Chemical changes of kenaf core binderless boards during hot pressing (I): influence of the pressing temperature condition     

Nobuhisa Okuda  Keko Hori  Masatoshi Sato 《Journal of Wood Science》2006,52(3):244-248

Self-bonding is the main factor of the performance expression of binderless boards, and therefore its clarification is considered to be an important issue. For this purpose, a series of chemical analyses were conducted on kenaf core binderless boards and their chemical changes during the hot-pressing process are discussed in this article. First of all, binderless boards were prepared from kenaf core powder at different pressing temperatures (without steam-explosion process) and were used for chemical analyses after they were reduced into powders and extracted with methanol. To investigate their chemical changes, lignin, holocellulose, and neutral sugar contents were determined, Fourier transform infrared (FTIR) spectra were recorded, and the nitrobenzene oxidation procedure was applied. As a result, it was found that parts of lignin and hemicelullose were decomposed during the hot-pressing process; however, the contribution of the resulting fractions to selfbonding was not observed. In addition, progress of condensation reactions in lignin and the formation of chemical bonds by low molecular weight conjugated carbonyl compounds in methanol extractives were observed. Thermal softening of lignin is also suggested to play an important role in the expression of board performance.  相似文献   

木质素合成酶基因F5H的RT-PCR引物筛选     

付月  薛永常  姚奇 《辽宁林业科技》2007,(4):9-11,59

据EMBL核酸序列库中发表的白杨杂种F5H的cDNA序列,利用Primer 5.0软件设计3组扩增引物。通过PCR及RT-PCR扩增反应,筛选出一组比较合适的引物,确定该引物对的最适反应体系和程序参数。利用该引物对,从正在分化的2年生欧美杨107茎的次生木质部提取的mRNA中RT-PCR扩增出一个867bp的木质素合成特异表达的f5h基因片段。将其克隆到pGM-T载体上,构建了f5h在大肠杆菌中的表达载体,并对引物筛选进行讨论。  相似文献   

硫酸盐草浆黑液制粉状活性炭的研究   总被引：2，自引：0，他引：2  

胡淑宜  黄碧忠 《福建林业科技》1993,20(4):33-37

本文探讨硫酸盐草浆纸厂黑液的治理和利用,提出用酸化法从黑液中沉析木素制取粉状活性炭。大约生产10t草浆可制取1t优质粉状活性炭。同时还含有占总碱量24%的Na_2S可回收。排出的废液即使不再经过处理,其污染程度也已大大降低。  相似文献   

木质素-LDPE扭矩流变性能试验研究     

黎先发  罗学刚 《福建林业科技》2007,34(4):8-12

研究了影响木质素与低密度聚乙烯(LDPE)共混物在转矩流变仪中的共混最大扭矩、平衡扭矩以及达到平衡扭矩时间的各个因素。结果表明,木质素、淀粉降解母料、增塑剂、温度对扭矩有明显影响;在LDPE为100份时,木质素55份,淀粉母料25份,增塑剂占木质素7.5%,增容剂10.5份,温度为180℃,共混物塑化性能最优。  相似文献   

木质素电氧化的影响因素研究   总被引：3，自引：0，他引：3  

薛建军  钟飞 《林产化学与工业》2002,22(3):37-40

木质素是天然高分子聚合物，具有一定的化学反应惰性。本文率先研究草类木质素在膜助电解时的电化学氧化作用。其结果表明：膜助电解对黑液中的有机物具有一定的氧化作用，能使木质素中的芳环被氧化而打开；同时木质素的氧化作用与施加的电压、阳极的电极材料等因素有关。通过对木质素氧化产物结构的进一步研究，可为木质素的电化学改性提供了新的方法。  相似文献   

3种白腐菌木质素降解酶的比较   总被引：1，自引：0，他引：1  

董旭杰  曹福祥  陈静  吕聪  DONG Xu-jie  CAO Fu-xiang  CHEN Jing  Lü Cong 《中南林业科技大学学报(自然科学版)》2007,27(3):131-135

