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Extraction System (extraction + system)

Distribution by Scientific Domains

Chemistry	47%
Medical Sciences	15%
Life Sciences	15%

Selected Abstracts

A comparison of molecular methods for the routine detection of viroids,

EPPO BULLETIN, Issue 3-4 2000
R. A. Mumford
Viroids, such as Chrysanthemum stunt viroid (CSVd) and Potato spindle tuber viroid (PSTVd), are important plant pathogens. However, because of their unique biological properties, viroids have proved, in the past, difficult to diagnose. The use of molecular methods has now changed this and this paper reports the comparison of three such methods (dot-blot hybridization using DIG-labelled cRNA probes, reverse transcription-polymerase chain reaction (RT-PCR) and TaqMan), which have been developed for routine detection of CSVd. Sensitivity comparisons show that the TaqMan assay is more sensitive than either RT-PCR (100 times) and hybridization (1000 times). RT-PCR and TaqMan assays have also been developed to detect PSTVd. In addition to the development of sensitive detection methods, considerable emphasis has been placed on making these assays amenable to mass-scale detection through the use of internal controls and the development of a rapid, reliable probe capture extraction system. [source]

The Use of N -Type Ligands in the Enantioselective Liquid,Liquid Extraction of Underivatized Amino Acids

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2010
Bastiaan J. V. Verkuijl
Abstract The first palladium based extraction system using chiral N -based ligands in the enantioselective liquid,liquid extraction (ELLE) of underivatized amino acids, is presented. The system shows the highest selectivity for the ELLE of methionine with metal complexes as hosts reported to date. Furthermore, the host can be prepared in situ from commercially available compounds. The dependency of the system on parameters such as pH, organic solvent, and temperature has been established. The intrinsic selectivity was deduced by determination of the association constants of the palladium complex with the tryptophan enantiomers. [source]

A selective and sensitive approach to characterize odour-active and volatile constituents in small-scale human milk samples

FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2007
Andrea Buettner
Abstract A sensitive and selective analytical approach was developed for the characterization of trace volatile and odorous substances in body fluids. The methodology was successfully applied for identification of more than 40 characteristic odorants in human milk. The technique comprises a modified stir bar sorptive extraction system in combination with two-dimensional gas chromatographic separation and parallel mass spectrometric and olfactometric characterization of the analytes. The present study shows that the technique can be used for both direct extractive sampling and headspace analysis, and that it is applicable for small sample volumes. Copyright © 2007 John Wiley & Sons, Ltd. [source]

EXTRACTION YIELD OF SOLUBLE PROTEIN AND MICROSTRUCTURE OF SOYBEAN AFFECTED BY MICROWAVE HEATING

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 4 2006
IL CHOI
ABSTRACT A laboratory-scale microwave (MW)-assisted extraction system was constructed and compared with a conventional shaking water bath regarding the extraction of soluble proteins in soybeans. Dynamic reaction was monitored by response surface methodology in the MW-assisted extraction system. The yield of soluble protein increased until either temperature (T) or water/solid (W/S) ratio reached an optimum point (60.1C, 12.6 mL/g), and then decreased with further increase of T or W/S ratio. In addition, the yield of soluble protein increased with time within a range of 30 min, and no critical point was observed. The molecular mass of soluble protein was distributed from 19.3 to 81.3 kDa estimated by sodium dodecyl sulfate,polyacrylamide gel electrophoresis. Scanning electron microscopy showed the destruction of the microstructure of soybean cells, which increased the extraction of soluble soy protein. [source]

Modeling of extraction behavior of docosahexaenoic acid ethyl ester by utilizing slug flow prepared by microreactor

AICHE JOURNAL, Issue 8 2010
Eiji Kamio
Abstract The liquid,liquid extraction dynamics of an ethyl ester of docosahexaenoic acid (DHA-Et) with silver ion was investigated. The kinetic model was derived according to the following stepwise processes: Diffusion of DHA-Et across the organic film, complex-formation between DHA-Et and silver ion at the interface, and diffusion of extracted complex across the aqueous film. The kinetic parameters for the complex-formation reaction were determined from the investigation with the stirred transfer cell. With the proposed model and determined parameters, we predicted the uptakes of DHA-Et for the extraction system utilizing a slug flow prepared by a microchip. The calculated uptakes showed good correlation to the experimental data. The theoretical investigation suggested that the fast equilibration realized for the slug flow extraction system was due to the large specific interfacial area of the slug caused by the presence of wall film and the thin liquid film caused by the internal circulation. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source]

Ion-pair mediated transport of small model peptides in liquid phase micro extraction under acidic conditions

