Iron-phosphate-based chemically bonded phosphate ceramics for mixed waste stabilization

In an effort to develop chemically bonded phosphate ceramics for mixed waste stabilization, a collaborative project to develop iron-phosphate based ceramics has been initiated between Argonne National Laboratory and the V. G. Khlopin Radium Institute in St. Petersburg, Russia. The starter powders are oxides of iron that are generated as inexpensive byproduct materials in the iron and steel industry. They contain iron oxides as a mixture of magnetite (Fe{sub 3}O{sub 4}) and haematite (Fe{sub 2}O{sub 3}). In this initial phase of this project, both of these compounds were investigated independently. Each was reacted with phosphoric acid solution to form iron phosphate ceramics. In the case of magnetite, the reaction was rapid. Adding ash as the waste component containing hazardous contaminants resulted in a dense and hard ceramic rich in glassy phase. On the other hand, the reaction of phosphoric acid solution with a mixture of haematite and ash waste contaminated with cesium and americium was too slow. Samples had to be molded under pressure. They were cured for 2-3 weeks and then hardened by heating at 350{degrees}C for 3 h. The resulting ceramics in both cases were subjected to physical tests for measurement of density, open porosity, compression strength, phase analyses using X-ray diffraction and differential thermal analysis, and leaching tests using toxicity characteristic leaching procedure (TCLP) and ANS 16.1 with 7 days of leaching. Using the preliminary information obtained from these tests, we evaluated these materials for stabilization of Department of Energy`s mixed waste streams

Effects of aqueous environment on long-term durability of phosphate-bonded ceramic waste forms

Over the last few years, Argonne National Laboratory has been developing room-temperature-setting chemically-bonded phosphate ceramics for solidifying and stabilizing low-level mixed wastes. This technology is crucial for stabilizing waste streams that contain volatile species and off-gas secondary waste streams generated by high-temperature treatment of such wastes. Magnesium phosphate ceramic has been developed to treat mixed wastes such as ash, salts, and cement sludges. Waste forms of surrogate waste streams were fabricated by acid-base reactions between the mixtures of magnesium oxide powders and the wastes, and phosphoric acid or acid phosphate solutions. Dense and hard ceramic waste forms are produced in this process. The principal advantage of this technology is that the contaminants are immobilized by both chemical stabilization and subsequent microencapsulation of the reaction products. This paper reports the results of durability studies conducted on waste forms made with ash waste streams spiked with hazardous and radioactive surrogates. Standard leaching tests such as ANS 16.1 and TCLP were conducted on the final waste forms. Fates of the contaminants in the final waste forms were established by electron microscopy. In addition, stability of the waste forms in aqueous environments was evaluated with long-term water-immersion tests

Stabilization of hazardous ash waste with newberyite-rich chemically bonded magnesium phosphate ceramic

A novel newberyite-rich magnesium-phosphate ceramic, intended for the stabilization of the US Department of Energy`s low-level mixed-waste streams, has been developed by an acid-base reaction between magnesium oxide and a phosphoric acid solution. The reaction slurry, formed at room temperature, sets rapidly and forms a lightweight hard ceramic with low open porosity and a high compression strength of {approx} 6,200 psi. It is a composite of stable mineral phases of newberyite, luenebergite, and residual Mg oxide. Using this matrix, the authors developed superior waste forms for a surrogate ash waste stream. The final waste form is a low-permeability structural-quality ceramic, in which hazardous contaminants are chemically fixed and physically encapsulated. The compression strength of the waste form is an order of magnitude higher than the land disposal requirement, even at high waste loading. The high compression strength is attributed to stronger bonds in the waste form that result from participation of ash waste in the setting reactions. Long-term leaching studies show that the waste form is stable in an aqueous environment. The chemically bonded phosphate ceramic approach in this study may be a simple, inexpensive, and efficient method for fabricating high-performance waste forms either for stabilizing waste streams or for developing value-added construction materials from high-volume benign waste streams

Molecular epidemiology and genetic diversity of human astrovirus in South Korea from 2002 to 2007

AbstractThe present study was conducted to survey the prevalence and genotypic distribution of human astrovirus (HAstV) circulating in South Korea. Of 160,027 patients with acute gastroenteritis, 2,057 (1.3%) were positive for HAstV antigen. We determined the genotypes of 187 HAstV strains collected from laboratories across the country. Genetic analysis revealed genotype 1 to be the most prevalent, accounting for 72.19% of the strains, followed by genotypes 8 (9.63%), 6 (6.95%), 4 (6.42%), 2 (3.21%) and 3 (1.60%). Our findings indicate that HAstV is less common but, even so, a potentially important viral agent of gastroenteritis in South Korea, with significant genetic diversity among circulating HAstV strains

Leaching behavior of phosphate-bonded ceramic waste forms

Over the last few years, Argonne National Laboratory has been developing room-temperature-setting chemically bonded phosphate ceramics for solidifying and stabilizing low-level mixed wastes. This technology is crucial for stabilizing waste streams that contain volatile species and off-gas secondary waste streams generated by high-temperature treatment of such wastes. We have developed a magnesium phosphate ceramic to treat mixed wastes such as ash, salts, and cement sludges. Waste forms of surrogate waste streams were fabricated by acid-base reactions between the mixtures of magnesium oxide powders and the wastes, and phosphoric acid or acid phosphate solutions. Dense and hard ceramic waste forms are produced in this process. The principal advantage of this technology is that the contaminants are immobilized by both chemical stabilization and subsequent microencapsulation of the reaction products. This paper reports the results of durability studies conducted on waste forms made with ash waste streams spiked with hazardous and radioactive surrogates. Standard leaching tests such as ANS 16.1 and TCLP were conducted on the final waste forms. Fates of the contaminants in the final waste forms were established by electron microscopy. In addition, stability of the waste forms in aqueous environments was evaluated with long-term water-immersion tests

