我国栓皮栎和麻栎木材的主要化学组成分析

选取不同树干高度的栓皮栎和麻栎木材,分别测定树皮、边材和心材的苯醇抽出物、综纤维素(α-纤纤维素和半纤维素)、木质素(酸不溶和酸溶木质素)、灰分、pH值和缓冲容量,为软木及栎木人造板的生产加工利用提供科学依据。栓皮栎软木生产工艺应关注树皮苯醇抽出物含量、灰分、pH值及缓冲容量;用于人造板加工,则需考虑树种及心边材纤维素、木质素和pH值。     

人心果乳汁的流变学特性

通过测定浓度、pH值、温度、剪切力变化等对人心果乳汁溶液粘度的影响及与黄原胶的协效性,对人心果乳汁溶液的流变学特性进行了研究.结果表明:随着浓度的升高,人心果乳汁粘度逐渐上升;酸在一定程度上能降低溶液粘度;温度和剪切力均能改变溶液的粘度;人心果乳汁与黄原胶溶液有一定的协效性,但其协效性较低.     

橡实淀粉粘度特性的研究

研究了淀粉乳质量浓度、pH值、温度、盐和常用食品添加剂等对橡实淀粉粘度的影响,结果表明:淀粉质量浓度增加,橡实淀粉的粘度呈幂次方上升;酸碱都能不同程度地降低橡实淀粉的粘度;温度升高,橡实淀粉的粘度逐渐降低;不同盐、添加剂的种类和质量浓度对橡实淀粉的粘度有极显著影响;测试转速的加快,各种橡实淀粉的粘度均迅速下降;橡实淀粉糊是非顿流体.     

芦荟多糖提取工艺的优化

从芦荟中提取芦荟多糖,研究乙醇浓度、醇沉时间、醇沉温度、pH值这4个因素对提取结果的影响,提出最佳工艺条件为：以80%的乙醇浓度,醇沉时间为5 h,醇沉温度为0℃,pH值控制在5时,多糖的收率是最高的。     

木质素-LDPE扭矩流变性能试验研究

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。     

桉木AS-AQ蒸煮及木质素特性研究

实验结果表明,桉木AS-AQ蒸煮到145 ℃以前,木质素磺化反应占主导地位,温度升高木质素大量溶出;蒸煮后期,残余木质素和溶出木质素发生缩合反应,从而导致纸浆的KMnO4值上升,白度下降.通过实验,论证了纸浆中残余木质素含量高的原因.     

黑木相思木材化学性质株内变异研究

研究我国黑木相思木材化学性质的株内变异规律,为其加工利用提供基础数据。对广东韶关产28 a黑木相思木材进行化学组成测定,其综纤维素(α纤维素、半纤维素)、酸不溶木质素和抽出物(冷水、热水、1%氢氧化钠、苯醇)的含量在株内纵向上的变异规律不明显;相较于边材,心材的综纤维素含量略低,酸不溶木质素含量略高,抽出物含量更高,pH值更低。实际加工利用中需考虑其心材和边材比例对原料化学组成的影响。     

塔拉胶理化性质分析

采用国内食品添加剂的一般常用检测方法研究了温度、pH、盐、浓度、时间等对塔拉胶液的影响。结果表明,随时间和温度的增加塔拉胶液粘度增加,在低浓度时增加幅度小,高浓度时呈梯度增加。30-50℃时对胶液的分散效果和粘度影响小,60-70℃时胶液的分散效果和粘度明显增加,80℃和90℃时呈梯度增加,但80℃时1%浓度下塔拉胶液分散效果最好,粘度达到最大;塔拉胶液对盐具有稳定性,塔拉胶液中无淀粉检出,pH对塔拉胶液的稳定性影响小。参照食品添加剂的标准,根据实验结果提出塔拉胶的较佳溶胶参数,为塔拉胶的应用提供理论依据。     

