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.

A metagenomic-based study of two sites from the Barbadian reef system.

We study the microbiome of sea water collected from two locations of the Barbadian coral reefs. The two sites differ in several environmental and ecological variables including their endogenous benthic community and their proximity to urban development and runoffs from inland watersheds. The composition of the microbial communities was estimated using whole genome DNA shotgun sequencing with adjuvant measurements of chemical and environmental qualities. Although both sites exhibit a similar degree of richness, the less urbanized site (Maycocks reef at Hangman's Bay) has a strong concentration of phototrophs whereas the more urbanized location (Bellairs reef at Folkstone) is enriched for copiotrophs, macroalgal symbionts and marine-related disease-bearing organisms from taxa scattered across the tree of life. Our results are concordant with previous profiles of warm ocean surface waters, suggesting our approach captures the state of each coral reef site, setting the stage for longitudinal studies of marine microbiome dynamics in Barbados. Supplementary Information: The online version contains supplementary material available at 10.1007/s00338-022-02330-y.

Demystifying mercury geochemistry in contaminated soil-groundwater systems with complementary mercury stable isotope, concentration, and speciation analyses.

Interpretation of mercury (Hg) geochemistry in environmental systems remains a challenge. This is largely associated with the inability to identify specific Hg transformation processes and species using established analytical methods in Hg geochemistry (total Hg and Hg speciation). In this study, we demonstrate the improved Hg geochemical interpretation, particularly related to process tracing, that can be achieved when Hg stable isotope analyses are complemented by a suite of more established methods and applied to both solid- (soil) and liquid-phases (groundwater) across two Hg2+-chloride (HgCl2) contaminated sites with distinct geological and physicochemical properties. This novel approach allowed us to identify processes such as Hg2+ (i.e., HgCl2) sorption to the solid-phase, Hg2+ speciation changes associated with changes in groundwater level and redox conditions (particularly in the upper aquifer and capillary fringe), Hg2+ reduction to Hg0, and dark abiotic redox equilibration between Hg0 and Hg(II). Hg stable isotope analyses play a critical role in our ability to distinguish, or trace, these in situ processes. While we caution against the non-critical use of Hg isotope data for source tracing in environmental systems, due to potentially variable source signatures and overprinting by transformation processes, our study demonstrates the benefits of combining multiple analytical approaches, including Hg isotope ratios as a process tracer, to obtain an improved picture of the enigmatic geochemical behavior and fate of Hg at contaminated legacy sites.

Single-longitudinal-mode pumped pulsed-dye amplifier for high-resolution laser spectroscopy.

The In-Gas-jet Laser Ionization and Spectroscopy (IGLIS) technique relies on narrow-bandwidth, high-peak-power, short-pulse-length (≈10 ns), and high-repetition-rate laser pulses to probe, precisely and efficiently, the hyperfine structure of medium-heavy and heavy isotopes, embedded in a supersonic jet. The power and repetition rate requirements of the laser system are met by combining ≈100 W, 8 ns pulse width, 10 kHz commercial Nd:YAG pump lasers with a single-mode continuous wave seeded Pulsed Dye Amplifier (PDA). The common multi-longitudinal-mode operation of these Nd:YAG pump lasers causes, however, undesirable frequency sidebands in the output spectrum of the PDA system, hindering the attainable spectral resolution, a correct interpretation, and an accurate analysis of the hyperfine spectra. In this article, a new prototype Nd:YAG laser is presented, which combined with the PDA system is capable of providing quasi-transform-limited laser pulses at 10 kHz, with only limited losses in laser power. This system reduces any spectral sideband amplitude below a proven upper limit of 0.2% with one order of magnitude extra reduction expected based on simulations. A full characterization of both the Nd:YAG and PDA laser systems is done by studying the temporal and frequency behavior in detail. This study is finalized by a performance benchmark of this combined laser system in the hyperfine spectroscopy of copper isotopes, showcasing its applicability for future IGLIS studies.

A large-scale assessment of lakes reveals a pervasive signal of land use on bacterial communities.

