Analysis and stereodifferentiation of linalool in Theobroma cacao and cocoa products using enantioselective multidimensional gas chromatography

Contents and enantiomeric distributions of linalool (3,7-dimethyl-1,6-octadien-3-ol) were investigated in raw and roasted cocoa beans (seeds of Theobroma cacao) of defined origin as well as in commercial products, such as cocoa powders or chocolates. The stereodifferentiation of linalool was achieved by enantioselective multidimensional gas chromatography using heptakis (2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin as chiral stationary phase. Simultaneous steam distillation–extraction at pH 7 allowed sample preparation without racemization of linalool. Cocoa beans contain linalool primarily as (S)-enantiomer. Model experiments and analyses of commercial products such as cocoa powders and chocolates revealed that technological procedures employed in the manufacturing of cocoa products do not result in significant changes of the original enantiomeric distribution of linalool.     

Micro gear validation: improving the correlation between virtual and physical testing

Downsizing mechanical systems requires the consideration of technological environment and restrictions. Nominal dimensions can be miniaturized, but shape and material deviations cannot be scaled down in the same way. In design these effects have to be considered and thus analyzed and evaluated in the very early activities. Simulation and test methods have to be adapted to the special characteristics of microtechnology. The present paper provides a strategy to validate micromechanical systems by means of virtual and physical testing. A standard test approach in macroscopic gear metrology, the tangential composite inspection, is used as validation tool for both test approaches. The results are very promising and show a good correlation between both miniaturized tests procedures.     

Mitigation strategies to reduce pesticide inputs into ground- and surface water and their effectiveness; a review

In this paper, the current knowledge on mitigation strategies to reduce pesticide inputs into surface water and groundwater, and their effectiveness when applied in practice is reviewed. Apart from their effectiveness in reducing pesticide inputs into ground- and surface water, the mitigation measures identified in the literature are evaluated with respect to their practicability. Those measures considered both effective and feasible are recommended for implementing at the farm and catchment scale. Finally, recommendations for modelling are provided using the identified reduction efficiencies. Roughly 180 publications directly dealing with or being somehow related to mitigation of pesticide inputs into water bodies were examined. The effectiveness of grassed buffer strips located at the lower edges of fields has been demonstrated. However, this effectiveness is very variable, and the variability cannot be explained by strip width alone. Riparian buffer strips are most probably much less effective than edge-of-field buffer strips in reducing pesticide runoff and erosion inputs into surface waters. Constructed wetlands are promising tools for mitigating pesticide inputs via runoff/erosion and drift into surface waters, but their effectiveness still has to be demonstrated for weakly and moderately sorbing compounds. Subsurface drains are an effective mitigation measure for pesticide runoff losses from slowly permeable soils with frequent waterlogging. For the pathways drainage and leaching, the only feasible mitigation measures are application rate reduction, product substitution and shift of the application date. There are many possible effective measures of spray drift reduction. While sufficient knowledge exists for suggesting default values for the efficiency of single drift mitigation measures, little information exists on the effect of the drift reduction efficiency of combinations of measures. More research on possible interactions between different drift mitigation measures and the resulting overall drift reduction efficiency is therefore indicated. Point-source inputs can be mitigated against by increasing awareness of the farmers with regard to pesticide handling and application, and encouraging them to implement loss-reducing measures of "best management practice". In catchments dominated by diffuse inputs at least in some years, mitigation of point-source inputs alone may not be sufficient to reduce pesticide loads/concentrations in water bodies to an acceptable level.     

Cellular investigations on electrochemically deposited calcium phosphate composites

Electrochemically deposited calcium phosphate (CaP) coatings are fast resorbable and existent only during the first period of osseointegration. In the present study, composite coatings with varying solubility (hydroxyapatite (HA), brushite with less HA and monetite (M) with less HA) were prepared and the influence of the degradation and the reprecipitation of CaP on osteoblastic cells were investigated. On the brushite composite coating a new precipitated, finely structured CaP phase was observed during immersion in cell culture medium with or without osteoblastic cells. The surface morphology of monetite and HA coatings were entirely unmodified under the same conditions. So it could be assumed that electrochemically deposited brushite with less HA acts as a precursor for new precipitated CaP. On this surface osteoblastic cells revealed a well-spread morphology with pronounced actin cytoskeleton and demonstrated good proliferation behaviour. Thus we suggest that brushite seems to be especially suitable for coating of implants as a matrix for nucleation and growth of new bone.     

