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Second-order Calibration

Ana L Pérez, Giuliana Tibaldo, Germán H Sánchez, Gabriel G Siano, Nilda R Marsili, Agustina V Schenone
We report the development of a new analytical method for the quantification of N-(phosphonomethyl)glycine (glyphosate) and (aminomethyl)phosphonic acid (AMPA) by combining spectrofluorimetry and multivariate calibration. In this study, fluorescence spectroscopy was used to quantify glyphosate and AMPA, which were previously derivatized with the fluorogenic reagent: 4-chloro-7-nitrobenzofurazan (NBD-Cl). Fluorescence excitation-emission matrices (EEM) were recorded by exciting between 400 and 500 nm, and measuring the emission between 500 and 610 nm...
January 31, 2019: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Chenyun Dai, Stephane Martel, Francois Martel, Denis Rancourt, Edward A Clancy
Joint mechanical impedance is commonly measured by applying dynamic perturbations about a joint at a fixed operating point/background torque, and quantifying torque change vs. angle change. Impedance characterization in functional tasks, therefore, requires multiple experimental trials over a range of operating points-a cumbersome, invasive, time-consuming and impractical task. As an alternative, studies have related EMG to impedance, after which EMG can estimate impedance without applying joint perturbations...
February 8, 2019: Journal of Electromyography and Kinesiology
Maira D Carabajal, Juan A Arancibia, Graciela M Escandar
The endocrine disrupting chemicals bisphenol A (BPA) and 4-nonylphenol (NP) were simultaneously quantified through third-order/four-way calibration. Excitation-emission fluorescence matrix-kinetic (EEFM-K) third-order data were generated by measuring the EEFMs of these priority xenoestrogens as a function of reaction time during their Fenton degradation. Third-order/four-way calibration notably improves the sensitivity of the method and provides the required selectivity for quantifying analytes with critically overlapped fluorescence signals...
May 15, 2019: Talanta
Chao Kang, Hai-Long Wu, Min-Li Xu, Xiu-Fang Yan, Ya-Juan Liu, Ru-Qin Yu
The simultaneous quantitative analysis of intracellular metabolic coenzymes flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) is of interest because they participate in many electron-transfer reactions of metabolism. But, the simultaneous quantitative analysis of FAD and FMN is hard to be achieved by traditional analytical methods. This paper proposes a novel strategy of intrinsic fluorescence coupled with four-way calibration method for simultaneous quantitative analysis of intracellular metabolic coenzymes FAD and FMN...
May 15, 2019: Talanta
Russell T Baker, Damon Burton, Michael A Pickering, Amanda Start
CONTEXT: The Disablement in the Physically Active (DPA) Scale is a patient-reported outcome instrument recommended for use in clinical practice and research. Analysis of the scale has indicated a need for further psychometric testing. OBJECTIVE: To assess the model fit of the original DPA Scale using a larger and more diverse sample and explore the potential for a short-form (SF) version. DESIGN: Observational study. SETTING: Twenty-four clinical settings...
February 11, 2019: Journal of Athletic Training
Yana Zlateva, Bryan R Muir, Jan P Seuntjens, Issam El Naqa
PURPOSE: Cherenkov emission (CE) is ubiquitous in external radiotherapy. It is also unique in that it carries the promise of 3D micrometer-resolution perturbation-free in-water dosimetry with a beam quality-independent detector response calibration. Our aim is to bring CE-based dosimetry into the clinic and we motivate this here with electron beams. We Monte Carlo-calculate and characterize broad-beam CE-to-dose conversion factors in water for a clinically representative library of electron beam qualities, address beam quality specification and reference depth selection, and develop a preliminary uncertainty budget based on our Monte Carlo results and relative experimental work of a companion study (Paper I)...
January 31, 2019: Medical Physics
Dong Hu, Renfu Lu, Yibin Ying, Xiaping Fu
This research was conducted to estimate the optical absorption and reduced scattering coefficients of two-layer turbid media using a stepwise method from the spatial-frequency domain reflectance generated by Monte Carlo (MC) simulation. The stepwise method's feasibility for optical property estimations was first investigated by comparing the reflectance generated by the diffusion model and MC simulation for one-layer and two-layer turbid media. The results showed that, with proper frequency selection, the one-layer model could be used for estimating the optical properties of the first layer of the two-layer turbid media...
