions depend on a function that relates count duration at a point to the proportion of animals detected. We model this function using exponential and Weibull distributions, and use numerical techniques to conduct the optimization. We provide an example of the procedure in which the function is estimated from data of cumulative number of individual birds seen for different count durations for three species of Hawaiian forest birds. In the example, optimal count duration at a point can differ greatly depending on the quantities that are optimized. Optimization of the mean-square error or of tests based on average counts generally requires longer count durations than does estimation of population change. A clear formulation of the goals of the study is a critical step in the optimization process.

  16. Sample preparation strategies for food and biological samples prior to nanoparticle detection and imaging

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt; Löschner, Katrin

    2014-01-01

    fractionation (AFFF, or AF4) coupled on-line to various detectors including static and dynamic light scattering (LS), UV or fluorescence (FL) spectroscopies and ICP-MS have proven useful and powerful [1, 2, 3]. Furthermore, additional information obtained by an imaging method such as transmission electron...... microscopy (TEM) proved to be necessary for trouble shooting of results obtained from AFFF-LS-ICP-MS. Aqueous and enzymatic extraction strategies were tested for thorough sample preparation aiming at degrading the sample matrix and to liberate the AgNPs from chicken meat into liquid suspension. The resulting...

  17. MALDI MS sample preparation by using paraffin wax film: systematic study and application for peptide analysis.

    Science.gov (United States)

    Wang, Junhua; Chen, Ruibing; Ma, Mingming; Li, Lingjun

    2008-01-15

    Recently developed sample preparation techniques employing hydrophobic sample support have improved the detection sensitivity and mass spectral quality of matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). These methods concentrate the samples on target by minimizing the sample area via the solvent repellent effect of the target surface. In the current study, we employed the use of paraffin wax film (Parafilm M) for improved MALDI MS analysis of low-abundance peptide mixtures, including neuronal tissue releasate and protein tryptic digests. This thin film was found to strongly repel polar solvents including water, methanol, and acetonitrile, which enabled the application of a wide range of sample preparation protocols that involved the use of various organic solvents. A "nanoliter-volume deposition" technique employing a capillary column has been used to produce tiny ( approximately 400 microm) matrix spots of 2,5-dihydroxybenzoic acid on the film. By systematically optimizing the sample volume, solvent composition, and film treatment, the Parafilm M substrate in combination with the nanoliter-volume matrix deposition method allowed dilute sample to be concentrated on the film for MALDI MS analysis. Peptide mixtures with nanomolar concentrations have been detected by MALDI time-of-flight and MALDI Fourier transform ion cyclotron resonance mass spectrometers. Overall, the use of Parafilm M enabled improved sensitivity and spectral quality for the analysis of complex peptide mixtures.

  18. Classifier-Guided Sampling for Complex Energy System Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Backlund, Peter B. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Eddy, John P. [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-09-01

    This report documents the results of a Laboratory Directed Research and Development (LDRD) effort enti tled "Classifier - Guided Sampling for Complex Energy System Optimization" that was conducted during FY 2014 and FY 2015. The goal of this proj ect was to develop, implement, and test major improvements to the classifier - guided sampling (CGS) algorithm. CGS is type of evolutionary algorithm for perform ing search and optimization over a set of discrete design variables in the face of one or more objective functions. E xisting evolutionary algorithms, such as genetic algorithms , may require a large number of o bjecti ve function evaluations to identify optimal or near - optimal solutions . Reducing the number of evaluations can result in significant time savings, especially if the objective function is computationally expensive. CGS reduce s the evaluation count by us ing a Bayesian network classifier to filter out non - promising candidate designs , prior to evaluation, based on their posterior probabilit ies . In this project, b oth the single - objective and multi - objective version s of the CGS are developed and tested on a set of benchm ark problems. As a domain - specific case study, CGS is used to design a microgrid for use in islanded mode during an extended bulk power grid outage.

  19. Optimal tests for the two-sample spherical location problem

    CERN Document Server

    Ley, Christophe; Verdebout, Thomas

    2012-01-01

    We tackle the classical two-sample spherical location problem for directional data by having recourse to the Le Cam methodology, habitually used in classical "linear" multivariate analysis. More precisely we construct locally and asymptotically optimal (in the maximin sense) parametric tests, which we then turn into semi-parametric ones in two distinct ways. First, by using a studentization argument; this leads to so-called pseudo-FvML tests. Second, by resorting to the invariance principle; this leads to efficient rank-based tests. Within each construction, the semi-parametric tests inherit optimality under a given distribution (the FvML in the first case, any rotationally symmetric one in the second) from their parametric counterparts and also improve on the latter by being valid under the whole class of rotationally symmetric distributions. Asymptotic relative efficiencies are calculated and the finite-sample behavior of the proposed tests is investigated by means of a Monte Carlo simulation.

  20. Efficient infill sampling for unconstrained robust optimization problems

    Science.gov (United States)

    Rehman, Samee Ur; Langelaar, Matthijs

    2016-08-01

    A novel infill sampling criterion is proposed for efficient estimation of the global robust optimum of expensive computer simulation based problems. The algorithm is especially geared towards addressing problems that are affected by uncertainties in design variables and problem parameters. The method is based on constructing metamodels using Kriging and adaptively sampling the response surface via a principle of expected improvement adapted for robust optimization. Several numerical examples and an engineering case study are used to demonstrate the ability of the algorithm to estimate the global robust optimum using a limited number of expensive function evaluations.

  1. Microsystem strategies for sample preparation in biological detection.

    Energy Technology Data Exchange (ETDEWEB)

    James, Conrad D.; Galambos, Paul C.; Bennett, Dawn Jonita (University of Maryland Baltimore County, Baltimore, MD); Manginell, Monica; Okandan, Murat; Acrivos, Andreas (The City College of New York, NY); Brozik, Susan Marie; Khusid, Boris (New Jersey Institute of Technology, Newark, NJ)

    2005-03-01

    The objective of this LDRD was to develop microdevice strategies for dealing with samples to be examined in biological detection systems. This includes three sub-components: namely, microdevice fabrication, sample delivery to the microdevice, and sample processing within the microdevice. The first component of this work focused on utilizing Sandia's surface micromachining technology to fabricate small volume (nanoliter) fluidic systems for processing small quantities of biological samples. The next component was to develop interfaces for the surface-micromachined silicon devices. We partnered with Micronics, a commercial company, to produce fluidic manifolds for sample delivery to our silicon devices. Pressure testing was completed to examine the strength of the bond between the pressure-sensitive adhesive layer and the silicon chip. We are also pursuing several other methods, both in house and external, to develop polymer-based fluidic manifolds for packaging silicon-based microfluidic devices. The second component, sample processing, is divided into two sub-tasks: cell collection and cell lysis. Cell collection was achieved using dielectrophoresis, which employs AC fields to collect cells at energized microelectrodes, while rejecting non-cellular particles. Both live and dead Staph. aureus bacteria have been collected using RF frequency dielectrophoresis. Bacteria have been separated from polystyrene microspheres using frequency-shifting dielectrophoresis. Computational modeling was performed to optimize device separation performance, and to predict particle response to the dielectrophoretic traps. Cell lysis is continuing to be pursued using microactuators to mechanically disrupt cell membranes. Novel thermal actuators, which can generate larger forces than previously tested electrostatic actuators, have been incorporated with and tested with cell lysis devices. Significant cell membrane distortion has been observed, but more experiments need to be

  2. Simultaneous beam sampling and aperture shape optimization for SPORT

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, Masoud; Li, Ruijiang; Xing, Lei, E-mail: Lei@stanford.edu [Department of Radiation Oncology, Stanford University, Stanford, California 94305 (United States); Ye, Yinyu [Department of Management Science and Engineering, Stanford University, Stanford, California 94305 (United States)

    2015-02-15

    Purpose: Station parameter optimized radiation therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital linear accelerators, in which the station parameters of a delivery system, such as aperture shape and weight, couch position/angle, gantry/collimator angle, can be optimized simultaneously. SPORT promises to deliver remarkable radiation dose distributions in an efficient manner, yet there exists no optimization algorithm for its implementation. The purpose of this work is to develop an algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: The authors build a mathematical model with the fundamental station point parameters as the decision variables. To solve the resulting large-scale optimization problem, the authors devise an effective algorithm by integrating three advanced optimization techniques: column generation, subgradient method, and pattern search. Column generation adds the most beneficial stations sequentially until the plan quality improvement saturates and provides a good starting point for the subsequent optimization. It also adds the new stations during the algorithm if beneficial. For each update resulted from column generation, the subgradient method improves the selected stations locally by reshaping the apertures and updating the beam angles toward a descent subgradient direction. The algorithm continues to improve the selected stations locally and globally by a pattern search algorithm to explore the part of search space not reachable by the subgradient method. By combining these three techniques together, all plausible combinations of station parameters are searched efficiently to yield the optimal solution. Results: A SPORT optimization framework with seamlessly integration of three complementary algorithms, column generation, subgradient method, and pattern search, was established. The proposed technique was applied to two previously treated clinical cases: a head and

  3. Comparison of sample preparation methods for the recovery of foodborne pathogens from fresh produce.

    Science.gov (United States)

    Kim, Se-Ri; Yoon, Yohan; Kim, Won-Il; Park, Kyeong-Hun; Yun, Hye-Jeong; Chung, Duck Hwa; Yun, Jong Chul; Ryu, Kyoung Yul

    2012-07-01

    Sample preparation methods (pummeling, pulsifying, sonication, and shaking by hand) were compared for achieving maximum recovery of foodborne pathogens from iceberg lettuce, perilla leaves, cucumber, green pepper, and cherry tomato. Antimicrobial and dehydration effects also were examined to investigate causes of poor recovery of pathogens. Each produce type was inoculated with Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes, Staphylococcus aureus, and Bacillus cereus at 6.0 log CFU/cm(2), and samples were prepared using the four methods. Bacterial populations recovered from the five types of produce were significantly different (P cucumber, and green pepper had no antimicrobial activity, the populations of E. coli O157:H7, Salmonella Typhimurium, B. cereus, and L. monocytogenes in cherry tomato extract were slightly reduced after these treatments (P 2 log CFU/cm(2) after exposure to 40% relative humidity for 1 h. No reduction was observed when the five pathogens were exposed to 90% relative humidity. These data suggest that pummeling and pulsifying are optimal sample preparation methods for detection of microorganisms. Acidic produce such as cherry tomato should be treated with a method that does not cause sample breakdown so that acid stress on the bacteria can be minimized. Dehydration stress also affects recovery of pathogens from produce.

  4. An enzyme-based DNA preparation method for application to forensic biological samples and degraded stains.

    Science.gov (United States)

    Lounsbury, Jenny A; Coult, Natalie; Miranian, Daniel C; Cronk, Stephen M; Haverstick, Doris M; Kinnon, Paul; Saul, David J; Landers, James P

    2012-09-01

    Extraction of DNA from forensic samples typically uses either an organic extraction protocol or solid phase extraction (SPE) and these methods generally involve numerous sample transfer, wash and centrifugation steps. Although SPE has been successfully adapted to the microdevice, it can be problematic because of lengthy load times and uneven packing of the solid phase. A closed-tube enzyme-based DNA preparation method has recently been developed which uses a neutral proteinase to lyse cells and degrade proteins and nucleases [14]. Following a 20 min incubation of the buccal or whole blood sample with this proteinase, DNA is polymerase chain reaction (PCR)-ready. This paper describes the optimization and quantitation of DNA yield using this method, and application to forensic biological samples, including UV- and heat-degraded whole blood samples on cotton or blue denim substrates. Results demonstrate that DNA yield can be increased from 1.42 (±0.21)ng/μL to 7.78 (±1.40)ng/μL by increasing the quantity of enzyme per reaction by 3-fold. Additionally, there is a linear relationship between the amount of starting cellular material added and the concentration of DNA in the solution, thereby allowing DNA yield estimations to be made. In addition, short tandem repeat (STR) profile results obtained using DNA prepared with the enzyme method were comparable to those obtained with a conventional SPE method, resulting in full STR profiles (16 of 16 loci) from liquid samples (buccal swab eluate and whole blood), dried buccal swabs and bloodstains and partial profiles from UV or heat-degraded bloodstains on cotton or blue denim substrates. Finally, the DNA preparation method is shown to be adaptable to glass or poly(methyl methacrylate) (PMMA) microdevices with little impact on STR peak height but providing a 20-fold reduction in incubation time (as little as 60 s), leading to a ≥1 h reduction in DNA preparation time.

  5. Effect of sample preparation on charged impurities in graphene substrates

    Science.gov (United States)

    Burson, K. M.; Dean, C. R.; Watanabe, K.; Taniguchi, T.; Hone, J.; Kim, P.; Cullen, W. G.; Fuhrer, M. S.

    2013-03-01

    The mobility of graphene as fabricated on SiO2 has been found to vary widely depending on sample preparation conditions. Additionally, graphene mobility on SiO2 appears to be limited to ~20,000 cm2/Vs, likely due to charged impurities in the substrate. Here we present a study of the effect of fabrication procedures on substrate charged impurity density (nimp) utilizing ultrahigh-vacuum Kelvin probe force microscopy. We conclude that even minimal SEM exposure, as from e-beam lithography, induces an increased impurity density, while heating reduces the number of charges for sample substrates which already exhibit a higher impurity density. We measure both SiO2 and h-BN and find that all nimp values observed for SiO2 are higher than those observed for h-BN; this is consistent with the observed improvement in mobility for graphene devices fabricated on h-BN over those fabricated on SiO2 substrates. This work was supported by the US ONR MURI program, and the University of Maryland NSF-MRSEC under Grant No. DMR 05-20471.

  6. Miniaturized sample preparation method for determination of amphetamines in urine.

    Science.gov (United States)

    Nishida, Manami; Namera, Akira; Yashiki, Mikio; Kimura, Kojiro

    2004-07-16

    A simple and miniaturized sample preparation method for determination of amphetamines in urine was developed using on-column derivatization and gas chromatography-mass spectrometry (GC-MS). Urine was directly applied to the extraction column that was pre-packed with Extrelut and sodium carbonate. Amphetamine (AP) and methamphetamine (MA) in urine were adsorbed on the surface of Extrelut. AP and MA were then converted to a free base and derivatized to N-propoxycarbonyl derivatives using propylchloroformate on the column. Pentadeuterated MA was used as an internal standard. The recoveries of AP and MA from urine were 100 and 102%, respectively. The calibration curves showed linearity in the range of 0.50-50 microg/mL for AP and MA in urine. When urine samples containing two different concentrations (0.50 and 5.0 microg/mL) of AP and MA were determined, the intra-day and inter-day coefficients of variation were 1.4-7.7%. This method was applied to 14 medico-legal cases of MA intoxication. The results were compared and a good agreement was obtained with a HPLC method.

  7. Ultrasound: a subexploited tool for sample preparation in metabolomics.

    Science.gov (United States)

    Luque de Castro, M D; Delgado-Povedano, M M

    2014-01-02

    Metabolomics, one of the most recently emerged "omics", has taken advantage of ultrasound (US) to improve sample preparation (SP) steps. The metabolomics-US assisted SP step binomial has experienced a dissimilar development that has depended on the area (vegetal or animal) and the SP step. Thus, vegetal metabolomics and US assisted leaching has received the greater attention (encompassing subdisciplines such as metallomics, xenometabolomics and, mainly, lipidomics), but also liquid-liquid extraction and (bio)chemical reactions in metabolomics have taken advantage of US energy. Also clinical and animal samples have benefited from US assisted SP in metabolomics studies but in a lesser extension. The main effects of US have been shortening of the time required for the given step, and/or increase of its efficiency or availability for automation; nevertheless, attention paid to potential degradation caused by US has been scant or nil. Achievements and weak points of the metabolomics-US assisted SP step binomial are discussed and possible solutions to the present shortcomings are exposed. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Optimizing Wound Bed Preparation With Collagenase Enzymatic Debridement

    Science.gov (United States)

    McCallon, Stanley K.; Weir, Dorothy; Lantis, John C.

    2015-01-01

    Difficult-to-heal and chronic wounds affect tens of millions of people worldwide. In the U.S. alone, the direct cost for their treatment exceeds $25 billion. Yet despite advances in wound research and treatment that have markedly improved patient care, wound healing is often delayed for weeks or months. For venous and diabetic ulcers, complete wound closure is achieved in as few as 25%–50% of chronic or hard-to-heal wounds. Wound bed preparation and the consistent application of appropriate and effective debridement techniques are recommended for the optimized treatment of chronic wounds. The TIME paradigm (Tissue, Inflammation/infection, Moisture balance and Edge of wound) provides a model to remove barriers to healing and optimize the healing process. While we often think of debridement as an episodic event that occurs in specific care giver/patient interface. There is the possibility of a maintenance debridement in which the chronic application of a medication can assist in both the macroscopic and microscopic debridement of a wound. We review the various debridement therapies available to clinicians in the United States, and explore the characteristics and capabilities of clostridial collagenase ointment (CCO), a type of enzymatic debridement, that potentially allows for epithelialization while debriding. It appears that in the case of CCO it may exert this influences by removal of the necrotic plug while promoting granulation and sustaining epithelialization. It is also easily combined with other methods of debridement, is selective to necrotic tissue, and has been safely used in various populations. We review the body of evidence has indicated that this concept of maintenance debridement, especially when combined episodic debridement may add a cost an efficacious, safe and cost-effective choice for debridement of cutaneous ulcers and burn wounds and it will likely play an expanding role in all phases of wound bed preparation. PMID:26442207

  9. DIELECTRIC PROPERTIES OF STRAINED ICE. II : EFFECT OF SAMPLE PREPARATION METHOD

    OpenAIRE

    Itagaki, K.; Lemieux, G.

    1987-01-01

    Since most commonly used sample preparation methods for ice dielectric studies involve rather heavy mechanical straining, the effects of straining were studied and compared with more strain-free sample preparation methods.

  10. Near-Optimal Random Walk Sampling in Distributed Networks

    CERN Document Server

    Sarma, Atish Das; Pandurangan, Gopal

    2012-01-01

    Performing random walks in networks is a fundamental primitive that has found numerous applications in communication networks such as token management, load balancing, network topology discovery and construction, search, and peer-to-peer membership management. While several such algorithms are ubiquitous, and use numerous random walk samples, the walks themselves have always been performed naively. In this paper, we focus on the problem of performing random walk sampling efficiently in a distributed network. Given bandwidth constraints, the goal is to minimize the number of rounds and messages required to obtain several random walk samples in a continuous online fashion. We present the first round and message optimal distributed algorithms that present a significant improvement on all previous approaches. The theoretical analysis and comprehensive experimental evaluation of our algorithms show that they perform very well in different types of networks of differing topologies. In particular, our results show h...

  11. Optimized distributed computing environment for mask data preparation

    Science.gov (United States)

    Ahn, Byoung-Sup; Bang, Ju-Mi; Ji, Min-Kyu; Kang, Sun; Jang, Sung-Hoon; Choi, Yo-Han; Ki, Won-Tai; Choi, Seong-Woon; Han, Woo-Sung

    2005-11-01

    As the critical dimension (CD) becomes smaller, various resolution enhancement techniques (RET) are widely adopted. In developing sub-100nm devices, the complexity of optical proximity correction (OPC) is severely increased and applied OPC layers are expanded to non-critical layers. The transformation of designed pattern data by OPC operation causes complexity, which cause runtime overheads to following steps such as mask data preparation (MDP), and collapse of existing design hierarchy. Therefore, many mask shops exploit the distributed computing method in order to reduce the runtime of mask data preparation rather than exploit the design hierarchy. Distributed computing uses a cluster of computers that are connected to local network system. However, there are two things to limit the benefit of the distributing computing method in MDP. First, every sequential MDP job, which uses maximum number of available CPUs, is not efficient compared to parallel MDP job execution due to the input data characteristics. Second, the runtime enhancement over input cost is not sufficient enough since the scalability of fracturing tools is limited. In this paper, we will discuss optimum load balancing environment that is useful in increasing the uptime of distributed computing system by assigning appropriate number of CPUs for each input design data. We will also describe the distributed processing (DP) parameter optimization to obtain maximum throughput in MDP job processing.

  12. Optimization of technological parameters for preparation of lycopene microcapsules.

    Science.gov (United States)

    Guo, Hui; Huang, Ying; Qian, Jun-Qing; Gong, Qiu-Yi; Tang, Ying

    2014-07-01

    Lycopene belongs to the carotenoid family with high degree of unsaturation and all-trans form. Lycopene is easy to isomerize and auto oxide by heat, light, oxygen and different food matrices. With an increasing understanding of the health benefit of lycopene, to enhance stability and bioavailability of lycopene, ultrasonic emulsification was used to prepare lycopene microcapsules in this article. The results optimized by response surface methodology (RSM) for microcapsules consisted of four major steps: (1) 0.54 g glycerin monostearate was fully dissolved in 5 mL ethyl acetate and then added 0.02 g lycopene to form an organic phase, 100.7 mL distilled water which dissolved 0.61 g synperonic pe(R)/F68 as the aqueous phase; (2) the organic phase was pulled into the aqueous phase under stirring at 60 °C water bath for 5 min; (3) the mixture was then ultrasonic homogenized at 380 W for 20 min to form a homogenous emulsion; (4) the resulting emulsion was rotary evaporated at 50 °C water bath for 10 min under a pressure of 20 MPa. Encapsulation efficiency (EE) of lycopene microcapsules under the optimized conditions approached to 64.4%.

  13. Optimal sampling frequency in recording of resistance training exercises.

    Science.gov (United States)

    Bardella, Paolo; Carrasquilla García, Irene; Pozzo, Marco; Tous-Fajardo, Julio; Saez de Villareal, Eduardo; Suarez-Arrones, Luis

    2017-03-01

    The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.

  14. Preparation of Plant 41Ca Tracer Samples for Accelerator Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    ZHAO Qing-zhang1;JANG Ping-ping3;LIN De-yu4;YANG Xian-lin1;DOU Liang1;PANG Yi-jun1;WANG Xiao-ming1;ZHANG Hui1,5;YANG Xu-ran1;WU Shao-yong1;GAO Dong-sheng2;LI Ling2;WANG Lei2;SUN Ke-peng2;ZHOU Jun2;DONG Ke-jun1;HE Ming1

    2016-11-01

    Full Text Available Calcium plays an important role in the metabolism of plants and animals. In this paper, the preparation method of plant 41Ca for accelerator mass spectrometry (AMS measurement was developed for the first time in China. AMS, with its advantages of high sensitivity, small dose of radioactivity, high accuracy, large measuring range, and long tracer cycle, can be used to measure cosmogenic nuclide 41Ca , which has long half-life. The intensity of the beam in ion source is an important parameter for the sensitivity of AMS measurement. The high beam current can improve the sensitivity of AMS. The preparation methods of plant samples of 41Ca tracer were systematically studied to obtain high beam current using wet, dry and a combining method with wet and dry re-fluoride. A reliable preparation procedure of plant samples for 41Ca tracer and its optimization parameters were determined by testing beam currents of various samples and lay a foundation for the 41Ca-AMS technology at plant tracer applications.

  15. DNA isolation and sample preparation for quantification of adduct levels by accelerator mass spectrometry.

    Science.gov (United States)

    Dingley, Karen H; Ubick, Esther A; Vogel, John S; Ognibene, Ted J; Malfatti, Michael A; Kulp, Kristen; Haack, Kurt W

    2014-01-01

    Accelerator mass spectrometry (AMS) is a highly sensitive technique used for the quantification of adducts following exposure to carbon-14- or tritium-labeled chemicals, with detection limits in the range of one adduct per 10(11)-10(12) nucleotides. The protocol described in this chapter provides an optimal method for isolating and preparing DNA samples to measure isotope-labeled DNA adducts by AMS. When preparing samples, special precautions must be taken to avoid cross-contamination of isotope among samples and produce a sample that is compatible with AMS. The DNA isolation method described is based upon digestion of tissue with proteinase K, followed by extraction of DNA using Qiagen isolation columns. The extracted DNA is precipitated with isopropanol, washed repeatedly with 70 % ethanol to remove salt, and then dissolved in water. DNA samples are then converted to graphite or titanium hydride and the isotope content measured by AMS to quantify adduct levels. This method has been used to reliably generate good yields of uncontaminated, pure DNA from animal and human tissues for analysis of adduct levels.

  16. Sample Preparation Report of the Fourth OPCW Confidence Building Exercise on Biomedical Sample Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Udey, R. N. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Corzett, T. H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Alcaraz, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-07-03

    Following the successful completion of the 3rd biomedical confidence building exercise (February 2013 – March 2013), which included the analysis of plasma and urine samples spiked at low ppb levels as part of the exercise scenario, another confidence building exercise was targeted to be conducted in 2014. In this 4th exercise, it was desired to focus specifically on the analysis of plasma samples. The scenario was designed as an investigation of an alleged use of chemical weapons where plasma samples were collected, as plasma has been reported to contain CWA adducts which remain present in the human body for several weeks (Solano et al. 2008). In the 3rd exercise most participants used the fluoride regeneration method to analyze for the presence of nerve agents in plasma samples. For the 4th biomedical exercise it was decided to evaluate the analysis of human plasma samples for the presence/absence of the VX adducts and aged adducts to blood proteins (e.g., VX-butyrylcholinesterase (BuChE) and aged BuChE adducts using a pepsin digest technique to yield nonapeptides; or equivalent). As the aging of VX-BuChE adducts is relatively slow (t1/2 = 77 hr at 37 °C [Aurbek et al. 2009]), soman (GD), which ages much more quickly (t1/2 = 9 min at 37 °C [Masson et al. 2010]), was used to simulate an aged VX sample. Additional objectives of this exercise included having laboratories assess novel OP-adducted plasma sample preparation techniques and analytical instrumentation methodologies, as well as refining/designating the reporting formats for these new techniques.

  17. Searching for the Optimal Sampling Solution: Variation in Invertebrate Communities, Sample Condition and DNA Quality.

    Directory of Open Access Journals (Sweden)

    Martin M Gossner

    Full Text Available There is a great demand for standardising biodiversity assessments in order to allow optimal comparison across research groups. For invertebrates, pitfall or flight-interception traps are commonly used, but sampling solution differs widely between studies, which could influence the communities collected and affect sample processing (morphological or genetic. We assessed arthropod communities with flight-interception traps using three commonly used sampling solutions across two forest types and two vertical strata. We first considered the effect of sampling solution and its interaction with forest type, vertical stratum, and position of sampling jar at the trap on sample condition and community composition. We found that samples collected in copper sulphate were more mouldy and fragmented relative to other solutions which might impair morphological identification, but condition depended on forest type, trap type and the position of the jar. Community composition, based on order-level identification, did not differ across sampling solutions and only varied with forest type and vertical stratum. Species richness and species-level community composition, however, differed greatly among sampling solutions. Renner solution was highly attractant for beetles and repellent for true bugs. Secondly, we tested whether sampling solution affects subsequent molecular analyses and found that DNA barcoding success was species-specific. Samples from copper sulphate produced the fewest successful DNA sequences for genetic identification, and since DNA yield or quality was not particularly reduced in these samples additional interactions between the solution and DNA must also be occurring. Our results show that the choice of sampling solution should be an important consideration in biodiversity studies. Due to the potential bias towards or against certain species by Ethanol-containing sampling solution we suggest ethylene glycol as a suitable sampling solution when

  18. Searching for the Optimal Sampling Solution: Variation in Invertebrate Communities, Sample Condition and DNA Quality.

    Science.gov (United States)

    Gossner, Martin M; Struwe, Jan-Frederic; Sturm, Sarah; Max, Simeon; McCutcheon, Michelle; Weisser, Wolfgang W; Zytynska, Sharon E

    2016-01-01

    There is a great demand for standardising biodiversity assessments in order to allow optimal comparison across research groups. For invertebrates, pitfall or flight-interception traps are commonly used, but sampling solution differs widely between studies, which could influence the communities collected and affect sample processing (morphological or genetic). We assessed arthropod communities with flight-interception traps using three commonly used sampling solutions across two forest types and two vertical strata. We first considered the effect of sampling solution and its interaction with forest type, vertical stratum, and position of sampling jar at the trap on sample condition and community composition. We found that samples collected in copper sulphate were more mouldy and fragmented relative to other solutions which might impair morphological identification, but condition depended on forest type, trap type and the position of the jar. Community composition, based on order-level identification, did not differ across sampling solutions and only varied with forest type and vertical stratum. Species richness and species-level community composition, however, differed greatly among sampling solutions. Renner solution was highly attractant for beetles and repellent for true bugs. Secondly, we tested whether sampling solution affects subsequent molecular analyses and found that DNA barcoding success was species-specific. Samples from copper sulphate produced the fewest successful DNA sequences for genetic identification, and since DNA yield or quality was not particularly reduced in these samples additional interactions between the solution and DNA must also be occurring. Our results show that the choice of sampling solution should be an important consideration in biodiversity studies. Due to the potential bias towards or against certain species by Ethanol-containing sampling solution we suggest ethylene glycol as a suitable sampling solution when genetic analysis

  19. Sampling-based Algorithms for Optimal Motion Planning

    CERN Document Server

    Karaman, Sertac

    2011-01-01

    During the last decade, sampling-based path planning algorithms, such as Probabilistic RoadMaps (PRM) and Rapidly-exploring Random Trees (RRT), have been shown to work well in practice and possess theoretical guarantees such as probabilistic completeness. However, little effort has been devoted to the formal analysis of the quality of the solution returned by such algorithms, e.g., as a function of the number of samples. The purpose of this paper is to fill this gap, by rigorously analyzing the asymptotic behavior of the cost of the solution returned by stochastic sampling-based algorithms as the number of samples increases. A number of negative results are provided, characterizing existing algorithms, e.g., showing that, under mild technical conditions, the cost of the solution returned by broadly used sampling-based algorithms converges almost surely to a non-optimal value. The main contribution of the paper is the introduction of new algorithms, namely, PRM* and RRT*, which are provably asymptotically opti...

  20. Optimizing Diagnostic Yield for EUS-Guided Sampling of Solid Pancreatic Lesions: A Technical Review

    Science.gov (United States)

    Weston, Brian R.

    2013-01-01

    Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) has a higher diagnostic accuracy for pancreatic cancer than other techniques. This article will review the current advances and considerations for optimizing diagnostic yield for EUS-guided sampling of solid pancreatic lesions. Preprocedural considerations include patient history, confirmation of appropriate indication, review of imaging, method of sedation, experience required by the endoscopist, and access to rapid on-site cytologic evaluation. New EUS imaging techniques that may assist with differential diagnoses include contrast-enhanced harmonic EUS, EUS elastography, and EUS spectrum analysis. FNA techniques vary, and multiple FNA needles are now commercially available; however, neither techniques nor available FNA needles have been definitively compared. The need for suction depends on the lesion, and the need for a stylet is equivocal. No definitive endosonographic finding can predict the optimal number of passes for diagnostic yield. Preparation of good smears and communication with the cytopathologist are essential to optimize yield. PMID:23935542

  1. Enhancing sampling design in mist-net bat surveys by accounting for sample size optimization

    Science.gov (United States)

    Trevelin, Leonardo Carreira; Novaes, Roberto Leonan Morim; Colas-Rosas, Paul François; Benathar, Thayse Cristhina Melo; Peres, Carlos A.

    2017-01-01

    The advantages of mist-netting, the main technique used in Neotropical bat community studies to date, include logistical implementation, standardization and sampling representativeness. Nonetheless, study designs still have to deal with issues of detectability related to how different species behave and use the environment. Yet there is considerable sampling heterogeneity across available studies in the literature. Here, we approach the problem of sample size optimization. We evaluated the common sense hypothesis that the first six hours comprise the period of peak night activity for several species, thereby resulting in a representative sample for the whole night. To this end, we combined re-sampling techniques, species accumulation curves, threshold analysis, and community concordance of species compositional data, and applied them to datasets of three different Neotropical biomes (Amazonia, Atlantic Forest and Cerrado). We show that the strategy of restricting sampling to only six hours of the night frequently results in incomplete sampling representation of the entire bat community investigated. From a quantitative standpoint, results corroborated the existence of a major Sample Area effect in all datasets, although for the Amazonia dataset the six-hour strategy was significantly less species-rich after extrapolation, and for the Cerrado dataset it was more efficient. From the qualitative standpoint, however, results demonstrated that, for all three datasets, the identity of species that are effectively sampled will be inherently impacted by choices of sub-sampling schedule. We also propose an alternative six-hour sampling strategy (at the beginning and the end of a sample night) which performed better when resampling Amazonian and Atlantic Forest datasets on bat assemblages. Given the observed magnitude of our results, we propose that sample representativeness has to be carefully weighed against study objectives, and recommend that the trade-off between

  2. Enhancing sampling design in mist-net bat surveys by accounting for sample size optimization.

    Science.gov (United States)

    Trevelin, Leonardo Carreira; Novaes, Roberto Leonan Morim; Colas-Rosas, Paul François; Benathar, Thayse Cristhina Melo; Peres, Carlos A

    2017-01-01

    The advantages of mist-netting, the main technique used in Neotropical bat community studies to date, include logistical implementation, standardization and sampling representativeness. Nonetheless, study designs still have to deal with issues of detectability related to how different species behave and use the environment. Yet there is considerable sampling heterogeneity across available studies in the literature. Here, we approach the problem of sample size optimization. We evaluated the common sense hypothesis that the first six hours comprise the period of peak night activity for several species, thereby resulting in a representative sample for the whole night. To this end, we combined re-sampling techniques, species accumulation curves, threshold analysis, and community concordance of species compositional data, and applied them to datasets of three different Neotropical biomes (Amazonia, Atlantic Forest and Cerrado). We show that the strategy of restricting sampling to only six hours of the night frequently results in incomplete sampling representation of the entire bat community investigated. From a quantitative standpoint, results corroborated the existence of a major Sample Area effect in all datasets, although for the Amazonia dataset the six-hour strategy was significantly less species-rich after extrapolation, and for the Cerrado dataset it was more efficient. From the qualitative standpoint, however, results demonstrated that, for all three datasets, the identity of species that are effectively sampled will be inherently impacted by choices of sub-sampling schedule. We also propose an alternative six-hour sampling strategy (at the beginning and the end of a sample night) which performed better when resampling Amazonian and Atlantic Forest datasets on bat assemblages. Given the observed magnitude of our results, we propose that sample representativeness has to be carefully weighed against study objectives, and recommend that the trade-off between

  3. A mixture design approach to optimizing low cholesterol mayonnaise formulation prepared with wheat germ protein isolate.

    Science.gov (United States)

    Rahbari, Mahshid; Aalami, Mehran; Kashaninejad, Mahdi; Maghsoudlou, Yahya; Aghdaei, Seid Soheil Amiri

    2015-06-01

    The aim of this study was to optimize the mixture proportion of low cholesterol mayonnaise containing wheat germ protein isolate (WGPI) and xanthan gum (XG), as emulsifying agents in mayonnaise preparation. The mayonnaise prepared with different combinations of WGPI, egg yolk (0-9 % of each component) and XG (0-0.5 %). The optimized mixture proportions of low cholesterol mayonnaise were determined by applying the optimal mixture design method to acquire the mayonnaise with proper stability, texture, rheological properties and sensory scores. Optimum values of WGPI, XG and egg yolk in the mixture were found to be 7.87 %, 0.2 % and 0.93 %, respectively (of 9 % egg yolk). The WGPI, due to unique functional properties, had the greatest effect on properties of mayonnaise samples. Moreover, combination of XG and WGPI, improved the stability, heat stability, viscosity, consistency coefficient and textural properties of product. However, the overall acceptance was maximum in a mixture contained high amount of WGPI and XG and low amount of egg yolk. The results of this research showed the feasibility of preparation a low cholesterol mayonnaise by application a desirable combination of WGPI, XG, and egg yolk, with comparable properties those of the conventional mayonnaise.

  4. Optimal CCD readout by digital correlated double sampling

    CERN Document Server

    Alessandri, Cristobal; Guzman, Dani; Passalacqua, Ignacio; Alvarez-Fontecilla, Enrique; Guarini, Marcelo

    2015-01-01

    Digital correlated double sampling (DCDS), a readout technique for charge-coupled devices (CCD), is gaining popularity in astronomical applications. By using an oversampling ADC and a digital filter, a DCDS system can achieve a better performance than traditional analogue readout techniques at the expense of a more complex system analysis. Several attempts to analyse and optimize a DCDS system have been reported, but most of the work presented in the literature has been experimental. Some approximate analytical tools have been presented for independent parameters of the system, but the overall performance and trade-offs have not been yet modelled. Furthermore, there is disagreement among experimental results that cannot be explained by the analytical tools available. In this work, a theoretical analysis of a generic DCDS readout system is presented, including key aspects such as the signal conditioning stage, the ADC resolution, the sampling frequency and the digital filter implementation. By using a time-dom...

  5. Determining the Bayesian optimal sampling strategy in a hierarchical system.

    Energy Technology Data Exchange (ETDEWEB)

    Grace, Matthew D.; Ringland, James T.; Boggs, Paul T.; Pebay, Philippe Pierre

    2010-09-01

    Consider a classic hierarchy tree as a basic model of a 'system-of-systems' network, where each node represents a component system (which may itself consist of a set of sub-systems). For this general composite system, we present a technique for computing the optimal testing strategy, which is based on Bayesian decision analysis. In previous work, we developed a Bayesian approach for computing the distribution of the reliability of a system-of-systems structure that uses test data and prior information. This allows for the determination of both an estimate of the reliability and a quantification of confidence in the estimate. Improving the accuracy of the reliability estimate and increasing the corresponding confidence require the collection of additional data. However, testing all possible sub-systems may not be cost-effective, feasible, or even necessary to achieve an improvement in the reliability estimate. To address this sampling issue, we formulate a Bayesian methodology that systematically determines the optimal sampling strategy under specified constraints and costs that will maximally improve the reliability estimate of the composite system, e.g., by reducing the variance of the reliability distribution. This methodology involves calculating the 'Bayes risk of a decision rule' for each available sampling strategy, where risk quantifies the relative effect that each sampling strategy could have on the reliability estimate. A general numerical algorithm is developed and tested using an example multicomponent system. The results show that the procedure scales linearly with the number of components available for testing.

  6. Removal of interfering substances in samples prepared for two-dimensional (2-D) electrophoresis.

    Science.gov (United States)

    Berkelman, Tom

    2008-01-01

    Biological samples may contain contaminants that interfere with analysis by two-dimensional (2-D) electrophoresis. Lysates or biological fluids are complex mixtures that contain a wide variety of nonprotein substances in addition to the proteins to be analyzed. These substances often interfere with the resolution of the electrophoretic separation or the visualization of the result. Macromolecules (e.g., polysaccharides and DNA) can interfere with electrophoretic separation by clogging gel pores. Small ionic molecules can impair isoelectric focusing (IEF) separation by rendering the sample too conductive. Other substances (e.g., phenolics and lipids) can bind to proteins, influencing their electrophoretic properties or solubility. In many cases, measures to remove interfering substances can result in significantly clearer 2-D patterns with more visible spots and better resolution. It should be borne in mind, however, that analysis of samples by 2-D electrophoresis is usually most successful and informative when performed with minimally processed samples, so it is important that any steps taken to remove interfering substance be appropriate to the sample and only performed when necessary. Procedures for the removal of interfering substances therefore represent a compromise between removing nonprotein contaminants, and minimizing interference with the integrity and relative abundances of the sample proteins. This chapter presents a number of illustrative examples of optimized sample preparation methods in which specific interfering substances are removed by a variety of different strategies.

  7. Optimization of preparation conditions of Fe-Co nanoparticles in low-temperature CO oxidation reaction by taguchi design method

    Institute of Scientific and Technical Information of China (English)

    Abolfazl Biabani; Mehran Rezaei; Zohreh Fattah

    2012-01-01

    Mixed iron-cobalt oxide (Co/Fe molar ratio=1/5) are prepared using a simple co-precipitation procedure and studied for the catalytic oxidation of carbon monoxide.In particular,the effects of a range of preparation variables such as pH value when precipitation,aging temperature,precipitation agent type and aging time are investigated on the catalytic performance of synthesized Fe-Co oxides in CO oxidation reaction.In addition,the preparation factors were optimized by Taguchi design method.The optimized sample was characterized by XRD,N2 adsorption/desorption,TEM and TGA/DTA techniques.The results reveal that the optimized sample shows a mesoporous structure with a narrow pore size distribution centered in the range of 2-7 nm.The sample prepared under optimized conditions has high activity and stability toward removal of carbon monoxide at lower temperatures.It is shown that different preparation variables influence the catalytic performance of Fe-Co oxide in CO oxidation reaction.

  8. Neuro-genetic system for optimization of GMI samples sensitivity.

    Science.gov (United States)

    Pitta Botelho, A C O; Vellasco, M M B R; Hall Barbosa, C R; Costa Silva, E

    2016-03-01

    Magnetic sensors are largely used in several engineering areas. Among them, magnetic sensors based on the Giant Magnetoimpedance (GMI) effect are a new family of magnetic sensing devices that have a huge potential for applications involving measurements of ultra-weak magnetic fields. The sensitivity of magnetometers is directly associated with the sensitivity of their sensing elements. The GMI effect is characterized by a large variation of the impedance (magnitude and phase) of a ferromagnetic sample, when subjected to a magnetic field. Recent studies have shown that phase-based GMI magnetometers have the potential to increase the sensitivity by about 100 times. The sensitivity of GMI samples depends on several parameters, such as sample length, external magnetic field, DC level and frequency of the excitation current. However, this dependency is yet to be sufficiently well-modeled in quantitative terms. So, the search for the set of parameters that optimizes the samples sensitivity is usually empirical and very time consuming. This paper deals with this problem by proposing a new neuro-genetic system aimed at maximizing the impedance phase sensitivity of GMI samples. A Multi-Layer Perceptron (MLP) Neural Network is used to model the impedance phase and a Genetic Algorithm uses the information provided by the neural network to determine which set of parameters maximizes the impedance phase sensitivity. The results obtained with a data set composed of four different GMI sample lengths demonstrate that the neuro-genetic system is able to correctly and automatically determine the set of conditioning parameters responsible for maximizing their phase sensitivities.

  9. Evaluation of Electrospray as a Sample Preparation Tool for Electron Microscopic Investigations: Toward Quantitative Evaluation of Nanoparticles.

    Science.gov (United States)

    Mielke, Johannes; Dohányosová, Pavla; Müller, Philipp; López-Vidal, Silvia; Hodoroaba, Vasile-Dan

    2017-02-01

    The potential of electrospray deposition, for the controlled preparation of particles for imaging in electron microscopes, is evaluated on various materials: from mono-modal suspensions of spherical particles to multimodal suspensions and to real-world industrial materials. It is shown that agglomeration is reduced substantially on the sample carrier, compared with conventional sample preparation techniques. For the first time, it is possible to assess the number concentration of a tri-modal polystyrene suspension by electron microscopy, due to the high deposition efficiency of the electrospray. We discovered that some suspension stabilizing surfactants form artifact particles during electrospraying. These can be avoided by optimizing the sprayed suspension.

  10. Sample size matters: Investigating the optimal sample size for a logistic regression debris flow susceptibility model

    Science.gov (United States)

    Heckmann, Tobias; Gegg, Katharina; Becht, Michael

    2013-04-01

    Statistical approaches to landslide susceptibility modelling on the catchment and regional scale are used very frequently compared to heuristic and physically based approaches. In the present study, we deal with the problem of the optimal sample size for a logistic regression model. More specifically, a stepwise approach has been chosen in order to select those independent variables (from a number of derivatives of a digital elevation model and landcover data) that explain best the spatial distribution of debris flow initiation zones in two neighbouring central alpine catchments in Austria (used mutually for model calculation and validation). In order to minimise problems arising from spatial autocorrelation, we sample a single raster cell from each debris flow initiation zone within an inventory. In addition, as suggested by previous work using the "rare events logistic regression" approach, we take a sample of the remaining "non-event" raster cells. The recommendations given in the literature on the size of this sample appear to be motivated by practical considerations, e.g. the time and cost of acquiring data for non-event cases, which do not apply to the case of spatial data. In our study, we aim at finding empirically an "optimal" sample size in order to avoid two problems: First, a sample too large will violate the independent sample assumption as the independent variables are spatially autocorrelated; hence, a variogram analysis leads to a sample size threshold above which the average distance between sampled cells falls below the autocorrelation range of the independent variables. Second, if the sample is too small, repeated sampling will lead to very different results, i.e. the independent variables and hence the result of a single model calculation will be extremely dependent on the choice of non-event cells. Using a Monte-Carlo analysis with stepwise logistic regression, 1000 models are calculated for a wide range of sample sizes. For each sample size

  11. Human genomic DNA analysis using a semi-automated sample preparation, amplification, and electrophoresis separation platform.

    Science.gov (United States)

    Raisi, Fariba; Blizard, Benjamin A; Raissi Shabari, Akbar; Ching, Jesus; Kintz, Gregory J; Mitchell, Jim; Lemoff, Asuncion; Taylor, Mike T; Weir, Fred; Western, Linda; Wong, Wendy; Joshi, Rekha; Howland, Pamela; Chauhan, Avinash; Nguyen, Peter; Petersen, Kurt E

    2004-03-01

    The growing importance of analyzing the human genome to detect hereditary and infectious diseases associated with specific DNA sequences has motivated us to develop automated devices to integrate sample preparation, real-time PCR, and microchannel electrophoresis (MCE). In this report, we present results from an optimized compact system capable of processing a raw sample of blood, extracting the DNA, and performing a multiplexed PCR reaction. Finally, an innovative electrophoretic separation was performed on the post-PCR products using a unique MCE system. The sample preparation system extracted and lysed white blood cells (WBC) from whole blood, producing DNA of sufficient quantity and quality for a polymerase chain reaction (PCR). Separation of multiple amplicons was achieved in a microfabricated channel 30 microm x 100 microm in cross section and 85 mm in length filled with a replaceable methyl cellulose matrix operated under denaturing conditions at 50 degrees C. By incorporating fluorescent-labeled primers in the PCR, the amplicons were identified by a two-color (multiplexed) fluorescence detection system. Two base-pair resolution of single-stranded DNA (PCR products) was achieved. We believe that this integrated system provides a unique solution for DNA analysis.

  12. Sample preparation for laser-microdissection of soybean shoot apical meristem

    Directory of Open Access Journals (Sweden)

    Chui E. Wong

    2012-10-01

    Full Text Available The shoot apical meristem houses stem cells responsible for the continuous formation of aerial plant organs including leaves and stems throughout the life of plants. Laser-microdissection in combination with high-throughput technology such as next generation sequencing permits an in-depth analysis of molecular events associated with specific cell type of interest. Sample preparation is the most critical step in ensuring good quality RNA to be extracted from samples following laser-microdissection. Here, we optimized the sample preparation for a major legume crop, soybean. We used Farmer’s solution as a fixative and paraffin as the embedding medium for soybean shoot apical meristem tissue without the use of any specialized equipment. Shorter time for tissue fixation (two days was found to be critical for the preservation of RNA in soybean shoot apical meristem. We further demonstrated the utility of this method for different tissues derived from soybean and rice. The method outlined here shall facilitate studies on crop plants involving laser-microdissection.

  13. Automatic, optimized interface placement in forward flux sampling simulations

    CERN Document Server

    Kratzer, Kai; Allen, Rosalind J

    2013-01-01

    Forward flux sampling (FFS) provides a convenient and efficient way to simulate rare events in equilibrium or non-equilibrium systems. FFS ratchets the system from an initial state to a final state via a series of interfaces in phase space. The efficiency of FFS depends sensitively on the positions of the interfaces. We present two alternative methods for placing interfaces automatically and adaptively in their optimal locations, on-the-fly as an FFS simulation progresses, without prior knowledge or user intervention. These methods allow the FFS simulation to advance efficiently through bottlenecks in phase space by placing more interfaces where the probability of advancement is lower. The methods are demonstrated both for a single-particle test problem and for the crystallization of Yukawa particles. By removing the need for manual interface placement, our methods both facilitate the setting up of FFS simulations and improve their performance, especially for rare events which involve complex trajectories thr...

  14. Robust Estimation of Diffusion-Optimized Ensembles for Enhanced Sampling

    DEFF Research Database (Denmark)

    Tian, Pengfei; Jónsson, Sigurdur Æ.; Ferkinghoff-Borg, Jesper

    2014-01-01

    The multicanonical, or flat-histogram, method is a common technique to improve the sampling efficiency of molecular simulations. The idea is that free-energy barriers in a simulation can be removed by simulating from a distribution where all values of a reaction coordinate are equally likely......, and subsequently reweight the obtained statistics to recover the Boltzmann distribution at the temperature of interest. While this method has been successful in practice, the choice of a flat distribution is not necessarily optimal. Recently, it was proposed that additional performance gains could be obtained...... by taking the position-dependent diffusion coefficient into account, thus placing greater emphasis on regions diffusing slowly. Although some promising examples of applications of this approach exist, the practical usefulness of the method has been hindered by the difficulty in obtaining sufficiently...

  15. Closer to the native state. Critical evaluation of cryo-techniques for Transmission Electron Microscopy: preparation of biological samples.

    Science.gov (United States)

    Mielanczyk, Lukasz; Matysiak, Natalia; Michalski, Marek; Buldak, Rafal; Wojnicz, Romuald

    2014-01-01

    Over the years Transmission Electron Microscopy (TEM) has evolved into a powerful technique for the structural analysis of cells and tissues at various levels of resolution. However, optimal sample preservation is required to achieve results consistent with reality. During the last few decades, conventional preparation methods have provided most of the knowledge about the ultrastructure of organelles, cells and tissues. Nevertheless, some artefacts can be introduced at all stagesofstandard electron microscopy preparation technique. Instead, rapid freezing techniques preserve biological specimens as close as possible to the native state. Our review focuses on different cryo-preparation approaches, starting from vitrification methods dependent on sample size. Afterwards, we discuss Cryo-Electron Microscopy Of VItreous Sections (CEMOVIS) and the main difficulties associated with this technique. Cryo-Focused Ion Beam (cryo-FIB) is described as a potential alternative for CEMOVIS. Another post-processing route for vitrified samples is freeze substitution and embedding in resin for structural analysis or immunolocalization analysis. Cryo-sectioning according to Tokuyasu is a technique dedicated to high efficiency immunogold labelling. Finally, we introduce hybrid techniques, which combine advantages of primary techniques originally dedicated to different approaches. Hybrid approaches permit to perform the study of difficult-to-fix samples and antigens or help optimize the sample preparation protocol for the integrated Laser and Electron Microscopy (iLEM) technique.

  16. Amphiphilic mediated sample preparation for micro-flow cytometry

    Energy Technology Data Exchange (ETDEWEB)

    Clague, David S. (Livermore, CA); Wheeler, Elizabeth K. (Livermore, CA); Lee, Abraham P. (Irvine, CA)

    2009-03-17

    A flow cytometer includes a flow cell for detecting the sample, an oil phase in the flow cell, a water phase in the flow cell, an oil-water interface between the oil phase and the water phase, a detector for detecting the sample at the oil-water interface, and a hydrophobic unit operatively connected to the sample. The hydrophobic unit is attached to the sample. The sample and the hydrophobic unit are placed in an oil and water combination. The sample is detected at the interface between the oil phase and the water phase.

