Arsenic derived from natural sources occurs in groundwater in many countries, affecting the health of millions of people. The combined effects of As(V) reduction and diagenesis of iron oxide minerals ...on arsenic mobility are investigated in this study by comparing As(V) and As(III) sorption onto amorphous iron oxide (HFO), goethite, and magnetite at varying solution compositions. Experimental data are modeled with a diffuse double layer surface complexation model, and the extracted model parameters are used to examine the consistency of our results with those previously reported. Sorption of As(V) onto HFO and goethite is more favorable than that of As(III) below pH 5−6, whereas, above pH 7−8, As(III) has a higher affinity for the solids. The pH at which As(V) and As(III) are equally sorbed depends on the solid-to-solution ratio and type and specific surface area of the minerals and is shifted to lower pH values in the presence of phosphate, which competes for sorption sites. The sorption data indicate that, under most of the chemical conditions investigated in this study, reduction of As(V) in the presence of HFO or goethite would have only minor effects on or even decrease its mobility in the environment at near-neutral pH conditions. As(V) and As(III) sorption isotherms indicate similar surface site densities on the three oxides. Intrinsic surface complexation constants for As(V) are higher for goethite than HFO, whereas As(III) binding is similar for both of these oxides and also for magnetite. However, decrease in specific surface area and hence sorption site density that accompanies transformation of amorphous iron oxides to more crystalline phases could increase arsenic mobility.
“More research is needed” is an iconic catchphrase used by scientists worldwide. Yet policy and management decisions are continually being made with variable levels of reliance on scientific ...knowledge. Funding agencies have provided incentives for knowledge exchange at the interfaces between science and policy or practice, yet it remains the exception rather than the rule within academic institutions. An important step forward would be the establishment and professionalization of knowledge brokering (i.e., as a complement to existing technology transfer and communications departments). This would require an explicit commitment of resources by both funding agencies and institutions. Many academic scientists are genuinely interested in the applications of their research. This interest could be stimulated by providing support for the process of knowledge brokering and by integrating the natural, social, and engineering sciences to address broad policy- and practice-relevant questions.
•We adapt a framework to compare integration across four synthesis processes.•We identify challenges and derive recommendations for future synthesis processes.•We recommend initiating synthesis ...processes concurrently with research projects.•We consider professional competences and management skills crucial for integration.•We recommend the promotion of communities of practice to support integration.
What challenges do researchers face when leading transdisciplinary integration? We address this question by analyzing transdisciplinary integration within four thematic synthesis processes of the Swiss National Research Programme (NRP 61) on Sustainable Water Management. We adapt an existing analytical framework to compare transdisciplinary integration across the four synthesis processes regarding different types of generated knowledge (systems, target and transformation knowledge), different types of involved actors (core team, steering committee, advisory board, scientific experts and practice experts) and different levels of actor involvement (information, consultation and collaboration) at different stages of the processes. Based on a structured ex-post self-evaluation of the four synthesis processes, we present core challenges of transdisciplinary integration as perceived by core team members of the four synthesis processes and formulate empirically derived recommendations for designing and implementing future processes. We suggest that future synthesis processes should be conceptualized and initiated concurrently with all other individual research projects, involving a phasing-in stage where leaders conceptualize transdisciplinary integration, an intermediate stage of intense knowledge integration involving all relevant actor groups in a functional and dynamic way, and a final phasing out stage, where synthesis results are consolidated within the research program, validated by different actor groups and diffused to the target audiences. We argue that transdisciplinary integration requires professional competences, management skills and enough time. Finally, we suggest fostering communities of practice (CoP) to link committed leaders and enable mutual learning processes beyond the boundaries of individual synthesis projects or research programs.
What methods and procedures support transdisciplinary knowledge integration? We address this question by exploring knowledge integration within four thematic synthesis processes of the Swiss National ...Research Programme 61 Sustainable Water Management (NRP 61). Drawing on literature from inter- and transdisciplinary research, we developed an analytical framework to map different methods and procedures of knowledge integration. We use this framework to characterize the variety of methods and procedures that were combined in the four processes to produce thematic synthesis reports. We suggest that the variety of combinations observed reflects the different objectives and questions that guided the processes of knowledge integration as well as the different roles that leaders assumed in these processes. Although the framework was developed in the course of NRP 61, we consider it as a basis for designing ex ante new synthesis processes by defining and sequencing different synthesis stages and by identifying, for each stage, the contributions of specific scientific and societal actors, the purpose of their contributions, and the methods and procedures supporting their contributions. Used in a formative evaluation process, the framework supports reflection on and adaptation of synthesis processes and also facilitates the generation of new knowledge for designing future processes.
