Uranium-selective adsorbent materials for environmental radiation sensing

Nuclear nonproliferation efforts and treaty verification require portable, robust radiation detectors capable of detecting trace-levels of radionuclides in environmental matrices. Despite widespread interest, currently, there are no fieldable, radiation detection techniques capable of directly analyzing gross activity or isotopic distributions of uranium in environmental waters. Extractive scintillating resins in flow-cell detectors and alpha spectroscopy are two promising fieldable detection methods; however, the implementation of these detection methods in the field requires novel separation materials capable of isolating uranium from environmental waters. Organophosphorus-derivitized materials are a promising class of materials to fit this need and are reviewed in Chapter 1. Chapter 2 presents my work understanding the stability of extractive scintillating resins prepared by multiple methods. This chapter characterizes the stability of scintillating resins for ionizing radiation detection that were synthesized with 2-(1-naphthyl)-5-phenyloxazole (α-NPO) or 2-(1-naphthyl)-4-vinyl-5-phenyloxazole (v-NPO) fluorophore in polystyrene (PS) or poly(4-methyl styrene) (PVT) matrices. Leaching studies of the PS and PVT beads with methyl acetate show a 60% reduction in luminosity and 80% reduction in detection efficiency for α-NPO samples; while v-NPO resins retained detection properties. Degradation studies indicate the nitration of PS resins and the fluorophores after nitric acid exposure, resulting in a 100% reduction in optical properties; whereas PVT resins with v-NPO fluorophore maintained 20% detection efficiency. Heuristics are reported for designing stable scintillating resins. Chapter 3 describes the synthesis and characterization of phosphonic acid derivitized resins for the simultaneous concentration and detection of uranium. Resins in this study were prepared by a two-step procedure: (1) suspension polymerization followed by (2) phosphorylation and hydrolysis. Phosphonate hydrolysis was performed via strong acid or trimethylsilyl bromide (TMSBr)-mediated methanolysis. Fluorophore degradation was observed in the resin hydrolyzed by strong acid, while the resin hydrolyzed by TMSBr-mediated methanolysis maintained luminosity and showed hydrogen bonding-induced Stokes\u27 shift of ~100 nm. Flow cell detection efficiency of the TMSBr-mediatied methanolysis resin was found to decrease with increasing pH. Trends are discussed in terms of uranium speciation in solution. Experiments performed in pH 4 synthetic groundwater show that the resins can concentrate the uranyl cation from waters with high concentrations of competitor ions at near-neutral pH. Chapter 4 describes the optimization of design parameters for the implementation of extractive scintillating resin in flow cell detectors. This chapter details the application of extractive scintillating resin with covalently bound fluorophore, v-NPO, and ligand, methyl phosphonic acid, in flow-cell experiments utilizing varying column diameters, resin diameters and diffusion times. The detection efficiency was evaluated by standard offline liquid scintillation counting methods. Diffusion experiments were conducted to determine the effect of the location of the alpha decay on detection efficiency, and the data were compared to a diffusion model to assess the feasibility of relying on diffusion-enhanced detection efficiency in an online measurement. Chapter 5 describes the synthesis and characterization of phosphonic acid- and alkyl phosphate-derivitized extractive scintillating resins. Organophosphorus-derivitized resins were synthesized by two approaches: (1) synthesis of a 4-vinylbenzyl chloride containing polymer followed by solid-phase synthesis techniques to add the phosphonic acid moiety and (2) one-pot polymerization that directly incorporates an alkyl phosphate moiety. Resins were compared on the basis of capacity for uranium, detection efficiency, and volume to detection. The volume to detection was evaluated in neutral pH simulated ground waters (pH 4-8) using a Shewart-3σ alarm statistic applied to data collected in real-time in a flow-cell detector. Resins exhibited similar binding capacities (0.18 mmol g-1) and detection efficiencies (~40%); however, the alkyl phosphate resins more rapidly achieved the Shewart-3σ alarm criteria than the phosphonic acid resins. Thermodynamic models in Visual MINTEQ software and the pKa\u27s of the ligands are used to understand how the binding mechanisms for both functional groups may change as a function of pH. The data imply that as pH increases from 4 to 8, the binding mechanism shifts from ion-exchange to ligand-exchange. Chapter 6 describes our efforts to develop a high throughput analytical technique for waterborne isotopic analysis by using reactive, functional membranes as alpha spectroscopy substrates. In this work, alpha spectroscopy substrates were prepared by two methods: (1) physical deposition of a uranium-selective, water-soluble polymer film on ultrafiltration membranes and (2) grafting uranium-selective ligands from the surface of ultrafiltration membranes. Uranium was loaded onto the substrates by filtering uranium-contaminated water through the ultrafiltration membranes. The uranium-selective, water-soluble polymer was prepared by the copolymerization of 2-hydroxylethyl methacrylate and 2-ethylene glycol methacrylate phosphate. The ligand-grafted membrane was prepared by the UV-polymerization of 2-ethylene glycol methacrylate phosphate with N,N-methylene bisacrylimide. Membranes were characterized by Fourier-transform infrared spectroscopy before and after modification to support the deposition or grafting of the polymer on the membrane surface. The capacity for uranium, 1.9 mmol U g-1, was determined from equilibrium binding experiments. The effect of membrane preparation method and membrane pore size on peak resolution in the alpha spectrum was investigated for pure uranium containing solutions at pH = 6. To mimic more realistic conditions, the selectivity of the membrane was tested using uranium-233 in simulated groundwater. Both uranium-coated membranes prepared from distilled water and groundwater showed resolutions of 80-100 keV in the alpha spectrum and detection efficiencies of 12% for uranium-233. The membranes showed both high resolution and fast preparation time. The permeability of the polymer-coated, ultrafiltration membranes (MWCO 100 kDa) was determined to be 3.74 LMH kPa-1. Overall, this research demonstrates the ability to synthesize robust, uranium-selective materials for the direct concentration of uranium from ground water. Results from this research are laying the groundwork for the development of robust, portable radiation detection techniques capable of analyzing waterborne alpha-emitting radionuclides

