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With the increased use of autoclaved aerated concrete (AAC) in the construction sector, the generation of AAC scrap is increasing in plant manufacturing and construction demolition works, but its reuse and recycling is limited compared to other typical construction wastes such as concrete and asphalt. To examine the use of AAC scrap for roadbed materials, this study investigated mechanical properties such as compaction curves and bearing capacity [i.e., California bearing ratio (CBR)] as well as the particle breakage, and hydraulic properties of well– and poorly–graded recycled concrete aggregates (RCA) blended with AAC grains made from AAC grains in different proportions (f) on a mass basis.The results showed that the compaction curves were mainly affected by particle size distribution and f. The f ≤ 30% is recommended for use as unbound roadbed materials based on the CBR results. The breakage of RCA itself was reduced due to the cushioning effect with increasing of f and the easily breakable property of AAC grains controlled the mechanical and hydraulic properties. The sudden increase of overall particle breakage for the tested samples with f > 30% and in the unique hydraulic properties for the tested samples mixed with different sizes of AAC grains. [ABSTRACT FROM AUTHOR]

The main aim of this study is to investigate the material and monetary flows of CDW management and to characterize the distribution of illegally dumped CDW in Hanoi. Construction and demolition waste management has become a source of much concern to the urban authorities and citizens of big cities in Vietnam. It is estimated that 3000 t of CDW were generated per day from construction and demolition activities in Hanoi, but only 45% of the CDW was received at official landfills, while 55% of the CDW was disposed of elsewhere. The consequences of improper waste management are potentially alarming. The study conducted interviews to identify the material and cash flow associated with licensed and unlicensed contractors in CDW classification, transportation, treatment, and disposal, to characterize the distribution of illegally dumped CDW in two districts in Hanoi (urban and suburban districts), and to assess the composition of dumped CDW and environmental assessment of illegally dumped CDW by chemical analyses such as leaching and content tests. The study concluded that illegal dumping was performed mostly by unlicensed private companies. The illegally dumped CDW was mostly composed of mixed materials such as concrete, bricks, stones, and some hazardous materials such as asbestos and gypsum were found. The environmental concern of illegally dumped CDW was mostly dust, blockage of water ways, and inundation of increased suspended solids, whereas the heavy metal leaching concentration of all samples was below the environmental standards in Vietnam. [ABSTRACT FROM AUTHOR]

The discharge of untreated oily wastewater into the environment has serious impacts on human health, living nature, and ecosystems and leads to significant economic losses. Many engineering techniques have been proposed and applied to treat oily wastewater, but limited studies have investigated low-cost and effective techniques using by-products and waste/scrap materials from the construction industry. Materials to treat oily wastewater are needed not only to mitigate environmental pollution but also to promote the reuse and recycling of industrial by-products, especially in developing countries. This study, therefore, examined the sorption capacity of dispersed oil in wastewater (dispersed soybean oil in water; initial oil concentrations, Ci = 10–1000 mg/L; oil droplet size in water <2 μm) onto the hydrophobized/oleophilized autoclaved porous aerated concrete (AAC) grains made from waste scrap in Vietnam by using batch sorption tests in the laboratory. The AAC grains (sizes 0.106–0.25, 0.25–0.85, and 0.85–2.00 mm) were hydrophobized/oleophilized using oleic and stearic acids (coating concentrations of 1.0, 5.0, and 10 g/kg), and two sands (0.18–2.00 and 0.30–2.00 mm) were used as control samples. The results showed that the hydrophobized/oleophilized AAC grains had high sorption capacity for dispersed oil (i.e., high oil removal efficiency) compared to the control sands. Especially, the removal of AAC grains coated with stearic acid was >80% in high oil concentration solutions (Ci = 100 and 1000 mg/L), indicating that the hydrophobized/oleophilized AAC grains have high potential as useful adsorbents to trap dispersed oil in oily wastewater. Moreover, adsorption isotherms were drawn to examine the sorption characteristics of dispersed oil onto AAC grains. For all tested samples, the sorption of dispersed oil increased linearly with increasing equilibrium concentration. The commonly used Langmuir model, on the other hand, did not capture the measured isotherms. [ABSTRACT FROM AUTHOR]

Treatment of oily wastewater has been still a challenge to environmental scientists. In this study, waste autoclaved aerated concrete (AAC) grains from a concrete manufacturing plant were collected and modified with stearic acid to evaluate the possibility of using them as low-cost filtration media for the removal of oil from water. The modification factors such as percentage of surface modifying agent — stearic acid (0.4%, 0.6%, 0.8%, 1%, 2% by weight), mixing durations (3 h, 6 h, and 9 h), and different grain sizes (0.1–0.2 mm; 0.63–1.25 mm; and 1.25–2.5 mm) were all evaluated in this study. The results showed that waste AAC with a grain size of 0.1–0.2 mm modified with 2% stearic acid in 9 h had only 24% (by weight) wetted during the wetting test. The filtration column test with oily wastewater using modified AAC and original AAC grains proved the oil removal performance depends on filtration flow modes (downflow, upflow, or up–downflow), types of filtration media (single or dual filtration layers), and initial oil concentrations. The COD removal and total oil removal efficiencies were 55–82% and 75–90%, respectively, depending on the testing conditions. [ABSTRACT FROM AUTHOR]

Separation of oil and water is an effective technique to treat oily wastewater. For examining the applicability of porous grains coated with hydrophobic agents (HA) as low-cost and easily available filtration and adsorbent materials in the separation of oil and water, this study assessed the hydrophobicity/oleophilicity of porous grains made from autoclaved aerated concrete scrap coated with low-cost and harmless hydrophobic agents such as oleic and stearic acids. Tests using a sessile droplet method showed unique relationships between the contact angles (CA) of water droplets in air (CAwa), oil droplets in water (CAow) and coated HA concentrations. The CAwa increased linearly with increasing HA concentration and then became almost constant and/or gently increased after a specific point, indicating that a minimum coating amount gives the maximum hydrophobicity to HA-coated porous grains exists. The CAow gradually decreased exponentially with increasing HA concentration. In particular, the CAow of porous grains coated with stearic acid decreased with increasing of HA concentration in a two-step process. Furthermore, analyses of the Pearson correlation showed that both CAwa and CAow correlated well with the specific surface area (SSA), implying that the SSA is a good indicator as a quick assessment of hydrophobicity/oleophilicity of HA-coated porous grains. [ABSTRACT FROM AUTHOR]

Along with economic development, urbanization will generate a large amount of solid waste and put pressure on the waste management systems in developing countries. Face-to-face interview methods were used to investigate the current status of construction and demolition waste (CDW) management (collection, transportation, treatment, and storage) as well as reveal attitudes of governmental agencies and enterprises towards CDW recycling and recycled material products in Hai Phong City, Vietnam. Waste generation rates (WGRs) of the works were also determined by site surveys and as-built drawings method of typical old buildings to be demolished and two licensed new construction works. WGRs of 34.5 kg/m2 and 758 kg/m2 were identified during the construction and demolition of small private houses, respectively, while WGRs at public house demolition sites were 1053 kg/m2. To effectively manage the CDW, the gross floor area of new construction work was estimated by a multiple regression equation with the population and gross region domestic product growth. Based on this model combining the investigation results, the amount of CDW increase in 5–30 years is also predicted. This data set will help management agencies plan storage yards as well as select the appropriate CDW treatment and recycling methods, contributing to building a sustainable and effective CDW management model for Hai Phong City as well as Vietnam in the future. [ABSTRACT FROM AUTHOR]

