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Extraction Techniques (extraction + techniques)
Selected AbstractsInterpreting variability in global SST data using independent component analysis and principal component analysisINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 3 2010Seth Westra Abstract Component extraction techniques are used widely in the analysis and interpretation of high-dimensional climate datasets such as global sea surface temperatures (SSTs). Principal component analysis (PCA), a frequently used component extraction technique, provides an orthogonal representation of the multivariate dataset and maximizes the variance explained by successive components. A disadvantage of PCA, however, is that the interpretability of the second and higher components may be limited. For this reason, a Varimax rotation is often applied to the PCA solution to enhance the interpretability of the components by maximizing a simple structure. An alternative rotational approach is known as independent component analysis (ICA), which finds a set of underlying ,source signals' which drive the multivariate ,mixed' dataset. Here we compare the capacity of PCA, the Varimax rotation and ICA in explaining climate variability present in globally distributed SST anomaly (SSTA) data. We find that phenomena which are global in extent, such as the global warming trend and the El Nińo-Southern Oscillation (ENSO), are well represented using PCA. In contrast, the Varimax rotation provides distinct advantages in interpreting more localized phenomena such as variability in the tropical Atlantic. Finally, our analysis suggests that the interpretability of independent components (ICs) appears to be low. This does not diminish the statistical advantages of deriving components that are mutually independent, with potential applications ranging from synthetically generating multivariate datasets, developing statistical forecasts, and reconstructing spatial datasets from patchy observations at multiple point locations. Copyright © 2009 Royal Meteorological Society [source] Modelling current trends in Northern Hemisphere temperaturesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 7 2006Terence C. Mills Abstract Fitting a trend is of interest in many disciplines, but it is of particular importance in climatology, where estimating the current and recent trend in temperature is thought to provide a major indication of the presence of global warming. A range of ad hoc methods of trend fitting have been proposed, with little consensus as to the most appropriate techniques to use. The aim of this paper is to consider a range of trend extraction techniques, none of which require ,padding' out the series beyond the end of the available observations, and to use these to estimate the trend of annual mean Northern Hemisphere (NH) temperatures. A comparison of the trends estimated by these methods thus provides a robust indication of the likely range of current trend temperature increases and hence inform, in a timely quantitative fashion, arguments based on global temperature data concerning the nature and extent of global warming and climate change. For the complete sample 1856,2003, the trend is characterised as having long waves about an underlying increasing level. Since around 1970, all techniques display a pronounced warming trend. However, they also provide a range of trend functions so that extrapolation far into the future would be a hazardous exercise. Copyright © 2006 Royal Meteorological Society. [source] Technology options for new nutritional conceptsINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2002Hannu Korhonen Recent advances in the food and nutrition sciences support the concept that the diet has a significant role in the modulation of various functions in the body. The diet and/or its components may contribute to an improved state of well-being, a reduction of risks related to certain diseases and even an improvement in the quality of life. These new concepts have led to the introduction of a new category of health-promoting foodstuffs, i.e. functional foods. The concern about health embraces a number of driving issues, needs and opportunities which may be approached by designing specific diets from various food raw materials. These tailor-made products provide physiological benefits that are targeted at particular consumer groups. The functionality of functional foods is based on bioactive components, which may be contained naturally in the product but usually require formulation by appropriate technologies in order to optimise the desired beneficial properties. To this end, it is often necessary to develop and apply novel technologies, e.g. membrane separation, high hydrostatic pressure and supercritical fluid extraction techniques. Also the minimal processing concept could be employed in this context. This review discusses the current technological options available and the future challenges faced in the area. Particular attention is paid to the exploitation of bovine colostrum and milk-derived bioactive compounds for the development of functional foods. [source] Multiplex PCR detection of slowly-evolving trypanosomatids and neogregarines in bumblebees using broad-range primersJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2010I. Meeus Abstract Aims:, The aims of this study were to design universal markers for different protozoan parasites of Bombus spp. based on the