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https://www.readbyqxmd.com/read/28738655/risk-of-false-decision-on-conformity-of-a-multicomponent-material-when-test-results-of-the-components-content-are-correlated
#1
Ilya Kuselman, Francesca R Pennecchi, Ricardo J N B da Silva, D Brynn Hibbert
The probability of a false decision on conformity of a multicomponent material due to measurement uncertainty is discussed when test results are correlated. Specification limits of the components' content of such a material generate a multivariate specification interval/domain. When true values of components' content and corresponding test results are modelled by multivariate distributions (e.g. by multivariate normal distributions), a total global risk of a false decision on the material conformity can be evaluated based on calculation of integrals of their joint probability density function...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738645/competitive-fluorescence-anisotropy-polarization-assay-for-atp-using-aptamer-as-affinity-ligand-and-dye-labeled-atp-as-fluorescence-tracer
#2
Yapiao Li, Linlin Sun, Qiang Zhao
We developed an aptamer-based competitive fluorescence anisotropy (FA)/fluorescence polarization (FP) assay for adenosine triphosphate (ATP). Different from the traditional fluorescence polarization immunoassays for small molecules, here DNA aptamer against ATP was used as affinity ligand, and tetramethylrhodamine (TMR) labeled ATP served as fluorescent tracer. The binding between TMR-labeled ATP and aptamer gave large FA due to molecular volume increase and restricted rotation of the dye-labeled ATP. When ATP was added in solution, ATP competitively displaced the TMR-labeled ATP from aptamer affinity complex, causing decrease of FA of TMR-labeled ATP...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738633/application-of-raman-spectroscopy-for-direct-analysis-of-carlina-acanthifolia-subsp-utzka-root-essential-oil
#3
Maciej Strzemski, Magdalena Wójciak-Kosior, Ireneusz Sowa, Monika Agacka-Mołdoch, Piotr Drączkowski, Dariusz Matosiuk, Łukasz Kurach, Ryszard Kocjan, Sławomir Dresler
Carlina genus plants e.g. Carlina acanthifolia subsp. utzka have been still used in folk medicine of many European countries and its biological activity is mostly associated with root essential oils. In the present paper, Raman spectroscopy (RS) was applied for the first time for evaluation of essential oil distribution in root of C. acnthifolia subsp. utzka and identification of root structures containing the essential oil. Furthermore, RS technique was applied to assess chemical stability of oil during drying of plant material or distillation process...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738628/mip-meps-based-sensing-strategy-for-the-selective-assay-of-dimethoate-application-to-wheat-flour-samples
#4
D Capoferri, M Del Carlo, N Ntshongontshi, E I Iwuoha, M Sergi, F Di Ottavio, D Compagnone
The aim of this work was to demonstrate the potentialities of the use of a molecularly imprinted (MIP) sensor coupled to a microextraction by packed sorbent (MEPS) strategy for the selective and sensitive detection of dimethoate in real samples. A dimethoate-polypyrrole MIP film was realised by cyclic voltammetry (CV) on the surface of a glassy carbon electrode (GCE). Being dimethoate electro-inactive, K3[Fe(CN)6] was used as probe for the indirect quantification of the analyte via the decrease of redox peaks observed upon binding of the target analyte...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738626/elimination-of-interference-from-water-in-kbr-disk-ft-ir-spectra-of-solid-biomaterials-by-chemometrics-solved-with-kinetic-modeling
#5
Sherald H Gordon, Rogers E Harry-O'kuru, Abdellatif A Mohamed
Infrared analysis of proteins and polysaccharides by the well known KBr disk technique is notoriously frustrated and defeated by absorbed water interference in the important amide and hydroxyl regions of spectra. This interference has too often been overlooked or ignored even when the resulting distortion is critical or even fatal, as in quantitative analyses of protein secondary structure, because the water has been impossible to measure or eliminate. Therefore, a new chemometric method was devised that corrects spectra of materials in KBr disks by mathematically eliminating the water interference...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738622/a-flow-based-procedure-exploiting-the-lab-in-syringe-approach-for-the-determination-of-ester-content-in-biodiesel-and-diesel-biodiesel-blends