Heavy metal contamination of water sources is an alarming issue across the globe. It may cause several health problems in humans in addition to its damage to aquatic organisms and its adverse effects on the environment. Among the wastewater treatment techniques of heavy metals, adsorption is much favored due to its cost-effectiveness and easy availability, especially in developing countries in tropical and semi-tropical climate regions. Moreover, natural geo-adsorbents like laterite and its crushed grains can be adopted as an attractive alternative adsorbent in floatation and filtration water treatment systems. In this review, the application of natural and pre-treated laterite grains as a low-cost adsorbent was examined based on selected journal articles published during 1990–2020. This paper summarizes basic physical and chemical properties including surface charge and element compositions of tested samples, batch adsorption results including initial conditions, isotherm and kinetic models, and adsorption and thermodynamic parameters such as the maximum adsorption capacity, removal percentage, and Gibbs free energy that categorize the natural and pre-treated laterite grains. In addition, the results of some previous studies of column experiments and desorption/regeneration of adsorbed heavy metals are described together with prospects for future studies and the applicability of laterite in wastewater treatment for heavy metal remediation. [ABSTRACT FROM AUTHOR]

Natural granular materials widely used in building and infrastructure development consume a considerable number of natural resources. To avoid depleting natural granular materials, recycled concrete aggregates (RCA) from construction and demolition waste are now commonly used as an alternative. The mechanical behavior of RCA used in road construction is highly influenced by field conditions such as traffic load and moisture variation. The particle breakage of RCA influences long-term pavement performance because it changes the RCA grading over time. However, the effect of moisture content (m.c.) on mechanical behavior and particle breakage during compaction and cyclic loading is often neglected. The aims of the study were to investigate the mechanism of permanent deformation development due to moisture change, the breakage response of RCA in this process, and the assessment of existing permanent deformation prediction model. The results showed that initial m.c. effectively controlled the deformation of RCA; the permanent axial strain (εpa) was enhanced, and the breakage of coarse fraction (19~9.5 mm) under cyclic loading was reduced at higher levels of m.c. Based on the experimental results, a modified model for predicting εpa was proposed, incorporating a deviation factor induced by m.c. The model fitted the experimental data well, suggesting that it is useful to have a quantitative estimation of εpa of RCA with different m.c. under cyclic loading. [ABSTRACT FROM AUTHOR]

The construction industry is one of the key industries with high potential for the circular economy; the promotion of reuse and recycling of construction and demolition waste (CDW) is essential for sustainable urban development. In this study, a series of compaction, California bearing ratio, saturated hydraulic conductivity, and particle breakage tests of well– and poor–graded mixtures of recycled clay brick aggregates (RCBs) and recycled concrete aggregates (RCAs) with maximum aggregate diameters of 19, 25, and 37.5 mm were carried out to examine the practical application of those mixtures to unbound roadbed materials in Vietnam. The experimental results suggest that the maximum amount of RCBs added to RCAs should be less than 30% when applied to unbound roadbed materials. In addition, it was found that the mixing proportions of RCBs and RCAs and the maximum aggregate diameter, gradation of aggregates, and initial moisture condition control the saturated hydraulic conductivity. Further, the particle breakage characteristics under compaction were carefully examined, and it was found that the percentage increment/decrement, as well as a newly introduced method of estimating the mixing proportions of RCAs and RCBs in the fine fraction (<2.36 mm), is effective in understanding the mechanism of particle breakage of RCA and RCB mixtures. [ABSTRACT FROM AUTHOR]

Due to the rapid increase in population and urbanization, municipal solid waste (MSW) generation is increasing. Sri Lanka, in particular, faces serious difficulties in finding new sites for MSW disposal, due to the lack of available space; therefore, the rehabilitation of existing MSW dumping sites and the extension of their services are required to achieve sustainable urban development. To examine suitable rehabilitation techniques, it is essential to identify the physicochemical and mechanical properties of dumped MSW, fully considering climatic conditions, waste composition, and the time since the waste was dumped. In this study, therefore, the physicochemical and mechanical properties of dumped MSW were investigated; the dumped MSW was taken from existing MSW dumping sites in three climate zones in Sri Lanka, namely the Karadiyana site in the wet zone, Udapalatha in the intermediate zone, and Hambantota in the dry zone, and it was taken at different times after being dumped. The results showed that the waste composition and biodegradation of organic materials affected the physicochemical and mechanical properties of the dumped waste. The measured compaction parameters of the "old" sites at Udapalatha and Hambantota were higher compared to the "new" sites. Compaction parameters at the Karadiyana site, on the other hand, were low, at even >20 years since being dumped, probably due to the high amount of scarcely compacted materials. In direct shear tests, both strain hardening and softening of the waste samples were observed, depending on the difference in vertical stress. Based on the Pearson correlations among measured physicochemical and mechanical parameters, it was found that the loss on ignition (LOI) would be a good indicator to quickly assess the mechanical parameters of "new" and "old" waste materials, due to the small sensitivities to waste age and climate conditions in Sri Lanka. In particular, LOI correlated well to measured specific gravity and compaction properties, and the r2 values of correlations exceeded |0.80|. [ABSTRACT FROM AUTHOR]

Mechanical properties of recycled concrete aggregates (RCA) such as compaction and California bearing ratio (CBR) are important for application as unbound road base and subbase materials. Limited studies, however, have examined the effects of the nominal maximum particle diameter (Dmax) of aggregates and fines content (Fc; < 0.075 mm). Also, particle rearrangement and breakage depend on water content (w) (i.e., water states of aggregates) under the compaction process. In this study, therefore, a series of compaction and CBR tests at different compaction energies (Ec) and w was carried in the laboratory using graded RCA with Dmax of 25 mm and 37.5 mm and four different Fc ranging from 0 to 20%. The results showed that the compaction properties of RCA were controlled by Ec and w. Based on the analysis of water states of aggregates, it can be understood that water existed in the capillary region for maximum dry density and existed at the boundary between capillary and hygroscopic regions for minimum dry density. The maximum measured CBR values were attained at Fc = 5% for both Dmax of 25 mm and 37.5 mm. The breakage of samples became enhanced with increasing Ec and weakened with increasing Fc. [ABSTRACT FROM AUTHOR]