Lakes play a pivotal role in ecological and biogeochemical processes and have been described as "sentinels" of environmental change. Assessing "lake health" across large geographic scales is critical to predict the stability of their ecosystem services and their vulnerability to anthropogenic disturbances. The LakePulse research network is tasked with the assessment of lake health across gradients of land use on a continental scale. Bacterial communities are an integral and rapidly responding component of lake ecosystems, yet large-scale responses to anthropogenic activity remain elusive. Here, we assess the ecological impact of land use on bacterial communities from over 200 lakes covering more than 660,000 km2 across Eastern Canada. In addition to community variation between ecozones, land use across Eastern Canada also appeared to alter diversity, community composition, and network structure. Specifically, increasing anthropogenic impact within the watershed lowered diversity. Likewise, community composition was significantly correlated with agriculture and urban development within a watershed. Interaction networks showed decreasing complexity and fewer keystone taxa in impacted lakes. Moreover, we identified potential indicator taxa of high or low lake water quality. Together, these findings point to detectable bacterial community changes of largely unknown consequences induced by human activity within lake watersheds.

The Heidelberg compact electron beam ion traps.

Electron beam ion traps (EBITs) are ideal tools for both production and study of highly charged ions (HCIs). In order to reduce their construction, maintenance, and operation costs, we have developed a novel, compact, room-temperature design, the Heidelberg Compact EBIT (HC-EBIT). Four already commissioned devices operate at the strongest fields (up to 0.86 T) reported for such EBITs using permanent magnets, run electron beam currents up to 80 mA, and energies up to 10 keV. They demonstrate HCI production, trapping, and extraction of pulsed Ar16+ bunches and continuous 100 pA ion beams of highly charged Xe up to charge state 29+, already with a 4 mA, 2 keV electron beam. Moreover, HC-EBITs offer large solid-angle ports and thus high photon count rates, e.g., in x-ray spectroscopy of dielectronic recombination in HCIs up to Fe24+, achieving an electron-energy resolving power of E/ΔE > 1500 at 5 keV. Besides traditional on-axis electron guns, we have also implemented a novel off-axis gun for laser, synchrotron, and free-electron laser applications, offering clear optical access along the trap axis. We report on its first operation at a synchrotron radiation facility demonstrating the resonant photoexcitation of highly charged oxygen.

[Alzheimer dementia: course and burden on caregivers : Data over 18 months from German participants of the GERAS study]. / Alzheimer-Demenz: Verlauf und Belastung der Pflegepersonen : 18-Monats-Daten der deutschen Teilnehmer der GERAS-Studie.

The GERAS study is an international observational study with dementia patients of the Alzheimer type (AD) and their caregivers in everyday care. The 18-month data recorded in Germany are presented. Disease progression, medical and psychosocial consequences for both patients and caregivers were recorded using commonly used tests in clinical care: the mini mental status examination (MMSE), Alzheimer's disease assessment scale (ADAS-Cog14), Alzheimer's disease cooperative study activities of daily living inventory (ADCS-ADL), neuropsychiatric inventory (NPI-12), resource utilization in dementia (RUD) and the Zarit burden interview (ZBI). Definition of AD severity level (MMSE): 21-26 mild (miAD), 15-20 moderate (moAD), <15 moderately severe to severe (m/sAD). For the 550 participants (mean age: 75.2 years, SD 7.6 years), miAD (41.5%), moAD (28.4%) and m/sAD (30.2%), the MMSE worsened: in miAD by -2.4 (CI -3.1/-1.7), in moAD by -3.9 (CI -5.0/-2.8) and in m/sAD by -2.5 (CI -3.5/-1.5) at 18 months and the ADAS-Cog14 by 6.2 (miAD-CI 4.6/7.8) and 7.1 points (moAD CI 3.9/10.3). Changes in overall ADCS-ADL amounted to -8.4 (CI -10.1/-6.2) for miAD, -12.9 (CI -15.3/-10.4) for moAD and -10.2 points (CI-12.8/-7.7) for m/sAD. Caregiver burden (NPI-12) rose in miAD by 1.2 points (CI -0.2/2.2), in moAD by 3.4 (CI 1.8/5.1) and in m/sAD by 1.5 points (CI 0.2/3.3). At study start, the total time required by caregivers (RUD) was 3.1 h/day (SD 5.4 h/day) for miAD, 6.6 (SD 7.5) for moAD and 12.7 (SD 9.3) for m/sAD. With 4.4 (SD 9.4) h/day, the increase after 18 months was highest in moAD. Caregiver burden (ZBI) increased most markedly in moAD with 7.2 (CI 4.2/9.7), 90.7% of the patients received antidementia drugs, while 26.6% received psychotropic medication.