Perceptions of French private veterinary practitioners’ on their role inorganic dairy farms and opportunities to improve their advisoryservices for organic dairy farmers

Veterinarians could be the expected sparring partners of organic dairy farmers in promoting animal health which is one of the main organic principles. However, in the past organic dairy farmers did not always consider veterinarians to be pertinent advisors for them. The objectives of this study are – from private veterinary practitioners’ point of views- i) to describe the roles of veterinarians today in organic dairy farmers’ animal health promotion strategies, ii) to identify factors related to organic farming which determine their role on organic dairy farms, and, iii) to identify opportunities for improvement of veterinarians’ advisory services for organic dairy herds. Fourteen veterinarians, providing herd health advisory services to dairy farmers, were interviewed using qualitative semi-structured research interviews. A modified approach to Grounded Theory was used for data collection and analysis. Most often veterinarians had only contact with the organic dairy farmers in cases of individual ill animals or acute herd health problems. Even though certain veterinarians experienced situations and approaches of animal health and welfare on organic dairy farms not meeting their standards, they were not always able to establish themselves an advisory role supporting farmers in improving this. Indeed, organic production principles, regulations and farmers’ health approaches challenged veterinarians’ values on animal health and welfare and their perceptions of ‘good veterinary practices’. Also, some veterinarians considered that there was no direct economic interest for them in the organic dairy sector and that could diminish their willingness to invest in this sector. Possible opportunities for improvement were identified; for example proposing more proactively advice via existing organisations, by making adaptations to advisory services for the organic sector and/or by dissociating veterinarians’ curative role from their advisory role in disease prevention

How can veterinarians be interesting partners for organic dairy farmers? French farmers’ point of views

Organic dairy farmers must live up to the organic goal of ‘good health’ in respect the organic principles and regulation. Veterinarians could be the organic dairy farmers’ expected sparring partners in reaching this goal but have found difficulties to establish advisory relationships with them. The objectives of this study are −from organic dairy farmers’ points of view- (i) to describe farmers’ objectives and strategies regarding herd health, (ii) to describe private veterinarians’ roles in farmers’ animal health promotion strategies and (iii) to identify farmers’ reasons for accepting veterinarians in an advisory role. Fourteen organic dairy farmers were interviewed using qualitative research interviews. Data collection and analysis was performed using a modified approach to Grounded Theory. Organic dairy farmers had animal health management strategies focusing on animal health promotion. Veterinarians had most often solely the role of therapist in farmers’ animal health management strategies. Reasons explaining that veterinarians were not able to establish advisory roles were found in the differences between veterinarians and farmers regarding their animal health strategies and solutions to disease problems. Furthermore, veterinarians did not always share farmers’ (organic) objectives, values and priorities and this could lead to disagreement on the best choice in animal health management practices. This might be further amplified in situations where there exists a lack of dialogue and mutual interest in other