  17. New Sample Preparation Method for Quantification of Phenolic Compounds of Tea (Camellia sinensis L. Kuntze: A Polyphenol Rich Plant

    Directory of Open Access Journals (Sweden)

    P. A. Nimal Punyasiri

    2015-01-01

    Full Text Available Chemical analysis of the Sri Lankan tea (Camellia sinensis, L. germplasm would immensely contribute to the success of the tea breeding programme. However, the polyphenols, particularly catechins (flavan-3-ols, are readily prone to oxidation in the conventional method of sample preparation. Therefore, optimization of the present sample preparation methodology for the profiling of metabolites is much important. Two sample preparation methodologies were compared, fresh leaves (as in the conventional procedures and freeze-dried leaves (a new procedure, for quantification of major metabolites by employing two cultivars, one is known to be high quality black tea and the other low quality black tea. The amounts of major metabolites such as catechins, caffeine, gallic acid, and theobromine, recorded in the new sampling procedure via freeze-dried leaves, were significantly higher than those recorded in the conventional sample preparation procedure. Additionally new method required less amount of leaf sample for analysis of major metabolites and facilitates storage of samples until analysis. The freeze-dried method would be useful for high throughput analysis of large number of samples in shorter period without chemical deterioration starting from the point of harvest until usage. Hence, this method is more suitable for metabolite profiling of tea as well as other phenol rich plants.

  18. Final LDRD report : development of sample preparation methods for ChIPMA-based imaging mass spectrometry of tissue samples.

    Energy Technology Data Exchange (ETDEWEB)

    Maharrey, Sean P.; Highley, Aaron M.; Behrens, Richard, Jr.; Wiese-Smith, Deneille

    2007-12-01

    The objective of this short-term LDRD project was to acquire the tools needed to use our chemical imaging precision mass analyzer (ChIPMA) instrument to analyze tissue samples. This effort was an outgrowth of discussions with oncologists on the need to find the cellular origin of signals in mass spectra of serum samples, which provide biomarkers for ovarian cancer. The ultimate goal would be to collect chemical images of biopsy samples allowing the chemical images of diseased and nondiseased sections of a sample to be compared. The equipment needed to prepare tissue samples have been acquired and built. This equipment includes an cyro-ultramicrotome for preparing thin sections of samples and a coating unit. The coating unit uses an electrospray system to deposit small droplets of a UV-photo absorbing compound on the surface of the tissue samples. Both units are operational. The tissue sample must be coated with the organic compound to enable matrix assisted laser desorption/ionization (MALDI) and matrix enhanced secondary ion mass spectrometry (ME-SIMS) measurements with the ChIPMA instrument Initial plans to test the sample preparation using human tissue samples required development of administrative procedures beyond the scope of this LDRD. Hence, it was decided to make two types of measurements: (1) Testing the spatial resolution of ME-SIMS by preparing a substrate coated with a mixture of an organic matrix and a bio standard and etching a defined pattern in the coating using a liquid metal ion beam, and (2) preparing and imaging C. elegans worms. Difficulties arose in sectioning the C. elegans for analysis and funds and time to overcome these difficulties were not available in this project. The facilities are now available for preparing biological samples for analysis with the ChIPMA instrument. Some further investment of time and resources in sample preparation should make this a useful tool for chemical imaging applications.

  19. An On-Target Desalting and Concentration Sample Preparation Protocol for MALDI-MS and MS/MS Analysis

    DEFF Research Database (Denmark)

    Zhang, Xumin; Wang, Quanhui; Lou, Xiaomin;

    2012-01-01

    2DE coupled with MALDI-MS is one of the most widely used and powerful analytic technologies in proteomics study. The MALDI sample preparation method has been developed and optimized towards the combination of simplicity, sample-cleaning, and sample concentration since its introduction. Here we...... present a protocol of the so-called Sample loading, Matrix loading, and on-target Wash (SMW) method which fulfills the three criteria by taking advantage of the AnchorChip™ targets. Our method is extremely simple and no pre-desalting or concentration is needed when dealing with samples prepared from 2DE....... The protocol is amendable for automation and would pave the road for high-throughput MALDI-MS or MS/MS-based proteomics studies with guaranteed sensitivity and high identification rate. The method has been successfully applied to mouse liver proteome study and so far has been employed in other proteome studies...

  20. Optimizing coverage of metal oxide nanoparticle prepared by pulsed laser deposition on nonenzymatic glucose detection.

    Science.gov (United States)

    Kaneko, Satoru; Ito, Takeshi; Hirabayashi, Yasuo; Ozawa, Takeshi; Okuda, Tetsuya; Motoizumi, Yu; Hirai, Kiyohito; Naganuma, Yasuhiro; Soga, Masayasu; Yoshimoto, Mamoru; Suzuki, Koji

    2011-04-15

    Metal oxide nanoparticles prepared by pulsed laser deposition (PLD) were applied to nonenzymatic glucose detection. NiO nanoparticles with size of 3 nm were deposited on glassy carbon (GC) and silicon substrates at room temperature in an oxygen atmosphere. Transmission electron microscope (TEM) image showed nanoparticles with the size of 3 nm uniformly scattered on the Si(001) substrate. Unlike co-sputtering nanoparticle and carbon simultaneously, the PLD method can easily control the surface coverage of nanoparticles on the surface of substrate by deposition time. Cyclic voltammetry was performed on the samples deposited on the GC substrates for electrochemical detection of glucose. The differences between peak currents with and without glucose was used to optimize the coverage of nanoparticles on carbon electrode. The results indicated that optimal coverage of nanoparticles on carbon electrode.

  1. Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality: A novel statistical approach for quality scoring.

    Science.gov (United States)

    Kooijman, Pieter C; Kok, Sander J; Weusten, Jos J A M; Honing, Maarten

    2016-05-05

    Preparation of samples according to an optimized method is crucial for accurate determination of polymer sample characteristics by Matrix-Assisted Laser Desorption Ionization (MALDI) analysis. Sample preparation conditions such as matrix choice, cationization agent, deposition technique or even the deposition volume should be chosen to suit the sample of interest. Many sample preparation protocols have been developed and employed, yet finding the optimal sample preparation protocol remains a challenge. Because an objective comparison between the results of diverse protocols is not possible, "gut-feeling" or "good enough" is often decisive in the search for an optimum. This implies that sub-optimal protocols are used, leading to a loss of mass spectral information quality. To address this problem a novel analytical strategy based on MALDI imaging and statistical data processing was developed in which eight parameters were formulated to objectively quantify the quality of sample deposition and optimal MALDI matrix composition and finally sum up to an overall quality score of the sample deposition. These parameters can be established in a fully automated way using commercially available mass spectrometry imaging instruments without any hardware adjustments. With the newly developed analytical strategy the highest quality MALDI spots were selected, resulting in more reproducible and more valuable spectra for PEG in a variety of matrices. Moreover, our method enables an objective comparison of sample preparation protocols for any analyte and opens up new fields of investigation by presenting MALDI performance data in a clear and concise way.

  2. Optimization and Evaluation Strategy of Esophageal Tissue Preparation Protocols for Metabolomics by LC-MS.

    Science.gov (United States)

    Wang, Huiqing; Xu, Jing; Chen, Yanhua; Zhang, Ruiping; He, Jiuming; Wang, Zhonghua; Zang, Qingce; Wei, Jinfeng; Song, Xiaowei; Abliz, Zeper

    2016-04-01

    Sample preparation is a critical step in tissue metabolomics. Therefore, a comprehensive and systematic strategy for the screening of tissue preparation protocols is highly desirable. In this study, we developed an Optimization and Evaluation Strategy based on LC-MS to screen for a high-extractive efficiency and reproducible esophageal tissue preparation protocol for different types of endogenous metabolites (amino acids, carnitines, cholines, etc.), with a special focus on low-level metabolites. In this strategy, we first selected a large number of target metabolites based on literature survey, previous work in our lab, and known metabolic pathways. For these target metabolites, we tested different solvent extraction methods (biphasic solvent extraction, two-step [TS], stepwise [SW], all-in one [AO]; single-phase solvent extraction, SP) and esophageal tissue disruption methods (homogenized wet tissue [HW], ground wet tissue [GW], and ground dry tissue [GD]). A protocol involving stepwise addition of solvents and a homogenized wet tissue protocol (SWHW) was superior to the others. Finally, we evaluated the stability of endogenous metabolites in esophageal tissues and the sensitivity, reproducibility, and recovery of the optimal protocol. The results proved that the SWHW protocol was robust and adequate for bioanalysis. This strategy will provide important guidance for the standardized and scientific investigation of tissue metabolomics.

  3. A comparison of sample preparation strategies for biological tissues and subsequent trace element analysis using LA-ICP-MS.

    Science.gov (United States)

    Bonta, Maximilian; Török, Szilvia; Hegedus, Balazs; Döme, Balazs; Limbeck, Andreas

    2017-03-01

    Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) is one of the most commonly applied methods for lateral trace element distribution analysis in medical studies. Many improvements of the technique regarding quantification and achievable lateral resolution have been achieved in the last years. Nevertheless, sample preparation is also of major importance and the optimal sample preparation strategy still has not been defined. While conventional histology knows a number of sample pre-treatment strategies, little is known about the effect of these approaches on the lateral distributions of elements and/or their quantities in tissues. The technique of formalin fixation and paraffin embedding (FFPE) has emerged as the gold standard in tissue preparation. However, the potential use for elemental distribution studies is questionable due to a large number of sample preparation steps. In this work, LA-ICP-MS was used to examine the applicability of the FFPE sample preparation approach for elemental distribution studies. Qualitative elemental distributions as well as quantitative concentrations in cryo-cut tissues as well as FFPE samples were compared. Results showed that some metals (especially Na and K) are severely affected by the FFPE process, whereas others (e.g., Mn, Ni) are less influenced. Based on these results, a general recommendation can be given: FFPE samples are completely unsuitable for the analysis of alkaline metals. When analyzing transition metals, FFPE samples can give comparable results to snap-frozen tissues. Graphical abstract Sample preparation strategies for biological tissues are compared with regard to the elemental distributions and average trace element concentrations.

  4. A mixture design approach to optimizing low cholesterol mayonnaise formulation prepared with wheat germ protein isolate

    OpenAIRE

    Rahbari, Mahshid; Aalami, Mehran; Kashaninejad, Mahdi; Maghsoudlou, Yahya; Aghdaei, Seid Soheil Amiri

    2014-01-01

    The aim of this study was to optimize the mixture proportion of low cholesterol mayonnaise containing wheat germ protein isolate (WGPI) and xanthan gum (XG), as emulsifying agents in mayonnaise preparation. The mayonnaise prepared with different combinations of WGPI, egg yolk (0–9 % of each component) and XG (0–0.5 %). The optimized mixture proportions of low cholesterol mayonnaise were determined by applying the optimal mixture design method to acquire the mayonnaise with proper stability, t...

  5. NGSI FY15 Final Report. Innovative Sample Preparation for in-Field Uranium Isotopic Determinations

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Thomas M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Meyers, Lisa [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-10

    Our FY14 Final Report included an introduction to the project, background, literature search of uranium dissolution methods, assessment of commercial off the shelf (COTS) automated sample preparation systems, as well as data and results for dissolution of bulk quantities of uranium oxides, and dissolution of uranium oxides from swipe filter materials using ammonium bifluoride (ABF). Also, discussed were reaction studies of solid ABF with uranium oxide that provided a basis for determining the ABF/uranium oxide dissolution mechanism. This report details the final experiments for optimizing dissolution of U3O8 and UO2 using ABF and steps leading to development of a Standard Operating Procedure (SOP) for dissolution of uranium oxides on swipe filters.

  6. RNA SAMPLE PREPARATION APPLIED TO GENE EXPRESSION PROFILING FOR THE HORSE BIOLOGICAL PASSPORT.

    Science.gov (United States)

    Bailly-Chouriberry, Ludovic; Baudoin, Florent; Cormant, Florence; Glavieux, Yohan; Loup, Benoit; Garcia, Patrice; Popot, Marie-Agnès; Bonnaire, Yves

    2017-04-05

    The improvement of doping control is an on-going race. Techniques to fight against doping are usually based on the direct detection of drugs or their metabolites by analytical methods such as chromatography hyphenated to mass spectrometry after ad hoc sample preparation. Nowadays, omic methods constitute an attractive development and advances have been achieved particularly by application of molecular biology tools for detection of anabolic androgenic steroids (AAS), erythropoiesis-stimulating agent (ESA) or to control human growth hormone misuses. These interesting results across different animal species have suggested that modification of gene expression offers promising new methods of improving the window of detection of banned substances by targeting their effects on blood cell gene expression. In this context, the present study describes the possibility of using a modified version of the dedicated Human IVD (in vitro Diagnostics) PAXgene® Blood RNA Kit for horse gene expression analysis in blood collected on PAXgene® tubes applied to the Horse Biological Passport. The commercial kit was only approved for human blood samples and has required an optimization of specific technical requirements for equine blood samples. Improvements and recommendations were achieved for sample collection, storage and RNA extraction procedure. Following these developments, RNA yield and quality were demonstrated to be suitable for downstream gene expression analysis by qPCR techniques.

  7. Preview of the NASA NNWG NDE Sample Preparation Handbook

    Science.gov (United States)

    2010-01-01

    This viewgraph presents a step-by-step how-to fabrication documentation of every kind of sample that is fabricated for MSFC by UA Huntsville, including photos and illustrations. The tabulation of what kind of samples are being fabricated for what NDE method, detailed instructions/documentation of the inclusion/creation of defects, detailed specifications for materials, processes, and equipment, case histories and/or experiences with the different fabrication methods and defect inclusion techniques, discussion of pitfalls and difficulties associated with sample fabrication and defect inclusion techniques, and a discussion of why certain fabrication techniques are needed as related to the specific NDE methods are included in this presentation.

  8. Sample Preparation (SS): SE45_SS01 [Metabolonote[Archive

    Lifescience Database Archive (English)

    Full Text Available tration of 15 ng µl-1 for each 1-µl injection. After 5-min centrifugation at 15,1...0 mg/ml in pyridine) was added to the sample. After 24 h of derivatization at room temperature, the sample w...µl of methoxyamine hydrochloride (20 mg ml-1 in pyridine) were added to the sample. After 24 h of derivatiza...f MSTFA at 37°C with shaking. After silylation 30 µl of n-heptane were added. All derivatization steps were

  9. Martian Radiative Transfer Modeling Using the Optimal Spectral Sampling Method

    Science.gov (United States)

    Eluszkiewicz, J.; Cady-Pereira, K.; Uymin, G.; Moncet, J.-L.

    2005-01-01

    The large volume of existing and planned infrared observations of Mars have prompted the development of a new martian radiative transfer model that could be used in the retrievals of atmospheric and surface properties. The model is based on the Optimal Spectral Sampling (OSS) method [1]. The method is a fast and accurate monochromatic technique applicable to a wide range of remote sensing platforms (from microwave to UV) and was originally developed for the real-time processing of infrared and microwave data acquired by instruments aboard the satellites forming part of the next-generation global weather satellite system NPOESS (National Polarorbiting Operational Satellite System) [2]. As part of our on-going research related to the radiative properties of the martian polar caps, we have begun the development of a martian OSS model with the goal of using it to perform self-consistent atmospheric corrections necessary to retrieve caps emissivity from the Thermal Emission Spectrometer (TES) spectra. While the caps will provide the initial focus area for applying the new model, it is hoped that the model will be of interest to the wider Mars remote sensing community.

  10. Sample Preparation (SS): SE55_SS01 [Metabolonote[Archive

    Lifescience Database Archive (English)

    Full Text Available 80℃ until analysis. The frozen tissues were homogenized in five volumes of 80% aqueous methanol containing 0...SE55_SS01 Metabolic profiling Collected sample tissues were weighed and stored at -

  11. Sample Preparation for Monolithic Refractories Part 1: Refractory Castables

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiaohui; Peng Xigao

    2010-01-01

    @@ 1 Scope This standard specifies the definition and test methods of flowability of dense and insulating refractory castables,and moulding equipment,moulding methods,curing and drying conditions of castables samples.

  12. Sample Preparation (SS): SE52_SS01 [Metabolonote[Archive

    Lifescience Database Archive (English)

    Full Text Available Tokyo, Japan) using a mixer mill (MM 300, Retsch) with a zirconia bead for 6 min... at 20 Hz. Next, the samples were centrifuged at 15,000 g for 10 min and filtered (Ultrafree-MC filter, 0.2 μm; Mil...lipore, Bedford, MA, USA). The sample extracts were then applied to an HLB μElution plate (Waters, Mil

  13. Automated Gel Size Selection to Improve the Quality of Next-generation Sequencing Libraries Prepared from Environmental Water Samples.

    Science.gov (United States)

    Uyaguari-Diaz, Miguel I; Slobodan, Jared R; Nesbitt, Matthew J; Croxen, Matthew A; Isaac-Renton, Judith; Prystajecky, Natalie A; Tang, Patrick

    2015-04-17

    Next-generation sequencing of environmental samples can be challenging because of the variable DNA quantity and quality in these samples. High quality DNA libraries are needed for optimal results from next-generation sequencing. Environmental samples such as water may have low quality and quantities of DNA as well as contaminants that co-precipitate with DNA. The mechanical and enzymatic processes involved in extraction and library preparation may further damage the DNA. Gel size selection enables purification and recovery of DNA fragments of a defined size for sequencing applications. Nevertheless, this task is one of the most time-consuming steps in the DNA library preparation workflow. The protocol described here enables complete automation of agarose gel loading, electrophoretic analysis, and recovery of targeted DNA fragments. In this study, we describe a high-throughput approach to prepare high quality DNA libraries from freshwater samples that can be applied also to other environmental samples. We used an indirect approach to concentrate bacterial cells from environmental freshwater samples; DNA was extracted using a commercially available DNA extraction kit, and DNA libraries were prepared using a commercial transposon-based protocol. DNA fragments of 500 to 800 bp were gel size selected using Ranger Technology, an automated electrophoresis workstation. Sequencing of the size-selected DNA libraries demonstrated significant improvements to read length and quality of the sequencing reads.

  14. Recent developments on field gas extraction and sample preparation methods for radiokrypton dating of groundwater

    Science.gov (United States)

    Yokochi, Reika

    2016-09-01

    Current and foreseen population growths will lead to an increased demand in freshwater, large quantities of which is stored as groundwater. The ventilation age is crucial to the assessment of groundwater resources, complementing the hydrological model approach based on hydrogeological parameters. Ultra-trace radioactive isotopes of Kr (81 Kr and 85 Kr) possess the ideal physical and chemical properties for groundwater dating. The recent advent of atom trap trace analyses (ATTA) has enabled determination of ultra-trace noble gas radioisotope abundances using 5-10 μ L of pure Kr. Anticipated developments will enable ATTA to analyze radiokrypton isotope abundances at high sample throughput, which necessitates simple and efficient sample preparation techniques that are adaptable to various sample chemistries. Recent developments of field gas extraction devices and simple and rapid Kr separation method at the University of Chicago are presented herein. Two field gas extraction devices optimized for different sampling conditions were recently designed and constructed, aiming at operational simplicity and portability. A newly developed Kr purification system enriches Kr by flowing a sample gas through a moderately cooled (138 K) activated charcoal column, followed by a gentle fractionating desorption. This simple process uses a single adsorbent and separates 99% of the bulk atmospheric gases from Kr without significant loss. The subsequent two stages of gas chromatographic separation and a hot Ti sponge getter further purify the Kr-enriched gas. Abundant CH4 necessitates multiple passages through one of the gas chromatographic separation columns. The presented Kr separation system has a demonstrated capability of extracting Kr with > 90% yield and 99% purity within 75 min from 1.2 to 26.8 L STP of atmospheric air with various concentrations of CH4. The apparatuses have successfully been deployed for sampling in the field and purification of groundwater samples.

  15. Optimal Selection of the Sampling Interval for Estimation of Modal Parameters by an ARMA- Model

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning

    1993-01-01

    Optimal selection of the sampling interval for estimation of the modal parameters by an ARMA-model for a white noise loaded structure modelled as a single degree of- freedom linear mechanical system is considered. An analytical solution for an optimal uniform sampling interval, which is optimal...... in a Fisherian sense, is given. The solution is investigated by a simulation study. It is shown that if the experimental length T1 is fixed it may be useful to sample the record at a high sampling rate, since more measurements from the system are then collected. No optimal sampling interval exists....... But if the total number of sample points N is fixed an optimal sampling interval exists. Then it is far worse to use a too large sampling interval than a too small one since the information losses increase rapidly when the sampling interval increases from the optimal value....

  16. COMPARISON OF SAMPLE PREPARATION METHODS FOR CHIP-CHIP ASSAYS

    OpenAIRE

    O'Geen, Henriette; Nicolet, Charles M.; Blahnik, Kim; Green, Roland; Farnham, Peggy J.

    2006-01-01

    A single ChIP sample does not provide enough DNA for hybridization to a genomic tiling array. A commonly used technique for amplifying the DNA obtained from ChIP assays is linker-mediated PCR (LMPCR). However, using this amplification method, we could not identify Oct4 binding sites on genomic tiling arrays representing 1% of the human genome (ENCODE arrays). In contrast, hybridization of a pool of 10 ChIP samples to the arrays produced reproducible binding patterns and low background signals...

  17. Microfluidic desalination. Capacitive deionization on chip for microfluidic sample preparation

    NARCIS (Netherlands)

    Roelofs, Susan Helena

    2015-01-01

    The main aim of the work described in this thesis is to implement the desalination technique capacitive deionization (CDI) on a microfluidic chip to improve the reproducibility in the analysis of biological samples for drug development. Secondly, microfluidic CDI allows for the in situ study of ion

  18. Effects of Sample Preparation on the Infrared Reflectance Spectra of Powders

    Energy Technology Data Exchange (ETDEWEB)

    Brauer, Carolyn S.; Johnson, Timothy J.; Myers, Tanya L.; Su, Yin-Fong; Blake, Thomas A.; Forland, Brenda M.

    2015-05-22

    While reflectance spectroscopy is a useful tool in identifying molecular compounds, laboratory measurement of solid (particularly powder) samples often is confounded by sample preparation methods. For example, both the packing density and surface roughness can have an effect on the quantitative reflectance spectra of powdered samples. Recent efforts in our group have focused on developing standard methods for measuring reflectance spectra that accounts for sample preparation, as well as other factors such as particle size and provenance. In this work, the effect of preparation method on sample reflectivity was investigated by measuring the directional-hemispherical spectra of samples that were hand-packed as well as pressed into pellets using an integrating sphere attached to a Fourier transform infrared spectrometer. The results show that the methods used to prepare the sample have a substantial effect on the measured reflectance spectra, as do other factors such as particle size.

  19. Sample preparation and assay refinements for pathogen detection platforms

    Science.gov (United States)

    Lim, Daniel V.; Kearns, Elizabeth A.; Leskinen, Stephaney D.; Magaña, Sonia; Stroot, Joyce M.; Hunter, Dawn M.; Schlemmer, Sarah M.

    2009-02-01

    Food-borne and waterborne microbial pathogens are a potential problem in biowarfare and public health. Such pathogens can affect the health, combat readiness, and effectiveness of the warfighter in a battlefield environment and present potential threats to the civilian population through intentional or natural contamination of food and water. Conventional procedures to detect and identify microbial pathogens in food, water, and other materials can take days to perform and may provide inconclusive information. Research at the University of South Florida's Advanced Biosensors Laboratory (ABL) focuses on development of sample processing procedures and biosensor-based assays for rapid detection of biothreat agents. Rapid processing methods, including use of an automated concentrator of microorganisms in water, have been developed for complex matrix samples including ground beef, apple juice, produce, potable water and recreational water, enabling such samples to be directly tested by biosensor assays for target analytes. Bacillus atrophaeus spores and other bacteria can be concentrated from potable and recreational water at low levels with a dead-end hollow-fiber ultrafiltration concentration system. Target bacteria recovered by these processing procedures can be identified by evanescent wave, fiber optic biosensors or other detection platforms. Fiber optic biosensor assays have been improved to include subsequent PCR analysis and viability determination of captured target bacteria using broth enrichment and/or ATP luminescence.

  20. Quantitative analysis of intermediately and infinitely thick samples with thin sample approach without sample preparation using confocal X-ray fluorescence

    CERN Document Server

    Sun, Xue-Peng; Sun, Tian-Xi; Peng, Song; Sun, Wei-Yuan; Li, Fang-Zuo; Jiang, Bo-Wen; Ma, Yong-Zhong; Ding, Xun-Liang

    2015-01-01

    In order to validate that the confocal X-ray fluorescence had potential applications in analyzing the intermediately and infinitely thick samples with thin sample approach without sample preparations, as an example, the confocal X-ray fluorescence based on polycapillary X-ray optics was used to analyze multi elements solutions.

  1. Adjustable virtual pore-size filter for automated sample preparation using acoustic radiation force

    Energy Technology Data Exchange (ETDEWEB)

    Jung, B; Fisher, K; Ness, K; Rose, K; Mariella, R

    2008-05-22

    We present a rapid and robust size-based separation method for high throughput microfluidic devices using acoustic radiation force. We developed a finite element modeling tool to predict the two-dimensional acoustic radiation force field perpendicular to the flow direction in microfluidic devices. Here we compare the results from this model with experimental parametric studies including variations of the PZT driving frequencies and voltages as well as various particle sizes and compressidensities. These experimental parametric studies also provide insight into the development of an adjustable 'virtual' pore-size filter as well as optimal operating conditions for various microparticle sizes. We demonstrated the separation of Saccharomyces cerevisiae and MS2 bacteriophage using acoustic focusing. The acoustic radiation force did not affect the MS2 viruses, and their concentration profile remained unchanged. With optimized design of our microfluidic flow system we were able to achieve yields of > 90% for the MS2 with > 80% of the S. cerevisiae being removed in this continuous-flow sample preparation device.

  2. Optimal Selection of the Sampling Interval for Estimation of Modal Parameters by an ARMA- Model

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning

    1993-01-01

    Optimal selection of the sampling interval for estimation of the modal parameters by an ARMA-model for a white noise loaded structure modelled as a single degree of- freedom linear mechanical system is considered. An analytical solution for an optimal uniform sampling interval, which is optimal...

  3. Sample-Path Optimization of Buffer Allocations in a Tandem Queue - Part I : Theoretical Issues

    NARCIS (Netherlands)

    Gürkan, G.; Ozge, A.Y.

    1996-01-01

    This is the first of two papers dealing with the optimal bu er allocation problem in tandem manufacturing lines with unreliable machines.We address the theoretical issues that arise when using sample-path optimization, a simulation-based optimization method, to solve this problem.Sample-path optimiz

  4. Global metabolite analysis of yeast: evaluation of sample preparation methods

    DEFF Research Database (Denmark)

    Villas-Bôas, Silas Granato; Højer-Pedersen, Jesper; Åkesson, Mats Fredrik;

    2005-01-01

    , which is the analysis of a large number of metabolites with very diverse chemical and physical properties. This work reports the leakage of intracellular metabolites observed during quenching yeast cells with cold methanol solution, the efficacy of six different methods for the extraction...... of intracellular metabolites, and the losses noticed during sample concentration by lyophilization and solvent evaporation. A more reliable procedure is suggested for quenching yeast cells with cold methanol solution, followed by extraction of intracellular metabolites by pure methanol. The method can be combined...

  5. Sample preparation of metal alloys by electric discharge machining

    Science.gov (United States)

    Chapman, G. B., II; Gordon, W. A.

    1976-01-01

    Electric discharge machining was investigated as a noncontaminating method of comminuting alloys for subsequent chemical analysis. Particulate dispersions in water were produced from bulk alloys at a rate of about 5 mg/min by using a commercially available machining instrument. The utility of this approach was demonstrated by results obtained when acidified dispersions were substituted for true acid solutions in an established spectrochemical method. The analysis results were not significantly different for the two sample forms. Particle size measurements and preliminary results from other spectrochemical methods which require direct aspiration of liquid into flame or plasma sources are reported.

  6. Current advances and strategies towards fully automated sample preparation for regulated LC-MS/MS bioanalysis.

    Science.gov (United States)

    Zheng, Naiyu; Jiang, Hao; Zeng, Jianing

    2014-09-01

    Robotic liquid handlers (RLHs) have been widely used in automated sample preparation for liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioanalysis. Automated sample preparation for regulated bioanalysis offers significantly higher assay efficiency, better data quality and potential bioanalytical cost-savings. For RLHs that are used for regulated bioanalysis, there are additional requirements, including 21 CFR Part 11 compliance, software validation, system qualification, calibration verification and proper maintenance. This article reviews recent advances in automated sample preparation for regulated bioanalysis in the last 5 years. Specifically, it covers the following aspects: regulated bioanalysis requirements, recent advances in automation hardware and software development, sample extraction workflow simplification, strategies towards fully automated sample extraction, and best practices in automated sample preparation for regulated bioanalysis.

  7. Status report of AMS sample preparation laboratory at GADAM Centre, Gliwice, Poland

    Energy Technology Data Exchange (ETDEWEB)

    Piotrowska, N., E-mail: natalia.piotrowska@polsl.pl [GADAM Centre of Excellence, Department of Radioisotopes, Institute of Physics, Silesian University of Technology, Gliwice (Poland)

    2013-01-15

    The laboratory for {sup 14}C AMS sample preparation in the Gliwice Radiocarbon Laboratory has gradually evolved since its start in 1999 to cater for an increase in volume and variety of radiocarbon dating samples. To date, nearly 2000 graphite targets have been produced from materials such as plant macrofossils, charcoal, peat, bones, shells and wood. The equipment comprises a station for chemical preparation and high vacuum lines for production, purification and graphitization of sample carbon dioxide. The present capacity allows preparation of up to 400 targets annually for the needs of scientific projects and external orders for radiocarbon dating continuously received by the GADAM Centre of Excellence. The laboratory's sample preparation protocols and recent improvements are described and its performance during the 10 years of activity is discussed in terms of parameters obtained from reference materials prepared in this laboratory and demonstrated with a few science applications.

  8. Intelligent front-end sample preparation tool using acoustic streaming.

    Energy Technology Data Exchange (ETDEWEB)

    Cooley, Erika J.; McClain, Jaime L.; Murton, Jaclyn K.; Edwards, Thayne L.; Achyuthan, Komandoor E.; Branch, Darren W.; Clem, Paul Gilbert; Anderson, John Mueller; James, Conrad D.; Smith, Gennifer; Kotulski, Joseph Daniel

    2009-09-01

    We have successfully developed a nucleic acid extraction system based on a microacoustic lysis array coupled to an integrated nucleic acid extraction system all on a single cartridge. The microacoustic lysing array is based on 36{sup o} Y cut lithium niobate, which couples bulk acoustic waves (BAW) into the microchannels. The microchannels were fabricated using Mylar laminates and fused silica to form acoustic-fluidic interface cartridges. The transducer array consists of four active elements directed for cell lysis and one optional BAW element for mixing on the cartridge. The lysis system was modeled using one dimensional (1D) transmission line and two dimensional (2D) FEM models. For input powers required to lyse cells, the flow rate dictated the temperature change across the lysing region. From the computational models, a flow rate of 10 {micro}L/min produced a temperature rise of 23.2 C and only 6.7 C when flowing at 60 {micro}L/min. The measured temperature changes were 5 C less than the model. The computational models also permitted optimization of the acoustic coupling to the microchannel region and revealed the potential impact of thermal effects if not controlled. Using E. coli, we achieved a lysing efficacy of 49.9 {+-} 29.92 % based on a cell viability assay with a 757.2 % increase in ATP release within 20 seconds of acoustic exposure. A bench-top lysing system required 15-20 minutes operating up to 58 Watts to achieve the same level of cell lysis. We demonstrate that active mixing on the cartridge was critical to maximize binding and release of nucleic acid to the magnetic beads. Using a sol-gel silica bead matrix filled microchannel the extraction efficacy was 40%. The cartridge based magnetic bead system had an extraction efficiency of 19.2%. For an electric field based method that used Nafion films, a nucleic acid extraction efficiency of 66.3 % was achieved at 6 volts DC. For the flow rates we tested (10-50 {micro}L/min), the nucleic acid extraction

  9. Chitosan-based hydrogel for dye removal from aqueous solutions: Optimization of the preparation procedure

    Science.gov (United States)

    Gioiella, Lucia; Altobelli, Rosaria; de Luna, Martina Salzano; Filippone, Giovanni

    2016-05-01

    The efficacy of chitosan-based hydrogels in the removal of dyes from aqueous solutions has been investigated as a function of different parameters. Hydrogels were obtained by gelation of chitosan with a non-toxic gelling agent based on an aqueous basic solution. The preparation procedure has been optimized in terms of chitosan concentration in the starting solution, gelling agent concentration and chitosan-to-gelling agent ratio. The goal is to properly select the material- and process-related parameters in order to optimize the performances of the chitosan-based dye adsorbent. First, the influence of such factors on the gelling process has been studied from a kinetic point of view. Then, the effects on the adsorption capacity and kinetics of the chitosan hydrogels obtained in different conditions have been investigated. A common food dye (Indigo Carmine) has been used for this purpose. Noticeably, although the disk-shaped hydrogels are in the bulk form, their adsorption capacity is comparable to that reported in the literature for films and beads. In addition, the bulk samples can be easily separated from the liquid phase after the adsorption process, which is highly attractive from a practical point of view. Compression tests reveal that the samples do not breakup even after relatively large compressive strains. The obtained results suggest that the fine tuning of the process parameters allows the production of mechanical resistant and highly adsorbing chitosan-based hydrogels.

  10. Simulating and Optimizing Preparative Protein Chromatography with ChromX

    Science.gov (United States)

    Hahn, Tobias; Huuk, Thiemo; Heuveline, Vincent; Hubbuch, Ju¨rgen

    2015-01-01

    Industrial purification of biomolecules is commonly based on a sequence of chromatographic processes, which are adapted slightly to new target components, as the time to market is crucial. To improve time and material efficiency, modeling is increasingly used to determine optimal operating conditions, thus providing new challenges for current and…

  11. Simulating and Optimizing Preparative Protein Chromatography with ChromX

    Science.gov (United States)

    Hahn, Tobias; Huuk, Thiemo; Heuveline, Vincent; Hubbuch, Ju¨rgen

    2015-01-01

    Industrial purification of biomolecules is commonly based on a sequence of chromatographic processes, which are adapted slightly to new target components, as the time to market is crucial. To improve time and material efficiency, modeling is increasingly used to determine optimal operating conditions, thus providing new challenges for current and…

  12. Preparation of magnetic graphene @polydopamine @Zr-MOF material for the extraction and analysis of bisphenols in water samples.

    Science.gov (United States)

    Wang, Xianying; Deng, Chunhui

    2015-11-01

    In this work, a simple method for the extraction and analysis of bisphenols in environmental samples was presented. And the prepared zirconium-based magnetic MOFs (magG@PDA@Zr-MOF) were used as the sorbents for the magnetic solid-phase extraction. With the simple solvothermal reaction and sol-gel method, the prepared material showed great characteristics of large surface area, homogeneous pore size, good magnetic responsivity and super-hydrophilicity. The large surface area provided abundant sites to extract target compounds; the magnetic property could simplify the whole extraction procedure; and the hydrophilicity improved the dispersibility of the material in matrix. Here, various extraction parameters were optimized, including amounts of sorbents, adsorption time, species of elution solvents and desorption time. The whole extraction procedure could be accomplished in 30 min. And under the optimized conditions, method validations were also studied, such as linearity, the limit of detection and recovery. Finally, the prepared material was used in real water samples. The results showed this material had good potential as the sorbent for the extraction of targets in environmental water samples.

  13. Sample preparation and in situ hybridization techniques for automated molecular cytogenetic analysis of white blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Rijke, F.M. van de; Vrolijk, H.; Sloos, W. [Leiden Univ. (Netherlands)] [and others

    1996-06-01

    With the advent in situ hybridization techniques for the analysis of chromosome copy number or structure in interphase cells, the diagnostic and prognostic potential of cytogenetics has been augmented considerably. In theory, the strategies for detection of cytogenetically aberrant cells by in situ hybridization are simple and straightforward. In practice, however, they are fallible, because false classification of hybridization spot number or patterns occurs. When a decision has to be made on molecular cytogenetic normalcy or abnormalcy of a cell sample, the problem of false classification becomes particularly prominent if the fraction of aberrant cells is relatively small. In such mosaic situations, often > 200 cells have to be evaluated to reach a statistical sound figure. The manual enumeration of in situ hybridization spots in many cells in many patient samples is tedious. Assistance in the evaluation process by automation of microscope functions and image analysis techniques is, therefore, strongly indicated. Next to research and development of microscope hardware, camera technology, and image analysis, the optimization of the specimen for the (semi)automated microscopic analysis is essential, since factors such as cell density, thickness, and overlap have dramatic influences on the speed and complexity of the analysis process. Here we describe experiments that have led to a protocol for blood cell specimen that results in microscope preparations that are well suited for automated molecular cytogenetic analysis. 13 refs., 4 figs., 1 tab.

  14. Triangular Geometrized Sampling Heuristics for Fast Optimal Motion Planning

    Directory of Open Access Journals (Sweden)

    Ahmed Hussain Qureshi

    2015-02-01

    Full Text Available Rapidly-exploring Random Tree (RRT-based algorithms have become increasingly popular due to their lower computational complexity as compared with other path planning algorithms. The recently presented RRT* motion planning algorithm improves upon the original RRT algorithm by providing optimal path solutions. While RRT determines an initial collision-free path fairly quickly, RRT* guarantees almost certain convergence to an optimal, obstacle-free path from the start to the goal points for any given geometrical environment. However, the main limitations of RRT* include its slow processing rate and high memory consumption, due to the large number of iterations required for calculating the optimal path. In order to overcome these limitations, we present another improvement, i.e, the Triangular Geometerized-RRT* (TGRRT* algorithm, which utilizes triangular geometrical methods to improve the performance of the RRT* algorithm in terms of the processing time and a decreased number of iterations required for an optimal path solution. Simulations comparing the performance results of the improved TG-RRT* with RRT* are presented to demonstrate the overall improvement in performance and optimal path detection.

  15. Triangular Geometrized Sampling Heuristics for Fast Optimal Motion Planning

    Directory of Open Access Journals (Sweden)

    Ahmed Hussain Qureshi

    2015-02-01

    Full Text Available Rapidly-exploring Random Tree (RRT-based algorithms have become increasingly popular due to their lower computational complexity as compared with other path planning algorithms. The recently presented RRT* motion planning algorithm improves upon the original RRT algorithm by providing optimal path solutions. While RRT determines an initial collision-free path fairly quickly, RRT* guarantees almost certain convergence to an optimal, obstacle-free path from the start to the goal points for any given geometrical environment. However, the main limitations of RRT* include its slow processing rate and high memory consumption, due to the large number of iterations required for calculating the optimal path. In order to overcome these limitations, we present another improvement, i.e, the Triangular Geometerized-RRT* (TG-RRT* algorithm, which utilizes triangular geometrical methods to improve the performance of the RRT* algorithm in terms of the processing time and a decreased number of iterations required for an optimal path solution. Simulations comparing the performance results of the improved TG-RRT* with RRT* are presented to demonstrate the overall improvement in performance and optimal path detection.

  16. Sampled-data and discrete-time H2 optimal control

    NARCIS (Netherlands)

    Trentelman, Harry L.; Stoorvogel, Anton A.

    1993-01-01

    This paper deals with the sampled-data H2 optimal control problem. Given a linear time-invariant continuous-time system, the problem of minimizing the H2 performance over all sampled-data controllers with a fixed sampling period can be reduced to a pure discrete-time H2 optimal control problem. This

  17. Sampled-Data and Discrete-Time H2 Optimal Control

    NARCIS (Netherlands)

    Trentelman, H.L.; Stoorvogel, A.A.

    1995-01-01

    This paper deals with the sampled-data H2 optimal control problem. Given a linear time-invariant continuous-time system, the problem of minimizing the H2 performance over all sampled-data controllers with a fixed sampling period can be reduced to a pure discrete-time H2 optimal control problem. This

  18. Sample preparation for atomic-resolution STEM at low voltages by FIB

    Energy Technology Data Exchange (ETDEWEB)

    Schaffer, Miroslava, E-mail: mschaffer@SuperSTEM.org [SuperSTEM, STFC Daresbury Laboratories, Keckwick Lane, Warrington WA4 4AD (United Kingdom); Department of Engineering, George Holt Building, Ashton Street, Liverpool L69 3BX (United Kingdom); Schaffer, Bernhard [SuperSTEM, STFC Daresbury Laboratories, Keckwick Lane, Warrington WA4 4AD (United Kingdom); Kelvin Nanocharacterisation Centre, SUPA School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, Scotland (United Kingdom); Ramasse, Quentin [SuperSTEM, STFC Daresbury Laboratories, Keckwick Lane, Warrington WA4 4AD (United Kingdom); Department of Engineering, George Holt Building, Ashton Street, Liverpool L69 3BX (United Kingdom)

    2012-03-15

    While FIB sample preparation for transmission electron microscopy is a well established technique, few examples exist of samples of sufficient quality for atomic resolution imaging by aberration corrected (scanning) transmission electron microscopy (STEM). In this work we demonstrate the successful preparation of such samples from five different materials and present the refined lift-out preparation technique, which was applied here. Samples with parallel surfaces and a general thickness between 20 and 40 nm over a range of several {mu}m were repeatedly prepared and analyzed by Cs-corrected STEM at 60 and 100 kV. Here, a novel 'wedge pre-milling' step helps to keep the protective surface layers intact during the whole milling process, allowing features close to or at the sample surface to be analyzed without preparation damage. Another example shows the cross-sectional preparation of a working thin film solar cell device to a final thickness of 10 to 20 nm over {mu}m sized areas in the region of interest, enabling atomic resolution imaging and elemental mapping across general grain boundaries without projection artefacts. All sample preparation has been carried out in modern Dual-Beam FIB microscopes capable of low-kV Ga{sup +} ion milling, but without additional preparation steps after the FIB lift-out procedure. -- Highlights: Black-Right-Pointing-Pointer Suitability of stand-alone FIB preparation for atomic resolution STEM is shown. Black-Right-Pointing-Pointer Reproducible preparation of 10-40 nm thick samples from 5 different materials. Black-Right-Pointing-Pointer Low-kV milling and adjusted procedure for crystalline, homogeneously thin specimen. Black-Right-Pointing-Pointer Wedge pre-milling to protect surface-near features.

  19. Near-Optimal Detection in MIMO Systems using Gibbs Sampling

    DEFF Research Database (Denmark)

    Hansen, Morten; Hassibi, Babak; Dimakis, Georgios Alexandros

    2009-01-01

    In this paper we study a Markov Chain Monte Carlo (MCMC) Gibbs sampler for solving the integer least-squares problem. In digital communication the problem is equivalent to preforming Maximum Likelihood (ML) detection in Multiple-Input Multiple-Output (MIMO) systems. While the use of MCMC methods...... for such problems has already been proposed, our method is novel in that we optimize the "temperature" parameter so that in steady state, i.e., after the Markov chain has mixed, there is only polynomially (rather than exponentially) small probability of encountering the optimal solution. More precisely, we obtain...

  20. pH adjustment of human blood plasma prior to bioanalytical sample preparation

    NARCIS (Netherlands)

    Hendriks, G.; Uges, D. R. A.; Franke, J. P.

    2008-01-01

    pH adjustment in bioanalytical sample preparation concerning ionisable compounds is one of the most common sample treatments. This is often done by mixing an aliquot of the sample with a proper buffer adjusted to the proposed pH. The pH of the resulting mixture however, does not necessarily have to

  1. Sample Preparation of Corn Seed Tissue to Prevent Analyte Relocations for Mass Spectrometry Imaging

    Science.gov (United States)

    Kim, Shin Hye; Kim, Jeongkwon; Lee, Young Jin; Lee, Tae Geol; Yoon, Sohee

    2017-08-01

    Corn seed tissue sections were prepared by the tape support method using an adhesive tape, and mass spectrometry imaging (MSI) was performed. The effect of heat generated during sample preparation was investigated by time-of-flight secondary mass spectrometry (TOF-SIMS) imaging of corn seed tissue prepared by the tape support and the thaw-mounted methods. Unlike thaw-mounted sample preparation, the tape support method does not cause imaging distortion because of the absence of heat, which can cause migration of the analytes on the sample. By applying the tape-support method, the corn seed tissue was prepared without structural damage and MSI with accurate spatial information of analytes was successfully performed.

  2. Equipment for Topographical Preparation and Analysis of Various Semiconductor Infrared Detector Samples

    Science.gov (United States)

    2015-11-13

    Approved for Public Release; Distribution Unlimited Final Report: Equipment for Topographical Preparation and Analysis of Various Semiconductor Infrared...Final Report: Equipment for Topographical Preparation and Analysis of Various Semiconductor Infrared Detector Samples Report Title A used calibrated...camera will reinitialize and the video settings have to be reset. 6 Figure 4. This will open the both video overlay and the Dektak

  3. Advanced Curation Activities at NASA: Preparing for the Next Waves of Astromaterials Sample Return

    Science.gov (United States)

    Zeigler, R. A.; Allton, J. H.; Evans, C. A.; Fries, M. D.; McCubbin, F. M.; Nakamura-Messenger, K.; Righter, K.; Zolensky, M.; Stansbery, E. K.

    2017-02-01

    We discuss the current curatorial efforts for NASA's astromaterials collections, as well as efforts that are underway (or need to be undertaken) to prepare for the challenging curation conditions required by future sample return missions.

  4. Simple and Reproducible Sample Preparation for Single-Shot Phosphoproteomics with High Sensitivity

    DEFF Research Database (Denmark)

    Jersie-Christensen, Rosa R.; Sultan, Abida; Olsen, Jesper V

    2016-01-01

    The traditional sample preparation workflow for mass spectrometry (MS)-based phosphoproteomics is time consuming and usually requires multiple steps, e.g., lysis, protein precipitation, reduction, alkylation, digestion, fractionation, and phosphopeptide enrichment. Each step can introduce chemica...

  5. Robotic, MEMS-based Multi Utility Sample Preparation Instrument for ISS Biological Workstation Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will develop a multi-functional, automated sample preparation instrument for biological wet-lab workstations on the ISS. The instrument is based on a...

  6. Optimized preparation of urine samples for two-dimensional electrophoresis and initial application to patient samples

    DEFF Research Database (Denmark)

    Lafitte, Daniel; Dussol, Bertrand; Andersen, Søren;

    2002-01-01

    protein excretion patterns of 49 healthy men and 4 patients with renal disease were obtained by 2D electrophoresis. Silver nitrate stained protein spots were identified by mass spectrometry. RESULTS: Reproductive 2D gels identified 5 classes of proteins systematically found in healthy subjects...... was constant over time and reveal for the first time the relative abundance of albumin fragments in healthy subjects' urine. The profiles of the 4 patients, were specific of their renal disease....

  7. Optimization of AZO films prepared on flexible substrates

    Indian Academy of Sciences (India)

    C C Hu; T W Lu; C Y Chou; J T Wang; H H Huang; C Y Hsu

    2014-10-01

    Transparent conductive Al2O3-doped zinc oxide (in AZO, Al2O3 content is ∼ 2 wt%) thin films are deposited on flexible polyethylene terephthalate (PET) substrates, using radio frequency (rf) magnetron sputtering. The Taguchi method with an 9 (34) orthogonal array, a signal-to-noise ratio and analysis of variance (ANOVA) was used to determine the performance characteristics of the coating operations. Using grey relational analysis, the optimization of these deposition process parameters for AZO thin films with multiple characteristics was performed. The electrical resistivity of AZO/PET films is reduced from 2.6 × 10-2 to 5.5 × 10-3 -cm and the visible range transmittance is > 83%, using the grey relational analysis. ANOVA results for the grey relational grade indicate that rf power and working pressure are the two most influential factors. The effect of the rf power (in the range from 30 to 70 W) and the argon working pressure (in the range from 0.90 to 1.1 Pa) on the morphology and optoelectronic performance of AZO films are also investigated. An analysis of the influence of the dominant parameters in the optimal design region is helpful for adjustment of the coating parameters.

  8. Microbial mediated preparation, characterization and optimization of gold nanoparticles.

    Science.gov (United States)

    Barabadi, Hamed; Honary, Soheila; Ebrahimi, Pouneh; Mohammadi, Milad Ali; Alizadeh, Ahad; Naghibi, Farzaneh

    2014-01-01

    The need for eco-friendly and cost effective methods for nanoparticles synthesis is developing interest in biological approaches which are free from the use of toxic chemicals as byproducts. This study aimed to biosynthesize and optimize the size of gold nanoparticles which produced by biotechnological method using Penicillium crustosum isolated from soil. Initially, Penicillium crustosum was grown in fluid czapek dox broth on shaker at 28 °C and 200 rpm for ten days and then the supernatant was separated from the mycelia to convert AuCl₄ solution into gold nanoparticles. The synthesized nanoparticles in the optimum conditions were formed with fairly well-defined dimensions and good monodispersity. The characterizations were done by using different methods (UV-Visible Spectroscopy, Fluorescence, FT-IR, AFM (Atomic Force Microscopy) and DLS (Dynamic Light Scattering). The bioconversion was optimized by Box-Behnken experimental design. The results show that the effective factors in this process were concentration of AuCl₄, pH of medium and temperature of shaker incubator. The R(2) value was calculated to be 0.9999 indicating the accuracy and ability of the polynomial model. It can be concluded that the use of multivariate analysis facilitated to find out the optimum conditions for the biosynthesis of gold nanoparticles induced by Penicillium crustosum in a time and cost effective process. The current approach suggested that rapid synthesis of gold nanoparticles would be suitable for developing a biological process for mass scale production of formulations.

  9. Microbial mediated preparation, characterization and optimization of gold nanoparticles

    Directory of Open Access Journals (Sweden)

    Hamed Barabadi

    2014-12-01

    Full Text Available The need for eco-friendly and cost effective methods for nanoparticles synthesis is developing interest in biological approaches which are free from the use of toxic chemicals as byproducts. This study aimed to biosynthesize and optimize the size of gold nanoparticles which produced by biotechnological method using Penicillium crustosum isolated from soil. Initially, Penicillium crustosum was grown in fluid czapek dox broth on shaker at 28 ºC and 200 rpm for ten days and then the supernatant was separated from the mycelia to convert AuCl4 solution into gold nanoparticles. The synthesized nanoparticles in the optimum conditions were formed with fairly well-defined dimensions and good monodispersity. The characterizations were done by using different methods (UV-Visible Spectroscopy, Fluorescence, FT-IR, AFM (Atomic Force Microscopy and DLS (Dynamic Light Scattering. The bioconversion was optimized by Box-Behnken experimental design. The results show that the effective factors in this process were concentration of AuCl4, pH of medium and temperature of shaker incubator. The R² value was calculated to be 0.9999 indicating the accuracy and ability of the polynomial model. It can be concluded that the use of multivariate analysis facilitated to find out the optimum conditions for the biosynthesis of gold nanoparticles induced by Penicillium crustosum in a time and cost effective process. The current approach suggested that rapid synthesis of gold nanoparticles would be suitable for developing a biological process for mass scale production of formulations.

  10. Analytical Chemistry Laboratory (ACL) procedure compendium. Volume 2, Sample preparation methods

    Energy Technology Data Exchange (ETDEWEB)

    1993-08-01

    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 VOC 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.

