Two-step hydrolysis of Japanese beech as treated by semi-flow hot-compressed water

A two-step hydrolysis of Japanese beech (Fagus crenata) was conducted by semi-flow treatment with hot-compressed water. The first treatment stage was conducted at 230°C/10 MPa for 15 min and the second at 270°C/10 MPa for 15 min. Hemicellulose and lignin were found to be hydrolyzed in the first stage, while crystalline cellulose was hydrolyzed in the second stage. The treatment solubilized 95.6% of the Japanese beech wood flour into water with 4.4% remaining as water-insoluble residue, which was composed mainly of lignin. Hydrolysis products from the first stage were xylose and xylo-oligosaccharides, glucuronic acid and acetic acid from O-acetyl-4-O-methylglucuronoxylan, and hydrolyzed monomeric guaiacyl and syringyl units and their dimeric condensed-type units from lignin. Products from the second hydrolysis stage were glucose and cello-oligosaccharides from cellulose. The dehydrated products levoglucosan, 5-hydroxymethylfurfural (5-HMF), and furfural, as well as fragmented products glycolaldehyde, methylglyoxal, and erythrose, were recovered in the first stage from hemicellulose, and to a greater extent in the second stage from cellulose. Furthermore, organic acids such as glycolic, formic, acetic, and lactic acids were recovered in both stages. Based on these lines of evidence, decomposition pathways of O-acetyl-4-O-methylglucuronoxylan and cellulose are independently proposed.     

Characterization of lignin-derived products from Japanese beech wood as treated by two-step semi-flow hot-compressed water

Japanese beech (Fagus crenata) wood was treated by two-step semi-flow hot-compressed water (the first stage: 230 °C/10 MPa/15 min, the second stage: 270 °C/10 MPa/15 min), and produced lignin-derived products in the hot-compressed water-soluble portions at the first and second stages, and the final residue of the second stage was characterized with alkaline nitrobenzene oxidation method and gel permeation chromatographic analysis. As a result, the lignin-derived products at the first stage, where hemicellulose was also decomposed, consisted of lignin-based monomers and dimers and oligomers/polymers in the water-soluble portion. A large part of the oligomers/polymers was, however, recovered as the precipitate during 12 h setting after hot-compressed water treatment. By the analysis of nitrobenzene oxidation products, there were relatively higher contents of ether-type lignin in the precipitate at the first stage than in original beech wood. Since the ether linkages of lignin are more preferentially cleaved by this hot-compressed water, lignin-based polymeric fractions were flowed out from the porous cell walls from which hemicellulose was removed. On the other hand, at the second stage condensed-type lignin remained in the precipitate and residue. Based on these results, decomposition behavior of lignin in Japanese beech wood as treated by the two-step semi-flow hot-compressed water was discussed regarding the topochemistry of lignin structure.     

Hydrothermal decomposition of various crystalline celluloses as treated by semi-flow hot-compressed water

Various types of crystalline celluloses I, II, III_I, III_II, IV_I and IV_II that have been adjusted for their degree of polymerization were treated by semi-flow hot-compressed water (HCW) at 230–270 °C/10 MPa/15 min to study their hydrothermal decomposition. The treatments resulted in either partial or complete decomposition of the celluloses and the decomposed products were primarily recovered as hydrolyzed, dehydrated and fragmented ones as well as organic acids in the water-soluble (WS) portions. Their results of hydrothermal decomposition and its kinetics revealed that the celluloses decomposition is dependent on the types of crystalline celluloses as well as temperature of the HCW treatment. The outcome from the WS portions at 270 °C/10 MPa/15 min showed that the degree of difficulty for decomposition is lower in group II (cell II, cell III_II, cell IV_II) than group I (cell I, cell III_I, cell IV_I), indicating that group II is less resistant to decomposition by HCW treatment. Therefore, the decomposition behaviors of the cellulose are due to the inherent differences in the crystalline structures.     

