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881.
We adapted and optimized a method to quantify the cellulose, hemicellulose, xylan, arabinan, mannan, galactan contents in lignocellulosic biomass. This method is based on a neutral detergent extraction (NDE) of the interfering biomass components, followed by a sulfuric acid hydrolysis (SAH) of the structural polysaccharides, and a liquid chromatography with charged aerosol detection (LC-CAD) to analyze the released monosaccharides. The first step of this NDE-SAH-LC-CAD method aims at removing all compounds that interfere with the subsequent sulphuric acid hydrolysis or with the subsequent chromatographic quantification of the cellulosic and hemicellulosic monosaccharides. This step includes starch hydrolysis with an analytical thermostable α-amylase followed by an extraction of soluble compounds by a Van Soest neutral detergent solution (NDE). The aim of this paper was to assess the precision of this method when choosing fiber sorghum (Sorghum bicolor (L.) Moench), tall fescue (Festuca arundinacea Schreb.) and fiber hemp (Cannabis sativa L.) as representative lignocellulosic biomass. The cellulose content of fiber sorghum, tall fescue and fiber hemp determined by the NDE-SAH-LC-CAD method were 28.7 ± 1.0, 29.7 ± 1.0 and 43.6 ± 1.2 g/100 g dry matter, respectively, and their hemicellulose content were 18.6 ± 0.5, 16.5 ± 0.5 and 14.5 ± 0.2 g/100 g dry matter, respectively. Cellulose, mannan and galactan contents were higher in fiber hemp (dicotyledon) as compared to tall fescue and fiber sorghum (monocotyledons). The xylan, arabinan and total hemicellulose contents were higher in tall fescue and fiber sorghum as compared to fiber hemp. The precision of the NDE-SAH-LC-CAD method was better for polysaccharide concentration levels above 1 g/100 g dry matter. Galactan analysis offered a lower precision, due to a lower CAD response intensity to galactose as compared to the other monosaccharides. The dispersions of the results (expanded uncertainty) of the NDE-SAH-LC-CAD method were smaller as compared to the Van Soest (VS) method. In addition, the NDE-SAH-LC-CAD method was able to provide additional information on the composition of the hemicellulose (xylan, arabinan, mannan and galactan content) that is not provided by the Van Soest method. The NDE-SAH-LC-CAD method offers also the advantage of a better specificity for hemicellulose and cellulose, as compared to the NREL and Uppsala methods. 相似文献
882.
Inertial effects in fluctuations of the work to sustain a system in a nonequilibrium steady state are discussed for a dragged
massive Brownian particle model using a path integral approach. We calculate the work distribution function in the laboratory
and comoving frames and prove the asymptotic fluctuation theorem for these works for any initial condition. Important and
observable differences between the work fluctuations in the two frames appear for finite times and are discussed concretely
for a nonequilibrium steady state initial condition. We also show that for finite times a time oscillatory behavior appears
in the work distribution function for masses larger than a nonzero critical value. 相似文献
883.
Joseph I. Kapusta 《Physics in Perspective (PIP)》2008,10(2):163-181
The possibility that experiments at high-energy accelerators could create new forms of matter that would ultimately destroy
the Earth has been considered several times in the past quarter century. One consequence of the earliest of these disaster
scenarios was that the authors of a 1993 article in Physics Today who reviewed the experiments that had been carried out at the Bevalac at Lawrence Berkeley Laboratory were placed on the
FBI’s Unabomber watch list. Later, concerns that experiments at the Relativistic Heavy Ion Collider at Brookhaven National
Laboratory might create mini black holes or nuggets of stable strange quark matter resulted in a flurry of articles in the
popular press. I discuss this history, as well as Richard A. Posner’s provocative analysis and recommendations on how to deal
with such scientific risks. I conclude that better communication between scientists and nonscientists would serve to assuage
unreasonable fears and focus attention on truly serious potential threats to humankind.
Joseph I. Kapusta: Joseph I. Kapusta received his Ph.D. degree at the University of California at Berkeley in 1978 and has
been on the faculty of the School of Physics and Astronomy at the University of Minnesota since 1982. He is the author of
over 150 papers in refereed journals and conference proceedings and of Finite Temperature Field Theory (Cambridge University Press, 1989; second edition with Charles Gale, 2006). 相似文献
884.
计算机实验室承担大学生在计算机上做实验的基础课、专业课、选修课和学科竞赛等各专业实验教学任务。通过对实验室在高校创新人才培养中存在问题和重要性进行分析,以计算机实验室为例研究了实验室与应用型创新人才培养之间的关系,以培养大学生计算机的综合应用能力和创新能力为目标的开放、互联、共享计算机实验室对应用性创新人才培养发挥了重要作用。 相似文献
885.
886.
“制药过程安全与环保”为制药工程专业本科生必修核心课程,但其课程体系不完善,基于OBE和EHS理念,从课程目标、课程内容、课程思政、教材、教学方法、课程考核与评价方法等方面对该课程进行了建设和完善,取得了一些创新性成果与经验,制定了教学目标,创新性地设置了课程内容,开展了课程思政,主编了教材,提出了适宜的教学方法,建立了课程考核与评价方法,可以为全国其他高等院校类似课程的教学与建设提供有益的借鉴。 相似文献