#6
Samara Soares, Wanessa R Melchert, Fábio R P Rocha
The ester content is an important parameter to be monitored in biodiesel for evaluation of the transesterification reaction yield and for assessing the purity of the final product. This is also a relevant quality parameter in diesel/biodiesel blends to avoid frauds, because legislation establishes a minimum amount of biodiesel to be added to diesel. The official method EN14103 requires the addition of an alternative internal standard (methyl nonadecanoate) for analysis of biodiesel from bovine tallow because the methyl heptadecanoate is found in high amounts in this product...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738615/electrochemical-magneto-immunosensor-based-on-endogenous-%C3%AE-galactosidase-enzyme-to-determine-enterotoxicogenic-escherichia-coli-f4-k88-in-swine-feces-using-square-wave-voltammetry
#7
Lorena Viviana Tarditto, María Alicia Zon, Hugo García Ovando, Nelio Roberto Vettorazzi, Fernando Javier Arévalo, Héctor Fernández
Diseases caused by enterotoxicogenic Escherichia coli F4 (K88) (ETEC F4) are a problem in swine production establishments. Due to the high rate of mortality and morbidity of E. coli infections, a rapid and accurate diagnosis is important in order to choose an appropriate treatment to reduce the economic impact. Therefore, an electrochemical magneto-immunosensor (EMI) was developed to detect and quantify ETEC F4 in swine feces samples through a direct non-competitive immunoassay. ETEC F4 was selectively captured by immunomagnetic separation...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738602/portable-electrochemical-system-using-screen-printed-electrodes-for-monitoring-corrosion-inhibitors
#8
André L Squissato, Weberson P Silva, Augusto T S Del Claro, Diego P Rocha, Rafael M Dornellas, Eduardo M Richter, Christopher W Foster, Craig E Banks, Rodrigo A A Munoz
This work presents a portable electrochemical system for the continuous monitoring of corrosion inhibitors in a wide range of matrices including ethanol, seawater and mineral oil following simple dilution of the samples. Proof-of-concept is demonstrated for the sensing of 2,5-dimercapto-1,3,5-thiadiazole (DMCT), an important corrosion inhibitor. Disposable screen-printed graphitic electrodes (SPGEs) associated with a portable batch-injection cell are proposed for the amperometric determination of DMCT following sample dilution with electrolyte (95% v/v ethanol + 5% v/v 0...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738587/a-novel-calibration-strategy-based-on-background-correction-for-quantitative-circular-dichroism-spectroscopy
#9
Qi Zuo, Shun Xiong, Zeng-Ping Chen, Yao Chen, Ru-Qin Yu
When using circular dichroism (CD) spectroscopy for quantitative analysis, the samples to be analyzed must be free of light-absorbing interferences. However, in real-world samples, the presence of background absorbers is practically unavoidable. The difference in the matrices between the real-world samples to be analyzed and the standard samples (on which either univariate or multivariate calibration model was built) would result in systematic errors in the quantification results of CD spectroscopy. In this contribution, a novel calibration strategy for quantitative CD spectroscopic analysis was proposed...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738583/application-of-headspace-and-direct-immersion-solid-phase-microextraction-in-the-analysis-of-organothiophosphates-related-to-the-chemical-weapons-convention-from-water-and-complex-matrices
#10
Marc André Althoff, Andreas Bertsch, Manfred Metzulat, Thomas M Klapötke, Konstantin L Karaghiosoff
The successful application of headspace (HS) and direct immersion (DI) solid phase microextraction (SPME) for the unambiguous identification and characterization of a series of toxic thiophosphate esters, such as Amiton (I), from aqueous phases and complex matrices (e.g. grass and foliage) has been demonstrated. A Thermo Scientific gas chromatograph (GC) - tandem mass spectrometer (MS/MS) system with a TriPlus RSH® autosampler and a SPME tool was used to investigate the effect of different parameters that influence the extraction efficiency: e...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738579/compositional-engineering-of-vopcpho-tio2-nano-composite-to-reduce-the-absolute-threshold-value-of-humidity-sensors
