Characterisation of high aspect ratio non-conductive ceramic microstructures made by spark erosion

The spark erosion process is widely used for micro structuring. Its possibility to structure materials independent of their material properties like high hardness or melting temperature enables to address a large material diversity. However the process requires a minimal electrical conductivity of 0.1 Scm⁻¹. Nevertheless recent research has shown that the usage of an assisting electrode makes a processing of non-conductive materials possible. Thus even ceramics like Al₂O₃ or ZrO₂ can be processed. These materials are becoming more and more interesting for industrial application and the field of miniaturisation due to their outstanding material characteristics like high hardness, bending strength, melting temperature and chemical inertness. In this study a new lacquer based assisting electrode is used to erode bars in zirconia samples. For this purpose a modular tool concept is established. Bars with aspect ratios of more than 80 are generated. The achieved bar heights are 1.5 mm and the smallest bar width is 8 μm. Furthermore a characterisation of the sidewall angles showed mean values between 0.4° and 2.2° depending on the bar height and width.     

Transesterification of soy lecithin by lipase and phospholipase

Soy lecithin was modified by enzymatic transesterification in a solvent-free system. 1,3-SpecificRhizomucor miehei lipase was found to be efficient in the transesterification with lauric acid and oleic acid, where oleic acid was more incorporated into soy lecithin. Phospholipase A₂ incorporated lauric acid hardly at all, but it hydrolyzed lecithin efficiently. The mixture of lipase and phospholipase A₂ (1:1, w/w) incorporated lauric acid to the same extent as did 1,3-specific lipase alone at the same total enzyme concentration. The main fatty acids replaced were palmitic and linoleic acids by 1,3-specific lipase and its mixture with phospholipase A₂, and linoleic and linolenic acids by phospholipase A₂ alone, suggesting an improved oxidative stability of the resulting product. Hydrolysis could not be prevented, but it could be regulated by incubation time and by enzyme dosage. The minimal water content for significant incorporation of lauric acid into lecithin was below 0.5% of the weight of the reaction mixture.     

Guest Editorial:Special Issue on Spatial Economic Activity Analysis: New Methodologies

Editorial Introduction

Guest Editorial:Special Issue on Spatial Economic Activity Analysis: New Methodologies     

Disease pattern recognition in infrared spectra of human sera with diabetes mellitus as an example

To benefit from the full information content of the mid-IR spectra of human sera, we directly related the overall shape of the spectra to the donors' disease states. For this approach of disease pattern recognition we applied cluster analysis and discriminant analysis to the example of the disease states diabetes type 1, diabetes type 2, and healthy. In a binary, supervised classification of any pair of these disease states we achieved specificities and sensitivities of ~80% within our data set.     

Robust SuperPoll with Chaining Protocol for IEEE 802.11 Wireless LANs in Support of Multimedia Applications

Design of Wireless Local Area Networks (WLANs) needs to take into consideration the limited bandwidth available in the ISM band along with the noisy characteristics of the wireless environment and hidden terminal effects. In this paper we propose an enhancement for IEEE 802.11 standard that improves the WLAN support for multimedia applications. In the IEEE 802.11 PCF polling based protocol designed for multimedia applications support, the Point Coordinator (PC) polls each station in the Basic Service Area (BSA) individually. In the proposed SuperPoll approach the PC broadcasts at the beginning of the contention free period a SuperPoll, i.e., a message that includes the list of stations that will be polled during the current period. To improve the reliability of the polling based approach in a noisy environment, we propose to use a chaining mechanism in which each packet resends in its turn the SuperPoll message appended to its packet. We provide performance measurements of the proposed method in terms of channel efficiency and channel access time for multimedia applications that use the contention free period of IEEE 802.11 PCF. We notice that for noisy channels, the proposed method provides a dramatic throughput increase and delay decrease when compared with the Single Poll mechanism used in IEEE 802.11 PCF, thus providing better support for multimedia applications.     

Facets of spirituality as predictors of adjustment to cancer: Relative contributions of having faith and finding meaning.

Spirituality is a multidimensional construct, and little is known about how its distinct dimensions jointly affect well-being. In longitudinal studies (Study 1, n = 418 breast cancer patients; Study 2, n = 165 cancer survivors), the authors examined 2 components of spiritual well-being (i.e., meaning/peace and faith) and their interaction, as well as change scores on those variables, as predictors of psychological adjustment. In Study 1, higher baseline meaning/peace, as well as an increase in meaning/peace over 6 months, predicted a decline in depressive symptoms and an increase in vitality across 12 months in breast cancer patients. Baseline faith predicted an increase in perceived cancer-related growth. Study 2 revealed that an increase in meaning/peace was related to improved mental health and lower cancer-related distress. An increase in faith was related to increased cancer-related growth. Both studies revealed significant interactions between meaning/peace and faith in predicting adjustment. Findings suggest that the ability to find meaning and peace in life is the more influential contributor to favorable adjustment during cancer survivorship, although faith appears to be uniquely related to perceived cancer-related growth. (PsycINFO Database Record (c) 2010 APA, all rights reserved)