Two-step hydrolysis of Japanese cedar as treated by semi-flow hot-compressed water

Two-step hydrolysis of Japanese cedar (Cryptomeria japonica) was studied as treated by semi-flow hot-compressed water at 230°C/10 MPa for 15 min and 280°C/10 MPa for 30 min as the first and second stages, respectively. At the first stage, hemicelluloses and para-crystalline cellulose, whose crystalline structure is somewhat disordered, were found to be selectively hydrolyzed, as well as lignin decomposition, whereas crystalline cellulose occurred at the second stage. In all, 87.76% of Japanese cedar could be liquefied by hot-compressed water and was primarily recovered as various hydrolyzed products, dehydrated, fragmented, and isomerized compounds as well as organic acids in the water-soluble portion. The remainder, 12.24%, could not be hydrolyzed and remained as the water-insoluble residue composed entirely of lignin. Based on the distribution of various products from hemicelluloses in Japanese cedar, their decomposition pathways were proposed as independent.     

Characterization of lignin-derived products from various lignocellulosics as treated by semi-flow hot-compressed water

To elucidate the decomposition behaviors of lignin from different taxonomic groups, five different lignocellulosics were treated with hot-compressed water (230 °C/10 MPa/15 min) to fractionate lignins into water-soluble portions, precipitates, and insoluble residues. The lignin-derived products in each fraction were characterized and compared. The delignification of monocotyledons [nipa palm (Nypa fruticans) frond, rice (Oryza sativa) straw, and corn (Zea mays) cob] was more extensive than that achieved for Japanese cedar (Cryptomeria japonica, gymnosperm) and Japanese beech (Fagus crenata, dicotyledon angiosperm). The water-soluble portions contained lignin monomers like coniferyl alcohol and phenolic acids, while the precipitates contained higher molecular weight lignin with high content of ether-type linkages. Lignin in the insoluble residues was rich in condensed-type structures. In all five lignocellulosics, ether-type linkages were preferentially cleaved, while condensed-type lignin showed resistance to hot-compressed water. In the monocotyledons, lignin–carbohydrate complexes were cleaved and gave lignins that had higher molecular weights than those eluted from the woods. These differences would facilitate the delignification in monocotyledons. Such information provides useful information for efficient utilization of various lignocellulosics.     

Reactivity of lignin in supercritical methanol studied with various lignin model compounds

Behavior of lignin in supercritical methanol (250–270°C, 24–27 MPa) was studied by using lignin model compounds at the tin bath temperature of 270°C with a batch-type reaction vessel. Guaiacol and veratrole were selected as a guaiacyl type of aromatic ring in lignin, while 2,6-dimethoxyphenol and 1,2,3-trimethoxybenzene as a syringyl one. In addition, biphenyl and β-O-4 types of dimeric lignin model compounds were, respectively, studied as condensed and ether linkages between C₆-C₃ phenyl propane units. As a result, both guaiacyl and syringyl types of aromatic rings were very stable, and the biphenyl type was comparatively stable under supercritical conditions of methanol. However, β-ether linkage in the phenolic β-O-4 model compound was cleaved rapidly into guaiacol and coniferyl alcohol, which was further converted to its γ-methyl ether. Non-phenolic β-O-4 model compound was, on the other hand, converted initially into its α-methyl ether and degraded further to produce guaiacol. These lines of evidence imply that in lignin macromolecules, the new phenolic residues are continuously formed and depolymerized repeatedly in supercritical methanol into the lower molecular products, mainly by the cleavage of the dominant β-ether structure in lignin.     

Canopy conductance and stand transpiration of <Emphasis Type="Italic">Populus simonii Carr</Emphasis> in response to soil and atmospheric water deficits in farmland shelterbelt,Northwest China

Populus simonii Carr trees are the most abundant species in Xinjiang farmland shelterbelt. They played an important role in protecting farmland ecosystem. Their stand transpiration rates and canopy conductances ranged from 0.14 to 1.02 cm d^?1 and from 1.19*10^?3 to 8.99*10^?5 m s^?1, respectively, during the 2014 growing season. Transpiration rate was showed quadratic polynomial regression with vapor pressure deficit (VPD) and air temperature (T), and exponential relationship with solar radiation (R_n). Furthermore, transpiration peaked at VPD, T, and Rn were 2.1 kPa, 23 °C, and 200 W m^?2, respectively. Canopy conductance increased exponentially with the increasing R_n, whereas decreased logarithmically with the increasing VPD. Besides, transpiration increased with the increasing T and VPD ,and decreased sharply with the increasing soil water deficit. Finally, canopy conductance increased with the decreasing atmospheric water deficit. These results are not only providing the basis for more detailed analyses of water physiology and growth of Populus simonii Carr trees for the later application of a climate-driven process model, but also might have implications for farmland shelterbelt management.     

