Effect of methyltrimethoxysilane impregnation on the cell wall porosity and water vapour sorption of archaeological waterlogged oak

This paper presents the water vapour sorption behaviour of degraded archaeological oak (Quercus robur L.) and the influence of methyltrimethoxysilane treatment on hygroscopicity. Wood samples (archaeological and undegraded recent oak) were treated with methyltrimethoxysilane using an oscillating pressure method. Moisture properties of the samples were determined using a dynamic vapour sorption system, and the surface area and porosity of treated and untreated waterlogged wood, previously dried using different methods, were characterised using a nitrogen sorption method. It was found that the silane modification resulted in a decrease in the equilibrium moisture content of archaeological oak samples from 23.7 to 19.4% for heartwood and from 23.3 to 10.0% for sapwood, respectively. After correction for silane content, however, the maximum equilibrium moisture content of the treated samples was 23.6% for heartwood and 21% for sapwood, which points rather at a bulking mechanism than chemical modification by silane. The results of the surface area and porosity measurements indicate that methyltrimethoxysilane is deposited in the cell wall and thus helps to preserve the microstructure of archaeological waterlogged wood.publishedVersio

Effects of Biological and Chemical Degradation on the Properties of Scots Pine Wood—Part I: Chemical Composition and Microstructure of the Cell Wall

Research on new conservation treatment for archaeological wood requires large amounts of wooden material. For this purpose, artificial wood degradation (biological—using brown-rot fungus Coniophora puteana, and chemical—using NaOH solution) under laboratory conditions was conducted to obtain an abundance of similar samples that mimic naturally degraded wood and can serve for comparative studies. However, knowledge about its properties is necessary to use this material for further study. In this study, the chemical composition and microstructure of degraded cell walls were investigated using FT-IR, XRD, helium pycnometry and nitrogen absorption methods. The results show that biological degradation caused the loss of hemicelluloses and celluloses, including the reduction in cellulose crystallinity, and led to lignin modification, while chemical degradation mainly depleted the amount of hemicelluloses and lignin, but also affected crystalline cellulose. These changes affected the cell wall microstructure, increasing both surface area and total pore volume. However, the chemical degradation produced a greater number of mesopores of smaller size compared to fungal decomposition. Both degradation processes weakened the cell wall’s mechanical strength, resulting in high shrinkage of degraded wood during air-drying. The results of the study suggest that degraded wood obtained under laboratory conditions can be a useful material for studies on new consolidants for archaeological wood

Effects of Biological and Chemical Degradation on the Properties of Scots Pine Wood—Part I: Chemical Composition and Microstructure of the Cell Wall

Research on new conservation treatment for archaeological wood requires large amounts of wooden material. For this purpose, artificial wood degradation (biological—using brown-rot fungus Coniophora puteana, and chemical—using NaOH solution) under laboratory conditions was conducted to obtain an abundance of similar samples that mimic naturally degraded wood and can serve for comparative studies. However, knowledge about its properties is necessary to use this material for further study. In this study, the chemical composition and microstructure of degraded cell walls were investigated using FT-IR, XRD, helium pycnometry and nitrogen absorption methods. The results show that biological degradation caused the loss of hemicelluloses and celluloses, including the reduction in cellulose crystallinity, and led to lignin modification, while chemical degradation mainly depleted the amount of hemicelluloses and lignin, but also affected crystalline cellulose. These changes affected the cell wall microstructure, increasing both surface area and total pore volume. However, the chemical degradation produced a greater number of mesopores of smaller size compared to fungal decomposition. Both degradation processes weakened the cell wall’s mechanical strength, resulting in high shrinkage of degraded wood during air-drying. The results of the study suggest that degraded wood obtained under laboratory conditions can be a useful material for studies on new consolidants for archaeological wood

Evaluation of the Effect of a Combined Chemical and Thermal Modification of Wood though the Use of Bicine and Tricine

The effects of thermal modification of wood have been well established, particularly in terms of reductions in mechanical performance. In recent years, there has been an increase in studies related to the Maillard reaction. More commonly associated with food chemistry, it involves the reaction of amines and reducing sugars during cooking procedures. This study has attempted to combine the use of amines and thermal modification, with subsequent properties investigated for the treatment of spruce (Picea abies (L.) H. Karst) and beech (Fagus sylvatica L.). In this initial study, the combined effects of chemical treatments by tricine and bicine were investigated with thermal modification. Along with some preliminary data on mechanical properties, the modifications which appeared in the wood structure were evaluated by infrared spectroscopy and biological studies according to EN113 and EN117 methodologies. The hierarchal study interpretation of FTIR suggested interactions between the bicine or tricine and the wood, which was partly supported by the analysis of volatile organic compounds (VOC), though other tests were not as conclusive. The potential of the method warrants further consideration, which will be described

Comparative Toxicity of Nanoparticulate CuO and ZnO to Soil Bacterial Communities