对3种白腐菌——黄孢原毛平革菌、变色栓菌和木质层孔菌在恒温振荡培养条件下产漆酶、锰过氧化物酶的情况进行比较研究,同时还对此3种菌在培养过程中还原糖的变化作了研究.结果表明:3种白腐菌中变色栓菌产漆酶相对最高,其漆酶酶活最高达到136.5 U/L,产酶最高时间为第8天;而木质层孔菌产锰过氧化物酶相对最高,其最高酶活达到880.2 U/L,产酶最高时间为第8天;同时在培养过程中还原糖含量随培养时间的延长而逐渐降低.  相似文献   

PCR法克隆紫穗槐4-香豆酸:CoA连接酶全长cDNA     

刘文哲  胡学军  高晓蓉  袁晓东  刘哲  范琦  安利佳 《中国林学(英文版)》2002,4(1):13-17

4 香豆酸 :CoA连接酶 (4CL)是木质素生物合成过程中重要的酶 .该文利用简并寡核苷酸PCR法结合cDNA末端快速扩增PCR法直接获得了紫穗槐 4CLAcDNA全长序列 ,避免了复杂的构建、筛选cDNA文库的过程 .先用简并PCR得到了 4CLA1片段 ,又据此片段设计反向嵌套引物 ,用RACE方法获得未知的 5′和 3′端序列 .所获得的全长 4CLAcDNA ,编码 5 40个氨基酸 .氨基酸序列同源性分析表明4CLA是典型的 4CL蛋白 ,含有预计的AMP binding位点、催化反应区和保守的Cys .  相似文献   

Lignin fragments rich in detached side-chain structures found in water-soluble LCC     

Hikaru Aimi  Yuji Matsumoto  Gyosuke Meshitsuka 《Journal of Wood Science》2005,51(3):252-255

The content of the glyceraldehyde-2-aryl ether-type structure in water-soluble lignin–carbohydrate complex (LCC) fractions, which were obtained from Japanese cedar and birch residual wood meal after milled wood lignin isolation, was determined by ozonation. Quite high amounts of the glyceraldehyde-2-aryl ether-type structure were found in water-soluble LCC fractions of both species; about 3–5 times higher than those of other fractions. This result, as well as the high content of the β-1 structure in these fractions shown in our previous reports, suggest that lignin in these fractions has the characteristics of endwise-type lignin, because the glyceraldehyde-2-aryl ether-type structure and β-1 structure are typical characteristics of this type of lignin fraction. These results are in good agreement with the generally accepted hypothesis that the glyceraldehyde-2-aryl ether-type structure and β-1 structure are generated at the same time by a radical coupling reaction. The results also indicated that these two structures are present in close proximity in the lignin.  相似文献   

纤维素废料与造纸黑液木质素制人造木材之探讨     

蒋应梯 《林产化学与工业》2005,25(10):165-167

介绍了现有人造木材的种类，阐述了用竹刨花、竹（木）屑等竹（木）加工剩余物或农作物秸秆与造纸黑液中提取的木质素开发人造木材的重大意义，简要介绍了该人造木材的制造原理和方法以及产品的用途，并分析了人造木材的市场前景及其产业化的可行性。  相似文献   

Screening of extracts of Japanese woods for melanin biosynthesis inhibition     

Kuniyoshi Shimizu  Shoko Fukunaga  Keisuke Yoshikawa  Ryuichiro Kondo 《Journal of Wood Science》2007,53(2):153-160

The effects of 120 methanol extracts prepared from bark and heartwood of 69 types of Japanese wood on the melanin production of B16 melanoma cells were examined. The melanin content of B16 melanoma cells was determined spectrophotometrically at 405nm. The extracts were also examined for their effects on cell viability. We found that the methanol extracts of Fagus crenata (buna, wood, 100μg/ml), Sapium sebiferum (Nankinhaze, wood, bark, 10μg/ml), and Zelkova serrata (keyaki, wood, 10μg/ml) greatly inhibited the melanin production of B16 melanoma cells without significant cytotoxicity. However, these extracts did not inhibit tyrosinase activity at the concentration of 100μg/ml. These findings indicate that the depigmenting mechanism of these extracts involves the suppression of some pigmenting signals in stimulating melanogenesis rather than the inhibition of tyrosinase activity. Part of this study was presented at the 53rd Annual Meeting of the Japan Wood Research Society, Fukuoka, Japan, March 2003  相似文献