The impact of climate change on the growth of tropical agroforestry tree seedlings

Several studies have been conducted on the response of crops to greater concentrations of atmospheric CO₂ (CO₂ fertilization) as a result of climate change, but only few studies have evaluated this effect on multipurpose agroforestry tree species in tropical environments. The objectives of this study were to quantify differences in growth parameters and in leaf carbon (C) and nitrogen (N) concentrations of Cedrela odorata L. and Gliricidia sepium (Jacq.) Walp. seedlings under current ambient temperature (32°C daytime, 22°C night time) and CO₂ (360 ppm) (AMB); CO₂ fertilization (800 ppm, 32°C daytime, 22°C night time) (_fCO₂); elevated ambient temperature (360 ppm, 34°C daytime, 25°C night time) (TEMP); and a combination of elevated temperature (32°C daytime, 22°C night time) and CO₂ fertilization (800 ppm) (TEMPx_fCO₂). Results showed significant differences (P < 0.05) in seedling growth parameters (seedling height, number of stem leaves, leaf area ratio, shoot and root biomass, and shoot/root ratio) between treatments for both tree species. The greatest increases in growth parameters occurred in the TEMP and TEMPx_fCO₂ treatments compared to the AMB treatment for both tree species. However, growth parameters were significantly lower (P < 0.05) in the _fCO₂ treatment compared to that of the AMB treatment. Leaf N concentration was 1.1 to 2.1 times lower (P < 0.05) in all treatments when compared to current ambient conditions (AMB) in both tree species, but no significant changes in leaf C concentrations were observed. Results from our study suggested that _fCO₂ had the greatest negative impact on tree growth parameters, and leaf N concentrations were affected negatively in all treatments compared to current ambient conditions. It is expected that such changes in growth parameters and plant N content may impact the long-term cycling of nutrients in agroforestry systems.     

浸泡和冷预处理对喜马拉雅长叶松不同种源种子萌发的作用

对喜马拉雅长叶松种子进行24小时GA3和H2O2浸泡预处理和15d的2-3℃低温预处理后,研究了在20℃,25℃和30℃萌发条件下,21个不同种源的喜马拉雅长叶松种子的萌发情况。结果表明,H2O2（1%v/v）和GA3（10mg/L）浸泡预处理,种子萌发率分别是82.39%和78.19%,而未经预处理的种子平均萌发率为70.79%。GA3和H2O2浸泡预处理分别使种子萌发时间缩短了8d和10d。在超过21天的20℃萌发条件下,湿冷处理提高了种子萌发率和缩短了萌发时间 而在25℃和30℃萌发条件下,总的萌发率未受到影响。喜马拉雅长叶松种子因缺少休眠而表现出很好的萌发,但是因为越来越多的造林项目需要大量的种子,播种预处理有利于提高种子萌发率和萌发速率,有助于满足种子需求。     

Optimization study for preparation of activated carbon from Acacia mangium wood using phosphoric acid

A study on the preparation of activated carbon from Acacia mangium wood was conducted, and the operating factors, such as activating agent concentration, activation temperature and activation time, were optimized using response surface methodology. In order to determine the effects of the operating factors namely H₃PO₄ concentration (6.48–48.5 %), activation temperature (364–1,036 °C) and activation time (19–146 min) on the characteristics of activated carbon, a three-level rotatable central composite design was used. The second-order mathematical model was proposed by regression analysis of the experimental data gathered from 20 batch runs. The optimum H₃PO₄ concentration, activation temperature and activation time were found to be 40 %, 900 °C and 45 min, respectively. At optimum conditions of the operating factors, the percent yield and surface area were 20.3 % and 1,767 m²/g, respectively. The activated carbon was found to be largely composed of mesopores. About 95 % of the total surface area was attributed to mesopores.     

