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Analytical Techniques

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https://www.readbyqxmd.com/read/29778877/an-insight-into-the-multi-scale-structures-and-pasting-behaviors-of-starch-following-citric-acid-treatment
#1
Yinqiang Huo, Binjia Zhang, Meng Niu, Caihua Jia, Siming Zhao, Qilin Huang, Hongying Du
Using combined analytical techniques, this work discloses how citric acid (CA) treatment affects the pasting features of starch from a view of multi-scale structural evolutions. The treatment induced disruption events in starch multi-level structures and thus modulated the pasting behaviors. A structure-property relationship was proposed to rationalize CA effects on starch pasting properties. Specifically, CA disrupted starch structures from molecular scale to micron scale, eventually reducing pasting temperature and paste viscosities...
May 17, 2018: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29778692/two-dimensional-distribution-measurement-of-electric-current-generated-in-a-polymer-electrolyte-fuel-cell-using-49-nmr-surface-coils
#2
Kuniyasu Ogawa, Tatsuyoshi Sasaki, Shigeki Yoneda, Kumiko Tsujinaka, Ritsuko Asai
In order to increase the current density generated in a PEFC (polymer electrolyte fuel cell), a method for measuring the spatial distribution of both the current and the water content of the MEA (membrane electrode assembly) is necessary. Based on the frequency shifts of NMR (nuclear magnetic resonance) signals acquired from the water contained in the MEA using 49 NMR coils in a 7 × 7 arrangement inserted in the PEFC, a method for measuring the two-dimensional spatial distribution of electric current generated in a unit cell with a power generation area of 140 mm × 160 mm was devised...
May 17, 2018: Magnetic Resonance Imaging
https://www.readbyqxmd.com/read/29778501/the-discrimination-of-geoforensic-trace-material-from-close-proximity-locations-by-organic-profiling-using-hplc-and-plant-wax-marker-analysis-by-gc
#3
G McCulloch, L A Dawson, J M Ross, R M Morgan
There is a need to develop a wider empirical research base to expand the scope for utilising the organic fraction of soil in forensic geoscience, and to demonstrate the capability of the analytical techniques used in forensic geoscience to discriminate samples at close proximity locations. The determination of wax markers from soil samples by GC analysis has been used extensively in court and is known to be effective in discriminating samples from different land use types. A new HPLC method for the analysis of the organic fraction of forensic sediment samples has also been shown recently to add value in conjunction with existing inorganic techniques for the discrimination of samples derived from close proximity locations...
May 16, 2018: Forensic Science International
https://www.readbyqxmd.com/read/29778309/association-of-the-helicobacter-pylori-caga-vaca-and-icea-genotypes-with-chronic-follicular-gastritis-in-a-colombian-population-at-high-risk-for-gastric-cancer
#4
Y H Carlosama-Rosero, H Bolaños-Bravo, C H Sierra-Tórres, E A Rosero
INTRODUCTION AND OBJECTIVE: Follicular gastritis is associated with Helicobacter pylori infection, but little is known of its relation to bacterial genotypes. Our aim was to establish the relation between follicular gastritis and different H. pylori strains. MATERIALS AND METHODS: An analytic case-control study was conducted that included 36 patients with follicular gastritis (cases) and 83 with nonatrophic gastritis (controls). The sociodemographic information was obtained through a questionnaire...
May 16, 2018: Revista de Gastroenterología de México
https://www.readbyqxmd.com/read/29778078/an-effective-and-low-cost-carbon-based-clean-up-method-for-pcdd-fs-and-pcbs-analysis-in-food
#5
Kleopatra Kedikoglou, Danae Costopoulou, Irene Vassiliadou, Evangelos Bakeas, Leondios Leondiadis
Sample preparation is of critical importance in dioxin analysis of food and feed samples. It is a complex procedure that includes lipid extraction followed by the application of chromatographic separation techniques, aiming in removing undesirable interferences from the matrix. The separation of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from polychlorinated biphenyls (PCBs) is achieved by carbon-based materials which should have high fat capacity in order to be suitable for lipid-containing matrices...
