Comparing a recursive digital filter with the moving-average andsequential probability-ratio detection methods for SNM portal monitors

A recursive digital filter proposed as a detection method for French special nuclear material monitors is compared with detection methods that employ a moving-average scaler or a sequential probability-ratio test. Each of the nine test subjects repeatedly carried a test source through a walk-through portal monitor that had the same nuisance-alarm rate with each method. It is shown that the average detection probability for the test source is also the same for each method. The recursive digital filter may have one drawback: its exponentially decreasing response to past radiation intensity prolongs the impact of any interference from radiation sources or radiation-producing machinery. The influence of each test subject on the monitor's operation was examined by measuring individual attenuation factors for background and source radiation. The subjects' attenuation factors are ranked against their individual probabilities for detecting the test source. The one inconsistent ranking is attributed to the subject's unusually long stride     

Semi-Automated High-Throughput Substrate Screening Assay for Nucleoside Kinases

Nucleoside kinases (NKs) are key enzymes involved in the in vivo phosphorylation of nucleoside analogues used as drugs to treat cancer or viral infections. Having different specificities, the characterization of NKs is essential for drug design and nucleotide analogue production in an in vitro enzymatic process. Therefore, a fast and reliable substrate screening method for NKs is of great importance. Here, we report on the validation of a well-known luciferase-based assay for the detection of NK activity in a 96-well plate format. The assay was semi-automated using a liquid handling robot. Good linearity was demonstrated (r² > 0.98) in the range of 0–500 µM ATP, and it was shown that alternative phosphate donors like dATP or CTP were also accepted by the luciferase. The developed high-throughput assay revealed comparable results to HPLC analysis. The assay was exemplarily used for the comparison of the substrate spectra of four NKs using 20 (8 natural, 12 modified) substrates. The screening results correlated well with literature data, and additionally, previously unknown substrates were identified for three of the NKs studied. Our results demonstrate that the developed semi-automated high-throughput assay is suitable to identify best performing NKs for a wide range of substrates.     

Optimization of Vapor Compression for Cost Savings in Drying Processes

Energy saving from vapor compression entails additional costs for the vapor compressors and larger heating surfaces of the drier. Thus, they are offset to a certain degree. An analytically solvable mathematical model is presented for determining the maximum cost savings with the optimum pressure ratio of the compression. According to this, the maximum cost savings depends only on five parameters, namely, the specific cost ratios of drier to fuel and compressors to fuel, the price ratio of power and fuel, the difference between the moisture contents of the inlet and outlet of the drier and the pressure level inside the drier. Above dy = 1 kg_H2O/kg_DS (DS – dry substance) the specific cost ratio of drier to fuel proves to be dominant and thus decisively determines the optimum pressure ratio. Hence, one can explain why, e.g., in the case of brown coal drying higher pressure ratios are required than in the case of sludge drying and here again higher ones than in the case of evaporization processes for liquids.