104 results on '"Chan, K. Y."'
Search Results
2. Local and Regional Staging of Nasopharyngeal Carcinoma Using Magnetic Resonance Imaging.
- Author
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Chan, K. Y. and Siu, J. C. W.
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- 2020
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3. Fuzzy System with Customized Subset Selection for Financial Trading Applications.
- Author
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Tang, W. M., Yiu, K. F. C., Chan, K. Y., and Wong, H.
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FUZZY systems ,TECHNICAL analysis (Investment analysis) ,SUBSET selection ,ALGORITHMS ,REGRESSION analysis - Abstract
In the financial industry, identifying useful information from big data becomes a key research topic. Since the vast number of technical indicators can be captured nowadays, the indicator selection can be used to support investment decision for different financial products concurrently; however, this process is still required experience from investors. In this article, we propose a novel recommendation system which is incorporated with technical indicators. The method of fuzzy subset selection is used to feature relevant indicators which have more impact to the variation in the transaction history. The proposed method enables automatic customization of indicators for different financial products in different markets. In particular, the least absolute distance fuzzy regression with non-symmetric lower and upper bounds is proposed to avoid extreme values in dominating the model. Furthermore, to reduce computational complexity in the subset selection, the selection algorithm operates in the frequency domain for identifying and matching key patterns and peaks in transacted volumes with the technical indicators. This method performs very effective although the number of factors is much greater than the sample size. The proposed method can benefit participants in the finance markets to customize their own trading dashboard as well as set up their own trading strategies. [ABSTRACT FROM AUTHOR]
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- 2019
- Full Text
- View/download PDF
4. Fuzzy System with Customized Subset Selection for Financial Trading Applications
- Author
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Tang, W. M., Yiu, K. F. C., Chan, K. Y., and Wong, H.
- Abstract
In the financial industry, identifying useful information from big data becomes a key research topic. Since the vast number of technical indicators can be captured nowadays, the indicator selection can be used to support investment decision for different financial products concurrently; however, this process is still required experience from investors. In this article, we propose a novel recommendation system which is incorporated with technical indicators. The method of fuzzy subset selection is used to feature relevant indicators which have more impact to the variation in the transaction history. The proposed method enables automatic customization of indicators for different financial products in different markets. In particular, the least absolute distance fuzzy regression with non-symmetric lower and upper bounds is proposed to avoid extreme values in dominating the model. Furthermore, to reduce computational complexity in the subset selection, the selection algorithm operates in the frequency domain for identifying and matching key patterns and peaks in transacted volumes with the technical indicators. This method performs very effective although the number of factors is much greater than the sample size. The proposed method can benefit participants in the finance markets to customize their own trading dashboard as well as set up their own trading strategies.
- Published
- 2019
- Full Text
- View/download PDF
5. Inferior Vena Cava Filter Retrieval: a Review of Seven Years' Experience at a Regional Hospital.
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Chong, W. H., Siu, K. L., Wan, W. S., Chan, K. Y., and Tan, C. B.
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- 2017
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6. Calibration of Electrostatic Discharge (ESD) Generator in Accordance with IEC61000-4-2: 2008 at SCL
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Lai, H. W., Chow, Michael W. K., and Chan, K. Y.
- Abstract
AbstractThis article demonstrates the essential procedures in the Hong Kong Standards and Calibration Laboratory for the calibration of an electrostatic discharge (ESD) generator in accordance with the International Standard IEC 61000-4-2 Edition 2.0 (2008–12) on electromagnetic compatibility. All the required instruments and special precautions to perform the calibration are listed clearly. The performance of an ESD generator has been tested and reported by following the requirements of the standard. The corresponding results, including the waveform parameters of the current discharge pulse and the DC high voltage test of the ESD generator before discharge with different voltages setting, are reported. The determination of uncertainty components is a critical factor for achieving an accurate measurement result. The measurement uncertainties of the calibration are suggested and clearly listed in this paper, and they are evaluated in accordance with the document “Guide to the Expression of Uncertainty in Measurement (GUM).” The expanded measurement uncertainty U, with level of confidence of approximate 95 % probability is used in the calibration.
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- 2018
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7. SI Engine Simulation Using Residual Gas and Neural Network Modeling to Virtually Estimate the Fuel Composition.
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Chan, K. Y., Ordys, A., Duran, O., Volkov, K., and Deng, J.
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SPARK ignition engines ,ARTIFICIAL neural networks ,COMPUTER simulation ,EMISSION control ,ALGORITHMS ,COMPUTER-aided design ,ENGINE design & construction - Abstract
Research in electronic controlled internal combustion engines mainly focuses on improving performance and lowering the emissions. Combustion performance depends on the geometry of cylinders and on the design of all mechanical parts, which are based on the laboratory experimental research. Due to the limitations of the materials used in the engine and the continuous high operating temperature, engines function in either spark ignition or charge ignition processes. Recent research on computer controlled engines uses sensors and electronic actuators which allows switching the engine operational mode between spark ignition and charge ignition. Thus, this makes possible to mix intake fuel compositions in order to give more choices to consumers. This study employs a neural network which is capable of estimating fuel composition using the parameters of residual gas. The simulation is based on a thermodynamic engine model implemented in Matlab Simulink. The main advantages are the capabilities of the model to 1) calculate the gas exchange as a function of time in transient mode, and 2) to generate data for the design control algorithms without the need of the engine bed test environment to test various fuel compositions. [ABSTRACT FROM AUTHOR]
- Published
- 2013
8. An Integrated Approach of Support Vector Machine and Variable Neighborhood Search for Discovering Combinational Gene Signatures in Predicting Chemo-response of Osteosarcoma.
- Author
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Chan, K. Y, Zhu, H. L., Aydin, M. E., Lau, C. C., and Wang, H. Q.
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SUPPORT vector machines ,ALGORITHMS ,GENES ,OSTEOSARCOMA ,CANCER chemotherapy ,DNA microarrays ,THERAPEUTICS - Abstract
Analyzing microarray data could help discover significant cancer genes and their mutual interactions, which can be used to generate hypothesis for the identification and validation of genetic biomarkers. However, the commonly used statistical significance analysis can only provide information of individual genes, thus neglecting influence of the mutual interactions. Therefore, methods aiming at discovering combinational gene signatures are highly valuable. In this paper, an integrated approach of support vector machine (SVM) and variable neighborhood search (VNS) is introduced in searching the gene signatures for predicting histologic response of chemotherapy on osteosarcoma patients. Cross validation results show that this method outperforms other existing algorithms. Further validation with the test dataset shows that only one of the fourteen samples is misclassified. The high testing accuracy further suggests that the proposed method has capability of extracting the stable discriminative signatures from microarray data. [ABSTRACT FROM AUTHOR]
- Published
- 2008
9. Temperature and diet modified swimming behaviors of larval sand dollar.
- Author
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Chan, K. Y. K. and Grüinbaum, D.
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LARVAE ,SAND dollars ,SEA urchin behavior ,TEMPERATURE ,DIET ,FATTY acids - Abstract
The article presents a study which looked at changes in the swimming behaviors of larval sand dollar due to temperature and diet. According to previous studies, larvae swim more slowly at lower temperatures and that improved diet quality in terms of essential fatty acid composition increases cold tolerance in many organisms. For this study, the researchers collected adult sand dollars Dendraster excentricus from Crescent Beach, East Sound, Orcas Island in Washington in early summer 2008. They have found that swimming behaviors of invertebrate larvae can significantly affect larval survival as well as dispersal outcomes.
