Disposal of radioactive waste into clay layers the most natural option

International Nuclear Information System (INIS)

Baetsle, L.H.; Bonne, A.

1990-01-01

Among the geological formations suitable for the disposal of radioactive waste, the clay formations provide outstanding opportunities : impermeable for water, self-healing, strongly absorbing for ions, widespread in nature. The self-healing properties of large clay deposits have been demonstrated by their auto-sealing and plastic response to tectonic stress and magmatic intrusion. The discovery of fossil trees preserved after geologic periods of burial in clay is one of the most dramatic illustrations of their entombment ability. The physicochemical and hydrologic characteristics of the Boom clay are very favorable for the confinement of migrating radionuclides within the layer. Except for the extremely long half-lives ( 237 Np, 129 I,...) no radionuclide can escape from the clay body. The effects of heat, metal corrosion, material interaction and biochemical degradation on the natural properties of the clay layer are discussed in some detail and related to the natural properties of the clay formation which have to stay unaltered for geologic periods. The first Safety Assessment Report, established by NIRAS-ONDRAF in close collaboration with SCK-CEN, has been submitted to a multi-disciplinary task force which is to advise the Belgian Government on the suitability of the Boom clay layer below the Nuclear Research site of Mol as a potential host formation for nuclear waste coming from the electronuclear program. 13 refs., 2 figs., 1 tab

Distribution of Fig Mosaic in Jordan

OpenAIRE

Khalil I. Al-Mughrabi; Ghandi H. Anfoka

2000-01-01

Fig mosaic (FM) is one of the most important diseases of figs in Jordan. A nationwide survey was conducted to determine the incidence and severity of this disease in trees and in seedlings propagated by cuttings in orchards and nurseries in 13 provinces and cities all over the country. Cultivars surveyed included Khdari, Mwazi, Zraki, Khartamani, Dafoori, Turki, Hamari, Esaili, Ajlouni, in addition to an Italian and a French cultivar. Disease severity varied from moderately severe...

Land use history and population dynamics of free-standing figs in a maturing forest.

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Larissa Albrecht

Full Text Available Figs (Ficus sp. are often considered as keystone resources which strongly influence tropical forest ecosystems. We used long-term tree-census data to track the population dynamics of two abundant free-standing fig species, Ficus insipida and F. yoponensis, on Barro Colorado Island (BCI, a 15.6-km2 island in Lake Gatún, Panama. Vegetation cover on BCI consists of a mosaic of old growth (>400 years and maturing (about 90-150 year old secondary rainforest. Locations and conditions of fig trees have been mapped and monitored on BCI for more than 35 years (1973-2011, with a focus on the Lutz Catchment area (25 ha. The original distribution of the fig trees shortly after the construction of the Panama Canal was derived from an aerial photograph from 1927 and was compared with previous land use and forest status. The distribution of both fig species (~850 trees is restricted to secondary forest. Of the original 119 trees observed in Lutz Catchment in 1973, >70% of F. insipida and >90% of F. yoponensis had died by 2011. Observations in other areas on BCI support the trend of declining free-standing figs. We interpret the decline of these figs on BCI as a natural process within a maturing tropical lowland forest. Senescence of the fig trees appears to have been accelerated by severe droughts such as the strong El Niño event in the year 1982/83. Because figs form such an important food resource for frugivores, this shift in resource availability is likely to have cascading effects on frugivore populations.

Partial avoidance of female inflorescences of a dioecious fig by their mutualistic pollinating wasps

Science.gov (United States)

Anstett, M. C.; Gibernau, M.; Hossaert-McKey, M.

1998-01-01

Every dioecious species of fig is pollinated by a specific wasp that only reproduces within the inflorescences of male trees. Pollinators usually die within the closed urn-shaped inflorescence (fig or syconium) they visit. Thus pollinators that enter female syconia allow seed production but die without reproducing. In a previous study, pollinators of one dioecious fig where male and female trees flower synchronously, Ficus hispida, did not exhibit differential attraction or choice between inflorescences of the two sexes. Here we show that Blastophaga psenes, the pollinator of another dioecious species of different lineage, the common fig (F. carica), significantly avoided female syconia, when we experimentally induce a situation of choice. Paradoxically, choosiness can be demonstrated in F. carica where usually wasps do not face a choice because male and female trees do not flower synchronously. We discuss how the mutualism may be stable despite this discrimination and hypothesize why the two species of fig-pollinators exhibit different behaviour on dioecious figs.

Tracking the elusive history of diversification in plant-herbivorous insect-parasitoid food webs: insights from figs and fig wasps.

Science.gov (United States)

Kjellberg, Finn; Proffit, Magali

2016-02-01

The food webs consisting of plants, herbivorous insects and their insect parasitoids are a major component of terrestrial biodiversity. They play a central role in the functioning of all terrestrial ecosystems, and the number of species involved is mind-blowing (Nyman et al. 2015). Nevertheless, our understanding of the evolutionary and ecological determinants of their diversity is still in its infancy. In this issue of Molecular Ecology, Sutton et al. (2016) open a window into the comparative analysis of spatial genetic structuring in a set of comparable multitrophic models, involving highly species-specific interactions: figs and fig wasps. This is the first study to compare genetic structure using population genetics tools in a fig-pollinating wasp (Pleistodontes imperialis sp1) and its main parasitoid (Sycoscapter sp.A). The fig-pollinating wasp has a discontinuous spatial distribution that correlates with genetic differentiation, while the parasitoid bridges the discontinuity by parasitizing other pollinator species on the same host fig tree and presents basically no spatial genetic structure. The full implications of these results for our general understanding of plant-herbivorous insect-insect parasitoids diversification become apparent when envisioned within the framework of recent advances in fig and fig wasp biology. © 2016 John Wiley & Sons Ltd.

PHENOLOGY AND YIELD OF THE ‘ROXO DE VALINHOS’ FIG CULTIVAR IN WESTERN POTIGUAR

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FRANCISCO SIDENE OLIVEIRA SILVA

2017-01-01

Full Text Available The ‘Roxo de Valinhos’ fig is one of the most widely grown varieties in the world, however, there are still few studies on the phenology and yield of fig trees, especially in semi-arid regions. This study evaluated the phenology and yield aspects of the ‘Roxo de Valinhos’ fig cultivar in Western Potiguar. The experiment was carried out from July to December 2015 in the didactic orchard of the Federal Rural University of the Semi-Arid, UFERSA. The following phenological aspects were analyzed: pruning at the beginning of budding, emergence and maturity of the first fruit, beginning of harvest, length and diameter of branches, number of fruits per branch, length and diameter of fruits, absolute growth rate, yield per plant, number of fruits per plant, and fruit weight. We used descriptive statistics; for quantitative and qualitative characteristics, we used regression analysis and means test, through Tukey´s test at 5% probability. Fig trees showed good adaptability to semi-arid regions and precocity when compared to fig trees from temperate regions, in all phenological stages; the studied cultivar showed promising results for cultivation in this region.

Woody plant roots fail to penetrate a clay-lined landfill: Managment implications

Science.gov (United States)

Robinson, George R.; Handel, Steven N.

1995-01-01

In many locations, regulatory agencies do not permit tree planting above landfills that are sealed with a capping clay, because roots might penetrate the clay barrier and expose landfill contents to leaching. We find, however, no empirical or theoretical basis for this restriction, and instead hypothesize that plant roots of any kind are incapable of penetrating the dense clays used to seal landfills. As a test, we excavated 30 trees and shrubs, of 12 species, growing over a clay-lined municipal sanitary landfill on Staten Island, New York. The landfill had been closed for seven years, and featured a very shallow (10 to 30-cm) soil layer over a 45-cm layer of compacted grey marl (Woodbury series) clay. The test plants had invaded naturally from nearby forests. All plants examined—including trees as tall as 6 m—had extremely shallow root plates, with deformed tap roots that grew entirely above and parallel to the clay layer. Only occasional stubby feeder roots were found in the top 1 cm of clay, and in clay cracks at depths to 6 cm, indicating that the primary impediment to root growth was physical, although both clay and the overlying soil were highly acidic. These results, if confirmed by experimental research should lead to increased options for the end use of many closed sanitary landfills.

Moving your sons to safety: galls containing male fig wasps expand into the centre of figs, away from enemies.

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Hui Yu

Full Text Available Figs are the inflorescences of fig trees (Ficus spp., Moraceae. They are shaped like a hollow ball, lined on their inner surface by numerous tiny female flowers. Pollination is carried out by host-specific fig wasps (Agaonidae. Female pollinators enter the figs through a narrow entrance gate and once inside can walk around on a platform generated by the stigmas of the flowers. They lay their eggs into the ovules, via the stigmas and styles, and also gall the flowers, causing the ovules to expand and their pedicels to elongate. A single pollinator larva develops in each galled ovule. Numerous species of non-pollinating fig wasps (NPFW, belonging to other families of Chalcidoidea also make use of galled ovules in the figs. Some initiate galls, others make use of pollinator-generated galls, killing pollinator larvae. Most NPFW oviposit from the outside of figs, making peripherally-located pollinator larvae more prone to attack. Style length variation is high among monoecious Ficus spp. and pollinators mainly oviposit into more centrally-located ovules, with shorter styles. Style length variation is lower in male (wasp-producing figs of dioecious Ficus spp., making ovules equally vulnerable to attack by NPFW at the time that pollinators oviposit. We recorded the spatial distributions of galled ovules in mature male figs of the dioecious Ficus hirta in Southern China. The galls contained pollinators and three NPFW that kill them. Pollinators were concentrated in galls located towards the centre of the figs, NPFW towards the periphery. Due to greater pedicel elongation by male galls, male pollinators became located in more central galls than their females, and so were less likely to be attacked. This helps ensure that sufficient males survive, despite strongly female-biased sex ratios, and may be a consequence of the pollinator females laying mostly male eggs at the start of oviposition sequences.

Four viruses infecting figs in Western Saudi Arabia

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Amal Y. ALDHEBIANI

2015-12-01

Full Text Available Many diseases are compromising fig production in Saudi Arabia and in particular those caused by viruses. RT-PCR assays were conducted on 80 samples collected from four fig-growing provinces in the West Mecca region of Saudi Arabia, including the Fatima, Khulais, Rabigh and Alshifa valleys. Samples consisted of leaf tissues taken from caprifig and common fig trees. The presence of Fig mosaic virus (FMV, Fig leaf mottle-associated virus 1 (FLMaV-1, Fig leaf mottle-associated virus 2 (FLMaV-2 and Fig mild mottle-associated virus (FMMaV was assessed from the samples. RT-PCR results showed that all four viruses were present in the surveyed areas with different proportions of infection. Incidence was 69% of samples, with a peak of 80%, from the Alshifa and Fatima valleys, 60% from Rabigh and 55% from Khulais valley. FLMaV-1 was the prevailing virus (55% of samples, followed by FMV (34%, whereas FLMaV-2 (11% of samples and FMMaV (6% were less common. Most of the mosaic symptoms observed in surveyed fig orchards occurred with the presence of FMV. However, many other symptoms remained unexplained because of the arduous task of determining the involvement of other fig-infecting viruses with mosaic disease. This is the first report of FMMaV and FLMaV-2 in Saudi Arabia, and of FMV and FLMaV-1 in western Saudi Arabia. The virus status of this crop is probably compromised and a sanitation programme is required to produce healthy plant material in Saudi Arabia.

Figs Are More Than Fallback Foods: The Relationship between Ficus and Cebus in a Tropical Dry Forest

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Nigel A. Parr

2011-01-01

Full Text Available In many studies on primate feeding ecology, figs (Ficus spp. are characterized as fallback foods, utilized only when preferred sources of food are unavailable. However, for white-faced capuchin monkeys (Cebus capucinus living in northwestern Costa Rica, figs are a consistently important resource and may increase groupwide energy intake. We investigated whether visits to figs affect ranging and behavioural patterns of capuchins. Although daily range length and average travel speed do not differ on days when fig trees are visited, capuchins spend more time in directed travel and more time stationary on “fig days”. Capuchins also increase time spent foraging for fruit and decrease time spent foraging for invertebrates on days when figs trees are visited. Capuchins experience higher energy intake and lower energy output on “fig” days. Thus, the patterns of foraging for figs support an energy-maximization strategy and constitute an important nutritional resource for capuchins.

Sorption of radionuclides by tertiary clays

International Nuclear Information System (INIS)

Wagner, J.F.; Czurda, K.A.

1990-01-01

The sorption capacity of different clay types for some metals (Co, Cs, Sr and Zn), occurring as common radionuclides in radioactive waste deposits, had been analysed by a static (batch technique) and a dynamic method (percolation tests, in which the driving force is a hydraulic gradient). Sorption capacity generally increased with an increasing pH of solution. A decrease of sorption capacity had been observed in the order Zn > Cs ≥ Co > Sr for the batch and Cs > Zn > Sr > Co for the percolation tests. Clay marls showed a distinctly higher sorption respectively retention capacity as pure clays. Sorption capacity depends on solution parameters like type and concentration of radionuclide, pH, salt concentration, etc., and on rock parameters like mineral content (e.g. swelling clay minerals and carbonates), organic material, rock pH, micro fabric, etc. A third parameter of great influence is the contact time between clay and solution. The adsorption isotherms reflect two different adsorption mechanisms: a very rapid adsorption (a few minutes) on the external surfaces of clay minerals and a slow adsorption process (weeks and longer), due to the diffusion of metal ions into the interlayer space of clay minerals. 12 refs., 9 figs., 1 tab

Acclimatization and leaf anatomy of micropropagated fig plantlets

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Chrystiane Fráguas Chirinéa

2012-12-01

Full Text Available The survival of micropropagated plants during and after acclimatization is a limiting process to plant establishment. There is little information on how the anatomy of vegetative organs of Ficus carica can be affected by culture conditions and acclimatization. The present research aimed to study the effects of time on culture medium and substrates during the acclimatization of fig tree plantlets produced in vitro, characterizing some leaf anatomy aspects of plantlets cultured in vitro and of fig trees produced in field. Plantlets previously multiplied in vitro were separated and transferred into Wood Plant Medium (WPM where they were kept for 0, 15, 30, 45 and 60 days. Different substrates were tested and studies on leaf anatomy were performed in order to compare among plantlets grown in vitro, plantlets under 20, 40 and 60 days of acclimatization, and field grown plants. Keeping plantlets for 30 days in WPM allowed better development in Plantmax during acclimatization. Field grown plants presented higher number of stomata, greater epicuticular wax thickness and greater leaf tissue production compared to in vitro ones. The leaf tissues of in vitro plantlets show little differentiation and have great stomata number compared with acclimatized plants, which reduce the number of stomata during the acclimatization process.

Backfilling with mixtures of bentonite/ballast materials or natural smectitic clay?

Energy Technology Data Exchange (ETDEWEB)

Pusch, R. [Geodevelopment AB, (Sweden)

1998-10-01

Comparison of the performance of backfills of mixed MX-80 and crushed rock ballast, and a natural smectitic clay, represented by the German Friedland clay, shows that the latter performs better than mixtures with up to 30 % MX-80. Considering cost, Friedland clay prepared to yield air-dry powder grains is cheaper than mixtures of 30 % MX-80 and crushed ballast. Both technically and economically it appears that the Friedland clay is a competitive alternative to mixtures of 30 % MX-80 and crushed ballast. However, it remains to be demonstrated on a full scale that Friedland clay ground to a suitable grain size distribution can be acceptably compacted on site 14 refs, 32 figs, 6 tabs

Diffusion, sorption and stability of radionuclide-organic complexes in clays and clay-organic complexes

International Nuclear Information System (INIS)

Staunton, S.; Rees, L.V.C.

1991-01-01

The dependence on various parameters of the diffusion coefficient of neptunium (V) in clay systems has been studied. The effect of the clay mineralogy, the charge compensating cation in the clay, the ionic strength of a background perchlorate solution and the presence of three organic ligands have been investigated. The diffusion coefficients were compared to those predicted if diffusion occurred only in the liquid phase and adsorption was reversible; agreement was fairly good. An approximation to the diffusion coefficient can thus be obtained from readily measured experimental parameters. There is no evidence of surface phase diffusion. The most significant factor in determining the diffusion coefficient is the magnitude of the distribution ratio, itself highly dependent on the nature of the clay. Neither EDTA nor citrate modified the diffusion coefficient. Although the presence of 1 or 100 mg dm -3 of Aldrich humic acid had little effect on the distribution ratio of neptunium, it caused a lowering of the measured diffusion coefficient. This is interpreted in terms of the limiting liquid phase diffusion coefficient and the true liquid phase impedance factor of neptunium-humic acid complexes. 21 figs; 3 tabs; 20 refs

Ficus religiosa L. (English: Peepal tree or sacred fig; Hindi: Pippal ...

Indian Academy of Sciences (India)

Fruits are fig-like, globose, small and purplish when ripe. The bark is astringent, sweet, aphrodisiac and the aqueous extract of it is antibacterial. Leaves and tender shoots are recommended for wounds and skin diseases. Pulverised dried fruit taken in water cures asthma. The latex is good for neuralgia, inflammations and ...

Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (Volume 1)

International Nuclear Information System (INIS)

Baldi, G.; Hueckel, T.; Peano, A.; Pellegrini, R.

1991-01-01

The results of two years of research on thermomechanics of clays performed within CEC contract Fl1W/0150 are described herein. Previous studies (research contracts with CEC/WAS/380.83.7 l) performed by ISMES have evidenced the need for an improved modelling of the volumetric response of natural clays. In a coupled approach, this leads to an improved prediction of pore-pressure development and dissipation. This is crucial for assessing conditions of a possible local thermal failure as verified in laboratory tests done at ISMES. The first part of the study lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton. It consists in: (a) developing a framework for inclusion of water/soil particle thermally induced interaction into a thermodynamically consistent mixture theory approach (Section 2); (b) studying possible modelling approaches of considering the effective thermal expansion coefficient of pore water dependency on pore water status (Section 2); (c) testing artificial clays to assess pore water thermal expansion dependence on temperature in the presence of different amounts of active clay minerals and also Boom clay (Section 3); (d) performing a laboratory test campaign on Boom clay with special attention to the response in the overconsolidated domain (Section 4). 89 figs., 18 tabs., 102 refs

Some pollinators are more equal than others: Factors influencing pollen loads and seed set capacity of two actively and passively pollinating fig wasps

Science.gov (United States)

Kjellberg, Finn; Suleman, Nazia; Raja, Shazia; Tayou, Abelouahad; Hossaert-McKey, Martine; Compton, Stephen G.

2014-05-01

The nursery pollination system of fig trees (Ficus) results in the plants providing resources for pollinator fig wasp larvae as part of their male reproductive investment, with selection determining relative investment into pollinating wasps and the pollen they carry. The small size of Ficus pollen suggests that the quantities of pollen transported by individual wasps often limits male reproductive success. We assessed variation in fig wasp pollen loads and its influence on seed production in actively pollinated (Ficus montana) and passively pollinated (Ficus carica) dioecious fig trees.

Clay minerals in sandstone uranium deposits: radwaste applications

International Nuclear Information System (INIS)

Brookins, D.G.

1990-01-01

Clay minerals play an important role in the genesis of uranium deposits in sandstones. They incorporate the rate earths (REE), U, Sb, Th, Cs, Rb, Sr, Y, Ba, and even small amounts of chalcophiles. These minerals possess analog elements for many of the radwaste fission products as well as actinides and some actinide daughters. In sandstone uranium deposits, clay minerals are also associated with sulfide minerals, usually pyrite, and organic carbonaceous matter. The primary clay minerals are usually smectites, illites, chlorites and mixed layer varieties. The integrity of these clay minerals is demonstrated by their retention of formational-mineralization ages determined by Rb-Sr geochronologic investigation of the Grants Mineral Belt of the United States. The importance of the clay minerals as analog for parts of the multi-barrier concept in radwaste disposal is their ability to impede water penetration into - and movement of key elements out of uranium rich zones. The clay minerals further sorb and in other ways incorporate into their structures many fission products and actinide analogs from man-made nuclear wastes. 22 refs., 1 fig., 3 tabs

On the loss of the rheological properties of activated montmorilonitic clays; Perda das propriedades reologicas de argilas montmoriloniticas ativadas

Energy Technology Data Exchange (ETDEWEB)

D` Avila, Joao Sampaio; Araujo, Raymundo Nonato Vieira de; Araujo, Ney Sa de; Campos, Ediraldo Barros; Nascimento, Reinaldo Ribeiro do [Sergipe Univ., Aracaju, SE (Brazil). Dept. de Engenharia Quimica

1988-12-31

A theory is developed associating clay aging to two key factors: reversibility of the cationic exchange reaction (activation reaction) and real humidity content of the clay. Various rheological parameters were studied during the aging process, where clay quality was shown to decrease. Aging effects were verified with clays obtained from an extrusion and a batching reactor. (author) 7 refs., 4 figs., 2 tabs.

Procedures and apparatus for measuring diffusion and distribution coefficients in compacted clays

Energy Technology Data Exchange (ETDEWEB)

Hume, H B

1993-12-01

Diffusion and distribution coefficients are needed to assess the migration of radionuclides through the compacted clay-based buffer and backfill materials proposed for use in a nuclear fuel waste disposal vault. This report describes the techniques used to measure these coefficients. Both steady-state and transient diffusion experiments are discussed. The procedures used to prepare the clay plug, assemble the cell, conduct the experiment and calculate the results are described. In addition, methods for obtaining distribution coefficients for radionuclides on both loose and compacted clays are discussed. (author). 18 refs., 3 tabs., 16 figs.

Procedures and apparatus for measuring diffusion and distribution coefficients in compacted clays

International Nuclear Information System (INIS)

Hume, H.B.

1993-12-01

Diffusion and distribution coefficients are needed to assess the migration of radionuclides through the compacted clay-based buffer and backfill materials proposed for use in a nuclear fuel waste disposal vault. This report describes the techniques used to measure these coefficients. Both steady-state and transient diffusion experiments are discussed. The procedures used to prepare the clay plug, assemble the cell, conduct the experiment and calculate the results are described. In addition, methods for obtaining distribution coefficients for radionuclides on both loose and compacted clays are discussed. (author). 18 refs., 3 tabs., 16 figs

The effect of freeze-thaw cycles on the hydraulic conductivity of compacted clay

International Nuclear Information System (INIS)

Waite, D.; Anderson, L.; Caliendo, J.; McFarland, M.

1994-01-01

A study was conducted to investigate the detrimental effects of freeze-thaw on the hydraulic conductivity of compacted clay. The purpose of this study was to determine the effect that molding water content has on the hydraulic conductivity of a compacted clay soil that is subjected to freeze-thaw cycles, and to determine the relationship between the number of freeze-thaw cycles and the hydraulic conductivity of the compacted clay soil. Clay soils compacted and frozen wet of optimum experienced an increase in hydraulic conductivity of approximately 140 fold. The hydraulic conductivity of clay compacted dry of optimum increased ten fold. These results are consistent with recent research which suggests that clay compacted wet of optimum experiences large increases in hydraulic conductivity while the hydraulic conductivity of clay compacted dry of optimum increases to a lesser extent. 12 refs., 9 figs

Phylogenetic analyses suggest a hybrid origin of the figs (Moraceae: Ficus) that are endemic to the Ogasawara (Bonin) Islands, Japan.

Science.gov (United States)

Kusumi, Junko; Azuma, Hiroshi; Tzeng, Hsy-Yu; Chou, Lien-Siang; Peng, Yan-Qiong; Nakamura, Keiko; Su, Zhi-Hui

2012-04-01

The Ogasawara Islands are oceanic islands and harbor a unique endemic flora. There are three fig species (Ficus boninsimae, F. nishimurae and F. iidaiana) endemic to the Ogasawara Islands, and these species have been considered to be closely related to Ficus erecta, and to have diverged within the islands. However, this hypothesis remains uncertain. To investigate this issue, we assessed the phylogenetic relationships of the Ogasawara figs and their close relatives occurring in Japan, Taiwan and South China based on six plastid genome regions, nuclear ITS region and two nuclear genes. The plastid genome-based tree indicated a close relationship between the Ogasawara figs and F. erecta, whereas some of the nuclear gene-based trees suggested this relationship was not so close. In addition, the phylogenetic analyses of the pollinating wasps associated with these fig species based on the nuclear 28S rRNA and mitochondrial cytB genes suggested that the fig-pollinating wasps of F. erecta are not sister to those of the Ogasawara figs These results suggest the occurrence of an early hybridization event(s) in the lineage leading to the Ogasawara figs. Copyright © 2012 Elsevier Inc. All rights reserved.

The Effect of Compost and the Ripe Fruit Waste of Fig on some Physical Properties of Surface Soil

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zahra dianat maharluei

2017-02-01

Full Text Available Introduction: In arid and semi-arid soils, low organic matter is one of the barriers to achieving optimal performance. The soils with more organic matter have a better structure and are more resistant to erosive factors such as water and wind. Soil organic matter has a particular importance and has significant impact on the stability of soil aggregates, the extension of plant root system, carbon and water cycles and soil resistance to erosion. This substance acts as a cementing agent and plays an important role in soil flocculation and formation of resistant aggregates.Also, the addition of organic matter to the soil increases soil porosity and decreases soil bulk density. Materials and Methods: In this research, the effect of the two types of organic matter (compost and the ripe fruit waste of fig on some soil physical properties was studied. A factorial experiment based on completely randomized design, including the four levels of compost and the ripe fruit waste of fig (0, 1, 2 and 4 by weight % and three soil types (loamy sand, loam and silty clay loam with three replications was carried out. The soil samples were collected from the three territories of Fars Province: loamy sand soil from Shiraz, loamy soil from Maharlu and Silty clay loam soil from Zarghan area. The soil samples were air dried and passed through a 2 mm sieve. The physical properties including the bulk density, particle density, porosity, moisture content and soil crust strength was measured. In this research, the soil texture by hydrometer method, Electrical conductivity of the soil saturated paste extract by electrical conductivity meter, saturated paste pH by pH meter, seedling emergence test, soil crust strength by a pocket penetrometer (HUMBOLDT MFG.CO. bulk density by cylindrical sample and particle density by pycnometer method were measured. The fig fruit treatments were prepared by thoroughly mixing the dried powder of ripe fig fruit passed through a 2 mm sieve (with

Organo-clay/anthracite filtration for oil removal

International Nuclear Information System (INIS)

Moazed, H.; Viragahavan, T.

1999-01-01

An advantage of organo-clay compared to other sorbents is that it can selectively remove organic pollutants from contaminated waters. An investigation was conducted to determine the potential of an organo-clay/anthracite mixture as a filter media for the removal of oil from synthetic and real oily waters. Also included in the study were column filtration studies using synthetic and real waste waters to determine the sorptive capacity of the material. In general, oil removal efficiencies in a 300 mm organo-clay/anthracite bed decreased with an increase in flow rates. Results of eight hour studies indicated that the depth of an organo-clay/anthracite bed has a direct effect on oil removal efficiency. The Thomas equation provides a reasonable fit of the data based on breakthrough studies. The model can be used to determine the parameters needed to design full-scale filtration columns. The uptake of oil by an organo-clay/anthracite mixture is well described by an equation including time such as the Weber or Moris model. The maximum solid-phase concentration of the solute values obtained from the Thomas equation were comparable to the values found by a mass balance approach. 12 refs., 8 figs., 4 tabs

Thermodynamically coupled mass transport processes in a saturated clay

International Nuclear Information System (INIS)

Carnahan, C.L.

1984-01-01

Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimension transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 refs., 8 figs

The ambiguous ripening nature of the fig (Ficus carica L.) fruit: a gene-expression study of potential ripening regulators and ethylene-related genes

Science.gov (United States)

Freiman, Zohar E.; Rosianskey, Yogev; Dasmohapatra, Rajeswari; Kamara, Itzhak; Flaishman, Moshe A.

2015-01-01

The traditional definition of climacteric and non-climacteric fruits has been put into question. A significant example of this paradox is the climacteric fig fruit. Surprisingly, ripening-related ethylene production increases following pre- or postharvest 1-methylcyclopropene (1-MCP) application in an unexpected auto-inhibitory manner. In this study, ethylene production and the expression of potential ripening-regulator, ethylene-synthesis, and signal-transduction genes are characterized in figs ripening on the tree and following preharvest 1-MCP application. Fig ripening-related gene expression was similar to that in tomato and apple during ripening on the tree, but only in the fig inflorescence–drupelet section. Because the pattern in the receptacle is different for most of the genes, the fig drupelets developed inside the syconium are proposed to function as parthenocarpic true fruit, regulating ripening processes for the whole accessory fruit. Transcription of a potential ripening regulator, FcMADS8, increased during ripening on the tree and was inhibited following 1-MCP treatment. Expression patterns of the ethylene-synthesis genes FcACS2, FcACS4, and FcACO3 could be related to the auto-inhibition reaction of ethylene production in 1-MCP-treated fruit. Along with FcMADS8 suppression, gene expression analysis revealed upregulation of FcEBF1, and downregulation of FcEIL3 and several FcERFs by 1-MCP treatment. This corresponded with the high storability of the treated fruit. One FcERF was overexpressed in the 1-MCP-treated fruit, and did not share the increasing pattern of most FcERFs in the tree-ripened fig. This demonstrates the potential of this downstream ethylene-signal-transduction component as an ethylene-synthesis regulator, responsible for the non-climacteric auto-inhibition of ethylene production in fig. PMID:25956879

YIELD OF COMMON FIG FERTIGATED WITH BOVINE BIOFERTILIZER IN THE SEMIARID REGION OF CEARÁ

Directory of Open Access Journals (Sweden)

FRANCISCO LIMEIRA DA SILVA

2016-01-01

Full Text Available The objective was to evaluate the productivity of the fig tree the organic fertirrigation cattle under different environmental conditions in Ceará semiarid region. The experiment was conducted in the experimental area of the Teaching Unit, Research and Extension, the IFCE, North Lemon Tree, EC. The experimental design was a randomized complete block design with split plots, with four replications and three plants per plot. The plots consisted of three rooms (full sun - PS; trellis - LT and greenhouse - EST, the subplots, the concentrations of bovine biofertilizer diluted in water in the following concentrations: T0 (0% of biofertilizer + 100% water; T1 (20% biofertilizer 80 +% water; T2 (40% biofertilizer + 60% water, T3 (60% biofertiliante + 40% water and subsubplot, the production cycles. The variables were evaluated: average fruit weight, fruit diameter, number of fruits per plant and yield. The cultivation environments (greenhouse and trellis promote better performance on average mass and diameter of the fruit compared to plants grown in full sun during the production cycles of the fig crop grown in Ceará semiarid region. The bovine biofertilizer in the concentration of 60% promoted the highest mass, diameter, number of fruits per plant and the fig crop yield.

Supplementary data Fig. S1 Fig. S1. FE-SEM images of the ...

Indian Academy of Sciences (India)

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Fig. S3. Cycling behavior of V2O5 nanomaterials recorded by CV at 20 mV·s-1 scan rate. Page 4. 4. Fig. S4. Fig. S4. Cycling behavior of V2O5 nanomaterials electrodes of galvanostatic charge and discharge profiles recorded by GCD at a current density of 1 A·g-1. Page 5. 5. Fig. S5. Fig. S5. Cycling behavior of V2O5 ...

Geomechanical behaviour of boom clay under ambient and elevated temperature conditions

International Nuclear Information System (INIS)

Neerdael, B.; Beaufays, R.; Buyens, M.; Bruyn, D. de; Voet, M.

1992-01-01

This research is focused upon in-situ investigations related to the (thermo-) mechanical behaviour of clay. Three main items are covered in this research area: Stress measurements around the underground research facility for radioactive waste disposal using hydraulical stress monitoring stations; detection of micro-fractures in the clay host, mainly using geophysical seismic techniques; long term mechanical behaviour of clay (this last item, studied by ANDRA at Mol, is not described in this paper). The stress monitoring stations appear to be more reliable in getting relative pressure variations with time rather than absolute values of stress, even after studying and improving the characteristics of the surrounding grout. The seismic techniques used to appear to be sensitive and accurate enough for detecting induced fracturation in the clay host, even for the low temperature. This is also in agreement with bench-scale experiments on clay samples intended to quantify the influence of both temperature and consolidation on the velocity. 10 refs., 80 figs., 3 tabs

Accurate control testing for clay liner permeability

Energy Technology Data Exchange (ETDEWEB)

Mitchell, R J

1991-08-01

Two series of centrifuge tests were carried out to evaluate the use of centrifuge modelling as a method of accurate control testing of clay liner permeability. The first series used a large 3 m radius geotechnical centrifuge and the second series a small 0.5 m radius machine built specifically for research on clay liners. Two permeability cells were fabricated in order to provide direct data comparisons between the two methods of permeability testing. In both cases, the centrifuge method proved to be effective and efficient, and was found to be free of both the technical difficulties and leakage risks normally associated with laboratory permeability testing of fine grained soils. Two materials were tested, a consolidated kaolin clay having an average permeability coefficient of 1.2{times}10{sup -9} m/s and a compacted illite clay having a permeability coefficient of 2.0{times}10{sup -11} m/s. Four additional tests were carried out to demonstrate that the 0.5 m radius centrifuge could be used for linear performance modelling to evaluate factors such as volumetric water content, compaction method and density, leachate compatibility and other construction effects on liner leakage. The main advantages of centrifuge testing of clay liners are rapid and accurate evaluation of hydraulic properties and realistic stress modelling for performance evaluations. 8 refs., 12 figs., 7 tabs.

Semivariogram models for estimating fig fly population density throughout the year

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Mauricio Paulo Batistella Pasini

2014-07-01

Full Text Available The objective of this work was to select semivariogram models to estimate the population density of fig fly (Zaprionus indianus; Diptera: Drosophilidae throughout the year, using ordinary kriging. Nineteen monitoring sites were demarcated in an area of 8,200 m2, cropped with six fruit tree species: persimmon, citrus, fig, guava, apple, and peach. During a 24 month period, 106 weekly evaluations were done in these sites. The average number of adult fig flies captured weekly per trap, during each month, was subjected to the circular, spherical, pentaspherical, exponential, Gaussian, rational quadratic, hole effect, K-Bessel, J-Bessel, and stable semivariogram models, using ordinary kriging interpolation. The models with the best fit were selected by cross-validation. Each data set (months has a particular spatial dependence structure, which makes it necessary to define specific models of semivariograms in order to enhance the adjustment to the experimental semivariogram. Therefore, it was not possible to determine a standard semivariogram model; instead, six theoretical models were selected: circular, Gaussian, hole effect, K-Bessel, J-Bessel, and stable.

Época de poda da figueira cultivada no estado de São Paulo Pruning time for fig trees in the state of São Paulo

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Orlando Rigitano

1963-01-01

Full Text Available No Estado de São Paulo as figueiras (Ficus carica L. são anualmente submetidas a um tipo de poda hibernal que consiste na eliminação quase total da copa formada na estação anterior. Com a finalidade de estudar o comportamento de figueiras podadas em diferentes épocas durante o inverno, foi iniciado em 1960, em Campinas, um experimento com cinco épocas de poda no período de 1.° de maio a 1.° de setembro. São apresentados os dados de produção, por tratamento obtidos em 1962 e 1963, relativos ao número e ao pêso de figos, assim como os pesos médios de uma fruta. Os dados de 1963, revelaram diferenças significativas e permitiram várias conclusões. A poda feita em 1.° de agôsto ofereceu os melhores resultados, embora sem diferir significativamente daquela executada em 1.° de julho. Como era esperado, as podas levadas a efeito nas épocas extremas, isto é, em princípios de maio e de setembro, resultaram nas produções mais baixas. Observou-se tendência da obtenção de colheitas mais precoces e figos mais pesados nos tratamentos mais produtivos.With a view to compare the effects on fruit bearing, pruning of fig trees was carried out in Campinas, State of São Paulo, during the dormant season of the plant, at 5 different dates, namely on the 1st day of each of the months of May, June, July, August and September. Pruning was started as soon as the plants became more or less dormant in the fall and was continued until vegetation again appeared at the end of winter. The pruning operation took place for two following years and at the dates mentioned all the new branches were cut back to short stubs. The experimental plot consisted of 30 trees of the variety "Roxo de Valinhos" (San Piero spread apart 7 by 13 feet and was laid out in randomized blocks with 3 replications. The results of this trial can be summarized as follows: a Trees pruned on August 1st gave the highest yield followed by those pruned on July 1st. While the

Fault-tree analysis for probabilistic assessment of radioactive-waste segregation: an application to a plastic clay formation at a specific site

International Nuclear Information System (INIS)

D'Alessandro, M.; Bonne, A.

1982-01-01

This study concerns a probabilistic safety analysis of potential nuclear-waste repository which may be mined into a Tertiary clay formation underlying the Nuclear Research Centre at Mol (Belgium). The value of the geological barrier has been analyzed in probabilistic terms through the application of the Fault-Tree Analysis (FTA) which can answer two main questions: how can the barrier fail (query) and what is the failure probability (query). FTA has been applied to conceptual radioactive-waste disposal systems. In this paper this methodology has been applied to a specific clay formation, to test the applicability of the procedure to a potential site. With this aim, release probabilities to three different receptors (groundwater, land surface, and atmosphere) were estimated for four different time periods. Because of obvious uncertainties in geology predictive capabilities, a probability band has been obtained. Faulting phenomena are among the main mechanisms having the potential to cause release to groundwater, whereas direct releases to land surface may be linked to various glacial phenomena; on short term, different types of human actions may be important. The overall failure probabilities seem to be sufficiently low to offer a good safety margin. (author)

Substratos no enraizamento de estacas herbáceas de figueira oriundas da desbrota Substrates in the rooting of fig tree herbaceous cuttings originated from the sprouting

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Rafael Pio

2005-06-01

Full Text Available Com o presente trabalho teve-se como objetivo verificar o enraizamento de estacas de figueira oriundas da desbrota, por meio da utilização de diferentes substratos. Foram coletadas estacas herbáceas de figueira 'Roxo de valinhos', aproximadamente com 10 cm de comprimento, no momento da desbrota da figueira. As estacas com apenas duas folhas e sem gema apical foram acondicionadas em bandejas de polipropileno, contendo diferentes substratos: casca de pinus®, vermiculita®, fibra de coco®, plantmax®, solo + esterco bovino (1:1 v/v e tropstrato® . Posteriormente, as estacas foram colocadas em casa-de-vegetação, com umidade e temperatura controlada. Após 50 dias, avaliaram-se a porcentagem de estacas enraizadas, brotadas e mortas, número de folhas e raízes emitidas da estaca. Os substratos fibra de coco® e plantmax® promoveram melhores resultados.The present work had the objective to verify the rooting of fig tree cuttings originating from sprouting, through the use of different substrates. Herbaceous cuttings were collected of 'Roxo de valinhos' fig tree with 10 cm of length when the sprouting was happening. The cuttings with two leaves and not of the apical bud to conditioned in polypropylene trays containing different substrates: casca de pinus®, vermiculita®, coconut fiber®, plantmax®, soil + cow mature(1:1 v/v and tropstrato® . The cuttings were placed at greenhouse, under humidity and temperature control. After 50 days, the rooting, sprouting and death cutting percentage, the number of leaves and roots of each cutting were evaluated. The substrates coconut fiber® and plantmax® promoted better results.

Termites utilise clay to build structural supports and so increase foraging resources.

Science.gov (United States)

Oberst, Sebastian; Lai, Joseph C S; Evans, Theodore A

2016-02-08

Many termite species use clay to build foraging galleries and mound-nests. In some cases clay is placed within excavations of their wooden food, such as living trees or timber in buildings; however the purpose for this clay is unclear. We tested the hypotheses that termites can identify load bearing wood, and that they use clay to provide mechanical support of the load and thus allow them to eat the wood. In field and laboratory experiments, we show that the lower termite Coptotermes acinaciformis, the most basal species to build a mound-nest, can distinguish unloaded from loaded wood, and use clay differently when eating each type. The termites target unloaded wood preferentially, and use thin clay sheeting to camouflage themselves while eating the unloaded wood. The termites attack loaded wood secondarily, and build thick, load-bearing clay walls when they do. The termites add clay and build thicker walls as the load-bearing wood is consumed. The use of clay to support wood under load unlocks otherwise unavailable food resources. This behaviour may represent an evolutionary step from foraging behaviour to nest building in lower termites.

Clay-based materials for engineered barriers: a review

International Nuclear Information System (INIS)

Lajudie, A.; Raynal, J.; Petit, J.C.; Toulhoat, P.

1994-01-01

The potential importance of backfilling and plugging in underground radioactive waste repositories has led different research institutions to carry out extensive studies of swelling clay materials for the development of engineered barriers in underground conditions. These materials should combine a variety of hydro-thermo-mechanical and geochemical properties: impermeability, swelling ability in order to fill all void space, heat transfer and retention capacity for the most noxious radionuclides. Smectite clays best exhibit these properties and most of the research effort has been devoted to this type of materials. In this paper, mineralogical composition, sodium or calcium content, thermo-hydro-mechanical properties, swelling pressure, hydraulic and thermal conductivity, and chemical properties of five smectite clays selected by five major nuclear countries are reviewed: Avonseal montmorillonite (Canada), MX 80 montmorillonite (Sweden), Montigel montmorillonite (Switzerland), S-2 montmorillonite (Spain), and Fo-Ca inter stratified kaolinite/beidellite (France). (J.S.). 29 refs., 5 figs., 3 tabs

Facts and features of radionuclide migration in Boom Clay

International Nuclear Information System (INIS)

De Regge, P.; Henrion, P.; Monsecour, M.; Put, M.

1988-01-01

The evolution which took place during ten years of research on the behaviour of radionuclides in Boom Clay is described. Initially, the Boom Clay was regarded as a chemically inert exchanger and the radiochemical research aimed at determining the distribution of cations between the clay and some liquid phases. The observation that Boom Clay deteriorates in contact with air and loses important intrinsic properties formed a major breakthrough in the research and led to a careful examination of the real in-situ conditions. Efforts devoted to the understanding of the chemical factors pertaining to the pH, the redox potential, the extent of the buffering capacity of FeS 2 and CaCO 3 in equilibrium with the interstitial aqueous phase are reviewed. Also emerging from the overall picture was the role of the organic material present in the Boom Clay. In contrast to the water percolating fractured formations which may not be in equilibrium with the rock, the interstitial aqueous phase is completely in equilibrium with Boom Clay mainly because of its low permeability and the large excesses of buffering components. As the retention mechanisms are better understood, a more coherent picture is obtained from distribution and diffusion experiments and the effects of consolidation are being investigated in detail. 23 refs.; 4 figs.; 3 tabs

Naphtha interaction with bitumen and clays : a preliminary study

Energy Technology Data Exchange (ETDEWEB)

Afara, M.; Munoz, V.; Mikula, R. [Natural Resources Canada, Devon, AB (Canada). CANMET Western Research Centre

2010-07-01

This PowerPoint presentation described a preliminary study conducted to characterize naphtha interactions with bitumen and clays. Coarse tailings, fluid-fine tailings, and froth treatment tailings are produced as a result of surface mine oil sands operations. Solvents are used to produce the bitumens, but the actual fraction of the solvent that evaporates and contributes to VOCs from tailing ponds is poorly understood. This study examined the interactions between the solvent, bitumen and mineral components in froth treatment tails. The study was conducted with aim of quantifying the VOC or solvent escaping from the froth treatment tailings. Samples containing bitumen, clay, a bitumen-clay mixture, or MFT were spiked with 3000 ppm of solvent. The amount of naphtha released was monitored by gas chromatography, mass spectrometry, and flame ionization detection of the evolved gases. The results were expressed as a percentage of the total hydrocarbon peak area of the sample versus a control. Results of the study showed that the naphtha interacted more strongly with the bitumen than with kaolinite and the clay minerals from the oil sands. Although initial solvent evaporation was reduced in the presence of bitumens and clays, long-term solvent releases will need to be quantified. tabs., figs.

A review of WIPP [Waste Isolation Pilot Plant] repository clays and their relationship to clays of adjacent strata

International Nuclear Information System (INIS)

Krumhansl, J.L.; Kimball, K.M.; Stein, C.L.

1990-12-01

The Salado Formation is a thick evaporite sequence located in the Permian Delaware Basin of southeastern New Mexico. This study focuses on the intense diagenetic alteration that has affected the small amounts of clay, feldspar, and quartz washed into the basin during salt deposition. These changes are of more than academic interest since this formation also houses the WIPP (Waste Isolation Pilot Plant). Site characterization concerns warrant compiling a detailed data base describing the clays in and around the facility horizon. An extensive sampling effort was undertaken to address these programmatic issues as well as to provide additional insight regarding diagenetic mechanisms in the Salado. Seventy-five samples were collected from argillaceous partings in halite at the stratigraphic level of the Waste Isolation Pilot Plant (WIPP). These were compared with twenty-eight samples from cores of the Vaca Triste member of the Salado, a thin clastic unit at the top of the McNutt potash zone, and with a clay-rich sample from the lower contact of the Culebra Dolomite (in the overlying Rustler Formation). These settings were compared to assess the influence of differences in brine chemistry (i.e., halite and potash facies, normal to hypersaline marine conditions) and sediment composition (clays, sandy silt, dolomitized limestone) on diagenetic processes. 44 refs., 11 figs., 5 tabs

A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

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Graham Edward

2006-04-01

Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

Laboratory and field tests for radionuclide migration and high flow paths in clay

International Nuclear Information System (INIS)

Bourke, P.J.; Jefferies, N.L.; Lineham, T.R.; Nesirky, P.

1991-01-01

Two investigations have been undertaken in this programme. The principal investigation was at Culham Laboratory, England, where water flow within the Kimmeridge clay was measured. A subsidiary investigation at SCK/CEN was undertaken at the Underground Research Laboratory SCK/CEN Mol, Belgium, where an in situ measurement of solute transport by diffusion was attempted. The in situ migration experiment at the Underground Research Laboratory at SCK/CEN Mol, Belgium, was unsuccessful, due to problems with the engineering installation. These difficulties caused significant disturbance to the Boom clay which was to be tested. Nevertheless the laboratory test proved the feasibility of the experiment. The field measurements at Culham Laboratory, Oxfordshire, were completed with the flow testing of a very silty clay horizon in the Kimmeridge clay. This layer was proved to be laterally continuous after drilling three exploratory boreholes. The hydraulic conductivity of the layer was ≥ 10 -8 ms -1 and comparative tests in the clay showed the conductivity of the clay to be at least 50 times less. 12 figs

Moessbauer study of the transformations occurring in egyptian alluvial and calcareous clays during firing

International Nuclear Information System (INIS)

Sallam, H.A.; Gomma, N.S.; El Meligy, W.M.; Eissa, N.A.

1994-01-01

Egyptian alluvial and calcareous clay samples, which are used in pottery production, were heated at different temperatures in air up to 1100 degree C. The physicochemical transformations were followed up and could be separated in two main stages; i) the dehydroxilation, of the clay mineral, stage for firing up to 700 degree C, ii) the second stage for firing at 900 degree C and higher. In the later stage the effect of calcium content was very pronounced. 2 figs

A large-scale laboratory investigation into the movement of gas and water through clay barriers exposed to the environment

International Nuclear Information System (INIS)

1993-01-01

This report describes a large scale laboratory investigation into the movements of gas and water through clay barriers exposed to the environment. The test beds, each 3m square were constructed and filled with clay to a depth of 400 mm, after compaction. One test bed contained London Clay, the other Glacial Till. The clays were subjected to accelerated environmental cycling and tests carried out on samples of the clays at appropriate intervals. The tests included measurements of the mechanical, physical and chemical properties of the clays and their permeability to gas and water. Gas permeability emerged as the more appropriate for the clays being investigated. The report discusses the difficulties of measuring the permeability of partially saturated clays and the need to define the measuring techniques when specifying limiting acceptability values. 55 refs., 8 figs., 7 tabs., 27 plates

Clay preference and particle transport behavior of Formosan subterranean termites (Isoptera: Rhinotermitidae): a laboratory study.

Science.gov (United States)

Wang, Cai; Henderson, Gregg

2014-12-01

Although preference and utilization of clay have been studied in many higher termites, little attention has been paid to lower termites, especially subterranean termites. The Formosan subterranean termite, Coptotermes formosanus Shiraki, can modify its habitat by using clay to fill tree cavities. Here, the biological significance of clay on C. formosanus was investigated. Choice tests showed that significantly more termites aggregated in chambers where clay blocks were provided, regardless of colony group, observation period, or nutritional condition (fed or starved). No-choice tests showed that clay had no observable effect on survivorship, live or dry biomass, water content, and tunneling activity after 33-35 d. However, clay appeared to significantly decrease filter paper consumption (dry weight loss). Active particle (sand, paper, and clay) transport behavior was observed in both choice and no-choice tests. When present, clay was preferentially spread on the substrate, attached to the smooth surfaces of the containers, and used to line sand tunnels. Mechanisms and potential application of clay attraction are discussed. © 2013 Institute of Zoology, Chinese Academy of Sciences.

Study of Adsorption of Phenanthrene on Different Types of Clay Minerals

International Nuclear Information System (INIS)

Contreras, M. L.; Escolano, O.; Rodriguez, V.; Diaz, F. J.; Perez, R.; Garcia, S.; Garcia Frutos, F. J.