  11. Preparation of testate amoebae samples affects water table depth reconstructions in peatland palaeoecological studies

    Directory of Open Access Journals (Sweden)

    Eve Avel

    2013-05-01

    Full Text Available In peatland palaeoecological studies, the preparation of peat samples for testate amoebae (TA analysis involves boiling of samples and microsieving them through a 15-μm sieve. We studied the effect of these preparation stages on the estimation of TA assemblages and on the reconstruction of water table depths (WTD. Our results indicate that the TA assemblages of boiled and unboiled samples are not significantly different, while microsieving reduces the concentration of small TA taxa and results in significantly different TA assemblages. The differences between microsieved and unsieved TA assemblages were reflected also in predicted values of WTD, which indicated drier conditions in case of unsieved samples than in microsieved samples. We conclude that the boiling of samples might be omitted if TA are extracted from the fresh peat samples. Microsieving may lead to erroneous palaeoecological WTD reconstructions and should be avoided if small TA taxa are present in samples.

  12. On radiation damage in FIB-prepared softwood samples measured by scanning X-ray diffraction.

    Science.gov (United States)

    Storm, Selina; Ogurreck, Malte; Laipple, Daniel; Krywka, Christina; Burghammer, Manfred; Di Cola, Emanuela; Müller, Martin

    2015-03-01

    The high flux density encountered in scanning X-ray nanodiffraction experiments can lead to severe radiation damage to biological samples. However, this technique is a suitable tool for investigating samples to high spatial resolution. The layered cell wall structure of softwood tracheids is an interesting system which has been extensively studied using this method. The tracheid cell has a complex geometry, which requires the sample to be prepared by cutting it perpendicularly to the cell wall axis. Focused ion beam (FIB) milling in combination with scanning electron microscopy allows precise alignment and cutting without splintering. Here, results of a scanning X-ray diffraction experiment performed on a biological sample prepared with a focused ion beam of gallium atoms are reported for the first time. It is shown that samples prepared and measured in this way suffer from the incorporation of gallium atoms up to a surprisingly large depth of 1 µm.

  13. Determination of Optimal Double Sampling Plan using Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Sampath Sundaram

    2012-03-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 Designing double sampling plan requires identification of sample sizes and acceptance numbers. In this paper a genetic algorithm has been designed for the selection of optimal acceptance numbers and sample sizes for the specified producer’s risk and consumer’s risk. Implementation of the algorithm has been illustrated numerically for different choices of quantities involved in a double sampling plan   

  1. Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation

    Science.gov (United States)

    Lai, Yin-Hung; Cai, Yi-Hong; Lee, Hsun; Ou, Yu-Meng; Hsiao, Chih-Hao; Tsao, Chien-Wei; Chang, Huan-Tsung; Wang, Yi-Sheng

    2016-08-01

    This work demonstrates a method to prepare homogeneous distributions of analytes to improve data reproducibility in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Natural-air drying processes normally result in unwanted heterogeneous spatial distributions of analytes in MALDI crystals and make quantitative analysis difficult. This study demonstrates that inducing Marangoni flows within drying droplets can significantly reduce the heterogeneity problem. The Marangoni flows are accelerated by changing substrate temperatures to create temperature gradients across droplets. Such hydrodynamic flows are analyzed semi-empirically. Using imaging mass spectrometry, changes of heterogeneity of molecules with the change of substrate temperature during drying processes are demonstrated. The observed heterogeneities of the biomolecules reduce as predicted Marangoni velocities increase. In comparison to conventional methods, drying droplets on a 5 °C substrate while keeping the surroundings at ambient conditions typically reduces the heterogeneity of biomolecular ions by 65%-80%. The observation suggests that decreasing substrate temperature during droplet drying processes is a simple and effective means to reduce analyte heterogeneity for quantitative applications.

  2. Preparation and optimization of calcium fluoride particles for dental applications.

    Science.gov (United States)

    Koeser, Joachim; Carvalho, Thiago Saads; Pieles, Uwe; Lussi, Adrian

    2014-07-01

    Fluorides are used in dental care due to their beneficial effect in tooth enamel de-/remineralization cycles. To achieve a desired constant supply of soluble fluorides in the oral cavity, different approaches have been followed. Here we present results on the preparation of CaF2 particles and their characterization with respect to a potential application as enamel associated fluoride releasing reservoirs. CaF2 particles were synthesized by precipitation from soluble NaF and CaCl2 salt solutions of defined concentrations and their morphology analyzed by scanning electron microscopy. CaF2 particles with defined sizes and shapes could be synthesized by adjusting the concentrations of the precursor salt solutions. Such particles interacted with enamel surfaces when applied at fluoride concentrations correlating to typical dental care products. Fluoride release from the synthesized CaF2 particles was observed to be largely influenced by the concentration of phosphate in the solution. Physiological solutions with phosphate concentration similar to saliva (3.5 mM) reduced the fluoride release from pure CaF2 particles by a factor of 10-20 × as compared to phosphate free buffer solutions. Fluoride release was even lower in human saliva. The fluoride release could be increased by the addition of phosphate in substoichiometric amounts during CaF2 particle synthesis. The presented results demonstrate that the morphology and fluoride release characteristics of CaF2 particles can be tuned and provide evidence of the suitability of synthetic CaF2 particles as enamel associated fluoride reservoirs.

  3. Optimizing analog-to-digital converters for sampling extracellular potentials.

    Science.gov (United States)

    Artan, N Sertac; Xu, Xiaoxiang; Shi, Wei; Chao, H Jonathan

    2012-01-01

    In neural implants, an analog-to-digital converter (ADC) provides the delicate interface between the analog signals generated by neurological processes and the digital signal processor that is tasked to interpret these signals for instance for epileptic seizure detection or limb control. In this paper, we propose a low-power ADC architecture for neural implants that process extracellular potentials. The proposed architecture uses the spike detector that is readily available on most of these implants in a closed-loop with an ADC. The spike detector determines whether the current input signal is part of a spike or it is part of noise to adaptively determine the instantaneous sampling rate of the ADC. The proposed architecture can reduce the power consumption of a traditional ADC by 62% when sampling extracellular potentials without any significant impact on spike detection accuracy.

  4. Optimized nested Markov chain Monte Carlo sampling: theory

    Energy Technology Data Exchange (ETDEWEB)

    Coe, Joshua D [Los Alamos National Laboratory; Shaw, M Sam [Los Alamos National Laboratory; Sewell, Thomas D [U. MISSOURI

    2009-01-01

    Metropolis Monte Carlo sampling of a reference potential is used to build a Markov chain in the isothermal-isobaric ensemble. At the endpoints of the chain, the energy is reevaluated at a different level of approximation (the 'full' energy) and a composite move encompassing all of the intervening steps is accepted on the basis of a modified Metropolis criterion. By manipulating the thermodynamic variables characterizing the reference system we maximize the average acceptance probability of composite moves, lengthening significantly the random walk made between consecutive evaluations of the full energy at a fixed acceptance probability. This provides maximally decorrelated samples of the full potential, thereby lowering the total number required to build ensemble averages of a given variance. The efficiency of the method is illustrated using model potentials appropriate to molecular fluids at high pressure. Implications for ab initio or density functional theory (DFT) treatment are discussed.

  5. Optimization conditions of samples saponification for tocopherol analysis.

    Science.gov (United States)

    Souza, Aloisio Henrique Pereira; Gohara, Aline Kirie; Rodrigues, Ângela Claudia; Ströher, Gisely Luzia; Silva, Danielle Cristina; Visentainer, Jesuí Vergílio; Souza, Nilson Evelázio; Matsushita, Makoto

    2014-09-01

    A full factorial design 2(2) (two factors at two levels) with duplicates was performed to investigate the influence of the factors agitation time (2 and 4 h) and the percentage of KOH (60% and 80% w/v) in the saponification of samples for the determination of α, β and γ+δ-tocopherols. The study used samples of peanuts (cultivar armadillo), produced and marketed in Maringá, PR. The factors % KOH and agitation time were significant, and an increase in their values contributed negatively to the responses. The interaction effect was not significant for the response δ-tocopherol, and the contribution of this effect to the other responses was positive, but less than 10%. The ANOVA and response surfaces analysis showed that the most efficient saponification procedure was obtained using a 60% (w/v) solution of KOH and with an agitation time of 2 h.

  6. Repeating cytological preparations on liquid-based cytology samples: A methodological advantage?

    Science.gov (United States)

    Pinto, Alvaro P; Maia, Henrique Felde; di Loretto, Celso; Krunn, Patrícia; Túlio, Siumara; Collaço, Luis Martins

    2007-10-01

    This study investigates the rule that repeating cytological preparations on liquid-based cytology improves sample adequacy, diagnosis, microbiological, and hormonal evaluations. We reviewed 156 cases of pap-stained preparations of exfoliated cervical cells in two slides processed by DNA-Cytoliq System. After sample repeat/dilution, limiting factors affecting sample adequacy were removed in nine cases and three unsatisfactory cases were reclassified as satisfactory. Diagnosis was altered in 24 cases. Of these, the original diagnosis in 15 was atypical squamous cells of undetermined significance; after the second slide examination, diagnosis in 5 of the 15 cases changed to low-grade squamous intraepithelial lesion, 3 to high-grade squamous intraepithelial lesion, and 7 to absence of lesion. Microbiological evaluation was altered, with Candida sp. detected in two repeated slides. Repeat slide preparation or dilution of residual samples enhances cytological diagnosis and decreases effects of limiting factors in manually processed DIGENE DCS LBC.

  7. Development of a high vacuum sample preparation system for helium mass spectrometer

    Science.gov (United States)

    Kumar, P.; Das, N. K.; Mallik, C.; Bhandari, R. K.

    2012-11-01

    A high vacuum sample preparation system for the 3He/4He ratio mass spectrometer (Helix SFT) has been developed to remove all the gaseous constituents excluding helium from the field gases. The sample preparation system comprises of turbo molecular pump, ion pump, zirconium getter, pipettes and vacuum gauges with controller. All these are fitted with cylindrical SS chamber using all metal valves. The field samples are initially treated with activated charcoal trap immersed in liquid nitrogen to cutoff major impurities and moisture present in the sample gas. A sample of 5 ml is collected out of this stage at a pressure of 10-2 mbar. This sample is subsequently purified at a reduced pressure of 10-7 mbar before it is injected into the ion source of the mass spectrometer. The sample pressure was maintained below 10-7 mbar with turbo molecular vacuum pumps and ion pumps. The sample gas passes through several getter elements and a cold finger with the help of manual high vacuum valves before it is fed to the mass spectrometer. Thus the high vacuum sample preparation system introduces completely clean, dry and refined helium sample to the mass spectrometer for best possible analysis of isotopic ratio of helium.

  8. Electromembrane extraction as a rapid and selective miniaturized sample preparation technique for biological fluids

    DEFF Research Database (Denmark)

    Gjelstad, Astrid; Pedersen-Bjergaard, Stig; Seip, Knut Fredrik

    2015-01-01

    This special report discusses the sample preparation method electromembrane extraction, which was introduced in 2006 as a rapid and selective miniaturized extraction method. The extraction principle is based on isolation of charged analytes extracted from an aqueous sample, across a thin film....... Technical aspects of electromembrane extraction, important extraction parameters as well as a handful of examples of applications from different biological samples and bioanalytical areas are discussed in the paper....

  9. TruSeq Stranded mRNA and Total RNA Sample Preparation Kits

    Science.gov (United States)

    Total RNA-Seq enabled by ribosomal RNA (rRNA) reduction is compatible with formalin-fixed paraffin embedded (FFPE) samples, which contain potentially critical biological information. The family of TruSeq Stranded Total RNA sample preparation kits provides a unique combination of unmatched data quality for both mRNA and whole-transcriptome analyses, robust interrogation of both standard and low-quality samples and workflows compatible with a wide range of study designs.

  10. Optimization of calcium phosphate fine ceramic powders preparation

    Science.gov (United States)

    Sezanova, K.; Tepavitcharova, S.; Rabadjieva, D.; Gergulova, R.; Ilieva, R.

    2013-12-01

    The effect of biomimetic synthesis method, reaction medium and further precursor treatments on the chemical and phase composition, crystal size and morphology of calcium phosphates was examined. Nanosized calcium phosphate precursors were biomimetically precipitated by the method of continuous precipitation in three types of reaction media at pH 8: (i) SBF as an inorganic electrolyte system; (ii) organic (glycerine) modified SBF (volume ratio of 1:1); (iii) polymer (10 g/l xanthan gum or 10 g/l guar gum) modified SBF (volume ratio of 1:1). After maturation (24 h) the samples were lyophilized, calcinated at 300°C for 3 hours, and washed with water, followed by new gelation, lyophilization and step-wise (200, 400, 600, 800, and 1000°C, each for 3 hours) sintering. The reaction medium influenced the chemical composition and particle size but not the morphology of the calcium phosphate powders. In all studied cases bi-phase calcium phosphate fine powders with well-shaped spherical grains, consisting of β-tricalcium phosphate (β-TCP) and hydroxyapatite (HA) with a Ca/P ratio of 1.3 - 1.6 were obtained. The SBF modifiers decreased the particle size of the product in the sequence guar gum ˜ xanthan gum < glycerin < SBF medium.

  11. Optimizing fish sampling for fish - mercury bioaccumulation factors

    Science.gov (United States)

    Scudder Eikenberry, Barbara C.; Riva-Murray, Karen; Knightes, Christopher D.; Journey, Celeste A.; Chasar, Lia C.; Brigham, Mark E.; Bradley, Paul M.

    2015-01-01

    Fish Bioaccumulation Factors (BAFs; ratios of mercury (Hg) in fish (Hgfish) and water (Hgwater)) are used to develop Total Maximum Daily Load and water quality criteria for Hg-impaired waters. Both applications require representative Hgfish estimates and, thus, are sensitive to sampling and data-treatment methods. Data collected by fixed protocol from 11 streams in 5 states distributed across the US were used to assess the effects of Hgfish normalization/standardization methods and fish sample numbers on BAF estimates. Fish length, followed by weight, was most correlated to adult top-predator Hgfish. Site-specific BAFs based on length-normalized and standardized Hgfish estimates demonstrated up to 50% less variability than those based on non-normalized Hgfish. Permutation analysis indicated that length-normalized and standardized Hgfish estimates based on at least 8 trout or 5 bass resulted in mean Hgfish coefficients of variation less than 20%. These results are intended to support regulatory mercury monitoring and load-reduction program improvements.

  12. Sampling technique is important for optimal isolation of pharyngeal gonorrhoea.

    Science.gov (United States)

    Mitchell, M; Rane, V; Fairley, C K; Whiley, D M; Bradshaw, C S; Bissessor, M; Chen, M Y

    2013-11-01

    Culture is insensitive for the detection of pharyngeal gonorrhoea but isolation is pivotal to antimicrobial resistance surveillance. The aim of this study was to ascertain whether recommendations provided to clinicians (doctors and nurses) on pharyngeal swabbing technique could improve gonorrhoea detection rates and to determine which aspects of swabbing technique are important for optimal isolation. This study was undertaken at the Melbourne Sexual Health Centre, Australia. Detection rates among clinicians for pharyngeal gonorrhoea were compared before (June 2006-May 2009) and after (June 2009-June 2012) recommendations on swabbing technique were provided. Associations between detection rates and reported swabbing technique obtained via a clinician questionnaire were examined. The overall yield from testing before and after provision of the recommendations among 28 clinicians was 1.6% (134/8586) and 1.8% (264/15,046) respectively (p=0.17). Significantly higher detection rates were seen following the recommendations among clinicians who reported a change in their swabbing technique in response to the recommendations (2.1% vs. 1.5%; p=0.004), swabbing a larger surface area (2.0% vs. 1.5%; p=0.02), applying more swab pressure (2.5% vs. 1.5%; p<0.001) and a change in the anatomical sites they swabbed (2.2% vs. 1.5%; p=0.002). The predominant change in sites swabbed was an increase in swabbing of the oropharynx: from a median of 0% to 80% of the time. More thorough swabbing improves the isolation of pharyngeal gonorrhoea using culture. Clinicians should receive training to ensure swabbing is performed with sufficient pressure and that it covers an adequate area that includes the oropharynx.

  13. Optimization and validation of post-column assay for screening of radical scavengers in herbal raw materials and herbal preparations.

    Science.gov (United States)

    Raudonis, Raimondas; Bumblauskiene, Lina; Jakstas, Valdas; Pukalskas, Audrius; Janulis, Valdimaras

    2010-12-03

    On-line method, which combines HPLC distribution and post-column reaction, was designed for the search of individual antioxidants. Optimization of the assay was performed evaluating optimal ABTS(+) radical cation concentration in the reactor, reaction time, impact of flow rate, reaction coil length. HPLC-ABTS assay validation in this work was performed by assessing reference antioxidant negative peak areas in radical scavenging chromatogram. Sample free radical scavenging activity is expressed as trolox equivalent antioxidant capacity (TEAC). Optimized and validated method was applied in detection of compounds possessing free radical scavenging ability in complex mixtures. Antioxidant compounds were studied in perilla (Perilla frutescens (L.) Britton var. crispa f. viridis) herbal raw material and its preparations. The HPLC-separated antioxidant compounds were identified using HPLC-photodiode array coupled to mass spectrometer, using a reference mass for determining accurate masses. Radical scavenging characteristics of rosmarinic acid, which is the dominant phenolic compound in medicinal herbal raw material of perilla and its preparations, were confirmed by the calculated TEAC values. Compounds responsible for antioxidant effect in herbal raw materials and herbal preparations were identified, evaluated and compared.

  14. Optimal purification and sensitive quantification of DNA from fecal samples

    DEFF Research Database (Denmark)

    Jensen, Annette Nygaard; Hoorfar, Jeffrey

    2002-01-01

    Application of reliable, rapid and sensitive methods to laboratory diagnosis of zoonotic infections continues to challenge microbiological laboratories. The recovery of DNA from a swine fecal sample and a bacterial culture extracted by a conventional phenol-chloroform extraction method was compared......, the detection range of X-DNA of a spectrophotometric and a fluorometric (PicoGreen) method was compared. The PicoGreen showed a quantification limit of 1 ng/mL, consistent triplicate measurements, and finally a linear relationship between the concentrations of DNA standards and the fluorescence readings (R-2...... = 0.99 and R-2 = 1.00). In conclusion, silica-membrane, columns can provide a more convenient and less hazardous alternative to the conventional phenol-based method. The results have implication for further improvement of sensitive amplification methods for laboratory diagnosis....

  15. High-throughput automated microfluidic sample preparation for accurate microbial genomics

    Science.gov (United States)

    Kim, Soohong; De Jonghe, Joachim; Kulesa, Anthony B.; Feldman, David; Vatanen, Tommi; Bhattacharyya, Roby P.; Berdy, Brittany; Gomez, James; Nolan, Jill; Epstein, Slava; Blainey, Paul C.

    2017-01-01

    Low-cost shotgun DNA sequencing is transforming the microbial sciences. Sequencing instruments are so effective that sample preparation is now the key limiting factor. Here, we introduce a microfluidic sample preparation platform that integrates the key steps in cells to sequence library sample preparation for up to 96 samples and reduces DNA input requirements 100-fold while maintaining or improving data quality. The general-purpose microarchitecture we demonstrate supports workflows with arbitrary numbers of reaction and clean-up or capture steps. By reducing the sample quantity requirements, we enabled low-input (∼10,000 cells) whole-genome shotgun (WGS) sequencing of Mycobacterium tuberculosis and soil micro-colonies with superior results. We also leveraged the enhanced throughput to sequence ∼400 clinical Pseudomonas aeruginosa libraries and demonstrate excellent single-nucleotide polymorphism detection performance that explained phenotypically observed antibiotic resistance. Fully-integrated lab-on-chip sample preparation overcomes technical barriers to enable broader deployment of genomics across many basic research and translational applications. PMID:28128213

  16. Optimal Joint Remote State Preparation of Arbitrary Equatorial Multi-qudit States

    Science.gov (United States)

    Cai, Tao; Jiang, Min

    2016-12-01

    As an important communication technology, quantum information transmission plays an important role in the future network communication. It involves two kinds of transmission ways: quantum teleportation and remote state preparation. In this paper, we put forward a new scheme for optimal joint remote state preparation (JRSP) of an arbitrary equatorial two-qudit state with hybrid dimensions. Moreover, the receiver can reconstruct the target state with 100 % success probability in a deterministic manner via two spatially separated senders. Based on it, we can extend it to joint remote preparation of arbitrary equatorial multi-qudit states with hybrid dimensions using the same strategy.

  17. Optimal Joint Remote State Preparation of Arbitrary Equatorial Multi-qudit States

    Science.gov (United States)

    Cai, Tao; Jiang, Min

    2017-03-01

    As an important communication technology, quantum information transmission plays an important role in the future network communication. It involves two kinds of transmission ways: quantum teleportation and remote state preparation. In this paper, we put forward a new scheme for optimal joint remote state preparation (JRSP) of an arbitrary equatorial two-qudit state with hybrid dimensions. Moreover, the receiver can reconstruct the target state with 100 % success probability in a deterministic manner via two spatially separated senders. Based on it, we can extend it to joint remote preparation of arbitrary equatorial multi-qudit states with hybrid dimensions using the same strategy.

  18. A proteomics sample preparation method for mature, recalcitrant leaves of perennial plants.

    Directory of Open Access Journals (Sweden)

    Deng Gang

    Full Text Available Sample preparation is key to the success of proteomics studies. In the present study, two sample preparation methods were tested for their suitability on the mature, recalcitrant leaves of six representative perennial plants (grape, plum, pear, peach, orange, and ramie. An improved sample preparation method was obtained: Tris and Triton X-100 were added together instead of CHAPS to the lysis buffer, and a 20% TCA-water solution and 100% precooled acetone were added after the protein extraction for the further purification of protein. This method effectively eliminates nonprotein impurities and obtains a clear two-dimensional gel electrophoresis array. The method facilitates the separation of high-molecular-weight proteins and increases the resolution of low-abundance proteins. This method provides a widely applicable and economically feasible technology for the proteomic study of the mature, recalcitrant leaves of perennial plants.

  19. LC-MS analysis of the plasma metabolome–a novel sample preparation strategy

    DEFF Research Database (Denmark)

    Skov, Kasper; Hadrup, Niels; Smedsgaard, Jørn

    2015-01-01

    of plasma samples: The first is protein precipitation; the second is protein precipitation followed by solid phase extraction with sub-fractionation into three sub-samples; a phospholipid, a lipid and a polar sub-fraction. Molecular feature extraction of the data files from LC-qTOF analysis of the samples......Blood plasma is a well-known body fluid often analyzed in studies on the effects of toxic compounds as physiological or chemical induced changes in the mammalian body are reflected in the plasma metabolome. Sample preparation prior to LC-MS based analysis of the plasma metabolome is a challenge...... as plasma contains compounds with very different properties. Besides, proteins, which usually are precipitated with organic solvent, phospholipids, are known to cause ion suppression in electrospray mass spectrometry. We have compared two different sample preparation techniques prior to LC-qTOF analysis...

  20. Automatic coal sample preparation system%煤炭自动制样系统

    Institute of Scientific and Technical Information of China (English)

    王兴无

    2015-01-01

    To solve the problems occurred during manual coal sample preparation,such as low work efficien-cy,high labor intensity,poor working environment,harmful to human beings and poor representativeness of the sample due to large error,the auto coal sample preparation system was designed.Performance tests like residue sample mass,fuel size,residue sample precision and sample preparation bias verified this system has met the requirements of GB/T 1 9494.3-2004 and GB 474-2008 on precision and bias.Its application not only improves the automation degree of sample preparation,but also reduces human disturbance factors in the sample preparation process.%为了解决电厂燃煤人工制样存在的工作效率低,劳动强度大,工作环境差,有害人体健康,误差大影响样品的代表性等问题,设计了煤炭自动制样系统.通过留样质量、出料粒径、留样精密度及制样偏倚等性能试验,证明该系统精密度和偏倚达到了 GB 474—2008和 GB/T 19494.3—2004规定的要求,其应用提高了样品制备的自动化程度,减少了制样过程人为因素的干扰.

  1. Optimizing Endoscopic Ultrasound Guided Tissue Sampling of the Pancreas

    Directory of Open Access Journals (Sweden)

    Pujan Kandel

    2016-03-01

    Full Text Available Endoscopic ultrasound is an important innovation in the field of gastrointestinal endoscopy and allows evaluation of many organs in the vicinity of the gastrointestinal tract. Endoscopic ultrasound-fine needle aspiration has been established to be an important tool in the management of pancreaticobiliary disease and is used for screening, staging, biopsy confirmation, and palliation. The accuracy of endoscopic ultrasound-fine needle aspiration is affected by several factors such as different needle sizes and types and fine needle aspiration techniques. Several comparative studies have been published on various techniques, such as the use of a stylet and suction during fine needle aspiration. Although most studies demonstrate high accuracy across techniques and equipment, various fine needle biopsy histology needles have been studied to compare the advantage of fine needle biopsy over fine needle aspiration. Although fine needle biopsy needles provide better tissue architecture and require fewer numbers of passes, there is no significant evidence of the superiority of fine needle biopsy over fine needle aspiration with regard to diagnostic yield and core tissue procurement. The main aim of this article is to review the various methodologies for improving the practice of endoscopic ultrasound-fine needle aspiration and endoscopic ultrasound- fine needle biopsy tissue sampling for cytological and histological analysis.

  2. A Sequential Optimization Sampling Method for Metamodels with Radial Basis Functions

    Science.gov (United States)

    Pan, Guang; Ye, Pengcheng; Yang, Zhidong

    2014-01-01

    Metamodels have been widely used in engineering design to facilitate analysis and optimization of complex systems that involve computationally expensive simulation programs. The accuracy of metamodels is strongly affected by the sampling methods. In this paper, a new sequential optimization sampling method is proposed. Based on the new sampling method, metamodels can be constructed repeatedly through the addition of sampling points, namely, extrema points of metamodels and minimum points of density function. Afterwards, the more accurate metamodels would be constructed by the procedure above. The validity and effectiveness of proposed sampling method are examined by studying typical numerical examples. PMID:25133206

  3. Electric transport measurements on bulk, polycrystalline MgB2 samples prepared at various reaction temperatures

    Science.gov (United States)

    Wiederhold, A.; Koblischka, M. R.; Inoue, K.; Muralidhar, M.; Murakami, M.; Hartmann, U.

    2016-03-01

    A series of disk-shaped, bulk MgB2 superconductors (sample diameter up to 4 cm) was prepared in order to improve the performance for superconducting super-magnets. Several samples were fabricated using a solid state reaction in pure Ar atmosphere from 750 to 950oC in order to determine the optimum processing parameters to obtain the highest critical current density as well as large trapped field values. Additional samples were prepared with added silver (up to 10 wt.-%) to the Mg and B powder. Magneto-resistance data and I/V-characteristics were recorded using an Oxford Instruments Teslatron system. From Arrhenius plots, we determine the TAFF pinning potential, U 0. The I/V-characteristics yield detailed information on the current flow through the polycrystalline samples. The current flow is influenced by the presence of pores in the samples. Our analysis of the achieved critical currents together with a thorough microstructure investigation reveals that the samples prepared at temperatures between 775°C and 805°C exhibit the smallest grains and the best connectivity between them, while the samples fabricated at higher reaction temperatures show a reduced connectivity and lower pinning potential. Doping the samples with silver leads to a considerable increase of the pinning potential and hence, the critical current densities.

  4. [Sample preparation methods for chromatographic analysis of organic components in atmospheric particulate matter].

    Science.gov (United States)

    Hao, Liang; Wu, Dapeng; Guan, Yafeng

    2014-09-01

    The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.

  5. Secondary Ion Mass Spectrometry Imaging of Molecular Distributions in Cultured Neurons and Their Processes: Comparative Analysis of Sample Preparation

    Science.gov (United States)

    Tucker, Kevin R.; Li, Zhen; Rubakhin, Stanislav S.; Sweedler, Jonathan V.

    2012-11-01

    Neurons often exhibit a complex chemical distribution and topography; therefore, sample preparation protocols that preserve structures ranging from relatively large cell somata to small neurites and growth cones are important factors in secondary ion mass spectrometry (SIMS) imaging studies. Here, SIMS was used to investigate the subcellular localization of lipids and lipophilic species in neurons from Aplysia californica. Using individual neurons cultured on silicon wafers, we compared and optimized several SIMS sampling approaches. After an initial step to remove the high salt culturing media, formaldehyde, paraformaldehyde, and glycerol, and various combinations thereof, were tested for their ability to achieve cell stabilization during and after the removal of extracellular media. These treatments improved the preservation of cellular morphology as visualized with SIMS imaging. For analytes >250 Da, coating the cell surface with a 3.2 nm-thick gold layer increased the ion intensity; multiple analytes previously not observed or observed at low abundance were detected, including intact cholesterol and vitamin E molecular ions. However, once a sample was coated, many of the lower molecular mass (cell stabilization with glycerol and 4 % paraformaldehyde. The sample preparation methods described here enhance SIMS imaging of processes of individual cultured neurons over a broad mass range with enhanced image contrast.

  6. Molecularly imprinted polymers for sample preparation and biosensing in food analysis: Progress and perspectives

    DEFF Research Database (Denmark)

    Ashley, Jon; Shahbazi, Mohammad-Ali; Kant, Krishna

    2017-01-01

    Molecularly imprinted polymers (MIPs) are biomimetics which can selectively bind to analytes of interest. One of the most interesting areas where MIPs have shown the biggest potential is food analysis. MIPs have found use as sorbents in sample preparation attributed to the high selectivity and high...... the imprinting methods which are applicable for imprinting food templates, summarize the recent progress in using MIPs for preparing and analysing food samples, and discuss the current limitations in the commercialisation of MIPs technology. Finally, future perspectives will be given....

  7. Analysis of aroma compounds of Roselle by Dynamic Headspace Sampling using different preparation methods

    DEFF Research Database (Denmark)

    Juhari, Nurul Hanisah Binti; Varming, Camilla; Petersen, Mikael Agerlin

    2015-01-01

    The influence of different methods of sample preparation on the aroma profiles of dried Roselle (Hibiscus sabdariffa) was studied. Least amounts of aroma compounds were recovered by analysis of whole dry calyxes (WD) followed by ground dry (GD), blended together with water (BTW), and ground...... and then mixed with water (GMW). The highest number of aroma compounds was found in Roselle treated in water bath (2hr/40°C) (GMWKB). GMW was chosen as the preparation method because it was shown to be an efficient extraction method without the possibility of excessive chemical changes of the sample....

  8. Statistical power and optimal design in experiments in which samples of participants respond to samples of stimuli.

    Science.gov (United States)

    Westfall, Jacob; Kenny, David A; Judd, Charles M

    2014-10-01

    Researchers designing experiments in which a sample of participants responds to a sample of stimuli are faced with difficult questions about optimal study design. The conventional procedures of statistical power analysis fail to provide appropriate answers to these questions because they are based on statistical models in which stimuli are not assumed to be a source of random variation in the data, models that are inappropriate for experiments involving crossed random factors of participants and stimuli. In this article, we present new methods of power analysis for designs with crossed random factors, and we give detailed, practical guidance to psychology researchers planning experiments in which a sample of participants responds to a sample of stimuli. We extensively examine 5 commonly used experimental designs, describe how to estimate statistical power in each, and provide power analysis results based on a reasonable set of default parameter values. We then develop general conclusions and formulate rules of thumb concerning the optimal design of experiments in which a sample of participants responds to a sample of stimuli. We show that in crossed designs, statistical power typically does not approach unity as the number of participants goes to infinity but instead approaches a maximum attainable power value that is possibly small, depending on the stimulus sample. We also consider the statistical merits of designs involving multiple stimulus blocks. Finally, we provide a simple and flexible Web-based power application to aid researchers in planning studies with samples of stimuli.

  9. Liquid-solid sample preparation followed by headspace solid-phase microextraction determination of multiclass pesticides in soil.

    Science.gov (United States)

    Durović, Rada D; Dordević, Tijana M; Santrić, Ljiljana R

    2012-01-01

    This paper describes development and validation of a multiresidue method for the determination of five pesticides (terbufos, prochloraz, chloridazon, pendimethalin, and fluorochloridone) belonging to different pesticide groups in soil samples by GC/MS, followed by its application in the analysis of some agricultural soil samples. The method is based on a headspace solid-phase microextraction method. Microextraction conditions, namely temperature, extraction time, and NaCI content, were tested and optimized using a 100 microm polydimethylsiloxane fiber. Three extraction solvents [methanol, methanol-acetone (1 + 1, v/v), and methanol-acetone-hexane (2 + 2 + 1, v/v/v)] and the optimum number of extraction steps within the sample preparation stage were optimized for the extraction procedure. LOD values for all the studied compounds were less than 12 microg/kg. Recovery values for multiple analyses of soil samples fortified at 30 microg/kg of each pesticide were higher than 64%. The method was proven to be repeatable, with RSD lower than 15%.

  10. Multivariate analysis for the optimization of polysaccharide-based nanoparticles prepared by self-assembly.

    Science.gov (United States)

    Pistone, Sara; Qoragllu, Dafina; Smistad, Gro; Hiorth, Marianne

    2016-10-01

    Polysaccharide-based nanoparticles are promising carriers for drug delivery applications. The particle size influences the biodistribution of the nanoparticles; hence size distributions and polydispersity index (PDI) are critical characteristics. However, the preparation of stable particles with a low PDI is a challenging task and is usually based on empirical trials. In this study, we report the use of multivariate evaluation to optimize the formulation factors for the preparation of alginate-zinc nanoparticles by ionotropic gelation. The PDI was selected as the response variable. Particle size, size distributions, zeta potential and pH of the samples were also recorded. Two full factorial (mixed-level) designs were analyzed by partial least squares regression (PLS). In the first design, the influence of the polysaccharide and the crosslinker concentrations were studied. The results revealed that size distributions with a low PDI were obtained by using a low polysaccharide concentrations (0.03-0.05%) and a zinc concentration of 0.03% (w/w). However, a high polysaccharide concentration can be advantageous for drug delivery systems. Therefore, in the second design, a high alginate concentration was used (0.09%) and a reduction in the PDI was obtained by simultaneously increasing the ionic strength of the solvent and the zinc concentration. The multivariate analysis also revealed the interaction between the factors in terms of their effects on the PDI; hence, compared to traditional univariate analyses, the multivariate analysis allowed us to obtain a more complete understanding of the effects of the factors scrutinized. In addition, the results are considered useful in order to avoid extensive empirical tests for future formulation studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Quality by design approach for optimizing the formulation and physical properties of extemporaneously prepared orodispersible films

    NARCIS (Netherlands)

    Visser, J. Caroline; Dohmen, Willem M. C.; Hinrichs, Wouter L. J.; Breitkreutz, Joerg; Frijlink, Henderik W.; Woerdenbag, Herman J.

    2015-01-01

    The quality by design (QbD) approach was applied for optimizing the formulation of extemporaneously prepared orodispersible films (ODFs) using Design-Expert Software. The starting formulation was based on earlier experiments and contained the film forming agents hypromellose and carbomer 974P and th

  12. HPLC analysis of oxindole alkaloids in Uncaria tomentosa: sample preparation and analysis optimisation by factorial design.

    Science.gov (United States)

    Bertol, Gustavo; Franco, Luzia; Oliveira, Brás Heleno de

    2012-01-01

    Uncaria tomentosa ("cat's claw") is widely used for the treatment of some infectious and inflammatory diseases. Oxindole alkaloids are regarded as the most important components responsible for the biological activities attributed to the plant. Their analysis require efficient sample preparation and suitable reference standards but few are commercially available. To develop and validate a HPLC analytical method for oxindole alkaloids in Uncaria tomentosa with emphasis on sample preparation. Factorial experimental designs were used for the optimisation of both sample preparation and chromatographic separation. The optimised sample preparation involved extraction with aqueous ethanol, and the granulometry of the powdered plant material significantly influenced extraction yields. Mitraphylline was used as a calibration reference for the determination of total alkaloids. The method was fully validated and showed good selectivity, linearity (r²  ≥ 0.9996), accuracy (≥ 96%) and precision (RSD < 2.4%). Detection and quantification limits for mitraphylline were 0.8 and 2.4 ppm, respectively. The optimised chromatographic method, using organic buffer in the mobile phase, provided baseline separation of tetracyclic and pentacyclic alkaloids in the samples. Calibration using mitraphylline provided more accurate estimates of total alkaloid content when compared to other available reference alkaloids. Copyright © 2011 John Wiley & Sons, Ltd.

  13. Sample size calculation in cost-effectiveness cluster randomized trials: optimal and maximin approaches.

    Science.gov (United States)

    Manju, Md Abu; Candel, Math J J M; Berger, Martijn P F

    2014-07-10

    In this paper, the optimal sample sizes at the cluster and person levels for each of two treatment arms are obtained for cluster randomized trials where the cost-effectiveness of treatments on a continuous scale is studied. The optimal sample sizes maximize the efficiency or power for a given budget or minimize the budget for a given efficiency or power. Optimal sample sizes require information on the intra-cluster correlations (ICCs) for effects and costs, the correlations between costs and effects at individual and cluster levels, the ratio of the variance of effects translated into costs to the variance of the costs (the variance ratio), sampling and measuring costs, and the budget. When planning, a study information on the model parameters usually is not available. To overcome this local optimality problem, the current paper also presents maximin sample sizes. The maximin sample sizes turn out to be rather robust against misspecifying the correlation between costs and effects at the cluster and individual levels but may lose much efficiency when misspecifying the variance ratio. The robustness of the maximin sample sizes against misspecifying the ICCs depends on the variance ratio. The maximin sample sizes are robust under misspecification of the ICC for costs for realistic values of the variance ratio greater than one but not robust under misspecification of the ICC for effects. Finally, we show how to calculate optimal or maximin sample sizes that yield sufficient power for a test on the cost-effectiveness of an intervention.

  14. Optimal designs of the median run length based double sampling X chart for minimizing the average sample size.

    Directory of Open Access Journals (Sweden)

    Wei Lin Teoh

    Full Text Available Designs of the double sampling (DS X chart are traditionally based on the average run length (ARL criterion. However, the shape of the run length distribution changes with the process mean shifts, ranging from highly skewed when the process is in-control to almost symmetric when the mean shift is large. Therefore, we show that the ARL is a complicated performance measure and that the median run length (MRL is a more meaningful measure to depend on. This is because the MRL provides an intuitive and a fair representation of the central tendency, especially for the rightly skewed run length distribution. Since the DS X chart can effectively reduce the sample size without reducing the statistical efficiency, this paper proposes two optimal designs of the MRL-based DS X chart, for minimizing (i the in-control average sample size (ASS and (ii both the in-control and out-of-control ASSs. Comparisons with the optimal MRL-based EWMA X and Shewhart X charts demonstrate the superiority of the proposed optimal MRL-based DS X chart, as the latter requires a smaller sample size on the average while maintaining the same detection speed as the two former charts. An example involving the added potassium sorbate in a yoghurt manufacturing process is used to illustrate the effectiveness of the proposed MRL-based DS X chart in reducing the sample size needed.

  15. Instrument and method for X-ray diffraction, fluorescence, and crystal texture analysis without sample preparation

    Science.gov (United States)

    Gendreau, Keith (Inventor); Martins, Jose Vanderlei (Inventor); Arzoumanian, Zaven (Inventor)

    2010-01-01

    An X-ray diffraction and X-ray fluorescence instrument for analyzing samples having no sample preparation includes a X-ray source configured to output a collimated X-ray beam comprising a continuum spectrum of X-rays to a predetermined coordinate and a photon-counting X-ray imaging spectrometer disposed to receive X-rays output from an unprepared sample disposed at the predetermined coordinate upon exposure of the unprepared sample to the collimated X-ray beam. The X-ray source and the photon-counting X-ray imaging spectrometer are arranged in a reflection geometry relative to the predetermined coordinate.

  16. SamplingStrata: An R Package for the Optimization of Strati?ed Sampling

    Directory of Open Access Journals (Sweden)

    Giulio Barcaroli

    2014-11-01

    Full Text Available When designing a sampling survey, usually constraints are set on the desired precision levels regarding one or more target estimates (the Ys. If a sampling frame is available, containing auxiliary information related to each unit (the Xs, it is possible to adopt a stratified sample design. For any given strati?cation of the frame, in the multivariate case it is possible to solve the problem of the best allocation of units in strata, by minimizing a cost function sub ject to precision constraints (or, conversely, by maximizing the precision of the estimates under a given budget. The problem is to determine the best stratification in the frame, i.e., the one that ensures the overall minimal cost of the sample necessary to satisfy precision constraints. The Xs can be categorical or continuous; continuous ones can be transformed into categorical ones. The most detailed strati?cation is given by the Cartesian product of the Xs (the atomic strata. A way to determine the best stratification is to explore exhaustively the set of all possible partitions derivable by the set of atomic strata, evaluating each one by calculating the corresponding cost in terms of the sample required to satisfy precision constraints. This is una?ordable in practical situations, where the dimension of the space of the partitions can be very high. Another possible way is to explore the space of partitions with an algorithm that is particularly suitable in such situations: the genetic algorithm. The R package SamplingStrata, based on the use of a genetic algorithm, allows to determine the best strati?cation for a population frame, i.e., the one that ensures the minimum sample cost necessary to satisfy precision constraints, in a multivariate and multi-domain case.

  17. Optimization of solid lipid nanoparticles prepared by a single emulsification-solvent evaporation method

    Directory of Open Access Journals (Sweden)

    Deep Pooja

    2016-03-01

    Full Text Available This data article contains the data related to the research article “Characterization, biorecognitive activity and stability of WGA grafted lipid nanostructures for the controlled delivery of rifampicin” (Pooja et al. 2015 [1]. In the present study, SLN were prepared by a single emulsification-solvent evaporation method and the various steps of SLN preparation are shown in a flow chart. The preparation of SLN was optimized for various formulation variables including type and quantity of lipid, surfactant, amount of co-surfactant and volume of organic phase. Similarly, effect of variables related to homogezation, sonication and stirring processes, on the size and surface potential of SLN was determined and optimized.

  18. Validation of a fully automated robotic setup for preparation of whole blood samples for LC-MS toxicology analysis

    DEFF Research Database (Denmark)

    Andersen, David Wederkinck; Rasmussen, Brian; Linnet, Kristian

    2012-01-01

    A fully automated setup was developed for preparing whole blood samples using a Tecan Evo workstation. By integrating several add-ons to the robotic platform, the flexible setup was able to prepare samples from sample tubes to a 96-well sample plate ready for injection on liquid chromatography...

  19. Recent advances in sample preparation techniques and methods of sulfonamides detection - A review.

    Science.gov (United States)

    Dmitrienko, Stanislava G; Kochuk, Elena V; Apyari, Vladimir V; Tolmacheva, Veronika V; Zolotov, Yury A

    2014-11-19

    Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid-liquid and solid-phase extraction, dispersive liquid-liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed.

  20. Author Contribution to the Pu Handbook II: Chapter 37 LLNL Integrated Sample Preparation Glovebox (TEM) Section

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Mark A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-25

    The development of our Integrated Actinide Sample Preparation Laboratory (IASPL) commenced in 1998 driven by the need to perform transmission electron microscopy studies on naturally aged plutonium and it’s alloys looking for the microstructural effects of the radiological decay process (1). Remodeling and construction of a laboratory within the Chemistry and Materials Science Directorate facilities at LLNL was required to turn a standard radiological laboratory into a Radiological Materials Area (RMA) and Radiological Buffer Area (RBA) containing type I, II and III workplaces. Two inert atmosphere dry-train glove boxes with antechambers and entry/exit fumehoods (Figure 1), having a baseline atmosphere of 1 ppm oxygen and 1 ppm water vapor, a utility fumehood and a portable, and a third double-walled enclosure have been installed and commissioned. These capabilities, along with highly trained technical staff, facilitate the safe operation of sample preparation processes and instrumentation, and sample handling while minimizing oxidation or corrosion of the plutonium. In addition, we are currently developing the capability to safely transfer small metallographically prepared samples to a mini-SEM for microstructural imaging and chemical analysis. The gloveboxes continue to be the most crucial element of the laboratory allowing nearly oxide-free sample preparation for a wide variety of LLNL-based characterization experiments, which includes transmission electron microscopy, electron energy loss spectroscopy, optical microscopy, electrical resistivity, ion implantation, X-ray diffraction and absorption, magnetometry, metrological surface measurements, highpressure diamond anvil cell equation-of-state, phonon dispersion measurements, X-ray absorption and emission spectroscopy, and differential scanning calorimetry. The sample preparation and materials processing capabilities in the IASPL have also facilitated experimentation at world-class facilities such as the

  1. Preparing to Receive and Handle Martian Samples When They Arrive on Earth

    Science.gov (United States)

    McCubbin, Francis M.

    2017-01-01

    The Astromaterials Acquisition and Curation Office at NASA Johnson Space Center (JSC) is responsible for curating all of NASA's extraterrestrial samples. Under the governing document, NASA Policy Directive (NPD) 7100.10F+ derivative NPR 'Curation of Extraterrestrial Materials', JSC is charged with 'The curation of all extraterrestrial material under NASA control, including future NASA missions. 'The Directive goes on to define Curation as including'...documentation, preservation, preparation, and distribution of samples for research, education, and public outreach."

  2. Optimizing the triple-axis spectrometer PANDA at the MLZ for small samples and complex sample environment conditions

    Science.gov (United States)

    Utschick, C.; Skoulatos, M.; Schneidewind, A.; Böni, P.

    2016-11-01

    The cold-neutron triple-axis spectrometer PANDA at the neutron source FRM II has been serving an international user community studying condensed matter physics problems. We report on a new setup, improving the signal-to-noise ratio for small samples and pressure cell setups. Analytical and numerical Monte Carlo methods are used for the optimization of elliptic and parabolic focusing guides. They are placed between the monochromator and sample positions, and the flux at the sample is compared to the one achieved by standard monochromator focusing techniques. A 25 times smaller spot size is achieved, associated with a factor of 2 increased intensity, within the same divergence limits, ± 2 ° . This optional neutron focusing guide shall establish a top-class spectrometer for studying novel exotic properties of matter in combination with more stringent sample environment conditions such as extreme pressures associated with small sample sizes.

  3. Minimalistic sample preparation strategies for LC-MS quantification of large molecule biopharmaceuticals: a case study highlighting alpha-1 antitrypsin protein.

    Science.gov (United States)

    Wright, Katherine; Dufield, Dawn

    2014-01-01

    Large molecule biotherapeutics pose a distinctive bioanalytical challenge for LC-MS assay development, particularly when optimizing sample enrichment steps. Alpha-1 antitrypsin (AAT) is used as an example for highlighting large-molecule assay-development strategies. Two sensitive and selective LC-MS/MS-based quantification assays were developed. Fit-for-purpose assay qualifications for BAL and serum matrices were performed by assessing sensitivity, precision and accuracy, dilution linearity and interferences. Our approach to sample preparation focuses on optimizing the simplest methodology necessary to generate fit-for-purpose bioanalytical assays. To measure AAT protein levels in preclinical species with selectivity and increased assay sensitivity, a minimalistic sample preparation strategy was adopted that included either traditional direct digestion or a more complicated immunoprecipitation enrichment process.

  4. Soil and Water – What is Detectable through Microbiological Sample Preparation Techniques

    Science.gov (United States)

    The concerns of a potential terrorist’s use of biological agents in soil and ground water are articulated by comparisons to major illnesses in this Country involving contaminated drinking water sources. Objectives are focused on the importance of sample preparation in the rapid, ...

  5. Analysis of biopharmaceutical proteins in biological matrices by LC-MS/MS I. Sample preparation

    NARCIS (Netherlands)

    Bischoff, Rainer; Bronsema, Kees J.; van de Merbel, Nico C.

    2013-01-01

    Part I of this review discusses sample-preparation aspects of quantifying biopharmaceutical proteins in complex biological matrices by LC-MS/MS with a focus on blood-derived body fluids. We conclude Part I with a short overview over options for automating the entire analytical procedure, which is

  6. Analysis of biopharmaceutical proteins in biological matrices by LC-MS/MS I. Sample preparation

    NARCIS (Netherlands)

    Bischoff, Rainer; Bronsema, Kees J.; van de Merbel, Nico C.

    2013-01-01

    Part I of this review discusses sample-preparation aspects of quantifying biopharmaceutical proteins in complex biological matrices by LC-MS/MS with a focus on blood-derived body fluids. We conclude Part I with a short overview over options for automating the entire analytical procedure, which is in

  7. Challenges of sample preparation for cross sectional EBSD analysis of electrodeposited nickel films

    DEFF Research Database (Denmark)

    Alimadadi, Hossein; Pantleon, Karen

    2009-01-01

    . Different procedures for sample preparation including mechanical grinding and polishing, electropolishing and focused ion beam milling have been applied to a nickel film electrodeposited on top of an amorphous Ni-P layer on a Cu-substrate. Reliable EBSD analysis of the whole cross section can be obtained...

  8. Sample preparation composite and replicate strategy case studies for assay of solid oral drug products.

    Science.gov (United States)

    Nickerson, Beverly; Harrington, Brent; Li, Fasheng; Guo, Michele Xuemei

    2017-08-16

    Drug product assay is one of several tests required for new drug products to ensure the quality of the product at release and throughout the life cycle of the product. Drug product assay testing is typically performed by preparing a composite sample of multiple dosage units to obtain an assay value representative of the batch. In some cases replicate composite samples may be prepared and the reportable assay value is the average value of all the replicates. In previously published work by Harrington et al. (2014) [5], a sample preparation composite and replicate strategy for assay was developed to provide a systematic approach which accounts for variability due to the analytical method and dosage form with a standard error of the potency assay criteria based on compendia and regulatory requirements. In this work, this sample preparation composite and replicate strategy for assay is applied to several case studies to demonstrate the utility of this approach and its application at various stages of pharmaceutical drug product development. Copyright © 2017. Published by Elsevier B.V.

  9. A novel sample preparation method to avoid influence of embedding medium during nano-indentation

    Science.gov (United States)

    Yujie Meng; Siqun Wang; Zhiyong Cai; Timothy M. Young; Guanben Du; Yanjun Li

    2012-01-01

    The effect of the embedding medium on the nano-indentation measurements of lignocellulosic materials was investigated experimentally using nano-indentation. Both the reduced elastic modulus and the hardness of nonembedded cell walls were found to be lower than those of the embedded samples, proving that the embedding medium used for specimen preparation on cellulosic...

  10. Sample preparation for combined chemical analysis and bioassay application in water quality assessment

    NARCIS (Netherlands)

    Kolkman, A.; Schriks, M.; Brand, W; Bäuerlein, P.S.; van der Kooi, M.M.E.; van Doorn, R.H.; Emke, E.; Reus, A.; van der Linden, S.; de Voogt, P.; Heringa, M.B.

    2013-01-01

    The combination of in vitro bioassays and chemical screening can provide a powerful toolbox to determine biologically relevant compounds in water extracts. In this study, a sample preparation method is evaluated for the suitability for both chemical analysis and in vitro bioassays. A set of 39 chemi

  11. Optimal two-phase sampling design for comparing accuracies of two binary classification rules.

    Science.gov (United States)

    Xu, Huiping; Hui, Siu L; Grannis, Shaun

    2014-02-10

    In this paper, we consider the design for comparing the performance of two binary classification rules, for example, two record linkage algorithms or two screening tests. Statistical methods are well developed for comparing these accuracy measures when the gold standard is available for every unit in the sample, or in a two-phase study when the gold standard is ascertained only in the second phase in a subsample using a fixed sampling scheme. However, these methods do not attempt to optimize the sampling scheme to minimize the variance of the estimators of interest. In comparing the performance of two classification rules, the parameters of primary interest are the difference in sensitivities, specificities, and positive predictive values. We derived the analytic variance formulas for these parameter estimates and used them to obtain the optimal sampling design. The efficiency of the optimal sampling design is evaluated through an empirical investigation that compares the optimal sampling with simple random sampling and with proportional allocation. Results of the empirical study show that the optimal sampling design is similar for estimating the difference in sensitivities and in specificities, and both achieve a substantial amount of variance reduction with an over-sample of subjects with discordant results and under-sample of subjects with concordant results. A heuristic rule is recommended when there is no prior knowledge of individual sensitivities and specificities, or the prevalence of the true positive findings in the study population. The optimal sampling is applied to a real-world example in record linkage to evaluate the difference in classification accuracy of two matching algorithms. Copyright © 2013 John Wiley & Sons, Ltd.

