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Second-order Calibration

Jianli Liu, Rui Zhang, Xiaotian Li, Jianjun Chen, Jianan Liu, Jun Qiu, Xun Gao, Jicheng Cui, Bayan Heshig
This work presents a method that can automatically estimate and remove varying continuous background emission for low-cost laser-induced breakdown spectroscopy (LIBS) without intensified CCD. The algorithm finds all third-order minima points in spectra and uses these points to partition the spectra into multiple subintervals. The mean value is then used as a threshold to select the effective points for the second-order minima in each subinterval. Finally, a linear interpolation method is used to realize extension of these effective points and complete fitting of the background using polynomials...
June 25, 2018: Optics Express
Ragaa Magdy, A Hemdan, N V Fares, Maha Farouk
Trandolapril has no sharp peak in its zero-order spectrum and therefore, it is difficult to be measured by direct spectrophotometry. In this manuscript, several univariate and multivariate spectrophotometric methods were developed and validated for determination of Trandolapril (TR) and Verapamil (VR) combination. The first method for measuring Trandolapril is Constant Multiplication-Spectrum Subtraction (CM-SS), where Trandolapril was measured at 210 nm in its zero-order curve after elimination of Verapamil spectrum...
August 6, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Roberto Grilli, Jack Triest, Jerome Chappellaz, Michel Calzas, Thibault Desbois, Pär Jansson, Christophe Guillerm, Bénédicte Ferré, Loic Lechevallier, Victor Ledoux, Daniele Romanini
We present a novel instrument, the Sub-Ocean probe, allowing in situ and continuous measurements of dissolved methane in seawater. It relies on an optical feedback cavity enhanced absorption technique designed for trace gas measurements and coupled to a patent-pending sample extraction method. The considerable advantage of the instrument compared with existing ones lies in its fast response time of the order of 30 seconds, that makes this probe ideal for fast and continuous 3D-mapping of dissolved methane in water...
August 16, 2018: Environmental Science & Technology
Dieter Lütjohann, Ingemar Björkhem, Silvia Friedrichs, Anja Kerksiek, Wolf-Jochen Geilenkeuser, Anita Lövgren-Sandblom, Diana Ansorena, Iciar Astiasarán, Lucía Baila-Rueda, Blanca Barriuso, Lionell Bretillon, Richard W Browne, Claudio Caccia, Ana Cenarro, Peter J Crick, Günter Fauler, Guadalupe García-Llatas, William J Griffiths, Luigi Iuliano, María Jésus Lagarda, Valerio Leoni, Ana Maria Lottenberg, Silke Matysik, Jeff McDonald, Todd C Rideout, Gerd Schmitz, Valéria Sutti Nunes, Yuqin Wang, Chiara Zerbinati, Ulf Diczfalusy, Hans-Frieder Schött
Increasing numbers of laboratories develop new methods based on gas-liquid and high-performance liquid chromatography to determine serum concentrations of oxygenated cholesterol metabolites such as 7α-, 24(S)-, and 27-hydroxycholesterol. We initiated a first international descriptive oxycholesterol (OCS) survey in 2013 and a second interventional survey 2014 in order to compare levels of OCS reported by different laboratories and to define possible sources of analytical errors. In 2013 a set of two lyophilized serum pools (A and B) was sent to nine laboratories in different countries for OCS measurement utilizing their own standard stock solutions...
July 29, 2018: Biochimie
Tamar Guy-Haim, Noa Simon-Blecher, Amos Frumkin, Israel Naaman, Yair Achituv
Background: Aquatic subterranean species often exhibit disjunct distributions, with high level of endemism and small range, shaped by vicariance, limited dispersal, and evolutionary rates. We studied the disjunct biogeographic patterns of an endangered blind cave shrimp, Typhlocaris , and identified the geological and evolutionary processes that have shaped its divergence pattern. Methods: We collected Typlocaris specimens of three species ( T. galilea , T. ayyaloni , and T...
2018: PeerJ
Karen C B De Freitas
Starting with the Rayleigh charge limiting model, a slightly different approach is used to account for the well-known discrepancy that exists between the said model and experimental ESI MS data for globular proteins. It is shown using published datasets that for globular proteins, the mass density ρ exhibits a weak second-order dependence on its mass M, according to ρ(M)∝ M-α , α ~ 0.14. A direct equivalence established between ESI MS and x-ray techniques suggests a minimum but critical surface tension of 15...
