The bioequivalence study design recommendations for immediate-release solid oral dosage forms in the international pharmaceutical regulators programme participating regulators and organisations: differences and commonalities

Bioequivalence (BE) studies are considered the standard for demonstrating that the performance of a generic drug product in the human body is sufficiently similar to that of its comparator product. The objective of this article is to describe the recommendations from participating Bioequivalence Working Group for Generics (BEWGG) members of the International Pharmaceutical Regulators Programme (IPRP) regarding the conduct and acceptance criteria for BE studies of immediate release solid oral dosage forms. A survey was conducted among BEWGG members regarding their BE recommendations and requirements related to study subjects, study design, sample size, single or multiple dose administration, study conditions (fasting or fed), analyte to be measured, selection of product strength, drug content, handling of endogenous substances, BE acceptance criteria, and additional design aspects. All members prefer conducting single dose cross-over designed studies in healthy subjects with a minimum of 12 subjects and utilizing the parent drug data to assess BE. However, differences emerged among the members when the drug's pharmacokinetics and pharmacodynamics become more complex, such that the study design (e.g., fasting versus fed conditions) and BE acceptance criteria (e.g., highly variable drugs, narrow therapeutic index drugs) may be affected. The survey results and discussions were shared with the ICH M13 Expert Working Group (EWG) and played an important role in identifying and analyzing gaps during the harmonization process. The draft ICH M13A guideline developed by the M13 EWG was endorsed by ICH on 20 December 2022, under Step 2.

A Survey of the Criteria Used for the Selection of Alternative Comparator Products by Participating Regulators and Organizations of the International Pharmaceutical Regulators Programme

The safety and efficacy of a generic product are partly based on demonstrating bioequivalence to the innovator product; however, when the innovator product is no longer available as a comparator product, a survey conducted within the Bioequivalence Working Group for Generics (BEWGG) of the International Pharmaceutical Regulators Programme (IPRP) indicated that the criteria for selecting an alternative comparator product varies. For most members of the BEWGG, an existing marketed generic that was approved based on a comparison with the locally registered innovator product can be used, contingent on criteria that ranges from allowing any generic to be used, to allowing only specific criteria-defined generics to be used. Notwithstanding the acceptability of a generic as an alternative comparator, it is not always the preferred comparator for several jurisdictions. Some jurisdictions require the use of a locally sourced alternative innovator comparator (e.g., the same medicinal ingredient manufactured by a different company) or a foreign innovator comparator. Unlike the other members of the BEWGG, the European Union (EU) has no such options available, rather mechanisms are in place to allow manufacturers to develop a new comparator. The criteria described herein regarding the use of an alternative comparator product can also be applied to scenarios where a specific strength of a series of strengths or an innovative fixed dose combination are discontinued. The results of the survey demonstrate that while criteria for selecting alternative comparator products are not harmonized among the BEWGG participants, the common concern for all jurisdictions is to select a comparator product that meets the safety and efficacy standards of the original innovator product.

Coffee consumption and cardiovascular health in the general population

Background

Coffee, next to water the most widespread beverage, is attributed both harmful and protective characteristics concerning cardiovascular health. This study aimed to evaluate associations of coffee consumption with cardiac biomarkers, echocardiographic, and electrocardiographic parameters as well as major cardiovascular diseases.

Methods and results

We performed a cross-sectional analysis of 9,009 participants a large German population-based cohort study, enrolled between 2016 and 2018 median age 63 [IQR: 55; 69] years. Coffee consumption was classified into three groups: <3 cups/day (low), 3–4 cups/day (moderate), >4 cups/day (high). In linear regression analyses adjusted for age, sex, body mass index, diabetes, hypertension, and smoking, moderate and high coffee consumption were associated with LDL-cholesterol (β=2.08; 95% CI: 0.14, 4.03, p=0.036; β=5.69; 95% CI: 2.91, 8.47; p<0.001). Moderate and high coffee consumption were negatively associated with systolic (β=−1.6; 95% CI: −2.66, −0.54; p=0.003; β=−2.63; 95% CI: −4.15, −1.12; p=0.001) and diastolic blood pressure (β=−0.8; 95% CI: −1.38, −0.22; p=0.007; β=1.28; 95% CI: −2.11, −0.45; p=0.002). Different levels of coffee consumption did neither correlate with any investigated electrocardiographic or echocardiographic parameter nor with prevalent major cardiovascular diseases, including prior myocardial infarction and heart failure.

