Production study of Fr, Ra and Ac radioactive ion beams at ISOLDE, CERN.

The presented paper discusses the production of radioactive ion beams of francium, radium, and actinium from thick uranium carbide (UC x ) targets at ISOLDE, CERN. This study focuses on the release curves and extractable yields of francium, radium and actinium isotopes. The ion source temperature was varied in order to study the relative contributions of surface and laser ionization to the production of the actinium ion beams. The experimental results are presented in the form of release parameters. Representative extractable yields per µ C are presented for 222 - 231 Ac, several Ra and Fr isotopes in the mass ranges 214 ≤ A ≤ 233 and 205 ≤ A ≤ 231 respectively. The release efficiency for several isotopes of each of the studied elements was calculated by comparing their yields to the estimated in-target production rates modeled by CERN-FLUKA. The maximal extraction efficiency of actinium was calculated to be 2.1(6)% for a combination of surface ionization using a Ta ion source and resonant laser ionization using the two-step 438.58 nm, and 424.69 nm scheme.

Urban stormwater quality: A review of methods for continuous field monitoring.

Urban stormwater is contaminated by a wide range of substances whose concentrations vary greatly between locations, as well as between and during rain events. This literature review evaluates advantages and limitations of current methods for using continuous water quality monitoring for stormwater characterization and control. High-temporal-resolution measurements have been used to improve the understanding of stormwater quality dynamics and pollutant pathways, facilitate the performance evaluation of stormwater control measures and improve operation of the urban drainage system with real-time control. However, most sensors used to study stormwater were developed for either centralized water treatment or natural water contexts and adaptation is necessary. At present, the primary application of interest in stormwater - characterization of pollutant concentrations - can only be achieved through the use of indirect measurements with site-specific relationships of pollutants to basic physical-chemical parameters. In addition, various problems arise in the field context, associated with intermittent or variable flow rates, the accumulation of debris and sediment, adverse conditions for electrical equipment and human factors. Obtaining reliable continuous stormwater quality data requires the adoption of best practices, including the calibration and regular maintenance of sensors, verification of data and accounting for the considerable uncertainties in data; however, the literature review showed that improvement is needed among the scientific community in implementing and documenting these practices.

Core protocol for the adaptive Platform Trial In COVID-19 Vaccine priming and BOOsting (PICOBOO).

BACKGROUND: The need for coronavirus 2019 (COVID-19) vaccination in different age groups and populations is a subject of great uncertainty and an ongoing global debate. Critical knowledge gaps regarding COVID-19 vaccination include the duration of protection offered by different priming and booster vaccination regimens in different populations, including homologous or heterologous schedules; how vaccination impacts key elements of the immune system; how this is modified by prior or subsequent exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and future variants; and how immune responses correlate with protection against infection and disease, including antibodies and effector and T cell central memory. METHODS: The Platform Trial In COVID-19 priming and BOOsting (PICOBOO) is a multi-site, multi-arm, Bayesian, adaptive, randomised controlled platform trial. PICOBOO will expeditiously generate and translate high-quality evidence of the immunogenicity, reactogenicity and cross-protection of different COVID-19 priming and booster vaccination strategies against SARS-CoV-2 and its variants/subvariants, specific to the Australian context. While the platform is designed to be vaccine agnostic, participants will be randomised to one of three vaccines at trial commencement, including Pfizer's Comirnaty, Moderna's Spikevax or Novavax's Nuvaxovid COVID-19 vaccine. The protocol structure specifying PICOBOO is modular and hierarchical. Here, we describe the Core Protocol, which outlines the trial processes applicable to all study participants included in the platform trial. DISCUSSION: PICOBOO is the first adaptive platform trial evaluating different COVID-19 priming and booster vaccination strategies in Australia, and one of the few established internationally, that is designed to generate high-quality evidence to inform immunisation practice and policy. The modular, hierarchical protocol structure is intended to standardise outcomes, endpoints, data collection and other study processes for nested substudies included in the trial platform and to minimise duplication. It is anticipated that this flexible trial structure will enable investigators to respond with agility to new research questions as they arise, such as the utility of new vaccines (such as bivalent, or SARS-CoV-2 variant-specific vaccines) as they become available for use. TRIAL REGISTRATION: Australian and New Zealand Clinical Trials Registry ACTRN12622000238774. Registered on 10 February 2022.

