The present study aims to provide new insights into the temperature-dependent spectral variations in the near infrared (NIR) region of the spectrum of water by comparing chemometrics with spectroscopic analysis. Fourier transform (FT)-NIR spectra of water in the 9000–5500 cm−1 region have been measured over a temperature range of 5–85°C. The observed spectral changes have been analysed by both chemometrics, such as multilinear regression (MLR), principal component regression (PCR) and partial least squares (PLS) regression, and spectroscopic data analyses, such as second derivative, difference spectra and curve fitting. The second derivative of the NIR spectra of water suggests that an intense feature around 6900 cm−1, due to the combination of antisymmetric and symmetric stretching modes of water, consists of at least five component spectra. Each component spectrum may be ascribed to the water species with no, one, two, three and four hydrogen bonds. Curve fitting has been performed for the 6900 cm−1 band and it has been found that the species with no hydrogen bonds increase largely with temperature, while those with more than two hydrogen bonds decrease. The temperature of water has been predicted by use of MLR, PCR and PLS regression. PCR and PLS regression loadings plots for Factor 1 of the models for the prediction of the temperature of water are almost identical with the difference spectrum of water between 5 and 85°C; both the loadings plots and the difference spectrum reflect strongly the changes in the hydrogen bonds of water. Loadings plots of Factor 1 of the PCR and PLS regression models are very similar to each other. It is very likely that since the temperature-dependent spectral variations of water in the NIR region are very regular, and the spectra have only very small noise and baseline changes, PCR and PLS regression select nearly identical factors.

The temperature-dependent near-infrared (NIR) spectral variations of n- and tert-butyl alcohols in the pure liquid state have been studied by generalized two-dimensional (2D) correlation analysis. The Fourier transform (FT) NIR spectra were recorded in the 6000−11000 cm-1 region over the temperature ranges of 20−85 and 25−75 °C for n- and tert-butyl alcohols, respectively. In the 2D NIR correlation spectra of both alcohols appear the bands due to the OH stretching vibrations of the monomer (first and second overtones), cyclic dimer, and linear hydrogen bonds in acyclic and cyclic polymers. Moreover, the spectra of tert-butyl alcohol reveal the bands that can be attributed to the free terminal OH groups in open chain species (7047 cm-1), bend OHO bonds (6520 cm-1), and a band at 6610 cm-1. The last one, not reported previously, was assigned to the small cyclic associates (trimers or tetramers). Our results evidenced that in the pure liquid state the population of rotational isomers is determined mostly by the accessibility of the OH proton. This is why the bands due to the less stable rotamers are much more intense than the energetically favorable ones in neat n- and sec-butyl alcohols. Owing to smaller population of the free OH groups, as compared to the sec-butyl alcohol, the rotational isomerism was not observed for n-butyl alcohol in the pure liquid phase. Yet, this effect was clearly seen in diluted solution of n-butyl alcohol. The analysis of the asynchronous 2D correlation spectra has proved that the variations in the population of the associated species and monomers do not occur at the same rate. The changes for the monomers are slower than that for any other species; however, the population of this species increases faster at higher temperatures. At elevated temperatures the rapid increase in the population of the cyclic dimers is reduced by simultaneous dissociation into the monomers. It has been demonstrated that the stability of the cyclic dimers is diminished upon branching. Our results show the relationship between the chemical structure of alcohols and dynamic properties of the hydrogen bonding.

The first paper in a series devoted to self-association in neat butanols presents the results of two-dimensional (2D) near-infrared (NIR) correlation analysis of temperature-induced spectral variations of sec-butanol. By taking advantage of resolution enhancement in the 2D correlation spectra, it was possible to identify spectral features due to vibrations of the free and associated OH groups in the first-overtone region. On the basis of a few assumptions, band assignments of the various types of OH bonds have been proposed. The monomer band (near 7100 cm−1) can be resolved into three components; two of them are due to a rotational isomerism (7089 and 7116 cm−1), and the third one is attributed to the free terminal OH groups in linear polymers (7055 cm−1). The presence of the 7055 cm−1 band implies that the intensity of the monomer peak cannot be used as a measure of the concentration of the monomer species (except in very diluted solutions). Thus, previous estimations of equilibrium constants and thermodynamic parameters associated with hydrogen-bond dissociation have been subject to unacceptable error. At higher temperatures, a new band near 6550 cm−1 becomes visible. This band originates from bended OHO bond, mostly in the cyclic polymers. In order to obtain more detailed information on the complex mechanism of the thermal dissociation of hydrogen-bonded sec-butanol in the pure liquid phase, the entire experimental temperature range was divided into narrower ranges, and then 2D correlation analysis was performed for smaller data sets. It has been shown that the variations of population of the polymeric species and the cyclic dimers are faster than the corresponding changes for the monomers. At elevated temperatures an appreciable dissociation of the cyclic species takes place.

