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Rate Used (rate + used)
Selected AbstractsLeaching of heavy metals and nutrients from calcareous sandy-loam soil receiving municipal solid sewage sludgeJOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2010Mohsen Jalali Abstract Leaching column experiments were conducted to determine the degree of mobility of heavy metals (HMs) and nutrients after the addition of municipal solid sewage sludge (MSS) in a sandy-loam soil. Treatments were (1) soil application of low metal content MSS, (2) soil application of metal-enriched municipal solid sewage sludge (EMSS), and (3) control. The MSS application represented a dose of 200 Mg dry weight (dw) ha,1. Soil columns were incubated at room temperature for 15 d and were irrigated daily with distilled water to make a total of 557,mm. Leachates were collected and analyzed for HMs and nutrients. The Ni and Pb added to soil via MSS and EMSS were found to be leached through the 20,cm columns of calcareous sandy soil although Ni and Pb concentrations in the percolate were small relative to the total amounts of metals applied. Losses of K+ from the EMSS, MSS, and control were 92.5, 82.0, and 52.5,kg ha,1, respectively. Losses of Mg2+ were in the range from 104.4 (control treatment) to 295.2,kg ha,1 (EMSS), while the loss of Ca2+ was in the range from 265.0 (control treatment) to 568.2,kg ha,1 (EMSS). The results showed that the amounts of P leached from EMSS (3.02,kg ha,1) and MSS (2.97,kg,1 ha,1) were significantly larger than those from the control treatment (1.54,kg ha,1). The geochemical code Visual MINTEQ was used to calculate saturation indices. Leaching of P in different treatments was controlled by rate-limited dissolution of hydroxyapatite, ,-tri-Ca phosphate, and octa-Ca phosphate. The results indicate that application of MSS to a sandy soil, at the loading rate used in this study, may pose a risk in terms of groundwater contamination with Ni, Pb, and the studied nutrients. [source] Impact of Copper Sulfate on Plankton in Channel Catfish Nursery PondsJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 1 2009Charles C. Mischke Many fish culturists are interested in applying copper sulfate pentahydrate (CSP) to channel catfish, Ictalurus punctatus, nursery ponds as a prophylactic treatment for trematode infection and proliferative gill disease by killing snails and Dero sp., respectively, before stocking fry. However, copper is an algaecide and may adversely affect phytoplankton and zooplankton populations. We evaluated the effects of prophylactic use of copper sulfate in catfish nursery ponds on water quality and phytoplankton and zooplankton populations. In 2006, treatments of 0 mg/L CSP, 3 mg/L CSP (0.77 mg/L Cu), and 6 mg/L CSP (1.54 mg/L Cu) were randomly assigned to 0.04-ha ponds. In 2007, only treatments of 0 and 3 mg/L CSP were randomly assigned to the 16 ponds. Ponds treated with CSP had significantly higher pH and significantly lower total ammonia concentrations. Treatment of both CSP rates increased total algal concentrations but reduced desirable zooplankton groups for catfish culture. CSP has been shown to be effective in reducing snail populations at the rate used in this study. CSP treatment also appears to be beneficial to the algal bloom, shifting the algal population to green algae and increasing total algal biomass within 1 wk after CSP treatment. Although zooplankton populations were adversely affected, populations of important zooplankton to catfish fry began rebounding 6,12 d after CSP treatment. Therefore, if CSP is used to treat catfish fry ponds of similar water composition used in this study, fry should not be stocked for about 2 wk after CSP application to allow time for the desirable zooplankton densities to begin increasing. [source] Heating rate effects on the TL characteristics of hot filament CVD diamond filmPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2010E. Cruz-Zaragoza Abstract The thermoluminescence (TL) glow curve of polycrystalline chemically vapor deposited (CVD) diamond is strongly dependent on the heating rate used. In the present work, we report results about the heating rate effects on a 500,µm hot filament (HF) CVD diamond film grown on silicon substrate using a precursor gas mixture composition of CH4(5,sccm),CO(10,sccm),H2(400,sccm). The irradiations were performed with 60Co source. The TL measurements were carried out at different heating rates in the 2,30,K/s range. As the heating rate increases, the maximum TL peak intensity decreases and shifts to higher temperature. The shift was from 578 to 669,K for heating rates of 2 and 30,K/s, respectively. The kinetics