Peracetic acid pretreatment of sugarcane bagasse for enzymatic hydrolysis: a continued work

Previous work has shown that the enzymatic hydrolysis of sugarcane bagasse could be greatly enhanced by peracetic acid (PAA) pretreatment. There are several factors affecting the enzymatic digestibility of the biomass, including lignin and hemicelluloses content, cellulose crystallinity, acetyl group content, accessible surface area and so on. The objective of this work is to analyze the mechanism of the enhancement of enzymatic digestibility caused by PAA pretreatment. Delignification resulted in an increase of the surface area and reduction of the irreversible absorption of cellulase, which helped to increase the enzymatic digestibility. The Fourier transform infrared (FTIR) spectrum showed that the absorption peaks of aromatic skeletal vibrations were weakened or disappeared after PAA pretreatment. However, the infrared crystallization index (N.O'KI) was increased. X‐ray diffraction (XRD) analysis indicated that the crystallinity of PAA‐treated samples was increased owing to the partial removal of amorphous lignin and hemicelluloses and probable physical change of cellulose. The effect of acetyl group content on enzymatic digestibility is negligible compared with the degree of delignification and crystallinity. The results indicate that enhancement of enzymatic digestibility of sugarcane bagasse by PAA pretreatment is achieved mainly by delignification and an increase in the surface area and exposure of cellulose fibers. Copyright © 2008 Society of Chemical Industry     

The influence of raw material characteristics on the industrial pelletizing process and pellet quality

Industrial pelletizing of sawdust was carried out as a designed experiment in the factors: sawdust moisture content, fractions of fresh pine, stored pine and spruce. The process parameters and response variables were energy consumption, pellet flow rate, pellet bulk density, durability and moisture content. The final data consisted of twelve industrial scale runs. Because of the many response variables, data evaluation was by principal component analysis of a 12 × 9 data matrix. The two principal component model showed a clustering of samples, with a good reproducibility of the center points. It also showed a positive correlation of energy consumption, bulk density and durability all negatively correlated to flow rate and moisture content. The stored pine was more related to high durability and bulk density. The role of the spruce fraction was unclear. The design matrix, augmented with the process parameters was a 12 × 6 matrix. Partial least squares regression showed excellent results for pellet moisture content and bulk density. The model for durability was promising. A 12 × 21 data matrix of fatty- and resin acid concentrations measured by GC–MS showed the differences between fresh and stored pine very clearly. The influence of the spruce fraction was less clear. However, the influence of the fatty- and resin acids on the pelletizing process could not be confirmed, indicating that other differences between fresh and stored pine sawdust have to be investigated. This work shows that it is possible to design the pelletizing process for moderate energy consumption and high pellet quality.     

青藏铁路西格二线混凝土冻融试验研究

由于工期的要求,青藏铁路西格增建二线必须进行冬期施工。根据工程状况,分析了混凝土受冻的破坏机理,针对施工环境及对混凝土设计强度和要求,进行了大量冻融试验分析,对引气剂、水胶比、砂率、粉煤灰掺量等原材料与混凝土含气量的关系及其混凝土搅拌温度与静停时间等对混凝土性能的影响进行了分析与技术论证,确保了该线冬期混凝土施工顺利进行。     

声波时差测井在鄂尔多斯天然气勘探中的地质应用

本文应用声波时差测井资料判别划分地层压实异常段,并结合其它测井资料对盖层进行质量评估,寻找油气有利聚集带(段),为勘探提供有利区域和评价依据。     

不同灌溉条件下的水稻需水规律及水分生产率分析

稻田需水量包括植株蒸腾、棵间蒸发、田间渗漏3部分。研究表明，水稻在充分供水条件下所形成的蒸腾量中包含了一部分无效蒸腾，无效蒸腾量的减少不会影响作物的生长发育，反而会有不同程度的增产和优质效应。节水灌溉技术的推广产生了明显的经济与社会效益。结合当地实际情况采用3种常见的灌溉方式探讨了不同灌溉方式下水稻的需水规律、灌概定额和生产率的差异，为水稻节水高效栽培提供理论与技术依据。     

F级高云母含量云母带的研制及应用

本文介绍了一种F级高云母含量云母带，它的主要特点是云母含量高达48％以上，具有良好的长时间耐电热老化性能，适用于高压电机主绝缘多胶模压工艺要求，该云母带的应用对提高电机绝缘水平和延长电机使用寿命具有重要意义。     

基于遗传神经网络的电站锅炉飞灰含碳量预测

针对锅炉飞灰含碳置影响因素复杂．实时测量难度大．精度低，提出了一种基于遗传神经网络的预测方法，并用于某电厂，结果表明，该方法是有效的。     

区域内旱情监测站点的布设研究

本文对北京通州辖区范围内组织的大规模的土壤墒情调查数据进行总结。基于地理统计、空间分析以及统计学知识，分析了北京通州旱情分布形势。运用数值分类学的知识对测量数据进行了聚类分析，同时用DB(DaviesBouldin)指标准则研究了区域内合理布设旱情监测站的数量及位置，为建立旱情监测站点提供了理论依据。     

包钢选矿厂降低铁精矿中氟含量的技术攻关

为了降低铁精矿氟含量,通过采取控制磨矿粒度、改进浮选工艺、采用高效捕收剂等措施,使包钢选矿厂铁精矿氟含量由1999年的0.75%降低到2000年的0.65%、2001年的0.58%,为包钢环保工作目标的完成做出了突出贡献.