2003-01-01

The fate and behaviour of non-ionic hydrophobic organic compounds in deep soil is mainly controlled by the mineral fraction present in the soil due to the very low organic carbon content of the deep soil. The mineral fraction that may greatly influence the fate and transport of these compounds due to its presence and properties are the clay minerals. Clay minerals also become increasingly important in low organic matter content soils. There tree, studies of non-ionic hydrophobic organic compounds adsorption on clay minerals without organic matter are necessary lo better understand the fate and transport of these compounds. In this work we used phenanthrene as model compound of non-ionic hydrophobic organic compound and four pure clay minerals: kaolinite, illite, montmorillonite, and vermiculite including muscovite mica. These clays minerals are selected due to its abundance in represents ve Spanish soils and different properties as its structural layers and expanding capacity. Batch experiments were performed using phenanthrene aqueous solutions and the clays selected. Phenanthrene sorption isotherms for all clays, except muscovite mica, were best described by the Freundlich model. Physical sorption on the external surfaces is the most probable adsorption mechanisms. In this sense, the presence of non-polar nano-sites on clay surfaces could determine the adsorption of phenanthrene by hydrophobic interaction on these sites. (Author) 22 refs

Codivergence and multiple host species use by fig wasp populations of the Ficus pollination mutualism

Directory of Open Access Journals (Sweden)

McLeish Michael J

2012-01-01

Full Text Available Abstract Background The interaction between insects and plants takes myriad forms in the generation of spectacular diversity. In this association a species host range is fundamental and often measured using an estimate of phylogenetic concordance between species. Pollinating fig wasps display extreme host species specificity, but the intraspecific variation in empirical accounts of host affiliation has previously been underestimated. In this investigation, lineage delimitation and codiversification tests are used to generate and discuss hypotheses elucidating on pollinating fig wasp associations with Ficus. Results Statistical parsimony and AMOVA revealed deep divergences at the COI locus within several pollinating fig wasp species that persist on the same host Ficus species. Changes in branching patterns estimated using the generalized mixed Yule coalescent test indicated lineage duplication on the same Ficus species. Conversely, Elisabethiella and Alfonsiella fig wasp species are able to reproduce on multiple, but closely related host fig species. Tree reconciliation tests indicate significant codiversification as well as significant incongruence between fig wasp and Ficus phylogenies. Conclusions The findings demonstrate more relaxed pollinating fig wasp host specificity than previously appreciated. Evolutionarily conservative host associations have been tempered by horizontal transfer and lineage duplication among closely related Ficus species. Independent and asynchronistic diversification of pollinating fig wasps is best explained by a combination of both sympatric and allopatric models of speciation. Pollinator host preference constraints permit reproduction on closely related Ficus species, but uncertainty of the frequency and duration of these associations requires better resolution.

Premature attraction of pollinators to inaccessible figs of Ficus altissima: a search for ecological and evolutionary consequences.

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Yuan Zhang

Full Text Available Adult life spans of only one or two days characterise life cycles of the fig wasps (Agaonidae that pollinate fig trees (Ficus spp., Moraceae. Selection is expected to favour traits that maximise the value of the timing of encounters between such mutualistic partners, and fig wasps are usually only attracted to their hosts by species- and developmental-stage specific volatiles released from figs at the time when they are ready to be entered, oviposited in and pollinated. We found that Ficus altissima is exceptional, because it has persistent tight-fitting bud covers that prevent its Eupristina altissima pollinator (and a second species of 'cheater' agaonid from entering its figs for several days after they start to be attracted. We examined the consequences of delayed entry for the figs and fig wasps and tested whether delayed entry has been selected to increase adult longevity. We found that older pollinators produced fewer and smaller offspring, but seed production was more efficient. Pollinator offspring ratios also varied depending on the age of figs they entered. The two agaonids from F. altissima lived slightly longer than six congeners associated with typical figs, but this was explainable by their larger body sizes. Delayed entry generates reproductive costs, especially for the pollinator. This opens an interesting perspective on the coevolution of figs and their pollinators and on the nature of mutualistic interactions in general.

Climate warming and the potential extinction of fig wasps, the obligate pollinators of figs.

Science.gov (United States)

Jevanandam, Nanthinee; Goh, Alexander G R; Corlett, Richard T

2013-06-23

Figs (Ficus) have a reciprocally obligate mutualism with tiny, short-lived (1-2 days) fig wasps (Agaonidae). The small size and short life of these pollinators is expected to make them more vulnerable to climate change than their larger and longer-lived hosts. We experimentally tested the thermal tolerances of four species of adult female fig wasp from equatorial Singapore. The results suggest that an increase of 3°C or more above the current temperatures experienced across much of the equatorial tropics would markedly decrease the active adult lifespan of all four species. Fig plants are the centre of an intricate web of specialist and generalist animals. Unless fig wasps can acclimate or adapt to warmer temperatures in time, these responses may disrupt the mutualism, potentially affecting multiple trophic levels.

Experience acquired with the realisation of a geotechnical measurement campaign in a deep clay formation

International Nuclear Information System (INIS)

Manfroy, P.; Neerdael, B.; Buyens, M.

1985-01-01

Belgium has selected clay as a possible disposal medium for conditioned radioactive waste. CEN/SCK has launched an important research and development programme to evaluate the disposal potential of the Boom clay formation present under the nuclear site Mol-Dessel. An underground facility has been built at 220 m. depth in order to proceed to geomechanical, corrosion, migration and heat transfer experiments. During its construction numerous geotechnical measuring instruments were emplaced on the lining and in the clay medium. Successful realization of such measurement campaigns was hampered by the very difficult underground working conditions. This paper describes what can be learned from the experience gained so far. 5 refs.; 5 figs

Tree health and physiology in a changing environment

Science.gov (United States)

Walter C. Shortle; Kevin T. Smith; Rakesh Minocha; Subhash Minocha; Philip M. Wargo; Kristina A. Vogt

2000-01-01

A tree is a large, long-lived, perennial, compartmented, woody, shedding, walling plant. This definition is based on new tree biology concepts (Shigo, 1986a,b, 1991) and explains much about how mature trees function through their unique structure. When the tree begins its life, it is mostly leaf in mass (Fig. 7.la). As a tree grows in stature, it becomes mostly stem in...

Repository tunnel construction in deep clay formations

International Nuclear Information System (INIS)

Clarke, B.G.; Mair, R.J.; Taylor, R.N.

1992-01-01

One of the objects of the Hades project at Mol, Belgium has been to evaluate the feasibility of construction of a deep repository in the Boom clay formation at depth of approximately 225 metres. The main objective of the present project was to analyse and interpret the detailed geotechnical measurements made around the Hades trial shaft and tunnel excavations and evaluate the safety of radioactive waste disposal in a repository facility in deep clay formations. Plasticity calculations and finite element analyses were used which gave results consistent with the in-situ measurements. It was shown that effective stress analysis could successfully predict the observed field behaviour. Correct modelling of the small-strain stiffness of the Boom clay was essential if reasonable predictions of the pore pressure response due to construction are to be made. The calculations undertaken indicated that, even in the long term, the pressures on the test drift tunnel lining are likely to be significantly lower than the overburden pressure. Larger long-term tunnel lining pressures are predicted for impermeable linings. A series of laboratory stress path tests was undertaken to determine the strength and stiffness characteristics of the Boom clay. The tests were conducted at appropriate effective stress levels on high-quality samples retrieved during construction of the test drift. The apparatus developed for the testing is described and the results discussed. The development of a self boring retracting pressure-meter is described. This novel in-situ testing device was specifically designed to determine from direct measurements the convergence/confinement curve relevant to tunnelling in clay formations. 44 refs., 60 figs., 3 tabs

X-ray diffraction analysis of clay stones, Muglad Sedimentary Basin, Sudan

International Nuclear Information System (INIS)

Ali, A. E.

1997-01-01

This study deals with the theoretical and experimental aspects of X-ray diffraction (XRD) technique. Moreover the XRD technique has been used to investigate the clay mineral types and their distribution for samples obtained from exploration wells in the Mugald Sedimentary Basin in Western Sudan. The studied samples range in depth from 1524 m to 4572 m. The XRD analysis of samples shows that they consist of kaolinite, smectite, illite, chlorite and the mixed-layer smectite/illite. Kaolinite has higher abundance (15 - 72 %) followed by illite (7 - 34 %), smectite (11 - 76 %) and the less abundance of chlorite and the mixed-layer smectite/illite. Non-clay minerals found include quartz and cristabolite. The clay mineral types and their vertical distribution reflect various controls such as environmental, burial diagenesis, source rocks and climatic influences in the Muglad Sedimentary Basin. (author). 19 refs., 11 figs., 3 tabs

How to be a dioecious fig: Chemical mimicry between sexes matters only when both sexes flower synchronously

Science.gov (United States)

Hossaert-McKey, M.; Proffit, M.; Soler, C. C. L.; Chen, C.; Bessière, J.-M.; Schatz, B.; Borges, R. M.

2016-01-01

In nursery pollination mutualisms, which are usually obligate interactions, olfactory attraction of pollinators by floral volatile organic compounds (VOCs) is the main step in guaranteeing partner encounter. However, mechanisms ensuring the evolutionary stability of dioecious fig–pollinator mutualisms, in which female fig trees engage in pollination by deceit resulting in zero reproductive success of pollinators that visit them, are poorly understood. In dioecious figs, individuals of each sex should be selected to produce odours that their pollinating wasps cannot distinguish, especially since pollinators have usually only one choice of a nursery during their lifetime. To test the hypothesis of intersexual chemical mimicry, VOCs emitted by pollen-receptive figs of seven dioecious species were compared using headspace collection and gas chromatography-mass spectrometry analysis. First, fig-flower scents varied significantly among species, allowing host-species recognition. Second, in species in which male and female figs are synchronous, intersexual VOC variation was not significant. However, in species where figs of both sexes flower asynchronously, intersexual variation of VOCs was detectable. Finally, with one exception, there was no sexual dimorphism in scent quantity. We show that there are two ways to use scent to be a dioecious fig based on differences in flowering synchrony between the sexes. PMID:26888579

Adsorption of heavy metal ions on different clays

International Nuclear Information System (INIS)

Kruse, K.

1992-01-01

The aim of the present dissertation is to study the adsorption of heavy metal ions (Cd 2+ , Cu 2+ , Pb 2+ , Zn 2+ ) and their mixtures on clays. Different clays and bentonites (Ca 2+ -bentonite, activated Na + -bentonite, special heavy metal adsorber bentonite, two organophilic bentonites and a mixed layer clay) were used. The adsorbed metal ions were desorbed by appropriate solutions of HCl, EDTA and dioctadecyl dimethylammonium bromide. High concentrations of the heavy metal ions in the solutions can be reached. The desorption guarantees economical recycling. After desorption the clays were used (up to three times) for purification of contaminated water. The best experimental conditions, i.e. the highest adsorption of heavy metal ions from aqueous solutions was found for the greatest ratio of adsorbent/adsorbate. The adsorption was very fast. Calcium, sodium bentonites and the heavy metal adsorber bentonite attained the highest adsorption and desorption for Cu 2+, Zn 2+ and Pb 2+ ions. Cd 2+ ions were only absorbed by Silitonit, a special heavy metal absorber bentonite. The mixed layer clay (Opalit) ranges in adsorption and desorption properties below the unmodified Ca 2+ -bentonite (Montigel) or the activated Na + -bentonite. Only Tixosorb and Tixogel (organophilic bentonites) reach the lowest value of heavy metal adsorption. Only lead cations which are characterised by good polarizability were adsorbed at higher rates, therefore the organophilic bentonites are not appropriate for adsorption of heavy metal ions from aqueous solutions. Mixing of the metal ions generally decreases the adsorption of Pb 2+ and increases the adsorption of Cd 2+ . From mixtures if heavy metal ions adsorption and desorption of Cu 2+ ions reached a maximum for all clays. (author) figs., tabs., 56 refs

Effect of illite clay and divalent cations on bitumen recovery

Energy Technology Data Exchange (ETDEWEB)

Ding, X. [SNC-Lavalin Inc., Calgary, AB (Canada); Repka, C. [Baker Petrolite Corp., Fort McMurray, AB (Canada); Xu, Z.; Masliyah, J. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

2006-12-15

Nearly 35 per cent of Canada's petroleum needs can be met from the Athabasca oil sands, particularly as conventional sources of petroleum decline. The interactions between bitumen and clay minerals play a key role in the recovery process of bitumen because they affect bitumen aeration. The 2 clays minerals found in various oil sands extraction process streams are kaolinite and illite. In this study, doping flotation tests using deionized water and electrokinetic studies were performed to examine the effect of illite clays on bitumen recovery. The effect of magnesium ions was also examined and compared with calcium ions. This paper also discussed the effects of temperature and tailings water chemistry. The negative effect of illite clay on bitumen recovery was found to be associated with its acidity. Denver flotation cell measurements indicated that the addition of calcium or magnesium ions to the flotation deionized water had only a slight effect on bitumen recovery, but the co-addition of illite clay and divalent cations resulted in a dramatic reduction in bitumen recovery. The effect was more significant at lower process temperature and low pH values. Zeta potential distributions of illite suspensions and bitumen emulsions were measured individually and as a mixture to determine the effect of divalent cations on the interaction between bitumen and illite clay. The presence of 1 mM calcium or magnesium ions in deionized water had a pronounced effect on the interactions between bitumen and illite clay. Slime coating of illite onto bitumen was not observed in zeta potential distribution measurements performed in alkaline tailings water. When tests were conducted using plant recycle water, the combination of illite clay and divalent cations did not have an adverse effect on bitumen recovery. 25 refs., 3 tabs., 15 figs.

Effects of auxin and misting on the rooting of herbaceous and hardwood cuttings from the fig tree Efeitos de auxina e nebulização no enraizamento de estacas herbáceas e lenhosas de figueira

Directory of Open Access Journals (Sweden)

Cleiton Mateus Sousa

2013-06-01

Full Text Available Propagation of the fig tree predominately uses hardwood cuttings obtained from pruning stock plants. With a view to optimising fig tree propagation, the effects of auxin and misting on the rooting of herbaceous and hardwood cuttings from the fig tree were evaluated. An experiment was set up in a 2x2x2 factorial design, with two types of cuttings (softwood and hardwood, two levels of auxin (0 and 1000 mg L-1 indolbutyric acid and two environments (with and without misting. Thirty days after starting the experiment, rooting, root length, sprouting and losses were all evaluated. The interaction of the type of cutting and the auxin was significant for rooting, sprouting, root length and cutting loss. Misting did not affect the variables analysed. In the absence of auxin, there was no difference between the type of cutting for rooting, length of root and sprouting, while the application of auxin (1,000 mg L-1 produced a reduction in these variables. The production of fig tree seedlings can be made from either softwood or hardwood cuttings and does not require the use of auxin or misting.A propagação da figueira predomina com o uso de estacas lenhosas obtidas após a poda de plantas matrizes. Visando otimizar a propagação da figueira, avaliou-se os efeitos da auxina e da nebulização no enraizamento de estacas herbáceas e lenhosas de figueira. Foi implantado um experimento em fatorial 2x2x2, sendo dois tipos de estacas (herbáceas e lenhosas, dois níveis de auxina (0 e 1.000 mg L-1 de ácido indolbultírico e dois ambientes (com ou sem nebulização. Aos 30 dias após a implantação do experimento, avaliou-se o enraizamento, comprimento da radícula, brotação e perdas. A interação do tipo de estaca e auxina foi significativa para enraizamento, brotação, comprimento da radícula e perdas de estacas. A nebulização não interferiu nas variáveis analisadas. Na ausência de auxina não houve diferença entre os tipos de estacas para o

Ring shear characteristics of clays in fractured-zone-landslide. Hasaitai chisuberichi no nenseido no ring sendan tokusei

Energy Technology Data Exchange (ETDEWEB)

Yatabe, R; Yagi, N; Enoki, M [Ehime Univ., Ehime (Japan). Faculty of Engineering

1991-09-20

The importance of study on the residual strength, in addition to the peak strength, has been pointed out for the study of landslides. The residual strength characteristics, effects of shearing rate, and grain size of clays, as well as the residual strength characteristics of clay minerals of a fractured zone landslide were examined by ring shear tests. The residual friction angles {phi}{sub r} of the tested clays of the fractured zone landslide were from 10 to 31{degree}, and were smaller than those of shearing resistance angles {phi}{prime} obtained by triaxial tests by 5 to 15{degree}. Contrary to the pointing out made hitherto, no correlation between clay content CF and plastic index was recognized for {phi}{sub r} of clays of a fractured zone landslide. As regards CF, the relation with CF was far below the lowest limit indicated by now. Ring shear characteristics of principal structural clay minerals, vermiculite, mica, illite, chlorite, and kaolinite were investigated. {phi}{sub r} of these clay minerals were in the range from 10 to 25{degree}. 20 refs., 14 figs., 2 tabs.

Chemical camouflage: a key process in shaping an ant-treehopper and fig-fig wasp mutualistic network.

Science.gov (United States)

Wang, Bo; Lu, Min; Cook, James M; Yang, Da-Rong; Dunn, Derek W; Wang, Rui-Wu

2018-01-30

Different types of mutualisms may interact, co-evolve and form complex networks of interdependences, but how species interact in networks of a mutualistic community and maintain its stability remains unclear. In a mutualistic network between treehoppers-weaver ants and fig-pollinating wasps, we found that the cuticular hydrocarbons of the treehoppers are more similar to the surface chemical profiles of fig inflorescence branches (FIB) than the cuticular hydrocarbons of the fig wasps. Behavioral assays showed that the cuticular hydrocarbons from both treehoppers and FIBs reduce the propensity of weaver ants to attack treehoppers even in the absence of honeydew rewards, suggesting that chemical camouflage helps enforce the mutualism between weaver ants and treehoppers. High levels of weaver ant and treehopper abundances help maintain the dominance of pollinating fig wasps in the fig wasp community and also increase fig seed production, as a result of discriminative predation and disturbance by weaver ants of ovipositing non-pollinating fig wasps (NPFWs). Ants therefore help preserve this fig-pollinating wasp mutualism from over exploitation by NPFWs. Our results imply that in this mutualistic network chemical camouflage plays a decisive role in regulating the behavior of a key species and indirectly shaping the architecture of complex arthropod-plant interactions.

Clay membrane made of natural high plasticity clay

DEFF Research Database (Denmark)

Foged, Niels; Baumann, Jens

1998-01-01

Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...... ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay material...... has been evaluated using standardised methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15 to 0.3m thick clay membrane have been tested...

Clay membrane made of natural high plasticity clay:

DEFF Research Database (Denmark)

Foged, Niels; Baumann, Jens

1999-01-01

Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

Thermal volume changes in clays and clay-stones

International Nuclear Information System (INIS)

Delage, P.; Sulem, J.; Mohajerani, M.; Tang, A.M.; Monfared, M.

2012-01-01

Document available in extended abstract form only. The disposal of high activity exothermic radioactive waste at great depth in clay host rocks will induce a temperature elevation that has been investigated in various underground research laboratories in Belgium, France and Switzerland through in-situ tests. Thermal effects are better known in clays (in particular Boom clay) than in clay-stone (e.g. Opalinus clay and Callovo-Oxfordian clay-stone). In terms of volume changes, Figure 1 confirms the findings of Hueckel and Baldi (1990) that volume changes depend on the over-consolidation ratio (OCR) of the clay. In drained conditions, normally consolidated clays exhibit plastic contraction when heated, whereas over-consolidated clay exhibit elastic dilation. The nature of thermal volume changes in heated clays obviously has a significant effect on thermally induced pore pressures, when drainage is not instantaneous like what occurs in-situ. Compared to clays, the thermal volume change behaviour of clay-stones is less well known than that of clays. clay-stone are a priori suspected to behave like over-consolidated clays. In this paper, a comparison of recent results obtained in the laboratory on the drained thermal volume changes of clay-stones is presented and discussed. It is difficult to run drained mechanical tests in clay-stones like the Opalinus clay and the Callovo-Oxfordian clay-stone because of their quite low permeability (10 -12 - 10 -13 m/s). This also holds true for thermal tests. Due to the significant difference in thermal expansion coefficient between minerals and water, it is necessary to adopt very slow heating rate (0.5 - 1 C/h) to avoid any thermal pressurization. To do so, a new hollow cylinder apparatus (100 mm external diameter, 60 mm internal diameter) with lateral drainages reducing the drainage length to half the sample thickness (10 mm) has been developed (Monfared et al. 2011). The results of a drained cyclic thermal test carried out on

The effect of contaminated groundwater on tree growth: A tree-ring analysis

International Nuclear Information System (INIS)

LeBlanc, D.C.; Loehle, C.

1990-10-01

A study was conducted on the effect of contaminated groundwater seepage on tree growth downslope from F- and H-Area seepage basins of the Savannah River Site. Trees in wetlands along Four Mile Creek began to show localized stress and mortality in the late 1970s. Extreme winter temperatures and high rainfall were ruled out as potential causal factors of tree stress. Drought was shown to affect trees in both contaminated and uncontaminated zones, but trees in uncontaminated areas exhibit better recovery after drought than trees in contaminated areas. Pollution-mediated alteration of soil acidity and aluminum, sodium, and heavy metal concentrations likely acted to predispose trees to decline, with severe drought acting as the trigger for decline initiation and tree death. Thus, a moderate pollution loading, not sufficient to cause visible damage of itself, may create conditions in which sudden, severe decline could result from natural stresses. This mechanism of forest decline is common, and should be considered in evaluations of the impact of pollution on wetland forest systems. 28 refs., 4 figs., 6 tabs

Interspecific variation in tree seedlings establishment in canopy gaps in relation to tree density

Energy Technology Data Exchange (ETDEWEB)

Reader, R.J.; Bonser, S.P.; Duralia, T.E.; Bricker, B.D. [Guelph Univ., ON (Canada). Dept. of Botany

1995-10-01

We tested whether interspecific variation in tree seedling establishment in canopy gaps was significantly related to interspecific variation in tree density, for seven deciduous forest tree species (Quercus alba, Hamamelis virginiana, Acer rubrum, Sassafras albidum, Quercus rubra, Prunus serotina, Ostrya virginiana). For each species, seedling establishment was calculated as the difference in seedling density before experimental gap creation versus three years after gap creation. In each of the six experimentally-created gap types (33% or 66% removal of tree basal area from 0.01ha, 0.05ha or 0.20ha patches), differences in seedling establishment among species were significantly related to differences in their density in the tree canopy. A regression model with log{sub e} tree density as the independent variable accounted for between 93% and 98% of interspecific variation in seedling establishment. Our results provide empirical support for models of tree dynamics in gaps that assume seedling establishment depends on canopy tree density. 17 refs, 1 fig, 3 tabs

Clay Play

Science.gov (United States)

Rogers, Liz; Steffan, Dana

2009-01-01

This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

Heterogeneities in illite/smectite mixed/layers clays: some comments and recollections

International Nuclear Information System (INIS)

Johns, W.D.

1995-01-01

A review of some studies of heterogeneities, structure and surface in illite/smectite mixed-layer clays of Vienna Basin using X-ray diffraction, high resolution-transmission electron microscopy, infra-red spectroscopy, laser microprobe mass analysis, Auger electron spectroscopy, secondary ion mass spectroscopy, x-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy is given. The models of hexyl ammonium ion configuration complexed between silica sheets is discussed. 1 tab., 10 figs., 6 refs

Ball clay

Science.gov (United States)

Virta, R.L.

2001-01-01

Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

Influence of clay mineralogy on clay based ceramic products

International Nuclear Information System (INIS)

Radzali Othman; Tuan Besar Tuan Sarif; Zainal Arifin Ahmad; Ahmad Fauzi Mohd Noor; Abu Bakar Aramjat

1996-01-01

Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

The influence of clay minerals on acoustic properties of sandstones

Energy Technology Data Exchange (ETDEWEB)

Hansen, Olav

1997-12-31

This thesis aims to provide better understanding of the relationship between the acoustic properties and the petrophysical/mineralogical properties in sand-prone rock. It emphasizes the influence of clay minerals. The author develops a method to deposit clay minerals/mineral aggregates in pore space of a rigid rock framework. Kaolinite aggregates were flushed into porous permeable Bentheimer sandstone to evaluate the effect of pore filling minerals on porosity, permeability and acoustic properties. The compressional velocity was hardly affected by the clay content and it was found that the effect of minor quantities of pore filling minerals may be acoustically modelled as an ideal suspension, where the pore fluid bulk modulus is modified by the bulk modulus of the clay minerals. The influence of clays on acoustic velocities in petroleum reservoir rocks was investigated through ultrasonic measurements of compressional- and shear-waves on core material from reservoir and non-reservoir units on the Norwegian Continental Shelf. The measured velocities decrease as the porosity increases, but are not strongly dependent on the clay content. The measured velocities are less dependent on the petrophysical and lithological properties than indicated by previous authors and published mathematical models, and stiffness reduction factors are introduced in two of the models to better match the data. Velocities are estimated along the wellbores based on non-sonic well logs and reflect well the actual sonic log well measurements. In some wells the compressional velocity cannot be modelled correctly by the models suggested. Very high compressional wave anisotropy was measured in the dry samples at atmospheric conditions. As the samples were saturated, the anisotropy was reduced to a maximum of about 30% and decreases further upon pressurization. Reservoir rocks retrieved from 2500 m are more stress dependent than those retrieved from less than 200 m depth. 168 refs., 117 figs., 24

Provenance and distribution of clay minerals in the sediments of the western continental shelf and slope of India

Digital Repository Service at National Institute of Oceanography (India)

Rao, V.P.; Rao, B.R.

-Goa (93 samples) For the convenience of description, the Saurashtra-Goa region has been divided into the Saurashtra, Gulf of Cambay-Ratnagiri and Ratnagiri-Goa sectors based on variations in clay mineral abundances. The boundaries between these sectors... are approximate and variations in the mineral abundances tend to grade one to the other. Smectite is the most abundant mineral in the inner shelf sediments of all the sectors [Fig. 3(Ba), 3(Ca) and Provenance and distribution of clay minerals 1763 0 Sm*ctlt* m...

Targeted mutagenesis using zinc-finger nucleases in perennial fruit trees.

Science.gov (United States)

Peer, Reut; Rivlin, Gil; Golobovitch, Sara; Lapidot, Moshe; Gal-On, Amit; Vainstein, Alexander; Tzfira, Tzvi; Flaishman, Moshe A

2015-04-01

Targeting a gene in apple or fig with ZFN, introduced by transient or stable transformation, should allow genome editing with high precision to advance basic science and breeding programs. Genome editing is a powerful tool for precise gene manipulation in any organism; it has recently been shown to be of great value for annual plants. Classical breeding strategies using conventional cross-breeding and induced mutations have played an important role in the development of new cultivars in fruit trees. However, fruit-tree breeding is a lengthy process with many limitations. Efficient and widely applied methods for targeted modification of fruit-tree genomes are not yet available. In this study, transgenic apple and fig lines carrying a zinc-finger nuclease (ZFNs) under the control of a heat-shock promoter were developed. Editing of a mutated uidA gene, following expression of the ZFN genes by heat shock, was confirmed by GUS staining and PCR product sequencing. Finally, whole plants with a repaired uidA gene due to deletion of a stop codon were regenerated. The ZFN-mediated gene modifications were stable and passed onto regenerants from ZFN-treated tissue cultures. This is the first demonstration of efficient and precise genome editing, using ZFN at a specific genomic locus, in two different perennial fruit trees-apple and fig. We conclude that targeting a gene in apple or fig with a ZFN introduced by transient or stable transformation should allow knockout of a gene of interest. Using this technology for genome editing allows for marker gene-independent and antibiotic selection-free genome engineering with high precision in fruit trees to advance basic science as well as nontransgenic breeding programs.

Putting your sons in the right place: the spatial distribution of fig wasp offspring inside figs

NARCIS (Netherlands)

Zavodna, M.; Compton, S.G.; Biere, A.; Gilmartin, P.M.; Van Damme, J.M.M.

2005-01-01

1. Pollinating fig wasps (Hymenoptera, Agaonidae) display sex ratio adjustment, producing less female-biased combined sex ratios as the number of ovipositing females (foundresses) inside a fig increases. Because males have low mobility, the oviposition sites (galled ovules) chosen by each foundress

MixtureTree annotator: a program for automatic colorization and visual annotation of MixtureTree.

Directory of Open Access Journals (Sweden)

Shu-Chuan Chen

Full Text Available The MixtureTree Annotator, written in JAVA, allows the user to automatically color any phylogenetic tree in Newick format generated from any phylogeny reconstruction program and output the Nexus file. By providing the ability to automatically color the tree by sequence name, the MixtureTree Annotator provides a unique advantage over any other programs which perform a similar function. In addition, the MixtureTree Annotator is the only package that can efficiently annotate the output produced by MixtureTree with mutation information and coalescent time information. In order to visualize the resulting output file, a modified version of FigTree is used. Certain popular methods, which lack good built-in visualization tools, for example, MEGA, Mesquite, PHY-FI, TreeView, treeGraph and Geneious, may give results with human errors due to either manually adding colors to each node or with other limitations, for example only using color based on a number, such as branch length, or by taxonomy. In addition to allowing the user to automatically color any given Newick tree by sequence name, the MixtureTree Annotator is the only method that allows the user to automatically annotate the resulting tree created by the MixtureTree program. The MixtureTree Annotator is fast and easy-to-use, while still allowing the user full control over the coloring and annotating process.

137Cs transfer for forage to milk and its removal by clay treatment

International Nuclear Information System (INIS)

Gattavecchia, E.; Ghini, S.; Tonelli, D.

1988-01-01

Since Apr 29, 1986, the radioactive contamination resulting from the accident of the Chernobyl reactor was measured in various kinds of matrixes, primarily in Northern Italy. Transfer kinetics of 137 Cs from forage of known activity to milk was studied over a period of one year and the body Cs absorption was evaluated by measuring the percentages of Cs eliminated with milk as well as with urine and feces. Further, the decay rate of 137 Cs in milk was assessed and the results of the kinetic analysis are reported. The efficiacy of various clay materials in removing Cs from milk was also evaluated. The results of adsorption kinetics for the grey clay which resulted the most effective material are reported. (author) 3 refs.; 5 figs

User's guide for Reactor Incident Root Cause Coding Tree

International Nuclear Information System (INIS)

Busch, D.A.; Paradies, M.W.

1986-01-01

The Reactor Incident (RI) Cause Coding Tree is designed to allow identification of root causes of RI's, thereby leading to trending of useful information and developing of corrective actions to prevent recurrence. This guide explains the terminology of the RI Cause Coding Tree and how to use the tree. Using this guide for cause coding is stressed to allow consistency of coding among all RI investigators. 8 figs

Evaluation of solid waste and plastic clay mixtures for structural ceramic use; Avaliacao de misturas de residuo solido com argila plastica para aplicacao em ceramica vermelha

Energy Technology Data Exchange (ETDEWEB)

Silva, Neli Iloni Warpechowski da [Fundacao de Ciencia e Tecnologia (CIENTEC), Porto Alegre, RS (Brazil); Belo, Pedro [Ceramics Representacoes Comerciais Ltda, Porto Alegre, RS (Brazil)

1996-07-01

This work aims to verify the behaviour of the organic solid waste added by 10%, 15% and 20% in mixture in a plastic clay. It intends to emphasize the influence of the waste in the mixture. Technology tests have been carried out in the clay and mixtures to obtain possible uses in the structural ceramics. (author) 1 ref., 4 figs., 2 tabs.

Clay Houses

Science.gov (United States)

Pedro, Cathy

2011-01-01

In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

Rooting of hardwood cuttings of Roxo de Valinhos fig (Ficus carica L. with different propagation strategies

Directory of Open Access Journals (Sweden)

Gilmar Antônio Nava

2014-12-01

Full Text Available The objective of this study was to evaluate the substrate, cuttings collection time, the position and the cutting depth, and the propagation environment on rooting of 'Purple Valinhos' fig tree cuttings in Southwestern Paraná, Brazil. Two experiments were carried out at UTFPR, Câmpus Dois Vizinhos, with hardwoods cuttings from Roxo de Valinhos fig tree. The first experiment used a randomized block design, in 3 x 3 x 2 factorial (substrate x environment x collection time, with four replications of 10 cuttings per plot. The cuttings were collected in the first fifteen days of July and August. The substrates were sand, soil and the mixture of these [1:1 (v / v]. The environments used were open sky, tunnel with plastic cover and tunnel with half-shade black net cover. The second experiment used a randomized block design, 2 x 2 x 3 factorial (shoot cutting position x soil cover x shoot cutting depth, with four replications of 12 cuttings per plot. In the factor position, the vertically (0 º inclination and inclined (45 º inclination shoot cuttings were evaluated. Soil cover was tested with mulching plastic cover or not. The tested depths were 1/3, 1/2 and 2/3 in relation to the total length of the shoot cutting. In both experiments, the following were analyzed: rooting and mortality indices, number of leaves and primary shoots, length of the three largest roots per cutting. It was conclude that, the protected environment with plastic cover on sand as substrate must recommended for the rooting of fig estaca, collecting them in the first half of July. The inclination position and cutting depth of the estaca and the substrate coverage with plastic mulching did not influence the results.

The systems containing clays and clay minerals from modified drug release: a review.

Science.gov (United States)

Rodrigues, Luís Alberto de Sousa; Figueiras, Ana; Veiga, Francisco; de Freitas, Rivelilson Mendes; Nunes, Lívio César Cunha; da Silva Filho, Edson Cavalcanti; da Silva Leite, Cleide Maria

2013-03-01

Clays are materials commonly used in the pharmaceutical industry, either as ingredients or as active ingredients. It was observed that when they are administered concurrently, they may interact with drugs reducing their absorption. Therefore, such interactions can be used to achieve technological and biopharmaceutical advantages, regarding the control of release. This review summarizes bibliographic (articles) and technological (patents) information on the use of systems containing clays and clay minerals in modified drug delivery. In this area, formulations such natural clay, commercial clay, synthetic clay, composites clay-polymers, nanocomposites clay-polymers, films and hidrogels composites clay-polymers are used to slow/extend or vectorize the release of drugs and consequently they increase their bioavailability. Finally, this review summarizes the fields of technology and biopharmaceutical applications, where clays are applied. Copyright © 2012 Elsevier B.V. All rights reserved.

Modelling of radionuclide migration and heat transport from an High-Level-Radioactive-Waste-repository (HLW) in Boom clay

International Nuclear Information System (INIS)

Put, M.; Henrion, P.

1992-01-01

For the modelling of the migration of radionuclides in the Boom clay formation, the analytical code MICOF has been updated with a 3-dimensional analytical solution for discrete sources. the MICOF program is used for the calculation of the release of α and β emitters from the HIGH LEVEL RADIOACTIVE WASTES (HLW). A coherent conceptual model is developed which describes all the major physico-chemical phenomena influencing the migration of radionuclides in the Boom clay. The concept of the diffusion accessible porosity is introduced and included in the MICOF code. Different types of migration experiments are described with their advantages and disadvantages. The thermal impact of the HLW disposal in the stratified Boom clay formation has been evaluated by a finite element simulation of the coupled heat and mass transport equation. The results of the simulations show that under certain conditions thermal convection cells may form, but the convective heat transfer in the clay formation is negligible. 6 refs., 19 figs., 2 tabs., 5 appendices

Natural attenuation of diesel fuel in heavy clay soil

International Nuclear Information System (INIS)

Berry, K.A.T.; Burton, D.L.

1997-01-01

The application of bioremediation techniques on heavy clay soils contaminated with diesel fuels was studied. Earlier studies suggested that in-situ bioreclamation was only effective on permeable soils such as medium- to coarse-textured sandy or loamy soils. It was assumed that heavy clay soils such as those found in the Red River Valley in Southern Manitoba had physical and chemical properties that would limit the usefulness of natural attenuation. In this study, the disappearance and the natural attenuation of diesel fuel added to soil at a rate of 5000 mg/kg soil in tilled and untilled heavy clay soil was monitored. Three methods of analysis were used: (1) oil and grease content, (2) extractable organics, and (3) the Millipore EnviroGard ELISA method for petroleum hydrocarbons. Effects of the contamination on the soil microbial population were measured using surface CO 2 flux measurements and microbial biomass carbon analysis. Soil moisture contents at all sample times were between 44 and 49 per cent. Soil temperature was also monitored. All three analytical methods used in the study showed the near-complete disappearance of detectable diesel fuel hydrocarbons from the soil after 30 days with half-lives ranging from 11 to 26 days. The advantages and limitations of the ELISA kit were described. No hydrocarbons were detected in the groundwater sample. 45 refs., 7 tabs., 2 figs

/sup 137/Cs transfer for forage to milk and its removal by clay treatment

Energy Technology Data Exchange (ETDEWEB)

Gattavecchia, E; Ghini, S; Tonelli, D

1988-03-01

Since Apr 29, 1986, the radioactive contamination resulting from the accident of the Chernobyl reactor was measured in various kinds of matrixes, primarily in Northern Italy. Transfer kinetics of /sup 137/Cs from forage of known activity to milk was studied over a period of one year and the body Cs absorption was evaluated by measuring the percentages of Cs eliminated with milk as well as with urine and feces. Further, the decay rate of /sup 137/Cs in milk was assessed and the results of the kinetic analysis are reported. The efficiacy of various clay materials in removing Cs from milk was also evaluated. The results of adsorption kinetics for the grey clay which resulted the most effective material are reported. (author) 3 refs.; 5 figs.

A Visual Basic program to classify sediments based on gravel-sand-silt-clay ratios

Science.gov (United States)

Poppe, L.J.; Eliason, A.H.; Hastings, M.E.

2003-01-01

Nomenclature describing size distributions is important to geologists because grain size is the most basic attribute of sediments. Traditionally, geologists have divided sediments into four size fractions that include gravel, sand, silt, and clay, and classified these sediments based on ratios of the various proportions of the fractions. Definitions of these fractions have long been standardized to the grade scale described by Wentworth (1922), and two main classification schemes have been adopted to describe the approximate relationship between the size fractions.Specifically, according to the Wentworth grade scale gravel-sized particles have a nominal diameter of ⩾2.0 mm; sand-sized particles have nominal diameters from <2.0 mm to ⩾62.5 μm; silt-sized particles have nominal diameters from <62.5 to ⩾4.0 μm; and clay is <4.0 μm. As for sediment classification, most sedimentologists use one of the systems described either by Shepard (1954) or Folk (1954, 1974). The original scheme devised by Shepard (1954) utilized a single ternary diagram with sand, silt, and clay in the corners to graphically show the relative proportions among these three grades within a sample. This scheme, however, does not allow for sediments with significant amounts of gravel. Therefore, Shepard's classification scheme (Fig. 1) was subsequently modified by the addition of a second ternary diagram to account for the gravel fraction (Schlee, 1973). The system devised by Folk (1954, 1974) is also based on two triangular diagrams (Fig. 2), but it has 23 major categories, and uses the term mud (defined as silt plus clay). The patterns within the triangles of both systems differ, as does the emphasis placed on gravel. For example, in the system described by Shepard, gravelly sediments have more than 10% gravel; in Folk's system, slightly gravelly sediments have as little as 0.01% gravel. Folk's classification scheme stresses gravel because its concentration is a function of

Study of delayed behaviour of clays in deep geologic formations

International Nuclear Information System (INIS)

Rousset, G.; Bazargan, B.; Ouvry, J.F.; Bouilleau, M.

1993-01-01

This study is a cost-sharing contract with the European Atomic Energy Community within the framework of Research and Development Program on Management, Storage and Radioactive Waste Disposal. The aim of the work presented in this report is to study the time-dependent behaviour of deep clays in Laboratory or in situ, by means of tests of similar geometry, in order to get easy comparisons and to study scale effect. The cylindrical geometry has been chosen as it resembles in situ works (tunnels, galleries) more closely. The first part of the study concerns a new test on hollow-cylinder. The experimental system, set up specially for this study, has allowed to conduct experiments in which 3 loading parameters may be controlled independently. Different types of experiments can therefore be conducted to study various aspects of mechanical behavior of rocks. A comprehensive experimental program was conducted in the particular case of Boom clay. In the second part of the report devoted to in situ creep or relaxation dilatometer tests, by using new techniques or loading paths, it was shown that time-dependent convergence of boreholes can reach significant values, and is dependent on the direction of the borehole. The anisotropy of the initial state of stress was also put in evidence. The proposed constitutive model (part III) appears to be very suitable to explain the behavior of the Boom clay, in view of the experimental results. In particular, the scale effect is low for Boom clay. 15 refs., 58 figs., 10 tabs

Geochemical of clay formations : study of Spanish clay REFERENCE

International Nuclear Information System (INIS)

Turrero, M. J.; Pena, J.

2003-01-01

Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, considerable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processes controlling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R and D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

TREE2FASTA: a flexible Perl script for batch extraction of FASTA sequences from exploratory phylogenetic trees.

Science.gov (United States)

Sauvage, Thomas; Plouviez, Sophie; Schmidt, William E; Fredericq, Suzanne

2018-03-05

The body of DNA sequence data lacking taxonomically informative sequence headers is rapidly growing in user and public databases (e.g. sequences lacking identification and contaminants). In the context of systematics studies, sorting such sequence data for taxonomic curation and/or molecular diversity characterization (e.g. crypticism) often requires the building of exploratory phylogenetic trees with reference taxa. The subsequent step of segregating DNA sequences of interest based on observed topological relationships can represent a challenging task, especially for large datasets. We have written TREE2FASTA, a Perl script that enables and expedites the sorting of FASTA-formatted sequence data from exploratory phylogenetic trees. TREE2FASTA takes advantage of the interactive, rapid point-and-click color selection and/or annotations of tree leaves in the popular Java tree-viewer FigTree to segregate groups of FASTA sequences of interest to separate files. TREE2FASTA allows for both simple and nested segregation designs to facilitate the simultaneous preparation of multiple data sets that may overlap in sequence content.

All rights reserved and www.bioline.org.br/ja Assessment of Tree ...

African Journals Online (AJOL)

PROF HORSFALL

recent times, thereby posing appreciable risk of local extinction to some ... Fig 1: Map showing study area; fresh and mangrove swamp of. University of Lagos .... African oil palm. 43. 10. 29. ... Brazilian rose tree, blue trumpet tree. 52. 13. 41.

Design study for a macropermeability test in an argillaceous formation (Boom clay)

International Nuclear Information System (INIS)

Bronders, J.

1992-01-01

In the present report a test design has been developed for determining the in-situ permeability of the Boom clay on a large scale at the Mol site (Belgium). Since in the Boom clay at the Mol site an Underground Repository Facility (URF) is operational the test has been designed to be run in or from this facility. The proposal is an in-situ macropermeability test with a set-up comprising a central borehole (metric scale in length) designed to allow various types of control of the water-level, surrounded by a lattice of piezometers installed in the clay mass for the monitoring of the interstitial water pressure changes in function of the various water-level controls. In one part the report describes the potential set-ups and a theoretical background as far as it can be done on the basis of existing literature and experiments. In a second part the method (technical and practical data of a test set-up) is described and documented. The method proposed is largely based on the several years of expertise gained within the field of in-situ migration and hydrogeologic investigations in the Hades-URF. 14 refs., 9 figs., 2 tabs

Understory vegetation in fast-growing tree plantations on savanna soils in Congo

OpenAIRE

Loumeto, J.J.; Huttel, Charles

1997-01-01

The hypothesis that tree plantations may catalyze the regeneration of natural forest biodiversity was tested through studies of floristic diversity and structure in fast-growing tree plantations in the Congo. Study sites included experimental and industrial plantations on poor sandy coastal soils near Pointe-Noire, and experimental plantations on clay soils near Loudima. The effects of plantations species, plantation age (in 6- to 20-year-old eucalypt stands), disturbance due to herbicide use...

Atmospheric carbon reduction by urban trees

International Nuclear Information System (INIS)

Nowak, D.J.

1993-01-01

Trees, because they sequester atmospheric carbon through their growth process and conserve energy in urban areas, have been suggested as one means to combat increasing levels of atmospheric carbon. Analysis of the urban forest in Oakland, California (21% tree cover), reveals a tree carbon storage level of 11·0 metric tons/hectare. Trees in the area of the 1991 fire in Oakland stored approximately 14,500 metric tons of carbon, 10% of the total amount stored by Oakland's urban forest. National urban forest carbon storage in the United States (28% tree cover) is estimated at between 350 and 750 million metric tons. Establishment of 10 million urban trees annually over the next 10 years is estimated to sequester and offset the production of 363 million metric tons of carbon over the next 50 years-less than 1% of the estimated carbon emissions in the United States over the same time period. Advantages and limitations of managing urban trees to reduce atmospheric carbon are discussed. 36 refs., 2 figs., 3 tabs

Expression and evolutionary divergence of the non-conventional olfactory receptor in four species of fig wasp associated with one species of fig

Directory of Open Access Journals (Sweden)

Xiao Jinhua

2009-02-01

Full Text Available Abstract Background The interactions of fig wasps and their host figs provide a model for investigating co-evolution. Fig wasps have specialized morphological characters and lifestyles thought to be adaptations to living in the fig's syconium. Although these aspects of natural history are well documented, the genetic mechanism(s underlying these changes remain(s unknown. Fig wasp olfaction is the key to host-specificity. The Or83b gene class, an unusual member of olfactory receptor family, plays a critical role in enabling the function of conventional olfactory receptors. Four Or83b orthologous genes from one pollinator (PFW (Ceratosolen solmsi and three non-pollinator fig wasps (NPFWs (Apocrypta bakeri, Philotrypesis pilosa and Philotrypesis sp. associated with one species of fig (Ficus hispida can be used to better understand the molecular mechanism underlying the fig wasp's adaptation to its host. We made a comparison of spatial tissue-specific expression patterns and substitution rates of one orthologous gene in these fig wasps and sought evidence for selection pressures. Results A newly identified Or83b orthologous gene was named Or2. Expressions of Or2 were restricted to the heads of all wingless male fig wasps, which usually live in the dark cavity of a fig throughout their life cycle. However, expressions were widely detected in the antennae, legs and abdomens of all female fig wasps that fly from one fig to another for oviposition, and secondarily pollination. Weak expression was also observed in the thorax of PFWs. Compared with NPFWs, the Or2 gene in C. solmsi had an elevated rate of substitutions and lower codon usage. Analyses using Tajima's D, Fu and Li's D* and F* tests indicated a non-neutral pattern of nucleotide variation in all fig wasps. Unlike in NPFWs, this non-neutral pattern was also observed for synonymous sites of Or2 within PFWs. Conclusion The sex- and species-specific expression patterns of Or2 genes detected beyond

Radionuclide release from high level waste forms under repository conditions in clay or granite

International Nuclear Information System (INIS)

Godon, N.; Lanza, F.

1990-01-01

The behaviour of both fully active and simulated vitrified high level waste (HLW) has been studied under conditions that are likely to occur in future repositories in clay and granite. The simulated HLW was doped with Cs, Sr, Tc and the actinides and the leaching of these elements from the glass has been measured together with their concentrations in the water of the near-field and their distribution between the various components of the repository. The diffusion coefficients of several elements in Boom clay has also been measured. The results show that the concentrations of Tc and the actinides in the near-field of a repository will be very low and that the actinides will only diffuse very slowly away from the vicinity of the glass. 24 refs., 1 figs., 7 tabs

Sorption/desorption of Cs on clay and soil fractions from various regions of Turkey

International Nuclear Information System (INIS)

Erten, H.N.

1988-01-01

The sorption/desorption behaviour of Cs ion in the concentration region of 10 -8 to 10 -4 meqml -1 have been studied using clay and soil fractions from various regions of Turkey. The sorption curves for all the material studied show similar behaviour indicating at least two different sorption processes. One with high and the other with low distribution coefficients. The results of desorption studies indicate that Cs cation is to a large extent attached to the solid material in a reversible manner. The adsorption isotherms were found to be nonlinear in all cases. The increase of R D values with decreasing particle size in most cases, suggests that sorption and/or exchange is primarily a surface phenomenon in the clay and soil fractions studied. 14 figs.; 4 tabs

Comprehensive review of geosynthetic clay liner and compacted clay liner

Science.gov (United States)

Shankar, M. Uma; Muthukumar, M.

2017-11-01

Human activity inevitably produces waste materials that must be managed. Some waste can be reused. However many wastes that cannot be used beneficially must be disposed of ensuring environmental safety. One of the common methods of disposal is landfilling. The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Liner in a landfill is an important component which prevent leachate migration and prevent groundwater contamination. Earthen liners have been widely used to contain waste materials in landfill. Liners and covers for municipal and hazardous waste containment facilities are often constructed with the use of fine-grained, low plasticity soils. Because of low permeability geosynthetic clay liners and compacted clay liners are the main materials used in waste disposal landfills. This paper summaries the important geotechnical characteristics such as hydraulic conductivity, liquid limit and free swell index of geosynthetic clay liner and compacted clay liner based on research findings. This paper also compares geosynthetic clay liner and compacted clay liner based on certain criteria such as thickness, availability of materials, vulnerability to damage etc.

Estimation of bitumen and clay content in fine tailings

International Nuclear Information System (INIS)

Motta Cabrera, S.C.; Bryan, J.; Kantzas, A.

2007-01-01

Fine tailings are the components of tailings ponds and the by-product of the oil sand extraction process, consisting mostly of water with small amounts of bitumen, sand, silts and clays. Because of the large volumes of tailings, an important environmental and production process issue involves the reduction of the remaining bitumen in the tailings stream. This paper presented the results of a study that used low field nuclear magnetic resonance (NMR) in order to estimate the bitumen, clay and water content of synthetic tailings samples. NMR is a non-destructive technique that is utilized to determine compositions of oil and brine emulsions and the viscosity of heavy oil and bitumen as well as in reservoir characterization, measuring properties such as permeability, porosity, mobile and immobile fluids, and fluid saturations. The study prepared and tested numerous samples with variable water, bitumen, sand and clay concentrations in the NMR tool under ambient conditions. Two qualities of water and bitumen were used to prepare the synthetic samples. Each type of water and bitumen was analyzed as a single substance and in a mixture with the typical solids found in tailings composition. These included kaolinite, illite, sodium montmorillonite and sand. These synthetic samples were analyzed using different mixing configurations, as a function of time and in two different NMR tools. It was concluded that NMR is a potential application for on-line determination of tailings streams composition. 18 refs., 3 tabs., 17 figs

Clay dispersibility and soil friability – testing the soil clay-to-carbon saturation concept

OpenAIRE

Schjønning, P.; de Jonge, L.W.; Munkholm, L.J.; Moldrup, P.; Christensen, B.T.; Olesen, J.E.

2011-01-01

Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC as a predictor of clay dispersibility and soil friability. Soil was sampled three years in a field varying in clay content (~100 to ~220 g kg-1 soil) and grown with different crop rotations. Clay ...

