Combustion of Shelled Corn in a Small-Scale Fluidized Bed

Fluidized bed combustion is an attractive method of extracting energy from a wide variety of fuels. This study analyzed operating parameters for shelled corn combustion in a 15.2 cm diameter, 44-kW atmospheric fluidized bed burner. Variables studied include sand particle size distribution, fuel particle size, moisture, air/fuel ratio, and bed depth. Increasing moisture from 16% to 22% reduced bottom bed temperature slightly, without significantly changing the rest of the bed profile temperatures. Increasing bed depth from 0.58 m to 0.71 m reduced the freeboard temperature while increasing heat energy in the sand bed. A system based reaction rate constant was developed and mass loss profiles and residence times of the various particle sizes were determined. Solving an energy balance for the system, k values (reaction rates) gave 0.3 min-1 for whole shelled corn and 0.4 min-1 or greater for particles sizes smaller than 5.7 mm. Combustion characteristics, chemical and physical properties, and fluidization behavior of whole and cracked shelled corn are presented. In particular, the activation energy for ground corn was found to be 68,630 J/mol using ASTM E 1641-04. Combustion efficiencies ranged from 93-99% for particles smaller than 5.7 mm and approximately 85% for the whole shelled corn. It should be noted that feed rates were the fixed variable, so excess air was lower for the whole shelled corn. More studies to control the air-fuel ratio are needed. Design strategies for the fluidized bed combustor including bed material and size, available air flow, and air/fuel ratios are discussed

Patient doses in CT examinations in Switzerland: implementation of national diagnostic reference levels

Diagnostic reference levels (DRLs) were established for 21 indication-based CT examinations for adults in Switzerland. One hundred and seventy-nine of 225 computed tomography (CT) scanners operated in hospitals and private radiology institutes were audited on-site and patient doses were collected. For each CT scanner, a correction factor was calculated expressing the deviation of the measured weighted computed tomography dose index (CTDI) to the nominal weighted CTDI as displayed on the workstation. Patient doses were corrected by this factor providing a realistic basis for establishing national DRLs. Results showed large variations in doses between different radiology departments in Switzerland, especially for examinations of the petrous bone, pelvis, lower limbs and heart. This indicates that the concept of DRLs has not yet been correctly applied for CT examinations in clinical routine. A close collaboration of all stakeholders is mandatory to assure an effective radiation protection of patients. On-site audits will be intensified to further establish the concept of DRLs in Switzerlan

An audit of diagnostic reference levels in interventional cardiology and radiology: are there differences between academic and non-academic centres?

A wide variation in patient exposure has been observed in interventional radiology and cardiology. The purpose of this study was to investigate the patient dose from fluoroscopy-guided procedures performed in non-academic centres when compared with academic centres. Four procedures (coronary angiography, percutaneous coronary intervention, angiography of the lower limbs and percutaneous transluminal angioplasty of the lower limbs) were evaluated. Data on the dose-area product, fluoroscopy time and number of images for 1000 procedures were obtained from 23 non-academic centres and compared with data from 5 academic centres. No differences were found for cardiology procedures performed in non-academic centres versus academic ones. However, significantly lower doses were delivered to patients for procedures of the lower limbs when they were performed in non-academic centres. This may be due to more complex procedures performed in the academic centres. Comparison between the centres showed a great variation in the patient dose for these lower limb procedure

A Nonzero Gap Two-Dimensional Carbon Allotrope from Porous Graphene

Graphene is considered one of the most promising materials for future electronic. However, in its pristine form graphene is a gapless material, which imposes limitations to its use in some electronic applications. In order to solve this problem many approaches have been tried, such as, physical and chemical functionalizations. These processes compromise some of the desirable graphene properties. In this work, based on ab initio quantum molecular dynamics, we showed that a two-dimensional carbon allotrope, named biphenylene carbon (BPC) can be obtained from selective dehydrogenation of porous graphene. BPC presents a nonzero bandgap and well-delocalized frontier orbitals. Synthetic routes to BPC are also addressed.Comment: Published on J. Phys. Chem. C, 2012, 116 (23), pp 12810-1281

Ideological Labels in America

This paper extends Ellis and Stimson’s (Ideology in America. New York: Cambridge UniversityPress, 2012) study of the operational-symbolic paradox using issue-level measures of ideological incongruence based on respondent positions and symbolic labels for these positions across 14 issues. Like Ellis and Stimson, we find that substantial numbers—over 30 %—of Americans experience conflicted conservatism. Our issue-level data reveal, furthermore, that conflicted conservatism is most common on the issues of education and welfare spending. In addition, we also find that 20 % of Americans exhibit conflicted liberalism. We then replicate Ellis and Stimson’s finding that conflicted conservatism is associated with low sophistication and religiosity, but also find that it is associated with being socialized in a post-1960s generation and using Fox News as a main news source. Finally, we show the important role played by identities, with both conflicted conservatism and conflicted liberalism linked with partisan and ideological identities, and conflicted liberalism additionally associated with ethnic identities

