Laboratory Experiments on the Alteration of Highly-Compacted Bentonite by Alkaline Solution and the Effects on Physical Properties

2011 ◽  
Author(s):  
Satoru Miyoshi ◽  
Shinya Morikami ◽  
Yukinobu Kimura ◽  
Tomoko Jinno ◽  
Shuichi Yamamoto
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Solution ◽  
Sodium Hydroxide Solution ◽  
Mineral Dissolution ◽  
Alkali Solution ◽  
Exchangeable Cation ◽  
High Concentration ◽  
Compacted Bentonite ◽  
Aqueous Silicon ◽  
The Difference

The laboratory experiment was done that 1.0mol/L sodium hydroxide solution was injected to the compacted bentonite whose density is the same as the prospected value in the concept of the intermediate-level disposal in Japan in the circumstance of 70°C temperature. After the injection of the alkali solution for approximately 600 days, the bentonite was taken out of the apparatus and some sorts of analysis were done. The accompanying minerals in the bentonite, calcedony and quartz, were dissolved and disappeared in XRD charts. Then analcime was precipitated as a secondary mineral. Although montmorillonite was dissolved, the mass fraction of it was kept approximately. The hydraulic conductivity of the bentonite calculated using the flow rate at the end of the injection of alkali solution was smaller than the prospected value based on a widely-used empirical model of the hydraulic conductivity of compacted bentonite as a function of the equivalent concentration of pore solution, montmorillonite partial void ratio, and the ratio of sodium ion equivalent to the exchangeable cation equivalent. The reasons for the difference were supposed to be the decrease of pore size brought by mineral dissolution and the large viscosity of pore solution involving high concentration aqueous silicon.

Hydraulic conductivity variation in compacted bentonite-fly ash mixes under constant volume and free swelling flow conditions

2021 ◽  
Author(s):  
Chandra Bhanu Gupt ◽  
Sanandam Bordoloi ◽  
Metta Niranjan Bhatlu ◽  
Sreedeep Sekharan
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Constant Volume ◽  
Upper And Lower Bounds ◽  
Power Relationship ◽  
Compacted Bentonite ◽  
Free Swelling ◽  
Extended Duration ◽  
Class C ◽  
The Difference

Compacted bentonite-sand (B-S) and bentonite-fly ash (B-FA) are established combinations for the construction of landfill liners. This study determined the upper and lower bounds of equilibrium hydraulic conductivity (keq) of amended bentonite under extended duration of flow. The keq for constant volume flow condition differed from free swelling condition by more than two orders of magnitude due to the difference in geomaterial interaction, microstructural changes, and mineralization. Considering constant volume and free swelling condition, B-FA mix with class F and class C fulfilled the hydraulic conductivity criterion up to 70 % and 30 % amendment, respectively. The higher keq observed for the B mixed with class C FA was attributed to the formation of porous calcium aluminium silicate hydrate gel and ettringite needle type minerals. The time taken to achieve equilibrium was inversely related to keq by a power relationship. The data from this study were used to propose empirical relationships for estimating keq (long-term) based on k obtained at 48 hours (short-term), plasticity and geomaterial type. The study reveals that FA can be used as an alternate for S as amendment material and keq based on free swelling condition should be used for designing the liner.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

The centriolar complex isolated from starfish spermatozoa

1981 ◽  
Vol 49 (1) ◽  
pp. 33-49 ◽  
Author(s):  
R. Kuriyama ◽  
H. Kanatani
Keyword(s):  
Gradient Centrifugation ◽  
Sucrose Density Gradient ◽  
Microtubule Assembly ◽  
High Concentration ◽  
Microtubule Organization ◽  
Sucrose Density Gradient Centrifugation ◽  
The Difference ◽  
Distal Centriole

Centrioles from spermatozoa of the starfish, Asterina pectinifera, were isolated and partially purified by solubilization of chromatin followed by sucrose density-gradient centrifugation. The ultrastructure of the isolated centriolar complex was investigated in whole mount preparations by electron microscopy. The complex unit was composed of a pair of centrioles and a pericentriolar structure, which associated with the distal end of the distal centriole by 9 spoke-like satellites extending radially to a marginal ring. Each satellite bifurcated at a dense node forming 2 fan-like shapes with a periodic striated pattern. The tubular structure of the centrioles easily disintegrated, leaving the pericentriolar structure or axonemal microtubules intact. The distal centriole in a spermatozoon served as an initiating site for flagellar microtubule assembly; that is, a number of “9 + 2′ axonemal tubules were observed adhering just beneath the distal end of the basal body. In experiments in vitro, polymerization of microtubule proteins purified from porcine brain was initiated by the structure at the ends of both proximal and distal centrioles, but not from the satellites or the marginal ring. Also, few if any microtubules were formed from the sides of each centriole, even in the presence of a high concentration of exogenous tubulin. On the other hand, centrioles of spermatozoa, when they were in mature ooplasm, could initiate the formation of sperm asters by microtubules. Therefore, centrioles in spermatozoa seem to be able to initiate microtubules in a 2 ways. A possible explanation of the difference between the 2 types of microtubule organization in vivo, i.e. in the sperm cell itself and in the ooplasm, it discussed.