Distribution of clay minerals in the process streams produced by the extraction of bitumen from Athabasca oil sands

Energy Technology Data Exchange (ETDEWEB)

Kaminsky, H.A.W.; Etsell, T.H.; Ivey, D.G. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering; Omotoso, O. [Natural Resources Canada, Devon, AB (Canada). CETC

2009-02-15

The clay minerals present in the oil sands were studied with particular reference to how they are partitioned in bitumen ore during the extraction process. Bitumen production from surface-mined oil sands accounts for nearly two-thirds of the total bitumen production in Alberta. Every cubic meter of mined ore results in 1.3 cubic meters of mature fine tailings (MFT). The characteristic differences between the clay minerals that report to the froth versus the tailings streams were also examined to determine which minerals could impact different unit operations in the bitumen extraction process. X-ray diffraction and random powder samples were used to quantify the clay minerals. Particle size distribution and clay activity balances were also conducted. The degree of partitioning during the conditioning and flotation stages in a batch extractor was determined by the surface properties of the clay minerals. The water-continuous tailings stream was separated into fine and coarse tailings fractions through sedimentation. The study showed that bitumen-clay interactions may be dominated by kaolinite or iron oxides. Clays are responsible for the poor settling behaviour of MFTs. The clay minerals present in the oil sands include illite, illite-smectite, kaolinite, kaolinite-smectite, and chlorite. The close proximity of the tailings ponds to the Athabasca River and volatile organic compounds (VOCs) emission require that the ponds be reclaimed to a natural landscape before mine closure. In addition to its impact on fine tailings reclamation, clay mineralogy plays a role in extraction froth flotation and emulsion stability during froth treatment. The mineralogy of the froth solids was found to be different from the mineralogy of the middlings and tailings solids. 39 refs., 6 tabs., 6 figs.

Fog and Rain Water Collection from Trees in the Dhofar Region in the Sultanate of Oman

Directory of Open Access Journals (Sweden)

S. A. Abdul-Wahab

2009-06-01

Full Text Available This work had two purposes. The first was to measure and investigate the amount of fog and rain water collected by a sample of trees during the summer monsoon season in the mountains of the Dhofar region in the south of Oman. The second purpose was to assess the potential of trees with different leaf shapes, sizes and cross sectional canopy areas to collect fog and rain water in the area. In order to meet these purposes three different tree species, were selected for experimental investigation and field measurements. They included fig, lemon, and tamarind trees. The experiments were designed and implemented in the monsoon season of 2006, between the 13th of July and the 3rd of September. The daily measurements of water collection showed that the three species of tree have different water collection capacities. It was found that the fig tree collected the least water. The fog water collection of the fig tree over a period of 47 days between the 13th of July and the 3rd of September was 140.5 L/m2, or an average of 2.7 L/m2/d. The fog water collection of the lemon tree was 243.0 L/m2, or an average of 4.4 L/m2/d. In terms of potential collection of the tamarind tree, the results showed that it collected a fog water of 218.9 L/m2, or an average of 4.3 L/m2/d over the same period. The study contributes to the knowledge of how different tree species collect fog and rain water, and concludes with a set of recommendations.

Purification and autolysis of the ficin isoforms from fig (Ficus carica cv. Sabz) latex.

Science.gov (United States)

Zare, Hamid; Moosavi-Movahedi, Ali Akbar; Salami, Maryam; Mirzaei, Morteza; Saboury, Ali Akbar; Sheibani, Nader

2013-03-01

Ficin (EC 3.4.22.3), a cysteine endoproteolytic protease in fig trees' latex, has multiple isoforms. Until now, no data on autolysis of individual ficins (ficin isoforms) are available. Following purification, ficins' autolysis was determined by HPLC chromatogram changes and ultrafiltrations at different temperatures and storage times. These results showed that the number of HPLC peaks in latex proteins purification of Ficus carica cv. Sabz varied from previous fig varieties or cultivars. Proteolytic activity of ficins was inhibited by specific cysteine protease inhibitors, confirming the participation of the cysteine residue in the active site. The zeta potential of the first two eluted peaks (I and II) was negative, while that of other peaks were positive. All ficins were susceptible to autolysis when stored at high temperatures. In contrast, only the last two ficins (B, C) were prone to autolysis at cold temperature after long storage period. The rate of degradation of the ficins was significantly increased with the increased storage time. The ficin (A) related to peak (III) had the highest and the lowest surface hydrophobic patches and ratio of autolytic to proteolytic activity, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

Science.gov (United States)

Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

2003-03-01

Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

International Nuclear Information System (INIS)

Chaudhary, D.S.; Prasad, R.; Gupta, R.K.; Bhattacharya, S.N.

2005-01-01

Various polymer clay nanocomposites (PCNs) were prepared from ethylene vinyl acetate copolymer (EVA) with 9, 18 and 28% vinyl acetate (VA) content filled with different wt.% (2.5, 5 and 7.5) of a Montmorillonite-based organo-modified clay (Cloisite[reg] C15A and C30B). The PCNs were prepared using melt blending techniques. Morphological information regarding intercalation and exfoliation were determined by using wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). WAXS and TEM confirmed that increasing the VA content was necessary to achieve greater clay-polymer interaction as seen from the comparatively higher intercalation of clay platelets with 28% VA. The effect of addition of clay on the development and the modification of crystalline morphology in EVA matrix was also studied using WAXS and temperature-modulated differential scanning calorimetry (MDSC). Results are presented showing that the addition of clay platelets does not increase the matrix crystallinity but the morphology was significantly modified such that there was an increase in the 'rigid' amorphous phase. Mechanical properties were also evaluated against the respective morphological information for each specimen and there are indications that the level of clay-polymer interaction plays a significant role in such morphological modification, and in such a way that affects the final PCN mechanical properties which has wide and significant applications in the packaging industries

Fourier analysis on trees as related to p-adic string theory

International Nuclear Information System (INIS)

O'Loughlin, M.; Joshi, G.

1989-01-01

After reviewing p-adic numbers, their relationship to trees, and some recent proposals for actions of a p-adic string theory with a tree-like world sheet, the possibility of constructing p-adic vertex operators in a similar way to the Frenkel-Kac construction of Kac-Moody algebras, is investigated. 25 refs., 5 figs

Clay Dispersibility and Soil Friability-Testing the Soil Clay-to-Carbon Saturation Concept

DEFF Research Database (Denmark)

Schjønning, Per; de Jonge, Lis Wollesen; Munkholm, Lars Juhl

2012-01-01

Soil organic carbon (OC) influences clay dispersibility, which affects soil tilth conditions and the risk of vertical migration of clay colloids. No universal lower threshold of OC has been identified for satisfactory stabilization of soil structure. We tested the concept of clay saturation with OC...... as a predictor of clay dispersibility and soil friability. Soil was sampled 3 yr in a field varying in clay content (∼100 to ∼220 g kg−1 soil) and grown with different crop rotations. Clay dispersibility was measured after end-over-end shaking of field-moist soil and 1- to 2-mm sized aggregates either air......-dried or rewetted to −100 hPa matric potential. Tensile strength of 1- to 2-, 2- to 4-, 4- to 8-, and 8- to 16-mm air-dried aggregates was calculated from their compressive strength, and soil friability estimated from the strength–volume relation. Crop rotation characteristics gave only minor effects on clay...

SBR Brazilian organophilic/clay nanocomposites

International Nuclear Information System (INIS)

Guimaraes, Thiago R.; Valenzuela-Diaz, Francisco R.; Morales, Ana Rita; Paiva, Lucilene B.

2009-01-01

The aim of this work is the obtaining of SBR composites using a Brazilian raw bentonite and the same bentonite treated with an organic salt. The clays were characterized by XRD. The clay addition in the composites was 10 pcr. The composites were characterized by XRD and had measured theirs tension strength (TS). The composite with Brazilian treated clay showed TS 233% higher than a composite with no clay, 133% higher than a composite with Cloisite 30B organophilic clay and 17% lower than a composite with Cloisite 20 A organophilic clay. XRD and TS data evidence that the composite with Brazilian treated clay is an intercalated nanocomposite. (author)

Atrazine biodegradation modulated by clays and clay/humic acid complexes

International Nuclear Information System (INIS)

Besse-Hoggan, Pascale; Alekseeva, Tatiana; Sancelme, Martine; Delort, Anne-Marie; Forano, Claude

2009-01-01

The fate of pesticides in the environment is strongly related to the soil sorption processes that control not only their transfer but also their bioavailability. Cationic (Ca-bentonite) and anionic (Layered Double Hydroxide) clays behave towards the ionisable pesticide atrazine (AT) sorption with opposite tendencies: a noticeable sorption capacity for the first whereas the highly hydrophilic LDH showed no interactions with AT. These clays were modified with different humic acid (HA) contents. HA sorbed on the clay surface and increased AT interactions. The sorption effect on AT biodegradation and on its metabolite formation was studied with Pseudomonas sp. ADP. The biodegradation rate was greatly modulated by the material's sorption capacity and was clearly limited by the desorption rate. More surprisingly, it increased dramatically with LDH. Adsorption of bacterial cells on clay particles facilitates the degradation of non-sorbed chemical, and should be considered for predicting pesticide fate in the environment. - The biodegradation rate of atrazine was greatly modulated by adsorption of the pesticide and also bacterial cells on clay particles.

Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

Science.gov (United States)

Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

2017-08-11

Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

Effects of ionizing radiation on the boreal forest: Canada's FIG experiment, with implications for radionuclides

International Nuclear Information System (INIS)

Amiro, B.D.; Sheppard, S.C.

1994-01-01

The Field-Irradiator Gamma (FIG) experiment chronically irradiated a section of the Canadian boreal forest over a period of 14 years. Forest trees were affected at dose rates >0.1 mGy·h -1 , but a berbaceous plant community thrived at dose rates up to 65 mGy·h -1 . Irradiation resulted in the establishment of four zones of vegetation: a herbaceous community, a shrub community, a narrow zone of dying trees, and a zone with no apparent impacts. Concentrations of 14 C, 99 Tc, 129 I, 137 Cs and 226 Ra that could cause a dose rate of 0.1 mGy·h -1 within vegetation were calculated. Chemical toxic effects on plants would be caused by 99 Tc and 129 I before radiological effects are predicted to occur. The calculated 226 Ra concentration is about a factor of 10 greater than that measured at some natural sites. Sufficiently high concentrations of 14 C and 137 Cs to cause an impact are unlikely unless a site is severely contaminated. (author)

Physical-chemical characteristics of figs (Ficus carica) preready to submitted to ionizing radiation

International Nuclear Information System (INIS)

Silva, Lucia C.A.S.; Harder, Marcia N.C.; Arthur, Paula B.; Lima, Roberta B.; Modlo, Debora M.; Arthur, Valter

2009-01-01

Fig (Ficus carica) is the fruit of the fig tree, original of Mediterranean, has fleshy and succulent pulp, besides being sweetened slightly. It is very appreciated for dessert. The immature form (green) can be used for make a sweet home-made. The aim of the present work was irradiate samples of fruits of pre-ready green fig, seeking the increase of the useful shelf-life. The samples were washed, made hygienic and submitted the cooking by a period of 15 minutes, after the cooking they were put in an drainer to expect cooling the fruits and after that process they were wrapped in plastic sack of 15x30cm and sealed in a manual sealing and stored at 8 deg C in a OBD camera for 7 days. Later samples were irradiated with doses of: 0 (control); 1.0 and 2.0 kGy, under a rate of dose of 0.601 kGy/h, in a Gammacell-220 irradiator and stored by 24 hours to 8 deg C in OBD. Each treatment was consisted with 3 repetitions with 10 fruits each. The samples were appraised, immediately after the irradiation, as for the parameters pH, soluble solids content, color peel, color pulp, texture, chlorophyll A, chlorophyll B and total carotenoids. The statistical analysis of the results was accomplished, through outline entirely randomized by test F for variance analysis and when significant compared by Tuckey test. By the obtained results was concluded that there was not significant difference between the treatments and the control. After four days the samples presented microbiological contamination, they went desecrated. (author)

Phosphonium modified clay/polyimide nanocomposites

International Nuclear Information System (INIS)

Ceylan, Hatice; Çakmakçi, Emrah; Beyler-Çiǧil, Asli; Kahraman, Memet Vezir

2014-01-01

In this study, octyltriphenylphosphonium bromide [OTPP-Br] was prepared from the reaction of triphenylphosphine and 1 -bromooctane. The modification of clay was done by ion exchange reaction using OTPP-Br in water medium. Poly(amic acid) was prepared from the reaction of 3,3',4,4'-Benzophenonetetracarboxylic dianhydride (BTDA) and 4,4'-Oxydianiline (ODA). Polyimide(PI)/clay hybrids were prepared by blending of poly(amic acid) and organically modified clay as a type of layered clays. The morphology of the Polyimide/ phosphonium modified clay hybrids was characterized by scanning electron microscopy (SEM). Chemical structures of polyimide and Polyimide/ phosphonium modified clay hybrids were characterized by FTIR. SEM and FTIR results showed that the Polyimide/ phosphonium modified clay hybrids were successfully prepared. Thermal properties of the Polyimide/ phosphonium modified clay hybrids were characterized by thermogravimetric analysis (TGA)

Common clay and shale

Science.gov (United States)

Virta, R.L.

2000-01-01

Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

Effects of modified Clay on the morphology and thermal stability of PMMA/clay nanocomposites

International Nuclear Information System (INIS)

Tsai, Tsung-Yen; Lin, Mei-Ju; Chuang, Yi-Chen; Chou, Po-Chiang

2013-01-01

The potential to improve the mechanical, thermal, and optical properties of poly(methyl methacrylate) (PMMA)/clay nanocomposites prepared with clay containing an organic modifier was investigated. Pristine sodium montmorillonite clay was modified using cocoamphodipropionate, which absorbs UVB in the 280–320 nm range, via ion exchange to enhance the compatibility between the clay platelets and the methyl methacrylate polymer matrix. PMMA/clay nanocomposites were synthesized via in situ free-radical polymerization. Three types of clay with various cation-exchange capacities (CEC) were used as inorganic layered materials in these organic–inorganic hybrid nanocomposites: CL42, CL120, and CL88 with CEC values of 116, 168, and 200 meq/100 g of clay, respectively. We characterized the effects of the organoclay dispersion on UV resistance, effectiveness as an O 2 gas barrier, thermal stability, and mechanical properties of PMMA/clay nanocomposites. Gas permeability analysis demonstrated the excellent gas barrier properties of the nanocomposites, consistent with the intercalated or exfoliated morphologies observed. The optical properties were assessed using UV–Visible spectroscopy, which revealed that these materials have good optical clarity, UV resistance, and scratch resistance. The effect of the dispersion capability of organoclay on the thermal properties of PMMA/clay nanocomposites was investigated by thermogravimetric analysis and differential scanning calorimetry; these analyses revealed excellent thermal stability of some of the modified clay nanocomposites. - Highlights: ► We control the dispersion morphology by protonation of K2 into the clay. ► The CL120 and CL88, with the higher CEC, are more random intercalated by K2. ► We report these materials have good optical clarity, and UV resistance

Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

Science.gov (United States)

Miller, Sandi G (Inventor)

2013-01-01

A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

Clay nanoparticles for regenerative medicine and biomaterial design: A review of clay bioactivity.

Science.gov (United States)

Mousa, Mohamed; Evans, Nicholas D; Oreffo, Richard O C; Dawson, Jonathan I

2018-03-01

Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

Study of adsorption of Phenanthrene on Different Types of Clay Minerals; Estudio de Adsorcion de Fenentreno en Diferentes Tipos de Arcillas

Energy Technology Data Exchange (ETDEWEB)

Contreras, M L; Escolano, O; Rodriguez, V; Diaz, F J; Perez, R; Garcia, S; Garcia Frutos, F J

2003-07-01

The fate and behaviour of non-ionic hydrophobic organic compounds in deep soil is mainly controlled by the mineral fraction present in the soil due to the very low organic carbon content of the deep soil. The mineral fraction that may greatly influence the fate and transport of these compounds due to its presence and properties are the clay minerals. Clay mineral also become increasingly important in low organic matter content soils. There tree, studies of non-ionic hydrophobic organic compounds adsorption on clay minerals without organic matter are necessary lo better understand the fate and transport of these compounds. In this work we used phenanthrene as model compound of non-ionic hydrophobic organic compound and four pure clay minerals: kaolinite, illite, montmorillonite, and vermiculite including muscovite mica. These clays minerals are selected due to its abundance in represent ve Spanish soils and different properties as its structural layers and expanding capacity. Batch experiments were performed using phenanthrene aqueous solutions and the clays selected. Phenanthrene sorption isotherms for all clays, except muscovite mica, were best described by the Freundlich model. Physical sorption on the external surfaces is the most probable adsorption mechanisms. In this sense, the presence of non-polar nano-sites on clay surfaces could determine the adsorption of phenanthrene by hydrophobic interaction on these sites. (Author) 22 refs.

Thixotropic Properties of Latvian Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Ruplis, Augusts

2015-01-01

This research studies Latvia originated Devon (Tūja, Skaņkalne), quaternary (Ceplīši), Jurassic, (Strēļi) and Triassic (Vadakste) deposit clays as well as Lithuania originated Triassic (Akmene) deposit clays. Thixotropic properties of clay were researched by measuring relative viscosity of clay in water suspensions. Relative viscosity is measured with a hopper method. It was detected that, when concentration of suspension is increased, clay suspension’s viscosity also increases. It happens un...

Physical and chemical parameters acquisition in situ, in deep clay. Development of sampling and testing methods

International Nuclear Information System (INIS)

Lajudie, A.; Coulon, H.; Geneste, P.

1991-01-01

Knowledge of deep formation for radioactive waste disposal requires field-tests or bench-scale experiments on samples of the site material. In the case of clay massifs the taking of cores and the sampling of these are particularly difficult. The most suitable materials and techniques were selected from a study of clay colling and conservation methods. These were used for a series of core samples taken at Mol in Belgium. Subsequently permeability measurements were carried out in laboratory on samples from vertical drilling and compared with in situ measurements. The latter were made by horizontal drillings from the shaft excavation of the underground facility HADES at Mol. There is a good overall agreement between the results of the two types of measurements. 25 figs.; 4 tabs.; 12 refs.; 16 photos

Specific attraction of fig-pollinating wasps: role of volatile compounds released by tropical figs.

Science.gov (United States)

Grison-Pigé, Laure; Bessière, Jean-Marie; Hossaert-McKey, Martine

2002-02-01

Floral scents often act as pollinator attractants. In the case of obligate and specific plant-pollinator relationships, the role of floral signals may be crucial in allowing the encounter of the partners. About 750 Ficus species (Moraceae) are involved in such interactions, each with a distinct species of pollinating wasp (Chalcidoidea, Agaonidae). Several species have been shown to release volatile compounds, but their role in pollinator attraction has rarely been simultaneously tested. We investigated the floral scents of four tropical fig species and combined chemical analysis with biological tests of stimulation of insects. Pollinators of three species were stimulated by the odor of their associated fig species and generally not by the odor of another species. The fourth actually comprised two distinct varieties. The main compound was often a different one in each species. Floral blends of different species always shared compounds, but ratios of these compounds varied among species.

Clay minerals behaviour in thin sandy clay-rich lacustrine turbidites (Lake Hazar, Turkey)

Science.gov (United States)

El Ouahabi, Meriam; Hubert-Ferrari, Aurelia; Lamair, Laura; Hage, Sophie

2017-04-01

Turbidites have been extensively studied in many different areas using cores or outcrop, which represent only an integrated snapshot of a dynamic evolving flow. Laboratory experiments provide the missing relationships between the flow characteristics and their deposits. In particular, flume experiments emphasize that the presence of clay plays a key role in turbidity current dynamics. Clay fraction, in small amount, provides cohesive strength to sediment mixtures and can damp turbulence. However, the degree of flocculation is dependent on factors such as the amount and size of clay particles, the surface of clay particles, chemistry and pH conditions in which the clay particles are dispersed. The present study focuses on thin clayey sand turbidites found in Lake Hazar (Turkey) occurring in stacked thin beds. Depositional processes and sources have been previously studied and three types were deciphered, including laminar flows dominated by cohesion, transitional, and turbulence flow regimes (Hage et al., in revision). For the purpose of determine the clay behavior in the three flow regimes, clay mineralogical, geochemical measurements on the cores allow characterising the turbidites. SEM observations provide further information regarding the morphology of clay minerals and other clasts. The study is particularly relevant given the highly alkaline and saline water of the Hazar Lake. Clay minerals in Hazar Lake sediments include kaolinite (1:1-type), illite and chlorite (2:1-type). Hazar lake water is alkaline having pH around 9.3, in such alkaline environment, a cation-exchange reaction takes place. Furthermore, in saline water (16‰), salts can act as a shield and decrease the repulsive forces between clay particle surfaces. So, pH and salt content jointly impact the behaviour of clays differently. Since the Al-faces of clay structures have a negative charge in basic solutions. At high pH, all kaolinite surfaces become negative-charged, and then kaolinite

Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

International Nuclear Information System (INIS)

Rivard, C.; Pelletier, M.; Villieras, F.; Barres, O.; Galmiche, M.; Ghanbaja, J.; Kohler, A.; Michau, N.

2010-01-01

Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste it is of prime importance to understand the interactions between the saturated clay formation and steel containers. This can be achieved through an in-depth analysis of iron-clay interactions. Previous studies on the subject investigated the influence of solid/liquid ratio, iron/clay ratio, temperature and reaction time. The aim of the present study is to explain Callovo-Oxfordian-Fe(0) interactions by determining the role of each mineral phases present in the Callovo-Oxfordian (clay minerals, quartz, carbonates and pyrite) on the mechanisms of interaction between metal iron and clay particles. In that context, it is especially important to understand in detail the influence of clay nature and to obtain some insight about the relationships between interaction mechanisms at the molecular scale and crystallographic properties (particle size, TO or TOT layers, amount of edge faces...). The influence of the combination of different clays and the addition of other minerals must also be studied. In a first step, the Callovo-Oxfordian argillite from the Andra's underground research laboratory was purified to extract the clay fraction (illite, illite-smectite, kaolinite and chlorite). Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) for durations of one, three or nine months in the presence of metallic iron powder. Experiments without iron were used as control. The iron/clay ratio was fixed at 1/3 with a solid/liquid ratio of 1/20. The above mentioned experiments were also carried out in parallel on other purified clays: two smectites (Georgia bentonite and SWy2 from the Clay Minerals Society), one illite (illite du Puy) and one kaolinite (KGa2, from the Clay Minerals society). At the end of the experiments, solid and liquid phases were

Euroclay 95. Clays and clay materials sciences. Book of abstracts

Energy Technology Data Exchange (ETDEWEB)

Elsen, A; Grobet, P; Keung, M; Leeman, H; Schoonheydt, R; Toufar, H [eds.

1995-08-20

The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY `95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately.

Euroclay 95. Clays and clay materials sciences. Book of abstracts

International Nuclear Information System (INIS)

Elsen, A.; Grobet, P.; Keung, M.; Leeman, H.; Schoonheydt, R.; Toufar, H.

1995-01-01

The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY '95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

Science.gov (United States)

Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

2017-06-01

In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Complete sequence of Fig fleck-associated virus, a novel member of the family Tymoviridae.

Science.gov (United States)

Elbeaino, Toufic; Digiaro, Michele; Martelli, Giovanni P

2011-11-01

The complete nucleotide sequence and the genome organization were determined of a novel virus, tentatively named Fig fleck-associated virus (FFkaV). The viral genome is a positive-sense, single-stranded RNA 7046 nucleotides in size excluding the 3'-terminal poly(A) tract, and comprising two open reading frames. ORF1 encodes a polypeptide of 2161 amino acids (p240), which contains the signatures of replication-associated proteins and the coat protein cistron (p24) at its 3' end. ORF2 codes for a 461 amino acid protein (p50) identified as a putative movement proteins (MP). In phylogenetic trees constructed with sequences of the putative polymerase and CP proteins FFkaV consistently groups with members of the genus Maculavirus, family Tymoviridae. However, the genome organization diverges from that of the two completely sequenced maculaviruses, Grapevine fleck virus (GFkV) and Bombix mori Macula-like virus (BmMLV), as it exhibits a structure resembling that of Maize rayado fino virus (MRFV), the type species of the genus Marafivirus and of Olive latent virus 3 (OLV-3), an unclassified virus in the family Tymoviridae. FFkaV was found in field-grown figs from six Mediterranean countries with an incidence ranging from 15% to 25%. Copyright © 2011 Elsevier B.V. All rights reserved.

The effect of kauri (Agathis australis) on grain size distribution and clay mineralogy of andesitic soils in the Waitakere Ranges, New Zealand

NARCIS (Netherlands)

Jongkind, A.G.; Buurman, P.

2006-01-01

Kauri (Agathis australis) is generally associated with intense podzolisation, but little research has been carried out to substantiate this. We studied soil profiles, grain size distribution patterns and clay mineralogy under kauri and broadleaf/tree fern vegetation in the Waitakere Ranges, North

Corrosion of container and infrastructure materials under clay repository conditions

International Nuclear Information System (INIS)

Debruyn, W.; Dresselaers, J.; Vermeiren, P.; Kelchtermans, J.; Tas, H.

1991-01-01

With regard to the disposal of high-level radioactive waste, it was recommended in a IAEA Technical Committee meeting to perform tests in realistic environments corresponding with normal and accidental conditions, to qualify and apply corrosion monitoring techniques for corrosion evaluation under real repository conditions and to develop corrosion and near-field evolution models. The actual Belgian experimental programme for the qualification of a container for long-term HLW storage in clay formations complies with these recommendations. The emphasis in the programme is indeed on in situ corrosion testing and monitoring and on in situ control of the near-field chemistry. Initial field experiments were performed in a near-surface clay quarry at Terhaegen. Based on a broad laboratory material screening programme and in agreement with the Commission of the European Communities, three reference materials were chosen for extensive in situ overpack testing. Ti/0.2 Pd and Hastelloy C-4 were chosen as reference corrosion resistant materials and a low-carbon steel as corrosion allowance reference material. This report summarizes progress made in the material qualification programme since the CEC contract of 1983-84. 57 Figs.; 15 Tabs.; 18 Refs

Phylogeny and evolution of life-history strategies in the Sycophaginae non-pollinating fig wasps (Hymenoptera, Chalcidoidea

Directory of Open Access Journals (Sweden)

Farache Fernando HA

2011-06-01

Full Text Available Abstract Background Non-pollinating Sycophaginae (Hymenoptera, Chalcidoidea form small communities within Urostigma and Sycomorus fig trees. The species show differences in galling habits and exhibit apterous, winged or dimorphic males. The large gall inducers oviposit early in syconium development and lay few eggs; the small gall inducers lay more eggs soon after pollination; the ostiolar gall-inducers enter the syconium to oviposit and the cleptoparasites oviposit in galls induced by other fig wasps. The systematics of the group remains unclear and only one phylogeny based on limited sampling has been published to date. Here we present an expanded phylogeny for sycophagine fig wasps including about 1.5 times the number of described species. We sequenced mitochondrial and nuclear markers (4.2 kb on 73 species and 145 individuals and conducted maximum likelihood and Bayesian phylogenetic analyses. We then used this phylogeny to reconstruct the evolution of Sycophaginae life-history strategies and test if the presence of winged males and small brood size may be correlated. Results The resulting trees are well resolved and strongly supported. With the exception of Apocrytophagus, which is paraphyletic with respect to Sycophaga, all genera are monophyletic. The Sycophaginae are divided into three clades: (i Eukoebelea; (ii Pseudidarnes, Anidarnes and Conidarnes and (iii Apocryptophagus, Sycophaga and Idarnes. The ancestral states for galling habits and male morphology remain ambiguous and our reconstructions show that the two traits are evolutionary labile. Conclusions The three main clades could be considered as tribes and we list some morphological characters that define them. The same biologies re-evolved several times independently, which make Sycophaginae an interesting model to test predictions on what factors will canalize the evolution of a particular biology. The ostiolar gall-inducers are the only monophyletic group. In 15 Myr, they

Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

Directory of Open Access Journals (Sweden)

Landrou Gnanli

2017-01-01

Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

Efeito de vespas não-polinizadoras sobre o mutualismo Ficus - vespas de figos Effect of non-pollinating fig wasps over fig-fig wasp mutualism

Directory of Open Access Journals (Sweden)

Larissa G. Elias

Full Text Available Relações ecológicas interespecíficas, que resultam em benefício para todos os organismos participantes, são conhecidas como mutualismo. No entanto, tal cooperação abre espaço para o surgimento de estratégias oportunistas (ou de trapaça, representadas por indivíduos parasitas do mutualismo, que recebem o benefício de um dos parceiros sem oferecer nada em troca. A interação figueiras - vespas - de - figo é um sistema adequado para o estudo do mutualismo e de estratégias oportunistas (parasitas de mutualismos. Representantes do gênero Ficus (Moraceae apresentam uma relação mutualística com pequenas vespas polinizadoras (Agaonidae e são explorados por outras espécies de vespas não-polinizadoras. Esse trabalho teve como objetivo avaliar o impacto das vespas não-polinizadoras sobre o mutualismo Ficus citrifolia e suas vespas polinizadoras, Pegoscapus tonduzi Grandi, 1919. Para tal, foi comparada a produção de aquênios (função feminina e de fêmeas da espécie polinizadora (função masculina entre amostras de sicônios altamente infestados e pouco infestados por vespas não-polinizadoras, coletadas nos municípios de Londrina (Paraná, Campinas e Ribeirão Preto (São Paulo, Brasil. Nossos resultados apontaram que as vespas não-polinizadoras exercem impacto negativo nos componentes feminino e masculino da planta, sendo maior no masculino. A produção de vespas polinizadoras foi cerca de sete vezes menor nos figos infestados, ao passo que a produção de aquênios foi 1,5 vez menor nesses mesmos figos. Hipóteses sobre a estabilidade do mutualismo na presença das espécies oportunistas são discutidas.Mutualism is the name given to interspecific interactions which result in benefit for all partners involved. However, such cooperation is open to opportunistic strategies: individuals that extract the benefit from the partner, but do not offer any benefit in exchange. The fig-fig wasp interaction is an appropriate case to

Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications

CSIR Research Space (South Africa)

Musyoka, Nicholas M

2014-10-01

Full Text Available 57 58 59 60 For Peer Review 1 Synthesis of templated carbons starting from clay and clay-derived zeolites for hydrogen storage applications N. M. Musyoka1*, J. Ren1, H. W. Langmi1, D. E. C. Rogers1, B. C. North1, M. Mathe1 and D. Bessarabov2... clear (filtered) extract of cloisite clay, SNC for zeolite from unfiltered cloisite clay extract and SBC for zeolite from unfiltered South African bentonite clay extract. Furfuryl alcohol (Sigma Aldrich, C5H6O2, 98%) and Ethylene gas were used...

Effects of ionizing radiation on the boreal forest: Canada's FIG experiment, with implications for radionuclides

Energy Technology Data Exchange (ETDEWEB)

Amiro, B D; Sheppard, S C

1994-07-01

The Field-Irradiator Gamma (FIG) experiment chronically irradiated a section of the Canadian boreal forest over a period of 14 years. Forest trees were affected at dose rates >0.1 mGy{center_dot}h{sup -1}, but a berbaceous plant community thrived at dose rates up to 65 mGy{center_dot}h{sup -1}. Irradiation resulted in the establishment of four zones of vegetation: a herbaceous community, a shrub community, a narrow zone of dying trees, and a zone with no apparent impacts. Concentrations of {sup 14}C, {sup 99}Tc, {sup 129}I, {sup 137}Cs and {sup 226}Ra that could cause a dose rate of 0.1 mGy{center_dot}h{sup -1} within vegetation were calculated. Chemical toxic effects on plants would be caused by {sup 99}Tc and {sup 129}I before radiological effects are predicted to occur. The calculated {sup 226}Ra concentration is about a factor of 10 greater than that measured at some natural sites. Sufficiently high concentrations of {sup 14}C and {sup 137}Cs to cause an impact are unlikely unless a site is severely contaminated. (author)

Use of nuclear magnetic resonance in the characterization of modified clays; Uso da ressonancia magnetica nuclear na caracterizacao de argilas modificadas

Energy Technology Data Exchange (ETDEWEB)

Leite, Sidnei Q.M. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Menezes, Sonia M.C. de [PETROBRAS, Rio de Janeiro, RJ (Brazil). Centro de Pesquisas; Gil, Rosane A.S. San [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Quimica

1992-12-31

This work uses NMR spectroscopy with rotation in the {sup 29} Si, {sup 27} Al and {sup 23} Na magic angles for characterization of clays with Si/Al ratio in the range 3.0 - 16,5, obtained by chemical treatment of commercial samples, under different conditions of leaching with mineral acid 5 refs., 2 figs., 2 tabs.

FIG4 regulates lysosome membrane homeostasis independent of phosphatase function.

Science.gov (United States)

Bharadwaj, Rajnish; Cunningham, Kathleen M; Zhang, Ke; Lloyd, Thomas E

2016-02-15

FIG4 is a phosphoinositide phosphatase that is mutated in several diseases including Charcot-Marie-Tooth Disease 4J (CMT4J) and Yunis-Varon syndrome (YVS). To investigate the mechanism of disease pathogenesis, we generated Drosophila models of FIG4-related diseases. Fig4 null mutant animals are viable but exhibit marked enlargement of the lysosomal compartment in muscle cells and neurons, accompanied by an age-related decline in flight ability. Transgenic animals expressing Drosophila Fig4 missense mutations corresponding to human pathogenic mutations can partially rescue lysosomal expansion phenotypes, consistent with these mutations causing decreased FIG4 function. Interestingly, Fig4 mutations predicted to inactivate FIG4 phosphatase activity rescue lysosome expansion phenotypes, and mutations in the phosphoinositide (3) phosphate kinase Fab1 that performs the reverse enzymatic reaction also causes a lysosome expansion phenotype. Since FIG4 and FAB1 are present together in the same biochemical complex, these data are consistent with a model in which FIG4 serves a phosphatase-independent biosynthetic function that is essential for lysosomal membrane homeostasis. Lysosomal phenotypes are suppressed by genetic inhibition of Rab7 or the HOPS complex, demonstrating that FIG4 functions after endosome-to-lysosome fusion. Furthermore, disruption of the retromer complex, implicated in recycling from the lysosome to Golgi, does not lead to similar phenotypes as Fig4, suggesting that the lysosomal defects are not due to compromised retromer-mediated recycling of endolysosomal membranes. These data show that FIG4 plays a critical noncatalytic function in maintaining lysosomal membrane homeostasis, and that this function is disrupted by mutations that cause CMT4J and YVS. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Research of Deformation of Clay Soil Mixtures Mixtures

OpenAIRE

Romas Girkontas; Tadas Tamošiūnas; Andrius Savickas

2014-01-01

The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bear...

Major gene mutations in fruit tree domestication

International Nuclear Information System (INIS)

Spiegel-Roy, P.

1989-01-01

Though fruit gathering from the wild began long before domestication, fruit tree domestication started only after the establishment of grain agriculture. Banana, fig, date, grape and olive were among the first fruit trees domesticated. Most fruit trees are outbreeders, highly heterozygous and vegetatively propagated. Knowledge of genetics and economic traits controlled by major genes is limited. Ease of vegetative propagation has played a prominent part in domestication; advances in propagation technology will play a role in domestication of new crops. Changes toward domestication affected by major genes include self-fertility in peach, apricot and sour cherry, while the emergence of self-fertile almond populations is more recent and due probably to introgression from Amygdalus webbii. Self-compatibility in the sweet cherry has been attained only by pollen irradiation. A single gene controls sex in Vitis. Wild grapes are dioecious, with most domesticated cultivars hermaphrodite, and only a few females. In the papaya changes from dioecism to hermaphroditism have also occurred. Self-compatible systems have also been selected during domestication in Rubus. Changes towards parthenocarpy and seedlessness during domestication occurred in the banana, citrus, grape, fig and pineapple. In the banana, parthenocarpy is due to three complementary dominant genes; stenospermocarpy in the grape depends on two complementary recessive genes; parthenocarpy and sterility in citrus seems more complicated; however, it can be induced in genetic material of suitable background with ease by irradiation. Presence of persistent syconia in the fig is controlled by a mutant allele P dominant to wild +. Thornlessness in blackberry is recessive, while in the pineapple spineless forms are dominant. Changes affecting fruit composition owing to major genes include the disappearance of amygdalin present in bitter almonds (bitter kernel recessive to sweet), shell hardness in almond, and a recessive

ALA Pretreatment Improves Waterlogging Tolerance of Fig Plants.

Directory of Open Access Journals (Sweden)

Yuyan An

Full Text Available 5-aminolevulinic acid (ALA, a natural and environmentally friendly plant growth regulator, can improve plant tolerance to various environmental stresses. However, whether ALA can improve plant waterlogging tolerance is unknown. Here, we investigated the effects of ALA pretreatment on the waterlogging-induced damage of fig (Ficus carica Linn. plants, which often suffer from waterlogging stress. ALA pretreatment significantly alleviated stress-induced morphological damage, increased leaf relative water content (RWC, and reduced leaf superoxide anion ([Formula: see text] production rate and malonaldehyde (MDA content in fig leaves, indicating ALA mitigates waterlogging stress of fig plants. We further demonstrated that ALA pretreatment largely promoted leaf chlorophyll content, photosynthetic electron transfer ability, and photosynthetic performance index, indicating ALA significantly improves plant photosynthetic efficiency under waterlogging stress. Moreover, ALA pretreatment significantly increased activities of leaf superoxide dismutase (SOD and peroxidase (POD, root vigor, and activities of root alcohol dehydrogenase (ADH, and lactate dehydrogenase (LDH, indicating ALA also significantly improves antioxidant ability and root function of fig plants under waterlogging stress. Taken together, ALA pretreatment improves waterlogging tolerance of fig plants significantly, and the promoted root respiration, leaf photosynthesis, and antioxidant ability may contribute greatly to this improvement. Our data firstly shows that ALA can improve plant waterlogging tolerance.

Characterization of clay (bentonite)/crushed granite mixtures to build barriers against the migration of radionuclides: diffusion studies and physical properties

International Nuclear Information System (INIS)

Mingarro, E.; Rivas, P.; Villar, L.P. del; Cruz, B. de la; Gomez, P.; Hernandez, A.; Turrero, M.J.; Villar, M.V.; Campos, R.; Cozar, J.

1991-01-01

In Spain, the possibility is being considered of storage of radioactive waste in granitic rocks, using Spanish clays as backfill and sealing materials. The study and selection of these materials is the objective of the project, accomplished with Community financial support under CEC contract No Fl1W-0191-E (TT). With the aim of minimizing the chemical-mineralogical disequilibrium between the granitic rock and the artificial barrier, the possibility has been studied of using molten granite as an additive and illite as clayish material, instead of the normal use of smectite (montmorillonite). The studies have been carried out on 30 commercial Spanish clays and two kinds of granite and have been orientated to the selection of materials and the optimization of the clay-granite mixtures, chemical characterization, mechanics and physics of the mixtures and compacted blocks, determination of their behaviour in the gradient fields of temperature, pressure and chemical potentials and to the determination of the migration parameters. 59 Figs.; 6 Micrograph; 52 Tabs.; 30 Refs

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

Energy Technology Data Exchange (ETDEWEB)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A., E-mail: ferelenakq@gmail.co [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Buenos Aires (Argentina). Inst. de Investigaciones para la Industria Quimica; Pita, Victor J.R.R.; Dias, Marcos L. [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Profa. Eloisa Mano

2009-07-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

HDPE/clay hybrids: the effect of clay modified with poly(diphenyl siloxanes) on thermal and rheological properties

International Nuclear Information System (INIS)

Monasterio, Fernanda E.; Carrera, Maria C.; Erdmann, Eleonora; Destefanis, Hugo A.; Pita, Victor J.R.R.; Dias, Marcos L.

2009-01-01

Poly(diphenyl siloxanes) (PDPhS) were synthesized in presence of organophilic clay in order to modify its nano structure. Two silane monomers were used: dimethoxydiphenylsilane and dichlorodiphenylsilane. The following characterizations were performed for all clays: XRD, FTIR and TGA/DTG. These siloxane-modified clays were more hydrophobic and had enhanced thermal stability. Solvent extraction was carried out in the siloxane-modified clays and the PDPhS soluble fraction analyzed according the molecular weight via GPC. The presence of free and grafted oligomers on clay surface was identified. The modified clays were added to HDPE by melt processing to obtain HDPE/clay hybrids which exhibited marked differences in the rheological behavior when compared with neat HDPE. (author)

Crystallite size distribution of clay minerals from selected Serbian clay deposits

Directory of Open Access Journals (Sweden)

Simić Vladimir

2006-01-01

Full Text Available The BWA (Bertaut-Warren-Averbach technique for the measurement of the mean crystallite thickness and thickness distributions of phyllosilicates was applied to a set of kaolin and bentonite minerals. Six samples of kaolinitic clays, one sample of halloysite, and five bentonite samples from selected Serbian deposits were analyzed. These clays are of sedimentary volcano-sedimentary (diagenetic, and hydrothermal origin. Two different types of shape of thickness distribution were found - lognormal, typical for bentonite and halloysite, and polymodal, typical for kaolinite. The mean crystallite thickness (T BWA seams to be influenced by the genetic type of the clay sample.

Understanding the acquisition and regulation mechanisms of the water chemistry in a clay formation: the CEC/ANDRA Archimede-argile project

International Nuclear Information System (INIS)

Merceron, T.; Mossmann, J.R.; Neerdael, B.; Canniere, P. de; Beaucaire, C.; Toulhoat, P.; Daumas, S.; Bianchi, A.; Christen, R.

1993-01-01

Clay formations are candidate host environments to high level radioactive waste repository. The radioelements could be partially released from the waste into the host geological formation after a very long time. Understanding behaviour of the natural chemical species is considered as a fundamental prerequisite before the disturbed system will be studied. Additional laboratory studies are also essential in order to forecast, by analogy, the behaviour of radioelements released from the radioactive waste repository. The ARCHIMEDE-ARGILE project has two main goals. The first is to gain an understanding of the mechanisms of acquisition and regulation of the water chemistry in a clay environment. This step is essential to predict both the behaviour and the migration in solution of artificial elements which are initially absent in the clay formation. The second is to test and validate in clay the measured physico chemical parameters which are the basis for the geochemical modelling of the behaviour of the natural and artificial radioelements. The paper presents the main results previously obtained on granitic waters and the research strategy established for the ARCHIMEDE project. (authors). 2 figs., 2 refs

Aspects of clay/concrete interactions

International Nuclear Information System (INIS)

Oscarson, D.W.; Dixon, D.A.; Onofrei, M.

1997-01-01

In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH - -generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH) 2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH - potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85 o C with up to 5 wt.% Ca(OH) 2 , compacted bentonite (dry density = 1.2 Mg/m 3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10 -11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment

Physical Properties of Latvian Clays

OpenAIRE

Jurgelāne, I; Stepanova, V; Ločs, J; Mālers, J; Bērziņa-Cimdiņa, L

2012-01-01

Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society (June 2007)

Energy Technology Data Exchange (ETDEWEB)

Randall T. Cygan

2007-06-01

“Enchanted Clays: 44th Annual Meeting of the Clay Minerals Society” was held in early June 2007 in beautiful and historic Santa Fe, New Mexico, USA. Santa Fe provided an idyllic location in the southwestern United States for the attendees to enjoy technical and social sessions while soaking up the diverse culture and wonderful climate of New Mexico—The Land of Enchantment. The meeting included a large and varied group of scientists, sharing knowledge and ideas, benefitting from technical interactions, and enjoying the wonderful historic and enchanted environs of Santa Fe. Including significant number of international scientists, the meeting was attended by approximately two hundred participants. The meeting included three days of technical sessions (oral and poster presentations), three days of field trips to clay and geological sites of northern New Mexico, and a full day workshop on the stabilization of carbon by clays. Details can be found at the meeting web site: www.sandia.gov/clay.

Evaluation of the bleaching flux in clays containing hematite and different clay minerals

International Nuclear Information System (INIS)

Silva Junior, E.M.; Lusa, T.; Silva, T.M.; Medeiros, B.B.; Santos, G.R. dos; Morelli, M.R.

2016-01-01

Previous studies have shown that the addition of a synthetic flux in a clay mineral constituted by illite phase in the presence of iron oxide with the hematite, promotes color change of the firing products, making the reddish color firing into whiteness. This flow is constituted of a vitreous phase of the silicates family obtained by fusion/solidification of oxides and carbonates. Thus, the objective of this work was that of studying the interaction of the iron element in the final color mechanism of the different types of mineral crystal phase of the clays. In order to study the phenomenon, we obtained different compositions between the select clays and the synthetic flow, and characterization using X-ray diffraction (XRD) and visual analysis. The results showed that the action of the synthetic flow as a modifying agent for color depends on the mineral crystal phase of the clays. The color firing modification does not occur in the clays content high levels of kaolinite mineral phase. (author)

Columns in Clay

Science.gov (United States)

Leenhouts, Robin

2010-01-01

This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

FIG4 regulates lysosome membrane homeostasis independent of phosphatase function

OpenAIRE

Bharadwaj, Rajnish; Cunningham, Kathleen M.; Zhang, Ke; Lloyd, Thomas E.

2015-01-01

FIG4 is a phosphoinositide phosphatase that is mutated in several diseases including Charcot-Marie-Tooth Disease 4J (CMT4J) and Yunis-Varon syndrome (YVS). To investigate the mechanism of disease pathogenesis, we generated Drosophila models of FIG4-related diseases. Fig4 null mutant animals are viable but exhibit marked enlargement of the lysosomal compartment in muscle cells and neurons, accompanied by an age-related decline in flight ability. Transgenic animals expressing Drosophila Fig4 mi...

Effects of Different Types of Clays and Maleic Anhydride Modified Polystyrene on Polystyrene/Clay Nanocomposites

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M. Mehrabzadeh

2013-01-01

Full Text Available Polymer/clay nanocomposites are considered as a new subject of research in Iran and the world. Addition of a minimum amount of clay (2-5wt% can improve the mechanical properties, enhance barrier properties and reduce flammability dramatically. Polystyrene (PS exhibits high strength, high modulus and excellent dimensional stability, but it has poor ductility, elongation, and flexural modulus. By incorporating clay into polystyrene these properties can be improved. In this study preparation of polystyrene/clay nanocomposite, effects of different types of clays (Cloisite 10A andNanomer I.30TC and maleic anhydride modified polystyrene on mechanical properties of the prepared polystyrene/clay nanocomposites were evaluated. Samples were prepared by a twin screw extruder. Transmission electron microscopy (TEM and X-ray diffraction (XRD techniques were employed to evaluate the extent of intercalation and exfoliation of silicate layers in the nanocomposites. Mechanical tests show that by addition of clay and maleic anhydride modified polystyrene the flexural modulus (~30% and elongation-at-break (~40% of prepared nanocomposites have been improved. XRD and TEM results show that nanocomposite have an intercalated structure with ability to change to further exfoliation structure.

Thixotropic Properties of Latvian Illite Containing Clays

OpenAIRE

Lakevičs, Vitālijs; Stepanova, Valentīna; Niedra, Santa; Dušenkova, Inga; Ruplis, Augusts

2015-01-01

Thixotropic properties of Latvian Devonian and Quaternary clays were studied. Dynamic viscosity of the water clay suspensions were measured with a rotating viscometer. Influence of concentration, pH and modifiers on the thixotropic clay properties was analyzed. It was found that Latvian clays have thixotropic properties. Stability of clay suspensions is described with the thixotropy hysteresis loop. Increasing the speed of the viscometer rotation, dynamic viscosity of the clay suspension decr...

Clay exfoliation and polymer/clay aerogels by supercritical carbon dioxide

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Simona eLongo

2013-11-01

Full Text Available Supercritical carbon dioxide (scCO2 treatments of a montmorillonite (MMT intercalated with ammonium cations bearing two long hydrocarbon tails (organo-modified MMT, OMMT led to OMMT exfoliation, with loss of the long-range order in the packing of the hydrocarbon tails and maintenance of the long-range order in the clay layers. The intercalated and the derived exfoliated OMMT have been deeply characterized, mainly by X-ray diffraction analyses. Monolithic composite aerogels, with large amounts of both intercalated and exfoliated OMMT and including the nanoporous-crystalline δ form of syndiotactic polystyrene (s-PS, have been prepared, by scCO2 extractions of s-PS-based gels. Also for high OMMT content, the gel and aerogel preparation procedures occur without re-aggregation of the exfoliated clay, which is instead observed for other kinds of polymer processing. Aerogels with the exfoliated OMMT have more even dispersion of the clay layers, higher elastic modulus and larger surface area than aerogels with the intercalated OMMT. Extremely light materials with relevant transport properties could be prepared. Moreover, s-PS-based aerogels with exfoliated OMMT could be helpful for the handling of exfoliated clay minerals.

Long term radiocesium contamination of fruit trees following the Chernobyl accident

International Nuclear Information System (INIS)

Antonopoulos-Domis, M.; Clouvas, A.; Gagianas, A.

1996-01-01

Radiocesium contamination form the Chernobyl accident of fruits and leaves from various fruit trees was systematically studied form 1990-1995 on two agricultural experimentation farms in Northern Greece. The results are discussed in the framework of a previously published model describing the long-term radiocesium contamination mechanism of deciduous fruit trees after a nuclear accident. The results of the present work qualitatively verify the model predictions. 11 refs., 5 figs., 1 tab

What makes a natural clay antibacterial?

Science.gov (United States)

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Port-Peterson, Amisha T.

2011-01-01

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (2+ solubility.

Viscosity and Plasticity of Latvian Illite Clays

OpenAIRE

Jurgelāne, I; Vecstaudža, J; Stepanova, V; Mālers, J; Bērziņa-Cimdiņa, L

2012-01-01

Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

Clay Portrait Boxes

Science.gov (United States)

Wilbert, Nancy Corrigan

2009-01-01

In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

Clay matrix voltammetry

International Nuclear Information System (INIS)

Perdicakis, Michel

2012-01-01

Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS 2 ), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

Clay Animals and Their Habitats

Science.gov (United States)

Adamson, Kay

2010-01-01

Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

Science.gov (United States)

Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

2002-07-01

In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

21 CFR 186.1256 - Clay (kaolin).

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Clay (kaolin). 186.1256 Section 186.1256 Food and... Substances Affirmed as GRAS § 186.1256 Clay (kaolin). (a) Clay (kaolin) Al2O3.2SiO2.nH2O, Cas Reg. No. 1332-58-7) consists of hydrated aluminum silicate. The commercial products of clay (kaolin) contain...