The fovea is a depression in the center of the macula and is the site of the highest visual acuity. Optical coherence tomography (OCT) has contributed considerably in elucidating the pathologic changes in the fovea and is now being considered as an accompanying imaging method in drug development, such as antivascular endothelial growth factor and its safety profiling. Because animal numbers are limited in preclinical studies and automatized image evaluation tools have not yet been routinely employed, essential reference data describing the morphologic variations in macular thickness in laboratory cynomolgus monkeys are sparse to nonexistent. A hybrid machine learning algorithm was applied for automated OCT image processing and measurements of central retina thickness and surface area values. Morphological variations and the effects of sex and geographical origin were determined. Based on our findings, the fovea parameters are specific to the geographic origin. Despite morphological similarities among cynomolgus monkeys, considerable variations in the foveolar contour, even within the same species but from different geographic origins, were found. The results of the reference database show that not only the entire retinal thickness, but also the macular subfields, should be considered when designing preclinical studies and in the interpretation of foveal data. [ABSTRACT FROM AUTHOR]

Reuse and recycling of non-hazardous construction and demolition waste and industrial byproducts in the construction industry is vital to promote environmentally sound waste management. In particular, the effective utilization of sludge and waste clay bricks is greatly required in developing countries. This paper studied compaction characteristics and the California bearing ratio (CBR) of water treatment sludge (WTS) blended with clay brick aggregates for the road subgrade application. Raw and waste clay bricks from Vietnam were used for preparing clay brick (CB) and recycled clay brick (RCB) aggregates of three different particle sizes, Coarse 10- 30 mm, Graded 2-30 mm, and Fine 2-10 mm. In addition, fine residues of clay bricks with a size of < 2 mm were tested. WTS sieved under 2.0 mm blended with CB/RCB aggregates with different mixing proportions (f) were used for compaction and CBR tests in the laboratory. Results showed that the measured maximum dry densities (MDD) were dependent solely on mixing proportion f and increased linearly with f irrespective of blended fractions of CB/RCB aggregates. Unlike MDD, the measured CBR was dependent on both f and blended fractions. Especially, the WTS blended with coarse and graded fractions with a range of 60 ≤ f ≤ 80% showed a significant improvement in CBR (>100%). Due to its limited particle breakage and high CBR, the WTS blended with graded CB/RCB aggregates was preferable for the road subgrade application. [ABSTRACT FROM AUTHOR]

This study conducted a review of a wide array of documents related to construction and demolition waste (CDW) management in Southeast Asia (SEA). CDW definitions, current state of CDW generation and composition, CDW flow and institutional arrangements for CDW management were assessed. CDW generation was estimated in SEA countries where data are unavailable. The review results indicated the inadequacy of existing CDW management in almost all SEA nations, with a dearth of proper data on the amount of CDW generated and proportions of CDW components. Insufficient legal documents designed for CDW and unclear assignment of prime responsibilities for CDW management have also been observed. The SEA's high ratio of CDW generation to the construction industry's value added implies a great waste burden that construction activities there are causing compared to their contribution to the regional economy. This study suggested a need for more holistic and aggressive methods of sustainable CDW management, namely: developing legalised systematic approaches to CDW data collection and database establishment; enabling public private partnership models, which involve the private sector in establishing recycling facilities and internalise informal actors in formal CDW management arrangement; applying recycling-favourable policies such as green public procurement, along with disposal fee schemes. [ABSTRACT FROM AUTHOR]

Landfill sites are significant sources of greenhouse gases, particularly methane. It is believed that methane gas eruptions occur under a surface ponding condition during rainfall events. In this study, based on laboratory column experiments in which mixed gas was applied to variably compacted soil columns (10 cm in diameter and 30.5 cm in height) under different rainfall intensities, the effects of the bulk density of the landfill cover soil, the gas injection rates, and the rainfall intensities on the gas eruption phenomenon were investigated. The gas pressure and the water content were monitored during rainfall events. The main results were that (1) an episodic gas compression and eruption cycle was observed under a surface ponding condition, (2) gas eruptions occurred at a higher gas pressure in the soil with a higher dry bulk density, and (3) a higher gas injection rate resulted in continuous gas eruptions. The monitoring of the gas eruption flux and gas concentration in the soil columns, using oxygen-mixed gas as an injected gas, showed that longer gas compression led to higher gas fluxes during the gas eruptions. The concentration of gas in the soil increased over time because of the upward gas flow in accordance with the eruptions. The calculation of the oxygen mass balance indicated that the eruptions had slightly promoted the emission of gas from that which had been stored in the soil prior to the rainfall events. [ABSTRACT FROM AUTHOR]

Introduction: Aortic mural thrombosis associated with a malignant disease is rare, and whether anticoagulation therapy or surgical treatment is the more definitive primary treatment remains uncertain. This study aims to determine the best treatment strategy for aortic thrombosis in a patient with a malignant disease. Methods: We reviewed medical literature using the PubMed database and present a case of aortic thrombosis due to a hypercoagulable state related to sigmoid colon adenocarcinoma. Results: Of the 18 patients from 14 articles included in this study, 13 received simple anticoagulation as a primary treatment (anticoagulation group), while 5 underwent surgical treatment (surgical treatment group). Recurrence or exacerbation of embolism was found in 2 (15.4%) of the 13 patients and in 1 (20.0%) of the 5 patients (P = 1.0). Major complications were observed in 1 (7.7%) of the patients in the anticoagulation group and in 1 (20.0%) of the 5 patients in the surgical treatment group (P = .49). No significant differences between the groups were found. Conclusions: A simple anticoagulation therapy may be as effective as surgical treatment in patients with aortic thrombosis associated with malignancy. [ABSTRACT FROM AUTHOR]

Introduction: Aortic mural thrombosis associated with a malignant disease is rare, and whether anticoagulation therapy or surgical treatment is the more definitive primary treatment remains uncertain. This study aims to determine the best treatment strategy for aortic thrombosis in a patient with a malignant disease. Methods: We reviewed medical literature using the PubMed database and present a case of aortic thrombosis due to a hypercoagulable state related to sigmoid colon adenocarcinoma. Results: Of the 18 patients from 14 articles included in this study, 13 received simple anticoagulation as a primary treatment (anticoagulation group), while 5 underwent surgical treatment (surgical treatment group). Recurrence or exacerbation of embolism was found in 2 (15.4%) of the 13 patients and in 1 (20.0%) of the 5 patients (P = 1.0). Major complications were observed in 1 (7.7%) of the patients in the anticoagulation group and in 1 (20.0%) of the 5 patients in the surgical treatment group (P = .49). No significant differences between the groups were found. Conclusions: A simple anticoagulation therapy may be as effective as surgical treatment in patients with aortic thrombosis associated with malignancy. [ABSTRACT FROM AUTHOR]

Landfill sites are significant sources of methane gas globally. Understanding the temporal variabilities of methane emissions from landfill sites is necessary for estimating such emissions. In this study, an automated monitoring system was used to monitor methane emission flux and concentration on daily and hourly time scales at a landfill site. Measured methane emission fluxes were almost negligible in the studied area. However, methane concentration at landfill surface at nighttime was significantly higher than those in the daytime, which demonstrates the importance of investigating methane emissions at an hourly time scale, including during nighttime. The daily and hourly variations in methane concentration were well correlated with either soil temperature or volumetric water content near the surface. The obtained relations indicate that the automated monitoring system measurements can facilitate a more comprehensive understanding of the methane emission mechanisms at different time scales. [ABSTRACT FROM AUTHOR]