This study examined physicians’ participation and performance in the examinations administered by the Asian Intensive Reader of Pneumoconiosis (AIR Pneumo) program from 2008 to 2020 and compared ...radiograph readings of physicians who passed with those who failed the examinations. Demography of the participants, participation trends, pass/fail rates, and proficiency scores were summarized; differences in reading the radiographs for pneumoconiosis of physicians who passed the examinations and those who failed were evaluated. By December 2020, 555 physicians from 20 countries had taken certification examinations; the number of participants increased in recent years. Reported background specialty training and work experience varied widely. Passing rate and mean proficiency score for participants who passed were 83.4% and 77.6 ± 9.4 in certification, and 76.8% and 88.1 ± 4.5 in recertification examinations. Compared with physicians who passed the examinations, physicians who failed tended to classify test radiographs as positive for pneumoconiosis and read a higher profusion; they likely missed large opacities and pleural plaques and had a lower accuracy in recognizing the shape of small opacities. Findings suggest that physicians who failed the examination tend to over-diagnose radiographs as positive for pneumoconiosis with higher profusion and have difficulty in correctly identifying small opacity shape.
Hydroxyapatite (Ca10(PO4)6(OH)2, HAP), both as a synthetic material and as a constituent of bone char, can serve as an effective and relatively inexpensive filter material for fluoride (F–) removal ...from drinking water in low-income countries. Fluoride uptake on HAP can occur through different mechanisms, which are, in principle, influenced by solution composition. Suspensions of HAP (2 g L–1) were equilibrated under controlled pH conditions (pH 6.5, 7.3, 9.5) at 25 °C for 28 d after the addition of different F– concentrations (0.5–7.0 mM). The reacted HAP solids were examined with Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), and Nano Secondary Ion Mass Spectroscopy (NanoSIMS). Fluoride uptake on HAP was dependent on pH, with the highest capacity at pH 6.5; the lowest uptake was found at pH 9.5. Under all experimental conditions, the thermodynamically stable mineral phase was fluorapatite, (Ca10(PO4)6F2, FAP). Fluoride uptake capacity was quantified on the basis of FTIR and XPS analysis, which was consistent with F– uptake from solution. The results of XPS and NanoSIMS analyses indicate that a fluoridated surface layer with a thickness of several nanometers is formed on nanosized HAP.
Oxidation of arsenite, As(III), to arsenate, As(V), is required for the efficient removal of arsenic by many water treatment technologies. The photocatalyzed oxidation of As(III) on titanium dioxide, ...TiO2, offers an environmentally benign method for this unit operation. In this study, we explore the efficacy and mechanism of TiO2-photocatalyzed As(III) oxidation at circumneutral pH and over a range of As(III) concentrations approaching those typically encountered in water treatment systems. We focus on the effect of As adsorption on observed rates of photooxidation. Adsorption (in the dark) of both As(III) and As(V) on Degussa P25 TiO2 was examined at pH 6.3 over a range in dissolved arsenic concentrations, Asdiss, of 0.10−89 μM and 0.2 or 0.05 g L-1 TiO2 for As(III) and As(V), respectively. Adsorption isotherms generally followed the Langmuir−Hinshelwood model with As(III) exhibiting an adsorption maxima of 32 μmol g-1. As(V) adsorption did not reach a plateau under the experimental conditions examined; the maximum adsorbed concentration observed was 130 μmol g-1. The extent of As(III) and As(V) adsorption observed at the beginning and end of the kinetic studies was consistent with that observed in the adsorption isotherms. Kinetic studies were performed in batch systems at pH 6.3 with 0.8−42 μM As(III) and 0.05 g L-1 TiO2; complete oxidation of As(III) was observed within 10−60 min of irradiation at 365 nm. The observed effect of As(III) concentration on reaction kinetics was consistent with surface saturation at higher concentrations. Addition of phosphate at 0.5−10 μM had little effect on either As(III) sorption or its photooxidation rate but did inhibit adsorption of the product As(V). The selective use of hydroxyl radical quenchers and superoxide dismutase demonstrated that superoxide, O2 •-, plays a major role in the oxidation of As(III) to As(V).