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- 2010
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10. Environmental Risk Assessment of Compost Prepared from Salvinia, Egeria densa, and Alligator Weed.
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Dorahy, C. G., Pirie, A. D., McMaster, I., Muirhead, L., Pengelly, P., Chan, K. Y., Jackson, M., and Barchia, I. M.
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ENVIRONMENTAL risk assessment ,AQUATIC weed control ,SALVINIA molesta ,EGERIA densa ,ALTERNANTHERA phylloxeroides ,COMPOSTING ,COMPOST & the environment - Abstract
The article discusses research regarding an environmental risk assessment of compost prepared from salvinia (Salvinia molesta), Egeria densa, and alligator weed (Alternanthera philoxeroides). Salvinia, which is an aquatic weed, was removed from the Hawkesbury-Nepean River in New South Wales (NSW) in 2004 and an assessment was performed to evaluate the risks associated with applying compost prepared from it and several other aquatic weeds (AWC). The focus of the study was the survival and spread of AWC and terrestrial weeds, eutrophication of waterways, and the accumulation of heavy metals and phototoxic compounds. The effectiveness of composting on the viability of AWC and terrestrial weeds, specifically alligator weed which was used as an indicator plant, is also discussed.
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- 2009
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11. Soil carbon dynamics under different cropping and pasture management in temperate Australia: Results of three long-term experiments
- Author
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Chan, K. Y., Conyers, M. K., Li, G. D., Helyar, K. R., Poile, G., Oates, A., and Barchia, I. M.
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- 2011
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12. Sequential linearization in analytical target cascading for optimization of complex multilevel systems
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Chan, K-Y
- Abstract
Large-scale design problems are high dimensional and deeply coupled in nature. The complexity of such large-scale systems prevents designers from solving them as a whole. Analytical target cascading (ATC) provides a systematic approach in solving decomposed large-scale systems that has solvable subsystems. By coordinating between subsystems, ATC can obtain the same optima as they were undecomposed. However, a convergent coordination requires series of ATC iterations that may hinder the efficiency of ATC. In this research, a sequential linearization technique is proposed to improve the efficiency of ATC. The proposed linearization technique is applied to each ATC iteration, and therefore each iteration has all linear subsystems that can be solved with high efficiency. The global convergence of this approach is ensured by a filter to determine the acceptance of the optima at each iteration and the corresponding trust region. One further motivation of the proposed strategy is its perceived potential in handling multilevel problems with random design variables. As previously studied, the sequential linear programming (SLP) algorithm provides a good balance between efficiency, accuracy, and convergence for single-level design optimization under random design variables. The proposed linearization technique can integrate with the SLP algorithm for multilevel systems. In this work, a geometric programming example is used to demonstrate the efficiency of the proposed method over standard ATC solution process without loss of accuracy.
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- 2011
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13. Comparison of three carbon determination methods on naturally occurring substrates and the implication for the quantification of ‘soil carbon’
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Conyers, M. K., Poile, G. J., Oates, A. A., Waters, D., and Chan, K. Y.
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Accounting for carbon (C) in soil will require a degree of precision sufficient to permit an assessment of any trend through time. Soil can contain many chemically and physically diverse forms of organic and inorganic carbon, some of which might not meet certain definitions of ‘soil carbon’. In an attempt to assess how measurements of these diverse forms of C might vary with analytical method, we measured the C concentration of 26 substrates by three methods commonly used for soil C (Walkley–Black, Heanes, and Leco). The Heanes and Leco methods were essentially equivalent in their capture of organic C, but the Leco method captured almost all of the inorganic C (carbonates, graphite). The Heanes and Walkley–Black methods did not measure carbonates but did measure 92% and 9%, respectively, of the C in graphite. All three of the common soil test procedures measured some proportion of the charcoal and of the other burnt materials. The proportion of common organic substrates (not the carbonates, graphite, or soil) that was C by weight ranged from ~10% to 90% based on the Heanes and Leco data. The proportion of the organic fraction of those same substrates, as measured by loss-on-ignition, that was C by weight ranged from 42% to 100%. The relationship between Walkley–Black C and total C (by Heanes and Leco) showed that Walkley–Black C was a variable proportion of total C for the 26 substrates. Finally, the well-known, apparent artefact in the Cr-acid methods was investigated: dichromate digestion should contain at least 7–10mg C in the sample or over-recovery of C might be reported. Our observation that common soil C procedures readily measure C in plant roots and shoots, and in burnt stubble, means that there will likely be intra-annual variation in soil C, because avoidance of these fresh residues is difficult. Such apparent intra-annual variation in soil C will make the detection of long-term trends problematic.
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- 2011
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14. Effect of composted mulch application on soil and wine grape potassium status
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Chan, K. Y. and Fahey, D. J.
- Abstract
Oversupply of potassium (K) to grape vines can result in high grape berry K and pH, leading to difficulty in wine making and low wine quality. There is concern that application of mulch to grape vines may increase K supply and the associated risks. The effect of composted mulch from green wastes was investigated in a field trial involving six vineyards in New South Wales on soils commonly used for viticulture production in Australia, over three seasons (2006–08). Significant increases in extractable soil K were detected as a result of mulch application. Higher berry K and pH were also observed due to the mulch treatments, with the changes dependent on season and mulch rate. Increases in berry K were significantly related to the higher soil exchangeable K. The mean increase in berry K due to a mulch rate of 153m3/ha was 123mg/kg. The mean increase in berry pH was 0.02 units observed in two seasons. Application of mulch can increase berry K and pH, but the changes are small compared with variations observed among vineyard sites and between seasons.
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- 2011
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15. Characterization of the calcitonin gene-related peptide receptor antagonist telcagepant (MK-0974) in human isolated coronary arteries.
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Chan, K Y, Edvinsson, L, Eftekhari, S, Kimblad, P O, Kane, S A, Lynch, J, Hargreaves, R J, de Vries, R, Garrelds, I M, van den Bogaerdt, A J, Danser, A H J, and Maassenvandenbrink, A
- Abstract
The sensory neuropeptide calcitonin gene-related peptide (CGRP) plays a role in primary headaches, and CGRP receptor antagonists are effective in migraine treatment. CGRP is a potent vasodilator, raising the possibility that antagonism of its receptor could have cardiovascular effects. We therefore investigated the effects of the antimigraine CGRP receptor antagonist telcagepant (MK-0974) [N-[(3R,6S)-6-(2,3-difluorophenyl)-2-oxo-1-(2,2,2-trifluoroethyl)azepan-3-yl]-4-(2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridine-1-yl)piperidine-1-carboxamide] on human isolated coronary arteries. Arteries with different internal diameters were studied to assess the potential for differential effects across the coronary vascular bed. The concentration-dependent relaxation responses to human alphaCGRP were greater in distal coronary arteries (i.d. 600-1000 microm; E(max) = 83 +/- 7%) than proximal coronary arteries (i.d. 2-3 mm; E(max) = 23 +/- 9%), coronary arteries from explanted hearts (i.d. 3-5 mm; E(max) = 11 +/- 3%), and coronary arterioles (i.d. 200-300 microm; E(max) = 15 +/- 7%). Telcagepant alone did not induce contraction or relaxation of these coronary blood vessels. Pretreatment with telcagepant (10 nM to 1 microM) antagonized alphaCGRP-induced relaxation competitively in distal coronary arteries (pA(2) = 8.43 +/- 0.24) and proximal coronary arteries and coronary arterioles (1 microM telcagepant, giving pK(B) = 7.89 +/- 0.13 and 7.78 +/- 0.16, respectively). alphaCGRP significantly increased cAMP levels in distal, but not proximal, coronary arteries, and this was abolished by pretreatment with telcagepant. Immunohistochemistry revealed the expression and colocalization of the CGRP receptor elements calcitonin-like receptor and receptor activity-modifying protein 1 in the smooth muscle cells in the media layer of human coronary arteries. These findings in vitro support the cardiovascular safety of CGRP receptor antagonists and suggest that telcagepant is unlikely to induce coronary side effects under normal cardiovascular conditions.
