Monitoring panel performance within and between sensory experiments by multi-way analysis

In sensory analysis a panel of trained assessors evaluates a set of samples according to specific sensory descriptors. The training improves objectivity and reliability of assessments. However, there can be individual differences between assessors left after the training that should be taken into account in the analysis. Monitoring panel performance is then crucial for optimal sensory evaluations. The quality of the results is strongly dependent on the performance of each assessor and of the panel as a whole. The present work proposes to analyze the panel performance within single sensory evaluations and between consecutive evaluations. The basic idea is to use multi-way models to handle the three-way nature of the sensory data. Specifically, a PARAFAC model is used to investigate the panel performance in the single experiment. N-PLS model is used to test the predictive ability of the panel on each experiment. A PARAFAC model is also used for monitoring panel performance over different experiments

Green synthesis of carbon quantum dots from vanillin for modification of magnetite nanoparticles and formation of palladium nanoparticles: Efficient catalyst for Suzuki reaction

In this report we prepared carbon quantum dots (CQD) from vanillin as an ecofriendly and naturally abundant compound for modification of magnetic nanoparticles (CQD@Fe3O4 NPs). This new magnetic solid has been used for complete reduction of PdCl2 with formation of stabilized palladium nanoparticles (Pd@CQD@Fe3O4 NPs) and characterized by SEM, TEM, EDX, solid UV, VSM, XPS, XRD, and N2 adsorption–desorption analyses. These magnetic supported Pd NPs have been used as an efficient catalyst for the Suzuki-Miyaura cross-coupling reactions of aryl bromides at room temperature in aqueous ethanol and of aryl chlorides at 120 °C in PEG200 under low catalyst loading in air. The heterogeneous catalyst can be easily recovered by an external magnet and reused for eight consecutive runs.The authors are grateful to Institute for Advanced Studies in Basic Sciences (IASBS) Research Council and Iran National Science Foundation (INSF-Grant number of 94010666) for support of this work. C. Nájera is also thankful to The Spanish Ministerio de Economia y Competitividad (MINECO) (projects CTQ2013-43446-P and CTQ2014-51912-REDC), FEDER, the Generalitat Valenciana (PROMETEOII/2014/017) and the University of Alicante for financial support

Københavns Universitet Multi-way based calibration transfer between two Raman spectrometers Multi-way based calibration transfer between two Raman spectrometers

A standardization algorithm based on the application of Tucker3 models on the tensorized measurement signals is proposed to transfer calibration information between two Raman spectrometers. The secondary instrument in this study is a low cost and portable CCD based unit employing an efficient 532 nm green laser. The primary instrument is a high performance Fouriertransform based laboratory instrument using a low efficiency NIR laser at 1064 nm, albeit with very limited sample fluorescence interference. This work is a first investigation of calibration transfer on Raman spectral data which include different values of fluorescent background from one instrument to the other. The spectra of a small set of calibration samples are measured on both spectrometers. Using the ability of Tucker3 to estimate missing values in tensorized data, we reconstruct the spectrum of a new sample on the primary instrument based on its measured response of the secondary instrument without the need for constructing an explicit transfer model. This way spectra of a prediction sample measured on one spectrometer can be successfully transferred to another spectrometer as if it has been measured directly on the latter. Hence, the task of calibration transfer among instruments is posed as a missing data problem. A discrete wavelet transform is performed to improve the predictive ability. Performance criteria for judging the success of the calibration transfer are reported as the standard error of prediction for estimation of samples in a prediction set. By comparison, the proposed Tucker3 based standardization method shows a better performance as compared to piecewise direct standardization. The method is expected to be applicable for performing calibration transfer using data from instruments other than Raman spectrometers

Graphene Quantum Dot Modified Fe3O4 Nanoparticles Stabilize PdCu Nanoparticles for Enhanced Catalytic Activity in the Sonogashira Reaction

In this report, Fe3O4 nanoparticles are modified for the first time with graphene quantum dots (GQD) and used for the stabilization of PdCu bimetallic nanoparticles. The new magnetic compound, PdCu@GQD@Fe3O4, is characterized by different methods such as SEM, high-resolution (HR)-TEM, energy-dispersive X-ray spectroscopy (EDS) mapping, XRD, and X-ray photoelectron spectroscopy (XPS). This material is applied as an efficient catalyst for the Sonogashira reaction of aryl iodides, bromides, and chlorides in toluene or N,N-dimethylacetamide at 60–110 °C in very high yields with 0.3 mol % of Pd loading. According to different tests, such as polyvinylpyridine poisoning, hot filtration, and kinetic studies, this catalyst works under heterogeneous conditions. By magnetic separation of the catalyst, it can be recycled for six consecutive runs with only a small decrease in activity without appreciable structural modification of the reused catalyst, which is characterized by TEM and XPS.The authors are grateful to the Institute for Advanced Studies in Basic Sciences (IASBS) Research Council and Iran National Science Foundation (INSF Grant number 94010666) for support of this work. C. Nájera is also thankful to the Spanish Ministerio de Economía y Competitividad (MINECO) (projects CTQ2013-43446-P and CTQ2014-51912-REDC), FEDER, the Generalitat Valenciana (PROMETEOII/2014/017), and the University of Alicante for financial support

