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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]

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]

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]

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 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]

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]

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]

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]

Spinal cord injury (SCI) rostral to the lumbosacral level causes bladder hyperreflexia and detrusor-sphincter dyssynergia (DSD), which are accompanied by bladder hypertrophy. We hypothesize that bladder augmentation using a bladder acellular matrix graft (BAMG) can improve the function of SCI-mediated neurogenic bladder. In female rats ( n = 35), SCI was induced by transection of the spinal cord at the lower thoracic level. Eight weeks following spinalization, bladder augmentation using BAMG was performed after hemicystectomy of the hypertrophic bladder. Cystometrography was performed at 8 weeks after spinalization and again at 8 weeks after augmentation. Several urodynamic parameters were measured and the grafted bladder was histologically evaluated. Thirty one rats were alive 8 weeks after spinalization. Twenty two (71%) rats developed hyperreflexic bladders and nine (29%) rats had underactive bladders before bladder augmentation. Twenty six rats survived until 8 weeks after augmentation. Urodynamic parameters showed improvement in some bladder functions in both hyperreflexic and underactive bladders after augmentation. In addition, bladder compliance was increased in hyperreflexic bladders and decreased in underactive bladders. Bladder augmentation decreased bladder capacity in high-capacity rats and increased it in low-capacity rats. Histological evaluation showed complete regeneration of BAMG in SCI-induced neurogenic bladder at 8 weeks after augmentation. This is the first report suggesting that the voiding function in SCI-induced neurogenic bladder can be improved by augmentation using BAMG. Improved voiding function was accompanied by histological regeneration of BAMG. [ABSTRACT FROM AUTHOR]

Investigates color discriminability on the background color. Measurement carried out at over 21 background colors in plane of a cone space by four observers; Use of a low temporal stimulus frequency so that threshold was determined by the red-green opponent mechanism; Sensitivity of the green-red opponent mechanism is high when the mechanism's output is small and increases with the output levels of the mechanism.