Nuclear moments of indium isotopes reveal abrupt change at magic number 82.

In spite of the high-density and strongly correlated nature of the atomic nucleus, experimental and theoretical evidence suggests that around particular 'magic' numbers of nucleons, nuclear properties are governed by a single unpaired nucleon1,2. A microscopic understanding of the extent of this behaviour and its evolution in neutron-rich nuclei remains an open question in nuclear physics3-5. The indium isotopes are considered a textbook example of this phenomenon6, in which the constancy of their electromagnetic properties indicated that a single unpaired proton hole can provide the identity of a complex many-nucleon system6,7. Here we present precision laser spectroscopy measurements performed to investigate the validity of this simple single-particle picture. Observation of an abrupt change in the dipole moment at N = 82 indicates that, whereas the single-particle picture indeed dominates at neutron magic number N = 82 (refs. 2,8), it does not for previously studied isotopes. To investigate the microscopic origin of these observations, our work provides a combined effort with developments in two complementary nuclear many-body methods: ab initio valence-space in-medium similarity renormalization group and density functional theory (DFT). We find that the inclusion of time-symmetry-breaking mean fields is essential for a correct description of nuclear magnetic properties, which were previously poorly constrained. These experimental and theoretical findings are key to understanding how seemingly simple single-particle phenomena naturally emerge from complex interactions among protons and neutrons.

Systematic review and meta-analysis of the effect of pertussis vaccine in pregnancy on the risk of chorioamnionitis, non-pertussis infectious diseases and other adverse pregnancy outcomes.

BACKGROUND: Several countries have introduced maternal immunisation with pertussis vaccine to provide protection against pertussis in early infancy. There is increasing interest in non-specific effects of vaccines including that non-live vaccines may enhance susceptibility to non-targeted infections in females. Some studies have shown increased risk of chorioamnionitis among women receiving pertussis vaccine during pregnancy. We aimed to conduct a systematic review and meta-analysis of the effect of maternal pertussis immunisation on the risk of chorioamnionitis, as well as the secondary outcomes of non-pertussis infections in women, non-pertussis infections in infants, spontaneous abortion or stillbirth, maternal death and infant death. METHODS: We searched PubMed and Embase for articles published until January 14, 2021. We screened articles for eligibility and extracted data using Covidence. Quality was assessed using Cochrane RoB tool and Newcastle-Ottawa Scale. Data were imported into RevMan for pooling and conduction of a meta-analysis stratified by study type. Outcomes are presented as risk ratios. RESULTS: We identified 13 observational studies and six randomized controlled trials eligible for inclusion. We pooled data on chorioamnionitis from six observational studies and found maternal pertussis vaccine (mostly compared with other maternal immunizations with non-live vaccines) to be associated with an increased risk among the pertussis vaccinated women, RR = 1.27 [CI 95%: 1.14-1.42]. We found no difference in the analysis of our secondary outcomes of non-pertussis infections, spontaneous abortion or stillbirth and death. CONCLUSION: We found an increased risk of chorioamnionitis among women who received pertussis vaccine in pregnancy. The large number of women receiving pertussis vaccine during pregnancy, as well as the growing evidence of non-live vaccines causing increased susceptibility to infections, indicates a need for further randomised trials to assess potential adverse effects of maternal immunisation with pertussis-containing vaccines.

Isotope Shifts of Radium Monofluoride Molecules.

Isotope shifts of ^{223-226,228}Ra^{19}F were measured for different vibrational levels in the electronic transition A^{2}Π_{1/2}←X^{2}Σ^{+}. The observed isotope shifts demonstrate the particularly high sensitivity of radium monofluoride to nuclear size effects, offering a stringent test of models describing the electronic density within the radium nucleus. Ab initio quantum chemical calculations are in excellent agreement with experimental observations. These results highlight some of the unique opportunities that short-lived molecules could offer in nuclear structure and in fundamental symmetry studies.

Ion Heating and Flow Driven by an Instability Found in Plasma Couette Flow.