On the Impact of Systematic Noise on the Evolutionary Optimization Performance—A Sphere Model Analysis

Quality evaluations in optimization processes are frequently noisy. In particular evolutionary algorithms have been shown to cope with such stochastic variations better than other optimization algorithms. So far mostly additive noise models have been assumed for the analysis. However, we will argue in this paper that this restriction must be relaxed for a large class of applied optimization problems. We suggest systematic noise as an alternative scenario, where the noise term is added to the objective parameters or to environmental parameters inside the fitness function. We thoroughly analyze the sphere function with systematic noise for the evolution strategy with global intermediate recombination. The progress rate formula and a measure for the efficiency of the evolutionary progress lead to a recommended ratio between and . Furthermore, analysis of the dynamics identifies limited regions of convergence dependent on the normalized noise strength and the normalized mutation strength. A residual localization error R can be quantified and a second to ratio is derived by minimizing R .     

Spannungskorrosion an Stahl St 37 und an der Aluminium-Legierung AlMg 3 durch staubhaltige Abgase von Zement-Drehöfen

Stress corrosion cracking of steel St 37 and the aluminium alloy AlMg 3 by dust-bearing flue-gases from rotary cement kilns Internals of electrofilters for dedusting flue-gases from rotary cement kilns were destroyed in several cases by stress corrosion cracking. Collector plates of steel St 37 exhibited serious corrosion damages after only two years' operation at temperatures between 60 and 120° C; in these cases an approximately uniform intercrystalline attack had been superimposed by local trough-like to pit-like corrosion. A frame of AlMg 3 for spray-electrodes fails by intercrystalline grain segregation after ribbon-like precipitates had formed on the grain-boundaries during 6 years' operation at 100° C. The characteristic types of destruction could be demonstrated on the surfaces of open cracks and artificially prepared ruptures and with the aid of metallographic specimens. Potential methods for increasing corrosion resistance are indicated.     

Rapid and simultaneous analysis of 16-<Emphasis Type="Italic">O</Emphasis>-methylcafestol and sterols as markers for assessment of green coffee bean authenticity by on-line LC-GC

An on-line LC-GC method for analysis of 16-O-methylcafestol (16-OMC) and total sterols in oils obtained from green beans of Coffea canephora (Robusta) and C. arabica (Arabica) has been developed. HPLC pre-separation of the transesterified lipids allows quantification of the content of 16-OMC. The fraction containing the sterols is transferred to on-line GC analysis. The results obtained for Arabica and Robusta samples were in good agreement with literature data obtained by classical analytical procedures. The method allows rapid and simultaneous determination of two markers (16-OMC and Δ⁵-avenasterol) proposed for authenticity assessment of coffee beans and overcomes time-consuming sample pretreatment steps.     

The inhibitory glycine receptor-simple views of a complicated channel

The strychnine-sensitive glycine receptor is the principal mediator of fast inhibitory synaptic transmission in the mammalian spinal cord and brain stem. As a member of the ligand-gated ion-channel family, it shares structural homology with the nicotinic acetylcholine, GABA(A/C) and serotonin 5-HT(3) receptors. Ion-channel activation and desensitisation are controlled by a variety of factors such as subunit composition, posttranslational modification, absence or presence of modulatory ions or other agents and possibly protein-protein interactions. Glycine-receptor mutations, either associated with the human motor disorder hyperekplexia or artificially introduced, have helped to define the regulatory domains of the receptor protein. In addition to their effects on glycine-receptor function, allelic variants of glycine-receptor genes may also affect biogenesis, assembly and degradation of the receptor.     

Investigations on increasing safe gas volumetric flow rate through a water trap flame arrester

In the process industries, safety problems may arise when combustible gases are transported through pipes. Therefore, it is necessary to prevent propagation of flame fronts into or through systems, in order to avoid undesired explosions and flashbacks into the production plant. Safety devices which are used in such cases are the flame arresters, e.g. water trap flame arresters. There is a maximum gas flow rate through a water trap flame arrester below which a flashback is unlikely to occur. Based on investigations of the explosion behaviour of bubbles in suspensions of glass spheres, experiments were carried out in a water trap flame arrester of industrial demensions. It is shown that the safe gas volumetric flow rate through a water trap flame arrester can be increased by up to 30% for H₂/air mixtures when glass spheres are added to the liquid in the flame arrester.