Conclusions

In this cross-sectional analysis, moderate and high coffee consumption was positively associated with LDL-cholesterol and negatively associated with systolic and diastolic blood pressure. However, major cardiovascular diseases including heart failure and its diagnostic precursors were not associated with coffee consumption, connoting a neutral role of coffee in the context of cardiovascular health.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Deutsche Forschungsgemeinschaft [Grant Number TH1106/5-1; AA93/2-1]The Foundation Leducq [Grant Number 16 CVD 03]

Requirements for Additional Strength Biowaivers for Modified Release Solid Oral Dosage Forms in International Pharmaceutical Regulators Programme Participating Regulators and Organisations: Differences and Commonalities

This article describes an overview of waivers of in vivo bioequivalence studies for additional strengths in the context of the registration of modified release generic products and is a follow-up to the recent publication for the immediate release solid oral dosage forms. The current paper is based on a survey among the participating members of the Bioequivalence Working Group for Generics (BEWGG) of the International Pharmaceutical Regulators Program (IPRP) regarding this topic. Most jurisdictions consider the extrapolation of bioequivalence results obtained with one (most sensitive) strength of a product series as less straightforward for modified release products than for immediate release products. There is consensus that modified release products should demonstrate bioequivalence not only in the fasted state but also in the fed state, but differences exist regarding the necessity of additional multiple dose studies. Fundamental differences between jurisdictions are revealed regarding requirements on the quantitative composition of different strengths and the differentiation of single and multiple unit dosage forms. Differences in terms of in vitro dissolution requirements are obvious, though these are mostly related to possible additional comparative investigations rather than regarding the need for product-specific methods. As with the requirements for immediate release products, harmonization of the various regulations for modified release products is highly desirable to conduct the appropriate studies from a scientific point of view, thus ensuring therapeutic equivalence.

A Survey of the Regulatory Requirements for the Waiver of In Vivo Bioequivalence Studies of Generic Products in Certain Dosage Forms by Participating Regulators and Organisations of the International Pharmaceutical Regulators Programme

The requirements to waive in vivo bioequivalence studies for immediate release solid oral dosage forms based on the Biopharmaceutics Classifications System (BCS) are well known, and biowaivers[1] for other types of oral dosage forms based on pre-defined criteria may also be acceptable. Similarly, biowaivers for dosage forms such as injectable products may also be allowed if certain criteria are met. The current paper summarises the biowaiver requirements for oral solutions and suspensions, soft gelatin capsules and injectable products (intravenous injections, subcutaneous and intramuscular injections, emulsions for injection and micellar solutions for injection) among the participants of the Bioequivalence Working Group for Generics (BEWGG) of the International Pharmaceutical Regulators Programme (IPRP). A review of the requirements indicated that there was a trend towards convergence when the dosage form became less complex; however, the most common approach used by each of the jurisdictions was a case-by-case approach given that most jurisdictions do not have well defined guidelines to support all possible scenarios. Even in the simplest case of intravenous solutions, the acceptability of qualitative changes in excipients differ between the IPRP members.  Notwithstanding the differences, the dissemination of the information is a first step towards regulatory convergence regarding biowaivers for certain dosage forms and should be useful for pharmaceutical companies currently developing generic medicinal products for IPRP jurisdictions.  

Project Orbis: Global Collaborative Review Program

In 2019, the FDA Oncology Center of Excellence launched Project Orbis, a global collaborative review program to facilitate faster patient access to innovative cancer therapies across multiple countries. Project Orbis aims for concurrent submission, review, and regulatory action for high-impact clinically significant marketing applications among the participating partner countries. Current Project Orbis partners (POP) include the regulatory health authorities (RHA) of Australia, Brazil, Canada, Singapore, and Switzerland. Project Orbis leverages the existing scientific and regulatory partnerships between the various RHA under mutual confidentiality agreements. While FDA serves as the primary coordinator for application selection and review, each country remains fully independent on their final regulatory decision. In the first year of Project Orbis (June 2019 to June 2020), a total of 60 oncology marketing applications were received, representing 16 unique projects, and resulting in 38 approvals. New molecular entities, also known as new active substances, comprised 28% of the received marketing applications. The median time gap between FDA and Orbis submission dates was 0.6 months with a range of -0.8 to 9.0 months. Across the program, the median time-to-approval was similar between FDA (4.2 months, range 0.9-6.9, N = 18) and the POP (4.4 months, range 1.7-6.8, N = 20). Participating countries have signified a strong commitment for continuation and growth of the program. Project Orbis expansion considerations include the addition of more countries and management of more complex applications.

