Solubility Modelling of Cements: Implications for Radioactive Waste Immobilisation.

1986 ◽  
Vol 84 ◽  
Author(s):  
F.P. Glasser ◽  
D.E. Macphee ◽  
E.E. Lachowski
Keyword(s):  
Calcium Silicate Hydrate ◽  
Composition Range ◽  
Solid Phase ◽  
Chemical Properties ◽  
Free Energies ◽  
Short Term ◽  
Solubility Products ◽  
Compositional Properties ◽  
Cementitious Systems

AbstractThe suitability of cement matrices for the long-term immobilisation of radionuclides cannot be predicted from short-term experimental data alone, because the chemical properties of cementitious systems change continuously over the repository lifetime. To model such changes is complex, so a stepwise approach has been adopted. A chemically simplified model for the solubility and compositional properties of calcium silicate hydrate gels in the system CaO-SiO2 -H20 was previously developed but has now been extended and improved and is applicable to gels in the wider composition range 0.8 < Ca/Si < 1.7. The effects of silicate speciation in aqueous solution on the formation of the solid phase have been more fully considered and the dissolution equilibrium has been revised. Solubility products and free energies of C-S-H formation have been evaluated and predictive applications of the model are discussed.

scholarly journals High-temperature short-term and long hardness of sintered compact and porous titanium-siliceous carbide ti3sic2

2004 ◽  
Vol 36 (1) ◽  
pp. 11-20 ◽  
Author(s):  
S.A. Firstov ◽  
E.P. Pechkovsky
Keyword(s):  
High Temperature ◽  
Ternary Compound ◽  
Solid Phase ◽  
Porous Titanium ◽  
Critical Values ◽  
Holding Time ◽  
Short Term ◽  
Sintered Compact ◽  
Temperature Range

The ternary compound of titanium-siliceous carbide Ti3SiC2, one of the representatives of Nan laminates, prepared by solid-phase sintering is investigated in compact and porous (q=0.03-0.41) states. Features of its short-term and long-term hardness (?=10 N) behavior in the temperature range from 20 to 1200?? at a holding time of 1-60 min were studied. It is shown that a temperature of about 700?? and holding time under load of about 10 min are critical values of the indentation procedure that correspond to an intensive decrease of hardness. The presence of porosity results in a decrease in hardness. a deformation scheme of compact and porous titanium-siliceous carbide Ti3SiC2 in the temperature range from 20 to 1200?? is proposed. .

scholarly journals Platinum Group Elements in Geosphere and Anthroposphere: Interplay among the Global Reserves, Urban Ores, Markets and Circular Economy

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 558 ◽  
Author(s):  
Juris Burlakovs ◽  
Zane Vincevica-Gaile ◽  
Maris Krievans ◽  
Yahya Jani ◽  
Mika Horttanainen ◽  
...  
Keyword(s):  
Waste Management ◽  
Chemical Properties ◽  
Platinum Group Elements ◽  
Global Market ◽  
Commodity Markets ◽  
Short Term ◽  
Specific Chemical ◽  
Recycling Potential ◽  
Platinum Group

Industrial and strategic significance of platinum group elements (PGEs)—Os, Ir, Ru, Rh, Pd, Pt—makes them irreplaceable; furthermore, some PGEs are used by investors as “safe heaven” assets traded in the commodity markets. This review analyzes PGEs from various aspects: their place in the geosphere, destiny in the anthroposphere, and opportunity in the economy considering interactions among the exploration, recycling of urban ores, trade markets, speculative rhetoric, and changes required for successful technological progress towards the implementation of sustainability. The global market of PGEs is driven by several concerns: costs for extraction/recycling; logistics; the demand of industries; policies of waste management. Diversity of application and specific chemical properties, as well as improper waste management, make the recycling of PGEs complicated. The processing approach depends on composition and the amount of available waste material, and so therefore urban ores are a significant source of PGEs, especially when the supply of elements is limited by geopolitical or market tensions. Recycling potential of urban ores is particularly important in a long-term view disregarding short-term economic fluctuations, and it should influence investment flows in the advancement of innovation.

scholarly journals Effects of dietary fat and carbohydrate on appetite vary depending upon site and structure

2004 ◽  
Vol 92 (S1) ◽  
pp. S23-S26 ◽  
Author(s):  
Stephen French
Keyword(s):  
Body Weight ◽  
Food Intake ◽  
Dietary Fat ◽  
Chemical Properties ◽  
Present Review ◽  
Dietary Composition ◽  
Levels Of Processing ◽  
Short Term ◽  
Physico Chemical

The present review summarises the effects of different carbohydrate and fat structures on food intake and appetite and the differences in response at various levels of processing of macronutrients. Several physico-chemical properties of carbohydrate and fat molecules appear to influence the short-term satiating properties. However, long-term substantiation of these findings expressed in terms of food intake or body weight is not currently available. Such studies will be required to make clear recommendations regarding dietary composition to aid satiety.

