Low Lignin Content Research Articles

Carbon Dynamics Along a Temperate Fjord‐Head Delta: Linkages With Carbon Burial in Fjords

AbstractWe used seven 210Pb‐dated sediment cores from the Gaer Arm in the Doubtful Sound fjord complex, Fiordland, New Zealand to evaluate organic carbon (OC) dynamics in a temperate fjord‐head delta. The highly dynamic spatial features of this delta were clearly evident in the observed sediment properties such as mass accumulation rates that varied by a factor of 14, sediment grain size by a factor 5, and sedimentary OC content by a factor 6. Low lignin concentrations (e.g., 2.95 mg (100 mg OC)−1) and syringic/vanillic ratios of lignin phenols (S/V; e.g., 0.44) at the upper deltaic stations were representative of substantial autochthonous OC contributions to delta sediments. Significantly higher acid/aldehyde ratios of vanillic phenols [(Ad/Al)v] at the deltaic stations (0.45–0.82) than the surface grabs (0.26–0.30) indicated rapid degradation of OC within the delta. Despite being a “hot spot” for OC oxidation, the delta likely improves OC preservation in the adjacent fjord by filtering out coarse‐grained particles and exporting fine‐grained particles to fjord sediments. Our results showed that fjord‐head deltas can influence sedimentation and OC dynamics in select regions of fjords and thus warrant more examination of fjord‐head processes, particularly in areas where they are expanding. In particular, as Earth warms and glaciers retreat, the newly exposed fjord‐head platforms in high‐latitude environments may evolve into similar “hot spots” of OC oxidation, thereby altering the dynamics of OC burial in these systems.

Production of cellulose pulp from agribusiness waste: experimental analysis of factors affecting the characteristics of pulp for absorbent purposes

Sustainable production is a recurrent theme in industrial engineering. Commercial production of canned palm hearts generates an amount of waste from the leaf sheaths that envelop the heart of palm, which can be used to produce cellulose pulp then reducing environmental impacts. This study aims to examine the feasibility of cellulose pulping from King Palm leaf sheaths to obtain a fiber with absorbent capacity and low residual lignin content, as well as demonstrate the influence of the controllable process factors on the response variables analyzed through the formulation of n-dimensional equations and surfaces which permitted the optimization of the variables of interest. The response variables were selected in order to characterize the fiber obtained according to degree of delignification, absorption capability and speed and apparent density. The results indicated that the pulps obtained from the processes proposed although didn’t meet the quality standards required for absorbent pulps, since values are lower than those established in the research hypotheses, is very promising. This attempt raises the discussion around the role that industrial engineering professionals and researchers may play in the agribusiness waste recovery and recycling. Moreover it provides useful information for re-planning of experiments in search for extraction optimization of this or similar agribusiness wastes.

Chemical and bioenergetic characterization of sorghum agronomic groups1

ABSTRACT The global demand and production of primary energy is expected to grow at a rate of 1.4 % per year by 2035. In the same period, the production of renewable energy is expected to grow at a rate of 6.6 % per year, rising from 3 % to 9 % of world primary energy. Therefore, the biofuels supply assumes a strategic role for world energy security. In this context, sorghum is a promising alternative in the bioenergetic sector, due to its agronomic characteristics and adaptability to limiting edaphoclimatic conditions. This study aimed at evaluating the productive potential of three sorghum agronomic groups (biomass, saccharin and forage), as well as chemically characterizing the biomass of these materials. For that, a field experiment was carried out using a randomized block design, where agronomic and chemical characteristics (cellulose, hemicellulose, lignin and ash), as well as moisture contents, were evaluated. The biomass sorghum cultivars presented a high yield (about 30 t ha-1 of dry stalk), being, for this reason, more suitable for the generation of solid biofuels, i.e., direct burning. On the other hand, the forage sorghum cultivars presented a lower lignin content in the stalks, in relation to the other cultivars, being indicated for the generation of liquid biofuels. It is also worth mentioning the possibility of producing second-generation bioethanol from saccharin sorghum bagasse. Therefore, sorghum presents different use potentials that may be exploited by the bioenergy sector according to the agronomic group and plant physical part.