The Requirements for Additional Strength Biowaivers for Immediate Release Solid Oral Dosage Forms in International Pharmaceutical Regulators Programme Participating Regulators and Organisations: Differences and Commonalities

In relation to the registration of generic products, waivers of in vivo bioequivalence studies (biowaivers) are considered in three main cases: certain dosage forms for which bioequivalence is self-evident (e.g. intravenous solutions), biowaivers based on the Biopharmaceutics Classification System and biowaivers for additional strengths with respect to the strength for which in vivo bioequivalence has been shown. The objective of this article is to describe the differences and commonalities in biowaivers for additional strengths of immediate release solid oral dosage forms between the participating members of the International Pharmaceutical Regulators Program (IPRP). The requirements are based on five main aspects; the pharmacokinetics of the drug substance, the manufacturing process, the qualitative and quantitative composition of the different strengths, and the comparative dissolution profiles. For the pharmacokinetic aspects, many regulators/agencies have the same requirements. All strengths must be manufactured with the same process, although a few regulators/agencies accept small differences. In relation to the formulation aspects, the data required breaks down into three major approaches based initially on one of those of the EU, the USA or Japan, but there are some differences in these three major approaches with some country specific interpretations. Most regulators/agencies also have the same requirements for the dissolution data, though there are some notable exceptions.

Radionuclides: Accumulation and Transport in Plants

Application of radioactive elements or radionuclides for anthropogenic use is a widespread phenomenon nowadays. Radionuclides undergo radioactive decays releasing ionizing radiation like gamma ray(s) and/or alpha or beta particles that can displace electrons in the living matter (like in DNA) and disturb its function. Radionuclides are highly hazardous pollutants of considerable impact on the environment, food chain and human health. Cleaning up of the contaminated environment through plants is a promising technology where the rhizosphere may play an important role. Plants belonging to the families of Brassicaceae, Papilionaceae, Caryophyllaceae, Poaceae, and Asteraceae are most important in this respect and offer the largest potential for heavy metal phytoremediation. Plants like Lactuca sativa L., Silybum marianum Gaertn., Centaurea cyanus L., Carthamus tinctorius L., Helianthus annuus and H. tuberosus are also important plants for heavy metal phytoremediation. However, transfer factors (TF) of radionuclide from soil/water to plant ([Radionuclide]plant/[Radionuclide]soil) vary widely in different plants. Rhizosphere, rhizobacteria and varied metal transporters like NRAMP, ZIP families CDF, ATPases (HMAs) family like P1B-ATPases, are involved in the radio-phytoremediation processes. This review will discuss recent advancements and potential application of plants for radionuclide removal from the environment.

Iodine-129, Iodine-127 and Cesium-137 in seawater from the North Sea and the Baltic Sea

In this study, new data are presented for the iodine isotopes (¹²⁷I, ¹²⁹I and their isotopic ratios) and Cesium (¹³⁷Cs) in water samples of the North Sea and the Baltic Sea in 2005 and 2009. This study supplements and extends the study of Michel et al. (2012). Iodine isotopes were separated from their matrix by using an anion exchange method and were determined by applying ICP-MS and AMS. ¹³⁷Cs in seawater was determined after cesium ion exchange procedure enrichment by gamma-spectrometry. The concentrations of ¹²⁷I in seawater of the North and Baltic Sea are fairly constant in each Sea with averages of (44 ± 2) and (21 ± 1) ng g^-1, respectively, depending on the salinity. However, large variations of ¹²⁹I concentrations in these areas were detected, which decreased along the French, Belgian, Dutch, German, and Danish shores. ¹²⁹I/¹²⁷I isotope ratios in the Baltic Sea are about 10 times lower than in the North Sea in 2009. The highest isotopic ratios (2.7 × 10^-6) was detected in the English Channel east of the nuclear reprocessing plant at Cap de la Hague. The results confirm the result of our early study that the sources of ¹²⁹I in the North Sea are primarily the nuclear reprocessing facilities at Sellafield (UK) and La Hague (F), and that in the Baltic Sea the inflow of water from North Sea through the Danish Straits dominates the occurrence of ¹²⁹I. In 2009, the activity concentration of ¹³⁷Cs was at least 6 times higher in the Baltic Sea (37 Bq m^-3) than in the North Sea (5.9 Bq m^-3), due to release of ¹³⁷Cs from sediments in the Baltic Sea, which were contaminated by the Chernobyl accident and - to a minor degree - the atmospheric explosions of atomic bombs. The results are discussed by comparing the results of our previous work and the current study demonstrating the continuing disequilibrium of ¹²⁹I/¹²⁷I atomic ratio in the environmental compartments.

