Loading...
Search for:
multivariant-analysis
0.007 seconds
Total 55 records
Analysis of Iranian rosemary essential oil: Application of gas chromatography-mass spectrometry combined with chemometrics
, Article Journal of Chromatography A ; Volume 1218, Issue 18 , May , 2011 , Pages 2569-2576 ; 00219673 (ISSN) ; Moazeni, R. S ; Sereshti, H ; Sharif University of Technology
Abstract
This paper focuses on characterization of the components of Iranian rosemary essential oil using gas chromatography-mass spectrometry (GC-MS). Multivariate curve resolution (MCR) approach was used to overcome the problem of background, baseline offset and overlapping/embedded peaks in GC-MS. The analysis of GC-MS data revealed that sixty eight components exist in the rosemary essential oil. However, with the help of MCR this number was extended to ninety nine components with concentrations higher than 0.01%, which accounts for 98.23% of the total relative content of the rosemary essential oil. The most important constituents of the Iranian rosemary are 1,8-cineole (23.47%), α-pinene...
Spectral clustering approach with sparsifying technique for functional connectivity detection in the resting brain
, Article 2010 International Conference on Intelligent and Advanced Systems, ICIAS 2010, 15 June 2010 through 17 June 2010 ; 2010 ; 9781424466238 (ISBN) ; Heidari, A ; Fatemizadeh, E ; Soltanianzadeh, H ; Sharif University of Technology
Abstract
The aim of this study is to assess the functional connectivity from resting state functional magnetic resonance imaging (fMRI) data. Spectral clustering algorithm was applied to the realistic and real fMRI data acquired from a resting healthy subject to find functionally connected brain regions. In order to make computation of the spectral decompositions of the entire brain volume feasible, the similarity matrix has been sparsified with the t-nearestneighbor approach. Realistic data were created to investigate the performance of the proposed algorithm and comparing it to the recently proposed spectral clustering algorithm with the Nystrom approximation and also with some well-known...
Pattern recognition analysis of chromatographic fingerprints of Crocus sativus L. secondary metabolites towards source identification and quality control
, Article Analytical and Bioanalytical Chemistry ; Volume 408, Issue 12 , 2016 , Pages 3295-3307 ; 16182642 (ISSN) ; Sereshti, H ; Parastar, H ; Sharif University of Technology
Springer Verlag
2016
Abstract
Chromatographic fingerprinting is an effective methodology for authentication and quality control of herbal products. In the presented study, a chemometric strategy based on multivariate curve resolution-alternating least squares (MCR-ALS) and multivariate pattern recognition methods was used to establish a gas chromatography-mass spectrometry (GC-MS) fingerprint of saffron. For this purpose, the volatile metabolites of 17 Iranian saffron samples, collected from different geographical regions, were determined using the combined method of ultrasound-assisted solvent extraction (UASE) and dispersive liquid-liquid microextraction (DLLME), coupled with GC-MS. The resolved elution profiles and...
Shuffling multivariate adaptive regression splines and adaptive neuro-fuzzy inference system as tools for QSAR study of SARS inhibitors
, Article Journal of Pharmaceutical and Biomedical Analysis ; Volume 50, Issue 5 , 2009 , Pages 853-860 ; 07317085 (ISSN) ; Asadollahi Baboli, M ; Mani Varnosfaderani, A ; Sharif University of Technology
Abstract
In this work, the inhibitory activity of pyridine N-oxide derivatives against human severe acute respiratory syndrome (SARS) is predicted in terms of quantitative structure-activity relationship (QSAR) models. These models were developed with the aid of multivariate adaptive regression spline (MARS) and adaptive neuro-fuzzy inference system (ANFIS) combined with shuffling cross-validation technique. A shuffling MARS algorithm is utilized to select the most important variables in QSAR modeling and then these variables were used as inputs of ANFIS to predict SARS inhibitory activities of pyridine N-oxide derivatives. A data set of 119 drug-like compounds was coded with over hundred calculated...
QSAR modeling of 1-(3,3-diphenylpropyl)-piperidinyl amides as CCR5 modulators using multivariate adaptive regression spline and bayesian regularized genetic neural networks
, Article QSAR and Combinatorial Science ; Volume 28, Issue 9 , 2009 , Pages 946-958 ; 1611020X (ISSN) ; Mani Varnosfaderani, A ; Sharif University of Technology
2009
Abstract
This study deals with developing a quantitative structure-activity relationship (QSAR) model for describing and predicting the inhibition activity of 1-(3,3-diphenylpropyl)-piperidinyl derivatives as CCR5 modulators. Applying the multiple linear regressions (MLR) and its inability in predicting the inhibition behavior showed that the interaction has no linear characteristics. To assess the nonlinear characteristics of the inhibition activity artificial neural networks (ANN) was used for data modeling. In order to select the variables needed for developing ANNs, three variable selection algorithms were used: Stepwise-MLR, genetic algorithm-partial least squares (GA-PLS), and Bayesian...
