Validation of meat inspection results for Taenia saginata cysticercosis by PCR-restriction fragment length polymorphism

Bovine cysticercosis is a zoonosis caused by the larval stage (cysticercus) of the human tapeworm Taenia saginata. Infected cattle is an important food safety issue besides an economic concern. Humans get infected by eating raw or undercooked meat containing viable cysticerci. Visual meat inspection of bovines is the only public health measure implemented to control transmission to humans, but it lacks sensitivity and objectivity. It may underestimate the prevalence of the disease by a factor 3 to 10. Furthermore, the success of the method depends on the expertise of the meat inspector as well as on the stage of development of the cysticerci. The focus of this study was to develop and explore the usefulness of a PCR assay as an objective alternative to evaluate the meat inspector's visual inspection results. Hereto, a PCR was developed for the detection of T. saginata DNA in muscle lesions. Based on the laboratory classification of lesions, almost 97% of viable cysts were confirmed by PCR, while for dead cysts, the percentage was approximately 73%. Taken together, these data demonstrate the difficulties of visual meat inspection and their objective interpretation, emphasizing the need to improve current assays to strengthen the control of bovine cysticercosis.     

Evolution of Texture and Deformation Mechanisms During Repeated Deformation and Heat Treating Cycles of U-6Nb

The evolution of the crystallographic texture and lattice strain of uranium 6-weight percent niobium alloy samples are tracked during multiple deformation and heat treating cycles in an effort to understand and control the mechanical properties of the material following thermo-mechanical processing. The heavily twinned microstructure and low-symmetry crystal structure of U-6Nb result in multiple sequential active deformation mechanisms associated with distinctive deformation textures in strain ranges from 0-0.15 true strain. It is found that heating into the high-temperature γ-phase erases much of the texture formed during deformation at room temperature in the α′′-phase and resets the active deformation mechanisms. Through a small number of deformation/heat treat cycles to moderate strains, i.e., ~ 0.13 per cycle, the flow strength of the material is recovered to its original value. However, on the fourth such cycle, a reduction of strength is observed and the sample failed.

     

Assessment of liquid chromatography-tandem mass spectrometry approaches for the analysis of ceftiofur metabolites in poultry muscle

The use of cephalosporin antibiotics in veterinary practice is likely to play an important role in the development of β-lactam-resistant bacteria. To detect off-label cephalosporin antibiotic usage, an analytical method is needed that, besides the native compound, also detects their active metabolites. In this paper, the applicability of three approaches for the quantitative analysis of ceftiofur using LC-MS/MS is assessed, viz. (A) analysis of ceftiofur, desfuroylceftiofur and/or desfuroylceftiofur cystein disulfide, (B) derivatisation of ceftiofur metabolites to desfuroylceftiofur acetamide and (C) chemical hydrolysis using ammonia, to produce a marker compound for ceftiofur. We found that approach A was not suited for quantitative analysis of total ceftiofur concentration or for effectively detecting off-label use of ceftiofur. Approach B resulted in adequate quantitative results, but was considered a single compound method because it depends on cleavage of a thioester group, which is present in only a limited number of cephalosporin antibiotics. Approach C showed adequate quantitative results but, in contrast to approach B, it is applicable to a range of cephalosporin antibiotics. Therefore, it is applicable as a broad quantitative screening of cephalosporin compounds in poultry tissue samples to indicate off-label use of cephalosporins in poultry breeding. Based on this study, it was concluded that approach C is the most suitable to detect off-label use of a range of cephalosporin antibiotics.     

Electrochemical oxidation of alcohols on Pt–TiO2 binary electrodes

In this study Pt–TiO₂ binary electrodes were prepared by means of thermal decomposition of chloride precursors on Ti substrates, characterised by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), electrochemical techniques and CO stripping and used as anodes for alcohol oxidation. The minimization of the Pt loading without electrocatalytic activity losses was also explored. TiO₂ was chosen due to its chemical stability, low cost and excellent properties as substrate for Pt dispersion. It was found that TiO₂ loading up to 50% results in Electrochemically Active Surface (EAS) increase. The EAS of Pt(50%)-TiO₂(50%) was found to be almost one order of magnitude higher than that of pure Pt while the EAS of samples with Pt loading lower than 30% was negligible. The above conclusion has been confirmed both by following the charge of the reduction peak of platinum oxide and by CO stripping experiments. All samples have been evaluated during the electrochemical oxidation of methanol and ethanol. In both cases the Pt(50%)-TiO₂(50%) electrode had better electrocatalytic activity than the pure Pt anode. The observed higher performance of the binary electrodes was mainly attributed to the enhanced Pt dispersion as well as the formation of smaller Pt particles by the addition of TiO₂.     