#11
Mohamad Izzat Azmer, Fakhra Aziz, Zubair Ahmad, Ehsan Raza, Mansoor Ani Najeeb, Noshin Fatima, Tahani M Bawazeer, Mohammad S Alsoufi, R A Shakoor, Khaulah Sulaiman
This research work demonstrates compositional engineering of an organic-inorganic hybrid nano-composites for modifying absolute threshold of humidity sensors. Vanadyl-2,9,16,23-tetraphenoxy-29H,31H-phthalocyanine (VOPcPhO), an organic semiconductor, doped with Titanium-dioxide nanoparticles (TiO2 NPs) has been employed to fabricate humidity sensors. The morphology of the VOPcPhO:TiO2 nano-composite films has been analyzed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738572/sequential-determination-of-nickel-and-cadmium-in-tobacco-molasses-and-refill-solutions-for-e-cigarettes-samples-by-molecular-fluorescence
#12
María Carolina Talio, Magdalena Alesso, Mariano Acosta, Verónica S Wills, Liliana P Fernández
In this work, a new procedure was developed for separation and preconcentration of nickel(II) and cadmium(II) in several and varied tobacco samples. Tobacco samples were selected considering the main products consumed by segments of the population, in particular the age (youth) and lifestyle of the consumer. To guarantee representative samples, a randomized strategy of sampling was used. In the first step, a chemofiltration on nylon membrane is carried out employing eosin (Eo) and carbon nanotubes dispersed in sodium dodecylsulfate (SDS) solution (phosphate buffer pH 7)...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738571/determination-of-polycyclic-aromatic-hydrocarbons-in-infant-formula-using-solid-state-urea-clathrate-formation-with-gas-chromatography-tandem-mass-spectrometry
#13
Zoltán Nyiri, Márton Novák, Zsolt Bodai, Noémi Petrovics, Zsuzsanna Eke
An analytical method has been developed for the quantitative determination of the 16 EU priority polycyclic aromatic hydrocarbons (PAHs) in infant formula. Prior to analysis infant formula is subjected to sample preparation including the extraction of PAHs from the sample, transesterification of the triglyceride content of the extract to fatty acid methyl esters (FAMEs), and solid state urea clathrate formation to remove the FAMEs. Measurements were carried out with gas chromatography - tandem mass spectrometry...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738558/elemental-source-attribution-signatures-for-calcium-ammonium-nitrate-can-fertilizers-used-in-homemade-explosives
#14
Carlos G Fraga, Alexander V Mitroshkov, Nikhil S Mirjankar, Brian P Dockendorff, Angie M Melville
Calcium ammonium nitrate (CAN) is a widely available fertilizer composed of ammonium nitrate (AN) mixed with some form of calcium carbonate such as limestone or dolomite. CAN is also frequently used to make homemade explosives. The potential of using elemental profiling and chemometrics to match both pristine and reprocessed CAN fertilizers to their factories of origin for use in future forensic investigations was examined. Inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine the concentrations of 64 elements in 125 samples from 11 CAN stocks from 6 different CAN factories...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738517/modelling-long-term-impacts-of-changes-in-climate-nitrogen-deposition-and-ozone-exposure-on-carbon-sequestration-of-european-forest-ecosystems
#15
Wim de Vries, Maximilian Posch, David Simpson, Gert Jan Reinds
We modelled the effects of past and expected future changes in climate (temperature, precipitation), CO2 concentration, nitrogen deposition (N) and ozone (O3) exposure (phytotoxic ozone dose, POD) on carbon (C) sequestration by European forest ecosystems for the period 1900-2050. Tree C sequestration was assessed by using empirical response functions, while soil C sequestration was simulated with the process-based model VSD, combined with the RothC model. We evaluated two empirical growth responses to N deposition (linear and non-linear) and two O3 exposure relationships (linear function with total biomass or net annual increment)...
