The Role of Surface Layers in Glass Leaching Performance

1990 ◽  
Vol 212 ◽  
Author(s):  
J. K. Bates ◽  
W. L. Ebert ◽  
J. J. Mazer ◽  
J. P. Bradley ◽  
C. R. Bradley ◽  
...  
Keyword(s):  
Surface Layers ◽  
Release Process ◽  
Long Time ◽  
Selective Incorporation ◽  
Radionuclide Release ◽  
Reaction Processes ◽  
Glass Leaching

ABSTRACTThe examination of reacted layers that form as glass reacts can provide insight into reaction mechanisms that control long-term glass reaction, and into processes by which radionuclides are released to solution. Examples are given for the natural glasses obsidian and tektite, and the nuclear waste glasses 131 and 165, where the layers form both in-situ and precipitated from solution, where they are both amorphous and crystal 1ine, where selective incorporation of actinide elements Into stable phases may offer a barrier to release, and where sloughing of the layers from the glass acts as an alternative radionuclide release process to solubility-limited control.Several reaction processes occur simultaneously as glass reacts, and the projection of glass performance to long time periods requires the identification of those processes that dominate the long-term reaction.

Investigations on the Role of Surface Layers in HLW Glass Leaching

1985 ◽  
Vol 50 ◽  
Author(s):  
R. Conradt ◽  
H. Roggendorf ◽  
H. Scholze
Keyword(s):  
Corrosion Test ◽  
Protective Effects ◽  
Reaction Products ◽  
Surface Layers ◽  
Hydrothermal Conditions ◽  
Glass Dissolution ◽  
Salt Brine ◽  
Glass Leaching

AbstractA corrosion test series was performed to clarify the role of reaction product layers on the corrosion of a simulated HLW borosilicate glass in a salt brine under hydrothermal conditions. The layers were unprotective at 200°C. At 120°C, slight protective effects ocurred when the leachant contained dissolved reaction products. The consequence for the long term behaviour between 120 and 200°C is a constant glass dissolution rate.

scholarly journals Potential forMethanosarcinato contribute to uranium reduction during acetate-promoted groundwater bioremediation

2017 ◽  
Author(s):  
Dawn E Holmes ◽  
Roberto Orelana ◽  
Ludovic Giloteaux ◽  
Li-Ying Wang ◽  
Pravin Shrestha ◽  
...  
Keyword(s):  
Field Experiment ◽  
Electron Donor ◽  
Enrichment Culture ◽  
Cell Suspensions ◽  
Contaminated Groundwater ◽  
Subunit A ◽  
Sedimentary Environments

AbstractPrevious studies ofin situbioremediation of uranium-contaminated groundwater with acetate injections have focused on the role ofGeobacterspecies in U(VI) reduction because of a lack of other abundant known U(VI)-reducing microorganisms. Monitoring the levels of methyl CoM reductase subunit A (mcrA) transcripts during an acetate-injection field experiment demonstrated that acetoclastic methanogens from the genusMethanosarcinawere enriched after 40 days of acetate amendment. The increased abundance ofMethanosarcinacorresponded with an accumulation of methane in the groundwater. An enrichment culture dominated by aMethanosarcinaspecies with the sameMethanosarcina mcrAsequence that predominated in the field experiment could effectively convert acetate to methane. In order to determine whetherMethanosarcinaspecies could be participating in U(VI) reduction in the subsurface, cell suspensions ofM. barkeriwere incubated in the presence of U(VI) with acetate provided as the electron donor. U(VI) was reduced by metabolically activeM. barkericells, however, no U(VI) reduction was observed in inactive controls. These results demonstrate thatMethanosarcinaspecies could play an important role in the long-term bioremediation of uranium-contaminated aquifers after depletion of Fe(III) oxides limits the growth ofGeobacterspecies. The results also suggest thatMethanosarcinahave the potential to influence uranium geochemistry in a diversity of anaerobic sedimentary environments.