May 7, 2018: Chemosphere
https://www.readbyqxmd.com/read/29777681/electrochemical-enzymatic-fenitrothion-sensor-based-on-a-tyrosinase-poly-2-hydroxybenzamide-modified-graphite-electrode
#6
Maria de Fátima Alves, Ricardo Augusto Moreira de Souza Corrêa, Filipe Soares da Cruz, Diego Leoni Franco, Lucas Franco Ferreira
This paper reports the electrosynthesis and characterisation of a polymeric film derived from 2-hydroxybenzamide over a graphite electrode and its application as an enzymatic biosensor for the determination and quantification of the pesticide fenitrothion. The material was analysed by scanning electron microscopy and its electrochemical properties characterised by cyclic voltammetry and electrochemical impedance spectroscopy. The enzyme tyrosinase was immobilised over the modified electrode by the drop and dry technique...
May 16, 2018: Analytical Biochemistry
https://www.readbyqxmd.com/read/29777599/immense-random-colocalization-revealed-by-automated-high-content-image-cytometry-seriously-questions-fish-as-gold-standard-for-detecting-eml4-alk-fusion
#7
Gábor Smuk, Tamás Tornóczky, László Pajor, Ilse Chudoba, Béla Kajtár, Veronika Sárosi, Gábor Pajor
EML4-ALK gene fusion (inv2(p21p23)) of non-small cell lung cancer (NSCLC) predisposes to tyrosine kinase inhibitor treatment. One of the gold standard diagnostics is the dual color (DC) break-apart (BA) FISH technique, however, the unusual closeness of the involved genes has been suggested to raise likelihood of random co-localization (RCL) of signals. Although this is suspected to decrease sensitivity (often to as low as 40-70%), the exact level and effect of RCL has not been revealed thus far. Signal distances were analyzed to the 0...
May 19, 2018: Cytometry. Part A: the Journal of the International Society for Analytical Cytology
https://www.readbyqxmd.com/read/29777596/morphological-analysis-of-pore-size-and-connectivity-in-a-thick-mixed-culture-biofilm
#8
Alex F Rosenthal, James S Griffin, Michael Wagner, Aaron I Packman, Oluwaseyi Balogun, George F Wells
Morphological parameters are commonly used to predict transport and metabolic kinetics in biofilms. Yet, quantification of biofilm morphology remains challenging due to imaging technology limitations and lack of robust analytical approaches. We present a novel set of imaging and image analysis techniques to estimate internal porosity, pore size distributions, and pore network connectivity to a depth of 1 mm at a resolution of 10 µm in a biofilm exhibiting both heterotrophic and nitrifying activity. Optical coherence tomography (OCT) scans revealed an extensive pore network with diameters as large as 110 µm directly connected to the biofilm surface and surrounding fluid...
May 19, 2018: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/29776547/on-the-potential-of-ion-mobility-spectrometry-coupled-to-gc-pre-separation-a-tutorial
#9
REVIEW
Wolfgang Vautz, Joachim Franzke, Stefano Zampolli, Ivan Elmi, Sascha Liedtke
In this tutorial, we want to demonstrate the significant potential of ion mobility spectrometry (IMS), an analytical technique for identification and quantification of gas-phase compounds, in particular combined to other useful analytical tools. Coupled to gas-chromatographic pre-separation (GC-IMS), selectivity can be improved significantly, thus enabling the analysis of complex, humid mixtures. In-line pre-concentration can improve sensitivity down to the ppqV range. Furthermore, the use of non-radioactive ionisation sources in the near future could gain acceptance and will avoid legal restrictions...
September 18, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29776546/recent-advances-in-analytical-methods-for-the-determination-of-4-alkylphenols-and-bisphenol-a-in-solid-environmental-matrices-a-critical-review
#10
REVIEW
N Salgueiro-González, S Castiglioni, E Zuccato, I Turnes-Carou, P López-Mahía, S Muniategui-Lorenzo
The problem of endocrine disrupting compounds (EDCs) in the environment has become a worldwide concern in recent decades. Besides their toxicological effects at low concentrations and their widespread use in industrial and household applications, these pollutants pose a risk for non-target organisms and also for public safety. Analytical methods to determine these compounds at trace levels in different matrices are urgently needed. This review critically discusses trends in analytical methods for well-known EDCs like alkylphenols and bisphenol A in solid environmental matrices, including sediment and aquatic biological samples (from 2006 to 2018)...
