魔芋葡甘聚糖基热可逆凝胶研究进展

魔芋葡甘聚糖(KGM)凝胶具有良好的生物降解性、生物相容性,以及环境敏感性、保水性、吸水性、抗菌性等特殊性能,被广泛应用于食品、医药、化工、功能材料领域等。然而,传统魔芋葡甘聚糖凝胶为单一组分凝胶,具有如低内聚性、较弱的机械性能和结构完整性、对加工和环境条件的稳定性不足、外观不可接受、保质期短以及明显的脱水收缩等局限性。魔芋葡甘聚糖基热可逆凝胶是将魔芋葡甘聚糖与其它多糖共混形成的,分子之间通过很强的协同相互作用形成稳定性更好、弹性更高的凝胶。本文从分子组装的角度综述了魔芋葡甘聚糖分别与卡拉胶、琼脂、纤维素衍生物、结冷胶、黄原胶和刺槐豆胶等多糖形成热可逆凝胶的协同增效作用,旨在为改善魔芋葡甘聚糖基热可逆凝胶的强度和体系的稳定性,扩大其应用范围提供参考。     

焦磷酸钠对魔芋葡甘聚糖酯化交联改性研究

焦磷酸钠对魔芋葡甘聚糖进行酯化交联改性,实验结果表明:反应最佳条件为焦磷酸钠∶魔芋葡甘聚糖=1∶8(w/w)、pH3、温度50℃、时间2h。改性KGM溶胶透明度、黏度、冻融稳定性及抗菌性明显改善,改性KGM膜耐洗刷性比未改性KGM膜明显增强。     

化学改性魔芋葡甘聚糖成膜性能的研究进展

魔芋葡甘聚糖(KonjacGlucomannan,简称KGM),是从魔芋块茎中分离、提取的一种天然复合多糖,具有亲水性、凝胶性、成膜性、抗菌性、可食用性等多种特征,在食品、医药、化工及生物领域应用广泛.简要论述魔芋葡甘聚糖的结构和理化特性,并综合介绍魔芋葡甘聚糖的化学改性研究进展,分析概括化学改性对魔芋葡甘聚糖成膜性能的改善作用.以期为魔芋葡甘聚糖膜的进一步研究提供理论基础,扩大它的应用范围,从而促进魔芋资源的开发.     

γ-射线辐照对魔芋葡甘聚糖结构的影响研究

采用1～8kGy的辐照剂量处理魔芋葡甘聚糖(KGM),运用紫外光谱、红外光谱、X-衍射、核磁共振等手段对魔芋葡甘聚糖的化学结构进行分析.研究表明辐照处理后引起KGM长链分子上糖苷键的断裂,黏度降低,但仍是吡喃己糖,也没有新的基团产生,仅引起羰基的增加和羟基氢的减少;无定型结构(α型)没有发生明显变化,但其峰值增高,面间距随辐照剂量的增大而增大.     

魔芋葡甘聚糖拓扑链对茶多酚的稳定性机理研究

为解决茶多酚(tea polyphenols,TP)不稳定、易被氧化的难题,采用直流电的方法制备了魔芋葡甘聚糖(konjac glucomannan,KGM)复合凝胶,在电场力的作用下实现了KGM拓扑链对TP活性的保护,以同等条件下的KGM-TP溶胶作为对照,着重研究了KGM-TP凝胶的微结构、热稳定性能,KGM-TP凝胶对于TP的保护与释放程度,分析了维系TP稳定的作用力,揭示了稳定化可能的形成机理。结果表明,在外加电场作用下,KGM链先通过分子内、分子间氢键作用力形成环状拓扑结构,再以氢键作用力的形式将TP分子保护起来,经KGM拓扑链包裹后的TP分子其O_2~-·清除力、DPPH·清除力明显强于同等条件下的KGM-TP溶胶。KGM拓扑链对TP不但可较好地保护而且释放程度高。     

三聚磷酸钠对魔芋葡甘聚糖酯化交联改性研究

三聚磷酸钠对魔芋葡甘聚糖进行酯化交联改性。实验结果表明,反应最佳条件为三聚磷酸钠∶魔芋葡甘聚糖=1∶9(W/W),反应pH为2,反应温度60℃,反应时间2h。改性KGM透明度、粘度、冻融稳定性均比未改性KGM明显改善,并具有一定的耐酸、耐高温能力,且有相当的抑菌效果。     