Evaluation of the differences in phenolic compounds and antioxidant activities of five green asparagus (Asparagus officinalisL.) cultivars

Phenolic compounds and total antioxidant activities were analysed in five green asparagus cultivars (Grande, Altas, UC800, UC301 and UC157). In addition, the colours as well as the lignin, amino acid, and microelement contents of the asparagus cultivars were assessed. Cultivar ‘Grande’ had the best greenness (a*=-12.47), the highest vitamin C (59.1 mg/kg) and microelement contents (282.3 mg/kg) and the lowest lignin content (0.92%). Cultivar ‘UC301’ had the highest amino acid content (3.95 g/kg), and cultivar ‘UC157’ had the highest total phenolic and total flavonoid contents. Correlations were determined to evaluate the relationship between phenolic compounds and total antioxidant activity. Phenolic compounds, particularly rutin, are major contributors to the antioxidant activity of green asparagus, with a correlation coefficient of r=0.977-0.982. A principal component analysis was then performed to investigate the interrelationships between the parameters and the investigated cultivars. The results showed that cultivars ‘UC157’ and ‘Grande’ had high total phenolic and rutin contents and consequently high antioxidant activity. The cultivar had a marked influence on bioactive constituents, particularly the phenolic compound content and composition, and on the antioxidant activity of green asparagus, which may provide a basis for improved health benefits and breeding programs.

Characterisation of 19th and 20th century Chinese paper

The chemical and physical properties of 19th and 20th century Chinese papers were investigated using a variety of material characterisation methods. A reference collection of 178 Chinese papers, dating from 1799 to 1990 was used, and properties such as pH, degree of polymerisation (DP), lignin content, and tensile strength (zero-span) were determined. Most of the papers were of approximately neutral pH, had a low lignin content and DP similar to pre-19th century European rag paper. It was found that the high inhomogeneity and the typical paper thinness affected tensile testing and as a result, a modified method for zero-span tensile strength test was developed. Using near infrared spectroscopy (NIR), proof-of-concept partial least squares (PLS) applications were developed for determination of tensile strength, pH, DP and for dating of the samples. For the latter, using post-1900 papers, the error of cross validation was 13 years. The presence of lignin was modelled using linear discriminant analysis (LDA), where the model could distinguish between high and low lignin content with 88% accuracy. Using one or multiple sheets for transmission NIR spectroscopy led to PLS results of similar quality, which was attributed to material inhomogeneity.

Availability of four energy crops assessing by the enzymatic hydrolysis and structural features of lignin before and after hydrothermal treatment

The anatomical characteristics, chemical composition, enzymatic hydrolysis efficiency and lignin characteristics of four energy crops (switchgrass, Miscanthus × giganteus, Hybrid Pennisetum, and Triarrhena lutarioriparia) before and after hydrothermal treatment (180 °C, 1 h) were investigated comprehensively to evaluate their potential for the bioenergy production. The hydrothermal treatment resulted in the deconstruction of the biomass cell walls and redistribution of the main components, accompanying with the removal of most hemicelluloses and partial lignin as well as favorable exposure of cellulose. These alterations significantly increased the efficiency of enzymatic hydrolysis, and the different recalcitrance of the four feedstocks was evenly erased by hydrothermal treatment. Among the four crops, Hybrid Pennisetum with high cellulose and low lignin contents had a better performance in the enzymatic hydrolysis process both before and after treatment. Meanwhile, the maximum concentration of low degree of polymerization xylo-oligosaccharides (2-6) and the lowest amount of degraded products were obtained from Hybrid Pennisetum during the treatment process. Moreover, the structural features of the residual lignin in the treated substrates were elaborately analyzed for deeply understanding the fundamental chemistry of lignin during the treatment. The present study is beneficial to the fully effective utilization of biomass components and extension of the energy sources.

