Flexible embedded circuitry: A novel process for high density, cost effective electronics

Flexible electronics are starting to emerge with all-printed but also hybrid cost effective, smart electronic products that will find a wide range of applications in large quantities in our society. Such products have to be built on low cost substrate materials like PEN or PET foils. Because of the low thermal stability and limited chemical resistance of these foils, established interconnection technologies are not suitable. The current paper describes a novel technology for making electronic circuitry which does not need incompatible thermal and chemical processes during fabrication. The technology called ‘embedded circuitry’ uses laser ablation to write the circuitry patterns in the flexible foils. These patterns are subsequently filled with conductive pastes using mask-less squeegee filling techniques. Conducting lines in flexible PEN foil with widths down to 10 μm, line gaps down to 10 μm and resistances down to 0.1 Ω/mm are demonstrated. Finite element modeling and bending tests revealed good flexibility of this low cost circuitry. Also the circuitry can be directly used for chip attachment through flipchip bonding.     

Evidence for hierarchical categorization of coarticulated phonemes.

The reported research investigates how listeners recognize coarticulated phonemes. First, 2 data sets from experiments on the recognition of coarticulated phonemes published by D. H. Whalen (1989) are reanalyzed. The analyses indicate that listeners used categorization strategies involving a hierarchical dependency. Two new experiments are reported investigating the production and perception of fricative–vowel syllables. On the basis of measurements of acoustic cues on a large set of natural utterances, it was predicted that listeners would use categorization strategies involving a dependency of the fricative categorization on the perceived vowel. The predictions were tested in a perception experiment using a 2-dimensional synthetic fricative–vowel continuum. Model analyses of the results pooled across listeners confirmed the predictions. Individual analyses revealed some variability in the categorization dependencies used by different participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potential routes for the nitration of toluene and nitrotoluene with solid acids

New synthesis routes have been investigated for the production of dinitrotoluenes (DNTs) from toluene or an equimolar mixture of 2-nitrotoluene (2-NT) and 4-nitrotoluene (4-NT) and nitric acid using solid acids as heterogeneous catalysts. The main objective was the replacement of liquid sulphuric acid. A secondary goal was the increase of 4-NT and 2,4-DNT in the product mixture, which are more valuable products. Particular consideration was given to the feasibility of future large-scale process implementation. Continuous flow vapour phase reaction, and liquid phase reaction with simultaneous distillation were investigated. DNT formation in the vapour phase reaction was negligible with all solid acids tested. Preshaped silica impregnated with sulphuric acid was the most active catalyst but a continuous loss of sulphuric acid with time-on-stream was observed. Zeolite beta provided a higher 4-NT to 2-NT ratio than ZSM-5, ZSM-12 and mordenite, but deactivated after 5–10 h on-stream. Regeneration of beta was possible by thermal treatment. The para-selectivity of mordenite could be improved by the creation of a mesoporous system. In the reaction with simultaneous distillation, supported liquid acids exhibited true catalytic behaviour for the conversion of NT to DNT, but a loss of the impregnated acid was observed. Zeolite beta was about half as active as supported liquid acids and gave an exceptionally high 2,4-DNT selectivity of up to 94%, compared to 74–79% obtained with all other solid acids.     

Pellet heat transfer coefficients in packed beds: Global and local values

Pellet heat transfer coefficients in a packed bed have been obtained, both for specific individual pellets and for the entire bed. They are referred to as local and global values, respectively. It appears that the local values are scattered around the global value. This is due to the heat transfer coefficient of individual pellets being statistically distributed, as a result of the randomnes of the packing. At low Reynolds numbers, both global and local values fall well below Nu = 2, which is the lower limit for a single sphere in absence of convection. In the literature, this behaviour has been attributed i.a. to axial dispersion and fluid maldistribution. However, these phenomena cannot explain why the same behaviour is observed in slurries. The fact that the local values fall below Nu = 2 would suggest that neither of these explanations is valid for packed beds.     

Residence time distribution and hold-up in a cocurrent upflow packed bed reactor at elevated pressure

The residence time distribution in liquid phase was measured in a cocurrent upflow packed bed reactor for the system methanol-hydrogen at low Reynolds numbers and at elevated pressure. The plug flow with axial dispersion model was used to describe mixing in the system. The imperfect pulse method was used to measure the system response to a tracer pulse input. The parameters were calculated using the weighted moments method. The influence of the weighting factor was investigated. The experimental and theoretical outputs, as calculated by convolution, agreed very well. Different types of correlations were used for the Bodenstein number and liquid hold-up. From these correlations, the optimal one was selected for each parameter. A comparison was made between the ordinary moments and the weighted moments methods which led to the conclusion that the latter method is superior with respect to the accuracy of the estimated parameters and therefore strongly recommended.     