JOURNAL OF SEPARATION SCIENCE, JSS, Issue 3 2005
J. Léon E. Reubsaet
Abstract This paper discusses the behaviour of five small model peptides in a three phase (aqueous donor-organic-aqueous acceptor) liquid phase micro extraction system in relation to their physico-chemical properties (charge, hydrophobicity). It is proved that for all peptides transport over the organic phase is mediated by aliphatic sulphonic acids. Heptane-1-sulphonic acid gave the best overall recoveries. It appeared that peptides with hydrophobic properties (IPI) and a high number of positive charges (KYK) show good recoveries and are enriched in the acceptor phase. Variation in the pH (1.6,4.4) of the donor phase shows that there are peptide-dependent optimal pH-values for their recovery. Increasing pH in the acceptor phase shows that in most cases the recovery decreases due to decreased ion-pair mediated membrane transport. For KYK the partition between the organic phase and the aqueous acceptor-phase is also driven by the solubility in the aqueous acceptor phase. Increase of the ion strength of the acceptor phase did not affect the recovery of the peptides. Except for KYK, which showed decreased recovery when the ion strength increased. Another finding is that delocalisation of positive charge causes bad recovery, probably due to incomplete ion-pair-peptide complex formation. [source]

Assessing the value of an e-mail knowledge extraction system

KNOWLEDGE AND PROCESS MANAGEMENT: THE JOURNAL OF CORPORATE TRANSFORMATION, Issue 2 2009
Sara Tedmori
This paper reviews an approach to locating knowledge holders within organizations through the use of a well-established communication medium, E-mail. The approach has been used to develop the E-mail knowledge extraction (EKE) tool. EKE was then evaluated at an academic institution in the United Kingdom. This study represents the first effort to validate the viability of the E-mail medium as a source of knowledge profiling data, to be used for finding employees who possess the required knowledge. It also looks at the socio,ethical challenges associated with EKE's adoption. The overall evaluation of EKE found it to be useful, interesting, easy and intuitive to use and of potential benefit to employees within organizations. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Locating knowledge sources through keyphrase extraction

KNOWLEDGE AND PROCESS MANAGEMENT: THE JOURNAL OF CORPORATE TRANSFORMATION, Issue 2 2006
Sara Tedmori
There are a large number of tasks for which keyphrases can be useful. Manually identifying keyphrases can be a tedious and time consuming process that requires expertise, but if automated could save time and aid in creating metadata that could be used to locate knowledge sources. In this paper, the authors present an automated process for keyphrase extraction from e-mail messages. The process enables users to find other people who might hold the knowledge they require from information communicated via the e-mail system. The effectiveness of the extraction system is tested and compared against other extraction systems and the overall value of extracting information from e-mail explored. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Color-based tumor tissue segmentation for the automated estimation of oral cancer parameters

MICROSCOPY RESEARCH AND TECHNIQUE, Issue 1 2010
Yung-nien Sun
Abstract This article presents an automatic color-based feature extraction system for parameter estimation of oral cancer from optical microscopic images. The system first reduces image-to-image variations by means of color normalization. We then construct a database which consists of typical cancer images. The color parameters extracted from this database are then used in automated online sampling from oral cancer images. Principal component analysis is subsequently used to divide the color features into four tissue types. Each pixel in the cancer image is then classified into the corresponding tissue types based on the Mahalanobis distance. The aforementioned procedures are all fully automated; in particular, the automated sampling step greatly reduces the need for intensive labor in manual sampling and training. Experiments reveal high levels of consistency among the results achieved using the manual, semiautomatic, and fully automatic methods. Parameter comparisons between the four cancer stages are conducted, and only the mean parameters between early and late cancer stages are statistically different. In summary, the proposed system provides a useful and convenient tool for automatic segmentation and evaluation for stained biopsy samples of oral cancer. This tool can also be modified and applied to other tissue images with similar staining conditions. Microsc. Res. Tech. 2009. © 2009 Wiley-Liss, Inc. [source]

Carbonate extraction process for the metabolic, isozymic and proteomic profiling of rose-scented geranium (Pelargonium sp.), a hyper-acidic plant

PHYTOCHEMICAL ANALYSIS, Issue 2 2008
Rajender Singh Sangwan
Abstract Rose-scented geranium (Pelargonium sp.) is a valuable monoterpene-yielding plant. It has been well characterised phytochemically through the isolation of >270 secondary metabolites, however, there is hardly any biochemical or metabolic information concerning this plant. Initial attempts to investigate its metabolism failed to produce any enzyme activity in the tissue extracts prepared in routine extraction buffers owing to the intrinsic properties of the tissue matrix. It was recognised that cellular hyper-acidity (cell sap pH ,3.0) gave rise to very low protein levels in the extracts, thus prohibiting detection of activities of even primary metabolic enzymes that are usually abundantly present in plants. Tissue extraction in Tris solution without pH adjustment (as used for studies involving citrus and banana) led to little or no improvement. Therefore, a novel approach using sodium carbonate solution as an efficient extraction system for enzymes and proteins from the plant was studied. Functionality of the carbonate extraction has been demonstrated through its effectiveness, a several-fold superior performance, in yielding protein, monitoring primary metabolism and secondary metabolic enzymes, and isozymic and polypeptide profiling. The process may also be helpful in the reliable analysis of other acidic plant tissues. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Exposure to respirable dust and crystalline silica in bricklaying education at Dutch vocational training centers