phylogenetic position of two important bumblebee parasites Crithidia bombi and Apicystis bombi. Methods and Results:, Standard PCR and extraction techniques were used to amplify and sequence 18S rDNA. Phylogenetic analysis of the rDNA was performed in order to predict the parasite range of the primers. Conclusions:,Crithidia bombi phylogenetically clusters with the trypanosomatids with slowly-evolving SSU-rRNA sequences (SE), while A. bombi is the closest sister group of Mattesia. A multiplex was designed containing an internal control and two broad-range primer pairs, detecting C. bombi and other SE trypanosomatids and also A. bombi and other neogregarines. Significance and Impact of the Study:, Sequence data generated will further improve the current systematics of insect trypanosomatids and gregarines that remain troublesome. Broad-range markers for bumblebee parasites are necessary tools enabling the screening of commercially imported colonies and thus controlling their worldwide distribution and to discover related emerging parasites. [source] Comparison of various extraction techniques for isolation and determination of isoflavonoids in plantsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 1 2007Bajer Abstract In the present paper, the following extraction techniques have been used for extracting isoflavonoids from the species Matricaria recutita, Rosmarinus officinalis, Foeniculum vulgare, and Agrimonia eupatoria L.: supercritical fluid extraction (SFE), pressurized fluid extraction, matrix solid phase dispersion, ultrasonic extraction in an ultrasonic bath (USE) and by means of an ultrasonic homogeniser (HOM), extraction by means of Soxhlet apparatus (SOX), and solid phase extraction. Experimental optimization of all techniques has been carried out using a soybean flour. Subsequent analyses of the extracts were carried out by liquid chromatography with UV detection. The maximum yields of daidzein and genistein were obtained by extraction with the SOX, USE, and HOM techniques. The maximum yields of apigenin and biochanin A from herb samples were obtained by SFE. [source] Chemical composition of mate tea leaves (Ilex paraguariensis): A study of extraction methodsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2006Rosângela Assis Jacques Abstract The objective of this work was to investigate the extraction of Ilex paraguariensis leaves by means of three extraction techniques: pressurized liquid extraction (PLE, also called accelerated solvent extraction , ASE), maceration, and sonication. Samples of mate tea leaves were collected from an experiment conducted under agronomic control at Indústria e Comércio de Erva-Mate Bar,o LTDA, Brazil. Six solvents with increasing polarities (n -hexane, toluene, dichloromethane, ethyl acetate, acetone, and methanol) were used in this investigation. Chemical analysis of the extracts was performed by GC coupled with a mass spectrometer detector. The identification and quantification were accomplished by coinjections of certified standards. The results showed that no significant differences in the qualities of the extracts were noticed regarding the extraction methods. On the other hand, the PLE technique was found to be more effective for the extractions of caffeine, phytol, palmitic, and stearic acid. The use of PLE led to a significant decrease in the total extraction time, amount of solvent consumption, and manipulation of samples compared to maceration and ultrasound-assisted extraction methods. [source] Methyl benzoate as a marker for the detection of mold in indoor building materialsJOURNAL OF SEPARATION SCIENCE, JSS, Issue 18 2005Loay Wady Abstract A convenient analytical method to quantify volatile organic compounds (VOCs) emitted from various building materials has not been addressed yet. This work presents a new and rapid automated method using SPME combined with GC/MS. Methyl benzoate , as a metabolic biomarker for mold growth,was used to indicate VOCs and to determine and assess mold growth on damp samples. Gypsum board and wallboard paper were used as examples of common indoor building materials. Optimized extraction conditions were carried out manually, using a GC/flame ionization detector. Moldy samples were analyzed using an automated SPME-GC/MS analysis under optimized conditions. The amount of methyl benzoate emitted from the studied samples ranged from 32 to 46 ppb, where the density of the fungal biomass was found to be 8×104 cells/mL. A relationship between the amount of fungal biomass and the emitted concentration of methyl benzoate was found and assessed based upon cultured mold samples taken from indoor building sites. The analytical method shows promise for the compound methyl benzoate, which can easily be identified at low detection limits (LOD = 3 ppb) and good linearity (> 0.988), and its extraction and detection can be accomplished cleanly by current extraction techniques. Results suggest that this method with easy sample preparation can be used for quantitation and, of importance, minimal matrix effects are observed. [source] Influence of ripening stage on volatiles composition, physicochemical indexes and sensory evaluation in two varieties of muskmelon (Cucumis melo L var reticulatus Naud)JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 8 2005Emilio Senesi Abstract The quality parameters of muskmelon (Cucumis melo L var reticulatus Naud) are often related to sugar content and aroma composition. A