A participatory approach to design monitoring indicators of production diseases in organic dairy farms

Production diseases have an important negative effect on the health and welfare of dairy cows. Although organic animal production systems aim for high animal health levels, compliance with European organic farming regulations does not guarantee that this is achieved. Herd health and production management (HHPM) programs aim at optimizing herd health by preventing disease and production problems, but as yet they have not been consistently implemented by farmers. We hypothesize that one reason is the mismatch between what scientists propose as indicators for herd health monitoring and what farmers would like to use. Herd health monitoring is a key element in HHPM programs as it permits a regular assessment of the functioning of the different components of the production process. Planned observations or measurements of these components are indispensable for this monitoring. In this study, a participatory approach was used to create an environment in which farmers could adapt the indicators proposed by scientists for monitoring the five main production diseases on dairy cattle farms. The adaptations of the indicators were characterized and the farmers’ explanations for the changes made were described. The study was conducted in France and Sweden, which differ in terms of their national organic regulations and existing advisory services. In both countries, twenty certified organic dairy farmers and their animal health management advisors participated in the study. All of the farmers adapted the initial monitoring plan proposed by scientists to specific production and animal health situation on their farm. This resulted in forty unique and farm-specific combinations of indicators for herd health monitoring. All but three farmers intended to monitor five health topics simultaneously using the constructed indicators. The qualitative analysis of the explanations given by farmers for their choices enabled an understanding of farmers’ reasons for selecting and adapting indicators. This is valuable information for scientists involved in the design of HHPM programs. Advisors in the field also can benefit from this participatory approach because it transforms monitoring tools provided by scientists into farm-specific tools

Evaluation of the impact of a Herd Health and Production Management programme in organic dairy cattle farms: a process evaluation approach

Animal health planning activities are not always providing a satisfactory positive impact on herd health and welfare. Moreover, evaluating the impact of advisory programmes is complex due to multiple interacting elements that influence its outcome. Therefore, measuring solely health outcomes is not sufficient: the whole process of the implementation and use of such programmes should be evaluated. In order to evaluate the impact of an intervention with a Herd Health and Production Management (HHPM) programme a process evaluation framework was designed and used. The intervention involved 20 organic dairy cattle farmers and their advisors, in both France and Sweden. In both countries 20 organic dairy farms were selected as control herds. The evaluation of the HHPM programme was based on: (a) the compliance to the programme; (b) the programme’s functions influencing herd health management practices and stimulating dialogue between farmers and advisors; (c) its effectiveness in terms of improving herd health compared with control farms. Complete compliance to the programme was fulfilled by 21 out of 40 farmers–advisors. Results from a questionnaire showed that the programme functioned as intended (e.g. by allowing early identification of herd health problems), stimulated change in farmers’ herd health management practices and farmer–advisor dialogue. Even though the majority of the users perceived that the programme contributed to herd health improvements, no significant differences in health outcomes were found when compared with control farms 12 months after the start of the intervention. The programme allowed creating an environment promoting the exchange of information between farmers and advisors, necessary to define pertinent advice in a farm-specific situation. Future research should aim at improving methods for the evaluation of the effect of advisory programmes, by identifying early indicators for effective advice and developing methods to evaluate the quality of advisory situations without interfering with them

Prediction of soil water retention properties after stratification by combining texture, bulk density and the type of horizon

International audienceAmong the numerous pedotransfer functions (PTFs) published, class-PTfs have received little attention because their accuracy is often considered limited. However, recent studies show that performance of class-PTFs can be similar to the more popular continuous-PTFs. In this study, we compare the performance of PTFs that were derived from a set of 456 horizons collected in France grouped by combinations of texture, bulk density and type of horizon (topsoil and subsoil). The performance of these class-PTFs was validated against water retained at −33 and −1500 kPa. Our results show that the best performance was obtained with class-PTFs that used both texture and bulk density (texture-structural class-PTFs). They also showed that incorporation of horizon type into the PTF did not improve prediction performance. Comparison of performance at −33 and −1500 kPa showed very little difference, thus indicating no bias according to the value of water potential. Finally, the class-PTFs developed are well suited for predicting water retention properties at the continental and national scales because only very basic soils data are available at these scales. A map of the available water capacity (AWC) was established for France using the 1:1 000 000 Soil Geographical Database of France and an averaged AWC of 104 mm was computed for France

