The C mineralisation pattern during the early stage of decomposition of plant materials is largely determined by their content
of different carbohydrates. This study investigated whether detailed plant analysis could provide a better prediction of C
mineralisation during decomposition than proximate analysis [neutral detergent solution (NDF)/acid detergent solution (ADF)].
The detailed analysis included sugars, fructans, starch, pectin, cellulose, lignin and organic N. To determine whether differences
in decomposition rate were related to differences in hemicellulose composition, the analysis particularly emphasised the concentrations
of arabinose and xylose in hemicelluloses. Carbon dioxide evolution was monitored hourly in soil amended with ten different
plant materials. Principal component and regression analysis showed that C mineralisation during day 1 was closely related
to free sugars, fructans and soluble organic N components (R2 = 0.83). The sum of non-cellulose structural carbohydrates (intermediate NDF/ADF fraction) was not related to C mineralisation
between days 1 and 9. In contrast, a model including starch and protein in addition to the non-cellulose structural carbohydrates,
with the hemicelluloses replaced by arabinose and xylose, showed a strong relationship with evolved CO2 (R2 = 0.87). Carbon mineralisation between days 9 and 34 was better explained by xylan, cellulose and lignin (R2 = 0.72) than by lignocellulose in the ADF fraction. Our results indicated that proximate analyses were not sufficient to
explain differences in decomposition. To predict C mineralisation from the range of plant materials studied, we propose a
minimum set of analyses comprising total N, free sugars, starch, arabinose, xylan, cellulose and lignin. 相似文献
In Japan, ammoniacal copper quaternary wood preservatives type-1 (ACQ-1), which contains copper and benzalkonium chloride
as its active ingredients, is among the most widely used wood preservatives in the pressure treatment of wood. Benzalkonium
chloride (BAC) in commercial ACQ-1 products mainly comprises C12 and C14 homologues. In the present study, the leaching characteristics
of these BAC homologues were investigated using the heartwood and sapwood portions of Japanese cedar, Japanese larch, and
Sakhalin fir treated with ACQ-1 and 1% monoethanolamine (MEA) solution containing equimolar amounts of homologues. Distilled
water (DW) and artificial seawater (SW) were used as leaching media. Consequently, it was observed that the leaching rate
of the C12 homologue tended to be higher than that of the C14 homologue in DW. The leaching of C12 homologues was accelerated
by using SW, resulting in a significantly higher leaching rate than the C14 homologue using SW. It was thought that the difference
in the hydrophobicities based on alkyl chain lengths resulted in these phenomena. However, when the heartwood portion of Japanese
larch was treated with the homologues in MEA, the leaching rate of the C14 homologue was significantly higher than that of
the C12 homologue. 相似文献
Heat treatments change the chemical and physical properties of wood and dimensional stability and hygroscopicity are affected
as a result of modifications of wood cell components. This study evaluated the water absorption of wood specimens treated
with boron compounds followed by heat treatment. Sugi (Cryptomeria japonica D. Don) sapwood specimens treated with either boric acid (BA) or disodium octoborate tetrahydrate (DOT) solutions were heat-modified
at either 180° or 220°C for 2 or 4 h. Carbohydrate composition and water absorption of the specimens were then measured and
compared with those of untreated and unheated specimens. Wood carbohydrates were significantly degraded in the specimens after
heat treatment. The heat treatment evidently decreased the water absorption and the heat-modified specimens absorbed less
water than unheated specimens. The higher the treatment temperature and the longer the treatment time, the lower the amount
of absorbed water. The boron-treated and heat-modified specimens, however, showed increased water absorption due to the hygroscopic
properties of BA and DOT. 相似文献
Lack of quantitative observations of extent, frequency, and severity of large historical fires constrains awareness of departure of contemporary conditions from those that demonstrated resistance and resilience to frequent fire and recurring drought.
Objectives
Compare historical and contemporary fire and forest conditions for a dry forest landscape with few barriers to fire spread.
Methods
Quantify differences in (1) historical (1700–1918) and contemporary (1985–2015) fire extent, fire rotation, and stand-replacing fire and (2) historical (1914–1924) and contemporary (2012) forest structure and composition. Data include 85,750-ha tree-ring reconstruction of fire frequency and extent; >?375,000-ha timber inventory following >?78,900-ha fires in 1918; and remotely-sensed maps of contemporary fire effects and forest conditions.
Results
Historically, fires?>?20,000 ha occurred every 9.5 years; fire rotation was 14.9 years; seven fires?>?40,469 ha occurred during extreme drought (PDSI <?? 4.0); and stand-replacing fire occurred primarily in lodgepole (Pinus contorta var. murrayana). In contemporary fires, only 5% of the ecoregion burned in 30 years, and stand-replacing fire occurred primarily in ponderosa (Pinus ponderosa) and mixed-conifer. Historically, density of conifers?>?15 cm dbh exceeded 120 trees/ha on?<?5% of the area compared to 95% currently.
