核子皮带秤在济钢集团总公司计量中的应用

本文介绍了核子皮带秤的特点、工作原理、组成及作用；说明了核子皮带秤在济钢的应用效果；同时指出了影响核子皮带秤计量精度的几个因素和消除这些因素所采取的措施。     

Enzymatic synthesis of monosaccharide fatty acid esters and their comparison with conventional products

5-O-Acyl-1,2-O-isopropylidene-D-xylofuranose and 6-O-acyl1,2∶3,4-di-O-isopropylidene-D-galactopyranose were enzymatically prepared from the corresponding monosaccharide acetals and commercial (crude) fatty acid mixtures. Subsequent acid-catalyzed hydrolysis of the isopropylidene group(s) gave monosaccharide esters with overall yields of 59–88%, where the monoester content was at least 80% (galactose oleate) and typically 90% for the other preparations. In contrast to sugar fatty acid esters prepared by conventional, high-temperature (trans)esterification, the enzymatically obtained monosaccharide esters contained no appreciable quantities of undersirable side products, and the only contaminants were monosaccharides and fatty acids.     

基于ANN的糖厂蒸发工段的建模

研究了人工神经网络技术在糖厂多效蒸发过程建模中应用的可行性,采用误差反向传播网络(BP网)建立了一效、二效汁汽压力P1、P2和出口糖浆的锤度C5之间的两输入单输出神经网络模型,借助MATLAB7.0加以实现。仿真试验证明了该模型的有效性,并为进一步实现多效蒸发过程的智能控制奠定了基础。     

Fermentation of cheese whey powder solution to ethanol in a packed‐column bioreactor: effects of feed sugar concentration

BACKGROUND: Cheese whey powder (CWP) is a concentrated source of lactose and other essential nutrients for ethanol fermentation. CWP solution containing different concentrations of total sugar was fermented to ethanol in an up‐flow packed‐column bioreactor (PCBR) at a constant hydraulic residence time (HRT) of 50 h. Total sugar concentration in the feed was varied between 50 and 200 g L^?1 and a pure culture of Kluyveromyces marxianus was used for ethanol fermentation of lactose. Variations of ethanol and sugar concentrations with the height of the column and with the feed sugar concentration were determined. RESULTS: Ethanol concentration increased and total sugar decreased with the column height for all feed sugar contents. The highest effluent ethanol concentration (22.5 g L^?1) and ethanol formation rate were obtained with feed sugar content of 100 g L^?1. Percentage sugar utilization decreased with increasing feed sugar content above 100 g L^?1 yielding lower ethanol contents in the effluent. The highest ethanol yield coefficient (0.52 gE g^?1S) was obtained with a feed sugar content of 50 g L^?1. Biomass concentration also decreased with column height, yielding low ethanol formation in the upper section of the column. CONCLUSION: The packed column bioreactor was found to be effective for ethanol fermentation from CWP solution. The optimum feed sugar content maximizing the effluent ethanol and the specific rate of ethanol formation was found to be 100 g L^?1. High sugar content above 100 g L^?1 resulted in low ethanol productivities due to high maintenance requirements. Copyright © 2008 Society of Chemical Industry     

用于兆拉德级的蔗糖溶液剂量计

蔗糖溶液受照射后,它的旋光度、酸度及光密度都发生了变化。这些变化量与吸收剂量都成比例关系。本工作研究了蔗糖溶液的这些特性和它作为兆拉德级化学剂量计的可能性。实验结果表明,在5×10~5-10~7rad剂量范围内,无论用上述哪一个指标,都可测量出溶液所受剂量。     

Optimality of the Münch mechanism for translocation of sugars in plants

Plants require effective vascular systems for the transport of water and dissolved molecules between distal regions. Their survival depends on the ability to transport sugars from the leaves where they are produced to sites of active growth; a flow driven, according to the Münch hypothesis, by osmotic gradients generated by differences in sugar concentration. The length scales over which sugars are produced (L_leaf) and over which they are transported (L_stem), as well as the radius r of the cylindrical phloem cells through which the transport takes place, vary among species over several orders of magnitude; a major unsettled question is whether the Münch transport mechanism is effective over this wide range of sizes. Optimization of translocation speed predicts a scaling relation between radius r and the characteristic lengths as r ∼ (L_leaf L_stem)^1/3. Direct measurements using novel in vivo techniques and biomimicking microfluidic devices support this scaling relation and provide the first quantitative support for a unified mechanism of sugar translocation in plants spanning several orders of magnitude in size. The existence of a general scaling law for phloem dimensions provides a new framework for investigating the physical principles governing the morphological diversity of plants.     

Effects of o-phenylenediamine on methylglyoxal generation from monosaccharide: Comment on “correlation of methylglyoxal with acrylamide formation in fructose/asparagine Maillard reaction model system”

Methylglyoxal (MG), a reactive carbonyl compound, has recently garnered much attention because of its ability to modify proteins over time and yield advanced glycation end products (AGEs) that are thought to contribute to the development of diabetes mellitus and its complications. In a recent paper published in Food Chemistry by Yuan et al. [Yuan, Y., Zhao, G. H., Hu, X. S., Wu, J. H., Liu, J., & Chen, F. (2007a). Correlation of methylglyoxal with acrylamide formation in fructose/asparagines Maillard reaction model system. Food Chemistry, 108(3), 885–890] authors showed a high correlation between methylglyoxal formation and acrylamide formation. However, in their study, model systems of aqueous fructose/asparagines (Fru/Asn) and fructose/asparagines/o-phenylenediamine (Fru/Asn/OPD) heating at 150 °C were used. The validity of these models relies on the assumption that OPD will only serve the role of a trapping agent for MG. In this short communication, we would like to call to attention that MG can also have a strong catalytic effect in the generation of MG from fructose. Therefore, it is concluded that the concentration of MG obtained in Fru/Asn/OPD model system cannot correspond to the total amount of MG formed by Maillard reaction of Fru and Asn as claimed by Yuan et al. [Yuan, Y., Zhao, G. H., Hu, X. S., Wu, J. H., Liu, J., & Chen, F. (2007a). Correlation of methylglyoxal with acrylamide formation in fructose/asparagines Maillard reaction model system. Food Chemistry, 108(3), 885–890, Yuan, Y., Zhao, G. H., Hu X. S., Wu, J. H., Liu, J., & Chen. F. (2007b). High correlation of methylglyoxal with acrylamide formation in glucose/asparagine Maillardreaction model. European Food Research and Technology. doi:10.1007/s00217-007-0658-0].     

氮素水平对甜菜主要营养的影响

甜菜植株含氮量与施氮量呈极显著正相关，生育中前期氮的分配以叶部为主，其后氮向根的分配率增加，但高氮处理到生育后期氮对叶部的分配率仍处于较高水平，不利于产量形成和糖分积累。甜菜植株磷、钾含量与施氮量呈极显著正相关，氮与磷、钾表现出明显的互作效应。     

糖厂降低吨糖耗蔗量的挖潜措施

首先论证了影响吨糖成本的关键环节，是吨糖耗蔗量。然后通过有关计算公式，算出大量数据的基础上分析了影响吨糖耗蔗的基本因素，最后提出了降低吨糖耗蔗量的参考措施