Volatile organic compounds (VOCs) emitted from materials during degradationcan be a valuable source of information. In this work, the emissions of furfural and aceticacid from cellulose were studied ...using solid-phase micro-extraction (SPME) incombination with gas chromatography-mass spectrometry. Two sampling techniques wereemployed: static headspace sampling using SPME for 1 h at 40
C after 18-h samplepreparation at 80
C in a closed glass vial, and contact SPME in a stack of paper (or abook). While a number of VOCs are emitted from paper under conditions of natural oraccelerated degradation, two compounds were confirmed to be of particular diagnosticvalue: acetic acid and furfural. The emissions of furfural are shown to correlate with pH ofthe cellulosic environment. Since pH is one of the most important parameters regardingdurability of this material, the developed method could be used for non-destructiveevaluation of historical paper.
EIT's teething problems Nowotny, Helga; Kolar, Jana
Science (American Association for the Advancement of Science),
2016-Aug-12, 2016-08-12, 20160812, Letnik:
353, Številka:
6300
Journal Article
Recenzirano
Good policy intentions do not always translate into the desired outcome. Nearly a decade ago, the European Commission (EC) launched two new entities with the goal of building a European-wide ...ecosystem-one to support frontier research, the European Research Council (ERC), and the other to boost innovation, the European Institute of Technology (EIT). Today, the ERC is considered the gold standard for funding frontier research of scientific excellence, with a budget that almost doubled in 2014 under Horizon 2020, the European Union Framework Programme for Research and Innovation. What about the EIT? While acknowledging the progress made, an April report by the European Court of Auditors states that the EIT's overly complex operational structure and past management problems have impeded its overall effectiveness. In fact, continuous evaluations and adjustments will probably be needed to turn it into a success.
EDITORIAL: EIT's teething problems Nowotny, Helga; Kolar, Jana
Science (American Association for the Advancement of Science),
08/2016, Letnik:
353, Številka:
6300
Journal Article
Near-Infrared Spectroscopy has became a widely used analytical technique in different research fields due to its non-destructiveness and low-cost. The spectra are rich in information but extremely ...complex, therefore their analysis necessitates the use of advanced statistical methods. The empirical properties of the statistical methods can be assessed using artificially generated data that resemble real Near-Infrared Spectroscopy.
In this paper we propose a new data generation approach (ABS) that takes into account the theoretical knowledge about the near-infrared absorption of the functional groups. The proposed method is compared to real data and to a simpler data generation method, which simulates the data from a multivariate normal distribution whose parameters are estimated from real data (MVNorig). The comparison between real data and the data generation approaches is based on a class-imbalanced classification problem using linear discriminant analysis, classification trees and support vector machines.
Both simulation approaches generated spectra with a good resemblance to real data, MVNorig performing slightly better than ABS; using real and simulated data we would have reached similar conclusions about the class-imbalance problem in classification.
Both methods can be used to artificially generate near-infrared spectra. The method based on multivariate normal distribution can be used when a large number of real data spectra is available, while the appropriateness of the results of the ABS method depend on the exactness of functional group near-infrared absorption knowledge.
•Near-Infrared Spectroscopy (NIR) is a widely used analytical technique.•The analysis of NIR data necessitates the use of advanced statistical methods.•Artificially generated data that resemble real NIR data can be used to assess the properties of statistical methods.•We propose a data generation approach that uses the theoretical knowledge about the NIR absorbtion of the functional groups.•The new method performs well in practice.
The focus of this research is the stabilisation of paper with Verdigris, a green copper pigment. Due to its corrosive effects on paper, many important documents, paintings and maps are in danger. The ...efficiency of several commercially available deacidification agents on paper samples with Verdigris was tested, including magnesium-based Bookkeeper® dispersion, nano calcium hydroxide containing Nanorestore® and CaLoSiL® dispersions as well as a recently developed dispersion of nano calcium carbonate. The antioxidant tetrabutylammonium bromide was tested either alone or in combination with nano calcium based deacidification agents. The effect of the treatments was evaluated using colour, tensile strength, degree of polymerization and pH measurements. The results indicate that acidic degradation does not play a major role during accelerated degradation of paper containing Verdigris with moderately acidic pH value and that oxidative decay could be the main culprit of the decay. The method described, which involves the use of antioxidant tetrabutylammonium bromide in combination with calcium carbonate based deacidification dispersion, was proved to have a superior effect against degradation of paper with Verdigris in comparison to the treatments which involve deacidification agents only. Nano calcium hydroxide based deacidification agents result in high pH values of the paper samples and therefore cannot be advised for use on paper documents.
Portability of instrumentation, non-destructive spectral acquisition and a wealth of information that can be extracted from the spectra are features that have made Near-Infrared Spectroscopy an ...attractive topic in the analysis of cultural heritage.
In this paper, a classification rule was developed using 41 classes of 535 historical and modern polymers using Near-Infrared Spectroscopy. The usability and the quality of the prediction model were tested on a blind sample set of 32 historical polymers. 20 out of 23 samples (87%) which are in the database used for the development of the classification model were correctly classified by the model. Eight darkly coloured samples could not be classified due to their low reflectance. The results of Near-Infrared Spectroscopy are compared to Attenuated Total Reflectance Fourier-Transform Mid-Infrared Spectroscopy and Pyrolysis-Gas Chromatography/Mass Spectrometry. Advantages and limitations of these techniques for the identification of historical polymers are discussed.
Sampling restrictions in analysis of cultural heritage materials narrow the choice of appropriate analytical methods considerably. In this work, near- and mid-FT-IR reflectance data were related to ...paper properties determined with classical analytical methods using partial least-squares. Nondestructive determination of properties, which are of importance for evaluation of the long-term stability of historical paper, i.e., ash content, lignin content, degree of polymerization of cellulose, pH, and aluminum content, is possible. With the use of a considerable sample set, satisfactory reliability was achieved for all properties but aluminum content. Considering that with age, chemical properties of paper change, dating of historical documents was attempted for the first time, also with success.
The role of transition metals in oxidative degradation of cellulose has been studied. Degradation experiments with model papers and studies of hydroxyl radical production in solution have been ...performed with Fe, Cu, Mn, Co, Cr, Ni, and Zn. Rates of production of hydroxyl radicals in solution have been estimated using the radical scavenger
N,
N′-(5-nitro-1,3-phenylene)bisglutaramide in the pH interval 7–9. Hydroxyl radical production during degradation of Cu-containing cellulose has been studied. To gain a better insight into chemistry behind degradation processes, chemiluminometric experiments were also performed.
The experiments provide strong evidence that the role of transition metals during the oxidative degradation of cellulose is catalytic. A correlation between the behaviour of transition metals in solution and in paper was established at low contents of transition metal in paper.
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