The unusual protoplanetary disk around the T Tauri star ET Cha

We present new continuum and line observations, along with modelling, of the faint (6-8) Myr old T Tauri star ET Cha belonging to the eta Chamaeleontis cluster. We have acquired HERSCHEL/PACS photometric fluxes at 70 mic and 160 mic, as well as a detection of the [OI] 63 mic fine-structure line in emission, and derived upper limits for some other far-IR OI, CII, CO and o-H2O lines. The HERSCHEL data is complemented by new ANDICAM B-K photometry, new HST/COS and HST/STIS UV-observations, a non-detection of CO J=3-2 with APEX, re-analysis of a UCLES high-resolution optical spectrum showing forbidden emission lines like [OI] 6300A, [SII] 6731A and 6716A, and [NII] 6583A, and a compilation of existing broad-band photometric data. We used the thermo-chemical disk code ProDiMo and the Monte-Carlo radiative transfer code MCFOST to model the protoplanetary disk around ET Cha. Based on these models we can determine the disk dust mass Mdust = (2.E-8 - 5.E-8) Msun, whereas the total disk gas mass is found to be only little constrained, Mgas = (5.E-5 - 3.E-3) Msun. In the models, the disk extends from 0.022 AU (just outside of the co-rotation radius) to only about 10 AU. Larger disks are found to be inconsistent with the CO J=3-2 non-detection. The low velocity component of the [OI] 6300A emission line is consistent with being emitted from the inner disk. The model can also reproduce the line flux of H2 v=1-0 S(1) at 2.122 mic. An additional high-velocity component of the [OI] 6300A emission line, however, points to the existence of an additional jet/outflow of low velocity (40 - 65) km/s with mass loss rate ~1.E-9 Msun/yr. In relation to our low estimations of the disk mass, such a mass loss rate suggests a disk lifetime of only ~(0.05 - 3) Myr, substantially shorter than the cluster age. The evolutionary state of this unusual protoplanetary disk is discussed.Comment: accepted by Astronomy & Astrophysics (18 pages, 11 figures and 7 tables). Additional 9-page appendix with 6 figures, 3 tables and 37 equation

Stabilities of nanohydrated thymine radical cations: insights from multiphoton ionization experiments and ab initio calculations

Multi-photon ionization experiments have been carried out on thymine-water clusters in the gas phase. Metastable H2O loss from T+(H2O)n was observed at n ≥ 3 only. Ab initio quantum-chemical calculations of a large range of optimized T+(H2O)n conformers have been performed up to n = 4, enabling binding energies of water to be derived. These decrease smoothly with n, consistent with the general trend of increasing metastable H2O loss in the experimental data. The lowest-energy conformers of T+(H2O)3 and T+(H2O)4 feature intermolecular bonding via charge-dipole interactions, in contrast with the purely hydrogen-bonded neutrals. We found no evidence for a closed hydration shell at n = 4, also contrasting with studies of neutral clusters

Fragmentation processes of ionized 5-fluorouracil in the gas phase and within clusters

We have measured mass spectra for positive ions produced from neutral 5-fluorouracil by electron impact at energies from 0 to 100 eV. Fragment ion appearance energies of this (radio-)chemotherapy agent have been determined for the first time and we have identified several new fragment ions of low abundance. The main fragmentations are similar to uracil, involving HNCO loss and subsequent HCN loss, CO loss, or FCCO loss. The features adjacent to these prominent peaks in the mass spectra are attributed to tautomerization preceding the fragmentation and/or the loss of one or two additional hydrogen atoms. A few fragmentions are distinct for 5-fluorouracil compared to uracil, most notably the production of the reactive moiety CF+. Finally, multiphoton ionization mass spectra are compared for 5-fluorouracil from a laser thermal desorption source and from a supersonic expansion source. The detection of a new fragment ion at 114 u in the supersonic expansion experiments provides the first evidence for a clustering effect on the radiation response of 5-fluorouracil. By analogy with previous experiments and calculations on protonated uracil, this is assigned to NH3 loss from protonated 5-fluorouracil