The effect of pH, electrolytes and temperature on the rhizosphere geochemistry of phytosiderophores.

BACKGROUND AND AIMS: Graminaceous plants are grown worldwide as staple crops under a variety of climatic and soil conditions. They release phytosiderophores for Fe acquisition (Strategy II). Aim of the present study was to uncover how the rhizosphere pH, background electrolyte and temperature affect the mobilization of Fe and other metals from soil by phytosiderophores. METHODS: For this purpose a series of kinetic batch interaction experiments with the phytosiderophore 2'-deoxymugineic acid (DMA), a calcareous clay soil and a mildly acidic sandy soil were performed. The temperature, electrolyte concentration and applied electrolyte cation were varied. The effect of pH was examined by applying two levels of lime and Cu to the acidic soil. RESULTS: Fe mobilization by DMA increased by lime application, and was negatively affected by Cu amendment. Mobilization of Fe and other metals decreased with increasing ionic strength, and was lower for divalent than for monovalent electrolyte cations at equal ionic strength, due to higher adsorption of metal-DMA complexes to the soil. Metal mobilization rates increased with increasing temperature leading to a faster onset of competition; Fe was mobilized faster, but also became depleted faster at higher temperature. Temperature also affected biodegradation rates of metal-DMA complexes. CONCLUSION: Rhizosphere pH, electrolyte type and concentration and temperature can have a pronounced effect on Strategy II Fe acquisition by affecting the time and concentration 'window of Fe uptake' in which plants can benefit from phytosiderophore-mediated Fe uptake.

Experimental considerations in metal mobilization from soil by chelating ligands: The influence of soil-solution ratio and pre-equilibration - A case study on Fe acquisition by phytosiderophores.

The efficiency of chelating ligands in mobilizing metals from soils and sediments is generally examined under conditions remote from those under which they are exuded or applied in the field. This may lead to incorrect estimations of the mobilizing efficiency. The aim of this study was to establish the influence of the soil solution ratio (SSR) and pre-equilibration with electrolyte solution on metal mobilization and metal displacement. For this purpose a series of interaction experiments with a calcareous clay soil and a biogenic chelating agent, the phytosiderophore 2'-deoxymugineic acid (DMA) were carried out. For a fixed ligand concentration, the SSR had a strong influence on metal mobilization and displacement. Metal complexation was faster at higher SSR. Reactive pools of metals that were predominantly mobilized at SSR 6 (in this case Cu), became depleted at SSR 0.1, whereas metals that were marginally mobilized at SSR 6, were dominantly mobilized at SSR 0.1 (in this case Fe), because of large soil reactive pools. For a fixed "amount of ligand"-to-"amount of soil"-ratio, metal complexation scaled linearly with the SSR. The efficiency of ligands in mobilizing metals under field conditions can be predicted with batch experiments, as long as the ligand-to-soil-ratio is matched. In most previously reported studies this criterion was not met. Equivalent metal-complex concentrations under field conditions can be back-calculated using adsorption isotherms for the respective metal-complexes. Drying and dry storage created labile pools of Fe, Cu and Zn, which were rapidly mobilized upon addition of DMA solution to dry soil. Pre-equilibration decreased these labile pools, leading to smaller concentrations of these metals during initial mobilization, but did not reduce the lag time between ligand addition and onset of microbial degradation of the metal-complexes. Hence SSR and pre-equilibration should be carefully considered when testing the metal mobilizing efficiency of chelating ligands.

Retention of phytosiderophores by the soil solid phase - adsorption and desorption.