We present the first observation of instability in weakly magnetized, pressure dominated plasma Couette flow firmly in the Hall regime. Strong Hall currents couple to a low frequency electromagnetic mode that is driven by high-ß (>1) pressure profiles. Spectroscopic measurements show heating (factor of 3) of the cold, unmagnetized ions via a resonant Landau damping process. A linear theory of this instability is derived that predicts positive growth rates at finite ß and shows the stabilizing effect of very large ß, in line with observations.

Laboratory Resolved Structure of Supercritical Perpendicular Shocks.

Supermagnetosonic perpendicular flows are magnetically driven by a large radius theta-pinch experiment. Fine spatial resolution and macroscopic coverage allow the full structure of the plasma-piston coupling to be resolved in laboratory experiment for the first time. A moving ambipolar potential is observed to reflect unmagnetized ions to twice the piston speed. Magnetized electrons balance the radial potential via Hall currents and generate signature quadrupolar magnetic fields. Electron heating in the reflected ion foot is adiabatic.

Laser Spectroscopy of Neutron-Rich

The mean-square charge radii of ^{207,208}Hg (Z=80, N=127, 128) have been studied for the first time and those of ^{202,203,206}Hg (N=122, 123, 126) remeasured by the application of in-source resonance-ionization laser spectroscopy at ISOLDE (CERN). The characteristic kink in the charge radii at the N=126 neutron shell closure has been revealed, providing the first information on its behavior below the Z=82 proton shell closure. A theoretical analysis has been performed within relativistic Hartree-Bogoliubov and nonrelativistic Hartree-Fock-Bogoliubov approaches, considering both the new mercury results and existing lead data. Contrary to previous interpretations, it is demonstrated that both the kink at N=126 and the odd-even staggering (OES) in its vicinity can be described predominately at the mean-field level and that pairing does not need to play a crucial role in their origin. A new OES mechanism is suggested, related to the staggering in the occupation of the different neutron orbitals in odd- and even-A nuclei, facilitated by particle-vibration coupling for odd-A nuclei.

Weakly Magnetized, Hall Dominated Plasma Couette Flow.

A novel plasma equilibrium in the high-ß, Hall regime that produces centrally peaked, high Mach number Couette flow is described. Flow is driven using a weak, uniform magnetic field and large, cross field currents. Large magnetic field amplification (factor 20) due to the Hall effect is observed when electrons are flowing radially inward, and near perfect field expulsion is observed when the flow is reversed. A dynamic equilibrium is reached between the amplified (removed) field and extended density gradients.

Laser spectroscopy of indium Rydberg atom bunches by electric field ionization.

This work reports on the application of a novel electric field-ionization setup for high-resolution laser spectroscopy measurements on bunched fast atomic beams in a collinear geometry. In combination with multi-step resonant excitation to Rydberg states using pulsed lasers, the field ionization technique demonstrates increased sensitivity for isotope separation and measurement of atomic parameters over previous non-resonant laser ionization methods. The setup was tested at the Collinear Resonance Ionization Spectroscopy experiment at ISOLDE-CERN to perform high-resolution measurements of transitions in the indium atom from the [Formula: see text] and [Formula: see text] states to [Formula: see text]p [Formula: see text]P and [Formula: see text]F Rydberg states, up to a principal quantum number of [Formula: see text]. The extracted Rydberg level energies were used to re-evaluate the ionization potential of the indium atom to be [Formula: see text]. The nuclear magnetic dipole and nuclear electric quadrupole hyperfine structure constants and level isotope shifts of the [Formula: see text] and [Formula: see text] states were determined for [Formula: see text]In. The results are compared to calculations using relativistic coupled-cluster theory. A good agreement is found with the ionization potential and isotope shifts, while disagreement of hyperfine structure constants indicates an increased importance of electron correlations in these excited atomic states. With the aim of further increasing the detection sensitivity for measurements on exotic isotopes, a systematic study of the field-ionization arrangement implemented in the work was performed at the same time and an improved design was simulated and is presented. The improved design offers increased background suppression independent of the distance from field ionization to ion detection.

Spectroscopy of short-lived radioactive molecules.

