糖液浓度检测仪的设计与研究

针对制糖生产过程中目前所采用的离线检测方法,实时性难以保证、生产效率受到制约等问题,对糖液浓度的在线检测技术展开研究.采用光学法实现对糖液浓度的测量,通过引入光电传感器,把光在糖液的传播过程中能量变化转化为电压信号,实验结果表明本设计原理可行,可为进一步深入研究提供理论依据.     

提高CCD糖液浓度测量系统精度的方法

为了实现糖液浓度的在线精密测量,在分析CCD测量原理的基础上,开发了基于ARM的糖液浓度测量系统,并分析了测量系统误差及对精度的影响;通过研究CCD信号边缘梯度特性,应用多项式插值的亚像素边缘检测算法提高了像素定位精度。实验结果表明,与传统的折光仪相比,该系统具有较高的分辨率和测量精度。     

Different strategies for selective monoacylation of hexoaldoses in acetone

Experimental protocols for the selective production of 6-O-acylhexoaldose emulsifiers from precursor sugars (mannose, glucose, and galactose) and corresponding fatty acids are compared. The protocols employ an immobilized Candida antarctica lipase in a solvent (acetone) which is both easily eliminated and accepted by the European Economic Community for use as an extraction solvent in the manufacture of foods and/or food additives. This comparative study provides guidelines for selection of appropriate conditions for quantitative monoacylation of aldoses in acetone, on the basis of the solubilities of the precursor sugar and the monoester in acetone at different temperatures. Although relatively low temperatures (<40°C) favor precipitation of glucose monoesters, higher temperatures (e.g., 55°C) should be used to increase solubility of mannose and thus selectivity of the reaction leading to the mannose ester. Galactose is transformed with poor selectivity to the desired monoester by these procedures. Factors affecting the viability of these synthetic reactions in acetone are also discussed.     

Synthesis and characterization of maltose fatty acid monoesters as biosurfactants

Maltose long-chain fatty acid esters (MFAE), esterified at the 6 and 6′ position, were synthesized with stearic, palmitic, myristic, and oleic groups. Synthesis yields were 15–20% based on initial maltose present, and structural confirmation was obtained using plasma desorption mass spectrometry and nuclear magnetic resonance spectroscopy. These surfactants have surface tensions in the range of 34–36 dyn/cm at their critical micelle concentrations (CMC) of approximately 10⁻⁵–10⁻⁶ mol/L. The increased chain lengths have a marked effect, reducing CMC values for MFAE by approximately three orders of magnitude over similar carbohydrate-based dodecyl chain sources. Within chain lengths between 14 and 18 carbons, the rate of change in CMC is significant and decreases with increasing chain length for MFAE. The melting points of MFAE are approximately 40°C, and the heat capacities range from 1.6 to 1.9 J/g·K. These numbers are comparable to those of sucrose esters, indicating their applicability in similar uses. However, because MFAE, unlike sucrose, possess an anomeric carbohydrate carbon position, these surfactants maintain their reducing nature and are susceptible to further derivatization. They are also synthesized from renewable, economical carbohydrates and lipids and may provide an excellent alternative to pertrochemical-derived products.     

Analysis of Flax Fiber Cell-Wall Non-Cellulosic Polysaccharides Under Different Weather Conditions (Marylin Variety)

The cell-wall composition has been analyzed for 13 batches of flax fibers grown over 3 years under 3 different weather conditions including a ‘normal one, a harsh drought and a rainy weather. It was found that both stresses, drought and excess of rain induced a decrease of uronic acid in the matrix and an increase of the structuring pectins. Besides, a drought led to an increase of hemicellulose polysaccharides (+24%) whereas an excess of rainfall caused a rise in the amount of so-called structuring pectins (+67%). As the fiber’s mechanical properties remained the same over the years, it was assumed that the cell-wall composition was modified to preserve the mechanical role of the fiber in the stem.     

掺杂离子的种类对介孔La0.6A0.4NiO3钙钛矿催化剂的结构与催化活性的影响

以十六烷基三甲基溴化铵（CTAB）为模板剂,用共沉淀法分别制备了介孔La_0.6A_0.4NiO₃（A=Ce、Sr、Y、Nd、Pr）钙钛矿复合氧化物,用XRD、SEM、FTIR、BET和程序升温技术等对复合氧化物的晶相结构、表面形貌、表面积、孔径分布及表面性能等进行了表征,同时在蔗渣高压液化反应中探讨了A位离子掺杂种类对介孔La_0.6A_0.4NiO₃催化活性和液化产物分布及液化油含量的影响。结果表明,掺杂的A位离子均能进行不同程度的同晶取代,其中掺杂的Pr³⁺能较好的与La³⁺发生同晶取代,且具有较大的比表面积和孔径分布,表面存在较强的氧物种传导性和碱性中心,在蔗渣高压液化反应中具有较高的液化油产率和较低的残渣率,生物质油的主要成分为乙酰柠檬酸三丁酯、柠檬酸三正丁酯、对乙基苯酚、6-乙基-3-肽酸酯,有利于提高油品的质量。     

射线传感器在蔗丝厚度自动调节系统中的应用

介绍了制糖企业甘蔗丝均衡传输自动调节系统的基本工作原理。给出了系统的硬件组成和控制软件主程序的流程图,系统以微机为控制中心,利用射线传感器检测蔗层厚度,通过控制输蔗机的速度实现了蔗丝流量均衡的自动调节,并利用微机监控程序完成了输蔗的计量和控制参数的在线设置。系统运行结果表明,其动态计量误差≤1%。     

甜高粱制取燃料乙醇产业初步分析

环境、能源和农业是近期国家重点考虑的问题,甜高粱制取燃料乙醇产业是综合解决上述问题的有效途径之一。从产业发展所需的资源、技术、市场、政策等方面进行了分析,并对未来产业发展的方向与措施阐述了自己的观点和建议。     

利用傅立叶变换简化苹果糖度的预测模型的研究

本文通过离散傅立叶变化,将苹果光谱信号转换为一系列的傅立叶系数。实验表明运用较少的傅立叶系数(15个)建立苹果糖度的PLS和PCR模型的效果与原始光谱(88个变量)建立的PLS模型的效果基本一致。这可以表明选择前若干个傅立叶系数建模,可以包含原光谱图的绝大部分信息。这样既可以较好的压缩图谱,减少计算量,同时也可以达到定量分析的要求。