Read by QxMD icon Read

Second-order Calibration

Yongsheng Hong, Ruili Shen, Hang Cheng, Yiyun Chen, Yong Zhang, Yaolin Liu, Min Zhou, Lei Yu, Yi Liu, Yanfang Liu
Heavy metal contamination of peri-urban agricultural soil is detrimental to soil environmental quality and human health. A rapid assessment of soil pollution status is fundamental for soil remediation. Heavy metals can be monitored by visible and near-infrared spectroscopy coupled with chemometric models. First and second derivatives are two commonly used spectral preprocessing methods for resolving overlapping peaks. However, these methods may lose the detailed spectral information of heavy metals. Here, we proposed a fractional-order derivative (FOD) algorithm for preprocessing reflectance spectra...
October 1, 2018: Science of the Total Environment
Tie Liu, Xiao-Na An, De-Long Liu, Yong-Ju Wei
This work presents a greener approach for simultaneous determination of neomangiferin and mangiferin, the major bioactive constituents with severe spectral overlapping in Anemarrhenae Rhizoma, combining the sensitivity of molecular fluorescence and the selectivity of chemometric multivariate calibration algorithms. In this study, we compared the analytical performance of two group chemometric algorithms including trilinear algorithms such as parallel factor analysis (PARAFAC), alternating trilinear decomposition (ATLD), self-weighted alternating trilinear decomposition (SWATLD) and alternating penalized trilinear decomposition (APTLD), and PLS-based methods such as unfolded partial least-squares or the multi-dimensional partial least-squares, both combined with residual bilinearization (U-PLS/RBL, N-PLS/RBL)...
October 2, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Samaneh Fooladi, Tribikram Kundu
The Distributed Point Source Method (DPSM) is a modeling technique based on superposition of fundamental solutions corresponding to individual pair of source and target points. A collection of source points distributed over the boundaries and interfaces are responsible for transmission, reflection, and refraction of acoustic waves in the solution domain. The strength of the source points may not be known a priory. By imposing the prescribed conditions on the boundaries and interfaces, a system of equations with the source strengths as the unknowns is obtained...
September 7, 2018: Ultrasonics
Xiao-Li Yin, Hui-Wen Gu, Ali R Jalalvand, Ya-Juan Liu, Ying Chen, Tian-Qin Peng
The quantification of preservatives in cosmetics has attracted great attentions for their controversial and widespread use. HPLC is a prevailing method for preservatives determination among various analytical methods. However, it takes long time to fully separate these compounds because of the complexity of cosmetic matrices. In this study, a fast and green HPLC-DAD strategy assisted with second-order multivariate calibration methods based on alternating trilinear decomposition (ATLD) and multivariate curve resolution-alternating least squares (MCR-ALS) was developed for the simultaneous determination of eight selected preservatives in complex facial mask samples...
October 26, 2018: Journal of Chromatography. A
Carlo De Michele, Francesco Avanzi
Maximum annual daily precipitation is a fundamental hydrologic variable that does not attain asymptotic conditions. Thus the classical extreme value theory (i.e., the Fisher-Tippett's theorem) does not apply and the recurrent use of the Generalized Extreme Value distribution (GEV) to estimate precipitation quantiles for structural-design purposes could be inappropriate. In order to address this issue, we first determine the exact distribution of maximum annual daily precipitation starting from a Markov chain and in a closed analytical form under the hypothesis of stochastic independence...
September 21, 2018: Scientific Reports
Hamed Heydari, Navid Cheraghi Kazerooni, Mojtaba Zolfaghari, Majid Ghoreishi, Vahid Tahmasbi
Bone drilling process is a prominent step of internal fixation in orthopedic surgeries. Process forces, leading to chip production, produce heat in the vicinity of the drilled bore and increase the probability of necrosis phenomenon. In this article, an analytical model to predict process temperature is presented based on Sui and Sugita model. This heat transfer model is the combination of a heat equilibrium equation for tool-chip system and a heat distribution equation for the bone itself where heat generation in tool's tip is due to cutting frictional forces...
September 2018: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
Mirta R Alcaraz, Ezequiel Morzán, Cecilia Sorbello, Héctor C Goicoechea, Roberto Etchenique
In this work, a direct in-flow methodology for the acquisition of excitation-emission fluorescence matrices is presented. The system is particularly suited for measurements in the order of tens of milliseconds. A light source operated in continuous mode is dispersed through a grating and focused onto a square-section capillary. Under the spatially resolved excitation, the emission is collected, dispersed through a second grating and further focused onto a CCD array sensor. To allow the wavelength accuracy, a spectral calibration was performed registering the scattering signal of a dispersive element using interference filters ranging from 340 nm to 740 nm...
November 22, 2018: Analytica Chimica Acta
Jingheng Ning, Quanguo He, Xin Luo, Min Wang, Donglin Liu, Jianhui Wang, Jun Liu, Guangli Li
A facile cuprous oxide nanoparticles functionalized electro-reduced graphene oxide modified glassy carbon electrode (denoted as Cu₂O NPs-ERGO/GCE) was fabricated via a simple physical adsorption and electrochemical reduction approach. Cyclic voltammetry and second-order derivative linear scan voltammetry were used to investigate the electrocatalysis oxidation of vanillin on the Cu₂O NPs-ERGO/GCE. The compound yielded a well-defined voltammetric response in 0.1 M H₂SO₄ at 0.916 V (vs. saturated calomel electrode (SCE))...
August 22, 2018: Sensors
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, Jérôme Chappellaz, Michel Calzas, Thibault Desbois, Pär Jansson, Christophe Guillerm, Bénédicte Ferré, Loïc 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 s, that makes this probe ideal for fast and continuous 3D-mapping of dissolved methane in water...
September 18, 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...
October 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...
October 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...
December 5, 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 21, 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...
August 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
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"