Fire-induced structural changes and long-term stability of burned historical rag papers.

When a fire strikes libraries or archives, physical deterioration of the paper is so severe that its chemical properties are often regarded as less important. However, knowledge of the chemical changes of the papers upon nearly burning is necessary to design a subsequent conservation treatment. In the present study, we have examined a rag paper object, which partially survived a fire, and analysed its chemical properties by various methods. The polymeric state of cellulose, as well as its low-molar mass degradation products, were assessed. Comparison to an identical, unharmed duplicate provided a more profound understanding of the changes caused by the fire. Light scattering analysis revealed conformational changes of the cellulose molecule after high-temperature impact, and a chemical cross-linking was observed. In our study, we found the integrity of cellulose to depend on the temperature profile induced by the fire. The low thermal conductivity of cellulose protects the material even in close proximity to the burned edges.

Improved quantification of monosaccharides in complex lignocellulosic biomass matrices: A gas chromatography-mass spectrometry based approach.

A novel method for the precise and accurate quantification of wood monosaccharides by gas-chromatography mass-spectrometry in complex lignocellulosic biomass matrices is presented. Instead of using the syn- or the anti-peak obtained by blocking the anomeric center using e.g. oximation, the sum of each syn- and anti-peak pair is used for quantification rendering the approach of the apparently constant syn- and anti-peak area ratio. Each wood monosaccharide syn- and anti-peak could essentially be distinguished upon O-ethoximation followed by trifluoroacetylation and separation on a 14% cyanopropyl/phenyl- 86% dimethylpoly-siloxane column. Additionally, internal standardization was carried out applying isotopically labeled compounds. Hence, the analytical figures of merit, such as precision and accuracy, could be substantially improved compared to standard gas-chromatography mass spectrometry as well as high-performance anion exchange chromatography (HPAEC) coupled to pulsed-amperometric detection (PAD). The applicability of the novel gas-chromatography mass-spectrometry approach is demonstrated by analysis of five selected lignocellulosic biomass sample matrices typically occurring in a biorefinery scenario. Even in exceedingly complex sample matrices precise and accurate data are obtained according to the methodology presented.

Safe and Ecological Refluxing with a Closed-Loop Air Cooling System.

Off-the-shelf computer cooling hardware was used to construct a closed-loop air cooling system (CLACS) that is distinguished by scalability, low energy, and no tap water consumption. Constructed to be generally used with laboratory condensers, the system was tested with several common low and high boiling solvents and showed a condensation performance equivalent to conventional tap water cooling. Reaction yields were therefore unaffected. Also, long-lasting Soxhlet extractions showed no performance loss relative to conventional cooling. Optionally, the device can be assembled from low-voltage components and be powered from a battery, rendering it independent of the main power. Both investment and running costs are minimal, allowing a lab-wide adoption and elimination of the two major drawbacks of commonly employed tap water cooling: waste of drinking water and the risk of flooding.

Preparation and analytical characterisation of pure fractions of cellooligosaccharides.

In the present work, a viable protocol was developed to prepare monodisperse cellooligomers up to a degree of polymerisation (DP) of 20. Peracetylated cellooligosaccharides were obtained from cellulose by acetolysis and subsequently purified by Normal Phase-High Performance Liquid Chromatography using toluene, ethyl acetate and acetone as eluents. In addition, we demonstrated how to efficiently monitor the purity and dispersity of the obtained compounds by High Performance Thin Layer Chromatography, Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry and Nuclear Magnetic Resonance. With this approach, it is possible to isolate cellooligomer standards up to DP 20 on a preparative scale (dozens of mg). The column chromatographic separation proved to be robust over several months and to be scalable from a analytical to a preparative column. The isolated oligomer standards allow a more precise description of cellooligomer distributions typically emerging from biorefinery process streams after hydrolysis of lignocelluloses. They can be used to calibrate the oligomeric region in size-exclusion chromatography where light scattering detection fails due to limited scattering intensities.

