Physicochemical characterization of alkali pretreated sugarcane tops and optimization of enzymatic saccharification using response surface methodology

Alkali pretreatment of sugarcane tops was carried out with 3% NaOH for 60 min at 121 °C in a laboratory autoclave. The effect of solid loading, enzyme loading, incubation time and surfactant concentration on enzymatic saccharification was studied using a response surface method according to Box–Behnken design. Under optimized conditions 77.5% sugar was recovered from the pretreated biomass. This yield was seven times higher than that obtained with untreated sugarcane tops. A substantial amount of lignin (90%) was removed by this pretreatment method. Physicochemical characterization of native and alkali pretreated sugarcane tops were carried out by XRD, FTIR and SEM and the changes in the chemical composition were also monitored. The X-ray diffraction profile showed that the degree of crystallinity was higher for alkali pretreated biomass than that for native.     

浅析梳棉机弹性盖板针布充塞挂花起因

为提高梳棉机弹性盖板针布对纤维的分梳、除杂、均匀、混合等梳理效果,解析了弹性盖板针布分梳纤维的过程;通过建立理论模型,进一步分析了弹性盖板针布与锡林针布之间分梳纤维时的力学状态,归纳、建立数学关系式μ=tanα;联系生产实际,解析弹性盖板针布充塞挂花的起因.指出:弹性盖板针布充塞挂花的根源在于对针布与纤维之间的摩擦因数...     

倾斜基岩在动载作用下群桩桩顶的最大弯矩分布

倾斜基岩上的框架是山地，丘陵地区多见的一种结构形式，但以往对其抗震性能研究很少。本文针对一柱一桩，桩间设置地梁的基础形式，引入了多次透射边界以模拟场地的无限性，利用二次开发后的ANSYS对倾斜基岩上的框架在ElCentro波、Taft波作用下群桩桩顶的荷载分布进行了上下部共同作用分析，以定性的判断地震作用下不同位置桩的受力情况。为了探讨桩端不同约束方式对桩顶最大弯矩的影响，每个算例都分别计算了桩端铰接和桩端固接两种情况。对于倾斜基岩，在A类、B类土层情况下，各桩的最大弯矩分布形状仍呈U形分布，但长桩所受最大弯矩大于短桩所受最大弯矩。在C类土层情况下，各桩最大弯矩呈一形分布；当基岩斜率为9：24时，对于桩端固接的情况，长桩的桩顶最大弯矩大于短桩的桩顶弯矩；对于桩端铰接的情况，则长桩的桩顶最大弯矩小于短桩的桩顶最大弯矩，随着基岩斜率减小，长短桩之间的最大桩顶弯矩差异减小。     

新型毛网卷捻兔毛梳理机

结合我国兔产业的状况,分析了目前加工兔毛产品所采用粗纺梳毛机的局限性、精纺梳毛机的问题及梳棉机对纤维的损伤性,从而提出研制新型兔毛梳理机的重要性.新型兔毛梳理机的设计主要结合兔毛纤维的特点以及解决其他梳理机加工兔毛存在的问题进行,对所研制生产出的毛网卷捻兔毛梳理机的结构及作用进行了分析,新型兔毛梳理机的主要特点是:用毛网卷捻器代替了一般梳理机从道夫上取下毛网的斩刀或剥棉罗拉,生产出的毛条为有捻毛条;该机对纤维损伤少,去粗、短、杂效果好;在梳前准备工序中不加和毛油,并可加工各品级的兔毛及其他类似的纤维.     

戊烷油和拔头油在不同裂解炉型上的裂解性能

对戊烷油和拨头油进行了中型模拟裂解评价.结果表明,芳烃装置的戊烷油在SRT-Ⅳ型炉石脑油工况下裂解,单程乙烯收率较低、丙烯收率高;重整的拔头油在CBL-Ⅳ型炉石脑油工况下裂解,单程乙烯和丙烯收率较高,是优质的裂解原料.     

盖板针布植针排列对梳理的影响

介绍了渐密型、弧形变化植针排列的盖板针布的梳理特点及效果,指出该品种是盖板针布的新型品种,也是其发展趋势。     

梳理用针布的技术进步及其配套应用

为了使针布三配套的选用更为合理以充分发挥其梳理效果,系统介绍了梳理用针布的发展历史,详细阐述了锡林、道夫、盖板针布的技术发展及具体参数的优化,以提高梳棉机梳理性能为首要条件,根据所纺原料、梳棉机的不同,结合实际举例,由浅入深地分析了锡林针布、道夫针布及活动盖板针布的技术进步.指出"矮、浅、尖、密、小"是针布发展的总趋势,并举例说明针布的三配套情况.     

MCBH型盖板针布的研制与使用

为了提高盖板针布的梳理效果,使梳棉机实现高产、优质、低耗,介绍了创新设计的MCBH型系列盖板针布,分析其植针排列形式、植针数学模型及植针工艺,重点对MCBH40、MCBH45、MCBH50、MCBH55盖板针布与其他类型盖板针布进行了详细的梳理试验对比。指出:MCBH型盖板针布克服了纤维进入端发生阻塞,使后区不能充分发挥分梳除杂作用的缺点;其优化设计的植针方式,具有横向针尖密度适中且纵向稀密渐变的特点,利于加强分梳和排除短绒、棉结,减少了纤维损伤及成纱棉结、纱疵、强力与单强不匀率;可配套优质、高产梳棉机。     

梳棉机活动盖板、固定盖板数的研究

通过在国产梳棉机上进行减少活动盖板,增加固定盖板的研究,说明在盖板总根数保持不变的条件下,将活动盖板减到17根左右,有利于成纱综合质量的提高。     

Re-utilization by perennial ryegrass (Lolium perenne L.) of labelled fertilizer sulphur incorporated in field-grown tops and roots of pasture plants added to soils

³⁵S-labelled gypsum fertilizer was incorporated under field conditions into pastures which were separated into white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) tops and roots. These were added to four soils from improved and unimproved pastures. The re-utilization of labelled fertilizer sulphur (S) was assessed under growth cabinet conditions (20°C day, 13°C night, daylength 16 h, light intensity 120–170 lx) by growing perennial ryegrass plants for 23 weeks.Mean recoveries of labelled fertilizer S varied from 7 to 20% depending on soil type, form amount and kind of plant residue added. Greater recovery was obtained from clover roots (9.5–16.2%) than grass roots (6.7–12.5%), and from grass tops (13.1–19.7%) than clover tops (9.7–17.9%). These results are related to contents of labelled S, total S, C/N, C/S and N/S ratios in plant residues which also accounted for their relative rates of decomposition. Ground (< 1 mm) and chopped (3 mm) roots increased labelled fertilizer S recovery by about 30% compared with whole roots. Additions of unlabelled fertilizer S influenced the recovery of labelled fertilizer S. This effect depends on the amounts of labelled grass roots and unlabelled fertilizer added.The significance of the findings is discussed with the aid of results from previous field experiments conducted on these soils.