study of aroma composition using two different extraction techniques (GC-HS and GC-MS extraction concentration) was performed in order to find correlations with sensory descriptors, other quality indices and ripening stage. Two muskmelon varieties (Calypso and Pamir) were assayed at three different ripening stages (unripe, ripe, overripe). Chemical, physical and sensory analyses were performed on the muskmelon samples just after harvest and after 7 days of cold storage. Solid soluble content (SSC) changed from about 10°Bx in unripe samples to about 15°Bx in ripe and overripe samples. Different aroma composition and sensory evaluation were found depending on the ripening stages. The main flavour components detected were esters which increased 10,15-fold from unripe to ripe and overripe stages. The acceptance judgements by panellists were strongly correlated with the sensory descriptor flavour. High statistical correlations were also found between sensory descriptor flavour and some classes of aroma compounds, mainly with total esters (about 0.66,0.69), formates (0.70) and acetates (0.64 and 0.72). The paper demonstrates that some classes of esters are very important to assess the sensory flavour and overall eating quality of muskmelons. Copyright © 2005 Society of Chemical Industry [source] Diagnosis of breast cancer using diffuse reflectance spectroscopy: Comparison of a Monte Carlo versus partial least squares analysis based feature extraction techniqueLASERS IN SURGERY AND MEDICINE, Issue 7 2006Changfang Zhu MS Abstract Background and Objective We explored the use of diffuse reflectance spectroscopy in the ultraviolet-visible (UV-VIS) spectrum for the diagnosis of breast cancer. A physical model (Monte Carlo inverse model) and an empirical model (partial least squares analysis) based approach, were compared for extracting diagnostic features from the diffuse reflectance spectra. Study Design/Methods The physical model and the empirical model were employed to extract features from diffuse reflectance spectra measured from freshly excised breast tissues. A subset of extracted features obtained using each method showed statistically significant differences between malignant and non-malignant breast tissues. These features were separately input to a support vector machine (SVM) algorithm to classify each tissue sample as malignant or non-malignant. Results and Conclusions The features extracted from the Monte Carlo based analysis were hemoglobin saturation, total hemoglobin concentration, beta-carotene concentration and the mean (wavelength averaged) reduced scattering coefficient. Beta-carotene concentration was positively correlated and the mean reduced scattering coefficient was negatively correlated with percent adipose tissue content in normal breast tissues. In addition, there was a statistically significant decrease in the beta-carotene concentration and hemoglobin saturation, and a statistically significant increase in the mean reduced scattering coefficient in malignant tissues compared to non-malignant tissues. The features extracted from the partial least squares analysis were a set of principal components. A subset of principal components showed that the diffuse reflectance spectra of malignant breast tissues displayed an increased intensity over wavelength range of 440,510 nm and a decreased intensity over wavelength range of 510,600 nm, relative to that of non-malignant breast tissues. The diagnostic performance of the classification algorithms based on both feature extraction techniques yielded similar sensitivities and specificities of approximately 80% for discriminating between malignant and non-malignant breast tissues. While both methods yielded similar classification accuracies, the model based approach provided insight into the physiological and structural features that discriminate between malignant and non-malignant breast tissues. Lasers Surg. Med. © 2006 Wiley-Liss, Inc. [source] INVITED REVIEW: Molecular analysis of predation: a review of best practice for DNA-based approachesMOLECULAR ECOLOGY, Issue 4 2008R. A. KING Abstract Molecular analysis of predation, through polymerase chain reaction amplification of prey remains within the faeces or digestive systems of predators, is a rapidly growing field, impeded by a lack of readily accessible advice on best practice. Here, we review the techniques used to date and provide guidelines accessible to those new to this field or from a different molecular biology background. Optimization begins with field collection, sample preservation, predator dissection and DNA extraction techniques, all designed to ensure good quality, uncontaminated DNA from semidigested samples. The advantages of nuclear vs. mitochondrial DNA as primer targets are reviewed, along with choice of genes and advice on primer design to maximize specificity and detection periods following ingestion of the prey by the predators. Primer and assay optimization are discussed, including cross-amplification tests and calibratory feeding experiments. Once primers have been made, the screening of field samples must guard against (through appropriate controls) cross contamination. Multiplex polymerase chain reactions provide a means of screening for many different species simultaneously. We discuss visualization of amplicons on gels, with and without incorporation of fluorescent primers. In more specialized areas, we examine the utility of temperature and denaturing