Simultaneous detection and identification of thiometon, phosalone, and prothioconazole pesticides using a nanoplasmonic sensor array
, Article Food and Chemical Toxicology ; Volume 151 , 2021 ; 02786915 (ISSN) ; Abbasi Moayed, S ; Ghasemi, F ; Mahdavi, V ; Hormozi Nezhad, M. R ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this work, a colorimetric sensor array has been designed for the identification and discrimination of thiometon (TM) and phosalone (PS) as organophosphate pesticides and prothioconazole (PC) as a triazole pesticide. For this purpose, two different plasmonic nanoparticles including unmodified gold nanoparticles (AuNPs) and unmodified silver nanoparticles (AgNPs) were used as sensing elements. The principle of the proposed strategy relied on the aggregation AuNPs and AgNPs through the cross-reactive interaction between the target pesticides and plasmonic nanoparticles. Therefore, these aggregation-induced UV–Vis spectra changes were utilized to discriminate the target pesticides with the...
Radial basis function-artificial neural network (RBF-ANN) for simultaneous fluorescent determination of cysteine enantiomers in mixtures
, Article Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy ; Volume 261 , 2021 ; 13861425 (ISSN) ; Reza Hormozi Nezhad, M ; Abdollahi, H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The determination of chiral compounds is critically important in chemical and pharmaceutical sciences. Cysteine amino acid is one of the important chiral compounds where each enantiomer (L and D) has different effects on fundamental physiological processes. The unique optical properties of nanoparticles make them a suitable probe for the determination of different analytes. In this work, the water-soluble thioglycolic acid (TGA)-capped cadmium-telluride (CdTe) quantum dots (QDs) were applied as optical nanoprobe for the simultaneous determination of cysteine enantiomers. The difference in the kinetics of the interactions between L- and D-cysteine with CdTe QDs is used for multivariate...
Elimination of chromatographic and mass spectrometric problems in GC-MS analysis of Lavender essential oil by multivariate curve resolution techniques: Improving the peak purity assessment by variable size moving window-evolving factor analysis
, Article Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences ; Volume 983-984 , 2015 , Pages 83-89 ; 15700232 (ISSN) ; Moazeni Pourasil, R. S ; Sereshti, H ; Sharif University of Technology
Abstract
In analysis of complex natural matrices by gas chromatography-mass spectrometry (GC-MS), many disturbing factors such as baseline drift, spectral background, homoscedastic and heteroscedastic noise, peak shape deformation (non-Gaussian peaks), low S/N ratio and co-elution (overlapped and/or embedded peaks) lead the researchers to handle them to serve time, money and experimental efforts. This study aimed to improve the GC-MS analysis of complex natural matrices utilizing multivariate curve resolution (MCR) methods. In addition, to assess the peak purity of the two-dimensional data, a method called variable size moving window-evolving factor analysis (VSMW-EFA) is introduced and examined. The...
Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry
, Article Journal of Chromatography A ; Volume 1413 , September , 2015 , Pages 117-126 ; 00219673 (ISSN) ; Sereshti, H ; Parastar, H ; Sharif University of Technology
Elsevier
2015
Abstract
In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9 μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a...
Metabolomics diagnostic approach to mustard airway diseases: A preliminary study
, Article Iranian Journal of Basic Medical Sciences ; Volume 21, Issue 1 , 2018 , Pages 59-69 ; 20083866 (ISSN) ; Aliannejad, R ; Oskouie, A. A ; Tavirani, M. R ; Kalantari, S ; Naseri, M. T ; Baghban, A. A ; Parastar, H ; Aliakbarzadeh, G ; Sharif University of Technology
Mashhad University of Medical Sciences
2018
Abstract
Objective(s): This study aims to evaluate combined proton nuclear magnetic resonance (1H NMR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) metabolic profiling approaches, for discriminating between mustard airway diseases (MADs) and healthy controls and for providing biochemical information on this disease. Materials and Methods: In the present study, analysis of serum samples collected from 17 MAD subjects and 12 healthy controls was performed using NMR. Of these subjects, 14 (8 patients and 6 controls) were analyzed by GC-MS. Then, their spectral profiles were subjected to principal component analysis (PCA) and orthogonal partial least squares regression discriminant...
