Environmental DNA Based Surveillance for the Highly Invasive Carpet Sea Squirt Didemnum vexillum : A Targeted Single-Species Approach

Funding Information: The authors would like to thank the site operators, owners and Solway Firth Partnership for allowing access and sample collection at studied sites visited during this study. Thanks also to Frank Armstrong, Katy Beaton, Maria Campbell, Pablo Dias, James Dooley, Judith Horrill, Nial McLeod, Warren Murray, Andrea Taylor, Joe Triscott, and Bill Turrell for contributing to field work and sample collection. The authors thank National Museums Scotland and particularly Fiona Ware for the loan of reference material (specimen register number NMS.Z.2015.82.8, 9 and 14 and NMS.Z.2018.2.2) which was used in the present study. KS thank the Japan Society for the Promotion of Science for post-doctoral fellowship funding.Peer reviewedPublisher PD

Enhanced production of HD and D_2 molecules on small dust grains in diffuse clouds

Motivated by recent observations of deuterated molecules in the interstellar medium, we examine the production of HD and D$_2$ molecules on dust grain surfaces. A mechanism for the enhanced production of these deuterated molecules is studied. This mechanism applies on grain surfaces on which D atoms stick more strongly than H atoms, under conditions of low flux and within a suitable range of temperatures. It is shown that under these conditions the production rates of HD and D$_2$ are greatly enhanced (vs. the H$_2$ production rate) compared with the expected rates based on the adsorption of gas-phase atomic abundances of D and H. The enhancement in the formation rate of HD is comparable with the enhancement due to gas-phase ion-molecule reactions in diffuse clouds.Comment: This is a preprint of an article accepted for publication in Monthly Notices of The Royal Astromnomical Societ

Dynamics and Depletion in Thermally Supercritical Starless Cores

In previous studies we identified two classes of starless cores, thermally subcritical and supercritical, distinguished by different dynamical behavior and internal structure. Here we study the evolution of the dynamically-unstable, thermally-supercritical cores by means of a numerical hydrodynamic simulation that includes radiative equilibrium and simple molecular chemistry. We use our non-LTE radiative transfer code MOLLIE to predict observable CO and N2H+ line spectra, including the non-LTE hyperfine ratios of N2H+, during the contraction. These are compared against observations of the starless core L1544.Comment: accepted for publication in MNRA

The CAR–mRNA Interaction Surface Is a Zipper Extension of the Ribosome A Site

The ribosome CAR interaction surface behaves as an extension of the decoding center A site and has H-bond interactions with the +1 codon, which is next in line to enter the A site. Through molecular dynamic simulations, we investigated the codon sequence specificity of this CAR–mRNA interaction and discovered a strong preference for GCN codons, suggesting that there may be a sequence-dependent layer of translational regulation dependent on the CAR interaction surface. Dissection of the CAR–mRNA interaction through nucleotide substitution experiments showed that the first nucleotide of the +1 codon dominates over the second nucleotide position, consistent with an energetically favorable zipper-like activity that emanates from the A site through the CAR–mRNA interface. Moreover, the CAR/+1 codon interaction is affected by the identity of nucleotide 3 of +1 GCN codons, which influences the stacking of G and C. Clustering analysis suggests that the A-site decoding center adopts different neighborhood substates that depend on the identity of the +1 codon

Instantaneous 4D micro-particle image velocimetry (µPIV) via multifocal microscopy (MUM)

Multifocal microscopy (MUM), a technique to capture multiple fields of view (FOVs) from distinct axial planes simultaneously and on one camera, was used to perform micro-particle image velocimetry (µPIV) to reconstruct velocity and shear stress fields imposed by a liquid flowing around a cell. A diffraction based multifocal relay was used to capture images from three different planes with 630 nm axial spacing from which the axial positions of the flow-tracing particles were calculated using the image sharpness metric. It was shown that MUM can achieve an accuracy on the calculated velocity of around (0.52 ± 0.19) µm/s. Using fixed cells, MUM imaged the flow perturbations at sub-cellular level, which showed characteristics similar to those observed in the literature. Using live cells as an exemplar, MUM observed the effect of changing cell morphology on the local flow during perfusion. Compared to standard confocal laser scanning microscope, MUM offers a clear advantage in acquisition speed for µPIV (over 300 times faster). This is an important characteristic for rapidly evolving biological systems where there is the necessity to monitor in real time entire volumes to correlate the sample responses to the external forces

A bis-calix[4]arene-supported [Cu II16 ] cage

Reaction of 2,2'-bis-p-tBu-calix[4]arene (H8L) with Cu(NO3)2·3H2O and N-methyldiethanolamine (Me-deaH2) in a basic dmf/MeOH mixture affords [CuII16(L)2(Me-dea)4(μ4-NO3)2(μ-OH)4(dmf)3.5(MeOH)0.5(H2O)2](H6L)·16dmf·4H2O (4), following slow evaporation of the mother liquor. The central core of the metallic skeleton describes a tetracapped square prism, [Cu12], in which the four capping metal ions are the CuII ions housed in the calix[4]arene polyphenolic pockets. The [CuII8] square prism is held together "internally" by a combination of hydroxide and nitrate anions, with the N-methyldiethanolamine co-ligands forming dimeric [CuII2] units which edge-cap above and below the upper and lower square faces of the prism. Charge balance is maintained through the presence of one doubly deprotonated H6L2- ligand per [Cu16] cluster. Magnetic susceptibility measurements reveal the predominance of strong antiferromagnetic exchange interactions and an S = 1 ground state, while EPR is consistent with a large zero-field splitting