Search results for " Total"
showing 10 items of 385 documents
Is Active Moss Biomonitoring Comparable to Air Filter Standard Sampling?
2022
Recently, significant attention has been paid to air quality awareness and its impact on human health, especially in urban agglomerations. Many types of dust samplers for air quality monitoring are used by governmental environmental monitoring agencies. However, these techniques are associated with high costs; as a consequence, biological methods such as active moss biomonitoring are being developed. The main disadvantages of such techniques are the lack of standardization of the preparation procedures and the lack of reliable comparisons of results with data from instrumental analyses. Our study aimed to compare the results obtained from active biomonitoring with the use of three moss spec…
On the Estimation of the Volatility-Growth Link
2012
It is common practice to estimate the volatility-growth link by specifying a standard growth equation such that the variance of the error term appears as an explanatory variable in this growth equation. The variance in turn is modeled by a second equation. Hardly any of existing applications of this framework includes exogenous controls in this second variance equation. Our theoretical findings suggest that the absence of relevant explanatory variables in the variance equation leads to a biased and inconsistent estimate of the volatility-growth link. Our simulations show that this effect is large. Once the appropriate controls are included in the variance equation consistency is restored. I…
Plasmonic modes in molybdenum ultra-thin films suitable for hydrogenated amorphous silicon thin film solar cells
2014
We have recently demonstrated that molybdenum ultra-thin films interposed between hydrogenated amorphous silicon (a-Si:H) and SnO2:F transparent conductive oxide (TCO) in thin film solar cells show light trapping effects which enhance the solar cells performances. The effect of this improvement may be attributed to surface plasmon polariton (SPP) modes excited at the molybdenum interface by the solar radiation. In this paper we show direct evidence of such SPP modes in the case of the molybdenum/air interface by using the attenuated total reflection (ATR) technique, pioneered by Kretschmann, and we evaluate the dielectric constant of molybdenum at 660 nm. (C) 2013 The Authors. Published by …
Quantification of minerals from ATR-FTIR spectra with spectral interferences using the MRC method.
2017
A method for quantifying the individual components of mineral samples based on attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR) is described, extending the constant ratio (CR) method to analytes absorbing in a common range of wavenumbers. Absorbance values in the spectral region where the analytes absorb relative to the absorbance of an internal standard absorbing at a wavenumber where the analytes do not absorb, permits the quantification of N analytes using measurements at N fixed wavenumbers. The method was tested for mixtures of albite, orthoclase, kaolin and quartz.
Nutritional parameters of commercially available milk samples by FTIR and chemometric techniques
2004
Abstract A chemometric study on the prediction of the main nutritional aspects of milk has been carried out by using fourier transform infrared spectroscopy (FTIR) attenuated total reflectance (ATR) measurements of commercially available milk samples of different types. Whole, semi and skimmed milks, enriched or not with calcium, vitamins or modified by alteration of lipid or sugar composition were considered. After evaluating different strategies for data acquisition and ATR cleaning between samples, hierarchical cluster analysis (HCA) was carried out for classification of samples in order to choose the calibration set. The prediction capabilities of partial least squares (PLS) data treatm…
Identification and determination of synthetic cannabinoids in herbal products by dry film attenuated total reflectance-infrared spectroscopy.
2017
A new procedure has been developed for the identification and quantitative determination of synthetic cannabinoids in illicit herbal preparations. The methodology is based on the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) measurement of sample extracts with 2-propanol drying 5µL of the extracts onto the ATR crystal. The qualitative identification was carried out on the 2-propanol extract after identification of the herbal matrix, followed by its subtraction and using a cut-off criterion of 75%. Quantitative determination was made by univariate calibration using the absorbance of the band located at 1520cm-1 of the spectrum. Four different cannabin…
Analytical potential of mid-infrared detection in capillary electrophoresis and liquid chromatography: a review.
2010
Literature published in the last decade concerning the use of mid-infrared spectrometry as a detection system in separation techniques employing a liquid mobile phase is reviewed. In addition to the continued use of isocratic liquid chromatographic (LC) techniques, advances in chemometric data evaluation techniques now allow the use of gradient techniques on a routine basis, thus significantly broadening the range of possible applications of LC-IR. The general trend towards miniaturized separation systems was also followed for mid-IR detection where two key developments are of special importance. Firstly, concerning on-line detection the advent of micro-fabricated flow-cells with inner volu…
Chemometric determination of lipidic parameters in serum using ATR measurements of dry films of solvent extracts
2013
Attenuated total reflectance (ATR) infrared spectroscopy of dried organic extracts of serum samples has been evaluated as a fast method for the determination of triglycerides, cholesterol, high density lipoprotein (HDL) and low density lipoprotein (LDL). After careful selection of solvents based on green parameters, serum samples were extracted using hexane-isopropanol and ethyl acetate-ethanol mixtures. Microscopy studies and comparison with standard spectra were performed in order to investigate whether the proposed methodology is suitable for the quantification of lipids in serum samples. The results of these preliminary studies confirmed that the variations in the IR spectra of sample e…
Attenuated Total Reflection-Fourier transform infrared analysis of the fermentation process of pineapple
2005
Abstract A direct and reagent free procedure has been developed to monitor the fermentation process of pine apple nectar using Attenuated Total Reflectance Fourier-transform mid-infrared spectrometry (FT-IR) and multivariate analysis. A classical 4 2 design for standards was employed for calibration using the information in the spectral range from 907 to 1531 cm −1 of the first order derivative spectra after mean centering of infrared data. The root mean square error of calibration (RMSEC) of 0.040, 0.021, 0.063 and 0.074% w/w were obtained for glucose, fructose, saccharose and ethanol, respectively, and a mean relative validation error of 2.9, 2.1, 2.6 and 3.6% was achieved for glucose, fr…
Funkcionālo un radioloģisko rezultātu salīdzinājums pacientiem pēc pleca locītavas endoprotezēšanas ar Global Icon™ Stemless un Global Unite® anatomi…
2021
Darba aktualitāte: Pleca locītavas endoprotezēšana ir viena no ķirurģiskās ārstēšanas metodēm osteoartrīta slimībai. Mūsdienu tehnoloģiskās iespējas nodrošina endoprotēžu attīstību un daudzveidību. Aizstājot pacienta dabīgo locītavu ar mākslīgo implantu, svarīgi ir izvēlēties viņa stāvoklim, ikdienas aktivitātēm un prasībām atbilstošāko protēzes veidu, lai sasniegtu labāko pēcoperācijas rezultātu. Darba mērķis: Salīdzināt Global Icon anatomiskās bezkājiņas implanta efektivitāti ar Global Unite implanta ar kājiņu efektivitāti, izvērtējot klīniskos un radioloģiskos rezultātus gadu pēc operācijas. Darba uzdevumi: Veikt CMS rezultātu analīzi pirms operācijas un gadu pēc endoprotezēšanas operāci…