Removal of heavy metals from wastewater is of special concern due to the persistence of heavy metals in the environment. The industrial discharge of heavy metals adversely affects soil and water resources, aquatic organisms, and ecosystem integrity. In addition, high concentrations of heavy metals are detected in solid waste landfill leachate in many developing countries due to non-segregated waste dumping. At present, various kinds of adsorbents such as activated carbon, biomass resources, geomaterials, and industrial waste products are used to treat heavy metal-contaminated water. However, the use of construction and demolition waste (CDW) and its recycled materials to treat heavy metal-contaminated water has not been fully examined. Because the generation of CDW is increasing due to rapid urbanization and a high demand for construction, the wise use of CDW and its recycled materials is necessary. This paper reviews journal articles published from 2004 to 2016 that studied the applicability of low-cost CDW adsorbents to remove heavy metals from wastewater. In particular, it summarizes results on using CDW and recycled materials such as cement, concrete, and brick compared to those from various other adsorbents such as biosorbents, geomaterials, and their industrial products. The potential applicability of CDW and its recycled materials as heavy-metal adsorbents was examined based on a comparison table listing material properties, test conditions, and measured adsorption properties. [ABSTRACT FROM AUTHOR]

This study aimed to develop a low-cost and effective clay liner material for solid waste landfills in Sri Lanka. A locally available clayey soil and its admixtures with 5 and 10% bentonite were examined for this purpose. Laboratory experiments to determine soil plasticity and swell index were carried out on the tested samples. Hydraulic conductivity ( k) tests were carried out in the laboratory using water and an aqueous solution of CaCl on unconsolidated samples prepared by either dry or slurry packing and pre-consolidated samples with five different consolidation pressures ( p) from 10 to 200 kPa. Measured liquid limits for tested admixtures increased with increasing bentonite contents and correlated well with measured values of the swell index. The difference in permeant solutions had little effect on measured k values for both unconsolidated and pre-consolidated samples. The hydraulic conductivities were highly affected by changing p, i.e., the k values decreased on two orders of magnitude as p increased from 10 to 200 kPa. The Kozeny-Carman equation, a theoretical permeability model that expresses the k-porosity relationship, was applied to measured data including reported values. Results showed the Kozeny-Carman equation captured well the porosity-dependent k values for tested soils and their admixtures with bentonite under a wide range of void ratios, suggesting that the Kozeny-Carman equation is a useful tool to estimate the magnitude of k values for differently compacted soil and its bentonite admixtures. [ABSTRACT FROM AUTHOR]

A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Gas samples were taken from vertical gas monitoring pipes installed along transects at two sections (called new and old) of an abandoned waste dump site in Sri Lanka. N2O concentrations varied especially widely, by more than three orders of magnitude (0.046–140 ppmv). The nitrogen/argon ratio of landfill gas was normally higher than that of fresh air, implying that denitrification occurred in the dump site. Argon assays indicate that both N2and N2O production occurred inside waste and more significantly in the old section. The Ar assay would help for evaluations of N2O emission in developing countries. Implications: A long-term monitoring of composition of landfill gases in the region with high rainfall was conducted using an argon assay in order to discuss air intrusion into the dump site. Argon assays indicate that both N2and N2O production occurred inside waste and more significantly in the old section. [ABSTRACT FROM AUTHOR]

Granulated bentonite mixtures (GBMs) have been regarded as effective buffer materials in the deep geological disposal of radioactive waste due to their operational advantages, such as ease of transportation and in-situ placement/backfilling. Many studies have been done to characterize the hydraulic and thermal properties of GBMs as well as their swelling properties. Only limited studies, however, have investigated their gas transport properties, even though these properties affect their compactness during in-situ placement/backfilling and subsequent gas diffusion and advection in the buffer zone. The aim of this study is to understand the gas transport parameters, i.e., air permeability (k a) and gas diffusivity (D p /D o), of tested samples compacted at different dry densities (DDs) under air-dried conditions, linking them with the measured density distribution characteristics determined by microfocus X-ray computed tomography (MFXCT) analysis. Two types of GBMs were used in this study: 1) FE-GBM (prepared from National Standard® bentonite, Wyoming, USA): this material was used in the Full-scale Emplacement (FE) experiment at the Mont Terri rock laboratory, Switzerland) and 2) OK-GBM (prepared from a bentonite, originating from Japan, with the trade name of OK bentonite, Kunimine Industries). The tested samples were firstly packed in a 100-cm3 acrylic core with different DDs, ranging from loose to dense (1.09 to 1.75 g/cm3), and scanned by MFXCT. The weighting factors, w f (fine fraction; lower density) and w c (coarse fraction; higher density) (w f + w c = 1), were determined after the peak separation of the measured CT brightness histograms from the reconstructed three-dimensional multiplanar reconstruction (MPR) images of the MFXCT analysis. The measured k a and D p /D o were highly dependent on the DDs, the k a (ɛ) values fitted well with a power law model, and the D p /D o (ɛ) was predicted accurately by several previously proposed models. For both FE-GBM and OK-GBM, there were good linear relationships between the gas transport parameters and w c × DD, implying that the weight of the coarse fraction controlled k a and D p /D o. Moreover, the Kozeny-Carman model, incorporating the measured volumetric surfaces from the MFXCT analysis, was able to predict the k a values well. [ABSTRACT FROM AUTHOR]

Mass transport in soils occurs through pore networks that are highly affected by basic physical properties such as the degree of compaction, and particle size and shape. In this study, micro-focus X-ray computed tomography (CT) was used to obtain information on the pore network structure at different compaction levels for repacked columns of sands and glass beads representing different size fractions and particle shapes. Mass transport parameters, including gas diffusion coefficient ( D p ) and air permeability ( k a ) at variably saturated conditions, were measured on the same columns using standard methods, and literature data on saturated hydraulic conductivity ( K sat ) for the same materials were analyzed. A comparison of X-ray CT derived pore network structure and physical parameters showed that the round sands and glass beads exhibited larger pores, a higher pore coordination number, and a lower volumetric surface area than that of angular sands at the same particle size, resulting in higher K sat as well as higher D p and k a under relatively dry conditions. The X-ray CT derived the mean pore diameter ( d ), and the pore coordination number ( C n ) for each material correlated well with key gas transport properties such as percolation thresholds and pore network connectivity. A predictive D p model from wet to dry conditions based fully on X-ray CT derived parameters ( d and C n ) was developed and showed good agreement with measured D p for both round and angular sands. [ABSTRACT FROM AUTHOR]