Clickable Polymer Scaffolds Enable Ce Recovery with Peptide Ligands

Rare earth elements (REEs) are a vital part of many technologies with particular importance to the renewable energy sector and there is a pressing need for environmentally friendly and sustainable processes to recover and recycle them from waste streams. Functionalized polymer scaffolds are a promising means to recover REEs due to the ability to engineer both transport properties of the porous material and specificity for target ions. In this work, REE adsorbing polymer scaffolds were synthesized by first introducing poly(glycidyl methacrylate) (GMA) brushes onto porous polyvinylidene fluoride (PVDF) surface through activator generated electron transfer atom transfer radical polymerization (AGET ATRP). Azide moieties were then introduced through a ring opening reaction of GMA. Subsequently, REE-binding peptides were conjugated to the polymer surface through copper catalyzed azide alkyne cycloaddition (CuAAC) click chemistry. The presence of GMA, azide, and peptide was confirmed through Fourier transform infrared spectroscopy. Polymer scaffolds functionalized with the REE-binding peptide bound cerium, while polymer scaffolds functionalized with a scrambled control peptide bound significantly less cerium. Importantly, this study shows that the REE binding peptide retains its functionality when bound to a polymer surface. The conjugation strategy employed in this work can be used to introduce peptides onto other polymeric surfaces and tailor surface specificity for a wide variety of ions and small molecules

La qualité des interactions observées en classe et les pratiques déclarées par les enseignantes à l’éducation préscolaire

Cette recherche a permis de mettre en parallèle des données observées et déclarées au sujet de la qualité des interactions enseignante-enfant à l’éducation préscolaire. Pour ce faire, l’outil Classroom Assessment Scoring System (CLASS) a été utilisé; celui-ci est composé de trois domaines : le soutien émotionnel, l’organisation de la classe et le soutien à l’apprentissage. L’échantillon à l’étude est composé de 12 classes d’éducation préscolaire; des observations ont d’abord été menées dans chacune des classes afin d’examiner la qualité des interactions à la maternelle 5 ans. Des entrevues semi-dirigées ont ensuite permis de relever les pratiques déclarées par les enseignantes au sujet des trois domaines qui composent l’outil d’observation. Les données issues de l’observation indiquent que le domaine « organisation de la classe » présente le niveau de qualité le plus élevé, en plus d’être le plus révélé par les enseignantes lors de l’entrevue. De plus, les résultats montrent un score de qualité moyen-faible lié au domaine du soutien à l’apprentissage dans les pratiques observées, ce domaine est d’ailleurs rarement évoqué par les enseignantes lors des entrevues. Ces résultats amènent à discuter du développement professionnel afin de favoriser la qualité des interactions en classe de maternelle

Identification des variables du système d'élevage influençant la santé des vaches laitières en exploitations agrobiologiques européennes

OBJECTIF - Identification des variables qui influencent la santé des vaches laitières en élevage agrobiologique, par une approche globale et systématique des élevages, comme première étape dans l’application de l’Impact Matrix

Evidence for Specific Genotype-Dependent Immune Priming in the Lophotrochozoan Biomphalaria glabrata Snail.

International audienceHistorically, the prevailing view in the field of invertebrate immunity was that invertebrates that do not possess acquired adaptive immunity rely on innate mechanisms with low specificity and no memory. Several recent studies have shaken this paradigm and suggested that the immune defenses of invertebrates are more complex and specific than previously thought. Mounting evidence has shown that at least some invertebrates (mainly Ecdysozoa) show high levels of specificity in their immune responses to different pathogens, and that subsequent reexposure may result in enhanced protection (recently called 'immune priming'). Here, we investigated immune priming in the Lophotrochozoan snail species Biomphalaria glabrata, following infection by the trematode pathogen Schistosoma mansoni. We confirmed that snails were protected against a secondary homologous infection whatever the host strain. We then investigated how immune priming occurs and the level of specificity of B. glabrata immune priming. In this report we confirmed that immune priming exists and we identified a genotype-dependent immune priming in the fresh-water snail B. glabrata