Cardiac rehabilitation

2020 ◽  
pp. 371-384
Keyword(s):  
Coronary Heart Disease ◽  
Cardiac Rehabilitation ◽  
Cardiac Disease ◽  
Cardiac Event ◽  
Cardiovascular Prevention ◽  
Improvement Plan ◽  
National Service Framework ◽  
Long Time

This chapter looks at the role of cardiac rehabilitation for those at risk of cardiac disease or who have sustained a cardiac event. Cardiac rehabilitation has been a priority area for a long time in the National Service Framework for Coronary Heart Disease, NHS Improvement Plan, and now features in the NHS Long Term Plan. The introduction of certification for cardiovascular prevention and rehabilitation programmes (CPRP) has meant that their quality can be measured. The introduction of more technology-based interventions has opened up the opportunity for more people to participate, particularly for individuals who could not, or did not want to attend a traditional CPRP.

scholarly journals Ecoacoustics: A Quantitative Approach to Investigate the Ecological Role of Environmental Sounds

Mathematics ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 21 ◽  
Author(s):  
Almo Farina
Keyword(s):  
Full Range ◽  
Individual Species ◽  
Ecological Role ◽  
Dissimilarity Index ◽  
Detection And Identification ◽  
Quantitative Metrics ◽  
Ecological Complexity

Ecoacoustics is a recent ecological discipline focusing on the ecological role of sounds. Sounds from the geophysical, biological, and anthropic environment represent important cues used by animals to navigate, communicate, and transform unknown environments in well-known habitats. Sounds are utilized to evaluate relevant ecological parameters adopted as proxies for biodiversity, environmental health, and human wellbeing assessment due to the availability of autonomous audio recorders and of quantitative metrics. Ecoacoustics is an important ecological tool to establish an innovative biosemiotic narrative to ensure a strategic connection between nature and humanity, to help in-situ field and remote-sensing surveys, and to develop long-term monitoring programs. Acoustic entropy, acoustic richness, acoustic dissimilarity index, acoustic complexity indices (ACItf and ACIft and their evenness), normalized difference soundscape index, ecoacoustic event detection and identification routine, and their fractal structure are some of the most popular indices successfully applied in ecoacoustics. Ecoacoustics offers great opportunities to investigate ecological complexity across a full range of operational scales (from individual species to landscapes), but requires an implementation of its foundations and of quantitative metrics to ameliorate its competency on physical, biological, and anthropic sonic contexts.

Adaptation to calcium deprivation in the rat: effects of parathyroidectomy.

1977 ◽  
Vol 232 (3) ◽  
pp. E336
Author(s):  
J T Pento ◽  
L C Waite ◽  
P J Tracy ◽  
A D Kenny
Keyword(s):  
Adaptive Response ◽  
Calcium Transport ◽  
Parathyroid Tissue ◽  
Adaptation Period ◽  
Short Term ◽  
High Calcium

The role of parathyroid hormone (PTH) in the adaptive response in gut calcium transport to calcium deprivation has been studied in the rat using both the in vitro everted duodenal sac and the in situ ligated duodenal segment technique. Intact or parathyroidectomized (PTX) young rats were placed on a low calcium (0.01%) diet for 7-, 14-, or 21-day adaptation periods and compared with control rats maintained on a high calcium (1.5%) diet. Prior PTX (3 days before the start of the adaptation period) abolished the adaptive response (enhanced calcium transport) induced by calcium deprivation for a 7-day adaptation period, but did not abolish a response after a 21-day period. A 14-day adaptation period gave equivocal results. It is concluded that PTH appears to be necessary for short-term (7-day) adaptation, but not for long-term (21-day) adaptation to calcium deprivation. However, if accessory parathyroid tissue is present, the data could be interpreted differently: the essentiality of PTH for the adaptive response might be independent of the length of the adaptation period. The data also contribute to a possible resolution of the controversy concerning the involvement of PTH in the regulation of intestinal calcium transport in the rat.

Long-term maintenance capecitabine and celecoxib improved clinical outcomes by targeting colorectal cancer micrometastasis

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 14513-14513
Author(s):  
M. Zhang ◽  
S. Curley ◽  
C. Ng ◽  
B. Kurland ◽  
S. Krishnan ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Stage Iv ◽  
Complete Response ◽  
Kaplan Meier ◽  
Stage Iv Disease ◽  
Disease Site ◽  
Colorectal Cancer Patients