BACKGROUND AND AIMS: Graminaceous plants exude phytosiderophores (PS) for acquiring Fe. Adsorption of PS and its metal complexes to the soil solid phase reduces the FePS solution concentration and hence Fe uptake. In this study we aimed to quantify adsorption, and to determine to what extent adsorption depends on the complexed metal and on soil properties. Furthermore, we examined if adsorption is a reversible process. METHODS: Adsorption and desorption of PS and metal-PS complexes were examined in batch experiments in which the PS 2'-deoxymugineic acid (DMA) and its metal-complexes (FeDMA, CuDMA, NiDMA and ZnDMA) interacted with several calcareous soils. RESULTS: Adsorption of DMA ligand (0-1000 µM) and metal-DMA complexes (0-100 µM) was linear in the concentration range examined. Adsorption varied by a factor ≈2 depending on the complexed metal and by up to a factor 3.5 depending on the soil. Under field-like conditions (50 % water holding capacity), 50-84 % of the DMA was predicted to be retained to the soil solid phase. Alike adsorption, desorption of metal-DMA complexes is fast (approximate equilibrium within 1 hour). However, only a small fraction of the adsorbed FeDMA (28-35 %) could be desorbed. CONCLUSIONS: Despite this small fraction, the desorbed FeDMA still exceeded the amount in solution, indicating that desorption of FeDMA from soil reactive compounds can be an important process buffering the solution concentration.

Fitness effects of new mutations in Chlamydomonas reinhardtii across two stress gradients.

Most spontaneous mutations affecting fitness are likely to be deleterious, but the strength of selection acting on them might be impacted by environmental stress. Such stress-dependent selection could expose hidden genetic variation, which in turn might increase the adaptive potential of stressed populations. On the other hand, this variation might represent a genetic load and thus lead to population extinction under stress. Previous studies to determine the link between stress and mutational effects on fitness, however, have produced inconsistent results. Here, we determined the net change in fitness in 29 genotypes of the green algae Chlamydomonas reinhardtii that accumulated mutations in the near absence of selection for approximately 1000 generations across two stress gradients, increasing NaCl and decreasing phosphate. We found mutational effects to be magnified under extremely stressful conditions, but such effects were specific both to the type of stress and to the genetic background. The detection of stress-dependent fitness effects of mutations depended on accurately scaling relative fitness measures by generation times, thus offering an explanation for the inconsistencies among previous studies.

Geochemical processes constraining iron uptake in Strategy II Fe acquisition.

Phytosiderophores (PS) are natural chelating agents, exuded by graminaceous plants (grasses) for the purpose of Fe acquisition (Strategy II). They can form soluble Fe complexes with soil-Fe that can be readily taken up. PS are exuded in a diurnal pulse release, and with the start of PS release a "window of iron uptake" opens. In the present study we examined how this window is constrained in time and concentration by biogeochemical processes. For this purpose, a series of interaction experiments was done with a calcareous clay soil and the phytosiderophore 2'-deoxymugineic acid (DMA), in which metal and DMA speciation were examined as a function of time and DMA concentration. Various kinetically and thermodynamically controlled processes affected the size of the window of Fe uptake. Adsorption lowered, but did not prevent Fe mobilization by DMA. Microbial activity depleted DMA from solution, but not on time scales jeopardizing Strategy II Fe acquisition. Complexation of competing metals played an important role in constraining the window of Fe uptake, particularly at environmentally relevant PS concentrations. Our study provides a conceptual model that takes into account the chemical kinetics involved with PS-mediated Fe acquisition. The model can help to explain how success or failure of PS-mediated Fe acquisition depends on environmental conditions.

Metal mobilization from soils by phytosiderophores - experiment and equilibrium modeling.

AIMS: To test if multi-surface models can provide a soil-specific prediction of metal mobilization by phytosiderophores (PS) based on the characteristics of individual soils. METHODS: Mechanistic multi-surface chemical equilibrium modeling was applied for obtaining soil-specific predictions of metal and PS speciation upon interaction of the PS 2'-deoxymugineic acid (DMA) with 6 soils differing in availability of Fe and other metals. Results from multi-surface modeling were compared with empirical data from soil interaction experiments. RESULTS: For soils in which equilibrium was reached during the interaction experiment, multi-surface models could well predict PS equilibrium speciation. However, in uncontaminated calcareous soils, equilibrium was not reached within a week, and experimental and modeled DMA speciation differed considerably. In soils with circum-neutral pH, on which Fe deficiency is likely to occur, no substantial Fe mobilization by DMA was predicted. However, in all but the contaminated soils, Fe mobilization by DMA was observed experimentally. Cu and Ni were the quantitatively most important metals competing with Fe for complexation and mobilization by DMA. CONCLUSION: Thermodynamics are unable to explain the role of PS as Fe carrier in calcareous soils, and the kinetic aspects of metal mobilization by PS need to be closer examined in order to understand the mechanisms underlying strategy II Fe acquisition.

