Knowledge networks across Europe: which distance matters?

In this paper, we address the manifold nature of knowledge through the analysis of four distinct but complementary phenomena (Internet hyperlinks, EPO co-patent applications, Erasmus students mobility and European research networks) which characterise knowledge as an intrinsic relational structure (directly) connecting people, institutions and (indirectly) regions across five European countries. We study the structure (in terms of density, centralisation, clustering, assortativity, centre-periphery and resilience) of these international knowledge flows through network analysis techniques and we test the influence of geographical distance as opposed to sectoral (based on the industrial distribution of innovative activity) and functional (based on the value of the European technological index) distances in shaping the strength of knowledge relations through a gravitational model. Network Analysis techniques applied to the configuration of international knowledge flows between European regions highlight the existence of a polarised hierarchical structure. By estimating a “gravity equation” model we demonstrate that, far from the claim of the “death of distance”, geographic distance is still relevant for determining the structure of inter-regional knowledge flows. Functional and, above all, sectoral distances play also a relevant role suggesting that knowledge flows easier between similar regions (according to their technological level and the industrial distribution of their innovation system).     

Fiducial markers for combined 3-dimensional mass spectrometric and optical tissue imaging

Mass spectrometric imaging (MSI) has become widely used in the analysis of a variety of biological surfaces. Biological samples are spatially, morphologically, and metabolically complex. Multimodal molecular imaging is an emerging approach that is capable of dealing with this complexity. In a multimodal approach, different imaging modalities can provide precise information about the local molecular composition of the surfaces. Images obtained by MSI can be coregistered with images obtained by other molecular imaging techniques such as microscopic images of fluorescent protein expression or histologically stained sections. In order to properly coregister images from different modalities, each tissue section must contain points of reference, which are visible in all data sets. Here, we report a newly developed coregistration technique using fiducial markers such as cresyl violet, Ponceau S, and bromophenol blue that possess a combination of optical and molecular properties that result in a clear mass spectrometric signature. We describe these fiducial markers and demonstrate an application that allows accurate coregistration and 3-dimensional reconstruction of serial histological and fluorescent microscopic images with MSI images of thin tissue sections from a breast tumor model.     

The effect of fruit extracts with polyphenol oxidase (PPO) activity on the in vitro accessibility of iron in high-tannin sorghum

Dephytinized high-tannin sorghum flour was incubated with crude extracts from pear, banana or avocado, respectively, followed by investigation of the effects on the phenolic content and on in vitro accessible iron. All fruits contained polyphenol oxidase (PPO) activity and incubation resulted in significant reduction of phenolic compounds. Incubation with avocado extract resulted in the lowest levels of phenolic compounds, as well as the highest amount of in vitro accessible iron. Peroxidase activity and some organic acids in the fruit extracts might also have contributed to the positive effect on iron accessibility. Nevertheless, incubation of the sorghum flour with the fruit extracts under conditions enabling the PPO to oxidize phenolic compounds, resulted in the highest accessibility of iron. The results from this study suggest that the PPO activity in simple fruit extracts can be utilized to increase the accessibility of iron in dephytinized polyphenol-containing cereal foods.     

Stochastic modelling of migration from polyolefins

A method is presented to predict diffusion coefficients in polyolefins using stochastic modelling. A large number of experimental diffusion coefficients, published in the literature as one dataset, was used to derive probability distributions of diffusion coefficients in the polymers low‐density polyethylene and linear low‐density polyethylene, medium‐ and high‐density polyethylene, and polypropylene. An equation is proposed to describe the diffusion coefficient as a function of the molar mass of the migrant. Model parameters and standard deviations are predicted by minimizing the sum of squared errors and the residuals are used to check the assumed types of probability distribution. The experimental data can be described by a log–normal distribution. It is shown how the derived probability distributions can be used as input for migration predictions. The method presented provides information about the most likely migration results for a given packaging–food simulant combination. This is important for prediction of the probability that a given migration limit may be exceeded. Copyright © 2005 Society of Chemical Industry     

In vitro investigations of a novel wound dressing concept based on biodegradable polyurethane

