Stability of acrylamide in model systems and its reactivity with selected nucleophiles

Since the discovery of relatively high amounts of the carcinogenic acrylamide in heat-processed food products, many studies have been devoted to the formation of acrylamide. However, as acrylamide is an α,β-unsaturated amide, subsequent reactions can provoke the desired removal of this compound. Therefore, the stability of acrylamide and its reactivity with various food-relevant nucleophiles were studied.The results showed that acrylamide was quite stable in aqueous solutions, but much less in dry reaction conditions. Buffer type and pH had a significant influence on the decrease of free acrylamide. The presence of amino acids with a nucleophilic side chain considerably decreased the free acrylamide, due to Michael-type addition reactions. The highest reactivity was noted for cysteine, leading to the formation of the mono-addition product cysteine-S-β-propionamide, as well as to the double addition product. Other nucleophiles, such as lysine, arginine, serine and ascorbic acid, were less reactive, but yielded comparable condensation products.     

Subacute myocardial infarction: assessment by STIR T2-weighted MR imaging in comparison to regional function

Purpose Increased T2 signal intensity (SI) can be regularly observed in myocardial infarction. However, there are controversial reports about the relationship of elevated T2 SI to myocardial viability and some authors propose that high T2 SI serves as a sign of irreversible myocardial injury. This study investigates increased T2 SI compared to myocardial function in patients with reperfused subacute myocardial infarction. Preserved function was used as criterion for viability. Methods Ten healthy volunteers and 17 patients with myocardial infarction and patent inlarct related coronary artery were examined on a 1.5 T Magnetom Vision system (Siemens). For T2-weighted MR imaging a breath-hold STIR sequence with dark-blood preparation was used. Cine FLASH 2D imaging was applied to assess myocardial function. Signal-to-noise (S/N) in STIR T2 images was measured in normal and infarcted regions and subsequently identified by two independent observers. Based on a 20 segment model of the left ventricle findings were compared to regional myocardial function. Results Elevated STIR T2 SI was found in all 17 patients and observed in 27% (204/754) of segments. S/N of normal myocardium was 5.1 ±0.7 in volunteers and 4.9 ± 0.8 in patients(P=NS). Infarcted myocardium presented with significantly-increased S/N 12.8 ± 1.9 (P < 0.0001). Significant transmural elevation of T2 SI was noted in 32% of segments with preserved systolic function. Conclusion Increased STIR T2 SI can be observed transmurally in post-ischemic myocardial regions with preserved function. It therefore cannot be used as an exclusive marker for the non-viable region.     

开关磁阻式平面电动机及其控制

该文提出了一类新颖结构的平面电动机，这类电动机采用开关磁阻电动机的工作原理，结构简单、适用性强，可产生直接驱动的平面运动；在对平面电动机特性分析的基础上，进行了速度自抗扰控制研究；采取的特殊结构使半面电动机两个方向的运动解耦，使平面电动机的平面运动控制等效为两个直线电动机的运动控制；利用扩张状态观测器对扰动的观测和补偿，实现了速度的自抗扰控制；在进行控制器设计时，采用力分配函数的方法，即减小了纹波推力扰动，又使控制器的设计简单和易于实现；实验结果验证了所用方法的可行性和有效性。     

A 94-mW, 100-MS/s, 12-bit pipeline ADC for multi-standard TV demodulation applications

This paper presents the design and implementation of a 12-bit Analog-to-Digital Converter (ADC) for multi-standard TV demodulation applications. The ADC was fabricated in a standard digital 90-nm CMOS process and it is built by means of a front-end sample-and-hold and a cascade of 10 pipeline stages with 1.5-bits resolution. Performance of 60-dB signal-to-noise-ratio and 68-dB spurious-free-dynamic-range is obtained without calibration at 100-MS/s with a 1-V_P-P input signal swing. The occupied silicon area is 0.5-mm²; and the power consumption of 94-mW from a 1.2-V supply.     

