Observation of a Low-Lying Metastable Electronic State in Highly Charged Lead by Penning-Trap Mass Spectrometry.

Highly charged ions (HCIs) offer many opportunities for next-generation clock research due to the vast landscape of available electronic transitions in different charge states. The development of extreme ultraviolet frequency combs has enabled the search for clock transitions based on shorter wavelengths in HCIs. However, without initial knowledge of the energy of the clock states, these narrow transitions are difficult to be probed by lasers. In this Letter, we provide experimental observation and theoretical calculation of a long-lived electronic state in Nb-like Pb^{41+} that could be used as a clock state. With the mass spectrometer PENTATRAP, the excitation energy of this metastable state is directly determined as a mass difference at an energy of 31.2(8) eV, corresponding to one of the most precise relative mass determinations to date with a fractional uncertainty of 4×10^{-12}. This experimental result agrees within 1σ with two partially different ab initio multiconfiguration Dirac-Hartree-Fock calculations of 31.68(13) eV and 31.76(35) eV, respectively. With a calculated lifetime of 26.5(5.3) days, the transition from this metastable state to the ground state bears a quality factor of 1.1×10^{23} and allows for the construction of a HCI clock with a fractional frequency instability of <10^{-19}/sqrt[τ].

High-precision mass measurement of doubly magic 208 Pb.

The absolute atomic mass of 208 Pb has been determined with a fractional uncertainty of 7 × 10 - 11 by measuring the cyclotron-frequency ratio R of 208 Pb 41 + to 132 Xe 26 + with the high-precision Penning-trap mass spectrometer Pentatrap and computing the binding energies E Pb and E Xe of the missing 41 and 26 atomic electrons, respectively, with the ab initio fully relativistic multi-configuration Dirac-Hartree-Fock (MCDHF) method. R has been measured with a relative precision of 9 × 10 - 12 . E Pb and E Xe have been computed with an uncertainty of 9.1 eV and 2.1 eV, respectively, yielding 207.976 650 571 ( 14 )  u ( u = 9.314 941 024 2 ( 28 ) × 10 8  eV/c 2 ) for the 208 Pb neutral atomic mass. This result agrees within 1.2 σ with that from the Atomic-Mass Evaluation (AME) 2020, while improving the precision by almost two orders of magnitude. The new mass value directly improves the mass precision of 14 nuclides in the region of Z = 81-84 and is the most precise mass value with A > 200 . Thus, the measurement establishes a new region of reference mass values which can be used e.g. for precision mass determination of transuranium nuclides, including the superheavies.

Renal volume assessed by magnetic resonance imaging volumetry correlates with renal function in living kidney donors pre- and postdonation: a retrospective cohort study.

Renal function of potential living kidney donors is routinely assessed with scintigraphy. Kidney anatomy is evaluated by imaging techniques such as magnetic resonance imaging (MRI). We evaluated if a MRI-based renal volumetry is a good predictor of kidney function pre- and postdonation. We retrospectively analyzed the renal volume (RV) in a MRI of 100 living kidney donors. RV was correlated with the tubular excretion rate (TER) of MAG3-scintigraphy, a measured creatinine clearance (CrCl), and the estimated glomerular filtration rate (eGFR) by Cockcroft-Gault (CG), CKD-EPI, and modification of diet in renal disease (MDRD) formula pre- and postdonation during a follow-up of 3 years. RV correlated significantly with the TER (total: r = 0.6735, P < 0.0001). Correlation between RV and renal function was the highest for eGFR by CG (r = 0.5595, P < 0.0001), in comparison with CrCl, MDRD-GFR, and CKD-EPI-GFR predonation. RV significantly correlated with CG-GFR postdonation and predicted CG-GFR until 3 years after donation. MRI renal volumetry might be an alternative technique for the evaluation of split renal function and prediction of renal function postdonation in living kidney donors.

"Will anybody listen?" parents' views on childhood asthma care: a qualitative study.

