Diastereo‐ and Enantioselective Direct Aldol Reactions in Aqueous Medium: A New Highly Efficient Proline‐Sugar Chimeric Catalyst

A new synthetic catalyst, capable of acting like an enzyme in the accomplishment of direct aldol reactions, is presented. Excellent results, in terms of chemical yields and diastereo‐/enantiomeric ratios, are reported for the catalyzed additions of cyclohexanone to variously substituted benzaldehydes.     

The bullwhip effect on product orders and inventory: a perspective of demand forecasting techniques

Demand forecasting is one of the key causes of the bullwhip effect on product orders. Although this aspect of order oscillation is not ignored, the current study focuses on another critical aspect of oscillation: the bullwhip effect on inventory, i.e. the net inventory variance amplification. In particular, this paper studies a two-level supply chain in which the demand is price sensitive, while the price follows a first-order autoregressive pricing process. We derive the analytical expressions of the bullwhip effect on product orders and inventory using minimum mean-squared error, moving average and exponential smoothing forecasting techniques. We also propose the conditions under which the three forecasting techniques would be chosen by the retailer to minimise the sum of the bullwhip effect on product orders and inventory under different weightings. These observations are used to develop managerial insights regarding choosing an appropriate forecasting technique after considering certain distinct characteristics of the product.     

Measurement of meat color using a computer vision system

The limits of the colorimeter and a technique of image analysis in evaluating the color of beef, pork, and chicken were investigated. The Minolta CR-400 colorimeter and a computer vision system (CVS) were employed to measure colorimetric characteristics. To evaluate the chromatic fidelity of the image of the sample displayed on the monitor, a similarity test was carried out using a trained panel. The panelists found the digital images of the samples visualized on the monitor very similar to the actual ones (P < 0.001). During the first similarity test the panelists observed at the same time both the actual meat sample and the sample image on the monitor in order to evaluate the similarity between them (test A). Moreover, the panelists were asked to evaluate the similarity between two colors, both generated by the software Adobe Photoshop CS3 one using the L*, a* and b* values read by the colorimeter and the other obtained using the CVS (test B); which of the two colors was more similar to the sample visualized on the monitor was also assessed (test C). The panelists found the digital images very similar to the actual samples (P < 0.001). As to the similarity (test B) between the CVS- and colorimeter-based colors the panelists found significant differences between them (P < 0.001). Test C showed that the color of the sample on the monitor was more similar to the CVS generated color than to the colorimeter generated color. The differences between the values of the L*, a*, b*, hue angle and chroma obtained with the CVS and the colorimeter were statistically significant (P < 0.05–0.001). These results showed that the colorimeter did not generate coordinates corresponding to the true color of meat. Instead, the CVS method seemed to give valid measurements that reproduced a color very similar to the real one.     

SiO2 nanoparticles biocompatibility and their potential for gene delivery and silencing

Despite the extensive use of silica nanoparticles (SiO(2)NPs) in many fields, the results about their potential toxicity are still controversial. In this work, we have performed a systematic in vitro study to assess the biological impact of SiO(2)NPs, by investigating 3 different sizes (25, 60 and 115 nm) and 2 surface charges (positive and negative) of the nanoparticles in 5 cell lines (3 in adherence and 2 in suspension). We analyzed the cellular uptake and distribution of the NPs along with their possible effects on cell viability, membrane integrity and generation of reactive oxygen species (ROS). Experimental results show that all the investigated SiO(2)NPs do not induce detectable cytotoxic effects (up to 2.5 nM concentration) in all cell lines, and that cellular uptake is mediated by an endocytic process strongly dependent on the particle size and independent of its original surface charge, due to protein corona effects. Once having assessed the biocompatibility of SiO(2)NPs, we have evaluated their potential in gene delivery, showing their ability to silence specific protein expression. The results of this work indicate that monodisperse and stable SiO(2)NPs are not toxic, revealing their promising potential in various biomedical applications.     

并行工程中基于信任度的知识(信息)协同问题研究

探讨了并行工程中知识协同处理的７元组描述模式，并在此基础上提出了基于信任度和基于模糊集理论的两种不同类型的知识协同处理算法。算法体现了权威性和民主性相结合的原则。并提出了知识协同处理的灵敏度问题，对提出的算法的灵敏度进行了理论上的分析。通过实例分析，算法具有较强的实用性和良好的效果，易为各个知识源所接受。     

Microstructural evolution of nickel nanoparticle catalysts supported on gadolinium-doped ceria during autothermal reforming of iso-octane