July 24, 2018: Journal of the American Society for Mass Spectrometry
Zhe Yang, Tingting Liu, Yutian Wang, Yuanyuan Yuan, Fengkai Shang
Interference-free determination of polycyclic aromatic hydrocarbons (PAHs) in water pollution is proposed based on third-order correction algorithms with quadrilinear component modeling applied to the constructed four way fluorescence excitation-emission-sample data array with higher accuracy and better predictive ability than second-order (three-dimension) correction. Alternating weighted residue constraint quadrilinear decomposition (AWRCQLD), quadrilinear parallel factor analysis (4-PARAFAC), alternate penalty quadrilinear decomposition (APQLD) and alternate penalty trilinear decomposition (APTLD) are applied to acenaphthene (ANA), naphthalene (NAP) and fluorene (FLU) respectively...
July 18, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Mahdiyeh Ghaffari, Alejandro C Olivieri, Hamid Abdollahi
A novel procedure is described for processing the second-order data matrices with multivariate curve resolution-alternating least-squares; while the data set is nontrilinear and severe profile overlapping occurs in the instrumental data modes. The area of feasible solutions can be reduced to a unique solution by including/considering the area correlation constraint, besides the traditional constraints (i.e., non-negativity, unimodality, species correspondence, etc.). The latter is implemented not only for the unknown samples but also for all calibration samples, regardless of their interferent content...
August 7, 2018: Analytical Chemistry
Elísabet Martín Tornero, Anunciación Espinosa-Mansilla, Arsenio Muñoz de la Peña, Isabel Durán Merás
Phenanthrene is the most released polycyclic aromatic hydrocarbon into the environment by anthropogenic action. Because of the absorption and biotransformation pathways, this compound is metabolized and the most abundant metabolites are hydroxylated derivatives, such as 1-, 2-, 3-, 4- and 9-hydroxyphenanthrene, which are excreted through biological fluids, included mammals milk. For the resolution and quantitation of co-eluted analytes, elution time-emission fluorescence matrices were analysed with different second-order calibration algorithms: n-way and unfolded partial least squares, both coupled with residual bilinearization (N-PLS/RBL and U-PLS/RBL), and multivariate curve resolution-alternative least squares (MCR-ALS)...
October 1, 2018: Talanta
Xiao-Li Yin, Hui-Wen Gu, Qiao Wu, Tian-Qin Peng, Shan-Hui Zhang, Yang Liu
In this work, high-performance liquid chromatography with diode array detection was applied for the simultaneous determination of andrographolide and dehydroandrographolide in Andrographis paniculata and its preparations. As a result of the incomplete baseline separation caused by complex backgrounds, the classical univariate calibration method failed to determine accurate contents of the analytes. On this occasion, chemometric second-order calibration based on the well-known alternating trilinear decomposition algorithm was then explored to serve as a post-experimental remedial tool to solve this problem...
July 16, 2018: Journal of Separation Science
Huan Lu, Zhiyong Suo, Zhenfang Li, Jinwei Xie, Jiwei Zhao, Qingjun Zhang
For Interferometry Synthetic Aperture Radar (InSAR), the normal baseline is one of the main factors that affects the accuracy of the ground elevation. For Gaofen-3 (GF-3) InSAR processing, the poor accuracy of the real-time orbit determination results in a large baseline error, leads to a modulation error in azimuth and a slope error in the range for timely Digital Elevation Model (DEM) generation. In order to address this problem, a novel baseline estimation approach based on Shuttle Radar Topography Mission (SRTM) DEM is proposed in this paper...
July 4, 2018: Sensors
Yu Li, Fan Xu, Fa Zhang, Pingyong Xu, Mingshu Zhang, Ming Fan, Lihua Li, Xin Gao, Renmin Han
Motivation: Super-resolution fluorescence microscopy with a resolution beyond the diffraction limit of light, has become an indispensable tool to directly visualize biological structures in living cells at a nanometer-scale resolution. Despite advances in high-density super-resolution fluorescent techniques, existing methods still have bottlenecks, including extremely long execution time, artificial thinning and thickening of structures, and lack of ability to capture latent structures...
July 1, 2018: Bioinformatics
Yue-Yue Chang, Hai-Long Wu, Huan Fang, Tong Wang, Zhi Liu, Yang-Zi Ouyang, Yu-Jie Ding, Ru-Qin Yu
In this study, a smart and green analytical method based on the second-order calibration algorithm coupled with excitation-emission matrix (EEM) fluorescence was developed for the determination of rhodamine dyes illegally added into chilli samples. The proposed method not only has the advantage of high sensitivity over the traditional fluorescence method but also fully displays the "second-order advantage". Pure signals of analytes were successfully extracted from severely interferential EEMs profiles via using alternating trilinear decomposition (ATLD) algorithm even in the presence of common fluorescence problems such as scattering, peak overlaps and unknown interferences...