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 6 2010
Daan Huizer MSc
Abstract Background Construction workers are educated at vocational training centers before they begin their working lives. Future bricklayers and their instructors are exposed to respirable dust and possibly to hazardous respirable crystalline silica from trial mortar. Methods Thirty-six personal air samples were collected at six training centers to estimate exposure to respirable dust for both students and teachers. A selection of 22 samples was analyzed for crystalline silica. Results Average respirable dust exposures ranged from 0.59,mg/m3 for teachers to 1.45,mg/m3 for students performing recycling and cleaning tasks. In 45% of the analyzed samples, respirable crystalline silica was detected. Exposure to silica remained below the Dutch OEL (75,µg/m3). Exposure was significantly less for teachers than for students. This effect was found in both types of vocational training centers present in the Netherlands. Dry sweeping, as performed at all locations in this study, contributed considerably to the exposure to respirable dust. A first step in reducing exposure to dust and silica at training centers would therefore be to avoid dry sweeping. The presence of a dust extraction system, although not optimally designed, also significantly lowered exposure. Conclusions To assess a construction worker's lifetime exposure to respirable dust and crystalline silica, the vocational training period should also be taken into account. Several epidemiological studies have shown that time since first exposure can be an important risk factor for chronic health effects. Am. J. Ind. Med. 53: 628,634, 2010. © 2010 Wiley-Liss, Inc. [source]

Extraction of Lanthanides from Aqueous Solution by Using Room-Temperature Ionic Liquid and Supercritical Carbon Dioxide in Conjunction

CHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2006
Soufiane Mekki Dr.
Abstract For the first time, the study of a three-step extraction system of water/ionic liquid/supercritical CO2 has been performed. Extraction of trivalent lanthanum and europium from an aqueous nitric acid solution to a supercritical CO2 phase via an imidazolium-based ionic liquid phase is demonstrated, and extraction efficiencies higher than 87,% were achieved. The quantitative extraction is obtained by using different fluorinated ,-diketones with and without the addition of tri(n -butyl)phosphate. The complexation phenomenon occurring in the room-temperature ionic-liquid (RTIL) phase was evidenced by using luminescence spectroscopy. [source]

Applications of the Liquid Cyclone in Biological Separations

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2004
E. Ortega-Rivas
Abstract Hydrocyclone technology has been suggested as a practical alternative in solid/liquid separations involving biological materials. This paper reviews applications of hydrocyclones in food processing, considering the non-Newtonian nature of most suspensions treated in the food industry. The hydrocyclone is easy to install and operate, and requires very limited space. It represents an unsophisticated piece of equipment, which runs in a continuous manner and it can be operated at lower costs than most solid/liquid separation techniques. Hydrocyclones have been used in the food industry for the refining of starch, to separate gossypol from cottonseed protein in cottonseed oil processing, and for some other applications, such as multi-stage mixer/separator extraction systems for soluble coffee. More recently, some other applications in biological systems, which will be discussed in this article, have also been tested. [source]

Carbon dioxide extraction of residual chloroform from biodegradable polymers

JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 5 2002
Wendy S. Koegler
Abstract Biodegradable polymeric devices for drug delivery and tissue engineering are often fabricated with the use of organic solvents and may still contain significant amounts of solvent (> 1 wt%) even after aggressive vacuum drying. This excess solvent can interfere with tissue response and the mechanical properties of the devices. The aim of this article is to demonstrate that liquid CO2 extraction can be used to reduce residual solvent in dense poly(L -lactide-co-glycolide) devices to 50 ppm relatively quickly and with minimal changes in architecture under some conditions. Two liquid CO2 extraction systems were developed to examine the removal of residual solvents from bar-shaped PLGA devices: (1) a low-pressure (1400 psi) batch system, and (2) a high-pressure (5000 psi) continuous-flow system. Eight hours of extraction in the high-pressure system reduced residual chloroform in 3 mm thick bars below the 50-ppm target. A simple Fickian diffusion model was fit to the extraction results. Diffusion coefficients ranged from 1.10×10,6 cm2/s to 2.64×10,6 cm2/s. The model predicts that ,1 h is needed to dry 1-mm bars to chloroform levels below 50 ppm, and 7 h are needed for 3 mm thick bars. The micro- and macroarchitectures of porous PLGA scaffolds created by particulate leaching were not significantly altered by CO2 drying if the salt used to make the pores was not removed before drying. © 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 567,576, 2002 [source]