Species richness estimation from probabilities of observing new species

A new species richness estimator applicable to probability sampling with fixed-area (a) plots in a finite-area (A) population is presented and tested in simulated sampling from three stem-mapped forest compartments, and from six large collections of forest inventory data. The estimator of richness is the average number of species per plot times the sum—over the N = A/n plots in a population—of the probability (p _m ) of observing a new species in the mth plot (m = 1,…, N). A Cauchy distribution function is used to capture trends in p _m . The parameters of the Cauchy distribution were estimated by optimizing a weighted maximum likelihood function. In comparison to five presumed best alternative estimators, the new estimator was ‘average’ with respect to bias, but best in terms of average root mean squared error. Taking the average of the estimates of richness produced by the five alternate and the new estimator would, generally, keep bias below 15 %. With relatively large sample sizes, the bias is moderately small (<10 %).     

Earthworm population and microbial activity temporal dynamics in a Caspian Hyrcanian mixed forest

Few studies have analyzed how tree species within a mixed natural forest affect the dynamics of soil chemical properties and soil biological activity. This study examines seasonal changes in earthworm populations and microbial respiration under several forest species (Carpinus betulus, Ulmus minor, Pterocarya fraxinifolia, Alnus glutinosa, Populus caspica and Quercus castaneifolia) in a temperate mixed forest situated in northern Iran. Soil samplings were taken under six individual tree species (n = 5) in April, June, August and October (a total of 30 trees each month) to examine seasonal variability in soil chemical properties and soil biological activity. Earthworm density/biomass varied seasonally but not significantly between tree species. Maximum values were found in spring (10.04 m^?2/16.06 mg m^?2) and autumn (9.7 m^?2/16.98 mg m^?2) and minimum in the summer (0.43 m^?2/1.26 mg m^?2). Soil microbial respiration did not differ between tree species and showed similar temporal trends in all soils under different tree species. In contrast to earthworm activity, maximum microbial activity was measured in summer (0.44 mg CO₂–C g soil^?1 day^?1) and minimum in winter (0.24 mg CO₂–C g soil^?1 day^?1). This study shows that although tree species affected soil chemical properties (pH, organic C, total N content of mineral soils), earthworm density/biomass and microbial respiration are not affected by tree species but are controlled by tree activity and climate with strong seasonal dynamics in this temperate forest.     

Dosage rate, temperature, and food source provisioning affect susceptibility of Tribolium castaneum and Tribolium confusum to chlorfenapyr

A series of experiments were conducted to evaluate residual efficacy of the insecticidal pyrrolle chlorfenapyr (Phantom^®) on treated concrete for control of Tribolium castaneum (Herbst), assess development of progeny from exposed parental adults, and to determine if starvation before exposure with or without a flour food source increased susceptibility of adult T. castaneum and adult Tribolium confusum Jacqueline du Val to chlorfenapyr. No adults survived exposure on concrete treated with chlorfenapyr at the maximum label rate of 1.1 g active ingredient (AI)/m², and no progeny were produced in bioassays conducted at 0–8 weeks posttreatment. In the second test, application rates were reduced, and bioassays were conducted at 27 and 32 °C. Adult survival and progeny production decreased as the application rate increased from 28 to 225 mg AI/m², and survival and progeny production were generally lower at 32 °C than at 27 °C, but at higher rates survival was <1 %, and no progeny were produced. In the final test, adult T. castaneum and adult T. confusum were starved for 1–7 days and then exposed either with or without flour on concrete treated with 3.9 and 27.5 mg AI chlorfenapyr/m². Mortality generally increased with starvation time, the presence of a food source led to decreased mortality at both application rates, and T. confusum was the more susceptible of the two species. Results show that chlorfenapyr could effectively control both species, but precise dosage levels need to be determined. Also, the presence of a food source greatly compromises adult control.     

Ingol diterpene ester from the latex of Euphorbia lactea

The stereochemistry of the ingol diterpene 3,12-di-O-acetyl-8-O-tigloyl-ingol (1), isolated from the latex of Euphorbia lactea, was determined by one- and two-dimensional NMR analysis.     