Towards hydrogen production using a breathable electrode structure to directly separate gases in the water splitting reaction

A novel electrode design to directly separate the gases and improve the efficiency of the water splitting reaction is described. In this work, platinum was used as a model catalyst, deposited on porous membranes with different pore size and shape. The O₂ evolution rate was monitored at the gaseous side of these breathable electrodes. We show that the hydrophobic Goretex^® membrane electrodes provide a highly efficient removal of the gases, breathing out 92% of expected O₂ during water splitting, and thereby also largely avoiding the well known migration of oxygen to the cathode in the absence of a separator in the cell. The breathable structure is also shown to operate as a hydrogen electrode. The ability to separate the two gases, without the need for a separator, decreases gas cross-over and thereby enhances the coloumbic efficiency. Merging this approach with catalysts and photocatalysts of a variety of types e.g. non-precious metal and metal oxides will allow fabrication of cost efficient and straightforward water splitting devices.     

Enhanced catalytic activity towards hydrogen evolution on polythiophene via microstructural changes

The discovery of poly(2,2′-bithiophene) (PBTh) as a photo-electrochemical catalyst for the hydrogen evolution reaction (HER) presents a novel electrode material for the transition to a sustainable hydrogen energy economy. Nonetheless, it remains limited by a low hydrogen evolution rate. We here investigate two methods in which to increase the catalytic activity of PBTh: using humidity for alternative templating and substrate roughening. It was found that exposure of the oxidant solution to humidity prior to polymerisation causes the formation of new microstructures that was found to increase catalytic activity of the PBTh film by over four times, from 14 to 57 µA cm^-2. It was also found that control of the atmospheric environment proved critical. In contrast, the roughening of the substrate did not consistently lead to an increase in performance and was attributed to poor adhesion and electrical contact of the film to the substrate. During these tests however, a photo-electrocatalytic current of 150 μA cm^?2 was recorded in pH 7.0 and an underpotential of 0.12 V on an un-roughened PBTh sample. This represents the highest reported value for PBTh thus far and a significant achievement for its further development towards a low-cost and efficient HER catalyst.     

Generation of reduced dynamic thermal models of electronic systems from time constant spectra of transient temperature responses

This paper concerns the problem of generating reduced dynamic thermal models whose elements have physical interpretation. The compact models of an electronic system are generated here based on the analysis of the time constant spectra of system transient thermal responses. The proposed method is illustrated on a practical example of an integrated power amplifier with a heat sink. The experiments demonstrate the influence of contact resistance and cooling conditions on the resulting values of thermal model elements.     

Dialysate saving by automated control of flow rates: comparison between individualized online hemodiafiltration and standard hemodialysis

Cost reduction and quality improvement seem to be conflicting issues. However, online hemodiafiltration (oHDF) with new automatic functions offers a cost‐efficient therapy compared to hemodialysis (HD). Seven dialysis centers conducted a randomized clinical trial with cross‐over design: high‐flux HD vs. postdilutional oHDF with functions coupling both dialysate and substitution flow rates to blood flow rates. During the 6 weeks of the study, all treatment parameters remained unchanged for HD and oHDF, apart from dialysate and substitution flow rate. Treatment data were recorded during each treatment, and predialytic and postdialytic concentrations of urea were recorded at the end of each study phase. The analysis involved 956 treatments of 54 patients. The mean dialysate consumption was 123.2 ± 6.4 l for HD and 113.4 ± 14.9 l for oHDF (p < 0.0001), the mean dialysis dose was 1.42 ± 0.23 for HD and 1.47 ± 0.26 for oHDF (p < 0.0001); oHDF resulted in a lower dialysate consumption (8.0% less) and a slightly increased dialysis dose (Kt/V 3.5% higher) compared to HD. oHDF with the investigated automatic functions offers substantial savings in dialysate consumption without decreasing dialysis dose.     

Fabrication of planar polymer waveguides for evanescent-wave sensing in aqueous environments

We present a detailed account of processing issues related to fabrication of optical waveguide sensors intended for evanescent-wave sensing in aqueous solutions or surface-bound fluorescence excitation in biological samples. The waveguides consist of a polymer layer on top of a fluoropolymer (Cytop^™) cladding. The fluoropolymer is closely index-matched to water, providing a symmetric cladding environment which simplifies optical excitation and provides tunability in penetration depth not available with other evanescent-wave techniques. We present methods of controlling the wettability of the fluoropolymer surface and improving adhesion to the core waveguide layer. Furthermore, we demonstrate the application of the waveguide structure to fluorescence imaging of cultured cells.