Photo splitting of bio-polyols and sugars to methanol and syngas.

Methanol is a clean liquid energy carrier of sunshine and a key platform chemical for the synthesis of olefins and aromatics. Herein, we report the conversion of biomass-derived polyols and sugars into methanol and syngas (CO+H2) via UV light irradiation under room temperature, and the bio-syngas can be further used for the synthesis of methanol. The cellulose and even raw wood sawdust could be converted into methanol or syngas after hydrogenolysis or hydrolysis pretreatment. We find Cu dispersed on titanium oxide nanorod (TNR) rich in defects is effective for the selective C-C bond cleavage to methanol. Methanol is obtained from glycerol with a co-production of H2. A syngas with CO selectivity up to 90% in the gas phase is obtained via controlling the energy band structure of Cu/TNR.

Effects of elevated UV-B radiation and N deposition on the decomposition of coarse woody debris.

Increases in nitrogen (N) deposition and ultraviolet-B (UV-B) radiation play an important role in global climate change. Because coarse woody debris (CWD) represents a sizeable proportion of total carbon (C) pool in forest ecosystems, understanding the response of CWD decomposition to increased UV-B and N deposition become necessary for evaluating forest C storage under global climate change. In this study, we investigated the respiration of CWD (RCWD) in response to increased UV-B and N deposition over a two-year period for two tree species in subtropical Chinese forests: Cunninghamia lanceolata (Lamb.) Hook. (CL) and Cinnamomum camphora (L.) Presl (CC). We found that N and UV-B treatment, alone or in combination, significantly promoted RCWD, which was further magnified by increased temperature. Moreover, the combined treatment (UV-B + N) far exceeded the sum of the individual effects of N and UV-B treatments. Our results indicated that the three components of global climate change (increased UV-B, N deposition, and warming) worked interactively to accelerate CWD decomposition in forest ecosystems, suggesting that the biogeochemical cycling of subtropical forests could be altered greatly in the future, and this alteration must be considered in modelling the effects of global climate change.

Effect of irradiation energy and residence time on decomposition efficiency of polycyclic aromatic hydrocarbons (PAHs) from rubber wood combustion emission using soft X-rays.

This research aims to investigate the effects of irradiation energy and residence time of soft X-ray irradiation in the decomposition of sixteen polycyclic aromatic hydrocarbons (PAHs) in smoke particles emitted from the Para rubber wood burning. The burning process was carried out in a tube furnace and the soft X-ray radiation used had a wave length of 0.13-0.41 nm. The irradiated (IR) and non irradiated (N-IR) smoke particles were collected simultaneously using a 10-stage Andersen sampler equipped with an inertial-filter stage (ANIF), in order to determine the physicochemical characteristic of both IR and N-IR smoke particles, including particle size distribution and concentration, and particle-bound PAHs concentration. Results show that the nano-size smoke particles contained the highest amount of PAHs and of carcinogenic potency equivalent (BaP-TEQ). About 75% of PAH compounds on the total smoke particles were decomposed at the highest irradiation energy. Moreover, 4-6 ring PAHs in nanoparticles (<70 nm) were decomposed of up to about 91% at the highest irradiation energy. The decomposition efficiency of PAHs was influenced by particle size, PAHs boiling temperature and irradiation energy. It was higher for PAHs with lower boiling temperature and smaller size particles, while the effect of residence time was not significant.

Protective behaviour monitoring on wood photo-degradation by spectroscopic techniques coupled with chemometrics.

This paper reports the investigation on the effect of protective materials on poplar (Populus sp.) wood modifications as consequence of artificial photo-degradation in controlled environment. The novelty of this work is to try to understand what happens to wood surface under the protective layer. Shellac, beeswax and Linfoil® were tested to compare traditional and novel products generally used for wood. The samples, uncovered and covered by these protective layers, were artificially aged. Colour and chemical modifications due to ageing were investigated at different time intervals by reflectance spectrophotometry, Fourier transform infrared spectroscopy and hyperspectral imaging. The obtained data were elaborated by statistical and chemometric tools in order to verify their significance and to assess the relationship between groups of measurements. The results highlighted that shellac, beeswax and Linfoil® materials have a very low protective effect on wood photo-degradation for long times of exposure, by little reducing the changes of wood components.

Cobalt-60 gamma-ray irradiation pretreatment and sludge protein for enhancing enzymatic saccharification of hybrid poplar sawdust.