Effects of soil temperature on the solute diffusion process in soils are important since subsurface temperature variation affects solute transport such as a fertilizer movement, leaching of salt, and pollutant movement to groundwater aquifers. However, the temperature dependency on the solute diffusion process in soils has been poorly understood and rarely documented. In this study, solute diffusion experiments as well as equilibrium adsorption experiments using pure kaolin clay were conducted under different temperature conditions. The experiments of K adsorption on kaolin clay showed more enhanced adsorption of K at elevated temperature likely because surface charge characteristics were affected at different temperature conditions for the kaolin clay. The temperature dependent solute diffusion showed that the solute diffusion coefficient at 40 °C was around two times higher than that at 6 °C for Cl and K. Overall, Arrhenius equation describing temperature dependent solute diffusion was applicable for both ions in samples at different bulk densities. At 40 °C, the liquid-phase impedance factor decreased, while liquid-phase pore-network tortuosity increased, suggesting changes in chemical surface activity towards the solute or pore structure changes of the clay fabric at the elevated temperature. [ABSTRACT FROM AUTHOR]

Capillary barrier cover systems (CBCSs) are useful and low-cost earthen cover systems for preventing water infiltration and controlling seepage at solid waste landfills. A possible technique to enhance the impermeable properties of CBCSs is to make water repellent grains by mixing the earthen cover material with a hydrophobic agent (HA). In this study, six different grains with different geometries and sizes were used to prepare dry hydrophobized grains by mixing with different contents of oleic acid as a HA. Wet hydrophobized grains were prepared by adjusting the water content ( θ; kg kg) of dry hydrophobized grains. To characterize the water repellency (WR) of dry and wet hydrophobized grains, initial solid-water contact angles ( α) were measured using the sessile drop method (SDM). Based on SDM results from the α-HA content and α- θ curves, useful WR indices were introduced as 'Area_' and 'Area_' (areas under the α-HA content and α- θ curves, respectively), 'HA_' and 'θ' (maximum HA content and θ at which WR disappears, respectively), and 'α' and 'HA_' (peak α in the α-HA content curve and corresponding HA content to α, respectively). Pearson correlation analysis was performed to identify correlations between proposed WR indices and basic grain properties. Results showed that WR indices correlated well to d and coefficient of uniformity ( C) and regression equations for WR indices were obtained as functions of d and C ( r > 0.7). [ABSTRACT FROM AUTHOR]

This study focuses on the characterization of leachate generated from Gohagoda dumpsite in Kandy, Sri Lanka, assessment of its spatial and temporal variations, and identification of subsurface canals and perched water bodies in the wetland system affected by the leachate flow. Leachate samples were collected monthly throughout dry and rainy seasons from different points of the leachate drainage channel over a period of 1 year and they were tested for quality parameters: pH, temperature, electrical conductivity, total dissolved soils, alkalinity, hardness, total solids, volatile solids, total suspended solids, volatile suspended solids, biochemical oxygen demand (BOD), chemical oxygen demand, nitrate-nitrogen, nitrite-nitrogen, phosphates, ammonium-nitrogen, chloride, dissolved organic carbon, total organic carbon and heavy metals. Sequential soil extraction procedures were performed for the characterization of leachate-affected local soil. A geophysical survey using direct current resistivity technique was conducted at locations downstream of the dumpsite. Leachate characteristics indicated that the leachate is in the methanogenic phase and the results strongly suggest that the leachate may be polluting the river where the leachate is discharged directly. Leachate exceeds the allowable limits of Sri Lankan wastewater discharge standards for many of the parameters. Significant difference ( P < 0.05) was observed for most of organic and inorganic parameters among all sampling locations. Many parameters showed a negative correlation with pH. The affected soils showed high heavy metal concentrations. Resistivity study confirmed a confined leachate flow at the near surface with few subsurface canals. However, no separate subsurface plume movement was observed. The results of this research can effectively be used for the establishment of an efficient and effective treatment method for the Gohagoda landfill leachate. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the repeatability of a new method of measurement of visual acuity by use of a psychometric function. Methods: The visual acuity of 15 healthy adults was measured by use of a psychometric function (PFVA) and by use of a conventional method using a decimal visual acuity chart (DeVA). We performed two tests. To evaluate intra-rater reliability, a tester measured the visual acuity three times for each subject, and the intraclass correlation coefficients, ICC (1,1), were calculated for PFVA and DeVA. Next, to evaluate inter-rater reliability, three testers measured the visual acuity for one subject, and the ICC (2,1) were calculated for PFVA and DeVA. The PFVA and DeVA of five subjects with ocular diseases were also measured. Results: In the evaluation of intra-rater reliability, the ICC (1,1) of the DeVA was 0.83 and the ICC (1,1) of the PFVA was 0.95. In the evaluation of inter-rater reliability, the ICC (2,1) of the DeVA was 0.88 and the ICC (2,1) of the PFVA was 0.93. In both tests the standard deviations of the PFVA were significantly lower than those of the DeVA. For four of the five subjects with ocular diseases, the PFVA was significantly improved by treatment. Conclusion: The repeatability of our method is better than that of the conventional method using a decimal visual acuity chart. [ABSTRACT FROM AUTHOR]

Cool road pavements contribute to mitigating urban heat islands. To evaluate the heat balance in paved surfaces and to select appropriate road construction materials that help suppress heat islands, an accurate understanding of heat transport parameters such as thermal conductivity (λ) and heat capacity (HC) is important. Recycled aggregates from construction and demolition waste, including scrap construction materials and industrial by-products, are often used for road construction; however, λ and HC of recycled aggregates especially for roadbeds are not fully understood. This study involved a series of laboratory tests to measure λ and HC of recycled concrete and clay brick aggregates (<40 mm) and their mixtures with autoclaved aerated concrete grains (<2 mm) under varied moisture conditions. The measured λ and HC increased with increasing volumetric water content (θ). Closed-form models for estimating λ(θ) were proposed using normalized thermal conductivity (λe) and effective saturation (Se). The new λe(Se) models performed well for the measured data compared to previously proposed models and would be useful to evaluate λ of recycled aggregates for roadbed materials. [ABSTRACT FROM AUTHOR]

Modeling water distribution and flow in partially saturated soils requires knowledge of the soil water characteristic (SWC). However, measurement of the SWC is challenging and time-consuming and, in some cases, not feasible. This study introduces two predictive models (FW-model and AW-model) for the SWC, derived from readily available soil properties such as texture and bulk density. A total of 46 undisturbed soils from different horizons at 15 locations across Denmark were used for model evaluation. The FW-model predicts the volumetric water content as a function of volumetric fines content (organic matter and clay). It performed reasonably well for the dry-end of SWC (above a pF value of 2.0; pF = log(|ψ|), where ψ is the matric potential in cm), but did not do as well closer to saturated conditions. The Aw-model predicts the volumetric water content as a function of volumetric content of different particle size fractions (organic matter, clay, silt, and fine and coarse sands). The volumetric content of a particular soil particle size fraction was considered if it contributed to the pore size fraction still occupied with water at the given pF value. Hereby, the Aw-model implicitly assumes that a given particle size fraction creates an analogue pore size fraction and further this pore size fraction filled with water is corresponding to a certain pF value according to the well-known capillary rise equation. The AW-model was found to be quite robust, and it performed exceptionally well for pF values ranging from 0.4 to 4.2 for different soil types. For prediction of the continuous SWC, it is recommended to parameterize the van Genuchten model based on the SWC data points predicted by the Aw-model. [ABSTRACT FROM AUTHOR]