BACKGROUND: Asthma is the most common chronic disease in children, resulting in considerable morbidity and health care utilisation, especially in geographical areas with high deprivation. Parents play a pivotal role in children's asthma management. AIM: To explore the views of parents whose children have asthma, regarding barriers and facilitators to receiving adequate asthma care. DESIGN & SETTING: A qualitative study conducted in an urban, multi-ethnic setting with high socioeconomic deprivation and paediatric asthma related hospital admissions. METHOD: The study used a pragmatic approach underpinned by a perspective of critical realism. Parents of children with asthma were recruited through purposive and convenience sampling and data collected through semi-structured interviews. Transcripts were analysed using thematic analysis, facilitated by NVivo software. RESULTS: 10 parents participated in nine interviews. Six themes were identified relating to: (1) the establishment of a new life dynamic following a diagnosis of asthma; (2) the turbulent and drawn-out process of asthma diagnosis; (3) the roles and expectations of the partnership established between parents and healthcare services; (4) the importance of schools in asthma management; (5) sources and access to relevant information; and (6) the importance of social support networks. Parents frequently felt unsupported and misunderstood, particularly during the diagnostic process. CONCLUSION: Unmet parental educational and emotional needs, particularly around the time of diagnosis were identified as a key barrier to adequate asthma management. Deeper understanding of gaps in support can instruct asthma care delivery and inform co-produced interventions, thus improving asthma outcomes in children.

Fast silicon carbide MOSFET based high-voltage push-pull switch for charge state separation of highly charged ions with a Bradbury-Nielsen gate.

In this paper, we report on the development of a fast high-voltage switch, which is based on two enhancement mode N-channel silicon carbide metal-oxide-semiconductor field-effect transistors in push-pull configuration. The switch is capable of switching high voltages up to 600 V on capacitive loads with rise and fall times on the order of 10 ns and pulse widths ≥20 ns. Using this switch, it was demonstrated that, from the charge state distribution of bunches of highly charged ions ejected from an electron beam ion trap with a specific kinetic energy, single charge states can be separated by fast switching of the high voltage applied to a Bradbury-Nielsen Gate with a resolving power of about 100.

A digital feedback system for advanced ion manipulation techniques in Penning traps.

The possibility of applying active feedback to a single ion in a Penning trap using a fully digital system is demonstrated. Previously realized feedback systems rely on analog circuits that are susceptible to environmental fluctuations and long term drifts, as well as being limited to the specific task they were designed for. The presented system is implemented using a field-programmable gate array (FPGA)-based platform (STEMlab), offering greater flexibility, higher temporal stability, and the possibility for highly dynamic variation of feedback parameters. The system's capabilities were demonstrated by applying feedback to the ion detection system primarily consisting of a resonant circuit. This allowed shifts in its resonance frequency of up to several kHz and free modification of its quality factor within two orders of magnitude, which reduces the temperature of a single ion by a factor of 6. Furthermore, a phase-sensitive detection technique for the axial ion oscillation was implemented, which reduces the current measurement time by two orders of magnitude, while simultaneously eliminating model-related systematic uncertainties. The use of FPGA technology allowed the implementation of a fully-featured data acquisition system, making it possible to realize feedback techniques that require constant monitoring of the ion signal. This was successfully used to implement a single-ion self-excited oscillator.

Access to Highly Functionalized Cyclopentenones via Diastereoselective Pauson-Khand Reaction of Siloxy-Tethered 1,7-Enynes.

A diastereoselective Co2(CO)8-mediated Pauson-Khand reaction (PKR) of siloxy-tethered 1,7-enynes for the synthesis of cyclopentaoxasilinones has been developed. This transformation can be performed on a multigram scale and is characterized by a broad substrate scope, functional group compatibility, and high chemo- and diastereoselectivity. Oxidation of the resulting cyclopentaoxasilinones delivers stereoenriched ß-alkylated cyclopentenones, which are inaccessible by intermolecular PKRs. This research provides a practical solution to the challenges associated with the classical intermolecular PKR.