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- 2010
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16. Active-set sequential quadratic programming with variable probabilistic constraint evaluations for optimization problems under non-Gaussian uncertainties
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Chan, K-Y and Huang, Y-C
- Abstract
Design optimization under random uncertainties are formulated as problems with probabilistic constraints. Calculating these constraints presents a major challenge in the optimization. While most research concentrates on uncertainties that are Gaussian, a great number of uncertainties in the environment are non-Gaussian. In this work, various reliability analyses for non-Gaussian uncertainties within a sequential quadratic programming framework are integrated. An analytical reliability contour (RC) is first constructed in the design space to indicate the minimal distance from the feasible boundary of a design at a desired reliability level. A safe zone contour is then created so as to provide a quick estimate of the RC. At each design iteration reliability analyses of different accuracies are selected based on the level needed, depending on the activity of a constraint. For problems with a large number of constraints and relatively few design variables, such as structural problems, the active set strategies significantly improve efficiency, as demonstrated in the examples.
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- 2010
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17. Effect of gypsum on establishment, persistence and productivity of lucerne and annual pasture legumes on two grey Vertosols in southern New South Wales
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Dear, B. S., Peoples, M. B., Hayes, R. C., Swan, A. D., Chan, K. Y., Oates, A. A., Morris, S. G., and Orchard, B. A.
- Abstract
Changes in pasture yield and botanical composition due to gypsum application were examined on Vertosols at two locations of differing soil sodicity, Grogan and Morangarell, in southern New South Wales. Two pasture treatments were examined. One was an annual pasture comprised of 3 annual legumes (2 subterranean clover Trifolium subterraneumL. cultivars, Clare and Riverina, and balansa clover T. michelianumSavi cv. Paradana), while the second treatment consisted of lucerne (Medicago sativaL.) cv. Aquarius sown in a mixture with the same annual legumes. Gypsum had no effect on the establishment or persistence of lucerne at either site. Gypsum increased the number of subterranean clover seedlings present in autumn in annual swards at the more sodic Grogan site in each of the 4 years, but provided no difference when the clover was in a mixture with lucerne. Annual legume seed yields in annual-only swards increased with gypsum by up to 58% at Grogan and 38% at Morangarell. Seed yields of both cultivars of subterranean clover declined as a proportion of the total annual legume seed bank when lucerne was included in the mixture, in contrast to balansa clover (at Grogan) and the naturalised annual legumes, burr medic (M. polymorphaL.) and woolly clover (T. tomentosumL.), which all increased in relative seed yield in the presence of lucerne. Total pasture production at the Grogan site increased with gypsum by up to 15% per annum in annual swards and 36% in lucerne swards depending on the season. Yield responses to gypsum by the lucerne component were observed in 10 of the 13 seasonal yield measurements taken at Grogan. However, total pasture yield and seasonal yields were unaffected by both gypsum and pasture type at the less sodic Morangarell site. It was concluded that sowing a diverse mixture of annual legumes or polycultures was conducive to maintaining productive pastures on these spatially variable soils. Lucerne dried the soil profile (0.15–1.15m) more than annual pastures at both sites. The combination of gypsum and lucerne enhanced water extraction at depth (0.6–1.15m) at the Grogan site increasing the size of the dry soil buffer whereas gypsum increased soil water at depth (>0.6m) under annual swards.
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- 2010
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18. A glasshouse study on the interaction of low mineral ash biochar with nitrogen in a sandy soil
- Author
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van Zwieten, L., Kimber, S., Downie, A., Morris, S., Petty, S., Rust, J., and Chan, K. Y.
- Abstract
The effect of a low mineral ash biochar on biomass production and nitrogen (N) uptake into plants was tested with wheat and radish in a Yellow Earth used for commercial vegetable production. The biochar had an acid neutralising capacity <0.5% CaCO3, a total C content of 75%, and a molar H/C ratio of 0.45, indicating stability due to its aromaticity. A pot trial was established under climate-controlled conditions. Five rates of N fertiliser (0, 17, 44, 88, 177kgN/ha) were applied as urea in combination with 5 biochar rates (0, 1.1, 2.2, 4.4, 11% w/w). Analysis of biomass production revealed a significant biochar×N fertiliser interaction. In particular, increasing biochar concentrations improved biomass production in both crop species at lower N application rates. The highest biochar application rate resulted in significantly greater accumulation of NO3--N in the soil and lower NH4+-N averaged across the 5N application rates. The biochar also decreased available P, and significantly increased microbial activity measured using the fluorescein diacetate method. Increasing N fertiliser application resulted in greater accumulation of NO3--N with no changes to NH4+-N averaged across the 5 biochar application rates. Nitrogen fertiliser application did not influence microbial activity or biomass C. The trial suggests that in some cropping systems, biochar application will enable reduced N fertiliser input while maintaining productivity.
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- 2010
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19. Soil carbon stocks under different pastures and pasture management in the higher rainfall areas of south-eastern Australia
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Chan, K. Y., Oates, A., Li, G. D., Conyers, M. K., Prangnell, R. J., Poile, G., Liu, D. L., and Barchia, I. M.
- Abstract
In Australia, pastures form the basis of the extensive livestock industries and are important components of crop rotation systems. Despite recent interest in the soil carbon sequestration value of pastures in the mitigation of climate change, little information is available on the soil carbon sequestration potential of pastures in New South Wales farming systems. To quantify the soil carbon stocks under different pastures and a range of pasture management practices, a field survey of soil carbon stocks was undertaken in 2007 in central and southern NSW as well as north-eastern Victoria, using a paired-site approach. Five comparisons were included: native v. introduced perennial, perennial v. annual, continuous v. rotational grazing, pasture cropping v. control, and improved v. unimproved pastures. Results indicated a wide range of soil organic carbon (SOC) stocks over 0–0.30m (22.4–66.3tC/ha), with little difference when calculated based on either constant soil depth or constant soil mass. Significantly higher SOC stocks were found only as a result of pasture improvement using P application compared with unimproved pastures. In this case, rates of sequestration were estimated to range between 0.26 and 0.72tC/ha.year, with a mean rate of 0.41tC/ha.year. Lack of significant differences in SOC stocks for the other pastures and pasture management practice comparisons could be due to inherent problems associated with the paired-site survey approach, i.e. large variability, difficulties in obtaining accurate site history, and the occasional absence of a valid control as well as the likely lower rates of SOC sequestration for these other comparisons. There is a need for scientific long-term trials to quantify the SOC sequestration potential of these other pastures and pasture management practices.
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- 2010
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20. Assessing P fertiliser use in vegetable production: agronomic and environmental implications
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Chan, K. Y., Wells, T., Fahey, D., Eldridge, S. M., and Dorahy, C. G.
