Research progress on hydrothermal dissolution and hydrolysis of lignocellulose and lignocellulosic waste

Ethanol production from lignocellulosic waste has attracted considerable attention because of its feasi- bility and the generation of valuable products. Previous studies have shown that pretreatment and hydrolysis are key processes for lignocellulose conversion. Hydrothermal process is a promising technique because of its efficiency to break down the lignocellulosic structures and produce fermentable hexoses. Most studies in this field have therefore focused on understanding these processes or optimizing the parameters, but commonly reported low yields of fermentable hexoses. The inability to produce high yields of fermentable hexoses is mainly attributed to inadequate information on the conversion mechanisms of lignocellulose, particularly the reaction rules of dissolu- tion, which is a limiting step in the entire conversion process. This paper critically reviewed the progress done in the research and development of the hydrothermal dissolution and hydrolysis of lignocellulose. Principles, processes, and related studies on separate dissolution and asynchronous hydrolysis of lignin, hemieellulose, and cellulose are presented. Potential research prospects are also suggested.     

自动变光面罩亟待成为中国焊工防护标配

本文阐述了电弧焊弧光所造成的危害种类及其严重程度,并围绕自动变光焊接面罩的基本结构、工作原理、性能指标、防护效果等,重点介绍了防治电弧焊弧光危害的这种专门利器,明确提出了应该让自动变光焊接面罩尽快成为中国焊工防护用具的标准配置的观点。     

WATERSHED CONFIGURATION AND GEOGRAPHIC INFORMATION SYSTEM PARAMETERIZATION FOR SPUR MODEL HYDROLOGIC SIMULATIONS1

ABSTRACT: A grid cell geographic information system (GIS) is used to parameterize SPUR, a quasi-physically based surface runoff model in which a watershed is configured as a set of stream segments and contributing areas. GIS analysis techniques produce various watershed configurations by progressive simplification of a stream network delineated from digital elevation models (DEM). We used three watershed configurations: ≥ 2nd, ≥ 4th, and ≥ 13th Shreve order networks, where the watershed contains 28, 15, and 1 channel segments with 66, 37, and 3 contributing areas, respectively. Watershed configuration controls simulated daily and monthly sums of runoff volumes. For the climatic and topographic setting in southeastern Arizona the ≥ 4th order configuration of the stream network and contributing areas produces results that are typically as good as the ≥ 2nd order network. However both are consistently better than the ≥ 13th order configuration. Due to the degree of parameterization in SPUR, model simulations cannot be significantly improved by increasing watershed configuration beyond the ≥ 4th order network. However, a range of Soil Conservation Service curve numbers derived from rainfall/runoff data can affect model simulations. Higher curve numbers yield better results for the ≥ 2nd order network while lower curve numbers yield better results for the ≥ 4th order network.     

GROUND-WATER TEMPERATURE FLUCTUATIONS AT LYONS FERRY FISH HATCHERY,WASHINGTON1

ABSTRACT: The well field serving the Lyons Ferry Fish Hatchery has experienced reduced water temperatures following continued, periodic withdrawal of large volumes of water. In January 1985, the well field temperature was 49°F, which is less than the optimal 52°F for raising salmon and steelhead trout. The aquifer supplying the hatchery is in hydraulic and thermal connection with the Snake River and a flooded embayment of the Palouse River. Ground-water temperatures in the well field cycle on an annual basis in response to changes in surface water temperature and pumping rate. Numerical simulation of the well field, using a simplified mixing cell model, demonstrates the coupling of well field hydraulics and aquifer thermal response. Alternative pumping schedules indicate that it is feasible to adjust ground-water pumping to effectively store heat in the aquifer during the summer months when surface water temperatures are elevated. Sensitivity analysis of this model indicated that the primary controls of the system's thermal response are the volume of the aquifer assumed to contribute to the well field and temperature of the overlying surface water body.     

负载型纳米Bi2WO6/AC的制备及在可见光下降解邻硝基苯酚

采用水热法在160℃条件下以活性炭(AC)为载体合成了光催化剂Bi2WO6/AC,用X射线衍射仪(XRD)、电子扫描电镜(SEM)对催化剂进行了表征.同时,以邻硝基苯酚为目标污染物,在可见光照射下,讨论了催化剂用量、溶液的pH、污染物初始浓度等因素对催化剂光催化活性的影响.结果表明,当[Bi2WO6/AC]=5 g·L-1、pH=5[邻硝基苯酚]0=100 mg·L-1时,催化剂可见光降解活性最好,60 min后邻硝基苯酚的降解率可达到99.81%.     

县级环境监测站能力配置和建设的探讨

环境监测站监测能力建设决定了监测站人员、仪器设备和实验室环境条件的配置,对监测站的建设具有着决定性的意义。监测能力配置的原则应该是既能满足环境例行监测的要求,又能很好地服务于当地社会经济发展需求,而且配置应该考虑人力物力和财力,经济合理。本文从环境例行监测、服务当地社会经济发展和应急预警监测三方面,以昆山市环境监测站为例,分析了县级环境监测站在监测能力配置上的不足和问题,并提出了相应的解决方案,为县级监测站能力建设提供一定的参考。     

装备快速封存技术中的传感器配置研究

以某型封存装甲装备为例,利用计算流体力学(CFD)技术,对封装装甲装备动态除湿过程中的装备内部温湿度场分布情况进行了仿真研究,结合装备封存技术的特殊要求提出了封存装备状态检测中传感器配置的原则和方法,并给出了装备快速封装技术中传感器配置的操作方法,实验表明该方法具有很强的操作性,为进一步深入研究快速封装技术奠定了基础.     

提升光电编码器湿热环境适应性方法研究

目的研究提升光电编码器湿热环境适应性的方法。方法对某型军用电子装备中,光电编码器湿热环境适应性低的原因进行分析,并制定相应的工艺改进方法。结果根据分析可知,潮气进入光电编码器内部和芯线接头处是造成故障率高的原因,拟定了相应的解决方法。由验证试验结果可知,实施工艺改进方法后,光电编码器内部和芯线接头处再无潮气进入。结论经过验证,改进的工艺方法非常有效,光电编码器在湿热环境下的适应能力得到了极大提高。     

可降解有机物湿解实验及产物分析

湿解是环境友好的新型有机废物处理工艺,湿解实验在反应温度450K,反应时间1h的工况下,对杂草和马粪进行湿解,并分析了两种物料的湿解产物。结果表明:杂草和马粪经湿解处理后,分别得到了18.8%和16.3%的原料转化率,有机质转化率均超过了95%,可为土壤提供丰富的有机质;两种湿解液中所含物质基本上均集中在166.7~428.9及1122~1622的两组质荷比范围内,湿解液呈弱酸性,其中奎尼酸、柠檬酸和L-苹果酸含量丰富。     

餐厨垃圾水热炭化产物分配规律及液固产物特性研究

以实采餐厨垃圾为对象,探究了3种反应强度("温和"180℃-1h、"中等"220℃-2h和"剧烈"260℃-4h)下餐厨垃圾水热炭化三相产物分配规律及液固产物特性.结果表明,反应强度显著影响产物分配.随反应强度提升,固相产物(水热炭)产率先上升后下降;液相产物(炭化液)产率先降低后趋于稳定;而气相产物产率持续上升.但无...