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对贵州省21个种源的棕榈的表型与化学组分研究分析表明,贵州省棕榈种质资源变异丰富:不同种源棕榈树高、胸径、冠幅、花果柄距顶高、棕片面积、棕板重量、棕丝重量、脂蜡质含量、水溶物含量、果胶含量、半纤维素含量、木质素含量、纤维素含量和灰分含量均差异显著(P0.05);14个性状的变异系数在11.09%-58.39%之间,平均值为27.38%,以脂蜡质含量变异系数最大,果胶含量次之,以半纤维素含量变异系数最小,胸径变异系数次之;不同种源棕榈资源表型性状变异系数的平均值在15.58%-26.96%之间,以岑巩地区最大,水城地区较小;通过聚类分析可知贵州省棕榈的遗传分化与地理位置、年降雨量、年均温都有一定的关系。 相似文献
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木质纤维素类生物质是地球上最丰富的可再生资源。为提高木质纤维素类生物质的转化率,提升纤维素酶的水解效率和可发酵性糖产量,降低纤维素酶的使用量和生物质转化成本,对木质纤维素类生物质进行预处理十分必要;然而,木质素、纤维素和半纤维素之间的天然屏障限制了纤维素酶对纤维素组分的酶解。木质纤维素类生物质预处理主要有物理法、化学法、物理化学法和生物法,目前更多采用质量分数小于4%的稀酸法(如盐酸、硫酸和硝酸等,120～210℃)、高温热水法、蒸汽爆破法和液相水热法等,不同预处理方法对木质素或大部分半纤维素的溶解和去除有利于提高纤维素酶的可及性。木质素对纤维素酶解具有明显抑制作用,通过预处理降低木质素含量有利于提高纤维素酶解效率。木质纤维经稀酸或高温热水等预处理后,Klason木质素相对含量反而会增加。在木质纤维素类生物质预处理过程中,木质素液滴可能以假木质素形式沉积于纤维素表面,使其比天然木质素更加抑制纤维素酶解。本研究首先概述生物质预处理过程中木质素液滴和假木质素的形成过程,提出假木质素产生的可能机制,并对其组成和性质进行综述;然后阐述木质素液滴和假木质素对木质纤维酶解的影响;最后总结假木质素形成的调控策略。假木质素的形成过程属于非均相反应过程,受传质扩散(分子水平)和流动(宏观统计水平)的影响,可从介尺度行为研究假木质素的形成机制,同时建立相关模型和理论实现其科学的定量描述和定向调控,这不仅有利于木质纤维素类生物质炼制工艺的发展,也有利于促进跨学科科学规模的形成。 相似文献
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采用改良的CTAB法提取南林95杨的基因组DNA，经PCR扩增得到肉桂酰辅酶A还原酶CCR基因的第4个外显子部分序列，通过中间载体pUCCRNAi，构建含正反向干涉片段的pBll21表达载体，导入农杆菌LBA4404。利用叶盘法侵染南林95杨，获得3株转基因植株，经分子鉴定证实干涉片段已导入南林95杨。测定Klason木质素及综纤维素含量的结果显示：转基因植株Klason木质素含量与对照相比平均降低了9．86％，综纤维素含量与对照相比平均增加了3．17％，纤维长宽比明显增加，均表明转基因植株更有利于造纸。 相似文献
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《中南林业科技大学学报(自然科学版)》2017,(10)
以桉树4个无性系(GLU4、GLGU9、GLU16、DH32-29)为研究对象,采用方差分析、多重比较、相关分析等方法对其茎部解剖结构、含水量、木质素含量和纤维素含量等多个指标进行比较分析。结果表明:桉树4个无性系的茎部解剖结构基本相同,但结构参数之间存在显著差异。GLU16的第5节茎段表皮厚度和木质部厚度显著高于其他3个无性系,具有较强的保水和输导能力,更能适应苗木迅速的生长。DH32-29第5节茎段髓腔面积较其他3个桉树无性系大,可能其营养物质的贮藏能力更强。4个无性系含水量差异不大,纤维素、木质素含量差异相对显著。木质素含量和纤维素含量的比值与表皮厚度呈显著正相关,纤维素含量与木质部面积占茎横切面积的比值呈极显著负相关。GLU4木质素含量较高,可能其茎的机械强度与抗菌能力较强。GLU4纤维素含量较高,且木质素与纤维素比值较低,更适宜作为制浆原料和生物质能源。 相似文献
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木材表面非极性化原理的研究：Ⅲ.各化学组分在乙酰化过程中酯化？… 总被引：1，自引：0，他引：1
本文对“三北”一号杨和杉木中分离出的纤维素、半纤维素、综纤维一纱、木质素在酯化过程中酯化能力的差异和木材抽出物对木材酯化增重率的影响进行了研究。结果表明：纤维素的酯化增重率较低，杉木和“三北”一号杨的纤维素酯化增生率在反应２．５ｈ后仅为１．９％和３．２％；在乙酰化过程中半纤维素会大量水解；综纤维素的酯化增重率主要是由于半纤维系酯化的结果；木质素的酯化反应在１ｈ内就基本完成。且杉木木质素的酯化能力比 相似文献
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韧皮纤维生物—化学法制浆研究（Ⅰ）：构皮降解嗜碱细菌的筛选及其降解特性 总被引：2，自引：0，他引：2
从７４株供试菌中筛选出一株对构皮有较强降解能力的嗜碱细菌（Ｂａｃｉｌｕｓｓｐ．ＮＴ７）。该菌株降解构皮的适宜条件如下：培养基初始ｐＨ为１００,构皮与培养液的比例为１∶３０,３７℃,２００ｒ／ｍｉｎ,培养４天,外加碳源或氮源均抑制该菌株对构皮的降解。比较降解前后构皮各组分含量,发现果胶去除率高达９６３０％,半纤维素、木质素去除率分别为６３４７％和４３５１％,而纤维素仅损失１３６％,表明该菌株具有优先降解构皮非纤维组分的能力。 相似文献
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Modelling moisture-related mechanical properties of wood Part I: Properties of the wood constituents
I. D. Cave 《Wood Science and Technology》1978,12(1):75-86