Water relations and photosynthesis in three families of radiata pine seedlings known to differ in their response to weed control

Needle water potential (Ψ_n), stomatal resistance (r_s) and net photosynthesis (P_N) were measured in potted radiata pine seedlings from three families (A, B, and C) during a soil drying and rewritting event. Measurements were made in a controlled environment of 25°C, 14-h days and 18°C, 10-h nights; vapour pressure deficit of 16 mbar; photon flux of 400 μE m^?2 s_?1; and wind speed of 1 m s^?1.Stomatal resistance increased at a greater rate in family A than in family B than in family C as Ψ_n decreased during the drying phase: at ?25 bar Ψ_n, r_s values were 77, 60, and 46 s cm^?1 for families A, B and C respectively. Net photosynthesis (P_N) was greatest in family A at high Ψ_n but least at low Ψ_n: at Ψ_n ?9 bar, P_N was 9.4 6.4, and 8.2 ng cm^?2 s^?1 for families A, B, and C respectively, but for ?25 bar Ψ_n corresponding P_N values were 0.4, 1.1, and 0.9.Consequently family A had a greater proportional decrease in both P_N and water use efficiency from high Ψ_n to low Ψ_n. This may help explain in part observed field behaviour (P.P. Cotterill, unpublished) where family A produces well relative to other families when weeds are controlled (high Ψ_n condition) but produces less well relative to other families when weeds are not controlled (low Ψ_n condition).Recovery of Ψ_n after rewatering preceded that of r_s and P_N, and recovery of P_n was typically biphasic with 70% of recovery coinciding with recovery in Ψ_n and the remaining 30% more closely coinciding with recovery in r_s. Recovery was slower in family A than the other two families.     

Simultaneous drying and densification of silver birch (Betula pendula L.) veneers: analysis of morphology,thickness swelling,and density profile

In this study, birch (Betula pendula L.) veneers were simultaneously densified and dried using a contact drying method at pressures of 1.5 and 3 MPa at 130 °C and compared with veneer dried in a laboratory-scale convective type dryer. Compression rate, thickness swelling, and the density profiles of the veneers were investigated. Furthermore, the microstructure of densified veneers was studied by scanning electron microscopy (SEM). A maximum veneer compression rate of 9 % was achieved at a pressure of 3 MPa. Under these conditions, the veneers were, on average, densified from 504 to 574 kg m^?3 (approximately 14 %). After water soaking, full set-recovery—recovery to the initial thickness—occurred. However, the swelling rate was lower for the densified veneer. Density profiles measurements showed that densification occurs throughout the veneers. The SEM images showed that the surface of the densified veneers were smoother, whilst no cracks were detected due to densification. Densification seemed to occur in vessels. Typically, rays were bent when there was a vessel nearby.     

Effects of warming basal ends of Carolina poplar (Populus × canadensis Moench.) softwood cuttings at controlled low-air-temperature on their root growth and leaf damage after planting

We investigated the effects of warming the basal ends of Carolina poplar (Populus × canadensis Moench.) softwood cuttings at controlled low-air-temperature on their root growth and leaf damage after planting. The warming treatment was applied to the cuttings by soaking 10 mm beyond the cut end in warmed water maintained at 30 °C in a cold chamber maintained at an air temperature of 10 °C and a photosynthetic photon flux density (PPFD) of 10 μmol m^?2 s^?1 (near the light compensation point at 10 °C) until rooting was observed. The warmed cuttings were then grown in a growth chamber at an air temperature of 30 °C, relative humidity 85–90 %, and a PPFD of 100 μmol m^?2 s^?1. Control cuttings were grown in the growth chamber throughout the experiment. Rooting occurred simultaneously for both warmed and control cuttings, irrespective of air temperature. Root development was greater and leaf damage, evaluated on the basis of extent of necrosis, was less for warmed cuttings than for control cuttings. The reduction of leaf damage for warmed cuttings probably resulted from reduced post-planting water stress and leaf senescence, because of improved root development as a result of the pre-planting warming treatment. This technique could improve the propagation of cuttings of woody plants, because it would ensure that the cuttings are ready to develop roots with minimum loss of carbohydrates, irrespective of weather conditions.     