In order to improve the enzymatic saccharification of hybrid poplar sawdust, gamma irradiation pretreatment and enzymatic hydrolysis in the presence of sludge protein were investigated. The cellulose crystallinity index were significantly decreased after irradiation pretreatment, and adding sludge protein improved enzyme activity and increased the reducing sugar yield. The conditions of irradiation pretreatment and enzymatic hydrolysis in the presence of sludge protein were systematically examined. The maximum reducing sugar yield was 519mg/g under an irradiation dose of 300kGy, a sludge protein dosage of 2mg/mL, an enzymatic hydrolysis temperature of 45°C, an enzymatic hydrolysis time of 84h, and a 90FPU/g enzyme loading. This work indicated that the combined method of gamma irradiation pretreatment and enzymatic hydrolysis in the presence of sludge protein was a promising potential for the saccharification of hybrid poplar sawdust.

Direct accumulation pathway of radioactive cesium to fruit-bodies of edible mushroom from contaminated wood logs.

This paper presents the accumulation process of radioactive Cs in edible mushrooms. We here first report the direct accumulation pathway of radioactive Cs from contaminated wood logs to the fruit-bodies of shiitake mushrooms through the basal portion of the stipe. In this pathway, radioactive Cs is not transported through the hyphae. This pathway results in a high accumulation of radioactive Cs in the fruit-body, more by the excess accumulation of radioactive Cs from the wood logs than that through the hyphae. We grew the fruit-bodies of Shiitake mushroom from radioactive-Cs-contaminated wood logs. The spatial distributions of radioactive Cs and Prussian blue as a tracer of interstitial water in the cross section of the wood log measured after the harvest of the fruit-body from the inoculated sawdust spawn area indicated that some fraction of the radioactive Cs and Prussian blue were transported directly to the basal portion of the stipe during the growth of the fruit-bodies.

The effect of red light and far-red light conditions on secondary metabolism in agarwood.

BACKGROUND: Agarwood, a heartwood derived from Aquilaria trees, is a valuable commodity that has seen prevalent use among many cultures. In particular, it is widely used in herbal medicine and many compounds in agarwood are known to exhibit medicinal properties. Although there exists much research into medicinal herbs and extraction of high value compounds, few have focused on increasing the quantity of target compounds through stimulation of its related pathways in this species. RESULTS: In this study, we observed that cucurbitacin yield can be increased through the use of different light conditions to stimulate related pathways and conducted three types of high-throughput sequencing experiments in order to study the effect of light conditions on secondary metabolism in agarwood. We constructed genome-wide profiles of RNA expression, small RNA, and DNA methylation under red light and far-red light conditions. With these profiles, we identified a set of small RNA which potentially regulates gene expression via the RNA-directed DNA methylation pathway. CONCLUSIONS: We demonstrate that light conditions can be used to stimulate pathways related to secondary metabolism, increasing the yield of cucurbitacins. The genome-wide expression and methylation profiles from our study provide insight into the effect of light on gene expression for secondary metabolism in agarwood and provide compelling new candidates towards the study of functional secondary metabolic components.

On radiation damage in FIB-prepared softwood samples measured by scanning X-ray diffraction.

The high flux density encountered in scanning X-ray nanodiffraction experiments can lead to severe radiation damage to biological samples. However, this technique is a suitable tool for investigating samples to high spatial resolution. The layered cell wall structure of softwood tracheids is an interesting system which has been extensively studied using this method. The tracheid cell has a complex geometry, which requires the sample to be prepared by cutting it perpendicularly to the cell wall axis. Focused ion beam (FIB) milling in combination with scanning electron microscopy allows precise alignment and cutting without splintering. Here, results of a scanning X-ray diffraction experiment performed on a biological sample prepared with a focused ion beam of gallium atoms are reported for the first time. It is shown that samples prepared and measured in this way suffer from the incorporation of gallium atoms up to a surprisingly large depth of 1 µm.

Measurement of photodegradation-caused roughness of wood using a new optical method.

The aim of this study was to clarify the intensity of the surface roughening of wood caused by light radiation using a fast optical method. The samples were irradiated by mercury lamp and the roughness change was monitored traditionally using a perthometer. The infrared (IR) diffuse reflectance spectrum was measured and the baseline shift was found to be a proper parameter to monitor the roughening effect of photodegradation. Linear correlation was found between the traditionally measured roughness and the baseline shift. This newly developed optical method is able to detect the degradation difference between earlywood and latewood. Some of the samples were immersed in distilled water for a day after an all light irradiation period of two days. This new baseline shift method was able to visualise and determine the small change in roughness caused by the leaching effect of water.

Severity factor coefficients for subcritical liquid hot water pretreatment of hardwood chips.