Quantifying the effect of squirt flow dispersion from compliant clay porosity in clay bearing sandstones

DEFF Research Database (Denmark)

Sørensen, Morten Kanne; Fabricius, Ida Lykke

2013-01-01

Compliant porosity in the form of cracks is known to cause significant attenuation and velocity dispersion through pore pressure gradients and consequent relaxation, dubbed squirt flow. Squirt flow from cracks vanish at high confining stress due to crack closing. Studies on clay bearing sandstones......-squirt flow on the bulk modulus of a clay bearing sandstone. The predicted magnitude of the clay-squirt effect on the bulk modulus is compared with experimental data. The clay-squirt effect is found to possibly account for a significant portion of the deviances from Gassmann fluid substitution in claybearing...... sandstones....

Event tree analysis using artificial intelligence techniques

International Nuclear Information System (INIS)

Dixon, B.W.; Hinton, M.F.

1985-01-01

Artificial Intelligence (AI) techniques used in Expert Systems and Object Oriented Programming are discussed as they apply to Event Tree Analysis. A SeQUence IMPortance calculator, SQUIMP, is presented to demonstrate the implementation of these techniques. Benefits of using AI methods include ease of programming, efficiency of execution, and flexibility of application. The importance of an appropriate user interface is stressed. 5 figs

Molecular trees: from syntheses towards applications

International Nuclear Information System (INIS)

Ardoin, N.; Astruc, D.

1995-01-01

Molecular trees, also called dendrimers, arborols, cauliflowers, cascades or hyperbranched molecules, have been synthesized since their first observation in 1978 by divergent, convergent or combined methods, with various functions on the branches. The potential applications of these nanoscopic molecules are in the fields of biology (gene therapy, virus mimicking an vectorization) and molecular materials sciences (new polymers, adhesion, liquid crystals, etc). (authors). 236 refs., 6 figs., 2 tabs., 8 schemes

Mineral acquisition from clay by budongo forest chimpanzees

NARCIS (Netherlands)

Reynolds, Vernon; Lloyd, Andrew W.; English, Christopher J.; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay

Evaluation of kaolinite clays of Moa for the production of cement based clinker-calcined clay-limestone (LC3

Directory of Open Access Journals (Sweden)

Roger S. Almenares-Reyes

2016-12-01

Full Text Available Clay materials from two outcrops of the Moa region were analyzed to determine their potential use as supplementary cementitious material in the production of ternary cements based on limestone-calcined clay. The clays were characterized by atomic absorption spectroscopy (EAA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (ATG. These methods revealed high aluminum in clays, moderate kaolinite content, a disordered structure and the presence of impurities. The solubility of aluminum and silicon in alkali and the compressive strength of LC3 systems is proportional to their content in clay, being higher for the one with higher kaolinite content and greater structural disorder (outcrop D1, although the clay of both outcrops may constitute supplementary cementitious materials in the production of ternary cements based clinker-calcined clay-limestone. The suitable thermal activation range for both clays is between 650 ° C and 850 ° C.

Methane production rates from natural organics of glacial lake clay and granitic groundwater

Energy Technology Data Exchange (ETDEWEB)

Sheppard, M I; Stroes-Gascoyne, S; Hawkins, J L; Hamon, C J; Motycka, M

1996-05-01

Engineered barrier materials are an integral part of the proposed Canadian concept for the disposal of used nuclear fuel or high level waste. Components of these barriers, such as the buffer and backfill clays surrounding the waste containers in a vault, and granitic groundwater, naturally contain small quantities of organic material (up to about 1.2 wt%). Despite high temperatures, space and water limitations and radiation effects, the question remains whether gas could be produced from these organics as a result of biological processes. Degradation of organic carbon by microbes can produce gases such as carbon dioxide (C0{sub 2}) and methane (CH{sub 4}). This work demonstrates that methane is produced in natural systems containing < 6 mole % 0{sub 2}. In deep fracture zone groundwater, the largest methane production rate was 0.19 mole %/day or 5 {mu}g CH{sub 4}/L groundwater per day, at STP. This can be compared with the methane production rate of 1 {mu}g CH{sub 4}/(kg clay {center_dot} day) at STP in an earlier experiment containing added organic material. Using this rate of 5 pg CH{sub 4}/(L groundwater {center_dot} day) (3.75 {mu}g C/(L groundwater {center_dot} day)), all of the organic C in the groundwater, assuming it is equally bioavailable, would have been converted to CH{sub 4} during the timeframe of this experiment. Enhanced methane production occurred with an increase in natural organic carbon, an increase in the microbe population and with the addition of Fe. Steady-state methane production rates of 10 to 25 {mu}g CH{sub 4}/ L groundwater per day have been repeatedly observed in clay-free systems. The effects of microbial metabolism, the requirement for a facilitating consortium, the Eh, the pH, the salinity, the groundwater sulphate concentration, the presence of methanotrophs and the sorption effects of clay interlayers are discussed as possible explanations for the inhibition of methanogenesis and methane production in the presence of clay and

Influence of herbicide structure, clay acidity, and humic acid coating on acetanilide herbicide adsorption on homoionic clays.

Science.gov (United States)

Liu, Weiping; Gan, Jianying; Yates, Scott R

2002-07-03

Adsorption of chloroacetanilide herbicides on homoionic montmorillonite was studied by coupling batch equilibration and FT-IR analysis. Adsorption decreased in the order metolachlor > acetochlor > alachlor > propachlor on Ca(2+)- or Mg(2+)-saturated clays and in the order metolachlor > alachlor > acetachlor > propachlor on Al(3+)- or Fe(3+)-saturated clays. FT-IR spectra showed that the carbonyl group of the herbicide molecule was involved in bonding. For the same herbicide, adsorption of alachlor, acetachlor, and metolachlor on clay followed the order Ca(2+) approximately Mg(2+) < Al(3+) < or = Fe(3+), which coincided with the increasing acidity of homoionic clays. Adsorption of propachlor, however, showed an opposite dependence, suggesting a different governing interaction. In clay and humic acid mixtures, herbicide adsorption was less than that expected from independent additive adsorption by the individual constituents, and the deviation was dependent on the clay-to-humic acid ratio, with the greatest deviation consistently occurring at a 60:40 clay-to-humic acid ratio.

Can urban tree roots improve infiltration through compacted subsoils for stormwater management?

Science.gov (United States)

Bartens, Julia; Day, Susan D; Harris, J Roger; Dove, Joseph E; Wynn, Theresa M

2008-01-01

Global land use patterns and increasing pressures on water resources demand creative urban stormwater management. Strategies encouraging infiltration can enhance groundwater recharge and water quality. Urban subsoils are often relatively impermeable, and the construction of many stormwater detention best management practices (D-BMPs) exacerbates this condition. Root paths can act as conduits for water, but this function has not been demonstrated for stormwater BMPs where standing water and dense subsoils create a unique environment. We examined whether tree roots can penetrate compacted subsoils and increase infiltration rates in the context of a novel infiltration BMP (I-BMP). Black oak (Quercus velutina Lam.) and red maple (Acer rubrum L.) trees, and an unplanted control, were installed in cylindrical planting sleeves surrounded by clay loam soil at two compaction levels (bulk density = 1.3 or 1.6 g cm(-3)) in irrigated containers. Roots of both species penetrated the more compacted soil, increasing infiltration rates by an average of 153%. Similarly, green ash (Fraxinus pennsylvanica Marsh.) trees were grown in CUSoil (Amereq Corp., New York) separated from compacted clay loam subsoil (1.6 g cm(-3)) by a geotextile. A drain hole at mid depth in the CUSoil layer mimicked the overflow drain in a stormwater I-BMP thus allowing water to pool above the subsoil. Roots penetrated the geotextile and subsoil and increased average infiltration rate 27-fold compared to unplanted controls. Although high water tables may limit tree rooting depth, some species may be effective tools for increasing water infiltration and enhancing groundwater recharge in this and other I-BMPs (e.g., raingardens and bioswales).

Comparing Kriging and Regression Approaches for Mapping Soil Clay Content in a diverse Danish Landscape

DEFF Research Database (Denmark)

Adhikari, Kabindra; Bou Kheir, Rania; Greve, Mette Balslev

2013-01-01

Information on the spatial variability of soil texture including soil clay content in a landscape is very important for agricultural and environmental use. Different prediction techniques are available to assess and map spatial variability of soil properties, but selecting the most suitable techn...... the prediction in OKst compared with that in OK, whereas RT showed the lowest performance of all (R2 = 0.52; RMSE = 0.52; and RPD = 1.17). We found RKrr to be an effective prediction method and recommend this method for any future soil mapping activities in Denmark....... technique at a given site has always been a major issue in all soil mapping applications. We studied the prediction performance of ordinary kriging (OK), stratified OK (OKst), regression trees (RT), and rule-based regression kriging (RKrr) for digital mapping of soil clay content at 30.4-m grid size using 6...

Clay shale as host rock. A geomechanical contribution about Opalinus clay

International Nuclear Information System (INIS)

Lempp, Christof; Menezes, Flora; Sachwitz, Simon

2016-01-01

The Opalinuston is a prominent rock representing the type of organic clay shales or clay stones within the sequence of Triassic and Jurassic marine sediments in Southern Germany. The rock forms a homogenous unit some ten meters thick. The degree of consolidation of this type of pelitic rock depends mainly on the former load conditions, but is also dependent on the long-term weathering and even on the present exposition. The geomechanical parameters such as shear strength, tensional strength and permeability vary with the state of consolidation and become important when the use is discussed of such rocks for radioactive waste disposal. A tunneling project at the northern escarpment of the Swabian Alb (Southwest Germany) within the Opalinus clay offered the rare opportunity to obtain fresh unweathered rock samples in greater amounts compared to fresh drilling cores from which geomechanical investigations are usually undertaken. Consequently, the results of geomechanical laboratory testings are presented in order to compare here the results of multistep triaxial compression tests, of hydraulic fracturing laboratory tests and of some other tests for rock characterization with the corresponding results of Opalinus clay sites in Switzerland that were investigated by the Swiss Nagra Company for host rock characterization. After a discussion of the relevant state of fresh Opalinus clay, especially of suction pressure conditions and saturation state, the results of triaxial shear tests are presented. Increasing shear deformation at increasing pressure and unchanged water saturation do not result in a significant strength reduction of the Opalinus clay. The rock shows increasing cohesion and stiffness, if multiple loading has repeatedly reached the failure point. Thus there is no increased permeability with continued shearing. Only at the beginning of the shearing process is a temporarily increased permeability to be expected due to dilatation processes. An increased

Diffusion through statically compacted clay

International Nuclear Information System (INIS)

Ho, C.L.; Shebl, M.A.A.

1994-01-01

This paper presents experimental work on the effect of compaction on contaminant flow through clay liners. The experimental program included evaluation of soil properties, compaction, permeability and solute diffusion. A permeameter was built of non reactive materials to test samples compacted at different water contents and compactive efforts. The flow of a permeating solute, LiCl, was monitored. Effluent samples were collected for solute concentration measurements. The concentrations were measured by performing atomic adsorption tests. The analyzed results showed different diffusion characteristics when compaction conditions changed. At each compactive effort, permeability decreased as molding water content increased. Consequently, transit time (measured at relative concentration 50%) increased and diffusivity decreased. As compactive effort increased for soils compacted dry of optimum, permeability and diffusion decreased. On the other hand, as compactive effort increased for soils compacted wet of optimum, permeability and diffusivity increased. Tortuosity factor was indirectly measured from the diffusion and retardation rate. Tortuosity factor also decreased as placement water content was increased from dry of optimum to wet of optimum. Then decreases were more pronounced for low compactive effort tests. 27 refs., 7 figs., 5 tabs

Mineralogy and geotechnical characteristics of some pottery clay

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Mujib Olamide ADEAGBO

2016-12-01

Full Text Available The physical properties of soils, which are tremendously influenced by the active clay minerals in soil, are of great importance in geotechnical engineering. This paper investigates the clay-sized particles of the Igbara-Odo pottery clay, and compares results obtained with available data on the bulk sample, to determine their correlation and underline the dependence of the geotechnical properties of the bulk clay material on the clay-sized particles. The bulk clay sample consists of 52% sand-size particles, 21% silt and 27% clay. Analysis of the clay-sized particles and the bulk materials shows: specific gravity of 2.07 and 2.66, liquid limit of 91.0% and 33.0%, plastic limit of 27.5% and 14.3%, plasticity index of 63.5% and 18.7% and a linear shrinkage of 7.9% and 5.4%, for both clay-sized particles and bulk clay respectively. The activity value of the clay material (0.64 suggests the presence of Kaolinite and Ilite; and these were confirmed with X-Ray diffraction on the bulk sample and clay-sized particles. X-Ray diffraction patterns shows distinctive peaks which highlight the dominance of Kaolinite (with 8 peaks in the pottery clay sample for both clay-sized particles and bulk material; while traces of other clay minerals like Illite and Halloysite and rock minerals like Mica, Feldspar and Chrysotile were also found. These results suggest that the clay possesses high viability in the manufacturing of ceramics, refractory bricks, paper, fertilizer and paint. The clay material can be used as a subgrade in road construction, since it possesses low swelling characteristics.

Xenon-129 NMR study of the microporous structure of clays and pillared clays

International Nuclear Information System (INIS)

Tsiao, C.; Carrado, K.A.

1990-01-01

129 Xe NMR studies have been carried out using xenon gas adsorbed in clays and pillared clays. Data from the measurements provide information on the pore structure of clays before and after pillaring. The results indicate that the effective pore diameter of montmorillonite increases, for example, from 5.4 Angstrom to 8.0 Angstrom after pillaring cheto-montmorillonite with aluminum polyoxohydroxy Keggin cations. The data are consistent with X-ray powder diffraction results, which show a corresponding increase in the interlamellar gallery height from 5.6 Angstrom to 8.4 Angstrom

Nearfield behaviour of clay barriers and their interaction with concrete Task 3 characterization of radioactive waste forms a series of final reports (1985-89) No 26

International Nuclear Information System (INIS)

Atabek, R.; Beziat, A.; Coulon, H.; Dardaine, M.; Eglem, A.; Farcy, C.; Fontan, N.; Gatabin, C.; Gegout, P.; Lajudie, A.; Landoas, O.; Lechelle, J.; Plas, F.; Raynal, J.; Revertegat, E.; Debrabant, P.; Proust, D.

1991-01-01

In order to guarantee the safety of waste underground disposal, engineered barriers will be implemented as backfill materials in galleries and access shafts and as buffer materials between the host medium and the waste packages. One of the first requirements for engineered barriers is to minimize water and chemical species transfer. The materials being considered are essentially swelling clays, in particular calcium smectite clays coming from french deposits and hydraulic binders, more specially a ternary cement (named C.L.C.). A vitrified waste disposal in granite is taken as the most constraining scenario as far as engineered barrier is concerned. The clay buffer material is placed between the packages and the host rock. The main properties which are determined are directly related to the engineered barrier requirements: thermal conductivity, hydraulic conductivity, swelling pressure and swelling capacity. Moreover results are obtained on temperature effect on clay microstructure and properties in both cases: without and with water intake. The concrete durability with regard to clay pore water attack is evaluated taking into account previous results obtained to ensure low-level radioactive waste disposal safety. 23 refs., 29 figs., 10 tabs

The dynamics of strangling among forest trees.

Science.gov (United States)

Okamoto, Kenichi W

2015-11-07

Strangler trees germinate and grow on other trees, eventually enveloping and potentially even girdling their hosts. This allows them to mitigate fitness costs otherwise incurred by germinating and competing with other trees on the forest floor, as well as minimize risks associated with host tree-fall. If stranglers can themselves host other strangler trees, they may not even seem to need non-stranglers to persist. Yet despite their high fitness potential, strangler trees neither dominate the communities in which they occur nor is the strategy particularly common outside of figs (genus Ficus). Here we analyze how dynamic interactions between strangling and non-strangling trees can shape the adaptive landscape for strangling mutants and mutant trees that have lost the ability to strangle. We find a threshold which strangler germination rates must exceed for selection to favor the evolution of strangling, regardless of how effectively hemiepiphytic stranglers may subsequently replace their hosts. This condition describes the magnitude of the phenotypic displacement in the ability to germinate on other trees necessary for invasion by a mutant tree that could potentially strangle its host following establishment as an epiphyte. We show how the relative abilities of strangling and non-strangling trees to occupy empty sites can govern whether strangling is an evolutionarily stable strategy, and obtain the conditions for strangler coexistence with non-stranglers. We then elucidate when the evolution of strangling can disrupt stable coexistence between commensal epiphytic ancestors and their non-strangling host trees. This allows us to highlight parallels between the invasion fitness of strangler trees arising from commensalist ancestors, and cases where strangling can arise in concert with the evolution of hemiepiphytism among free-standing ancestors. Finally, we discuss how our results can inform the evolutionary ecology of antagonistic interactions more generally

Wave liquefaction in soils with clay content

DEFF Research Database (Denmark)

Kirca, Özgür; Sumer, B. Mutlu; Fredsøe, Jørgen

2012-01-01

The paper presents the results of an experimental study of the influence of clay content (in silt-clay and sand-clay mixtures) on liquefaction beneath progressive waves. The experiments showed that the influence of clay content is very significant. Susceptibility of silt to liquefaction is increa...

Characterization of clay minerals

International Nuclear Information System (INIS)

Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A.

2002-01-01

The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

Produção da figueira submetida a diferentes épocas de poda e irrigação The yield of fig trees as a function of pruning time and irrigation

Directory of Open Access Journals (Sweden)

Sarita Leonel

2008-12-01

Full Text Available O trabalho teve como objetivo avaliar diferentes épocas de poda, correspondentes aos meses de julho, agosto, setembro e outubro dos anos de 2004/05 e 2005/06, com e sem o uso de irrigação, em figueira 'Roxo de Valinhos', no município de Botucatu-SP. Para atingir tal objetivo, adotou-se o delineamento experimental em parcelas subdivididas, com 5 repetições em blocos, onde as parcelas corresponderam aos tratamentos com e sem irrigação, e as subparcelas foram constituídas pelas podas realizadas nos quatro meses do ano. Foram avaliadas características de produção e alguns atributos de qualidade, que serviram para indicar a necessidade do uso de irrigação. Os resultados obtidos permitiram concluir que, na avaliação do desdobramento da interação entre épocas de poda e irrigação complementar, o mês de agosto, com o uso de irrigação complementar, foi o mais favorável para a realização da poda da figueira, proporcionando as maiores produções médias verificadas no ensaio, tanto no ciclo agrícola de 2004/05 (3.513,8 g planta-1, quanto em 2005/06 (4.110,7 g planta-1. Em condições não-irrigadas, não houve diferença estatística entre os meses de julho, agosto e setembro de 2004/05 e entre julho e agosto de 2005/06.The research had the purpose to determine the effects of pruning time in July, August, September and October of 2004/05 and 2005/06, with and without irrigation, in the fig trees 'Roxo de Valinhos', located in Botucatu/SP/Brazil. The experimental design was in split plots with 5 replications at random in lines, where the plots consisted in the treatments with and without irrigation and the subplots were composed of the pruning accomplished in the four months of the year. It was evaluated the yield and fruits quality. These characteristics could be used to evaluate the irrigation necessity. The August month with irrigation was the best time to the fig trees pruning, enhancing the yield (3.513,8 g plant-1 in 2004

Clays and Clay Minerals and their environmental application in Food Technology

Science.gov (United States)

del Hoyo Martínez, Carmen; Cuéllar Antequera, Jorge; Sánchez Escribano, Vicente; Solange Lozano García, Marina; Cutillas Díez, Raul

2013-04-01

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications. Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health. We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health. References

Transport of toxic material within the clay lining of waste disposal sites and natural clay layers. Schadstofftransport in mineralischen Deponieabdichtungen und natuerlichen Tonschichten

Energy Technology Data Exchange (ETDEWEB)

Schneider, W; Goettner, J J

1991-01-01

In a field experiment lasting two years the transfer of several substances was observed in clay by technical measurement. The substance transport was simulated with three mathematical models which considered different transport process mechanisms. The quality of numerical adaption in connection with plausibility tests allow the determination of the factual transport proceeding and the quantity of the separate partial processes. The perceptions gained are employed for calculating the dimensions of mineral sealings. The environmental supportability of dumps can be conducted by calculating the duration and permeation rates of different pollutions. Recommendations for the construction and dimensioning of sealings and for the dump conception are given using these calculations. In order to utilize the present experiences for dump practice concrete proposals are made for the construction and management of fields of measurement for the dump supervision. (orig.) With 49 figs., 17 tabs.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

Directory of Open Access Journals (Sweden)

Vernon Reynolds

Full Text Available Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Mineral Acquisition from Clay by Budongo Forest Chimpanzees.

Science.gov (United States)

Reynolds, Vernon; Lloyd, Andrew W; English, Christopher J; Lyons, Peter; Dodd, Howard; Hobaiter, Catherine; Newton-Fisher, Nicholas; Mullins, Caroline; Lamon, Noemie; Schel, Anne Marijke; Fallon, Brittany

2015-01-01

Chimpanzees of the Sonso community, Budongo Forest, Uganda were observed eating clay and drinking clay-water from waterholes. We show that clay, clay-rich water, and clay obtained with leaf sponges, provide a range of minerals in different concentrations. The presence of aluminium in the clay consumed indicates that it takes the form of kaolinite. We discuss the contribution of clay geophagy to the mineral intake of the Sonso chimpanzees and show that clay eaten using leaf sponges is particularly rich in minerals. We show that termite mound soil, also regularly consumed, is rich in minerals. We discuss the frequency of clay and termite soil geophagy in the context of the disappearance from Budongo Forest of a formerly rich source of minerals, the decaying pith of Raphia farinifera palms.

Influence of carbonate micro-fabrics on the failure strength of Callovo-Oxfordian clay stones and Opalinus Clay

International Nuclear Information System (INIS)

Klinkenberg, M.; Dohrmann, R.; Kaufhold, S.; Siegesmund, S.

2010-01-01

Document available in extended abstract form only. The potential use of clay stones as host rock for radioactive waste disposal is currently investigated. For this application, hydraulic conductivity, swelling properties, water uptake, rheological and mechanical properties are of great importance. The Opalinus Clay (Mont-Terri, Switzerland) and the Callovo- Oxfordian clay stone (France) are the most frequently studied clay stones. One goal is to develop a numerical model being able to predict the mechanical behaviour of clay stones under repository-like conditions. Experimental investigations reveal that Opalinus Clay and Callovo-Oxfordian clay stone behave different with respect to the dependence of mechanical strength on the carbonate content. The failure strength of Opalinus Clay decreases with increasing carbonate content, whereas it increases with increasing carbonate content when Callovo-Oxfordian clay stone is considered. To supply proper data and enable reliable model assumptions, the use of suitable experimental techniques for the description of the microstructure is indispensable. After mechanical testing, samples were taken perpendicular to the bedding and polished sections were prepared. The micro-fabrics were investigated using scanning electron microscopy (SEM) and image analysis. Backscattered electron (BSE) images were used for the image analysis because carbonates can be extracted by grey level analysis. The image analysis of the extracted particles provides the following parameters: area, longest and shortest axis of an ellipse (surrounding the particle), perimeter, the angle to horizontal (longest axis), and the aspect ratio (longest axis/shortest axis). Callovo-Oxfordian clay stone shows a homogenous distribution of fine-grained carbonates and dovetail connection of calcium carbonate with the clayey matrix. In contrast Opalinus Clay shows large elongated carbonate grains (high aspect ratios) of shell fragments. Cracks are mostly related to these

In situ and laboratory migration experiments through boom clay at Mol

International Nuclear Information System (INIS)

Preter, P. de; Put, M.; Canniere, P. de

1993-01-01

Physico-chemical characterization and migration studies in the Boom clay, envisaged as a potential host sediment for high level waste disposal in Belgium, were started some 15 years ago. A synthesis study of this experimental work has recently been conducted to compile all available data. From a comparison of the available migration data and the data requirements as derived from the performance assessment studies PAGIS (1988) and PACOMA (1991) the new migration programme (1991-1995) was defined. The critical radionuclides, both with relation to dose rates to man and to missing or unreliable migration data, turned out to be 14 C, 99 Tc. 135 Cs and 237 Np. A second group of radionuclides was found to be possibly critical: 79 Se, 93 Zr, 107 Pd, U - , Am - , Cm - , and Pu-isotopes. This report concentrates on the experimental results as obtained from the migration experiments started in the previous migration programme. Some of the reported radionuclides e.g. 90 Sr) have lost their critical character and will not be further studied within the new programme. New experimental data from laboratory tests have become available for Np, Cs, Sr and C (as HC0 3 - ) and the first results on the migration of organic molecules dissolved in the interstitial Boom clay water are reported. The hydraulic parameters (the hydraulic conductivity K and the storage coefficient S o ) were calculated from both laboratory percolation experiments and in situ piezometric measurements. Conclusions concerning Boom clay anisotropy are drawn. Finally, a short description of the ongoing in situ HTO injection experiment is given and the experimental data are analyzed and discussed. 10 refs., 4 figs., 1 tab

Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

International Nuclear Information System (INIS)

Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

2009-01-01

Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

A collaborative archaeological research and conservation project for Moriori carved trees (rakau momori), Rekohu (Chatham Island)

International Nuclear Information System (INIS)

Barber, I.; Maxwell, J.

2011-01-01

In January-February 2010 a conservation and site-recording project began on Rekohu (Chatham Island) to locate, assess and digitally scan archaeological carved trees known as rakau momori ('dendroglyphs'). This paper briefly considers earlier work on carved trees before reporting preliminary and anticipated outcomes from our recent collaborative rakau momori archaeological project. 14 refs., 9 figs., 2 tabs.

Crude oil polycyclic aromatic hydrocarbons removal via clay-microbe-oil interactions: Effect of acid activated clay minerals.

Science.gov (United States)

Ugochukwu, Uzochukwu C; Fialips, Claire I

2017-07-01

Acid treatment of clay minerals is known to modify their properties such as increase their surface area and surface acidity, making them suitable as catalysts in many chemical processes. However, the role of these surface properties during biodegradation processes of polycyclic aromatic hydrocarbons (PAHs) is only known for mild acid (0.5 M Hydrochloric acid) treated clays. Four different clay minerals were used for this study: a montmorillonite, a saponite, a palygorskite and a kaolinite. They were treated with 3 M hydrochloric acid to produce acid activated clay minerals. The role of the acid activated montmorillonite, saponite, palygorskite and kaolinite in comparison with the unmodified clay minerals in the removal of PAHs during biodegradation was investigated in microcosm experiments. The microcosm experiments contained micro-organisms, oil, and clays in aqueous medium with a hydrocarbon degrading microorganism community predominantly composed of Alcanivorax spp. Obtained results indicated that acid activated clays and unmodified kaolinite did not enhance the biodegradation of the PAHs whereas unmodified montmorillonite, palygorskite and saponite enhanced their biodegradation. In addition, unmodified palygorskite adsorbed the PAHs significantly due to its unique channel structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

From clay bricks to deep underground storage

International Nuclear Information System (INIS)

2012-05-01

This booklet issued by the Swiss National Cooperative for the Disposal of Radioactive Waste NAGRA takes a look at the use of clay strata for the storage of radioactive wastes in deep-lying repositories. First of all, a geological foray is made concerning the history of the use of clay and its multifarious uses. The characteristics of clay and its composition are examined and its formation in the geological past is explained. In particular Opalinus clay is looked at and the structures to be found are discussed. The clay's various properties and industrial uses are examined and its sealing properties are examined. Also, Bentonite clay is mentioned and work done by Nagra and co-researchers is noted

Microstructure and Thermal Properties of Polypropylene/Clay Nanocomposites with TiCl4/MgCl2/Clay Compound Catalyst

Directory of Open Access Journals (Sweden)

Limei Wang

2015-01-01

Full Text Available Polypropylene (PP/clay nanocomposites were synthesized by in situ intercalative polymerization with TiCl4/MgCl2/clay compound catalyst. Microstructure and thermal properties of PP/clay nanocomposites were studied in detail. Fourier transform infrared (FTIR spectra indicated that PP/clay nanocomposites were successfully prepared. Both wide-angle X-ray diffraction (XRD and transmission electron microscopy (TEM examination proved that clay layers are homogeneously distributed in PP matrix. XRD patterns also showed that the α phase was the dominate crystal phase of PP in the nanocomposites. Thermogravimetric analysis (TGA examinations confirmed that thermal stability of PP/clay nanocomposites was markedly superior to pure PP. Differential scanning calorimetry (DSC scans showed that the melt temperature and the crystallinity of nanocomposites were slightly lower than those of pure PP due to crystals imperfections.

Iodide Sorption to Clays and the Relationship to Surface Charge and Clay Texture - 12356

Energy Technology Data Exchange (ETDEWEB)

Miller, Andrew; Kruichiak, Jessica; Tellez, Hernesto; Wang, Yifeng [Sandia National Laboratories, Albuquerque, NM 87185 (United States)

2012-07-01

Iodine is assumed to behave conservatively in clay barriers around nuclear waste repositories and in natural sediments. Batch experiments tend to show little to no sorption, while in column experiments iodine is often retarded relative to tritiated water. Current surface complexation theory cannot account for negatively charged ion sorption to a negatively charged clay particle. Surface protonation and iodide sorption to clay minerals were examined using surface titrations and batch sorption experiments with a suite of clay minerals. Surface titrations were completed spanning a range of both pH values and ionic strengths. For reference, similar titrations were performed on pure forms of an Al-O powder. The titration curves were deconvoluted to attain the pKa distribution for each material at each ionic strength. The pKa distribution for the Al-O shows two distinct peaks at 4.8 and 7.5, which are invariant with ionic strength. The pKa distribution of clays was highly variable between the different minerals and as a function of ionic strength. Iodide sorption experiments were completed at high solid:solution ratios to exacerbate sorption properties. Palygorskite and kaolinite had the highest amount of iodide sorption and montmorillonite had the least. (authors)

Feasibility of using overburden clays for sealing purposes and laboratory testing of the clays

Energy Technology Data Exchange (ETDEWEB)

Mann, J. (Vyzkumny Ustav pro Hnede Uhli, Most (Czechoslovakia))

1992-03-01

Studies properties of overburden clay from North Bohemian surface coal mines for use as sealants of industrial and household waste that will be dumped at Czechoslovak surface mine sites. Basic requirements of sealing layers are optimum compressibility and impermeability by suitable compacting. Laboratory soil mechanical tests of different clay samples were carried out using the Proctor standard tests (PCS) and the Norwegian Geonor A/S - m 45 instrument. Laboratory tests were used to select the best available clay types with optimum density and moisture content. Experimental results of laboratory tests are provided.

Organophilization and characterization of commercial bentonite clays

International Nuclear Information System (INIS)

Cunha, B.B. da; Lima, J.C.C.; Alves, A.M.; Araujo, E.M.; Melo, T.J.A. de

2012-01-01

Bentonite clay is a plastic changes resulting from volcanic ash, consisting mostly of montmorillonite. The state of Paraiba is a major source of bentonite clay from Brazil, where the main oil fields are located in Boa Vista and represents the largest national production of raw and beneficiated bentonite. Aimed at the commercial value of this type of clay and its high applicability in the polls, this article aims to make a comparison between two kinds of clay, a national (Brasgel) and other imported (Cloisite) from organophilization of two commercial bentonite, ionic surfactant with Praepagem WB, and characterize them by XRD, FTIR and TG / DTG. We observe that despite getting inferior properties, the clay presents national values very similar to those presented by imported clay. (author)

Thermal Behaviour of clay formations

International Nuclear Information System (INIS)

Tassoni, E.

1985-01-01

The programme carried out by ENEA to model the thermal-hydraulic-mechanical behaviour of the clay formations and to measure, in situ and in laboratory, the thermal properties of these rocks, is presented. An in situ heating experiment has been carried out in an open clay quarry in the area of Monterotondo, near Rome. The main goal of the experiment was to know the temperature field and the thermal effects caused by the high level radioactive waste disposed of in a clayey geological formation. The conclusions are as follows: - the thermal conduction codes are sufficiently accurate to forecast the temperature increases caused in the clay by the dissipation of the heat generated by high level radioactive waste; - the thermal conductivity deduced by means of the ''curve fitting'' method ranges from 0.015 to 0.017 W.cm -1 . 0 C -1 - the temperature variation associated with the transport of clay interstitial water caused by temperature gradient is negligible. A laboratory automated method has been designed to measure the thermal conductivity and diffusivity in clay samples. A review of experimental data concerning thermomechanical effects in rocks as well as results of thermal experiments performed at ISMES on clays are presented. Negative thermal dilation has been found both in the elastic and plastic range under constant stress. Thermoplastic deformation appears ten times greater than the thermoelastic one. A mathematical model is proposed in order to simulate the above and other effects that encompass thermal-elastic-plastic-pore water pressure response of clays at high temperature and effective pressure with undrained and transient drainage conditions. Implementation of the two versions into a finite element computer code is described

Silt-clay aggregates on Mars

International Nuclear Information System (INIS)

Greeley, R.

1979-01-01

Viking observations suggest abundant silt and clay particles on Mars. It is proposed that some of these particles agglomerate to form sand size aggregates that are redeposited as sandlike features such as drifts and dunes. Although the binding for the aggregates could include salt cementation or other mechanisms, electrostatic bonding is considered to be a primary force holding the aggregates together. Various laboratory experiments conducted since the 19th century, and as reported here for simulated Martian conditions, show that both the magnitude and sign of electrical charges on windblown particles are functions of particle velocity, shape and composition, atmospheric pressure, atmospheric composition, and other factors. Electrical charges have been measured for saltating particles in the wind tunnel and in the field, on the surfaces of sand dunes, and within dust clouds on earth. Similar, and perhaps even greater, charges are proposed to occur on Mars, which could form aggregates of silt and clay size particles. Electrification is proposed to occur within Martian dust clouds, generating silt-clay aggregates which would settle to the surface where they may be deposited in the form of sandlike structures. By analog, silt-clay dunes are known in many parts of the earth where silt-clay aggregated were transported by saltation and deposited as 'sand.' In these structures the binding forces were later destroyed, and the particles reassumed the physical properties of silt and clay, but the sandlike bedding structure within the 'dunes' was preserved. The bedding observed in drifts at the Viking landing site is suggested to result from a similar process involving silt-clay aggregates on Mars

Reconstruction of tritium release history from contaminated groundwater using tree ring analysis

International Nuclear Information System (INIS)

Kalin, R.M.; Murphy, C.E. Jr.; Hall, G.

1995-01-01

The history of tritium releases to the groundwater from buried waste was reconstructed through dendrochronology. Wood from dated tree rings was sectioned from a cross-section of a tree that was thought to tap the groundwater. Cellulose was chemically separated from the wood. The cellulose was combusted and the water of combustion collected for liquid scintillation counting. The tritium concentration in the rings rose rapidly after 1972 which was prior to the first measurements made in this area. Trends in the tritium concentration of water outcropping to the surface are similar to the trends in tritium concentration in tree rings. 14 refs., 3 figs

What Makes a Natural Clay Antibacterial?

Science.gov (United States)

Williams, Lynda B.; Metge, David W.; Eberl, Dennis D.; Harvey, Ronald W.; Turner, Amanda G.; Prapaipong, Panjai; Poret-Peterson, Amisha T.

2011-01-01

Natural clays have been used in ancient and modern medicine, but the mechanism(s) that make certain clays lethal against bacterial pathogens has not been identified. We have compared the depositional environments, mineralogies, and chemistries of clays that exhibit antibacterial effects on a broad spectrum of human pathogens including antibiotic resistant strains. Natural antibacterial clays contain nanoscale (clay minerals in the bactericidal process is to buffer the aqueous pH and oxidation state to conditions that promote Fe2+ solubility. Chemical analyses of E. coli killed by aqueous leachates of an antibacterial clay show that intracellular concentrations of Fe and P are elevated relative to controls. Phosphorus uptake by the cells supports a regulatory role of polyphosphate or phospholipids in controlling Fe2+. Fenton reaction products can degrade critical cell components, but we deduce that extracellular processes do not cause cell death. Rather, Fe2+ overwhelms outer membrane regulatory proteins and is oxidized when it enters the cell, precipitating Fe3+ and producing lethal hydroxyl radicals. PMID:21413758

Multielemental analyses of tree rings by inductively coupled plasma mass spectrometry

International Nuclear Information System (INIS)

Hall, G.S.

1990-01-01

Inductively coupled plasma mass spectrometry (ICP-MS) was evaluated for major, minor, trace, and ultra-trace elemental analyses of individual tree rings. The samples were obtained from an old-growth Douglas fir growing near Mount St. Helens volcano, and from trees at various other North American sites. Eightly percent of elements from Li to U had detection limits in the solid (wood) below 8.0 ng g -1 . Two anomalous peaks occur in Mount St. Helens samples at A.D. 1478 and 1490 that closely correlate with past eruptions of the volcano. These results show that ICP-MS is a rapid and sensitive analytical method for multielemental analyses of individual tree rings. (author) 16 refs.; 2 figs.; 2 tabs

Iodide uptake by negatively charged clay interlayers?

International Nuclear Information System (INIS)

Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

2015-01-01

Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI (aq) ) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. - Highlights: • Iodide sorption experiments were completed with a diverse array of clay minerals. • Iodide uptake trended with CEC and swamping electrolyte identity and concentration. • Results can be explained by considering the formation of ion pairs in clay interlayers

Stools - pale or clay-colored

Science.gov (United States)

... gov/ency/article/003129.htm Stools - pale or clay-colored To use the sharing features on this page, please enable JavaScript. Stools that are pale, clay, or putty-colored may be due to problems ...

Mars, clays and the origins of life

Science.gov (United States)

Hartman, Hyman

1989-01-01

To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

Preparation of organophilic clays and polypropylene nano composites

International Nuclear Information System (INIS)

Lima, Martha Fogliato S.; Nascimento, Vinicius G. do; Lenz, Denise M.; Schenato, Flavia

2011-01-01

Polypropylene/montmorillonite nano composites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organo clay. The modified clays with the quaternary ammonium salts were introduced in a polypropylene matrix with 3 wt. % of clay. The interlayer distance (d001) of the clay particles were obtained by X- ray diffraction and the thermal stability of the systems were investigated by thermogravimetry. The organo clay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. (author)

Tree rings as monitors of heavy metal air pollution histories

International Nuclear Information System (INIS)

Kennedy, G.; Bergeron, S.

1991-01-01

The potential of five species of trees as historical monitors of heavy metal air pollution has been investigated. The study was carried out at a site 2 km from an industrial complex including several metal refineries. Using neutron activation, heavy metal concentrations were measured in the xylem as a function of the year of wood formation. The manganese concentrations were by far the highest. In maple trees the high natural level of this essential trace element masked any increases due to pollution. In ash and cedar increased Mn concentrations were found, relative to control trees, but there is evidence for radial translocation. In hemlock the time variations of the average Mn concentrations followed the production rates of the refineries but large variations among individual trees were observed. Hemlock was estimated to accumulate up to 0.3% of the atmospheric Mn input. (author) 13 refs.; 3 figs

Hydrogen isotope ratios of clay minerals constituting clay veins found in granitic rocks in Hiroshima Prefecture

International Nuclear Information System (INIS)

Kitagawa, Ryuji; Kakitani, Satoru; Kuroda, Yoshimatsu; Matsuo, Sadao; Suzuoki, Tetsuro.

1980-01-01

The deuterium content of the constitutional and interlayer water extracted from the clay minerals (illite, montmorillonite, interstratified illite-montmorillonite mineral, kaolinite, halloysite) constituting the clay veins found in the granitic rocks in Hiroshima Prefecture was measured. The clay minerals were heated at 270 deg C to extract the interlayer water, then heated to 1,400 or 1,500 deg C to extract the constitutional water. The deuterium content of the local surface water collected from sampling points was measured. In the clay veins formed along perpendicular joints, the constituent clay minerals change from lower to upper part: illite → montmorillonite → kaolinite → halloysite. The deuterium content values of the constitutional water for illite and montmorillonite were estimated to be -67 to -69% and -86 to -89%, respectively. The deuterium content values of the constitutional water for halloysite range from -68 to -80% and for kaolinite from -63 to -67%. (J.P.N.)

FiGS: a filter-based gene selection workbench for microarray data

Directory of Open Access Journals (Sweden)

Yun Taegyun

2010-01-01

Full Text Available Abstract Background The selection of genes that discriminate disease classes from microarray data is widely used for the identification of diagnostic biomarkers. Although various gene selection methods are currently available and some of them have shown excellent performance, no single method can retain the best performance for all types of microarray datasets. It is desirable to use a comparative approach to find the best gene selection result after rigorous test of different methodological strategies for a given microarray dataset. Results FiGS is a web-based workbench that automatically compares various gene selection procedures and provides the optimal gene selection result for an input microarray dataset. FiGS builds up diverse gene selection procedures by aligning different feature selection techniques and classifiers. In addition to the highly reputed techniques, FiGS diversifies the gene selection procedures by incorporating gene clustering options in the feature selection step and different data pre-processing options in classifier training step. All candidate gene selection procedures are evaluated by the .632+ bootstrap errors and listed with their classification accuracies and selected gene sets. FiGS runs on parallelized computing nodes that capacitate heavy computations. FiGS is freely accessible at http://gexp.kaist.ac.kr/figs. Conclusion FiGS is an web-based application that automates an extensive search for the optimized gene selection analysis for a microarray dataset in a parallel computing environment. FiGS will provide both an efficient and comprehensive means of acquiring optimal gene sets that discriminate disease states from microarray datasets.

Pedological ~cterization, Clay Mine:at~ and .~cation of,

African Journals Online (AJOL)

namely, very deep, well drained, dark reddish brown to dark brown, sandy clay loams and sandy clays on the steep convex slopes; very deep, well drained, dark brown to dark red, sandy clay loams and; sandy clays on the linear slopes; and very ...

Preparation and characterization of bentonite organo clay

International Nuclear Information System (INIS)

Bertagnolli, C.; Almeida Neto, A.F.; Silva, M.G.C.

2009-01-01

Bentonite clays organically modified have great potential use for environmental remediation, especially in the separation of organic compounds from the water. The aim of this work was the preparation of organophilic clays from 'Verde-Lodo' bentonite clay with the quaternary ammonium salts cetyl-pyridinium chloride and benzalkonium chloride. The materials obtained were characterized by XRD, thermogravimetric analyses, Helium picnometry, SEM and energy dispersive X-ray techniques. The results show consistently successful synthesis of the organoclay through the increase in the basal spacing, as well as salt elimination picks and presence of carbon and chlorine in the modified clays; they are inexistent elements in the natural clay. (author)

Treatment for cracked and permeable Houston clay

International Nuclear Information System (INIS)

Vipulanandan, C.; Leung, M.

1991-01-01

In this study, the treatability of a field clay (obtained from Houston, Texas) and a clay-sand mixture to reduce their hydraulic conductivity was evaluated. Remolded field clay and clay-sand mixture with and without methanol contamination were treated to reduce their hydraulic conductivity by permeating very dilute grout solutions. The concentration of sodium silicate in the grout solution was 8%, while the solid content in the cement grout was 0.3%. The hydraulic conductivity of permeable Houston clay (hydraulic conductivity >10 -5 cm/sec) could be reduced to less than 10 -7 cm/sec (U.S. EPA limit for soil barriers) by permeating with a selected combination of grout solutions

Characterization of clay used for red ceramic fabrication

International Nuclear Information System (INIS)

Pereira, P.S.; Morais, A.S.C.; Caldas, T.C.C.; Monteiro, S.N.; Vieira, C.M.F.

2011-01-01

The objective of this work is to characterize a clay used in the red ceramics fabrication, from Campos dos Goytacazes north of the State of Rio de Janeiro. The clay was submitted for physical, chemical and mineralogical tests. The results showed that the clay has a high content of clay minerals with kaolinitic predominance, high loss on ignition and low flux oxides. It is recommended that this clay is mixed with non-plastic materials. (author)

Encapsulation of Clay Platelets inside Latex Particles

NARCIS (Netherlands)

Voorn, D.J.; Ming, W.; Herk, van A.M.; Fernando, R.H.; Sung, Li-Piin

2009-01-01

We present our recent attempts in encapsulating clay platelets inside latex particles by emulsion polymerization. Face modification of clay platelets by cationic exchange has been shown to be insufficient for clay encapsulation, leading to armored latex particles. Successful encapsulation of

Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

Science.gov (United States)

Moran, Anthony R.; Hettiarachchi, Hiroshan

2011-01-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling. PMID:21845150

Geotechnical characterization of mined clay from Appalachian Ohio: challenges and implications for the clay mining industry.

Science.gov (United States)

Moran, Anthony R; Hettiarachchi, Hiroshan

2011-07-01

Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL) in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

Geotechnical Characterization of Mined Clay from Appalachian Ohio: Challenges and Implications for the Clay Mining Industry

Directory of Open Access Journals (Sweden)

Anthony R. Moran

2011-06-01

Full Text Available Clayey soil found in coal mines in Appalachian Ohio is often sold to landfills for constructing Recompacted Soil Liners (RSL in landfills. Since clayey soils possess low hydraulic conductivity, the suitability of mined clay for RSL in Ohio is first assessed by determining its clay content. When soil samples are tested in a laboratory, the same engineering properties are typically expected for the soils originated from the same source, provided that the testing techniques applied are standard, but mined clay from Appalachian Ohio has shown drastic differences in particle size distribution depending on the sampling and/or laboratory processing methods. Sometimes more than a 10 percent decrease in the clay content is observed in the samples collected at the stockpiles, compared to those collected through reverse circulation drilling. This discrepancy poses a challenge to geotechnical engineers who work on the prequalification process of RSL material as it can result in misleading estimates of the hydraulic conductivity of the samples. This paper describes a laboratory investigation conducted on mined clay from Appalachian Ohio to determine how and why the standard sampling and/or processing methods can affect the grain-size distributions. The variation in the clay content was determined to be due to heavy concentrations of shale fragments in the clayey soils. It was also concluded that, in order to obtain reliable grain size distributions from the samples collected at a stockpile of mined clay, the material needs to be processed using a soil grinder. Otherwise, the samples should be collected through drilling.

Sorption of Pu onto some kinds of clay

International Nuclear Information System (INIS)

Jia Haihong; Si Gaohua; Liu Wei; Yu Jing

2010-01-01

There are rich clay mines holding in one area, so it's necessary to know about these clays' sorption capacity to Pu, for building radioactive waste repository in the area. Distribution coefficients of Pu onto different clays were acquired in static method, with the result about 104. The size of clay is different, but the result of Kds is near. In addition, it's estimated how far Pu moves in the most rapid speed in the clay based on these Kids', disregarding the influence of Pu-colloid. In a word, as a kind of backfilling material clays in the area can effectively prevent Pu from moving to environment, and when designing the backfilling layer, it's not necessary to catch clays through NO.200 sieve, if only considering the influence of Kd. (authors)

Rheological characterization of nanocomposites Nylon 6/bentonite clay

International Nuclear Information System (INIS)

Silva, T.R.G.; Fernandes, P.C.; Oliveira, S.V.; Araujo, E.M.; Melo, T.J.A.

2010-01-01

Polymer nanocomposites are a class of materials that have been widely used in various applications. Among them, has been emphasizing the preparation of polymer films with barrier properties for applications in polymer membranes. In this work, nanocomposites of nylon 6/bentonite clay were obtained from a Homogenizer, in the ratios of 1, 3 and 5 wt% clay. The Brasgel PA bentonite clay was treated organically with Praepagen HY salt, to make it organophilic. By X-ray diffraction (XRD), it was showed that the efficiency of the incorporation of salt in the clay. The rheological curves showed that for the AST clay the torque did not change when compared with the pure nylon 6, while for the clay ACT, the torque increased gradually with the percentage of clay. (author)

21 CFR 145.130 - Canned figs.

Science.gov (United States)

2010-04-01

..., a mixture of brown sugar and honey, the statement “___ sirup of brown sugar and honey” the blank to... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Canned figs. 145.130 Section 145.130 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN...

Polymer-clay nanocomposites obtained by solution polymerization ...

Indian Academy of Sciences (India)

Clay minerals can be found all over the world.1 Clay minerals have ... salts or covalent bonding with silanes at the OH edges of the clay. ..... Marras S I, Tsimpliaraki A, Zuburtikudis I and ... Mansoori Y, Roojaei K, Zamanloo M R and Imanzadeh.

Wood specific gravity and anatomy of branches and roots in 113 Amazonian rainforest tree species across environmental gradients.

Science.gov (United States)

Fortunel, Claire; Ruelle, Julien; Beauchêne, Jacques; Fine, Paul V A; Baraloto, Christopher

2014-04-01

Wood specific gravity (WSG) is a strong predictor of tree performance across environmental gradients. Yet it remains unclear how anatomical elements linked to different wood functions contribute to variation in WSG in branches and roots across tropical forests. We examined WSG and wood anatomy in white sand, clay terra firme and seasonally flooded forests in French Guiana, spanning broad environmental gradients found throughout Amazonia. We measured 15 traits relating to branches and small woody roots in 113 species representing the 15 most abundant species in each habitat and representative species from seven monophyletic lineages occurring in all habitats. Fiber traits appear to be major determinants of WSG, independent of vessel traits, in branches and roots. Fiber traits and branch and root WSG increased from seasonally flooded species to clay terra firme species and lastly to white sand species. Branch and root wood traits were strongly phylogenetically constrained. Lineages differed in wood design, but exhibited similar variation in wood structure across habitats. We conclude that tropical trees can invest differently in support and transport to respond to environmental conditions. Wind disturbance and drought stress represent significant filters driving tree distribution of Amazonian forests; hence we suggest that biophysical explanations should receive more attention. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Hydro-mechanical properties of the red salt clay (T4) - Natural analogue of a clay barrier

International Nuclear Information System (INIS)

Minkley, W.; Popp, T.; Salzer, K.; Gruner, M.; Boettge, V.