杨木预水解过程中化学组分的降解行为及P因子调控作用

预水解具有环境友好性,符合生物炼制的理念。前期关于预水解的研究多集中于半纤维素的降解、分离和利用,而有关预水解过程中木质素降解的系统研究鲜有报道。以杨木为原料,在130~210℃条件下保温30~120 min进行预水解,结合P因子研究得率、葡聚糖、木聚糖、酸不溶木质素和酸溶木质素的降解率,揭示P因子对木质素降解行为的调控作用,探讨各化学组分在预水解过程中的相互作用。研究表明,预水解过程中木质素发生了一定程度的碎片化。随温度升高和时间延长,酸不溶木质素降解率均逐渐升高;当温度为190和210℃时,随时间延长,酸溶木质素降解率先升高后降低。试验证明,P因子对杨木木质素的降解具有调控作用。随着P因子增加,酸不溶木质素降解率呈指数上升,且分为快速降解(P因子<1500)和缓慢降解(P因子>1500)两个阶段;酸溶木质素降解率先上升后下降,在P因子为1926时达到最大值45.9%。此外,预水解过程中碳水化合物和木质素的降解具有相互作用关系。碳水化合物的降解为木质素的溶出打开了物理通道,同时木质素的重新吸附阻碍了其进一步降解。     

亚硫酸氢盐预处理对玉米秸秆酶水解的影响

研究了亚硫酸氢钠对玉米秸秆进行预处理的条件,主要考察了亚硫酸氢钠用量、预处理温度和pH值对玉米秸秆酶水解效率的影响。结果表明:在温度180℃、保温30min时,随着亚硫酸氢钠用量的增加,木质素和半纤维素的溶出量增大,从而促进玉米秸秆预处理后底物的酶水解,当亚硫酸氢钠用量为7%时,酶水解转化率和葡萄糖得率分别为69.40%和62.44%;预处理温度越高,酶水解效率越高,温度190℃、保温30min时底物酶水解转化率达到了81.04%,葡萄糖得率71.91%;预处理pH值升高,酶水解效率相应增大,pH值在4.2～4.7之间时,酶解效率增加明显。     

利用CaO/PAC选择性去除预水解液中木质素

利用CaO结合聚合氯化铝(PAC)来选择性去除预水解液中的木质素。分别探讨了酸化法、碱化法及其结合PAC选择性去除木质素的效果,并分析了PAC选择性去除木质素的机理。结果表明:酸化法pH值为1.5时,木质素去除率最大(杨木15.68%,麦草18.76%);而采用CaO调节pH值为12时,木质素去除率最大(杨木33.33%,麦草30.67%),碱化法去除效果优于酸化法。添加CaO将pH值调至10并使PAC浓度为36 mmol/L时,预水解液中木质素的去除率(杨木50.59%,麦草49.17%)及选择性(杨木86.57%,麦草82.76%)效果最佳。     

气候和枯落物质量对印度东部亚热带森林凋落叶分解和营养回归的影响(英文)

为了评价印度东部曼尼普尔亚热带橡树混交林中的土壤养分收支平衡情况,研究了全年不同月份的3个主要树种,枹栎(Quercus serrata)、木荷(Schima wallichi)和滇石栎(Lithocarpus dealbata)的枯落物分解和营养回归情况。印度东部橡树林是生产柞蚕丝的重要经济树种。林下2-7月月枯落物为25.6 g·m-2(7月)和198.0 g·m-2(2月),年枯落物为1093 8g·m-2。在初始月(11月3),滇石栎森林壤土的氮和碳浓度最高,其次是在枹栎林。最低的是木荷林。但就木质素和纤维素含而言,木荷林中的最高,其次是袍栎林和滇石栎林。滇石栎林(k=0.54)具有较高的枯落物分解率,这与月初枯落物中含有较高的氮和碳浓度以及低含量的纤维素相符合。然而,在木荷森林中枯落物分解率低,是与月初时森林土中具有低浓度氮和碳及高浓度木质素和纤维素相符合。在不同月份,剩余的生物量与木质素、碳、碳氮比和纤维素含量呈正相关,但与氮含量呈负相关。由于环境条件的影响,在寒冷和冬季枯落物分解率最低,而在雨季枯落物分解率最高。图3表5参52。     