Summary By starting with simple concepts of the molecular structure and building up through the various levels of organisation in the wood cell wall it is possible to construct a model that simultaneously predicts the variation with moisture content change of both the longitudinal Young's modulus and longitudinal shrinkage of wood. To do this it is first necessary to define the stiffness and swelling characteristics of the lignin, hemicellulose and cellulose constituents of the wood as moisture content changes. It is suggested here that it is the bound fraction of the sorbed water that is responsible for the changes in swelling stress as well as for change in stiffness in the lignin and hemicellulose. The magnitudes of the stiffness of each of the constituents appear to be quite closely circumscribed by experimental values for longitudinal Young's modulus and shrinkage of wood and it is apparent that the stiffness characteristics of the in situ constituents are compatible with available experimental evidence for extracted lignin and hemicellulose and for native cellulose. 相似文献
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为实现生物质的溶解,同时克服传统离子液体溶解生物质的缺点,制备了新型转极性离子化合物1,8-二氮杂二环十一碳-7-烯(DBU)/CH3OH/CO_2(DCC)的甲醇溶液,考察了不同温度、时间和溶液浓度对香樟木屑的溶解性能和再生效果,分析了溶解前后香樟木屑中纤维素、半纤维素和木质素的溶解率及结晶度的变化,并对溶解前后的木屑进行FT-IR、XRD和SEM表征,对溶解液中再生的物质进行FT-IR和UV分析。结果表明:较高温度(≥120℃)下,香樟木屑在DCC的甲醇溶液中的溶解率随温度升高和时间延长而有所增加;DCC甲醇溶液对半纤维素和木质素的溶解能力较强,对纤维素的溶解能力较弱;2.5 mol/L的DCC甲醇溶液在溶解温度180℃,溶解时间6 h时,木屑溶解率达到48.6%,半纤维素溶解率达62.4%,木质素溶解率为55.7%,纤维素溶解率为19.6%,溶解效果与传统离子液体相当。FT-IR、XRD和SEM分析表明,DCC甲醇溶液溶解木屑时,主要溶解木屑中无定形的半纤维素、木质素和少量非晶态的纤维素。FT-IR和UV分析表明溶解液中再生的物质是木质素,其质量分数在90%以上。DCC甲醇溶液重复使用3次时,每溶解一次其溶解能力下降2~3个百分点。 相似文献
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生物柴油原料树种文冠果的化学成分与综合利用研究进展 总被引：1，自引：0，他引：1
生物柴油原料树种文冠果的叶片、枝干、果皮、种皮、种仁中化学成分丰富多样,除了含有细胞壁组分木质素、纤维素、半纤维素、果胶质以及储藏物质蛋白质、糖类、脂肪外,还含有甾体、萜类、香豆素、黄酮类、有机酸以及蒽醌等多类次生代谢产物,具有在食用、药用、饲用、化工、能源等多个领域的开发利用潜力。在对该树种化学成分和综合利用方面的研究进展进行总结分析的基础上,提出了目前存在的问题和需要进一步研发的建议。 相似文献
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分别将木粉、纤维素和木质素在乙二醇中进行热化学液化。研究结果表明木粉中纤维素的非结晶区、木质素和半纤维素首先被液化,而纤维素的结晶区较慢被液化,到液化反应中期基本降解完全,液化产率高于97%。利用在线红外光谱仪跟踪检测了整个液化反应过程,结合GC-MS结果发现:乙二醇在反应过程中脱水生成了二甘醇和三甘醇。在液化反应中,纤维素的糖苷键断裂后生成葡萄糖苷结构,随后葡萄糖苷中的吡喃环也被打开,生成的活性中间体相互反应或与乙二醇反应生成了如3-(2-甲基-[1,3]-二氧戊环-2-基)-丙酸乙酯、乙酰丙酸丁酯等酯类;木质素的苯丙烷结构主要降解为苯酚、2,6-甲氧基苯酚等芳香族衍生物,因此木粉液化产物是聚醚/酯混合多元醇。 相似文献
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Dai Oka Kayoko Kobayashi Noriyuki Isobe Yu Ogawa Tomoya Yokoyama Satoshi Kimura Ung-Jin Kim Ken Tokuyasu Masahisa Wada 《Journal of Wood Science》2013,59(6):484-488
Pulverized samples of wood, cedar and eucalyptus were treated with 5 N NaOH solutions at 25–150 °C. Hemicellulose and lignin content in the samples decreased with increasing treatment temperatures, while the recovery of glucose was maintained at nearly 90 %. X-ray diffraction analysis showed that the content of the original cellulose I structure in the samples decreased with increasing temperature, and most of the cellulose in the sample treated at 150 °C was converted to cellulose II by mercerization. Enzymatic hydrolysis of the alkaline-treated samples was carried out at 37 °C using solutions comprising a mixture of cellulase and β-glucosidase. The samples treated at higher temperatures showed better enzymatic degradability. Treatment with an