Growing plants in extraterrestrial environments, for example on a space station or in a future lunar or Martian outpost, is a challenge that has attracted increasing interest over the last few decades. Most of the essential plant needs for optimal growth (air, water, and nutrient supply, and mechanical support) are closely linked with the basic physical properties of the growth media. Diffusion is the main process whereby oxygen and nutrients are supplied to plant roots, and gas and solute diffusivity are the key parameters controlling the diffusive movement of oxygen and nutrients in the root zone. As one among several essential aspects of optimal porous media design for plant growth, this study presents a diffusion-based characterization of four commercial, aggregated growth media. To account for the observed large percolation threshold for gas diffusivity in the selected media, an inactive pore and density corrected (IPDC) model was developed and excellently described measured gas diffusivity in both inter- and intraaggregate pore regions. A strong relation (r² = 0.98) between percolation threshold for gas diffusivity and mean particle (aggregate) diameter was found and suggested to be used in future design models. Also, critical windows of diffusivity (CWD) was defined identifying the air content range where gas diffusivity (hence, oxygen supply) and solute diffusivity or the analogous electrical conductivity (hence, nutrient supply) are above pre-defined, critical minimum values. Assuming different critical values for gas diffusivity under terrestrial and Martian conditions, the four growth media were compared and it was found that one medium did not fulfill the pre-set criteria. Overall, the analyses suggested that particle (aggregate) sizes below 0.25 and above 5 mm should likely be avoided when designing safe plant growth media for space. The CWD concept was also applied to a natural volcanic ash soil (Nishi-Tokyo, Japan), and the natural soil was found competitive or better than the tested commercial growth media. This could bear large perspectives for Martian outpost missions, since NASA has found that Martian dust/soil mostly resembles volcanic ash soil among terrestrial materials. [ABSTRACT FROM AUTHOR]

The gas diffusion coefficient (Ds,g) and solute diffusion coefficient (Ds,l) and their dependencies on fluid content (κ) (equal to soil-air content θ for Ds,g and soil-water content ε for Ds,l) are controlling factors for gas and solute transport in variably saturated soils. In this study, we propose unified, predictive models for Ds,g(ε) and Ds,l(θ) based on modifying and extending the classical Maxwell model at fluid saturation with a fluid-induced reduction term including a percolation threshold (εth for Ds,g and θth for Ds,l). Different percolation threshold terms adopted from recent studies for gas (Ds,g) and solute (Ds,l) diffusion were applied. For gas diffusion, εth was a function of bulk density (total porosity), while for solute diffusion θth was best described by volumetric content of finer soil particles (clay and organic matter), FINESvol. The resulting LIquid and GAs diffusivity and tortuosity (LIGA) models were tested against Ds,g and Ds,l data for differently-textured soils and performed well against the measured data across soil types. A sensitivity analysis using the new Maxwell's Law based LIGA models implied that the liquid phase but not the gaseous-phase tortuosity was controlled by soil type. The analyses also suggested very different pathways and fluid-phase connectivity for gas and solute diffusion in unsaturated soil. In conclusion, the commonly applied strategy of using the same, soil-type-independent model for gas and solute diffusivity in analytical and numerical models for chemical transport and fate in variably-saturated soils appears invalid, except for highly sandy soils. The unified LIGA model with differing percolation thresholds for diffusion in the liquid and gaseous phases solves this problem. [ABSTRACT FROM AUTHOR]

Subsurface gaseous-phase transport is governed by three gas transport parameters: the air permeability coefficient (ka), gas diffusion coefficient (DP), and gas dispersion coefficient (DH). Among these, DH is the least understood due to hitherto limited research into the relationship between gas dispersion and soil physical characteristics. In this study, a series of advection--dispersion experiments was performed on granular porous media to identify the effects of soil column dimensions (length and diameter), particle size and shape, dry bulk density, and moisture content on the magnitude of gas dispersion. Glass beads and various sands of different shapes (angular and rounded) with mean particle diameters (d50) ranging from 0.19 to 1.51 mm at both air-dry and variable moisture contents were used as granular porous media. Gas dispersion coefficients and gas dispersivities (α = DH/v, where v is the pore-gas velocity) were determined by fitting the advection--dispersion equation to the measured breakthrough curves. For all test conditions, DH increased linearly with v. The test results showed that neither soil column length nor diameter had significant effect on gas dispersivity. Under air-dry conditions, higher gas dispersivities were observed for media with wider particle size distribution and higher dry bulk density. The minor effect of particle shape on gas dispersivity was found under both air-dry and wet conditions. Under wet conditions, the variations in gas dispersivity were mainly controlled by the air-filled porosity. An empirical model was also proposed for the prediction of gas dispersivity in granular, unsaturated porous media. [ABSTRACT FROM AUTHOR]

A unified measurement system with Suction control (UMS—SC) was developed for measuring soil water characteristics curves (SWCC) and gas transport parameters under alternating drying and wetting cycles. The new system consists of a diffusion chamber, sample ring, porous plate, tensiometer, moisture sensor, oxygen electrodes, and air pressure gauges. The SWCC and gas transport parameters [gas diffusion coefficient (Dp) and air permeability (ka)] for two different porous materials, Toyoura sand and granulated slag, were simultaneously measured under drying and wetting cycles. The SWCC and gas transport parameters measured by UMSSC were consistent with recent models and independently measured data on exactly the same materials using standard experimental setups from literature. For an applied water suction head of less than 50 cm and corresponding water saturation of around 0.3-0.5, the UMS—SC data documented hysteretic (nonsingular) behavior in both measured Dp and κa under repeated drying and wetting cycles. The hysteretic behavior was insignificant for water and air contents but large for both gas transport parameters when applying suction, and hysteretic effects were larger for air permeability than for gas diffusivity. Additionally, hysteresis in the percolation threshold (soil-air content where gas transport ceases due to interconnected water-filled pores) for both gas diffusion and air permeability was insignificant for both materials. These findings should be taken into account when developing models for diffusive and convective gas transport and their parameters in variably saturated porous media. [ABSTRACT FROM AUTHOR]