Molecular spectroscopy offers opportunities for the exploration of the fundamental laws of nature and the search for new particle physics beyond the standard model1-4. Radioactive molecules-in which one or more of the atoms possesses a radioactive nucleus-can contain heavy and deformed nuclei, offering high sensitivity for investigating parity- and time-reversal-violation effects5,6. Radium monofluoride, RaF, is of particular interest because it is predicted to have an electronic structure appropriate for laser cooling6, thus paving the way for its use in high-precision spectroscopic studies. Furthermore, the effects of symmetry-violating nuclear moments are strongly enhanced5,7-9 in molecules containing octupole-deformed radium isotopes10,11. However, the study of RaF has been impeded by the lack of stable isotopes of radium. Here we present an experimental approach to studying short-lived radioactive molecules, which allows us to measure molecules with lifetimes of just tens of milliseconds. Energetically low-lying electronic states were measured for different isotopically pure RaF molecules using collinear resonance ionisation at the ISOLDE ion-beam facility at CERN. Our results provide evidence of the existence of a suitable laser-cooling scheme for these molecules and represent a key step towards high-precision studies in these systems. Our findings will enable further studies of short-lived radioactive molecules for fundamental physics research.

A spectrometer for high-precision ion temperature and velocity measurements in low-temperature plasmas.

We have developed a low-cost spectrometer with simple optical design that achieves unprecedented precision measurements of ion temperature (±0.01 eV) and velocity (±20 m/s). A Fabry-Pérot étalon provides the simultaneous high resolving power and high throughput needed for the light levels available in singly ionized helium and argon plasmas. Reducing the systematic uncertainty in the absolute wavelength calibration needed for the specified velocity precision motivates a Bayesian analysis method called Nested Sampling to address the nontrivial uncertainty in the diffraction order. An initial emission measurement of a singly charged stationary argon plasma yields a temperature of 0.339 ± 0.007 eV and a velocity of -3 ± 4 m/s with a systematic uncertainty of 20 m/s.

Malaria vaccines in the eradication era: current status and future perspectives.

INTRODUCTION: The challenge to eradicate malaria is an enormous task that will not be achieved by current control measures, thus an efficacious and long-lasting malaria vaccine is required. The licensing of RTS, S/AS01 is a step forward in providing some protection, but a malaria vaccine that protects across multiple transmission seasons is still needed. To achieve this, inducing beneficial immune responses while minimising deleterious non-targeted effects will be essential. AREAS COVERED: This article discusses the current challenges and advances in malaria vaccine development and reviews recent human clinical trials for each stage of infection. Pubmed and ScienceDirect were searched, focusing on cell mediated immunity and how T cell subsets might be targeted in future vaccines using novel adjuvants and emerging vaccine technologies. EXPERT COMMENTARY: Despite decades of research there is no highly effective licensed malaria vaccine. However, there is cause for optimism as new adjuvants and vaccine systems emerge, and our understanding of correlates of protection increases, especially regarding cellular immunity. The new field of heterologous (non-specific) effects of vaccines also highlights the broader consequences of immunization. Importantly, the WHO led Malaria Vaccine Technology Roadmap illustrates that there is a political will among the global health community to make it happen.

Factors influencing recruitment and appearance of bull kelp, Nereocystis luetkeana (phylum Ochrophyta).

The dynamics of annual species are strongly tied to their capacity for recruitment each year. We examined how competition and propagule availability influence recruitment and appearance and tracked survivorship of an annual species of marine macroalgae, the bull kelp (Nereocystis luetkeana), which serves as major biogenic habitat in the Salish Sea of Washington State. We hypothesized that (i) juvenile N. luetkeana would exhibit a seasonal appearance as a cohort in the spring and (ii) competition for space would be more limiting than propagules (spores) to recruitment at sites adjacent to established N. luetkeana beds. We tagged N. luetkeana recruits in the field to track appearance and survivorship across seasons (spring, summer, fall, and winter), using a two-factor crossed design to assess effects of competition and propagule availability on appearance of new N. luetkeana sporophytes. Survivorship of N. luetkeana recruits was low and, whereas most new individuals arose in the spring, some appeared in every season. New N. luetkeana recruits also appeared the earliest (median 8 weeks vs. >20 weeks) after experimental "seeding" in the spring as compared to other seasons. Eliminating macroalgal competitors ("clearing") influenced the appearance of recruits more than enhancement of propagules in the spring. An improved understanding of factors regulating the seasonal appearance of new N. luetkeana sporophytes furthers our understanding of this crucial foundation species' appearance and persistence across seasons, which is increasingly important as global ocean conditions change, and highlights the importance of studying organisms with complex life histories across multiple stages and geographical regions.