14513 Background: Role of mainteance therapy after achieving complete response (CR) remain undefined for patients with metasatic colorectal cancer. We studied prognostic and treatment factors including maintenance capecitabine and celecoxib (XCEL) in all 19 unresectable metastatic colorectal cancer patients (pts) who had CR from the prior XCEL study. Methods: Event charts are used to summarize the timeline of the various treatments. Kaplan-Meier survival estimates and univariate log-rank tests were used to evaluate RFS and OS as time from CR. Prognostic and treatment factors included: tumor size, metastasis number (9 solitary disease), site (13 being extrahepatic), stage on diagnosis (stage II versus III/IV), disease free interval prior to stage IV disease, surgery (5 R0, 3 R1–2 resections), lactate dehydrogenase levels, first-line irinotecan chemotherapy, radiation (9 pts ≥ 45 Gy, 3 Pts < 45 Gy), and maintenance XCEL (duration 0–50.3 months). Results: Nine of 19 patients experienced recurrence (median 13 months after CR), and 4 died during the follow-up period (median 31 months after CR). The 2-year RFS for the unresected and R1–2 resected patients was 71% versus 20% for the R0 resected patients (p = 0.07). This paradoxical RFS pattern corresponded to a RFS advantage for maintenance XCEL (p = 0.002), but not any other prognostic or treatment factors. All relapses occurred in situ following discontinuation of XCEL except for the surgical cases. Patients undergoing maintenance XCEL also benefited in OS (p = 0.04). The median OS from XCEL and from onset of metastasis reached 51.9 months (95% CI, 45 months- not reached [NR]) and 73.3 months (95% CI, NR-NR months) respectively. Conclusions: Maintenance XCEL targets colorectal micrometastases and produces a paradoxical RFS and OS advantage among the high-risk unresected/R1–2 resected patients than R0 resected patients. Prospective studies are warranted to validate roles of maintenance XCEL in the treatment of colorectal micrometastases. No significant financial relationships to disclose.

scholarly journals Aerosol decadal trends – Part 2: In-situ aerosol particle number concentrations at GAW and ACTRIS stations

2013 ◽  
Vol 13 (2) ◽  
pp. 895-916 ◽  
Author(s):  
A. Asmi ◽  
M. Collaud Coen ◽  
J. A. Ogren ◽  
E. Andrews ◽  
P. Sheridan ◽  
...  
Keyword(s):  
Time Series ◽  
Aerosol Particle ◽  
Particle Number ◽  
Cloud Condensation Nuclei ◽  
Temperature Changes ◽  
Long Time ◽  
Modelling Studies ◽  
Infrastructure Project

Abstract. We have analysed the trends of total aerosol particle number concentrations (N) measured at long-term measurement stations involved either in the Global Atmosphere Watch (GAW) and/or EU infrastructure project ACTRIS. The sites are located in Europe, North America, Antarctica, and on Pacific Ocean islands. The majority of the sites showed clear decreasing trends both in the full-length time series, and in the intra-site comparison period of 2001–2010, especially during the winter months. Several potential driving processes for the observed trends were studied, and even though there are some similarities between N trends and air temperature changes, the most likely cause of many northern hemisphere trends was found to be decreases in the anthropogenic emissions of primary particles, SO2 or some co-emitted species. We could not find a consistent agreement between the trends of N and particle optical properties in the few stations with long time series of all of these properties. The trends of N and the proxies for cloud condensation nuclei (CCN) were generally consistent in the few European stations where the measurements were available. This work provides a useful comparison analysis for modelling studies of trends in aerosol number concentrations.

scholarly journals The Corinth Rift Laboratory or an in situ Investigation on Interactions between Fluids and Active Faults

2007 ◽  
Vol SpecialIssue ◽  
pp. 35-38 ◽  
Author(s):  
F. H. Cornet
Keyword(s):  
Fluid Flow ◽  
Deformation Process ◽  
Active Faults ◽  
Localization Of Deformation

Earthquakes result from the sudden acceleration of a preliminary long-term slow deformation process. The objective of the Corinth Rift Laboratory (CRL) is to investigate <i>in situ</i> this quasistatic deformation process and mechanisms leading to a sudden catastrophic acceleration. Of particular interest is the characterization of the structure of the deforming zones and of the progressive localization of deformation. Special attention is given to the role of fluids but also on the influence of faults on regional fluid flow <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.s01.20.2007" target="_blank">10.2204/iodp.sd.s01.20.2007</a>

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