alkaline solution of lower concentration (1 N NaOH) at 150 °C was also used. Despite significant quantities of hemicellulose and lignin being removed, mercerization was not induced. The enzymatic degradability was much lower than that of the sample treated with a 5 N NaOH solution at 150 °C. Thus, treatment with concentrated alkaline solution at high temperature led to not only the removal of hemicellulose and lignin, but also to modification of the cellulose structure, which resulted in high efficiency of enzymatic saccharification of the wood samples. 相似文献
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The polymeric angle and concentration within the S2 layer of the softwood fiber cell wall are very critical for molecular and microscopic properties that influence strength, stiffness and acoustic velocity of wood at the macroscopic level. The main objective of this study was to elucidate the effect of cellulose, hemicellulose, lignin, microfibril angle and density on acoustic velocity and material mechanical properties of 14-year-old suppressed loblolly pine. Cellulose, hemicellulose and density are consistently the most important drivers of strength, stiffness and velocity. Cellulose and lignin are the highest and lowest contributor to velocity, respectively, with lignin acting as a sound wave dispersant, while cellulose is the most important conductor of sound wave at the molecular level, while hemicellulose acts as a special coupling agent between these components. The polymeric constituents are thus important drivers of sound wave propagation at the molecular level, while density played a subsequent role at the macroscale. 相似文献
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在材种鉴定的基础上,通过近红外光谱(NIRS)定性分析了建成约600 a的木造古建筑木构件的化学组分,结合木构件化学组分定量分析,与现代木材相比较,探讨了近红外光谱技术评价木构件老化的可行性。结果表明:近红外二阶导数特征性谱带反映了木材纤维素以及半纤维素和木质素的基团信息,而其差谱反映出木构件与对照样化学组分变化。这些光谱特征与传统的化学组分定量分析的结果非常一致:纤维素和半纤维素相对含量减少而木质素相对含量增加,与各种组分谱带差谱的增减相对应。此外,在5 882,5 587和5 464 cm-1等谱带处反映的纤维素结晶和半结晶区的光谱信息,差谱观察到木构件与现代材落叶松之间化学组分的不变或减少,其结果与X射线衍射(XRD)方法获得的木材结晶度分析结果相一致。通过NIRS定性分析木构件化学组分及结晶度变化,接近于现场检测方法,使用便携式NIRS,在古建筑木构件端头裸露部位获取光谱信息,能够实现现场对木材化学组分的无损定性评价。本实验结果也表明,除了常规的红外光谱(FT-IR)、XRD分析技术,NIRS技术对于木构件老化状况的评价是一种有潜力的无损检测方法。 相似文献
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Residual wood meal after extraction of milled wood lignin (WMEM) ofEucalyptus globulus was extracted with alkali and LiCl/N,N-Dimethylacetamide (DMAc). These agents dissolve mainly hemicellulose and cellulose, respectively. The extractability of WMEM in alkali solutions was influenced by the degree of swelling of the cellulose. Under good swelling conditions, considerable amounts of cellulose and lignin were extracted with the hemicellulose. Maximum extractability was about 60% of the WMEM under optimum conditions (3 M or 5 M LiOH or 3M NaOH solution). Some portion of cellulose was extracted with LiCl/DMAc at room temperature. Thus, lignin inE. globulus WMEM was divided into three fractions: hemicellulose-lignin fraction, cellulose-lignin fraction, and insoluble-lignin fraction.Part of this work was presented at the 49th annual meeting of the Japan Wood Research Society, Tokyo, April 1999; and at the 50th annual meeting of the Japan Wood Research Society, Kyoto, April 2000 相似文献