- Abstract
Vegetable production is often located in the peri-urban areas close to large cities. In Sydney, Australia, excessive levels of phosphorus (P) have been reported in the soils, and vegetable farms have long been regarded as a potential source of the P that enters Sydney’s waterways. We report vegetable production under varying soil P conditions and the consequent changes in soil P, as well as water quality of runoff and leachate after growing 5 crops in a field trial where inputs in the form of garden organic compost were compared to current farmers’ practice. No difference in vegetable yield was observed between 100 and 400mg/kg of soil Colwell P (0–0.10m); therefore, our results indicate that the excessive soil P levels in the vegetable farms around Sydney are not important for optimal vegetable production. Results from runoff and leachate studies clearly demonstrate that high concentrations of P in soils used for vegetable production under the current farming practice around Sydney have increased the potential to export P and to negatively affect water quality of receiving environments. The significant increases in soluble P concentrations found in the soil and runoff water from the current farming practice can be attributed to the use of poultry litter. In contrast, using compost in place of poultry litter resulted in significantly reduced soil P accumulation and P concentration in runoff and leachate. Training and education programs for farmers and their advisors are recommended to encourage more sustainable fertiliser management practices and reduce the accumulation of P in the environment.
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- 2010
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21. Environmental Risk Assessment of Compost Prepared from Salvinia, Egeria densa, and Alligator Weed
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Dorahy, C. G., Pirie, A. D., McMaster, I., Muirhead, L., Pengelly, P., Chan, K. Y., Jackson, M., and Barchia, I. M.
- Abstract
Approximately 70,000 m3of salvinia (Salvinia molesta) was removed from the Hawkesbury‐Nepean River, New South Wales (NSW), Australia, during 2004. This study assessed the risks associated with applying compost prepared from aquatic weeds (AWC) to land, namely, survival and spread of aquatic and terrestrial weeds, eutrophication of waterways, accumulation of heavy metals and phytotoxicity. The results demonstrate composting is an effective method of reducing the viability of aquatic and terrestrial weeds. However, mortality of alligator weed (Alternanthera philoxeroides), which was used as an indicator plant, was significantly (P< 0.001) correlated with the temperature within the windrows and the length of time the material was subjected to composting. Conditions within the central core of the windrow were sufficient to kill the alligator weed, although not all of the aquatic weed material was exposed to the windrows' central core. This resulted in alligator weed continuing to grow at the base of the windrow. To reduce the risk of weeds surviving and spreading in aquatic and terrestrial environments it is suggested compost windrows should be located on an appropriate hard pad to enable complete mixing of the material and ensure all material is exposed to temperatures >55°C for greater than three consecutive days. The likelihood of other risks associated with the AWC was low. If composting is selected as the preferred method for managing organic material harvested from waterways, then ongoing monitoring and evaluation is required to validate the composting process and ensure consumer confidence in the final product.
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- 2009
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22. Liquid phase deposition of iron and cobalt doped TiO2epitaxial thin films
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Chan, K. Y. S., Goh, G. K. L., and Han, M. Y.
- Abstract
Liquid phase deposition LPD is a wet process in which metal oxide thin films can be deposited on substrates via a chemical equilibrium reaction between a metal fluorocomplex and a metal oxide in aqueous solution. In this study, iron and cobalt doped TiO2anatase thin films were deposited on 001 oriented SrTiO3single crystal substrates using liquid phase deposition. The process involves the reaction of ammonium hexafluorotitanate and boric acid, in the presence of FeOOH–HF and CoNO32–ethylenediamine en for the iron and cobalt doped TiO2films respectively. Cobalt doping was also attempted by immersing a nondoped TiO2film in a solution of Coen ions. XRD shows that the films are caxis oriented and films epitaxy was confirmed using pole figure measurements. No metallic secondary phases were detected by XRD and XPS. The iron and cobalt doped films are observed to yield room temperature ferromagnetism. The insulating nature of the films suggests that bound magnetic polarons are responsible for the observed ferromagnetism. © 2008 WILEYVCH Verlag GmbH & Co. KGaA, Weinheim
- Published
- 2008
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23. Using poultry litter biochars as soil amendments
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Chan, K. Y., Van Zwieten, L., Meszaros, I., Downie, A., and Joseph, S.
- Abstract
Despite the recent interest in biochars as soil amendments for improving soil quality and increasing soil carbon sequestration, there is inadequate knowledge on the soil amendment properties of these materials produced from different feed stocks and under different pyrolysis conditions. This is particularly true for biochars produced from animal origins. Two biochars produced from poultry litter under different conditions were tested in a pot trial by assessing the yield of radish (Raphanus sativus var. Long Scarlet) as well as the soil quality of a hardsetting Chromosol (Alfisol). Four rates of biochar (0, 10, 25, and 50 t/ha), with and without nitrogen application (100 kg N/ha) were investigated. Both biochars, without N fertiliser, produced similar increases in dry matter yield of radish, which were detectable at the lowest application rate, 10 t/ha. The yield increase (%), compared with the unamended control rose from 42% at 10 t/ha to 96% at 50 t/ha of biochar application. The yield increases can be attributed largely to the ability of these biochars to increase N availability. Significant additional yield increases, in excess of that due to N fertiliser alone, were observed when N fertiliser was applied together with the biochars, highlighting the other beneficial effects of these biochars. In this regard, the non activated poultry litter biochar produced at lower temperature (450°C) was more effective than the activated biochar produced at higher temperature (550°C), probably due to higher available P content. Biochar addition to the hardsetting soil resulted in significant but different changes in soil chemical and physical properties, including increases in C, N, pH, and available P, but reduction in soil strength. These different effects of the 2 different biochars can be related to their different characteristics. Significantly different changes in soil biology in terms of microbial biomass and earthworm preference properties were also observed between the 2 biochars, but the underlying mechanisms require further research. Our research highlights the importance of feedstock and process conditions during pyrolysis on the properties and, hence, soil amendment values of biochars.
- Published
- 2008
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24. Plant-available nitrogen supply from granulated biosolids: implications for land application guidelines
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Eldridge, S. M., Chan, K. Y., Xu, Z. H., Chen, C. R., and Barchia, I.
- Abstract
Current State government guidelines attempt to ensure that the supply of plant available nitrogen (PAN) from land-applied biosolids does not exceed the crop's requirement for mineral nitrogen (N), in order to minimise the risk of excess nitrate contaminating surface and groundwater. In estimating a suitable application rate, current guideline methodology assumes a fixed proportion of the organic N in the biosolids will be mineralised in the first year following the application for all situations. Our study included a field trial and a field incubation study to assess N mineralisation for both a granulated biosolid and a dewatered biosolid product, together with an additional laboratory incubation study for the granulated biosolid product. The application rates were 12, 24, and 48 dry t/ha for the granulated biosolids and 22 dry t/ha for the dewatered biosolids.Our results showed that the guideline procedure underestimated the supply of mineral N from the biosolid-treated soils, with more than 3 times the predicted amount being supplied by the biosolids at all application rates. The excess supply of mineral N was due to a much larger proportion of the biosolid organic N being mineralised than the assumed 25%, as well as a significant contribution of mineral N from the soil itself (which is ignored in the estimation calculation). The proportion of biosolid organic N mineralised in the 12-month field incubation study for the 3 granulated biosolid treatments (12, 24, and 48 dry t/ha) and the dewatered biosolid treatment (22 dry t/ha) were estimated to be 54%, 48%, 45%, and 53%, respectively, in our field incubation study. Both the laboratory and field incubation studies found that most of the biosolid mineralisable organic N was mineralised rapidly during the early stages of the incubation. In the field incubation, the 24 dry t/ha granulated biosolid treatment had 35% of its organic N mineralised within the first 2 months following application, while all granulated biosolid treatments in the laboratory incubations had by, day 29, supplied >50% of the mineral N they would supply for the whole 216-day incubation. This release pattern for the supply of PAN from biosolid organic N should be factored into fertiliser application strategies. Our study reveals some of the shortcomings of the currently recommended ‘one size fits all' approach for estimating the PAN supply from land-applied biosolids. Further research on the development of an effective rapid assessment for the mineralisable N content in organic wastes and soils, in combination with modelling, may improve our capacity to predict PAN supply from land-applied organic wastes in the future.