Impact of ozonation on the genotoxic activity of tertiary treated municipal wastewater

Ozonation is an emerging technology for the removal of micropollutants from treated wastewater. Aim of the present study was to investigate the impact of ozone treatment on genotoxic and acute toxic effects of tertiary treated municipal wastewater. It is known that DNA-damaging chemicals cause adverse effects in the environment and that exposure to humans leads to cancer and other diseases. Toxicity was tested in organisms from three trophic levels namely in bacteria (Salmonella/microsome assays) which enable the detection of gene mutations, in a plant bioassay (micronucleus assay with root tip cells of Allium cepa) which reflects clastogenic and aneugenic effects and in single cell gel electrophoresis (SCGE) tests with mammalian cells which detect DNA migration caused by single-, double strand breaks and alkali labile sites. In the bacterial tests negative results were obtained with untreated samples but after concentration with C₁₈ cartridges a positive result was found in strains TA1537 and TA98 which are sensitive to frameshift mutagens while no mutations were induced in other tester strains (TA100, TA102 and YG1024). Ozone treatment led to a decrease of the mutagenic activity of the samples. In the SCGE experiments, DNA migration was detected with the unconcentrated effluent of the treatment plant and ozonation led to a substantial decrease of this effect. In the plant bioassays, negative results were obtained with the effluent and ozone treatment did not cause an alteration of the micronucleus frequencies. Also acute toxic effects were monitored in the different indicator organisms under all experimental conditions. The bacteriocidal/bacteriostatic effects which were seen with the concentrated samples were reduced by ozonation. In the experiments with the eukaryotic (plant and animal) cells no acute toxicity was seen with the effluents and ozonation had no impact on their viability. In conclusion findings of this study indicate that ozonation of tertiary effluents of a municipal treatment plant reduces the adverse effects caused by release of mutagens in aquatic ecosystems and does not decrease the viability of bacteria and eukaryotic cells. However, future research is required to find out if, and to which extent these findings can be generalized and which mechanisms account for the detoxification of the wastewater.     

Catalytic co-pyrolysis of packaging plastic and wood waste to achieve H2 rich syngas

In this work, the co-pyrolysis of pine sawdust and low-density polyethylene (LDPE) was performed in a two-stage fixed-bed reactor to achieve hydrogen-rich syngas and to investigate the effect of the parameters on gas yield and composition. Gas chromatography was used to confirm the content of the gas products. The pyrolysis was supported with Ni (in 5-25 wt%) loaded on activated carbon (AC). The maximum hydrogen concentration was 392.8 mmol g⁻¹ sample, which was achieved by the use of the 10% Ni-AC catalyst. The influence of Ni loading on supporter was investigated by scanning electron microscope and transmission electron microscope techniques besides the thermogravity analysis. The increasing size of the Ni particles can be observed as a function of the Ni concentration on the catalyst. Carbon deposition was detected and the amorphous carbon seems more dominant than filamentous form. In addition, the effect of fluid residence time (water inlet and purge gas) on syngas yield was studied. Three different fluid residence times were investigated, and among them, the highest hydrogen yield was 392.8 mmol g⁻¹sample at 1.57 minutes residence time. Furthermore, the catalyst lifetime was studied using 10 wt% of Ni containing AC, and the average hydrogen concentration was 196.0 mmol g⁻¹ sample over 15 cycles.     

The Online Market Observatory: A Domain Model Approach

The \"Semantic Market Monitoring\" (SEMAMO) project is intended to providea flexible empirical instrument for the permanent collection of data -- notably, prices --about products and services on offeneric online market observatory, SEMAMO capitalizeson a uniform data processing scheme covering all stages from automatic data capture usingconfigurable mediators, through integration of Web-extracted data from multiple sourcesand their long-term storage in a persistent econometric database, up to statistical analysesfeeding into flexible reporting functions. Based on a self-contained specification frameworkdescribing formally, by means of explicit models capturing market semantics, the onlinemarkets to be tracked, SEMAMO economizes the derivation of individual market monitoringapplications. During run-time, a SEMAMO instance then seeks to adaptively optimize dataquality and observation e±ciency based on both, previously gathered market evidence andcustomer-defined reporting requirements. The framework is evaluated experimentally in apractical application to online tourism.