Detection of Cellulose-Derived Chromophores by Ambient Ionization-MS.

The detection of individual chromophores that contribute to the overall discoloration of paper ("yellowing") is a challenge because those substances are only present in very small amounts. In this research, two analytical approaches based on ambient ionization techniques, namely, desorption electrospray ionization and paper spray, both coupled to mass spectrometry, are compared to each other with regard to their suitability for detecting acetylated cellulosic key chromophores. The paper spray approach proved to be the more sensitive and versatile method. Subsequently, paper spray (PS)-mass spectrometry was applied to model papers and historical papers in which the acetylated chromophores were detected successfully. Independent accurate mass measurements confirmed the results obtained from reference compounds, model samples, and real-world specimens.

Phylloxera (Daktulosphaira vitifoliae Fitch) alters the carbohydrate metabolism in root galls to allowing the compatible interaction with grapevine (Vitis ssp.) roots.

Gall forming phylloxera may compete for nutrients with meristematic tissues and develop heterotrophic structures that act as carbon sinks. In this work, we studied the underlying starch metabolism, sink-source translocation of soluble sugars towards and within root galls. We demonstrated that nodosities store carbohydrates by starch accumulation and monitored the expression of genes involved in the starch metabolic. Thereby we proved that the nodosity is symplastically connected to the source tissues through its development and that the starch metabolism is significantly affected to synthesize and degrade starch within the gall. Genes required for starch biosynthesis and degradation are up-regulated. Among the carbohydrate transporters the expression of a glucose-6-phosphate translocater, one sucrose transporter and two SWEET proteins were increases, whereas hexose transporters, tonoplast monosaccharide transporter and Erd6-like sugar transporters were decreased. We found general evidence for plant response to osmotic stress in the nodosity as previously suggested for gall induction processes. We conclude that nodosities are heterogenous plant organs that accumulate starch to serve as temporary storage structure that is gradually withdrawn by phylloxera. Phylloxera transcriptionally reprograms gall tissues beyond primary metabolism and included downstream secondary processes, including response to osmotic stress.

Steam explosion pretreatment for enhancing biogas production of late harvested hay.

Grasslands are often abandoned due to lack of profitability. Extensively cultivating grassland for utilization in a biogas-based biorefinery concept could mend this problem. Efficient bioconversion of this lignocellulosic biomass requires a pretreatment step. In this study the effect of different steam explosion conditions on hay digestibility have been investigated. Increasing severity in the pretreatment induced degradation of the hemicellulose, which at the same time led to the production of inhibitors and formation of pseudo-lignin. Enzymatic hydrolysis showed that the maximum glucose yields were obtained under pretreatment at 220 °C for 15 min, while higher xylose yields were obtained at 175 °C for 10 min. Pretreatment of hay by steam explosion enhanced 15.9% the methane yield in comparison to the untreated hay. Results indicate that hay can be effectively converted to methane after steam explosion pretreatment.

Accurate analysis of formose reaction products by LC-UV: an analytical challenge.

This study presents a liquid chromatography-ultraviolet (LC-UV) method for the accurate analysis of formose reaction products with regard to sum parameters. Limitations encountered in gas chromatography (e.g., thermal stability of analytes) were overcome. First, alditols are O-benzoylated and subjected to reversed-phase chromatography. They are then detected by UV and by electrospray ionization-mass spectrometry (ESI-MS) for validation purposes. Compared with standard 2,4-dinitrophenylhydrazine labeling, the accuracy of results from LC-UV is dramatically improved due to enhanced chromatographic resolution and validation by ESI-MS. For the first time ever, LC-UV may be used to accurately quantify 2-hydroxymethylglycerol, a branched chain alditol, D,L-glyceraldehyde, D,L-galactose, which represents the group of D,L-iditol/galactose/glucose/mannose and D,L-erythrose in formose reaction products.