甲醛交联碱木质素-聚乙烯醇薄膜的透光性和透气性

为了提高工业碱木质素的利用价值,扩大碱木质素的应用范围,以工业碱木质素和聚乙烯醇为原料,以甲醛为交联剂,利用流延法制备了碱木质素-聚乙烯醇交联反应膜。通过单因素实验探索了碱木质素加入量、甲醛加入量、溶液pH值对碱木质素-聚乙烯醇(PVA,poly vinyl alcohol)反应膜透光性和透气性的影响。采用紫外可见分光光度计分析了薄膜的光学性能,压差法测定薄膜的透气性。采用SEM(scanning electron microscopy)和FTIR(Fourier transform infrared spectroscopy)方法分析反应膜的表面形貌和化学结构,利用静态接触角测量仪测定薄膜的接触角。结果表明:碱木质素加入后,在紫外光区200～400 nm薄膜的透过率为零,对紫外线全吸收,在可见光区400～800 nm薄膜透过率降低,当碱木质素与PVA质量比为1:4时,在600 nm处薄膜的透过率为16.12%;随着甲醛加入量的提高,薄膜可见光区的透光率逐渐增大;随着pH值增大,木质素逐渐溶解,pH值为9时,薄膜600 nm处薄膜透过率为20.85%。与纯PVA薄膜相比较,碱木质素加入后薄膜二氧化碳和氧气的透气性都减小;经甲醛交联后,薄膜的氧气和二氧化碳的透过量都增大;pH值由小到大变化时,碱木质素-聚乙烯醇反应薄膜对二氧化碳和氧气的透气量先增大后减小。FT-IR表征说明碱木质素-聚乙烯醇薄膜结构中有醚键生成,碱木质素和PVA发生了交联反应;电镜图片显示碱木质素-聚乙烯醇反应薄膜表面较光滑;接触角分析说明碱木质素的加入增大了薄膜与水的接触角,薄膜表面亲水性降低,并且交联反应薄膜的接触角大于共混薄膜的接触角,交联提高了薄膜的耐水性。与戊二醛相比甲醛做交联剂时碱木质素和PVA之间的交联反应程度更大,交联薄膜在可见光区的透光性更大。薄膜对紫外线吸收主要是受碱木质素的影响。碱木质素-聚乙烯醇反应膜可作为良好的紫外吸收材料,应用于地膜中。     

竹材草酸预水解过程木质素的溶出规律

为了探索用草酸预处理竹材制备溶解浆,该文用不同用量的草酸对竹材进行预水解,测定预水解过程竹材木质素含量的变化,用场发射扫描电镜(field emission scanning electron microscope,FE-SEM)观察水解后假木质素在竹纤维表面的分布状况,用核磁共振技术(cross polarisation/magic angle spinning carbon-13 nuclear magnetic resonance,CP/MAS 13C-NMR)分析木质素的结构变化。研究结果表明,在竹片草酸预水解过程中,竹片预水解得率将随着预水解时间的延长而下降,并且,草酸用量越大,得率下降越多。基于水解后竹材基质的木质素含量会随着预水解时间的延长而逐渐升高,并且,草酸用量越大,木质素含量升高越多;而基于竹材原料的木质素含量则随着预水解时间的延长先下降再增加,并且,草酸用量越大,增加的速率也越大。竹材木质素由于芳基醚键(β-O-4)断裂,酚型木质素含量提高。纤维素和半纤维素降解产物在预水解过程形成的假木质素类物质会以微球的形式附着在竹片表面。该研究可为探索竹材快速高选择性去除半纤维素的预水解方法提供参考。     

Impact of plant cell wall network on biodegradation in soil: Role of lignin composition and phenolic acids in roots from 16 maize genotypes

