Influence of Spectroscopic Techniques on the Estimation of the Degree of Conversion of Bulk-fill Composites

2020 ◽  
Vol 45 (1) ◽  
pp. 92-103 ◽  
Author(s):  
V Bolaños-Carmona ◽  
C Benavides-Reyes ◽  
S González-López ◽  
P González-Rodríguez ◽  
P Álvarez-Lloret
Keyword(s):  
Nonparametric Test ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Degree Of Conversion ◽  
Rank Test ◽  
Analytical Control ◽  
Spectroscopic Techniques ◽  
Raman Spectroscopic ◽  
Flowable Composites ◽  
Ft Raman

SUMMARY Objectives: To compare the degree of conversion (DC) of different flowable and sculptable bulk-fill composites (BFC), at 0- and 4-mm depths from the surface, by Fourier transform infrared (FTIR), attenuated total reflection FTIR (ATR-FTIR), and FT-Raman spectroscopic techniques. Methods and Materials: Six BFC were investigated, including three sculptable composites (Admira Fusion [Voco], Aura Bulk Fill [SDI], and X-tra Fill [Voco]) and three flowable composites (Venus Bulk Fill [Heraeus], Filtek [3M], and X-tra Base [Voco]). Three molds of each composite were light cured as specified by the manufacturer. For each mold, slices corresponding to 0-mm (surface) and 4-mm depth were analyzed by spectroscopic techniques: ATR-FTIR, FTIR, and FT-Raman. The spectra of uncured composite material were used as an analytical control for background subtraction of the treated composite. The area and amplitude of the reference peaks (1607 and 1637 cm−1) were obtained to calculate the DC percentage at 0- and 4-mm depth. A Kruskal-Wallis nonparametric test was used for materials, and paired comparisons were made using Mann-Whitney nonparametric test. Wilcoxon's rank test was used for comparison between spectroscopic methods and between 0- and 4-mm depth in each composite. Significance was accepted at p<0.05. Results: FTIR showed significantly lower DC values, both in areas and amplitudes of the peaks, when compared with the results reported by different BFC. Differences between the surface and 4-mm depth were detected more precisely by FT-Raman. ATR-FTIR obtained DC values significantly higher than those obtained by FTIR. Conclusions: The vibrational spectroscopy method significantly influenced DC measurements of the flowable and sculptable BFC explored.

Quantitative Determination of Prednisone in Tablets by Infrared Attenuated Total Reflection and Raman Spectroscopy

2012 ◽  
Vol 95 (3) ◽  
pp. 744-750 ◽  
Author(s):  
Sylwester Mazurek ◽  
Roman Szostak
Keyword(s):  
Predictive Ability ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Relative Standard Error ◽  
Data Sets ◽  
Spectroscopic Techniques ◽  
Validation Data ◽  
Relative Standard ◽  
Atr Spectroscopy ◽  
Ft Raman

Abstract The quantification of prednisone in tablets was performed using partial least squares (PLS) models based on FTIR-attenuated total reflection (ATR) and FT-Raman spectra. To compare the predictive ability of these models, the relative standard error of prediction (RSEP) values were calculated. In the case of prednisone determination from the FT-Raman data, RSEP values of 3.1 and 3.2% for the calibration and validation data sets were obtained. For FTIR-ATR models, which were constructed using five spectra for each sample, these errors amounted to 2.6 and 2.9%, respectively. Four commercial products containing 1, 5, 10, and 20 mg prednisone/tablet were quantified. Concentrations derived from the elaborated models correlated strongly with the results of reference analyses and with the declared values (in parentheses). The analyses gave recoveries of 100.0–101.6% (100.1–103.0%) and 98.1–103.2% (100.4–102.9%) for FTIR-ATR and FT-Raman data, respectively. A successful quantification of prednisolone in tablets containing 5 mg active ingredient/tablet was also performed using the PLS model, which was based on FTIR-ATR spectra, with a recovery of 99.8 (98.8%). Both reported spectroscopic techniques can be used as fast and convenient alternatives to the standard pharmacopeial methods of prednisone and prednisolone quantification in solid dosage forms. However, in the case of FTIR-ATR spectroscopy, it is necessary to repeat measurements several times to obtain sufficiently low quantification errors.

scholarly journals The Influence of Storage Conditions on the Biochemical Composition and Morphology of Dahlia Tubers

2016 ◽  
Vol 44 (2) ◽  
pp. 459-465 ◽  
Author(s):  
Ioana CIOBANU ◽  
Maria CANTOR ◽  
Razvan STEFAN ◽  
Erzsebet BUTA ◽  
Klara MAGYARI ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Storage Conditions ◽  
Spectroscopic Techniques ◽  
Air Humidity ◽  
Raman Spectroscopic ◽  
Pathogen Invasion ◽  
Ft Ir ◽  
Biometric Measurements ◽  
C 30 ◽  
Ft Raman

The aim of this study was to assess by means of biometric measurements and FT-IR and FT-Raman spectroscopic techniques the influence of storage conditions on the morphology and biochemical composition of Dahlia tubers. Investigated samples belong to ‘Kennemerland’ and ‘Red Pygmy’ cultivars of the Dahlia hybrida species, which were preserved over winterat 5-8 °C, 30-40% air humidity in different substrates: sand, sand and sawdust, peat and sawdust. The biometric parameters revealed that the peat and sawdust substrate is the most appropriate one for tubers storage, whereas the sand substrate is the least suitable one. The inulin signature was evidenced in all tuber samples as well as the changes of biochemical composition induced by different storage conditions. The analysis of the FT-IR and FT-Raman spectra demonstrated that the inulinaccumulation inside the tubers is favourably influenced by the sand storage, and depends on the cultivar type. Moreover, it was established that the peat and sawdust substrate favours the polyacetylene formation inside the tubers probably because it facilitates the occurrence and development of pathogens inside the tuber. It was also found that the polyacetylene concentration increased, which is associated with the plant response to the pathogen invasion, depends on the cultivar type.