魔芋葡甘聚糖功能特性研究及其在食品工业中的应用

魔芋葡甘聚糖(KGM)是一种天然的优异膳食纤维,本文综述了魔芋葡甘聚糖的功能特性以及魔芋葡甘聚糖在食品工业中的应用概况,并对其发展前景进行了展望。     

硫酸酯化魔芋葡甘聚糖的制备及其应用研究

目的制备硫酸酯化魔芋葡甘聚糖(sulfated konjac glucomannan,SKGM)并研究其与大分子黄原胶的复配作用机制。方法用市售魔芋精粉为原料,采用创新的乙醇-超滤沉淀法获得高纯度的魔芋葡甘聚糖(konjac glucomannan,KGM),在氯磺酸的作用下制备出硫酸酯化魔芋葡甘聚糖,以粘度为指标,分析讨论SKGM与大分子黄原胶(xanthan gum,XG)的作用机制。结果制备的魔芋葡甘聚糖冻干粉纯度为98.61%,此时粘均分子量179万,粘度870 mpa/s;合成硫酸酯化魔芋葡甘聚糖最佳反应条件是时间3 h,温度为70℃,氯磺酸6 m L,通过计算得知取代度为1.053。硫酸酯化魔芋葡甘聚糖和黄原胶复配物因为氢键作用使得粘度显著增加。结论该研究获得一种精制高粘度魔芋葡甘聚糖及其酯化产物的方法,并得到其酯化产物SKGM和XG的复配机制。     

魔芋葡甘聚糖凝胶研究进展及其问题

魔芋葡甘聚糖是魔芋的主要功能活性成分,因其特殊的结构而具有特殊的性能,已成为多糖研究领域的热点之一.本文综述了魔芋葡甘聚糖3种特殊凝胶行为及其研究中存在的问题,并对研究方向进行展望,为KGM凝胶研究提供理论基础和科学依据.     

魔芋葡甘聚糖酯化交联改性研究

三偏磷酸钠为魔芋葡甘聚糖进行酯化交联改性。结果表明，反应最佳条件为三偏磷酸钠；魔芋葡甘聚糖=1：10(w／w)，反应PH为2，反应温度50℃，反应时间2h。改性KGM透明度、粘度、冻融稳定性均比未改性KGM明显改善，并具有一定的耐酸耐高温能力，且有相当的抑菌效果。     

模块化机械传动系统的开发

介绍了模块化机械传动系统的总体设计思路。系统分为4级应用模块,并用Visual Basic 6.0,Visual FoxPro 6.0和Visual LISP协同开发。各模块以Windows和AutoCAD为运行支持系统,在接口程序的控制下,自动运行和传递数据。文中着重介绍一级应用模块的程序接口设计技术。     

茧丝粘弹性及其对丝质的影响

从高分子物质的粘弹性建立茧丝纤维的四要素力学模型,讨论茧丝的粘弹性特征。通过有关理论和实验,分析制丝工程中张力、温湿度对丝质的影响。     

抗振可靠性设计

运用常规振动理论和可靠性相干理论．建立了抗振可靠性设计理论．提出了抗共振可靠度,刚度可靠度，抗振可靠度等概念．建立了它们的数学模型，并用数值计算和图表分析来描述抗共振可靠度Rn在不同频率变异系数Vwc、Vw下对频率比的变化规律。一般机械设计只需满足抗共振可靠性，精密机械设计则需满足抗共振可靠性和刚度可靠性。最后用两个算例加以了验证。     

环保型水溶性酚醛树脂增强滤纸在机油中的介质相容性

以一种水溶性酚醛树脂为研究对象,对其浸渍滤纸在机油中的力学性能保持率及孔结构的变化进行了研究。研究结果表明：与苯丙乳液相比,浸渍滤纸表现出优异的耐油性能,在135℃机油介质中,增强滤纸具有较好的尺寸稳定性,浸泡5d后抗张强度和挺度保持率均在90%以上,耐破度保持率较低,而孔径大小随着浸泡时间变长呈现出逐渐增大的趋势,但总体变化不很显著。     