Statistical optimization of acid catalyzed steam pretreatment of citrus peel waste for bioethanol production

Citrus waste is an attractive lignocellulosic biomass for the production of bioethanol due to the richness in carbohydrates and low lignin content. In this study, sweet lime peel was chosen as the lignocellu- losic biomass. To increase the cellulose for enzymatic hydrolysis, the statistical optimization of process parameters namely, solid loading, time of exposure and sulphuric acid concentration for pretreatment of sweet lime peel were accomplished by Taguchi orthogonal array design. The sweet lime peel was exposed to acid catalyzed steam pretreatment for solid loading [10%, 12%, 15% and 17% (w/v)], time of exposure [15 min, 30 min, 45 min and 60 min] and sulphuric acid concentration [0.25%, 0.5%, 0.75% and 1% (v/v)]. The cellulose content was found to be an optimum at 35% for 17% (w/v) solid loading and 0.25% (v/v) acid concentration and steam exposure for 60 min. With these optimized process parameters, enzymatic hy- drolysis of pretreated sweet lime peel was investigated at 50 °C for 48 h using in vitro isolated enzymes, viz., cellulase and pectinase from Aspergillus Niger with an activity of 1.7 FPU/ml and15 IU/ml respectively. 7.09 mg of reducing sugar/ml of hydrolysate was released in enzymatic hydrolysis which was estimated by DNS method. For the production of bioethanol, fermentation of hydrolysate was carried out at 30 °C for 72 h using baker’s yeast. The yield of ethanol was 18%. From this study, it is proved that citrus waste is a promising source for the production of bioethanol.

Exploring an oxidative bleaching treatment for Chilean bamboo: a source of cellulose for biofuel generation and the nanotech industry

Quila (Chusquea quila) is a very abundant native Chilean bamboo species. This work reports on a delignification process which can be applied to quila to produce crystalline cellulose, an important resource for obtaining cellulose nanofibres or nanocrystals. Alternatively, the crystalline cellulose can then be subjected to fermentation processes, making it a useful raw material for biofuel production. The treatment studied is an oxidative treatment at low concentration (15% v/v), for short time periods (10, 20 min) and at temperatures between 100 and 140 °C, which produces alpha-cellulose fibres with high crystallinity (over 70%) and low residual lignin content (< 2%). The morphology of the cellulose fibres was analysed by scanning electron microscope, revealing a smooth surface containing many fibrils. Infrared spectroscopy was used to identify functional groups, showing that almost 99% of the lignin was removed. The crystallinity index of the cellulose fibres after the reaction was up to 79%, making it an excellent raw material for processing cellulose nanofibres required by the emerging nanotech industry. Carbohydrate analysis revealed 86% glucose and 14% xylose, which makes quila a promising candidate as a precursor for biofuel generation.

Carboxylated Lignin as an Effective Cohardener for Enhancing Strength and Toughness of Epoxy

AbstractIt is demonstrated that pristine or functionalized lignin can be used in epoxy as a cohardener or comonomer; however either unsatisfactory mechanical properties or low lignin content remains a challenge in utilizing the sustainable biomass to replace petrochemical product. In this study, carboxylic acid‐modified kraft lignin (lignin–COOH) is synthesized and used as a cohardener for epoxy with loading content of up to 10.0 wt%. With incorporation of 10.0 wt% of lignin–COOH, the resulting composite exhibits increments of 16%, 13%, 20%, and 95% on tensile modulus, flexural modulus, tensile strength, and toughness respectively, in contrast to neat epoxy. The good dispersion of lignin–COOH in epoxy, rigid aromatic structure of lignin, and the reduced crosslink density in the composite can simultaneously contribute to the high mechanical performance, which is verified by the thermal and mechanical analysis results. It suggests that lignin can be converted to effective alternative curing agents for epoxy thermosets.

Vernal freeze damage and genetic variation alter tree growth, chemistry, and insect interactions.