Concentrations of iodine isotopes ((129)I and (127)I) and their isotopic ratios in aerosol samples from Northern Germany

New data about (129)I, (127)I concentrations and their isotopic ratios in aerosol samples from the trace survey station of the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Northern Germany, are presented and discussed in this paper. The investigated samples were collected on a weekly basis during the years 2011 to 2013. Iodine was extracted from aerosol filters using a strong basic solution and was separated from the matrix elements with chloroform and was analysed by accelerator mass spectrometry (AMS) for (129)I and by inductively coupled plasma mass spectrometry (ICP-MS) for (127)I. The concentrations of (127)I and (129)I in aerosol filters ranged from 0.31 to 3.71 ng m(-3) and from 0.06 to 0.75 fg m(-3), respectively. The results of (129)I/(127)I isotopic ratios were in the order 10(-8) to 10(-7). The (129)I originated directly from gaseous emissions and indirectly from liquid emissions (via sea spray) from the reprocessing plants in Sellafield and La Hague. In comparison with the results of (131)I after the Fukushima accident, no contribution of (129)I from this accident was detectable in Central Europe due to the high background originating from the (129)I releases of the European reprocessing plants. (129)I atmospheric activity concentrations were compared with those of an anthropogenic radionuclide ((85)Kr). We did not find any correlation between (129)I and (85)Kr, both having nuclear reprocessing plant as the main source.

Automated classification of stages of anaesthesia by populations of evolutionary optimized fuzzy rules

The detection of stages of anaesthesia is mainly performed on evaluating the vital signs of the patient. In addition the frontal one-channel electroencephalogram can be evaluated to increase the correct detection of stages of anaesthesia. As a classification model fuzzy rules are used. These rules are able to classify the stages of anaesthesia automatically and were optimized by multiobjective evolutionary algorithms. As a result the performance of the generated population of fuzzy rule sets is presented. A concept of the construction of an autonomic embedded system is introduced. This system should use the generated rules to classify the stages of anaesthesia using the frontal one-channel electroencephalogram only.

Impact of former uranium mining activities on the floodplains of the Mulde River, Saxony, Germany

The Mulde River drains the former uranium mining areas in Saxony (Germany), which has led to a large-scale contamination of the river and the adjacent floodplain soils with radionuclides of the uranium decay series. The objective of the investigation is to quantify the long-term effect of former uranium mining activities on a river system. All of the investigated environmental compartments (water, sediment, soil) still reveal an impact from the former uranium mining and milling activities. The contamination of water has decreased considerably during the last 20 years due to the operation of water treatment facilities. The uranium content of the sediments decreased as well (on average by a factor of 5.6), most likely caused by displacement of contaminated material during flood events. Currently, the impact of the mining activities is most obvious in soils. For some of the plots activity concentrations of >200 Bq/kg of soil were detected for uranium-238. Alluvial soils used as grassland were found to be contaminated to a higher degree than those used as cropland.