Residue quality is a key factor governing biodegradation and the fate of C in soil. Most investigations of relationships existing between crop residue quality and soil decomposition have been based on determining the relative proportions of soluble, cellulose, hemicellulose and lignin components. However, cell wall cohesion is increased by tight interconnections between polysaccharides and lignin that involve cross-linking agents (phenolic acids). The aim of this study was to determine the role of lignin composition and phenolic acids on short- to medium-term decomposition of maize roots in soil. Sixteen maize genotypes, presenting a range of chemical characteristics related to root lignin and phenolic acids, were used. The main components were characterized by Van Soest (VS) extraction and cell wall acid hydrolysis, and the non-condensed Syringyl and Guaicyl lignin monomers, esterified phenolic acids and etherified phenolic acids were determined. Maize roots were then incubated in soil under controlled conditions (15 °C, −80 kPa moisture) for 796 days. Results showed that VS extraction over-estimated the structural hemicellulose content and that VS lignin was more recalcitrant than Klason lignin. The tremendous effect of cell wall chemical characteristics was shown by marked variations (almost two-fold differences in C mineralization), between the 16 maize roots. Decomposition was controlled by soluble residue components in the short term whereas lignin and the interconnections between cell wall polymers were important in the long-term. Notably the cell wall domain rich in non-condensed lignin and esterified phenolic acids was prone to decomposition whereas the presence of etherified ferulic acids seemed to hamper cell wall decomposition.     

氨化木质素在丸粒化种衣剂中应用研究初报

以造纸工业废料——氨化木质素作为丸粒化种子包衣剂的辅料包衣花椰菜和豇豆种子,研究其应用效果,探索再生资源重复利用的新途径。结果表明,氨化木质素Ls-1能促进蔬菜幼苗生长发育和增产,可以在种子丸粒化包衣剂生产中充分利用。     

黄孢原毛平革菌对玉米秸秆木质素的降解研究

农作物秸秆还田是目前合理利用秸秆资源的有效方法之一,但不经预处理直接还田存在着许多不足之处.笔者通过分析玉米秸秆在黄孢原毛平革菌处理条件下木质素的降解情况,筛选出黄孢原毛平革菌对玉米秸秆木质素降解的最佳粒度与时间,为今后经济高效的还田产业提供理论基础.研究结果表明,黄孢原毛平革菌对大粒度的玉米秸秆(4~5和1~3 cm)较小粒度(0.5 cm)的降解效果好.在动态降解过程中,玉米秸秆的降解速率出现了两个高峰期,但不同粒度高峰期出现的时间略有不同.3种粒度的玉米秸秆分别在接菌35,40和35 d后累计降解率达到最大,其值分别为21.6%,35.6%和45.2%.综合比较,粒度为4~5 cm的玉米秸秆接种黄孢原毛平革菌35 d后,玉米秸秆达到最佳降解效果.     

春秋季萝卜生长中肉质根木质素含量变化研究

对春秋季萝卡生长过程中肉质根的本质素含量变化进行了研究。结果表明,春季木质素含量变化与秋季不同。春季,从破肚期到定桩期木质素含量变化不定,定桩期后木质素显著增加。秋季,从破肚期到定桩期再到露肩期,木质素含量变化不大,露肩期的木质素含量有所下降,采收期以后,木质素含量显著增加。春季萝卡除秋魁青外,其他品种在露肩期前均低于秋季的木质素含量,采收期后,春季萝卡肉质根中的木质素含量高于秋季,这表明,春季萝卡在生长期肉质根的木质化速度要比较季的大。木质素含量变化在红皮萝卡（水萝卜、大红袍）和白皮萝卡（短13、特早30天）之内存在显著差异。     

贵州山区生态茶园不同凋落物木质素、纤维素分解特征

采用凋落物分解袋法,以贵州久安生态茶园内云南樟（Cinnamomum glanduliferum）、光皮桦（Betula luminifera）、杉木（Cunninghamia lanceolata）和马尾松（Pinus massoniana）叶凋落物以及茶树（Camellia sinensis）修剪物为研究对象,分析5种单一凋落物类型,以及9种混合凋落物类型（茶树-云南樟、茶树-马尾松、茶树-杉木、茶树-光皮桦、杉木-光皮桦、云南樟-光皮桦、云南樟-马尾松、云南樟-杉木、光皮桦-马尾松）分解速率和木质素、纤维素释放特征及差异性。结果表明,单一凋落物类型中,阔叶树种凋落物分解速率大于针叶树种;阔叶树种凋落物木质素含量总体上呈现增加趋势,而针叶树种总体上则呈现下降趋势;凋落物纤维素含量总体上呈现下降趋势。单一凋落物纤维素释放规律与混合凋落物纤维素释放一致,均为直接释放;单一凋落物木质素释放存在3种规律;混合凋落物木质素释放规律有5种。分析9种混合凋落物分解特征,44.4%的混合凋落物混合分解表现为加和效应,11.2%的混合分解表现为拮抗效应,44.4%的混合分解表现为协同效应;22.2%的混合凋落物木质素的释放表现为促进释放,55.6%的混合凋落物木质素释放表现为促进富集;22.2%的混合凋落物纤维素释放表现为促进释放;11.1%的混合凋落物纤维素释放表现为促进富集。研究结果可为维持茶园肥力提供理论依据。     