Anticipated consequences of climate change in temperate regions include early spring warmup punctuated by intermittent hard freezes. Warm weather accelerates leaf flush in perennial woody species, potentially exposing vulnerable young tissues to damaging frosts. We employed a 2×6 randomized factorial design to examine how the interplay of vernal (springtime) freeze damage and genetic variation in a hardwood species (Populus tremuloides) influences tree growth, phytochemistry, and interactions with an insect herbivore (Chaitophorus stevensis). Acute effects of freezing included defoliation and mortality. Surviving trees exhibited reduced growth and altered biomass distribution. Reflushed leaves on these trees had lower mass per area, lower lignin concentrations, and higher nitrogen concentrations, altered chemical defence profiles, and supported faster aphid population growth. Many effects varied among plant genotypes and were related with herbivore performance. This study suggests that a single damaging vernal freeze event can alter tree-insect interactions through effects on plant growth and chemistry. Differential responses of various genotypes to freeze damage suggest that more frequent vernal freeze events could also influence natural selection, favouring trees with greater freeze hardiness, and more resistance or tolerance to herbivores following damage.

Photodegradation effects are related to precipitation amount, precipitation frequency and litter traits in a desert ecosystem

Photodegradation due to litter exposure to solar UV radiation (UV) is presumed to contribute to the surprisingly fast decomposition in some arid and semi-arid regions; however, precipitation may affect the relative importance of photodegradation versus microbial decomposition in litter decomposition. To assess the dependence of photodegradation effects on precipitation, we subjected litters from three plant life forms (spring annual, summer annual and shrub) to two UV treatments (UV block and sunlight) combining four precipitation treatments (two frequencies plus two amounts) over 2.5 years. UV radiation increased k, and it interacted with litter type, with the strongest stimulating effects on low lignin content litter. Precipitation amount and frequency both affected k, and UV photodegradation was dependent on precipitation, with the strongest photodegradation effects in low frequency and low amount of precipitation. UV radiation decreased microbial PLFAs, and altered microbial community in two litters by depressing fungi development. High precipitation frequency significantly increased microbial PLFAs in E. oxyrrhynchum litter. Litter decomposition rate was negatively correlated with initial lignin concentration, and UV photodegradation effects increased with increasing lignin loss, suggesting that the increased decomposition rate under UV radiation may primarily result from photochemical mineralization of lignin, rather than from facilitation of microbial decomposition. Our results demonstrate that UV radiation plays an important role in desert litter decomposition. The dependence of photodegradation on litter type and precipitation underscores the importance of incorporating UV radiation-induced C release into modeling of C cycling in desert ecosystems.

Characterization and methane production of different nut residue wastes in anaerobic digestion

Nut residues are common wastes which abandoned with more than 5 million tons in China annually. In this study, anaerobic digestion (AD) was firstly applied to treat 18 kinds of nut residues and their characterization, methane production, and kinetics were comprehensively investigated. Results implied that nut residues with low lignin content, high lipid and carbohydrate contents, such as lotus seed shells (expressed the highest biodegradability of 95.11% among others), showed good performance in AD. Kinetic analysis proved that modified Gompertz and Cone model were well fitted to describe the AD process of nut residues. Multiple linear regression equation was developed to determine the correlation between experimental methane yield and biochemical compositions of different nut residues, based on which, the highest cumulative methane yield could be predicted. The findings of this research provided useful knowledge for bioconversion of nut waste to renewable energy, and also showed a promising possibility for practical industrial application in future.

Changes in Lignocellulosic Polymers, Carbon, and Energy in Switchgrass for Bioenergy Production

Core Ideas Depending on the energy conversion method, switchgrass may be harvested over 2 months prior to killing frost. Drought may have caused a delay in the fall increase in C concentrations in switchgrass. Switchgrass cellulose, hemicellulose, lignin, and energy contents were unaffected by drought. Few studies have intensively monitored switchgrass chemical components during natural drought conditions. Switchgrass (Panicum virgatum L.) is a potential bioenergy crop recommended by the U.S. Department of Energy. To produce biofuel from switchgrass, high cellulose and low lignin concentrations are ideal for biochemical conversion while high lignin and energy content are desirable for thermochemical conversion. These values change during plant growth. The objective of this study was to identify the optimum harvest window using a one‐cut system. Thirteen and eight harvests were collected in 2011 and 2012, respectively, and analyzed for cellulose, hemicellulose, lignin, total C, and energy content. Generally, cellulose and hemicellulose concentrations increased through July, remained relatively constant for the remainder of the study period (through early November), and were unaffected by drought. Carbon concentrations increased significantly with plant growth then decreased significantly in July/August, presumably due to reproductive growth, followed by a significant increase in September or October of 2011 and 2012 due to senescence. Drought in early 2012 may have caused small changes in C concentration as compared to 2011. Energy content increased significantly early in the season, and remained similar between August and November while lignin concentrations increased. Both parameters, however, were relatively unaffected by the 2012 drought. It was concluded that switchgrass could be harvested as early as late August (earlier than the current recommended period of after 1 November or killing frost) depending on the requirements of the conversion method. More research is needed to determine whether early or delayed harvests have a greater economic impact on overall fuel yields in drought or normal years.