Pharmaceuticals and health care products in wastewater effluents: the example of carbamazepine

2003 ◽  
Vol 3 (4) ◽  
pp. 131-137 ◽  
Author(s):  
K. Stamatelatou ◽  
C. Frouda ◽  
M.S. Fountoulakis ◽  
P. Drillia ◽  
M. Kornaros ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Consumption Rate ◽  
Solid Phase ◽  
Organic Content ◽  
Operating Conditions ◽  
Anaerobic Sludge ◽  
Aquatic Environments ◽  
Short Term ◽  
Xenobiotic Compound

Persistence and impact of pharmaceutics in the environment are discussed. The case of carbamazepine (CBZ), a widely used antiepileptic drug detected in rivers, lakes, sludges and even in ground water is examined. CBZ fate was investigated in all possible routes that may follow after it has been discharged to the sewage system: activated sludge, anaerobic digestion sludge, seawater, fresh water and soil. Carbamazepine slowed down, i.e. caused a decrease in the COD consumption rate in the activated sludge process, especially after longer term exposure, while the anaerobic sludge process was unaffected in the operating conditions that were applied. The compound was not degraded under either short term or long term exposure to either aerobic or anaerobic degradation processes. Carbamazepine seemed to biosorb to solid phases (soil, sludge) and this strength of sorption was related to the organic content of the solid phase. These results explain why CBZ is a very persistent xenobiotic compound, as is apparent from its detection in appreciable amounts in various aquatic environments.

scholarly journals Short- and Long-Term Effects of Lime and Gypsum Applications on Acid Soils in a Water-Limited Environment: 2. Soil Chemical Properties

Agronomy ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1987
Author(s):  
Geoffrey C. Anderson ◽  
Shahab Pathan ◽  
James Easton ◽  
David J. M. Hall ◽  
Rajesh Sharma
Keyword(s):  
Soil Ph ◽  
Crop Production ◽  
Soil Layer ◽  
Chemical Properties ◽  
Al Toxicity ◽  
Long Term Effects ◽  
Medium Term ◽  
Short Term ◽  
The Impact

Soil acidity or aluminum (Al) toxicity is a major limitation to crop production. In this paper, we examine the effects of surface-applied lime and gypsum on soil profile chemical properties that affect Al toxicity in short-term (1 year), medium-term (2 years and 8 months) and long-term (10 years) experiments. Sulfate applied to the soil surface as gypsum was leached rapidly to a depth of 40 cm in the short-term despite relatively low amounts (279 mm) of rainfall. In the medium and long-term experiments, 28–54% of the sulfate applied as gypsum was retained in the 0–50 cm soil layer due to adsorption and precipitation reactions. The combined application of lime and gypsum increased soil calcium, to a depth of 30 cm in the short-term and to a depth of 50 cm in the medium and long-terms. Increases in soil sulfate and calcium were associated with greater electrical conductivity to a depth of 50 cm for all sampling times. Application of lime alone had no impact on soil Al, pH, and calcium in the soil layers below 10 cm in the short and medium terms. In the long-term, increasing the rate of lime application from 2 to 8 t L ha−1 increased soil pH in the 10–20 cm soil layer while soil Al decreased to a depth of 30 cm. The combined use of lime and gypsum decreased soil Al in the 30–50 cm soil layer in the medium-term and the 20–30 cm soil layer in the long-term which was more than when only lime was applied. Hence, we recommend the use of lime plus gypsum for treating soils with subsoil Al toxicity. Additionally, soil Al measurements are a more sensitive measurement of the impact of surface application lime and lime plus gypsum than soil pH.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

2020 ◽  
Vol 29 (4) ◽  
pp. 710-727
Author(s):  
Beula M. Magimairaj ◽  
Naveen K. Nagaraj ◽  
Alexander V. Sergeev ◽  
Natalie J. Benafield
Keyword(s):  
Auditory Processing ◽  
Short Term Memory ◽  
Group Differences ◽  
Long Term Memory ◽  
Short Term ◽  
Significant Group ◽  
Term Memory ◽  
Memory And Attention ◽  
Speed And Accuracy

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607

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