Remediation of TENORM residues: risk communication in practice

Despite several decades of studies on the risk assessment and risk perception of ionising radiation, risk management of radioactive materials remains a challenging issue. This is also true for wastes containing technologically enhanced naturally occurring radioactive materials. The present work focuses on the underlying reasons for communication problems between experts and affected members of the public. Exploring the case of a German remediation site with residual radioactive contamination in a residential area, the experts' as well as the residents' perspectives were studied by conducting qualitative interviews. Our results indicate a variety of reasons for communication problems on different levels of risk management and risk communication: the regulatory, the communicative and the moral levels. In the observed case, four salient causes for problems in risk communication and risk management emerged: the mismatch in understanding the residents' values, the issue of risk communication in an unforeseen situation, the problem of the regulatory gap between radiation protection and soil protection in regard to legacies with naturally occurring radioactive material in Germany, and the challenge of communicating a highly complex scientific issue to non-scientists. Moreover, one (at least partial) solution could be seen: the introduction of an external mediator. The results indicate that coordination of different health and environment protection disciplines-in this case radiation protection relating to soil protection-is possible and urgently needed. The opportunity to put, at least natural, radioactive material in line with other conventional industrial materials should be taken.

Role of phosphate fertilizers in heavy metal uptake and detoxification of toxic metals

As a nonrenewable resource, phosphorus (P) is the second most important macronutrient for plant growth and nutrition. Demand of phosphorus application in the agricultural production is increasing fast throughout the globe. The bioavailability of phosphorus is distinctively low due to its slow diffusion and high fixation in soils which make phosphorus a key limiting factor for crop production. Applications of phosphorus-based fertilizers improve the soil fertility and agriculture yield but at the same time concerns over a number of factors that lead to environmental damage need to be addressed properly. Phosphate rock mining leads to reallocation and exposure of several heavy metals and radionuclides in crop fields and water bodies throughout the world. Proper management of phosphorus along with its fertilizers is required that may help the maximum utilization by plants and minimum run-off and wastage. Phosphorus solubilizing bacteria along with the root rhizosphere of plant integrated with root morphological and physiological adaptive strategies need to be explored further for utilization of this extremely valuable nonrenewable resource judiciously. The main objective of this review is to assess the role of phosphorus in fertilizers, their uptake along with other elements and signaling during P starvation.

The INE-Beamline for actinide science at ANKA

Since its inauguration in 2005, the INE-Beamline for actinide research at the synchrotron source ANKA (KIT North Campus) provides dedicated instrumentation for x-ray spectroscopic characterization of actinide samples and other radioactive materials. R&D work at the beamline focuses on various aspects of nuclear waste disposal within INE's mission to provide the scientific basis for assessing long-term safety of a final nuclear waste repository. The INE-Beamline is accessible for the actinide and radiochemistry community through the ANKA proposal system and the European Union Integrated Infrastructure Initiative ACTINET-I3. Experiments with activities up to 1 × 10(+6) times the European exemption limit are feasible within a safe but flexible containment concept. Measurements with monochromatic radiation are performed at photon energies varying between ~2.1 keV (P K-edge) and ~25 keV (Pd K-edge), including the lanthanide L-edges and the actinide M- and L3-edges up to Cf. The close proximity of the INE-Beamline to INE controlled area labs offers infrastructure unique in Europe for the spectroscopic and microscopic characterization of actinide samples. The modular beamline design enables sufficient flexibility to adapt sample environments and detection systems to many scientific questions. The well-established bulk techniques x-ray absorption fine structure (XAFS) spectroscopy in transmission and fluorescence mode have been augmented by advanced methods using a microfocused beam, including (confocal) XAFS/x-ray fluorescence detection and a combination of (micro-)XAFS and (micro-)x-ray diffraction. Additional instrumentation for high energy-resolution x-ray emission spectroscopy has been successfully developed and tested.

On the polymerization of hexavalent uranium. An electrospray mass spectrometry study

Polymerization in hexavalent uranium solutions was measured by electrospray ionization time-of-flight mass spectrometry in three different acidic media at pH values from 3 to 5.3 in order to detect all hydrolysis species present in solution. The aqueous solutions were directly measured without further dilution in organic solvents. At high uranyl concentrations ([U(VI)] = 10(- 3) M) artifacts were observed due to the presence of more than one solution species per formed microdroplet. Those artifacts were composed of ions and neutral species being present in the same droplet. However, by analyzing the detected species carefully, the origin of the artifacts could be traced back to the physically meaningful species. Still, only general trends of the hydrolysis behavior can be deduced from the measurements at [U(VI)] = 1 ⋅ 10(- 3) M. The solutions at [U(VI)] = 5 ⋅ 10(- 5) M did not show any comparable artifact formation. The detected species distributions resemble the expected trends calculated from the equilibrium constants published in the Nuclear Energy Agency Thermodynamic Database (NEA-TDB). The neutral (UO(2))(CO(3))(0) species present in solution causes, if located in the same microdroplet as a charged species, the apparent formation of dimeric and trimeric ternary hydroxo carbonate complexes at pH 5.3. As the uncharged species is not repelled from the ionic species, it might remain in the same droplet during the droplet fission process. By dividing those detected species into the uncharged (UO(2))(CO(3))(0) and a second ionic species, the relative abundances of the solution species can be corrected, leading to a good agreement with the predictions of the published equilibrium constants. In addition to the well-known trimer, we report the direct mass spectrometric detection of the dimeric (UO(2))(2)(OH)(2)(2+) species.