- Published
- 2008
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25. Use of garden organic compost in vegetable production under contrasting soil P status
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Chan, K. Y., Dorahy, C., Wells, T., Fahey, D., Donovan, N., Saleh, F., and Barchia, I.
- Abstract
Little research has been carried out on the agronomic value of compost produced from garden organics for vegetable production. A field experiment was established in Camden, near Sydney, Australia, to (i) evaluate the effect of the compost on vegetable production and soil quality relative to conventional practice, (ii) compare vegetable production under high and low soil P status, and (iii) monitor the changes in soil P concentration under two compost treatments relative to conventional farmers' practice. After three successive crops (broccoli, eggplant and cabbage), results indicate that compost (120 dry t/ha) and half-compost (60 dry t/ha supplemented by inorganic fertilisers) treatments can produce similar yield to the conventional practice of using a mixture of poultry manure and inorganic fertiliser. Furthermore, similar yields were achieved for three different crops grown under high and low P soil conditions, clearly demonstrating that the high extractable soil P concentrations currently found in the vegetable farms of Sydney are not necessary for maintaining productivity. The compost treatments also significantly increased soil organic carbon and soil quality including soil structural stability, exchangeable cations, and soil biological properties. Importantly, the compost treatment was effective in reducing the rate of accumulation of extractable soil P compared with the conventional vegetable farming practice. Our results highlight the potential for using compost produced from source separated garden organics in reversing the trend of soil degradation observed under current vegetable production, without sacrificing yield.
- Published
- 2008
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26. Phosphorus accumulation and other changes in soil properties as a consequence of vegetable production, Sydney region, Australia
- Author
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Chan, K. Y., Dorahy, C. G., Tyler, S., Wells, A. T., Milham, P. P., and Barchia, I.
- Abstract
A survey of 34 farms covering the major soil types used for growing vegetables within the greater Sydney metropolitan region (New South Wales, Australia) was undertaken to determine the effect of vegetable production on soil chemical and physical properties. Comparison of farmed ?vegetable' v. unfarmed ?reference' sites revealed that the soils used for vegetable production had extremely high concentrations of total P, Colwell-P, and CaCl2-extractable P (mean 1205, 224, and 4.3mg/kg in the 0?0.30m layer, respectively). In the 0?0.30m soil layer, mean bicarbonate-extractable P (Colwell-P) concentrations have increased to up to 44 times that of the unfarmed reference soils and exceed that required for adequate vegetable nutrition. Concentrations of P in the soil solution (CaCl2-P) were up to 230 times that of the unfarmed reference soils. Moreover, the vegetable soils had low total soil carbon concentrations (mean 14.1g/kg in the 0?0.10m layer, only 57% of the mean concentration of the reference soils). These soils exhibited extremely low structural stability, which is likely to reduce soil infiltration rates and increase the potential for runoff. Marked changes in soil pH, EC, and exchangeable cations (Ca, Mg, and K) were also observed as a consequence of vegetable production. All of these changes are a consequence of current management practices used in vegetable production, which include application of high rates of inorganic fertilisers and poultry manure, as well as excessive cultivation. Excessive accumulation of P, to at least 0.30m depth, coupled with a loss of soil structural stability, is of particular environmental concern. Options such as adopting minimum tillage, in conjunction with using alternative inputs such as low P composts and cover crops, as a means of improving soil structure and reducing the extent of P accumulation in these soils require further investigation.
- Published
- 2007
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27. Agronomic values of greenwaste biochar as a soil amendment
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Chan, K. Y., Van Zwieten, L., Meszaros, I., Downie, A., and Joseph, S.
- Abstract
A pot trial was carried out to investigate the effect of biochar produced from greenwaste by pyrolysis on the yield of radish (Raphanus sativus var. Long Scarlet) and the soil quality of an Alfisol. Three rates of biochar (10, 50 and 100t/ha) with and without additional nitrogen application (100kgN/ha) were investigated. The soil used in the pot trial was a hardsetting Alfisol (Chromosol) (0?0.1m) with a long history of cropping. In the absence of N fertiliser, application of biochar to the soil did not increase radish yield even at the highest rate of 100t/ha. However, a significant biocharנnitrogen fertiliser interaction was observed, in that higher yield increases were observed with increasing rates of biochar application in the presence of N fertiliser, highlighting the role of biochar in improving N fertiliser use efficiency of the plant. For example, additional increase in DM of radish in the presence of N fertiliser varied from 95% in the nil biochar control to 266% in the 100t/ha biochar-amended soils. A slight but significant reduction in dry matter production of radish was observed when biochar was applied at 10t/ha but the cause is unclear and requires further investigation. Significant changes in soil quality including increases in pH, organic carbon, and exchangeable cations as well as reduction in tensile strength were observed at higher rates of biochar application (>50t/ha). Particularly interesting are the improvements in soil physical properties of this hardsetting soil in terms of reduction in tensile strength and increases in field capacity.
- Published
- 2007
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28. Earthworm population dynamics under conservation tillage systems in south-eastern Australia
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Chan, K. Y. and Heenan, D. P.
- Abstract
Changes in earthworm abundance, biomass, and diversity were monitored under a range of tillage and stubble management practices in a wheat/alternative crop rotation over 5 years on a Sodosol (Alfisol) in southern New South Wales, Australia. There were 3 tillage and 2 stubble management practices in a completely randomised block design with 3 replications. The 3 tillage treatments were no-tillage (NT), 1 tillage pass (1T), and 3 tillage passes (3T). Stubble management practices were stubble retained (sr) and stubble burnt (sb). Positive responses of earthworm abundance and biomass to stubble retention (>2-fold increase) were evident in the second year and to both stubble and tillage in the third year. In the latter, abundance in NT/sr was 6.6 times that found under 3T/sb (239 v. 36/m2). Higher earthworm abundance in NT/sr compared with 3T/sb prevailed for the remaining duration of the experiment. However, a drastic decline in total population (to a mean of 31/m2) was observed in the fourth year in all the treatments and this was followed by further decline to a mean abundance of 4/m2 in the fifth year. The drastic decline in abundance was also accompanied by a shift in earthworm species composition. The earthworm population was originally dominated by the exotic Lumbrid, Aporrectodea trapezoides (Lumbricidae) (~100% in composition), but by the fifth year, Microscolex dubious (Acanthodrilidae) was the dominant species, making up 75% of the earthworm population in NT/sr. Improvement in soil quality as detected in the fifth year under a conservation tillage system compared with a conventional system included higher transmitting macropores, higher labile carbon, and water-stable aggregation. The reason for the decline in earthworm abundance was not clear but was unlikely related to changes in soil quality, wheat yield, and rainfall. Instead, we suggest that it was related to the changes in insecticide applications during the course of the experiment. The study highlights the importance of judicious use of chemicals in farming systems if earthworm presence is to be encouraged.
