Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Multiplicative potentials, appropriate for adding to the non-multiplicative fractional orbital exchange term in the Kohn-Sham equations, are determined from correlated ab initio electron densities. The potentials are examined graphically and are used in conjunction with conventional thermochemical data to determine a new hybrid exchange-correlation functional, denoted B97-2. Calculations using B97-2 are compared with those from ͑a͒ the B97-1 functional ͓J. Chem. Phys. 109, 6264 ͑1998͔͒, which has the same functional form and fraction of orbital exchange, but was fitted to just thermochemical data; and ͑b͒ the widely used B3LYP functional ͓J. Chem. Phys. 98, 5648 ͑1993͔͒. B97-2 atomization energies are close to those from B97-1; total electronic energies and ionization potentials are less accurate, but remain an improvement over B3LYP. Molecular structures from all three functionals are comparable. Static isotropic polarizabilities improve from B3LYP to B97-1 to B97-2; the B97-2 functional underestimates experimental values, which is consistent with the neglect of zero-point vibrational corrections. NMR shielding constantsdetermined as the conventional second derivative of the electronic energy-improve from B3LYP to B97-1 to B97-2. Shieldings determined directly from these DFT electron densities using the recently proposed MKS approach ͓Chem. Phys. Lett. 337, 341 ͑2001͔͒ are two to three times more accurate than the conventional shieldings, and exhibit an analogous improvement across the three functionals. Classical reaction barriers for sixteen chemical reactions improve significantly from B3LYP to B97-1 to B97-2. The introduction of multiplicative potentials into semi-empirical hybrid functional development therefore appears beneficial.

We determine properties of Saturn's planetary period oscillations from Cassini magnetic measurements over the~2-year interval from September 2015 to end of mission in September 2017, spanning Saturn northern summer solstice in May 2017. Phases of the northern system oscillations are derived over the whole interval, while those of the southern system are not discerned in initial equatorial data due to too low amplitude relative to the northern, but are determined once southern polar data become available from inclined orbits beginning May 2016. Planetary period oscillation periods are shown to be almost constant over these intervals at~10.79 hr for the northern system and~10.68 hr for the southern, essentially unchanged from values previously determined after the periods reversed in 2014. High cadence phase and amplitude data obtained from the short-period Cassini orbits during the mission's last 10 months newly reveal the presence of dual modulated oscillations varying at the beat period of the two systems (~42 days) on nightside polar field lines in the vicinity (likely either side) of the open-closed field boundary. The modulations differ from those observed previously in the equatorial region, indicative of a reversal in sign of the radial component oscillations, but not of the colatitudinal component oscillations. Brief discussion is given of a possible theoretical scenario. While weak equatorial beat modulations indicate a north/south amplitude ratio >5 early in the study interval, polar and equatorial region modulations suggest a ratio~1.4 during the later interval, indicating a significant recovery of the southern system.

We newly analyze Cassini magnetic field data from the 2012/2013 Saturn northern spring interval of highly inclined orbits and compare them with similar data from late southern summer in 2008, thus providing unique information on the seasonality of the currents that couple momentum between Saturn's ionosphere and magnetosphere. Inferred meridional ionospheric currents in both cases consist of a steady component related to plasma subcorotation, together with the rotating current systems of the northern and southern planetary period oscillations (PPOs). Subcorotation currents during the two intervals show opposite north-south polar region asymmetries, with strong equatorward currents flowing in the summer hemispheres but only weak currents flowing to within a few degrees of the open-closed boundary (OCB) in the winter hemispheres, inferred due to weak polar ionospheric conductivities. Currents peak at 1 MA rad À1 in both hemispheres just equatorward of the open-closed boundary, associated with total downward polar currents~6 MA, then fall across the narrow auroral upward current region to small values at subauroral latitudes. PPO-related currents have a similar form in both summer and winter with principal upward and downward field-aligned currents peaking at~1.25 MA rad À1 being essentially collocated with the auroral upward current and approximately equal in strength. Though northern and southern PPO currents were approximately equal during both intervals, the currents in both hemispheres were dual modulated by both systems during 2012/2013, with approximately half the main current closing in the opposite ionosphere and half cross field in the magnetosphere, while only the northern hemisphere currents were similarly dual modulated in 2008.

