FEM-computation of load carrying capacity of highly loaded passive components by direct methods

Limit and shakedown theorems are exact theories of classical plasticity for the direct computation of safety factors or of the load carrying capacity under constant and varying loads. Simple versions of limit and shakedown analysis are the basis of all design codes for pressure vessels and pipings. Using finite element methods (FEM), more realistic modeling can be used for a more rational design. The methods can be extended towards optimum plastic design. In this paper, we present a first implementation of limit and shakedown analyses for perfectly plastic material into a general purpose FEM program. Limit and shakedown loads are obtained for a square plate with a hole and for a thin tube. Interaction diagrams are calculated and the results are compared with known analytic solutions.     

Measurements with multi-point microprobes: Effect of suspended solids on the hydrodynamics of bubble columns for application in chemical and biotechnological processes

Many experimental studies reveal that suspended solids considerably alter the coalescence behaviour and hydrodynamic functions of wo-phase flow. But no systematic efforts have yet been undertaken to separate the effects of different particle properties on local gas hold-up, bubble size and interfacial area gas/liquid. The aim of this paper is to present the local values of these parameters in three-phase fluidized beds of different solids, using miniaturized optical fiber and conductivity needle probes. It is shown that particle concentration, size and, in particular, density are decisive for the change in coalescence behaviour. Ranges of normal (?_S > ?_L) and inverse fluidization (?_S < ?_L) must be distinguished and the flow regime also exerts a strong influence on the interactions between the dispersed phases, the transition point itself being a function of particle properties can be observed, This effect is evaluated for different column diameters, between 0.1 and 0.3 m.     

Fabrication of discontinuous surface patterns within microfluidic channels using photodefinable vapor-based polymer coatings

In this report, we introduce a surface modification method for the fabrication of discontinuous surface patterns within microfluidic systems. The method is based on chemical vapor deposition (CVD) of a photodefinable coating, poly(4-benzoyl-p-xylylene-co-p-xylylene), onto the luminal surface of a microfluidic device followed by a photopatterning step to initiate spatially controlled surface binding. During photopatterning, light-reactive groups of the CVD polymer spontaneously react with molecules adjunct to the surface, such as poly(ethylene oxide). We demonstrate the potential of these reactive polymers for surface modification by preventing nonspecific protein adsorption on different substrates including silicon and poly(dimethylsiloxane) as measured by fluorescence microscopy. More importantly, three-dimensional patterns have successfully been created within polymer-based microfluidic channels, establishing spatially controlled, bioinert surfaces. The herein reported surface modification method addresses a critical challenge with respect to surface engineering of microfluidic devices, namely, the fabrication of discontinuous patterns within microchannels.     

Multidimensional velocity filters for visual scene analysis in automotive driver assistance systems

Automotive scenery often contains objects that can be classified by object speed and movement direction. These features can be extracted from video data by linear n-D filters, which have already been analyzed in the past. While soundness of results was convincing, interest in those systems declined due to the reduced computational abilities of contemporary computers. Modern hardware allows realization of velocity filters, if the n-D system is carefully adapted to the analysis problem. The present paper analyzes the premises for application of velocity filters in the domain of automotive driver assistance systems, i.e. with respect to detectability of objects and implementability in a cost effective way. Especially the influence of the frame rate and the temporal violation of the sampling theorem are analyzed. Transfer functions for n-D filters working in a vision-based blind spot collision avoidance system are presented and discussed, and promising approaches for future application fields are proposed.     

Joint Modulations of Electromagnetic Waves and Digital Signals on a Single Metasurface Platform to Reach Programmable Wireless Communications

In current wireless communication and electronic systems,digital signals and electromagnetic(EM)radi-ation are processed by different modules.Here,we propose a ...     

Masked mycotoxins: A review

The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non‐extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon‐X, T‐2 toxin, HT‐2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.     

Zinc deprivation inhibits extracellular matrix calcification through decreased synthesis of matrix proteins in osteoblasts

Scope: Zinc is implicated as an activator for bone formation, however, its influence on bone calcification has not been reported. This study examined how zinc regulates the bone matrix calcification in osteoblasts. Methods and Results: Two osteoblastic MC3T3‐E1 cell subclones (SC 4 and SC 24 as high and low osteogenic differentiation, respectively) were cultured in normal osteogenic (OSM), Zinc deficient (Zn–, 1 μM), or adequate (Zn+, 15 μM) media up to 20 days. Cells (SC 4) were also supplemented with (50 μg/mL) or no ascorbic acid (AA) in combination with Zinc treatment. Zn– decreased collagen synthesis and matrix accumulation. Although AA is essential for collagen formation, its supplementation could not compensate for Zinc deficiency‐induced detrimental effects on extracellular matrix mineralization. Zn– also decreased the medium and cell layer alkaline phosphatase ALP activity. This decreased ALP activity might cause the decrease of Pi accumulation in response to Zn–, as measured by von Kossa staining. Ca deposition in cell layers, measured by Alizarin red S staining, was also decreased by Zn^–. Conclusion: Our findings suggest that zinc deprivation inhibits extracellular matrix calcification in osteoblasts by decreasing the synthesis and activity of matrix proteins, type I collagen and ALP, and decreasing Ca and Pi accumulation. Therefore zinc deficiency can be considered as risk factor for poor extracellular matrix calcification.     

Laterally vibrating MEMS resonant vacuum sensor based on cavity-SOI process for evaluation of wide range of sealed cavity pressure

Microsystem Technologies - This paper reports a laterally vibrating MEMS resonant vacuum sensor which senses ambient pressure based on the squeeze-film damping effect. The single-anchored...     

Advanced characterization technique for mechanochemically synthesized materials: neutron total scattering analysis

Materials that adopt the pyrochlore (A₂B₂O₇) structure show promise for use in a variety of energy-related applications such as immobilization of actinide-rich nuclear waste and oxide fuel cells. Mechanochemical synthesis, a combination of milling and high-temperature treatment, has been successfully applied to fabricate many different pyrochlore compositions. High-resolution neutron total scattering experiments were used to gain fundamental insight into the structural details of milled Er₂Ti₂O₇ pyrochlore and the subsequent evolution under high-temperature treatment. The milling process creates a highly disordered structure in which local atomic ordering is present that is significantly different than the observed long-range behavior. Thermal annealing leads to a complex defect recovery scheme with a gradual local rearrangement from a weberite-type atomic ordering to a pyrochlore phase independent of the sharp long-range crystallization process. Annealing of the milled sample up to 1200 °C does not reproduce the local structure of the same pyrochlore sample prepared by solid-state synthesis. This indicates that despite both samples possessing identical long-range structures, local defects induced by the milling process persist to very high temperatures. These findings provide a direct insight into the mechanochemical synthesis of pyrochlore oxides and help to better elucidate the structural properties of highly disordered complex oxides under extreme conditions from the local atomic arrangement to the macroscale.