- Published
- 2006
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29. Modelling the effects of soil properties on the concentration of Cd extracted by 10 mM CaCl2 from soils of the Sydney Basin
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Milham, P. J., Jinadasa, K. B. P. N., Collins, D., Nicholls, P. J., Hawkins, C. A., Wenzel, R. G., Kaldor, C. J., Senn, A. A., Humphris, C. S., Fabien, J., Conyers, M. K., Chan, K. Y., Holford, P., and Conroy, J. P.
- Abstract
Undisturbed surface soils on the peri-urban fringe of the Sydney Basin are mostly acidic, with low concentrations of total cadmium (Cdt) and a wide range of other properties. In taxonomically similar soils on vegetable farms, Cdt is typically about 20-fold greater and undesirably large concentrations of Cd occur in some of the vegetables. We used a sequence of multiple regression models to evaluate how soil properties, taxonomy, and farming affected the behaviour of Cd in surface composites (0?15 cm) from 29 farmed and 12 unfarmed sites in the Basin. The dependent variable was the log10 transformation of the concentration of Cd extracted in 1 h by 10 mm CaCl2 solution (log10CdCa). The range of values of CdCa was 0.2?60 ?g/L. The independent variables in the base model were pHCa and log10Cdt (R2 = 0.885, r.s.d. = 0.245). The final model contained 2 additional log10-transformed soil properties: effective cation exchange capacity (ECEC) and oxalate-extractable Fe (Feox) (R2 = 0.974, r.s.d. = 0.121). The effect of log10Feox was significant (P < 0.05), but only when pHCa was > 5.6, the approximate sorption edge for Cd on goethite. The effects of other soil properties could not be adequately tested because the residual variation was too small. The measured values of CdCa had a median error of 17% and a maximum error of 58% relative to the back-transformed fitted values from the final model. The coefficient of log10Cdt in the final model was 1.33 0.05 for the farmed soils and 1.01 0.04 for the unfarmed soils, i.e. log10CdCa was more sensitive to changes in log10Cdt in the farmed than the unfarmed soils (P < 0.01). This difference is consistent with the effects of the greater load and briefer duration of contact for Cd in the farmed soils. The coefficients of pHCa and of log10ECEC in our final model had values of 0.49 ( 0.03) and 0.69 ( 0.08). These values are remarkably similar to those obtained when we fitted our data, using a model that had been used to describe the effects of soil properties on a compilation of Cd-sorption data, and to those in a partitioning model based on the desorption of Cd from contaminated soils. That is, the behaviour of Cd may be influenced by the duration of contact between Cd and the soil, and perhaps the load; however, neither factor appears to change the effects of pHCa and log10ECEC.
- Published
- 2004
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30. One-Dimensional Capacitance Behavior of Electrolytes in a Nanopore
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Tang, Y. W., Chan, K. Y., and Szalai, I.
- Abstract
One-dimensional capacitor behavior is reported for electrolytes confined in a nanopore. The electrical behavior of a 0.1 M electrolyte confined in a nanopore is studied by equilibrium and nonequilibrium molecular dynamics simulations. For an electrolyte in a nanopore with a radius of 4.5 Å, capacitance character is exhibited at low frequencies. A unique feature of the maximum conductivity at a resonance frequency corresponds to RLC equivalent circuit behavior.
- Published
- 2003
31. Water-in-Oil Microemulsion Synthesis of Platinum−Ruthenium Nanoparticles, Their Characterization and Electrocatalytic Properties
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Zhang, X. and Chan, K.-Y.
- Abstract
Mixed platinum−ruthenium nanoparticles are prepared by water-in-oil reverse microemulsions of water/Triton X-100/propanol-2/cyclohexane. Nanoparticles formed in the microemulsions are characterized by transmission electron microscopy (TEM), electron diffraction (ED), X-ray diffractometry (XRD), energy-dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). TEM results show a narrow distribution of Pt−Ru nanoparticles. A homogeneous alloy structure in the bimetallic nanoparticles is indicated by XRD analysis and ED analysis. The composition of the Pt−Ru nanoparticles can be easily controlled by the relative concentration of Pt and Ru in the initial precursor solution. The composition that was in the Pt−Ru nano-alloy is found to be the same as that in the original precursor solution. XPS analysis reveals the presence of Pt and Ru metal as well as some oxide of ruthenium. The effect of precursor concentration on microemulsion drop size was investigated by photo correlation spectroscopy (PCS) measurement. The size of Pt−Ru nanoparticles depends on the concentration of precursor in the aqueous phase. At low precursor concentration, the final particle size is about 2.5 nm and appears to be limited by nucleation. At high precursor concentration, the final particle size is about 4.5 nm and appears to be limited by the collisions and mixing with thousands of hydrazine droplets. The Pt−Ru nanoparticles supported on a carbon electrode possessed high dispersion and high catalytic activity for methanol oxidation at room temperature.
- Published
- 2003
32. New polycyclic aromatic hydrocarbon dopants for red organic electroluminescent devices
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Mi, B. X., Gao, Z. Q., Liu, M. W., Chan, K. Y., Kwong, H. L., Wong, N. B., Lee, C. S., Hung, L. S., and Lee, S. T.
- Abstract
Two new anthracene derivatives with red emission have been synthesized. The materials were characterized with photoluminescence spectroscopy, and showed emission peaking at over 600 nm. Organic light-emitting devices were fabricated by using these derivatives as dopants. The devices have a maximum efficiency of 0.6 cd A
−1 and an emission peak at 617 nm. The results of color tuning and fluorescent yield enhancement for anthracene derivatives are presented.- Published
- 2002
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33. Sodicity v. yield decline functions for a Vertisol (Grey Vertosol) under border check and raised bed irrigation
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McKenzie, D. C., Bernardi, A. L., Chan, K. Y., Nicol, H. I., Banks, L. W., and Rose, K. L.
- Abstract
The grain yields of 2 soybean crops and a canola crop were related to topsoil and subsoil properties that are known to affect soil aggregate stability in water. A broad range of soil conditions was produced by applying gypsum and lime at various rates to a Vertisol that was naturally sodic throughout the soil profile. The observations were made under both border check and raised bed irrigation. Soil factors that influence dispersibility and crop growth were considered as part of a stepwise regression analysis. For the 2 soybean crops under border check irrigation, surface exchangeable sodium percentage (ESP) explained 72 and 63%, respectively, of the grain yield variation. For the canola crop that followed, a combination of pH, ESP and electrical conductivity (in that order) explained 75% of the variation in grain yield. Grain yields for the 3 crops declined as the soil became more sodic, particularly on the flat border check area. For soybeans (flat area), the critical values of ESP at which surface sodicity caused a 50% yield decline (ESP50) were strongly influenced by the post-planting climatic conditions. When there was heavy rain just after germination of the soybean seedlings, the ESP50 value was 8.6. The more sodic areas developed a thick crust that impeded seedling emergence. However, in the following year, when conditions remained dry after planting, the ESP50 value was 10.7. Under bed irrigation, the influence of ESP on yield was only minor after the first year of cropping. There was evidence of soil structure improvement from salt that was deposited in the beds via the irrigation water. Subsoil chemical properties that affect structural stability had more of an influence on crop yield under beds than under the flat areas.