gradient gel electrophoresis to examine responses of predators to prey diversity, and review the potential of quantitative polymerase chain reaction systems to quantify predation. Alternative routes by which prey DNA might get into the guts of a predator (scavenging, secondary predation) are highlighted. We look ahead to new technologies, including microarrays and pyrosequencing, which might one day be applied to this field. [source] A high-throughput protocol for extracting high-purity genomic DNA from plants and animalsMOLECULAR ECOLOGY RESOURCES, Issue 4 2008R. WHITLOCK Abstract DNA extraction techniques that employ the reversible binding of DNA to silica via chaotropic salts can deliver high-quality genomic DNA from plant and animal tissues, while avoiding the use of toxic organic solvents. Existing techniques that use this method are either prohibitively expensive, or are applicable to only a restricted set of taxa. Here we describe a cost-effective DNA extraction technique suitable for a wide range of plant and animal taxa that yields microgram quantities of high-molecular-weight genomic DNA at a throughput of 192 samples per day. Our technique is particularly robust for tissue samples that are insoluble or are rapidly discoloured or oxidized in standard DNA extraction buffers. We demonstrate the quality of DNA extracted using this method by applying the amplified fragment length polymorphism technique to plant species. [source] Comparison of the capabilities of accelerated solvent extraction and sonication as extraction techniques for the quantification of kavalactones in piper methysticum (Kava) roots by high performance liquid chromatography with ultra violet detectionPHYTOCHEMICAL ANALYSIS, Issue 2 2007Emma Warburton Abstract A conventional extraction technique of sonication has been compared, in terms of extraction efficiency, extraction time and amount of solvent, with the more novel technique of accelerated solvent extraction for the extraction of kavain from the powdered roots of Piper methysticum (Kava) with acetone. The extracts were analysed using high-performance liquid chromatography with ultra violet detection. The effects of varying solvent volume and extraction time upon the quantity of kavain extracted with sonication, and the effects of varying temperature upon the kavain extraction efficiency by ASE, were investigated. ASE was found to be more efficient with respect to time and solvent volume required; however, a good agreement was found between the kavain concentration obtained using both extraction techniques. © Crown Copyright 2007. Reproduced with the permission of the Controller of HMSO. Published by John Wiley & Sons, Ltd. [source] Enhanced solvent extraction of polar lipids associated with rubber particles from hevea brasiliensisPHYTOCHEMICAL ANALYSIS, Issue 2 2007Frederic Bonfils Abstract Biochemical studies of lipids bound to rubber particles have been complicated due to the solubility of polyisoprene chains in most extracting solvents and the rather delicate nature of polar lipids that are often denatured when traditional solvent extraction techniques are employed. In this paper, we describe a traditional technique and accompanying solvents that permit optimal extraction of rubber particle bound lipids. The technique, which is validated after characterizing the lipid extracts by elemental analysis, silica column adsorption and thin layer chromatography, appeared more suitable for extracting total lipids with optimal glycolipid and phospholipid contents. This technique is proposed as an alternative to traditional extraction methods used for solid natural rubber as it offers advantages with respect to ease of application, extract quality, extraction yields and reproducibility. Copyright © 2007 John Wiley & Sons, Ltd. [source] Water policy and environmental sustainability: the case of post-colonial NamibiaPUBLIC ADMINISTRATION & DEVELOPMENT, Issue 5 2001Joshua B. ForrestArticle first published online: 21 DEC 200 In semi-arid countries, particularly in Africa, governments have evolved water policies oriented toward ,techno-giantist,' grand-scale schemes that have generally accelerated the depletion of national water tables. In Namibia, such a techno-giantist water management strategy was utilized to reinforce the privileges of white minority farmers prior to independence, and was subsequently expanded to provide modern water facilities to the black African majority in the post-independence period. The government has pursued not only the construction of a massive new system of pipelines and boreholes, but also the development of giant dam-building and river canal schemes that are likely to result in watershed depletion over the long term. This reflects state leaders' belief in the imagery of political potency projected by the government's ability to build macro-scale water systems. However, a water supply approach focused on more micro-level extraction techniques through which aquifer recharge is prioritized is more likely to assure both local-level water access and water table sustainability. Copyright © 2001 John Wiley & Sons, Ltd. [source] The determination of N- nitrosamines in foodQUALITY ASSURANCE & SAFETY OF CROPS & FOOD, Issue 1 2010Colin Crews Abstract Introduction N -nitrosamines are formed in food as a result of natural chemical interactions, but mainly through food processing activity. Most are potent carcinogens and their determination is