Decomposition and nutrient release patterns of Phyllostachys bambusoides and Arundinaria racemosa, India

We investigated decomposition and nutrient release patterns of leaf and sheath litter of two important highland bamboo species (viz. Phyllostachys bambusoides Sieb. (Zucc.) and Arundinaria racemosa Munro) by using a litter bag technique. Our objective was to improve understanding of the addition of organic matter and nutrients to soil from the litter of two abundant highland bamboo species, species that support the local population of the region in many ways. N concentration and N/P ratio were significantly higher (p<0.01) in leaf litter of P. bambusoides. Significantly, larger values of lignin concentration, C/N ratio, and lignin/N ratio were found in the sheath litter of A racemosa. Weight loss of both leaf and sheath litter was strongly positively correlated with N and N/P ratio, and significantly negatively correlated (p<0.01) with C/N ratio. Lignin/N had a negative correlation with decay rate. In both species, only lignin concentration of the litter showed strong positive correlation with N release. Litter decomposition and N release patterns were similar for the two bamboo species, whereas, P release rate from leaf litter was higher in P. bambusoides and differed significantly between sheath and leaf litter for both species. The complex pattern of nutrient release through mineralization and immobilization during litter decomposition ensures nutrient availability in both managed and natural bamboo stands subjected to anthropogenic disturbances.     

麦草碱木质素烷基化反应的研究

用不同的卤代烷烃与碱木质素进行烷基化反应。探讨了烷基化试剂种类，反应温度、时间、PH值等因素对产物性质的影响，发现，当烷基化试剂为溴代十二烷，反应时间3h、反应温度170℃，PH12时，木质素的反应率和反应产物表面活性较高，对烷基化碱木质素进行磺化，可以改善其水溶性，进一步提高其表面活性。     

Seasonal changes in lignin distribution during tracheid development in Pinus radiata D. Don

Summary Lignin distribution in developing tracheids of Pinus radiata was studied throughout the growth' season using quantitative interference microscopy. The pattern of lignification remained constant although the number of lignifying cells varied reaching a maximum in summer. Lignification of the secondary wall of latewood tracheids was incomplete at the onset of winter. Each stage of lignification was preceded by deposition of carbohydrates with lignification of the middle lamella starting after S1 formation and lignification of the secondary wall starting after S3 formation. Lignification of the middle lamella was completed before the start of lignin deposition in the secondary wall. In one of the trees examined, the secondary wall lignified concurrently with the middle lamella and this was associated with a low lignin concentration in the middle lamella of mature cells. The secondary wall reached a mature lignin concentration of 21–22% v/v except in one specimen containing severe compression wood which reached 28% v/v. The cell corner middle lamella reached a mature lignin concentration of 74–87% v/v.     

木荷种源鲜叶抑燃和助燃性化学组分的差异

选择木荷15个代表性种源,以研究火险期鲜叶主要抑燃性和助燃性化学组分的种源差异及地理变异模式。结果表明,木荷叶片含水量、灰分、木质素、粗脂肪和苯-乙醇抽出物5个化学组分在种源间存在显著的差异,其最高和最低种源测定值分别相差5％、31％、80％、66％和33％,尤以灰分和粗脂肪两组分的种源差异最大。木荷种源鲜叶的上述5个化学组分都呈现随纬度变化的地理模式,木质素和粗脂肪质量分数还与产地经度有关。较之于分布区北部的种源,木荷南部种源鲜叶的含水量、灰分等抑燃性组分质量分数高,粗脂肪、苯醇抽出物等助燃性组分质量分数低。木质素作为一种不易燃烧但燃烧时能释放大量热量的组分,呈与产地纬度显著正相关的关系,有异于含水量和灰分两个抑燃性组分的地理变异模式。结合苗期种源试验结果,可以初步判定分布区南部的种源生长快,根系发达、叶片数量多,鲜叶抑燃性组分质量分数高,助燃性组分质量分数低,因此防火性能较好。     

