Flow beneath inland navigation vessels

Growing transportation rates and the subsequent growth in inland waterway transport have led to an increase in inland vessel sizes and draught. Due to the fluctuating water levels on rivers and these increasing draughts, the distance between the river bed and the ships are decreasing. Rijkswaterstaat wants to know the effects of sailing at these small underkeel clearances on river beds and ship manoeuvrability. In order to quantify these effects, more knowledge about the flow field beneath sailing vessels is required, as well as the effect of the flow field on erosion of bed material. Currently no methods exist to determine the flow field beneath vessels, only a few formulations for a single maximum velocity value are available, but these are not applicable at small underkeel clearances (h / T < 1.25). Also the effect on the river bed is fairly unknown. To quantify the different effects of small underkeel clearances on the flow field physical model tests (with a length scale of 30) have been performed at Deltares. During these experiments a ship was towed through the flume, and flow velocities and pressures on the bed were measured, as well as forces on the ship. Additional experiments have been performed to investigate the effect on a moveable bed with different bed forms. From the experiments, it was found that the most important parameters that influence the flow field beneath the keel are the bow shape and the underkeel clearance. Barge bows force more flow underneath the keel than conventional bows, and this results in higher bed velocities. Decreasing keel clearances also result in significantly higher velocities at the bed. However, for very small underkeel clearances the boundary layer on the ship will interact with the boundary layer on the bed. This results in flow blockage underneath the keel. As a result, the flow needs to divert to the sides, and the velocities underneath the keel decrease. The diversion of the flow to the sides is also known as the fanning-out effect. This effect has definitely been proved by the measurements from the experiments. The effect (transverse velocities) increases with decreasing keel clearance (due to boundary layer interaction) and also increases with increasing ship widths. During the experiments, erosion of bed material was clearly observed, and its effect increased with decreasing keel clearance. However, the underkeel clearance needs to be very small (h /UKC < 1.1) to give significant bed erosion. Due to the fanning-out effect and turbulence fluctuations, most sediment transport occurred immediately alongside the vessel, rather than underneath the keel. With bed forms such as dunes the erosion increased, due to erosion at the dune tops and deposition in the troughs (10 passages of a conventional vessel over a dune resulted in a decrease in dune height of 20%). For the removal of small shoals this might be interesting, although a small underkeel clearance is necessary. Barges are preferred over conventional vessels due to the higher velocities and increased turbulence intensity. From the measured velocities during the physical model tests a model has been developed to predict the flow field underneath sailing inland navigation vessels. There are separate models for conventional vessels and for barges. The model is able to accurately predict maximum velocities (in sailing direction as well as in transverse direction), as well as a transverse velocity distribution. Compared to the previous prediction methods, the newly developed model is preferable. The results are more accurate, and the model is more extensive, due to the inclusion of transverse velocities and velocity distributions. More validation is required however, due to the lack of other data sets.Hydraulic EngineeringCivil Engineering and Geoscience

Cellular Redox Profiling Using High-content Microscopy

Item does not contain fulltextReactive oxygen species (ROS) regulate essential cellular processes including gene expression, migration, differentiation and proliferation. However, excessive ROS levels induce a state of oxidative stress, which is accompanied by irreversible oxidative damage to DNA, lipids and proteins. Thus, quantification of ROS provides a direct proxy for cellular health condition. Since mitochondria are among the major cellular sources and targets of ROS, joint analysis of mitochondrial function and ROS production in the same cells is crucial for better understanding the interconnection in pathophysiological conditions. Therefore, a high-content microscopy-based strategy was developed for simultaneous quantification of intracellular ROS levels, mitochondrial membrane potential (DeltaPsim) and mitochondrial morphology. It is based on automated widefield fluorescence microscopy and image analysis of living adherent cells, grown in multi-well plates, and stained with the cell-permeable fluorescent reporter molecules CM-H2DCFDA (ROS) and TMRM (DeltaPsim and mitochondrial morphology). In contrast with fluorimetry or flow-cytometry, this strategy allows quantification of subcellular parameters at the level of the individual cell with high spatiotemporal resolution, both before and after experimental stimulation. Importantly, the image-based nature of the method allows extracting morphological parameters in addition to signal intensities. The combined feature set is used for explorative and statistical multivariate data analysis to detect differences between subpopulations, cell types and/or treatments. Here, a detailed description of the assay is provided, along with an example experiment that proves its potential for unambiguous discrimination between cellular states after chemical perturbation