Plasticity of Sorghum Stem Biomass Accumulation in Response to Water Deficit: A Multiscale Analysis from Internode Tissue to Plant Level

Sorghum is increasingly used as a biomass crop worldwide. Its genetic diversity provides a large range of stem biochemical composition suitable for various end-uses as bioenergy or forage. Its drought tolerance enables it to reasonably sustain biomass production under water limited conditions. However, drought effect on the accumulation of sorghum stem biomass remains poorly understood which limits progress in crop improvement and management. This study aimed at identifying the morphological, biochemical and histological traits underlying biomass accumulation in the sorghum stem and its plasticity in response to water deficit. Two hybrids (G1, G4) different in stem biochemical composition (G4, more lignified, less sweet) were evaluated during 2 years in the field in Southern France, under two water treatments differentiated during stem elongation (irrigated; 1 month dry-down until an average soil water deficit of -8.85 bars). Plant phenology was observed weekly. At the end of the water treatment and at final harvest, plant height, stem and leaf dry-weight and the size, biochemical composition and tissue histology of internodes at 2–4 positions along the stem were measured. Stem biomass accumulation was significantly reduced by drought (in average 42% at the end of the dry-down). This was due to the reduction of the length, but not diameter, of the internodes expanded during water deficit. These internodes had more soluble sugar but lower lignin and cellulose contents. This was associated with a decrease of the areal proportion of lignified cell wall in internode outer zone whereas the areal proportion of this zone was not affected. All internodes for a given genotype and environment followed a common histochemical dynamics. Hemicellulose content and the areal proportion of inner vs. outer internode tissues were set up early during internode growth and were not drought responsive. G4 exhibited a higher drought sensitivity than G1 for plant height only. At final harvest, the stem dry weight was only 18% lower in water deficit (re-watered) compared to well-watered treatment and internodes growing during re-watering were similar to those on the well-watered plants. These results are being valorized to refine the phenotyping of sorghum diversity panels and breeding populations.

Wood Properties of Three Fruit Tree Species Planted in Central Kalimantan, Indonesia

The objective of this study was to evaluate the properties for wood utilization of fruit trees planted in Central Kalimantan, Indonesia. A total of 9 jambu bol (Syzygium malaccense), rambutan (Nephelium lappaceum), and durian (Durio zibethinus) trees were randomly selected from the plot (20 by 30 m) and measured for stem diameter, tree height, stress-wave velocity (SWV), and Pilodyn penetration of the trees. Mean values of stem diameter were 11.8, 15.9, and 29.3 cm for S. malaccense, N. lappaceum, and D. zibethinus, respectively. Mean values of stress-wave velocity were 3.16, 3.95, and 3.63 km/s for S. malaccense, N. lappaceum, and D. zibethinus, respectively. Core samples (5 mm in diameter) were collected from these trees to investigate the wood properties [basic density (BD) and compressive strength parallel to grain (CS)], anatomical characteristics [vessel diameter (VD), cell wall thickness (CWT) in wood fiber, and cell length (CL) of wood fiber and vessel element], and amounts of chemical components. In VD, CWT in wood fiber, and CL in wood fiber and vessel element, almost the same radial variation patterns were found in the three species. Relatively higher values in SWV, BD, and CS were found in N. lappaceum, suggesting that its wood can be used for construction lumber. On the other hand, S. malaccense and D. zibethinus had relatively thicker CWT in wood fiber, longer CL in wood fiber, and lower Klason lignin content. It is considered that the wood of these two species may be suitable for pulpwood.