A series of column experiments was conducted to investigate the transport and deposition of variably charged colloids in saturated porous media. Soil colloids with diameters <1 μm were extracted from a volcanic‐ash soil from Nishi‐Tokyo (referred to here as VAS colloids) and a red‐yellow soil from Okinawa (RYS colloids) in Japan. The VAS colloids exhibited a negative surface charge with a high pH dependency, whereas the RYS colloids exhibited a negative surface charge with less pH dependency. The soil colloids were applied as colloidal suspensions to 10‐cm‐long saturated sand columns packed with either Narita sand (mean diameter = 0.64 mm) or Toyoura sand (mean diameter = 0.21 mm) at different flow rates, suspension concentrations, and pH conditions. Both sands exhibited a negative surface charge in the measured pH range, but the pH dependency was more pronounced for the Toyoura sand. Breakthrough curves and deposition profiles for soil colloids were strong functions of the hydrodynamics, solution pH, and surface charge of the colloids and sand grains. Greater deposition was typical for lower flow rates and lower pH. The deposition of VAS colloids in both sands under low‐pH conditions exhibited depth‐dependent retention, with high colloid deposition at the column inlet. The RYS colloids were mainly deposited uniformly along columns, and depth‐dependent retention was observed only in Toyoura sand at low pH. Results suggest that decreasing solution pH enhanced surface charge neutralization of both soil colloids and sand grains, thereby increasing colloid deposition. This study emphasizes that the pH‐dependent surface charge of both mobile colloids and receiving porous media needs more consideration in models for colloid and colloid‐facilitated transport in soil. [ABSTRACT FROM AUTHOR]

Understanding colloid mobilization, transport, and deposition in the subsurface is a prerequisite for predicting colloid-facilitated transport of strongly adsorbing contaminants and further developing remedial activities. This study investigated the transport behavior of soil-colloids extracted from a red-yellow soil from Okinawa, Japan. Different concentrations of suspended-soil colloids (with diameter <1 μm) were applied, at different flow velocities and pH conditions, to 10-cm long water-saturated columns repacked with either Narita (mean diameter D50=0.64 mm) or Toyoura (mean diameter D50=0.21 mm) sands. The transport and retention of colloids were studied by analyzing colloid effluent breakthrough curves (BTCs), particle size distribution in the effluent, and colloid deposition profiles within the column. The results showed a significant influence of flow velocity: Low flow velocity caused tailing of colloid BTCs with higher reversible entrapment and release of colloids than high flow velocity. The finer Toyoura sand retained more colloids than the coarser Narita sand at low pH conditions. The deposition profile and particle size distribution of colloids in the Toyoura sand clearly indicated a depth-dependent straining mechanism. By fitting colloid transport models (one-site and two-site models) to the colloid effluent breakthrough curves, transport and deposition of colloids in Narita sand at low pH were best described by a one-site attachment-detachment model, whereas colloid transport and deposition in Toyoura sand at low pH were better captured by a two-site attachment, detachment, and straining model. The coupled effects of solution chemistry, colloid sizes, and medium surface properties have a dominating role in particle-particle and particle-collector interactions in colloid transport and deposition. [ABSTRACT FROM AUTHOR]

Gas exchange through the compacted final cover soil at landfill sites plays a vital role for emission, fate, and transport of toxic landfill gases. This study involved measuring the soil-gas diffusivity (Dp/Do, the ratio of gas diffusion coefficients in soil and free air) and air permeability (ka) for differently compacted soil samples (reddish-brown soil) from the final cover at the Maharagama landfill in Sri Lanka. The samples were prepared by either standard Proctor compaction or hand compaction to dry bulk densities of 1.60-1.94 g cm-3. Existing and modified models for predicting Dp/Do and ka were tested against the measured data. The simple, single-parameter Buckingham model predicted measured Dp/Do values across compaction levels equally well or better than a dry bulk density (DBD) dependent model and a soil-water retention (SWR) dependent model. The measured ka values for differently compacted samples were highly affected by the compaction level and the sample moisture preparation method. Also, for air permeability, a single-parameter Buckingham-type ka model was most accurate in predicting ka in the differently compacted soil samples. Equivalent air-filled pore diameters (the effective diameter of the drained pores active in leading air through the sample) for gas flow, deq, were calculated from the measured Dp/D0 and ka values. The deq increased with compaction level, suggesting that a very high compaction level creates well-connected macropores in the reduced total pore space of the cover soil. This is an important consideration when designing cover soils for optimally low water and high oxygen exchange while minimizing climate and toxic gas emissions from the waste layer to the atmosphere. [ABSTRACT FROM AUTHOR]

Accurate predictions of the soil-gas diffusivity (Dp/Do, where Dp is the soil-gas diffusion coefficient and Do is the diffusion coefficient in free air) from easily measureable parameters like air-filled porosity (e) and soil total porosity (ε) are valuable when predicting soil aeration and the emission of greenhouse gases and gaseous-phase contaminants from soils. Soil type (texture) and soil density (compaction) are two key factors controlling gas diffusivity in soils. We extended a recently presented density-corrected Dp (ε)/Do model by letting both model parameters (α and beta;) be interdependent and also functions of φ. The extension was based on literature measurements on Dutch and Danish soils ranging from sand to peat. The parameter α showed a promising linear relation to total porosity, while β also varied with α following a weak linear relation. The thus generalized density-corrected (GDC) model gave improved predictions of diffusivity across a wide range of soil types and density levels when tested against two independent data sets (total of 280 undisturbed soils or soil layers) representing Danish soil profile data (0-8 m below the ground surface) and performed better than existing models. The GDC model was further extended to describe two-region (bimodal) soils and could describe and predict Dp/Do well for both different soil aggregate size fractions and variably compacted volcanic ash soils. A possible use of the new GDC model is engineering applications such as the design of highly compacted landfill site caps. [ABSTRACT FROM AUTHOR]

Landfill sites have been implicated in greenhouse warming scenarios as a significant source of atmospheric methane. In this study, the effects of extreme compaction on the two main soil-gas transport parameters, the gas diffusion coefficient (Dp) and the intrinsic air permeability (ka), and the cumulative methane oxidation rate in a landfill cover soil were investigated. Extremely compacted landfill cover soil exhibited negligible inactive soil-air contents for both Dp and ka. In addition, greater Dp and ka were observed as compared with normal compacted soils at the same soil-air content ([variant_greek_epsilon]), likely because of reduced water-blockage effects under extreme compaction. These phenomena are not included in existing predictive models for Dp([variant_greek_epsilon]) and ka([variant_greek_epsilon]). On the basis of the measured data, new predictive models for Dp([variant_greek_epsilon]) and ka([variant_greek_epsilon]) were developed with model parameters (representing air-filled pore connectivity and water-blockage effects) expressed as functions of dry density (ρb). The developed Dp([variant_greek_epsilon]) and ka([variant_greek_epsilon]) models together with soil-water retention data for soils at normal and extreme compaction (ρb=1.44 and 1.85 g cm-3) implied that extremely compacted soils will exhibit lower Dp and ka at natural field-water content (-100 cmH2O of soil-water matric potential) because of much lower soil-air content. Numerical simulations of methane gas transport, including a first-order methane oxidation rate, were performed for differently compacted soils by using the new predictive Dp([variant_greek_epsilon]) model. Model results showed that compaction-induced difference in soil-air content at a given soil-water matric potential condition is likely the most important parameter governing methane oxidation rates in extremely compacted landfill cover soil. [ABSTRACT FROM AUTHOR]