  12. Optimization of techniques for multiple platform testing in small, precious samples such as human chorionic villus sampling.

    Science.gov (United States)

    Pisarska, Margareta D; Akhlaghpour, Marzieh; Lee, Bora; Barlow, Gillian M; Xu, Ning; Wang, Erica T; Mackey, Aaron J; Farber, Charles R; Rich, Stephen S; Rotter, Jerome I; Chen, Yii-der I; Goodarzi, Mark O; Guller, Seth; Williams, John

    2016-11-01

    Multiple testing to understand global changes in gene expression based on genetic and epigenetic modifications is evolving. Chorionic villi, obtained for prenatal testing, is limited, but can be used to understand ongoing human pregnancies. However, optimal storage, processing and utilization of CVS for multiple platform testing have not been established. Leftover CVS samples were flash-frozen or preserved in RNAlater. Modifications to standard isolation kits were performed to isolate quality DNA and RNA from samples as small as 2-5 mg. RNAlater samples had significantly higher RNA yields and quality and were successfully used in microarray and RNA-sequencing (RNA-seq). RNA-seq libraries generated using 200 versus 800-ng RNA showed similar biological coefficients of variation. RNAlater samples had lower DNA yields and quality, which improved by heating the elution buffer to 70 °C. Purification of DNA was not necessary for bisulfite-conversion and genome-wide methylation profiling. CVS cells were propagated and continue to express genes found in freshly isolated chorionic villi. CVS samples preserved in RNAlater are superior. Our optimized techniques provide specimens for genetic, epigenetic and gene expression studies from a single small sample which can be used to develop diagnostics and treatments using a systems biology approach in the prenatal period. © 2016 John Wiley & Sons, Ltd. © 2016 John Wiley & Sons, Ltd.

  13. SU-E-T-295: Simultaneous Beam Sampling and Aperture Shape Optimization for Station Parameter Optimized Radiation Therapy (SPORT)

    Energy Technology Data Exchange (ETDEWEB)

    Zarepisheh, M; Li, R; Xing, L [Stanford UniversitySchool of Medicine, Stanford, CA (United States); Ye, Y [Stanford Univ, Management Science and Engineering, Stanford, Ca (United States); Boyd, S [Stanford University, Electrical Engineering, Stanford, CA (United States)

    2014-06-01

    Purpose: Station Parameter Optimized Radiation Therapy (SPORT) was recently proposed to fully utilize the technical capability of emerging digital LINACs, in which the station parameters of a delivery system, (such as aperture shape and weight, couch position/angle, gantry/collimator angle) are optimized altogether. SPORT promises to deliver unprecedented radiation dose distributions efficiently, yet there does not exist any optimization algorithm to implement it. The purpose of this work is to propose an optimization algorithm to simultaneously optimize the beam sampling and aperture shapes. Methods: We build a mathematical model whose variables are beam angles (including non-coplanar and/or even nonisocentric beams) and aperture shapes. To solve the resulting large scale optimization problem, we devise an exact, convergent and fast optimization algorithm by integrating three advanced optimization techniques named column generation, gradient method, and pattern search. Column generation is used to find a good set of aperture shapes as an initial solution by adding apertures sequentially. Then we apply the gradient method to iteratively improve the current solution by reshaping the aperture shapes and updating the beam angles toward the gradient. Algorithm continues by pattern search method to explore the part of the search space that cannot be reached by the gradient method. Results: The proposed technique is applied to a series of patient cases and significantly improves the plan quality. In a head-and-neck case, for example, the left parotid gland mean-dose, brainstem max-dose, spinal cord max-dose, and mandible mean-dose are reduced by 10%, 7%, 24% and 12% respectively, compared to the conventional VMAT plan while maintaining the same PTV coverage. Conclusion: Combined use of column generation, gradient search and pattern search algorithms provide an effective way to optimize simultaneously the large collection of station parameters and significantly improves

  14. Optimal protein extraction methods from diverse sample types for protein profiling by using Two-Dimensional Electrophoresis (2DE).

    Science.gov (United States)

    Tan, A A; Azman, S N; Abdul Rani, N R; Kua, B C; Sasidharan, S; Kiew, L V; Othman, N; Noordin, R; Chen, Y

    2011-12-01

    There is a great diversity of protein samples types and origins, therefore the optimal procedure for each sample type must be determined empirically. In order to obtain a reproducible and complete sample presentation which view as many proteins as possible on the desired 2DE gel, it is critical to perform additional sample preparation steps to improve the quality of the final results, yet without selectively losing the proteins. To address this, we developed a general method that is suitable for diverse sample types based on phenolchloroform extraction method (represented by TRI reagent). This method was found to yield good results when used to analyze human breast cancer cell line (MCF-7), Vibrio cholerae, Cryptocaryon irritans cyst and liver abscess fat tissue. These types represent cell line, bacteria, parasite cyst and pus respectively. For each type of samples, several attempts were made to methodically compare protein isolation methods using TRI-reagent Kit, EasyBlue Kit, PRO-PREP™ Protein Extraction Solution and lysis buffer. The most useful protocol allows the extraction and separation of a wide diversity of protein samples that is reproducible among repeated experiments. Our results demonstrated that the modified TRI-reagent Kit had the highest protein yield as well as the greatest number of total proteins spots count for all type of samples. Distinctive differences in spot patterns were also observed in the 2DE gel of different extraction methods used for each type of sample.

  15. The role of sample preparation in interpretation of trace element concentration variability in moss bioindication studies

    Science.gov (United States)

    Migaszewski, Z.M.; Lamothe, P.J.; Crock, J.G.; Galuszka, A.; Dolegowska, S.

    2011-01-01

    Trace element concentrations in plant bioindicators are often determined to assess the quality of the environment. Instrumental methods used for trace element determination require digestion of samples. There are different methods of sample preparation for trace element analysis, and the selection of the best method should be fitted for the purpose of a study. Our hypothesis is that the method of sample preparation is important for interpretation of the results. Here we compare the results of 36 element determinations performed by ICP-MS on ashed and on acid-digested (HNO3, H2O2) samples of two moss species (Hylocomium splendens and Pleurozium schreberi) collected in Alaska and in south-central Poland. We found that dry ashing of the moss samples prior to analysis resulted in considerably lower detection limits of all the elements examined. We also show that this sample preparation technique facilitated the determination of interregional and interspecies differences in the chemistry of trace elements. Compared to the Polish mosses, the Alaskan mosses displayed more positive correlations of the major rock-forming elements with ash content, reflecting those elements' geogenic origin. Of the two moss species, P. schreberi from both Alaska and Poland was also highlighted by a larger number of positive element pair correlations. The cluster analysis suggests that the more uniform element distribution pattern of the Polish mosses primarily reflects regional air pollution sources. Our study has shown that the method of sample preparation is an important factor in statistical interpretation of the results of trace element determinations. ?? 2010 Springer-Verlag.

  16. Preparation and characterisation of magnetic nanostructured samples for inelastic neutron scattering experiments

    Energy Technology Data Exchange (ETDEWEB)

    Kreuzpaintner, Wolfgang

    2010-06-22

    Recent advances in thin-film structuring techniques have generated significant interest in the dynamics of spin waves in magnetic nanostructures and the possible use of inelastic neutron scattering (INS) for their investigation. This thesis describes the design and implementation, at GKSS Research Centre, of equipment for preparation of large and laterally submicron and nanometre structured magnetic samples for such future INS experiments. After a brief resume on spin waves in nanostructures, the development work on new purpose-designed equipment, including high vacuum (HV) argon ion beam milling and ultra high vacuum (UHV) e-beam evaporation setups, is described. Ni nanodot as well as Ni and novel Gd nanowire samples were prepared using combinations of sputter deposition, laser interference lithography, argon ion beam milling, e-beam evaporation and self organisation techniques. With reference to sample preparation, epitaxial growth studies for Ni on Si(100) substrate were performed, resulting in the development of a new deposition process, which by thermal tuning allows for the direct epitaxial growth of Ni on Si with unprecedented crystalline quality. The results of various characterisation experiments on the prepared nanostructured samples, including Scanning Electron Microscopy (SEM), microprobe analysis, Atomic and Magnetic Force Microscopy (AFM/MFM), Vibrating Sample Magnetometry (VSM), X-ray Diffraction (XRD) and Reflectivity (XRR), unpolarised and Polarised Neutron Scattering (PNR) and off-specular scattering by X-rays and neutrons using rocking scans and Time-Of-Flight Grazing Incidence Small Angle Neutron Scattering (TOF-GISANS), together with various analysis procedures such as Distorted-Wave Born Approximation (DWBA), are reported. The analysis of a Gd nanowire sample by TOF-GISANS led to a novel evaluation technique which in comparison with single wavelength methods allows portions of reciprocal space to be scanned without changing the angle of

  17. Evaluation of optimized bronchoalveolar lavage sampling designs for characterization of pulmonary drug distribution.

    Science.gov (United States)

    Clewe, Oskar; Karlsson, Mats O; Simonsson, Ulrika S H

    2015-12-01

    Bronchoalveolar lavage (BAL) is a pulmonary sampling technique for characterization of drug concentrations in epithelial lining fluid and alveolar cells. Two hypothetical drugs with different pulmonary distribution rates (fast and slow) were considered. An optimized BAL sampling design was generated assuming no previous information regarding the pulmonary distribution (rate and extent) and with a maximum of two samples per subject. Simulations were performed to evaluate the impact of the number of samples per subject (1 or 2) and the sample size on the relative bias and relative root mean square error of the parameter estimates (rate and extent of pulmonary distribution). The optimized BAL sampling design depends on a characterized plasma concentration time profile, a population plasma pharmacokinetic model, the limit of quantification (LOQ) of the BAL method and involves only two BAL sample time points, one early and one late. The early sample should be taken as early as possible, where concentrations in the BAL fluid ≥ LOQ. The second sample should be taken at a time point in the declining part of the plasma curve, where the plasma concentration is equivalent to the plasma concentration in the early sample. Using a previously described general pulmonary distribution model linked to a plasma population pharmacokinetic model, simulated data using the final BAL sampling design enabled characterization of both the rate and extent of pulmonary distribution. The optimized BAL sampling design enables characterization of both the rate and extent of the pulmonary distribution for both fast and slowly equilibrating drugs.

  18. Optimization of preparation process and characterization of carboxymethyl chitosan/sodium alginate hemostatic sponge

    Science.gov (United States)

    Hu, Z.; Ouyang, Q. Q.; Cheng, Y.; Hong, P. Z.; Liao, M. N.; Chen, F. J.; Li, S. D.

    2017-06-01

    Composite hemostatic sponge was prepared by vacuum freeze-drying using carboxymethyl chitosan and sodium alginate as the main materials and CaCl2 as a crosslinking agent. On the basis of single factor experiments, an orthogonal experiment was carried out to optimize the preparation process of hemostatic sponge. The appearance, water absorption, porosity ratio, and in vitro hemostasis of the sponge were evaluated. The optimum conditions to prepare hemostatic sponge were obtained as follows: mass ratio of sodium alginate to carboxymethyl chitosan 4: 1, mass fraction of CaCl2 2%, and crosslinking temperature 30°C. The hemostatic sponge prepared under such conditions was off-white and porous. Its water absorption and porosity ratio were 3050% and 67.23%, respectively. Meanwhile, the hemostatic sponges had significant in vitro procoagulant activity. Therefore, the hemostatic sponge is expected to be developed as a novel medical material.

  19. Challenges of biological sample preparation for SIMS imaging of elements and molecules at subcellular resolution

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Subhash [Cornell SIMS Laboratory, Department of Earth and Atmospheric Sciences, Snee Hall, Cornell University, Ithaca, NY 14853 (United States)], E-mail: sc40@cornell.edu

    2008-12-15

    Secondary ion mass spectrometry (SIMS) based imaging techniques capable of subcellular resolution characterization of elements and molecules are becoming valuable tools in many areas of biology and medicine. Due to high vacuum requirements of SIMS, the live cells cannot be analyzed directly in the instrument. The sample preparation, therefore, plays a critical role in preserving the native chemical composition for SIMS analysis. This work focuses on the evaluation of frozen-hydrated and frozen freeze-dried sample preparations for SIMS studies of cultured cells with a CAMECA IMS-3f dynamic SIMS ion microscope instrument capable of producing SIMS images with a spatial resolution of 500 nm. The sandwich freeze-fracture method was used for fracturing the cells. The complimentary fracture planes in the plasma membrane were characterized by field-emission secondary electron microscopy (FESEM) in the frozen-hydrated state. The cells fractured at the dorsal surface were used for SIMS analysis. The frozen-hydrated SIMS analysis of individual cells under dynamic primary ion beam (O{sub 2}{sup +}) revealed local secondary ion signal enhancements correlated with the water image signals of {sup 19}(H{sub 3}O){sup +}. A preferential removal of water from the frozen cell matrix in the Z-axis was also observed. These complications render the frozen-hydrated sample type less desirable for subcellular dynamic SIMS studies. The freeze-drying of frozen-hydrated cells, either inside the instrument or externally in a freeze-drier, allowed SIMS imaging of subcellular chemical composition. Morphological evaluations of fractured freeze-dried cells with SEM and confocal laser scanning microscopy (CLSM) revealed well-preserved mitochondria, Golgi apparatus, and stress fibers. SIMS analysis of fractured freeze-dried cells revealed well-preserved chemical composition of even the most highly diffusible ions like K{sup +} and Na{sup +} in physiologically relevant concentrations. The high K

  20. Optimization of the sampling scheme for maps of physical and chemical properties estimated by kriging

    Directory of Open Access Journals (Sweden)

    Gener Tadeu Pereira

    2013-10-01

    Full Text Available The sampling scheme is essential in the investigation of the spatial variability of soil properties in Soil Science studies. The high costs of sampling schemes optimized with additional sampling points for each physical and chemical soil property, prevent their use in precision agriculture. The purpose of this study was to obtain an optimal sampling scheme for physical and chemical property sets and investigate its effect on the quality of soil sampling. Soil was sampled on a 42-ha area, with 206 geo-referenced points arranged in a regular grid spaced 50 m from each other, in a depth range of 0.00-0.20 m. In order to obtain an optimal sampling scheme for every physical and chemical property, a sample grid, a medium-scale variogram and the extended Spatial Simulated Annealing (SSA method were used to minimize kriging variance. The optimization procedure was validated by constructing maps of relative improvement comparing the sample configuration before and after the process. A greater concentration of recommended points in specific areas (NW-SE direction was observed, which also reflects a greater estimate variance at these locations. The addition of optimal samples, for specific regions, increased the accuracy up to 2 % for chemical and 1 % for physical properties. The use of a sample grid and medium-scale variogram, as previous information for the conception of additional sampling schemes, was very promising to determine the locations of these additional points for all physical and chemical soil properties, enhancing the accuracy of kriging estimates of the physical-chemical properties.

  1. A simple sample preparation method for measuring amoxicillin in human plasma by hollow fiber centrifugal ultrafiltration.

    Science.gov (United States)

    Dong, Wei-Chong; Hou, Zi-Li; Jiang, Xin-Hui; Jiang, Ye

    2013-02-01

    A simple sample preparation method has been developed for the determination of amoxicillin in human plasma by hollow fiber centrifugal ultrafiltration (HF-CF-UF). A 400-μL plasma sample was placed directly into the HF-CF-UF device, which consisited of a slim glass tube and a U-shaped hollow fiber. After centrifugation at 1.25 × 10(3) g for 10 min, the filtrate was withdrawn from the hollow fiber and 20 µL was directly injected into the high-performance liquid chromatography (HPLC) for analysis. The calibration curve was linear over the range of 0.1-20 µg/mL (r = 0.9996) and the limit of detection was as low as 0.025 µg/mL. The average recovery and absolute recovery were 99.9% and 84.5%, respectively. Both the intra-day and inter-day precisions (relative standard deviation) were less than 3.1% for three concentrations (0.25, 2.5 and 10 µg/mL). The sample preparation process was simplified. Only after a single centrifugal ultrafiltration can the filtrate be injected directly into HPLC. The present method is simple, sensitive and accurate. It could be effective for the analysis of biological samples with high protein contents, especially for the biopharmaceutical analysis of drugs that use traditional isolation techniques for sample preparation such as the protein precipitation method.

  2. Community-Level Physiological Profiling of Microbial Communities in Constructed Wetlands: Effects of Sample Preparation.

    Science.gov (United States)

    Button, Mark; Weber, Kela; Nivala, Jaime; Aubron, Thomas; Müller, Roland Arno

    2016-03-01

    Community-level physiological profiling (CLPP) using BIOLOG® EcoPlates™ has become a popular method for characterizing and comparing the functional diversity, functional potential, and metabolic activity of heterotrophic microbial communities. The method was originally developed for profiling soil communities; however, its usage has expanded into the fields of ecotoxicology, agronomy, and the monitoring and profiling of microbial communities in various wastewater treatment systems, including constructed wetlands for water pollution control. When performing CLPP on aqueous samples from constructed wetlands, a wide variety of sample characteristics can be encountered and challenges may arise due to excessive solids, color, or turbidity. The aim of this study was to investigate the impacts of different sample preparation methods on CLPP performed on a variety of aqueous samples covering a broad range of physical and chemical characteristics. The results show that using filter paper, centrifugation, or settling helped clarify samples for subsequent CLPP analysis, however did not do so as effectively as dilution for the darkest samples. Dilution was able to provide suitable clarity for the darkest samples; however, 100-fold dilution significantly affected the carbon source utilization patterns (CSUPs), particularly with samples that were already partially or fully clear. Ten-fold dilution also had some effect on the CSUPs of samples which were originally clear; however, the effect was minimal. Based on these findings, for this specific set of samples, a 10-fold dilution provided a good balance between ease of use, sufficient clarity (for dark samples), and limited effect on CSUPs. The process and findings outlined here can hopefully serve future studies looking to utilize CLPP for functional analysis of microbial communities and also assist in comparing data from studies where different sample preparation methods were utilized.

  3. Isolation and purification of heroin from heroin street samples by preparative high performance liquid chromatography.

    Science.gov (United States)

    Guo, Zhen; Zheng, Hui; Lu, Yanzhen; Wei, Yun

    2012-09-10

    The present study established a novel method using preparative high performance liquid chromatography to isolate and purify heroin·HCl from heroin street samples to be used as a reference standard. Different kinds of mobile phases and columns were used, ultimately the mobile phase consisting of hexane-isopropanol-methanol (65:28:7, v/v) and the SIL preparative column prepared in laboratory were selected as the final condition. Heroin was further purified by the drowning-out crystallization method using isopropanol-methanol (50:1, v/v) and hexane as drowning-out anti-solvents and salting-out agents, respectively. The purity was assessed by analytical high performance liquid chromatography and the confirmation of the chemical structure was performed by IR and NMR. About 110.7mg of heroin·HCl at a purity of over 99.52% was obtained from 180mg of heroin street samples which contained 156.15mg of heroin·HCl component by preparative high performance liquid chromatography. This method is suitable for preparing heroin standards in forensic science area.

  4. Changes of the elemental distributions in marine diatoms as a reporter of sample preparation artefacts. A nuclear microscopy application

    Energy Technology Data Exchange (ETDEWEB)

    Godinho, R.M. [Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal); Instituto Português do Mar e da Atmosfera, Lisboa (Portugal); Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Porto (Portugal); Cabrita, M.T. [Instituto Português do Mar e da Atmosfera, Lisboa (Portugal); Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Porto (Portugal); Alves, L.C. [Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Sacavém (Portugal); Pinheiro, T., E-mail: murmur@ctn.ist.utl.pt [Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa, Lisboa (Portugal)

    2015-04-01

    Studies of the elemental composition of whole marine diatoms cells have high interest as they constitute a direct measurement of environmental changes, and allow anticipating consequences of anthropogenic alterations to organisms, ecosystems and global marine geochemical cycles. Nuclear microscopy is a powerful tool allowing direct measurement of whole cells giving qualitative imaging of distribution, and quantitative determination of intracellular concentration. Major obstacles to the analysis of marine microalgae are high medium salinity and the recurrent presence of extracellular exudates produced by algae to maintain colonies in natural media and in vitro. The objective of this paper was to optimize the methodology of sample preparation of marine unicellular algae for elemental analysis with nuclear microscopy, allowing further studies on cellular response to metals. Primary cultures of Coscinodiscus wailesii maintained in vitro were used to optimize protocols for elemental analysis with nuclear microscopy techniques. Adequate cell preparation procedures to isolate the cells from media components and exudates were established. The use of chemical agents proved to be inappropriate for elemental determination and for intracellular morphological analysis. The assessment of morphology and elemental partitioning in cell compartments obtained with nuclear microscopy techniques enabled to infer their function in natural environment and imbalances in exposure condition. Exposure to metal affected C. wailesii morphology and internal elemental distribution.

  5. Optimal spatial sampling techniques for ground truth data in microwave remote sensing of soil moisture

    Science.gov (United States)

    Rao, R. G. S.; Ulaby, F. T.

    1977-01-01

    The paper examines optimal sampling techniques for obtaining accurate spatial averages of soil moisture, at various depths and for cell sizes in the range 2.5-40 acres, with a minimum number of samples. Both simple random sampling and stratified sampling procedures are used to reach a set of recommended sample sizes for each depth and for each cell size. Major conclusions from statistical sampling test results are that (1) the number of samples required decreases with increasing depth; (2) when the total number of samples cannot be prespecified or the moisture in only one single layer is of interest, then a simple random sample procedure should be used which is based on the observed mean and SD for data from a single field; (3) when the total number of samples can be prespecified and the objective is to measure the soil moisture profile with depth, then stratified random sampling based on optimal allocation should be used; and (4) decreasing the sensor resolution cell size leads to fairly large decreases in samples sizes with stratified sampling procedures, whereas only a moderate decrease is obtained in simple random sampling procedures.

  6. Optimal and maximin sample sizes for multicentre cost-effectiveness trials.

    Science.gov (United States)

    Manju, Md Abu; Candel, Math J J M; Berger, Martijn P F

    2015-10-01

    This paper deals with the optimal sample sizes for a multicentre trial in which the cost-effectiveness of two treatments in terms of net monetary benefit is studied. A bivariate random-effects model, with the treatment-by-centre interaction effect being random and the main effect of centres fixed or random, is assumed to describe both costs and effects. The optimal sample sizes concern the number of centres and the number of individuals per centre in each of the treatment conditions. These numbers maximize the efficiency or power for given research costs or minimize the research costs at a desired level of efficiency or power. Information on model parameters and sampling costs are required to calculate these optimal sample sizes. In case of limited information on relevant model parameters, sample size formulas are derived for so-called maximin sample sizes which guarantee a power level at the lowest study costs. Four different maximin sample sizes are derived based on the signs of the lower bounds of two model parameters, with one case being worst compared to others. We numerically evaluate the efficiency of the worst case instead of using others. Finally, an expression is derived for calculating optimal and maximin sample sizes that yield sufficient power to test the cost-effectiveness of two treatments. © The Author(s) 2015.

  7. An Approximate Optimal Relationship in the Sampling Plan with Inspection Errors

    Institute of Scientific and Technical Information of China (English)

    YANG Ji-ping; QIU Wan-hua; Martin NEWBY

    2001-01-01

    The paper presents and proves an approximate optimal relationship between sample size n andacceptance number c in the sampling plans under imperfect inspection which minimize the Bayesian risk. Theconclusion generalizes the result obtained by A. Hald on the assumption that the inspection is perfect.

  8. Optimization of Preparative Separation and Purification of Total Polyphenols from Sargassum tenerrimum by Column Chromatography

    Institute of Scientific and Technical Information of China (English)

    Samee Haider; LI Zhenxing; LIN Hong; Khalid Jamil

    2009-01-01

    Polyphenols from the ethanol extracts of Sargassum tenerrimum (ST) with potent antiallergie effects were studied to optimize separation process through column chromatography. The adsorption and desorption characteristics of three widely used adsorbents: macroporous resin, silica gel, and polyvinylpolypyrrolidone (PVPP), were critically evaluated respectively and studied for the optimization of preparative separation of polyphenols. Static operations on these adsorbents showed that macroporous resin had the best adsorption and desorption capability among the three adsorbents. Dynamic adsorption and desorption with maeroporous resin packed column were also conducted to optimize the parameters such as: with the optimal values shown in brackets, the concentration of extract solution (4 times diluted), pH value (6-7), adsorption speed (3 BVh1, bed volumes/per hour), concentration of ethanol (80%), elution speed (3 BV h-1) and elution volume (7 BV). The chromatographic process so optimized gave a purity of 62.43% from the crude polyphenols, providing a promising basis for large scale preparation of bioactive polyphenols upon further scaling up tests.

  9. Sample-first preparation: a method for surface-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of cyclic oligosaccharides.

    Science.gov (United States)

    Wu, Hsin-Pin; Su, Chih-Lin; Chang, Hui-Chiu; Tseng, Wei-Lung

    2007-08-15

    A new sample preparation method for the analysis of cyclic oligosaccharides in surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is presented. We call this new technique "sample first method", in which a sample is deposited first and then bare gold nanoparticles (AuNPs), which serve as the SALDI matrixes, are added to the top of the sample layer. The use of the sample first method offers significant advantages for improving shot-to-shot reproducibility, enhancing the ionization efficiency of the analyte, and reducing sample preparation time as compared to the dried-droplet method, wherein samples and bare AuNPs are mixed and dried together. The relative standard deviation (RSD) values of the signal intensity as calculated from 65 sample spots was 25% when the sample first methods were applied to the analysis of beta-cyclodextrin. The results were more homogeneous as compared to the outcome using dried-droplet preparation of AuNPs (RSD=66%) and 2,5-dihydroxybenzoic acid (RSD=209%). We also found out that the optimal concentration of AuNP for ionization efficiency is 7.4 nM (4.52x10(12) particles/mL) while the lowest detectable concentration of cyclic oligosaccharides through this approach is 0.25 microM. Except for the cyclic oligosaccharide, the proposed method was also applied to the analyses of other biological samples, including neutral carbohydrate and steroid, aminothiols, and peptides as well as proteins.

  10. Compact low temperature scanning tunneling microscope with in-situ sample preparation capability

    Science.gov (United States)

    Kim, Jungdae; Nam, Hyoungdo; Qin, Shengyong; Kim, Sang-ui; Schroeder, Allan; Eom, Daejin; Shih, Chih-Kang

    2015-09-01

    We report on the design of a compact low temperature scanning tunneling microscope (STM) having in-situ sample preparation capability. The in-situ sample preparation chamber was designed to be compact allowing quick transfer of samples to the STM stage, which is ideal for preparing temperature sensitive samples such as ultra-thin metal films on semiconductor substrates. Conventional spring suspensions on the STM head often cause mechanical issues. To address this problem, we developed a simple vibration damper consisting of welded metal bellows and rubber pads. In addition, we developed a novel technique to ensure an ultra-high-vacuum (UHV) seal between the copper and stainless steel, which provides excellent reliability for cryostats operating in UHV. The performance of the STM was tested from 2 K to 77 K by using epitaxial thin Pb films on Si. Very high mechanical stability was achieved with clear atomic resolution even when using cryostats operating at 77 K. At 2 K, a clean superconducting gap was observed, and the spectrum was easily fit using the BCS density of states with negligible broadening.

  11. Experimental improvements in sample preparation for the track registration technique from dry and solution media

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Navarro, M.J. [Universidad Politecnica de Madrid (UPM), E.T.S.I de Caminos, Canales y Puertos, Profesor Aranguren s/n, 28040 Madrid (Spain)]. E-mail: he04@caminos.upm.es; Pujol, Ll. [Centro de Estudios y Experimentacion de Obras Publicas (CEDEX), Alfonso XII, 3, 28014 Madrid (Spain); Gonzalez-Gonzalez, J.A. [Universidad Politecnica de Madrid (UPM), E.T.S.I de Caminos, Canales y Puertos, Profesor Aranguren s/n, 28040 Madrid (Spain)

    2006-04-15

    This paper describes the sample preparation studies carried out to determine gross alpha activities in waste materials by means of alpha-particle track counting using CR-39 detector. Sample preparation for the track registration technique using evaporation or electroplating methods (also known as conventional 'dry methods') has a number of drawbacks. The distribution of tracks in different areas of the detector surface is non-uniform, so accurate quantitative determinations depend on tedious and time-consuming counting of tracks under an optical microscope. In this paper, we propose the use of tensioactives in sample preparation to achieve uniform track distribution over the entire detector surface, which enables track density to be evaluated by scanning a small representative area. Under our counting conditions, uniform distribution was achieved with 0.2 ml of Teg from a planchetted source. Furthermore, track registration techniques using solution media (also known as the 'wet methods') and conventional 'dry methods' were analysed and compared with the proposed method. The reproducibility of the procedure described in the study was tested by analysing gross alpha activity in two low-level nuclear waste samples at two different laboratories.

  12. Molecularly imprinted polymers for sample preparation and biosensing in food analysis: Progress and perspectives.

    Science.gov (United States)

    Ashley, Jon; Shahbazi, Mohammad-Ali; Kant, Krishna; Chidambara, Vinayaka Aaydha; Wolff, Anders; Bang, Dang Duong; Sun, Yi

    2017-05-15

    Molecularly imprinted polymers (MIPs) are biomimetics which can selectively bind to analytes of interest. One of the most interesting areas where MIPs have shown the biggest potential is food analysis. MIPs have found use as sorbents in sample preparation attributed to the high selectivity and high loading capacity. MIPs have been intensively employed in classical solid-phase extraction and solid-phase microextraction. More recently, MIPs have been combined with magnetic bead extraction, which greatly simplifies sample handling procedures. Studies have consistently shown that MIPs can effectively minimize complex food matrix effects, and improve recoveries and detection limits. In addition to sample preparation, MIPs have also been viewed as promising alternatives to bio-receptors due to the inherent molecular recognition abilities and the high stability in harsh chemical and physical conditions. MIPs have been utilized as receptors in biosensing platforms such as electrochemical, optical and mass biosensors to detect various analytes in food. In this review, we will discuss the current state-of-the-art of MIP synthesis and applications in the context of food analysis. We will highlight the imprinting methods which are applicable for imprinting food templates, summarize the recent progress in using MIPs for preparing and analysing food samples, and discuss the current limitations in the commercialisation of MIPs technology. Finally, future perspectives will be given.

  13. Should the mass of a nanoferrite sample prepared by autocombustion method be considered as a realistic preparation parameter?

    Science.gov (United States)

    Wahba, Adel Maher; Mohamed, Mohamed Bakr

    2017-02-01

    Detectable variations in structural, elastic and magnetic properties have been reported depending on the mass of the cobalt nanoferrite sample prepared by citrate autocombustion method. Heat released during the autocombustion process and its duration are directly proportional to the mass to be prepared, and is thus expected to affect both the crystallite size and the cation distribution giving rise to the reported variations in microstrain, magnetization, and coercivity. Formation of a pure spinel phase has been validated using X-ray diffraction patterns (XRD) and Fourier-transform infrared (FTIR) spectra. Crystallite sizes obtained from Williamson-Hall (W-H) method range from 28-87 nm, being further supported by images of high-resolution transmission electron microscope (HRTEM). Saturation magnetization and coercivity deduced from M-H hysteresis loops show a clear correlation with the cation distribution, which was proposed on the basis of experimentally obtained data of XRD, VSM, and IR. Elastic parameters have been estimated using the cation distribution and FTIR data, with a resulting trend quite opposite to that of the lattice parameter.

  14. Plasma treatment of bulk niobium surface for superconducting rf cavities: Optimization of the experimental conditions on flat samples

    Directory of Open Access Journals (Sweden)

    M. Rašković

    2010-11-01

    Full Text Available Accelerator performance, in particular the average accelerating field and the cavity quality factor, depends on the physical and chemical characteristics of the superconducting radio-frequency (SRF cavity surface. Plasma based surface modification provides an excellent opportunity to eliminate nonsuperconductive pollutants in the penetration depth region and to remove the mechanically damaged surface layer, which improves the surface roughness. Here we show that the plasma treatment of bulk niobium (Nb presents an alternative surface preparation method to the commonly used buffered chemical polishing and electropolishing methods. We have optimized the experimental conditions in the microwave glow discharge system and their influence on the Nb removal rate on flat samples. We have achieved an etching rate of 1.7  μm/min⁡ using only 3% chlorine in the reactive mixture. Combining a fast etching step with a moderate one, we have improved the surface roughness without exposing the sample surface to the environment. We intend to apply the optimized experimental conditions to the preparation of single cell cavities, pursuing the improvement of their rf performance.

  15. A normative inference approach for optimal sample sizes in decisions from experience.

    Science.gov (United States)

    Ostwald, Dirk; Starke, Ludger; Hertwig, Ralph

    2015-01-01

    "Decisions from experience" (DFE) refers to a body of work that emerged in research on behavioral decision making over the last decade. One of the major experimental paradigms employed to study experience-based choice is the "sampling paradigm," which serves as a model of decision making under limited knowledge about the statistical structure of the world. In this paradigm respondents are presented with two payoff distributions, which, in contrast to standard approaches in behavioral economics, are specified not in terms of explicit outcome-probability information, but by the opportunity to sample outcomes from each distribution without economic consequences. Participants are encouraged to explore the distributions until they feel confident enough to decide from which they would prefer to draw from in a final trial involving real monetary payoffs. One commonly employed measure to characterize the behavior of participants in the sampling paradigm is the sample size, that is, the number of outcome draws which participants choose to obtain from each distribution prior to terminating sampling. A natural question that arises in this context concerns the "optimal" sample size, which could be used as a normative benchmark to evaluate human sampling behavior in DFE. In this theoretical study, we relate the DFE sampling paradigm to the classical statistical decision theoretic literature and, under a probabilistic inference assumption, evaluate optimal sample sizes for DFE. In our treatment we go beyond analytically established results by showing how the classical statistical decision theoretic framework can be used to derive optimal sample sizes under arbitrary, but numerically evaluable, constraints. Finally, we critically evaluate the value of deriving optimal sample sizes under this framework as testable predictions for the experimental study of sampling behavior in DFE.

  16. A normative inference approach for optimal sample sizes in decisions from experience

    Directory of Open Access Journals (Sweden)

    Dirk eOstwald

    2015-09-01

    Full Text Available Decisions from experience (DFE refers to a body of work that emerged in research on behavioral decision making over the last decade. One of the major experimental paradigms employed to study experienced-based choice is the sampling paradigm, which serves as a model of decision making under limited knowledge about the statistical structure of the world. In this paradigm respondents are presented with two payoff distributions, which, in contrast to standard approaches in behavioral economics, are specified not in terms of explicit outcome-probability information, but by the opportunity to sample outcomes from each distribution without economic consequences. Participants are encouraged to explore the distributions until they feel confident enough to decide from which they would prefer to draw from in a final trial involving real monetary payoffs. One commonly employed measure to characterize the behavior of participants in the sampling paradigm is the sample size, that is, the number of outcome draws which participants choose to obtain from each distribution prior to terminating sampling. A natural question that arises in this context concerns the optimal sample size, which could be used as a normative benchmark to evaluate human sampling behavior in DFE. In this theoretical manuscript, we relate the DFE sampling paradigm to the classical statistical decision theoretic literature and, under a probabilistic inference assumption, evaluate optimal sample sizes for decisions from experience. In our treatment we go beyond analytically established results by showing how the classical statistical decision theoretic framework can be used to derive optimal sample sizes under arbitrary, but numerically evaluable, constraints. Finally, we critically evaluate the value of deriving optimal sample sizes under this framework as testable predictions for the experimental study of sampling behavior in DFE.

  17. An improved adaptive sampling and experiment design method for aerodynamic optimization

    Institute of Scientific and Technical Information of China (English)

    Huang Jiangtao; Gao Zhenghong; Zhou Zhu; Zhao Ke

    2015-01-01

    Experiment design method is a key to construct a highly reliable surrogate model for numerical optimization in large-scale project. Within the method, the experimental design criterion directly affects the accuracy of the surrogate model and the optimization efficient. According to the shortcomings of the traditional experimental design, an improved adaptive sampling method is pro-posed in this paper. The surrogate model is firstly constructed by basic sparse samples. Then the supplementary sampling position is detected according to the specified criteria, which introduces the energy function and curvature sampling criteria based on radial basis function (RBF) network. Sampling detection criteria considers both the uniformity of sample distribution and the description of hypersurface curvature so as to significantly improve the prediction accuracy of the surrogate model with much less samples. For the surrogate model constructed with sparse samples, the sample uniformity is an important factor to the interpolation accuracy in the initial stage of adaptive sam-pling and surrogate model training. Along with the improvement of uniformity, the curvature description of objective function surface gradually becomes more important. In consideration of these issues, crowdness enhance function and root mean square error (RMSE) feedback function are introduced in C criterion expression. Thus, a new sampling method called RMSE and crowd-ness enhance (RCE) adaptive sampling is established. The validity of RCE adaptive sampling method is studied through typical test function firstly and then the airfoil/wing aerodynamic opti-mization design problem, which has high-dimensional design space. The results show that RCE adaptive sampling method not only reduces the requirement for the number of samples, but also effectively improves the prediction accuracy of the surrogate model, which has a broad prospects for applications.

  18. Approximate Optimal Control of Affine Nonlinear Continuous-Time Systems Using Event-Sampled Neurodynamic Programming.

    Science.gov (United States)

    Sahoo, Avimanyu; Xu, Hao; Jagannathan, Sarangapani

    2017-03-01

    This paper presents an approximate optimal control of nonlinear continuous-time systems in affine form by using the adaptive dynamic programming (ADP) with event-sampled state and input vectors. The knowledge of the system dynamics is relaxed by using a neural network (NN) identifier with event-sampled inputs. The value function, which becomes an approximate solution to the Hamilton-Jacobi-Bellman equation, is generated by using event-sampled NN approximator. Subsequently, the NN identifier and the approximated value function are utilized to obtain the optimal control policy. Both the identifier and value function approximator weights are tuned only at the event-sampled instants leading to an aperiodic update scheme. A novel adaptive event sampling condition is designed to determine the sampling instants, such that the approximation accuracy and the stability are maintained. A positive lower bound on the minimum inter-sample time is guaranteed to avoid accumulation point, and the dependence of inter-sample time upon the NN weight estimates is analyzed. A local ultimate boundedness of the resulting nonlinear impulsive dynamical closed-loop system is shown. Finally, a numerical example is utilized to evaluate the performance of the near-optimal design. The net result is the design of an event-sampled ADP-based controller for nonlinear continuous-time systems.

  19. The beauty of being (label)-free: sample preparation methods for SWATH-MS and next-generation targeted proteomics

    Science.gov (United States)

    Campbell, Kate; Deery, Michael J.; Lilley, Kathryn S.; Ralser, Markus

    2014-01-01

    The combination of qualitative analysis with label-free quantification has greatly facilitated the throughput and flexibility of novel proteomic techniques. However, such methods rely heavily on robust and reproducible sample preparation procedures. Here, we benchmark a selection of in gel, on filter, and in solution digestion workflows for their application in label-free proteomics. Each procedure was associated with differing advantages and disadvantages. The in gel methods interrogated were cost effective, but were limited in throughput and digest efficiency. Filter-aided sample preparations facilitated reasonable processing times and yielded a balanced representation of membrane proteins, but led to a high signal variation in quantification experiments. Two in solution digest protocols, however, gave optimal performance for label-free proteomics. A protocol based on the detergent RapiGest led to the highest number of detected proteins at second-best signal stability, while a protocol based on acetonitrile-digestion, RapidACN, scored best in throughput and signal stability but came second in protein identification. In addition, we compared label-free data dependent (DDA) and data independent (SWATH) acquisition on a TripleTOF 5600 instrument. While largely similar in protein detection, SWATH outperformed DDA in quantification, reducing signal variation and markedly increasing the number of precisely quantified peptides. PMID:24741437

  20. Bio-sample preparation and gas chromatographic determination of benzodiazepines--a review.

    Science.gov (United States)

    Uddin, Mohammad Nasir; Samanidou, Victoria F; Papadoyannis, Ioannis N

    2013-08-01

    Benzodiazepines have become commonly prescribed medicines worldwide in the therapy of anxiety, sleep disorders and convulsive attacks because they are relatively safe, with mild side effects. The availability of rapid, sensitive and selective analytical methods is essential for the determination of these drugs in clinical and forensic cases. Benzodiazepines are usually present at trace levels (μg/mL or ng/mL) in a complex biological matrix, and the potentially interfering compounds need to be removed before analysis. Therefore, a sample preparation technique is often mandatory, both to extract the drugs of interest from the matrices and to increase their concentration. An extended and comprehensive review is presented herein, focusing on bio-sample preparation (pretreatment, extraction and derivatization) and gas chromatographic methods applied for the quantification of 1,4-benzodiazepines.

  1. Fast Determination of Manganese in Milk and Similar Infant Food Samples Using Multivariate Optimization and GF AAS

    Directory of Open Access Journals (Sweden)

    Flávia Regina de Amorim

    2011-01-01

    Full Text Available Manganese is an essential element, but high levels in foods can be toxic mainly for children. A fast and efficient method to determine Mn in milk and other infant foods using slurries and liquid samples is presented. Slurries were prepared in ultrapure water with 10 minutes of sonication. Liquid samples were diluted in ultrapure water when necessary. Multivariate optimization was used to establish some optimal analytical parameters through a fractional factorial design and a central composite design. Slurred and diluted samples were analyzed directly by GF AAS. The method presented limit of detection of (0.98±0.04 μg L−1, characteristic mass of (2.9±0.3 pg (recommended value 2 pg, RSD of 2.3% (n=5, and linear range from 0.98 to 20.0 μg L−1 using iridium as permanent modifier. The accuracy was evaluated analyzing two certified reference materials: nonfat milk powder (SRM1549 and whole milk powder (SRM8435. The powdered samples concentrations were between 0.210 and 26.3 μg g−1.

  2. On the use of ultracentrifugal devices for routine sample preparation in biomolecular magic-angle-spinning NMR.

    Science.gov (United States)

    Mandal, Abhishek; Boatz, Jennifer C; Wheeler, Travis B; van der Wel, Patrick C A

    2017-02-22

    A number of recent advances in the field of magic-angle-spinning (MAS) solid-state NMR have enabled its application to a range of biological systems of ever increasing complexity. To retain biological relevance, these samples are increasingly studied in a hydrated state. At the same time, experimental feasibility requires the sample preparation process to attain a high sample concentration within the final MAS rotor. We discuss these considerations, and how they have led to a number of different approaches to MAS NMR sample preparation. We describe our experience of how custom-made (or commercially available) ultracentrifugal devices can facilitate a simple, fast and reliable sample preparation process. A number of groups have since adopted such tools, in some cases to prepare samples for sedimentation-style MAS NMR experiments. Here we argue for a more widespread adoption of their use for routine MAS NMR sample preparation.

  3. Sample preparation for the analysis of flavors and off-flavors in foods.

    Science.gov (United States)

    Wilkes, J G; Conte, E D; Kim, Y; Holcomb, M; Sutherland, J B; Miller, D W

    2000-06-01

    Off-flavors in foods may originate from environmental pollutants, the growth of microorganisms, oxidation of lipids, or endogenous enzymatic decomposition in the foods. The chromatographic analysis of flavors and off-flavors in foods usually requires that the samples first be processed to remove as many interfering compounds as possible. For analysis of foods by gas chromatography (GC), sample preparation may include mincing, homogenation, centrifugation, distillation, simple solvent extraction, supercritical fluid extraction, pressurized-fluid extraction, microwave-assisted extraction, Soxhlet extraction, or methylation. For high-performance liquid chromatography of amines in fish, cheese, sausage and olive oil or aldehydes in fruit juice, sample preparation may include solvent extraction and derivatization. Headspace GC analysis of orange juice, fish, dehydrated potatoes, and milk requires almost no sample preparation. Purge-and-trap GC analysis of dairy products, seafoods, and garlic may require heating, microwave-mediated distillation, purging the sample with inert gases and trapping the analytes with Tenax or C18, thermal desorption, cryofocusing, or elution with ethyl acetate. Solid-phase microextraction GC analysis of spices, milk and fish can involve microwave-mediated distillation, and usually requires adsorption on poly(dimethyl)siloxane or electrodeposition on fibers followed by thermal desorption. For short-path thermal desorption GC analysis of spices, herbs, coffee, peanuts, candy, mushrooms, beverages, olive oil, honey, and milk, samples are placed in a glass-lined stainless steel thermal desorption tube, which is purged with helium and then heated gradually to desorb the volatiles for analysis. Few of the methods that are available for analysis of food flavors and off-flavors can be described simultaneously as cheap, easy and good.

  4. Fast detection of Noroviruses using a real-time PCR assay and automated sample preparation

    Directory of Open Access Journals (Sweden)

    Schmid Michael

    2004-06-01

    Full Text Available Abstract Background Noroviruses (NoV have become one of the most commonly reported causative agents of large outbreaks of non-bacterial acute gastroenteritis worldwide as well as sporadic gastroenteritis in the community. Currently, reverse transcriptase polymerase chain reaction (RT-PCR assays have been implemented in NoV diagnosis, but improvements that simplify and standardize sample preparation, amplification, and detection will be further needed. The combination of automated sample preparation and real-time PCR offers such refinements. Methods We have designed a new real-time RT-PCR assay on the LightCycler (LC with SYBR Green detection and melting curve analysis (Tm to detect NoV RNA in patient stool samples. The performance of the real-time PCR assay was compared with that obtained in parallel with a commercially available enzyme immunoassay (ELISA for antigen detection by testing a panel of 52 stool samples. Additionally, in a collaborative study with the Baden-Wuerttemberg State Health office, Stuttgart (Germany the real-time PCR results were blindly assessed using a previously well-established nested PCR (nPCR as the reference method, since PCR-based techniques are now considered as the "gold standard" for NoV detection in stool specimens. Results Analysis of 52 clinical stool samples by real-time PCR yielded results that were consistent with reference nPCR results, while marked differences between the two PCR-based methods and antigen ELISA were observed. Our results indicate that PCR-based procedures are more sensitive and specific than antigen ELISA for detecting NoV in stool specimens. Conclusions The combination of automated sample preparation and real-time PCR provided reliable diagnostic results in less time than conventional RT-PCR assays. These benefits make it a valuable tool for routine laboratory practice especially in terms of rapid and appropriate outbreak-control measures in health-care facilities and other settings.

  5. Confronting the ironies of optimal design: Nonoptimal sampling designs with desirable properties

    Science.gov (United States)

    Casman, Elizabeth A.; Naiman, Daniel Q.; Chamberlin, Charles E.

    1988-03-01

    Two sampling designs are developed for the improvement of parameter estimate precision in nonlinear regression, one for when there is uncertainty in the parameter values, and the other for when the correct model formulation is unknown. Although based on concepts of optimal design theory, the design criteria emphasize efficiency rather than optimality. The development is illustrated using a Streeter-Phelps dissolved oxygen-biochemical oxygen demand model.

  6. Optimization on Preparation Conditions of Salidroside Liposome and Its Immunological Activity on PCV-2 in Mice

    Directory of Open Access Journals (Sweden)

    Yibo Feng

    2015-01-01

    Full Text Available The aim of this study was to optimize the preparation conditions of salidroside liposome with high encapsulation efficiency (EE and to study the immunological enhancement activity of salidroside liposome as porcine circovirus type 2 virus (PCV-2 vaccine adjuvant. Response surface methodology (RSM was selected to optimize the conditions for the preparation of salidroside liposome using Design-Expert V8.0.6 software. Three kinds of salidroside liposome adjuvants were prepared to study their adjuvant activity. BALB/c mice were immunized with PCV-2 encapsulated in different kinds of salidroside liposome adjuvants. The PCV-2-specific IgG in immunized mice serum was determined with ELISA. The results showed that when the concentration of ammonium sulfate was 0.26 mol·L−1, ethanol volume 6.5 mL, temperature 43°C, ethanol injection rate 3 mL·min−1, and salidroside liposome could be prepared with high encapsulation efficiency of 94.527%. Salidroside liposome as adjuvant could rapidly induce the production of PCV-2-specific IgG and salidroside liposome I adjuvant proved to provide the best effect among the three kinds of salidroside liposome adjuvants.

  7. Automatic Motion Generation for Robotic Milling Optimizing Stiffness with Sample-Based Planning

    Directory of Open Access Journals (Sweden)

    Julian Ricardo Diaz Posada

    2017-01-01

    Full Text Available Optimal and intuitive robotic machining is still a challenge. One of the main reasons for this is the lack of robot stiffness, which is also dependent on the robot positioning in the Cartesian space. To make up for this deficiency and with the aim of increasing robot machining accuracy, this contribution describes a solution approach for optimizing the stiffness over a desired milling path using the free degree of freedom of the machining process. The optimal motion is computed based on the semantic and mathematical interpretation of the manufacturing process modeled on its components: product, process and resource; and by configuring automatically a sample-based motion problem and the transition-based rapid-random tree algorithm for computing an optimal motion. The approach is simulated on a CAM software for a machining path revealing its functionality and outlining future potentials for the optimal motion generation for robotic machining processes.

  8. Rapid sample preparation method for LC-MS/MS or GC-MS analysis of acrylamide in various food matrices.

    Science.gov (United States)

    Mastovska, Katerina; Lehotay, Steven J

    2006-09-20

    A fast and easy sample preparation procedure for analysis of acrylamide in various food matrices was developed and optimized. In its first step, deuterated acrylamide internal standard is added to 1 g of homogenized sample together with 5 mL of hexane, 10 mL of water, 10 mL of acetonitrile, 4 g of MgSO4, and 0.5 g of NaCl. Water facilitates the extraction of acrylamide; hexane serves for sample defatting; and the salt combination induces separation of water and acetonitrile layers and forces the majority of acrylamide into the acetonitrile layer. After vigorous shaking of the extraction mixture for 1 min and centrifugation, the upper hexane layer is discarded and a 1 mL aliquot of the acetonitrile extract is cleaned up by dispersive solid-phase extraction using 50 mg of primary secondary amine sorbent and 150 mg of anhydrous MgSO4. The final extract is analyzed either by liquid chromatography-tandem mass spectrometry or by gas chromatography-mass spectrometry (in positive chemical ionization mode) using the direct sample introduction technique for rugged large-volume injection.

  9. Development of an automated sample preparation module for environmental monitoring of biowarfare agents.

    Science.gov (United States)

    Hindson, Benjamin J; Brown, Steve B; Marshall, Graham D; McBride, Mary T; Makarewicz, Anthony J; Gutierrez, Dora M; Wolcott, Duane K; Metz, Thomas R; Madabhushi, Ramakrishna S; Dzenitis, John M; Colston, Billy W

    2004-07-01

    An automated sample preparation module, based upon sequential injection analysis (SIA), has been developed for use within an autonomous pathogen detection system. The SIA system interfaced aerosol sampling with multiplexed microsphere immunoassay-flow cytometric detection. Metering and sequestering of microspheres using SIA was found to be reproducible and reliable, over 24-h periods of autonomous operation. Four inbuilt immunoassay controls showed excellent immunoassay and system stability over five days of unattended continuous operation. Titration curves for two biological warfare agents, Bacillus anthracis and Yersinia pestis, obtained using the automated SIA procedure were shown to be similar to those generated using a manual microtiter plate procedure.