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This paper demonstrates the usefulness of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy and chemometrics in nondestructive discrimination of biological materials. The discrimination among three kinds of materials—hard ivories, soft ivories, and mammoth tusks—has been investigated as an example. NIR (1064-nm) excited FT-Raman spectra were measured in situ for these materials, and principal component analysis (PCA) of the obtained spectra was carried out over the 1800–400-cm−1 region. The two kinds of ivories are clearly discriminated from one another on the basis of a one-factor plot. It was found that treatment of the Raman data by multiplicative scatter correction (MSC) greatly improves the ability to discriminate. Principal component weight loadings show that the discrimination relies upon the ratio of collagen and hydroxyapatite included in two kinds of ivories. The discrimination among the hard and soft ivories and mammoth tusks was made by a three-factor plot for FT-Raman spectra after the MSC treatments. Partial least-squares regression (PLSR) enabled us to make a calibration model which predicts the specific gravity of the hard and soft ivories.

Background It is important to control chemotherapy‐induced nausea and vomiting (CINV) to maintain dose intensity and patients' quality of life. The National Comprehensive Cancer Network guidelines suggest combination therapy of antiemetic agents. The growing number of antiemetic regimens, and in particular the growing use of regimens containing antagonists to the Nk‐1 receptor (NK1RAs) and the antipsychotic drug olanzapine (OLZ), call for the re‐evaluation of the optimal regimen for CINV. This study assessed the efficacy and safety of antiemetic regimens for highly emetogenic chemotherapy, using Bayesian network meta‐analysis. Methods Randomized trials that compared different antiemetic regimens were included. We strictly followed Preferred Reporting Items for Systematic Reviews and Meta‐Analysis guidelines. The main outcomes were the odds ratio (OR) for overall complete response (absence of vomiting). We conducted network meta‐analysis within a Bayesian model to combine the direct and indirect evidence. Safety was assessed from the trial description. All statistical tests were two‐sided. Results We systematically reviewed 27 randomized control trials (13,356 participants), which compared 12 different antiemetic regimens: serotonin‐3 receptor antagonist (5HT3), 5HT3 + dexamethasone (Dex), palonosetron (PAL), PAL + Dex, PAL at 0.75 mg (PAL0.75), PAL0.75 + Dex, NK1RA + 5HT3 + Dex, NK1RA + PAL + Dex, an oral combination of netupitant and palonosetron (NEPA) + Dex, OLZ + 5HT3 + Dex, OLZ + PAL + Dex, and OLZ + NK1RA + 5HT3 + Dex. An NK1RA + 5HT3 + Dex regimen and an NK1RA + palonosetron + Dex regimen gave a higher complete response (CR) rate than the reference regimen, 5HT3 + Dex (OR, 1.75; 95% credibility interval [95% CrI], 1.56–1.97, and OR, 2.25; 95% CrI, 1.66–3.03, respectively). A regimen containing NEPA was more effective in producing CR than conventional regimens without NEPA or olanzapine. Further analysis, based on the surface under the cumulative ranking probability curve, indicated that olanzapine‐containing regimens were the most effective in producing CR. Conclusion Our meta‐analysis supports the conclusion that olanzapine‐containing regimens are the most effective for CINV of highly emetogenic chemotherapy. We confirmed that NK1RA + PAL + Dex is the most effective of conventional regimens. Substituting olanzapine for an Nk‐1 receptor antagonist may offer a less costly and more effective alternative for patients. Implications for Practice Nausea and vomiting during chemotherapy often pose difficulties for patients and doctors, making it hard to continue the proper therapy and to maintain the quality of life. This article gives insights into the optimal choice of medicine to treat nausea during chemotherapy. The findings reported here provide readers with a robust efficacy ranking of antinausea medicine, which can be used as a reference for the best possible treatment. Furthermore, the 70% less costly drug, olanzapine, is suggested to be equally effective to aprepitant in reducing nausea and vomi...

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