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木材白腐机理研究进展 总被引：14，自引：0，他引：14
白腐菌是木材的主要腐朽菌之一，白腐菌菌丝在细胞内形成多种降解酶主要是木素降解酶，次则是纤维素降解酶及半纤维素降解酶，以降解细胞壁物质中的木素、半纤维素及纤维素，作为木腐菌的营养。由于这些木材组成的降解，必然改变木材的化学及物理性质。近年来，在白腐菌的营养需求、降解酶传递途径，对木材主要组成酶降解机理及对材性的影响，产酶的分子遗传等领域的研究均取得一定进展，可望不久将来能利用生物工程改变白腐菌基因， 相似文献
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Human activities are increasing the concentrations of atmospheric carbon dioxide ([CO2]) and tropospheric ozone ([O3]), potentially leading to changes in the quantity and chemical quality of leaf litter inputs to forest soils. Because the quality and quantity of labile and recalcitrant carbon (C) compounds influence forest productivity through changes in soil organic matter content, characterizing changes in leaf litter in response to environmental change is critical to understanding the effects of global change on forests. We assessed the independent and combined effects of elevated [CO2] and elevated [O3] on foliar litter production and chemistry in aspen (Populus tremuloides Michx.) and birch-(Betula papyrifera Marsh.) aspen communities at the Aspen free-air CO2 enrichment (FACE) experiment in Rhinelander, WI. Litter was analyzed for concentrations of C, nitrogen (N), soluble sugars, lipids, lignin, cellulose, hemicellulose and C-based defensive compounds (soluble phenolics and condensed tannins). Concentrations of these chemical compounds in naturally senesced litter were similar in aspen and birch-aspen communities among treatments, except for N, the C:N ratio and lipids. Elevated [CO2] significantly increased C:N (+8.7%), lowered mean litter N concentration (-10.7%) but had no effect on the concentrations of soluble sugars, soluble phenolics and condensed tannins. Elevated [CO2] significantly increased litter biomass production (+33.3%), resulting in significant increases in fluxes of N, soluble sugars, soluble phenolics and condensed tannins to the soil. Elevated [O3] significantly increased litter concentrations of soluble sugars (+78.1%), soluble phenolics (+53.1%) and condensed tannins (+77.2%). There were no significant effects of elevated [CO2] or elevated [O3] on the concentrations of individual C structural carbohydrates (cellulose, hemicellulose and lignin). Elevated [CO2] significantly increased cellulose (+37.4%) input to soil, whereas elevated [O3] significantly reduced hemicellulose and lignin inputs to soil (-22.3 and -31.5%, respectively). The small changes in litter chemistry in response to elevated [CO2] and tropospheric [O3] that we observed, combined with changes in litter biomass production, could significantly alter the inputs of N, soluble sugars, condensed tannins, soluble phenolics, cellulose and lignin to forest soils in the future. 相似文献