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41.
Francesca Mocci Chiara Olla Antonio Cappai Riccardo Corpino Pier Carlo Ricci Daniele Chiriu Marcello Salis Carlo Maria Carbonaro 《Materials》2021,14(4)
The molecular model is one of the most appealing to explain the peculiar optical properties of Carbon nanodots (CNDs) and was proven to be successful for the bottom up synthesis, where a few molecules were recognized. Among the others, citrazinic acid is relevant for the synthesis of citric acid-based CNDs. Here we report a combined experimental and computational approach to discuss the formation of different protonated and deprotonated species of citrazinic acid and their contribution to vibrational and magnetic spectra. By computing the free energy formation in water solution, we selected the most favoured species and we retrieved their presence in the experimental surface enhanced Raman spectra. As well, the chemical shifts are discussed in terms of tautomers and rotamers of most favoured species. The expected formation of protonated and de-protonated citrazinic acid ions under extreme pH conditions was proven by evaluating specific interactions with H2SO4 and NaOH molecules. The reported results confirm that the presence of citrazinic acid and its ionic forms should be considered in the interpretation of the spectroscopic features of CNDs. 相似文献
42.
In this paper, various graphite oxide (GO) and reduced graphene oxide (rGO) preparation methods are analyzed. The obtained materials differed in their properties, including (among others) their oxygen contents. The chemical and structural properties of graphite, graphite oxides, and reduced graphene oxides were previously investigated using Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). In this paper, hierarchical clustering analysis (HCA) and analysis of variance (ANOVA) were used to trace the directions of changes of the selected parameters relative to a preparation method of such oxides. We showed that the oxidation methods affected the physicochemical properties of the final products. The aim of the research was the statistical analysis of the selected properties in order to use this information to design graphene oxide materials with properties relevant for specific applications (i.e., in gas sensors). 相似文献
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Manuel Toledano Fátima S. Aguilera Salvatore Sauro Inmaculada Cabello Estrella Osorio Raquel Osorio 《Dental materials》2014
Objectives
The purpose of this study was to evaluate if mechanical loading promotes bioactivity at the resin interface after bonding with three different adhesive approaches.Methods
Dentin surfaces were subjected to three different treatments: demineralisation by (1) 37% phosphoric acid (PA) followed by application of an etch-and-rinse dentin adhesive Single Bond (SB) (PA + SB), (2) by 0.5 M ethylenediaminetetraacetic acid (EDTA) followed by SB (EDTA + SB), (3) application of a self-etch dentin adhesive: Clearfil SE Bond (SEB). Bonded interfaces were stored in simulated body fluid during 24 h or 3 w. One half of each tooth was submitted to mechanical loading. Remineralisation of the bonded interfaces was assessed by AFM imaging/nano-indentation, Raman spectroscopy/cluster analysis, dye assisted confocal microscopy evaluation (CLSM) and Masson's trichrome staining.Results
Loading cycling for 3 w promoted an increase of mechanical properties at the resin–dentin interface. Cluster analysis demonstrated an augmentation of the mineral–matrix ratio in SB-loaded specimens. CLSM showed an absent micropermeability and nanoleakage after loading EDTA + SB and SEB specimens. Trichrome staining reflected a narrow demineralised dentin matrix after loading, almost not observable in EDTA + SB and SEB.Significance
In vitro mechanical loading promoted mineralization in the resin–dentin interfaces, at 24 h and 3 w of storage. 相似文献46.
An efficient method for the quantitative determination of acetaminophen (AAP) and diclofenac sodium (DS) in commercial suppositories based on partial least squares (PLS) treatment of FT‐Raman spectra is described. The relative standard errors of prediction (RSEP) were calculated for calibration and validation data sets to evaluate the quality of the constructed models. In the case of DS determination, RSEP error values of 1.9 % and 2.3 % for the calibration and validation data sets, respectively, were found. For AAP these errors amounted to 1.6–2.3 % and 1.8–2.8 %, respectively, for the different calibration models. Four commercial preparations containing 5, 12.5, 16.7 and 33.3 % (w/w) AAP and one containing 5 % (w/w) DS were successfully quantified using the developed models. Concentrations derived from the developed models correlated strongly with the declared values and yielded recoveries of 99.4–100.2 % and 99.6 % for AAP and DS, respectively. The proposed procedure can be used as a fast, economic and reliable method for quantification of the active pharmaceutical ingredients in suppositories. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Background/purpose: Dermal water plays an important role in the physical properties of the skin. Recently, researchers have attempted to directly measure the dermal water content in vivo using magnetic resonance imaging, near infrared spectroscopy, and Raman spectroscopy. However, these methods have limitations. Although confocal Raman spectroscopy has been developed to measure the water content in the skin, no reports have suggested that this instrument can measure the dermal water content. This report describes a method for measuring the dermal water content in vivo using confocal Raman spectroscopy. Methods: We used a confocal Raman spectrometer and adjusted the laser exposure time and depth increments according to the skin depth. Age‐related changes in the dermal water content of the forearm were examined in 30 young and 30 elderly male subjects. Diurnal changes in the dermal water content of the forearm were examined in 12 elderly male subjects. Results: Adjusting the exposure time and depth increment dramatically improved the signal‐to‐noise ratios of the Raman spectra. Elderly dermis had significantly higher water content than young dermis. Moreover, the dermal water content displayed a diurnal change. Conclusion: This study demonstrates that the dermal water content can be measured in vivo using confocal Raman spectroscopy. 相似文献
50.
Joanna Mercado Manel Alcalà Krizia M. Karry Jorge L. Ríos-Steiner Rodolfo J. Romañach 《Journal of pharmaceutical innovation》2008,3(4):271-279
Raman spectroscopy was used to design and monitor a lysozyme protein batch crystallization process in a lab scale study to
facilitate the design of a pharmaceutical protein manufacturing process. A D-optimal design that consisted of 18 experiments
was performed to elucidate the effect of temperature, concentration of the precipitating agent, time of crystallization, and
possible interactions between these three factors on the Raman scattering changes. A polynomial mathematical model was calculated
relating the scattering of the lysozyme solutions measured at individual Raman shifts to the significant factors obtained
in the previous crystallization experiment. The 2,940-cm−1 band provided the highest correlation values indicative of small prediction errors and good predictive ability for the crystallization
model. Raman scattering signals obtained during the experiments were used as input to obtain a response surface for the factors
studied and elucidate the relationship between the crystallization process conditions and the crystals obtained. The main
factors affecting the crystallization process were the sodium chloride concentration and temperature. 相似文献