Determination of the overall migration from silicone baking moulds into simulants and food using 1H-NMR techniques

Different silicone baking moulds (37 samples) were characterized with respect to potential migrating substances using ¹H-NMR, RP-HPLC–UV/ELSD and GC techniques. In all cases cyclic organosiloxane oligomers with the formula [Si(CH₃)₂–O] _n were identified (n = 6 … 50). Additionally, linear, partly hydroxyl-terminated organosiloxanes HO–[Si(CH₃)₂–O] _n –H (n = 7 … 20) were found in 13 samples. No substances other than siloxanes could be detected, meaning the migrants mainly consist of organopolysiloxanes. Based on this knowledge, a ¹H-NMR quantification method for siloxanes was established for the analysis of both simulants and foodstuffs. Validation of the ¹H-NMR method gave suitable performance characteristics: limit of detection 8.7 mg kg^–1 oil, coefficient of variation 7.8% (at a level of 1.0 mg kg^–1 food). Migration studies were carried out with simulants (olive oil, isooctane, ethanol (95%), Tenax) as well as preparation of different cakes. From the 1st to 10th experiment, siloxane migration into cakes only slightly decreased, with a significant dependence on fat content. Migration never exceeded a level of 21 mg kg^–1 (3 mg dm^–2) and was, therefore, well below the overall migration limit of 60 mg kg^–1 (10 mg dm^–2). However, migration behaviour into simulants differed completely from these results.     

Ferulic acid dehydrodimers as structural elements in cereal dietary fibre

 Investigations on insoluble dietary fibre (IDF) of wheat, rye, barley, oat, maize, rice and millet led to the identification of several new dehydrodimers of ferulic acid (DFA). These compounds arise from 8–8′, 8–5′, 8–O–4′ and 5–5′ coupling. Esterified phenolics were set free by mild alkali hydrolysis, total amounts of phenolics (ester- plus etherified) were determined by alkali hydrolysis under pressure. Phenolic acids were analysed by gas chromatography – mass spectrometry (GC-MS) as their trimethylsilyl (TMS) derivatives and by high performance liquid chromatography – diode array detection (HPLC-DAD). In esterified form 8–8′aryl DFA and 5–5′ DFA dominate in most cereal IDF with, together, 45–60% of the DFA sum. More than 60% of total bound DFA are involved in ether linkages. Highest amounts of esterified as well as etherified DFA are estimated in millet, followed by maize. DFA contents of wheat, rye and barley are about two- to threefold lower than in millet but about twofold higher than in oat or rice. Received: 27 January 2000     

Short Vapour Residence Time Catalytic Pyrolysis of Spruce Sawdust in a Bubbling Fluidized-Bed Reactor with HZSM-5 Catalysts

Catalytic pyrolysis of spruce sawdust was carried out in a bubbling fluidized-bed reactor using HZSM-5 catalysts. The effects of space velocity, catalyst deactivation, catalyst acidity and catalyst regeneration were studied. The use of catalysts decreased the yield of organic liquids compared to non-catalytic yields while the yields of pyrolytic water and gases increased. Decreasing the space velocity enhanced these effects. The rate of catalyst deactivation depended on the acidity of the catalyst, with more acidic catalysts deactivating more rapidly. Using a catalyst with a Si/Al ratio of 140 resulted in the largest changes in bio-oil properties. Periodic regeneration of the catalyst in the fluidized-bed reactor was also demonstrated using varying regeneration times and temperatures. It was shown that compared to BFB reactors, CFB reactor types would offer better operating characteristics for commercial scale catalytic pyrolysis processes in regard to vapour residence times, and catalyst activity and regeneration.     

RNA amplification chip with parallel microchannels and droplet positioning using capillary valves

We present results from the MicroActive project which develops an instrument for molecular diagnostics. The instrument is first tested for patient screening for a group of viruses causing cervical cancer. Two disposable polymer chips with reagents stored on-chip are developed and will be inserted into the instrument for each patient sample analysis. The first chip will perform nucleic acid extraction from patient epithelial cervical cells, while mRNA amplification and fluorescent detection takes place in the second chip. This paper reports results on the amplification chip. Purified sample is inserted into the chip and split into ten smaller droplets for simultaneous amplification and detection of ten viruses. The droplets move in parallel channels, each with two chamber extensions containing dried reagents. Experimental results on parallel droplet movement using one external pump combined with hydrophobic restrictions show that the parallel droplet positions can be controlled. There are four valves with increasing burst pressures between 800 and 4,500 Pa in each parallel channel, positioning the droplets in metering zones and reaction chambers. The re-hydration times for the dried reagents in micro chambers have been monitored. After sample insertion, uniform concentration of the reagents in the droplet was reached after respectively 60 s and 10 min. These times are acceptable for successful amplification. Finally we show positive amplification of HPV type 16 viruses in a micro chamber.     

