Stabilisation of the Fatty Acid Decarboxylase from Chlorella variabilis by Caprylic Acid

The fatty acid photodecarboxylase from Chlorella variabilis NC64 A (CvFAP) catalyses the light-dependent decarboxylation of fatty acids. Photoinactivation of CvFAP still represents one of the major limitations of this interesting enzyme en route to practical application. In this study we demonstrate that the photostability of CvFAP can easily be improved by the administration of medium-chain length carboxylic acids such as caprylic acid indicating that the best way of maintaining CvFAP stability is ‘to keep the enzyme busy’.     

Formative e-assessment: Practitioner cases

This paper reports on one aspect of the Joint Information Systems Committee (JISC)-funded project ‘Scoping a vision of formative e-assessment’, namely on cases of formative e-assessment developed iteratively with the UK education practitioner community. The project, which took place from June 2008 to January 2009, aimed to identify current theories and practices relating to formative assessment of learning where technologies play a key role. The project aimed to scope the ‘domain’ of formative e-assessment, by developing cases of practice and identifying key formative processes within them, which are affected by the use of technologies. From this analysis, patterns were extracted to inform future software design. A discussion of the key issues emerging from the review of the literature on formative e-assessment, a full account of the project methodology – the design pattern methodology – as well as a critical discussion of the findings – namely the patterns and the role of technology – are the focus of a separate paper (see Daly, Pachler, Mor, and Mellar (in press). This paper documents how cases of formative e-assessment were developed during the project by a collaborative methodology involving practitioners from a range of post-16 education contexts. The cases were analysed with reference to key theoretical perspectives on formative assessment, particularly the work of Black and Wiliam (2009). In addition, Laurillard’s Conversational Framework (2002, 2007) was used to locate practices of formative assessment within a wider concept of learning and teaching involving technologies, although a detailed discussion of the latter is not within the scope of this paper¹.     

Reduced complexity decoding of convolutional codes based on the M-algorithm and the minimal trellis

In this paper, we propose three new sub-optimum, reduced complexity decoding algorithms for convolutional codes. The algorithms are based on the minimal trellis representation for the convolutional code and on the M-algorithm. Since the minimal trellis has a periodically time-varying state profile, each algorithm has a different strategy to select the number of surviving states in each trellis depth. We analyse both the computational complexity, in terms of arithmetic operations, and the bit error rate performance of the proposed algorithms over the additive white Gaussian noise channel. Results demonstrate that considerable complexity reductions can be obtained at the cost of a small loss in the performance, as compared to the Viterbi decoder.     

适应交互智能产品设计需要的素质教育模式

埃因霍温科技大学工业设计系自建系以来就注重培养学生成长为交互智能产品、系统及相关服务的专业设计师.我系创立并实旋了一种新型的以能力素质为中心的教育模式.此模式包括素质架构及建立在这个架构上勤思求变的设计流程两个方面.这个教育模式注重学生学习的方法(目标,方式和原因),从多方面培养学生在新的知识时代成为能够在应对大量不断变化的信息中保持创造性和灵活性的设计师.     

Failure Analysis of Titanium-Based Dental Implant

Metallic materials designed for applications in orthopedic or dental surgical implants must show a group of properties, including biocompatibility, mechanical strength and resistance to degradation (by wear or corrosion) outstand. In order to assure that the properties are achieved, the implant materials must fulfill certain requirements, usually specified in standards. The standards also include chemical composition, microstructure and even macrographic aspects. The main aim of this work was to perform a failure analysis on a titanium-based dental implant and connect the possible causes of failure with the associated material requirements which were previously mentioned. Evaluation techniques included metallographic analysis by optical microscopy and fractographic analysis by scanning electron microscopy (SEM). The results of the examinations suggested that, in spite of their adequate microstructures, the implants fractured due to the overload generated by stress raisers which were found in the implants.     

Failure Analysis of Two Stainless Steel Based Components Used in an Oil Refinery

The petroleum industry has changed significantly over the past decades. For example, in Brazil, oil extraction under very deep sea water is growing very quickly. As a consequence, materials and components used for such applications must have properties required to withstand adverse conditions and ensure satisfactory performance and reliability in service. Nonetheless, components that normally fulfill these standard requirements can fail under severe service conditions such as high pressure and temperatures and high concentrations of H₂S and CO₂. Among the factors that can cause the premature failure in metallic components are the use of inadequate materials, the presence of defects that appeared during the production, and errors of project, assembly, or maintenance. Failure analysis allows the identification of causes and thus contributes to improvements in the operation and performance of similar equipment. In this work, light optical microscopy and scanning electron microscopy (SEM) were used to analyze the microstructure and fracture surface of two centrifugal pump shafts that failed during use in a Brazilian petroleum refinery. The results showed that one shaft, made of duplex stainless steel, failed by fatigue fracture, and the other, made of 316 austenitic stainless steel, experienced a similar fracture, which was promoted by the presence of nonmetallic inclusion particles.     

Nitrate accelerated corrosion of lead solder in potable water systems

Although nitrate is generally believed to have little effect on lead corrosion, bench-scale tests in this work revealed that increasing nitrate in the range of occurrence in potable water (0–10 mg/L N) can dramatically increase lead leaching from simulated soldered pipe joints. Lead in water created slightly increased galvanic currents between solder and copper pipe, but nitrate also altered the nature of the attack in a manner that caused solder particles to detach into the water. Chloramine decay and the associated conversion of ammonia to nitrate could create much higher lead contamination of potable water from solder in some cases.