A Comparative Biomass Compositional Analysis of Five Algal Species from the Paddy Fields of Burdwan District, West Bengal, India, to Determine Their Suitability for Handmade Paper Pulp Formulation

The need for research into the use of alternative raw materials for the production of paper results from the anticipated shortages in the supply of raw-materials to the wood-based paper-industry. Although Burdwan town is vested with different types of algae, literally no work has been done for valorization of such biomass. Start of such bioprocess involves optimization of resource-utilization that is the main topic in this paper. Burdwan town was surveyed for collection of algae that were identified by morphologic characteristics under the microscope. Cellulose, hemicelluloses, lignin, ash-content, water-retention-value, total carbohydrate and starch concentration of these algae were determined for assessing their feasibility in handmade-paper production. Element content in these algae was determined from energy-dispersive-X-ray-spectroscopy. Breaking-length and tensile-strength were the two parameters tested to assess hand-made-paper quality obtained from pulp extracted from the collected algae species. Data obtained were statistically evaluated with one-way analysis-of-variance followed by Tukey’s HSD (honest-significant-difference) test. Paper made from pure algae pulp was also tested for inter-fiber bonding with scanning-electron-microscopic-imaging. All experiments were repeated with Eucalyptus sp. pulp (wood) as control to assess the suitability of algal pulp as an alternative to the conventional wood pulp. Five algal species: Pithophora sp., Lyngbya sp., Hydrodiction sp., Cladophora sp. and Rhizoclonium sp. were collected. Although here were no statistically-significant differences (p = 0.8137) in biomass-compositional values from the studied algae species and Eucalyptus sp. pulp, paper quality parameters (Breaking-length and tensile-strength) varied significantly (p < 0.1, p < 0.5) among them. Hydrodiction sp., besides Rhizoclonium sp. and Cladophora sp. were established as the most suitable candidates for paper-pulp formulation in terms of high cellulose, hemicelluloses contents and low lignin and silica contents. Paper from pure Hydrodiction sp. pulp was found to have statistically significant (P < 0.05) improved breaking-length and tensile-strength properties compared to that obtained from Lyngbya sp. Paper-pulp characters varied insignificantly among Hydrodiction sp., Rhizoclonium sp. and Cladophora sp. versus Eucalyptus sp. (wood pulp) whereas statistically significant differences were noticed in paper pulp quality of Pithophora sp. (p < 0.05) and Lyngbya sp. (p < 0.01) with Eucalyptus sp. respectively. Thus, this paper enlightens (through statistical comparison), the properties of different algae, leading out Hydrodiction sp., Rhizoclonium sp. and Cladophora sp. to be the most appropriate as start up material (resources) for paper-pulp formulation, in comparison to conventional wood pulp (Eucalyptus sp.).

Impact of Dilute Sulfuric Acid, Ammonium Hydroxide, and Ionic Liquid Pretreatments on the Fractionation and Characterization of Engineered Switchgrass

Improving plant characteristics for better environmental resilience and more cost-effective transformation to fuels and chemicals is one of the focus areas in biomass feedstock development. In order to bridge lignin engineering and conversion technologies, this study aimed to fractionate and characterize lignin streams from wild-type and engineered switchgrass using three different pretreatment methods, i.e., dilute sulfuric acid (DA), ammonium hydroxide (AH), and aqueous ionic liquid (IL). Results demonstrate the low lignin content and high S/G ratio switchgrass mutant (4CL) was more susceptible to pretreatment and subsequently more digestible by enzymes as compared to wild-type switchgrass and AtLOV1 mutant. In addition, when compared to DA and AH pretreatment, aqueous IL (cholinium lysinate) was demostrated to be an efficient lignin solvent, as indicated by the high (> 80%) lignin solubility and reduced lignin molecular weight. FTIR and differential scanning calorimetry measurements suggest that pretreatment chemistry greatly influenced the structural and compositional changes and thermal properties of the pretreated switchgrass and recovered lignin-rich streams. The comparative data obtained from this work deepen our understanding of how lignin modification impacts the fractionation and properties of biomass feedstocks.