砀山酥梨石细胞发育过程中木质素代谢关键酶POD类型的分析

 以不同发育时期的砀山酥梨为材料,通过组织化学定位、过氧化物酶（POD）活性及同工酶谱技术,研究木质素代谢关键酶POD不同类型,即谷胱甘肽POD（GSH-PX）、愈创木酚POD（PPOD）、抗坏血酸POD（APX）活性变化与石细胞中木质素代谢的关系,探讨梨果实石细胞发育过程中木质素代谢关键酶POD的类型。结果表明：（1）在砀山酥梨果实发育过程中,位于石细胞细胞壁及邻近区域的POD参与木质素在石细胞细胞壁上的沉积;（2）花后15 ~ 123 d,POD同工酶谱带主要分为3组酶活性区,其中PODⅠ的Rf值为0.13 ~ 0.23,PODⅡ的Rf值为0.44,PODⅢ的Rf值为0.63 ~ 0.96;（3）PPOD是砀山酥梨果实发育过程中木质素代谢关键酶POD的主要类型,参与木质素的合成,促进石细胞团的发育。     

Improvement of Antioxidant System and Decrease of Lignin by Nickel Treatment in Tea Plant

The effect of nickel (Ni) on the activities of antioxidant enzymes was evaluated in suspension-cultured cells of tea (Camellia sinensis L. cv. ‘Yabukita’) and two-year-old rooted cuttings of tea (Camellia sinensis L. assamica × sinensis). Suspension-cultured cells were grown in B5 medium and treated with 40 μM of Ni for 24 h. Tea plants were grown in a modified Hoagland solution and treated for one week with 40 μM of Ni. The activities of superoxide dismutase, catalase, ascorbate peroxidase, and ionically wall-bound peroxidase of both Ni-treated tea cells and Ni-treated tea plants increased compared with those of control groups. The activities of soluble peroxidase and covalently wall-bound peroxidase, as well as the lignin content of both tea cells and tea plants, decreased under Ni treatment. Thus it seems that Ni may have beneficial effects on tea plants via elevation of antioxidant activity and decrease of lignification of the walls.     

不同密度巨桉人工林凋落物分解过程中基质质量的变化

【目的】研究林分密度对巨桉(Eucalyptus grandis)人工林凋落物木质素和纤维素降解及基质质量组成的影响。【方法】收集巨桉人工林凋落物(叶和直径3~5mm的枝),部分凋落物在65℃烘干至恒质量并测定含水量、纤维素、木质素、C、N、P;部分自然风干后装入尼龙分解袋中,将分解袋置于稀疏(833株/hm2,株距×行距=1.5m×8m)、中密(1 333株/hm2,株距×行距=1.5m×5m)和高密(2 222株/hm2,株距×行距=1.5m×3m)巨桉林中自然分解,凋落叶于分解第60,120,180,210,240,300,360天取样,凋落枝于第90,180,270,360天取样,测定凋落物中养分、纤维素、木质素含量,计算碳/氮、木质素/氮、纤维素/氮、碳/磷、木质素/磷、纤维素/磷值,并采用Olson负指数衰减模型对木质素和纤维素残留率进行拟合。【结果】经过360d的分解,同一密度巨桉人工林凋落物中木质素的降解率小于纤维素的降解率。其中稀疏林凋落叶中木质素、纤维素的降解率分别为82.41%和93.77%,而凋落枝中木质素、纤维素的降解率分别为39.12%和65.65%。木质素、纤维素残留率拟合结果表明,分解系数k随着林分密度的增大而减小,稀疏林凋落物中木质素和纤维素质量损失50%和95%所需时间均短于高密林和中密林。随着巨桉林密度的减小,凋落物木质素和纤维素降解率增大,凋落物C/N减小,其中稀疏林的凋落叶、枝中C/N较初始值分别下降了12.73%和47.24%。凋落叶中木质素/N、C/P、木质素/P和凋落枝中纤维素/N、纤维素/P随着林分密度的减小而减小。【结论】四川华西雨屏区巨桉人工林凋落物分解过程中,不同林分密度对巨桉林凋落物基质质量有明显影响。