聚合氯化铝对木质纤维素MgCl2预处理液的纯化

预处理是生物质资源转化的关键步骤,其过程会使植物细胞壁的结构发生变化,从而降低生物质的顽固性并增强其中糖的有效溶解,以促进其高值化利用。预处理液成分复杂,所含木质素和多种降解产物不利于糖类的高效利用,需要对其进行分离纯化。以桉木经MgCl₂预处理的废液为对象,通过聚合氯化铝(PAC)絮凝的方法去除其中的大分子木质素,利用Zeta电位和粒径检测、高效液相色谱法、紫外光谱法等技术分析絮凝处理前后预处理液的成分变化,并对其去除机理进行深入研究。结果表明:当PAC用量为4.00%质量分数时,反应体系Zeta电位为0,此时胶体稳定性最差,可获得较大的木质素沉淀量;当预处理液的pH接近3.00时,刚好达到等电点,体系中正负电荷中和不稳定,胶体颗粒粒径最大,出现明显絮凝沉淀;随着pH的升高,PAC对木质素的去除效果仍有明显增强,综合所有因素可知,在pH为10.00、PAC用量为2.00%质量分数时,处理体系对木质素的絮凝表现出良好的选择性,木质素的选择性去除率可达86.05%。由此可知,PAC主要是通过静电和桥联双重作用改善预处理液的胶体稳定性,使预处理液中的木质素大分子优先沉淀,体现出良好的选择性,是一种非常有潜力的预处理液纯化方法,值得进一步探究和优化。     

3种百合淀粉糊的特性

以株洲本地卷丹Lilium lancifolium Thunb淀粉(样品1)、宜章县成品卷丹淀粉(样品2)和麝香百合L. longifcorum Thunb淀粉(样品3)为原料,对淀粉的透光性能、凝沉性能以及粘度变化规律进行了研究.结果表明:百合淀粉的凝沉性较大,而且其凝沉性还受添加剂的影响,在淀粉糊中添加1.0% NaCl后,3种样品的凝沉性都增强,添加1.0%的蔗糖能有效地抑制凝沉的发生;百合淀粉糊的透明度很低,3种样品的透光率都在14%以下;3种百合淀粉糊的粘度随浓度的升高而升高,随转速和温度的升高而降低,在pH值7.0左右粘度最高.     

Decomposition of Mongolian pine litter in the presence of understory species in semi-arid northeast China

The effects of understory plant litter on dominant tree litter decomposition are not well documented especially in semi-arid forests. In this study, we used a microcosm experiment to examine the effects of two understory species (Artemisia scoparia and Setaria viridis) litter on the mass loss and N release of Mongolian pine (Pinus sylvestris var. mongolica) litter in Keerqin Sandy Lands, northeast China, and identified the influencing mechanism from the chemical quality of decomposing litter. Four litter combinations were set up: one monoculture of Mongolian pine and three mixtures of Mongolian pine and one or two understory species in equal mass proportions of each species. Total C, total N, lignin, cellulose and polyphenol concentrations, and mass loss of pine litter were analyzed at days 84 and 182 of incubation. The chemistry of pine litter not only changed with the stages of decomposition, but was also strongly influenced by the presence of understory species during decomposition. Both understory species promoted mass loss of pine litter at 84 days, while only the simultaneous presence of two understory species promoted mass loss of pine litter at 182 days. Mass loss of pine litter was negatively correlated with initial ratios of C/N, lignin/N and polyphenol/N of litter combinations during the entire incubation period; at 182 days it was negatively correlated with polyphenol concentration and ratios of C/N and polyphenol/N of litter combinations at 84 days of incubation. Nitrogen release of pine litter was promoted in the presence of understory species. Nitrogen release at 84 days was negatively correlated with initial N concentration; at 182 days it was negatively correlated with initial polyphenol concentration of litter combinations and positively correlated with lignin concentration of litter combinations at 84 days of incubation. Our results suggest that the presence of understory species causes substantial changes in chemical components of pine litter that can exert strong influences on subsequent decomposition of pine litter.