Mechanical Models of Compression and Impact on Fresh Fruits

Well‐designed and well‐operated postharvest mechanical handling processes are vital if fresh fruits are to enter markets with minimal damage. The susceptibility of fruit to quality loss during handling is largely determined by mechanical contact and damage. This article reviews current understanding concerning the effect of impact and other mechanical contacts on fruits. It also discusses the major mechanical models that represent the interaction between fruits or a fruit and a surface. In total, 25 mechanical models associated with compression and impact behaviors of fresh fruits, mainly characterizing such behavior between 2 deformable spherical bodies and between a deformable spherical body and a rigid plate are reviewed. Finally, possible future research directions are discussed. The main challenge in fruit handling is to recognize and prevent microscopic damage to fruits, especially internal tissue/cell damage and microcracks resulting from multiple/repetitive impacts and compressions.     

A new closing Y‐shaped training system for grapevines

Background and Aims: Total leaf area and its distribution inside the canopy are known to influence the photosynthesis capacity as well as grape quality and health. The aim of this work was to evaluate the effectiveness of a simple and innovative training system characterised by an open canopy called ‘SAYM’ (a closing Y‐shaped training system derived from the spur‐pruned single cordon and trained to an inclined shoot‐positioned trellis type) as well as the possibility of using traditional machines during harvesting and pruning after closing the structure just before grape harvesting. Methods and Results: The SAYM was applied on eight rows of 80 vines from an experimental Sangiovese vineyard and compared to vertically shoot‐positioned (VSP) trellis type during the 2004–2008 seasons. In comparison to VSP vines, the SAYM was able to reduce the incidence of botrytis rot and improve grape and wine quality (alcohol, anthocyanins, phenolics, tannins and colour intensity), while maintaining an adequate yield (about 13 t/ha) without significantly increasing the management operations of the vineyard. Conclusions: The SAYM was able to bring together economically and easily the advantages guaranteed by training systems characterised by horizontally divided canopy with the limitation of production costs by the use of traditional mechanical harvesters and pruners. Significance of the Study: SAYM can be proposed as a functional training system able to improve grape and wine quality, which is easy and inexpensive to manage.     

水力碎浆机密封的改进

对现有老式水力碎浆机密封进行改进,重新增加一个机械密封座,变盘根密封为机械密封,使其免维护。     

浅谈硅藻土过滤机在豉香型白酒的应用与比较

酒厂的原酒都带有不应含的机械杂质。机械杂质不仅影响白酒的透明度 ,也影响白酒的香和味和纯净性等。必须把它们尽可能多地从白酒中除去。豉香白酒经硅藻土机过滤后 ,酒的理化、口感、香味损失甚微 ,保留了原酒的风味     

过氧化物漂白机械浆过程中用氢氧化镁代替氢氧化钠以降低草酸钙结垢

报导了在过氧化物漂白机械浆过程中用Mg(OH)2代替部分NaOH可以降低草酸钙结垢,漂白过程中用Mg(OH)2代替30%~50%NaOH产生的沉淀草酸钙量可忽略不计,与NaOH基过氧化物漂白方法比较还可提高纸浆白度。添加MgSO4(用量较大,大于1%)到过氧化物漂后段,虽然也能降低沉淀碳酸钙量,但是,这种解决草酸钙结垢方法没有用Mg(OH)2代替部分NaOH那样有效。     

Thermal and Mechanical Behavior of the Coir Powder Filled Polyester Micro-Composites

ABSTRACT

Reinforcement of micro- or nano-fillers is the new key technique to enhance the mechanical properties of polymers. The present work pertaining to the thermo-mechanical behavior of micron range coir filler reinforced polyester matrix composites. The polyester micro-composites are manufactured by hand lay-up method in which the reinforcement is coir micro-fillers, which are uniformly dispersed in the polyester matrix. The following testing and characterizations were performed to predict the thermo-mechanical behavior of the micro-composites and pristine polymer: tensile and flexural tests, Dynamic Mechanical Analysis (DMA), and Field Emission Scanning Electron Microscopy (FESEM). The mechanical properties of micro-composites were attained highest when the filler reinforcements were maximum. Dynamic light scattering (DLS) particle size analysis shown the size distribution of coir micro-particles and the avg. size of coir micro-particles was 0.255 µm.