Surface modification of birch veneer by peroxide bleaching

This study examined effects of surface modification with hydrogen peroxide (H₂O₂) on adhesive bond performance in birch veneer bonded with phenol–formaldehyde resin. The veneer was treated with 5% of H₂O₂ at 80 °C in the presence of alkali with the objective of improving adhesive bond performance and reducing the resin demand. The effects of the surface modification were determined by surface color measured with a spectrophotometer, bond performance tests with ABES (automated bonding evaluation system) and surface hydrophobicity with sessile contact angle measurements. Results demonstrated that veneer surface became significantly whiter, which also increased in lightness and decreased in redness and yellowness. ABES test revealed that a remarkable increase in bond performance in the treated veneer and the maximum bond strength with the treatment at 60 min, which was nearly twice as high as reference sample (5.42 → 9.94 N/mm²), was obtained. A notable decrease in contact angle measurements was also observed in the treated veneers (0° in 0.5 s). The surface modification of birch veneer with H₂O₂ + alkali demonstrated greater potential for the improvement of physical characteristics in veneer surface. Other aspects of H₂O₂ consumption during the treatment are also discussed.     

Optimal seed water content and storage temperature for preservation of Populus nigra L. germplasm

Context

Black poplar (Populus nigra L.) is an alluvial forest tree species whose genetic pool is decreasing in Europe. Poplar trees produce short-lived seeds that do not store well.

Aim

The feasibility of seed storage in conventional and cryogenic conditions after their desiccation from water content (WC) of 0.15 to 0.07 g H₂O g^?1 dry mass (g g^?1) was investigated.

Methods

Seed germinability was evaluated (seeds with a radicle and green cotyledons were counted) after storage of seeds for a period of 3 to 24 months at different temperatures: 20°, 10°, 3°, ?3°, ?10°, ?20° or ?196°C.

Results

Seeds desiccated to a 0.07 g g^?1 WC can be stored successfully at ?10 °C and ?20 °C for at least 2 years. A significant decrease in germination was observed only after 12 months of seed storage (WC 0.15 g g^?1) at temperatures above 0 °C. We demonstrated that both fresh (0.15 g g^?1 WC) and desiccated (0.07 g g^?1 WC) seeds can be preserved at ?196 °C for at least 2 years.

Conclusions

Seed storage temperature and time of storage were statistically significant factors affecting seed storability. The presented data provide a foundation for the successful gene banking of P. nigra seeds.     

Effect of nitrogen in combination with elevated temperatures on insects,microbes and organoleptic characteristics of stored currants

In the present study, the effect of nitrogen, applied as a controlled atmosphere treatment on the microbial and entomological loads, as well as on the organoleptic characteristics of stored dried currants (Corinthian raisins, Vitis vinifera L. var. Apyrena), was investigated. Trials were conducted under “real world” conditions, in the nitrogen chambers of a commercial facility, in which nitrogen was introduced by using an incorporated nitrogen generator. Prior to the initiation of the trial, chambers were filled with pallets carrying dried black currants. Subsequently, currants were artificially infected with all life stages of Tribolium confusum, eggs and larvae of Ephestia elutella and adults of Oryzaephilus surinamensis. Currants were exposed for 3 days in nitrogen (O₂ concentration <1 %) at two temperature levels, 25 and 38–43 °C. After treatment, insect mortality was recorded and currant samples were collected and forwarded for microbial analysis and determination of their organoleptic characteristics. When nitrogen was applied at 25 °C, high insect mortality levels were noted; however, in most cases there were a number of insects that survived the nitrogen treatment. In contrast, complete control was achieved at 38–43 °C for all insect species and life stages tested, with the exception of T. confusum larvae. Nitrogen application at 25 °C had no effect on total microbial and yeast and mould counts, while both were reduced at 38–43 °C. Sensory attributes of Corinthian currants remained acceptable after nitrogen fumigation, although taste, odour, aroma and overall acceptance were affected by the treatments. Total phenolic as well as 5-hydroxymethylfurfural content increased after nitrogen application at 38–43 °C, while the lower temperature applied had no effect. The results of the present study suggest that nitrogen-based controlled atmosphere at elevated temperature could be a valuable tool for ensuring clean, pest-free, hygienic standards in dried Corinthian currants.