[Effects of daily physical exercise at school on cardiovascular risk--results of a 2-year cluster-randomized study]

BACKGROUND AND OBJECTIVE

It was the aim of this study to measure the effects over two years of daily sport activity during the school-day on their physical fitness (primary endpoint), motor coordination and blood pressure (secondary endpoints).

METHODS

A total of 232 children from eleven different 6 (th) grade classes were enrolled after informed parental consent. Their mean age was 11.1  ±  0.6 years. Six classes were randomly assigned for intervention (n=141), five as control (n=91). Those of the intervention cohort undertook, for five days weekly during the school year one hour of regulated sport exercise, including 15 min of endurance training. The pupils of the control group undertook customary sport activity (two hours a week). Anthropometric data were recorded and maximal oxygen uptake measured in each pupil, as well as blood pressure and motor coordination at the beginning and at the end of each of the two years of the study. The data were analyzed using the cluster randomization method.

RESULTS

Maximal oxygen uptake (VO (2)max) had improved among the intervention group after two years, compared with the controls (3.12 m/kg/min, 95% confindence interval [CI] 0.06-6.19), while improvement in motor coordination just failed to reach statistical significance (3.06, 95% CI -0.17-6.29). There was no significant difference in systolic and diastolic blood pressure, but a downward trend in the prevalence of overweight and obesity from 12.1% to 7.8% in the intervention group.

CONCLUSION

The results indicate that daily physical exercise during school hours should be given greater importance. But it will require a long-term trial to determine whether promotion of increased physical activity at school influences the prevalence of cardiovascular risk factors when the pupils reach adulthood.

Hemodynamic effects of eating and prolonged supine position in healthy subjects studied under clinical-pharmacological test conditions

The influences of both being in a supine position for a prolonged period and food intake on cardiovascular variables were studied under clinical-pharmacological test conditions. In a randomized crossover design study without drug or placebo administration, 6 healthy male volunteers received a light standard meal before and during test A and fasted in test B. In both tests, while they were continuously supine for more than 8 h, a synchronous recording of cardiovascular variables was done at 24, 26 and 28 min after starting the supine position (first recordings) and 25 times from 2 to 480 min after the first recordings. Using a multifactorial statistical analysis, each parameter was evaluated regarding the factors eating and time of supine recording. Eating led to a significant decrease in diastolic and mean blood pressure, PQ time and QS₂ time, a downward trend in systemic vascular resistance and an upward trend in systolic blood pressure and cardiac output. When the subjects remained in a supine position for prolonged periods, significant increases in systolic, diastolic, mean blood pressure and systemic vascular resistance were noted as well as significant decreases in cardiac output and QS₂ time. Thus, eating and remaining in a supine position for prolonged periods should be considered as sources of bias in clinical-pharmacological studies on cardiovascular drug effects and accompanying placebo controls.

Broadband THz lasing from a photon-phonon quantum cascade structure

Laser emission over a broad range of frequencies from 2.8 to 4.1 THz is reported for a two-quantum well, photon-phonon cascade structure. Maximum operating temperatures of 125 K are reported, with optical peak powers in eccess of 30 mW from a double-metal ridge waveguide. The broadband nature of the gain curve is identified as due to coherent coupling of the injector and upper lasing states. Internal quantum efficiencies reaching 43 % are evaluated at 10 K.The laser operates in both polarities, showing laser action in reverse bias up to a temperature of 90 K. Simulations based on a full treatment of the structure with density matrix formalism are also presented and discussed.