September 18, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29776545/evolution-of-clinical-and-environmental-health-applications-of-exhaled-breath-research-review-of-methods-and-instrumentation-for-gas-phase-condensate-and-aerosols
#11
REVIEW
M Ariel Geer Wallace, Joachim D Pleil
Human breath, along with urine and blood, has long been one of the three major biological media for assessing human health and environmental exposure. In fact, the detection of odor on human breath, as described by Hippocrates in 400 BC, is considered the first analytical health assessment tool. Although less common in comparison to contemporary bio-fluids analyses, breath has become an attractive diagnostic medium as sampling is non-invasive, unlimited in timing and volume, and does not require clinical personnel...
September 18, 2018: Analytica Chimica Acta
https://www.readbyqxmd.com/read/29776343/physical-inactivity-gender-and-culture-in-arab-countries-a-systematic-assessment-of-the-literature
#12
Eman Sharara, Chaza Akik, Hala Ghattas, Carla Makhlouf Obermeyer
BACKGROUND: Physical inactivity is associated with excess weight and adverse health outcomes. We synthesize the evidence on physical inactivity and its social determinants in Arab countries, with special attention to gender and cultural context. METHODS: We searched MEDLINE, Popline, and SSCI for articles published between 2000 and 2016, assessing the prevalence of physical inactivity and its social determinants. We also included national survey reports on physical activity, and searched for analyses of the social context of physical activity...
May 18, 2018: BMC Public Health
https://www.readbyqxmd.com/read/29776040/distribution-of-diameters-for-erd%C3%A5-s-r%C3%A3-nyi-random-graphs
#13
A K Hartmann, M Mézard
We study the distribution of diameters d of Erdős-Rényi random graphs with average connectivity c. The diameter d is the maximum among all the shortest distances between pairs of nodes in a graph and an important quantity for all dynamic processes taking place on graphs. Here we study the distribution P(d) numerically for various values of c, in the nonpercolating and percolating regimes. Using large-deviation techniques, we are able to reach small probabilities like 10^{-100} which allow us to obtain the distribution over basically the full range of the support, for graphs up to N=1000 nodes...
March 2018: Physical Review. E
https://www.readbyqxmd.com/read/29775562/rapid-quantification-of-vesicle-concentration-for-dopg-dopc-and-cardiolipin-dopc-mixed-lipid-systems-of-variable-composition
#14
Margaret M Elmer-Dixon, Bruce E Bowler
A novel approach to quantify mixed lipid systems is described. Traditional approaches to lipid vesicle quantification are time consuming, require large amounts of material and are destructive. We extend our recently described method for quantification of pure lipid systems to mixed lipid systems. The method only requires a UV-Vis spectrometer and does not destroy sample. Mie scattering data from absorbance measurements are used as input into a Matlab program to calculate the total vesicle concentration and the concentrations of each lipid in the mixed lipid system...
May 15, 2018: Analytical Biochemistry
https://www.readbyqxmd.com/read/29775432/estimating-usual-dietary-in-take-from-national-health-and-nut-rition-examination-survey-data-using-the-national-cancer-institute-method
#15
Kristen A Herrick, Lauren M Rossen, Ruth Parsons, Kevin W Dodd
Dietary recommendations are intended to be met based on dietary intake over long periods, as associations between diet and health result from habitual intake, not a single eating occasion or day of intake. Measuring usual intake directly is impractical for large population-based surveys due to the respondent burden associated with reporting habitual intake over longer periods. Therefore, analytical techniques were developed to estimate usual intake using as few as 2 days of 24-hour dietary recall data. With National Health and Nutrition Examination Survey (NHANES) data, this report demonstrates how to estimate usual intake using the National Cancer Institute (NCI)...