Impact of primary kidney disease on the effects of empagliflozin in patients with chronic kidney disease: secondary analyses of the EMPA-KIDNEY trial

Background: The EMPA KIDNEY trial showed that empagliflozin reduced the risk of the primary composite outcome of kidney disease progression or cardiovascular death in patients with chronic kidney disease mainly through slowing progression. We aimed to assess how effects of empagliflozin might differ by primary kidney disease across its broad population. Methods: EMPA-KIDNEY, a randomised, controlled, phase 3 trial, was conducted at 241 centres in eight countries (Canada, China, Germany, Italy, Japan, Malaysia, the UK, and the USA). Patients were eligible if their estimated glomerular filtration rate (eGFR) was 20 to less than 45 mL/min per 1·73 m2, or 45 to less than 90 mL/min per 1·73 m2 with a urinary albumin-to-creatinine ratio (uACR) of 200 mg/g or higher at screening. They were randomly assigned (1:1) to 10 mg oral empagliflozin once daily or matching placebo. Effects on kidney disease progression (defined as a sustained ≥40% eGFR decline from randomisation, end-stage kidney disease, a sustained eGFR below 10 mL/min per 1·73 m2, or death from kidney failure) were assessed using prespecified Cox models, and eGFR slope analyses used shared parameter models. Subgroup comparisons were performed by including relevant interaction terms in models. EMPA-KIDNEY is registered with ClinicalTrials.gov, NCT03594110. Findings: Between May 15, 2019, and April 16, 2021, 6609 participants were randomly assigned and followed up for a median of 2·0 years (IQR 1·5–2·4). Prespecified subgroupings by primary kidney disease included 2057 (31·1%) participants with diabetic kidney disease, 1669 (25·3%) with glomerular disease, 1445 (21·9%) with hypertensive or renovascular disease, and 1438 (21·8%) with other or unknown causes. Kidney disease progression occurred in 384 (11·6%) of 3304 patients in the empagliflozin group and 504 (15·2%) of 3305 patients in the placebo group (hazard ratio 0·71 [95% CI 0·62–0·81]), with no evidence that the relative effect size varied significantly by primary kidney disease (pheterogeneity=0·62). The between-group difference in chronic eGFR slopes (ie, from 2 months to final follow-up) was 1·37 mL/min per 1·73 m2 per year (95% CI 1·16–1·59), representing a 50% (42–58) reduction in the rate of chronic eGFR decline. This relative effect of empagliflozin on chronic eGFR slope was similar in analyses by different primary kidney diseases, including in explorations by type of glomerular disease and diabetes (p values for heterogeneity all >0·1). Interpretation: In a broad range of patients with chronic kidney disease at risk of progression, including a wide range of non-diabetic causes of chronic kidney disease, empagliflozin reduced risk of kidney disease progression. Relative effect sizes were broadly similar irrespective of the cause of primary kidney disease, suggesting that SGLT2 inhibitors should be part of a standard of care to minimise risk of kidney failure in chronic kidney disease. Funding: Boehringer Ingelheim, Eli Lilly, and UK Medical Research Council

Radiative relaxation in 2p-excited argon clusters

The emission of ultraviolet fluorescence radiation from variable size argon clusters is investigated with high spectral resolution in the Ar 2p-excitation regime. The fluorescence excitation spectra reveal strong fluorescence intensity in the Ar 2p-continuum, but no evidence for the occurrence of discrete low-lying core-exciton states in the near-edge regime. This finding is different from the absorption and photoionization cross section of argon clusters and the solid. The dispersed fluorescence shows a broad molecular band centered near 280 nm. The present work indicates that double and triple ionization via the LMM-Auger decay are required to initiate the fluorescence processes in the Ar 2p-continuum. The present results are consistent with the formation of singly charged, excited moieties within the clusters, which are assigned as sources of the radiative emission in the 280 nm regime. A fast energy transfer process (interatomic Coulombic decay (ICD)), which has been proposed by recent theoretical work, is assigned to be primarily the origin of these singly charged, excited cations besides intra-cluster electron impact ionization by the Auger electrons. Our findings give first possible experimental evidence for ICD in the core level regime