94 research outputs found
Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste
Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900â1000 °C), whereas glass/slag interactions resulted in the formation of magnetite crystals, providing ferrimagnetism. Such behavior could be exploited for applying the obtained glass ceramics as induction heating plates, according to preliminary tests (showing the rapid heating of selected samples, even above 200 °C). The chemical durability and safety of the obtained glass ceramics were assessed by both leaching tests and cytotoxicity tests
New insights into the mineralogy and geochemistry of sb ores from Greece
Antimony is a common metalloid occurring in the form of Sb-sulfides and sulfosalts, in various base and noble metal deposits. It is also present in corresponding metallurgical products (concentrates) and, although antimony has been considered a penalty element in the past, recently it has gained interest due to its classification as a critical raw material (CRM) by the European Union (EU). In the frame of the present paper, representative ore samples from the main Sb-bearing deposits of Greece (Kilkis prefecture, Chalkidiki prefecture (Kassandra Mines), and Chios Isl.) have been investigated. According to optical microscopy and electron probe microanalysis (EPMA) data, the Greek ores contain stibnite (Sb2 S3), boulangerite (Pb5 Sb4 S11), bournonite (PbCuSbS3), bertherite (FeSbS4), and valentinite (Sb2 O3). Bulk analyses by inductively coupled plasma mass spectrometry (ICP-MS) confirmed, for the first time published, the presence of a significant Hg content in the Kilkis Sb-ore. Furthermore, Kassandra Mines ores are found to contain remarkable amounts of Bi, As, Sn, Tl, and Se (excluding Ag, which is a bonus element). The above findings could contribute to potential future exploration and exploitation of Sb ores in Greece
The role of nano-perovskite in the negligible thorium release in seawater from Greek bauxite residue (red mud)
We present new data about the chemical and structural characteristics of bauxite residue (BR) from Greek Al industry, using a combination of microscopic, analytical, and spectroscopic techniques. SEM-EDS indicated a homogeneous dominant âAl-Fe-Ca-Ti-Si-Na-Cr matrixâ, appearing at the microscale. The bulk chemical analyses showed considerable levels of Th (111âÎŒg gâ1), along with minor U (15âÎŒg gâ1), which are responsible for radioactivity (355 and 133âBq kgâ1 for 232Th and 238U, respectively) with a total dose rate of 295ânGy hâ1. Leaching experiments, in conjunction with SF-ICP-MS, using Mediterranean seawater from Greece, indicated significant release of V, depending on S/L ratio, and negligible release of Th at least after 12 months leaching. STEM-EDS/EELS & HR-STEM-HAADF study of the leached BR at the nanoscale revealed that the significant immobility of Th4+ is due to its incorporation into an insoluble perovskite-type phase with major composition of Ca0.8Na0.2TiO3 and crystallites observed in nanoscale. The Th LIII-edge EXAFS spectra demonstrated that Th4+ ions, which are hosted in this novel nano-perovskite of BR, occupy Ca2+ sites, rather than Ti4+ sites. That is most likely the reason of no Th release in Mediterranean seawater
A Prescription for Improving Drug Formulary Decision Making
Gordon Schiff and colleagues present a new tool and checklist to help formularies make decisions about drug inclusion and to guide rational drug use
Swimming in a Sea of Shame: Incorporating Emotions into Explanations of Institutional Reproduction and Change
We theorize the role in institutional processes of what we call the shame nexus, a set of shame-related constructs: felt shame, systemic shame, sense of shame, and episodic shaming. As a discrete emotion, felt shame signals to a person that a social bond is at risk and catalyzes a fundamental motivation to preserve valued bonds. We conceptualize systemic shame as a form of disciplinary power, animated by personsâ sense of shame, a mechanism of ongoing intersubjective surveillance and self-regulation. We theorize how the duo of the sense of shame and systemic shame drives the self-regulation that underpins personsâ conformity to institutional prescriptions and institutional reproduction. We conceptualize episodic shaming as a form of juridical power used by institutional guardians to elicit renewed conformity and reassert institutional prescriptions. We also explain how episodic shaming may have unintended effects, including institutional disruption and recreation, when it triggers sensemaking among targets and observers that can lead to the reassessment of the appropriateness of institutional prescriptions or the value of social bonds. We link the shame nexus to three broad categories of institutional work
The worldwide NORM production and a fully automated gamma-ray spectrometer for their characterization
Materials containing radionuclides of natural origin, which is modified by
human made processes and being subject to regulation because of their
radioactivity are known as NORM. We present a brief review of the main
categories of non-nuclear industries together with the levels of activity
concentration in feed raw materials, products and waste, including mechanisms
of radioisotope enrichments. The global management of NORM shows a high level
of complexity, mainly due to different degrees of radioactivity enhancement and
the huge amount of worldwide waste production. The future tendency of
guidelines concerning environmental protection will require both a systematic
monitoring based on the ever-increasing sampling and high performance of gamma
ray spectroscopy. On the ground of these requirements a new low background
fully automated high-resolution gamma-ray spectrometer MCA_Rad has been
developed. The design of Pb and Cu shielding allowed to reach a background
reduction of two order of magnitude with respect to laboratory radioactivity. A
severe lowering of manpower cost is obtained through a fully automation system,
which enables up to 24 samples to be measured without any human attendance. Two
coupled HPGe detectors increase the detection efficiency, performing accurate
measurements on sample volume (180 cc) with a reduction of sample transport
cost of material. Details of the instrument calibration method are presented.