Spectroscopic identification of ternary Cm-carbonate surface complexes

The influence of dissolved CO(2) on the sorption of trivalent curium (Cm) on alumina (gamma-Al(2)O(3)) and kaolinite was investigated by time resolved laser fluorescence spectroscopy (TRLFS) using the optical properties of Cm as a local luminescent probe. Measurements were performed at T < 20 K on Cm loaded gamma-Al(2)O(3) and kaolinite wet pastes prepared in the absence and presence of carbonate in order to pictorially illustrate any changes through a direct comparison of spectra from both systems. The red-shift of excitation and emission spectra, as well as the increase of fluorescence lifetimes observed in the samples with carbonate, clearly showed the influence of carbonate and was fully consistent with the formation of Cm(III) surface species involving carbonate complexes. In addition, the biexponential decay behavior of the fluorescence lifetime indicated that at least two different Cm(III)-carbonate species exist at the mineral-water interface. These results provide the first spectroscopic evidence for the formation of ternary Cm(III)-carbonate surface complexes.

Formation and hydrolysis of polynuclear Th(IV) complexes – a nano-electrospray mass-spectrometry study

Polynuclear hydroxide complexes play an important role for the hydrolysis of tetravalent thorium ions in aqueous solution, in particular for Th(IV) concentrations exceeding some [Th(IV)]=10−4 M. Consequently, these polymers must be considered when describing hydrolysis of Th(IV) or dissolution processes of Th(IV) solids. In the past, considerable efforts were made to obtain equilibrium formation constants of these polymers and different stoichiometries for dimers, tetramers and hexamers have been suggested. However, most information was obtained from indirect methods, in particular, from potentiometric titrations. In the present work, we present an approach of directly quantifying polymeric metal hydroxide complexes in solution. By nano-electrospray mass-spectrometry the degrees of polymerization, i.e. the numbers of Th4+ ions and the numbers of hydroxide ligands, and as a consequence, also the charges of the complexes are measured. All mono- and polynuclear species which are present in solution are quantified simultaneously down to species contributing less than 0.1% of the total [Th(IV)] concentration. Solutions of [Th(IV)]=6×10−6–10−1 M are investigated in HCl at [H+]=10−4–0.1 M. More than 30 different polymeric complexes are observed with the general trend of increasing number of hydroxide ligands with decreasing acidity. A surprising finding is the presence of the pentamer Th5(OH)y z +, which was not described in the literature before. With decreasing Th(IV) concentration the stability field of polymers narrows continuously until polymers can no longer be detected below [Th(IV)]=10−5 M.

Sorption of Cm(III) onto different Feldspar surfaces: a TRLFS study

The pH dependent sorption of Cm(III) onto alkali Feldspars (albite and orthoclase) is investigated by time resolved laser fluorescence spectroscopy (TRLFS) in the pH range from 3.4 to 9.4. Three single components are calculated from the raw spectra for both feldspar systems. The first component which corresponds to the Cm(III) aquo ion has a peak maximum at 593.8 nm and a fluorescence emission lifetime of 68±4 μs. This lifetime corresponds to a Cm(III) coordination of nine water molecules in the first coordination sphere of the actinide ion. The second component with a peak maximum at 601.4 nm corresponds to an adsorbed species. Its lifetime of 107±3 μs indicates a reduction of coordinating H2O/OH− ligands from nine to five caused by inner-sphere complex formation. The third component (603.6 nm) can be attributed to another sorption species. The corresponding lifetime is again 107±3 μs. Hence the number of coordinating ligands remains constant while the ligand field changes caused by the hydrolysis of the sorbed Cm(III).

In a further set of experiments the Cm(III) sorption onto albite which is altered at pH 6.0 and pH 9.0 is also investigated by TRLFS. Independent of the dissolution and different surface morphologies caused by the alteration process the same Cm(III) species are formed as found for the sorption onto the untreated albite surface. With regard to the clarification of a feldspar dissolution mechanism the TRLFS results of the Cm(III) sorption onto altered feldspar surfaces give no evidence for a dissolution-reprecipitation based alteration mechanism.

