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Abstract Molecular observations of four planetary nebulae (PNe), M4-17, Hu 1-1, M1-59, and Na 2, were conducted at 1–3 mm using the Arizona Radio Observatory’s 12 m antenna and Submillimeter Telescope, and the Institut de Radioastronomie Millimétrique 30 m Telescope. Toward M4-17, HNC (J= 3 → 2), CCH (N= 2 → 1,N= 3 → 2), CN (N= 1 → 0,N= 2 → 1), H₂CO (J_Ka,Kc= 2_1,2→ 1_1,1,J_Ka,Kc= 2_0,2→ 1_0,1,J_Ka,Kc= 2_1,1→ 1_1,0), CS (J= 3 → 2,J= 5 → 4), and H¹³CN (J= 2 → 1) were detected. An almost identical set of transitions was identified toward Hu 1-1. Moreover, c–C₃H₂was detected in Hu 1-1 via three 2 mm lines:J_Ka,Kc= 3_1,2→ 2_2,1,J_Ka,Kc= 4_1,4→ 3_0,3, andJ_Ka,Kc= 3_{2, 2}→ 2_1,1. HNC, CCH, CN, CS, and H¹³CN were found in M1-59, as well as H₂S via itsJ_Ka,Kc= 1_1,0→ 1_0,1line—the first detection of this key sulfur species in PNe. In addition, CCH and CN were identified in the 27,000 yr old Na 2. Among these four sources, CN and CCH were the most prevalent molecules (after CO and H₂) with fractional abundances, relative to H₂, off∼ 0.9–7.5 × 10⁻⁷and 0.8–7.5 × 10⁻⁷, respectively. CS and HNC have abundances in the rangef∼ 0.5–5 × 10⁻⁸, the latter resulting in HCN/HNC ∼ 3 across all three PNe. The unusual species H₂CO, c–C₃H₂, and H₂S hadf∼ 3–4 × 10⁻⁷, 10⁻⁸, and 6 × 10⁻⁸. This study suggests that elliptical PNe such as Hu 1-1 can have a diverse molecular composition. The presence of CN, CCH, and HCO⁺in Na 2, with comparable abundances to younger PNe, demonstrates that molecular content is maintained into the late PN stage. 

Abstract Despite model predictions, many planetary nebulae appear to have a relatively rich molecular content. Observational studies of over 30 such objects show the presence of a variety of gas-phase molecules, from simple species such as CN and CS, to more complex organics including H₂CO, HC₃N, c-C₃H₂, and CH₃CN. Other PNe contain fullerenes; carbonaceous and silicate dust features are also found. Molecular abundances also do not appear to vary with nebular age. Remnant material from the asymptotic giant branch appears to undergo chemical processing in the protoplanetary nebula phase and then is frozen out in planetary nebulae. PN ejecta are thus in part molecular in content and may account for the observation of complex molecules in diffuse clouds. 

Abstract Observations of HCN and HCO + have been carried out toward 13 planetary nebulae (PNe) using the facilities of the Arizona Radio Observatory (ARO). These nebulae represent a wide range of morphologies and ages (∼2000–28,000 yr). For both molecules, the J = 1 → 0 transitions at 88–89 GHz and the J = 3 → 2 lines at 265–267 GHz were measured, together with CO lines ( J = 1 → 0, 2 → 1, and 3 → 2, depending on the source), using the ARO 12 m and Submillimeter Telescopes. HCN and HCO + were detected with at least one transition in 10 nebulae: He 2-459, Hu 1-1, K3-52, K3-65, M1-8, M1-40, M1-59, M2-53, M4-17, and NGC 6445. HCO + was additionally identified via two transitions in Na 2. Some observed line profiles were complex, with multiple velocity components tracing varied outflows. From radiative transfer modeling, column densities were established for HCN and HCO + : N tot (HCN) = 0.005–1.1 × 10 14 and N tot (HCO + ) = 0.008–9.5 × 10 13 cm −2 . Gas densities of n (H 2 ) ∼ 10 5 –10 7 cm −3 were also determined for all PNe. Fractional abundances with respect to H 2 , calculated using CO as a proxy, are f (HCN) ∼ 0.2–1.5 × 10 −7 and f (HCO + ) ∼ 0.3–5.1 × 10 −8 . The abundances of HCN and HCO + did not significantly vary with nebular age to 28,000 yr. Combined with previous observations, at least 30 PNe contain HCN and/or HCO + , indicating that polyatomic molecules are common constituents of these objects. The data strongly support a scenario where dense ejecta from PNe seed the interstellar medium with molecular material. 

Grading adhesive properties across a bondline can lead to more unniform stresses and increased strength without altering the geometry of the adherends. In this research, radiation sensitizers have been added to adhesives to create a secondary cross-linking possibility that is activated with radiation. In this way the adhesive stiffness and strength can be controlled by controlling the exposure to radition. In this paper, a system of grading adhesive properties is introduced and the double cantilver beam test results show that the gradation not only changes stiffness and strength, but also mode I fracture properties. Additionally, specimens were created with graded properties along the bondline and test results will be presented in the final paper. 

Abstract Data collected so far by the Pierre Auger Observatory have enabled major advances in ultra-high energy cosmic ray physics and demonstrated that improved determination of masses of primary cosmic-ray particles, preferably on an event-by-event basis, is necessary for understanding their origin and nature. Improvement in primary mass measurements was the main motivation for the upgrade of the Pierre Auger Observatory, called AugerPrime. As part of this upgrade, scintillator detectors are added to the existing water-Cherenkov surface detector stations. By making use of the differences in detector response to the electromagnetic particles and muons between scintillator and water-Cherenkov detectors, the electromagnetic and muonic components of cosmic-ray air showers can be disentangled. Since the muonic component is sensitive to the primary mass, such combination of detectors provides a powerful way to improve primary mass composition measurements over the original Auger surface detector design. In this paper, the so-called Scintillator Surface Detectors are discussed, including their design characteristics, production process, testing procedure and deployment in the field. 

Abstract The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 yr of operation by the Pierre Auger Observatory surface detectors in Malargüe, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability. 

Abstract Ultrahigh-energy cosmic rays are known to be mainly of extragalactic origin, and their propagation is limited by energy losses, so their arrival directions are expected to correlate with the large-scale structure of the local Universe. In this work, we investigate the possible presence of intermediate-scale excesses in the flux of the most energetic cosmic rays from the direction of the supergalactic plane region using events with energies above 20 EeV recorded with the surface detector array of the Pierre Auger Observatory up to 2022 December 31, with a total exposure of 135,000 km²sr yr. The strongest indication for an excess that we find, with a posttrial significance of 3.1σ, is in the Centaurus region, as in our previous reports, and it extends down to lower energies than previously studied. We do not find any strong hints of excesses from any other region of the supergalactic plane at the same angular scale. In particular, our results do not confirm the reports by the Telescope Array Collaboration of excesses from two regions in the Northern Hemisphere at the edge of the field of view of the Pierre Auger Observatory. With a comparable integrated exposure over these regions, our results there are in good agreement with the expectations from an isotropic distribution.