Phylogeography of an endangered disjunct herb: long-distance dispersal, refugia and colonization routes

Quaternary glacial cycles appear to have had a consistent role in shaping the genetic diversity and structure of plant species. Despite the unusual combination of the characteristics of the western Mediterranean– Macaronesian area, there are no studies that have specifically examined the effects of palaeoclimatic and palaeogeographic factors on the genetic composition and structure of annual herbs. Astragalus edulis is a disjunct endemic found in the easternmost Canary Islands and the semi-arid areas of north-eastern Africa and south-eastern Iberian Peninsula. This endangered species shows no evident adaptations to long-distance dispersal. Amplified fragment length polymorphism (AFLP) data and plastid DNA sequences were analysed from a total of 360 individuals distributed throughout the range of this species. The modelled potential distribution of A. edulis under current conditions was projected over the climatic conditions of the Last Interglacial (130 ka BP) and Last Glacial Maximum (21 ka BP) to analyse changes in habitat suitability and to look for associations between the modelling and genetic results. Amplified fragment length polymorphism analysis showed clear phylogeographic structure with four distinct genetic clusters. Approximate Bayesian computation (ABC) models based on plastid DNA sequences indicated a Middle Pleistocene long-distance dispersal event as the origin of the populations of the Canary Islands. The models also suggested south-western Morocco as the ancestral area for the species, as well as subsequent colonization of north-eastern Morocco and the Iberian Peninsula. The data compiled indicated the possibility of the presence of refuge areas at favourable locations around the High Atlas and Anti-Atlas mountain ranges. Moreover, palaeodistribution models strongly support the events inferred by ABC modelling and show the potential distribution of the species in the past, suggesting a putative colonization route.This work has been financed by the Spanish Ministerio de Ciencia e Innovación through the projects CGL2012- 32574 and REN2003-09427, as well as by the Andalusian Consejería de Innovación, Ciencia y Tecnología through the project RNM1067. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript

Simulated Warming Differentially Affects the Growth and Competitive Ability of Centaurea maculosa Populations from Home and Introduced Ranges

Climate warming may drive invasions by exotic plants, thereby raising concerns over the risks of invasive plants. However, little is known about how climate warming influences the growth and competitive ability of exotic plants from their home and introduced ranges. We conducted a common garden experiment with an invasive plant Centaurea maculosa and a native plant Poa pratensis, in which a mixture of sand and vermiculite was used as a neutral medium, and contrasted the total biomass, competitive effects, and competitive responses of C. maculosa populations from Europe (home range) and North America (introduced range) under two different temperatures. The warming-induced inhibitory effects on the growth of C. maculosa alone were stronger in Europe than in North America. The competitive ability of C. maculosa plants from North America was greater than that of plants from Europe under the ambient condition whereas this competitive ability followed the opposite direction under the warming condition, suggesting that warming may enable European C. maculosa to be more invasive. Across two continents, warming treatment increased the competitive advantage instead of the growth advantage of C. maculosa, suggesting that climate warming may facilitate C. maculosa invasions through altering competitive outcomes between C. maculosa and its neighbors. Additionally, the growth response of C. maculosa to warming could predict its ability to avoid being suppressed by its neighbors

Supporting self-regulated learning

Self-regulated learning (SRL) competences are crucial for lifelong learning. Their cultivation requires the right balance between freedom and guidance during the learning processes. Current learning systems and approaches, such as personal learning environments, give overwhelming freedom, but also let weak learners alone. Other systems, such as learning management systems or adaptive systems, tend to institutionalise learners too much, which does not support the development of SRL competences. This chapter presents possibilities and approaches to support SRL by the use of technology. After discussing the theoretical background of SRL and related technologies, a formal framework is presented that describes the SRL process, related competences, and guidelines. Furthermore, a variety of methods is presented, how learners can be supported to learn in a self-regulated way

Identification of Nedd4 E3 Ubiquitin Ligase as a Binding Partner and Regulator of MAK-V Protein Kinase

MAK-V/Hunk is a scantily characterized AMPK-like protein kinase. Recent findings identified MAK-V as a pro-survival and anti-apoptotic protein and revealed its role in embryonic development as well as in tumorigenesis and metastasis. However molecular mechanisms of MAK-V action and regulation of its activity remain largely unknown. We identified Nedd4 as an interaction partner for MAK-V protein kinase. However, this HECT-type E3 ubiquitin ligase is not involved in the control of MAK-V degradation by the ubiquitin-proteasome system that regulates MAK-V abundance in cells. However, Nedd4 in an ubiquitin ligase-independent manner rescued developmental defects in Xenopus embryos induced by MAK-V overexpression, suggesting physiological relevance of interaction between MAK-V and Nedd4. This identifies Nedd4 as the first known regulator of MAK-V function