Conclusions
Frequent, large, low-severity fires historically maintained open-canopy ponderosa and mixed-conifer forests in which large fire- and drought-tolerant trees were prevalent. Stand-replacing patches in ponderosa and mixed-conifer were rare, even in fires >?40,469 ha (minimum size of contemporary “megafires”) during extreme drought. In this frequent-fire landscape, mixed-severity fire historically influenced lodgepole and adjacent forests. Lack of large, frequent, low-severity fires degrades contemporary forest ecosystems.
The cover image is based on Research Article Field evaluation of an unmanned aerial vehicle (UAV) sprayer: effect of spray volume on deposition and the control of pests and disease in wheat by Guobin Wang et al., DOI: 10.1002/ps.5321 . Illustration Credit: Guobin Wang, Yubin Lan, and Yuxing Han.
Lupinus albus seeds contain conglutin gamma (Cγ) protein, which exerts a hypoglycemic effect and positively modifies proteins involved in glucose homeostasis. Cγ could potentially be used to manage patients with impaired glucose metabolism, but there remains a need to evaluate its effects on hepatic glucose production. The present study aimed to analyze G6pc, Fbp1, and Pck1 gene expressions in two experimental animal models of impaired glucose metabolism. We also evaluated hepatic and renal tissue integrity following Cγ treatment. To generate an insulin resistance model, male Wistar rats were provided 30% sucrose solution ad libitum for 20 weeks. To generate a type 2 diabetes model (STZ), five-day-old rats were intraperitoneally injected with streptozotocin (150 mg/kg). Each animal model was randomized into three subgroups that received the following oral treatments daily for one week: 0.9% w/v NaCl (vehicle; IR-Ctrl and STZ-Ctrl); metformin 300 mg/kg (IR-Met and STZ-Met); and Cγ 150 mg/kg (IR-Cγ and STZ-Cγ). Biochemical parameters were assessed pre- and post-treatment using colorimetric or enzymatic methods. We also performed histological analysis of hepatic and renal tissue. G6pc, Fbp1, and Pck1 gene expressions were quantified using real-time PCR. No histological changes were observed in any group. Post-treatment G6pc gene expression was decreased in the IR-Cγ and STZ-Cγ groups. Post-treatment Fbp1 and Pck1 gene expressions were reduced in the IR-Cγ group but increased in STZ-Cγ animals. Overall, these findings suggest that Cγ is involved in reducing hepatic glucose production, mainly through G6pc inhibition in impaired glucose metabolism disorders. 相似文献
Cassava (Manihot esculenta Crantz) native starch was treated with pyroconversion and enzymatic hydrolysis to produce a pyrodextrin and an enzyme-resistant maltodextrin. Some nutritional characteristics were quantified for both compounds. Pyroconversion was done using a 160:1 (p/v) starch:HCl ratio, 90 °C temperature and 3 h reaction time. The resulting pyrodextrin contained 46.21% indigestible starch and 78.86% dietary fiber. Thermostable α-amylase (0.01%) was used to hydrolyze the pyrodextrin at 95 °C for 5 min. The resulting resistant maltodextrin contained 24.45% dextrose equivalents, 56.06% indigestible starch and 86.62% dietary fiber. Compared to the cassava native starch, the pyrodextrin exhibited 56% solubility at room temperature and the resistant maltodextrin 100%. The glycemic index value for the resistant maltodextrin was 59% in healthy persons. Its high indigestible starch and dietary fiber contents, as well as its complete solubility, make the resistant maltodextrin a promising ingredient for raising dietary fiber content in a wide range of foods, especially in drinks, dairy products, creams and soups. 相似文献
Red beetroot has been ranked among the 10 most potent antioxidant vegetables, although only extraction-based methods have been used to evaluate its total antioxidant capacity. Therefore, the present study aims at comparing the traditional extraction-based method with two more recent approaches (QUENCHER -QUick, Easy, New, CHEap and Reproducible- and GAR -global antioxidant response method), in order to establish their suitability in the case of beetroot. Our results indicate that the total antioxidant capacity of beetroot would be underestimated when using extraction-based procedures, since both QUENCHER and GAR methods resulted in a higher total antioxidant capacity. The effect of a thermal treatment on the total antioxidant capacity of beetroot varies among the methods evaluated and our findings suggest different compounds responsible for the total antioxidant capacity detected in each pre-processing method. Remarkably, the present study demonstrates that the traditional extraction-based method seems useful to screen for (changes in) the “bioavailable” antioxidant potential of the root. 相似文献