Additional keywords: soybean, canola, gypsum, lime, dispersion, crusting, waterlogging, controlled traffic. - Published
- 2002
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34. Diffusivity and Conductivity of a Solvent Primitive Model Electrolyte in a Nanopore by Equilibrium and Nonequilibrium Molecular Dynamics Simulations
- Author
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Tang, Y. W., Szalai, I., and Chan, K.-Y.
- Abstract
Equilibrium and nonequilibrium molecular dynamics simulations are performed to calculate the diffusion coefficient and electric conductivity of ions in a 0.1 M concentration solution confined in neutral cylindrical pores. The applied model is a solvent primitive model (SPM) in which both ions and solvent molecules are soft core spheres and the polar nature of the solvent is represented implicitly as a background with a given dielectric constant. The simulations are carried out in an isokinetic ensemble, and the system, responsing to an applied electric field, is maintained at constant temperature by a Gaussian thermostat. From equilibrium molecular dynamics, diffusion coefficients of ions and solvent decrease with decreasing pore radius or increasing packing fraction of solvent particles. The conductivity determined by nonequilibrium molecular dynamics shows a similar trend, but the pore-size dependence of conductivity does not have a local maximum as was found in the restricted primitive model in which solvent spheres are absent. Using the Nernst−Einstein relation, the ionic conductivity is also calculated from the equilibrium diffusion coefficient and compared with the conductivity obtained from nonequilibrium simulations. The comparison shows that the Nernst−Einsten relation is not valid only at low solvent packing and in very small pores.
- Published
- 2001
35. Soil organic matter in rainfed cropping systems of the Australian cereal belt
- Author
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Dalal, R. C. and Chan, K. Y.
- Abstract
The Australian cereal belt stretches as an arc from north-eastern Australia to south-western Australia (24˚S40˚S and 125˚E147˚E), with mean annual temperatures from 14˚C (temperate) to 26˚C (subtropical), and with annual rainfall ranging from 250 mm to 1500 mm. The predominant soil types of the cereal belt include Chromosols, Kandosols, Sodosols, and Vertosols, with significant areas of Ferrosols, Kurosols, Podosols, and Dermosols, covering approximately 20 Mha of arable cropping and 21 Mha of ley pastures. Cultivation and cropping has led to a substantial loss of soil organic matter (SOM) from the Australian cereal belt; the long-term SOM loss often exceeds 60% from the top 00.1 m depth after 50 years of cereal cropping. Loss of labile components of SOM such as sand-size or particulate SOM, microbial biomass, and mineralisable nitrogen has been even higher, thus resulting in greater loss in soil productivity than that assessed from the loss of total SOM alone. Since SOM is heterogeneous in nature, the significance and functions of its various components are ambiguous. It is essential that the relationship between levels of total SOM or its identif iable components and the most affected soil properties be established and then quantif ied before the concentrations or amounts of SOM and/or its components can be used as a performance indicator. There is also a need for experimentally verifiable soil organic C pools in modelling the dynamics and management of SOM. Furthermore, the interaction of environmental pollutants added to soil, soil microbial biodiversity, and SOM is poorly understood and therefore requires further study. Biophysically appropriate and cost-effective management practices for cereal cropping lands are required for restoring and maintaining organic matter for sustainable agriculture and restoration of degraded lands. The additional benefit of SOM restoration will be an increase in the long-term greenhouse C sink, which has the potentialto reduce greenhouse emissions by about 50 Mt CO2 equivalents/year over a 20-year period, although current improved agricultural practices can only sequester an estimated 23% of the potential soil C sink.
soil carbon loss, soil types, greenhouse effects, cultural practices, ley pastures, crops, soil quality, sustainability. - Published
- 2001
36. Restoring soil fertility of degraded hardsetting soils in semi-arid areas with different pastures
- Author
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Chan, K. Y., Bowman, A. M., Smith, W., and Ashley, R.
- Abstract
To evaluate the effectiveness of a pasture phase in restoring soil fertility, changes in concentration of organic carbon, physical and chemical properties of degraded hardsetting red soils (Alfisols) were assessed at 3 sites in the semi-arid central western region of New South Wales 3&endash;4 years after conversion to different pastures. The pasture species included an annual grass, ryegrass (Lolium rigidum cv. Wimmera), an annual legume, barrel medic (Medicago truncatulata cv. Sephi) as well as a perennial grass, Consol lovegrass (Eragrostis curvula), and a perennial legume, lucerne (Medicago sativa cv. Trifecta). Significant differences in concentration of organic carbon in soils were found only in the top 0&endash;2.5 cm even after 3&endash;4 years under perennial pastures. The concentration of organic carbon under annual grass pasture did not differ from that in the fallow. Corresponding to the organic carbon concentrations, significant changes in water-stable aggregation (detectable to 20 cm depth) and hydraulic properties (up to a 5-fold difference in sorptivity, namely 0.29 mm/h 0.5 under fallow to 1.42 mm/h 0.5 under lucerne) were observed under perennial pastures when compared with that of the fallow. Of the 2 perennial pastures, Consol lovegrass and lucerne were both effective in promoting soil friability as well as water-stable aggregation. However, lucerne increased mineralisable nitrogen more than Consol lovegrass (by up to 4.6 times more, equivalent to 11.6 mg/kg in the 0&endash;10-cm layer). Our results highlight the potential benefits of perennial pastures in maintaining the quality of the fragile hardsetting soils in the low rainfall areas. However, due to the slow rate and the restricted depth of improvement (0&endash;2.5 cm), apart from incorporation of a pasture phase in the cropping system, soil management that maintains soil organic matter level and soil structure, namely reduced tillage and stubble retention, should also be adopted. These findings should be relevant to the management of the hardsetting soils that occupy 12% of the land area of Australia, particularly those in the lower rainfall areas.
available nitrogen, Eragrostis curvula, friabi lity, Medicago sativa, soil structure. - Published
- 2001
37. Equation of State for Nonpolar, Polar, Chain, and Associating Fluids Based on the Dipolar Yukawa Potential
- Author
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Liu, Z.-P., Li, Y.-G., and Chan, K.-Y.
- Abstract
An equation of state (EOS) based on Yukawa and dipolar Yukawa potentials is presented. It is extended to chainlike and associating fluids in the framework of statistical associating fluid theory (SAFT). The EOS is applied to 42 pure real fluids (including nonpolar, polar, and associating fluids) and has a good description of saturated pressures and coexistence curves for these fluids, except very near to the critical point. The parameters for each fluid are regressed from experimental data. Some comparisons among this work, the original SAFT, and the Lennard-Jones (LJ)-based SAFT are carried out. The performance for real polar fluids is also compared between the dipolar Yukawa fluids (DYF) and the Stockmayer fluids (STMF).
- Published
- 2001
38. OXIDIZIBLE ORGANIC CARBON FRACTIONS AND SOIL QUALITY CHANGES IN AN OXIC PALEUSTALF UNDER DIFFERENT PASTURE LEYS
- Author
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Chan, K. Y., Bowman, A., and Oates, A.