A design for external quality assessment for the analysis of thiopurine drugs: pitfalls and opportunities

Background: For the analysis of 6-thioguanine nucleotides (6-TGN) and 6-methylmercaptopurine ribonucleotides (6-MMPR), no external quality assessment scheme (EQAS) is currently available and no quality control samples can be made because of the absence of pure substances. An experimental design is tested to compare laboratory analytical results. Methods: In this EQAS, participating laboratories were asked to select patient samples from their routine analysis and exchange these with a coupled laboratory. Because of large differences in results between laboratories, all standard operating procedures were reviewed, revealing that the origin of these differences could be in the method of hydrolysis and the preparation of calibrators. To investigate the contribution of the calibrators to these differences, one participating laboratory was asked to prepare a batch of calibrators to be shipped to the participating laboratories for analysis. Results: Results for 6-TGN differed more between laboratories, compared with results for 6-MMPR. For 6-TGN and 6-MMPR 43% and 24% of the results, respectively, were out of the 80%-120% range. When correcting the results from the exchange of the patient samples with the results of the calibrators, the mean absolute difference for 6-TGN improved from 24.8% to 16.3% (p <0.001), while the results for 6-MMPR worsened from 17.3% to 20.0% (p = 0.020). Conclusions: This first EQAS for thiopurine drugs shows that there is a difference between laboratories in the analysis of 6-TGN, and to a lesser extent in the analysis of 6-MMPR. This difference for 6-TGN can partially be explained by the use of in-house-prepared calibrators that differ among the participants

Melittin disruption of raft and non-raft-forming biomimetic membranes:A study by quartz crystal microbalance with dissipation monitoring

In this work we examine the role of lateral phase separation in cholesterol-containing biomimetic membranes on the disrupting action of melittin using a label-free surface-sensitive technique, quartz crystal microbalance with dissipation monitoring (QCM-D). Melittin disruption mechanisms depend strongly on the geometry of the lipid layer; however, despite the interplay between layer geometry/thickness and melittin activity, results indicate that the presence of lipid heterogeneity and lateral phase separation greatly influences the disrupting efficiency of melittin. In homogeneous non-raft forming membranes with high cholesterol content, melittin spontaneous activity is strongly delayed compared to heterogeneous raft-forming systems with the same amount of cholesterol. These results confirm the importance of lateral phase separation as a determinant factor in peptide activity. The information provided can be used for the design of more efficient antimicrobial peptides and the possibility of using a label-free approach for tailored-membranes and interactions with other types of peptides, such as amyloid peptides

Melittin disruption of raft and non-raft-forming biomimetic membranes: A study by quartz crystal microbalance with dissipation monitoring

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Commutability of proficiency testing material containing amitriptyline and nortriptyline: A study within the framework of the Dutch Calibration 2.000 project

Background: External quality assessment schemes (EQAS) can provide important information regarding accuracy and comparability of different measurement methods if the sample matrices are composed of commutable material. The aim of this study was to assess the commutability of different matrices for the material used in an EQAS for amitriptyline and nortriptyline. Methods: Proficiency testing material (PTM) and patient samples containing amitriptyline and nortriptyline were prepared, collected, pooled, and distributed to participating laboratories for analysis. Low, medium and high concentrations of both drugs in liquid pooled human, lyophilized human and lyophilized bovine serum were tested in this study. The measurement deviation of the PTM results to the patient serum regression line were normalized by dividing trough the average within-laboratory SD (SDwl) derived from the results reported in the official EQAS, resulting in a relative residual. The commutability decision limit was set at 3 SDwl. Results: With 10 laboratories participating in this study, 45 laboratory couples were formed. All matrix types delivered several relative residuals outside the commutability decision limit. The number and the magnitude of relative residuals for both drugs were lower for liquid human sera as compared to lyophilized human and bovine sera. Conclusions: The PTM used for amitriptyline and nortriptyline is preferably prepared with human serum, although not all relative residuals are within the commutability decision limit

Commutability of proficiency testing material containing amitriptyline and nortriptyline:A study within the framework of the Dutch Calibration 2.000 project