Enzymatic Polymerization of Phosphonate Nucleosides

5′‐O‐Phosphonomethyl‐2′‐deoxyadenosine (PMdA) proved to be a good substrate of the Therminator polymerase. In this article, we investigated whether the A, C, T and U analogues of this phosphonate nucleoside (PMdN) series can function as substrates of natural DNA polymerases. PMdT and PMdU could only be polymerized enzymatically to a limited extent. Nevertheless, PMdA and PMdC could be incorporated into a DNA duplex with complete chain elongation by all the DNA polymerases tested. A mixed sequence of four nucleotides containing modified C, T and A residues could be obtained with the Vent(exo^?) and Therminator polymerases. The kinetic values for the incorporation of PMdA by Vent(exo^?) polymerase were determined; a reduced K_M value was found for the incorporation of PMdA compared to the natural substrate. Future polymerase directed evolution studies will allow us to select an enzyme with a heightened capacity to process these modified DNA building blocks into modified strands.     

Traits at work: The design of a new trait-based stream library

Recent years saw the development of a composition mechanism called traits. Traits are pure units of behavior that can be composed to form classes or other traits. The trait composition mechanism is an alternative to multiple or mixin inheritance in which the composer has full control over the trait composition.To evaluate the expressiveness of traits, some hierarchies were refactored, showing code reuse. However, such large refactorings, while valuable, may not exhibit all possible composition problems, since the hierarchies were previously expressed using single inheritance and following certain patterns.This paper presents our work on designing and implementing a new trait-based stream library named Nile. It evaluates how far traits enable reuse, what problems can be encountered when building a library using traits from scratch and compares the traits solution to alternative composition mechanisms. Nile's core allows the definition of compact collection and file streaming libraries as well as the implementation of a backward-compatible new stream library. Nile method size shows a reduction of 40% compared to the Squeak equivalent. The possibility to reuse the same set of traits to implement two distinct libraries is a concrete illustration of trait reuse capability.     

Categorization of sounds.

The authors conducted 4 experiments to test the decision-bound, prototype, and distribution theories for the categorization of sounds. They used as stimuli sounds varying in either resonance frequency or duration. They created different experimental conditions by varying the variance and overlap of 2 stimulus distributions used in a training phase and varying the size of the stimulus continuum used in the subsequent test phase. When resonance frequency was the stimulus dimension, the pattern of categorization-function slopes was in accordance with the decision-bound theory. When duration was the stimulus dimension, however, the slope pattern gave partial support for the decision-bound and distribution theories. The authors introduce a new categorization model combining aspects of decision-bound and distribution theories that gives a superior account of the slope patterns across the 2 stimulus dimensions. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The Effect of Age of Acquisition in Visual Word Processing: Further Evidence for the Semantic Hypothesis.

The authors investigated whether the meaning of visually presented words is activated faster for early-acquired words than for late-acquired words. They addressed the issue using the semantic Simon paradigm. In this paradigm, participants are instructed to decide whether a stimulus word is printed in uppercase or lowercase letters. However, they have to respond with a verbal label ("living" or "nonliving") that is either congruent with the meaning of the word (e.g., saying "living" to the stimulus DOG) or incongruent (e.g., saying "nonliving" to the stimulus dog). Results showed a significant congruency effect that was stronger for early-acquired words than for late-acquired words. The authors conclude that the age of acquisition is an important variable in the activation of the meaning of visually presented words. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic feedback control of relative blood volume changes during hemodialysis improves blood pressure stability during and after dialysis

Automatic feedback systems have been designed to control relative blood volume changes during hemodialysis (HD) as hypovolemia plays a major role in the development of dialysis hypotension. Of these systems, one is based on the concept of blood volume tracking (BVT). BVT has been shown to improve intra-HD hemodynamic stability. We first questioned whether BVT also improves post-HD blood pressure stability in hypotension-prone patients and second, whether BVT is effective in reducing the post-HD weight as many hypotension-prone patients are overhydrated because of an inability to reach dry weight. After a 3-week period on standard HD, 12 hypotension-prone patients were treated with two consecutive BVT treatment protocols. During the first BVT period of 3 weeks, the post-HD target weight was kept identical compared with the standard HD period (BVT-constant weight; BVT-cw). During the second BVT period of 6 weeks, we gradually tried to lower the post-HD target weight (BVT-reduced weight; BVT-rw). In the last week of each period, we studied intra-HD and 24 hr post-HD blood pressure behavior by ambulatory blood pressure measurement (ABPM). Pre- and post-HD weight did not differ between standard HD and either BVT-cw or BVT-rw. Heart size on a standing pre-dialysis chest X-ray did not change significantly throughout the study. There were less episodes of dialysis hypotension during BVT compared with standard HD (both BVT periods: p<0.01). ABPM data were complete in 10 patients. During the first 16 hr post-HD, systolic blood pressure was significantly higher with BVT in comparison with standard HD (both BVT periods: p<0.05). The use of BVT in hypotension-prone patients is associated with higher systolic blood pressures for as long as 16 hr post-HD. BVT was not effective in reducing the post-HD target weight in this patient group.