AMP-activated protein kinase-α1 as an activating kinase of TGF-β-activated kinase 1 has a key role in inflammatory signals

Although previous studies have proposed plausible mechanisms of the activation of transforming growth factor-β-activated kinase 1 (TAK1) in inflammatory signals, including Toll-like receptors (TLRs), its activating kinase still remains to be unclear. In the present study, we have provided evidences that AMP-activated protein kinase (AMPK)-α1 has a pivotal role for activating TAK1, and thereby regulate NF-κB-dependent gene expressions in inflammatory signaling mediated by TLR4 and TNF-α stimulation. AMPK-α1 specifically interacts with TAK1 and reciprocally regulates their kinase activities. Upon the stimulation of lipopolysaccharide, AMPK-α1-knockdown (AMPK-$\alpha 1^{KD}$) or TAK1-knockdown human monocytic THP-1 cells exhibit a dramatic reduction in the TAK1 or AMPK-α1 kinase activity, respectively, and subsequent suppressions of its downstream signaling cascades, which further leads to inhibitions of NF-κB and thereby productions of proinflammatory cytokines, such as TNF-α, IL-1β, and IL-6. Importantly, the microarray analysis of AMPK-$\alpha 1^{KD}$ cells revealed a dramatic reduction in the NF-κB-dependent genes induced by TLR4 and TNF-α stimulation, and the observation was in significant correlation with the results of quantitative real-time PCR. Moreover, AMPK-$\alpha 1^{KD}$ cells are highly sensitive to the TNF-α-induced apoptosis, which is accompanied with dramatic reductions in the NF-κB-dependent and anti-apoptotic genes. As a result, our data demonstrate that AMPK-α1 as an activating kinase of TAK1 has a key role in mediating inflammatory signals triggered by TLR4 and TNF-α

Development of black ice prediction model using GIS-based multi-sensor model validation

Fog, freezing rain, and snow (melt) quickly condense on road surfaces, forming black ice that is difficult to identify and causes major accidents on highways. As a countermeasure to prevent icing car accidents, it is necessary to predict the amount and location of black ice. This study advanced previous models through machine learning and multi-sensor-verified results. Using spatial (hill shade, river system, bridge, and highway) and meteorological (air temperature, cloudiness, vapour pressure, wind speed, precipitation, snow cover, specific heat, latent heat, and solar radiation energy) data from the study area (Suncheon–Wanju Highway in Gurye-gun, Jeollanam-do, South Korea), the amount and location of black ice were modelled based on system dynamics to predict black ice and then simulated with a geographic information system in units of square metres. The intermediate factors calculated as input factors were road temperature and road moisture, modelled using a deep neural network (DNN) and numerical methods. Considering the results of the DNN, the root mean square error was improved by 148.6 % and reliability by 11.43 % compared to a previous study (linear regression). Based on the model results, multiple sensors were buried at four selected points in the study area. The model was compared with sensor data and verified with the upper-tailed test (with a significance level of 0.05) and fast Fourier transform (freezing does not occur when frequency = 0.00001 Hz). Results of the verified simulation can provide valuable data for government agencies like road traffic authorities to prevent traffic accidents caused by black ice

Flexible Near-Field Wireless Optoelectronics as Subdermal Implants for Broad Applications in Optogenetics

In vivo optogenetics provides unique, powerful capabilities in the dissection of neural circuits implicated in neuropsychiatric disorders. Conventional hardware for such studies, however, physically tethers the experimental animal to an external light source, limiting the range of possible experiments. Emerging wireless options offer important capabilities that avoid some of these limitations, but the current size, bulk, weight, and wireless area of coverage is often disadvantageous. Here, we present a simple but powerful setup based on wireless, near-field power transfer and miniaturized, thin, flexible optoelectronic implants, for complete optical control in a variety of behavioral paradigms. The devices combine subdermal magnetic coil antennas connected to microscale, injectable light-emitting diodes (LEDs), with the ability to operate at wavelengths ranging from UV to blue, green-yellow, and red. An external loop antenna allows robust, straightforward application in a multitude of behavioral apparatuses. The result is a readily mass-producible, user-friendly technology with broad potential for optogenetics applications.114419Ysciescopu

Effect of Purity and Substrate on Field Emission Properties of Multi-walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWNT) have been synthesized by chemical vapour decomposition (CVD) of acetylene over Rare Earth (RE) based AB2(DyNi2) alloy hydride catalyst. The as-grown carbon nanotubes were purified by acid and heat treatments and characterized using powder X-ray diffraction, Scanning Electron Microscopy, Transmission Electron Microscopy, Thermo Gravimetric Analysis and Raman Spectroscopy. Fully carbon based field emitters have been fabricated by spin coating a solutions of both as-grown and purified MWNT and dichloro ethane (DCE) over carbon paper with and without graphitized layer. The use of graphitized carbon paper as substrate opens several new possibilities for carbon nanotube (CNT) field emitters, as the presence of the graphitic layer provides strong adhesion between the nanotubes and carbon paper and reduces contact resistance. The field emission characteristics have been studied using an indigenously fabricated set up and the results are discussed. CNT field emitter prepared by spin coating of the purified MWNT–DCE solution over graphitized carbon paper shows excellent emission properties with a fairly stable emission current over a period of 4 h. Analysis of the field emission characteristics based on the Fowler–Nordheim (FN) theory reveals current saturation effects at high applied fields for all the samples