  10. Sample preparation: a critical step in the analysis of cholesterol oxidation products.

    Science.gov (United States)

    Georgiou, Christiana A; Constantinou, Michalis S; Kapnissi-Christodoulou, Constantina P

    2014-02-15

    In recent years, cholesterol oxidation products (COPs) have drawn scientific interest, particularly due to their implications on human health. A big number of these compounds have been demonstrated to be cytotoxic, mutagenic, and carcinogenic. The main source of COPs is through diet, and particularly from the consumption of cholesterol-rich foods. This raises questions about the safety of consumers, and it suggests the necessity for the development of a sensitive and a reliable analytical method in order to identify and quantify these components in food samples. Sample preparation is a necessary step in the analysis of COPs in order to eliminate interferences and increase sensitivity. Numerous publications have, over the years, reported the use of different methods for the extraction and purification of COPs. However, no method has, so far, been established as a routine method for the analysis of COPs in foods. Therefore, it was considered important to overview different sample preparation procedures and evaluate the different preparative parameters, such as time of saponification, the type of organic solvents for fat extraction, the stationary phase in solid phase extraction, etc., according to recovery, precision and simplicity.

  11. On-chip sample preparation for complete blood count from raw blood.

    Science.gov (United States)

    Nguyen, John; Wei, Yuan; Zheng, Yi; Wang, Chen; Sun, Yu

    2015-03-21

    This paper describes a monolithic microfluidic device capable of on-chip sample preparation for both RBC and WBC measurements from whole blood. For the first time, on-chip sample processing (e.g. dilution, lysis, and filtration) and downstream single cell measurement were fully integrated to enable sample preparation and single cell analysis from whole blood on a single device. The device consists of two parallel sub-systems that perform sample processing and electrical measurements for measuring RBC and WBC parameters. The system provides a modular environment capable of handling solutions of various viscosities by adjusting the length of channels and precisely controlling mixing ratios, and features a new 'offset' filter configuration for increased duration of device operation. RBC concentration, mean corpuscular volume (MCV), cell distribution width, WBC concentration and differential are determined by electrical impedance measurement. Experimental characterization of over 100,000 cells from 10 patient blood samples validated the system's capability for performing on-chip raw blood processing and measurement.

  12. Gamut Volume Index: a color preference metric based on meta-analysis and optimized colour samples.

    Science.gov (United States)

    Liu, Qiang; Huang, Zheng; Xiao, Kaida; Pointer, Michael R; Westland, Stephen; Luo, M Ronnier

    2017-07-10

    A novel metric named Gamut Volume Index (GVI) is proposed for evaluating the colour preference of lighting. This metric is based on the absolute gamut volume of optimized colour samples. The optimal colour set of the proposed metric was obtained by optimizing the weighted average correlation between the metric predictions and the subjective ratings for 8 psychophysical studies. The performance of 20 typical colour metrics was also investigated, which included colour difference based metrics, gamut based metrics, memory based metrics as well as combined metrics. It was found that the proposed GVI outperformed the existing counterparts, especially for the conditions where correlated colour temperatures differed.

  13. The Role of Vertex Consistency in Sampling-based Algorithms for Optimal Motion Planning

    CERN Document Server

    Arslan, Oktay

    2012-01-01

    Motion planning problems have been studied by both the robotics and the controls research communities for a long time, and many algorithms have been developed for their solution. Among them, incremental sampling-based motion planning algorithms, such as the Rapidly-exploring Random Trees (RRTs), and the Probabilistic Road Maps (PRMs) have become very popular recently, owing to their implementation simplicity and their advantages in handling high-dimensional problems. Although these algorithms work very well in practice, the quality of the computed solution is often not good, i.e., the solution can be far from the optimal one. A recent variation of RRT, namely the RRT* algorithm, bypasses this drawback of the traditional RRT algorithm, by ensuring asymptotic optimality as the number of samples tends to infinity. Nonetheless, the convergence rate to the optimal solution may still be slow. This paper presents a new incremental sampling-based motion planning algorithm based on Rapidly-exploring Random Graphs (RRG...

  14. Improved sample preparation and counting techniques for enhanced tritium measurement sensitivity

    Science.gov (United States)

    Moran, J.; Aalseth, C.; Bailey, V. L.; Mace, E. K.; Overman, C.; Seifert, A.; Wilcox Freeburg, E. D.

    2015-12-01

    Tritium (T) measurements offer insight to a wealth of environmental applications including hydrologic tracking, discerning ocean circulation patterns, and aging ice formations. However, the relatively short half-life of T (12.3 years) limits its effective age dating range. Compounding this limitation is the decrease in atmospheric T content by over two orders of magnitude (from 1000-2000 TU in 1962 to low background proportional counters which, when combined, offer improved T measurement sensitivity (~4.5 mmoles of H2 equivalent) and will help expand the application of T age dating to smaller sample sizes linked to persistent environmental questions despite the limitations above. For instance, this approach can be used to T date ~ 2.2 mmoles of CH4 collected from sample-limited systems including microbial communities, soils, or subsurface aquifers and can be combined with radiocarbon dating to distinguish the methane's formation age from C age in a system. This approach can also expand investigations into soil organic C where the improved sensitivity will permit resolution of soil C into more descriptive fractions and provide direct assessments of the stability of specific classes of organic matter in soils environments. We are employing a multiple step sample preparation system whereby organic samples are first combusted with resulting CO2 and H2O being used as a feedstock to synthesize CH4. This CH4 is mixed with Ar and loaded directly into an ultra-low background proportional counter for measurement of T β decay in a shallow underground laboratory. Analysis of water samples requires only the addition of geologic CO2 feedstock with the sample for methane synthesis. The chemical nature of the preparation techniques enable high sample throughput with only the final measurement requiring T decay with total sample analysis time ranging from 2 -5 weeks depending on T content.

  15. Reducing time and increasing sensitivity in sample preparation for adherent mammalian cell metabolomics.

    Science.gov (United States)

    Lorenz, Matthew A; Burant, Charles F; Kennedy, Robert T

    2011-05-01

    A simple, fast, and reproducible sample preparation procedure was developed for relative quantification of metabolites in adherent mammalian cells using the clonal β-cell line INS-1 as a model sample. The method was developed by evaluating the effect of different sample preparation procedures on high performance liquid chromatography- mass spectrometry quantification of 27 metabolites involved in glycolysis and the tricarboxylic acid cycle on a directed basis as well as for all detectable chromatographic features on an undirected basis. We demonstrate that a rapid water rinse step prior to quenching of metabolism reduces components that suppress electrospray ionization thereby increasing signal for 26 of 27 targeted metabolites and increasing total number of detected features from 237 to 452 with no detectable change of metabolite content. A novel quenching technique is employed which involves addition of liquid nitrogen directly to the culture dish and allows for samples to be stored at -80 °C for at least 7 d before extraction. Separation of quenching and extraction steps provides the benefit of increased experimental convenience and sample stability while maintaining metabolite content similar to techniques that employ simultaneous quenching and extraction with cold organic solvent. The extraction solvent 9:1 methanol: chloroform was found to provide superior performance over acetonitrile, ethanol, and methanol with respect to metabolite recovery and extract stability. Maximal recovery was achieved using a single rapid (∼1 min) extraction step. The utility of this rapid preparation method (∼5 min) was demonstrated through precise metabolite measurements (11% average relative standard deviation without internal standards) associated with step changes in glucose concentration that evoke insulin secretion in the clonal β-cell line INS-1.

  16. Sample Subset Optimization Techniques for Imbalanced and Ensemble Learning Problems in Bioinformatics Applications.

    Science.gov (United States)

    Yang, Pengyi; Yoo, Paul D; Fernando, Juanita; Zhou, Bing B; Zhang, Zili; Zomaya, Albert Y

    2014-03-01

    Data sampling is a widely used technique in a broad range of machine learning problems. Traditional sampling approaches generally rely on random resampling from a given dataset. However, these approaches do not take into consideration additional information, such as sample quality and usefulness. We recently proposed a data sampling technique, called sample subset optimization (SSO). The SSO technique relies on a cross-validation procedure for identifying and selecting the most useful samples as subsets. In this paper, we describe the application of SSO techniques to imbalanced and ensemble learning problems, respectively. For imbalanced learning, the SSO technique is employed as an under-sampling technique for identifying a subset of highly discriminative samples in the majority class. In ensemble learning, the SSO technique is utilized as a generic ensemble technique where multiple optimized subsets of samples from each class are selected for building an ensemble classifier. We demonstrate the utilities and advantages of the proposed techniques on a variety of bioinformatics applications where class imbalance, small sample size, and noisy data are prevalent.

  17. Soybean and lactose in meat products and preparations sampled at retail

    Directory of Open Access Journals (Sweden)

    Filomena Piccolo

    2016-06-01

    Full Text Available Food allergies and intolerances have increased during the last decades and regulatory authorities have taken different measures to prevent and manage consumers’ adverse reactions, including correct labelling of foods. Aim of this work was to search for soybean and lactose in meat products and meat preparations taken from retail in some provinces of Campania Region (Southern Italy and to evaluate the food labels compliance with Regulation (EU n.1169/2011. Soybean and lactose were searched using commercial kits in n. 58 samples of meat products produced in or distributed by 19 establishments, and in n. 55 samples of meat products and n. 8 of meat preparations produced in 21 plants. All samples were selected on the basis of the absence of any information on the labels about the presence of the two searched allergens, with the exception of n. 5 samples tested for lactose. Traces of soybean were detected in 50 out of the 58 examined samples, at concentrations up to 0.93 mg kg–1. Only two samples contained levels above the detection limit of 0.31 mg kg–1. Lactose levels ranging from 0.11 to 2.95 g/100 g, i.e. above the detection limit, were found in all the tested samples (n. 63. The results of the present research underline the need for careful controls and planning by operators as part of the self-control plans, and deserve attention from the competent authorities considering not only the consumers’ health but also the great attention media pay to regulations providing consumers with information on food.

  18. XAFSmass: a program for calculating the optimal mass of XAFS samples

    Science.gov (United States)

    Klementiev, K.; Chernikov, R.

    2016-05-01

    We present a new implementation of the XAFSmass program that calculates the optimal mass of XAFS samples. It has several improvements as compared to the old Windows based program XAFSmass: 1) it is truly platform independent, as provided by Python language, 2) it has an improved parser of chemical formulas that enables parentheses and nested inclusion-to-matrix weight percentages. The program calculates the absorption edge height given the total optical thickness, operates with differently determined sample amounts (mass, pressure, density or sample area) depending on the aggregate state of the sample and solves the inverse problem of finding the elemental composition given the experimental absorption edge jump and the chemical formula.

  19. Rapid Measurement of Food Adulteration with Minimal Sample Preparation and No Chromatography Using Ambient Ionization Mass Spectrometry.

    Science.gov (United States)

    Dalmia, Avinash

    2017-03-01

    A rapid method, with minimal sample preparation and no chromatography, was developed for analyzing food samples such as olive oil and pomegranate juice to measure adulteration with cheaper ingredients using the novel Direct Sample Analysis™ (DSA) ion source in conjunction with a time-of-flight (TOF)-MS. In less than 30 s, with minimal sample preparation and method development, adulteration of olive oil and pomegranate juice with cheaper seed oils and fruit juices, respectively, was measured with DSA/TOF-MS.

  20. Membrane-based sample preparation for ion chromatography-Techniques, instrumental configurations and applications.

    Science.gov (United States)

    Frenzel, Wolfgang; Markeviciute, Inga

    2017-01-06

    Sample preparation is the bottleneck of many analytical methods, including ion chromatography (IC). Procedures based on the application of membranes are important, yet not well appreciated means for clean-up and analyte preconcentration of liquid samples. Filtration, ultrafiltration, the variety of dialysis techniques, i.e. passive dialysis, Donnan dialysis and electrodialysis, as well as gas-diffusion are being reviewed here with respect to their application in combination with IC. Instrumental aspects including hardware requirements, configuration of membrane separation units and membrane characteristics are presented. Operation in batch and flow-through mode is described with emphasis on the latter to in-line coupling with IC, permitting fully automated operation. Attention is also drawn to dialysis probes and microdialysis both providing options for in-situ measurements with inherent selective sampling of analytes and sample preparation. The respective features of the various techniques are outlined with respect to the possibilities of matrix removal and selectivity enhancement. In this article, we provide examples of application of the diverse membrane separation techniques and discuss the benefits and limitations thereof.

  1. Comparison of two sample preparation procedures for HPLC determination of ochratoxin A

    Directory of Open Access Journals (Sweden)

    Vuković Gorica L.

    2009-01-01

    Full Text Available In preparation of samples for chromatographic determination of ochratoxin A, two types of columns were used for sample cleanup (SPE and immunoaffinity columns. The first method consisted of liquid-liquid extraction with a mixture of chloroform and phosphoric acid, followed by ion-exchange cleanup on Waters Oasis MAX columns. The sec­ond method consisted of extraction with a mixture of water and methanol, followed by LCTech OtaCLEAN immunoaf­finity column cleanup. Recoveries of the methods were determined at three levels in three repetitions for maize flour, and they were 84% (%RSD = 19.2 for the first method of sample preparation and 101% (%RSD = 2.2 for the second method. Values of LOQ for OTA were 0.25 and 1.00 μg/kg for the IAC and SPE clean-up procedures, respectively. Both methods comply with present regulations, but the MAX sample clean-up procedure should be used as an alternative, since the immunoaffinity column clean-up procedure is characterized by better reproducibility, accuracy, and efficiency.

  2. An Optimal Dimensionality Sampling Scheme on the Sphere for Antipodal Signals In Diffusion Magnetic Resonance Imaging

    CERN Document Server

    Bates, Alice P; Kennedy, Rodney A

    2015-01-01

    We propose a sampling scheme on the sphere and develop a corresponding spherical harmonic transform (SHT) for the accurate reconstruction of the diffusion signal in diffusion magnetic resonance imaging (dMRI). By exploiting the antipodal symmetry, we design a sampling scheme that requires the optimal number of samples on the sphere, equal to the degrees of freedom required to represent the antipodally symmetric band-limited diffusion signal in the spectral (spherical harmonic) domain. Compared with existing sampling schemes on the sphere that allow for the accurate reconstruction of the diffusion signal, the proposed sampling scheme reduces the number of samples required by a factor of two or more. We analyse the numerical accuracy of the proposed SHT and show through experiments that the proposed sampling allows for the accurate and rotationally invariant computation of the SHT to near machine precision accuracy.

  3. Algorithms for integration of stochastic differential equations using parallel optimized sampling in the Stratonovich calculus

    Science.gov (United States)

    Kiesewetter, Simon; Drummond, Peter D.

    2017-03-01

    A variance reduction method for stochastic integration of Fokker-Planck equations is derived. This unifies the cumulant hierarchy and stochastic equation approaches to obtaining moments, giving a performance superior to either. We show that the brute force method of reducing sampling error by just using more trajectories in a sampled stochastic equation is not the best approach. The alternative of using a hierarchy of moment equations is also not optimal, as it may converge to erroneous answers. Instead, through Bayesian conditioning of the stochastic noise on the requirement that moment equations are satisfied, we obtain improved results with reduced sampling errors for a given number of stochastic trajectories. The method used here converges faster in time-step than Ito-Euler algorithms. This parallel optimized sampling (POS) algorithm is illustrated by several examples, including a bistable nonlinear oscillator case where moment hierarchies fail to converge.

  4. Spatial Prediction and Optimized Sampling Design for Sodium Concentration in Groundwater.

    Science.gov (United States)

    Zahid, Erum; Hussain, Ijaz; Spöck, Gunter; Faisal, Muhammad; Shabbir, Javid; M AbdEl-Salam, Nasser; Hussain, Tajammal

    Sodium is an integral part of water, and its excessive amount in drinking water causes high blood pressure and hypertension. In the present paper, spatial distribution of sodium concentration in drinking water is modeled and optimized sampling designs for selecting sampling locations is calculated for three divisions in Punjab, Pakistan. Universal kriging and Bayesian universal kriging are used to predict the sodium concentrations. Spatial simulated annealing is used to generate optimized sampling designs. Different estimation methods (i.e., maximum likelihood, restricted maximum likelihood, ordinary least squares, and weighted least squares) are used to estimate the parameters of the variogram model (i.e, exponential, Gaussian, spherical and cubic). It is concluded that Bayesian universal kriging fits better than universal kriging. It is also observed that the universal kriging predictor provides minimum mean universal kriging variance for both adding and deleting locations during sampling design.

  5. Subdivision, Sampling, and Initialization Strategies for Simplical Branch and Bound in Global Optimization

    DEFF Research Database (Denmark)

    Clausen, Jens; Zilinskas, A,

    2002-01-01

    two schemes for sampling points of the function: midpoint sampling and vertex sampling. The convergence of the algorithm is proved, and numerical results are presented for the two dimensional case, for which also a special initial covering is presented. (C) 2002 Elsevier Science Ltd. All rights......We consider the problem of optimizing a Lipshitzian function. The branch and bound technique is a well-known solution method, and the key components for this are the subdivision scheme, the bound calculation scheme, and the initialization. For Lipschitzian optimization, the bound calculations...... are based on the sampling of function values. We propose a branch and bound algorithm based on regular simplexes. Initially, the domain in question is covered with regular simplexes, and our subdivision scheme maintains this property. The bound calculation becomes both simple and efficient, and we describe...

  6. A developed wedge fixtures assisted high precision TEM samples pre-thinning method: Towards the batch lamella preparation

    Directory of Open Access Journals (Sweden)

    Dandan Wang

    2017-04-01

    Full Text Available Ion milling, wedge cutting or polishing, and focused ion beam (FIB milling are widely-used techniques for the transmission electron microscope (TEM sample preparation. Especially, the FIB milling provides a site-specific analysis, deposition, and ablation of materials in the micrometer and nanometer scale. However, the cost of FIB tools has been always a significant concern. Since it is inevitable to use the FIB technique, the improvement of efficiency is a key point. Traditional TEM sample preparation with FIB was routinely implemented on a single sample each time. Aiming at cost efficiency, a new pre-thinning technique for batch sample preparation was developed in this paper. The present proposal combines the sample preparation techniques with multi-samples thinning, cross-section scanning electron microscopy (SEM, wedge cutting, FIB and other sample pre-thinning techniques. The new pre-thinning technique is to prepare an edge TEM sample on a grinding and polishing fixture with a slant surface. The thickness of the wedges sample can be measured to 1∼2 μm under optical microscope. Therefore, this fixture is superior to the traditional optical method of estimating the membrane thickness. Moreover, by utilizing a multi-sample holding fixture, more samples can be pre-thinned simultaneously, which significantly improved the productivity of TEM sample preparation.

  7. Evaluation of neon focused ion beam milling for TEM sample preparation.

    Science.gov (United States)

    Pekin, T C; Allen, F I; Minor, A M

    2016-10-01

    Gallium-based focused ion beams generated from liquid-metal sources are widely used in micromachining and sample preparation for transmission electron microscopy, with well-known drawbacks such as sample damage and contamination. In this work, an alternative (neon) focused ion beam generated by a gas field-ionization source is evaluated for the preparation of electron-transparent specimens. To do so, electron-transparent sections of Si and an Al alloy are prepared with both Ga and Ne ion beams for direct comparison. Diffraction-contrast imaging and energy dispersive x-ray spectroscopy are used to evaluate the relative damage induced by the two beams, and cross-sections of milled trenches are examined to compare the implantation depth with theoretical predictions from Monte Carlo simulations. Our results show that for the beam voltages and materials systems investigated, Ne ion beam milling does not significantly reduce the focused ion beam induced artefacts. However, the Ne ion beam does enable more precise milling and may be of interest in cases where Ga contamination cannot be tolerated.

  8. A Novel Sample Preparation for Shotgun Proteomics Characterization of HCPs in Antibodies.

    Science.gov (United States)

    Huang, Lihua; Wang, Ning; Mitchell, Charles E; Brownlee, Tammy; Maple, Steven R; De Felippis, Michael R

    2017-05-16

    Residual host cell proteins (HCPs) in biopharmaceuticals derived from recombinant DNA technology can present potential safety risks to patients or compromise product stability. Thus, the downstream purification process is designed to demonstrate robust removal of these impurities. ELISA using polyclonal anti-HCP antibodies as reagents for capture, detection, and quantitation purposes is most commonly used to monitor HCP removal during process development, but this technique has limitations. More recently, LC-MS for residual HCP characterization has emerged as a powerful tool to support purification process development. However, mass spectrometry needs to overcome the enormous dynamic range to detect low ppm levels of residual HCPs in biopharmaceutical samples. We describe a simple and powerful methodology to characterize residual HCPs in (monoclonal) antibodies by combining a novel sample preparation procedure using trypsin digestion and a shotgun proteomics approach. Differing from the traditional methodology, the sample preparation approach maintains nearly intact antibody while HCPs are digested. Thus, the dynamic range for HCP detection by MS is 1 to 2 orders of magnitude less than the traditional trypsin digestion sample preparation procedure. HCP spiking experiments demonstrated that our method could detect 0.5 ppm of HCP with molecular weight >60 kDa, such as rPLBL2. Application of our method to analyze a high-purity NIST monoclonal antibody standard RM 8670 derived from a murine cell line expression system resulted in detection of 60 mouse HCPs; twice as many as previously reported with 2D-UPLC/IM/MS(E) method. A control monoclonal antibody used for 70 analyses over 450 days demonstrated that our method is robust.

  9. Novel sample preparation method for surfactant containing suppositories: effect of micelle formation on drug recovery.

    Science.gov (United States)

    Kalmár, Éva; Ueno, Konomi; Forgó, Péter; Szakonyi, Gerda; Dombi, György

    2013-09-01

    Rectal drug delivery is currently at the focus of attention. Surfactants promote drug release from the suppository bases and enhance the formulation properties. The aim of our work was to develop a sample preparation method for HPLC analysis for a suppository base containing 95% hard fat, 2.5% Tween 20 and 2.5% Tween 60. A conventional sample preparation method did not provide successful results as the recovery of the drug failed to fulfil the validation criterion 95-105%. This was caused by the non-ionic surfactants in the suppository base incorporating some of the drug, preventing its release. As guidance for the formulation from an analytical aspect, we suggest a well defined surfactant content based on the turbidimetric determination of the CMC (critical micelle formation concentration) in the applied methanol-water solvent. Our CMC data correlate well with the results of previous studies. As regards the sample preparation procedure, a study was performed of the effects of ionic strength and pH on the drug recovery with the avoidance of degradation of the drug during the procedure. Aminophenazone and paracetamol were used as model drugs. The optimum conditions for drug release from the molten suppository base were found to be 100 mM NaCl, 20-40 mM NaOH and a 30 min ultrasonic treatment of the final sample solution. As these conditions could cause the degradation of the drugs in the solution, this was followed by NMR spectroscopy, and the results indicated that degradation did not take place. The determined CMCs were 0.08 mM for Tween 20, 0.06 mM for Tween 60 and 0.04 mM for a combined Tween 20, Tween 60 system. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Sample preparation methods for beeswax characterization by gas chromatography with flame ionization detection.

    Science.gov (United States)

    Jiménez, J J; Bernal, J L; del Nozal, M A J; Martín, M A T; Bernal, J

    2006-10-06

    New and simpler methods of sample preparation to determine several families of compounds in beeswax by conventional and high temperature gas chromatography are proposed. To analyze hydrocarbons and palmitates, a dilution of sample is enough whereas for the total acid content, a hydrolysis and simultaneous methylation with BF3-methanol results more effective than the usual methods; for the total content of alcohols, a further acetylation with acetic anhydride is necessary. Free alcohols are directly acetylated in a sample dissolution but for free acids and monoesterified 1,2,3-propanetriols analysis, a previous extraction with acetonitrile is required. The concentrations of all the compounds studied are expressed in weight percentage referred only to one standard: octadecyl octadecanoate. The precision of the analytical methods has been evaluated showing its importance in the analysis of beeswaxes used in apiculture.

  11. Preparation of finasteride capsules-loaded drug nanoparticles: formulation, optimization, in vitro, and pharmacokinetic evaluation

    Directory of Open Access Journals (Sweden)

    Ahmed TA

    2016-02-01

    Full Text Available Tarek A Ahmed1,2 1Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia; 2Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt Abstract: In this study, optimized freeze-dried finasteride nanoparticles (NPs were prepared from drug nanosuspension formulation that was developed using the bottom–up technique. The effects of four formulation and processing variables that affect the particle size and solubility enhancement of the NPs were explored using the response surface optimization design. The optimized formulation was morphologically characterized using transmission electron microscopy (TEM. Physicochemical interaction among the studied components was investigated. Crystalline change was investigated using X-ray powder diffraction (XRPD. Crystal growth of the freeze-dried NPs was compared to the corresponding aqueous drug nanosuspension. Freeze-dried NPs formulation was subsequently loaded into hard gelatin capsules that were examined for in vitro dissolution and pharmacokinetic behavior. Results revealed that in most of the studied variables, some of the quadratic and interaction effects had a significant effect on the studied responses. TEM image illustrated homogeneity and shape of the prepared NPs. No interaction among components was noticed. XRPD confirmed crystalline state change in the optimized NPs. An enhancement in the dissolution rate of more than 2.5 times from capsules filled with optimum drug NPs, when compared to capsules filled with pure drug, was obtained. Crystal growth, due to Ostwald ripening phenomenon and positive Gibbs free energy, was reduced following lyophilization of the nanosuspension formulation. Pharmacokinetic parameters from drug NPs were superior to that of pure drug and drug microparticles. In conclusion, freeze-dried NPs based on drug nanosuspension formulation is a successful

  12. An Optimal Spatial Sampling Design for Intra-Urban Population Exposure Assessment.

    Science.gov (United States)

    Kumar, Naresh

    2009-02-01

    This article offers an optimal spatial sampling design that captures maximum variance with the minimum sample size. The proposed sampling design addresses the weaknesses of the sampling design that Kanaroglou et al. (2005) used for identifying 100 sites for capturing population exposure to NO(2) in Toronto, Canada. Their sampling design suffers from a number of weaknesses and fails to capture the spatial variability in NO(2) effectively. The demand surface they used is spatially autocorrelated and weighted by the population size, which leads to the selection of redundant sites. The location-allocation model (LAM) available with the commercial software packages, which they used to identify their sample sites, is not designed to solve spatial sampling problems using spatially autocorrelated data. A computer application (written in C++) that utilizes spatial search algorithm was developed to implement the proposed sampling design. This design was implemented in three different urban environments - namely Cleveland, OH; Delhi, India; and Iowa City, IA - to identify optimal sample sites for monitoring airborne particulates.

  13. Estimation of the optimal statistical quality control sampling time intervals using a residual risk measure.

    Directory of Open Access Journals (Sweden)

    Aristides T Hatjimihail

    Full Text Available BACKGROUND: An open problem in clinical chemistry is the estimation of the optimal sampling time intervals for the application of statistical quality control (QC procedures that are based on the measurement of control materials. This is a probabilistic risk assessment problem that requires reliability analysis of the analytical system, and the estimation of the risk caused by the measurement error. METHODOLOGY/PRINCIPAL FINDINGS: Assuming that the states of the analytical system are the reliability state, the maintenance state, the critical-failure modes and their combinations, we can define risk functions based on the mean time of the states, their measurement error and the medically acceptable measurement error. Consequently, a residual risk measure rr can be defined for each sampling time interval. The rr depends on the state probability vectors of the analytical system, the state transition probability matrices before and after each application of the QC procedure and the state mean time matrices. As optimal sampling time intervals can be defined those minimizing a QC related cost measure while the rr is acceptable. I developed an algorithm that estimates the rr for any QC sampling time interval of a QC procedure applied to analytical systems with an arbitrary number of critical-failure modes, assuming any failure time and measurement error probability density function for each mode. Furthermore, given the acceptable rr, it can estimate the optimal QC sampling time intervals. CONCLUSIONS/SIGNIFICANCE: It is possible to rationally estimate the optimal QC sampling time intervals of an analytical system to sustain an acceptable residual risk with the minimum QC related cost. For the optimization the reliability analysis of the analytical system and the risk analysis of the measurement error are needed.

  14. Preparation, formula optimization and antitumor actions of mannitol coupling camptothecin nanoparticles.

    Science.gov (United States)

    Wang, Zhichao; Li, Qingyong; Zhao, Xiuhua; Sun, Baihe; Zhu, Qiaochu; Gao, Wenqing; Hua, Changlong

    2014-04-25

    The purpose of this work is to prepare a formulation using mannitol coupling Camptothecin (CPT) nanoparticles (CPT-NPs) to circumvent the difficult solubilization practice based on central composite experimental statistical design. CPT-NPs were prepared with a high-pressure homogenization technique method. The independent variables considered for the optimization of CPT-NPs were percentage of CPT in raw material (CPT and mannitol), concentration of CPT in working liquid, cycles numbers and homogenizer pressure for drug loading efficiency, particle size and polydispersity index. Analysis of variance (ANOVA) statistical test was used to assess the optimization. The optimized CPT-NPs showed an appropriate drug loading efficiency (18.09 ± 2.13%), a homogeneous particle size (165.33 ± 37.23 nm) and a low polydispersity index (0.29 ± 0.01). The CPT-NPs group show higher inhibition ratio (79.95%) of H22 tumor growth in vivo compared with TPT and CPT at the same dose. Changes in mice body weight demonstrate CPT-NPs have the lower toxicity. The results of biodistribution studies indicated the obviously superiority of CPT-NPs in increasing the accumulation of CPT within tumor. Overall, CPT-NPs under optimum conditions are considered to be potentially feasible to overcome formulation challenges for drug delivery.

  15. Infant food from quality protein maize and chickpea: optimization for preparing and nutritional properties.

    Science.gov (United States)

    Alarcón-Valdez, C; Milán-Carrillo, J; Cárdenas-Valenzuela, O G; Mora-Escobedo, R; Bello-Pérez, L A; Reyes-Moreno, C

    2005-06-01

    The present study had two objectives: to determine the best combination of nixtamalized maize flour (NMF) from quality protein maize and extruded chickpea flour (ECF) for producing an infant food, and to evaluate the nutritional properties of the optimized NMF/ECF mixture and the infant food. Response surface methodology (RSM) was applied to determine the best combination of NMF/ECF; the experimental design (Lattice simplex) generated 11 assays. Mixtures from each assay were evaluated for true protein and available lysine. Each one of 11 mixtures was used for preparing 11 infant foods that were sensory evaluated for acceptability. A common optimum value for the three response variables was obtained utilizing the desirability method. The best combination of NMF/ECF for producing an infant food was NMF = 26.7%/ECF = 73.3%; this optimized mixture had a global desirability of 0.87; it contained 19.72% dry matter (DM) proteins, 6.10% (DM) lipids, 71.45% (DM) carbohydrates, and 2.83% (DM) minerals; its essential amino acids profile covered the amino acids requirements for children 10-12 years old. The infant food prepared from optimized mixture had an in vitro protein digestibility of 87.9%, and a calculated protein efficiency ratio of 1.86. Infant food could be used to support the growth of infants in developing countries.

  16. Determination of optimal samples for robot calibration based on error similarity

    Directory of Open Access Journals (Sweden)

    Tian Wei

    2015-06-01

    Full Text Available Industrial robots are used for automatic drilling and riveting. The absolute position accuracy of an industrial robot is one of the key performance indexes in aircraft assembly, and can be improved through error compensation to meet aircraft assembly requirements. The achievable accuracy and the difficulty of accuracy compensation implementation are closely related to the choice of sampling points. Therefore, based on the error similarity error compensation method, a method for choosing sampling points on a uniform grid is proposed. A simulation is conducted to analyze the influence of the sample point locations on error compensation. In addition, the grid steps of the sampling points are optimized using a statistical analysis method. The method is used to generate grids and optimize the grid steps of a Kuka KR-210 robot. The experimental results show that the method for planning sampling data can be used to effectively optimize the sampling grid. After error compensation, the position accuracy of the robot meets the position accuracy requirements.

  17. Practical Guide to Using Cryoprotectants in Biological Sample Preparation at Cryogenic temperature for Electron Microscopic Studies

    Directory of Open Access Journals (Sweden)

    A-Reum Je

    2011-10-01

    Full Text Available Cryo-fixation enables the preservation of the fine structures of intracellular organelles in a condition that is as close to their native state as possible compared with chemical fixation and room temperature processing. Fixation is the initial step for biological sample preparation in electron microscopy. This step is critically important because the goals of electron microscopic observation are fundamentally dependent on well-preserved specimens resulting from this fixation. In the present work, key components of cryo-fixation, cryoprotectants, are tested with various cell types of interest. The results show that dextran can be easily adapted for use with animal cells and cyanobacteria, whereas 1-hexadecene is applicable to plant and yeast cells. The current report provides useful information on the preparation of cryo-fixed biological specimens using high pressure freezing and freeze-substitution aimed at electron microscopic observation.

  18. Laboratory Investigation of Rivers State Clay Samples for Drilling Mud Preparation

    Directory of Open Access Journals (Sweden)

    Nmegbu, Chukwuma Godwin Jacob

    2014-06-01

    Full Text Available Drilling fluids are an integral part of any oil and gas industry, providing the ease to which wells are drilled to access subsurface reservoir fluids. Certain rheology and mineralogical properties of the clay material used for drilling mud preparation must be critically investigated since clay deposits in different location exhibits different characteristics. Clay samples were collected from three different geographical locations namely; Egbamini (Emolga, Afam Street (Port Harcourt and Oboboru (onelga local government areas in Rivers state. Their rheological and wall building properties were measured in the laboratory to determine their suitability for drilling mud formulation. Results showed that in their respective native states, they proved unsuitable for drilling mud preparation when compared to standard Bentonite because they were observed to show responses far below the required API standards for mud formulation.

  19. Preparation of carbon-nitride bulk samples in the presence of seed carbon-nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. I. [Korea University of Technology and Education, Chonan (Korea, Republic of); Zorov, N. B. [Moscow State University, Moscow (Russian Federation)

    2004-05-15

    A procedure was developed for preparing bulk carbon-nitride crystals from polymeric alpha-C{sub 3}N{sub 4.2} at high pressure and high temperature in the presence of seeds of crystalline carbon-nitride films prepared by using a high-voltage discharge plasma combined with pulsed laser ablation of a graphite target. The samples were evaluated by using X-ray photoelectron spectroscopy (XPS), infrared (IR) spectroscopy, Auger electron spectroscopy (AES), secondary-ion mass spectrometry (SIMS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Notably, XPS studies of the film composition before and after thermobaric treatments demonstrated that the nitrogen composition in the alpha-C{sub 3}N{sub 4.2} material, which initially contained more than 58 % nitrogen, decreased during the annealing process and reached a common, stable composition of approx 45 %. The thermobaric experiments were performed at 10 - 77 kbar and 350 - 1200 .deg. C.

  20. Improved sample preparation for CE-LIF analysis of plant N-glycans.

    Science.gov (United States)

    Nagels, Bieke; Santens, Francis; Weterings, Koen; Van Damme, Els J M; Callewaert, Nico

    2011-12-01

    In view of glycomics studies in plants, it is important to have sensitive tools that allow one to analyze and characterize the N-glycans present on plant proteins in different species. Earlier methods combined plant-based sample preparations with CE-LIF N-glycan analysis but suffered from background contaminations, often resulting in non-reproducible results. This publication describes a reproducible and sensitive protocol for the preparation and analysis of plant N-glycans, based on a combination of the 'in-gel release method' and N-glycan analysis on a multicapillary DNA sequencer. Our protocol makes it possible to analyze plant N-glycans starting from low amounts of plant material with highly reproducible results. The developed protocol was validated for different plant species and plant cells.

  1. On the Effectiveness of Sampling for Evolutionary Optimization in Noisy Environments.

    Science.gov (United States)

    Qian, Chao; Yu, Yang; Tang, Ke; Jin, Yaochu; Yao, Xin; Zhou, Zhi-Hua

    2016-12-16

    In real-world optimization tasks, the objective (i.e., fitness) function evaluation is often disturbed by noise due to a wide range of uncertainties. Evolutionary algorithms are often employed in noisy optimization, where reducing the negative effect of noise is a crucial issue. Sampling is a popular strategy for dealing with noise: to estimate the fitness of a solution, it evaluates the fitness multiple (k) times independently and then uses the sample average to approximate the true fitness. Obviously, sampling can make the fitness estimation closer to the true value, but also increases the estimation cost. Previous studies mainly focused on empirical analysis and design of efficient sampling strategies, while the impact of sampling is unclear from a theoretical viewpoint. In this paper, we show that sampling can speed up noisy evolutionary optimization exponentially via rigorous running time analysis. For the (1+1)-EA solving the OneMax and the LeadingOnes problems under prior (e.g., one-bit) or posterior (e.g., additive Gaussian) noise, we prove that, under a high noise level, the running time can be reduced from exponential to polynomial by sampling. The analysis also shows that a gap of one on the value of k for sampling can lead to an exponential difference on the expected running time, cautioning for a careful selection of k. We further prove by using two illustrative examples that sampling can be more effective for noise handling than parent populations and threshold selection, two strategies that have shown to be robust to noise. Finally, we also show that sampling can be ineffective when noise does not bring a negative impact.

  2. Validation of genetic algorithm-based optimal sampling for ocean data assimilation

    Science.gov (United States)

    Heaney, Kevin D.; Lermusiaux, Pierre F. J.; Duda, Timothy F.; Haley, Patrick J.

    2016-08-01

    Regional ocean models are capable of forecasting conditions for usefully long intervals of time (days) provided that initial and ongoing conditions can be measured. In resource-limited circumstances, the placement of sensors in optimal locations is essential. Here, a nonlinear optimization approach to determine optimal adaptive sampling that uses the genetic algorithm (GA) method is presented. The method determines sampling strategies that minimize a user-defined physics-based cost function. The method is evaluated using identical twin experiments, comparing hindcasts from an ensemble of simulations that assimilate data selected using the GA adaptive sampling and other methods. For skill metrics, we employ the reduction of the ensemble root mean square error (RMSE) between the "true" data-assimilative ocean simulation and the different ensembles of data-assimilative hindcasts. A five-glider optimal sampling study is set up for a 400 km × 400 km domain in the Middle Atlantic Bight region, along the New Jersey shelf-break. Results are compared for several ocean and atmospheric forcing conditions.

  3. 'Adaptive Importance Sampling for Performance Evaluation and Parameter Optimization of Communication Systems'

    NARCIS (Netherlands)

    Remondo Bueno, D.; Srinivasan, R.; Nicola, V.F.; van Etten, Wim; Tattje, H.E.P.

    2000-01-01

    We present new adaptive importance sampling techniques based on stochastic Newton recursions. Their applicability to the performance evaluation of communication systems is studied. Besides bit-error rate (BER) estimation, the techniques are used for system parameter optimization. Two system models

  4. Statistical surrogate model based sampling criterion for stochastic global optimization of problems with constraints

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Su Gil; Jang, Jun Yong; Kim, Ji Hoon; Lee, Tae Hee [Hanyang University, Seoul (Korea, Republic of); Lee, Min Uk [Romax Technology Ltd., Seoul (Korea, Republic of); Choi, Jong Su; Hong, Sup [Korea Research Institute of Ships and Ocean Engineering, Daejeon (Korea, Republic of)

    2015-04-15

    Sequential surrogate model-based global optimization algorithms, such as super-EGO, have been developed to increase the efficiency of commonly used global optimization technique as well as to ensure the accuracy of optimization. However, earlier studies have drawbacks because there are three phases in the optimization loop and empirical parameters. We propose a united sampling criterion to simplify the algorithm and to achieve the global optimum of problems with constraints without any empirical parameters. It is able to select the points located in a feasible region with high model uncertainty as well as the points along the boundary of constraint at the lowest objective value. The mean squared error determines which criterion is more dominant among the infill sampling criterion and boundary sampling criterion. Also, the method guarantees the accuracy of the surrogate model because the sample points are not located within extremely small regions like super-EGO. The performance of the proposed method, such as the solvability of a problem, convergence properties, and efficiency, are validated through nonlinear numerical examples with disconnected feasible regions.

  5. Application of a Dual-Arm Robot in Complex Sample Preparation and Measurement Processes.

    Science.gov (United States)

    Fleischer, Heidi; Drews, Robert Ralf; Janson, Jessica; Chinna Patlolla, Bharath Reddy; Chu, Xianghua; Klos, Michael; Thurow, Kerstin

    2016-10-01

    Automation systems with applied robotics have already been established in industrial applications for many years. In the field of life sciences, a comparable high level of automation can be found in the areas of bioscreening and high-throughput screening. Strong deficits still exist in the development of flexible and universal fully automated systems in the field of analytical measurement. Reasons are the heterogeneous processes with complex structures, which include sample preparation and transport, analytical measurements using complex sensor systems, and suitable data analysis and evaluation. Furthermore, the use of nonstandard sample vessels with various shapes and volumes results in an increased complexity. The direct use of existing automation solutions from bioscreening applications is not possible. A flexible automation system for sample preparation, analysis, and data evaluation is presented in this article. It is applied for the determination of cholesterol in biliary endoprosthesis using gas chromatography-mass spectrometry (GC-MS). A dual-arm robot performs both transport and active manipulation tasks to ensure human-like operation. This general robotic concept also enables the use of manual laboratory devices and equipment and is thus suitable in areas with a high standardization grade.

  6. Preparation of porous n-type silicon sample plates for desorption/ionization on silicon mass spectrometry (DIOS-MS).

    Science.gov (United States)

    Tuomikoski, S; Huikko, K; Grigoras, K; Ostman, P; Kostiainen, R; Baumann, M; Abian, J; Kotiaho, T; Franssila, S

    2002-11-01

    This study focuses on porous silicon (pSi) fabrication methods and properties for desorption ionization on silicon mass spectrometry (DIOS-MS). PSi was prepared using electrochemical etching of n-type silicon in HF-ethanol solution. Porous areas were defined by a double-sided illumination arrangement: front-side porous areas were masked by a stencil mask, eliminating the need for standard photolithography, and backside illumination was used for the backside ohmic contact. Backside illumination improved the uniformity of the porosified areas. Porosification conditions, surface derivatizations and storage conditions were explored to optimize pSi area, pore size and pore depth. Chemical derivatization of the pSi surfaces improved the DIOS-MS performance providing better ionization efficiency and signal stability with lower laser energy. Droplet spreading and drying patterns on pSi were also examined. Pore sizes of 50-200 nm were found to be optimal for droplet evaporation and pore filling with the sample liquid, as measured by DIOS efficiency. With DIOS, significantly better detection sensitivity was obtained (e.g. 150 fmol for midazolam) than with desorption ionization from a standard MALDI steel plate without matrix addition (30 pmol for midazolam). Also the noise that disturbs the detection of low-molecular weight compounds at m/z < 500 with MALDI could be clearly reduced with DIOS. Low background MS spectra and good detection sensitivity at the 100-150 fmol level for pharmaceutical compounds were achieved with DIOS-MS.

  7. Optimization of groundwater sampling approach under various hydrogeological conditions using a numerical simulation model

    Science.gov (United States)

    Qi, Shengqi; Hou, Deyi; Luo, Jian

    2017-09-01

    This study presents a numerical model based on field data to simulate groundwater flow in both the aquifer and the well-bore for the low-flow sampling method and the well-volume sampling method. The numerical model was calibrated to match well with field drawdown, and calculated flow regime in the well was used to predict the variation of dissolved oxygen (DO) concentration during the purging period. The model was then used to analyze sampling representativeness and sampling time. Site characteristics, such as aquifer hydraulic conductivity, and sampling choices, such as purging rate and screen length, were found to be significant determinants of sampling representativeness and required sampling time. Results demonstrated that: (1) DO was the most useful water quality indicator in ensuring groundwater sampling representativeness in comparison with turbidity, pH, specific conductance, oxidation reduction potential (ORP) and temperature; (2) it is not necessary to maintain a drawdown of less than 0.1 m when conducting low flow purging. However, a high purging rate in a low permeability aquifer may result in a dramatic decrease in sampling representativeness after an initial peak; (3) the presence of a short screen length may result in greater drawdown and a longer sampling time for low-flow purging. Overall, the present study suggests that this new numerical model is suitable for describing groundwater flow during the sampling process, and can be used to optimize sampling strategies under various hydrogeological conditions.

  8. Development of a sample preparation procedure of sewage sludge samples for the determination of polycyclic aromatic hydrocarbons based on selective pressurized liquid extraction.

    Science.gov (United States)

    Pena, Maria Teresa; Casais, Maria Carmen; Mejuto, Maria Carmen; Cela, Rafael

    2010-01-22

    An automated, simple and sensitive method based on selective pressurized liquid extraction (SPLE) was developed for the analysis of polycyclic aromatic hydrocarbons in sewage sludge samples. The new sample preparation procedure consists of on-line clean-up by inclusion of sorbents in the extraction cell, and combines elevated temperatures and pressures with liquid solvents to achieve fast and efficient removal of target analytes from complex sewage sludge matrices. The effects of various operational parameters (e.g. sample pretreatment, extraction solvent, temperature, pressure, static time, etc.) on the performance of SPLE procedure were carefully investigated, obtaining the best results when SPLE conditions were fixed at 140 degrees C, 1500 psi, static time of 5 min and n-hexane as extraction solvent. A new programmed temperature vaporization-gas chromatography-tandem mass spectrometry method based on large volume injection (PTV-LVI-GC-MS/MS) was also developed and analytical determinations were performed by high performance liquid chromatography coupled with fluorescence detection and GC-MS/MS. The extraction yields for the different compounds obtained by SPLE ranged from 84.8% to 106.6%. Quantification limits obtained for all of these studied compounds (between 0.0001 and 0.005 microg g(-1), dry mass) were well below the regulatory limits for all compounds considered. To test the accuracy of the SPLE technique, the optimized methodology was applied to the analysis of a certified reference material (sewage sludge (BCR088)) and a reference material (sewage sludge (RTC-CNS312-04)), with excellent results.

  9. Error baseline rates of five sample preparation methods used to characterize RNA virus populations

    Science.gov (United States)

    Kugelman, Jeffrey R.; Wiley, Michael R.; Nagle, Elyse R.; Reyes, Daniel; Pfeffer, Brad P.; Kuhn, Jens H.; Sanchez-Lockhart, Mariano; Palacios, Gustavo F.

    2017-01-01

    Individual RNA viruses typically occur as populations of genomes that differ slightly from each other due to mutations introduced by the error-prone viral polymerase. Understanding the variability of RNA virus genome populations is critical for understanding virus evolution because individual mutant genomes may gain evolutionary selective advantages and give rise to dominant subpopulations, possibly even leading to the emergence of viruses resistant to medical countermeasures. Reverse transcription of virus genome populations followed by next-generation sequencing is the only available method to characterize variation for RNA viruses. However, both steps may lead to the introduction of artificial mutations, thereby skewing the data. To better understand how such errors are introduced during sample preparation, we determined and compared error baseline rates of five different sample preparation methods by analyzing in vitro transcribed Ebola virus RNA from an artificial plasmid-based system. These methods included: shotgun sequencing from plasmid DNA or in vitro transcribed RNA as a basic “no amplification” method, amplicon sequencing from the plasmid DNA or in vitro transcribed RNA as a “targeted” amplification method, sequence-independent single-primer amplification (SISPA) as a “random” amplification method, rolling circle reverse transcription sequencing (CirSeq) as an advanced “no amplification” method, and Illumina TruSeq RNA Access as a “targeted” enrichment method. The measured error frequencies indicate that RNA Access offers the best tradeoff between sensitivity and sample preparation error (1.4−5) of all compared methods. PMID:28182717

  10. Simple, Expendable, 3D-Printed Microfluidic Systems for Sample Preparation of Petroleum.

    Science.gov (United States)

    Kataoka, Érica M; Murer, Rui C; Santos, Jandyson M; Carvalho, Rogério M; Eberlin, Marcos N; Augusto, Fabio; Poppi, Ronei J; Gobbi, Angelo L; Hantao, Leandro W

    2017-03-21

    In this study, we introduce a simple protocol to manufacture disposable, 3D-printed microfluidic systems for sample preparation of petroleum. This platform is produced with a consumer-grade 3D-printer, using fused deposition modeling. Successful incorporation of solid-phase extraction (SPE) to microchip was ensured by facile 3D element integration using proposed approach. This 3D-printed μSPE device was applied to challenging matrices in oil and gas industry, such as crude oil and oil-brine emulsions. Case studies investigated important limitations of nonsilicon and nonglass microchips, namely, resistance to nonpolar solvents and conservation of sample integrity. Microfluidic features remained fully functional even after prolonged exposure to nonpolar solvents (20 min). Also, 3D-printed μSPE devices enabled fast emulsion breaking and solvent deasphalting of petroleum, yielding high recovery values (98%) without compromising maltene integrity. Such finding was ascertained by high-resolution molecular analyses using comprehensive two-dimensional gas chromatography and gas chromatography/mass spectrometry by monitoring important biomarker classes, such as C10 demethylated terpanes, ααα-steranes, and monoaromatic steroids. 3D-Printed chips enabled faster and reliable preparation of maltenes by exhibiting a 10-fold reduction in sample processing time, compared to the reference method. Furthermore, polar (oxygen-, nitrogen-, and sulfur-containing) analytes found in low-concentrations were analyzed by Fourier transform ion cyclotron resonance mass spectrometry. Analysis results demonstrated that accurate characterization may be accomplished for most classes of polar compounds, except for asphaltenes, which exhibited lower recoveries (82%) due to irreversible adsorption to sorbent phase. Therefore, 3D-printing is a compelling alternative to existing microfabrication solutions, as robust devices were easy to prepare and operate.

  11. Review of sample preparation strategies for MS-based metabolomic studies in industrial biotechnology.

    Science.gov (United States)

    Causon, Tim J; Hann, Stephan

    2016-09-28

    Fermentation and cell culture biotechnology in the form of so-called "cell factories" now play an increasingly significant role in production of both large (e.g. proteins, biopharmaceuticals) and small organic molecules for a wide variety of applications. However, associated metabolic engineering optimisation processes relying on genetic modification of organisms used in cell factories, or alteration of production conditions remain a challenging undertaking for improving the final yield and quality of cell factory products. In addition to genomic, transcriptomic and proteomic workflows, analytical metabolomics continues to play a critical role in studying detailed aspects of critical pathways (e.g. via targeted quantification of metabolites), identification of biosynthetic intermediates, and also for phenotype differentiation and the elucidation of previously unknown pathways (e.g. via non-targeted strategies). However, the diversity of primary and secondary metabolites and the broad concentration ranges encompassed during typical biotechnological processes means that simultaneous extraction and robust analytical determination of all parts of interest of the metabolome is effectively impossible. As the integration of metabolome data with transcriptome and proteome data is an essential goal of both targeted and non-targeted methods addressing production optimisation goals, additional sample preparation steps beyond necessary sampling, quenching and extraction protocols including clean-up, analyte enrichment, and derivatisation are important considerations for some classes of metabolites, especially those present in low concentrations or exhibiting poor stability. This contribution critically assesses the potential of current sample preparation strategies applied in metabolomic studies of industrially-relevant cell factory organisms using mass spectrometry-based platforms primarily coupled to liquid-phase sample introduction (i.e. flow injection, liquid

  12. Effects of sample preparation conditions on biomolecular solid-state NMR lineshapes

    Energy Technology Data Exchange (ETDEWEB)

    Jakeman, David L.; Mitchell, Dan J.; Shuttleworth, Wendy A.; Evans, Jeremy N.S. [Washington State University, Department of Biochemistry and Biophysics (United States)

    1998-10-15

    Sample preparation conditions with the 46 kDa enzyme complex of 5-enolpyruvyl-shikimate-3-phosphate (EPSP) synthase, shikimate-3-phosphate (S3P) and glyphosate (GLP) have been examined in an attempt to reduce linewidths in solid-state NMR spectra. The linewidths of {sup 13}P resonances associated with enzyme bound S3P and GLP in the lyophilized ternary complex have been reduced to 150 {+-} 12 Hz and 125 {+-} 7 Hz respectively, by a variety of methods involving additives and freezing techniques.