This study examined inter-observer agreement and diagnostic accuracy in classifying radiographs for pneumoconiosis among Asian physicians taking the AIR Pneumo examination. We compared agreement and ...diagnostic accuracy for parenchymal and pleural lesions across residing countries, specialty training, and work experience using data on 93 physicians. Physicians demonstrated fair to good agreement with kappa values 0.30 (95% CI: 0.20–0.40), 0.29 (95% CI: 0.23–0.36), 0.59 (95% CI: 0.52–0.67), and 0.65 (95% CI: 0.55–0.74) in classifying pleural plaques, small opacity shapes, small opacity profusion, and large opacities, respectively. Kappa values among Asian countries ranging from 0.25 to 0.55 (pleural plaques), 0.47 to 0.73 (small opacity profusion), and 0.55 to 0.69 (large opacity size). The median Youden’s J index (interquartile range) for classifying pleural plaque, small opacity, and large opacity was 61.1 (25.5), 76.8 (29.3), and 88.9 (23.3), respectively. Radiologists and recent graduates showed superior performance than other groups regarding agreement and accuracy in classifying all types of lesions. In conclusion, Asian physicians taking the AIR Pneumo examination were better at classifying parenchymal lesions than pleural plaques using the ILO classification. The degree of agreement and accuracy was different among countries and was associated with background specialty training.
Experiments were conducted to quantify Fe(II) sorption onto goethite in the absence and presence of As(III). The experimental data obtained in single-sorbate experiments were modeled using a diffuse ...double layer surface complexation model and used to predict and compare sorption in dual-sorbate systems. The sorption process was shown to be reversible by the complete recovery of sorbed Fe(II) upon extraction with 0.5 N HCl. Sorption of Fe(II) increases with increasing pH, as observed previously for various iron oxides. Sorption isotherms obtained between pH 6.0 and 7.5 showed continuous increase in sorption density with increase in dissolved Fe(II) concentration; under these conditions, surface saturation was approached but not reached. Experiments conducted in the absence and presence of 500 and 1000 μM total As(III) did not show any significant difference in the Fe(II) sorption density. As(III) sorption density did not change with increasing sorbed Fe(II) concentration when the total arsenic concentration was 500 μM. However, when the total As(III) concentration was 1000 μM, As(III) sorption densities increased almost linearly with increasing sorbed Fe(II) concentrations. The model provided a good-to-adequate description of Fe(II) and As(III) sorption in single-sorbate systems over a range of experimental conditions but failed to predict the experimental observations in dual-sorbate systems. The predicted sorption densities for both As(III) and Fe(II) were lower than those observed. These discrepancies illustrate problems that may arise when model parameters obtained in single-sorbate systems are used to predict sorption in multi-sorbate systems where all sorbates are presumed to compete for the same sites. The lack of competition observed between As(III) and Fe(II) for sorption sites indicate that the concurrent release of Fe(II) and As(III) during reductive dissolution of iron oxides, inferred as the mechanism of arsenic mobilization in many reducing ground waters, may have relatively minor effects on the subsequent re-sorption of As(III) to residual iron oxides remaining in the sediment.
The establishment of the field of implementation science was motivated by the understanding that medical and health research alone is insufficient to generate better health outcomes. With strong ...support from funding agencies for medical research, implementation science promotes the application of a structured framework or model in the implementation of research-based results, specifically evidence-based practices (EBPs). Furthermore, explicit consideration is given to the context of EBP implementation (i.e., socio-economic, political, cultural, and institutional factors that could affect the implementation process). Finally, implementation is monitored in a robust and rigorous way. Today, the field of implementation science supports conferences and professional societies as well as one dedicated journal and numerous others with related content. The goal of these various activities is to reduce the estimated, average “bench to bedside” time lag of 17 years for uptake of EBPs from health research into routine practice. Despite similar time lags and impediments to uptake in the environmental domain, a parallel field of implementation science for the environment has not (yet) emerged. Although some parallels in needs and opportunities can easily be drawn between the health and environmental domains, a detailed mapping exercise is needed to understand which aspects of implementation science could be applied in the environmental domain either directly or in a modified form. This would allow an accelerated development of implementation science for the environment.
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