January 21, 2019: Optics Express
Graciela M Escandar, Alejandro C Olivieri
This review discusses recent advances in both theory and experiment regarding multi-way chromatographic calibration. The focus is directed towards the chemometric processing of multi-way data arrays in which one or more instrumental modes describe the elution time behavior across liquid or gas chromatographic columns, and the remaining ones are of spectroscopic nature, e.g. UV-vis absorption, fluorescence emission (either as vectors or matrices) or mass spectrometry. Successful multi-way data decomposition into profiles for the contributing components allows one to perform quantitative analysis of complex samples...
January 9, 2019: Journal of Chromatography. A
Françoise Viallefont-Robinet, Dennis Helder, Renaud Fraisse, Amy Newbury, Frans van den Bergh, DongHan Lee, Sébastien Saunier
A sensor's spatial resolution has traditionally been a difficult concept to define, but all would agree that it is inextricably linked to the Ground Sampling Distance (GSD) and Instantaneous Field of View (IFOV) of an imaging sensor system. As a measure of the geospatial quality of imagery, the Modulation Transfer Function (MTF) of the system is often used along with the signal-to-noise ratio (SNR). However, their calculation is not fully standardized. Further, consistent measurements and comparisons are often hard to obtain...
December 24, 2018: Optics Express
Barbara Feist, Michal Pilch, Jacek Nycz
Graphene oxide (GO) was chemically functionalized with 5-amino-1,10-phenanthroline. The resulting conjugate (phen-GO) was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The experiments show that phen-GO has a high affinity for extraction of Pb(II) ions. Isotherms and kinetics fit the Langmuir model and pseudo-second-order equations. By using phen-GO as a sorbent, Pb(II) ions can be quantitatively adsorbed at pH 6.0. The adsorption capacity is 548 mg g-1 . Following desorption with 2 mol L-1 HNO3 , Pb(II) was quantified by inductively coupled plasma optical emission spectrometry...
January 10, 2019: Mikrochimica Acta
O Ye Rodionova, A V Titova, N A Demkin, K S Balyklova, A L Pomerantsev
The ultimate goal of the study is to present a method of authentication of hard-shell capsules of medicines packed in polyvinylchloride (PVC) blisters without damaging the primary packaging. This is done by collecting NIR spectra in a non-invasive mode and subsequent analysis of measurements by a one-class classification procedure. The first part of the study demonstrates that NIR spectra collected through a PVC blister and capsule shell do carry information about the medication itself. Firstly, this is done by visual inspection of spectra of the sample, its interfering layers and main pharmaceutical ingredients...
April 1, 2019: Talanta
Lin Tan, Yan Zhang, Qin Yang, Nan Chen, Wen Du, Li-Juan Tang, Jian-Hui Jiang, Ru-Qin Yu
Fluorescent probes have been valuable tools for bioanalytical multiplex assays. However, as a common phenomenon in multiplex fluorescence assays, spectral overlap usually leads to difficulty in spectral analysis for multiple analytes. Although multiway calibrations have provided mathematic approaches for complex spectral analysis, it remains a grand challenge for these methods in practical applications because of the problems such as prior rank estimation. Herein, we report a novel second-order calibration algorithm of alternating residual trilinearization (ART) for the decomposition of complex spectra generated from multiplex fluorescence assays...
April 1, 2019: Talanta
Marine Lorent, Haïfa Maalmi, Philippe Tessier, Stéphane Supiot, Etienne Dantan, Yohann Foucher
BACKGROUND: The Cancer of the Prostate Risk Assessment (CAPRA) score was designed and validated several times to predict the biochemical recurrence-free survival after a radical prostatectomy. Our objectives were, first, to study the clinical validity of the CAPRA score, and, second, to assess its clinical utility for stratified medicine from an original patient-centered approach. METHODS: We proposed a meta-analysis based on a literature search using MEDLINE. Observed and predicted biochemical-recurrence-free survivals were compared to assess the calibration of the CAPRA score...