- Abstract
To compare the effectiveness of different pasture species in restoring soil quality, changes in concentration and quality of soil organic carbon (C) were measured in the surface 10 cm of an Oxic Paleustalf (red earth) in the semiarid area of New South Wales, Australia, at the end of 4 years under lucerne (Medicago sativa cv. Trifecta), Consol lovegrass (Eragrostis curvula), and barrel medic (Medicago truncutulata cv sephi). Before the investigation, the soil had been degraded by 50 years of cropping. Soil samples were analyzed for water stable aggregation, mineralizable N, and C by three procedures: Total carbon (C) by dry combustion, oxidizible C by potassium permanganate, and oxidizible C by potassium dichromate/sulphuric acid with varying concentrations of acid.
- Published
- 2001
39. Examining prognostic factors and patterns of failure in nasopharyngeal carcinoma following concomitant radiotherapy and chemotherapy: impact on future clinical trials
- Author
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Cheng, S. H., Yen, K. L., Jian, J. J., Tsai, S. Y., Chu, N. M., Leu, S. Y., Chan, K. Y., Tan, T. D., Cheng, J. C., and Hsieh, C. Y.
- Published
- 2001
- Full Text
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40. Fetal programming of appetite and obesity
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Breier, B. H., Vickers, M. H., Ikenasio, B. A., Chan, K. Y., and Wong, W. P.
- Published
- 2001
- Full Text
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41. Comparison of different mixing rules for prediction of density and residual internal energy of binary and ternary Lennard-Jones mixtures
- Author
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Chen, J., Mi, J. G., and Chan, K. Y.
- Published
- 2001
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42. Platinum nanoparticles spontaneously formed on HOPG
- Author
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Shen, P., Chi, N., Chan, K. Y., and Phillips, D. L.
- Published
- 2001
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43. The impact of long-term rotation, tillage and stubble management on lupin (Lupinus angustifolius) productivity
- Author
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Heenan, D. P., Taylor, A. C., Chan, K. Y., McGhie, W. J., Collins, D., and Lill, W. J.
- Published
- 2000
- Full Text
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44. Quantification of bacterial adhesion forces using atomic force microscopy (AFM)
- Author
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Fang, H. H., Chan, K. Y., and Xu, L. C.
- Published
- 2000
- Full Text
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45. Long-term survival of nasopharyngeal carcinoma following concomitant radiotherapy and chemotherapy
- Author
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Cheng, S. H., Jian, J. Jer-Min, Tsai, S. Y., Yen, K. L., Chu, N. M., Chan, K. Y., Tan, T. D., Cheng, J. C., Leu, S. Y., and Hsieh, C. Y.
- Published
- 2000
- Full Text
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46. Microbial-induced soil aggregate stability under different crop rotations
- Author
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Chan, K. Y. and Heenan, D. P.
- Abstract
Abstract: Changes in the quantity and quality of soil organic carbon, and their effect on soil aggregate stability as a result of growing different crops in rotation with wheat, were investigated on a red earth (Oxic Paleustalf) in Wagga Wagga, New South Wales, Australia. After two cycles of the 1 : 1 rotation, while the total organic carbon in the 0–5 cm soil depth was similar (15.1 g/kg), significant differences in water stable aggregation were observed in the order: wheat/lupin=wheat/barley >wheat/canola>wheat/field pea. Using a selective extraction technique, significant differences in the quality (composition) of the soil organic carbon were detected in the soils from the different rotations. Soil from the lupin rotation had the highest salt- and acid-extractable carbon whereas that from the barley rotation had the highest level of hot-water-extractable carbon and microbial biomass carbon. Rather than total carbon or other extractable fractions, the observed differences in aggregate stability were only significantly (P<0.05) related to microbial biomass carbon, which made up only 1.3–1.7% of the total carbon pool. Multiple linear regression analysis indicated that with the exception of salt-extractable carbon, inclusion of any other of the less labile fractions failed to improve the correlation relationship. The labile nature of the microbial biomass carbon therefore accounted for the transient existence of the differences in aggregate stability under different rotation crops. The latter was found to be transient and disappeared at the end of the subsequent wheat crop.
- Published
- 1999
- Full Text
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47. Lime‐induced loss of soil organic carbon and effect on aggregate stability
- Author
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Chan, K. Y. and Heenan, D. P.
- Abstract
We investigated the decline in soil organic C on an Oxic Paleustalf (red earth) as a result of lime application (1.5 t CaCO3ha−1) in New South Wales, Australia and determined how loss of organic C was related to soil aggregate stability changes. Organic C lost as a result of liming was mainly (up to 84% of total loss) in the form of light fraction (specific gravity <1.8) bound to macroaggregates. With liming, a given level of aggregate stability was achieved at a lower soil organic C level in limed soil (e.g., total C level for a 50% aggregate stability was 13.0 and 17.8 g kg−1for limed and unlimed soils, respectively). Increased aggregate stability in limed soils suggested formation of new bonding involved Ca bridges.
- Published
- 1999
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48. Multiple limit cycles and global stability in predator-prey model
- Author
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Yuquan, Wang, Zhujun, Jing, and Chan, K. Y.
- Abstract
A predator-prey system is investigated for the global stability and existences of limit cycle and at least two cycles by using qualitative analysis and the idea of Poincaré-Bendixson Theoy.
- Published
- 1999
- Full Text
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49. Identification of basic metabolites of 4-[4-(p-chlo- robenzoyl)piperidino]-4'-fluorobutyrophenone, an experimental neuroleptic agent.
- Author
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Fusaro, G A, Garteiz, D A, Chan, K Y, and Leeson, G A
- Abstract
Two metabolites of 4-[4-(p-(chlorobenzoyl)piperidino]-4'-fluorobutyrophenone (RMI 9901) as well as unchanged drug, have been identified in the urine of rats following oral administration of the drug. Analysis of basic urine extracts by combined gas chromatography-mass spectrometry was employed for metabolite identification. N-dealkylation appears to be a major metabolic pathway and results in formation of 4-(p-chlorobenzoyl)piperidine (I). Subsequent oxidation of this metabolite results in the formation of 4-(p-chlorobenzoyl)-2-piperidone (II), and represents rather unusual metabolic pathway for compounds of this chemical class.
- Published
- 1976
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50. Decrease in the activity of the drug-metabolizing enzymes of rat liver following the administration of tilorone hydrochloride.
- Author
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Leeson, G A, Biedenbach, S A, Chan, K Y, Gibson, J P, and Wright, G J
- Abstract
Tilorone hydrochloride, 2,7-bias(2-(diethylamino)ethoxy(fluoren-9-one dihydrochloride, has been studied to determine its effect on the drug-metabolizing enzymes of the liver of male Charles River CD strain rats. Single and multiple doses of tilorone-HCl, 100 mg/kg/day po, were used. Most experiments were performed 24 hr after the last dose, except for a study 5 hr after dosing, and those in which the duration of effects of tilorone hydrochloride were determined. The hexobarbital sleeping time was prolonged after both single doses and four doses of tilorone hydrochloride. The 4-dose regimen prolonged the zoxazolamine paralysis time but the single dose did not. A decrease in microsomal protein was observed after the single- and 4-dose regimens but not after 21 daily doses of tilorone-HCl. Cytochrome P-450 content of microsomes was decreased by the single doses, 100 and 250 mg/kg po, and by 4 and 21 doses of 100 mg/kg/day po. Activities of aminopyrine demethylase and hexobarbital oxidase also were decreased by the above regimens, but the activity of hexobarbital oxidase was affected more markedly. Electron micrographs of rat liver, after treatment with tilorone-HCl, 100 mg/kg/day for 21 days, revealed many membranous structures in the form of whorls.
- Published
- 1976
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