MCA_Rad system can measure in less than one hour a typical NORM sample enriched
in U and Th with some hundreds of Bq/kg, with an overall uncertainty less than
5%. Quality control of this method has been tested. Measurements of certified
reference materials RGK-1, RGU-2 and RGTh-1 containing concentrations of K, U
and Th comparable to NORM have been performed, resulting an overall relative
discrepancy of 5% among central values within the reported uncertainty.Comment: 21 pages, 4 figures, 6 table
Guiding principles for the development and application of solid-phase phosphorus adsorbents for freshwater ecosystems
While a diverse array of phosphorus (P)-adsorbent materials is currently available for application to freshwater aquatic systems, selection of the most appropriate P-adsorbents remains problematic. In particular, there has to be a close correspondence between attributes of the P-adsorbent, its field performance, and the management goals for treatment. These management goals may vary from a rapid reduction in dissolved P to address seasonal enrichments from internal loading, targeting external fluxes due to anthropogenic sources, or long term inactivation of internal P inventories contained within bottom sediments. It also remains a challenge to develop new methods and materials that are ecologically benign and cost-effective. We draw on evidence in the literature and the authorsâ personal experiences in the field, to summarise the attributes of a range of P-adsorbent materials. We offer 'guiding principles' to support practical use of existing materials and outline key development needs for new materials
Bauxite residue (Red mud) as a pulverised fuel ash substitute in the manufacture of lightweight aggregate
This study looked at the potential of bauxite residue or red mud to be used in the manufacture of lightweight aggregate in replacement of pulverised fuel ash (PFA), commonly used as a way of recycling problematic wastes. The percentage replacements of red mud with PFA were as follows: 25, 31, 38, 44 and 50%. These were blended in a mix with waste excavated clay and sewage sludge â all from the Chongqing municipality in China. Lightweight pellets were produced using a Trefoil rotary kiln and were sintered to 1200 °C. Results showed that 44 % bauxite residue replacement produced lightweight pellets with the highest compressive strength, highest density and largest water holding capacity. This would be expected in materials with a low level of silicates, which causes insufficient glass phase viscosity and therefore poor bloating during firing; producing an aggregate with a higher density but with open pores that allowed for larger water absorption. All ratios of red mud aggregates were significantly reduced in pH after firing to around pH 8, and this reduced the leachability of the aggregates to levels below those set by the European landfill directive (2003/33/EC)
Category spanning, evaluation, and performance: revised theory and test on the corporate law market
Studies suggest that category-spanning organizations receive lower evaluation and perform worse than organizations focused on a single category. We propose that (1) these effects are contingent on clients' theory of value and that as clients expect more sophisticated services, they tend to value category spanners more positively and (2) the evaluation of producers mediates the relationship between category spanning and performance. We test our hypotheses using original data on corporate legal services in three markets (London, New York City, and Paris) over the decade 2000-2010. We find that (1) category spanners receive a better evaluation, and more so when their categorical combination is more inclusive and (2) evaluation mediates significantly the relationship between category spanning and performance. This study enriches our understanding of how audiences apprehend a whole market category system and why organizations span categories.The HEC
Foundation and the Society & Organizations Research Center provided financial support
for this research
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Holier than thou? Identity buffers and adoption of controversial practices in the Islamic banking category
Existing scholarship on categories frequently highlights how some category members may violate codes that others diligently abide by. In this paper, we take into account the differences in identity across category members, and ask how these relative differences determine their response to a code-violating change. Taking a case where category members are clearly identified as âinsidersâ
and âoutsidersâ, we argue that insidersâ reaction to a code violation depends upon the extent to which they believe their identity to be distinct from the code violatorâs, who might be an insider or an outsider. Specifically, we suggest that it is the presence or absence of an âidentity bufferâ â i.e., a relative identity advantage â which determines insidersâ reaction. We hypothesize that when a code violation is introduced by a fellow category insider, the focal insider will be more likely to refrain from the practice. When it is an outsider who introduces the code violation, insiders will be more likely to adopt the code violation as long as they can retain an identity buffer. We further posit that when outsiders adopt code-preserving behavior, thus narrowing the identity buffer between insiders and outsiders, it will mitigate insidersâ likelihood of code violation adoption. We test and find support for our hypotheses using data on Islamic banking industry in 12 countries (2003-2014)
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