scholarly journals Spectroscopic, Electronic and Optical Properties of 4-Nitroimidazole using DFT Calculations

2020 ◽  
Vol 33 (1) ◽  
pp. 83-88
Author(s):  
S. Jeyavijayan ◽  
Palani Murugan
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Dft Method ◽  
Nbo Analysis ◽  
Spectroscopic Techniques ◽  
Functional Theory ◽  
Raman Spectroscopic ◽  
Homo Lumo ◽  
Total Energy Distribution ◽  
Ft Raman

Theoretical and experimental vibrational spectra of 4-nitroimidazole were studied by FTIR, FT-Raman spectroscopic techniques and density functional theory (DFT) method. The contributions of the different modes to each wavenumber were confirmed using total energy distribution (TED). The optimized parameters and thermodynamic properties of 4-nitroimidazole have been computed. The charge transfer interactions of the molecule were explained from the small value of HOMO-LUMO energy gap. The NBO analysis, Mulliken’s plot and MEP studies of the molecule have also been reported.

An attenuated total reflection (ATR) and Raman spectroscopic investigation into the effects of chloroquine on Plasmodium falciparum-infected red blood cells

The Analyst ◽  
2015 ◽  
Vol 140 (7) ◽  
pp. 2236-2246 ◽  
Author(s):  
M. Kozicki ◽  
D. J. Creek ◽  
A. Sexton ◽  
B. J. Morahan ◽  
A. Wesełucha-Birczyńska ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Plasmodium Falciparum ◽  
Fourier Transform ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Raman Spectroscopic ◽  
Human Red Blood Cells ◽  
Ftir And Raman Spectroscopy

Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) and Raman spectroscopy were used to compare chloroquine (CQ)-treated and untreated cultured Plasmodium falciparum-infected human red blood cells (iRBCs).

Gas Cell Infrared and Attenuated Total Reflection Infrared Spectroscopic Studies for Organic–Inorganic Interactions in Adsorption of Fulvic Acid on the Goethite Surface Generating Carbon Dioxide

2021 ◽  
pp. 000370282199121
Author(s):  
Yuki Nakaya ◽  
Satoru Nakashima ◽  
Takahiro Otsuka
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Fulvic Acid ◽  
Spectroscopic Studies ◽  
Reaction Model ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Gas Cell ◽  
Rate Determining Step ◽  
Ir Spectroscopic

The generation of carbon dioxide (CO2) from Nordic fulvic acid (FA) solution in the presence of goethite (α-FeOOH) was observed in FA–goethite interaction experiments at 25–80 ℃. CO2 generation processes observed by gas cell infrared (IR) spectroscopy indicated two steps: the zeroth order slower CO2 generation from FA solution commonly occurring in the heating experiments of the FA in the presence and absence of goethite (activation energy: 16–19 kJ mol–1), and the first order faster CO2 generation from FA solution with goethite (activation energy: 14 kJ mol–1). This CO2 generation from FA is possibly related to redox reactions between FA and goethite. In situ attenuated total reflection infrared (ATR-IR) spectroscopic measurements indicated rapid increases with time in IR bands due to COOH and COO– of FA on the goethite surface. These are considered to be due to adsorption of FA on the goethite surface possibly driven by electrostatic attraction between the positively charged goethite surface and negatively charged deprotonated carboxylates (COO–) in FA. Changes in concentration of the FA adsorbed on the goethite surface were well reproduced by the second order reaction model giving an activation energy around 13 kJ mol–1. This process was faster than the CO2 generation and was not its rate-determining step. The CO2 generation from FA solution with goethite is faster than the experimental thermal decoloration of stable structures of Nordic FA in our previous report possibly due to partial degradations of redox-sensitive labile structures in FA.

scholarly journals Distinguishing active from quiescent disease in ANCA-associated vasculitis using attenuated total reflection Fourier-transform infrared spectroscopy

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam D. Morris ◽  
Camilo L. M. Morais ◽  
Kássio M. G. Lima ◽  
Daniel L. D. Freitas ◽  
Mark E. Brady ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Unmet Need ◽  
Fourier Transform Infrared ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Remission Induction ◽  
Disease Remission ◽  
Anca Associated Vasculitis ◽  
Active Disease ◽  
Quiescent Disease

AbstractThe current lack of a reliable biomarker of disease activity in anti-neutrophil cytoplasmic autoantibody (ANCA) associated vasculitis poses a significant clinical unmet need when determining relapsing or persisting disease. In this study, we demonstrate for the first time that attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy offers a novel and functional candidate biomarker, distinguishing active from quiescent disease with a high degree of accuracy. Paired blood and urine samples were collected within a single UK centre from patients with active disease, disease remission, disease controls and healthy controls. Three key biofluids were evaluated; plasma, serum and urine, with subsequent chemometric analysis and blind predictive model validation. Spectrochemical interrogation proved plasma to be the most conducive biofluid, with excellent separation between the two categories on PC2 direction (AUC 0.901) and 100% sensitivity (F-score 92.3%) for disease remission and 85.7% specificity (F-score 92.3%) for active disease on blind predictive modelling. This was independent of organ system involvement and current ANCA status, with similar findings observed on comparative analysis following successful remission-induction therapy (AUC > 0.9, 100% sensitivity for disease remission, F-score 75%). This promising technique is clinically translatable and warrants future larger study with longitudinal data, potentially aiding earlier intervention and individualisation of treatment.

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