Species-Specific Detection of C. difficile Using Targeted Antibody Design.

Clostridium difficile is a Gram-positive, spore-forming bacterium that continues to present a worldwide problem in healthcare settings. The bacterium causes disease, the symptoms of which include diarrhea, fever, nausea, abdominal pain and even death. Despite the prevalence of the disease, the diagnosis of C. difficile infection is still challenging, with a variety of methods available, each varying in their effectiveness. In this work we sought to identify a new biomarker for C. difficile, develop affinity reagents and design a diagnostic assay for C. difficile infection which could be used in a typical two-step testing algorithm. Initially a bioinformatics pipeline was developed that identified a surface associated biomarker "AKDGSTKEDQLVDALA" present in all C. difficile strains sequenced to-date and unique to the C. difficile species. Monoclonal antibodies were subsequently raised against peptides corresponding to the biomarker sequence. During characterization studies, monoclonal antibody 521 (mAb521) was shown to bind all known C. difficile surface layer types, but not closely related strains. Surface plasmon resonance measurements were used to calculate an apparent equilibrium dissociation constant of 36.5 nM between the purified protein target containing the biomarker (surface layer protein A) and mAb521. We demonstrate a limit of detection of 12.4 ng/mL against surface layer protein A and 1.7 × 106 cells/mL in minimally processed C. difficile cultures. The utility of this computational approach to antibody design for diagnostic tests is the ability to produce antibodies that can act as universal species identifiers while mitigating the likelihood of false-positive detection by intelligently screening potential biomarkers against RefSeq data for other nontarget bacteria.

From Calcium to Cadmium: Testing the Pairing Functional through Charge Radii Measurements of

Differences in mean-square nuclear charge radii of ^{100-130}Cd are extracted from high-resolution collinear laser spectroscopy of the 5s ^{2}S_{1/2}→5p ^{2}P_{3/2} transition of the ion and from the 5s5p ^{3}P_{2}→5s6s ^{3}S_{1} transition in atomic Cd. The radii show a smooth parabolic behavior on top of a linear trend and a regular odd-even staggering across the almost complete sdgh shell. They serve as a first test for a recently established new Fayans functional and show a remarkably good agreement in the trend as well as in the total nuclear charge radius.

Structural and biochemical characterization of SpoIIIAF, a component of a sporulation-essential channel in Bacillus subtilis.

Environmental stress factors initiate the developmental process of sporulation in some Gram-positive bacteria including Bacillus subtilis. Upon sporulation initiation the bacterial cell undergoes a series of morphological transformations that result in the creation of a single dormant spore. Early in sporulation, an asymmetric cell division produces a larger mother cell and smaller forespore. Next, the mother cell septal membrane engulfs the forespore, and an essential channel, the so-called feeding-tube apparatus, is formed. This assembled channel is thought to form a transenvelope secretion complex that crosses both mother cell and forespore membranes. At least nine proteins are essential for channel formation including SpoIIQ under forespore control and the eight SpoIIIA proteins (SpoIIIAA-AH) under mother cell control. Several of these proteins share similarity with components of Gram-negative bacterial secretion systems and the flagellum. Here we report the X-ray crystallographic structure of the soluble domain of SpoIIIAF to 2.7 Šresolution. Like the channel components SpoIIIAG and SpoIIIAH, SpoIIIAF adopts a conserved ring-building motif (RBM) fold found in proteins from numerous dual membrane secretion systems of distinct function. The SpoIIIAF RBM fold contains two unique features: an extended N-terminal helix, associated with multimerization, and an insertion at a loop region that can adopt two distinct conformations. The ability of the same primary sequence to adopt different secondary structure conformations is associated with protein regulation, suggesting a dual structural and regulatory role for the SpoIIIAF RBM. We further analyzed potential interaction interfaces by structure-guided mutagenesis in vivo. Collectively, our data provide new insight into the possible roles of SpoIIIAF within the secretion-like apparatus during sporulation.