一乙酰基五硝基六氮杂异伍兹烷NMR谱归属

利用ＮＭＲ技术对ＣＬ－２０制备中伴生的少量副产物－乙酰基五硝基六氮杂异伍兹烷（ＭＰＩＷ）的＾１Ｈ、＾１３ＮＭＲ谱进行了完全的归属。     

The second time derivative analysis of chemiluminescence emission profiles and its application to the accurate determination of oxidative induction times

The technique of second time derivative (STD) analysis is developed and applied to the chemiluminescence (CL) profiles of two polypropylene (PP) formulations and a 5% w/w blend of polybutadiene (PBD) in PP to assess this novel method of analysis as a means of reliably determining the oxidative induction time (OIT) of polymers. It is proposed that the STD technique, when used in conjunction with the integrated CL profile, can enable evaluations of the OIT to be made that are less subjective than those made using the conventional extrapolation method. This is particularly so in systems that exhibit a gradual onset towards autoacceleration and/or convoluted CL profiles. Chemiluminescence profiles of the PBD–PP blend that were obtained at different temperatures were subjected to STD analysis, and Arrhenius plots of the data were made. The results are consistent with the notion that the PBD and PP phases oxidize almost independently. The activation energies for the oxidation of the PBD and PP phases were calculated to be 200 ± 31 kJ mol⁻¹ and 146 ± 9 kJ mol⁻¹, respectively. The higher activation energy for the PBD phase is partly attributed to the greater partitioning of thermal stabilizer in this phase. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1986–1993, 2001     

How Well Do MWL and CEL Preparations Represent the Whole Hardwood Lignin?

Hardwood lignin preparations were isolated using classical milled wood lignin (MWL) and cellulolytic enzyme lignin (CEL) protocols. Furthermore, we managed to produce a lignin preparation of a very high yield, above 90%, with high purity and minimal structural degradation. This was achieved by dissolution and regeneration of milled wood prior to enzymatic hydrolysis, along with the use of 80% dioxane for lignin extraction. This preparation (RCEL-80) yield was about 4.5 and 2.5 times higher than the yields of the traditional MWL and CEL preparations, correspondingly, at the same milling time. The preparations obtained were comprehensively analyzed with state-of-the-art quantitative NMR techniques and wet chemistry methods. CELs were representative preparations for hardwood lignins as the S/G ratios in the CELs were equivalent to those in lignin in situ. Degradation of the main lignin subunits was very low. Importantly, the structures of CELs were independent of the preparation yield and were very similar to the structure of the high-yield lignin, RCEL-80. In contrast, the structures of MWLs were noticeably dependent on the preparation yield, especially when the yield was below 15–20% of total wood lignin. In particular, the S/G ratio increased with increasing MWL yield, but was still lower than the S/G ratios of the whole lignins in situ, even at high MWL yields. The amounts of β-O-4 lignin units in MWL were lower than those in the corresponding CEL preparations. It has been concluded that CEL preparations were representative of the whole wood lignin whereas MWLs represent a fraction with a lower S/G ratio.     

六苄基六氮杂异伍兹烷氢解工艺的改进

提出了使用溴甲基（o,m,p-混合物）代替文献所使用溴苯等在六苄基六氮杂异伍兹烷（HBIW）一次氢解中为溴源物质,其结果提高了氢解收率,降低了溴源物质的用量和毒性,溴甲苯制造简单,有利于放大制备。     

高沸溶剂法制备核桃壳木质素

核桃壳中的木质素能在热的高沸溶剂(HBS)及少量催化助剂中溶解而与纤维素分离。由于HBS易溶于水而木质素难溶于水,因而加水能将溶解在HBS中的木质素沉淀出来。沉淀物经洗涤、低温冷冻干燥可得到低灰分的木质素。HBS经热蒸发去水后可循环使用。工艺过程无废液排放。HBS法能使木质自然资源得以充分利用,节能又不污染环境。     

二乙酰基四硝基六氮杂异伍兹烷分子和晶体结构

测定了制备CL－20的中间体二乙酰基四硝基六氮杂异伍兹烷（DATN）的晶体结构,发现其分子中两个乙酰基处于笼子的一个七元环上,因而可以认为DATN的生成是个高度立体选择性反应。     

