Hidden in Plain Sight: The Overlooked Influence of the Cs+ Substructure on Transformations in Cesium Lead Halide Nanocrystals

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Computational approach for calculating the probability of eukaryotic translation initiation from ribo-seq data that takes into account leaky scanning

BACKGROUND: Ribosome profiling (ribo-seq) provides experimental data on the density of elongating or initiating ribosomes at the whole transcriptome level that can be potentially used for estimating absolute levels of translation initiation at individual Translation Initiation Sites (TISs). These absolute levels depend on the mutual organisation of TISs within individual mRNAs. For example, according to the leaky scanning model of translation initiation in eukaryotes, a strong TIS downstream of another strong TIS is unlikely to be productive, since only a few scanning ribosomes would be able to reach the downstream TIS. In order to understand the dependence of translation initiation efficiency on the surrounding nucleotide context, it is important to estimate the strength of TISs independently of their mutual organisation, i.e. to estimate with what probability a ribosome would initiate at a particular TIS. RESULTS: We designed a simple computational approach for estimating the probabilities of ribosomes initiating at individual start codons using ribosome profiling data. The method is based on the widely accepted leaky scanning model of translation initiation in eukaryotes which postulates that scanning ribosomes may skip a start codon if the initiation context is unfavourable and continue on scanning. We tested our approach on three independent ribo-seq datasets obtained in mammalian cultured cells. CONCLUSIONS: Our results suggested that the method successfully discriminates between weak and strong TISs and that the majority of numerous non-AUG TISs reported recently are very weak. Therefore the high frequency of non-AUG TISs observed in ribosome profiling experiments is due to their proximity to mRNA 5′-ends rather than their strength. Detectable translation initiation at non-AUG codons downstream of AUG codons is comparatively infrequent. The leaky scanning method will be useful for the characterization of differences in start codon selection between tissues, developmental stages and in response to stress condition

Bazhenov Fm Classification Based on Wireline Logs

This paper considers the main aspects of Bazhenov Formation interpretation and application of machine learning algorithms for the Kolpashev type section of the Bazhenov Formation, application of automatic classification algorithms that would change the scale of research from small to large. Machine learning algorithms help interpret the Bazhenov Formation in a reference well and in other wells. During this study, unsupervised and supervised machine learning algorithms were applied to interpret lithology and reservoir properties. This greatly simplifies the routine problem of manual interpretation and has an economic effect on the cost of laboratory analysis

Inductively coupled plasma mass spectrometer with axial field in a quadrupole reaction cell

AbstractA novel reaction cell for ICP-MS with an electric field provided inside the quadrupole along its axis is described. The field is implemented via a DC bias applied to additional auxiliary electrodes inserted between the rods of the quadrupole. The field reduces the settling time of the pressurized quadrupole when its mass bandpass is dynamically tuned. It also improves the transmission of analyte ions. It is shown that for the pressurized cell with the field activated, the recovery time for a change in quadrupole operating parameters is reduced to <4 ms, which allows fast tuning of the mass bandpass in concert with and at the speed of the analyzing quadrupole. When the cell is operated with ammonia, the field reduces ion-ammonia cluster formation, further enhancing the transmission of atomic ions that have a high cluster formation rate. Ni·(NH3)n+ cluster formation in a cell operated with a wide bandpass (i.e., Ni+ precursors are stable in the cell) is shown to be dependent on the axial field strength. Clusters at n = 2–4 can be suppressed by 9, 1200, and >610 times, respectively. The use of a retarding axial field for in-situ energy discrimination against cluster and polyatomic ions is shown. When the cell is pressurized with O2 for suppression of 129Xe+, the formation of 127IH2+ by reactions with gas impurities limits the detection of 129I to isotopic abundance of ∼10−6. In-cell energy discrimination against 127IH2+ utilizing a retarding axial field is shown to reduce the abundance of the background at m/z = 129 to ca. 3 × 10−8 of the 127I+ signal. In-cell energy discrimination against 127IH2+ is shown to cause less I+ loss than a post-cell potential energy barrier for the same degree of 127IH2+ suppression