Single stage and multi-stage liquid hot water pretreatments of mixed hardwood pinchips were investigated at various severities (log R0 = 3.65-4.81) to assess the efficiencies of the pretreatments with respect to achieving high pentose sugar yields and improved enzymatic digestibility of pretreated cellulose. We investigate the effect of pretreatment parameters that is, temperature, and time, as expressed in the severity factor, on the recovery of sugars and hydrolyzability of pretreated cellulose. We find the severity factor, in its widely used form, is an incomplete measure for evaluating the pretreatment efficiencies and predicting overall sugar yields when pretreatment temperatures above 200°C are used. Corrections to the severity factor and its correlation to the measured pretreatment responses (% xylan solubilization, xylan recovery as fermentable sugars, cellulose enzymatic digestibility) indicate a greater influence of temperature on the pretreatment efficiencies than predicted by the commonly used severity factor. A low temperature, long residence time is preferred for hemicellulose dissolution during the pretreatment since the condition favors oligosaccharide and monomeric sugar formation over sugar degradation. On the contrary, high cellulose hydrolyzability is achieved with a high temperature (>200°C), high severity pretreatment when pretreatment is followed by enzyme hydrolysis. In multi-stage pretreatment, the first low-severity pretreatment is optimized for solubilizing fast-hydrolyzing hemicellulose while minimizing formation of furans. The subsequent pretreatment is carried out at over 200°C to recover the difficult-to-hydrolyze hemicellulose fraction as well as to increase susceptibility of pretreated cellulose to enzymes. High recovery (>92%) of hemicellulose-derived pentose sugars and enhanced enzymatic hydrolysis of pretreated cellulose (where >80% glucose yield results with 20 FPU = 32 mg protein/g glucan or 10-13 mg/g initial hardwood) are achieved by applying a multi-stage pretreatment. This work shows how the severity equation may be used to obtain a single characteristic curve that correlate xylan solubilization and enzymatic cellulose hydrolysis as a function of severity at pretreatment temperatures up to 230°C.

[Changes in chemistry component structure and microstructure characterization of acetylated wood before and after UV radiation].

The poplar powder was acetylated with different duration as sample, processed ray radiation by using ultraviolet test box, contrasting the influences to lightfastness of wood with different acetylation degree, analyzing changing rules of characteristic peaks' intensity which belonged to the chemistry components of samples based on FTIR spectra, and the relationship between duration of acetylation and changes of chemistry components was established, The results showed that: Before UV radiation, the characteristic peaks' intensity of acetylated poplar powder at 1 739 cm(-1) which belonged to C = O in saturated esters compounds and 1 385 cm(-1) which belonged to C-H in acetate were higher than untreated ones', the poplar powder with 40 min's acetylation has the highest characteristic peaks' intensity, highest weight gain rate, remarkable acetylation effect; After UV radiation, characteristic peaks' intensity of Benzene at 1 504 cm(-1) which belonged to lignin of poplar powder was obviously higher than untreated ones', and characteristic peaks' intensity of poplar powder with 40 min's acetylation was the highest, this showed that acetylation could effectively reduce the light degradation of wood chemistry components, in order to improve the lightfastness, especially the poplar powder with 40 min's acetylation; SEM photos showed that, the fibrous surface of acetylated poplar powder was more smooth and had more narrow particle size than untreated ones', so acetylation can effectively improve the stability of wood.

Effects of nutrient optimization on intra-annual wood formation in Norway spruce.

In the Nordic countries, growth of Norway spruce (Picea abies (L.) Karst.) is generally limited by low availability of nutrients, especially nitrogen. Optimizing forest management requires better insight on how growth responds to the environmental conditions and their manipulation. The aim of this study was to analyse the effects of nutrient optimization on timing and the rate of tracheid formation of Norway spruce and to follow the differentiation of newly formed tracheids. The study was performed during two growing seasons in a long-term nutrient optimization experiment in northern Sweden, where all essential macro- and micronutrients were supplied in irrigation water every second day from mid-June to mid-August. The control plots were without additional nutrients and water. Tracheid formation in the stem was monitored throughout the growing season by weekly sampling of microcores at breast height. The onset of xylogenesis occurred in early June, but in early summer there were no significant between-treatment differences in the onset and relative rate of tracheid formation. In both treatments, the onset of secondary cell wall formation occurred in mid-June. The maximum rate of tracheid formation occurred close to the summer solstice and 50% of the tracheids had been accumulated in early July. Optimized nutrition resulted in the formation of ∼50% more tracheids and delayed the cessation of tracheid formation, which extended the tracheid formation period by 20-50%, compared with control trees. The increased growth was mainly an effect of enhanced tracheid formation rate during the mid- and later-part of the growing season. In the second year, the increased growth rate also resulted in 11% wider tracheids. We conclude that the onset and rate of tracheid formation and differentiation during summer is primarily controlled by photoperiod, temperature and availability of nutrients, rather than supply of carbohydrates.