酶解木质素的分离与结构研究

采用两种方法从酶解玉米秸秆制备能源酒精的残渣中分离得到酶解木质素。根据不同的分离条件,酶解木质素的得率为20%～35%。应用UV、FT-IR、GPC和13C-NMR研究了不同分离方法的酶解木质素的结构特性。结果表明,所分离的酶解木质素分子量较小,在结构上较好地保留了各种活性基团。与木质素磺酸钙相比,酶解木质素的红外图谱中多了1700cm-1和1328cm-1峰,说明酶解木质素存在非共轭羰基作用。紫外图谱在210nm,280nm和310nm附近有峰值出现,说明其具有木质素的基本结构特征,且结构上有很大的不饱和性。由13C-NMR图谱解析可知,所提取酶解木质素为GSH型木质素,主要以β-O-4、β-5、β-1的结构存在。以氢氧化钠作为萃取剂的酶解木质素提取率比有机溶剂高。酶解木质素的有效利用将提高酶解玉米秸秆制备能源酒精的经济效益。     

天然高分子对生物聚酯P(3,4)HB复合材料阻燃性能的影响

以三聚氰胺磷酸盐(MP)和季戊四醇磷酸酯(PEPA)复配的膨胀型阻燃体系阻燃聚(3-羟基丁酸酯-co-4-羟基丁酸酯)[P(3,4)HB], 分别用木质素、壳聚糖和海藻酸钠3种天然高分子作为成炭剂代替部分PEPA, 采用熔融共混法制备P(3,4)HB基阻燃复合材料。通过热重分析仪(TGA)、微型量热仪(MCC)、垂直燃烧仪(UL-94)、极限氧指数仪(LOI)及扫描电镜(SEM)等对其热稳定性、热燃烧性能、阻燃特性及炭渣形貌进行了表征与分析, 对比研究了3种天然高分子对P(3,4)HB基复合材料阻燃性能的影响。结果表明:含有木质素的复合材料体系燃烧后形成了致密而连续的炭层, 且能达到V-0级别, 而含壳聚糖或海藻酸钠的复合材料体系燃烧后形成的炭层结构多孔而疏松, 只能达到V-2级。     

高沸醇木质素的研究进展

高沸醇木质素是采用高沸醇溶剂法从植物原料中提取的木质素,具有纯度高、化学活性强等特点。介绍了高沸醇木质素的制备、结构以及应用基础研究的最新成果,尤其是高沸醇木质素环氧树脂、聚氨酯和聚合物改性材料方面的进展,展望了高沸醇木质素的应用前景。     

Genome-Wide Analysis of Respiratory Burst Oxidase Homologs in Grape (Vitis vinifera L.)

Plant respiratory burst oxidase homolog (rboh) genes appear to play crucial roles in plant development, defense reactions and hormone signaling. In this study, a total of seven rboh genes from grape were identified and characterized. Genomic structure and predicted protein sequence analysis indicated that the sequences of plant rboh genes are highly conserved. Synteny analysis demonstrated that several Vvrboh genes were found in corresponding syntenic blocks of Arabidopsis, suggesting that these genes arose before the divergence of the respective lineages. The expression pattern of Vvrboh genes in different tissues was assessed by qRT-PCR and two were constitutively expressed in all tissues tested. The expression profiles were similarly analyzed following exposure to various stresses and hormone treatments. It was shown that the expression levels of VvrbohA, VvrbohB and VvrbohC1 were significantly increased by salt and drought treatments. VvrbohB, VvrbohC2, and VvrbohD exhibited a dramatic up-regulation after powdery mildew (Uncinula necator (Schw.) Burr.) inoculation, while VvrbohH was down-regulated. Finally, salicylic acid treatment strongly stimulated the expression of VvrbohD and VvrbohH, while abscisic acid treatment induced the expression of VvrbohB and VvrbohH. These results demonstrate that the expression patterns of grape rboh genes exhibit diverse and complex stress-response expression signatures.