2010-01-01

Document available in extended abstract form only. Long-term storage of high-level radioactive waste in deep geologic formations is worldwide the only accepted solution to warranty long term safety. Besides clay and crystalline rocks, salt is one of the potential host-rock candidates, mainly favored in Germany. As salts rocks are highly soluble their barrier integrity against water inflow from the cap rock is questionable. Argillaceous cap rocks or intercalated clay layers may act as protective shield in the hanging wall above a repository, thus providing a multi-barrier system. The aims of our study are twofold: 1) to characterize the mineralogical, hydraulic and rock-mechanical properties of the so-called Red Salt Clay (T4) as natural analogue of a clay barriers represented by different states of induration corresponding to various depth of burial diagenesis; 2) to demonstrate the favoured barrier properties of an argillaceous layer in the top of a salt formation undergoing dynamic processes such as rock bursts. The so-called Red Salt Clay (T4) is deposited as clay rich clastic sediment at the base of the Aller-series forming a persistent lateral layer above the lower Zechstein-series. The thickness of the clay-formation becomes smaller with decreasing distance from the border of the basin, i.e. from ∼15 m at Rossleben, over 7 m at Bernburg to 3.5 m at Zielitz, all in Saxony-Anhalt, D). The mineralogical composition of the Red Salt Clay varies, e.g. average composition for the Teutschenthal area: clay minerals 54% (Chlorite: 8%; Illite/Muscovite: 46%); quartz: 22%; anhydrite: 15%; accessory gypsum; Halite: 6%, Hematite: ∼ 2%). The geochemical and mineralogical composition of the Red Salt Clay represents a final state of natural salt-clay-systems, thus standing as a natural analogue for bentonite-based sealing systems in contact with high-saline solutions (e.g. saturated NaCl-solution, solutions with various Mg 2+ -, K + -, SO 4 2- - concentrations). The

Uptake and distribution of soil applied zinc by citrus trees-addressing fertilizer use efficiency with 68Zn labeling.

Science.gov (United States)

Hippler, Franz Walter Rieger; Boaretto, Rodrigo Marcelli; Quaggio, José Antônio; Boaretto, Antonio Enedi; Abreu-Junior, Cassio Hamilton; Mattos, Dirceu

2015-01-01

The zinc (Zn) supply increases the fruit yield of Citrus trees that are grown, especially in the highly weathered soils of the tropics due to the inherently low nutrient availability in the soil solution. Leaf sprays containing micronutrients are commonly applied to orchards, even though the nutrient supply via soil could be of practical value. This study aimed to evaluate the effect of Zn fertilizers that are applied to the soil surface on absorption and partitioning of the nutrient by citrus trees. A greenhouse experiment was conducted with one-year-old sweet orange trees. The plants were grown in soils with different textures (18.1 or 64.4% clay) that received 1.8 g Zn per plant, in the form of either ZnO or ZnSO4 enriched with the stable isotope 68Zn. Zinc fertilization increased the availability of the nutrient in the soil and the content in the orange trees. Greater responses were obtained when ZnSO4 was applied to the sandy loam soil due to its lower specific metal adsorption compared to that of the clay soil. The trunk and branches accumulated the most fertilizer-derived Zn (Zndff) and thus represent the major reserve organ for this nutrient in the plant. The trees recovered up to 4% of the applied Zndff. Despite this relative low recovery, the Zn requirement of the trees was met with the selected treatment based on the total leaf nutrient content and increased Cu/Zn-SOD activity in the leaves. We conclude that the efficiency of Zn fertilizers depends on the fertilizer source and the soil texture, which must be taken into account by guidelines for fruit crop fertilization via soil, in substitution or complementation of traditional foliar sprays.

Uptake and distribution of soil applied zinc by citrus trees-addressing fertilizer use efficiency with 68Zn labeling.

Directory of Open Access Journals (Sweden)

Franz Walter Rieger Hippler

Full Text Available The zinc (Zn supply increases the fruit yield of Citrus trees that are grown, especially in the highly weathered soils of the tropics due to the inherently low nutrient availability in the soil solution. Leaf sprays containing micronutrients are commonly applied to orchards, even though the nutrient supply via soil could be of practical value. This study aimed to evaluate the effect of Zn fertilizers that are applied to the soil surface on absorption and partitioning of the nutrient by citrus trees. A greenhouse experiment was conducted with one-year-old sweet orange trees. The plants were grown in soils with different textures (18.1 or 64.4% clay that received 1.8 g Zn per plant, in the form of either ZnO or ZnSO4 enriched with the stable isotope 68Zn. Zinc fertilization increased the availability of the nutrient in the soil and the content in the orange trees. Greater responses were obtained when ZnSO4 was applied to the sandy loam soil due to its lower specific metal adsorption compared to that of the clay soil. The trunk and branches accumulated the most fertilizer-derived Zn (Zndff and thus represent the major reserve organ for this nutrient in the plant. The trees recovered up to 4% of the applied Zndff. Despite this relative low recovery, the Zn requirement of the trees was met with the selected treatment based on the total leaf nutrient content and increased Cu/Zn-SOD activity in the leaves. We conclude that the efficiency of Zn fertilizers depends on the fertilizer source and the soil texture, which must be taken into account by guidelines for fruit crop fertilization via soil, in substitution or complementation of traditional foliar sprays.

Utilization of Nkpuma-Akpatakpa clay in ceramics: characterization ...

African Journals Online (AJOL)

Nkpuma – Akpatakpa clay was analysed for its ceramics suitability. Chemical, mechanical and spectral characterization of the clay was carried out to obtain more information from this clay found in commercial quantity at Ebonyi State Nigeria. The XRD analysis showed that the principal minerals in the clay are quartz, ...

Preparation and properties of recycled HDPE/clay hybrids

Science.gov (United States)

Yong Lei; Qinglin Wu; Craig M. Clemons

2007-01-01

Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could...

Iodide uptake by negatively charged clay interlayers?

Science.gov (United States)

Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

2015-09-01

Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. Copyright © 2015 Elsevier Ltd. All rights reserved.

generalized constitutive model for stabilized quick clay

African Journals Online (AJOL)

QUICK CLAY. PANCRAS MUGISHAGWE BUJULU AND GUSTAV GRIMSTAD. ABSTRACT. An experimentally-based two yield surface constitutive model for cemented quick clay has been ... Clay Model, the Koiter Rule and two Mapping Rules. .... models, where a mobilization formulation is used, this is independent of q.

Search for methylation-sensitive amplification polymorphisms in mutant figs

OpenAIRE

Rodrigues, M. G F; Martins, A. B G [UNESP; Bertoni, B. W.; Figueira, A.; Giuliatti, S.

2013-01-01

Fig (Ficus carica) breeding programs that use conventional approaches to develop new cultivars are rare, owing to limited genetic variability and the difficulty in obtaining plants via gamete fusion. Cytosine methylation in plants leads to gene repression, thereby affecting transcription without changing the DNA sequence. Previous studies using random amplification of polymorphic DNA and amplified fragment length polymorphism markers revealed no polymorphisms among select fig mutants that ori...

Processes of cation migration in clay-rocks: Final Scientific Report of the CatClay European Project

International Nuclear Information System (INIS)

Altmann, S.; Aertsens, M.; Appelo, T.; Bruggeman, C.; Gaboreau, S.; Glaus, M.; Jacquier, P.; Kupcik, T.; Maes, N.; Montoya, V.; Rabung, T.; Robinet, J.-C.; Savoye, S.; Schaefer, T.; Tournassat, C.; Van Laer, L.; Van Loon, L.

2015-07-01

In the framework of the feasibility studies on the radioactive waste disposal in deep argillaceous formations, it is now well established that the transport properties of solutes in clay rocks, i.e. parameter values for Fick's law, are mainly governed by the negatively charged clay mineral surface. While a good understanding of the diffusive behaviour of non-reactive anionic and neutral species is now achieved, much effort has to be placed on improving understanding of coupled sorption/diffusion phenomena for sorbing cations. Indeed, several cations known to form highly stable surface complexes with sites on mineral surfaces migrate more deeply into clay rock than expected. Therefore, the overall objective of the EC CatClay project is to address this issue, using a 'bottom-up' approach, in which simpler, analogous systems (here a compacted clay, 'pure' illite) are experimentally studied and modelled, and then the transferability of these results to more complex materials, i.e. the clay rocks under consideration in France, Switzerland and Belgium for hosting radioactive waste disposal facilities, is verified. The cations of interest were chosen for covering a representative range of cations families: from a moderately sorbing cation, the strontium, to three strongly sorbing cations, Co(II), Zn(II) and Eu(III). For the 4 years of this project, much effort was devoted to developing and applying specific experimental methods needed for acquiring the high precision, reliable data needed to test the alternative hypotheses represented by different conceptual-numerical models. The enhanced diffusion of the sorbing cations of interest was confirmed both in the simpler analogous illite system for Sr 2+ , Co(II) and Zn(II), but also in the natural clay rocks, except for Eu(III). First modelling approach including diffusion in the diffuse double layer (DDL) promisingly succeeded in reproducing the experimental data under the various conditions both in

Clay-Enriched Silk Biomaterials for Bone Formation

Science.gov (United States)

Mieszawska, Aneta J.; Llamas, Jabier Gallego; Vaiana, Christopher A.; Kadakia, Madhavi P.; Naik, Rajesh R.; Kaplan, David L.

2011-01-01

The formation of silk protein/clay composite biomaterials for bone tissue formation is described. Silk fibroin serves as an organic scaffolding material offering mechanical stability suitable for bone specific uses. Clay montmorillonite (Cloisite ® Na+) and sodium silicate are sources of osteoinductive silica-rich inorganic species, analogous to bioactive bioglass-like bone repair biomaterial systems. Different clay particle-silk composite biomaterial films were compared to silk films doped with sodium silicate as controls for support of human bone marrow derived mesenchymal stem cells (hMSCs) in osteogenic culture. The cells adhered and proliferated on the silk/clay composites over two weeks. Quantitative real-time RT-PCR analysis revealed increased transcript levels for alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col I) osteogenic markers in the cells cultured on the silk/clay films in comparison to the controls. Early evidence for bone formation based on collagen deposition at the cell-biomaterial interface was also found, with more collagen observed for the silk films with higher contents of clay particles. The data suggest that the silk/clay composite systems may be useful for further study toward bone regenerative needs. PMID:21549864

Influence of non-clay minerals on the interaction between metallic iron and Callovo-Oxfordian clay fraction

International Nuclear Information System (INIS)

Rivard, C.; Pelletier, M.; Villieras, F.; Michau, N.

2012-01-01

Document available in extended abstract form only. In the context of the geological disposal of high-level radioactive waste, it is of prime importance to understand the interaction mechanisms between the geological matrix, Callovo-Oxfordian clay rock (COx) and metallic iron, from the package overpack. In order to evidence the individual role of each clay component entering in the mineralogy of the COx, interactions between metallic iron and pure clays (smectites, illite and kaolinite) were first conducted. To investigate the role of the other minerals, the reactivity of COx, COx clay fraction (COxCF) and mixtures between COxCF and quartz, calcite or pyrite, was studied. Clays and additional minerals were put in contact with powder metallic iron with a weight ratio iron:clay fixed at 1:3 and a clay:solution ratio of 1:20. Proportions of non-clay minerals were deduced from the average COx composition: 50% clays, 24.5% quartz, 24.5% calcite and 1% pyrite. Batch experiments were carried out in anoxic conditions at 90 deg. C in the presence of background electrolyte (NaCl 0.02 M.L -1 , CaCl 2 0.04 M.L -1 ) in Parr reactors for durations of one, three or nine months. After reaction, solid and liquid phases were separated by centrifugation and characterized by classical techniques combining chemical analyses (liquid analyses, transmission electron microscopy combined with Energy Dispersive of X-rays spectroscopy TEM-EDS), mineralogical (X-ray diffraction), spectroscopic ( 57 Fe Moessbauer) and morphometric techniques (TEM, scanning electron microscopy and N 2 adsorption). For COx, COxCF and all the pure clay phases, major evolutions were observed during the first month, which shows that the oxidation of metallic iron is rapid in our experimental conditions. Release of iron cations in solution, pH increase (8-10) and Eh decrease (reductive conditions) are responsible for the partial dissolution of initial clay phases. Released iron is involved in the crystallization of Fe

Strength Properties of Aalborg Clay

DEFF Research Database (Denmark)

Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

glacial time are characterised by the absence of this mussel. These deposits are named Aalborg Clay and Aalborg Sand. In the city of Aalborg, a fill layer superposes Aalborg Clay. This layer is at some places found to be 6m thick. This fill layer does not provide sufficient bearing capacity, which has...... resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...

Mechanical interaction between swelling compacted clay and fractured rock, and the leaching of clay colloids

NARCIS (Netherlands)

Grindrod, P.; Peletier, M.A.; Takase, H.

1999-01-01

We consider the interaction between a saturated clay buffer layer and a fractured crystalline rock engineered disturbed zone. Once saturated, the clay extrudes into the available rock fractures, behaving as a compressible non-Newtonian fluid. We discuss the modelling implications of published

Tree Coring as a Complement to Soil Gas Screening to Locate PCE and TCE Source Zones and Hot Spots

DEFF Research Database (Denmark)

Nielsen, Mette Algreen; Trapp, Stefan; Rehne Jensen, Pernille

2015-01-01

) or trichloroethylene (TCE) to evaluate their ability to locate source zones and contaminant hot spots. One test site represented a relatively homogeneous sandy soil and aquifer, and the second a more heterogeneous geology with both sandy and less permeable clay till layers overlying a chalk aquifer. Tree cores from...

1st International Conference on Calcined Clays for Sustainable Concrete

CERN Document Server

Favier, Aurélie

2015-01-01

This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

Interphase vs confinement in starch-clay bionanocomposites.

Science.gov (United States)

Coativy, Gildas; Chevigny, Chloé; Rolland-Sabaté, Agnès; Leroy, Eric; Lourdin, Denis

2015-03-06

Starch-clay bionanocomposites containing 1-10% of natural montmorillonite were elaborated by melt processing in the presence of water. A complex macromolecular dynamics behavior was observed: depending on the clay content, an increase of the glass transition temperature and/or the presence of two overlapped α relaxation peaks were detected. Thanks to a model allowing the prediction of the average interparticle distance, and its comparison with the average size of starch macromolecules, it was possible to associate these phenomena to different populations of macromolecules. In particular, it seems that for high clay content (10%), the slowdown of segmental relaxation due to confinement of the starch macromolecules between the clay tactoïds is the predominant phenomenon. While for lower clay contents (3-5%), a significant modification of chain relaxation seems to occur, due to the formation of an interphase by the starch macromolecules in the vicinity of clay nanoparticles coexisting with the bulk polymer. Copyright © 2014 Elsevier Ltd. All rights reserved.

Soil clay content underlies prion infection odds

Science.gov (United States)

David, Walter W.; Walsh, D.P.; Farnsworth, Matthew L.; Winkelman, D.L.; Miller, M.W.

2011-01-01

Environmental factors-especially soil properties-have been suggested as potentially important in the transmission of infectious prion diseases. Because binding to montmorillonite (an aluminosilicate clay mineral) or clay-enriched soils had been shown to enhance experimental prion transmissibility, we hypothesized that prion transmission among mule deer might also be enhanced in ranges with relatively high soil clay content. In this study, we report apparent influences of soil clay content on the odds of prion infection in free-ranging deer. Analysis of data from prion-infected deer herds in northern Colorado, USA, revealed that a 1% increase in the clay-sized particle content in soils within the approximate home range of an individual deer increased its odds of infection by up to 8.9%. Our findings suggest that soil clay content and related environmental properties deserve greater attention in assessing risks of prion disease outbreaks and prospects for their control in both natural and production settings. ?? 2011 Macmillan Publishers Limited. All rights reserved.

Economic Cost-Analysis of the Impact of Container Size on Transplanted Tree Value

Directory of Open Access Journals (Sweden)

Lauren M. Garcia Chance

2017-04-01

Full Text Available The benefits and costs of varying container sizes have yet to be fully evaluated to determine which container size affords the most advantageous opportunity for consumers. To determine value of the tree following transplant, clonal replicates of Vitex agnus-castus L. [Chaste Tree], Acer rubrum L. var. drummondii (Hook. & Arn. ex Nutt. Sarg. [Drummond Red Maple], and Taxodium distichum (L. Rich. [Baldcypress] were grown under common conditions in each of five container sizes 3.5, 11.7, 23.3, 97.8 or 175.0 L, respectively (#1, 3, 7, 25 or 45. In June 2013, six trees of each container size and species were transplanted to a sandy clay loam field in College Station, Texas. To determine the increase in value over a two-year post-transplant period, height and caliper measurements were taken at the end of nursery production and again at the end of the second growing season in the field, October 2014. Utilizing industry standards, initial costs of materials and labor were then compared with the size of trees after two years. Replacement cost analysis after two growing seasons indicated a greater increase in value for 11.7 and 23.3 L trees compared to losses in value for some 175.0 L trees. In comparison with trees from larger containers, trees from smaller size containers experienced shorter establishment times and increased growth rates, thus creating a quicker return on investment for trees transplanted from the smaller container sizes.

Fig juice Fortified with Inulin and Lactobacillus Delbrueckii: A Promising Functional Food

Directory of Open Access Journals (Sweden)

Sima Khezri

2018-03-01

Full Text Available Background and Objective: Nowadays, consumption of functional foods is favored because of their health promoting characteristics. Also there is an increasing demand for nondairy products because of lactose intolerance in dairies. Fig juice as a source of dietary fiber and other nutrients would be a functional food. Adding probiotics and prebiotics makes it more functional for daily use. No study has yet been done on synbiotic fig juice. Accordingly, the aim of this study was to characterize synbiotic fig juice prepared by Lactobacillus delbrueckii and inulin.Material and Methods: Samples consisted of control fig juice; fig juice fermented by Lactobacillus delbrueckii (probiotic and fig juice containing inulin fermented by Lactobacillus delbrueckii (synbiotic were produced. Physico-chemical parameters, total phenolic content, antioxidant capacity and microbial survival aspects were analyzed during the fermentation period. Aforementioned parameters were also evaluated in 4 weeks with one-week time intervals. Sensory characteristics of fig juices were assessed in the second week of storage.Results and Conclusion: The results showed significant differences among treatments (p≤0.05 in physico-chemical indices during incubation and storage time. Total phenolic content and antioxidant capacity of fermented fig juices were significantly increased in comparison to the control samples (p≤0.05. Viability of Lactobacillus delbrueckii was increased in both probiotic and synbiotic treatments during incubation; but a significant reduction was observed during storage time. Sensory analysis revealed that there were significant differences in terms of odor, taste and overall acceptance between the fermented fig juices and control (p≤0.05 and the highest scores were obtained for control. Considering viable counts of Lactobacillus delbrueckii depicted that fermented fig juice could be a suitable medium for survival and proliferation of Lactobacillus

Radiation synthesis and characterization of thermo-sensitive PNIPA/clay hydrogels

International Nuclear Information System (INIS)

Song Hongyan; He Suqin; Liu Wentao; Zhu Chengshen; Yang Mingcheng

2007-01-01

In this work, the thermo-sensitive hydrogels of PNIPA/Clay were synthesized by 60 Co-γ rays irradiation. The effects of organically modified clay and Na + clay, clay content, and dispersing condition on swelling behavior of PNIPA/clay hydrogels were investigated. The results showed that the equilibrium swelling ratio (SR) of the PNIPA/clay hydrogels is better than PNIPA, and the SR of PNIPA/organically modified clay hydrogels is the highest. With clay content increases, the SR of hydrogels became better. The deswelling behavior of hydrogel was improved, the deswelling ratio of the hydrogel with organically modified clay is highest, and ratio of losing water is 83%, while PNIPA is about 50%. The compressive properties of hydrogel composites were also examined. The results showed that the compressive properties of the PNIPA/clay hydrogels were improved distinctly than that of the conventional hydrogels without clay. And with increasing of clay content, the compressive properties of hydrogel composites improve rapidly. When the content of clay is 15%, the maximum compression force of the PNIPA/clay hydrogel is 5.28N, which is 14 times of PNIPA hydrogel and compression strength is 2.5 times. (authors)

Fig Juice Fermented with Lactic Acid Bacteria as a Nutraceutical Product

Directory of Open Access Journals (Sweden)

Sima Khezri 1, Parvin Dehghan 2 * , Razzagh Mahmoudi 3, Mahdi Jafarlou 4

2016-12-01

Full Text Available Background: Probiotics are live microorganisms bringing useful effects to the host through balancing intestine microbiota. This research was undertaken to determine the suitability of fig juice as raw material for production of probiotic juice by three species of lactic acid bacteria (Lactobacillus casei, Lactobacillus plantarum and Lactobacillus delbrueckii. Methods: Heat treated fig juices were inoculated (6 log CFU/ml by three species inocula separately and incubated at 30 °C for 72 h. Changes in the pH, acidity, reducing sugar content and viable cell counts during the fermentation were monitored. Sensory characteristics of probiotic fig juice were also evaluated. Results: L. delbrueckii grew well on fig juice; reached nearly 9 log CFU/ml after 48 h of fermentation at 30 °C. After 4 weeks of cold storage at 4 °C, the viable cell counts of L. delbrueckii and L. plantarum were still 6 and 5 log CFU/ml, respectively, in fermented fig juice; but L. casei was just survived until 2th week of cold storage time, reduced from 9 to 3 log CFU/ml. The results of the sensory evaluation showed that fermented fig juice samples were significantly different (P<0.05 from the control sample in taste, odor, consistency and overall acceptability. L. casei was more acceptable comparing to the others. Conclusion: L. delbrueckii was the most suitable strain from the point of survivability among other species at the consumption time. Therefore, probiotic fig juice can serve as healthy beverage for vegetarians and consumers with lactose-allergy.

Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (volume 2)

International Nuclear Information System (INIS)

Baldi, G.; Hueckel, T.; Peano, A.; Pellegrini, R.

1991-01-01

This study is composed of two parts: The first part (Volume 1) lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton during thermal dilatation. The second part (volume 2) is devoted to the development and the application of advance constitutive modelling of mechanical behaviour of clays taking into account the extensive tests of Boom clay reported in the first volume. The development concentrated on the improvement of prediction of the volumetric response of clay skeleton: (a) improving the dilatancy prediction at low to high overconsolidation ratios (Section 2). An elasto-plastic constitutive model has been developed to account for this effect (Section 3.2.); (b) modelling of swelling effects (Section 2.5). A preliminary interpretative model for swelling prediction has been developed (Section 2.5). The application part consisted in interpreting the experimental results obtained for Boom clay to calibrate a set of constants (Section 3) for performing numerical analyses (Section 4) for the thermomechanical model already calibrated for Boom clay (Appendix). Interpretation of the tests required an assessment of influence of the strong anisotropy effects revealed by Boom clay on the basis of an interpretative model characterized by a kinematic hardening plasticity and coupled elasticity (section 3)

Investigations of salt mortar containing saliferous clay

International Nuclear Information System (INIS)

Walter, F.

1992-01-01

Saliferous clay mortar might be considered for combining individual salt bricks into a dense and tight long-term seal. A specific laboratory program was started to test mortars consisting of halite powder and grey saliferous clay of the Stassfurt from the Bleicherode salt mine. Clay fractions between 0 and 45% were used. The interest focused upon obtaining good workabilities of the mixtures as well as upon the permeability and compression strength of the dried mortar samples. Test results: 1) Without loss of quality the mortar can be mixed using fresh water. Apprx. 18 to 20 weight-% of the solids must be added as mixing water. 2) The porosity and the permeability of the mortar samples increases distinctly when equally coarse-grained salt power is used for mixing. 3) The mean grain size and the grain size distribution of the saliferous clay and the salt powder should be very similar to form a useful mortar. 4) The permeability of the mortar samples decreases with increasing clay fraction from 2 10 -12 m 2 to 2 10 -14 m 2 . The investigated samples, however, were large and dried at 100degC. 5) The uniaxial compressive strength of the clay mortar equals, at an average, only 4 MPa and decreases clearly with increasing clay fraction. Moist mortar samples did not show any measurable compressive strength. 6) Moistened saliferous clay mortar may show little temporary swelling. (orig./HP)

Philippine Fig wasps 1. Records and descriptions of Otitesellini (Hymenoptera Chalcidoidea, Torymidae)

NARCIS (Netherlands)

Wiebes, J.T.

1974-01-01

In 1964, by awarding to me that year's proceeds of the "Pieter Langerhuizen Fonds", the Hollandsche Maatschappij der Wetenschappen enabled me to study figs and fig wasps in the Philippines. While several Philippine fig wasps are already known from the papers by Ashmead (1904, 1905), Brown (1906),

Organic waste treatment with organically modified clays

International Nuclear Information System (INIS)

Evans, J.C.; Pancoski, S.E.; Alther, G.

1989-01-01

The use of organically modified clays in hazardous waste management applications offers a significant new and untapped potential. These clays may be used in the stabilization of organic wastes and organically contaminated soils, for waste water treatment, for oil spill control, for liner systems beneath fuel oil storage tanks, and as a component within liner systems of hazardous waste storage treatment and disposal facilities. Organically modified clays (organophilic clays) may be employed in each of these systems to adsorb organic waste constituents, enhancing the performance of the applications

Compressibility characteristics of Sabak Bernam Marine Clay

Science.gov (United States)

Lat, D. C.; Ali, N.; Jais, I. B. M.; Baharom, B.; Yunus, N. Z. M.; Salleh, S. M.; Azmi, N. A. C.

2018-04-01

This study is carried out to determine the geotechnical properties and compressibility characteristics of marine clay collected at Sabak Bernam. The compressibility characteristics of this soil are determined from 1-D consolidation test and verified by existing correlations by other researchers. No literature has been found on the compressibility characteristics of Sabak Bernam Marine Clay. It is important to carry out this study since this type of marine clay covers large coastal area of west coast Malaysia. This type of marine clay was found on the main road connecting Klang to Perak and the road keeps experiencing undulation and uneven settlement which jeopardise the safety of the road users. The soil is indicated in the Generalised Soil Map of Peninsular Malaysia as a CLAY with alluvial soil on recent marine and riverine alluvium. Based on the British Standard Soil Classification and Plasticity Chart, the soil is classified as a CLAY with very high plasticity (CV). Results from laboratory test on physical properties and compressibility parameters show that Sabak Bernam Marine Clay (SBMC) is highly compressible, has low permeability and poor drainage characteristics. The compressibility parameters obtained for SBMC is in a good agreement with other researchers in the same field.

Fracture behavior of polypropylene/clay nanocomposites.

Science.gov (United States)

Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

2006-12-01

Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

Preparation and properties of biodegradable starch–clay nanocomposites

KAUST Repository

Chung, Yi-Lin; Ansari, Seema; Estevez, Luis; Hayrapetyan, Suren; Giannelis, Emmanuel P.; Lai, Hsi-Mei

2010-01-01

Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn't significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

Preparation and properties of biodegradable starch–clay nanocomposites

KAUST Repository

Chung, Yi-Lin

2010-01-01

Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The clay didn\\'t significantly influence the type of crystalline structure of starch molecules although the amount of crystallinity appears to be somewhat lower in the nanocomposites. The nanocomposites show improved modulus and strength without a decrease in elongation at break. The increase in modulus and strength is 65% and 30%, respectively for the nanocomposite containing 5 wt.% clay compared to the unfilled starch materials. Further increases in clay result in deterioration in properties most likely due to poorer clay dispersion and lower polymer crystallinity. As the amount of water increases, the modulus of both pure starch and starch nanocomposites decreases, although the change is less pronounced in the nanocomposites suggesting that the addition of clay to form nanocomposites can improve the stability of starch-based products during transportation and storage. © 2009 Elsevier Ltd. All rights reserved.

Proceedings of the NEA Clay Club Workshop on Clay characterisation from nanoscopic to microscopic resolution

International Nuclear Information System (INIS)

2013-01-01

A wide spectrum of argillaceous media are being considered in Nuclear Energy Agency (NEA) member countries as potential host rocks for the final, safe disposal of radioactive waste, and/or as major constituent of repository systems in which wastes will be emplaced. In this context, the NEA established the Working Group on the 'Characterisation, the Understanding and the Performance of Argillaceous Rocks as Repository Host Formations' in 1990, informally known as the 'Clay Club'. The Clay Club examines various argillaceous rocks that are being considered for the underground disposal of radioactive waste, ranging from soft clays to indurated shales. Very generally speaking, these clay rocks are composed of fine-grained minerals showing pore sizes from < 2 nm (micropores) up to > 50 nm (macro-pores). The water flow, solute transport and mechanical properties are largely determined by this microstructure, the spatial arrangement of the minerals and the chemical pore water composition. Examples include anion accessible ('geochemical') porosity and macroscopic membrane effects (chemical osmosis, hyper-filtration), geomechanical properties and the characteristics of two-phase flow properties (relevant for gas transport). At the current level of knowledge, there is a strong need to improve the nanoscale description of the phenomena observed at a more macroscopic scale. However, based on the scale of individual clay-minerals and pore sizes, for most of the imaging techniques this resolution is a clear challenge. The workshop, hosted by the Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT) in the Akademiehotel Karlsruhe (Germany) from 6 to 8 September 2011, was intended to give, inter alia, a discussion platform on: - The current state-of-the-art of different spectro-microscopic methods - New developments addressing the above mentioned knowledge gaps in clays. - The perception of the interplay between geometry

Single clay sheets inside electrospun polymer nanofibers

Science.gov (United States)

Sun, Zhaohui

2005-03-01

Nanofibers were prepared from polymer solution with clay sheets by electrospinning. Plasma etching, as a well controlled process, was used to supply electrically excited gas molecules from a glow discharge. To reveal the structure and arrangement of clay layers in the polymer matrix, plasma etching was used to remove the polymer by controlled gasification to expose the clay sheets due to the difference in reactivity. The shape, flexibility, and orientation of clay sheets were studied by transmission and scanning electron microscopy. Additional quantitative information on size distribution and degree of exfoliation of clay sheets were obtained by analyzing electron micrograph of sample after plasma etching. Samples in various forms including fiber, film and bulk, were thinned by plasma etching. Morphology and dispersion of inorganic fillers were studied by electron microscopy.

A time-dependent event tree technique for modelling recovery operations

International Nuclear Information System (INIS)

Kohut, P.; Fitzpatrick, R.

1991-01-01

The development of a simplified time dependent event tree methodology is presented. The technique is especially applicable to describe recovery operations in nuclear reactor accident scenarios initiated by support system failures. The event tree logic is constructed using time dependent top events combined with a damage function that contains information about the final state time behavior of the reactor core. Both the failure and the success states may be utilized for the analysis. The method is illustrated by modeling the loss of service water function with special emphasis on the RCP [reactor coolant pump] seal LOCA [loss of coolant accident] scenario. 5 refs., 2 figs., 2 tabs

Ground water chlorinated ethenes in tree trunks: case studies, influence of recharge, and potential degradation mechanism

Science.gov (United States)

Don A. Vroblesky; Barton D. Clinton; James M. Vose; Clifton C. Casey; Gregory J. Harvey; Paul M. Bradley

2004-01-01

Trichloroethene (TCE) was detected in cores of trees growing above TCE-contaminated ground at three sites: the Carswell Golf Course in Texas, Air Force Plant PJKS in Colorado, and Naval Weapons Station Charleston in South Carolina. This was true even when the depth to water was 7.9 m or when the contaminated aquifer was confined beneath ~3 m of clay. Additional ground...

Dynamics and Scaling Properties of Fractures in clay-like Materials

Energy Technology Data Exchange (ETDEWEB)

Walmann, Thomas

1998-12-31

Computer models that can help oil companies predict realistic and physically correct fracture patterns are important. To verify such a model, experiments described in this thesis were undertaken, using wet clay and powder. The main focus was on extensional fractures, but other types of fractures were also studied. High resolution digital images of the fracture patterns were recorded and analyzed using statistical physics and fractal geometry. The characteristic shapes and size distributions of individual fractures and the overall fracture patterns obtained from laboratory model studies were compared to results from aerial photographs of a fracture pattern in a collapsed glacier that had undergone a similar deformation. A new scaling relation (a power-law) between the length of a fracture and the projected area is derived for fractures formed during clay model experiments. This scaling relation is found also in a field study of a fracture pattern in a glacier. The forms of the different distributions that characterizes fractures in clay experiments are discussed. Several characteristic lengths are associated with the laboratory experiments. They are related to the sample size and shape, the model material and the nature of the imposed deformation. The roughness of the fracture traces obtained from powder experiments was found to have a self-affine form. The roughness, or Hurst exponent, was found to have the value 0.73, plus or minus 0.09. A large number of interacting fractures were formed in the systems studied, and under such conditions the fluctuations about the direction perpendicular to the principle strain direction are influenced by neighbouring fractures. As expected, an upper cutoff for the scaling range was observed. But the length at which the crossover from a self-affine shape to a flat shape took place did not depend systematically on any of the experimental parameters or characteristic length scales. The total fracture trace patterns could not be

Comparing uranyl sorption complexes on soil and reference clays

International Nuclear Information System (INIS)

Chisholm-Brause, C.J.; Berg, J.M.; Conradson, S.D.; Morris, D.E.; McKinley, J.P.; Zachara, J.M.

1993-01-01

Clay minerals and other components in natural soils may play a key role in limiting the mobility of uranium in the environment through the formation of sorption complexes. Reference clays are frequently used as models to study sorption processes because they have well-known chemical and physical properties, but they may differ chemically and morphologically from clays derived from natural soils. Therefore, inferences based on reference clay data have been questioned. The authors have used luminescence and x-ray absorption spectroscopies to characterize the sorption complexes of aqueous uranyl (UO 2 2+ ) species on two soil smectites from the Kenoma and Ringold formations, and compared these results to those obtained on reference smectite clays. The pH dependence of uptake suggests that the ratio of sorption on amphoteric edge sites is greater for the soil smectites than for reference clays such as Wyoming montmorillonite (SWy-1). The luminescence spectra for uranyl sorbed to the soil clays are very similar to those for uranyl sorbed principally to the edge sites of SWy-1. This observation supports the solution data suggesting that adsorption to amphoteric sites is a more important mechanism for soil clays. However, the spectral data indicate that the sorption complexes on natural and reference clays are quite similar. Furthermore, as with the reference clays, the authors have found that the chemistry of the solution plays a greater role in defining the sorption complex than does the clay matrix. Thus, if differences in surface properties are adequately taken into account, the reference clays may serve as useful analogs for soil clays in investigations of metal-ion sorption

Investigations into the water flow and water conduction in spruce trees

International Nuclear Information System (INIS)

Strack, S.; Unger, H.

1988-02-01

The water-flow systems in the xylem of healthy and ailing spruce trees, based on the distribution patterns of tritiated water (HTO), were compared. In case of the ailing tree a severely altered water-flow system was observed. Whereas in the healthy tree the injected HTO spread in the apex in a distinctly differentiated manner following the spiral pattern of the ligneous fibers, no comparable spreading pattern was detected in the ailing tree. Also the labeled water molecules distributed twice as fast in the ailing as in the healthy tree. We conclude that the water conducting cross section of the diseased tree is reduced. Indeed, heartwood formation was about 60% in the ailing as compared to 5-20% in healthy trees. The methods of determining water content in the annual rings are described. The tissue water of needles from the healthy tree showed a distinct gradation of tritium concentrations according to age. This finding suggests that there is an age specific stomatal regulation in the healthy but not in the diseased needles. Water potential measurements at various times during the vegetation period provided evidence of a tighter water budget in diseased trees; however, a chronically enhanced water stress was not evident. The role of pathological heartwood formation during the disease is discussed. (orig.) With 27 figs., 38 refs [de

Clay Cuffman: A Cool, Calm, Relaxed Guy

Science.gov (United States)

Booth, Gina

2010-01-01

This article describes Clay Cuffman, a simple clay-sculpture project that requires two or three sessions, and works for students from the upper-elementary level through high school. It takes about 1.5 pounds of clay per student--about the size of a small grapefruit. The Cuffman project is a great way for upper-elementary through high-school…

Hygrothermal behavior for a clay brick wall

Science.gov (United States)

Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

2018-06-01

In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

Hygrothermal behavior for a clay brick wall

Science.gov (United States)

Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

2018-01-01

In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

Some Tests on Heather Field Moraine Clay

DEFF Research Database (Denmark)

Jørgensen, Mogens B.; Jacobsen, Moust

This report deals with oedometer tests on three samples of moraine clay from the Heather Field in the English part of the North Sea. The tests have been carried out in the very unelastic apparatus used in Denmark and with special test procedures differing from the ones used elsewhere. In Denmark...... Moraine Clay covers a large part of the surface, and it has therefore been investigated extensively in the field and in the laboratories during the last 25 years. It is to day - from a geotechnical point of view - the best known clay in Denmark. It could therefore be of some interest to compare...... the English North Sea moraine clays with the corresponding Danish Moraine Clays. The Danish test procedures are explained in details and some comments are given in the hope that they may not be banalities all of them....

Root-Zone Redox Dynamics - In Search for the Cause of Damage to Treated-Wastewater Irrigated Orchards in Clay Soils

Science.gov (United States)

Yalin, David; Shenker, Moshe; Schwartz, Amnon; Assouline, Shmuel; Tarchitzky, Jorge

2016-04-01

Treated wastewater (TW) has become a common source of water for agriculture. However recent findings raise concern regarding its use: a marked decrease (up to 40%) in yield appeared in orchards irrigated with TW compared with fresh water (FW) irrigated orchards. These detrimental effects appeared predominantly in orchards cultivated in clay soils. The association of the damage with clay soils rather than sandy soils led us to hypothesize that the damage is linked to soil aeration problems. We suspected that in clay soils, high sodium adsorption ratio (SAR) and high levels of organic material, both typical of TW, may jointly lead to an extreme decrease in soil oxygen levels, so as to shift soil reduction-oxidation (redox) state down to levels that are known to damage plants. Two-year continuous measurement of redox potential, pH, water tension, and oxygen were conducted in the root-zone (20-35 cm depth) of avocado trees planted in clay soil and irrigated with either TW or FW. Soil solution composition was sampled periodically in-situ and mineral composition was sampled in tree leaves and woody organs biannually. In dry periods the pe+pH values indicated oxic conditions (pe+pH>14), and the fluctuations in redox values were small in both TW and FW plots. Decreases in soil water tension following irrigation or rain were followed by drops in soil oxygen and pe+pH values. TW irrigated plots had significantly lower minimum pe+pH values compared with FW-irrigated plots, the most significant differences occurred during the irrigation season rather than the rain season. A linear correlation appeared between irrigation volume and reduction severity in TW-irrigated plots, but not in the FW plots, indicating a direct link to the irrigation regime in TW-irrigated plots. The minimum pe+pH values measured in the TW plots are indicative of suboxic conditions (9water tension and oxygen concentration levels. The consequences of our findings to plant health will be discussed, and

Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

Science.gov (United States)

Sarabadani, Hamid; Rayhani, Mohammad T

2014-06-01

Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

KARAKTERISTIK MORFOLOGI SERTA PERKEMBANGAN FIG NYAWAI (Ficus variegata Blume DI KEBUN RAYA CIBODAS

Directory of Open Access Journals (Sweden)

Agus Astho Pramono

2015-12-01

Full Text Available Nyawai (Ficus variegata Blume merupakan salah satu jenis pohon yang memiliki prospek yang baik untuk hutan tanaman. Informasi tentang aspek biologi reproduksinya masih terbatas. Penelitian ini bertujuan untuk mengetahui karakteristik morfologi bunga dan buah nyawai, serta tahapan perkembangan fig. Penelitian dilakukan di Kebun Raya Cibodas, Jawa Barat. Kegiatan penelitian meliputi: 1 pengamatan morfologi bunga dan buah, dan 2 pengamatan perkembangan fig. Hasil penelitian menunjukkan bahwa karakteristik morfologi fig nyawai yang dijumpai di Kebun Raya Cibodas, memiliki variasi yang tinggi dalam hal ukuran dan warna. Berdasarkan karakteristik morfologi bunga, secara individual ditemui dua tipe pohon yang mencirikan sebagai pohon menghasilkan bunga jantan dan penghasil bunga betina. Perbedaan antara tahap bunga, buah muda, dan buah matang tidak dapat dibakukan berdasarkan karakteristik morfologi eksternal dari fig. Tingkat kematangan buah nyawai dapat dilakukan dengan membelah fig. Nyawai tahap kuncup bunga berakhir sekitar 6-11 hari setelah munculya tunas fig, dan tahap bunga berakhir 11-26 hari. Perkembangan kuncup bunga menjadi buah yang matang memakan waktu sekitar 2-3 bulan. Hasil penelitian menyarankan untuk tidak mengumpulkan benih dari fig yang berukuran kecil, meskipun mereka memiliki karakteristik fisik fig yang matang.

Recent advances in clay mineral-containing nanocomposite hydrogels.

Science.gov (United States)

Zhao, Li Zhi; Zhou, Chun Hui; Wang, Jing; Tong, Dong Shen; Yu, Wei Hua; Wang, Hao

2015-12-28

Clay mineral-containing nanocomposite hydrogels have been proven to have exceptional composition, properties, and applications, and consequently have attracted a significant amount of research effort over the past few years. The objective of this paper is to summarize and evaluate scientific advances in clay mineral-containing nanocomposite hydrogels in terms of their specific preparation, formation mechanisms, properties, and applications, and to identify the prevailing challenges and future directions in the field. The state-of-the-art of existing technologies and insights into the exfoliation of layered clay minerals, in particular montmorillonite and LAPONITE®, are discussed first. The formation and structural characteristics of polymer/clay nanocomposite hydrogels made from in situ free radical polymerization, supramolecular assembly, and freezing-thawing cycles are then examined. Studies indicate that additional hydrogen bonding, electrostatic interactions, coordination bonds, hydrophobic interaction, and even covalent bonds could occur between the clay mineral nanoplatelets and polymer chains, thereby leading to the formation of unique three-dimensional networks. Accordingly, the hydrogels exhibit exceptional optical and mechanical properties, swelling-deswelling behavior, and stimuli-responsiveness, reflecting the remarkable effects of clay minerals. With the pivotal roles of clay minerals in clay mineral-containing nanocomposite hydrogels, the nanocomposite hydrogels possess great potential as superabsorbents, drug vehicles, tissue scaffolds, wound dressing, and biosensors. Future studies should lay emphasis on the formation mechanisms with in-depth insights into interfacial interactions, the tactical functionalization of clay minerals and polymers for desired properties, and expanding of their applications.

Geotechnical properties of Karwar marine clay

Digital Repository Service at National Institute of Oceanography (India)

Bhat, S.T.; Nayak, B.U.; Naik, R.L.

Karwar marine clay possesses high plasticity characteristics with natural water content higher than the liquid limit. Liquidity index was as high as 1.7. Predominant clay mineral was kaolinite. Undrained shear strength showed an increasing trend...

Enrichment and activation of smectite-poor clay

Energy Technology Data Exchange (ETDEWEB)

Sarcevica, Inese; Kostjukovs, Juris; Actint, Andris, E-mail: inese.sarcevicha@gmail.com [Department of Chemistry, University of Latvia, Kr. Valdemara street 48, Riga (Latvia)

2011-06-23

A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

Pure and impure clays and their firing products

International Nuclear Information System (INIS)

Murad, E.; Wagner, U.

1989-01-01

Moessbauer spectroscopy is highly suited for the study of clays whose industrial uses depend on the iron content. Reactions that take place during clay firing can be readily monitored by Moessbauer spectroscopy. Following dehydroxylation of clay minerals, the quadrupole splitting of octahedrally coordinated iron (III) increases abruptly, but reverts to lower values upon the formation of new, better ordered phases at higher temperatures. It is also shown that iron oxides may account for a considerably higher proportion of the total iron content of many clays than is commonly recognized, and their existence must be taken into consideration for a correct interpretation of the Moessbauer spectra of clays. (orig.)

Hydration Phase Diagram of Clay Particles from Molecular Simulations.

Science.gov (United States)

Honorio, Tulio; Brochard, Laurent; Vandamme, Matthieu

2017-11-07

Adsorption plays a fundamental role in the behavior of clays. Because of the confinement between solid clay layers on the nanoscale, adsorbed water is structured in layers, which can occupy a specific volume. The transition between these states is intimately related to key features of clay thermo-hydro-mechanical behavior. In this article, we consider the hydration states of clays as phases and the transition between these states as phase changes. The thermodynamic formulation supporting this idea is presented. Then, the results from grand canonical Monte Carlo simulations of sodium montmorillonite are used to derive hydration phase diagrams. The stability analysis presented here explains the coexistence of different hydration states at clay particle scale and improves our understanding of the irreversibilities of clay thermo-hydro-mechanical behavior. Our results provide insights into the mechanics of the elementary constituents of clays, which is crucial for a better understanding of the macroscopic behavior of clay-rich rocks and soils.

1.7. Acid decomposition of kaolin clays of Ziddi Deposit. 1.7.1. The hydrochloric acid decomposition of kaolin clays and siallites

International Nuclear Information System (INIS)

Mirsaidov, U.M.; Mirzoev, D.Kh.; Boboev, Kh.E.

2016-01-01

Present article of book is devoted to hydrochloric acid decomposition of kaolin clays and siallites. The chemical composition of kaolin clays and siallites was determined. The influence of temperature, process duration, acid concentration on hydrochloric acid decomposition of kaolin clays and siallites was studied. The optimal conditions of hydrochloric acid decomposition of kaolin clays and siallites were determined.

Absorption characteristics of Kupravas deposit clays modified by phosphoric acid

International Nuclear Information System (INIS)

Ruplis, A.; Mezinskis, G.; Chaghuri, M.

1998-01-01

Literature data suggested that clays may be used as sorbents for waste water treatment. The surface and sorption properties of minerals changes due to the influence of acid rains. The process of recession of clay properties has been modeled in laboratory by treatment of clays with mineral acids at higher temperature that in natural conditions. The present paper is devoted to the study of influence of phosphoric acid on the sorption properties of Kupravas deposit clays. Natural clay samples and samples treated with phosphoric acid were characterized by means of x-ray diffraction an differential thermal analysis (DTA) methods These methods were used also to identify the sample of Lebanese clays. X-ray diffraction analysis data show that the samples of clays from the deposit of Kuprava contain illite and kaolinite while sample of Lebanese clay contains quartz, calcite, and montmorillonite. DTA results show characteristic features of Kuprava clays described in reference with DTA of Lebanese clay clearly demonstrate the presence of large quantity of calcite

Studies of maturation fig (Ficus carica L.) treated with ionizing radiation

International Nuclear Information System (INIS)

Domarco, Rachel E.; Spotp, Maria H.F.; Blumer, Lucimara; Walder, Julio M.M.; Matraia, Clarice

1997-01-01

The effect of irradiation dose, temperature and periods of storage were analized on figs type Ramy (harvest in post-climateric stage) and type Exportation (harvest on climate stage). The figs were packed in carton boxes and irradiated with 0.0 and 1,5 kGy, a source of Cobalt-60, type Gammabeam-650, was utilized. After the irradiation, the samples were stored at room temperature (± 22 0 C) and under refrigeration ±8 0 C). The samples were analised by physic and chemical analysis (soluble solids, pH, titulable acidity and ratio) after 3, 7, 13, 20 and 26 days of storage. The Rami showed higher soluble solids, pH and ratio, of type Exportation. The radiation dose effects caused small variations in all caracteristics. The soluble solids, pH and ratio increased with radiation dose, but titulable acidity decreased for both types of figs. It was observed an increased on soluble solids, titulable acidity and pH for Ramy and Exportation. The color was influenced by type of fig, radiation dose and storage period of storage. There was change in coler with high radiation dose. (author). 5 refs., 7 figs

Feasibility of classification of clay minerals by using PAS

International Nuclear Information System (INIS)

Honda, Y; Yoshida, Y; Akiyama, Y; Nishijima, S

2015-01-01

After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found. (paper)

Clay-Alcohol-Water Dispersions: Anomalous Viscosity Changes Due to Network Formation of Clay Nanosheets Induced by Alcohol Clustering.

Science.gov (United States)

Kimura, Yuji; Haraguchi, Kazutoshi

2017-05-16

Clay-alcohol-water ternary dispersions were compared with alcohol-water binary mixtures in terms of viscosity and optical absorbance. Aqueous clay dispersions to which lower alcohols (ethanol, 1-propanol, 2-propanol, and tert-butanol) were added exhibited significant viscosity anomalies (maxima) when the alcohol content was 30-55 wt %, as well as optical absorbance anomalies (maxima). The maximum viscosity (η max ) depended strongly on the clay content and varied between 300 and 8000 mPa·s, making it remarkably high compared with the viscosity anomalies (2 mPa·s) observed in alcohol-water binary mixtures. The alcohol content at η max decreased as the hydrophobicity of the alcohol increased. The ternary dispersions with viscosity anomalies exhibited thixotropic behaviors. The effects of other hydrophilic solvents (glycols) and other kinds of clays were also clarified. Based on these findings and the average particle size changes, the viscosity anomalies in the ternary dispersions were explained by alcohol-clustering-induced network formation of the clay nanosheets. It was estimated that 0.9, 1.7, and 2.5 H 2 O molecules per alcohol molecule were required to stabilize the ethanol, 2-propanol, and tert-butanol, respectively, in the clay-alcohol-water dispersions.

Chemo-hydro-mechanical behaviour of unsaturated clays

International Nuclear Information System (INIS)

Mokni, N.; Olivella, S.; Alonso, E.E.; Romero, E.

2010-01-01

Document available in extended abstract form only. Understanding of the chemical effects on clays is essential for many problems ranging from pollution studies and waste-containment. Several studies examined the effect of changes in pore fluid composition on the mechanical and hydraulic properties. Volume changes (contraction/ expansion) have been measured on clay specimens upon exposure to salt solutions or permeation with organic liquids. Moreover, it was shown that permeation of clay with brine induces an increase of the shear strength. In addition, several models have been proposed to describe the chemo-mechanical behaviour of saturated clays under saturated conditions. A new chemo-hydro-mechanical model for unsaturated clays is under development. The chemo-mechanical effects are described within an elasto-plastic framework using the concept that chemical effects act on the plastic properties by increasing or decreasing the pre-consolidation stress. The model is based on the distinction within the material of a microstructural and a macro-structural levels. Chemical loading has a significant effect on the microstructure. The negative pressure associated with the capillary water plays its role in the interconnected macro pores. By adopting simple assumptions concerning the coupling between the two levels it is intended to reproduce the features of the behaviour of unsaturated clays when there is a change in pore fluid composition (increase or decrease of concentration). A yield surface which defines the set of yield pre-consolidation stress values, for each associated capillary suction and concentration of pore fluid should be defined. In addition, the behaviour of clays under unsaturated condition and the behaviour at full saturation under chemical loading represent two limiting cases of the framework. Studies on the compatibility of Boom Clay with large amounts of nitrate- bearing bituminized radioactive waste have recently raised a particular interest on the

Synthetic mullite fabrication from smectite clays

International Nuclear Information System (INIS)

Lima, L.N. de; Kiminami, R.H.G.A.