Cooperation in capital deposits

The rate of return earned on a deposit can depend on its term, the amount of money invested in it, or both. Most banks, for example, offer a higher interest rate for longer term deposits. This implies that if one individual has capital available for investment now, but needs it in the next period, whereas the opposite holds for another individual, then they can both benefit from cooperation since it allows them to invest in a longer term deposit. A similar situation arises when the rate of return on a deposit depends on the amount of capital invested in it. Although the benefits of such cooperative behavior may seem obvious to all individuals, the actual participation of an individual depends on what part of the revenues he eventually receives. The allocation of the jointly earned benefits to the investors thus plays an important part in the stability of the cooperation. This paper provides a game theoretical analysis of this allocation problem. Several classes of corresponding deposit games are introduced. For each class, necessary conditions for a nonempty core are provided, and allocation rules that yield core-allocations are examined.     

Ozonation of Spent Reactive Dye-Baths: Effect of HCO3?/CO32? Alkalinity

The effect of carbonate and bicarbonate alkalinity (soda ash buffer as 5,180 mg/L HCO3? alkalinity at pH 7 and as 5,100 mg/L CO32? alkalinity at pH 12) on the ozonation of reactive vinylsulphone dyestuffs in a simulated spent dye-bath has been studied at varying pHs. Adsorbable organic halogen (AOX) formation due to the high chloride content of the effluent and detoxification, which was evaluated in terms of the relative toxicity index Itox determined from the ED50 values for the marine photobacteria Vibrio fischeri, were also evaluated. Highest total organic carbon (56%), chemical oxygen demand (44%), and UV254 (77%) removals were achieved at pH 7 in the presence of HCO3? alkalinity. The fastest decolorization was observed for the case pH 2, the first order decolorization rate constant found as k620 = 0.16?min?1, closely followed by the pH 12 case with soda ash (k620 = 0.12?min?1) case. No positive correlation was evident between AOX, whose maximum value (=1.3 mg/L) appeared after 40 min ozonation at pH 7 and decreased to 0.54 mg/L after 120 min treatment, and Itox, which decreased to 0.16 at t = 50?min and increased rapidly thereafter. The Itox values were more related to color abatement kinetics. The maximum relative toxicity index of Itox = 0.83 occurred after 120 min. It was also established that the presence of alkalinity in the spent reactive dye-bath had no negative impact on the oxidation rates. In contrast, its absence seriously inhibited treatment efficiency. It is speculated that, with added soda ash, the carbonate radicals HCO3? and CO3??, which are more stable and selective than OH?, were produced and promoted the oxidation process.     

Chemotactic and Angiogenic Potential of Mineralized Collagen Scaffolds Functionalized with Naturally Occurring Bioactive Factor Mixtures to Stimulate Bone Regeneration

To develop cost-effective and efficient bone substitutes for improved regeneration of bone defects, heparin-modified mineralized collagen scaffolds were functionalized with concentrated, naturally occurring bioactive factor mixtures derived from adipose tissue, platelet-rich plasma and conditioned medium from a hypoxia-treated human bone marrow-derived mesenchymal stem cell line. Besides the analysis of the release kinetics of functionalized scaffolds, the bioactivity of the released bioactive factors was tested with regard to chemotaxis and angiogenic tube formation. Additionally, functionalized scaffolds were seeded with human bone marrow-derived mesenchymal stromal cells (hBM-MSC) and their osteogenic and angiogenic potential was investigated. The release of bioactive factors from the scaffolds was highest within the first 3 days. Bioactivity of the released factors could be confirmed for all bioactive factor mixtures by successful chemoattraction of hBM-MSC in a transwell assay as well as by the formation of prevascular structures in a 2D co-culture system of hBM-MSC and human umbilical vein endothelial cells. The cells seeded directly onto the functionalized scaffolds were able to express osteogenic markers and form tubular networks. In conclusion, heparin-modified mineralized collagen scaffolds could be successfully functionalized with naturally occurring bioactive factor mixtures promoting cell migration and vascularization.     

Computer-tailored smoking cessation intervention in a general population setting in Germany: outcome of a randomized controlled trial.

This study reports the outcome of a randomized controlled trial testing a computer-tailored smoking cessation intervention based on the transtheoretical model in a general population setting in Germany. Participants of the smoking intervention study were recruited from an existing general population health examination survey in a university hospital. The sample consisted of 611 current and former smokers at baseline, and of 485 participants in the core group of baseline daily cigarette smokers. Follow-ups were conducted 6, 12, 18, and 24 months after baseline. The intervention was designed for both current and former smokers, involved up to three individualized feedback letters, and was created using expert-system technology. Based on 7-day point-prevalence abstinence and 6-month prolonged abstinence as the outcome measures, the study identified no significant differences between the intervention and control groups. Modeling the full longitudinal data in generalized estimation equation analyses, using different nonresponse procedures, and adjusting for covariates did not alter the results. We conclude that the computer-tailored transtheoretical model-based smoking cessation intervention, as delivered in this study and in this special setting, was ineffective.