FTICR mass spectrometry-based multivariate analysis to explore distinctive metabolites and metabolic pathways:A comprehensive bioanalytical strategy toward time-course metabolic profiling of Thymus vulgaris plants responding to drought stress

In this research, metabolic profiling/pathways of Thymus vulgaris (thyme) plant were assessed during a water deficit stress using an FTICR mass spectrometry-based metabolomics strategy incorporating multivariate data analysis and bioinformatics techniques. Herein, differences of MS signals in specific time courses after water deficit stress and control cases without any timing period were distinguished significantly by common pattern recognition techniques, i.e., PCA, HCA-Heatmap, and PLS-DA. Subsequently, the results were compared with supervised Kohonen neural network (SKN) ones as a non-linear data visualization and capable mapping tool. The classification models showed excellent performance to predict the level of drought stress. By assessing variances contribution on the PCA-loadings of the MS data, the discriminant variables related to the most critical metabolites were identified and then confirmed by ANOVA. Indeed, FTICR MS-based multivariate analysis strategy could explore distinctive metabolites and metabolic pathways/profiles, grouped into three metabolism categories including amino acids, carbohydrates (i.e., galactose, glucose, fructose, sucrose, and mannose), and other metabolites (rosmarinic acid and citrate), to indicate biological mechanisms in response to drought stress for thyme. It was achieved and approved through the MS signals, genomics databases, and transcriptomics factors to interpret and predict the plant metabolic behavior. Eventually, a comprehensive pathway analysis was used to provide a pathway enrichment analysis and explore topological pathway characteristics dealing with the remarkable metabolites to demonstrate that galactose metabolism is the most significant pathway in the biological system of thym

Multivariate spectrochemical analysis of interactions of three common Isatin derivatives to calf thymus DNA <i>in vitro</i>

<p>Interactions of Isatin and its derivatives, Isatin-3-isonicotinylhydrazone (IINH) and Isatin-β-thiosemicarbazone (IBT), with calf thymus DNA (ctDNA) have been investigated to delineate pharmaceutical-physicochemical properties using UV–Vis/fluorescence/circular dichroism (CD) spectroscopy, viscosity measurements, and multivariate chemometrics. IINH and IBT molecules intercalate between base pairs of DNA, hypochromism in UV absorptions, increase in the CD positive band, sharp increase in specific viscosity, and the displacement of the methylene blue and Neutral Red dye in complexes with ctDNA, by the IINH and IBT molecules, respectively. The observed intrinsic binding constants (<i>K</i>_{<i>b</i>[IBT–ctDNA]}= 1.03 × 10⁵ and <i>K</i>_{<i>b</i>[IINH–ctDNA]}= 1.09 × 10⁵ L mol⁻¹) were roughly comparable to other intercalators. In contrast, Isatin binds with ctDNA via groove mode (<i>K</i>_{<i>b</i>[Isatin–ctDNA]}= 7.32 × 10⁴ L mol⁻¹) without any significant enhancement in ctDNA viscosity. The fluorescence quenching of Isatin by ctDNA was observed as static. CD spectra indicated that Isatin effectively absorbs into grooves of ctDNA, leading to transition from <i>B</i> to <i>C</i> form. Thermodynamic parameters like enthalpy changes (∆<i>H</i> < 0) and entropy changes (∆<i>S</i> > 0) were calculated according to Van’t Hoff’s equation, indicating the spontaneous interactions. The common soft/hard chemometric methods were used not only to resolve pure concentration and spectral profiles of components using the acquired spectra but also to calculate Stern–Volmer quenching constants, binding stoichiometry, apparent binding constants (<i>K</i>_<i>a</i>), binding constants (<i>K</i>_<i>b</i>), and thermodynamic parameters. The <i>K</i>_<i>b</i> values for Isatin, IINH, and IBT were calculated as 9.18 × 10³, 1.53 × 10⁵, and 2.45 × 10⁴ L mol⁻¹, respectively. The results obtained from experimental-spectroscopic analyses showed acceptable agreement with chemometric outlines.</p