Fluorescence lifetime imaging of lignin autofluorescence in normal and compression wood.

Wood cell walls fluoresce as a result of UV and visible light excitation due to the presence of lignin. Fluorescence spectroscopy has revealed characteristic spectral differences in various wood types, notably normal and compression wood. In order to extend this method of characterising cell walls we examined the fluorescence lifetime of wood cell walls using TCSPC (Time-Correlated Single Photon Counting) as a method of potentially detecting differences in lignin composition and measuring the molecular environment within cell walls. The fluorescence decay curves of both normal and compression wood from pine contain three exponential decay components with a mean lifetime of τm = 473 ps in normal wood and 418 ps in compression wood. Lifetimes are spatially resolved to different cell wall layers or cell types where individual lifetimes are shown to have a log-normal distribution. The differences in fluorescence lifetime observed in pine compression wood compared to normal wood, are associated with known differences in cell wall composition such as increased p-hydroxyphenyl content in lignin as well as novel deposition of ß(1,4)-Galactan. Our results indicate increased deposition of lignin fluorophores with shorter lifetimes in the outer secondary wall of compression wood. We have demonstrated the usefulness of fluorescence lifetime imaging for characterising wood cell walls, offering some advantages over conventional fluorescence imaging/spectroscopy. For example, we have measured significant changes in fluorescence lifetime resulting from changes to lignin composition as a result of compression wood formation that complement similar changes in fluorescence intensity.

Structural study of photodegraded acrylic-coated lime wood using Fourier transform infrared and two-dimensional infrared correlation spectroscopy.

The weathering of acrylic films and acrylic-coated lime wood (Tillia cordata Mill.) were examined using Fourier transform infrared (FT-IR) and two-dimensional infrared correlation spectroscopy. The obtained results showed chemical changes induced by exposure to weathering conditions, in both films and coated wood. The observed spectral changes of the acrylic films refer to the absorption band assigned to the C-O stretching, which progressively decreases with increasing exposure time. In the spectra of treated wood samples the main signal indicating the advance of oxidation during the photodegradation exposure is the gradual increase and broadening of the band in the carbonyl region. This is due to the formation of the non-hydrogen bonded aliphatic carboxylic acids and γ-lactone structures in the acrylic resin and of the nonconjugated ketones, carboxyl groups, and lactones in wood. As a consequence, the increase of the 1734 cm(-1) band is due to the degradation of lignin from wood surface. These observations are also supported by the decreased intensities of the bands at 1598 and 1505 cm(-1), assigned to C=C of aromatic skeletal (lignin). The relative intensity of the characteristic aromatic lignin band at 1505 cm(-1) decreases up to 25% of its original value after weathering, being less than half of the value obtained for uncoated wood. Two-dimensional infrared (2D IR) correlation spectroscopy was used to identify the sequence of the modifications of the different stretching vibrations bands under the weathering conditions, the method allowing the prediction of the order of degradation reactions. The acrylic resin degradation starts with the formation of radicals by abstraction of the tertiary hydrogen atoms of the methyl acrylate units and the α-CH3 groups from the ethyl methacrylate units. The subsequent decomposition and oxidation led to the formation of alcohol groups, hydroperoxides, ketones, and/or carboxylic acid groups. The 2D IR correlation spectra of weathered impregnated wood also revealed the elimination of low molecular weight compounds following the degradation of lignin and carbohydrates components from wood.

A photochemical method for improvement of color stability at polymer-wood biointerfaces.

The possibility of photochemical improvement of color stability by UV-irradiation treatment at coating-wood biointerfaces was investigated. The surface of beech wood was partially delignified by exposure to UV-irradiation by passing of samples under UV lamps: a mercury (Hg) lamp with a peak wavelength of 366nm, a gallium (Ga) lamp with peak wavelengths at 410 and 420nm and a combination of a mercury and a gallium (Hg+Ga) lamp. After UV-irradiation, the samples were coated with a UV-curable acrylic coating. The number of passes under the lamps was varied to determine the optimum combination of the number of passes and the lamp type that produces the smallest change in color of the coated wood in an indoor environment. The coated samples that had been UV-irradiated by passing 15 times under both an Hg lamp and a Ga lamp showed the smallest change in color (decrease in the ΔE by 23.23% compared to the untreated coated samples) after 72h of accelerated artificial sunlight exposure. Microscope images of the same samples showed deformation of the cells in wood surface layer and a roughening of the ?wood-coating line", which could be related to a partial removal of lignin. These findings suggest that delignification of wood leads to more photo-stable polymer-wood interfaces in terms of color.