Fluorescence spectroscopy on protactinium(IV) in aqueous solution

This work focuses on time-resolved laser fluorescence spectroscopy (TRLFS) of Pa(IV) in aqueous solution. Excitation at 308 nm causes a fluorescence emission with a peak maximum at about 460 nm. Thereby, the position of the band´s maximum depends on the concentration, the type of the acid, and the pH value. Increasing complexation of the Pa(IV) ion leads to an increasing hypsochromic shift of the emission band up to 46 nm. In contrast to the band position the half-width (61.6±1.4 nm) and the lifetime (16±2 ns) of the fluorescence emission do not change significantly with changes in the chemical environment of the Pa(IV). The results of this work show that speciation of Pa(IV) can be performed even in aqueous solution by using TRLFS.

Ion-molecule reactions of Ru+ and Os+ with oxygen in a Penning trap

Gas-phase ion chemistry in a Penning trap has been explored for future experiments on the chemical properties of the heaviest elements. The Mainz Cluster Trap, a Penning trap experiment devoted to metal cluster research, has served as a model apparatus for SHIPTRAP which is being installed behind the velocity filter SHIP (Separator for Heavy Ion reaction Products) at the Gesellschaft für Schwerionenforschung (GSI) at Darmstadt. The reactions of stored Ru+ and Os+ with oxygen have been studied and the reaction products MO+ and MO2 + (M = Ru, Os) have been observed. The corresponding rate constants have been measured and the results are discussed with respect to future studies of similar ion-molecule reactions of the element 108 (hassium) in SHIPTRAP.

Phase locking of a 1.5 Terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver

We demonstrate for the first time the closure of an electronic phase lock loop for a continuous-wave quantum cascade laser (QCL) at 1.5 THz. The QCL is operated in a closed cycle cryo cooler. We achieved a frequency stability of better than 100 Hz, limited by the resolution bandwidth of the spectrum analyser. The PLL electronics make use of the intermediate frequency (IF) obtained from a hot electron bolometer (HEB) which is downconverted to a PLL IF of 125 MHz. The coarse selection of the longitudinal mode and the fine tuning is achieved via the bias voltage of the QCL. Within a QCL cavity mode, the free-running QCL shows frequency fluctuations of about 5 MHz, which the PLL circuit is able to control via the Stark-shift of the QCL gain material. Temperature dependent tuning is shown to be nonlinear, and of the order of -16 MHz/K. Additionally we have used the QCL as local oscillator (LO) to pump an HEB and perform, again for the first time at 1.5 THz, a heterodyne experiment, and obtain a receiver noise temperature of 1741 K.

Incorporation of Eu(III) into hydrotalcite: a TRLFS and EXAFS study

The behavior of radionuclides in the environment (geo-, hydro-, and biosphere) is determined by interface reactions like adsorption, ion exchange, and incorporation processes. Presently, operational gross parameters for the distribution between solution and minerals are available. For predictive modeling of the radionuclide mobility in such systems, however, individual reactions and processes need to be localized, characterized, and quantified. A prerequisite for localization and clarification of the concerned processes is the use of modern advanced analytical and speciation methods, especially spectroscopy. In this study, Eu(III) was chosen as an analogue for trivalent actinides to identify the different species that occur by the Ln(III)/hydrotalcite interaction. Therefore, Eu(III) doped Mg-Al-Cl-hydrotalcite was synthesized and investigated by TRLFS, EXAFS, and XRD measurements. Two different Eu/hydrotalcite species were obtained. The minor part of the lanthanide is found to be inner-sphere sorbed onto the mineral surface, while the dominating Eu/hydrotalcite species consists of Eu(III) that is incorporated into the hydrotalcite lattice. Both Eu/hydrotalcite species have been characterized by their fluorescence emission spectra and lifetimes. Structural parameters of the incorporated Eu(III) species determined by EXAFS indicate a coordination number of 6.6 +/- 1.3 and distances of 2.41 +/- 0.02 A for the first Eu-OH shell.

[Intensified school sports improve fitness]

Several studies performed over the last 20 years have revealed an appreciable decrease in the average time spent daily on physical activity by children and adolescents in Europe. On the other hand, sports and physical activity improve not only motor ability and coordination, but also impact positively on cognitive performance and mental health, and also reduce cardiovascular risks. Relevant associations agree that children should spend an hour a day indulging in moderate to higher-level physical activity. Daily periods of inactivity should be limited to fewer than two hours. Measures aimed at improving mobility should be made available in kindergartens, schools and universities.