1988-01-01

The technological importance of mullite is mostly due to its refractory properties. Mullite in native form is very rare, and therefore it may be necessary to produced it by synthetic means. Brazil has a large reserve of smectite clays. In this work the process to produce synthetic mullite from these clays by treatment with aluminum sulphate was studied. X-ray analyses has shown the presence of mullite crystals in treated smectite clays of several colours, sinterized at 1100 0 C. By sintering at 1300 0 C, pure mullite was obtained in some colours. (author) [pt

Multifaceted role of clay minerals in pharmaceuticals

OpenAIRE

Khurana, Inderpreet Singh; Kaur, Satvinder; Kaur, Harpreet; Khurana, Rajneet Kaur

2015-01-01

The desirable physical and physiochemical properties of clay minerals have led them to play a substantial role in pharmaceutical formulations. Clay minerals like kaolin, smectite and palygorskite-sepiolite are among the world's most valuable industrial minerals and of considerable importance. The elemental features of clay minerals which caused them to be used in pharmaceutical formulations are high specific area, sorption capacity, favorable rheological properties, chemical inertness, swelli...

Aluminium - Cobalt-Pillared Clay for Dye Filtration Membrane

Science.gov (United States)

Darmawan, A.; Widiarsih

2018-04-01

The manufacture of membrane support from cobalt aluminium pillared clay has been conducted. This research was conducted by mixing a clay suspension with pillared solution prepared from the mixture of Co(NO3)2.6H2O and AlCl3.6H2O. The molar ratio between Al and Co was 75:25 and the ratio of [OH-]/[metal] was 2. The clay suspension was stirred for 24 hours at room temperature, filtered and dried. The dried clay was then calcined at 200°C, 300°C and 400°C with a ramp rate of 2°C/min. Aluminium-cobalt-pillared clay was then characterized by XRD and GSA and moulded become a membrane support for subsequent tests on dye filtration. The XRD analysis showed that basal spacing (d 001) value of aluminium cobalt was 19.49 Å, which was higher than the natural clay of 15.08Å however, the basal spacing decreased with increasing calcination temperature. The result of the GSA analysis showed that the pore diameter of the aluminium cobalt pillared clay membrane was almost the same as that of natural clay that were 34.5Å and 34.2Å, respectively. Nevertheless, the pillared clay has a more uniform pore size distribution. The results of methylene blue filtration measurements demonstrated that the membrane filter support could well which shown by a clear filtrate at all concentrations tested. The value of rejection and flux decreased with the increasing concentration of methylene blue. The values of dye rejection and water flux reached 99.89% and 5. 80 x 10-6 kg min-1, respectively but they decreased with increasing concentration of methylene blue. The results of this study indicates that the aluminium-pillared clay cobalt could be used as membrane materials especially for ultrafiltration.

clay nanocomposite by solution intercalation technique

Indian Academy of Sciences (India)

Polymer–clay nanocomposites of commercial polystyrene (PS) and clay laponite were prepared via solution intercalation technique. Laponite was modified suitably with the well known cationic surfactant cetyltrimethyl ammonium bromide by ion-exchange reaction to render laponite miscible with hydrophobic PS.

Impact-Induced Clay Mineral Formation and Distribution on Mars

Science.gov (United States)

Rivera-Valentin, E. G.; Craig, P. I.

2015-01-01

Clay minerals have been identified in the central peaks and ejecta blankets of impact craters on Mars. Several studies have suggested these clay minerals formed as a result of impact induced hydrothermalism either during Mars' Noachian era or more recently by the melting of subsurface ice. Examples of post-impact clay formation is found in several locations on Earth such as the Mjolnir and Woodleigh Impact Structures. Additionally, a recent study has suggested the clay minerals observed on Ceres are the result of impact-induced hydrothermal processes. Such processes may have occurred on Mars, possibly during the Noachian. Distinguishing between clay minerals formed preor post-impact can be accomplished by studying their IR spectra. In fact, showed that the IR spectra of clay minerals is greatly affected at longer wavelengths (i.e. mid-IR, 5-25 micron) by impact-induced shock deformation while the near-IR spectra (1.0-2.5 micron) remains relatively unchanged. This explains the discrepancy between NIR and MIR observations of clay minerals in martian impact craters noted. Thus, it allows us to determine whether a clay mineral formed from impact-induced hydrothermalism or were pre-existing and were altered by the impact. Here we study the role of impacts on the formation and distribution of clay minerals on Mars via a fully 3-D Monte Carlo cratering model, including impact- melt production using results from modern hydrocode simulations. We identify regions that are conducive to clay formation and the location of clay minerals post-bombardment.

Polyethersulfone/clay membranes and its water permeability

International Nuclear Information System (INIS)

Cavalho, Thamyres Cardoso de; Medeiros, Vanessa da Nobrega; Araujo, Edcleide Maria de; Lira, Helio Lucena; Leite, Amanda Melissa Damiao

2017-01-01

Membranes can be considered polymeric or inorganic films that function as a semipermeable barrier to filtration on a molecular scale, separating two phases and restricting, totally or partially, the transportation of one or more chemical species (solute) present in the solution. Therefore, the aim of this work is to produce polyethersulfone membranes (PES) and polyethersulfone/clay by phase inversion technique and evaluate the presence of clay in obtaining membranes for wastewater treatment. The used solvent was dimethylformamide (DMF) and clays were Brasgel PA (MMT) and Cloisite Na (CL Na) in the proportion of 3 to 5% (wt.). By Xray diffraction (XRD), the membranes with 3% of MMT and CL Na clays apparently had partially exfoliated structures. For the composition with 5% of CL Na a small peak was observed, which indicates that this is possibly an intercalated structure or microcomposite. By scanning electron microscopy (SEM), visualizes that the pure surface of the pure PES membrane a structure apparently without pores was observed in the used magnification and without roughness surface when compared to membranes with clay. The measurements of contact angle indicated that the inclusion of clay altered the wetting ability of the membranes. The flow with distilled water for all membranes started high and over time reached a stabilization level. Thus, it can be concluded that the presence and the content of clay altered the morphology of the membrane, contributing to an increase in water flow. (author)

Influence of clay organic modifier on morphology and performance of poly(ε-caprolactone/clay nanocomposites

Directory of Open Access Journals (Sweden)

Nikolić Marija S.

2015-01-01

Full Text Available Two series of poly(e-caprolactone nanocomposites with different organo-modified clays (1 to 8 wt% were prepared by the solution casting method. Organoclays with polar (Cloisite®C30B and nonpolar (Cloisite®C15A organic modifier and with different miscibility with poly(e-caprolactone matrix, were chosen. Exfoliated and/or intercalated nanocomposite’s structures were obtained by using high dilution and an ultrasonic treatment for the composite preparation. The effect of the surface modification and clay content on the morphology, mechanical and thermal properties of the nanocomposites was studied. Scanning electron microscopy excluded the formation of microcomposite. The wide-angle X-ray diffraction analysis revealed that the tendency toward exfoliated structure is higher for the Cloisite®C30B, which had better miscibility with poly(e-caprolactone matrix. Differences in spherulites’ sizes and morphology between two series of the nanocomposites were observed by the optical microscopy performed on as-casted films. Enthalpies of fusion and degrees of crystallinity were higher for nanocomposites than for neat poly(e-caprolactone and increase with the clay loading in both series, as a consequence of the clay nucleating effect. Decreased thermal stability of nanocomposites was ascribed to thermal instability of organic modifiers of the clays. The Halpin-Tsai model was used to compare the theoretically predicted values of the Young’s modulus with experimentally obtained ones in tensile tests.[Projekat Ministarstva nauke Republike Srbije, br. 172062

Influence of Fuel Load Dynamics on Carbon Emission by Wildfires in the Clay Belt Boreal Landscape

Directory of Open Access Journals (Sweden)

Aurélie Terrier

2016-12-01

Full Text Available Old-growth forests play a decisive role in preserving biodiversity and ecological functions. In an environment frequently disturbed by fire, the importance of old-growth forests as both a carbon stock as well as a source of emissions when burnt is not fully understood. Here, we report on carbon accumulation with time since the last fire (TSF in the dominant forest types of the Clay Belt region in eastern North America. To do so, we performed a fuel inventory (tree biomass, herbs and shrubs, dead woody debris, and duff loads along four chronosequences. Carbon emissions by fire through successional stages were simulated using the Canadian Fire Effects Model. Our results show that fuel accumulates with TSF, especially in coniferous forests. Potential carbon emissions were on average 11.9 t·ha−1 and 29.5 t·ha−1 for old-growth and young forests, respectively. In conclusion, maintaining old-growth forests in the Clay Belt landscape not only ensures a sustainable management of the boreal forest, but it also optimizes the carbon storage.

Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

Directory of Open Access Journals (Sweden)

Raman P. Singh

2010-01-01

Full Text Available This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

Environmental Degradation and Durability of Epoxy-Clay Nanocomposites

International Nuclear Information System (INIS)

Singh, R.P.; Zunjarrao, S.C.; Pandey, G.; Khait, M.; Korach, C.S.

2010-01-01

This experimental investigation reports on the durability of epoxy-clay nanocomposites upon exposure to multiple environments. Nanocomposites are fabricated by mixing the clay particles using various combinations of mechanical mixing, high-shear dispersion, and ultrasonication. Clay morphology is characterized using X-ray diffraction and transmission electron microscopy. Specimens of both neat epoxy and the epoxy-clay nanocomposite are subjected to two environmental conditions: combined UV radiation and condensation on 3-hour repeat cycle and constant temperature-humidity, for a total exposure duration of 4770 hours. The presence of nanoscale clay inhibits moisture uptake, as demonstrated by exposure to constant temperature-humidity. Nonetheless, both materials lose mass under exposure to combined UV radiation and condensation due to the erosion of epoxy by a synergistic process. Surprisingly, the epoxy-clay specimens exhibit greater mass loss, as compared to neat epoxy. Mechanical testing shows that either environment does not significant affect the flexure modulus of either material. On the other hand, both materials undergo degradation in flexural strength when exposed to either environment. However, the epoxy-clay nanocomposite retains 37% more flexure strength than the neat epoxy after 4072 hours of exposure.

Studies on Tagged Clay Migration Due to Water Movement

International Nuclear Information System (INIS)

Scharpenseel, H.W.; Kerpen, W.

1967-01-01

55 Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the B t -development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of 55 Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for 55 Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

clay nanocomposites

Indian Academy of Sciences (India)

The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray ...

α-Pinene conversion by modified-kaolinitic clay

International Nuclear Information System (INIS)

Volzone, C.; Masini, O.; Comelli, N.A.; Grzona, L.M.; Ponzi, E.N.; Ponzi, M.I.

2005-01-01

The isomerization of α-pinene using natural kaolinitic clay before and after different treatments was studied in this work. The kaolinite is a clay material constituted by phyllosilicate 1:1 layer (one sheet of tetrahedral silicon and one sheet of octahedral alumina). The clay was treated at different times using 6.0 N solution of sulfuric acid previous heating to 500 or 700 K. The materials were characterized by X-ray diffraction, by chemical analyses and acidity measurements. The catalytic reactions were carried out at 373 K in a reactor batch with condenser and stirrer. Samples were taken at regular intervals, and reactants and products were quantitatively analyzed with a gas chromatograph after separation of the individual compounds. Conversions of alpha pinene between 67 and 94%, and selectivities in camphene and in limonene of 65 and 23%, respectively, were obtained with the clay treated at different conditions. The structural and textural changes of the clay by the treatments influenced on catalytic reactions

{alpha}-Pinene conversion by modified-kaolinitic clay

Energy Technology Data Exchange (ETDEWEB)

Volzone, C. [CETMIC-Centro de Tecnologia de Recursos Minerales y Ceramica-(CONICET-CIC), C.C. 49, Cno. Centenario y 506 (1897) M.B. Gonnet, Prov., Buenos Aires (Argentina)]. E-mail: volzcris@netverk.com.ar; Masini, O. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina); Comelli, N.A. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina); Grzona, L.M. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina); Ponzi, E.N. [CINDECA (CONICET-UNLP) calle 47 No. 257 (1900) La Plata, Prov., Buenos Aires (Argentina); Ponzi, M.I. [INTEQUI (CONICET-UNSL), Facultad de Ingenieria y Ciencias Economico Sociales, 25 de Mayo 384, V. Mercedes, Prov., San Luis (Argentina)

2005-10-15

The isomerization of {alpha}-pinene using natural kaolinitic clay before and after different treatments was studied in this work. The kaolinite is a clay material constituted by phyllosilicate 1:1 layer (one sheet of tetrahedral silicon and one sheet of octahedral alumina). The clay was treated at different times using 6.0 N solution of sulfuric acid previous heating to 500 or 700 K. The materials were characterized by X-ray diffraction, by chemical analyses and acidity measurements. The catalytic reactions were carried out at 373 K in a reactor batch with condenser and stirrer. Samples were taken at regular intervals, and reactants and products were quantitatively analyzed with a gas chromatograph after separation of the individual compounds. Conversions of alpha pinene between 67 and 94%, and selectivities in camphene and in limonene of 65 and 23%, respectively, were obtained with the clay treated at different conditions. The structural and textural changes of the clay by the treatments influenced on catalytic reactions.

Active containment systems incorporating modified pillared clays

International Nuclear Information System (INIS)

Lundie, P.; McLeod, N.

1997-01-01

The application of treatment technologies in active containment systems provides a more advanced and effective method for the remediation of contaminated sites. These treatment technologies can be applied in permeable reactive walls and/or funnel and gate systems. The application of modified pillared clays in active containment systems provides a mechanism for producing permeable reactive walls with versatile properties. These pillared clays are suitably modified to incorporate reactive intercalatants capable of reacting with both a broad range of organic pollutants of varying molecular size, polarity and reactivity. Heavy metals can be removed from contaminated water by conventional ion-exchange and other reactive processes within the clay structure. Complex contamination problems can be addressed by the application of more than one modified clay on a site specific basis. This paper briefly describes the active containment system and the structure/chemistry of the modified pillared clay technology, illustrating potential applications of the in-situ treatment process for contaminated site remediation

Controlling harmful algae blooms using aluminum-modified clay.

Science.gov (United States)

Liu, Yang; Cao, Xihua; Yu, Zhiming; Song, Xiuxian; Qiu, Lixia

2016-02-15

The performances of aluminum chloride modified clay (AC-MC), aluminum sulfate modified clay (AS-MC) and polyaluminum chloride modified clay (PAC-MC) in the removal of Aureococcus anophagefferens were compared, and the potential mechanisms were analyzed according to the dispersion medium, suspension pH and clay surface charges. The results showed that AC-MC and AS-MC had better efficiencies in removing A.anophagefferens than PAC-MC. The removal mechanisms of the three modified clays varied. At optimal coagulation conditions, the hydrolysates of AC and AS were mainly monomers, and they transformed into Al(OH)3(am) upon their addition to algae culture, with the primary mechanism being sweep flocculation. The PAC mainly hydrolyzed to the polyaluminum compounds, which remained stable when added to the algae culture, and the flocculation mainly occurred through polyaluminum compounds. The suspension pH significantly influenced the aluminum hydrolysate and affected the flocculation between the modified clay and algae cells. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tensile mechanical response of polyethylene – clay nanocomposites.

Directory of Open Access Journals (Sweden)

2007-03-01

Full Text Available In this work we report on the microstructural and the mechanical characteristics of high density polyethylene (HDPE-clay nanocomposites, with particular attention to the creep behaviour. The samples were prepared through melt compounding, using two high-density polyethylenes with different melt flow rate (MFR, two different organo-modified clays, and changing the relative amount of a polyethylene grafted with maleic anhydride (PEgMA compatibilizer. The intercalation process is more effective as the matrix melt viscosity decreases (higher MFR, while the clay interlamellar spacing increases as the compatibilizer amount increases. The relative stiffness of the nanocomposites increases with the addition of clay, with a limited enhancement of the relative yield stress. The better intercalation obtained by the addition of the compatibilizer is not accompanied by a concurrent improvement of the tensile mechanical properties. The creep resistance is enhanced by the introduction of clay, with an appreciable dependence on both the polyethylene and the clay type.

Study of radionuclide migration in clay formations

International Nuclear Information System (INIS)

Antonioli, F.; Bocola, W.

1985-01-01

This paper reports the studies on the migration of Cs, Sr and I in clay formations, which are presently considered for the geological disposal of radioactive wastes. The distribution and diffusion coefficients were evaluated by means of experimental techniques and computer procedures, which are presented in this report. The natural clays tested in the laboratory experiments were sampled from the most representative italian basins and from the zone of Mol (Belgium). In addition tests were performed on monomineral clays artificially remade in edometer. The experimental results are in accordance with data found in the literature and show the existence of a good correlation between the observed migration properties and the granulometric and mineralogic characteristics of the natural clays

Heteroaggregation of titanium dioxide nanoparticles with natural clay colloids.

Science.gov (United States)

Labille, Jérôme; Harns, Carrie; Bottero, Jean-Yves; Brant, Jonathan

2015-06-02

To better understand and predict the fate of engineered nanoparticles in the water column, we assessed the heteroaggregation of TiO2 nanoparticles with a smectite clay as analogues for natural colloids. Heteroaggregation was evaluated as a function of water salinity (10(-3) and 10(-1) M NaCl), pH (5 and 8), and selected nanoparticle concentration (0-4 mg/L). Time-resolved laser diffraction was used, coupled to an aggregation model, to identify the key mechanisms and variables that drive the heteroaggregation of the nanoparticles with colloids. Our data show that, at a relevant concentration, nanoparticle behavior is mainly driven by heteroaggregation with colloids, while homoaggregation remains negligible. The affinity of TiO2 nanoparticles for clay is driven by electrostatic interactions. Opposite surface charges and/or high ionic strength favored the formation of primary heteroaggregates via the attachment of nanoparticles to the clay. The initial shape and dispersion state of the clay as well as the nanoparticle/clay concentration ratio also affected the nature of the heteroaggregation mechanism. With dispersed clay platelets (10(-3) M NaCl), secondary heteroaggregation driven by bridging nanoparticles occurred at a nanoparticle/clay number ratio of greater than 0.5. In 10(-1) M NaCl, the clay was preaggregated into larger and more spherical units. This favored secondary heteroaggregation at lower nanoparticle concentration that correlated to the nanoparticle/clay surface area ratio. In this latter case, a nanoparticle to clay sticking efficiency could be determined.

Influence of chemical treatment of clay to obtain polypropylene nanocomposites

International Nuclear Information System (INIS)

Rosa, Jeferson L.S.; Marques, Maria F.V.

2009-01-01

Commercial clay was chemically treated to prepare a Ziegler-Natta catalyst containing MgCl 2 and clay for the synthesis of polypropylene nanocomposites by in situ polymerization. The performance of this catalyst and materials obtained in propylene polymerization was compared with a reference catalyst (without clay) and with another, whose composition presents the same clay but without prior chemical treatment. Techniques like differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and melt flow index (MFI) measurements were performed. There was a marked reduction in catalytic activity of clay catalysts in comparison with the reference one, and a slight reduction in melting temperature of the polymers produced from first ones. The melt flow index of polymers obtained with treated clay were notably higher than those synthesized with the untreated clay, so the treated clay caused treated the production of PP's with lower molar mass. The clays showed an increase of spacing and irregular stacking of the lamellas, especially if chemically treated. (author)

The real water consumption of orange trees irrigated by reused water in tunisia

International Nuclear Information System (INIS)

Zouhaier, M.C.

1995-01-01

Our research experiments, have been conducted in the experiment station of 'Oued souhil' situated under semi-arid climate in tunisia. We have studied the real water consumption of orange trees irrigated by reused water compared the results with trees using water from well. For measuring the different parameters, to determine soil humidity and the soil apparent density, we have used respectively neutron lead 'Neutron probe' and radiation gamma instruments. However, the experiments results conducted for 7 years from 1987 to 1993 - allowed the evaluation of the read consumption of orange trees using reused water and well water and the production quantity. The effect of using the two different quality of water with different irrigation systems have been also studied. 6 figs., 4 tabs

The real water consumption of orange trees irrigated by reused water in tunisia

Energy Technology Data Exchange (ETDEWEB)

Zouhaier, M C [Center de recherche du Genie Rural B.P. No. 10-2080 Ariana (Tunisia)

1995-10-01

Our research experiments, have been conducted in the experiment station of `Oued souhil` situated under semi-arid climate in tunisia. We have studied the real water consumption of orange trees irrigated by reused water compared the results with trees using water from well. For measuring the different parameters, to determine soil humidity and the soil apparent density, we have used respectively neutron lead `Neutron probe` and radiation gamma instruments. However, the experiments results conducted for 7 years from 1987 to 1993 - allowed the evaluation of the read consumption of orange trees using reused water and well water and the production quantity. The effect of using the two different quality of water with different irrigation systems have been also studied. 6 figs., 4 tabs.

Studies on Tagged Clay Migration Due to Water Movement

Energy Technology Data Exchange (ETDEWEB)

Scharpenseel, H. W. [Institut fuer Bodenkunde der Universitaet Bonn, Federal Republic of Germany (Germany); Kerpen, W. [Arbeitsgruppe, Institut fuer Landwirtschaft der KFA Juelich, Bonn, Federal Republic of Germany (Germany)

1967-11-15

{sup 55}Fe-tagged clay minerals, produced by hydrothermal synthesis, serve to clarify the question whether clay migration or clay formation in situ is the predominating mechanism in the B{sub t}-development of Parabraunerde (sol brun lessive, grey brown podsolic, hapludalf, dernopodsol). They further indicate the possibilities of clay transportation caused by water percolation. Suitable experimental approaches, such as thin-layer chromatography and autoradiography, translocation tests in columns filled with monotypical textural fractions or with undisturbed soil profiles, and synchronous hydrothermal treatment of {sup 55}Fe-con raining material from different horizons of Parabraunerde, to reveal the specific readiness of the different profile zones for {sup 55}Fe-clay production, are described. The possibilities of clay percolation are discussed. (author)

Geological Investigations on Boulder-Clay of E. Groningen

NARCIS (Netherlands)

Gijzel, van P.; Overweel, C.J.; Veenstra, H.J.

1959-01-01

In this article the results of a study on boulder-clay in the neighbourhood of Winschoten (N.E. Netherlands) are communicated (Chapter I). The underlying sediments of the boulder-clay in this area consist of fine preglacial sands and black clay. In the nuclei of the many drumlins a strongly

Nanoporous polymer--clay hybrid membranes for gas separation.

Science.gov (United States)

Defontaine, Guillaume; Barichard, Anne; Letaief, Sadok; Feng, Chaoyang; Matsuura, Takeshi; Detellier, Christian

2010-03-15

Nanohybrid organo-inorgano clay mineral-polydimethylsiloxane (PDMS) membranes were prepared by the reaction of pure and/or modified natural clay minerals (Sepiolite and montmorillonite) with PDMS in hexane, followed by evaporation of the solvent at 70 degrees C. The membranes were characterized by means of XRD, SEM, ATD-TG and solid state (29)Si magic angle spinning (MAS) and cross-polarization (CP) CP/MAS NMR. The morphology of the membranes depends on the content loading of clay mineral. For low content, the membrane composition is homogeneous, with well dispersed nanoparticles of clay into the polymer matrix, whereas for higher clay content, the membranes are constituted also of a mixture of well dispersed nanoparticles into the polymer, but in the presence of agglomerations of small clay particles. Quantitative (29)Si MAS NMR demonstrated a strong correlation between the clay content of the membrane and the average length of the PDMS chain, indicating that the nanohybrid material is made of clay particles covalently linked to the PDMS structure. This is particularly the case for Sepiolite with has a high density of Q(2) silanol sites. The separation performances of the prepared membranes were tested for CO(2)/CH(4) and O(2)/N(2) mixtures. The observed separation factors showed an increase of the selectivity in the case of CO(2)/CH(4) in comparison with membranes made from PDMS alone under the same conditions. 2009 Elsevier Inc. All rights reserved.

Polyurethane/organo clay nano composite materials via in-situ polymerization

International Nuclear Information System (INIS)

Rehab, A.; Agag, T; Akelah, A.; Shalaby, N.

2005-01-01

Polyurethane/organo clay nano composites have been synthesized via in situ polymerization. The organo clay firstly prepared by intercalation of lyamine or amino lauric acid into montmorillonite-clay (MMT) through ion exchange process. The syntheses of polyurethane/organo clay hybrid films containing different ratio of clay were carried out by swelling the organo clay, into diol and diamine or into different kinds of diols, followed by addition of diisocyanate. The nano composites with dispersed structure of MMT was obtained as evidence by scanning electron microscope and x-ray diffraction. X-ray analysis showed that the d-spacing increased to more than 44A since there is no peaks corresponding to do spacing in organo clay with all the ratios (1, 5, 10, 20%). Also, SEM results confirm the dispersion of nanometer silicate layers in the polyurethane matrix. This indicated that the clay was completely exfoliated and homogeneous dispersion in the polyurethane matrix. Also, it was found that the presence of organo clay leads to improvement the mechanical properties. Since, the tensile strength increased with increasing the organo clay contents to 20% by the ratio 194% in compared to the 1H: with 0% organo clay. Also, the elongation is a decreases with increasing the organo clay contents. The results shown the tensile strength of PU/SMA/ALA-MMT nano composites is high by 6-7 times than the corresponding to PU/Tvr-MMT

Development of polymer nanocomposites with regional bentonite clay

International Nuclear Information System (INIS)

Araujo, Edcleide M.; Leite, Amanda M.D.; Paz, Rene A. da; Medeiros, Keila M. de; Melo, Tomas J.A.; Barbosa, Josiane D.V.; Barbosa, Renata

2011-01-01

nanocomposites with regional bentonite clay were prepared by melt intercalation technique. The clays were studied without modification and modified with four quaternary ammonium salts. It was evidenced by X-ray diffraction that salts were incorporated into the clay structure thus confirming its organophilization. The nanocomposites were evaluated by means of thermal mechanic and flammability tests where presented properties significantly improved their pure polymers. The process of biodegradation of obtained bio nanocomposites was accelerated by the presence of clay. The produced membranes from nanocomposites have potential in the oil-water separation. (author)

Clays causing adhesion with tool surfaces during mechanical tunnel driving

Science.gov (United States)

Spagnoli, G.; Fernández-Steeger, T.; Stanjek, H.; Feinendegen, M.; Post, C.; Azzam, R.

2009-04-01

During mechanical excavation with a tunnel boring machine (TBM) it is possible that clays stick to the cutting wheel and to other metal parts. The resulting delays in the progress of construction work, cause great economic damage and often disputes between the public awarding authorities and executing companies. One of the most important factors to reduce successfully the clay adhesion is the use of special polymers and foams. But why does the clay stick to the metal parts? A first step is to recognize which kind of clay mineralogy shows serious adhesion problems. The mechanical properties of clay and clay suspensions are primarily determined by surface chemistry and charge distribution at the interfaces, which in turn affect the arrangement of the clay structure. As we know, clay is a multi-phase material and its behaviour depends on numerous parameters such as: clay mineralogy, clay fraction, silt fraction, sand fraction, water content, water saturation, Atterberg limits, sticky limit, activity, cation exchange capacity, degree of consolidation and stress state. It is therefore likely that adhesion of clay on steel is also affected by these clay parameters. Samples of clay formations, which caused problems during tunnel driving, will be analyzed in laboratory. Mineralogical analyses (diffractometry, etc.) will be carried out to observe which minerals are responsible for adherence problems. To manipulate the physical properties, batch tests will be carried out in order to eliminate or reduce the adhesion on tool surfaces through variation of the zeta potential. Second step is the performance of vane shear tests on clay samples. Different pore fluid (distilled water, pure NaCl solution, ethanol and methanol) will be used to study the variation of the mechanical behaviour of clay depending on the dielectric constant of the fluids. This project is funded by the German Federal Ministry of Education and Research (BMBF) and the DFG (German Research Foundation) in the

Corrosion behaviour of carbon steel in the Tournemire clay

International Nuclear Information System (INIS)

Foct, F.; Dridi, W.; Cabrera, J.; Savoye, S.

2004-01-01

Carbon steels are possible materials for the fabrication of nuclear waste containers for long term geological disposal in argillaceous environments. Experimental studies of the corrosion behaviour of such materials has been conducted in various conditions. Concerning the numerous laboratory experiments, these conditions (water and clay mixture or compacted clay) mainly concern the bentonite clay that would be used for the engineered barrier. On the opposite, only few in-situ experiments has been conducted directly in the local clay of the repository site (such as Boom clay, etc.). In order to better estimate the corrosion behaviour of carbon steels in natural clay site conditions, an experimental study has been conducted jointly by EDF and IRSN in the argillaceous French site of Tournemire. In this study, A42 carbon steel specimens have been exposed in 3 different zones of the Tournemire clay formation. The first type of environmental conditions concerns a zone where the clay has not been affected by the excavation (EDZ) of the main tunnel neither by the main fracture zone of the clay formation. The second and third ones are located in the EDZ of the tunnel. In the second zone, an additional aerated water flows from the tunnel, whereas it does not in the third place. Some carbon steel specimens have been extracted after several years of exposure to these conditions. The average corrosion rate has been measured by the weight loss technique and the pitting corrosion depth has been evaluated under an optical microscope. Corrosion products have also been characterised by scanning electron microscopy and X-ray diffraction technique. Results are then discussed regarding the surrounding environmental conditions. Calculations of the oxygen transport from the tunnel through the clay and of the clay re-saturation can explain, in a first approach, the corrosion behaviour of the carbon steel in the different tested zones. (authors)

Thermally modified bentonite clay for copper removal

International Nuclear Information System (INIS)

Bertagnolli, C.; Kleinübing, S.J.; Silva, M.G.C.

2011-01-01

Bentonite clay coming from Pernambuco was thermally modified in order to increase its affinity and capacity in the copper removal in porous bed. The application of this procedure is justified by the low cost of clay, their abundance and affinity for various metal ions. Thermally treatment modifies the clay adsorption properties enables its use in porous bed system, with the increase in surface area and mechanical strength. The material was characterized by x-ray diffraction, thermogravimetric analysis and N_2 physisorption. Then tests were carried out for adsorption of copper in various experimental conditions and evaluated the mass transfer zone, useful and total adsorbed removal amounts and total copper removal percentage. The results showed that the clay treated at higher temperature showed higher copper removal. (author)

Performance of Kaolin Clay on the Concrete Pavement

Science.gov (United States)

Abdullah, M. E.; Jaya, R. P.; Shahafuddin, M. N. A.; Yaacob, H.; Ibrahim, M. H. Wan; Nazri, F. M.; Ramli, N. I.; Mohammed, A. A.

2018-05-01

This paper investigates the performance of concrete pavement containing kaolin clay with their engineering properties and to determine the optimum kaolin clay content. The concrete used throughout the study was designed as grade 30 MPa strength with constant water to cement ratio of 0.49. The compressive strength, flexural strength and water absorption test was conducted in this research. The concrete mix designed with kaolin clay as cement replacement comprises at 0%, 5%, 10% and 15% by the total weight of cement. The results indicate that the strength of pavement concrete decreases as the percentage of kaolin clay increases. It also shows that the water absorption increases with the percentage of cement replacement. However, 5% kaolin clay is found to be the optimum level to replace cement in a pavement concrete.

In situ study of radionuclide diffusion into clays with specific device: Autolab probe

International Nuclear Information System (INIS)

Porcheron, J.

1993-01-01

The aim of this shared cost contract between the French Atomic Energy Commissariat, Nuclear Safety and Protection Institute and the Commission of the European Communities was to build and use an experimental drilling probe, the AUTOLAB prob, which was designed to measure the diffusion into clay of radioactive pollutants originating from a high activity waste storage. The measurement was carried out in-situ during drilling. The probe is equipped a new operating mode which involves using the pressure of the drilling water as its source of energy. The probe is autonomous and can stay in the bore hole for an extensive period of time without requiring any monitoring and without introducing any pollution. The diffusion experiment was carried out in a bore-hole at the JRC in ISPRA (ITALY). Two diffusion experiments were carried out in identical conditions (clay, 85Sr tracer, water samples), one in Laboratory, (ISPRA JRC Radiochemistry Laboratory, ITALY), and the other in-situ. The results displayed that 85Sr diffusion was considerably faster in the in-situ experiment than in that conducted in Laboratory. The explanation for this phenomenon, which could be due to the balance of carbonates, has not yet been clearly established. This test shows the value of comparing laboratory tests with in-situ tests conducted accurately using well adapted equipment. 9 refs., 10 figs

Induced polarization of clay-sand mixtures: experiments and modeling

International Nuclear Information System (INIS)

Okay, G.; Leroy, P.; Tournassat, C.; Ghorbani, A.; Jougnot, D.; Cosenza, P.; Camerlynck, C.; Cabrera, J.; Florsch, N.; Revil, A.

2012-01-01

Document available in extended abstract form only. Frequency-domain induced polarization (IP) measurements consist of imposing an alternative sinusoidal electrical current (AC) at a given frequency and measuring the resulting electrical potential difference between two other non-polarizing electrodes. The magnitude of the conductivity and the phase lag between the current and the difference of potential can be expressed into a complex conductivity with the in-phase representing electro-migration and a quadrature conductivity representing the reversible storage of electrical charges (capacitive effect) of the porous material. Induced polarization has become an increasingly popular geophysical method for hydrogeological and environmental applications. These applications include for instance the characterization of clay materials used as permeability barriers in landfills or to contain various types of contaminants including radioactive wastes. The goal of our study is to get a better understanding of the influence of the clay content, clay mineralogy, and pore water salinity upon complex conductivity measurements of saturated clay-sand mixtures in the frequency range ∼1 mHz-12 kHz. The complex conductivity of saturated unconsolidated sand-clay mixtures was experimentally investigated using two types of clay minerals, kaolinite and smectite in the frequency range 1.4 mHz - 12 kHz. Four different types of samples were used, two containing mainly kaolinite (80% of the mass, the remaining containing 15% of smectite and 5% of illite/muscovite; 95% of kaolinite and 5% of illite/muscovite), and the two others containing mainly Na-smectite or Na-Ca-smectite (95% of the mass; bentonite). The experiments were performed with various clay contents (1, 5, 20, and 100% in volume of the sand-clay mixture) and salinities (distilled water, 0.1 g/L, 1 g/L, and 10 g/L NaCl solution). In total, 44 saturated clay or clay-sand mixtures were prepared. Induced polarization measurements

Organic or organometallic template mediated clay synthesis

Science.gov (United States)

Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

1994-01-01

A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

Modification of clay-based waste containment materials

International Nuclear Information System (INIS)

Adu-Wusu, K.; Whang, J.M.; McDevitt, M.F.

1997-01-01

Bentonite clays are used extensively for waste containment barriers to help impede the flow of water in the subsurface because of their low permeability characteristics. However, they do little to prevent diffusion of contaminants, which is the major transport mechanism at low water flows. A more effective way of minimizing contaminant migration in the subsurface is to modify the bentonite clay with highly sorptive materials. Batch sorption studies were conducted to evaluate the sorptive capabilities of organo-clays and humic- and iron-based materials. These materials proved to be effective sorbents for the organic contaminants 1,2,4-trichlorobenzene, nitrobenzene, and aniline in water, humic acid, and methanol solution media. The sorption capacities were several orders of magnitude greater than that of unmodified bentonite clay. Modeling results indicate that with small amounts of these materials used as additives in clay barriers, contaminant flux through walls could be kept very small for 100 years or more. The cost of such levels of additives can be small compared to overall construction costs

Scour at Vertical Piles in Sand-Clay Mixtures under Waves

DEFF Research Database (Denmark)

Dey, Subhasish; Helkjær, Anders; Sumer, B. Mutlu

2011-01-01

Marine sediments often contain sand-clay mixtures in widely varying proportions. This study presents the results of equilibrium scour and time variation of scour depths at circular piles embedded vertically in clay alone and sand-clay mixed beds under waves. Experiments were conducted in a wave...... flume with different proportions of sand-clay mixtures as bed sediments. Test results for the cases of steady current and sand alone under waves are used as references. The equilibrium scour depth reduces with an increase in clay proportion n (by weight) in a sand-clay mixture. Interestingly, the scour...

Removal of waterborne microorganisms by filtration using clay-polymer complexes.

Science.gov (United States)

Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

2014-08-30

Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods. Copyright © 2014 Elsevier B.V. All rights reserved.

Instrumental neutron activation analysis of tree rings for dendrochemical studies

International Nuclear Information System (INIS)

Schaumloffel, J.C.; Filby, R.H.

1996-01-01

Instrumental neutron activation analysis (INAA) was employed to determine zinc, cadmium and potassium concentrations in the growth rings of ponderosa pine (Pinus ponderosa Dougl.) trees growing along the shores of Lake Roosevelt in Washington State, U.S.A. where mineral processing activities have resulted in high burdens of zinc and cadmium in the lake sediments. The tree growing along the contaminated waterway display elevated concentrations of zinc in its growth rings relative to a tree growing along an uncontaminated tributary of Lake Roosevelt. Cadmium concentrations in the growth rings from both sites are similar from 1988 to 1993. Water quality data indicate an increased concentration of cadmium in the lake from 1984 to 1988. The increased concentrations of cadmium in the lake water were reflected in apparent increases in concentrations of cadmium in individual rings of the tree sampled at the contaminated site. This suggests that translocation of cadmium in the sapwood of heartwood-forming species does not occur in the short term, and thus may not be a limiting factor in using trees as environmental monitors for cadmium. In addition, five-year tree ring segments were analyzed and subsequently reanalyzed as individual single-year ring segments. The analytical data obtained for the pooled individual rings are essentially the same as for the five-year segments, demonstrating the utility of NAA for dendrochemical studies. (author). 24 refs., 5 figs., 2 tabs

Climatic control on clay mineral formation

Indian Academy of Sciences (India)

Many physico-chemical variables like rock-type,climate,topography and exposure age affect weathering environments.In the present study,an attempt is made to understand how the nature of clay minerals formed due to weathering differs in tropical regions receiving high and low rainfall. Clay mineralogy of weathering pro ...

Competitive exclusion among fig wasps achieved via entrainment of host plant flowering phenology.

Directory of Open Access Journals (Sweden)

Min Liu

Full Text Available Molecular techniques are revealing increasing numbers of morphologically similar but co-existing cryptic species, challenging the niche theory. To understand the co-existence mechanism, we studied phenologies of morphologically similar species of fig wasps that pollinate the creeping fig (F. pumila in eastern China. We compared phenologies of fig wasp emergence and host flowering at sites where one or both pollinators were present. At the site where both pollinators were present, we used sticky traps to capture the emerged fig wasps and identified species identity using mitochondrial DNA COI gene. We also genotyped F. pumila individuals of the three sites using polymorphic microsatellites to detect whether the host populations were differentiated. Male F. pumila produced two major crops annually, with figs receptive in spring and summer. A small partial third crop of receptive figs occurred in the autumn, but few of the second crop figs matured at that time. Hence, few pollinators were available to enter third crop figs and they mostly aborted, resulting in two generations of pollinating wasps each year, plus a partial third generation. Receptive figs were produced on male plants in spring and summer, timed to coincide with the release of short-lived adult pollinators from the same individual plants. Most plants were pollinated by a single species. Plants pollinated by Wiebesia sp. 1 released wasps earlier than those pollinated by Wiebesia sp. 3, with little overlap. Plants occupied by different pollinators were not spatially separated, nor genetically distinct. Our findings show that these differences created mismatches with the flight periods of the other Wiebesia species, largely 'reserving' individual plants for the resident pollinator species. This pre-emptive competitive displacement may prevent long term co-existence of the two pollinators.

Water-clay interactions. Experimental study

International Nuclear Information System (INIS)

Gaucher, Eric

1998-01-01

Clay minerals contribute to the chemical composition of soil and sediment groundwaters via surface and dissolution/precipitation reactions. The understanding of those processes is still today fragmentary. In this context, our experimental purpose is to identify the contribution of each reaction in the chemical composition of water in a water/clay System. Kaolinite, illite, montmorillonite are the reference clays. After a fine mineralogical study, the exchange equilibria between K + and H + are characterised. Different exchange sites are identified and the exchange capacities and selectivity coefficients are quantified. Then, mixtures of the three clays are equilibrated with acidic and basic (I≤10 -2 M) solutions at 25 deg. C, 60 deg. C, 80 deg. C, during 320 days. The System evolution is observed by chemical analysis of the solutions and mineralogical analysis by TEM. We show that montmorillonite is unstable compared to the kaolinite/amorphous silica assemblage for solutions of pH<7. Aqueous silica is probably controlled by the kinetics of dissolution of the montmorillonite in moderate pH media. In more acidic solutions, amorphous silica precipitates. Al is under control of 'kaolinite' neo-formations. The use of the selectivity coefficients in a numerical simulation shows that K + concentration depends on exchange reactions. The pH has a more complicated evolution, which is not completely understood. This evolution depends on both exchange equilibria and organic acid occurrence. In this type of experiments, we have demonstrated that the equilibrium equations between smectite and kaolinite are inexact. The problem of the thermodynamic nature of clays remains and is not resolved by these solubility experiments. (author) [fr

The use of clays as sorbents and catalysts

International Nuclear Information System (INIS)

McCabe, R.W.

1998-01-01

The paper attempts to show the structural, physical and chemical properties of clay minerals relate to their laboratory, industrial and environmental uses as sorbents and catalysts. A brief review of the formulae and structures of clays and their relationship to their chemical and physical properties follows. Clay minerals are also useful in environmental protection as they can adsorb crude oils from spills and they are used, sometimes mixed into concrete, as containment barriers for radionuclides caesium 137 and strontium 90. Clay soils can also act as natural barriers to the migration of radionuclides in the environment

Rheology of Poly(N-isopropylacrylamide)-Clay Nanocomposite Hydrogels

Science.gov (United States)

Lombardi, Jack; Xu, Di; Bhatnagar, Divya; Gersappe, Dilip; Sokolov, Jonathan; Rafailovich, Miriam

2015-03-01

The stiffness of PNIPA Gels has been reported could be significant improved by gelation with clay fillers. Here we conducted systematic rheology study of synthesized PNIPA-Clay Composites at different clay concentration, in a range from fluid to strong gel, where G'' dominant changed to G' dominant. Molecular dynamics simulation was employed to analyze the structure of composites and corresponding mechanical changes with increased clays. Where we found viscoelastic behavior become significant only 1.5 times above percolation threshold. The yield stress extrapolated from our rheology results shows good fitting to modified Mooney's theory of suspension viscosity.

Effects of biochar on hydraulic conductivity of compacted kaolin clay.

Science.gov (United States)

Wong, James Tsz Fung; Chen, Zhongkui; Wong, Annie Yan Yan; Ng, Charles Wang Wai; Wong, Ming Hung

2018-03-01

Compacted clay is widely used as capillary barriers in landfill final cover system. Recently, biochar amended clay (BAC) has been proposed as a sustainable alternative cover material. However, the effects of biochar on saturated hydraulic conductivity (k sat ) of clay with high degree of compaction is not yet understood. The present study aims to investigate the effects of biochar on k sat of compacted kaolin clay. Soil specimens were prepared by amending kaolin clay with biochar derived from peanut-shell at 0, 5 and 20% (w/w). The k sat of soil specimens was measured using a flexible water permeameter. The effects of biochar on the microstructure of the compacted clay was also investigated using MIP. Adding 5% and 20% of biochar increased the k sat of compacted kaolin clay from 1.2 × 10 -9 to 2.1 × 10 -9 and 1.3 × 10 -8 ms -1 , respectively. The increase in k sat of clay was due to the shift in pore size distribution of compacted biochar-amended clay (BAC). MIP results revealed that adding 20% of biochar shifted the dominant pore diameter of clay from 0.01-0.1 μm (meso- and macropores) to 0.1-4 μm (macropores). Results reported in this communication revealed that biochar application increased the k sat of compacted clay, and the increment was positively correlated to the biochar percentage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inter-layered clay stacks in Jurassic shales

Science.gov (United States)

Pye, K.; Krinsley, D. H.

1983-01-01

Scanning electron microscopy in the backscattered electron mode is used together with energy-dispersive X-ray microanalysis to show that Lower Jurassic shales from the North Sea Basin contain large numbers of clay mineral stacks up to 150 microns in size. Polished shale sections are examined to determine the size, shape orientation, textural relationships, and internal compositional variations of the clays. Preliminary evidence that the clay stacks are authigenic, and may have formed at shallow burial depths during early diagenesis, is presented.

Decantation time of evaluation on bentonite clays fractionation

International Nuclear Information System (INIS)

Gomes, J.; Menezes, R.R.; Neves, G.A.; Lira, H.L; Santana, L.N.L.

2009-01-01

Bentonite clays present a great number of industrial uses, from petroleum to pharmaceutics and cosmetic industry. The bentonite clay present particles with very fine particles that is responsible by the vast application of these materials. However, commercial clays present wide particle size distribution and a significant content of impurities, particularly quartz, in the form of silt and fine silt. So, the aim of this work is to analyze the effect of the stirring and decantation time in the deagglomeration, purification and size separation of the bentonite clay particles from Paraiba. The clays were characterized by X-ray diffraction and particle size distribution. Based on the results it was observed the decantation time give the elimination of the agglomerates formed by submicrometric particles. The uses of decantation column give separation of the fraction below 200nm. (author)

Removal of clay by stingless bees: load size and moisture selection.

Science.gov (United States)

Costa-Pereira, Raul

2014-09-01

Some organisms disperse energy, associated with the transportation of resource, which is not necessarily food. Stingless bees of Central Amazonia (Melipona flavolineata and M. lateralis) collect clay in banks along streams for nest building. The moisture of the clay varies along the bank, and bees collect clay from specific location, indicating that there is some sort of preference regarding their selection. This study aims at identifying: if larger bees carry more clay; if there is a preference for moisture of substrates; and if bees are less efficient accumulating and transporting clay when it is wet. In order to do so, I measured the size of the bees and of the pellets of clay found in the corbicula. I set up a field experiment to test substrate preferences. The amount of clay transported, increased exponentially in accordance to the size of the bee, and the preferred substrate was the driest clay. The amount and the efficiency of removal of clay were not affected by the moisture of the substrate. Despite the wet clay being denser, it does not reduce the efficiency of exploitation of the resource, but suggests that bees spend more energy to carry the same quantity of wet clay, which may be the underlying mechanism explaining their preference for removing drier clay.

Sensory profiles for dried fig (Ficus carica L.) cultivars commercially grown and processed in California.

Science.gov (United States)

Haug, Megan T; King, Ellena S; Heymann, Hildegarde; Crisosto, Carlos H

2013-08-01

A trained sensory panel evaluated the 6 fig cultivars currently sold in the California dried fig market. The main flavor and aroma attributes determined by the sensory panel were "caramel," "honey," "raisin," and "fig," with additional aroma attributes: "common date," "dried plum," and "molasses." Sensory differences were observed between dried fig cultivars. All figs were processed by 2 commercial handlers. Processing included potassium sorbate as a preservative and SO2 application as an antibrowning agent for white cultivars. As a consequence of SO2 use during processing, high sulfite residues affected the sensory profiles of the white dried fig cultivars. Significant differences between dried fig cultivars and sources demonstrate perceived differences between processing and storage methods. The panel-determined sensory lexicon can help with California fig marketing. © 2013 The Regents of California, Davis Campus Department of Plant Sciences.

Removal of Phenol in Aqueous Solution Using Kaolin Mineral Clay

International Nuclear Information System (INIS)

Sayed, M.S.

2008-01-01

Kaolin clay were tested for phenol removal as toxic liquid waste from aqueous waste water. Several experimental conditions such as weight and particle size of clay were investigated to study batch kinetic techniques, also the ph and concentration of the phenol solution were carried out. The stability of the Langmuir adsorption model of the equilibrium data were studied for phenol sorbent clay system. Infrared spectra, thermogravimetric and differential thermal analysis techniques were used to characterize the behavior of kaolin clay and kaolin clay saturated with phenol. The results obtained showed that kaolin clay could be used successfully as an efficient sorbent material to remove phenol from aqueous solution

Gassmann Modeling of Acoustic Properties of Sand-clay Mixtures

Science.gov (United States)

Gurevich, B.; Carcione, J. M.

The feasibility of modeling elastic properties of a fluid-saturated sand-clay mixture rock is analyzed by assuming that the rock is composed of macroscopic regions of sand and clay. The elastic properties of such a composite rock are computed using two alternative schemes.The first scheme, which we call the composite Gassmann (CG) scheme, uses Gassmann equations to compute elastic moduli of the saturated sand and clay from their respective dry moduli. The effective elastic moduli of the fluid-saturated composite rock are then computed by applying one of the mixing laws commonly used to estimate elastic properties of composite materials.In the second scheme which we call the Berryman-Milton scheme, the elastic moduli of the dry composite rock matrix are computed from the moduli of dry sand and clay matrices using the same composite mixing law used in the first scheme. Next, the saturated composite rock moduli are computed using the equations of Brown and Korringa, which, together with the expressions for the coefficients derived by Berryman and Milton, provide an extension of Gassmann equations to rocks with a heterogeneous solid matrix.For both schemes, the moduli of the dry homogeneous sand and clay matrices are assumed to obey the Krief's velocity-porosity relationship. As a mixing law we use the self-consistent coherent potential approximation proposed by Berryman.The calculated dependence of compressional and shear velocities on porosity and clay content for a given set of parameters using the two schemes depends on the distribution of total porosity between the sand and clay regions. If the distribution of total porosity between sand and clay is relatively uniform, the predictions of the two schemes in the porosity range up to 0.3 are very similar to each other. For higher porosities and medium-to-large clay content the elastic moduli predicted by CG scheme are significantly higher than those predicted by the BM scheme.This difference is explained by the fact

Methods for obtention of PS/clay nanocomposites

International Nuclear Information System (INIS)

Lins, Pedro G.; Valera, Ticiane S.; Coelho, Caio P.D.; Demarquette, Nicole R.