Solvent extraction studies of Sm(III) from nitrate medium and separation factors of rare earth elements with mixtures of sec -octylphenoxyacetic acid and 1,10-phenthroline

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2010
Shujuan Fan
Abstract BACKGROUND: Liquid,liquid extraction is widely used for the separation of rare earths, among which synergistic extraction has attracted more and more attention. Numerous types of synergistic extraction systems have been applied to rare earths with high extraction efficiency and selectivities. In the present study, mixtures of sec -octylphenoxyacetic acid (CA12, H2A2) and 1,10-phenanthroline (phen, B) have been used for the extraction of rare earths from nitrate medium. The stoichiometry of samarium(III) extraction has been studied using the methods of slope analysis and constant molar ratio. The possibility of using synergistic extraction effects to separate rare earths has also been studied. RESULTS: Mixtures of CA12 and phen display synergistic effects in the extraction of rare earth elements giving maximum enhancement coefficients of 5.5 (La); 13.7 (Nd); 15.9 (Sm); 24.5 (Tb); 45.4 (Yb) and 12.3 (Y). Samarium(III) is extracted as SmHA4B3 with mixtures of CA12 and phen instead of SmHA4 when extracted with CA12 alone. The calculated logarithm of the equilibrium constant is 6.0 and the thermodynamic functions, ,H, ,G, and ,S, have been calculated as 4.3 kJ mol,1, , 33.7 kJ mol,1 and 129.7 J mol,1 K,1, respectively. CONCLUSION: Mixtures of CA12 and phen exhibit synergistic effects on rare earth elements. Graphical and numerical methods have been successfully used to determine their stoichiometries. The different synergistic effects may provide the possibility of separating yttrium from heavy lanthanoids at an appropriate ratio of CA12 and phen. Copyright © 2010 Society of Chemical Industry [source]

Locating knowledge sources through keyphrase extraction

Improvement in fetal DNA extraction from maternal plasma.

PRENATAL DIAGNOSIS, Issue 1 2007
Evaluation of the NucliSens Magnetic Extraction system, the QIAamp DSP Virus Kit in comparison with the QIAamp DNA Blood Mini Kit
Abstract Objective Prenatal diagnostic assays have been developed using free fetal DNA circulating in the maternal blood of pregnant women. Efficient DNA extraction is crucial for a robust analysis. To improve fetal DNA yield, we tested two manual extraction methods,the NucliSens Magnetic Extraction (NMAG) system and the QIAamp DSP Virus Kit (QDSP),against our current standard method, the widely used QIAamp DNA Blood Mini Kit (QDNA). Methods The fetal DNA yield of the two extraction systems was evaluated using the RHD exon 7 as target in DNA extracts of 75 plasma samples from pregnant RhD-negative women, known to have given birth to RhD-positive infanto. The total DNA yield was evaluated in 23 samples, targeting GAPDH. Results The fetal DNA yield was improved by a mean factor of 1.7 using the NMAG system, and improved by a mean factor of 1.5 using the QDSP. The total DNA yield was improved by a mean factor of 2.3 using the NMAG system, and by a mean factor of 1.3 using the QDSP. Conclusion Both extraction systems tested were superior to our standard with regard to DNA yield. This improvement may have a great impact on the success of genotyping in early pregnancy. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Comparison of methods of DNA extraction for real-time PCR in a model of pleural tuberculosis

APMIS, Issue 1 2010
ANA SANTOS
Santos A, Cremades R, Rodríguez JC, García-Pachón E, Ruiz M, Royo G. Comparison of methods of DNA extraction for real-time PCR in a model of pleural tuberculosis. APMIS 2010; 118: 60,5. Molecular methods have been reported to have different sensitivities in the diagnosis of pleural tuberculosis and this may in part be caused by the use of different methods of DNA extraction. Our study compares nine DNA extraction systems in an experimental model of pleural tuberculosis. An inoculum of Mycobacterium tuberculosis was added to 23 pleural liquid samples with different characteristics. DNA was subsequently extracted using nine different methods (seven manual and two automatic) for analysis with real-time PCR. Only two methods were able to detect the presence of M. tuberculosis DNA in all the samples: extraction using columns (Qiagen) and automated extraction with the TNAI system (Roche). The automatic method is more expensive, but requires less time. Almost all the false negatives were because of the difficulty involved in extracting M. tuberculosis DNA, as in general, all the methods studied are capable of eliminating inhibitory substances that block the amplification reaction. The method of M. tuberculosis DNA extraction used affects the results of the diagnosis of pleural tuberculosis by molecular methods. DNA extraction systems that have been shown to be effective in pleural liquid should be used. [source]