therefore of considerable importance. They exist in various chemical forms and have been measured by colorimetric and spectroscopic methods following gas or liquid chromatography or as a total N -nitroso group by measurement of chemically released nitric oxide. Objectives To provide an overview of the available methods for the analysis of N -nitrosamines in food that includes recently developments. Methods The literature was reviewed from the discovery of the N -nitrosamine problem and the introduction on the N -nitroso-specific detector. Results The evaluation shows that analytical detection methods for volatile N -nitrosamines in food have changed little since the introduction on the N -nitroso-specific detector and that research into the occurrence and formation of both non-volatile N -nitrosamines and the apparent total N -nitroso content (ATNC) have declined. Methods for measuring the apparent total N -nitroso content have not been improved significantly in recent years. Conclusion Modern sample extraction techniques and mass spectrometric methods for the volatile N -nitrosamines have been applied more extensively to water analysis and offer a good opportunity to improve the determination of these carcinogens in food and make the analysis more widely available. Developments in liquid chromatography-mass spectrometry should provide an avenue for renewed interest in non-volatile N -nitrosamines, and could help with the identification of novel compounds whose presence is suggested by the high apparent total N -nitroso content of some foods. [source] A NEW METHOD FOR EXTRACTION, ISOLATION AND TRANSESTERIFICATION OF FREE FATTY ACIDS FROM ARCHAEOLOGICAL POTTERYARCHAEOMETRY, Issue 5 2010M. W. GREGG This paper presents evidence for increased recovery of organic residues from archaeological pottery through use of a microwave-assisted liquid chromatography protocol. C16:0 and C18:0 saturated fatty acids were obtained from archaeological potsherds recovered from nine Neolithic settlements in the Middle East dating between 4700 and 7300 cal bc, including materials that had not produced evidence for the survival of any lipid species through use of ,conventional' solvent extraction techniques. Compound-specific isotopic analyses of C16:0 and C18:0 fatty acids in potsherd extracts subsequently revealed ,13C/,12C compositions consistent with modern subcutaneous fats of wild boar and goats pastured on lands adjacent to the Jordan Valley, and residues from a modern pottery vessel used in the manufacturing of butter, cheese and yogurt in central Turkey. These results are presented as an illustration of capabilities of the microwave-assisted recovery protocol. The reclamation of saturated and unsaturated fatty acids from archaeological pottery fragments recovered from a number of the earliest ceramic horizons in the Middle East is herewith reported, and the extraction methods and instrumental analytical techniques are described. [source] Endothelial injury and repair in systemic vasculitis of the youngARTHRITIS & RHEUMATISM, Issue 6 2010L. A. Clarke Objective Endothelial injury is central to the pathogenesis of vasculitis. The purpose of this study was to assess how indices of endothelial injury and repair change during different stages of disease activity in children with primary systemic vasculitis (PSV). Methods Fifty children with PSV, 17 children with nonvasculitic inflammatory diseases (pediatric inflammatory disease controls), 35 healthy age- and sex-matched pediatric controls, and 27 healthy adult controls were included in the study. Biomarkers examined were endothelial microparticles (EMPs), circulating endothelial cells (CECs), angiogenic growth factors, and endothelial progenitor cells (EPCs). EMP binding to annexin V, EMPs expressing CD144 or E-selectin, and EPCs expressing vascular endothelial growth factor receptor 2 (VEGFR-2), CD133, and CD34 were examined by flow cytometry. CECs were enumerated using immunomagnetic bead extraction techniques, and VEGF and angiopoietin 2 (Ang-2) were measured by enzyme-linked immunosorbent assay. Results Levels of CD144+ EMPs, CECs, VEGF, and EPCs were all significantly elevated in children with active vasculitis as compared with healthy children, and the levels declined with remission-inducing therapy in the individual patients. Treatment-naive patients with active disease had significantly higher levels of VEGF and Ang-2 than did those with active disease who were receiving treatment, although the levels of CECs and EMPs remained high in both of these groups. Conclusion Elevation of the levels of CECs, EMPS, EPCs, VEGF, and Ang-2 occurs during active vasculitis in children. EPC responses to active vasculitis are different in children as compared with that observed in adults with vasculitis, and both CECs and EMPs can be used to monitor disease activity in children with vasculitis. [source] Chromatographic determination of herbicide residues in various matricesBIOMEDICAL CHROMATOGRAPHY, Issue 6 2004Tibor Cserháti Abstract The newest results in the use of various extraction techniques and chromatographic methods such as gas,liquid and high-performance liquid chromatography used for the assessment of herbicide residues in various matrices have been compiled and critically evaluated. Practical employments in water and soil research, environmental protection, clinical and food chemistry are presented. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||