2009-01-01

In this work, nanocomposites of Polystyrene (PS) and organoclay were obtained using a twin-screw extruder and a mixer Haake. A commercial clay named Cloisite 20A was used. The clay and the nanocomposites were characterized by X-Ray Diffraction. The rheological properties were investigated carrying out small amplitude oscillatory strain (SAOS). The results of X-ray diffraction showed that the polymer was incorporated by the organoclay. The results of SAOS indicated a better clay dispersion for the samples obtained using the mixer. (author)

Traditional mining and mineralogy of geophagic clays from Limpopo ...

African Journals Online (AJOL)

Geophagic clays consumed were whitish, yellowish, khaki and black; mined from hills and mountains, river beds, valleys, excavation sites and termitaria. Geophagic individuals from Free State preferred whitish geophagic clays; and sometimes khaki. Yellowish clays were preferred mostly by geophagic individuals from ...

Storage stability of standard and diet figs canned in syrup

Directory of Open Access Journals (Sweden)

Priscilla Kárim CAETANO

Full Text Available Abstract The current study aimed to evaluate the physicochemical, microbiological and sensory quality of traditional and diet figs canned in syrup, as well as verify their storage stability. Therefore, it was used green figs from the cultivar Roxo de Valinhos. Two treatments were held: standard sucrose syrup and sweetener blends: sodium cyclamate, sucralose and sodium saccharin. The syrups were previously prepared; being 25 °Brix for sucrose syrup; and by dividing the quantity of sucrose potency (100 to the blend of sweeteners potency (125 for sweetener blends. The products were stored at room temperature for 180 days and evaluated once a month through pH, soluble solids, titratable acidity, texture, vacuum and sensory evaluation (i.e. affective test; except for the commercial sterility test that was conducted at 0 to 180 days. Both canned figs in syrup showed no significant difference for pH, titratable acidity, soluble solids, vacuum and texture; therefore, both were considered commercially sterile and kept their sensory characteristics throughout storage.

Adsorption of zinc and lead on clay minerals

Directory of Open Access Journals (Sweden)

Katarína Jablonovská

2006-12-01

Full Text Available Clays (especially bentonite, zeolite and quartz sand are widely used as landfill barriers to prevent contamination of subsoil and groundwater by leachates containing heavy metals. The sorption of zinc and lead on these clays was studied as a function of time and it was found that the initial 1 h our was sufficient to exchange most of the metal ions. The retention efficiency of clay samples of Zn2+ and Pb2+ follows the order of bentonite > zeolite> quartz sand. Whatever the clay sample, lead is retained more than zinc. The concentration of elements in the solution was followed by atomic adsorption spectrofotometry. Bacillus cereus and Bacillus pumilus, previously isolated from the kaoline deposit Horna Prievrana was added into the clay samples to comparise the accumulation of Zn2+ and Pb2+ from the model solution. The study of heavy metal adsorption capacity of bacteria- enriched clay adsorbent showed a high retention efficiency for lead ions as comparised with zinc ions. Biosorption is considered a potential instrument for the removal of metals from waste solutions and for the precious metals recovery as an alternative to the conventional processes.

Characterization and analysis of epoxy/clay nanotubes composites

International Nuclear Information System (INIS)

Sene, Tarcisio S.; Kock, Thyago; Coelho, Luiz A.F.; Becker, Daniela

2011-01-01

An DGEBA epoxy matrix was used aiming to achieve a nanocomposite material, through the dispersion of (CNT) via mechanical stirring followed by sonication. In this work the following characterization were performed: mechanical characterization, differential scanning calorimetry (DSC), wide angle X-ray diffraction (WXRD) and scanning electron microscopy (SEM). The addition of CNT and modified clays promoted the increase of modulus of the epoxy matrix, and a synergistic effect between CNT and both clays could be presumed. SEM images of the fracture surface show the difference between the fracture surface area and the presence of clusters among the samples, allowing a correlation with the modulus of elasticity. X-ray diffractograms from 2Θ = 5 deg showed no peaks for modified clay samples, however it is possible to affirm that modified clay platelets are forming a less organized structure compared to the structure of the clay as natural in epoxy. (author)

Technetium migration in natural clays

International Nuclear Information System (INIS)

Luebke, Maria

2015-01-01

The present work was performed within the joint research project ''Retention of repository relevant radionuclides in argillaceous rocks and saline systems'' (contract no.: 02E10981), funded by the Federal Ministry for Economic Affairs and Energy (BMWi). The aim was to obtain first insights into the interaction of the long-lived fission product technetium and natural clay with regard to a repository for high-level nuclear waste. For this purpose Opalinus Clay from Mont Terri (northern Switzerland) was used as a reference material. The nuclide technetium-99 will contribute to the radiotoxicity of spent nuclear fuel for more than thousand years due to its long half-live. In case of a leakage of the storage vessels, the geochemistry of technetium is determined by its oxidation state, at which only the oxidation states +IV and +VII are relevant. Because of the high solubility and low affinity to sorption on surfaces of minerals, Tc(VII) is considered to be very mobile and thus the most hazardous species. The focuses of this study therefore are diffusion experiments with this mobile species and investigations of the effect of ferrous iron on the mobility and speciation of technetium.rnThe interaction of technetium and Opalinus Clay was studied in sorption and diffusion experiments varying several parameters (pH value, addition of reducing agents, effect of oxygen, diffusion pathways). In the course of this study spatially resolved investigations of the speciation have been performed on Opalinus Clay thin sections and bore cores for the first time. In addition to the speciation, further information regarding elemental distributions and crystalline phases near technetium enrichments were obtained. Supplementary investigations of powder samples allowed determining the molecular structure of technetium on the clay surface.rnBoth the combination of sorption experiments with spectroscopic investigations and the diffusion experiment exhibit a reduction of Tc

Water diffusion in clays with added organic surfactants

International Nuclear Information System (INIS)

Pineda-Pinon, J; Mendoza-Lopez, M L; Manzano-RamIrez, A; Perez-Robles, J F; Vega-Duran, J T

2007-01-01

Tensoactive agents may decrease water absorption in clay products like adobes. They modify the characteristics of the surface of clay particles. Characterization of water diffusion through the pores of modified clays is important to apply appropriate surface modifiers and to improve their performance. We established a simple model for water diffusion in test samples of defined dimensions to estimate real physical parameters and their effect on water absorption. Adsorption mechanisms are examined based on experimental results. The fitting of the experimental data to the model provides a deep understanding of water adsorption in chemically modified clays. A better agreement between the model and the experimental data is achieved for complex molecules

Clay club catalogue of characteristics of argillaceous rocks

International Nuclear Information System (INIS)

2005-01-01

The OECD/NEA Working Group on the Characterisation, the Understanding and the Performance of Argillaceous Rocks as Repository Host Formations, namely the Clay Club, examines the various argillaceous rocks that are being considered for the deep geological disposal of radioactive waste, i.e. from plastic, soft, poorly indurated clays to brittle, hard mud-stones or shales. The Clay Club considered it necessary and timely to provide a catalogue to gather in a structured way the key geo-scientific characteristics of the various argillaceous formations that are - or were - studied in NEA member countries with regard to radioactive waste disposal. The present catalogue represents the outcomes of this Clay Club initiative. (author)

p-Nitrophenol, phenol and aniline sorption by organo-clays

International Nuclear Information System (INIS)

Ko, C.H.; Fan Chihhao; Chiang, P.N.; Wang, M.K.; Lin, K.C.

2007-01-01

The aims of this study were to make use of organo-clays (i.e., Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A), to remove p-nitrophenol, phenol and aniline of organic pollutants. The organo-clays were characterized by X-ray diffraction (XRD). Sorption isotherm, kinetic and pH effect of p-nitrophenol, phenol and aniline sorbed by four organo-clays were evaluated. The d-spacings (0 0 1) of the XRD peak of Cloisite-10A, Cloisite-15A, Cloisite-30B and Cloisite-93A are 1.98, 2.76, 1.93 and 2.64 nm, respectively. The d(0 0 1)-spacings of XRD indicated that these p-nitropheno, phenol and aniline could penetrate into the interlayer of clays and expand the d(0 0 1)-spacings. The linear sorption isotherm of constant partition was employed to describe the sorption isotherms of phenols sorbed by organo-clays through hydrophobic-hydrophobic chemical reactions. The parabolic diffusion and power-function of kinetic models were employed to describe properly the kinetic experiments. The rate limiting step of the p-nitrophenol sorption reactions on organo-clays were diffusion-controlled processes (i.e., 15A, 30B, 93A) and chemical-controlled process for 10A organo-clays. The pre-exponential factor of the p-nitrophenol sorbed by four organo-clays showed the trend as follows: 10A > 30B > 93A > 15A. The efficiency of these organo-clays in removing phenol compounds in water treatments merit further study

Removal of clay by stingless bees: load size and moisture selection

Directory of Open Access Journals (Sweden)

RAUL COSTA-PEREIRA

2014-09-01

Full Text Available Some organisms disperse energy, associated with the transportation of resource, which is not necessarily food. Stingless bees of Central Amazonia (Melipona flavolineata and M. lateralis collect clay in banks along streams for nest building. The moisture of the clay varies along the bank, and bees collect clay from specific location, indicating that there is some sort of preference regarding their selection. This study aims at identifying: if larger bees carry more clay; if there is a preference for moisture of substrates; and if bees are less efficient accumulating and transporting clay when it is wet. In order to do so, I measured the size of the bees and of the pellets of clay found in the corbicula. I set up a field experiment to test substrate preferences. The amount of clay transported, increased exponentially in accordance to the size of the bee, and the preferred substrate was the driest clay. The amount and the efficiency of removal of clay were not affected by the moisture of the substrate. Despite the wet clay being denser, it does not reduce the efficiency of exploitation of the resource, but suggests that bees spend more energy to carry the same quantity of wet clay, which may be the underlying mechanism explaining their preference for removing drier clay.

Quality evaluation of processed clay soil samples.

Science.gov (United States)

Steiner-Asiedu, Matilda; Harrison, Obed Akwaa; Vuvor, Frederick; Tano-Debrah, Kwaku

2016-01-01

This study assessed the microbial quality of clay samples sold on two of the major Ghanaian markets. The study was a cross-sectional assessing the evaluation of processed clay and effects it has on the nutrition of the consumers in the political capital town of Ghana. The items for the examination was processed clay soil samples. Staphylococcus spp and fecal coliforms including Klebsiella, Escherichia, and Shigella and Enterobacterspp were isolated from the clay samples. Samples from the Kaneshie market in Accra recorded the highest total viable counts 6.5 Log cfu/g and Staphylococcal count 5.8 Log cfu/g. For fecal coliforms, Madina market samples had the highest count 6.5 Log cfu/g and also recorded the highest levels of yeast and mould. For Koforidua, total viable count was highest in the samples from the Zongo market 6.3 Log cfu/g. Central market samples had the highest count of fecal coliforms 4.6 Log cfu/g and yeasts and moulds 6.5 Log cfu/g. "Small" market recorded the highest staphylococcal count 6.2 Log cfu/g. The water activity of the clay samples were low, and ranged between 0.65±0.01 and 0.66±0.00 for samples collected from Koforidua and Accra respectively. The clay samples were found to contain Klebsiella spp. Escherichia, Enterobacter, Shigella spp. staphylococcus spp., yeast and mould. These have health implications when consumed.

Sponge 'tree rings' : new indicators of ocean variability?

International Nuclear Information System (INIS)

Ellwood, M.; Kelly, M.

2003-01-01

Certain marine sponges offer a unique approach to the problem of recording environmental change. These sponges and their spicules grow by putting on concentric layers of silica material on a seasonal basis, rather like tree rings. The concentrations of certain chemicals in the surrounding water, and the growth rate of the sponge itself, are archived in the silica deposited. The information in each layer of silica can be used to deduce environmental conditions on a range of scales; years, decades and centuries. (author). 7 figs

Nafion–clay hybrids with a network structure

KAUST Repository

Burgaz, Engin; Lian, Huiqin; Alonso, Rafael Herrera; Estevez, Luis; Kelarakis, Antonios; Giannelis, Emmanuel P.

2009-01-01

Nafion-clay hybrid membranes with a unique microstructure were synthesized using a fundamentally new approach. The new approach is based on depletion aggregation of suspended particles - a well-known phenomenon in colloids. For certain concentrations of clay and polymer, addition of Nafion solution to clay suspensions in water leads to a gel. Using Cryo-TEM we show that the clay particles in the hybrid gels form a network structure with an average cell size in the order of 500 nm. The hybrid gels are subsequently cast to produce hybrid Nafion-clay membranes. Compared to pure Nafion the swelling of the hybrid membranes in water and methanol is dramatically reduced while their selectivity (ratio of conductivity over permeability) increases. The small decrease of ionic conductivity for the hybrid membranes is more than compensated by the large decrease in methanol permeability. Lastly the hybrid membranes are much stiffer and can withstand higher temperatures compared to pure Nafion. Both of these characteristics are highly desirable for use in fuel cell applications, since a) they will allow the use of a thinner membrane circumventing problems associated with the membrane resistance and b) enable high temperature applications. © 2009 Elsevier Ltd. All rights reserved.

Nafion–clay hybrids with a network structure

KAUST Repository

Burgaz, Engin

2009-05-01

Nafion-clay hybrid membranes with a unique microstructure were synthesized using a fundamentally new approach. The new approach is based on depletion aggregation of suspended particles - a well-known phenomenon in colloids. For certain concentrations of clay and polymer, addition of Nafion solution to clay suspensions in water leads to a gel. Using Cryo-TEM we show that the clay particles in the hybrid gels form a network structure with an average cell size in the order of 500 nm. The hybrid gels are subsequently cast to produce hybrid Nafion-clay membranes. Compared to pure Nafion the swelling of the hybrid membranes in water and methanol is dramatically reduced while their selectivity (ratio of conductivity over permeability) increases. The small decrease of ionic conductivity for the hybrid membranes is more than compensated by the large decrease in methanol permeability. Lastly the hybrid membranes are much stiffer and can withstand higher temperatures compared to pure Nafion. Both of these characteristics are highly desirable for use in fuel cell applications, since a) they will allow the use of a thinner membrane circumventing problems associated with the membrane resistance and b) enable high temperature applications. © 2009 Elsevier Ltd. All rights reserved.

Fluoride retention by kaolin clay

DEFF Research Database (Denmark)

Kau, P. M. H.; Smith, D. W.; Binning, Philip John

1997-01-01

To evaluate the potential effectiveness of kaolin clay liners in storage of fluoride contaminated waste, an experimental study of the sorption and desorption behaviour of fluoride in kaolin clay was conducted. The degree of fluoride sorption by kaolin was found to depend on solution p......H and available fluoride concentration with equilibrium being achieved within 24 h. A site activation process involving the uptake of fluoride was also observed at the initial stages of sorption. This behaviour was attributed to a layer expansion process of the clay during sorption. The maximum fluoride sorption...... capacity was found to be 18.3 meq/100 g at pH 6 and 8.6 meq/100 g at pH 7. A competitive Langmuir sorption isotherm where sorption is dependant on both pH and fluoride concentration is employed to characterise the experimental sorption and desorption data. The sorption and desorption isotherms revealed...

Methyl methacrylate oligomerically-modified clay and its poly(methyl methacrylate) nanocomposites

International Nuclear Information System (INIS)

Zheng Xiaoxia; Jiang, David D.; Wilkie, Charles A.

2005-01-01

A methyl methacrylate oligomerically-modified clay was used to prepare poly(methyl methacrylate) clay nanocomposites by melt blending and the effect of the clay loading level on the modified clay and corresponding nanocomposite was studied. These nanocomposites were characterized by X-ray diffraction, transmission electron microscopy, thermogravimetric analysis and cone calorimetry. The results show a mixed intercalated/delaminated morphology with good nanodispersion. The compatibility between the methylacrylate-subsituted clay and poly(methyl methacrylate) (PMMA) are greatly improved compared to other oligomerically-modified clays

The Composition and Physical Properties of Some Clays of Cross ...

African Journals Online (AJOL)

... and quartz as the main subsidiary non-clay mineral. The high plasticity index of the clays corresponds to the more transported clays of the tertiary- to –recent environment. The percentage of linear shrinkage varied from 11-16% with the lowest shrinkage (11%), having the coarsest features. Silica (SiO2) content of the clays ...

Polyethylene organo-clay nanocomposites: the role of the interface chemistry on the extent of clay intercalation/exfoliation.

Science.gov (United States)

Mainil, Michaël; Alexandre, Michaël; Monteverde, Fabien; Dubois, Philippe

2006-02-01

High density polyethylene (HDPE)/clay nanocomposites have been prepared using three different functionalized polyethylene compatibilizers: an ethylene/vinyl acetate copolymer, a polyethylene grafted with maleic anhydride functions and a (styrene-b-ethylene/butylene-b-styrene) block copolymer. The nanocomposites were prepared via two different routes: (1) the dispersion in HDPE of a masterbatch prepared from the compatibilizer and the clay or (2) the direct melt blending of the three components. For each compatibilizer, essentially intercalated nanocomposites were formed as determined by X-ray diffraction and transmission electron microscopy. With the ethylene/vinyl acetate copolymer, a significant delamination of the intercalated clay in thin stacks was observed. This dispersion of thin intercalated stacks within the polymer matrix allowed increasing significantly the stiffness and the flame resistance of the nanocomposite. A positive effect of shear rate and blending time has also been put into evidence, especially for the process based on the masterbatch preparation, improving both the formation of thin stacks of intercalated clay and the mechanical properties and the flame resistance of the formed nanocomposites.

Search for methylation-sensitive amplification polymorphisms in mutant figs.

Science.gov (United States)

Rodrigues, M G F; Martins, A B G; Bertoni, B W; Figueira, A; Giuliatti, S

2013-07-08

Fig (Ficus carica) breeding programs that use conventional approaches to develop new cultivars are rare, owing to limited genetic variability and the difficulty in obtaining plants via gamete fusion. Cytosine methylation in plants leads to gene repression, thereby affecting transcription without changing the DNA sequence. Previous studies using random amplification of polymorphic DNA and amplified fragment length polymorphism markers revealed no polymorphisms among select fig mutants that originated from gamma-irradiated buds. Therefore, we conducted methylation-sensitive amplified polymorphism analysis to verify the existence of variability due to epigenetic DNA methylation among these mutant selections compared to the main cultivar 'Roxo-de-Valinhos'. Samples of genomic DNA were double-digested with either HpaII (methylation sensitive) or MspI (methylation insensitive) and with EcoRI. Fourteen primer combinations were tested, and on an average, non-methylated CCGG, symmetrically methylated CmCGG, and hemimethylated hmCCGG sites accounted for 87.9, 10.1, and 2.0%, respectively. MSAP analysis was effective in detecting differentially methylated sites in the genomic DNA of fig mutants, and methylation may be responsible for the phenotypic variation between treatments. Further analyses such as polymorphic DNA sequencing are necessary to validate these differences, standardize the regions of methylation, and analyze reads using bioinformatic tools.

Efeito da adubação com boro e esterco bovino sobre a produtividade da figueira e as propriedades químicas do solo Effect of boron and cattle manure fertilization on yield productivity fig tree and on soil properties

Directory of Open Access Journals (Sweden)

Luiz Carlos Santos Caetano

2006-08-01

Full Text Available O objetivo deste trabalho foi verificar o efeito da adubação da cultura da figueira com boro e esterco bovino sobre a produtividade de figos verdes e as propriedades químicas do solo. Os tratamentos foram cinco doses de ácido bórico (0, 20, 40, 60 e 100g planta-1 combinadas com dois níveis de adubação de esterco (sem esterco e 10kg de esterco/planta. O delineamento experimental foi o de blocos casualizados em esquema de parcelas subdivididas e quatro repetições. A adubação com ácido bórico não afetou a produtividade de figos, enquanto que o esterco bovino aumentou-a. Os teores de fósforo e potássio no solo aumentaram significativamente e o teor de alumínio diminuiu significativamente em função da adubação com esterco bovino. O teor de B no solo, extraído pelo método da água quente, aumentou linearmente em função das doses de ácido bórico.The objective of the present work was evaluate the effect of fig tree orchard fertilization with boron and cattle manure on the green fig yield and soil chemical properties. The treatments were five boric acid levels (0, 20, 40, 60 and 100g plant-1 combined with two cattle manure fertilization levels (without cattle manure and 10kg of cattle manure/plant. The experimental design was that of randomized blocks in a split-plot scheme and four repetitions. The boric acid fertilization did not affect the fig productivity whereas the cattle manure one increased it. The P and K content increased significantly and the Al content decreased significantly in function of the cattle manure fertilization. The B soil content, extracted by hot water methodology increased linearly in function of the boric acid levels.

Effects of clay-seam behavior on WIPP repository design

International Nuclear Information System (INIS)

Stone, C.M.; Krieg, R.D.; Branstetter, L.J.

1981-07-01

The geology at the southeastern New Mexico WIPP site consists of bedded layers of rock salt, anhydrite, polyhalite, mixtures of those materials, and thin clay seams. In spite of their very small (0.005 m to 0.05 m) thickness, clay seams are important to structural characterization of the WIPP stratigraphy since slip might possibly take place across them. Results of a study to determine the effects of clay seam frictional slip on the closure of a well-defined drift configuration are described. A Mohr-Coulomb dry friction model was used to model the active clay seams. The main thrust of the study was to determine the effects of friction coefficient variability on drift closure. Results show that the drift closure varies by a factor of 3.0 over the range of friction coefficients studied. The maximum slip observed along any clay seam was 0.12 m. For values of μ > .7, virtually no slip occurs along any clay seam

Fixing of heavy metals by some inflated Tunisian clays

International Nuclear Information System (INIS)

Gharsalli, Jamel

2009-01-01

At the time of discharge of the water polluted in a natural environment and thanks to the properties of retention, adsorption and exchange of ions, clays constitute a natural barrier which will be able to limit the toxicity and the propagation of the pollutants. To contribute to the development of clays layers of Tunisia in the field of water treatments, we undertook with a mineralogical and physicochemical characterization of some inflating clays. The characteristics of these clays will be exploited for the study of the retention by adsorption of some heavy metals. The isotherms of adsorption, of heavy metals in aqueous solution by these natural clays before and after acid activation, are studied. The influence of several parameters on the fixing of heavy metals on clay such as the factors relating to the medium of adsorption (agitation, pH, time of contact, temperature. etc) and those relating to the adsorbent (mass, granulometry, impurities. etc) was studied in order to optimize the operating conditions of adsorptions.

Characterization of organophilic attapulgite clay from state of Piaui

International Nuclear Information System (INIS)

Silva, L.C. dos Santos; Alves, T.S.; Barbosa, R.

2011-01-01

The attapulgite is mineral clay typically fibrous. It owns a superficial area around 125 to 210 m²/g, cationics transfer capacity from 20 to 30 mill equivalents per 100g of clay, high capacity of sorption, considerable decolourizer capacity, chemical inertia and maintenance of thixotropics properties in the presence of electrolytes. The objective of this work was to perform the chemical modification of attapulgite original from state of Piaui - Brazil, for applications in polymeric nanocomposites. The chemical composition of clay without modification was determined by X-Ray Diffraction. The natural clay and organophilizated one were characterized by X-Ray Diffraction (XRD), by Fourier Transform Infra-Red spectroscopy (FTIR), and Foster's swelling. The obtained results indicated the presence of characteristics groups of the salt in the clay, alteration in its chemical composition, evidencing that the chemical modification in the clay was efficient, could the same be applied in preparation of polymeric nanocomposites. (author)

Clay facial masks: physicochemical stability at different storage temperatures.

Science.gov (United States)

Zague, Vivian; de Almeida Silva, Diego; Baby, André Rolim; Kaneko, Telma Mary; Velasco, Maria Valéria Robles

2007-01-01

Clay facial masks--formulations that contain a high percentage of solids dispersed in a liquid vehicle--have become of special interest due to specific properties presented by clays, such as particle size, cooling index, high adsorption capacity, and plasticity. Although most of the physicochemical properties of clay dispersions have been studied, specific aspects concerning the physicochemical stability of clay mask products remain unclear. This work aimed at investigating the accelerated physicochemical stability of clay mask formulations stored at different temperatures. Formulations were subjected to centrifuge testing and to thermal treatment for 15 days, during which temperature was varied from -5.0 degrees to 45.0 degrees C. The apparent viscosity and visual aspect (homogeneity) of all formulations were affected by temperature variation, whereas color, odor, and pH value remained unaltered. These results, besides the estimation of physicochemical stability under aging, can be useful in determining the best storage conditions for clay-based formulations.

Clays in natural and engineered barriers for radioactive waste confinement

International Nuclear Information System (INIS)

2007-01-01

The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO 2 geological sequestration, chemical waste isolation

Clays in natural and engineered barriers for radioactive waste confinement

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO{sub 2} geological sequestration, chemical waste isolation

Mineralogy of subducted clay and clay restite in the lower mantle

Science.gov (United States)

Armstrong, L.; Skora, S. E.; Walter, M. J.

2012-12-01

Seismic tomography indicates that subducting oceanic lithosphere often penetrates the transition zone and eventually the lower mantle [e.g. 1, 2]. While mineralogical changes in the mafic and ultramafic portions of slabs have been well documented experimentally, the phase relations of overlying sediments at pressures above 25 GPa remain poorly studied. This is in part because sediments are expected to partially melt at sub-arc depth (P~2.5-4.5 GPa), and contribute to the genesis of arc magmas. Sediment restites left behind after the extraction of low pressure melts undergo major chemical changes, according to the melting reaction: Coe+Phen+Cpx+H2O = Grt+Ky+Melt [3]. However, sediments may not always melt depending on the thermal regime and volatile availability and composition [3]. Hence, chemically unmodified sediments as well as restites may be entrained to greater depths and contribute to compositional heterogeneity in the deep mantle. Indeed, mineral inclusions with compositions indicative of subducted sedimentary protoliths (CAS-phase; K-hollandite; stishovite) have been reported in 'ultradeep' diamonds and suggest that deep subduction and survival of sediments occurs to at least transition zone depths [4]. With this in mind, we have performed laser heated diamond anvil cell experiments at pressures of 8-80 GPa on two anhydrous glass starting materials: a marine clay and the restite that is left after 50% melt extraction of this clay at 3 GPa and 800 °C [3]. We chose to work with an anhydrous version of the marine clay given that the investigated pressure range exceeds that of phengite stability [5], and phengite is the only hydrous phase in subducted sediments at UHP conditions. The clay was heated along a P-T path representative of a cold subduction geotherm, whereas the clay restite was heated along a hotter subduction geotherm consistent with low pressure melting. Phases were identified by synchrotron X-ray micro-diffraction at beamline I15 of the Diamond

Homogeneity vs. Heterogeneity of Porosity in Boom Clay

International Nuclear Information System (INIS)

Hemes, Susanne; Desbois, Guillaume; Urai, Janos L.; De Craen, Mieke; Honty, Miroslav

2013-01-01

Microstructural investigations on Boom Clay at nano- to micrometer scale, using BIB-SEM methods, result in porosity characterization for different mineral phases from direct observations on high resolution SE2-images of representative elementary areas (REAs). High quality, polished surfaces of cross-sections of ∼ 1 mm 2 size were produced on three different samples from the Mol-Dessel research site (Belgium). More than 33,000 pores were detected, manually segmented and analyzed with regard to their size, shape and orientation. Two main pore classes were defined: Small pores (< 500 nm (ED)) within the clay matrices of samples and =big' pores (> 500 nm (ED)) at the interfaces between clay and non-clay mineral (NCM) grains. Samples investigated show similar porosities regarding the first pore-class, but differences occur at the interfaces between clay matrix and NCM grains. These differences were interpreted to be due to differences in quantitative mineralogy (amount of non-clay mineral grains) and grain-size distributions between samples investigated. Visible porosities were measured as 15 to 17 % for samples investigated. Pore-size distributions of pores in clay are similar for all samples, showing log-normal distributions with peaks around 60 nm (ED) and more than 95 % of the pores being smaller than 500 nm (ED). Fitting pore-size distributions using power-laws with exponents between 1.56 and 1.7, assuming self-similarity of the pore space, thus pores smaller than the pore detection resolution following the same power-laws and using these power-laws for extrapolation of pore-size distributions below the limit of pore detection resolution, results in total estimated porosities between 20 and 30 %. These results are in good agreement with data known from Mercury Porosimetry investigations (35-40 % porosity) and water content porosity measurements (∼ 36 %) performed on Boom Clay. (authors)

Provisional host catalogue of Fig wasps (Hymenoptera, Chalcidoidea)

NARCIS (Netherlands)

Wiebes, J.T.

1966-01-01

INTRODUCTION In this catalogue — entitled "provisional" because our knowledge of the subject is still so evidently incomplete — all species of Ficus mentioned as hosts of fig wasps, are listed with the Hymenoptera Chalcidoidea reared from their receptacles. The names used for the Agaonidae are in

Clay mineral type effect on bacterial enteropathogen survival in soil.

Science.gov (United States)

Brennan, Fiona P; Moynihan, Emma; Griffiths, Bryan S; Hillier, Stephen; Owen, Jason; Pendlowski, Helen; Avery, Lisa M

2014-01-15

Enteropathogens released into the environment can represent a serious risk to public health. Soil clay content has long been known to have an important effect on enteropathogen survival in soil, generally enhancing survival. However, clay mineral composition in soils varies, and different clay minerals have specific physiochemical properties that would be expected to impact differentially on survival. This work investigated the effect of clay materials, with a predominance of a particular mineral type (montmorillonite, kaolinite, or illite), on the survival in soil microcosms over 96 days of Listeria monocytogenes, Salmonella Dublin, and Escherichia coli O157. Clay mineral addition was found to alter a number of physicochemical parameters in soil, including cation exchange capacity and surface area, and this was specific to the mineral type. Clay mineral addition enhanced enteropathogen survival in soil. The type of clay mineral was found to differentially affect enteropathogen survival and the effect was enteropathogen-specific. © 2013.

Characterization of groundwater dynamics in landslides in varved clays

NARCIS (Netherlands)

Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

2013-01-01

Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trieves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

Do scaly clays control seismicity on faulted shale rocks?

Science.gov (United States)

Orellana, Luis Felipe; Scuderi, Marco M.; Collettini, Cristiano; Violay, Marie

2018-04-01

One of the major challenges regarding the disposal of radioactive waste in geological formations is to ensure isolation of radioactive contamination from the environment and the population. Shales are suitable candidates as geological barriers. However, the presence of tectonic faults within clay formations put the long-term safety of geological repositories into question. In this study, we carry out frictional experiments on intact samples of Opalinus Clay, i.e. the host rock for nuclear waste storage in Switzerland. We report experimental evidence suggesting that scaly clays form at low normal stress (≤20 MPa), at sub-seismic velocities (≤300 μm/s) and is related to pre-existing bedding planes with an ongoing process where frictional sliding is the controlling deformation mechanism. We have found that scaly clays show a velocity-weakening and -strengthening behaviour, low frictional strength, and poor re-strengthening over time, conditions required to allow the potential nucleation and propagation of earthquakes within the scaly clays portion of the formation. The strong similarities between the microstructures of natural and experimental scaly clays suggest important implications for the slip behaviour of shallow faults in shales. If natural and anthropogenic perturbations modify the stress conditions of the fault zone, earthquakes might have the potential to nucleate within zones of scaly clays controlling the seismicity of the clay-rich tectonic system, thus, potentially compromising the long-term safeness of geological repositories situated in shales.

Hydroxyapatite clay for gap filling and adequate bone ingrowth.

Science.gov (United States)

Maruyama, M; Terayama, K; Ito, M; Takei, T; Kitagawa, E

1995-03-01

In uncemented total hip arthroplasty, a complete filling of the gap between femoral prosthesis and the host bone is difficult and defects would remain, because the anatomy of the reamed intramedullary canal cannot fit the prosthesis. Therefore, it seems practical to fill the gap with a clay containing hydroxyapatite (HA), which has an osteoconductive character. The clay (HA clay) is made by mixing HA granules (size 0.1 mm or more) having a homogeneous pore distribution and a porosity of 35-48 vol%, and a viscous substance such as a saline solution of sodium alginate (SSSA). In the first experiment, the ratio of HA granules and sodium alginate in SSSA is set for the same handling properties of HA clay and polymethylmethacrylate bone cement (standard viscosity) before hardening. As a result, the ratio is set for 55 wt% of HA in the clay and 12.5 wt% of sodium alginate in SSSA (i.e., HA:sodium alginate:saline solution = 9.8:1:7). In the second study, the gap between the femoral stem and bone model is completely filled with HA clay. However, the gap is not filled only with HA granules or HA granules mixed with saline solution. In the third animal experiment, using an unloaded model, histology shows that HA clay has an osteoconductive property bridging the gap between the implant and the cortical bone without any adverse reaction. HA clay is considered a useful biomaterial to fill the gap with adequate bone ingrowth.

Impact of Oriented Clay Particles on X-Ray Spectroscopy Analysis

Science.gov (United States)

Lim, A. J. M. S.; Syazwani, R. N.; Wijeyesekera, D. C.

2016-07-01

Understanding the engineering properties of the mineralogy and microfabic of clayey soils is very complex and thus very difficult for soil characterization. Micromechanics of soils recognize that the micro structure and mineralogy of clay have a significant influence on its engineering behaviour. To achieve a more reliable quantitative evaluation of clay mineralogy, a proper sample preparation technique for quantitative clay mineral analysis is necessary. This paper presents the quantitative evaluation of elemental analysis and chemical characterization of oriented and random oriented clay particles using X-ray spectroscopy. Three different types of clays namely marine clay, bentonite and kaolin clay were studied. The oriented samples were prepared by placing the dispersed clay in water and left to settle on porous ceramic tiles by applying a relatively weak suction through a vacuum pump. Images form a Scanning Electron Microscope (SEM) was also used to show the comparison between the orientation patterns of both the sample preparation techniques. From the quantitative analysis of the X-ray spectroscopy, oriented sampling method showed more accuracy in identifying mineral deposits, because it produced better peak intensity on the spectrum and more mineral content can be identified compared to randomly oriented samples.

Incorporation of nano-clay saponite layers in the organo-clay hybrid films using anionic amphiphile stearic acid by Langmuir–Blodgett technique

Energy Technology Data Exchange (ETDEWEB)

Hussain, Syed Arshad, E-mail: sa_h153@hotmail.com [Department of Physics, Tripura University, Suryamaninagar-799022 (India); Chakraborty, S.; Bhattacharjee, D. [Department of Physics, Tripura University, Suryamaninagar-799022 (India); Schoonheydt, R.A. [Centres for Surface Chemistry and Catalysis, K.U. Leuven, Kasteelpark Arenberg 23, 3001 Leuven (Belgium)

2013-06-01

In general cationic amphiphiles are used to prepare organo-clay hybrid film in Langmuir–Blodgett (LB) technique. In this present communication we demonstrated a unique technique to prepare the organo–clay hybrid films using an anionic amphiphile. The T–O–T type clay saponite was incorporated onto a floating stearic acid monolayer via a divalent cation Mg{sup 2+}. Salt MgCl{sub 2} was mixed along with the clay dispersion in the LB trough and amphiphile solution was spread onto the subphase in order to make the organo-clay hybrid films. It was observed that salt (MgCl{sub 2}) concentration on the subphase affects the organization of nano-dimensional clay platelet (saponite) in organo-clay hybrid films at air–water interface as well as in LB films. Noticeable changes in area per molecule and shape of the isotherms were observed and measured at subphases with different salt concentrations. Infrared reflection absorption spectroscopy studies reveal that only an in-plane (996 cm{sup −1}) vibration of ν (Si-O) band occurred when the salt concentration was 10 mM. However, both in-plane (996 cm{sup −1}) and out-of-plane (1063 cm{sup −1}) vibrations of the ν (Si-O) band of saponite occurred when the subphase salt concentration was 100 mM. Also the out-of-plane vibration of ν (OH) of saponite was prominent at higher salt concentration. This is because at lower salt concentration clay sheets remain flat on the surface whereas; at higher MgCl{sub 2} concentration they aggregated and form stacks of saponite layers. Also they may be slightly tilted with a very small tilt angle at higher salt concentration making a favorable condition for both in-plane and out-of-plane vibrations of ν (Si-O) in the hybrid films. Observed decrease in starting area per molecule in the pressure area isotherm measured at higher salt concentration also supports the tilting of clay layers at air–clay dispersion interface. Attentuated total reflectance Fourier transform infrared

Application of Logistic Regression Tree Model in Determining Habitat Distribution of Astragalus verus

Directory of Open Access Journals (Sweden)

M. Saki

2013-03-01

Full Text Available The relationship between plant species and environmental factors has always been a central issue in plant ecology. With rising power of statistical techniques, geo-statistics and geographic information systems (GIS, the development of predictive habitat distribution models of organisms has rapidly increased in ecology. This study aimed to evaluate the ability of Logistic Regression Tree model to create potential habitat map of Astragalus verus. This species produces Tragacanth and has economic value. A stratified- random sampling was applied to 100 sites (50 presence- 50 absence of given species, and produced environmental and edaphic factors maps by using Kriging and Inverse Distance Weighting methods in the ArcGIS software for the whole study area. Relationships between species occurrence and environmental factors were determined by Logistic Regression Tree model and extended to the whole study area. The results indicated species occurrence has strong correlation with environmental factors such as mean daily temperature and clay, EC and organic carbon content of the soil. Species occurrence showed direct relationship with mean daily temperature and clay and organic carbon, and inverse relationship with EC. Model accuracy was evaluated both by Cohen’s kappa statistics (κ and by area under Receiver Operating Characteristics curve based on independent test data set. Their values (kappa=0.9, Auc of ROC=0.96 indicated the high power of LRT to create potential habitat map on local scales. This model, therefore, can be applied to recognize potential sites for rangeland reclamation projects.

Biogeomorphic and pedogenic impact of trees in three soil regions

Science.gov (United States)

Pawlik, Łukasz; Šamonil, Pavel

2017-04-01

results from the first site at Turbacz (fir tree stump) indicate some significant differences with higher amount of Cox, clay and C-THS (carbon content in total humus substances), pHH2O and Fe in the control soil profile as compared to stump soil profiles. Content of various chemical indicators were more homogenous between soil profiles at the second microsite (beech). There were significant differences between soil regions for the following chemical properties: N (nitrogen) (AP vs. EP), Cox (oxidized carbon) (AP vs. EP), C-HA (carbon content in humic acids) (AP vs. HC), C-FA (carbon content in fulvic acids) (AP vs. EP), Fed (crystalline forms of iron) (AP and EP vs. HC).

[Mechanism of tritium persistence in porous media like clay minerals].

Science.gov (United States)

Wu, Dong-Jie; Wang, Jin-Sheng; Teng, Yan-Guo; Zhang, Ke-Ni

2011-03-01

To investigate the mechanisms of tritium persistence in clay minerals, three types of clay soils (montmorillonite, kaolinite and illite) and tritiated water were used in this study to conduct the tritium sorption tests and the other related tests. Firstly, the ingredients, metal elements and heat properties of clay minerals were studied with some instrumental analysis methods, such as ICP and TG. Secondly, with a specially designed fractionation and condensation experiment, the adsorbed water, the interlayer water and the structural water in the clay minerals separated from the tritium sorption tests were fractionated for investigating the tritium distributions in the different types of adsorptive waters. Thirdly, the location and configuration of tritium adsorbed into the structure of clay minerals were studied with infrared spectrometry (IR) tests. And finally, the forces and mechanisms for driving tritium into the clay minerals were analyzed on the basis of the isotope effect of tritium and the above tests. Following conclusions have been reached: (1) The main reason for tritium persistence in clay minerals is the entrance of tritium into the adsorbed water, the interlayer water and the structural water in clay minerals. The percentage of tritium distributed in these three types of adsorptive water are in the range of 13.65% - 38.71%, 0.32% - 5.96%, 1.28% - 4.37% of the total tritium used in the corresponding test, respectively. The percentages are different for different types of clay minerals. (2) Tritium adsorbed onto clay minerals are existed in the forms of the tritiated hydroxyl radical (OT) and the tritiated water molecule (HTO). Tritium mainly exists in tritiated water molecule for adsorbed water and interlayer water, and in tritiated hydroxyl radical for structural water. (3) The forces and effects driving tritium into the clay minerals may include molecular dispersion, electric charge sorption, isotope exchange and tritium isotope effect.

Efficacy of Tissue Culture in Virus Elimination from Caprifig and Female Fig Varieties (Ficus carica L.

Directory of Open Access Journals (Sweden)

Chokri Bayoudh

2017-06-01

Full Text Available Fig mosaic disease (FMD is a viral disease that spreads in all Tunisian fig (Ficus carica L. orchards. RT-PCR technique was applied to leaf samples of 29 fig accessions of 15 fig varieties from the fig germplasm collection of High Agronomic Institute (I.S.A of Chatt-Mariem, to detect viruses associated to FMD. Analysis results show that 65.5% of the accessions (19/29 and 80.0% (12/15 of the fig varieties are infected by FMD-associated viruses. From all fig accessions, 41.4% of them are with single infection (one virus and 24.1% are with multi-infections (2 virus and more. Viruses infecting fig leaf samples are Fig mosaic virus (FMV (20.7%, Fig milde-mottle-associated virus (FMMaV (17.25%, Fig fleck associated virus (FFkaV (3.45%, and Fig cryptic virus (FCV (55.17%. A reliable protocol for FCV and FMMaV elimination from 4 local fig varieties Zidi (ZDI, Soltani (SNI, Bither Abiadh (BA, and Assafri (ASF via in vitro culture of 3 meristem sizes was established and optimized. With this protocol, global sanitation rates of 79.46%, 65.55%, 68.75%, and 70.83% respectively for ZDI, SNI, BA, and ASF are achieved. For all sanitized varieties, the effectiveness of meristem culture for the elimination of FCV and FMMaV viruses was related to meristem size. Meristem size 0.5 mm provides the highest sanitation rates ranging from 70% to 90%.

The many ways of making anionic clays

Indian Academy of Sciences (India)

Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

Clay as Thermoluminescence Dosemeter in diagnostic Radiology ...

African Journals Online (AJOL)

This paper reports the investigation of the basic thermoluminescence properties of clay at x-rays in the diagnostic radiology range, including dose monitoring in abdominal radiography. Clay sourced from Calabar, Nigeria, was tested for thermoluminescence response after irradiation at diagnostic radiology doses, including ...

Characterization of groundwater dynamics in landslides in varved clays

NARCIS (Netherlands)

Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

2013-01-01

Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trièves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

Clay minerals as palaeoenvironment indicators exemplified on a Karoo sequence from the Bothaville area, South Africa

International Nuclear Information System (INIS)

Buehmann, C.; Buehmann, D.

1990-01-01

The whole-rock and clay mineral composition of 74 samples from a 184 m borehole core from the Ecca Group and Dwyka Formation from the vicinity of Bothaville, 100 km southwest of Johannesburg, South Africa, has been determined by means of X-ray diffractometry. The objective was to establish the salinity and pH of the water of the original environments of deposition. The sediment investigated was subjected to a low degree of diagenesis. Clay mineral associations display characteristic variations while distinctive vertical trends in kaolinite occurrence have been established. Mineralogical trends are ascribed to fundamental changes, which must have existed in the pore fluid composition during deposition (palaeoenvironment setting) which have been maintained through the early stages of diagenesis. Conditions were alkaline-marine during the Dwyka and in the lower section of the Vryheid Formation, as indicated by the dominance of 2:1 layer silicates. From the middle section of the Vryheid Formation the entire brackish water mixing range is recorded mineralogically by kaolinite contents which increase progressively at the cost of 2:1 layer silicates. Acid-freshwater conditions, characterised by the dominance of kaolinite are interpreted for the upper section of the Vryheid Formation. 26 refs., 6 figs., 2 tabs

Performance Study of the Natural Rubber Composite with Clay Minerals

International Nuclear Information System (INIS)

Nyo Nyo Myint; Tin Tin Aye; Kyaw Myo Naing; Nyunt Wynn

2008-03-01

The preparation, characterization and some applications of natural rubber clay composite have been studied. This study investigated the possibility of natural rubber latex to replace some part of natural clays. In formulation of rubber clay composite from natural rubber latex and various clay minerals, three main steps were involved (i) preparation of latex cream (ii) prevulcanization of latex cream (iii) mixing vulcanized latex compound, with other ingredients. In each step, several parameters have been carefully investigated to optimize the performance of natural rubber clay composite production. The composite products were of better quality and can be considered to be more cost effective.

Radionuclide sorption studies on abyssal red clays

International Nuclear Information System (INIS)

Erickson, K.L.

1979-01-01

The radionuclide sorption properties of a widely distributed abyssal red clay are being experimentally investigated using batch equilibration techniques. This paper summarizes sorption equilibrium data obtained when 0.68 N NaCl solutions containing either Tc, U, Pu, Am or Cm were contacted with samples of the red clay and also summarizes some initial results from experiments designed to determine the relative selectivity of the clay for various nuclides. Under mildly oxidizing conditions, the sorption equilibrium distribution coefficients for technetium were essentially zero. At solution-phase nuclide concentrations on the order of 10 -6 M and less and at solution pH values of about 6.9, the distribution coefficients for plutonium were about 3 x 10 3 m1/gm and for uranium, americium, and curium were about 10 5 ml/gm or greater. However, at solution pH values of about 2.7, the distribution coefficients for each of the nuclides were greatly diminished. Initial experiments conducted in order to determine the relative selectivity of the clay for cesium, barium, and cerium, indicated that the silicate phases in the clay were selective for cesium over barium and cerium. These experiments also indicated that the hydrous oxide phases were selective for cerium over barium and for barium over cesium

Permeability response of oil-contaminated compacted clays

International Nuclear Information System (INIS)

Silvestri, V.; Mikhail, N.; Soulie, M.

1997-01-01

This paper presents the results of a laboratory investigation on the behavior of motor oil-contaminated, partially saturated compacted clays. For the study, both a natural clay and an artificially purified kaolinite, contaminated with 0 to 8% of motor oil, were firstly compacted following the ASTM standard procedure. Secondly, permeability tests were carried out in a triaxial cell on 10 cm-diameter compacted clay specimens. The results of the investigation indicate that increasing percentages of motor oil decrease both the optimum water content and the optimum dry density of the two clays. However, whereas the optimum water content on the average decreases by about 6% when the percentage contamination increases from 0 to 8%, the corresponding decrease in the optimum dry density is less than 3%. Even though the optimum dry density decreases as the percentage of oil increases from 0 to 8%, there is, however, a range in oil content varying between 2 and 4% for which the optimum dry density is slightly greater than that of the untreated soils. As far as the permeability tests are concerned, the results indicate that as the percentage of oil increases, the coefficient of permeability decreases substantially, especially for clay specimens which were initially compacted on the dry side of optimum

Comparisons of host mitochondrial, nuclear and endosymbiont bacterial genes reveal cryptic fig wasp species and the effects of Wolbachia on host mtDNA evolution and diversity

Directory of Open Access Journals (Sweden)

Feng Gui

2011-04-01

Full Text Available Abstract Background Figs and fig-pollinating wasp species usually display a highly specific one-to-one association. However, more and more studies have revealed that the "one-to-one" rule has been broken. Co-pollinators have been reported, but we do not yet know how they evolve. They may evolve from insect speciation induced or facilitated by Wolbachia which can manipulate host reproduction and induce reproductive isolation. In addition, Wolbachia can affect host mitochondrial DNA evolution, because of the linkage between Wolbachia and associated mitochondrial haplotypes, and thus confound host phylogeny based on mtDNA. Previous research has shown that fig wasps have the highest incidence of Wolbachia infection in all insect taxa, and Wolbachia may have great influence on fig wasp biology. Therefore, we look forward to understanding the influence of Wolbachia on mitochondrial DNA evolution and speciation in fig wasps. Results We surveyed 76 pollinator wasp specimens from nine Ficus microcarpa trees each growing at a different location in Hainan and Fujian Provinces, China. We found that all wasps were morphologically identified as Eupristina verticillata, but diverged into three clades with 4.22-5.28% mtDNA divergence and 2.29-20.72% nuclear gene divergence. We also found very strong concordance between E. verticillata clades and Wolbachia infection status, and the predicted effects of Wolbachia on both mtDNA diversity and evolution by decreasing mitochondrial haplotypes. Conclusions Our study reveals that the pollinating wasp E. verticillata on F. microcarpa has diverged into three cryptic species, and Wolbachia may have a role in this divergence. The results also indicate that Wolbachia strains infecting E. verticillata have likely resulted in selective sweeps on host mitochondrial DNA.

Verification of substitution of bentonites by montmorillonitic clays summary report on Czech montmorillonitic clays

International Nuclear Information System (INIS)

Carlson, L.; Keto, P.

2006-10-01

Czech bentonites and smectite-rich clays were characterised in order to study if they could be used as buffer and backfill materials instead of non-Czech commercial bentonites. The characterisation work was orgnized by RAWRA (the Czech Radioactive Waste Repository Authority) and the main part of the work was performed in the Czech Republic at Charles University and at Czech Technical University. Parallel and complementary characterisation was conducted in Finland in Sweden. This report was compiled with the aim to summarise the results, and to compare the methods and results gained in different testing laboratories. The characterisation included mineralogical, chemical and geotechnical investigations and experiments on thermal stability and sorption. There were some variations between the results gained in different laboratories. This was mainly due to differences between the testing methods used but also due to heterogeneity of the samples. The Czech bentonite-clays from Rokle and Strance clay deposits contained relatively high amount of swelling minerals and thus can be considered as potential buffer and backfill materials. (orig.)

Toxicological evaluation of clay minerals and derived nanocomposites: a review.