June 15, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Amélie Mathieu, Tiphaine Vidal, Alexandra Jullien, QiongLi Wu, Camille Chambon, Benoit Bayol, Paul-Henry Cournède
Background and Aims: Functional-structural plant models (FSPMs) describe explicitly the interactions between plants and their environment at organ to plant scale. However, the high level of description of the structure or model mechanisms makes this type of model very complex and hard to calibrate. A two-step methodology to facilitate the calibration process is proposed here. Methods: First, a global sensitivity analysis method was applied to the calibration loss function...
June 19, 2018: Annals of Botany
Agisilaos Chantzis, Joanna K Kowalska, Dimitrios Maganas, Serena DeBeer, Frank Neese
In this study, a detailed calibration of the performance of modern ab initio wave function methods in the domain of X-ray absorption spectroscopy (XAS) is presented. It has been known for some time that for a given level of approximation, for example, using time-dependent density functional theory (TD-DFT) in conjunction with a given basis set, there are systematic deviations of the calculated transition energies from their experimental values that depend on the functional, the basis set, and the chosen treatment of scalar relativistic effects...
July 10, 2018: Journal of Chemical Theory and Computation
Mouhannad Ali, Fadi Al Machot, Ahmad Haj Mosa, Midhat Jdeed, Elyan Al Machot, Kyandoghere Kyamakya
Machine learning approaches for human emotion recognition have recently demonstrated high performance. However, only/mostly for subject-dependent approaches, in a variety of applications like advanced driver assisted systems, smart homes and medical environments. Therefore, now the focus is shifted more towards subject-independent approaches, which are more universal and where the emotion recognition system is trained using a specific group of subjects and then tested on totally new persons and thereby possibly while using other sensors of same physiological signals in order to recognize their emotions...
June 11, 2018: Sensors
Nicola Dinapoli, Brunella Barbaro, Roberto Gatta, Giuditta Chiloiro, Calogero Casà, Carlotta Masciocchi, Andrea Damiani, Luca Boldrini, Maria Antonietta Gambacorta, Michele Dezio, Gian Carlo Mattiucci, Mario Balducci, Johan van Soest, Andre Dekker, Philippe Lambin, Claudio Fiorino, Carla Sini, Francesco De Cobelli, Nadia Di Muzio, Calogero Gumina, Paolo Passoni, Riccardo Manfredi, Vincenzo Valentini
PURPOSE: The objective of this study is finding an intensity based histogram (IBH) signature to predict pathologic complete response (pCR) probability using only pre-treatment magnetic resonance (MR) and validate it externally in order to create a workflow for the external validation of an MR IBH signature and to apply the model out of the environment where it has been tuned. The impact of pCR and the final predictors on the survival outcome were also evaluated. METHODS AND MATERIALS: Three centers using different MR scanners were involved in this retrospective study...
May 4, 2018: International Journal of Radiation Oncology, Biology, Physics
Wan-Jun Long, Hai-Long Wu, Tong Wang, Li-Xia Xie, Yong Hu, Huan Fang, Li Cheng, Yu-Jie Ding, Ru-Qin Yu
A smart chemometrics-assisted strategy that combines the full scan mode of liquid chromatography with mass spectrometry with second-order calibration method based on alternating trilinear decomposition algorithm was developed for the rapid determination of 15 glucocorticoids including the epimers betamethasone and dexamethasone illegally added into face masks. Fifteen glucocorticoids were rapidly eluted (11 min) under a simple elution program. By means of the second-order calibration method, 15 target analytes were successfully quantified in the presence of peak overlaps, unknown interferences and baseline drifts...
June 8, 2018: Journal of Separation Science
Conner C Harper, Andrew G Elliott, Haw-Wei Lin, Evan R Williams
A general method for in situ measurements of the energy of individual ions trapped and weighed using charge detection mass spectrometry (CDMS) is described. Highly charged (> 300 e), individual polyethylene glycol (PEG) ions are trapped and oscillate within an electrostatic trap, producing a time domain signal. A segmented Fourier transform (FT) of this signal yields the temporal evolution of the fundamental and harmonic frequencies of ion motion throughout the 500-ms trap time. The ratio of the fundamental frequency and second harmonic (HAR) depends on the ion energy, which is an essential parameter for measuring ion mass in CDMS...
June 2, 2018: Journal of the American Society for Mass Spectrometry
Joern Kuchenbecker
BACKGROUND: Pseudoisochromatic colour plates are constructed according to specific principles. They can be very different in quality. To check the diagnostic quality, they have to be tested on a large number of subjects, but this procedure is can be tedious and expensive. Therefore, the use of a standardised web-based test is recommended. METHODS: Eight Pflüger trident colour plates (including 1 demo plate) according to the Velhagen edition of 1980 were digitised and inserted into a web-based colour vision test (www...
May 22, 2018: Klinische Monatsblätter Für Augenheilkunde
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