The microstructure and composition of a nanoparticle Ni catalyst supported on gadolinium-doped ceria (Ce_1−xGd_xO_(4−x)/2) were studied using transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The support of the fresh catalyst exhibits a homogenous aggregation of crystalline grains, with sizes ranging between 20 nm and 50 nm. The crystalline structure of the fresh catalyst support is of the CeO₂ phase, in which gadolinium atoms exist in a solid solution of CeO₂. Nickel in the fresh catalyst is highly dispersed and forms granular crystals that are 5–30 nm in size on the surface of the ceria support. The support of the used catalyst exhibits a bimodal distribution of grains in which smaller grains have similar structure and morphology as those in the fresh catalyst, while the larger sized grains appear dull and exhibit nonfaceted crystal morphology resulting either from the sintering of a number of CeO₂ grains or by the occupation of highly defective crystals of Ce₂O₃ and CeO phases. A thin amorphous layer of carbon also covers most of the larger grains in the used catalyst. The Ni particles could not be imaged by TEM in the used catalyst, but energy dispersive x-ray spectroscopy (EDX) detected their presence. The XPS analysis of the catalyst samples suggests the participation of lattice O atoms from the ceria support in the catalytic reaction. The XPS data also show the presence of carbonate species and a higher hydrocarbon concentration in the used catalyst.     

Finding unusual medical time-series subsequences: algorithms and applications.

In this work, we introduce the new problem of finding time series discords. Time series discords are subsequences of longer time series that are maximally different to all the rest of the time series subsequences. They thus capture the sense of the most unusual subsequence within a time series. While discords have many uses for data mining, they are particularly attractive as anomaly detectors because they only require one intuitive parameter (the length of the subsequence), unlike most anomaly detection algorithms that typically require many parameters. While the brute force algorithm to discover time series discords is quadratic in the length of the time series, we show a simple algorithm that is three to four orders of magnitude faster than brute force, while guaranteed to produce identical results. We evaluate our work with a comprehensive set of experiments on electrocardiograms and other medical datasets.     

Biodiesel stability under commercial storage conditions over one year

Results obtained from a long‐term storage study using eleven different biodiesel samples are presented. Samples prepared from several feedstocks using different manufacturing technologies (with or without biodiesel distillation), some containing an antioxidant additive, were stored in 200 l drums. These were periodically monitored during the complete storage period by analysis of fifteen different properties. Several properties do not show any significant change during storage, while others such as viscosity, peroxide value and more dramatically, Rancimat Induction Period demonstrated changes related to the nature of the starting product. A parallel test, carried out in simulated wrong storage conditions (occasional shaking promoting intimate contact between biodiesel and air oxygen) lead to some strong changes in biodiesel composition and can be used as a guide for devising biodiesel production set‐up, storage and distribution chain.     

以可持续规划缔造公营房屋优质居住环境:香港房屋委员会的经验

香港房屋委员会(香港房委会)是一个法定机构,负责为无力负担私营楼宇的人士提供可负担的优质居所.在香港的700万人口中,大约30％的市民居住在公营租住房屋中,另有15％的市民居住在房委会提供的资助出售单位中.目前,我们的公共租住屋邨内共有约72万个居住单位.为满足公营房屋日益增长的需求,按照现时逐年延展的五年计划,我们平均每年新建1.5万套租住单位.面对严峻的土地、社区和环境的限制,我们竭力实现公营房屋建设量的目标,同时我们从未放弃公营房屋既定的可持续发展的质量指标,包括在和谐社区中提供安全、绿色和健康宜居的家园,开发实而不华、环境友好及以人为本的屋邨.过去十年间,我们在规划设计阶段逐步开发及实施了一系列新措施和工具,为居民营造优质居住环境.这些实践经验值得在规划行业内总结推广,从而鼓励后续更多改善.本文介绍香港房委会在可行性研究、总体布局规划、方案设计等阶段推行的新措施,涵盖了房委会使用的可持续规划设计方法,以应对香港公众对公营房屋优质居住环境日益提升的期望.同时,香港房委会亦与地方社区紧密合作,共同营造和谐社会氛围.总之,公营房屋已成为香港繁荣稳定的基石,以及超过半个世纪以来香港公共行政的支柱.     

Biological Implications of the Ribosome's Stunning Stereochemistry

The ribosome's striking architecture is ingeniously designed for its efficient polymerase activity in the biosynthesis of proteins, which is a prerequisite for cell vitality. This elaborate architecture is comprised of a universal symmetrical region that connects all of the ribosomal functional centers involved in protein biosynthesis. Assisted by the mobility of selected ribosomal nucleotides, the symmetrical region provides the structural tools that are required not only for peptide bond formation, but also for fast and smooth successive elongation of nascent proteins. It confines the path along which the A‐tRNA 3′‐end is rotated into the P‐site in concert with the overall tRNA/mRNA sideways movement, thus providing the required stereochemistry for peptide bond formation and substrate‐mediated catalysis. The extreme flexibility of the nucleotides that facilitate peptide bond formation is being exploited to promote antibiotic selectivity and synergism, as well as to combat antibiotic resistance.