Non-healing and partially healing wounds are an important problem not only for the patient but also for the public health care system. Current treatment solutions are far from optimal regarding the chosen material properties as well as price and source. Biodegradable polyurethane (PUR) scaffolds have shown great promise for in vivo tissue engineering approaches, but accomplishment of the goal of scaffold degradation and new tissue formation developing in parallel has not been observed so far in skin wound repair. In this study, the mechanical properties and degradation behavior as well as the biocompatibility of a low-cost synthetic, pathogen-free, biocompatible and biodegradable extracellular matrix mimicking a PUR scaffold was evaluated in vitro. The novel PUR scaffolds were found to meet all the requirements for optimal scaffolds and wound dressings. These three-dimensional scaffolds are soft, highly porous, and form-stable and can be easily cut into any shape desired. All the material formulations investigated were found to be nontoxic. One formulation was able to be defined that supported both good fibroblast cell attachment and cell proliferation to colonize the scaffold. Tunable biodegradation velocity of the materials could be observed, and the results additionally indicated that calcium plays a crucial role in PUR degradation. Our results suggest that the PUR materials evaluated in this study are promising candidates for next-generation wound treatment systems and support the concept of using foam scaffolds for improved in vivo tissue engineering and regeneration.     

Answering quasi-randomized reading items without the passages on the SAT—I.

Examinees can correctly answer many Scholastic Assessment Test (SAT) reading items when the passages accompanying the items are missing. According to one hypothesis, examinees use information from other reading items (cognates) belonging to the same passage. The purpose of this study was to test that hypothesis for the revised SAT (SAT-I) reading task. Cognate information was diminished by dispersing cognates among other reading items from 4 parallel forms of the SAT-I. Examinee performance in this condition was inferior to performance in a control, where cognate information was readily available. Nonetheless, the correlation between performance and verbal SAT score in the experimental condition remained high and equivalent to the control. Examinees do seem to use cognate information when passages are missing on the SAT-I reading task, but such information is not among the no-passage factors that systematically affect reading performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

应用于功率芯片封装的瞬态液相扩散连接材料与接头可靠性研究进展

功率半导体由于其工作电压高、电流大、放热量大等特点,已逐渐向小型化、高致密化发展.新一代宽禁带半导体器件因其优异的性能可以提高工作温度和功率密度,展现出较好的应用前景,这对与之匹配的电力封装材料提出了更高的要求.随着工作温度的不断升高,高温环境下失稳和运行环境不稳定等安全问题亟需解决,对功率半导体芯片封装接头的高温可靠性提出了更高的要求.且由于污染严重的高铅焊料不满足环保要求,高温无铅焊料的研制与对相应连接技术的研究成为当前的研究重点.瞬态液相扩散连接(Transient liquid phase bonding,TLP bonding)技术通过在低温下焊接形成耐高温金属间化合物接头,以满足"低温连接,高温服役"的要求,在新一代功率半导体的耐高温封装方面有良好的应用前景.针对TLP技术的耐高温封装材料有Sn基、In基和Bi基等.目前TLP连接材料主要有片层状、焊膏与焊片三种形态.其中片层状TLP焊料应用最早,且国内外对于其连接机理、接头性能和可靠性已有较为成熟的研究.近些年开发的基于复合粉末的焊膏与焊片形态TLP焊料具有相对较高的反应效率,但仍需大量理论与实验研究来验证其工业应用前景.本文综述了TLP连接用Sn基与In基焊料的特点,重点阐述了不同形态焊料在TLP连接机理、接头微观组织、力学性能与结构可靠性等方面的国内外研究现状及进展,并且认为接头中缺陷问题的研究以及不同服役条件下物相转化机制和接头失效机理的研究对高可靠性接头的制备具有重要意义.     

International on-line reciprocal peer tutoring to promote modern language development in primary schools

The paper reports data from an on-line peer tutoring project. In the project 78, 9–12-year-old students from Scotland and Catalonia peer tutored each other in English and Spanish via a managed on-line environment. Significant gains in first language (Catalonian pupils) modern language (Scottish pupils) and attitudes towards modern languages (both Catalonian and Scottish pupils) were reported for the experimental group as compared to the control group. Results indicated that pupils tutored each other in using Piagetian techniques of error correction during the project. Error correction provided by tutors to tutees focussed on morph syntaxys, more specifically the correction of verbs. Peer support provided via the on-line environment was predominantly based on the tutor giving the right answer to the tutee. High rates of impact on tutee corrected messages were observed. The implications for peer tutoring initiative taking place via on-line environments are discussed. Implications for policy and practice are explored.