  13. Optimized preparation of zinc-inorganic antibacterial material containing samariumusing response surface methodology

    Institute of Scientific and Technical Information of China (English)

    毛翠萍; 张彬; 唐晓宁; 李欢; 何素琼

    2014-01-01

    A Box-Behnken design (BBD) of response surface methodology (RSM) was used to optimize the preparation of the Zn-Sm antibacterial white carbon black by the sol-gel method. The statistical analysis of the results showed that the particle size of the Zn-Sm antibacterial white carbon black was significantly affected by the reaction time, reaction temperature and the stirring speed. According to analysis of variance (ANOVA), the values of the determination coefficient (R2=0.9821) and the "Pred R-Squared" of 0.8227 were in reasonable agreement with the "Adj R-Squared" of 0.9591. It was indicated that this model could be used to navigate the design space. The optimized reaction time, temperature and the stirring speed were 0.88 h, 87.83 ºC, and 473.45 r/min, respec-tively. In addition, the bacteriostasis rate of the product was about 97.92%.

  14. A Simplified Approach for Two-Dimensional Optimal Controlled Sampling Designs

    Directory of Open Access Journals (Sweden)

    Neeraj Tiwari

    2014-01-01

    Full Text Available Controlled sampling is a unique method of sample selection that minimizes the probability of selecting nondesirable combinations of units. Extending the concept of linear programming with an effective distance measure, we propose a simple method for two-dimensional optimal controlled selection that ensures zero probability to nondesired samples. Alternative estimators for population total and its variance have also been suggested. Some numerical examples have been considered to demonstrate the utility of the proposed procedure in comparison to the existing procedures.

  15. Optimizing headspace sampling temperature and time for analysis of volatile oxidation products in fish oil

    DEFF Research Database (Denmark)

    Rørbæk, Karen; Jensen, Benny

    1997-01-01

    Headspace-gas chromatography (HS-GC), based on adsorption to Tenax GR(R), thermal desorption and GC, has been used for analysis of volatiles in fish oil. To optimize sam sampling conditions, the effect of heating the fish oil at various temperatures and times was evaluated from anisidine values (......) and HS-CC. AV indicated sample degradations at 90 degrees C but only small alterations between 60 and 75 degrees C. HS-GC showed increasing response with temperature and rime. Purging at 75 degrees C for 45 min was selected as the preferred sampling condition for oxidized fish oil....

  16. ON DEVELOPMENT OF OPTIMAL METALLURGICAL PROCESS FOR PREPARATION OF A NEW GENERATION OF INTERMETALLIC ALLOYS

    Directory of Open Access Journals (Sweden)

    Viliam Hrnčiar

    2009-06-01

    Full Text Available Intermetallic TiAl based alloys are used in extreme conditions, e.g. high temperature, aggressive atmosphere and combined high temperature mechanical loading. The contribution deals with development and optimization of plasma melting metallurgical process in new developed crystallizer with rotational and axial movement of melt, for preparation of new intermetallic alloys based on Ti-(45-48Al-(1-10Ta (at.%. The melting process parameters and their influence to final microstructure and properties of alloys are discussed. The aim of this work is to produce alloys with lower number of technological steps necessary to achieve chemical composition, homogeneity and purity as well.

  17. Optimized methods for high-throughput analysis of hair samples for American black bears (Ursus americanus

    Directory of Open Access Journals (Sweden)

    Thea V Kristensen

    2011-06-01

    Full Text Available Noninvasive sampling has revolutionized the study of species that are difficult or dangerous to study using traditional methods. Early studies were often confined to small populations as genotyping large numbers of samples was prohibitively costly and labor intensive. Here we describe optimized protocols designed to reduce the costs and effort required for microsatellite genotyping and sex determination for American black bears (Ursus americanus. We redesigned primers for six microsatellite loci, designed novel primers for the amelogenin gene for genetic determination of sex, and optimized conditions for a nine-locus multiplex PCR. Our high-throughput methods will enable researchers to include larger sample sizes in studies of black bears, providing data in a timely fashion that can be used to inform population management.

  18. Preparation of finasteride capsules-loaded drug nanoparticles: formulation, optimization, in vitro, and pharmacokinetic evaluation

    Science.gov (United States)

    Ahmed, Tarek A

    2016-01-01

    In this study, optimized freeze-dried finasteride nanoparticles (NPs) were prepared from drug nanosuspension formulation that was developed using the bottom–up technique. The effects of four formulation and processing variables that affect the particle size and solubility enhancement of the NPs were explored using the response surface optimization design. The optimized formulation was morphologically characterized using transmission electron microscopy (TEM). Physicochemical interaction among the studied components was investigated. Crystalline change was investigated using X-ray powder diffraction (XRPD). Crystal growth of the freeze-dried NPs was compared to the corresponding aqueous drug nanosuspension. Freeze-dried NPs formulation was subsequently loaded into hard gelatin capsules that were examined for in vitro dissolution and pharmacokinetic behavior. Results revealed that in most of the studied variables, some of the quadratic and interaction effects had a significant effect on the studied responses. TEM image illustrated homogeneity and shape of the prepared NPs. No interaction among components was noticed. XRPD confirmed crystalline state change in the optimized NPs. An enhancement in the dissolution rate of more than 2.5 times from capsules filled with optimum drug NPs, when compared to capsules filled with pure drug, was obtained. Crystal growth, due to Ostwald ripening phenomenon and positive Gibbs free energy, was reduced following lyophilization of the nanosuspension formulation. Pharmacokinetic parameters from drug NPs were superior to that of pure drug and drug microparticles. In conclusion, freeze-dried NPs based on drug nanosuspension formulation is a successful technique in enhancing stability, solubility, and in vitro dissolution of poorly water-soluble drugs with possible impact on the drug bioavailability. PMID:26893559

  19. Sample preparation and separation techniques for bioanalysis of morphine and related substances.

    Science.gov (United States)

    Hansen, Steen Honoré

    2009-03-01

    In present time the use or misuse of morphine and its derivatives are monitored by assaying the presence of the drug and its metabolites in biofluids. In the present review, focus is placed on the sample preparation and on the separation techniques used in the current best practices of bioanalysis of morphine and its major metabolites. However, as methods for testing the misuse of heroin, a morphine derivative, often involve bioanalytical methods that cover a number of other illicit drug substances, such methods are also included in the review. Furthermore, the review also includes bioanalysis in a broader perspective as analysis of plant materials, cell cultures and environmental samples. The review is not intended to cover all publications that include bioanalysis of morphine but is more to be considered a view into the current best practices of bioanalysis of morphine, its metabolites and other related substances.

  20. Capacitive deionization on-chip as a method for microfluidic sample preparation.

    Science.gov (United States)

    Roelofs, Susan H; Kim, Bumjoo; Eijkel, Jan C T; Han, Jongyoon; van den Berg, Albert; Odijk, Mathieu

    2015-03-21

    Desalination as a sample preparation step is essential for noise reduction and reproducibility of mass spectrometry measurements. A specific example is the analysis of proteins for medical research and clinical applications. Salts and buffers that are present in samples need to be removed before analysis to improve the signal-to-noise ratio. Capacitive deionization is an electrostatic desalination (CDI) technique which uses two porous electrodes facing each other to remove ions from a solution. Upon the application of a potential of 0.5 V ions migrate to the electrodes and are stored in the electrical double layer. In this article we demonstrate CDI on a chip, and desalinate a solution by the removal of 23% of Na(+) and Cl(-) ions, while the concentration of a larger molecule (FITC-dextran) remains unchanged. For the first time impedance spectroscopy is introduced to monitor the salt concentration in situ in real-time in between the two desalination electrodes.

  1. Matrix compatible solid phase microextraction coating, a greener approach to sample preparation in vegetable matrices.

    Science.gov (United States)

    Naccarato, Attilio; Pawliszyn, Janusz

    2016-09-01

    This work proposes the novel PDMS/DVB/PDMS fiber as a greener strategy for analysis by direct immersion solid phase microextraction (SPME) in vegetables. SPME is an established sample preparation approach that has not yet been adequately explored for food analysis in direct immersion mode due to the limitations of the available commercial coatings. The robustness and endurance of this new coating were investigated by direct immersion extractions in raw blended vegetables without any further sample preparation steps. The PDMS/DVB/PDMS coating exhibited superior features related to the capability of the external PDMS layer to protect the commercial coating, and showed improvements in terms of extraction capability and in the cleanability of the coating surface. In addition to having contributed to the recognition of the superior features of this new fiber concept before commercialization, the outcomes of this work serve to confirm advancements in the matrix compatibility of the PDMS-modified fiber, and open new prospects for the development of greener high-throughput analytical methods in food analysis using solid phase microextraction in the near future.

  2. Performance Evaluation of Fast Microfluidic Thermal Lysis of Bacteria for Diagnostic Sample Preparation

    Directory of Open Access Journals (Sweden)

    Evangelyn C. Alocilja

    2013-01-01

    Full Text Available Development of new diagnostic platforms that incorporate lab-on-a-chip technologies for portable assays is driving the need for rapid, simple, low cost methods to prepare samples for downstream processing or detection. An important component of the sample preparation process is cell lysis. In this work, a simple microfluidic thermal lysis device is used to quickly release intracellular nucleic acids and proteins without the need for additional reagents or beads used in traditional chemical or mechanical methods (e.g., chaotropic salts or bead beating. On-chip lysis is demonstrated in a multi-turn serpentine microchannel with external temperature control via an attached resistive heater. Lysis was confirmed for Escherichia coli by fluorescent viability assay, release of ATP measured with bioluminescent assay, release of DNA measured by fluorometry and qPCR, as well as bacterial culture. Results comparable to standard lysis techniques were achievable at temperatures greater than 65 °C and heating durations between 1 and 60 s.

  3. Semiautomated Sample Preparation for Protein Stability and Formulation Screening via Buffer Exchange.

    Science.gov (United States)

    Ying, William; Levons, Jaquan K; Carney, Andrea; Gandhi, Rajesh; Vydra, Vicky; Rubin, A Erik

    2016-06-01

    A novel semiautomated buffer exchange process workflow was developed to enable efficient early protein formulation screening. An antibody fragment protein, BMSdab, was used to demonstrate the workflow. The process afforded 60% to 80% cycle time and scientist time savings and significant material efficiencies. These efficiencies ultimately facilitated execution of this stability work earlier in the drug development process, allowing this tool to inform the developability of potential candidates for development from a formulation perspective. To overcome the key technical challenges, the protein solution was buffer-exchanged by centrifuge filtration into formulations for stability screening in a 96-well plate with an ultrafiltration membrane, leveraging automated liquid handling and acoustic volume measurements to allow several cycles of exchanges. The formulations were transferred into a vacuum manifold and sterile filtered into a rack holding 96 glass vials. The vials were sealed with a capmat of individual caps and placed in stability stations. Stability of the samples prepared by this process and by the standard process was demonstrated to be comparable. This process enabled screening a number of formulations of a protein at an early pharmaceutical development stage with a short sample preparation time.

  4. Sampling scheme optimization for diffuse optical tomography based on data and image space rankings

    Science.gov (United States)

    Sabir, Sohail; Kim, Changhwan; Cho, Sanghoon; Heo, Duchang; Kim, Kee Hyun; Ye, Jong Chul; Cho, Seungryong

    2016-10-01

    We present a methodology for the optimization of sampling schemes in diffuse optical tomography (DOT). The proposed method exploits singular value decomposition (SVD) of the sensitivity matrix, or weight matrix, in DOT. Two mathematical metrics are introduced to assess and determine the optimum source-detector measurement configuration in terms of data correlation and image space resolution. The key idea of the work is to weight each data measurement, or rows in the sensitivity matrix, and similarly to weight each unknown image basis, or columns in the sensitivity matrix, according to their contribution to the rank of the sensitivity matrix, respectively. The proposed metrics offer a perspective on the data sampling and provide an efficient way of optimizing the sampling schemes in DOT. We evaluated various acquisition geometries often used in DOT by use of the proposed metrics. By iteratively selecting an optimal sparse set of data measurements, we showed that one can design a DOT scanning protocol that provides essentially the same image quality at a much reduced sampling.

  5. A generic sample preparation approach for LC–MS/MS bioanalysis of therapeutic monoclonal antibodies in serum applied to Infliximab

    Directory of Open Access Journals (Sweden)

    Anne J. Kleinnijenhuis

    2015-01-01

    Full Text Available In this study, we developed a generic bioanalytical workflow providing sensitive, specific, and accurate absolute quantification of therapeutic monoclonal antibodies in serum. The workflow involves magnetic beads coated with protein A to pull-down therapeutic monoclonal antibodies with affinity for protein A from the biological matrix, followed by tryptic digestion and LC-MS/MS quantification of a unique signature peptide, considering of course the matrix of interest and other present mAbs, if applicable. The feasibility of this approach was demonstrated for Infliximab (trade name Remicade in rat serum. The assigned signature peptide was monitored in the selected reaction monitoring (SRM mode. Assay variability was determined to be below 20%, except at the QC low level, which was provided through optimization of the sample preparation and monitoring of the LC-MS/MS using a stable isotope labeled signature peptide as internal standard. The 100 ng/ml lower limit of quantification using only 25 μl sample volume, is generally considered as sufficient for pharmaceutical development purposes for monoclonal antibodies.

  6. Determination of Mycotoxins in Brown Rice Using QuEChERS Sample Preparation and UHPLC-MS-MS.

    Science.gov (United States)

    Jettanajit, Adisorn; Nhujak, Thumnoon

    2016-01-01

    QuEChERS sample preparation was optimized and validated using solvent extraction with 10% (v/v) acetic acid-containing acetonitrile in the presence of four salts (anh. MgSO4, NaCl, sodium citrate tribasic dihydrate and sodium citrate dibasic sesquihydrate) and dispersive solid-phase extraction with mixed sorbents (octadecylsilane, primary and secondary amine and silica sorbents) for an ultra high performance liquid chromatography-tandem mass spectrometric determination of nine mycotoxins in brown rice: aflatoxins (AFB1, AFB2, AFG1 and AFG2), fumonisins (FB1 and FB2), deoxynivalenol, ochratoxin A and zearalenone (ZON). Our developed method allows for the determination of trace levels of mycotoxins with method detection limits in the range of 1.4-25 µg/kg, below the maximum limits of EU regulations, and with an acceptable accuracy and precision, and recoveries in the range of 81-101% with relative standard deviations of 5-19% over a mycotoxin concentration range of 5.0-1,000 µg/kg. Six out of fourteen real samples of brown rice were found to be contaminated with at least one of these mycotoxins, ranging from 2.49-5.41 µg/kg of FB1, 4.33 ± 0.04 µg/kg of FB2 and 6.10-14.88 µg/kg of ZON.

  7. Determination of the optimal sample size for a clinical trial accounting for the population size.

    Science.gov (United States)

    Stallard, Nigel; Miller, Frank; Day, Simon; Hee, Siew Wan; Madan, Jason; Zohar, Sarah; Posch, Martin

    2017-07-01

    The problem of choosing a sample size for a clinical trial is a very common one. In some settings, such as rare diseases or other small populations, the large sample sizes usually associated with the standard frequentist approach may be infeasible, suggesting that the sample size chosen should reflect the size of the population under consideration. Incorporation of the population size is possible in a decision-theoretic approach either explicitly by assuming that the population size is fixed and known, or implicitly through geometric discounting of the gain from future patients reflecting the expected population size. This paper develops such approaches. Building on previous work, an asymptotic expression is derived for the sample size for single and two-arm clinical trials in the general case of a clinical trial with a primary endpoint with a distribution of one parameter exponential family form that optimizes a utility function that quantifies the cost and gain per patient as a continuous function of this parameter. It is shown that as the size of the population, N, or expected size, N∗ in the case of geometric discounting, becomes large, the optimal trial size is O(N1/2) or O(N∗1/2). The sample size obtained from the asymptotic expression is also compared with the exact optimal sample size in examples with responses with Bernoulli and Poisson distributions, showing that the asymptotic approximations can also be reasonable in relatively small sample sizes. © 2016 The Author. Biometrical Journal published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Optimized Preparation of Levofloxacin-loaded Chitosan Nanoparticles by Ionotropic Gelation

    Science.gov (United States)

    Guan, J.; Cheng, P.; Huang, S. J.; Wu, J. M.; Li, Z. H.; You, X. D.; Hao, L. M.; Guo, Y.; Li, R. X.; Zhang, H.

    The present work investigates the feasibility of fabricating chitosan (CS)-levofloxacin (LOF) nanoparticles by ionotropic gelation technology. An orthogonal experiment was designed to optimize its preparing parameters and multi-index comprehensive weighed score analysis method was used to study the effects of various factors including concentration of CS, concentration of tripolyphosphate (TPP), mass ratio of CS to TPP, and mass ratio of CS to LOF on the properties of nanoparticles. The particles prepared under optimal condition of 2 mg/ml CS concentration, 2 mg/ml TPP concentration, 0.5:1 mass ratio of oil to water and 4:1 mass ratio of CS to TPP had 140 nm diameter, 0.95 span, 6.13% loading capacity (LC) and 24.91% encapsulation efficiency (EE). In vitro release profile showed that LOF released fast initially and then slowly with T90 occurring at 76.5 h. Future studies should focus on antibacterial and biocompatible properties in order to evaluate its potential as sustainable delivery system.

  9. Preparation, optimization and application of affinity absorbent with a polysaccharide YCP as the ligand.

    Science.gov (United States)

    Ding, Ran; Zhou, Yan; Zhang, Xian; Zhu, Rui; Yao, Wen-Bing; Gao, Xiang-Dong

    2014-04-15

    YCP, an α-glucan from the mycelium of marine filamentous fungus Phoma herbarum YS4108, has great antitumor potential via enhancement of host immune through Toll-like receptor (TLR) 2 and TLR4 signaling. In the current study, YCP was coupled to EAH Sepharose 4B agarose beads to prepare the YCP-Sepharose affinity absorbent using 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP) as the activating agent. An orthogonal experiment L9 (3)(4) was applied to optimize the coupling procedure, giving the optimal parameters as follows: molar ratio of CDAP to YCP of 1:2, CDAP-activation time of 5 min, gel volume of 0.1 mL, and gel-incubation time of 72 h, respectively. Scanning electron microscopy analysis indicated successfully preparation of YCP immobilized sepharose beads, while these beads essentially maintained biological properties of free YCP since they can interact with TLR2 and TLR4 specifically at comparable level. Collectively, our findings provide an alternative approach to immobilize carbohydrate-based molecules for studying the carbohydrate-protein interaction.

  10. Time optimization of (90)Sr measurements: Sequential measurement of multiple samples during ingrowth of (90)Y.

    Science.gov (United States)

    Holmgren, Stina; Tovedal, Annika; Björnham, Oscar; Ramebäck, Henrik

    2016-04-01

    The aim of this paper is to contribute to a more rapid determination of a series of samples containing (90)Sr by making the Cherenkov measurement of the daughter nuclide (90)Y more time efficient. There are many instances when an optimization of the measurement method might be favorable, such as; situations requiring rapid results in order to make urgent decisions or, on the other hand, to maximize the throughput of samples in a limited available time span. In order to minimize the total analysis time, a mathematical model was developed which calculates the time of ingrowth as well as individual measurement times for n samples in a series. This work is focused on the measurement of (90)Y during ingrowth, after an initial chemical separation of strontium, in which it is assumed that no other radioactive strontium isotopes are present. By using a fixed minimum detectable activity (MDA) and iterating the measurement time for each consecutive sample the total analysis time will be less, compared to using the same measurement time for all samples. It was found that by optimization, the total analysis time for 10 samples can be decreased greatly, from 21h to 6.5h, when assuming a MDA of 1Bq/L and at a background count rate of approximately 0.8cpm.

  11. Preparation of solid-state samples of a transition metal coordination compound for synchrotron radiation photoemission studies

    CERN Document Server

    Crotti, C; Celestino, T; Fontana, S

    2003-01-01

    The aim of this research was to identify a sample preparation method suitable for the study of transition metal complexes by photoemission spectroscopy with synchrotron radiation as the X-ray source, even in the case where the compound is not evaporable. Solid-phase samples of W(CO) sub 4 (dppe) [dppe=1,2-bis(diphenylphosphino)ethane] were prepared according to different methods and their synchrotron radiation XPS spectra measured. The spectra acquired from samples prepared by spin coating show core level peaks only slightly broader than the spectrum recorded from UHV evaporated samples. Moreover, for these samples the reproducibility of the binding energy values is excellent. The dependence of the spin coating technique on parameters such as solvent and solution concentration, spinning speed and support material was studied. The same preparation method also allowed the acquisition of valence band spectra, the main peaks of which were clearly resolved. The results suggest that use of the spin coating techniqu...

  12. Preparation of Magnetic Hollow Molecularly Imprinted Polymers for Detection of Triazines in Food Samples.

    Science.gov (United States)

    Wang, Aixiang; Lu, Hongzhi; Xu, Shoufang

    2016-06-22

    Novel magnetic hollow molecularly imprinted polymers (M-H-MIPs) were proposed for highly selective recognition and fast enrichment of triazines in food samples. M-H-MIPs were prepared on the basis of multi-step swelling polymerization, followed by in situ growth of magnetic Fe3O4 nanoparticles on the surface of hollow molecularly imprinted polymers (H-MIPs). Transmission electron microscopy and scanning electron microscopy confirmed the successful immobilization of Fe3O4 nanoparticles on the surface of H-MIPs. M-H-MIPs could be separated simply using an external magnet. The binding adsorption results indicated that M-H-MIPs displayed high binding capacity and fast mass transfer property and class selective property for triazines. Langmuir isotherm and pseudo-second-order kinetic models fitted the best adsorption models for M-H-MIPs. M-H-MIPs were used to analyze atrazine, simazine, propazine, and terbuthylazine in corn, wheat, and soybean samples. Satisfactory recoveries were in the range of 80.62-101.69%, and relative standard deviation was lower than 5.2%. Limits of detection from 0.16 to 0.39 μg L(-1) were obtained. When the method was applied to test positive samples that were contaminated with triazines, the results agree well with those obtained from an accredited method. Thus, the M-H-MIP-based dispersive solid-phase extraction method proved to be a convenient and practical platform for detection of triazines in food samples.

  13. Preparation of Biological Samples Containing Metoprolol and Bisoprolol for Applying Methods for Quantitative Analysis

    Directory of Open Access Journals (Sweden)

    Corina Mahu Ştefania

    2015-12-01

    Full Text Available Arterial hypertension is a complex disease with many serious complications, representing a leading cause of mortality. Selective beta-blockers such as metoprolol and bisoprolol are frequently used in the management of hypertension. Numerous analytical methods have been developed for the determination of these substances in biological fluids, such as liquid chromatography coupled with mass spectrometry, gas chromatography coupled with mass spectrometry, high performance liquid chromatography. Due to the complex composition of biological fluids a biological sample pre-treatment before the use of the method for quantitative determination is required in order to remove proteins and potential interferences. The most commonly used methods for processing biological samples containing metoprolol and bisoprolol were identified through a thorough literature search using PubMed, ScienceDirect, and Willey Journals databases. Articles published between years 2005-2015 were reviewed. Protein precipitation, liquid-liquid extraction and solid phase extraction are the main techniques for the extraction of these drugs from plasma, serum, whole blood and urine samples. In addition, numerous other techniques have been developed for the preparation of biological samples, such as dispersive liquid-liquid microextraction, carrier-mediated liquid phase microextraction, hollow fiber-protected liquid phase microextraction, on-line molecularly imprinted solid phase extraction. The analysis of metoprolol and bisoprolol in human plasma, urine and other biological fluids provides important information in clinical and toxicological trials, thus requiring the application of appropriate extraction techniques for the detection of these antihypertensive substances at nanogram and picogram levels.

  14. Determination of bromine, fluorine and iodine in mineral supplements using pyrohydrolysis for sample preparation

    Energy Technology Data Exchange (ETDEWEB)

    Taflik, Ticiane; Antes, Fabiane G.; Paniz, Jose N.G.; Flores, Erico M.M.; Dressler, Valderi L., E-mail: valdres@quimica.ufsm.br [Departamento de Quimica, Universidade Federal de Santa Maria, RS (Brazil); Duarte, Fabio A. [Escola de Quimica e Alimentos, Universidade Federal do Rio Grande, Rio Grande, RS (Brazil); Flores, Eder L.M. [Coordenacao de Engenharia de Alimentos, Universidade Tecnologica Federal do Parana, Medianeira, PR (Brazil)

    2012-03-15

    Pyrohydrolysis was employed for mineral supplements decomposition prior to F, Br and I determination. Fluoride determination was carried out by potentiometry using a fluoride-ion selective electrode, whereas Br and I were determined by inductively coupled plasma mass spectrometry. The main parameters that influence on pyrohydrolysis were investigated. After evaluation, the following conditions were established: reactor temperature of 1000 deg C during 10 min; sample plus accelerator mass ratio of 1 + 5 and carrier gas (air) flow rate of 200 mL min{sup -1} . The accuracy of the proposed method was evaluated by analyte recovery tests and analysis of certified reference materials of phosphate rock and soil. Commercial mineral supplement samples were analyzed. The limits of quantification were 16, 0.3 and 0.07 {mu}g g{sup -1} for F, Br and I, respectively. By using a relatively simple and low cost pyrohydrolysis system up to 5 samples can be processed per hour. The developed sample preparation procedure can be routinely employed for F, Br and I determination in mineral supplements. (author)

  15. Preparative divergent flow IEF without carrier ampholytes for separation of complex biological samples.

    Science.gov (United States)

    Stastna, Miroslava; Slais, Karel

    2010-01-01

    Efficient separation method is a crucial part of the process in which components of highly complex biological sample are identified and characterized. Based on the principles of recently newly established electrophoretic method called divergent flow IEF (DF IEF), we have tested the DF IEF instrument which is able to operate without the use of background carrier ampholytes. We have verified that during separation and focusing of sample consisting of high numbers of proteins (yeast lysate and wheat flour extract), the pH gradient of preparative DF IEF can be created by autofocusing of the sample components themselves without any addition of carrier ampholytes. In DF IEF, the proteins are separated, desalted and concentrated in one step. The fractions of yeast lysate sample, collected at the DF IEF output and subjected to gel IEF, contained the zones of proteins gradually covering the pI values from 3.7 to 8.5. In our experimental arrangement, the highest number of proteins has been found in fractions with pI values around 5.3 as detected by polyacrylamide gel IEF with CBB staining. During DF IEF, the selected protein bands have been concentrated up to 16.8-fold.

  16. Sample preparation for scanning electron microscopy of plant surfaces--horses for courses.

    Science.gov (United States)

    Pathan, A K; Bond, J; Gaskin, R E

    2008-12-01

    Plant tissues must be dehydrated for observation in most electron microscopes. Although a number of sample processing techniques have been developed for preserving plant tissues in their original form and structure, none of them are guaranteed artefact-free. The current paper reviews common scanning electron microscopy techniques and the sample preparation methods employed for visualisation of leaves under specific types of electron microscopes. Common artefacts introduced by specific techniques on different leaf types are discussed. Comparative examples are depicted from our lab using similar techniques; the pros and cons for specific techniques are discussed. New promising techniques and microscopes, which can alleviate some of the problems encountered in conventional methods of leaf sample processing and visualisation, are also discussed. It is concluded that the choice of technique for a specific leaf sample is dictated by the surface features that need to be preserved (such as trichomes, epidermal cells or wax microstructure), the resolution to be achieved, availability of the appropriate processing equipment and the technical capabilities of the available electron microscope.

  17. Average Sample-path Optimality for Continuous-time Markov Decision Processes in Polish Spaces

    Institute of Scientific and Technical Information of China (English)

    Quan-xin ZHU

    2011-01-01

    In this paper we study the average sample-path cost (ASPC) problem for continuous-time Markov decision processes in Polish spaces.To the best of our knowledge,this paper is a first attempt to study the ASPC criterion on continuous-time MDPs with Polish state and action spaces.The corresponding transition rates are allowed to be unbounded,and the cost rates may have neither upper nor lower bounds.Under some mild hypotheses,we prove the existence of e (ε ≥ 0)-ASPC optimal stationary policies based on two different approaches:one is the “optimality equation” approach and the other is the “two optimality inequalities” approach.

  18. Preparation of C₁₈-functionalized magnetic polydopamine microspheres for the enrichment and analysis of alkylphenols in water samples.

    Science.gov (United States)

    Wang, Xianying; Deng, Chunhui

    2016-02-01

    In this work, C18-functionalized magnetic polydopamine microspheres (Fe3O4@PDA@C18) were successfully synthesized and applied to the analysis of alkylphenols in water samples. The magnetic Fe3O4 particles coated with hydrophilic surface were synthesized via a solvothermal reaction and the self-polymerization of dopamine. And then the C18 groups were fabricated by a silylanization method. Benefit from the merits of Fe3O4 particles, polydopamine coating and C18 groups, the Fe3O4@PDA@C18 material possessed several properties of super magnetic responsiviness, good water dispersibility, π-electron system and hydrophobic C18 groups. Thus, the materials had great potential to be developed as the adsorbent for the magnetic solid-phase extraction (MSPE) technique. Here, we selected three kinds of alkylphenols (4-tert-octylphenol, 4-n-nonylphenol, 4-n-octylphenol) to be the target analyst for evaluating the performance of the prepared material. In this study, various extraction parameters were investigated and optimized, such as pH values of water sample solution, amount of adsorbents, adsorption and desorption time, the species of desorption solution. Meanwhile, the method validations were studied, including linearity, limit of detection and method precision. From the results, Fe3O4@PDA@C18 composites were successfully applied as the adsorbents for the extraction of alkylphenols in water samples. The proposed material provided an approach for a simple, rapid magnetic solid-phase extraction for hydrophobic compounds in environmental samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Preparation and analysis of dust samples for medical examinations; Praeparation und Analytik der Staubproben fuer medizinische Untersuchungen

    Energy Technology Data Exchange (ETDEWEB)

    Armbruster, L. [Deutsche Montan Technologie GmbH, Essen (Germany). Gas and Fire Div.

    2004-07-01

    For medical research within this project three respirable dust samples have been prepared and analysed. The original bulk material came from three different stratigraphic horizons, for the preparation a multiplex classifier was used. The respirable samples showed the same size distribution as the samples used in former projects. The quartz content was rather low, but within the normal variability. Pure quartz particles without surface contamination are not present in the three samples. Nickel, lead, cobalt, and arsenic are the most significant trace elements in the samples. (orig.)

  20. Preparing and measuring ultra-small radiocarbon samples with the ARTEMIS AMS facility in Saclay, France

    Energy Technology Data Exchange (ETDEWEB)

    Delque-Kolic, E., E-mail: emmanuelle.delque-kolic@cea.fr [LMC14, CEA Saclay, Batiment 450 Porte 4E, 91191 Gif sur Yvette (France); Comby-Zerbino, C.; Ferkane, S.; Moreau, C.; Dumoulin, J.P.; Caffy, I.; Souprayen, C.; Quiles, A.; Bavay, D.; Hain, S.; Setti, V. [LMC14, CEA Saclay, Batiment 450 Porte 4E, 91191 Gif sur Yvette (France)

    2013-01-15

    The ARTEMIS facility in Saclay France measures, on average, 4500 samples a year for French organizations working in an array of fields, including environmental sciences, archeology and hydrology. In response to an increasing demand for the isolation of specific soil compounds and organic water fractions, we were motivated to evaluate our ability to reduce microgram samples using our standard graphitization lines and to measure the graphite thus obtained with our 3MV NEC Pelletron AMS. Our reduction facility consists of two fully automated graphitization lines. Each line has 12 reduction reactors with a reduction volume of 18 ml for the first line and 12 ml for the second. Under routine conditions, we determined that we could reduce the samples down to 10 {mu}g of carbon, even if the graphitization yield is consequently affected by the lower sample mass. Our results when testing different Fe/C ratios suggest that an amount of 1.5 mg of Fe powder was ideal (instead of lower amounts of catalyst) to prevent the sample from deteriorating too quickly under the Cs+ beam, and to facilitate pressing procedures. Several sets of microsamples produced from HOxI standard, international references and backgrounds were measured. When measuring {sup 14}C-free wood charcoal and HOxI samples we determined that our modern and dead blanks, due to the various preparation steps, were of 1.1 {+-} 0.8 and 0.2 {+-} 0.1 {mu}g, respectively. The results presented here were obtained for IAEA-C1, {sup 14}C-free wood, IAEA-C6, IAEA-C2 and FIRI C.

  1. Preparation and examination of monolithic in-needle extraction (MINE) device for the direct analysis of liquid samples

    Energy Technology Data Exchange (ETDEWEB)

    Pietrzyńska, Monika, E-mail: monikapietrzynska@gmail.com; Voelkel, Adam; Bielicka-Daszkiewicz, Katarzyna

    2013-05-07

    Graphical abstract: -- Highlights: •MINE device for isolation of analytes from water samples. •Nine polymer poly(styrene-divinylbenzene) monoliths prepared in stainless steel needles. •High efficiency of in-needle extraction systems based on monolithic materials. •New possibilities in sample preparation area. -- Abstract: Combination of extraction and chromatographic techniques opens NEW possibilities in sample preparation area. Macroporous poly(styrene-divinylbenzene) (PS-DVB) monoliths were prepared by in situ polymerization in stainless steel needles. The surface of stainless steel needle was modified earlier by the silane coupling agent. Monolithic materials located inside needles were used as the in-needle extraction device. Scanning electron microscope (SEM) images were obtained for nine monoliths. Spectra of prepared materials were also performed with the use of two techniques: Attenuated Total Reflectance (ATR) and Fourier Transform Infrared Spectroscopy (FTIR). The new monolithic in-needle extraction (MINE) devices were used in the preparation of a series of test water samples for chromatographic analysis. The extraction of phenolic compounds from water samples was carried out by pumping liquid samples through the MINE device. Obtained results indicate a high efficiency of in-needle extraction systems based on monolithic materials. Breakthrough volume and the sorption efficiency of prepared monolithic in-needle extraction devices were determined experimentally. The achieved recovery was close to 90%, and determined LOQ values varied between 0.4 and 6 μg.

  2. Optimization of ultrasonic-assisted preparation of dietary fiber from corn pericarp using response surface methodology.

    Science.gov (United States)

    Wang, Anna; Wu, Ligen; Li, Xiulin

    2013-09-01

    Corn pericarp, which is an industrial waste of corn starch production, is an important source of dietary fiber in cereals, with claimed health benefits. However, they used to be discarded or utilized as animal feed. The application of pre-ultrasound treatment is critical for achieving rapid preparation of desired components from plant materials and for preserving structural and molecular properties of these compounds. Ultrasonic-assisted preparation was used to produce dietary fiber from corn pericarp using response surface methodology. The optimal particle size of corn pericarp (mesh size 40), the ratio of liquid to solid (25 mL g⁻¹), ultrasonic power (180 W) and ultrasonic time (80 min) were determined based on response surface methodology analysis. The interaction effects of particle size of corn pericarp and ultrasonic time had a highlysignificant effect on the yield of dietary fiber, and a significant effect was shown by ultrasonic power and ultrasonic time. The maximum yield of dietary fiber was 86.84%, which agreed closely with the predicted value. Using ultrasonic-assisted preparation, it may be possible to enhance the yield of dietary fiber from corn pericarp. © 2013 Society of Chemical Industry.

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

    Science.gov (United States)

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

    2017-09-01

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

  4. Memory-Optimized Software Synthesis from Dataflow Program Graphs with Large Size Data Samples

    Directory of Open Access Journals (Sweden)

    Hyunok Oh

    2003-05-01

    Full Text Available In multimedia and graphics applications, data samples of nonprimitive type require significant amount of buffer memory. This paper addresses the problem of minimizing the buffer memory requirement for such applications in embedded software synthesis from graphical dataflow programs based on the synchronous dataflow (SDF model with the given execution order of nodes. We propose a memory minimization technique that separates global memory buffers from local pointer buffers: the global buffers store live data samples and the local buffers store the pointers to the global buffer entries. The proposed algorithm reduces 67% memory for a JPEG encoder, 40% for an H.263 encoder compared with unshared versions, and 22% compared with the previous sharing algorithm for the H.263 encoder. Through extensive buffer sharing optimization, we believe that automatic software synthesis from dataflow program graphs achieves the comparable code quality with the manually optimized code in terms of memory requirement.

  5. A 96-well screen filter plate for high-throughput biological sample preparation and LC-MS/MS analysis.

    Science.gov (United States)

    Peng, Sean X; Cousineau, Martin; Juzwin, Stephen J; Ritchie, David M

    2006-01-01

    A novel 96-well screen filter plate (patent pending) has been invented to eliminate a time-consuming and labor-intensive step in preparation of in vivo study samples--to remove blood or plasma clots. These clots plug the pipet tips during a manual or automated sample-transfer step causing inaccurate pipetting or total pipetting failure. Traditionally, these blood and plasma clots are removed by picking them out manually one by one from each sample tube before any sample transfer can be made. This has significantly slowed the sample preparation process and has become a bottleneck for automated high-throughput sample preparation using robotic liquid handlers. Our novel screen filter plate was developed to solve this problem. The 96-well screen filter plate consists of 96 stainless steel wire-mesh screen tubes connected to the 96 openings of a top plate so that the screen filter plate can be readily inserted into a 96-well sample storage plate. Upon insertion, the blood and plasma clots are excluded from entering the screen tube while clear sample solutions flow freely into it. In this way, sample transfer can be easily completed by either manual or automated pipetting methods. In this report, three structurally diverse compounds were selected to evaluate and validate the use of the screen filter plate. The plasma samples of these compounds were transferred and processed in the presence and absence of the screen filter plate and then analyzed by LC-MS/MS methods. Our results showed a good agreement between the samples prepared with and without the screen filter plate, demonstrating the utility and efficiency of this novel device for preparation of blood and plasma samples. The device is simple, easy to use, and reusable. It can be employed for sample preparation of other biological fluids that contain floating particulates or aggregates.

  6. Optimal adaptive group sequential design with flexible timing of sample size determination.

    Science.gov (United States)

    Cui, Lu; Zhang, Lanju; Yang, Bo

    2017-04-26

    Flexible sample size designs, including group sequential and sample size re-estimation designs, have been used as alternatives to fixed sample size designs to achieve more robust statistical power and better trial efficiency. In this work, a new representation of sample size re-estimation design suggested by Cui et al. [5,6] is introduced as an adaptive group sequential design with flexible timing of sample size determination. This generalized adaptive group sequential design allows one time sample size determination either before the start of or in the mid-course of a clinical study. The new approach leads to possible design optimization on an expanded space of design parameters. Its equivalence to sample size re-estimation design proposed by Cui et al. provides further insight on re-estimation design and helps to address common confusions and misunderstanding. Issues in designing flexible sample size trial, including design objective, performance evaluation and implementation are touched upon with an example to illustrate. Copyright © 2017. Published by Elsevier Inc.

  7. Microwave processing for sample preparation to evaluate mitochondrial ultrastructural damage in hemorrhagic shock.

    Science.gov (United States)

    Josephsen, Gary D; Josephsen, Kelly A; Beilman, Greg J; Taylor, Jodie H; Muiler, Kristine E

    2005-12-01

    This is a report of the adaptation of microwave processing in the preparation of liver biopsies for transmission electron microscopy (TEM) to examine ultrastructural damage of mitochondria in the setting of metabolic stress. Hemorrhagic shock was induced in pigs via 35% total blood volume bleed and a 90-min period of shock followed by resuscitation. Hepatic biopsies were collected before shock and after resuscitation. Following collection, biopsies were processed for TEM by a rapid method involving microwave irradiation (Giberson, 2001). Samples pre- and postshock of each of two animals were viewed and scored using the mitochondrial ultrastructure scoring system (Crouser et al., 2002), a system used to quantify the severity of ultrastructural damage during shock. Results showed evidence of increased ultrastructural damage in the postshock samples, which scored 4.00 and 3.42, versus their preshock controls, which scored 1.18 and 1.27. The results of this analysis were similar to those obtained in another model of shock (Crouser et al., 2002). However, the amount of time used to process the samples was significantly shortened with methods involving microwave irradiation.

  8. Using Exclusion-Based Sample Preparation (ESP to Reduce Viral Load Assay Cost.

    Directory of Open Access Journals (Sweden)

    Scott M Berry

    Full Text Available Viral load (VL measurements are critical to the proper management of HIV in developing countries. However, access to VL assays is limited by the high cost and complexity of existing assays. While there is a need for low cost VL assays, performance must not be compromised. Thus, new assays must be validated on metrics of limit of detection (LOD, accuracy, and dynamic range. Patient plasma samples from the Joint Clinical Research Centre in Uganda were de-identified and measured using both an existing VL assay (Abbott RealTime HIV-1 and our assay, which combines low cost reagents with a simplified method of RNA isolation termed Exclusion-Based Sample Preparation (ESP.71 patient samples with VLs ranging from 3,000,000 copies/mL were used to compare the two methods. We demonstrated equivalent LOD (~50 copies/mL and high accuracy (average difference between methods of 0.08 log, R2 = 0.97. Using expenditures from this trial, we estimate that the cost of the reagents and consumables for this assay to be approximately $5 USD. As cost is a significant barrier to implementation of VL testing, we anticipate that our assay will enhance access to this critical monitoring test in developing countries.

  9. Using Exclusion-Based Sample Preparation (ESP) to Reduce Viral Load Assay Cost.

    Science.gov (United States)

    Berry, Scott M; Pezzi, Hannah M; Williams, Eram D; Loeb, Jennifer M; Guckenberger, David J; Lavanway, Alex J; Puchalski, Alice A; Kityo, Cissy M; Mugyenyi, Peter N; Graziano, Franklin M; Beebe, David J

    2015-01-01

    Viral load (VL) measurements are critical to the proper management of HIV in developing countries. However, access to VL assays is limited by the high cost and complexity of existing assays. While there is a need for low cost VL assays, performance must not be compromised. Thus, new assays must be validated on metrics of limit of detection (LOD), accuracy, and dynamic range. Patient plasma samples from the Joint Clinical Research Centre in Uganda were de-identified and measured using both an existing VL assay (Abbott RealTime HIV-1) and our assay, which combines low cost reagents with a simplified method of RNA isolation termed Exclusion-Based Sample Preparation (ESP).71 patient samples with VLs ranging from 3,000,000 copies/mL were used to compare the two methods. We demonstrated equivalent LOD (~50 copies/mL) and high accuracy (average difference between methods of 0.08 log, R2 = 0.97). Using expenditures from this trial, we estimate that the cost of the reagents and consumables for this assay to be approximately $5 USD. As cost is a significant barrier to implementation of VL testing, we anticipate that our assay will enhance access to this critical monitoring test in developing countries.

  10. Modular approach to customise sample preparation procedures for viral metagenomics: a reproducible protocol for virome analysis.

    Science.gov (United States)

    Conceição-Neto, Nádia; Zeller, Mark; Lefrère, Hanne; De Bruyn, Pieter; Beller, Leen; Deboutte, Ward; Yinda, Claude Kwe; Lavigne, Rob; Maes, Piet; Van Ranst, Marc; Heylen, Elisabeth; Matthijnssens, Jelle

    2015-11-12

    A major limitation for better understanding the role of the human gut virome in health and disease is the lack of validated methods that allow high throughput virome analysis. To overcome this, we evaluated the quantitative effect of homogenisation, centrifugation, filtration, chloroform treatment and random amplification on a mock-virome (containing nine highly diverse viruses) and a bacterial mock-community (containing four faecal bacterial species) using quantitative PCR and next-generation sequencing. This resulted in an optimised protocol that was able to recover all viruses present in the mock-virome and strongly alters the ratio of viral versus bacterial and 16S rRNA genetic material in favour of viruses (from 43.2% to 96.7% viral reads and from 47.6% to 0.19% bacterial reads). Furthermore, our study indicated that most of the currently used virome protocols, using small filter pores and/or stringent centrifugation conditions may have largely overlooked large viruses present in viromes. We propose NetoVIR (Novel enrichment technique of VIRomes), which allows for a fast, reproducible and high throughput sample preparation for viral metagenomics studies, introducing minimal bias. This procedure is optimised mainly for faecal samples, but with appropriate concentration steps can also be used for other sample types with lower initial viral loads.

  11. Microwave absorption properties of polyaniline-Fe3O4/ZnO-polyester nanocomposite: Preparation and optimization

    Science.gov (United States)

    Dorraji, M. S. Seyed; Rasoulifard, M. H.; Khodabandeloo, M. H.; Rastgouy-Houjaghan, M.; Zarajabad, H. Karimi

    2016-03-01

    New nanocomposites have been successfully prepared based on polyester resin, including various metal oxides (ZnO nanorod bundles, Fe3O4 nanoparticles, and nano Fe3O4/ZnO) and Polyaniline (PANI) synthesized with different dopants. The microwave absorption properties of nanocomposites were investigated in X-band range. The Taguchi experimental design was used to study the effects of the type of metal oxide and that of PANI (doped with various acids) and the weight percent of metal oxide in PANI and that of filler (metal oxide and PANI) in polyester matrix on the microwave absorption properties with the absorber thickness of only 2 mm. The weight percent of metal oxide in PANI was found to be the most significant parameter, accounting for 45.611% of the total contribution of the four selected parameters. Fe3O4/ZnO as inorganic oxide, PTSA as dopant of PANI, 25 wt.% for inorganic oxide in PANI, and filler in the polyester matrix were selected as optimum conditions by Taguchi method. The sample prepared in optimal conditions had reflection loss of less than -10 dB (absorption >90%) and covering a frequency range of 8.4-11.6 GHz.

  12. SU-E-T-21: A Novel Sampling Algorithm to Reduce Intensity-Modulated Radiation Therapy (IMRT) Optimization Time

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, P; Xie, Y; Chen, Y [Washington University in Saint Louis, Saint Louis, Missouri (United States); Deasy, J [Memorial Sloan Kettering Cancer Center, NY, NY (United States)

    2014-06-01

    Purpose: The IMRT optimization problem requires substantial computer time to find optimal dose distributions because of the large number of variables and constraints. Voxel sampling reduces the number of constraints and accelerates the optimization process, but usually deteriorates the quality of the dose distributions to the organs. We propose a novel sampling algorithm that accelerates the IMRT optimization process without significantly deteriorating the quality of the dose distribution. Methods: We included all boundary voxels, as well as a sampled fraction of interior voxels of organs in the optimization. We selected a fraction of interior voxels using a clustering algorithm, that creates clusters of voxels that have similar influence matrix signatures. A few voxels are selected from each cluster based on the pre-set sampling rate. Results: We ran sampling and no-sampling IMRT plans for de-identified head and neck treatment plans. Testing with the different sampling rates, we found that including 10% of inner voxels produced the good dose distributions. For this optimal sampling rate, the algorithm accelerated IMRT optimization by a factor of 2–3 times with a negligible loss of accuracy that was, on average, 0.3% for common dosimetric planning criteria. Conclusion: We demonstrated that a sampling could be developed that reduces optimization time by more than a factor of 2, without significantly degrading the dose quality.

  13. Preparation and characterization of magnetic molecularly imprinted polymers for the extraction of hexamethylenetetramine in milk samples.

    Science.gov (United States)

    Xu, Xing; Duhoranimana, Emmanuel; Zhang, Xiaoming

    2017-01-15

    Magnetic molecularly imprinted polymers (M-MIPs) were synthesized as the sorbents for extracting hexamethylenetetramine (HMT) from milk samples. Molecular simulations were used to calculate the interaction energies of the template monomers. The physical properties of M-MIPs were characterized. The adsorption isotherms and kinetics were investigated. Gas chromatography coupled with tandem mass spectrometry (GC-MS/MS) was applied to determine the amount of HMT residue in milk samples. In the optimized method, a linear calibration curve was obtained using a matrix-matched standard in the range of 1.0-50.0μgL(-1). The limit of detection (LOD) and limit of quantification (LOQ) was 0.3μgkg(-1) and 1.0μgkg(-1), respectively. The relative standard deviation (RSD) of the intra-day assay ranged from 2.6% to 5.2%, while that of the inter-day assay ranged from 3.6% to 11.5%. The recovery of HMT in milk samples ranged from 88.7% to 111.4%.

  14. Effects of sample preparation on the optical properties of breast tissue

    Science.gov (United States)

    Marks, Fay A.

    1996-04-01

    The optical properties of biological tissue should be determined in vivo whenever possible. However, for those instances when in vivo studies are impractical, too expensive or inappropriate, and when blood flow is not an issue, the ability to perform in vitro studies then becomes invaluable. Optical absorption spectroscopy shows that it may be possible to obtain meaningful information about the optical properties of human breast tissue from in vitro samples if strict preparation and measuring protocols are used. That a strict protocol for storing and handling tissue is critical can be seen from our observations of changes in the optical absorption spectra that occur in response to formalin fixation, the passage of time, application of stains and dyes, and storage in growth medium of the excised tissue. In vivo optical absorption spectroscopy measurements have been made on human breast cancer xenografts and compared with in vitro measurements on breast biopsies prepared according to precise collection and treatment protocols. There is a 'window of opportunity' before time dependent changes in the UV optical absorption spectra of the excised tissue specimens occur. This time window of opportunity widens at longer wavelengths with the least changes occurring in the optical spectra in the NIR.

  15. Lights Will Guide You : Sample Preparation and Applications for Integrated Laser and Electron Microscopy

    Science.gov (United States)

    Karreman, M. A.

