Wear of polycrystalline boron nitride tool during the friction stir welding of steel

The wear issue of a polycrystalline boron nitride (PCBN) tools during the friction stir welding of two grades of steel, DH36 and EH46, was studied. Two welding traverse and tool rotational speeds were used when welding the DH36 steel. A low tool speed (200RPM, 100 mm/min) and a high tool speed (550RPM, 400 mm/min) were denoted by W1D and W2D, respectively. Nine welding conditions were applied to the welding of EH46 steel plate including seven plunge/dwell trials (W1E–W7E) and two steady-state trials (W8E and W9E). SEM–EDS and XRD tests were applied in order to reveal the boronitride (BN) particles inside the welded joints, and the percentage (%) of BN was calculated according to the standard quantitative metallographic technique. The findings showed that tool wear increases when the tool rotational speed increases as a result of binder softening which is a function of the peak temperature (exceeds 1250 °C) at the tool/workpiece interface. When considering the EH46 steel trials, it was found that an increase in the tool traverse speed in friction stir welding caused a significant tool wear with 4.4% of BN in the top of the stirred zone of W9E compared to 1.1% volume fraction of BN in W8E which was attributed to the higher thermomechanical action on the PCBN tool surface. Tool wear was also found to increase with an increase in tool plunge depth as a result of the higher contact between the surface of friction stir welding tool and the workpiece

High accuracy genotyping directly from genomic DNA using a rolling circle amplification based assay

BACKGROUND: Rolling circle amplification of ligated probes is a simple and sensitive means for genotyping directly from genomic DNA. SNPs and mutations are interrogated with open circle probes (OCP) that can be circularized by DNA ligase when the probe matches the genotype. An amplified detection signal is generated by exponential rolling circle amplification (ERCA) of the circularized probe. The low cost and scalability of ligation/ERCA genotyping makes it ideally suited for automated, high throughput methods. RESULTS: A retrospective study using human genomic DNA samples of known genotype was performed for four different clinically relevant mutations: Factor V Leiden, Factor II prothrombin, and two hemochromatosis mutations, C282Y and H63D. Greater than 99% accuracy was obtained genotyping genomic DNA samples from hundreds of different individuals. The combined process of ligation/ERCA was performed in a single tube and produced fluorescent signal directly from genomic DNA in less than an hour. In each assay, the probes for both normal and mutant alleles were combined in a single reaction. Multiple ERCA primers combined with a quenched-peptide nucleic acid (Q-PNA) fluorescent detection system greatly accellerated the appearance of signal. Probes designed with hairpin structures reduced misamplification. Genotyping accuracy was identical from either purified genomic DNA or genomic DNA generated using whole genome amplification (WGA). Fluorescent signal output was measured in real time and as an end point. CONCLUSIONS: Combining the optimal elements for ligation/ERCA genotyping has resulted in a highly accurate single tube assay for genotyping directly from genomic DNA samples. Accuracy exceeded 99 % for four probe sets targeting clinically relevant mutations. No genotypes were called incorrectly using either genomic DNA or whole genome amplified sample

Supernova neutrino burst detection with the Deep Underground Neutrino Experiment

The Deep Underground Neutrino Experiment (DUNE), a 40-kton underground liquid argon time projection chamber experiment, will be sensitive to the electron-neutrino flavor component of the burst of neutrinos expected from the next Galactic core-collapse supernova. Such an observation will bring unique insight into the astrophysics of core collapse as well as into the properties of neutrinos. The general capabilities of DUNE for neutrino detection in the relevant few- to few-tens-of-MeV neutrino energy range will be described. As an example, DUNE's ability to constrain the νe spectral parameters of the neutrino burst will be considered