Gas chromatographic fingerprint analysis of secondary metabolites of Stachys lanata (Stachys byzantine C. Koch) combined with antioxidant activity modelling using multivariate chemometric methods
, Article Journal of Chromatography A ; Volume 1602 , 2019 , Pages 432-440 ; 00219673 (ISSN) ; Abtahi, M ; Parastar, H ; Sharif University of Technology
Elsevier B.V
2019
Abstract
S. lanata has been traditionally used as a medicinal plant due to its various biological activities such as antioxidant activity. Therefore, identification and quality control studies of this plant are of great importance. To this end, gas chromatography (GC) combined with chemometrics was proposed for fingerprint analysis of S. lanata samples. This study sought to classify GC fingerprints of twenty-eight S. lanata samples from eight different regions of Iran and more importantly, to correlate fingerprints to the antioxidant activity to select S. lanata volatile antioxidant markers. S. lanata samples were classified into five and three classes using partial least squares-discriminant...
Association of glomerular and tubular dysfunction with glycaemic control, lipid, lipoprotein, apolipoprotein and antioxidant status in type 2 diabetes mellitus
, Article Singapore Medical Journal ; Volume 48, Issue 9 , 2007 , Pages 840-846 ; 00375675 (ISSN) ; Djalali, M ; Siassi, F ; Farvid, S. S ; Sharif University of Technology
Singapore Medical Association
2007
Abstract
Introduction: This study was conducted to investigate the relationship of glomerular and tubular dysfunctions with glycaemic control, lipid, lipoprotein, apolipoproteins and antioxidant status in 72 patients with type 2 diabetes mellitus. Methods: Urine albumin concentration was measured by immunoturbidimetric and urine N-acetyl-beta-D-glucosaminidase (NAG) and alanine aminopeptidase (AAP) activities with colorimetric methods. Glycated haemoglobin was measured using affinity chromatography. Erythrocyte glu ta thione reductase and glutathione peroxidase activities and serum levels of malondialdehyde, lipids, lipoproteins and apolipoproteins were determined in patients with type 2 diabetes...
Chromatographic fingerprint analysis of secondary metabolites in citrus fruits peels using gas chromatography-mass spectrometry combined with advanced chemometric methods
, Article Journal of Chromatography A ; Volume 1251 , 2012 , Pages 176-187 ; 00219673 (ISSN) ; Jalali Heravi, M ; Sereshti, H ; Mani Varnosfaderani, A ; Sharif University of Technology
2012
Abstract
Multivariate curve resolution (MCR) and multivariate clustering methods along with other chemometric methods are proposed to improve the analysis of gas chromatography-mass spectrometry (GC-MS) fingerprints of secondary metabolites in citrus fruits peels. In this way, chromatographic problems such as baseline/background contribution, low S/N peaks, asymmetric peaks, retention time shifts, and co-elution (overlapped and embedded peaks) occurred during GC-MS analysis of chromatographic fingerprints are solved using the proposed strategy. In this study, first, informative GC-MS fingerprints of citrus secondary metabolites are generated and then, whole data sets are segmented to some...
Towards obtaining more information from gas chromatography-mass spectrometric data of essential oils: An overview of mean field independent component analysis
, Article Journal of Chromatography A ; Volume 1217, Issue 29 , 2010 , Pages 4850-4861 ; 00219673 (ISSN) ; Parastar, H ; Sereshti, H ; Sharif University of Technology
2010
Abstract
Mean field independent component analysis (MF-ICA) along with other chemometric techniques was proposed for obtaining more information from multi-component gas chromatographic-mass spectrometric (GC-MS) signals of essential oils (mandarin and lemon as examples). Using these techniques, some fundamental problems during the GC-MS analysis of essential oils such as varying baseline, presence of different types of noise and co-elution have been solved. The parameters affecting MF-ICA algorithm were screened using a 25 factorial design. The optimum conditions for MF-ICA algorithm were followed by deconvolution of complex GC-MS peak clusters. The number of independent components (ICs) (chemical...
Chemometrics comparison of gas chromatography with mass spectrometry and comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry Daphnia magna metabolic profiles exposed to salinity
, Article Journal of Separation Science ; Volume 41, Issue 11 , 2018 , Pages 2368-2379 ; 16159306 (ISSN) ; Garreta Lara, E ; Campos, B ; Barata, C ; Lacorte, S ; Tauler, R ; Sharif University of Technology
Wiley-VCH Verlag
2018
Abstract
The performances of gas chromatography with mass spectrometry and of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry are examined through the comparison of Daphnia magna metabolic profiles. Gas chromatography with mass spectrometry and comprehensive two-dimensional gas chromatography with mass spectrometry were used to compare the concentration changes of metabolites under saline conditions. In this regard, a chemometric strategy based on wavelet compression and multivariate curve resolution–alternating least squares is used to compare the performances of gas chromatography with mass spectrometry and comprehensive two-dimensional gas chromatography with...