Growth performance and lignin content of Acacia mangium Willd. and Acacia auriculiformis A. Cunn. ex Benth. under normal and stressed conditions

Acacia mangium Willdenow and Acacia auriculiformis A. Cunningham ex Bentham are fast-growing species with wide environmental adaptability. Fast-growing species which thrive in otherwise non-arable problematic soil and which hold the added advantage of improving the condition of the soil, can be used to increase production area, and, thus, are highly desired. We investigated the growth performance and lignin content under normal and stressed conditions for these Acacia mangium Willd. and Acacia auriculiformis A. Cunn. ex Benth. Normal growing conditions was represented by fertile soil, high water-holding capacity due to low soil drainage, high organic matter, low soil temperature, overall consistent rainfall and relatively milder temperatures, whilst stressed conditions were achieved with a sandy soil with low fertility, low water-holding capacity due to high drainage and low organic matter, and high soil temperature accompanied by inconsistent monthly temperature and rainfall. Growth performance under normal conditions was significantly better compared to the stressed conditions. A. mangium performed better than A. auriculiformis under the normal conditions. However A. auriculiformis performed better under stressed conditions due to better adaptability. The lignin content under normal conditions fluctuated from one DBH class to another. As for the stress conditions, A. mangium exhibited incremental increases in lignin content with increasing biomass. In contrast, lignin content in A. auriculiformis decreased with increasing biomass. The differences in performance may be attributable to both the micro- and macro-environments and adaptive differences between the two species. For growth under normal conditions, A. mangium appears to be the superior choice, whereas for problematic soils, A. auriculiformis can be recommended. However, for the selection of superior plants with a combination of desired growth rates and lower lignin content the breeding of interspecific hybrids would be a desirable approach.

Trophic ecology of green turtleChelonia mydasjuveniles in the Colombian Pacific

Gorgona National Park (GNP) protects the only known feeding aggregation of juvenile green turtlesChelonia mydason the Pacific coast of Colombia. This study was undertaken to compare the diet of the two knownC. mydasmorphotypes (black and yellow), and to determine availability, selectivity, and quality of food resources at GNP. Oesophageal lavages and isotopic analysis of epidermal tissue were performed on turtles captured between February and December 2012. Food quantity was estimated by determining per cent cover in quadrats randomly placed on the reefs. Food quality of algae species was estimated by proximate analysis. Food selection was estimated using Ivlev's electivity index, and the trophic level of sea turtles at GNP was calculated. A total of 30 black (mean = 63.9 cm SCL) and 47 yellow (mean = 54.3 cm SCL) morphotype turtles were lavaged. Eight invertebrate and nine algae food items were identified in oesophageal contents. The most frequently found and abundant items in lavages were terrestrial plants, plastic fibres, invertebrates and algae. A total of 27 items, including 15 algae species, were identified on the reefs, of whichCladophorasp. was selected by black turtles, andHypnea pannosaandDictyotasp. were selected by both morphotypes; the latter species had the highest protein and lipid content, and low lignin content. A trophic level of 3.5 for black and 3.4 for yellow turtles was calculated. No significant difference in diet between the two morphotypes could be determined through lavage or isotopic analysis.

Laser-Induced Graphene Formation on Wood.

Wood as a renewable naturally occurring resource has been the focus of much research and commercial interests in applications ranging from building construction to chemicals production. Here, a facile approach is reported to transform wood into hierarchical porous graphene using CO2 laser scribing. Studies reveal that the crosslinked lignocellulose structure inherent in wood with higher lignin content is more favorable for the generation of high-quality graphene than wood with lower lignin content. Because of its high electrical conductivity (≈10 Ω per square), graphene patterned on wood surfaces can be readily fabricated into various high-performance devices, such as hydrogen evolution and oxygen evolution electrodes for overall water splitting with high reaction rates at low overpotentials, and supercapacitors for energy storage with high capacitance. The versatility of this technique in formation of multifunctional wood hybrids can inspire both research and industrial interest in the development of wood-derived graphene materials and their nanodevices.