We examine the final 44 orbits of the Cassini spacecraft traversing the midnight sector of Saturn's magnetosphere to distances of~21 Saturn radii, to investigate responses to heliospheric conditions inferred from model solar wind and Cassini galactic cosmic ray flux data. Clear storm responses to anticipated magnetospheric compressions are observed in magnetic field and energetic particle data, together with Saturn kilometric radiation (SKR), auroral hiss, and ultraviolet auroral emissions. Most compression events are associated with corotating interaction regions, producing~2-3.5 day intervals of magnetospheric activity that are recurrent with the~26 day solar rotation period (one or two such events per rotation), though one on the final pass is related to a nonrecurrent interplanetary shock possibly associated with an earlier X-class solar flare. The response to compressions is modulated by the concurrent relative phasing of the northern and southern planetary period oscillation (PPO) systems, with long (>1 planetary rotation) SKR low-frequency extension (LFE) intervals associated with strong field-aligned coupling currents being favored when the two PPO systems act together to thin and thicken the tail plasma sheet during each PPO cycle. LFE onsets/intensifications are then favored at thin plasma sheet phases most unstable to reconnection, producing energetic nightside particle injections and poleward contractions of dawn-brightened auroras. Correspondingly, solar rotation recurrent intervals of magnetospheric quiet conditions also occur with weak energetic particle fluxes and auroral emissions, associated with extended solar wind rarefactions. Overall, the results emphasize how strongly activity in Saturn's magnetosphere is modulated by concurrent heliospheric conditions.

We overview the properties of the azimuthal magnetic fields observed during the periapsis passes of the final 23 orbits of the Cassini spacecraft, including the partial orbit at end of mission, on near equatorial field lines passing inside of Saturn's D ring. The signatures are variable in form and amplitude, though generally approximately symmetric about the point where the spacecraft trajectory lies tangent to a flux shell, corresponding to where the ionospheric field line feet map closest to the equator, consistent with the effect of interhemispheric field‐aligned currents. The perturbations usually begin and end near symmetrically at some point on field lines threading the D ring and extend into the interior region, but in no case do they clearly extend outward onto field lines passing through the C ring. About 35% of cases display a ~20‐40 nT single positive central field peak indicative of southward field‐aligned current flow, while a further ~30% display two or three weaker ~10‐20 nT positive peaks indicative of multiple sheets of northward and southward current. Significant smaller‐scale >5 nT peak‐to‐peak field fluctuations are commonly superposed. A further ~20% of cases exhibit unique profiles within the data set, including two with ~20‐30 nT negative fields and two with only <10 nT fluctuating fields. The variable nature of the signatures is not connected with the pass altitude, local time, planetary period oscillation phase, or D68 ringlet phase but may relate to variable structured thermospheric winds and/or ionospheric conductivities that suggest a significant dynamical role for D ring‐atmosphere interactions.

Thiol-terminated single-stranded deoxyribonucleic acids (ssDNA) can be immobilized onto pulsed plasma deposited poly(allylmercaptan) surfaces via disulfide bridge chemistry and are found to readily undergo nucleic acid hybridization. Unlike other methods for oligonucleotide attachment to solid surfaces, this approach is shown to be independent of substrate material or geometry, and amenable to highly efficient rewriting.

We conduct a statistical analysis of 2,094 reconnection events in Saturn's near-equatorial magnetotail previously identified in Cassini magnetometer data from intervals during 2006 and 2009/2010. These consist of tailward propagating plasmoids and planetward propagating dipolarizations, with approximately twice as many plasmoids as dipolarizations. We organize these by three related planetary period oscillation (PPO) phase systems, the northern and southern PPO phases relative to noon, the same phases retarded by a radial propagation delay, and the local retarded phases that take account of the azimuth (local time) of the observation. Clear PPO modulation is found for both plasmoid and dipolarization events, with local retarded phases best organizing the event data with the modulation in event frequency propagating across the tail as the PPO systems rotate. This indicates that the events are localized in azimuth, rather than simultaneously affecting much of the tail width. Overall, events occur preferentially by factors of 3 at northern and southern phases where the tail current sheet is expected locally to be thinnest in the PPO cycle, with field lines contracting back from their maximum radial displacement, compared with the antiphase conditions. Separating the events into those representing the start of independent reconnection episodes, occurring at least 3 hr after the last, and events in subsequent clusters, shows that the above phases are predominantly characteristic of the majority cluster events. The phases at the start of independent reconnection episodes are typically~60°earlier.Also relevant are observations of reconnection-related phenomena in the magnetic field and plasma in Saturn's magnetotail. Specifically, reconnection within the near-planet plasma sheet pinches off sections of BRADLEY ET AL. 9476

We study Saturn's nightside ring current during Cassini's Grand Finale.