Hetero-oligomerization of chemokine receptors: diversity and relevance for function.

The G protein-coupled receptor (GPCR) family of membrane receptors encompasses over 1000 members, representing the largest known receptor family, with a variety of structurally different ligands. GPCRs are favorite targets for drug development in numerous diseases. Chemokine receptors are an important GPCR sub-class and are known to play a crucial role in the regulation of multiple physiological and various pathophysiological processes, including inflammation, atherosclerosis, cancer, and viral infections. Chemokine receptor activation is controlled by some 50 chemokine ligands which often act in a redundant and overlapping manner, enabling for a complex regulatory system together controlling and fine-tuning the specificity and spatio-temporal properties of the response. Recent findings have indicated that additionally the organization of chemokine receptors on the cell surface could be critical for driving their biological effects. In fact, chemokine receptors have increasingly been found to organize into homo- or hetero-oligomeric complexes, in part in a ligand-inducible manner, resulting in complex networks and crosstalk with other orthogonal signaling complexes. There has even been evidence for heterologous complex formation between chemokine receptors and non-chemokine receptor G protein-coupled receptors (GPCRs), and even non-GPCRs. However, the functional consequences of this kind of oligomerization have remained poorly understood, even for the chemokine receptor homo-oligomers. Yet, there is growing evidence that targeting homo- and/or hetero-oligomerization of chemokine receptors might be beneficial for the development of novel and specific therapeutics. In the present article, we highlight the multi-faceted complexity of chemokine receptor structures with a focus on their hetero-oligomerization properties.

[Neuropsychology of psychoeducation in schizophrenia: results of the Munich COGPIP study]. / Neuropsychologie der Psychoedukation bei Schizophrenie: Ergebnisse der Münchner COGPIP-Studie.

BACKGROUND: The aim of the study was to examine whether the efficacy of psychoeducation in patients with schizophrenia is dependent on their cognitive performance and if a preceding cognitive training can enhance the therapeutic effects of psychoeducation. PATIENTS AND METHODS: A total of 116 inpatients were randomly assigned to either a standardized cognitive training (COGPACK) or to routine occupational therapy, followed by a psychoeducational group program of 8 sessions within 4 weeks for all study patients. The effects of cognitive training and psychoeducation were assessed directly afterwards and in a follow-up after 9 months. RESULTS: The patient knowledge and compliance improved. Neurocognition and especially memory acquisition significantly predicted illness knowledge after psychoeducation, whereas psychopathology did not. No differential effects of the COGPACK training were found. After 9 months 75% of the patients showed a very good compliance and the readmission rate was 18%. The results were comparable under both study conditions. CONCLUSION: Besides baseline illness knowledge neurocognition was the only significant predictor for illness knowledge after psychoeducation. Patients with cognitive deficits can profit from psychoeducation in the long run as well. In future it should be examined whether a modified cognitive training program could achieve a faster improvement of the illness knowledge.

Competitive ligand exchange between Cu-humic acid complexes and methanobactin.

Copper has been found to play a key role in the physiology of methanotrophic micro-organisms, and methane oxidation may critically depend on the availability of Cu. In natural environments, such as soils, sediments, peat bogs, and surface waters, the presence of natural organic matter (NOM) can control the bioavailability of Cu by forming strong metal complexes. To promote Cu acquisition, methanotrophs exude methanobactin, a ligand known to have a high affinity for Cu. In this study, the capability of methanobactin for Cu acquisition from NOM was investigated using humic acid (HA) as a model substance. The kinetics of ligand exchange between Cu-HA and methanobactin was observed by UV-vis spectroscopy, and the speciation of Cu bound to methanobactin was determined by size-exclusion chromatography coupled to an ICP-MS. The results showed that Cu was mobilized from HA by a fast ligand exchange reaction following a second-order rate law with first-order kinetics for both methanobactin and Cu-HA complexes. The reaction rates decreased with decreasing temperature. Equilibrium experiments indicated that methanobactin was not sorbed to HA and proved that methanobactin is competitive with HA for Cu binding by forming strong 1:1 Cu-methanobactin complexes. Consequently, our results demonstrate that methanobactin can efficiently acquire Cu in organic-rich environments.