    2013-03-01

    Correlative microscopy is the combined use of two different forms of microscopy in the study of a specimen, allowing for the exploitation of the advantages of both imaging tools. The integrated Laser and Electron Microscope (iLEM), developed at Utrecht University, combines a fluorescence microscope (FM) and a transmission electron microscope (TEM) in a single set-up. The region of interest in the specimen is labeled or tagged with a fluorescent probe and can easily be identified within a large field of view with the FM. Next, this same area is retraced in the TEM and can be studied at high resolution. The iLEM demands samples that can be imaged with both FM and TEM. Biological specimen, typically composed of light elements, generate low image contrast in the TEM. Therefore, these samples are often ‘contrasted’ with heavy metal stains. FM, on the other hand, images fluorescent samples. Sample preparation for correlative microscopy, and iLEM in particular, is complicated by the fact that the heavy metals stains employed for TEM quench the fluorescent signal of the probe that is imaged with FM. The first part of this thesis outlines preparation procedures for biological material yielding specimen that can be imaged with the iLEM. Here, approaches for the contrasting of thin sections of cells and tissue are introduced that do not affect the fluorescence signal of the probe that marks the region of interest. Furthermore, two novel procedures, VIS2FIXH and VIS2FIX­FS are described that allow for the chemical fixation of thin sections of cryo-immobilized material. These procedures greatly expedite the sample preparation process, and open up novel possibilities for the immuno-labeling of difficult antigens, eg. proteins and lipids that are challenging to preserve. The second part of this thesis describes applications of iLEM in research in the field of life and material science. The iLEM was employed in the study of UVC induced apoptosis (programmed cell death) of

  16. Sample Preparation for Headspace GC Analysis of Residual Solvents in Hyaluronic Acid Derivative Fiber

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hoon Joo; Kim, Dong Min; Yang, Jeong Soo [LG life Sciences, Ltd./R and D Park, Daejeon (Korea, Republic of); Kim, Chan Wha [Korea University, Seoul (Korea, Republic of)

    2006-02-15

    The aim of this study is to develop efficient sample preparation method for HS-GC analysis of residual solvents in HA derivative fiber. Compared to direct extraction of residual solvents from HA derivative fiber, the extraction through the hydrolysis of HA derivative fiber by HAse gave more complete and higher reproducible quantification of residual solvent. To validate HS-GC analysis method of residual solvents, specificity, limits of detection and quantification, linearity, accuracy and precision are investigated in the study. HA derivative fiber was hydrolyzed using HAse for headspace gas chromatographic analysis of residual solvents of ethanol, acetone and isopropanol in HA derivative fiber. This study showed that the developed method had specificity, linearity, accuracy and precision. In addition, it demonstrated that HS-GC coupled with matrix-breaking method such as hydrolysis was available for the determination of residual solvents in a matrix like HA derivative fiber.

  17. Applied Study on Magnetic Nanometer Beads in Preparation of Genechip Samples

    Institute of Scientific and Technical Information of China (English)

    陈慧; 高华方; 谢欣; 马雪梅; 杨渝珍

    2004-01-01

    Summary: A protocol for enrichment and adsorption of karyocyte from whole blood by using magnetic nanometer beads as solid-phase absorbents was presented. The PCR amplification could be accomplished by using the nanobeads with karyocyte as template directly and the PCR products were applied on an oligonucleotide array to do gene typing. The HLA-A PCR amplification system and a small HLA-A oligonucleotide microarray were applied as the platform and an experiment protocol of separating karyocyte from whole blood using the magnetic nanometer beads (Fe2O3) were set up.The experimental conditions were also discussed. It showed that pH level of PBS eluent, Taq enzyme quantity and fragment length of products could influent the amplification results, and the magnetic nano-beads could succeed in sample preparation in microarray to provide a promising way in automatic detection and lab-on-a-chip.

  18. Agarose- and alginate-based biopolymers for sample preparation: Excellent green extraction tools for this century.

    Science.gov (United States)

    Sanagi, Mohd Marsin; Loh, Saw Hong; Wan Ibrahim, Wan Nazihah; Pourmand, Neda; Salisu, Ahmed; Wan Ibrahim, Wan Aini; Ali, Imran

    2016-03-01

    Recently, there has been considerable interest in the use of miniaturized sample preparation techniques before the chromatographic monitoring of the analytes in unknown complex compositions. The use of biopolymer-based sorbents in solid-phase microextraction techniques has achieved a good reputation. A great variety of polysaccharides can be extracted from marine plants or microorganisms. Seaweeds are the major sources of polysaccharides such as alginate, agar, agarose, as well as carrageenans. Agarose and alginate (green biopolymers) have been manipulated for different microextraction approaches. The present review is focused on the classification of biopolymer and their applications in multidisciplinary research. Besides, efforts have been made to discuss the state-of-the-art of the new microextraction techniques that utilize commercial biopolymer interfaces such as agarose in liquid-phase microextraction and solid-phase microextraction.

  19. METHODOLOGICAL ASPECTS OF MOLASSES SAMPLE PREPARATION IN SULFUR DIOXIDE CONTENT DETERMINING

    Directory of Open Access Journals (Sweden)

    M. I. Egorova

    2015-01-01

    Full Text Available Summary. Molasses is characterized as sugar production by-product from primary or secondary sacchariferous raw materials. The features of the appearance, the chemical composition, molasses and exit directions of its use, depending on the type of production, in which it is formed. The value of molasses is demonstrated according to its total composition as well as its use directions. Statistics on beet molasses amounts in Russia is presented. Described consumer market molasses in Russia and abroad with its exports. Shown regulations contain requirements for the quality and safety of molasses, including sulfur dioxide. The data on sulfur allergenic properties are presented. Showing source of the sulfur dioxide in the residual molasses number of processing aids and the impact of its level in the value of raw molasses for use in biotechnological processes and fodder production. The necessity to develop methodology for determining the sulfur dioxide content in the molasses to control its security. The iodometric method, which is used in practice for determination of sulphur dioxide in foods are characterized. Differences molasses and sugar as objects of iodometric determination of sulfur dioxide, which leads to the inability to ascertain the equivalence point. The variants eliminate interfering background of dark-colored foods common in analytical chemistry. Advantages and disadvantages of the background masking and stripping the determination of sulfur dioxide in the darkcolored products. It was characterized by clarifying sugar solutions in optical control methods. The hypothesis about preferability of its use in sample molasses preparation for equivalence point fixation in iodometric titration is suggested. The tasks of experimental research for the development of sample preparation algorithm molasses in determining the content of sulphurous acid.

  20. ALGORITHM OF PREPARATION OF THE TRAINING SAMPLE USING 3D-FACE MODELING

    Directory of Open Access Journals (Sweden)

    D. I. Samal

    2016-01-01

    Full Text Available The algorithm of preparation and sampling for training of the multiclass qualifier of support vector machines (SVM is provided. The described approach based on the modeling of possible changes of the face features of recognized person. Additional features like perspectives of shooting, conditions of lighting, tilt angles were introduced to get improved identification results. These synthetic generated changes have some impact on the classifier learning expanding the range of possible variations of the initial image. The classifier learned with such extended example is ready to recognize unknown objects better. The age, emotional looks, turns of the head, various conditions of lighting, noise, and also some combinations of the listed parameters are chosen as the key considered parameters for modeling. The third-party software ‘FaceGen’ allowing to model up to 150 parameters and available in a demoversion for free downloading is used for 3D-modeling.The SVM classifier was chosen to test the impact of the introduced modifications of training sample. The preparation and preliminary processing of images contains the following constituents like detection and localization of area of the person on the image, assessment of an angle of rotation and an inclination, extension of the range of brightness of pixels and an equalization of the histogram to smooth the brightness and contrast characteristics of the processed images, scaling of the localized and processed area of the person, creation of a vector of features of the scaled and processed image of the person by a Principal component analysis (algorithm NIPALS, training of the multiclass SVM-classifier.The provided algorithm of expansion of the training selection is oriented to be used in practice and allows to expand using 3D-models the processed range of 2D – photographs of persons that positively affects results of identification in system of face recognition. This approach allows to compensate

  1. preparation of microgram samples on iron wool for radiocarbon analysis via accelerator mass spectrometry: A closed-system approach

    Science.gov (United States)

    Verkouteren, R. Michael; Klouda, George A.; Currie, Lloyd A.; Donahue, Douglas J.; Jull, A. J. Timothy; Linick, T. W.

    1987-11-01

    A technique has been developed at NBS for the production of high quality targets for radiocarbon analysis by accelerator mass spectrometry (AMS). Our process optimizes chemical yields, ion currents and characterizes the chemical blank. The approach encompasses sample combustion to CO 2, catalytic reduction of CO 2 by Zn to CO, reduction to graphitic carbon on high-purity iron wool and in situ formation of a homogeneous iron-carbon bead; all steps are performed in a closed system. The total measurement system blank and variability are considered in the light of contributions from combustion, iron wool, reduction, bead formation and instrument blank. Additionally, use of this approach provides an increase in throughput, i.e. the effective management of large numbers of samples. Chemical yields for 50-800 μg C samples deposited on 15 mg iron wool were greater than 90%. Integrated 12C - ion currents observed were significant, being 4-64% of those observed in pure graphite. These currents are about an order of magnitude greater than those expected from dilution of graphite with an inert substrate. Isotopic accuracy, precision and blank were assessed by measuring the {14C }/{13C } ratios of a series of targets prepared from dead carbon and oxalic acid (SRM 4990C). Each target was typically measured for one hour; bead consumption was estimated at 5% to 10%. System blank subsequent to combustion was equivalent to (2.2 ± 0.5) μg modern carbon (chemistry + instrument); combustion blank currently stands at (0.4 ± 0.1) (SE, n = 6) μg C.

  2. A two-stage method to determine optimal product sampling considering dynamic potential market.

    Science.gov (United States)

    Hu, Zhineng; Lu, Wei; Han, Bing

    2015-01-01

    This paper develops an optimization model for the diffusion effects of free samples under dynamic changes in potential market based on the characteristics of independent product and presents a two-stage method to figure out the sampling level. The impact analysis of the key factors on the sampling level shows that the increase of the external coefficient or internal coefficient has a negative influence on the sampling level. And the changing rate of the potential market has no significant influence on the sampling level whereas the repeat purchase has a positive one. Using logistic analysis and regression analysis, the global sensitivity analysis gives a whole analysis of the interaction of all parameters, which provides a two-stage method to estimate the impact of the relevant parameters in the case of inaccuracy of the parameters and to be able to construct a 95% confidence interval for the predicted sampling level. Finally, the paper provides the operational steps to improve the accuracy of the parameter estimation and an innovational way to estimate the sampling level.

  3. Advanced sample preparation for the molecular quantification of Staphylococcus aureus in artificially and naturally contaminated milk.

    Science.gov (United States)

    Aprodu, Iuliana; Walcher, Georg; Schelin, Jenny; Hein, Ingeborg; Norling, Börje; Rådström, Peter; Nicolau, Anca; Wagner, Martin

    2011-03-01

    Sample treatment is an essential element when using real-time PCR for quantification of pathogens directly on food samples. This study comparatively evaluated three different principles of sample treatment, i.e. immunomagnetic separation based on phage-derived cell wall binding molecules, matrix solubilization and flotation, in order to establish their suitability for quantifying low numbers of Staphylococcus aureus in milk. All three procedures succeeded to remove S. aureus from the milk matrix, either raw or pasteurized, and, as a result of the concentration of the target cells, minimized the effect of milk associated PCR inhibitors. Sample preparation based on immunomagnetic separation albeit of being user friendly, specific and rapid, failed to allow quantification of low and medium numbers (<10(4)CFU) of S. aureus. In a mastitic milk model cell wall binding domain (CBD)-based target cell extraction revealed results most closely matching those derived from culture-based quantification. Both matrix lysis and flotation allowed quantification of S. aureus at a level of 1-10 cells per ml. Both methods resulted in higher numbers of bacterial cell equivalents (bce) than plating could reveal. Since both methods harvest cells that have been subjected to either mechanical and chemical stresses before quantification, we concluded that the higher bce numbers resulted from a disaggregation of S. aureus clusters initially present in the inoculum. Conclusively, since likely each S. aureus cell of a toxigenic strain contributes to enterotoxin production, molecular quantification could provide an even more realistic impact assessment in outbreak investigations than plating does.

  4. Second generation laser-heated microfurnace for the preparation of microgram-sized graphite samples

    Science.gov (United States)

    Yang, Bin; Smith, A. M.; Long, S.

    2015-10-01

    We present construction details and test results for two second-generation laser-heated microfurnaces (LHF-II) used to prepare graphite samples for Accelerator Mass Spectrometry (AMS) at ANSTO. Based on systematic studies aimed at optimising the performance of our prototype laser-heated microfurnace (LHF-I) (Smith et al., 2007 [1]; Smith et al., 2010 [2,3]; Yang et al., 2014 [4]), we have designed the LHF-II to have the following features: (i) it has a small reactor volume of 0.25 mL allowing us to completely graphitise carbon dioxide samples containing as little as 2 μg of C, (ii) it can operate over a large pressure range (0-3 bar) and so has the capacity to graphitise CO2 samples containing up to 100 μg of C; (iii) it is compact, with three valves integrated into the microfurnace body, (iv) it is compatible with our new miniaturised conventional graphitisation furnaces (MCF), also designed for small samples, and shares a common vacuum system. Early tests have shown that the extraneous carbon added during graphitisation in each LHF-II is of the order of 0.05 μg, assuming 100 pMC activity, similar to that of the prototype unit. We use a 'budget' fibre packaged array for the diode laser with custom built focusing optics. The use of a new infrared (IR) thermometer with a short focal length has allowed us to decrease the height of the light-proof safety enclosure. These innovations have produced a cheaper and more compact device. As with the LHF-I, feedback control of the catalyst temperature and logging of the reaction parameters is managed by a LabVIEW interface.

  5. Second generation laser-heated microfurnace for the preparation of microgram-sized graphite samples

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bin; Smith, A.M.; Long, S.

    2015-10-15

    We present construction details and test results for two second-generation laser-heated microfurnaces (LHF-II) used to prepare graphite samples for Accelerator Mass Spectrometry (AMS) at ANSTO. Based on systematic studies aimed at optimising the performance of our prototype laser-heated microfurnace (LHF-I) (Smith et al., 2007 [1]; Smith et al., 2010 [2,3]; Yang et al., 2014 [4]), we have designed the LHF-II to have the following features: (i) it has a small reactor volume of 0.25 mL allowing us to completely graphitise carbon dioxide samples containing as little as 2 μg of C, (ii) it can operate over a large pressure range (0–3 bar) and so has the capacity to graphitise CO{sub 2} samples containing up to 100 μg of C; (iii) it is compact, with three valves integrated into the microfurnace body, (iv) it is compatible with our new miniaturised conventional graphitisation furnaces (MCF), also designed for small samples, and shares a common vacuum system. Early tests have shown that the extraneous carbon added during graphitisation in each LHF-II is of the order of 0.05 μg, assuming 100 pMC activity, similar to that of the prototype unit. We use a ‘budget’ fibre packaged array for the diode laser with custom built focusing optics. The use of a new infrared (IR) thermometer with a short focal length has allowed us to decrease the height of the light-proof safety enclosure. These innovations have produced a cheaper and more compact device. As with the LHF-I, feedback control of the catalyst temperature and logging of the reaction parameters is managed by a LabVIEW interface.

  6. Comparison of sample preparation methods for reliable plutonium and neptunium urinalysis using automatic extraction chromatography.

    Science.gov (United States)

    Qiao, Jixin; Xu, Yihong; Hou, Xiaolin; Miró, Manuel

    2014-10-01

    This paper describes improvement and comparison of analytical methods for simultaneous determination of trace-level plutonium and neptunium in urine samples by inductively coupled plasma mass spectrometry (ICP-MS). Four sample pre-concentration techniques, including calcium phosphate, iron hydroxide and manganese dioxide co-precipitation and evaporation were compared and the applicability of different techniques was discussed in order to evaluate and establish the optimal method for in vivo radioassay program. The analytical results indicate that the various sample pre-concentration approaches afford dissimilar method performances and care should be taken for specific experimental parameters for improving chemical yields. The best analytical performances in terms of turnaround time (6h) and chemical yields for plutonium (88.7 ± 11.6%) and neptunium (94.2 ± 2.0%) were achieved by manganese dioxide co-precipitation. The need of drying ashing (≥ 7h) for calcium phosphate co-precipitation and long-term aging (5d) for iron hydroxide co-precipitation, respectively, rendered time-consuming analytical protocols. Despite the fact that evaporation is also somewhat time-consuming (1.5d), it endows urinalysis methods with better reliability and repeatability compared with co-precipitation techniques. In view of the applicability of different pre-concentration techniques proposed previously in the literature, the main challenge behind relevant method development is pointed to be the release of plutonium and neptunium associated with organic compounds in real urine assays. In this work, different protocols for decomposing organic matter in urine were investigated, of which potassium persulfate (K2S2O8) treatment provided the highest chemical yield of neptunium in the iron hydroxide co-precipitation step, yet, the occurrence of sulfur compounds in the processed sample deteriorated the analytical performance of the ensuing extraction chromatographic separation with chemical

  7. Optimal conditions for the preparation of superhydrophobic surfaces on al substrates using a simple etching approach

    Science.gov (United States)

    Ruan, Min; Li, Wen; Wang, Baoshan; Luo, Qiang; Ma, Fumin; Yu, Zhanlong

    2012-07-01

    Many methods have been proposed to develop the fabrication techniques for superhydrophobic surfaces. However, such techniques are still at their infant stage and suffer many shortcomings. In this paper, the superhydrophobic surfaces on an Al substrate were prepared by a simple etching method. Effects of etching time, modifiers, and modification concentration and time were investigated, and optimal conditions for the best superhydrophobicity were studied. It was demonstrated that for etching the aluminum plate in Beck's dislocation, if the etching time was 15 s, modifier was Lauric acid-ethanol solution, and modification concentration and time was 5% and 1.5 h, respectively, the surface exhibited a water contact angle as high as 167.5° and a contact angle hysteresis as low as 2.3°.

  8. Novel Starch-PVA Polymer for Microparticle Preparation and Optimization Using Factorial Design Study.

    Science.gov (United States)

    Chattopadhyay, Helen; De, Amit Kumar; Datta, Sriparna

    2015-01-01

    The aim of our present work was to optimize the ratio of a very novel polymer, starch-polyvinyl alcohol (PVA), for controlled delivery of Ornidazole. Polymer-coated drug microparticles were prepared by emulsion method. Microscopic study, scanning electron microscopic study, and atomic force microscopic study revealed that the microparticles were within 10 micrometers of size with smooth spherical shape. The Fourier transform infrared spectroscopy showed absence of drug polymer interaction. A statistical 3(2) full factorial design was used to study the effect of different concentration of starch and PVA on the drug release profile. The three-dimensional plots gave us an idea about the contribution of each factor on the release kinetics. Hence this novel polymer of starch and polyvinyl alcohol can be utilized for control release of the drug from a targeted delivery device.

  9. Amphoteric Starch in Simultaneous Process Preparation with Box-Behnken Design for Optimal Conditions

    Directory of Open Access Journals (Sweden)

    Sopa Cansee

    2008-01-01

    Full Text Available Cassava starch was chemically modified to produce an amphoteric starch. The amphoteric starch was prepared in a simultaneous process which was evaluated in relation to four factors: temperature (45-55 °C, 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC, 4-12% and sodium tripolyphosphate (STP, 2-8% concentrations, and reaction time (2-6 h. The extent of amphoteric starch produced was determined by the degree of substitution (DS of the nitrogen content and percentage of phosphorus content. In addition, a quantitative response of yield and whiteness as well as pasting characteristics were tested. Response surface analysis showed that the DS (0.01-0.05 increased with increasing temperature, CHPTAC and reaction time. The phosphorus content (0.09-0.34% followed a parabolic shape with all of the factors. Consequently, the response surface methodology appears to be a powerful technique to determine the optimal conditions for the production of amphoteric starches.

  10. An optimization based sampling approach for multiple metrics uncertainty analysis using generalized likelihood uncertainty estimation

    Science.gov (United States)

    Zhou, Rurui; Li, Yu; Lu, Di; Liu, Haixing; Zhou, Huicheng

    2016-09-01

    This paper investigates the use of an epsilon-dominance non-dominated sorted genetic algorithm II (ɛ-NSGAII) as a sampling approach with an aim to improving sampling efficiency for multiple metrics uncertainty analysis using Generalized Likelihood Uncertainty Estimation (GLUE). The effectiveness of ɛ-NSGAII based sampling is demonstrated compared with Latin hypercube sampling (LHS) through analyzing sampling efficiency, multiple metrics performance, parameter uncertainty and flood forecasting uncertainty with a case study of flood forecasting uncertainty evaluation based on Xinanjiang model (XAJ) for Qing River reservoir, China. Results obtained demonstrate the following advantages of the ɛ-NSGAII based sampling approach in comparison to LHS: (1) The former performs more effective and efficient than LHS, for example the simulation time required to generate 1000 behavioral parameter sets is shorter by 9 times; (2) The Pareto tradeoffs between metrics are demonstrated clearly with the solutions from ɛ-NSGAII based sampling, also their Pareto optimal values are better than those of LHS, which means better forecasting accuracy of ɛ-NSGAII parameter sets; (3) The parameter posterior distributions from ɛ-NSGAII based sampling are concentrated in the appropriate ranges rather than uniform, which accords with their physical significance, also parameter uncertainties are reduced significantly; (4) The forecasted floods are close to the observations as evaluated by three measures: the normalized total flow outside the uncertainty intervals (FOUI), average relative band-width (RB) and average deviation amplitude (D). The flood forecasting uncertainty is also reduced a lot with ɛ-NSGAII based sampling. This study provides a new sampling approach to improve multiple metrics uncertainty analysis under the framework of GLUE, and could be used to reveal the underlying mechanisms of parameter sets under multiple conflicting metrics in the uncertainty analysis process.

  11. Racing Sampling Based Microimmune Optimization Approach Solving Constrained Expected Value Programming

    Directory of Open Access Journals (Sweden)

    Kai Yang

    2016-01-01

    Full Text Available This work investigates a bioinspired microimmune optimization algorithm to solve a general kind of single-objective nonlinear constrained expected value programming without any prior distribution. In the study of algorithm, two lower bound sample estimates of random variables are theoretically developed to estimate the empirical values of individuals. Two adaptive racing sampling schemes are designed to identify those competitive individuals in a given population, by which high-quality individuals can obtain large sampling size. An immune evolutionary mechanism, along with a local search approach, is constructed to evolve the current population. The comparative experiments have showed that the proposed algorithm can effectively solve higher-dimensional benchmark problems and is of potential for further applications.

  12. Optimization of a sample processing protocol for recovery of Bacillus anthracis spores from soil

    Science.gov (United States)

    Silvestri, Erin E.; Feldhake, David; Griffin, Dale; Lisle, John T.; Nichols, Tonya L.; Shah, Sanjiv; Pemberton, A; Schaefer III, Frank W

    2016-01-01

    Following a release of Bacillus anthracis spores into the environment, there is a potential for lasting environmental contamination in soils. There is a need for detection protocols for B. anthracis in environmental matrices. However, identification of B. anthracis within a soil is a difficult task. Processing soil samples helps to remove debris, chemical components, and biological impurities that can interfere with microbiological detection. This study aimed to optimize a previously used indirect processing protocol, which included a series of washing and centrifugation steps. Optimization of the protocol included: identifying an ideal extraction diluent, variation in the number of wash steps, variation in the initial centrifugation speed, sonication and shaking mechanisms. The optimized protocol was demonstrated at two laboratories in order to evaluate the recovery of spores from loamy and sandy soils. The new protocol demonstrated an improved limit of detection for loamy and sandy soils over the non-optimized protocol with an approximate matrix limit of detection at 14 spores/g of soil. There were no significant differences overall between the two laboratories for either soil type, suggesting that the processing protocol will be robust enough to use at multiple laboratories while achieving comparable recoveries.

  13. Optimization of a sample processing protocol for recovery of Bacillus anthracis spores from soil.

    Science.gov (United States)

    Silvestri, Erin E; Feldhake, David; Griffin, Dale; Lisle, John; Nichols, Tonya L; Shah, Sanjiv R; Pemberton, Adin; Schaefer, Frank W

    2016-11-01

    Following a release of Bacillus anthracis spores into the environment, there is a potential for lasting environmental contamination in soils. There is a need for detection protocols for B. anthracis in environmental matrices. However, identification of B. anthracis within a soil is a difficult task. Processing soil samples helps to remove debris, chemical components, and biological impurities that can interfere with microbiological detection. This study aimed to optimize a previously used indirect processing protocol, which included a series of washing and centrifugation steps. Optimization of the protocol included: identifying an ideal extraction diluent, variation in the number of wash steps, variation in the initial centrifugation speed, sonication and shaking mechanisms. The optimized protocol was demonstrated at two laboratories in order to evaluate the recovery of spores from loamy and sandy soils. The new protocol demonstrated an improved limit of detection for loamy and sandy soils over the non-optimized protocol with an approximate matrix limit of detection at 14spores/g of soil. There were no significant differences overall between the two laboratories for either soil type, suggesting that the processing protocol will be robust enough to use at multiple laboratories while achieving comparable recoveries. Copyright © 2016. Published by Elsevier B.V.

  14. Dynamics of hepatitis C under optimal therapy and sampling based analysis

    Science.gov (United States)

    Pachpute, Gaurav; Chakrabarty, Siddhartha P.

    2013-08-01

    We examine two models for hepatitis C viral (HCV) dynamics, one for monotherapy with interferon (IFN) and the other for combination therapy with IFN and ribavirin. Optimal therapy for both the models is determined using the steepest gradient method, by defining an objective functional which minimizes infected hepatocyte levels, virion population and side-effects of the drug(s). The optimal therapies for both the models show an initial period of high efficacy, followed by a gradual decline. The period of high efficacy coincides with a significant decrease in the viral load, whereas the efficacy drops after hepatocyte levels are restored. We use the Latin hypercube sampling technique to randomly generate a large number of patient scenarios and study the dynamics of each set under the optimal therapy already determined. Results show an increase in the percentage of responders (indicated by drop in viral load below detection levels) in case of combination therapy (72%) as compared to monotherapy (57%). Statistical tests performed to study correlations between sample parameters and time required for the viral load to fall below detection level, show a strong monotonic correlation with the death rate of infected hepatocytes, identifying it to be an important factor in deciding individual drug regimens.

  15. Optimized production of Serratia marcescens B742 mutants for preparing chitin from shrimp shells powders.

    Science.gov (United States)

    Zhang, Hongcai; Fang, Jiyang; Deng, Yun; Zhao, Yanyun

    2014-08-01

    To improve the deproteinization (DP) efficacy of shrimp shell powders (SSP) for preparing chitin, Serratia marcescens B742 mutants were prepared using 2% diethyl sulfate (DES), UV-irradiation, and/or microwave heating treatments. Both single-stage and multi-stage mutations were investigated for optimizing S. marcescens B742 mutation conditions. Under the optimized mutation conditions (2% DES treatment for 30min plus successive 20min UV-irradiation), the protease and chitosanase activity produced by mutant S. marcescens B742 was 240.15 and 170.6mU/mL, respectively, as compared with 212.58±1.51 and 83.75±6.51mU/mL, respectively, by wild S. marcescens B742. DP efficacy of SSP by mutant S. marcescens B742 reached 91.4±4.6% after 3d of submerged fermentation instead of 83.4±4.7% from the wild S. marcescens B742 after 4d of submerged fermentation. Molecular mass of chitosanase and protease was 41.20 and 47.10kDa, respectively, and both enzymes were verified by mass spectrometry analysis. The chitosanase from both wild and mutant S. marcescens B742 was activated by sodium dodecyl sulfate (SDS), Tween 20, Tween 40, and Triton-100, and the protease and chitosanase were strongly inhibited by ethylenediaminetetraacetic acid (EDTA). These results suggested that S. marcescens B742 mutants can be used in the biological production of chitin through deproteinization of SSP.

  16. Optical biosensor system with integrated microfluidic sample preparation and TIRF based detection

    Science.gov (United States)

    Gilli, Eduard; Scheicher, Sylvia R.; Suppan, Michael; Pichler, Heinz; Rumpler, Markus; Satzinger, Valentin; Palfinger, Christian; Reil, Frank; Hajnsek, Martin; Köstler, Stefan

    2013-05-01

    There is a steadily growing demand for miniaturized bioanalytical devices allowing for on-site or point-of-care detection of biomolecules or pathogens in applications like diagnostics, food testing, or environmental monitoring. These, so called labs-on-a-chip or micro-total analysis systems (μ-TAS) should ideally enable convenient sample-in - result-out type operation. Therefore, the entire process from sample preparation, metering, reagent incubation, etc. to detection should be performed on a single disposable device (on-chip). In the early days such devices were mainly fabricated using glass or silicon substrates and adapting established fabrication technologies from the electronics and semiconductor industry. More recently, the development focuses on the use of thermoplastic polymers as they allow for low-cost high volume fabrication of disposables. One of the most promising materials for the development of plastic based lab-on-achip systems are cyclic olefin polymers and copolymers (COP/COC) due to their excellent optical properties (high transparency and low autofluorescence) and ease of processing. We present a bioanalytical system for whole blood samples comprising a disposable plastic chip based on TIRF (total internal reflection fluorescence) optical detection. The chips were fabricated by compression moulding of COP and microfluidic channels were structured by hot embossing. These microfluidic structures integrate several sample pretreatment steps. These are the separation of erythrocytes, metering of sample volume using passive valves, and reagent incubation for competitive bioassays. The surface of the following optical detection zone is functionalized with specific capture probes in an array format. The plastic chips comprise dedicated structures for simple and effective coupling of excitation light from low-cost laser diodes. This enables TIRF excitation of fluorescently labeled probes selectively bound to detection spots at the microchannel surface

  17. Sample preparation for metalloprotein analysis: A case study using horse chestnuts.

    Science.gov (United States)

    de Magalhães, Cristiana Schmidt; Arruda, Marco Aurélio Zezzi

    2007-03-30

    In the present work, 11 different procedures for protein and metalloprotein extraction from horse chestnuts (Aescullus hippocastanum L.) in natura were tested. After each extraction, total protein was determined and, after protein separation through sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), those metals belonging to the protein structure were mapped by synchrotron radiation X-ray fluorescence (SRXRF). After mapping the elements (Cr, Fe and Mn) in the protein bands (ca. 33 and 23.7kDa), their concentrations were determined using atomic absorption spectrometry (ET AAS). Good results were obtained for protein extraction using a combination of grinding and sonication. However, this strategy was not suitable to preserve metal ions in the protein structure. In fact, there was 42% decrease on Mn concentration using this procedure, compared to that performed with sample agitation in water (taken as reference). On the other hand, when grinding and agitation with an extracting buffer was used, there was a 530% increase of Mn concentration, when compared to the reference procedure. These results indicate agreement between metal identification and determination in proteins as well as the great influence of the extraction procedure (i.e., the sample preparation step) for preserving metals in the protein structures.

  18. Suspension trapping (STrap) sample preparation method for bottom-up proteomics analysis.

    Science.gov (United States)

    Zougman, Alexandre; Selby, Peter J; Banks, Rosamonde E

    2014-05-01

    Despite recent developments in bottom-up proteomics, the need still exists in a fast, uncomplicated, and robust method for comprehensive sample processing especially when applied to low protein amounts. The suspension trapping method combines the advantage of efficient SDS-based protein extraction with rapid detergent removal, reactor-type protein digestion, and peptide cleanup. Proteins are solubilized in SDS. The sample is acidified and introduced into the suspension trapping tip incorporating the depth filter and hydrophobic compartments, filled with the neutral pH methanolic solution. The instantly formed fine protein suspension is trapped in the depth filter stack-this crucial step is aimed at separating the particulate matter in space. SDS and other contaminants are removed in the flow-through, and a protease is introduced. Following the digestion, the peptides are cleaned up using the tip's hydrophobic part. The methodology allows processing of protein loads down to the low microgram/submicrogram levels. The detergent removal takes about 5 min, whereas the tryptic proteolysis of a cellular lysate is complete in as little as 30 min. We have successfully utilized the method for analysis of cellular lysates, enriched membrane preparations, and immunoprecipitates. We expect that due to its robustness and simplicity, the method will become an essential proteomics tool.

  19. Optimized method for preparation of TiO2 nanoparticles dispersion for biological study.

    Science.gov (United States)

    Zhang, Xiaoqiang; Yin, Lihong; Tang, Meng; Pu, Yuepu

    2010-08-01

    The objective of the present study was to develop a practical method to prepare a stable dispersion of TiO2 nanoparticles for biological studies. To address this matter a variety of different approaches for suspension of nanoparticles were conducted. TiO2 (rutile/anatase) dispersions were prepared in distilled water following by treated with different ultrasound energies and various dispersion stabilizers (1.0% carboxymethyl cellulose, 0.5% hydroxypropyl methyl cellulose K4M, 100% fetal bovine serum, and 2.5% bovine serum albumin). The average size of dispersed TiO2 (rutile/anatase) nanoparticles was measured by dynamic light scattering device. Agglomerate sizes of TiO2 in distilled water and 100% FBS were estimated using TEM analysis. Sedimentation rate of TiO2 (rutile/anatase) nanoparticles in dispersion was monitored by optical absorbance detection. In vitro cytotoxicity of various stabilizers in 16-HBE cells was measured using MTT assay. The optimized process for preparation of TiO2 (rutile/anatase) nanoparticles dispersion was first to vibrate the nanoparticles by vortex and disperse particles by ultrasonic vibration in distilled water, then to add dispersion stabilizers to the dispersion, and finally to sonicate the nanoparticles in dispersion. TiO2 (rutile/anatase) nanoparticles were disaggregated sufficiently with an ultrasound energy of 33 W for 10 min. The formation of TiO2 (rutile/anatase) agglomerates in distilled water was decreased obviously by addition of 1.0% CMC, 0.5% HPMC K4M, 100% FBS and 2.5% BSA. For the benefit of cell growth, FBS is the most suitable stabilizer for preparation of TiO2 (rutile/anatase) particle dispersions and subsequent investigation of the in vivo and in vitro behavior of TiO2 (rutile/anatase) nanoparticles. This method is practicable to prepare a stable dispersion of TiO2 (rutile/anatase) nanoparticles for at least 120 h.

  20. Investigation into Alternative Sample Preparation Techniques for the Determination of Heavy Metals in Stationary Source Emission Samples Collected on Quartz Filters

    Directory of Open Access Journals (Sweden)

    Sharon L. Goddard

    2014-11-01

    Full Text Available Monitoring stationary source emissions for heavy metals generally requires the use of quartz filters to collect samples because of the high temperature and high moisture sampling environment. The documentary standard method sample preparation technique in Europe, EN 14385, uses digestion in hydrofluoric acid and nitric acid (HF/HNO3 followed by complexing with boric acid (H3BO3 prior to analysis. However, the use of this method presents a number of problems, including significant instrumental drift during analysis caused by the matrix components, often leading to instrument breakdown and downtime for repairs, as well as posing significant health and safety risks. The aim of this work was to develop an alternative sample preparation technique for emissions samples on quartz filters. The alternative techniques considered were: (i acid digestion in a fluoroboric acid (HBF4 and HNO3 mixture and (ii acid extraction in an aqua regia (AR mixture (HCl and HNO3. Assessment of the effectiveness of these options included determination of interferences and signal drift, as well as validating the different methods by measurement of matrix certified reference materials (CRMs, and comparing the results obtained from real test samples and sample blanks to determine limits of detection. The results showed that the HBF4/HNO3 mixture provides the most viable alternative to the documentary standard preparation technique.

  1. State of the art of environmentally friendly sample preparation approaches for determination of PBDEs and metabolites in environmental and biological samples: A critical review.

    Science.gov (United States)

    Berton, Paula; Lana, Nerina B; Ríos, Juan M; García-Reyes, Juan F; Altamirano, Jorgelina C

    2016-01-28

    Green chemistry principles for developing methodologies have gained attention in analytical chemistry in recent decades. A growing number of analytical techniques have been proposed for determination of organic persistent pollutants in environmental and biological samples. In this light, the current review aims to present state-of-the-art sample preparation approaches based on green analytical principles proposed for the determination of polybrominated diphenyl ethers (PBDEs) and metabolites (OH-PBDEs and MeO-PBDEs) in environmental and biological samples. Approaches to lower the solvent consumption and accelerate the extraction, such as pressurized liquid extraction, microwave-assisted extraction, and ultrasound-assisted extraction, are discussed in this review. Special attention is paid to miniaturized sample preparation methodologies and strategies proposed to reduce organic solvent consumption. Additionally, extraction techniques based on alternative solvents (surfactants, supercritical fluids, or ionic liquids) are also commented in this work, even though these are scarcely used for determination of PBDEs. In addition to liquid-based extraction techniques, solid-based analytical techniques are also addressed. The development of greener, faster and simpler sample preparation approaches has increased in recent years (2003-2013). Among green extraction techniques, those based on the liquid phase predominate over those based on the solid phase (71% vs. 29%, respectively). For solid samples, solvent assisted extraction techniques are preferred for leaching of PBDEs, and liquid phase microextraction techniques are mostly used for liquid samples. Likewise, green characteristics of the instrumental analysis used after the extraction and clean-up steps are briefly discussed.

  2. The Optimization of Matrix Preparation Process and Performance Testing for Molten Carbonate Fuel Cell

    Directory of Open Access Journals (Sweden)

    Jian Cheng

    2014-01-01

    Full Text Available A key component in the molten carbonate fuel cell (MCFC is electrolyte matrix, which provides both ionic conduction and gas sealing. The aim of this work is to investigate the effects of selected operating conditions on the performance of the matrix preparation. Slurries were prepared to produce matrices by the technique of tape casting. The characteristics of the slurries and matrices were examined by laser particle size analyzer, scanning electron microscopy, and BET surface area analyzer. The testing results revealed that a slurry composition with 40 wt.% lithium aluminate was the optimal formulation to produce a good matrix with a pore size distribution of 0.1–0.4 μm and porosity of 50 vol.%. Coarse and fine LiAlO2 particles were added in the matrix slurry to enhance the mechanical strength. Several green sheets were heated and pressed to enhance the bulk density to get a dense matrix of MCFC. Finally, a single MCFC was assembled and tested. The testing results showed the matrix with 40% solid loading gave the maximum discharge current of 20 A at 0.56 V.

  3. Thermal preparation of chitosan-acrylic acid superabsorbent: optimization, characteristic and water absorbency.

    Science.gov (United States)

    Ge, Huacai; Wang, Senkang

    2014-11-26

    Chitosan-acrylic acid superabsorbent polymer was successfully prepared by the thermal reaction without using initiator and crosslinker in air. The effects of some reaction variables on the water absorbency of this polymer were investigated by orthogonal tests, and the optimal conditions were described. The influences of temperature, time, ratio of the reactants and neutralization degree of acrylic acid on the reaction were further studied. These polymers were also prepared in nitrogen atmosphere and by using a radical initiator and compared against thermal reaction obtained polymers. The structures of the polymers were characterized by FT-IR, TGA, XRD, (13)C NMR and elemental analyses. The results showed that the thermal reaction product of acrylic acid with chitosan might form N-carboxyethyl grafted and amide-linked polymer and this product could absorb water 644 times its own dry weight. The possible mechanism for the thermal reaction was further suggested. The purpose of this research was to explore the friendly synthesized method of the superabsorbent.

  4. Model reduction algorithms for optimal control and importance sampling of diffusions

    Science.gov (United States)

    Hartmann, Carsten; Schütte, Christof; Zhang, Wei

    2016-08-01

    We propose numerical algorithms for solving optimal control and importance sampling problems based on simplified models. The algorithms combine model reduction techniques for multiscale diffusions and stochastic optimization tools, with the aim of reducing the original, possibly high-dimensional problem to a lower dimensional representation of the dynamics, in which only a few relevant degrees of freedom are controlled or biased. Specifically, we study situations in which either a reaction coordinate onto which the dynamics can be projected is known, or situations in which the dynamics shows strongly localized behavior in the small noise regime. No explicit assumptions about small parameters or scale separation have to be made. We illustrate the approach with simple, but paradigmatic numerical examples.

  5. Optimal cross-sectional sampling for river modelling with bridges: An information theory-based method

    Science.gov (United States)

    Ridolfi, E.; Alfonso, L.; Di Baldassarre, G.; Napolitano, F.

    2016-06-01

    The description of river topography has a crucial role in accurate one-dimensional (1D) hydraulic modelling. Specifically, cross-sectional data define the riverbed elevation, the flood-prone area, and thus, the hydraulic behavior of the river. Here, the problem of the optimal cross-sectional spacing is solved through an information theory-based concept. The optimal subset of locations is the one with the maximum information content and the minimum amount of redundancy. The original contribution is the introduction of a methodology to sample river cross sections in the presence of bridges. The approach is tested on the Grosseto River (IT) and is compared to existing guidelines. The results show that the information theory-based approach can support traditional methods to estimate rivers' cross-sectional spacing.

  6. Quality by design approach for optimizing the formulation and physical properties of extemporaneously prepared orodispersible films.

    Science.gov (United States)

    Visser, J Carolina; Dohmen, Willem M C; Hinrichs, Wouter L J; Breitkreutz, Jörg; Frijlink, Henderik W; Woerdenbag, Herman J

    2015-05-15

    The quality by design (QbD) approach was applied for optimizing the formulation of extemporaneously prepared orodispersible films (ODFs) using Design-Expert® Software. The starting formulation was based on earlier experiments and contained the film forming agents hypromellose and carbomer 974P and the plasticizer glycerol (Visser et al., 2015). Trometamol and disodium EDTA were added to stabilize the solution. To optimize this formulation a quality target product profile was established in which critical quality attributes (CQAs) such as mechanical properties and disintegration time were defined and quantified. As critical process parameters (CPP) that were evaluated for their effect on the CQAs the percentage of hypromellose and the percentage of glycerol as well as the drying time were chosen. Response surface methodology (RMS) was used to evaluate the effects of the CPPs on the CQAs of the final product. The main factor affecting tensile strength and Young's modulus was the percentage of glycerol. Elongation at break was mainly influenced by the drying temperature. Disintegration time was found to be sensitive to the percentage of hypromellose. From the results a design space could be created. As long as the formulation and process variables remain within this design space, a product is obtained with desired characteristics and that meets all set quality requirements.

  7. An S/H circuit with parasitics optimized for IF-sampling

    Science.gov (United States)

    Xuqiang, Zheng; Fule, Li; Zhijun, Wang; Weitao, Li; Wen, Jia; Zhihua, Wang; Shigang, Yue

    2016-06-01

    An IF-sampling S/H is presented, which adopts a flip-around structure, bottom-plate sampling technique and improved input bootstrapped switches. To achieve high sampling linearity over a wide input frequency range, the floating well technique is utilized to optimize the input switches. Besides, techniques of transistor load linearization and layout improvement are proposed to further reduce and linearize the parasitic capacitance. The S/H circuit has been fabricated in 0.18-μm CMOS process as the front-end of a 14 bit, 250 MS/s pipeline ADC. For 30 MHz input, the measured SFDR/SNDR of the ADC is 94.7 dB/68. 5dB, which can remain over 84.3 dB/65.4 dB for input frequency up to 400 MHz. The ADC presents excellent dynamic performance at high input frequency, which is mainly attributed to the parasitics optimized S/H circuit. Poject supported by the Shenzhen Project (No. JSGG20150512162029307).

  8. Optimizing 4-Dimensional Magnetic Resonance Imaging Data Sampling for Respiratory Motion Analysis of Pancreatic Tumors

    Energy Technology Data Exchange (ETDEWEB)

    Stemkens, Bjorn, E-mail: b.stemkens@umcutrecht.nl [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Tijssen, Rob H.N. [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands); Senneville, Baudouin D. de [Imaging Division, University Medical Center Utrecht, Utrecht (Netherlands); L' Institut de Mathématiques de Bordeaux, Unité Mixte de Recherche 5251, Centre National de la Recherche Scientifique/University of Bordeaux, Bordeaux (France); Heerkens, Hanne D.; Vulpen, Marco van; Lagendijk, Jan J.W.; Berg, Cornelis A.T. van den [Department of Radiotherapy, University Medical Center Utrecht, Utrecht (Netherlands)

    2015-03-01

    Purpose: To determine the optimum sampling strategy for retrospective reconstruction of 4-dimensional (4D) MR data for nonrigid motion characterization of tumor and organs at risk for radiation therapy purposes. Methods and Materials: For optimization, we compared 2 surrogate signals (external respiratory bellows and internal MRI navigators) and 2 MR sampling strategies (Cartesian and radial) in terms of image quality and robustness. Using the optimized protocol, 6 pancreatic cancer patients were scanned to calculate the 4D motion. Region of interest analysis was performed to characterize the respiratory-induced motion of the tumor and organs at risk simultaneously. Results: The MRI navigator was found to be a more reliable surrogate for pancreatic motion than the respiratory bellows signal. Radial sampling is most benign for undersampling artifacts and intraview motion. Motion characterization revealed interorgan and interpatient variation, as well as heterogeneity within the tumor. Conclusions: A robust 4D-MRI method, based on clinically available protocols, is presented and successfully applied to characterize the abdominal motion in a small number of pancreatic cancer patients.

  9. The functional model of optimization of the special physical preparation of students in the period of flying practice

    Directory of Open Access Journals (Sweden)

    Kirpenko V.N.

    2013-03-01

    Full Text Available It is considered approaches to optimization special physical preparation of students during the period of flying practice. For the construction of functional model of such system new information IDEF technology is utillized (ICAM Definition. The feature of technology is gradual introduction all large levels of working out in detail (decoupligs. It is marked that it is expedient to carry out a decouplig before functions which will realize leaders of physical preparation and instructor of flying preparation. It is well-proven that on the stage of research of function a fundamental place is occupied by a functional design. The result of optimization of maintenance of teaching is systematization of knowledge, abilities, facilities of development and support professionally of meaningful qualities of students. The hierarchical levels of process of systematization of maintenance of teaching are recommended. It is offered directions of realization of functional model through conditioning optimization of pedagogical activity of teacher.

  10. Application of the central composite design to optimize the preparation of novel micelles of harmine

    Directory of Open Access Journals (Sweden)

    Bei YY

    2013-05-01

    Full Text Available Yong-Yan Bei,1,* Xiao-Feng Zhou,2,3,* Ben-Gang You,1 Zhi-Qiang Yuan,1 Wei-Liang Chen,1 Peng Xia,1 Yang Liu,1 Yong Jin,4 Xiao-Juan Hu,1 Qiao-Ling Zhu,1 Chun-Ge Zhang,1 Xue-Nong Zhang,1 Liang Zhang5 1Department of Pharmaceutics, College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, People’s Republic of China; 2College of Radiological Medicine and Protection, Soochow University, Suzhou, People’s Republic of China; 3Changshu Hospital of Traditional Chinese Medicine, Changshu, People’s Republic of China; 4Invasive Technology Department, The Second Affiliated Hospital of Soochow University, Suzhou, People’s Republic of China; 5Department of Biopharmaceutics, College of Pharmaceutical Sciences, Soochow University, Suzhou, People’s Republic of China*These authors contributed equally to the paperAbstract: Lactose–palmitoyl–trimethyl–chitosan (Lac-TPCS, a novel amphipathic self-assembled polymer, was synthesized for administration of insoluble drugs to reduce their adverse effects. The central composite design was used to study the preparation technique of harmine (HM-loaded self-assembled micelles based on Lac-TPCS (Lac-TPCS/HM. Three preparation methods and single factors were screened, including solvent type, HM amount, hydration volume, and temperature. The optimal preparation technique was identified after investigating the influence of two independent factors, namely, HM amount and hydration volume, on four indexes, ie, encapsulation efficiency (EE, drug-loading amount (LD, particle size, and polydispersity index (PDI. Analysis of variance showed a high coefficient of determination of 0.916 to 0.994, thus ensuring a satisfactory adjustment of the predicted prescription. The maximum predicted values of the optimal prescription were 91.62%, 14.20%, 183.3 nm, and 0.214 for EE, LD, size, and PDI, respectively, when HM amount was 1.8 mg and hydration volume was 9.6 mL. HM-loaded micelles were successfully characterized by

  11. Toward a Fieldable Atomic Mass Spectrometer for Safeguards Applications: Sample Preparation and Ionization

    Energy Technology Data Exchange (ETDEWEB)

    Barinaga, Charles J.; Hager, George J.; Hart, Garret L.; Koppenaal, David W.; Marcus, R. Kenneth; Jones, Sarah MH; Manard, Benjamin T.

    2014-10-31

    The International Atomic Energy Agency’s (IAEA’s) long-term research and development plan calls for the development of new methods to detect misuse at nuclear fuel cycle facilities such as reprocessing and enrichment plants. At enrichment plants, for example, the IAEA’s contemporary safeguards approaches are based on a combination of routine and random inspections that include collection of UF6 samples from in-process material and selected cylinders for subsequent analyses. These analyses include destructive analysis (DA) in a laboratory (typically by mass spectrometry [MS]) for isotopic characterization, and environmental sampling (ES) for subsequent laboratory elemental and isotopic analysis (also both typically by MS). One area of new method development includes moving this kind of isotope ratio analytical capability for DA and ES activities into the field. Some of the reasons for these developments include timeliness of results, avoidance of hazardous material shipments, and guidance for additional sample collecting. However, this capability does not already exist for several reasons, such as that most lab-based chemical and instrumental methods rely on laboratory infrastructure (highly trained staff, power, space, hazardous material handling, etc.) and require significant amounts of consumables (power, compressed gases, etc.). In addition, there are no currently available, fieldable instruments for atomic or isotope ratio analysis. To address these issues, Pacific Northwest National Laboratory (PNNL) and collaborator, Clemson University, are studying key areas that limit the fieldability of isotope ratio mass spectrometry for atomic ions: sample preparation and ionization, and reducing the physical size of a fieldable mass spectrometer. PNNL is seeking simple and robust techniques that could be effectively used by inspectors who may have no expertise in analytical MS. In this report, we present and describe the preliminary findings for three candidate

  12. Preparation of edible wild fruit and plant samples for analysis and some difficulties encountered in such analyses

    CSIR Research Space (South Africa)

    Strydom, ESP

    1969-12-01

    Full Text Available Freeze-dried samples are used for analysis and the methods of preparation of samples for freeze-drying are discussed. Freeze-drying has obvious advantages but has also a few minor disadvantages. Difficulties encountered in the determination of some...

  13. Selectivity in the sample preparation for the analysis of drug residues in products of animal origin using LC-MS

    NARCIS (Netherlands)

    Berendsen, B.J.A.; Stolker, A.A.M.; Nielen, M.W.F.

    2013-01-01

    Sample preparation is critical in relation to analysis time, sample throughput and therefore analysis costs. Due to recent advances in liquid chromatography-mass spectrometry (LC-MS) instrumentation, the detection of many compounds within one run became possible, and methods for the simultaneous ana

  14. CTEPP STANDARD OPERATING PROCEDURE FOR EXTRACTING AND PREPARING AIR SAMPLES FOR ANALYSIS OF POLAR PERSISTENT ORGANIC POLLUTANTS (SOP-5.13)

    Science.gov (United States)

    The method for extracting and preparing indoor and outdoor air samples for analysis of polar persistent organic pollutants is summarized in this SOP. It covers the preparation of samples that are to be analyzed by gas chromatography/mass spectrometry.

  15. CTEPP STANDARD OPERATING PROCEDURE FOR EXTRACTING AND PREPARING AIR SAMPLES FOR ANALYSIS OF POLAR PERSISTENT ORGANIC POLLUTANTS (SOP-5.13)

    Science.gov (United States)

    The method for extracting and preparing indoor and outdoor air samples for analysis of polar persistent organic pollutants is summarized in this SOP. It covers the preparation of samples that are to be analyzed by gas chromatography/mass spectrometry.

  16. Optimization of sampling pattern and the design of Fourier ptychographic illuminator.

    Science.gov (United States)

    Guo, Kaikai; Dong, Siyuan; Nanda, Pariksheet; Zheng, Guoan

    2015-03-09

    Fourier ptychography (FP) is a recently developed imaging approach that facilitates high-resolution imaging beyond the cutoff frequency of the employed optics. In the original FP approach, a periodic LED array is used for sample illumination, and therefore, the scanning pattern is a uniform grid in the Fourier space. Such a uniform sampling scheme leads to 3 major problems for FP, namely: 1) it requires a large number of raw images, 2) it introduces the raster grid artefacts in the reconstruction process, and 3) it requires a high-dynamic-range detector. Here, we investigate scanning sequences and sampling patterns to optimize the FP approach. For most biological samples, signal energy is concentrated at low-frequency region, and as such, we can perform non-uniform Fourier sampling in FP by considering the signal structure. In contrast, conventional ptychography perform uniform sampling over the entire real space. To implement the non-uniform Fourier sampling scheme in FP, we have designed and built an illuminator using LEDs mounted on a 3D-printed plastic case. The advantages of this illuminator are threefold in that: 1) it reduces the number of image acquisitions by at least 50% (68 raw images versus 137 in the original FP setup), 2) it departs from the translational symmetry of sampling to solve the raster grid artifact problem, and 3) it reduces the dynamic range of the captured images 6 fold. The results reported in this paper significantly shortened acquisition time and improved quality of FP reconstructions. It may provide new insights for developing Fourier ptychographic imaging platforms and find important applications in digital pathology.

