39 research outputs found
The dynamic cilium in human diseases
Cilia are specialized organelles protruding from the cell surface of almost all mammalian cells. They consist of a basal body, composed of two centrioles, and a protruding body, named the axoneme. Although the basic structure of all cilia is the same, numerous differences emerge in different cell types, suggesting diverse functions. In recent years many studies have elucidated the function of 9+0 primary cilia. The primary cilium acts as an antenna for the cell, and several important pathways such as Hedgehog, Wnt and planar cell polarity (PCP) are transduced through it. Many studies on animal models have revealed that during embryogenesis the primary cilium has an essential role in defining the correct patterning of the body. Cilia are composed of hundreds of proteins and the impairment or dysfunction of one protein alone can cause complete loss of cilia or the formation of abnormal cilia. Mutations in ciliary proteins cause ciliopathies which can affect many organs at different levels of severity and are characterized by a wide spectrum of phenotypes. Ciliary proteins can be mutated in more than one ciliopathy, suggesting an interaction between proteins. To date, little is known about the role of primary cilia in adult life and it is tempting to speculate about their role in the maintenance of adult organs. The state of the art in primary cilia studies reveals a very intricate role. Analysis of cilia-related pathways and of the different clinical phenotypes of ciliopathies helps to shed light on the function of these sophisticated organelles. The aim of this review is to evaluate the recent advances in cilia function and the molecular mechanisms at the basis of their activity
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LCA of Disposal Practices for Arsenic-Bearing Iron Oxides Reveals the Need for Advanced Arsenic Recovery
Iron (Fe)-based groundwater treatment removes carcinogenic arsenic (As) effectively but generates toxic As-rich Fe oxide water treatment residuals (As WTRs) that must be managed appropriately to prevent environmental contamination. In this study, we apply life cycle assessment (LCA) to compare the toxicity impacts of four common As WTR disposal strategies that have different infrastructure requirements and waste control: (i) landfilling, (ii) brick stabilization, (iii) mixture with organic waste, and (iv) open disposal. The As disposal toxicity impacts (functional unit = 1.0 kg As) are compared and benchmarked against impacts of current methods to produce marketable As compounds via As mining and concentrate processing. Landfilling had the lowest non-carcinogen toxicity (2.0 × 10-3 CTUh), carcinogen toxicity (3.8 × 10-5 CTUh), and ecotoxicity (4.6 × 103 CTUe) impacts of the four disposal strategies, with the largest toxicity source being As emission via sewer discharge of treated landfill leachate. Although landfilling had the lowest toxicity impacts, the stored toxicity of this strategy was substantial (ratio of stored toxicity/emitted As = 13), suggesting that landfill disposal simply converts direct As emissions to an impending As toxicity problem for future generations. The remaining disposal strategies, which are frequently practiced in low-income rural As-affected areas, performed poorly. These strategies yielded ∼3-10 times greater human toxicity and ecotoxicity impacts than landfilling. The significant drawbacks of each disposal strategy indicated by the LCA highlight the urgent need for new methods to recover As from WTRs and convert it into valuable As compounds. Such advanced As recovery technologies, which have not been documented previously, would decrease the stored As toxicity and As emissions from both WTR disposal and from mining As ore
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Technoeconomic analysis of metal-organic frameworks for bulk hydrogen transportation
Numerous adsorption-based technologies are emerging as candidates for hydrogen transportation, and yet little is known about their practical viability. As such, new approaches are needed to conduct early validation of emerging hydrogen transportation concepts despite a lack of clear criteria for viable future hydrogen supply chains. In this work, we conduct technoeconomic modeling to quantify cost, performance, and relations between system components for early-stage adsorbent-based hydrogen supply chains. We compare results with the cost and performance of high pressure compressed gas and liquid hydrogen trucks in the same applications. Using available experimental adsorption data, we simulate the gravimetric performance of tube trailer trucks packed with metal-organic frameworks (MOFs) operated at 100 bar and 77 or 200 K. We also extrapolated available experimental data to study a third scenario where tube trailer trucks are operated at ambient temperature and 250 bar. Models developed for these conditions represent feasible operation scenarios where pressurization or cooling costs can be reduced relative to compressed or liquid hydrogen truck systems. Results suggest that the levelized cost of long-distance transmission, including a gas terminal and MOF-based truck fleet, ranges from 29.0 per kg H2. The levelized cost of transmission using compressed hydrogen gas trucks at 350 and 500 bar and liquid hydrogen trucks is substantially lower, at 1.7 and 11.8 and 4.7, 3.9 per kg H2, respectively. Key opportunities identified for lowering costs are: increasing the hydrogen capacity of the tube system by developing new MOFs with higher volumetric deliverable capacities, flexible allowable daily deliveries per refueling station, increasing the cycling stability of the MOF, and driverless trucks
Towards a ‘smart’ cost–benefit tool: using machine learning to predict the costs of criminal justice policy interventions
Four thousand years of plant exploitation in the Chad Basin of northeast Nigeria I: The archaeobotany of Kursakata
A comprehensive German business cycle chronology
Business cycles, Turning points, Business cycle dating algorithm, Non-parametric, Markov-switching, E32, C14, C22,