Influence of Temperature on Hydraulic Conductivity in Compacted Bentonite

1997 ◽  
Vol 506 ◽  
Author(s):  
W. J. Cho ◽  
J. O. Lee ◽  
K. S. Chun
Keyword(s):  
Hydraulic Conductivity ◽  
Influence Of Temperature ◽  
Temperature Range ◽  
Compacted Bentonite ◽  
Influence Of Temperature On ◽  
Water Saturated ◽  
Increasing Temperature ◽  
Good Agreement

ABSTRACTThe hydraulic conductivities in water saturated bentonites at different densities were measured within temperature range of 20 to 80 °C. The results show that the hydraulic conductivities increase with increasing temperature. The hydraulic conductivities of bentonites at the temperature of 80 °C increase up to about 3 times as high as those at 20 °C. The measured values are in good agreement with those predicted. The change in viscosity of water with temperature contributes greatly to increase of hydraulic conductivity.

scholarly journals Effects of Hydraulic Gradient and Clay Type on Permeability of Clay Mineral Materials

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1064
Author(s):  
Masanori Kohno
Keyword(s):  
Hydraulic Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Clay Mineral ◽  
Specific Surface Area ◽  
Hydraulic Gradient ◽  
Consistency Index ◽  
Hydrogen Energy ◽  
The Difference ◽  
Mineral Type

Considering the relevance of clay mineral-bearing geomaterials in landslide/mass movement hazard assessment, various engineering projects for resource development, and stability evaluation of underground space utilization, it is important to understand the permeability of these clay mineral-based geomaterials. However, only a few quantitative data have been reported to date regarding the effects of the clay mineral type and hydraulic gradient on the permeability of clay mineral materials. This study was conducted to investigate the permeability of clay mineral materials based on the clay mineral type, under different hydraulic gradient conditions, through a constant-pressure permeability test. Comparative tests have revealed that the difference in the types of clay mineral influences the swelling pressure and hydraulic conductivity. In addition, it has been found that the difference in water pressure (hydraulic gradient) affects the hydraulic conductivity of clay mineral materials. The hydraulic conductivity has been found to be closely associated with the specific surface area of the clay mineral material. Furthermore, the hydraulic conductivity value measured is almost consistent with the value calculated theoretically using the Kozeny–Carman equation. Moreover, the hydraulic conductivity is also found to be closely associated with the hydrogen energy, calculated from the consistency index of clay. This result suggests that the hydraulic conductivity of clay mineral materials can be estimated based on the specific surface area and void ratio, or consistency index of clay.

Photodosimeter Badge System

PEDIATRICS ◽  
1985 ◽  
Vol 75 (2) ◽  
pp. 437-441
Author(s):  
Peter C. Scheidt ◽  
Phyllis M. Sternthal ◽  
Robert Anderson ◽  
Robert Studholme ◽  
Dolores A. Bryla ◽  
...  
Keyword(s):  
Child Health ◽  
Human Development ◽  
Optical Density ◽  
Action Spectrum ◽  
Radiant Energy ◽  
National Academy Of Sciences ◽  
High Concentration ◽  
Film Badge ◽  
The Difference ◽  
Academy Of Sciences

The Committee on Phototherapy in the Newborn of the National Academy of Sciences has recommended10 development of a compact system to continuously measure radiant energy exposure of infants treated with phototherapy. A small bilirubinimpregnated photodosimeter film badge was developed by the Beckman Instrument Company for this purpose and was used during the National Institute of Child Health and Human Development (NICHD) phototherapy study. This report summarizes the results of data obtained with this measurement device and briefly describes the performance of this system. METHODS The film badge dosimeter system consists of a 5.2x2.6-cm plastic badge composed of an imbedded disk of bilirubin cast in a polymeric substrate and sandwiched between two layers of clear plastic. Before exposure to light, the badge exhibits a high optical density at 460 nm due to a relatively high concentration of bilirubin. The optical density of the badge at 400 to 500 nm decreases as a function of the total dose of light within the action spectrum for the photodecomposition of bilirubin to which the badge has been exposed. Initial optical density at 460 nm is measured by a densitometer designed and dedicated specifically for this purpose. After exposure, the optical density is again measured by insertion into the densitometer; the total dosage, which is the time-integrated irradiance received by the badge during the photodecomposition process, is derived from the difference in optical density between the two readings. (A description of the calibration of the badge is available on request from Biometry Branch, Epidemiology and Biometry Research Program, National Institute of Child Health and Human Development, Bethesda, Maryland.)