January 7, 2019: BMC Medical Informatics and Decision Making
Liqiang He, Jingnan Hu, Liuhanzi Yang, Zhenhua Li, Xuan Zheng, Shuxia Xie, Lei Zu, Junhui Chen, Yuan Li, Ye Wu
Mileage of taxi fleets is significantly higher than regular passenger vehicles in China, which might trigger greater tailpipe emissions of air pollutants. To investigate their real-world gaseous emissions, we applied portable emissions measurement systems (PEMSs) to test 44 gasoline and 24 bi-fuel taxis in seven cities. Our real-world measurement results indicated that a major part of the tested China 3 and China 4 gasoline taxis, especially the samples with high mileage (>300,000 km), far exceeded the corresponding emission limits of NOX , THC and CO...
December 24, 2018: Science of the Total Environment
Milagros Montemurro, Romina Brasca, María J Culzoni, Héctor C Goicoechea
A novel method for the determination of pirimiphos-methyl (PMM) in maize grains by fluorescence spectroscopy and three-way calibration was developed. The formation of supramolecular complexes and their effect on the luminescence properties of PMM were studied. A solvent extraction step followed by solid phase extraction for sample clean-up was optimized. A chemometric approach consisting in PARAFAC as second-order data processing tool and piecewise direct standardization (PDS) for reducing the complexity of the calibration process was developed to overcome the matrix effect...
April 25, 2019: Food Chemistry
Max Nimmer, Gabriele Steidl, Rainer Riesenberg, Andreas Wuttig
We present a variational approach to reconstruct a multispectral image from an array of diffraction patterns captured in one monochromatic image. The mathematical model relies on the superposition of wavelength dependent calibration diffraction patterns and a spectral regularization with second order differences. The necessary preprocessing steps which influence the mathematical setting are discussed in detail. For computing a minimizer of our model we propose an active set method with model specific modifications...
October 29, 2018: Optics Express
Gareth D Lewis, Patrick Merken, Marijke Vandewal
In this paper, we demonstrate an improvement in the accuracy of a low-cost smart temperature sensor, by measurement of the nonlinear curvature correction at multiple temperature references. The sensors were positioned inside a climate chamber and connected outside to a micro-controller via a network cable. The chamber temperature was increased systematically over a wide range from -20 °C to 55 °C. A set of calibration curves was produced from the best fitting second-order polynomial curves for the offset in temperature between the sensor and reference...
November 22, 2018: Sensors
Shutao Wang, Qi Cheng, Yuanyuan Yuan, Changbing Wang, Shuangna Ma
Methanol gasoline, known as a new energy, has a certain degree of damage to automobile. The aim of this work was to identify and quantify the methanol in methanol gasoline using three-dimensional fluorescence spectroscopy technique combined with second order chemometric methods. Parallel factor analysis (PARAFAC) and self-weighted alternating trilinear decomposition (SWATLD) methods were used to analyse artificial samples. However, the obtained results by PARAFAC were not satisfactory. On the other hand, excellent prediction results were obtained when SWATLD model was applied, with recovery rate between 98...
November 15, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Zakriya Mohammed, Ibrahim Abe M Elfadel, Mahmoud Rasras
With the continuous advancements in microelectromechanical systems (MEMS) fabrication technology, inertial sensors like accelerometers and gyroscopes can be designed and manufactured with smaller footprint and lower power consumption. In the literature, there are several reported accelerometer designs based on MEMS technology and utilizing various transductions like capacitive, piezoelectric, optical, thermal, among several others. In particular, capacitive accelerometers are the most popular and highly researched due to several advantages like high sensitivity, low noise, low temperature sensitivity, linearity, and small footprint...
November 16, 2018: Micromachines
Felix Leeb, Lutz Maibaum
We study the effect of cholesterol on the structure of dipalmitoylphosphatidylcholine phospholipid bilayers. Using extensive molecular dynamics computer simulations at atomistic resolution, we observe and quantify several structural changes upon increasing cholesterol content that are collectively known as the condensing effect: a thickening of the bilayer, an increase in lipid tail order, and a decrease in lateral area. We also observe a change in leaflet interdigitation and a lack thereof in the distributions of dipalmitoylphosphatidylcholine headgroup orientations...
November 2, 2018: Biophysical Journal
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