The increasing industrial application of metal oxide Engineered Nano-Particles (ENPs) is likely to increase their environmental release to soils. While the potential of metal oxide ENPs as environmental toxicants has been shown, lack of suitable control treatments have compromised the power of many previous assessments. We evaluated the ecotoxicity of ENP (nano) forms of Zn and Cu oxides in two different soils by measuring their ability to inhibit bacterial growth. We could show a direct acute toxicity of nano-CuO acting on soil bacteria while the macroparticulate (bulk) form of CuO was not toxic. In comparison, CuSO4 was more toxic than either oxide form. Unlike Cu, all forms of Zn were toxic to soil bacteria, and the bulk-ZnO was more toxic than the nano-ZnO. The ZnSO4 addition was not consistently more toxic than the oxide forms. Consistently, we found a tight link between the dissolved concentration of metal in solution and the inhibition of bacterial growth. The inconsistent toxicological response between soils could be explained by different resulting concentrations of metals in soil solution. Our findings suggested that the principal mechanism of toxicity was dissolution of metal oxides and sulphates into a metal ion form known to be highly toxic to bacteria, and not a direct effect of nano-sized particles acting on bacteria. We propose that integrated efforts toward directly assessing bioavailable metal concentrations are more valuable than spending resources to reassess ecotoxicology of ENPs separately from general metal toxicity

Experimental method to quantify progressive stages of decay of wood by basidiomycete fungi.

A biological exposure method was developed that allows wood samples to be progressively removed for monitoring colonization and decay by basidiomycete fungi. Monitoring involves strength tests, determination of weight loss, and chemical analysis. To optimize the procedure, several variations of the method were tested using two species of brown-rot fungi (Gloeophyllum trabeum and Oligoporus placentus (Postia placenta)) and one white-rot species (Trametes versicolor) against southern pine sapwood. The variations involved type of culture medium and exposure method. All variations enabled substantial and rapid decay. Specimens exposed to brown-rot fungi lost 80-100% strength and 25-40% weight after 12 weeks; the white-rot fungus was less effective, but nevertheless caused 20-40% loss in strength. For both brown- and white-rot fungi, strength loss exceeded weight loss. For brown-rot fungi, there was a direct relationship between strength loss and weight loss, suggesting a quantitative relationship between strength loss and chemical composition (hemicellulose sugars) during incipient decay of southern pine by these fungi

Effect of methyltrimethoxysilane impregnation on the cell wall porosity and water vapour sorption of archaeological waterlogged oak

This paper presents the water vapour sorption behaviour of degraded archaeological oak (Quercus robur L.) and the influence of methyltrimethoxysilane treatment on hygroscopicity. Wood samples (archaeological and undegraded recent oak) were treated with methyltrimethoxysilane using an oscillating pressure method. Moisture properties of the samples were determined using a dynamic vapour sorption system, and the surface area and porosity of treated and untreated waterlogged wood, previously dried using different methods, were characterised using a nitrogen sorption method. It was found that the silane modification resulted in a decrease in the equilibrium moisture content of archaeological oak samples from 23.7 to 19.4% for heartwood and from 23.3 to 10.0% for sapwood, respectively. After correction for silane content, however, the maximum equilibrium moisture content of the treated samples was 23.6% for heartwood and 21% for sapwood, which points rather at a bulking mechanism than chemical modification by silane. The results of the surface area and porosity measurements indicate that methyltrimethoxysilane is deposited in the cell wall and thus helps to preserve the microstructure of archaeological waterlogged wood.publishedVersio

Simulation Model to Evaluate Human Comfort Factors for an Office in a Building

According to the literature, both advanced and developing countries are facing several challenges due to the lack of clean energy and emissions of CO2 leading to climate change. Especially in the built environment, energy efficient buildings are highly desirable to save energy without affecting occupant’s health while providing an acceptable indoor environment and thermal conditions. The use of insulation, passive solar heating, and HVAC systems can contribute to improve the indoor thermal comfort. In the present study, a numerical simulation model is developed to evaluate the human comfort factors in a simulated indoor environment. The CFD model considers the thermal interaction of humans with the indoor environment. Ventilation and a heat source are added to model a workspace for evaluating indoor air temperature and human comfort factors. Indices like predicted mean vote (PMV) and predicted percentage dissatisfaction (PPD) are evaluated to assess thermal sensation of human body when adding and removing a heat source in the model office (i.e., radiator)

Free Cu in in soil solutions.

<p>The relationship between Cu concentration in soil solution and the application rate of nano-CuO (panels A, D), bulk-CuO (panels B, E) and CuSO₄ (panels C, F) in mineral (panels A, B, C) and organic (D, E, F) soils. Note the broken y-axis scales (panels C, F). Datapoints are the mean of three replicate analyses ±1 SE. Sometimes error bars are hidden by symbols.</p