scholarly journals Occurrence and correlation between the numbers of Black-headed Gull Chroicocephalus ridibundus and Yellow-legged Gull Larus michahellis on Kolut fish ponds (Serbia)

2015 ◽  
Vol 84 (1) ◽  
pp. 37
Author(s):  
Marko Tucakov ◽  
Milan Vogrin
Keyword(s):  
Food Availability ◽  
Fish Ponds ◽  
Early Winter ◽  
High Food ◽  
High Concentration ◽  
Aquatic Animals ◽  
Autumn Period ◽  
Larus Michahellis ◽  
The Difference ◽  
Fish Harvest

Presence and correlation between the numbers of Black-headed and Yellow-legged Gull was studies between 1998 and 2004 on Kolut fishponds in NW Serbia. Both species occurred there from February to December. Spring migration culminated in late February and early March. The period of the most intensive autumn concentration was from October to December. The difference between the numbers in all months as well as between the numbers in spring and in autumn was statistically significant. The period of the most intensive autumn passage of Yellow-legged Gull was from late October to early December. The difference between the numbers between the months was not statistically significant. A high concentration of both species in autumn and early winter was explained by high food availability during fish harvest when ponds were empty. Positive correlation between the numbers of two species thru the year indicated attractiveness of large flocks of Black-headed Gulls for Yellow-legged Gulls. This is especially true for the autumn period, when feeding niches and food is easily accessible. Correlation between the numbers of two species was negative in spring, when accesibility of aquatic animals is lower and large flocks of Black-headed Gulls are lacking.

scholarly journals Bottom-up versus top-down factor investing: an alpha forecasting perspective

2020 ◽  
Author(s):  
Martin Zurek ◽  
Lars Heinrich
Keyword(s):  
Interaction Effects ◽  
Informational Content ◽  
Firm Characteristics ◽  
Recent Discussion ◽  
High Concentration ◽  
Top Down ◽  
Bottom Up ◽  
Factor Investing ◽  
Significant Performance ◽  
The Difference

AbstractIn a recent discussion about efficient ways to combine multiple firm characteristics into a multifactor portfolio, a distinction was made between the bottom-up and top-down approach. Both approaches integrate characteristics with equal weights and ignore interaction effects from differences in informational content and correlations between the firm characteristics. The authors complement the bottom-up approach for the missing interaction effects by implementing a linear alpha forecasting framework. Bottom-up versus top-down factor investing is typically discussed using the assumption that all characteristics are equally priced, but the pricing impact of different firm characteristics can vary tremendously. The alpha forecasting perspective provides a theoretical motivation for factor investing and helps to compare the bottom-up and top-down approach with regard to the difference of informational content and interaction effects between firm characteristics. Taking into account the difference in informational content between firm characteristics leads to significant performance improvement in factor models with a high concentration of informational content. Equally weighted characteristics result in related performance irrespective of whether the bottom-up or top-down approach is applied.

scholarly journals Comparison of three methods for rendering plant fat transesterification

2013 ◽  
Vol 59 (No. 2) ◽  
pp. 51-55
Author(s):  
A. Prošková ◽  
J. Kučera ◽  
Z. Kopicová ◽  
L. Škarková
Keyword(s):  
Fatty Acids ◽  
Free Acid ◽  
The Other ◽  
Alkaline Media ◽  
Optimum Temperature ◽  
Optimum Conditions ◽  
High Concentration ◽  
Reaction Velocity ◽  
Catalysed Reaction ◽  
The Difference

Three most frequently used methods for fat transesterification were compared using rendering plant fat (RPF) as model. Acid-catalysed transesterification was found to be the most effective (conversion 90%) at optimum conditions (fat: methanol ratio 1:10, sulphuric acid amount of 2% v/v, temperature 95°C). Base-catalysed transesterification of RPF on the other hand, results in much lower conversion (45%) at optimum conditions (fat:methanol ratio 1:20, NaOH amount 8% w/v, optimum temperature 95°C). The difference is done (among others) by the fact that RPF has high concentration of free acid (high acidity number) compared with the fats usually used for transesterification and that free acids are not esterified in alkaline media. Enzyme-(lipase) catalysed reaction could lead to partial esterification of free fatty acids, but with much lower reaction velocity. This fact leads to higher conversion in the case of enzyme-catalysed transesterification of RPF compared with base-catalysed reaction; nevertheless, even in this case the conversion is much lower in comparison with acid-catalysed reaction. The optimum conversion in enzyme-catalysed reaction was 55%.  

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