July 19, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28738511/litter-thickness-but-not-root-biomass-explains-the-average-and-spatial-structure-of-soil-hydraulic-conductivity-in-secondary-forests-and-coffee-agroecosystems-in-veracruz-mexico
#16
B E Marín-Castro, S Negrete-Yankelevich, D Geissert
Secondary forests and coffee agroecosystems are considered good alternatives for conservation of a high capacity for water filtration in the soil where tropical montane cloud forests (TMCF) once grew; however, it is not clear which characteristics of the vegetation modulate the field saturated hydraulic conductivity of the soil (Kfs) and whether these characteristics persist in such derived systems. Here, we explore how changes in vegetation between secondary forests and coffee agroecosystems have consequences for the average value and spatial variation of litter thickness and root biomass, and whether these differences can explain the Kfs and its spatial distribution...
July 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28738509/ambient-sediment-quality-conditions-in-minnesota-lakes-usa-effects-of-watershed-parameters-and-aquatic-health-implications
#17
Judy L Crane
Surficial sediments were collected from 50 randomly selected Minnesota lakes, plus four a priori reference lakes, in 2007. The lakes encompassed broad geographic coverage of the state and included a variety of major land uses in the surrounding watersheds. Sediment samples were analyzed for a suite of metals, metalloids, persistent organic pollutants, total organic carbon, and particle size fractions. In addition, a small fish survey was conducted to assess PBDEs in both whole fish and fish tissues. Sediment quality in this set of lakes ranged from good (43%) to moderate (57%) based on an integrative measure of multiple contaminants...
July 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28738508/modelling-of-airborne-particulate-matter-concentration-in-underground-stations-using-a-two-size-class-conservation-model
#18
E Walther, M Bogdan, R Cohen
This study presents an attempt of predictive modelling of airborne particulate matter in underground railway stations. The aerosol is represented by a set of simple, ordinary differential equations that describe apparent emission of two particles size-classes in relation with train traffic, ventilation and deposition. The parameters of the equations are identified numerically by a genetic algorithm and comply with their respective expected order of magnitude. A quantitative comparison of numerical results with experimental data from Paris underground station exhibits a good accordance...
July 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28738505/rethinking-aqueous-phase-diffusion-related-isotope-fractionation-contrasting-theoretical-effects-with-observations-at-the-field-scale
#19
Shu Xu, Barbara Sherwood Lollar, Brent E Sleep
Aqueous phase diffusion-related isotope fractionation (DRIF) was investigated through modelling to determine under what subsurface conditions carbon isotope DRIF effects would be observable using typical sampling approaches. A dispersive enrichment factor was defined based on heavy and light isotopologue dispersion coefficients. For a given ratio of source concentration (C0) to method detection limit (MDL), the maximum DRIF in a system increased linearly with transverse dispersive enrichment factor. Using this linear relationship, the critical dispersion enrichment factor for which DRIF would not be observable was quantified...
July 18, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28738481/-progress-in-research-of-relationship-between-ambient-air-pm-2-5-and-lung-diseases
#20
Y Xia, L Fan, Y Guan, S Y Liu, Y Xiao
Fine Particulate Matter (PM(2.5)-particles with an aerodynamic diameter ≤2.5 μm) can penetrate deeply into the lung, deposit in the alveoli, and consequently impair lung function. Both short term and long term exposures to PM(2.5) are associated with the incidence of respiratory diseases (e.g. asthma, chronic obstructive pulmonary disease, lung cancer). This paper summarizes the effects of ambient air PM(2.5) exposure on human respiratory system revealed by epidemiological studies.
July 10, 2017: Zhonghua Liu Xing Bing Xue za Zhi, Zhonghua Liuxingbingxue Zazhi
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