February 2018: Vital and Health Statistics. Series 2, Data Evaluation and Methods Research
https://www.readbyqxmd.com/read/29775341/clustering-of-magnetic-swimmers-in-a-poiseuille-flow
#16
Fanlong Meng, Daiki Matsunaga, Ramin Golestanian
We investigate the collective behavior of magnetic swimmers, which are suspended in a Poiseuille flow and placed under an external magnetic field, using analytical techniques and Brownian dynamics simulations. We find that the interplay between intrinsic activity, external alignment, and magnetic dipole-dipole interactions leads to longitudinal structure formation. Our work sheds light on a recent experimental observation of a clustering instability in this system.
May 4, 2018: Physical Review Letters
https://www.readbyqxmd.com/read/29775045/in-situ-spectroelectrochemical-monitoring-of-dye-bleaching-after-electrogeneration-of-chlorine-based-species-application-to-chloride-detection
#17
Daniel Martín-Yerga, Alejandro Pérez-Junquera, María Begoña Gonzalez-Garcia, David Hernández-Santos, Pablo Fanjul-Bolado
Spectroelectrochemical techniques are becoming increasingly versatile tools to solve a diverse range of analytical problems. Herein, the use of in situ real-time luminescence spectroelectrochemistry to quantify chloride ions is demonstrated. Utilizing the bleaching effect of chlorine-based electrogenerated products after chloride oxidation, it is shown that the fluorescence of the Rhodamine 6G dye decrease proportionally to the initial chloride concentration in solution. A strong decrease of fluorescence is observed in acidic media compared to a lower decrease in alkaline media, which suggests that Cl2 , favourably generated at low pH, could be the main species responsible of the fluorescence loss...
May 18, 2018: Analytical Chemistry
https://www.readbyqxmd.com/read/29774908/enhanced-dna-detection-using-a-multiple-pulse-pumping-scheme-with-time-gating-mpptg
#18
Joseph D Kimball, Badri Maliwal, Sangram L Raut, Hung Doan, Zhangatay Nurekeyev, Ignacy Gryczynski, Zygmunt Gryczynski
Fluorescence signal enhancement induced by the binding of intercalators to DNA has been broadly utilized in various DNA detection methods. In most instances the increase in fluorescence intensity is associated with a concomitant increase of fluorescence lifetime. This increase of the fluorescence lifetime presents an additional opportunity to increase detection sensitivity. In this paper, we present a new approach to significantly enhance the sensitivity in detecting minute DNA concentrations. The approach is based on simultaneous use of time-gated detection and multi-pulse pumping...
May 18, 2018: Analyst
https://www.readbyqxmd.com/read/29774897/development-of-highly-sensitive-fluorescent-probes-for-the-detection-of-%C3%AE-galactosidase-activity-application-to-the-real-time-monitoring-of-senescence-in-live-cells
#19
Mauro Safir Filho, Pascal Dao, Maéva Gesson, Anthony R Martin, Rachid Benhida
We report the development of four novel fluorescent probes to monitor the activity of the β-galactosidase enzyme (β-gal), in vitro and in living cells. The fluorophores are based on a 6-amino-styryl-benzothiazole push-pull core and display a strong ICT emission. The probes encompass the fluorescent motif that is connected to a β-d-galactopyranoside moiety through a self-immolative benzyl carbamate linker (βGal-1-4). The screening of four different fluorophores enabled us to access new light-up and two-band ratiometric reporters...
May 18, 2018: Analyst
https://www.readbyqxmd.com/read/29773805/new-insights-into-mechanisms-of-material-ejection-in-maldi-mass-spectrometry-for-a-wide-range-of-spot-sizes
#20
Marcel Niehaus, Jens Soltwisch
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is widely used for the analysis of large biomolecules in numerous applications. The technique utilizes nanosecond-long laser pulses at various spot sizes to eject and ionize large molecules embedded in a highly absorptive chemical matrix. Despite the methods name, 'molecular desorption' from the matrix crystal surface is not the sole mechanism discussed for material ejection in MALDI, but additional ablation of larger clusters has been reported...
May 17, 2018: Scientific Reports
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