Optimisation of enzymatic hydrolysis for concentration of squalene in palm fatty acid distillate

BACKGROUND: Squalene was concentrated from palm fatty acid distillate (PFAD) in this study using commercial immobilised Candida antarctica lipase (Novozyme 435^®). The PFAD was neutralised (NPFAD) using an alkali to liberate the free fatty acids and then hydrolysed at 65 ± 1 °C. The enzymatic hydrolysis on NPFAD was optimised using response surface methodology (RSM) before being neutralised again to obtain a concentrated squalene fraction. RESULTS: A five‐level, three‐factor central composite rotatable design was adopted to evaluate the effects of the enzymatic hydrolysis parameters reaction time (4–12 h), water content (50–70% w/w) and enzyme concentration (1.5–3.5% w/w) on the percentage yield of squalene concentration. The optimal reaction parameters for maximum yield of squalene concentration were identified from the respective contour plots. The optimal enzymatic hydrolysis conditions were a reaction time of 7.05 h, a water content of 61.40% w/w and an enzyme concentration of 2.23% w/w. CONCLUSION: RSM was used to determine the optimal conditions for enzymatic hydrolysis of NPFAD with C. antarctica lipase for maximum recovery of squalene which could be implemented on an industrial scale. Copyright © 2008 Society of Chemical Industry     

Equivalent a posteriori error estimates for elliptic optimal control problems with L1-control cost

An elliptic optimal control problem involving the $L^1$ norm of the control in the cost functional is considered in this paper. We use the full discretization and the variational discretization to approximate the control problem and the efficient and reliable a posteriori error estimates are obtained for the two cases. For the variational discretization, we also analyze the convergence of adaptive finite element methods. In the end, some examples are provided to validate our analysis.     

粉喷桩单桩竖向抗压极限承载力预测方法

根据粉喷桩单桩静载试验所得荷载-沉降曲线对粉喷桩的极限荷载的预测方法进行了探讨,分别按照抛物线法、双曲线法和灰色理论预测方法对粉喷桩极限荷载进行了预测。结果表明:灰色理论预测值与另两种方法的预测值相比要小些,偏于安全。另外,也讨论了各种预测方法的适用性与应用条件。其方法和成果可供相同工程参考和利用。     

莫来石结合碳化硅高温吸热陶瓷抗氧化性能的研究

以碳化硅及合成莫来石微粉为主要原料,制备了用于非真空太阳能吸热管的莫来石结合碳化硅高温陶瓷涂层。针对碳化硅基材料高温氧化问题,测定了样品的烧成增重率及亮度并结合XRD、SEM研究了莫来石结合碳化硅陶瓷的抗氧化性能。结果表明,莫来石添加量为20%,经1 380℃烧成样品的抗氧化性最好,其增重率为7.49%,亮度值为46.61。XRD分析烧结体主晶相为碳化硅(α-SiC)和莫来石(3Al2O3.2SiO2),并含有少量的方石英(SiO2),莫来石作为结合相在碳化硅晶粒周围形成"骨架",与SiO2玻璃相形成三围的网状保护层包裹在碳化硅表面,阻止碳化硅氧化。     

重力式加筋土挡墙设计参数的影响分析

重力式加筋土挡墙是将传统重力挡墙和普通加筋土挡墙相结合的一种新型挡墙。采用FLAC程序,模拟先浇筑重力挡墙,后填筑墙后加筋土的施工顺序,在已完成一个典型重力式加筋土挡墙从墙后填土到墙顶和墙顶堆载完成以后两个阶段数值模拟,掌握其工作性状的基础上,进一步对重力挡墙刚度、墙后填土性质、加筋土工格栅性质、加筋长度和间距等主要影响因素进行数值模拟分析,为设计参数的合理选择提供依据。     

超高层建筑沉降后浇带留置时间研究与工程应用

为解决沉降后浇带的留置时间与工期的矛盾,以青岛市"创业中心"为例,结合沉降计算、沉降预测和有限元软件ABAQUS分析结果,对沉降后浇带的留置时间或取消提供指导.     

Evaluation across and within collaborative manufacturing networks: a comparison of manufacturers’ interactions and attributes

Evaluation on collaborative manufacturing network (CMN) structure characteristics has important implications for network operations such as production decision-making, product recovery, creating consensus. Several recent studies suggest that augmenting network structure with nodes’ attributes can provide a more fine-grained understanding of the network. However, there have been few studies to provide a systematic understanding of these effects in a CMN at scale. This gap is bridged using an industrial printing machinery CMN data-set collected on a web-based producing and outsourcing service platform. Novel phenomena with respect to both interaction and attribute metrics across and within the CMNs are observed. Moreover, although many studies employ either interaction or attribute data to study the relative roles of manufacturers in a CMN, relatively little is known about the relationship between these two types of data. This study explores this relationship by comparing two defined metrics (i.e. relational capability and node capability), which evaluate the manufacturers’ interactions and attributes, respectively. We examine to what extent the two metrics of manufacturers correlate with each other, and how possible dissimilarities and similarities can be explained based on the collected industrial CMN data-set. The insights thereby provide a better basis for efficient operations decision-making in CMN.     

A new method for heat transfer and fluid flow performance simulation of plate heat exchangers

Successful numerical simulation on heat transfer and fluid flow performances of plate heat exchangers is vital. Their complex structures often make the numerical calculation quite difficult and time-consuming. Conclusions drawn by the present work are promising for greatly simplifying the simulation. Different types of plates consisting of different numbers of periods are analyzed and it is concluded that the Nusselt number remains constant for different periods of different plates under different inlet velocities. The central friction coefficients behave the same as Nusselt number. For the first and last periods, the respective friction coefficient also remains for different plates. A small plate fraction with four periods is enough for performance prediction of any-sized plates.     

涤纶毛条生产中毛粒的形成原因及其控制措施

讨论了涤纶毛条生产过程中纺丝、拉伸、卷曲、制条等工艺参数及设备条件对毛粒的影响。为了减少毛粒,采用了合理的纺丝和制条工艺,并对后纺设备进行适当改造。涤纶毛条中的毛粒得到了有效控制,从而生产出优质涤纶毛条产品。