Accurate description of the soil water retention curve (SWRC) at low water contents is important for simulating water dynamics and biochemical vadose zone processes in arid environments. Soil water retention data corresponding to matric potentials of less than −10 MPa, where adsorptive forces dominate over capillary forces, have also been used to estimate soil specific surface area (SA). In the present study, the dry end of the SWRC was measured with a chilled-mirror dew point psychrometer for 41 Danish soils covering a wide range of clay (CL) and organic carbon (OC) contents. The 41 soils were classified into four groups on the basis of the Dexter number (n = CL/OC), and the Tuller-Or (TO) general scaling model describing water film thickness at a given matric potential (<−10 MPa) was evaluated. The SA estimated from the dry end of the SWRC (SA_SWRC) was in good agreement with the SA measured with ethylene glycol monoethyl ether (SA_EGME) only for organic soils with n > 10. A strong correlation between the ratio of the two surface area estimates and the Dexter number was observed and applied as an additional scaling function in the TO model to rescale the soil water retention curve at low water contents. However, the TO model still overestimated water film thickness at potentials approaching ovendry condition (about −800 MPa). The semi-log linear Campbell-Shiozawa-Rossi-Nimmo (CSRN) model showed better fits for all investigated soils from −10 to −800 MPa and yielded high correlations with CL and SA. It is therefore recommended to apply the empirical CSRN model for predicting the dry part of the water retention curve (−10 to −800 MPa) from measured soil texture or surface area. Further research should aim to modify the more physically based TO model to obtain better descriptions of the SWRC in the very dry range (−300 to −800 MPa). [ABSTRACT FROM AUTHOR]

The air permeability (ka) and soil gas diffusion coefficients (Dp) are controlling factors for gas transport and fate in variably saturated soils. We developed a unified model for ka and Dp based on the classical Archie's law, extended by: (i) allowing for two-region gas transport behavior for structured soils, with the natural field moisture condition (set at -100 cm H2O matric potential [pF 2]) as the reference (spliced) point between the large-pore (drained pore diameter ≥30 μm at pF ≤ 2) and the small-pore (subsequently drained pores <30 μm at pF > 2) regions, and (ii) including a percolation threshold, set as 10% of the total porosity for structureless porous media or 10% of the porosity in the large-pore region for structured soils. The resulting extended Archie's law with reference point (EXAR) models for ka and Dp were fitted to the measured data. For both structureless and structure porous media, Archie's saturation exponent (n) was higher for Dp than for ka, indicating higher water blockage effects on gas diffusion. For structured soils, the saturation exponent for the large-pore region (n1) was lower than for the small-pore region (n2). Generally, n1 values of ∼ 1 for ka and 2 for Dp and n2 values of 4/3 for ka and 7/3 for Dp described the data well. Two reference-point expressions for ka at pF 2 were also developed and tested together with existing models for Dp at pF 2 against independent data across soil types. The best-performing reference-point models were a ka model based on the classical Kozeny equation and the Moldrup Dp model. [ABSTRACT FROM AUTHOR]

Purpose: A three-dimensional (3D) image viewing experiment was performed using a new 3D scenography system. The influence on visual function was investigated both in adults and in children employing both objective and subjective methods. Methods: The subjects were 21 healthy adults (mean age ± standard deviation: 42.1 ± 10.0 years) and 21 healthy children (7.8 ± 1.5 years). The 3D image viewing time was set at 90 min for adults and 60 min for children, and the visual function was objectively evaluated using an accommodative microfluctuation analysis system both before and after 3D image viewing. In addition, subjective symptoms were surveyed employing a questionnaire both before and after viewing in the adult group to subjectively evaluate the visual function. Results: No significant difference was noted in accommodative microfluctuation between the before and after viewing in either the adult or child group, nor was there a significant difference in subjective symptoms in the adult group based on the questionnaire. However, accommodative microfluctuation tended to increase after viewing in some subjects. Conclusions: Under the conditions of this study, 3D image viewing did not influence visual function, or only very slightly influenced it, if at all, but there are many unknown problems, requiring further surveys using 3D image viewing. [ABSTRACT FROM AUTHOR]

Advances in next generation technologies have driven the costs of DNA sequencing down to the point that genotyping-by-sequencing (GBS) is now feasible for high diversity, large genome species. Here, we report a procedure for constructing GBS libraries based on reducing genome complexity with restriction enzymes (REs). This approach is simple, quick, extremely specific, highly reproducible, and may reach important regions of the genome that are inaccessible to sequence capture approaches. By using methylation-sensitive REs, repetitive regions of genomes can be avoided and lower copy regions targeted with two to three fold higher efficiency. This tremendously simplifies computationally challenging alignment problems in species with high levels of genetic diversity. The GBS procedure is demonstrated with maize (IBM) and barley (Oregon Wolfe Barley) recombinant inbred populations where roughly 200,000 and 25,000 sequence tags were mapped, respectively. An advantage in species like barley that lack a complete genome sequence is that a reference map need only be developed around the restriction sites, and this can be done in the process of sample genotyping. In such cases, the consensus of the read clusters across the sequence tagged sites becomes the reference. Alternatively, for kinship analyses in the absence of a reference genome, the sequence tags can simply be treated as dominant markers. Future application of GBS to breeding, conservation, and global species and population surveys may allow plant breeders to conduct genomic selection on a novel germplasm or species without first having to develop any prior molecular tools, or conservation biologists to determine population structure without prior knowledge of the genome or diversity in the species. [ABSTRACT FROM AUTHOR]

The article discusses a research study which investigated the role of Wnt antagonist DKK1 as a tumor suppressor gene in renal cell carcinoma (RCC). The study found that the expression of DKK1 gene is genetically silenced in kidney cancer. The reexpression of DKK1 gene was found to induce apoptosis and cell cycle arrest in RCC.

Secreted frizzled-related protein-5 ( sFRP-5) has been identified as 1 of the secreted antagonists that bind Wnt protein. However, the functional significance of sFRP-5 in renal cell cancer (RCC) has not been reported. We hypothesized that sFRP-5 may be epigenetically downregulated through DNA methylation and histone modification and function as a tumor suppressor gene in RCC. Using tissue microarray and real-time RT-PCR, we found that sFRP-5 was significantly downregulated in kidney cancer tissues and cell lines, respectively. DNA bisulfite sequencing of the sFRP-5 promoter region in RCC cell lines showed it to be densely methylated, whereas there was few promoter methylation in normal kidney. The sFRP-5 expression was restored and the acetylation of H3 and H4 histones associated with the sFRP-5 promoter region were significantly increased after treatment with demethylation agent (5-Aza-dc) and histone deacetylase inhibitor (TSA). When RCC cells were transfected with the sFRP-5 gene, significant inhibition of anchorage independent colony formation and cell invasion were observed compared to controls. The sFRP-5 transfection also significantly induced apoptosis in RCC cells. In conclusion, this is the first report documenting that the sFRP-5 is downregulated by promoter methylation and histone acetylation and functions as a tumor suppressor gene by inducing apoptosis in RCC cells. [ABSTRACT FROM AUTHOR]