Science.gov (United States)

Maisanaba, Sara; Pichardo, Silvia; Puerto, María; Gutiérrez-Praena, Daniel; Cameán, Ana M; Jos, Angeles

2015-04-01

Clays and clay minerals are widely used in many facets of our society. This review addresses the main clays of each phyllosilicate groups, namely, kaolinite, montmorillonite (Mt) and sepiolite, placing special emphasis on Mt and kaolinite, which are the clays that are more frequently used in food packaging, one of the applications that are currently exhibiting higher development. The improvements in the composite materials obtained from clays and polymeric matrices are remarkable and well known, but the potential toxicological effects of unmodified or modified clay minerals and derived nanocomposites are currently being investigated with increased interest. In this sense, this work focused on a review of the published reports related to the analysis of the toxicological profile of commercial and novel modified clays and derived nanocomposites. An exhaustive review of the main in vitro and in vivo toxicological studies, antimicrobial activity assessments, and the human and environmental impacts of clays and derived nanocomposites was performed. From the analysis of the scientific literature different conclusions can be derived. Thus, in vitro studies suggest that clays in general induce cytotoxicity (with dependence on the clay, concentration, experimental system, etc.) with different underlying mechanisms such as necrosis/apoptosis, oxidative stress or genotoxicity. However, most of in vivo experiments performed in rodents showed no clear evidences of systemic toxicity even at doses of 5000mg/kg. Regarding to humans, pulmonary exposure is the most frequent, and although clays are usually mixed with other minerals, they have been reported to induce pneumoconiosis per se. Oral exposure is also common both intentionally and unintentionally. Although they do not show a high toxicity through this pathway, toxic effects could be induced due to the increased or reduced exposure to mineral elements. Finally, there are few studies about the effects of clay minerals on

Effects of sand compaction pile (SCP) driving on the strength of clay outside the improved area; Sand compaction pile no dasetsu ga jiban kairyo ikigai no nendo jiban no kyodo ni oyobosu eikyo

Energy Technology Data Exchange (ETDEWEB)

Matsuda, H. [Yamaguchi University, Yamaguchi (Japan); Takahashi, S. [Ministry of Transport, Tokyo (Japan); Fujiwara, K. [Penta-Ocean Construction Co. Ltd., Tokyo (Japan); Kitayama, N. [Fukken Co. Ltd., Hiroshima (Japan)

1998-06-21

This paper describes effects of the disturbance by the sand compaction pile (SCP) driving operations on the shear strength of clay outside the improved area and the border of region affected by the SCP driving. About 1,400 soil specimens were taken before and after the SCP driving inside and outside the improved area during the foundation improvement at Tokuyama-Shimomatsu Port in Yamaguchi Prefecture. Soil test data of the specimens and strength characteristics of disturbed clay specimens were investigated through the laboratory experiments. The results obtained are as follows. According to the multi-directional simple shear test results, the shear strength immediately after the cyclic shear decreased in 10 to 30% compared with that before the cyclic shear. When recompaction was conducted before the cyclic shear, however, it increased in 50% compared with that before the cyclic shear. The strength of clay decreased by the SCP driving even outside the improved area. When the internal frictional angle of clay, friction coefficient of the improved boundary and driving depth of SCP were determined, it was possible to estimate an area affected by the SCP driving using a combined sliding plane. 21 refs., 18 figs.

Effect of red clay on diesel bioremediation and soil bacterial community.

Science.gov (United States)

Jung, Jaejoon; Choi, Sungjong; Hong, Hyerim; Sung, Jung-Suk; Park, Woojun

2014-08-01

Red clay is a type of soil, the red color of which results from the presence of iron oxide. It is considered an eco-friendly material, with many industrial, cosmetic, and architectural uses. A patented method was applied to red clay in order to change its chemical composition and mineral bioavailability. The resulting product was designated processed red clay. This study evaluates the novel use of red clay and processed red clay as biostimulation agents in diesel-contaminated soils. Diesel biodegradation was enhanced in the presence of red clay and processed red clay by 4.9- and 6.7-fold, respectively, and the number of culturable bacterial cells was correlated with the amount of diesel biodegradation. The growth of Acinetobacter oleivorans DR1, Pseudomonas putida KT2440, and Cupriavidus necator was promoted by both types of red clays. Culture-independent community analysis determined via barcoded pyrosequencing indicated that Nocardioidaceae, Xanthomonadaceae, Pseudomonadaceae, and Caulobacteraceae were enriched by diesel contamination. Bacterial strain isolation from naphthalene- and liquid paraffin-amended media was affiliated with enriched taxa based on 16S rRNA gene sequence identity. We suggest that the biostimulating mechanism of red clay and processed red clay is able to support bacterial growth without apparent selection for specific bacterial species.

STUDY OF THERMAL AND ACID STABILITY OF BENTONITE CLAY

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Karna Wijaya

2010-06-01

Full Text Available The thermal and acid stability of the bentonite clays (Na- and Ca-bentonite have been tested. The thermal stability testing has been carried out by heating 5 gram of the clays  for five hours at 200, 300 and 500 °C respectively, meanwhile acid stability testing was performed by immersing 5 gram clays into 100 mL sulphuric acid 1M, 2M and 3M for 24 hours. The tested clays, then were characterized by means of X-Ray difractometry and IR-spectroscopy methods. The characterization results showed that upon heating, both Ca- and Na-bentonites indicated same thermal stability. However, upon acid treatment, Na-bentonite was found relatively stabiler and more resistance then Ca-bentonite.   Keywords: bentonite, clay, thermal stability, acid stability.

Structural characterization of clays commercially used in red ceramics

International Nuclear Information System (INIS)

Brito, E.M.; Moura, J.K.L.; Souza, R.B.; Brandim, A.S.

2014-01-01

The use of clays hills being an alternative to clay floodplain, due to environmental protection laws. The research project aims at the morphological and chemical characterization of hills clays used industrially for the production of ceramic tiles and blocks. Therefore, two types of methods were known commercially in the region of Teresina-PI through diffraction of X-rays (X-DR), scanning electron microscopy (SEM) and energy dispersive spectrometry X-ray (EDS). It can be observed that the samples have a high percentage of quartz, hematite still having in its constitution aluminum oxide, zirconium oxide and titanium oxide. The results show that the clays are clays and montmorillonites may be used for the production of ceramic tiles and blocks, but as the proportion of using the same will be focusing the next job. (author)

The molecular aggregation of pyronin Y in natural bentonite clay suspension

International Nuclear Information System (INIS)

Meral, Kadem; Yilmaz, Nuray; Kaya, Mehmet; Tabak, Ahmet; Onganer, Yavuz

2011-01-01

The molecular aggregation and spectroscopic properties of Pyronin Y (PyY) in the suspension containing natural bentonite clay were studied using molecular absorption, steady-state and time-resolved fluorescence spectroscopy techniques. Interaction between the clay particles and the cationic dye compounds in aqueous solution resulted in significant changes in spectral properties of PyY compared to its molecular behavior in deionized water at the same concentration. These changes were due to the formation of dimer and aggregate of PyY in the clay suspension as well as the presence of the dye monomer. The H-type aggregates of PyY in the clay suspension were identified by the observation of a blue-shifted absorption band of the dye compared to that of its monomer. In spite of diluted dye concentrations, the H-aggregate of PyY in the clay suspension was formed. The intensive aggregation in the clay suspension attributed to the localized high dye concentration on the negatively charged clay surfaces. Adsorption sites of PyY on the clay particles were discussed by deconvulated absorption and excitation spectra. Fluorescence spectroscopy studies revealed that the fluorescence intensity of PyY in the clay suspension is decreased by H-aggregates drastically. Moreover, the presence of H-aggregates in the clay suspension resulted in the decrease of fluorescence lifetime and quantum yield of PyY compared to those in deionized water. - Highlights: → Molecular behavior of PyY adsorbed on clay surface was followed spectroscopically. → H-aggregates of PyY in the clay suspension were formed at very low dye concentrations. → The intensive H-aggregate structure drastically reduced the fluorescence intensity of PyY. → The fluorescence lifetime and quantum yield of PyY in the clay suspension was discussed.

Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres.

Science.gov (United States)

Frindy, Sana; Primo, Ana; Qaiss, Abou El Kacem; Bouhfid, Rachid; Lahcini, Mohamed; Garcia, Hermenegildo; Bousmina, Mosto; El Kadib, Abdelkrim

2016-08-01

Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel-forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicity in the order CSclay microstructure, an improvement in the mechanical properties of the chitosan-clay films has been substantiated with CS-SP reaching the highest value at 5% clay loading. While clay addition provides a way to resist the shrinkage occurring for native chitosan, the enhanced hydrophilicity associated to the water content affects the efficacy of the CO2 super-critical drying as the most hydrophilic CS-SP microspheres face the highest shrinkage, resulting in a lowest specific surface area compared to CS-HNT and CS-MMT. Chitosan-clay exhibits enhanced thermal properties with the degradation delayed in the order CSclay compared to native chitosan, evidencing the beneficial protective effect of the clay particulates for the biopolymer. However, under hydrothermal treatment, the presence of clay was found to be detrimental to the material stability as a significant shrinkage occurs in hybrid CS-clay microspheres, which is attributed again to their increased hydrophilicity compared to the native polymeric microspheres. In this framework, a peculiar behavior was observed for CS-MMT, with the microspheres standing both against contraction during CO2 gel drying and under hydrothermal conditions. The knowledge gained from this rational design will constitute a guideline toward the preparation of ultra-stable, practically-optimized food-packaging films and commercially scalable porous bio-based adsorbents. Copyright © 2016 Elsevier Ltd. All rights reserved.

Thermo Gravimetric and Differential Thermal Analysis of Clay of Western Rajasthan (india)

Science.gov (United States)

Shekhawat, M. S.

The paper presents the study of thermo gravimetric and differential thermal analysis of blended clay. Western part of Rajasthan (India) is rich resource of Ball clays and it is mainly used by porcelain, sanitary ware, and tile industry. The quality and grade of clay available in the region vary from one deposit to other. To upgrade the fired colour and strength properties, different variety of clays may be blended together. The paper compares the results of thermal analysis one of blended clay B2 with reference clay of Ukraine which is imported by industries owners. The result revealed that the blended clay is having mineral kaolinite while the Ukrainian clay is Halloysite.

Research on swelling clays and bitumen as sealing materials for radioactive waste repositories

International Nuclear Information System (INIS)

Allison, J.A.; Wilson, J.; Mawditt, J.M.; Hurt, J.C.

1991-01-01

This report describes a programme of research to investigate the performance of composite seals incorporating adjacent blocks of swelling clay and bitumen. It is shown that the interaction of the materials can promote a self-sealing mechanism which prevents water penetration, even when defects are present in the bitumen layer. A review of the swelling properties of highly compacted bentonite and magnesium oxide is presented, and the characteristic sealing properties of bituminous materials are described. On the basis of this review, it is concluded that bentonite is the preferred candidate material for use in composite clay/bitumen seals for intermediate-level radioactive waste repositories. However, it is thought that magnesium oxide may have other sealing applications for high-level waste repositories. A programme of laboratory experiments is described in which relevant swelling and intrusion properties of highly compacted bentonite blocks and the annealing characteristics of oxidised and hard-grade industrial bitumens are examined. The results of composite sealing experiments involving different water penetration routes are reported, and factors governing the mechanism of self-sealing are described. The validation of the sealing concept at a laboratory scale indicates that composite bentonite/bitumen seals could form highly effective barriers for the containment of radioactive wastes. Accordingly, recommendations are made concerning the development of the research, including the implementation of full-scale demonstration experiments to simulate conditions in an underground repository. 13 tabs., 41 figs., 62 refs

Production of smectite organophylic clays from three commercial sodium bentonite

International Nuclear Information System (INIS)

Valenzuela Diaz, Francisco R.; Souza Santos, Persio de

1995-01-01

Laboratory cationic exchange procedures using Brazilian's commercial quaternary ammonium salt and three samples of commercial sodium bentonites (two Brazilian's and one from Wyoming (US) are described. Swelling values in some liquid organic media are shown for the organophilic clays and for a Brazilian's commercial organophilic clay. Organophilic clays with larger swelling values than the commercial organophilic clay in kerosene, Varsol, toluene and soya bean oil were obtained. (author)

Fault tree and failure mode and effects analysis of a digital safety function

International Nuclear Information System (INIS)

Maskuniitty, M.; Pulkkinen, U.

1995-01-01

The principles of fault tree and failure mode and effects analysis (FMEA) for the analysis of digital safety functions of nuclear power plants are discussed. Based on experiences from a case study, a proposal for a full scale analysis is presented. The feasibility and applicability the above mentioned reliability engineering methods are discussed. (author). 13 refs, 1 fig., 2 tabs

Laboratory study of the Flandres clay swelling

International Nuclear Information System (INIS)

Khaddaj, Said

1992-01-01

The first chapter contains a survey about the swelling of soils, and about the experimental methods used to characterize this phenomenon. A classification of soils in function of their swelling potential is proposed. The second chapter deals with the properties of Flandres clay. Chemical and mineralogical compositions, mechanical properties and free swell index are given. The third chapter contains a presentation of the study of the swelling potential of Flandres clay using the oedometer. Four methods are described and used (free-swell, different pressures, pre-swell and direct-swell). A numerical simulation of free-swell tests is also given. The fourth chapter includes a presentation of the study of the swelling behaviour of Flandres clay using a triaxial cell. Three methods are used: free-swell, pre-swell and different-pressures. The last chapter contains a parametric study of the swelling behaviour of Flandres clay. The influence of some parameters such as sample thickness, initial water content, vertical load and load history is presented. (author) [fr

Geochemical effects of electro-osmosis in clays

KAUST Repository

Loch, J. P. Gustav

2010-02-13

Geochemical effects of electro-osmosis in bentonite clay are studied in the laboratory, where a 6 mm thick bentonite layer is subjected to direct current. Acidification and alkalization near anode and cathode are expected, possibly causing mineral deterioration, ion mobilization and precipitation of new solids. Afterwards the clay is analysed by XRF and anolyte and catholyte are analysed by ICP-MS. In addition, as a preliminary experiment treated bentonite is analysed by high resolution μ-XRF. Electro-osmotic flow is observed. Due to its carbonate content the bentonite is pH-buffering. Alkalization in the catholyte is substantial. Ca, Na and Sr are significantly removed from the clay and accumulate in the catholyte. Recovery in the catholyte accounts for a small fraction of the element-loss from the clay. The rest will have precipitated in undetected solid phases. μ-XRF indicates the loss of Ca-content throughout the bentonite layer. © The Author(s) 2010.

Clay-cement suspensions - rheological and functional properties

Science.gov (United States)

Wojcik, L.; Izak, P.; Mastalska-Poplawska, J.; Gajek, M.

2017-01-01

The piping erosion in soil is highly unexpected in civil engineering. Elimination of such damages is difficult, expensive and time-consuming. One of the possibility is the grouting method. This method is still developed into direction of process automation as well as other useful properties of suspensions. Main way of modernization of the grouting method is connected it with rheology of injection and eventuality of fitting them to specific problems conditions. Very popular and useful became binders based on modified clays (clay-cement suspensions). Important principle of efficiency of the grouting method is using of time-dependent pseudothixotropic properties of the clay-cement suspensions. The pseudo-rheounstability aspect of the suspensions properties should be dedicated and fitted to dynamic changes of soil conditions destructions. Whole process of the modification of the suspension rheology is stimulated by the specific agents. This article contains a description of practical aspects of the rheological parameters managing of the clay-cement suspensions, dedicated to the building damages, hydrotechnic constructions etc.

Effects of the pear tree canopy on photosynthetically active radiation availability

International Nuclear Information System (INIS)

Rossi, F.; Baldini, E.; Baraldi, R.

1984-01-01

The relationships existing between radiant energy and photosynthesis have been extensively investigated on the apple /2/ but not on the other fruit trees, pear included. In addition, such information resists generalization, owing to the remarkable differences underlying tree morphology and physiology of the different species; furthermore, some disagreement arises regarding the terminology and the units used to evaluate the amount of radiant energy useful for the photosynthetic process. In general this evaluation is based on the readouts of illuminance (symbol Ev; unit: lux), in agreement with the photopic curve (fig. 1:A), i.e. with the human eye sensibility to the visible radiation(light). However, the relative response of the chloroplasts to the radiant flux, although included within the same spectral wavebands as the photopic curve, follows a different model (fig.1:B), that is, it has two peaks in connection with the spectral wavelenghts of blue (440–490 nm), and, particularly, of red (620–700 nm). Therefore, according to a number of authors /3/6/8/11/, the correct evaluation of the photosynthetically active radiation should be made using sensors calibrated to measure the photosynthetic photon lux density (symbol: PPFD; unit: μE m -2 s -1 ), and provided with a relative spectral response similar to that of the leaves. (author)

Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

Directory of Open Access Journals (Sweden)

Jiang-Jen Lin

2010-04-01

Full Text Available Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropyleneamine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE, enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

Hydrophobic Modification of Layered Clays and Compatibility for Epoxy Nanocomposites

Science.gov (United States)

Lin, Jiang-Jen; Chan, Ying-Nan; Lan, Yi-Fen

2010-01-01

Recent studies on the intercalation and exfoliation of layered clays with polymeric intercalating agents involving poly(oxypropylene)-amines and the particular uses for epoxy nanocomposites are reviewed. For intercalation, counter-ionic exchange reactions of clays including cationic layered silicates and anionic Al-Mg layered double hydroxide (LDH) with polymeric organic ions afforded organoclays led to spatial interlayer expansion from 12 to 92 Å (X-ray diffraction) as well as hydrophobic property. The inorganic clays of layered structure could be modified by the poly(oxypropylene)amine-salts as the intercalating agents with molecular weights ranging from 230 to 5,000 g/mol. Furthermore, natural montmorillonite (MMT) clay could be exfoliated into thin layer silicate platelets (ca. 1 nm thickness) in one step by using polymeric types of exfoliating agents. Different lateral dimensions of MMT, synthetic fluorinated Mica and LDH clays had been cured into epoxy nanocomposites. The hydrophobic amine-salt modification resulting in high spacing of layered or exfoliation of individual clay platelets is the most important factor for gaining significant improvements of properties. In particular, these modified clays were reported to gain significant improvements such as reduced coefficient of thermal expansion (CTE), enhanced thermal stability, and hardness. The utilization of these layered clays for initiating the epoxy self-polymerization was also reported to have a unique compatibility between clay and organic resin matrix. However, the matrix domain lacks of covalently bonded crosslink and leads to the isolation of powder material. It is generally concluded that the hydrophobic expansion of the clay inter-gallery spacing is the crucial step for enhancing the compatibility and the ultimate preparation of the advanced epoxy materials.

Modified montmorillonite clay microparticles for stable oil-in-seawater emulsions.

Science.gov (United States)

Dong, Jiannan; Worthen, Andrew J; Foster, Lynn M; Chen, Yunshen; Cornell, Kevin A; Bryant, Steven L; Truskett, Thomas M; Bielawski, Christopher W; Johnston, Keith P

2014-07-23

Environmentally benign clay particles are of great interest for the stabilization of Pickering emulsions. Dodecane-in-synthetic seawater (SSW) emulsions formed with montmorillonite (MMT) clay microparticles modified with bis(2-hydroxyethyl)oleylamine were stable against coalescence, even at clay concentrations down to 0.1% w/v. Remarkably, as little as 0.001% w/v surfactant lowered the hydrophilicity of the clay to a sufficient level for stabilization of oil-in-SSW emulsions. The favorable effect of SSW on droplet size reduction and emulsion stability enhancement is hypothesized to be due to reduced electrostatic repulsion between adsorbed clay particles and a consequent increase in the continuous phase (an aqueous clay suspension) viscosity. Water/oil (W/O) emulsions were inverted to O/W either by decreasing the mass ratio of surfactant-to-clay (transitional inversion) or by increasing the water volume fraction (catastrophic inversion). For both types of emulsions, coalescence was minimal and the sedimentation or creaming was highly correlated with the droplet size. For catastrophic inversions, the droplet size of the emulsions was smaller in the case of the preferred curvature. Suspensions of concentrated clay in oil dispersions in the presence of surfactant were stable against settling. The mass transfer pathways during emulsification of oil containing the clay particles were analyzed on the droplet size/stability phase diagrams to provide insight for the design of dispersant systems for remediating surface and subsurface oceanic oil spills.

Toxic element composition of multani mitti clay for nutritional safety

International Nuclear Information System (INIS)

Waheed, S.; Faiz, Y.; Rahman, S.; Siddique, N.

2013-01-01

Geophagy of multani mitti (MM) clay is very common in central Pakistan especially amongst women. It was therefore mandatory to establish baseline levels of toxic elements in this clay for its safe dietary consumption by consumers of different genders, age groups and physical states. Instrumental neutron activation analysis and atomic absorption spectrometry techniques were used to determine the nutritional safety of MM clay for oral intake. All quantified toxic elements were detected at trace levels with composition in the descending order; Pb > Br > As > Sb > Hg > Cd. Comparison of these elements in MM clay with other clays shows that As, Cd, and Pb, are lowest in MM clay while its Br and Hg contents are high. Highest weekly dietary intakes of As, Br, Cd, Hg, and Sb were found to be 18, 0.05, 1.6, 9.2 and 1.1 % of the respective recommended provisional tolerable weekly intakes. The findings of this study show that As, Br, Cd, Hg and Sb in MM clay are well below the tolerance levels. However its Pb concentration is very high and may pose health concerns. The data presented in this study can be used as national base level guideline for geophagy of MM clay by men, women (normal, pregnant and lactating) and children. (author)

Stochastic Dynamics of Clay Translocation and Formation of Argillic Horizons

Science.gov (United States)

Calabrese, S.; Richter, D. D., Jr.; Porporato, A. M.

2017-12-01

The formation of argillic horizons in vertical soil profiles is mainly attributed to lessivage, namely the transport of clay from an upper E horizon to a deeper illuviated horizon. Because of the long timescales involved in this phenomenon, quantitative modeling is useful to explore the role of clay lessivage on soil formation and sub-surface clay accumulation. The limitations of detailed models of colloidal transport to short timescales make it necessary to resort to simple models. Here, we present a parsimonious model of clay transport in which lessivage is interpreted stochastically. Clay particles approach the soil surface at a speed equal to the erosion rate and are intermittently transported to deeper soil layers when percolation events occur or removed by erosion. Along with the evolution of clay particles trajectories, the model predicts the vertical clay profile, the depth of the B horizon, and the mean time to erosion. Dimensional analysis reveals the two dimensionless parameters governing the dynamics, leading to a new classification of soil types based on erosion rates and intensity of lessivage.

Quick clay and landslides of clayey soils

NARCIS (Netherlands)

Khaldoun, A.; Moller, P.; Fall, A.; Wegdam, G.; de Leeuw, B.; Méheust, Y.; Fossum, J.O.; Bonn, D.

2009-01-01

We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay

Studies on thermal reactions and sintering behaviour of red clays by irreversible dilatometry

Science.gov (United States)

Anil, Asha; Misra, S. N.; Misra, N. M.

2018-05-01

Thermal behavior of clays strongly influences that of ceramic bodies made thereof and hence, its study is must for assessing its utility in ceramic products as well as to set the body composition. Irreversible dilatometry is an effective thermal analysis tool for evaluating thermal reactions as well as sintering behavior of clays or clay based ceramic bodies. In this study, irreversible dilatometry of four red clay samples (S, M, R and G) of Gujarat region, which vary in their chemical and mineralogical compositions was carried out using a Dilatometer and compared. Chemical analysis and XRD of red clays were carried out. XRD showed that major clay minerals in S, M and R clays are kaolinite. However, clay marked R and G showed presence of both kaolinite and illite and /muscovite. Presence of non-clay minerals such as hematite, quartz, anatase were also observed in all clays. XRD results were in agreement with chemical analyses results. Rational analyses showed variation in amount of clay and non-clay minerals in red clay samples. Evaluation of dilatometric curves showed that clay marked as S, M and R exhibit patterns typical for kaolinitic clays. Variation in linear expansion (up to 550°C) and shrinkage (above 550°C) between these three clays was found to be related to difference in amount of quartz and kaolinite respectively. However, dilatometric curve of G exhibit a pattern similar to that for an illitic clay. This study confirmed that sintering of investigated kaolinitic and illitic and / muscovitic red clays initiates at above 1060°C and 860°C respectively and this behaviour strongly depends upon type and amount of minerals and their chemical compositions.

Synchrotron SAXS/WAXD and rheological studies of clay suspensions in silicone fluid.

Science.gov (United States)

Zhang, Li-Ming; Jahns, Christopher; Hsiao, Benjamin S; Chu, Benjamin

2003-10-15

Suspensions of two commercial smectite clays, montmorillonite KSF and montmorillonite K10, in a low-viscosity silicone oil (Dow Corning 245 Fluid) were studied by simultaneous synchrotron small-angle X-ray scattering (SAXS)/wide-angle X-ray diffraction (WAXD) techniques and rheological measurements. In the 0.5% (w/v) KSF clay suspension and two K10 clay suspensions (0.5% and 1.0%), WAXD profiles below 2theta=10.0 degrees did not display any characteristic reflection peaks associated with the chosen montmorillonite clays, while corresponding SAXS profiles exhibited distinct scattering maxima, indicating that both clays were delaminated by the silicone oil. In spite of the large increase in viscosity, the clay suspensions exhibited no gel characteristics. Dynamic rheological experiments indicated that the clay/silicone oil suspensions exhibited the behavior of viscoelasticity, which could be influenced by the type and the concentration of the clay. For the K10 clay suspensions, the frequency-dependent loss modulus (G") was greater in magnitude than the storage modulus (G') in the concentration range from 0.5 to 12.0%. The increase in the clay concentration shifted the crossover point between G' and G" into the accessible frequency range, indicating that the system became more elastic. In contrast, the KSF clay suspension exhibited lower G' and G" values, indicating a weaker viscoelastic response. The larger viscoelasticity response in the K10 clay suspension may be due to the acid treatment generating a higher concentration of silanol groups on the clay surface.

Long-term performance of geosynthetic clay liners in cappings

International Nuclear Information System (INIS)

Maubeuge, K.P. von; Fricke, A.

1998-01-01

Geosynthetic clay liners (GCLs) are relatively thin composite materials combining bentonite clay and geosynthesis (usually geotextiles). GCLs have been employed by the waste industry for well over a decade now, and their level of usage is rapidly increasing world-wide. In landfill facilities, GCLs are generally used to replace or augment compacted clay liners. Until recently, the decision to do so has primarily been based on the availability of clay material on site (i.e., economic considerations). However, the advantages in using a GCL over other sealing elements such as compacted clay are not only economic but technically based, and the economic benefits extend beyond the construction phase, as a thin GCL can increase the revenue earning potential of a facility. This paper will highlight the shear behaviour of GCLs and demonstrate the long-term stability. (orig.)

Mud peeling and horizontal crack formation in drying clays

KAUST Repository

Style, Robert W.

2011-03-01

Mud peeling is a common phenomenon whereby horizontal cracks propagate parallel to the surface of a drying clay. Differential stresses then cause the layer of clay above the crack to curl up to form a mud peel. By treating the clay as a poroelastic solid, we analyze the peeling phenomenon and show that it is caused by the gradient in tensile stress at the surface of the clay, analogously to the spalling of thermoelastic materials. For a constant water evaporation rate at the clay surface we derive equations for the depth of peeling and the time of peeling as functions of the evaporation rate. Our model predicts a simple relationship between the radius of curvature of a mud peel and the depth of peeling. The model predictions are in agreement with the available experimental data. Copyright 2011 by the American Geophysical Union.

Experimental Study on Environment Friendly Tap Hole Clay for Blast Furnace

Science.gov (United States)

Siva kumar, R.; Mohammed, Raffi; Srinivasa Rao, K.

2018-03-01

Blast furnace (BF) is the best possible route of iron production available. Blast furnace is a high pressure vessel where iron ore is melted and liquid iron is produced. The liquid iron is tapped through the hole in Blast Furnace called tap hole. The tapped liquid metal flowing through the tap hole is plugged using a clay called tap hole clay. Tap hole clay (THC) is a unshaped refractory used to plug the tap hole. The tap hole clay extruded through the tap hole using a gun. The tap hole clay is designed to expand and plug the tap hole. The tap hole filled with clay is drilled using drill bit and the hole made through the tap hole to tap the liquid metal accumulated inside the furnace. The number of plugging and drilling varies depending on the volume of the furnace. The tap hole clay need to have certain properties to avoid problems during plugging and drilling. In the present paper tap hole clay properties in industrial use was tested and studied. The problems were identified related to tap hole clay manufacturing. Experiments were conducted in lab scale to solve the identified problems. The present composition was modified with experimental results. The properties of the modified tap hole clay were found suitable and useful for blast furnace operation with lab scale experimental results.

Molecular Mechanisms of Enhanced Bacterial Growth on Hexadecane with Red Clay.

Science.gov (United States)

Jung, Jaejoon; Jang, In-Ae; Ahn, Sungeun; Shin, Bora; Kim, Jisun; Park, Chulwoo; Jee, Seung Cheol; Sung, Jung-Suk; Park, Woojun

2015-11-01

Red clay was previously used to enhance bioremediation of diesel-contaminated soil. It was speculated that the enhanced degradation of diesel was due to increased bacterial growth. In this study, we selected Acinetobacter oleivorans DR1, a soil-borne degrader of diesel and alkanes, as a model bacterium and performed transcriptional analysis using RNA sequencing to investigate the cellular response during hexadecane utilization and the mechanism by which red clay promotes hexadecane degradation. We confirmed that red clay promotes the growth of A. oleivorans DR1 on hexadecane, a major component of diesel, as a sole carbon source. Addition of red clay to hexadecane-utilizing DR1 cells highly upregulated β-oxidation, while genes related to alkane oxidation were highly expressed with and without red clay. Red clay also upregulated genes related to oxidative stress defense, such as superoxide dismutase, catalase, and glutaredoxin genes, suggesting that red clay supports the response of DR1 cells to oxidative stress generated during hexadecane utilization. Increased membrane fluidity in the presence of red clay was confirmed by fatty acid methyl ester analysis at different growth phases, suggesting that enhanced growth on hexadecane could be due to increased uptake of hexadecane coupled with upregulation of downstream metabolism and oxidative stress defense. The monitoring of the bacterial community in soil with red clay for a year revealed that red clay stabilized the community structure.

Simulation of the long term alteration of clay minerals in engineered bentonite barriers: nucleation and growth of secondary clay particles

International Nuclear Information System (INIS)

Fritz, B.; Clement, A.; Zwingmann, H.; Noguera, C.

2010-01-01

Document available in extended abstract form only. The long term stability of clay rich rocks used as barriers to the migration of radionuclides in the environment of nuclear wastes has been intensively studied, looking at the geochemical interactions between clay minerals and aqueous solutions. These studies combine experimental approaches for the short term and numerical modellings for the long term extrapolations, in the frame of the research supported by ANDRA in the French design for High Level Waste (HLW) repository. The main objective of the geochemical numerical tools devoted to clay-solutions interaction processes was to predict the feed-back effects of mineralogical and chemical transformations of clay mineral, in repository conditions as defined by Andra, on their physical and transport properties (porosity, molecular diffusion, permeability). The 1D transport-reaction coupled simulation was done using the code KIRMAT, at 100 deg. C for 100000 years. The fluid considered is that of the Callovo-Oxfordian geological formation (COX) and assumed to diffuse into the clay barrier from one side. On the other side, ferrous iron, is provided by the steel overpack corrosion. Under these conditions, montmorillonite of the clay barrier is only partially transformed into illite, chlorite, and saponite. The simulation shows that only outer parts of the clay barrier is significantly modified, mainly at the interface with the geological environment. These modifications correspond to a closure of the porosity, followed by a decrease of mass transport by molecular diffusion. Near the COX, the swelling pressure of the clays from the barrier is predicted to decrease, but in its major part, the engineered barrier seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure). In this modelling approach, the very important role of secondary clay minerals has to be taken into account with relevant kinetic rate laws; particularly

Fired products of Cr-smectite clays in nitrogen

OpenAIRE

C. Volzone; A. M. Cesio

2004-01-01

The products of Cr-smectite clays heated to 1350 ° C in nitrogen were evaluated by X-ray diffraction and chemical analysis. Cr-smectite clays were prepared at room temperature by contact between smectite clays and Cr species contained in OH-Cr solutions. The Cr species were prepared using chromium nitrate solution by addition of NaOH solution with OH/Cr = 2. Products of firing in nitrogen at the high temperature were different (magnesia chromite, donathite, iron chromium oxide and picrochromi...

Deformation and Fabric in Compacted Clay Soils

Science.gov (United States)

Wensrich, C. M.; Pineda, J.; Luzin, V.; Suwal, L.; Kisi, E. H.; Allameh-Haery, H.

2018-05-01

Hydromechanical anisotropy of clay soils in response to deformation or deposition history is related to the micromechanics of platelike clay particles and their orientations. In this article, we examine the relationship between microstructure, deformation, and moisture content in kaolin clay using a technique based on neutron scattering. This technique allows for the direct characterization of microstructure within representative samples using traditional measures such as orientation density and soil fabric tensor. From this information, evidence for a simple relationship between components of the deviatoric strain tensor and the deviatoric fabric tensor emerge. This relationship may provide a physical basis for future anisotropic constitutive models based on the micromechanics of these materials.

Discrete analysis of clay layer tensile strength

International Nuclear Information System (INIS)

Le, T.N.H.; Ple, O.; Villard, P.; Gourc, J.P.

2010-01-01

The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover and comparing to experimental large scale field bending tests achieved in a real site of storage. (authors)

Clay characterization of Monte Alegre-RN, Brazil

International Nuclear Information System (INIS)

Alencar, M.I.; Ferreira, O.F.; Ren, D.G.; Cunha, J.M.R.; Harima, E.

2011-01-01

This study aimed to characterize the clay from the municipality of Monte Alegre in Rio Grande do Norte. Clay (popularly known as tabatinga) is used in brick kilns for producing bricks and tiles. This study also verified the possibility of using this for industrial ceramics and ceramic tiles. The following techniques were used for characterization: chemical and mineralogical analysis which found the composition of this material the presence of quartz and kaolinite, plasticity index where the result was that the clay has plasticity null; solid residue content was 60, 19%, the determination of loss on ignition was 8.70% on checking the color of the burning got creamy clear. (author)

Sectioning Clay Models Makes Anatomy & Development Tangible

Science.gov (United States)

Howell, Carina Endres; Howell, James Endres

2010-01-01

Clay models have proved to be useful teaching aids for many topics in biology that depend on three-dimensional reasoning. Students studying embryonic development struggle to mentally reconstruct the three-dimensional structure of embryos and larvae by observing prepared slides of cross-sectional slices. Students who build clay models of embryos…

Influence of clay and surfactant content in non-aqueous fluid rheology

International Nuclear Information System (INIS)

Guedes, I.C.; Gomes, N.L.; Menezes, R.R.; Campos, L.F.A.; Ferreira, H.S.

2012-01-01

The bentonite clay used as viscosity agent in the production of non-aqueous fluids cannot be used without organic treatment for their surfaces to become hydrophobic. These clays are called organophilic clays, and are generally obtained by adding, in an aqueous way, ionic or a nonionic surfactant. Recent studies of the variables involved in the dispersion of bentonite clays and in the process of organophilization, showed their lack of influence. This work aims to study the influence of clay content and surfactants on the rheology of nonaqueous fluids. To this end, the clays were treats and characterized, evidencing the incorporation of the surfactant, and then formulated non-aqueous fluids, following PETROBRAS standards, being possible to verify the influence of clay content and surfactant both from the point of view as the characterizing and rheological behavior. (author)

Diazonium cation-exchanged clay: an efficient, unfrequented route for making clay/polymer nanocomposites.

Science.gov (United States)

Salmi, Zakaria; Benzarti, Karim; Chehimi, Mohamed M

2013-11-05

We describe a simple, off-the-beaten-path strategy for making clay/polymer nanocomposites through tandem diazonium salt interface chemistry and radical photopolymerization. Prior to photopolymerization, sodium montmorillonite (MMT) was ion exchanged with N,N'-dimethylbenzenediazonium cation (DMA) from the tetrafluoroborate salt precursor. DMA acts as a hydrogen donor for benzophenone in solution; this pair of co-initiators permits us to photopolymerize glycidyl methacrylate (GMA) between the lamellae of the diazonium-modified clay, therefore providing intercalated MMT-PGMA nanocomposites with an onset of exfoliation. This work conclusively provides a new approach for bridging reactive and functional polymers to layered nanomaterials via aryl diazonium salts in a simple, fast, efficient cation-exchange approach.

Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres

OpenAIRE

Frindy, Sana; Primo Arnau, Ana Maria; Qaiss, Abou el Kacem; Bouhfid, Rachid; Lahcini, Mohamed; García Gómez, Hermenegildo; Bousmina, Mosto; El Kadib, Abdelkrim

2016-01-01

[EN] Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicit...

Stabilization Of Marine Clay Using Biomass Silica-Rubber Chips Mixture

Science.gov (United States)

Marto, Aminaton; Ridzuan Jahidin, Mohammed; Aziz, Norazirah Abdul; Kasim, Fauziah; Zurairahetty Mohd. Yunus, Nor

2016-11-01

Marine clay is found widely along the coastal area and had caused expensive solutions in the construction of coastal highways. Hence, soil stabilization was suggested by some consultant to increase the strength of this soil in order to meet the highway construction requirement and also to achieve the specification for the development. Biomass Silica (BS), particularly the SH85 as a non-traditional stabilisation method, has been gaining more interest from the engineers recently. Rubber chips (RC), derived from waste rubber tyres, are considered ‘green’ element and had been used previously in some geotechnical engineering works. This paper presents the effect of using BS and RC as a mixture (BS-RC mixture), to increase the strength of marine clay for highway construction. Samples of marine clay, obtained from the West Coast Expressway project at Teluk Intan, Perak, were oven dried and grind to fine-grained sized. The marine clay was mixed with 9 % by weight proportion of BS- RC; that were 8%-l% and 7%-2%, respectively. For comparison purposes the result of BS-RC was compared to the result of stabilization by using 9% BS only. Laboratory tests were then carried out to determine the Atterberg limits and compaction characteristics of the untreated and treated marine clay. The Unconfined Compressive Strength (UCS) of the untreated and treated marine clays, compacted at the optimum moisture content was later obtained. The treated marine clay was tested at 0, 3 and 7 days curing periods. The results show that the Plasticity Index of BS-RC treated marine clay was lower than the untreated marine clay. From the UCS test results, it is shown that BS-RC mixtures had significantly improved the strength of marine clay. With the same percentage of 9% BS-RC, the increased of BS from 7% to 8% increased the UCS further to about six times more than untreated marine clay soils in 7 days curing period. The strength gained by using BS-RC at 8%-1% is slightly below the strength by

A preliminary study on titanium-clay interactions

International Nuclear Information System (INIS)

Wersin, P.; Grolimund, D.; Kumpulainen, S.; Brendle, J.; Snellman, M.

2010-01-01

Document available in extended abstract form only. Posiva and SKB are developing a horizontal disposal design alternative, termed KBS-3H. In this design alternative, modules of a Cu-waste canister surrounded by bentonite blocks is placed in a perforated steel cylinder, a so-called supercontainer (SC), before emplacement in the deposition drifts. The current design for the SC is based on carbon steel. But because corrosion will lead to high hydrogen levels and iron-clay interactions, alternative materials are also being considered. A promising alternative are Ti alloys which display high strength and are known to behave as chemically inert materials under variety of conditions. Also for the Ti alloys, both the corrosion rate and interaction behaviour with other components in the drift needs to be known. In particular, it needs to be demonstrated that corrosion-derived Ti has no significant detrimental effects on the bentonite buffer which is one main barrier within the KBS-3H concept. Unfortunately, the benign inert behaviour of Ti makes it difficult to perform meaningful experiments. Hence, it is not surprising that so far, very little research work on this topic has been carried out and experience is very limited. A preliminary batch-type investigation has been launched to shed more light on Ti-clay interaction processes and on the Ti species resulting from these interactions. A series of experiments including purified MX-80 bentonite or synthetic 'Ti-free' montmorillonite were mixed with metallic Ti nano-powder or foil in 0.1 M NaCl solutions at different pH and temperature conditions. After several months, solid and solute samples from the first set of tests were analyzed by wet chemistry and spectroscopic methods. Ti speciation was analyzed with XAS combined with XRF as elemental mapping tool. A further series of tests will be analyzed in the near future. In addition to reacted samples, a number of reference and starting materials (e.g. MX-80, Rokle

Se of polymers to control clay swelling

Energy Technology Data Exchange (ETDEWEB)

Slobod, R L; Beiswanger, J P.G.

1968-01-01

The injection of water to displace oil is one of the main methods used to increase oil recovery. High injection rates are generally desired, and in some cases the flood will not be economic unless high rates are maintained. The presence of clays which swell in the presence of water offers a complication to the problem of maintaining adequate injectivity. In the course of this study it was observed that certain polymers, when present in dilute concentrations in the water, had the ability to reduce the response of these clays to fresh water. Two polymers, one an anionic and the other nonionic, were found to be very effective in controlling the clays present in Berea cores. Successful control of clay swelling was obtained by use of solutions containing as little as 1.0 ppM of polymer, but at this low concentration appreciable volumes of treating solution were required. These results suggest that some minimum amount of polymer must be adsorbed to prevent clay swelling. In Berea sandstone this minimum amount appeared to be of the order of 0.03 mg per cc of pore space. A series of tests made using 10.0 ppM polymer showed that the polymer could be made through the porous system in which 0.066 per mg of polymer was adsorbed per cc of pore space.

The contribution of edaphic heterogeneity to the evolution and diversity of Burseraceae trees in the western Amazon.

Science.gov (United States)

Fine, Paul V A; Daly, Douglas C; Villa Muñoz, Gorky; Mesones, Italo; Cameron, Kenneth M

2005-07-01

Environmental heterogeneity in the tropics is thought to lead to specialization in plants and thereby contribute to the diversity of the tropical flora. We examine this idea with data on the habitat specificity of 35 western Amazonian species from the genera Protium, Crepidospermum, and Tetragastris in the monophyletic tribe Protieae (Burseraceae) mapped on a molecular-based phylogeny. We surveyed three edaphic habitats that occur throughout terra firme Amazonia: white-sand, clay, and terrace soils in eight forests across more than 2000 km in the western Amazon. Twenty-six of the 35 species were found to be associated with only one of three soil types, and no species was associated with all three habitats; this pattern of edaphic specialization was consistent across the entire region. Habitat association mapped onto the phylogenetic tree shows association with terrace soils to be the probable ancestral state in the group, with subsequent speciation events onto clay and white-sand soils. The repeated gain of clay association within the clade likely coincides with the emergence of large areas of clay soils in the Miocene deposited during the Andean uplift. Character optimizations revealed that soil association was not phylogenetically clustered for white-sand and clay specialists, suggesting repeated independent evolution of soil specificity is common within the Protieae. This phylogenetic analysis also showed that multiple cases of putative sister taxa with parapatric distributions differ in their edaphic associations, suggesting that edaphic heterogeneity was an important driver of speciation in the Protieae in the Amazon basin.

Synthesis, thermal properties and applications of polymer-clay nanocomposites

International Nuclear Information System (INIS)

Meneghetti, Paulo; Qutubuddin, Syed

2006-01-01

Polymer-clay nanocomposites constitute a new class of materials in which the polymer matrix is reinforced by uniformly dispersed inorganic particles (usually 10 wt.% or less) having at least one dimension in the nanometer scale. Nanocomposites exhibit improved properties when compared to pure polymer or conventional composites, such as enhanced mechanical and thermal properties, reduced gas permeability, and improved chemical stability. In this work, the synthesis of poly(methyl methacrylate) (PMMA)/clay nanocomposites is described via two methods: in situ and emulsion polymerization. The in situ technique follows a two-step process: ion-exchange of the clay to make it hydrophobic, and polymerization after dispersing the functionalized clay in the monomer. The emulsion technique combines the two steps of the in situ method into one by conducting ion-exchange and polymerization in an aqueous medium in the same reactor. The clay (montmorillonite, MMT) is functionalized with a zwitterionic surfactant, octadecyl-dimethyl betaine (C18DMB). Partially exfoliated nanocomposite, observed by transmission electron microscopy (TEM), was obtained by emulsion polymerization with 10 wt.% clay. Glass transition temperature (T g ) of this nanocomposite was 18 deg. C higher than pure PMMA. With the same clay content, in situ polymerization produced intercalated nanocomposite with T g 10 deg. C lower than the emulsion nanocomposite. The storage modulus of partially exfoliated nanocomposite was superior to the intercalated structure and to the pure polymer. Using nanocomposite technology, novel PMMA nanocomposite gel electrolytes were synthesized exhibiting improved ionic conductivity and stable lithium interfacial resistance. Nanocomposites can also be used for gas storage and packaging applications as demonstrated by high barrier polymer-clay films

Synthesis, thermal properties and applications of polymer-clay nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Meneghetti, Paulo [Chemical Engineering Department, Case Western Reserve University, 10900 Euclid Ave. Cleveland, OH 44106 (United States); Qutubuddin, Syed [Chemical Engineering Department, Case Western Reserve University, 10900 Euclid Ave. Cleveland, OH 44106 (United States)]. E-mail: sxq@case.edu

2006-03-15

Polymer-clay nanocomposites constitute a new class of materials in which the polymer matrix is reinforced by uniformly dispersed inorganic particles (usually 10 wt.% or less) having at least one dimension in the nanometer scale. Nanocomposites exhibit improved properties when compared to pure polymer or conventional composites, such as enhanced mechanical and thermal properties, reduced gas permeability, and improved chemical stability. In this work, the synthesis of poly(methyl methacrylate) (PMMA)/clay nanocomposites is described via two methods: in situ and emulsion polymerization. The in situ technique follows a two-step process: ion-exchange of the clay to make it hydrophobic, and polymerization after dispersing the functionalized clay in the monomer. The emulsion technique combines the two steps of the in situ method into one by conducting ion-exchange and polymerization in an aqueous medium in the same reactor. The clay (montmorillonite, MMT) is functionalized with a zwitterionic surfactant, octadecyl-dimethyl betaine (C18DMB). Partially exfoliated nanocomposite, observed by transmission electron microscopy (TEM), was obtained by emulsion polymerization with 10 wt.% clay. Glass transition temperature (T {sub g}) of this nanocomposite was 18 deg. C higher than pure PMMA. With the same clay content, in situ polymerization produced intercalated nanocomposite with T {sub g} 10 deg. C lower than the emulsion nanocomposite. The storage modulus of partially exfoliated nanocomposite was superior to the intercalated structure and to the pure polymer. Using nanocomposite technology, novel PMMA nanocomposite gel electrolytes were synthesized exhibiting improved ionic conductivity and stable lithium interfacial resistance. Nanocomposites can also be used for gas storage and packaging applications as demonstrated by high barrier polymer-clay films.

Nanocomposites of PP and bentonite clay modified with different surfactants

International Nuclear Information System (INIS)

Rodrigues, Andre W.B.; Agrawal, Pankaj; Araujo, Edcleide M.; Melo, Tomas J.A.; Ueki, Marcelo M.

2009-01-01

The aim of this work was the development of nano composites of polypropylene (PP) and national bentonite clay modified with different surfactants. The results of X-Ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) showed that the organophilization process was effective. The surfactants led to a significant increase in the basal spacing of Brasgel PA clay. XRD results of the mixture PP/Brasgel PA clay modified with Praepagem WB surfactant indicated that a nanocomposite with intercalated structure was formed. When the Brasgel PA clay was modified with Praepagem HY surfactant, DRX results indicated that a micro composite was formed. Screw speed, clay content and PP viscosity had no influence on the XRD pattern of the obtained materials. (author)

Rheological properties of purified illite clays in glycerol/water suspensions

Science.gov (United States)

Dusenkova, I.; Malers, J.; Berzina-Cimdina, L.

2015-04-01

There are many studies about rheological properties of clay-water suspensions, but no published investigations about clay-glycerol suspensions. In this work apparent viscosity of previously purified illite containing clay fraction clay minerals were almost totally removed by centrifugation. All obtained suspensions behaved as shear-thinning fluids with multiple times higher viscosity than pure glycerol/water solutions. Reduction of clay fraction concentration by 5% decreased the apparent viscosity of 50% glycerol/water suspensions approximately 5 times. There was basically no difference in apparent viscosity between all four 50% glycerol/water suspensions, but in 90% glycerol/water suspensions samples from Iecava deposit showed slightly higher apparent viscosity, which could be affected by the particle size distribution.

Probabilistic Description of a Clay Site using CPTU tests

DEFF Research Database (Denmark)

Andersen, Sarah; Lauridsen, Kristoffer; Nielsen, Benjaminn Nordahl

2012-01-01

A clay site at the harbour of Aarhus, where numerous cone penetration tests have been conducted, is assessed. The upper part of the soil deposit is disregarded, and only the clay sections are investigated. The thickness of the clay deposit varies from 5 to 6 meters, and is sliced into sections of...... a geotechnical assessment of a site, using both the method for classifying soil behaviour types and applying statistics, yield a new level of information, and certainty about the estimates of the strength parameters which are the important outcome of such a site description.......A clay site at the harbour of Aarhus, where numerous cone penetration tests have been conducted, is assessed. The upper part of the soil deposit is disregarded, and only the clay sections are investigated. The thickness of the clay deposit varies from 5 to 6 meters, and is sliced into sections of 1...... meter in thickness. For each slice, a map of the variation of the undrained shear strength is created through Kriging and the probability of finding weak zones in the deposit is calculated. This results in a description of the spatial variation of the undrained shear strength at the site. Making...

Quantifying the ability of environmental parameters to predict soil texture fractions using regression-tree model with GIS and LIDAR data

DEFF Research Database (Denmark)

Greve, Mogens Humlekrog; Bou Kheir, Rania; Greve, Mette Balslev

2012-01-01

Soil texture is an important soil characteristic that drives crop production and field management, and is the basis for environmental monitoring (including soil quality and sustainability, hydrological and ecological processes, and climate change simulations). The combination of coarse sand, fine...... sand, silt, and clay in soil determines its textural classification. This study used Geographic Information Systems (GIS) and regression-tree modeling to precisely quantify the relationships between the soil texture fractions and different environmental parameters on a national scale, and to detect...... precipitation, seasonal precipitation to statistically explain soil texture fractions field/laboratory measurements (45,224 sampling sites) in the area of interest (Denmark). The developed strongest relationships were associated with clay and silt, variance being equal to 60%, followed by coarse sand (54...