Prehydrolysis of xylan in culm of Sasa kurilensis with dilute sulphuric acid

To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa kurilensis was hydrolysed with dilute sulphuric acid. A fermentable substrate with a relatively high xylose concentration (21.9?g?L^?1) was obtained by hydrolysis with 2% sulphuric acid with a liquid to solid ratio of 10?:?1 at 121°C for 1?h. During hydrolysis at elevated temperatures, some undesirable byproducts were also generated, such as degradation products of solubilized sugars and lignin, which are potential inhibitors of microbial metabolism. These compounds were successfully removed from the hydrolysate by treatment with a commercially available activated charcoal (30?g?L^?1 dose).     

Gaseous phase hydrogen storage and electrochemical properties of Zr8Ni21, Zr7Ni10, Zr9Ni11, and ZrNi metal hydride alloys

A systematic study of four important non-Laves phase alloys, Zr₈Ni₂₁, Zr₇Ni₁₀, Zr₉Ni₁₁, and ZrNi, commonly seen in the Zr-based AB₂ metal hydride alloys was presented. In order to investigate the synergetic effect between the major and secondary phases, an annealing treatment was used to change the abundances of various phases in the alloys. The structure, gaseous phase hydrogen storage, and electrochemical properties were obtained for each of the four alloy compositions before and after annealing, and the correlations among these properties were explored. Annealing generally suppressed secondary phases except for the case of Zr₉Ni₁₁, where its secondary ZrNi phase abundance increased. As the Zr/Ni ratio in the average composition increased, the maximum gaseous phase hydrogen storage capacity increased but maximized at Zr:Ni = 9:11. Comparing the properties before and after annealing, it was established that the change in phase distribution influenced the gaseous phase storage. Through the electrochemical measurements, it was found that the highest full discharge capacity was obtained at Zr:Ni = 7:10, which represents a compromise between the hydrogen desorption/discharge rate and the theoretical maximum gaseous phase hydrogen storage. As the Zr/Ni ratio increased, the high-rate dischargeability decreased, which followed the trend of the amount of metallic Ni in the surface oxide determined by magnetic susceptibility measurement. The synergetic effect was observed in the electrochemical environment by comparing the results before and after annealing. In general, annealing deteriorated and improved the electrochemical discharge capacity and high-rate dischargeability, respectively, due to the reduction in secondary phase abundance and consequent synergetic effect. Among all alloys investigated, the unannealed Zr₇Ni₁₀ demonstrated the best overall gaseous phase hydrogen storage and electrochemical capacity and could be considered as a candidate to replace the AB₅ and AB₂ metal hydride alloys in Ni/MH battery applications. Furthermore, the unannealed Zr₈Ni₂₁ showed a good balance between high-rate dischargeability and ease of formation.     

Study of deformation mechanism for linear low-density polyethylene

The deformation mechanism for linear low-density polythylene (LLDPE) has been studied by electron microscopy, infrared spectroscopy, and pulsed nuclear magnetic resonance. Morphologically, the lamellae in the polar region of a spherulite are aligned in parallel to the drawing direction and then unfolded into microfibrils with drawing. The lamellae in the equatorial region are curved, corrugated, and unfolded partially. Actually, microfibrils are formed with transformation of both lamellae and some amorphous molecules throughout the drawing. Restraint of molecular mobility for the amorphous region increases with drawing, but mobility for the immobile region (lamellae and microfibrils) remains constant. Orientation of the trans-methylene sequences in amorphous regions proceeds with extension. These results can explain the changes of the s-s curve behavior.     

利用Excel的自定义公式进行原料配料

利用Excel最简单的自定义公式功能,根据尝试拼凑法的原理来进行原料配料计算。详细介绍了其计算步骤以及利用Excel自定义公式计算的具体设置方法。一般试凑两、三次即可得到所需要的三率值控制目标值,此方法简便易懂。     

苯加氢工艺比较及设计应注意的一些问题

文章在研究苯加氢工艺特点的基础上,分析了苯加氢工程在设计中应注意的一些问题。主要包括:两种加氢工艺的比较,氢腐蚀及抗氢腐蚀钢的选择,H2S腐蚀及抗硫化氢腐蚀钢的选择,导热油系统施工时注意的问题,高压管道系统的选择。     

测量90oV型槽口宽度尺寸的简便方法

在机械加工过程中,每当遇到带90oV型槽的零件常使用卡板测量,但卡板测量只能作终检,不能控制某道工序中的加工余量.为了解决这一问题,我们采用圆柱棒和高度尺相结合的测量方法,如图所示.     

高层建筑管网集中试压工艺

从工程实践出发。针对高层建筑内部管道施工方法的复杂性，提出相应的措施，组织实施高层建筑管网集中试压。以期达到有序施工、有序试压、提高工效、节省资源的目的。     

包钢炼铁厂生产过程监控系统的设计与实现

包钢炼铁厂生产过程自动化已经广泛应用到烧结机、高炉生产的全过程.为了掌握全厂生产的动态信息,通过采集不同控制系统的实时数据,在局域网上发布,为生产技术人员提供生产现场的实时数据及统计分析信息.     

Artificial neural network ensemble-based land-cover classifiers using MODIS data

Terra and Aqua, two satellites launched by the NASA-centered International Earth Observing System project, house MODIS (moderate resolution imaging spectroradiometer) sensors. Moderate-resolution remote sensing allows the quantifying of land-surface type and extent, which can be used to monitor changes in land cover and land use for extended periods of time. In this article, we propose land-surface classification by applying an ensemble technique based on fault masking among individual classifiers in N-version programming. An N-version programming ensemble of artificial neural networks is created, in which the majority vote result is used to predict land-surface cover from MODIS data. It is shown by experiment that an N-version programming ensemble of neural networks greatly improves the classification error rate of land-cover type.