BACKGROUND: External quality assessment schemes (EQAS) can provide important information regarding accuracy and comparability of different measurement methods if the sample matrices are composed of commutable material. The aim of this study was to assess the commutability of different matrices for the material used in an EQAS for amitriptyline and nortriptyline. METHODS: Proficiency testing material (PTM) and patient samples containing amitriptyline and nortriptyline were prepared, collected, pooled, and distributed to participating laboratories for analysis. Low, medium and high concentrations of both drugs in liquid pooled human, lyophilized human and lyophilized bovine serum were tested in this study. The measurement deviation of the PTM results to the patient serum regression line were normalized by dividing trough the average within-laboratory SD (SDwl) derived from the results reported in the official EQAS, resulting in a relative residual. The commutability decision limit was set at 3 SDwl. RESULTS: With 10 laboratories participating in this study, 45 laboratory couples were formed. All matrix types delivered several relative residuals outside the commutability decision limit. The number and the magnitude of relative residuals for both drugs were lower for liquid human sera as compared to lyophilized human and bovine sera. CONCLUSIONS: The PTM used for amitriptyline and nortriptyline is preferably prepared with human serum, although not all relative residuals are within the commutability decision limit

A Multilaboratory Commutability Evaluation of Proficiency Testing Material for Carbamazepine and Valproic Acid:A Study Within the Framework of the Dutch Calibration 2000 Project

Background: Medical laboratories are required to participate in interlaboratory comparisons of the analyses they perform. The materials used in these comparisons need to be of sufficient quality so that the comparison provides a picture of the performances. One of the main characteristics of the testing material is commutability, which is the ability of a material to yield the same numerical relationships between results of measurements as those relationships obtained when the same procedures are applied to patient samples. The aim of this study was to assess the commutability of 3 different matrices for the preparation of proficiency testing material (PTM) for the analysis of carbamazepine and valproic acid. Methods: Patient samples and PTM containing various concentrations of carbamazepine and valproic acid were collected, prepared, and shipped to different laboratories for analysis. Reported results for patient samples from each laboratory were plotted against results for patient samples of each of the other laboratories, and the corresponding regression line was calculated. The distance of results from PTM to the regression line is a measure for commutability. The distance is expressed as a multiple of the SDwl (average within-laboratory SD as calculated from external quality assessment scheme results) and referred to as relative residual. A commutability decision limit of 2 SDwl was set. Results: For carbamazepine and valproic acid, a total of 78 and 105 laboratory couples respectively could be formed. The number of relative residuals for liquid human serum outside the commutability decision limit was 1, 4, and 0 for low, medium, and high concentrations of carbamazepine, respectively and 3, 1, and 0 for low, medium, and high concentrations of valproic acid, respectively. In both liquid and lyophilized bovine sera, the number of relative residuals outside the commutability decision limit was between 2 and 15 and between 6 and 21 for carbamazepine and valproic acid, respectively. Conclusions: Although not all results for PTM with carbamazepine and valproic acid are within the commutability decision limits, a preference for human serum can be seen

Commutability of proficiency testing material containing tobramycin:a study within the framework of the Dutch Calibration 2.000 project

Background: Results from external quality assessment schemes (EQASs) can provide information about accuracy and comparability of different measurement methods, provided that the material used in these schemes behave identical to patient samples among the different methods, a characteristic also known as commutability. The aim of this study was to assess the commutability of different matrices for the material used in an EQAS for tobramycin. Methods: Proficiency testing material (PTM) and patient samples containing tobramycin were prepared, collected, pooled, and distributed to participating laboratories for analysis. Low, medium, and high tobramycin concentrations in liquid human, liquid bovine and lyophilized bovine serum were tested in this study. The patient serum results of every laboratory were plotted against each of the other laboratories, and the distances of the PTM results to the patient serum regression line were calculated. For comparison, these distances were divided by the average within-laboratory standard deviation (SDwl) of the results reported in the official EQAS for tobramycin, resulting in a relative residual. The commutability decision limit was set at 3 SDwl. Results: With 10 laboratories participating in this study, 45 laboratory couples were formed. For human serum, only one relative residual for high concentrations of tobramycin was found outside the commutability decision limit. For liquid and lyophilized bovine sera, the number of relative residuals outside the decision limit was between 15 and 18 for low, medium, and high tobramycin concentrations. Conclusions: The PTM used for tobramycin is preferably prepared with human serum