  17. A lab-on-a-chip system with integrated sample preparation and loop-mediated isothermal amplification for rapid and quantitative detection of Salmonella spp. in food samples

    DEFF Research Database (Denmark)

    Sun, Yi; Than Linh, Quyen; Hung, Tran Quang

    2015-01-01

    and usually take a few hours to days to complete. In response to the demand for rapid on line or at site detection of pathogens, in this study, we describe for the first time an eight-chamber lab-on-a-chip (LOC) system with integrated magnetic beads-based sample preparation and loop-mediated isothermal...

  18. Development of microwave-assisted drying methods for sample preparation for dried spot micro-X-ray fluorescence analysis.

    Science.gov (United States)

    Link, Dirk D; Kingston, H M; Havrilla, George J; Colletti, Lisa P

    2002-03-01

    Although dried spot micro X-ray fluorescence (MXRF) is an effective analytical technique for trace elemental analysis, the sample preparation procedures currently used suffer from a number of drawbacks. These drawbacks include relatively long preparation times, lack of control of the sample preparation environment, and possibility of loss of volatile analytes during the drying process. Microwave-assisted drying offers several advantages for dried spot preparation, including control of the environment and minimized volatility because of the differences between microwave heating and conventional heating. A microwave-assisted drying technique has been evaluated for use in preparing dried spots for trace analysis. Two apparatus designs for microwave drying were constructed and tested using multielement standard solutions, a standard reference material, and a "real-world" semiconductor cleaning solution. Following microwave-assisted drying of these aqueous samples, the residues were redissolved and analyzed by ICPMS. Effective recovery was obtained using the microwave drying methods, demonstrating that the microwave drying apparatus and methods described here may be more efficient alternatives for dried spot sample preparation.

  19. Demonstration of a frozen sample aliquotter to prepare plasma and serum aliquots without thawing frozen parent samples.

    Science.gov (United States)

    Ellis, Helena Judge; Venturini, Deborah S

    2013-06-01

    Human biospecimens represent invaluable resources to advance molecular medicine, epidemiology, and biomarker discovery/validation, among other biomedical research. Biobanks typically cryopreserve biospecimens to safeguard their biochemical composition. However, exposing specimens repeatedly to freeze/thaw cycles can degrade their integrity in unforeseen ways. Those biobanks storing liquid samples, thus, regularly make a fundamental compromise at collection time between freezing samples in many small volumes (e.g., 0.5 mL or smaller) or in fewer, larger volumes (e.g., 1.8 mL). The former eliminates the need to expose samples to repeated freeze/thaw cycling, although increasing up-front labor costs, consumables used, and cold storage space requirements. The latter decreases up-front labor costs, consumables, and cold storage requirements, yet exposes samples repeatedly to damaging freeze/thaw cycles when smaller aliquots are needed for analysis. The Rhode Island BioBank at Brown University (RIBB) thoroughly evaluated the performance of an original technology that minimizes a sample's exposure to freeze/thaw cycling by enabling the automated extraction of frozen aliquots from one single frozen parent sample without thawing it. A technology that eliminates unnecessary sample exposures to freeze/thaw cycles could help protect sample integrity, extend its useful life, and effectively rectify and eliminate the aforementioned need to compromise. This report presents the results of the evaluation, and conclusively demonstrates the technology's ability to extract multiple uniform frozen aliquots from a single cryotube of never-thawed frozen human plasma, which faithfully represent the parent sample when analyzed for typical biochemical analytes, showing a coefficient of variability lower than 5.5%.

  20. Preparation of solid-phase microextraction fiber coated with single-walled carbon nanotubes by electrophoretic deposition and its application in extracting phenols from aqueous samples.

    Science.gov (United States)

    Li, Quanlong; Wang, Xuefeng; Yuan, Dongxing

    2009-02-27

    A novel solid-phase microextraction (SPME) Pt fiber coated with single-walled carbon nanotubes (SWCNTs) was prepared by electrophoretic deposition (EPD) and applied to the determination of phenols in aqueous samples by direct immersion (DI)-SPME-HPLC-UV. The results revealed that EPD was a simple and reproducible technique for the preparation of SPME fibers coated with SWCNTs without the use of adhesive. The obtained SWCNT coating did not swell in organic solvents nor strip off from substrate, and possessed high mechanical strength due to the strong Van der Waals attractions between the surfaces of the SWCNTs. The prepared SPME fiber was conductive since both SWCNT coating and Pt wire were conductive. Using Pt wire as substrate, the fiber was unbreakable. Owing to the presence of oxygenated groups on SWCNTs and the high surface area of SWCNTs, the SWCNT fiber was similar to or superior to commercial PA fiber in extracting the studied phenols from aqueous sample. A durability of more than 80 analyses was achieved for one unique fiber. Under optimized conditions, the detection limits for the phenols varied between 0.9 and 3.8 ng/mL, the precisions were in the range of 0.7-3.2% (n=3), and linear ranges were within 10 and 300 ng/mL. The method was successfully applied to the analysis of spiked seawater and tap water samples with the recoveries from 87.5 to 102.0%.

  1. State-of-the-art technologies for rapid and high-throughput sample preparation and analysis of N-glycans from antibodies.

    Science.gov (United States)

    Aich, Udayanath; Lakbub, Jude; Liu, Aston

    2016-06-01

    Glycosylation is a PTM that occurs during production of many protein-based biologic drugs and can have a profound impact on their biological, clinical, and pharmacological properties. Quality by design, process optimization, and advance in manufacturing technology create a demand for robust, sensitive, and accurate profiling and quantification of antibody glycosylation. Potential drawbacks in antibody glycosylation profiling include the high hands-on time required for sample preparation and several hours for data acquisition and analysis. Rapid and high-throughput (HTP) N-glycan profiling and characterization along with automation for sample preparation and analysis are essential for extensive antibody glycosylation analysis due to the substantial improvement of turnaround time. The first part of this review article will focus on the recent progress in rapid and HTP sample preparation and analysis of antibody glycosylation. Subsequently, the article will cover a brief overview of various separation and mass spectrometric methods for the rapid and HTP analysis of N-glycans in antibodies. Finally, we will discuss the recent developments in process analytical technologies for the screening and quantification of N-glycans in antibodies.

  2. Advanced overlay: sampling and modeling for optimized run-to-run control

    Science.gov (United States)

    Subramany, Lokesh; Chung, WoongJae; Samudrala, Pavan; Gao, Haiyong; Aung, Nyan; Gomez, Juan Manuel; Gutjahr, Karsten; Park, DongSuk; Snow, Patrick; Garcia-Medina, Miguel; Yap, Lipkong; Demirer, Onur Nihat; Pierson, Bill; Robinson, John C.

    2016-03-01

    In recent years overlay (OVL) control schemes have become more complicated in order to meet the ever shrinking margins of advanced technology nodes. As a result, this brings up new challenges to be addressed for effective run-to- run OVL control. This work addresses two of these challenges by new advanced analysis techniques: (1) sampling optimization for run-to-run control and (2) bias-variance tradeoff in modeling. The first challenge in a high order OVL control strategy is to optimize the number of measurements and the locations on the wafer, so that the "sample plan" of measurements provides high quality information about the OVL signature on the wafer with acceptable metrology throughput. We solve this tradeoff between accuracy and throughput by using a smart sampling scheme which utilizes various design-based and data-based metrics to increase model accuracy and reduce model uncertainty while avoiding wafer to wafer and within wafer measurement noise caused by metrology, scanner or process. This sort of sampling scheme, combined with an advanced field by field extrapolated modeling algorithm helps to maximize model stability and minimize on product overlay (OPO). Second, the use of higher order overlay models means more degrees of freedom, which enables increased capability to correct for complicated overlay signatures, but also increases sensitivity to process or metrology induced noise. This is also known as the bias-variance trade-off. A high order model that minimizes the bias between the modeled and raw overlay signature on a single wafer will also have a higher variation from wafer to wafer or lot to lot, that is unless an advanced modeling approach is used. In this paper, we characterize the bias-variance trade off to find the optimal scheme. The sampling and modeling solutions proposed in this study are validated by advanced process control (APC) simulations to estimate run-to-run performance, lot-to-lot and wafer-to- wafer model term monitoring to

  3. Comparison of different sample preparation methods for platinum determination in cultured cells by graphite furnace atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Man Xiao

    2017-01-01

    Full Text Available Background Platinum-based agents are widely used in chemotherapy against solid tumors and insufficient intracellular drug accumulation is one of the leading causes of platinum resistance which is associated with poor survival of tumor patients. Thus, the detection of intracellular platinum is pivotal for studies aiming to overcome platinum resistance. In the present study, we aimed to establish a reliable graphite furnace atomic absorption spectrometry (GFAAS-based assay to quantify the intracellular platinum content for cultured cells. Methods Several most commonly applied cell preparation methods, including 0.2% HNO3, 0.2% Triton X-100, concentrated nitric acid, RIPA combined with concentrated nitric acid and hydroxide, followed by GFAAS for platinum detection were compared in ovarian, cervical and liver cancer cell lines to obtain the optimal one, and parameters regarding linearity, accuracy, precision and sensitivity were evaluated. Influence of other metals on platinum detection and the storage conditions of samples were also determined. Results The treatment of cells with 0.2% HNO3 was superior to other approaches with fewer platinum loss and better repeatability. The recovery rate and precision of this method were 97.3%–103.0% and 1.4%–3.8%, respectively. The average recoveries in the presence of other metals were 95.1%–103.1%. The detection limit was 13.23 ug/L. The recovery rate of platinum remained acceptable even in cell samples stored in −20 °C or −80 °C for two months. Discussion After comparison, we found that 0.2% HNO3 was optimal for intracellular platinum quantification based on GFAAS, which presented values compatible with that of inductively-coupled plasma mass-spectrometry (ICP-MS, and this is partially attributed to the simplicity of this method. Moreover, the assay was proved to be accurate, sensitive, cost-effective and suitable for the research of platinum-based antitumor therapy.

  4. Humidity-controlled preparation of frozen-hydrated biological samples for cryogenic coherent x-ray diffraction microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Takayama, Yuki; Nakasako, Masayoshi [Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Kanagawa 223-8522 (Japan); RIKEN Harima Institute/SPring-8, 1-1-1 Kouto, Mikaduki, Sayo, Hyogo 679-5148 (Japan)

    2012-05-15

    Coherent x-ray diffraction microscopy (CXDM) has the potential to visualize the structures of micro- to sub-micrometer-sized biological particles, such as cells and organelles, at high resolution. Toward advancing structural studies on the functional states of such particles, here, we developed a system for the preparation of frozen-hydrated biological samples for cryogenic CXDM experiments. The system, which comprised a moist air generator, microscope, micro-injector mounted on a micromanipulator, custom-made sample preparation chamber, and flash-cooling device, allowed for the manipulation of sample particles in the relative humidity range of 20%-94%rh at 293 K to maintain their hydrated and functional states. Here, we report the details of the system and the operation procedure, including its application to the preparation of a frozen-hydrated chloroplast sample. Sample quality was evaluated through a cryogenic CXDM experiment conducted at BL29XUL of SPring-8. Taking the performance of the system and the quality of the sample, the system was suitable to prepare frozen-hydrated biological samples for cryogenic CXDM experiments.

  5. Rapid Preparation Methods of Biological Samples for Ionic Compounds Using Ion Exchange Type Monolithic Silica Spin Column

    OpenAIRE

    宮崎, 将太; 山田, 智子; 太田, 茂徳; 斉藤, 剛; 奈女良, 昭; 大平, 真義

    2010-01-01

    We developed a device comprising a spin column packed with ion exchange type (SCX and SAX) monolithic silica for extracting ionic compounds from biological samples. The methods involving the use of these spin column are not useful for the extraction of ionic analytes, but are highly reproducible for the analysis in serum and urine. This spin column enabled sample preparation in less than 10 min. Handling such as sample loading, washing, and elution of analytes, was exhibited by the centrifuga...

  6. Analysis and Optimization of Bulk DNA Sampling with Binary Scoring for Germplasm Characterization

    Science.gov (United States)

    Reyes-Valdés, M. Humberto; Santacruz-Varela, Amalio; Martínez, Octavio; Simpson, June; Hayano-Kanashiro, Corina; Cortés-Romero, Celso

    2013-01-01

    The strategy of bulk DNA sampling has been a valuable method for studying large numbers of individuals through genetic markers. The application of this strategy for discrimination among germplasm sources was analyzed through information theory, considering the case of polymorphic alleles scored binarily for their presence or absence in DNA pools. We defined the informativeness of a set of marker loci in bulks as the mutual information between genotype and population identity, composed by two terms: diversity and noise. The first term is the entropy of bulk genotypes, whereas the noise term is measured through the conditional entropy of bulk genotypes given germplasm sources. Thus, optimizing marker information implies increasing diversity and reducing noise. Simple formulas were devised to estimate marker information per allele from a set of estimated allele frequencies across populations. As an example, they allowed optimization of bulk size for SSR genotyping in maize, from allele frequencies estimated in a sample of 56 maize populations. It was found that a sample of 30 plants from a random mating population is adequate for maize germplasm SSR characterization. We analyzed the use of divided bulks to overcome the allele dilution problem in DNA pools, and concluded that samples of 30 plants divided into three bulks of 10 plants are efficient to characterize maize germplasm sources through SSR with a good control of the dilution problem. We estimated the informativeness of 30 SSR loci from the estimated allele frequencies in maize populations, and found a wide variation of marker informativeness, which positively correlated with the number of alleles per locus. PMID:24260321

  7. Analysis and optimization of bulk DNA sampling with binary scoring for germplasm characterization.

    Directory of Open Access Journals (Sweden)

    M Humberto Reyes-Valdés

    Full Text Available The strategy of bulk DNA sampling has been a valuable method for studying large numbers of individuals through genetic markers. The application of this strategy for discrimination among germplasm sources was analyzed through information theory, considering the case of polymorphic alleles scored binarily for their presence or absence in DNA pools. We defined the informativeness of a set of marker loci in bulks as the mutual information between genotype and population identity, composed by two terms: diversity and noise. The first term is the entropy of bulk genotypes, whereas the noise term is measured through the conditional entropy of bulk genotypes given germplasm sources. Thus, optimizing marker information implies increasing diversity and reducing noise. Simple formulas were devised to estimate marker information per allele from a set of estimated allele frequencies across populations. As an example, they allowed optimization of bulk size for SSR genotyping in maize, from allele frequencies estimated in a sample of 56 maize populations. It was found that a sample of 30 plants from a random mating population is adequate for maize germplasm SSR characterization. We analyzed the use of divided bulks to overcome the allele dilution problem in DNA pools, and concluded that samples of 30 plants divided into three bulks of 10 plants are efficient to characterize maize germplasm sources through SSR with a good control of the dilution problem. We estimated the informativeness of 30 SSR loci from the estimated allele frequencies in maize populations, and found a wide variation of marker informativeness, which positively correlated with the number of alleles per locus.

  8. Methodologies and perspectives of proteomics applied to filamentous fungi: from sample preparation to secretome analysis.

    Science.gov (United States)

    Bianco, Linda; Perrotta, Gaetano

    2015-03-12

    Filamentous fungi possess the extraordinary ability to digest complex biomasses and mineralize numerous xenobiotics, as consequence of their aptitude to sensing the environment and regulating their intra and extra cellular proteins, producing drastic changes in proteome and secretome composition. Recent advancement in proteomic technologies offers an exciting opportunity to reveal the fluctuations of fungal proteins and enzymes, responsible for their metabolic adaptation to a large variety of environmental conditions. Here, an overview of the most commonly used proteomic strategies will be provided; this paper will range from sample preparation to gel-free and gel-based proteomics, discussing pros and cons of each mentioned state-of-the-art technique. The main focus will be kept on filamentous fungi. Due to the biotechnological relevance of lignocellulose degrading fungi, special attention will be finally given to their extracellular proteome, or secretome. Secreted proteins and enzymes will be discussed in relation to their involvement in bio-based processes, such as biomass deconstruction and mycoremediation.

  9. Atmospheric pressure microwave sample preparation procedure for the combined analysis of total phosphorus and kjeldahl nitrogen.

    Science.gov (United States)

    Collins, L W; Chalk, S J; Kingston, H M

    1996-08-01

    An atmospheric pressure microwave digestion method has been developed for the combined analysis of total phosphorus and Kjeldahl nitrogen in complex matrices. In comparison to the digestion steps in EPA Methods 365.4 (total phosphorus) and 351.x (Kjeldahl nitrogen), this method requires less time, eliminates the need for a catalyst, and reduces the toxicity of the waste significantly. It employs a microwave-assisted digestion step, using refluxing borosilicate glass vessels at atmospheric pressure. Traditionally, this method has a time-consuming sample preparation step and generates toxic waste through the use of heavy metal catalysts. These advantages are gained by the combination of a high boiling point acid (sulfuric acid) and the application of focused microwave irradiation, which enhances the digestion process by direct energy coupling. NIST standard reference materials 1572 (citrus leaves), 1577a (bovine liver), and 1566 (oyster tissue) and tryptophan were analyzed to validate the method. Phosphorus concentrations were determined by the colorimetric ascorbic acid method outlined in EPA Method 365.3. Kjeldahl nitrogen concentrations were determined using EPA Method 351.1. The results of the analyses showed good precision and are in excellent agreement with the NIST published values for both elements.

  10. Simplified sample preparation method for protein identification by matrix-assisted laser desorption/ionization mass spectrometry: in-gel digestion on the probe surface

    DEFF Research Database (Denmark)

    Stensballe, A; Jensen, Ole Nørregaard

    2001-01-01

    Identification and detailed characterization of complex mixtures of proteins separated by polyacrylamide gel electrophoresis (PAGE) require optimized and robust methods for interfacing electrophoretic techniques to mass spectrometry. Peptide mapping by matrix-assisted laser desorption/ionization-......Identification and detailed characterization of complex mixtures of proteins separated by polyacrylamide gel electrophoresis (PAGE) require optimized and robust methods for interfacing electrophoretic techniques to mass spectrometry. Peptide mapping by matrix-assisted laser desorption...... for protein identification similar to that obtained by the traditional protocols for in-gel digestion and MALDI peptide mass mapping of human proteins, i.e. approximately 60%. The overall performance of the novel on-probe digestion method is comparable with that of the standard in-gel sample preparation...

  11. Influence of sampling, storage, processing and optimal experimental conditions on adenylate energy charge in penaeid shrimp

    Directory of Open Access Journals (Sweden)

    Robles-Romo Arlett

    2014-01-01

    Full Text Available Adenylate energy charge (AEC has been used as a practical index of the physiological status and health in several disciplines, such as ecotoxicology and aquaculture. This study standardizes several procedures for AEC determination in penaeid shrimp that are very sensitive to sampling. We concluded that shrimp can be frozen in liquid nitrogen and then stored at -76°C for up to two years for further analysis, or freshly dissected and immediately homogenized in acid. Other cooling procedures, such as immersion in cold water or placing shrimp on ice for 15 min resulted in 50% and 73% decreases in ATP levels, and 9-fold and 10-fold increases in IMP levels, respectively. Optimal values of AEC (0.9 were obtained in shrimp recently transferred from ponds to indoor conditions, but decreased to 0.77 after one month in indoor tanks when stocked at high densities; the AEC re-established to 0.85 when the shrimps were transferred to optimal conditions (lower density and dark tanks. While the levels of arginine phosphate followed the same pattern, its levels did not fully re-establish. Comparison of different devices for sample homogenization indicated that a cryogenic ball mill mixer is the more suitable procedure.

  12. Optimization of a miniaturized DBD plasma chip for mercury detection in water samples.

    Science.gov (United States)

    Abdul-Majeed, Wameath S; Parada, Jaime H Lozano; Zimmerman, William B

    2011-11-01

    In this work, an optimization study was conducted to investigate the performance of a custom-designed miniaturized dielectric barrier discharge (DBD) microplasma chip to be utilized as a radiation source for mercury determination in water samples. The experimental work was implemented by using experimental design, and the results were assessed by applying statistical techniques. The proposed DBD chip was designed and fabricated in a simple way by using a few microscope glass slides aligned together and held by a Perspex chip holder, which proved useful for miniaturization purposes. Argon gas at 75-180 mL/min was used in the experiments as a discharge gas, while AC power in the range 75-175 W at 38 kHz was supplied to the load from a custom-made power source. A UV-visible spectrometer was used, and the spectroscopic parameters were optimized thoroughly and applied in the later analysis. Plasma characteristics were determined theoretically by analysing the recorded spectroscopic data. The estimated electron temperature (T(e) = 0.849 eV) was found to be higher than the excitation temperature (T(exc) = 0.55 eV) and the rotational temperature (T(rot) = 0.064 eV), which indicates non-thermal plasma is generated in the proposed chip. Mercury cold vapour generation experiments were conducted according to experimental plan by examining four parameters (HCl and SnCl(2) concentrations, argon flow rate, and the applied power) and considering the recorded intensity for the mercury line (253.65 nm) as the objective function. Furthermore, an optimization technique and statistical approaches were applied to investigate the individual and interaction effects of the tested parameters on the system performance. The calculated analytical figures of merit (LOD = 2.8 μg/L and RSD = 3.5%) indicates a reasonable precision system to be adopted as a basis for a miniaturized portable device for mercury detection in water samples.

  13. Development of a sample preparation procedure for the simultaneous determination of Np and Pu in clay samples

    Energy Technology Data Exchange (ETDEWEB)

    Renz, Tobias; Quinto, Francesca; Lagos, Markus; Plaschke, Markus; Bauer, Andreas; Geckeis, Horst [INE, KIT, Eggenstein-Leopoldshafen (Germany); Taubald, Heinrich [Eberhard Karls Universitaet, Tuebingen (Germany)

    2015-07-01

    Neptunium (Np) and plutonium (Pu) are two key radionuclides for the long-term disposal of nuclear waste. Within this context Opalinus Clay formations are considered as a potential location for disposal of high-level radioactive waste. In the framework of experiments studying the diffusion behavior and retention of actinides under repository conditions, the present work focuses on the development of an analytical-chemical procedure for the determination of Np and Pu in clay (or clay-rich soil) samples. The procedure aims at the simultaneous determination of Np and Pu at femto- to attogram levels with AMS. Fields of application are the investigation of global fallout actinides in environmental clay-rich samples or the diffusion behavior of actinides in compacted clay liners used as technical barriers in nuclear waste repositories. Clay samples are spiked with certified standards of Pu-242 and Np-237. The analytical method, including a) leaching of the spiked clay samples, b) redox adjustments of Np and Pu, c) chromatographic separation of Np and Pu from the sample matrix and d) measurement of the actinides with Sector Field (SF)-ICP-MS will be presented. The suitability of a Pu isotope as non-isotopic tracer for determination of Np-237 is evaluated by determining the chemical yield using SF-ICP-MS.

  14. Reproducibility of NMR Analysis of Urine Samples: Impact of Sample Preparation, Storage Conditions, and Animal Health Status

    Directory of Open Access Journals (Sweden)

    Christina Schreier

    2013-01-01

    Full Text Available Introduction. Spectroscopic analysis of urine samples from laboratory animals can be used to predict the efficacy and side effects of drugs. This employs methods combining 1H NMR spectroscopy with quantification of biomarkers or with multivariate data analysis. The most critical steps in data evaluation are analytical reproducibility of NMR data (collection, storage, and processing and the health status of the animals, which may influence urine pH and osmolarity. Methods. We treated rats with a solvent, a diuretic, or a nephrotoxicant and collected urine samples. Samples were titrated to pH 3 to 9, or salt concentrations increased up to 20-fold. The effects of storage conditions and freeze-thaw cycles were monitored. Selected metabolites and multivariate data analysis were evaluated after 1H NMR spectroscopy. Results. We showed that variation of pH from 3 to 9 and increases in osmolarity up to 6-fold had no effect on the quantification of the metabolites or on multivariate data analysis. Storage led to changes after 14 days at 4°C or after 12 months at −20°C, independent of sample composition. Multiple freeze-thaw cycles did not affect data analysis. Conclusion. Reproducibility of NMR measurements is not dependent on sample composition under physiological or pathological conditions.

  15. Reproducibility of NMR analysis of urine samples: impact of sample preparation, storage conditions, and animal health status.

    Science.gov (United States)

    Schreier, Christina; Kremer, Werner; Huber, Fritz; Neumann, Sindy; Pagel, Philipp; Lienemann, Kai; Pestel, Sabine

    2013-01-01

    Spectroscopic analysis of urine samples from laboratory animals can be used to predict the efficacy and side effects of drugs. This employs methods combining (1)H NMR spectroscopy with quantification of biomarkers or with multivariate data analysis. The most critical steps in data evaluation are analytical reproducibility of NMR data (collection, storage, and processing) and the health status of the animals, which may influence urine pH and osmolarity. We treated rats with a solvent, a diuretic, or a nephrotoxicant and collected urine samples. Samples were titrated to pH 3 to 9, or salt concentrations increased up to 20-fold. The effects of storage conditions and freeze-thaw cycles were monitored. Selected metabolites and multivariate data analysis were evaluated after (1)H NMR spectroscopy. We showed that variation of pH from 3 to 9 and increases in osmolarity up to 6-fold had no effect on the quantification of the metabolites or on multivariate data analysis. Storage led to changes after 14 days at 4°C or after 12 months at -20°C, independent of sample composition. Multiple freeze-thaw cycles did not affect data analysis. Reproducibility of NMR measurements is not dependent on sample composition under physiological or pathological conditions.

  16. Automated Sample Preparation for Radiogenic and Non-Traditional Metal Isotopes: Removing an Analytical Barrier for High Sample Throughput

    Science.gov (United States)

    Field, M. Paul; Romaniello, Stephen; Gordon, Gwyneth W.; Anbar, Ariel D.; Herrmann, Achim; Martinez-Boti, Miguel A.; Anagnostou, Eleni; Foster, Gavin L.

    2014-05-01

    MC-ICP-MS has dramatically improved the analytical throughput for high-precision radiogenic and non-traditional isotope ratio measurements, compared to TIMS. The generation of large data sets, however, remains hampered by tedious manual drip chromatography required for sample purification. A new, automated chromatography system reduces the laboratory bottle neck and expands the utility of high-precision isotope analyses in applications where large data sets are required: geochemistry, forensic anthropology, nuclear forensics, medical research and food authentication. We have developed protocols to automate ion exchange purification for several isotopic systems (B, Ca, Fe, Cu, Zn, Sr, Cd, Pb and U) using the new prepFAST-MC™ (ESI, Nebraska, Omaha). The system is not only inert (all-flouropolymer flow paths), but is also very flexible and can easily facilitate different resins, samples, and reagent types. When programmed, precise and accurate user defined volumes and flow rates are implemented to automatically load samples, wash the column, condition the column and elute fractions. Unattended, the automated, low-pressure ion exchange chromatography system can process up to 60 samples overnight. Excellent reproducibility, reliability, recovery, with low blank and carry over for samples in a variety of different matrices, have been demonstrated to give accurate and precise isotopic ratios within analytical error for several isotopic systems (B, Ca, Fe, Cu, Zn, Sr, Cd, Pb and U). This illustrates the potential of the new prepFAST-MC™ (ESI, Nebraska, Omaha) as a powerful tool in radiogenic and non-traditional isotope research.

  17. Preparation optimization and spectral properties of BCNO phosphors with high quantum efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Chunrong; Zhang, Xinghua, E-mail: xinghua146@126.com; Zhou, Liyu; Lu, Zunming; Lin, Jing; Xu, Xuewen; Li, Lanlan; Zhang, Xiao; Xue, Yanming; Meng, Fanbin; Zhao, Jianling; Tang, Chengchun, E-mail: tangcc@hebut.edu.cn

    2014-09-15

    BCNO phosphors with high quantum efficiency (QE) were synthesized using trimethyl borate, melamine and urotropine as raw materials. The effects of urotropine, starting materials ratio, sintering time and temperature on luminescence properties were systematically investigated and the preparation conditions were optimized. The BCNO phosphor has turbostratic boron nitride structure and its size in the range of several millimeters. The emission peak position was not influenced by the content of urotropine. However, the emission peak blue can be tuned from 475 nm to 535 nm with increasing B/N source ratios (R{sub B/N}=2–6), while the QE decreased from 65.2% to 15.8%. The emission peaks of BCNO phosphor with R{sub B/N}=4 were in the range of green light (495–540 nm) with high QE (20.8–51.4%) as sintering time increased (4–20 h). In addition, the emission peaks of BCNO phosphor with R{sub B/N}=4 blue-shifted from 525 nm to 460 nm and increased QE (16.1–56.7%) with increasing sintering temperature (650–750 °C). The formation mechanism of BCNO phosphors was investigated by means of ultraviolet visible absorption spectra and infrared spectra. The tunable emission spectra and high QE corresponded to the chemical composition, carbon concentration and crystallinity of BCNO phosphors. - Highlights: • We prepared BCNO phosphors with high quantum efficiency (65.2%). • The effects of raw materials, sintering condition on spectral properties were investigated. • The formation and luminescence mechanism of BCNO phosphors were investigated.

  18. Preparation of cationized pine sawdust for nitrate removal: Optimization of reaction conditions.

    Science.gov (United States)

    Keränen, Anni; Leiviskä, Tiina; Hormi, Osmo; Tanskanen, Juha

    2015-09-01

    Anion exchange materials were prepared from pine sawdust (Pinus sylvestris, PSD) through cationizing treatment with N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHMAC) in the presence of NaOH. Response surface methodology (RSM) was used to find the optimal reaction conditions. Three factors were chosen: reaction temperature (26-94 °C), reaction time (0.32-3.7 h) and NaOH/CHMAC molar ratio (0.19-2.2). Product yield (%) was used as a response. A quadratic model was fitted to the experimental data. The optimal conditions were: a reaction temperature of 57 °C, a reaction time of 1.8 h and a NaOH/CHMAC molar ratio of 1.32. A maximum nitrogen content of 2.6% was obtained at 60 °C, 3.7 h and a molar ratio of 1.2. The molar ratio had the greatest impact on the response. Regression analysis revealed that over 95% of the variance can be explained by the model. A maximum nitrate sorption capacity of 15.3 ± 1.4 mg N/g was achieved. The effect of CHMAC dose was also studied (a NaOH/CHMAC molar ratio of 1.2): 0.064 mol/g PSD was found to be near the optimum. Nitrate-contaminated groundwater (27.5 mg/l NO3) was treated with CPSD. Doses of 3-6 g/l resulted in 59-71% nitrate reduction.

  19. Optimization of a Pre-MEKC Separation SPE Procedure for Steroid Molecules in Human Urine Samples

    Directory of Open Access Journals (Sweden)

    Ilona Olędzka

    2013-11-01

    Full Text Available Many steroid hormones can be considered as potential biomarkers and their determination in body fluids can create opportunities for the rapid diagnosis of many diseases and disorders of the human body. Most existing methods for the determination of steroids are usually time- and labor-consuming and quite costly. Therefore, the aim of analytical laboratories is to develop a new, relatively low-cost and rapid implementation methodology for their determination in biological samples. Due to the fact that there is little literature data on concentrations of steroid hormones in urine samples, we have made attempts at the electrophoretic determination of these compounds. For this purpose, an extraction procedure for the optimized separation and simultaneous determination of seven steroid hormones in urine samples has been investigated. The isolation of analytes from biological samples was performed by liquid-liquid extraction (LLE with dichloromethane and compared to solid phase extraction (SPE with C18 and hydrophilic-lipophilic balance (HLB columns. To separate all the analytes a micellar electrokinetic capillary chromatography (MECK technique was employed. For full separation of all the analytes a running buffer (pH 9.2, composed of 10 mM sodium tetraborate decahydrate (borax, 50 mM sodium dodecyl sulfate (SDS, and 10% methanol was selected. The methodology developed in this work for the determination of steroid hormones meets all the requirements of analytical methods. The applicability of the method has been confirmed for the analysis of urine samples collected from volunteers—both men and women (students, amateur bodybuilders, using and not applying steroid doping. The data obtained during this work can be successfully used for further research on the determination of steroid hormones in urine samples.

  20. Inverse supercritical fluid extraction as a sample preparation method for the analysis of the nanoparticle content in sunscreen agents.

    Science.gov (United States)

    Müller, David; Cattaneo, Stefano; Meier, Florian; Welz, Roland; de Vries, Tjerk; Portugal-Cohen, Meital; Antonio, Diana C; Cascio, Claudia; Calzolai, Luigi; Gilliland, Douglas; de Mello, Andrew

    2016-04-01

    We demonstrate the use of inverse supercritical carbon dioxide (scCO2) extraction as a novel method of sample preparation for the analysis of complex nanoparticle-containing samples, in our case a model sunscreen agent with titanium dioxide nanoparticles. The sample was prepared for analysis in a simplified process using a lab scale supercritical fluid extraction system. The residual material was easily dispersed in an aqueous solution and analyzed by Asymmetrical Flow Field-Flow Fractionation (AF4) hyphenated with UV- and Multi-Angle Light Scattering detection. The obtained results allowed an unambiguous determination of the presence of nanoparticles within the sample, with almost no background from the matrix itself, and showed that the size distribution of the nanoparticles is essentially maintained. These results are especially relevant in view of recently introduced regulatory requirements concerning the labeling of nanoparticle-containing products. The novel sample preparation method is potentially applicable to commercial sunscreens or other emulsion-based cosmetic products and has important ecological advantages over currently used sample preparation techniques involving organic solvents.

  1. Recent advances in metal-organic frameworks and covalent organic frameworks for sample preparation and chromatographic analysis.

    Science.gov (United States)

    Wang, Xuan; Ye, Nengsheng

    2017-09-04

    In the field of analytical chemistry, sample preparation and chromatographic separation are two core procedures. The means by which to improve the sensitivity, selectivity and detection limit of a method have become a topic of great interest. Recently, porous organic frameworks, such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely used in this research area because of their special features, and different methods have been developed. This review summarizes the applications of MOFs and COFs in sample preparation and chromatographic stationary phases. The MOF- or COF-based solid-phase extraction (SPE), solid-phase microextraction (SPME), gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) methods are described. The excellent properties of MOFs and COFs have resulted in intense interest in exploring their performance and mechanisms for sample preparation and chromatographic separation. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Preparation

    Directory of Open Access Journals (Sweden)

    M.M. Dardir

    2014-03-01

    Full Text Available Some hexanamide-mono and di-linoleniate esters were prepared by the reaction of linolenic acid and hexanamide (derived from the reaction of hexanoic acid and diethanolamine. The chemical structure for the newly prepared hexanamide-mono and di-linoleniate esters were elucidated using elemental analysis, (FTIR, H 1NMR and chemical ionization mass spectra (CI/Ms spectroscopic techniques. The results of the spectroscopic analysis indicated that they were prepared through the right method and they have high purity. The new prepared esters have high biodegradability and lower toxicity (environmentally friendly so they were evaluated as a synthetic-based mud (ester-based mud for oil-well drilling fluids. The evaluation included study of the rheological properties, filtration and thermal properties of the ester based-muds formulated with the newly prepared esters compared to the reference commercial synthetic-based mud.

  3. Optimized measurement of radium-226 concentration in liquid samples with radon-222 emanation.

    Science.gov (United States)

    Perrier, Frédéric; Aupiais, Jean; Girault, Frédéric; Przylibski, Tadeusz A; Bouquerel, Hélène

    2016-06-01

    Measuring radium-226 concentration in liquid samples using radon-222 emanation remains competitive with techniques such as liquid scintillation, alpha or mass spectrometry. Indeed, we show that high-precision can be obtained without air circulation, using an optimal air to liquid volume ratio and moderate heating. Cost-effective and efficient measurement of radon concentration is achieved by scintillation flasks and sufficiently long counting times for signal and background. More than 400 such measurements were performed, including 39 dilution experiments, a successful blind measurement of six reference test solutions, and more than 110 repeated measurements. Under optimal conditions, uncertainties reach 5% for an activity concentration of 100 mBq L(-1) and 10% for 10 mBq L(-1). While the theoretical detection limit predicted by Monte Carlo simulation is around 3 mBq L(-1), a conservative experimental estimate is rather 5 mBq L(-1), corresponding to 0.14 fg g(-1). The method was applied to 47 natural waters, 51 commercial waters, and 17 wine samples, illustrating that it could be an option for liquids that cannot be easily measured by other methods. Counting of scintillation flasks can be done in remote locations in absence of electricity supply, using a solar panel. Thus, this portable method, which has demonstrated sufficient accuracy for numerous natural liquids, could be useful in geological and environmental problems, with the additional benefit that it can be applied in isolated locations and in circumstances when samples cannot be transported.

  4. Transmission Electron Microscopy (TEM) Sample Preparation of Si(1-x)Gex in c-Plane Sapphire Substrate

    Science.gov (United States)

    Kim, Hyun Jung; Choi, Sang H.; Bae, Hyung-Bin; Lee, Tae Woo

    2012-01-01

    The National Aeronautics and Space Administration-invented X-ray diffraction (XRD) methods, including the total defect density measurement method and the spatial wafer mapping method, have confirmed super hetero epitaxy growth for rhombohedral single crystalline silicon germanium (Si1-xGex) on a c-plane sapphire substrate. However, the XRD method cannot observe the surface morphology or roughness because of the method s limited resolution. Therefore the authors used transmission electron microscopy (TEM) with samples prepared in two ways, the focused ion beam (FIB) method and the tripod method to study the structure between Si1-xGex and sapphire substrate and Si1?xGex itself. The sample preparation for TEM should be as fast as possible so that the sample should contain few or no artifacts induced by the preparation. The standard sample preparation method of mechanical polishing often requires a relatively long ion milling time (several hours), which increases the probability of inducing defects into the sample. The TEM sampling of the Si1-xGex on sapphire is also difficult because of the sapphire s high hardness and mechanical instability. The FIB method and the tripod method eliminate both problems when performing a cross-section TEM sampling of Si1-xGex on c-plane sapphire, which shows the surface morphology, the interface between film and substrate, and the crystal structure of the film. This paper explains the FIB sampling method and the tripod sampling method, and why sampling Si1-xGex, on a sapphire substrate with TEM, is necessary.

  5. Comparison of green sample preparation techniques in the analysis of pyrethrins and pyrethroids in baby food by liquid chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Petrarca, Mateus Henrique; Ccanccapa-Cartagena, Alexander; Masiá, Ana; Godoy, Helena Teixeira; Picó, Yolanda

    2017-05-12

    A new selective and sensitive liquid chromatography triple quadrupole mass spectrometry method was developed for simultaneous analysis of natural pyrethrins and synthetic pyrethroids residues in baby food. In this study, two sample preparation methods based on ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and salting-out assisted liquid-liquid extraction (SALLE) were optimized, and then, compared regarding the performance criteria. Appropriate linearity in solvent and matrix-based calibrations, and suitable recoveries (75-120%) and precision (RSD values≤16%) were achieved for selected analytes by any of the sample preparation procedures. Both methods provided the analytical selectivity required for the monitoring of the insecticides in fruit-, cereal- and milk-based baby foods. SALLE, recognized by cost-effectiveness, and simple and fast execution, provided a lower enrichment factor, consequently, higher limits of quantification (LOQs) were obtained. Some of them too high to meet the strict legislation regarding baby food. Nonetheless, the combination of ultrasound and DLLME also resulted in a high sample throughput and environmental-friendly method, whose LOQs were lower than the default maximum residue limit (MRL) of 10μgkg(-1) set by European Community for baby foods. In the commercial baby foods analyzed, cyhalothrin and etofenprox were detected in different samples, demonstrating the suitability of proposed method for baby food control. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Bovine liver sample preparation and micro-homogeneity study for Cu and Zn determination by solid sampling electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Cassiana S. [Instituto de Quimica, Universidade de Sao Paulo, CP 26077, Sao Paulo, SP 05513-970 (Brazil); Silva, Cintia S. [Instituto de Quimica, Universidade de Sao Paulo, CP 26077, Sao Paulo, SP 05513-970 (Brazil); Nogueira, Ana R.A. [Embrapa Pecuaria Sudeste, CP 339, Sao Carlos, SP 13560-970 (Brazil); Oliveira, Pedro V. [Instituto de Quimica, Universidade de Sao Paulo, CP 26077, Sao Paulo, SP 05513-970 (Brazil)]. E-mail: pvolivei@iq.usp.br

    2005-06-30

    This work describes a systematic study for the bovine liver sample preparation for Cu and Zn determination by solid sampling electrothermal atomic absorption spectrometry. The main parameters investigated were sample drying, grinding process, particle size, sample size, microsample homogeneity, and their relationship with the precision and accuracy of the method. A bovine liver sample was prepared using different drying procedures: (1) freeze drying, and (2) drying in a household microwave oven followed by drying in a stove at 60 deg. C until constant mass. Ball and cryogenic mills were used for grinding. Less sensitive wavelengths for Cu (216.5 nm) and Zn (307.6 nm), and Zeeman-based three-field background correction for Cu were used to diminish the sensitivities. The pyrolysis and atomization temperatures adopted were 1000 deg. C and 2300 deg. C for Cu, and 700 deg. C and 1700 deg. C for Zn, respectively. For both elements, it was possible to calibrate the spectrometer with aqueous solutions. The use of 250 {mu}g of W + 200 {mu}g of Rh as permanent chemical modifier was imperative for Zn. Under these conditions, the characteristic mass and detection limit were 1.4 ng and 1.6 ng for Cu, and 2.8 ng and 1.3 ng for Zn, respectively. The results showed good agreement (95% confidence level) for homogeneity of the entire material (> 200 mg) when the sample was dried in microwave/stove and ground in a cryogenic mill. The microsample homogeneity study showed that Zn is more dependent on the sample pretreatment than Cu. The bovine liver sample prepared in microwave/stove and ground in a cryogenic mill presented results with the lowest relative standard deviation for Cu than Zn. Good accuracy and precision were observed for bovine liver masses higher than 40 {mu}g for Cu and 30 {mu}g for Zn. The concentrations of Cu and Zn in the prepared bovine liver sample were 223 mg kg{sup -} {sup 1} and 128 mg kg{sup -} {sup 1}, respectively. The relative standard deviations were lower

  7. Thermally Sprayed Large Tubular Solid Oxide Fuel Cells and Its Stack: Geometry Optimization, Preparation, and Performance

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Liu, Shuai; Li, Chang-Jiu; Yang, Guan-Jun; He, Peng-Jiang; Yun, Liang-Liang; Song, Bo; Xie, Ying-Xin

    2017-02-01

    In this study, we develop a large tubular solid oxide fuel cells design with several cells in series on a porous cermet support, which has many characteristics such as self-sealing, low Ohmic loss, high strength, and good thermal expansion coefficient matching. Here, we investigate aspects of the cell design, manufacture, performance, and application. Firstly, the cell length and number of cells in series are optimized by theoretical analysis. Then, thermal spraying is applied as a cost-effective method to prepare all the cell components. Finally, the performance of different types of cells and two types of stacks is characterized. The maximum output power of one tube, which had 20 cells in series, reaches 31 and 40.5 W at 800 and 900 °C, respectively. Moreover, the output power of a stack assembled with 56 tubes, each with ten cells in series, reaches 800 W at 830 °C. The excellent single tube and cell stack performance suggest that thermally sprayed tubular SOFCs have significant potential for commercialized application.

  8. Thermally Sprayed Large Tubular Solid Oxide Fuel Cells and Its Stack: Geometry Optimization, Preparation, and Performance

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Liu, Shuai; Li, Chang-Jiu; Yang, Guan-Jun; He, Peng-Jiang; Yun, Liang-Liang; Song, Bo; Xie, Ying-Xin

    2017-01-01

    In this study, we develop a large tubular solid oxide fuel cells design with several cells in series on a porous cermet support, which has many characteristics such as self-sealing, low Ohmic loss, high strength, and good thermal expansion coefficient matching. Here, we investigate aspects of the cell design, manufacture, performance, and application. Firstly, the cell length and number of cells in series are optimized by theoretical analysis. Then, thermal spraying is applied as a cost-effective method to prepare all the cell components. Finally, the performance of different types of cells and two types of stacks is characterized. The maximum output power of one tube, which had 20 cells in series, reaches 31 and 40.5 W at 800 and 900 °C, respectively. Moreover, the output power of a stack assembled with 56 tubes, each with ten cells in series, reaches 800 W at 830 °C. The excellent single tube and cell stack performance suggest that thermally sprayed tubular SOFCs have significant potential for commercialized application.

  9. Optimized extract preparation methods and reaction conditions for improved yeast cell-free protein synthesis.

    Science.gov (United States)

    Hodgman, C Eric; Jewett, Michael C

    2013-10-01

    Cell-free protein synthesis (CFPS) has emerged as a powerful platform technology to help satisfy the growing demand for simple, affordable, and efficient protein production. In this article, we describe a novel CFPS platform derived from the popular bio-manufacturing organism Saccharomyces cerevisiae. By developing a streamlined crude extract preparation protocol and optimizing the CFPS reaction conditions we were able to achieve active firefly luciferase synthesis yields of 7.7 ± 0.5 µg mL(-1) with batch reactions lasting up to 2 h. This duration of synthesis is the longest ever reported for a yeast CFPS batch reaction. Furthermore, by removing extraneous processing steps and eliminating expensive reagents from the cell-free reaction, we have increased relative product yield (µg protein synthesized per $ reagent cost) over an alternative commonly used method up to 2000-fold from ∼2 × 10(-4) to ∼4 × 10(-1)  µg $(-1) , which now puts the yeast CPFS platform on par with other eukaryotic CFPS platforms commercially available. Our results set the stage for developing a yeast CFPS platform that provides for high-yielding and cost-effective expression of a variety of protein therapeutics and protein libraries.

  10. Recovery of Salmonella from internally and externally contaminated whole tomatoes using several different sample preparation procedures.

    Science.gov (United States)

    Wang, Hua; Gill, Vikas S; Irvin, Kari A; Byrd, Mindi; Bolger, Cathryn M; Zheng, Jie; Dickey, Erin E; Duvall, Robert E; Jacobson, Andrew P; Hammack, Thomas S

    2012-01-01

    Studies were conducted to determine the relative effectiveness of whole soak [current Bacteriological Analytical Manual-(BAM) Salmonella method], quarter, stomach, and blend methods for the recovery of Salmonella organisms from internally and externally contaminated tomatoes. Tomatoes were subjected to three inoculation methods: surface inoculation, internal inoculation by injection, and immersion with single Salmonella serovars. The inoculation levels ranged from 1 to 100 CFU/tomato for surface and injection inoculation or 1 to 100 CFU/mL for immersion inoculation. Tomatoes were held for 3 days after inoculation at 2-6 degrees C prior to initiation of analysis. Contaminated tomatoes were soaked, quartered, stomached, and blended in appropriate portions of Universal Pre-enrichment broth, and incubated for 24 h at 35 +/- 2 degrees C. The BAM Salmonella culture method was followed thereafter, and tomatoes were treated as a low-microbial-load food. The stomaching procedure was significantly (P < 0.05) more effective than the whole soak procedure for recovery of internalized Salmonella from tomatoes (by injection). The blending procedure was arithmetically superior to the stomaching procedure for detection of internalized Salmonella from tomatoes (by immersion). The blending procedure showed the same effectiveness as the whole soak procedure for the detection of Salmonella on tomato surfaces. Comparisons between test portion-to-broth ratios (weight to volume) showed that a 1:3 test portion-to-broth ratio had a better buffering capacity for blended tomatoes than a 1:1 test portion-to-broth ratio. It is recommended that the current whole soak BAM tomato sample preparation procedure be replaced with a blending procedure and a 1:3 test portion-to-broth ratio.

  11. Preparative chromatography for specific δ13C isotopic analysis of individual carbohydrates in environmental samples

    Science.gov (United States)

    Nouara, Amel; Panagiotopoulos, Christos; Balesdent, Jérôme; Sempéré, Richard

    2017-04-01

    Carbohydrates are among the most abundant organic molecules on the Earth and are present in all geochemical systems. Despite their high abundance in the environment, very few studies assessed their origin using molecular carbohydrate isotopic analyses. In contrast with bulk stable isotope analysis (BSIA), which gives the isotopic signature of the entire sample without any specification about its chemical composition, compound specific 13C isotopic analysis of individual sugars (CSIA) offers valuable information about the origin of single molecules. Previous investigations used gas or liquid chromatography coupled with isotope ratio mass spectroscopy (GC-IRMS; HPLC-IRMS) for CSIA of sugars however the former requires δ13C corrections due to the carbon added to the sugar (derivatization) while the later does not provide always adequate separations among monosaccharides. Here we used cation preparative chromatography (Ca2+, Pb2+ and Na+) with refractive index detection in order to produce pure monosaccharide targets for subsequent EA-IRMS analyses. Milli-Q water was used as eluant at a flow rate 0.6 ml min-1. In general, three successive purifications (Ca2+, Pb2+, Ca2+) were sufficient to produce pure compounds. Pure monosaccharides were compared with authentic monosaccharide standards using 1H NMR and/or mass spectroscopy. The detection limit of our technique was about 1µM/sugar with a precision of 10% (n=6). Blanks run with Milli-Q water after three successive purifications resulted in carbon content of 0.13 to 2.77 µgC per collected sugar. These values are much lower than the minimum required amount (5 µgC) of the EA-IRSMS system with a precision of ± 0.35 ‰. Application of our method to environmental samples resulted in δ13C values of glucose, fructose, and levoglucosan in the range of -24 to -26 ‰ (PM10 atmospheric particles), and -15‰ to -22 ‰ for arabinose, glucose, and xylose (marine high molecular dissolved organic matter). These results fall in

  12. Optimizing EUS-guided liver biopsy sampling: comprehensive assessment of needle types and tissue acquisition techniques.

    Science.gov (United States)

    Schulman, Allison R; Thompson, Christopher C; Odze, Robert; Chan, Walter W; Ryou, Marvin

    2017-02-01

    EUS-guided liver biopsy sampling using FNA and, more recently, fine-needle biopsy (FNB) needles has been reported with discrepant diagnostic accuracy, in part due to differences in methodology. We aimed to compare liver histologic yields of 4 EUS-based needles and 2 percutaneous needles to identify optimal number of needle passes and suction. Six needle types were tested on human cadaveric tissue: one 19G FNA needle, one existing 19G FNB needle, one novel 19G FNB needle, one 22G FNB needle, and two 18G percutaneous needles (18G1 and 18G2). Two needle excursion patterns (1 vs 3 fanning passes) were performed on all EUS needles. Primary outcome was number of portal tracts. Secondary outcomes were degree of fragmentation and specimen adequacy. Pairwise comparisons were performed using t tests, with a 2-sided P samplings (48 per needle type) were performed. The novel 19G FNB needle had significantly increased mean portal tracts compared with all needle types. The 22G FNB needle had significantly increased portal tracts compared with the 18G1 needle (3.8 vs 2.5, P sampling. Investigations are underway to determine whether these results can be replicated in a clinical setting. Copyright © 2017 American Societ