Photodegradation of thermally modified wood.

Natural wood, being biological material, undergoes rapid degradation by ultraviolet (UV) radiations and other environmental factors under outdoor exposure. In order to protect wood from such degradation, the chemical structure of wood is altered by chemical modification or heat treatment. In the present study, heat treated specimens of rubberwood (Hevea brasiliensis) were exposed to xenon light source in a weather-o-meter for different periods up to 300 h. Photostability of modified and unmodified wood was evaluated in terms of colour and chemical changes. Light coloured untreated wood became dark upon UV irradiation whereas, dark colour of heat treated wood lightened on UV exposure. CIE lightness parameter (L(*)) decreased for untreated wood whereas its value increased for heat treated wood upon irradiation. Other colour coordinates a(*) and b(*) increased with exposure duration for both untreated and heat treated wood. The overall colour change (ΔE(*)) increased for both untreated and heat treated wood. The Fourier Transform Infrared (FTIR) spectroscopic studies revealed severe lignin degradation of heat treated wood due to UV light exposure. Colour changes and FTIR measurements indicate that thermal modification of wood was ineffective in restricting light induced colour changes and photodegradation of wood polymers.

Changes in DRIFT spectra of wood irradiated by lasers of different wavelength.

An exact wavelength separation of the spectrum cannot be accomplished when utilizing common ultraviolet (UV) light sources, so the dependence of photodegradation on wavelength cannot be done directly. The photodegradation of wood resulted in by laser irradiation on various wavelengths can be studied by comparing the changes in the DRIFT spectra of various wood materials. The analysis of the difference spectrum is a widely used method to investigate the changes in the infrared spectrum. As this procedure cannot be used to compare the changes quantitatively, a new indicator was introduced, termed Band Damage Index (BDI). The BDI and the results obtained by its analysis are going to be discussed.

The response to daylight or continuous ozone of phenylpropanoid and lignin biosynthesis pathways in poplar differs between leaves and wood.

Ozone induces a stimulation of the phenylpropanoid and lignin biosynthesis pathways in leaves but the response of wood, the main lignin-producing tissue, is not well documented. The purpose of this study was to compare the responses of phenylpropanoid and lignin pathways in leaves and stem wood by a simultaneous analysis of both organs. Young poplars (Populus tremula×alba) were subjected either to daylight ozone (200 nL L(-1) during light period) or continuous ozone (200 nL L(-1) during light and dark periods) in controlled chambers. The trees were tilted so as to limit the formation of tension wood to the upper side of the stem and that of opposite wood to the lower side. Continuous ozone fumigation induced more pronounced effects in leaves than daylight ozone. Tension wood and opposite wood displayed similar responses to ozone. Enzyme activities involved in phenylpropanoid and lignin biosynthesis increased in the leaves of ozone-treated poplars and decreased in the wood. All steps involved in phenylpropanoid and monolignol synthesis in leaves and stem wood, were also altered at the transcript level (except coniferyl aldehyde 5-hydroxylase in leaves) suggesting that the responses were tightly coordinated. The response occurred rapidly in the leaves and much later in the wood. Phenylpropanoid and lignin biosynthesis is probably first involved in a defensive role against ozone in the leaves, which would lead to considerable rerouting of the carbon skeletons. The later response of phenylpropanoid and lignin metabolism in wood seemed to result from readjustment to the reduced carbon supply.

Photodegradation of wood at elevated temperature: colour change.

The purpose of this investigation was to evaluate the effect of elevated temperature on the photodegradation of solid wood. The work presented here, dealt with the changes of colour during the degradation process. Wood samples were irradiated by mercury vapour lamp at 80°C and at 30°C to screen out the effect of thermal decomposition during photodegradation. Results demonstrated that the same light irradiation resulted in considerably greater redness increase at 80°C than at 30°C. Pine samples showed 57% higher redness change at 80°C than at 30°C during the 200h light exposure. Corresponding data for spruce, ash and poplar were 33%, 40% and 15%, respectively. Results indicated that the extractive content has an important role in thermal decomposition during photodegradation. The elevated environmental temperature did not affect yellowness.