476 research outputs found
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Method of glass melter electrode length measurement using time domain reflectometry (TDR)
The present invention overcomes the drawbacks inherent in the prior art and solves the problems inherent in conventional Joule-heated vitrification melters, where the melter preferably comprises a vessel having a refractory liner and an opening for receiving material which is converted into molten vitreous material in the vessel. The vessel has an outlet port for removing molten vitreous material from the vessel. A plurality of electrodes is disposed in the vessel and electrical energy is passed between electrode pairs through feed material and molten vitreous material in the vessel. Typically, the electrodes erode and wear in time, and this invention seeks to monitor and evaluate the length and condition of the electrodes. The present invention uses time domain reflectometry (TDR) methods to accurately measure the length of an electrode that is subject to wear and electrolytic decomposition due to the extreme conditions in which the electrode is required to operate. Specifically, TDR would be used to measure the length and effects of erosion of molybdenum electrodes used in Joule-heated vitrification melter. Of course, the inventive concept should not be limited to this preferred environment
Fibroblastic polyp of the colon: clinicopathological analysis of 10 cases with emphasis on its common association with serrated crypts
: To describe the clinical and pathological features of 10 further cases of fibroblastic polyps (FP), a recently described, distinctive type of colorectal mucosal polyp. Methods and results : The patients were seven women and three men with ages ranging from 44 to 63 years. The lesions ranged in size from 2 to 4 mm. Eight of the polyps were located in the sigmoid colon. Five cases were associated with hyperplastic polyps. Histologically, FP displayed bland, plump spindle cells with oval nuclei arranged as bundles parallel to the surface or as haphazardly orientated sheets with a focal periglandular or perivascular concentric arrangement. Eight polyps represented mixed fibroblastic/hyperplastic polyps as they contained serrated (hyperplastic) crypts. Immunohistochemically, all cases were positive for vimentin and negative for desmin, smooth-muscle actin, h-caldesmon, S100 protein, c-Kit, epithelial membrane antigen, cytokeratin AE1/3, CD34, CD68, COX-2, and factor XIIIa. Ultrastructural examination supported the fibroblastic nature of the tumour cells. Conclusions : FP is a distinctive type of benign mucosal colorectal polyp characterized by its distal location, small size, frequent association with hyperplastic polyps, distinct morphological appearance and typical immunonegativity for markers of specific differentiation. FP with serrated crypts (mixed fibroblastic/hyperplastic polyp) represents a frequent variant of this lesion. Pathologists should recognize FP and discriminate it from other types of colorectal polyps.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72181/1/j.1365-2559.2006.02357.x.pd
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GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESS CELL WITH SLUDGE AND SUPERNATE SIMULANTS
Savannah River Remediation (SRR) is evaluating changes to its current Defense Waste Processing Facility (DWPF) flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the Chemical Process Cell (CPC) since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT&QAP). The details regarding the simulant preparation and analysis have been documented previously
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ISOPAR L RELEASE FROM SALTSTONE CURED AT 55 C
The decontaminated salt solution waste stream from the Modular Caustic Side Solvent Extraction Unit and the Salt Waste Processing Facility is anticipated to contain entrained extraction solvent. The decontaminated salt solution is scheduled to be processed through Tank 50 into the Saltstone Production Facility. This study, among others, has been undertaken because the solvent concentration in the decontaminated salt solution may cause flammability issues within the Saltstone Disposal Facility that may need to be addressed prior to operation. Previous work at the Savannah River National Laboratory determined the release of Isopar{reg_sign} L from saltstone prepared with a simulated DSS with Isopar{reg_sign} L concentrations ranging from 50 to 200 {micro}g/g in the salt fraction and with test temperatures ranging from ambient to 95 C. The results from the curing of the saltstone showed that the Isopar{reg_sign} L release data can be treated as a percentage of initial concentration in the concentration range studied. The majority of the Isopar{reg_sign} L that was released over the test duration was released in the first few days. The release of Isopar{reg_sign} L begins immediately and the rate of release decreases over time. At higher temperatures the immediate release is larger than at lower temperatures. In this study, saltstone was prepared using a simulated decontaminated salt solution containing Isopar{reg_sign} L concentrations of 50 {micro}L/L (30 {micro}g/g) and 100 {micro}L/L (61 {micro}g/g) and cured at 55 C. The headspace of each sample was purged and the Isopar{reg_sign} L was trapped on a coconut shell carbon tube. The amount of Isopar{reg_sign} L captured was determined using NIOSH Method 1501. The percentage of Isopar{reg_sign} L released after 20 days was 1.4 - 3.7% for saltstone containing 50 {micro}L/L concentration and 2.1 - 4.3% for saltstone containing 100 {micro}L/L concentration. Given the measurement uncertainties in this work there is no clearly discernible relationship between percentage release and initial Isopar{reg_sign} L concentration
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ISOPAR L RELEASE RATES FROM SALTSTONE USING SIMULATED SALT SOLUTIONS
The Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) and the Salt Waste Processing Facility (SWPF) will produce a Decontaminated Salt Solution (DSS) that will go to the Saltstone Production Facility (SPF). Recent information indicates that solvent entrainment in the DSS is larger than expected. The main concern is with Isopar{reg_sign} L, the diluent in the solvent mixture, and its flammability in the saltstone vault. If it is assumed that all the Isopar{reg_sign} L is released instantaneously into the vault from the curing grout before each subsequent pour, the Isopar{reg_sign} L in the vault headspace is well mixed, and each pour displaces an equivalent volume of headspace, the maximum concentration of Isopar{reg_sign} L in the DSS to assure 25% of the lower flammable limit is not exceeded has been determined to be about 4 ppm. The amount allowed would be higher if the release from grout were significantly less. The Savannah River National Laboratory was tasked with determining the release of Isopar{reg_sign} L from saltstone prepared with a simulated DSS with Isopar{reg_sign} L concentrations ranging from 50 to 200 mg/L in the salt fraction and with test temperatures ranging from ambient to 95 C. The results from the curing of the saltstone showed that the amount of Isopar{reg_sign} L released versus time can be treated as a percentage of initial amount present; there was no statistically significant dependence of the release rate on the initial concentration. The majority of the Isopar{reg_sign} L that was released over the test duration was released in the first few days. The release of Isopar{reg_sign} L begins immediately and the rate of release decreases over time. At higher temperatures the immediate release rate is larger than at lower temperatures. Initial curing temperature was found to be very important as slight variations during the first few hours or days had a significant effect on the amount of Isopar{reg_sign} L released. Short scoping tests at 95 C with solvent containing all components (Isopar{reg_sign} L, suppressor trioctylamine (TOA), and modifier Cs-7SB) except the BOBCalixC6 extractant released less Isopar{reg_sign} L than the tests run with Isopar{reg_sign} L/TOA. Based on these scoping tests, the Isopar{reg_sign} L releases reported herein are conservative. Isopar{reg_sign} L release was studied for a two-month period and average cumulative release rates were determined from three sets of tests each at 95 and 75 C and at ambient conditions. The overall average releases at were estimated for each temperature. For the 95 and 75 C data, at a 5% significance level, the hypothesis that the three test sets at each temperature had the same average percent release can be rejected, suggesting that there was a statistically significant difference among the three averages seen in the three experimental tests conducted. An upper confidence limit on the mean percent release required incorporation of variation from two sources: test-to-test variation as well as the variation within a test. An analysis of variance that relies on a random effects model was used to estimate the two variance components. The test-to-test variance and the within test (or residual) variance were both calculated. There is no indication of a statistically significant linear correlation between the percent Isopar{reg_sign} L release and the Isopar{reg_sign} L initial concentration. From the analysis of variance, upper confidence limits at confidences of 80-95% were calculated for the data at 95 and 75 C. The mean Isopar{reg_sign} L percent releases were 67.33% and 13.17% at 95 and 75 C, respectively
Structure–activity relationships of dinucleotides: Potent and selective agonists of P2Y receptors
Dinucleoside polyphosphates act as agonists on purinergic P2Y receptors to mediate a variety of cellular processes. Symmetrical, naturally occurring purine dinucleotides are found in most living cells and their actions are generally known. Unsymmetrical purine dinucleotides and all pyrimidine containing dinucleotides, however, are not as common and therefore their actions are not well understood. To carry out a thorough examination of the activities and specificities of these dinucleotides, a robust method of synthesis was developed to allow manipulation of either nucleoside of the dinucleotide as well as the phosphate chain lengths. Adenosine containing dinucleotides exhibit some level of activity on P2Y1 while uridine containing dinucleotides have some level of agonist response on P2Y2 and P2Y6. The length of the linking phosphate chain determines a different specificity; diphosphates are most accurately mimicked by dinucleoside triphosphates and triphosphates most resemble dinucleoside tetraphosphates. The pharmacological activities and relative metabolic stabilities of these dinucleotides are reported with their potential therapeutic applications being discussed
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Hanford Supplemental Treatment: Literature and Modeling Review of SRS HLW Salt Dissolution and Fractional Crystallization
In order to accelerate waste treatment and disposal of Hanford tank waste by 2028, the Department of Energy (DOE) and CH2M Hill Hanford Group (CHG), Inc. are evaluating alternative technologies which will be used in conjunction with the Waste Treatment Plant (WTP) to safely pretreat and immobilize the tank waste. Several technologies (Bulk Vitrification and Steam Reforming) are currently being evaluated for immobilizing the pretreated waste. Since the WTP does not have sufficient capacity to pretreat all the waste going to supplemental treatment by the 2028 milestone, two technologies (Selective Dissolution and Fractional Crystallization) are being considered for pretreatment of salt waste. The scope of this task was to: (1) evaluate the recent Savannah River Site (SRS) Tank 41 dissolution campaign and other literature to provide a more complete understanding of selective dissolution, (2) provide an update on the progress of salt dissolution and modeling activities at SRS, (3) investigate SRS experience and outside literature sources on industrial equipment and experimental results of previous fractional crystallization processes, and (4) evaluate recent Hanford AP104 boildown experiments and modeling results and recommend enhancements to the Environmental Simulation Program (ESP) to improve its predictive capabilities. This report provides a summary of this work and suggested recommendations
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