parameter and its dependence on the heating rate were evaluated using the Chen's peak shape method and a computerized glow curve deconvolution (CGCD) method. [source] Morphology in Immiscible Polymer Blends During Solidification of an Amorphous Dispersed Phase under ShearingTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2002Yves Deyrail Abstract Solidification under shear of dispersed polycarbonate (PC) fibers in copolymer polyethylene-methyl acrylate matrix (EMA) was investigated using a hot optical shear device. First, the deformation of PC droplets and its modeling under isothermal conditions were studied for comprehension purposes. Overall agreement with literature models was found and the main influence of the viscosity ratio has been stressed. Second, the morphology control through dynamic quenching was experimented. It consists of solidifying the amorphous PC dispersed phase under shear flow. Break-up times of PC fibers were taken into account. Shear rate and quenching-time balance was demonstrated. Thus, during dynamic solidification, a fibrillar morphology could be obtained through rapid quenching. Long quenching times allow nodular morphology, whose size depends on the shear rate used. PC rods can be obtained by adjusting the shear rate during dynamic quenching. La solidification sous cisaillement du polycarbonate (PC) dispersé dans une matrice copolymère éthylène-acétate de vinyle (EMA) a été suivie à l'aide d'un microscope et d'une platine de cisaillement chauffante. Dans un premier temps la déformation isotherme de billes de PC pour différentes températures a été étudiée, ainsi que sa modélisation. Une bonne corrélation avec les modèles issus de la littérature a été obtenue. L'importance du rapport des viscosités a été ainsi soulignée. Dans un second temps le contrôle de la morphologie par le procédé de « refroidissement dynamique » a été expérimenté. Celui-ci consiste à solidifier le PC sous cisaillement pendant le refroidissement. Les temps de rupture des fibres de PC ont été considérés et l'importance du couple gradient de cisaillement-temps de refroidissement sur le contrôle de la morphologie a été mis en évidence. Pendant la solidification, un refroidissement rapide permet d'obtenir une morphologie fibrillaire. [source] Is radiation damage dependent on the dose rate used during macromolecular crystallography data collection?ACTA CRYSTALLOGRAPHICA SECTION D, Issue 2 2006Hanna-Kirsti S. Leiros This paper focuses on the radiation-damage effects when applying the same total X-ray dose to protein crystals at different dose rates. These experiments have been performed on both a selenomethionated protein and on bovine trypsin using dose rates that span nearly two orders of magnitude. The results show no clear dose-rate effect on the global indicators of radiation damage, but a small measurable dose-rate effect could be found when studying specific radiation damage. It is hypothesized that this observed dose-rate effect relates to differences in the steady-state free-radical concentration. [source] RUNOFF NUTRIENT AND FECAL COLIFORM CONTENT FROM CATTLE MANURE APPLICATION TO FESCUE PLOTS,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2000D. R. Edwards ABSTRACT: Grazed pastures represent a potential source of non-point pollution. In comparison to other nonpoint sources (e.g., row-cropped lands), relatively little information exists regarding possible magnitudes of pollution from grazed pasture; how that pollution is affected by weather, soil, management and other variables; and how the pollution can be minimized. The objective of this study was to assess how the quality of runoff from fescue plots is influenced by duration of cattle manure application (4,12 weeks) and manure application strategy (none, weekly application of 1.4 kg/plot, and monthly application at 5.6 kg/plot). Additional analyses were performed to relate runoff quality to the timing of sample collection. The study was conducted at the University of Kentucky Maine Chance Agricultural Experiment Station north of Lexington. Plots (2.4 m wide by 6.1 m long) were constructed and established in Kentucky 31 fescue (Festuca arundinacea Schreb.) to represent pasture. Grazing was simulated by application of beef cattle manure to the plots. Runoff was generated by applying simulated rainfall approximately 4, S and 12 weeks following initiation of manure application. Runoff samples were collected and analyzed according to standard methods for nitrogen (N), phosphorus (P) and fecal coliforms (FC). Runoff concentrations of N and P from manure-treated plots were low and generally not consistently different from control plot concentrations or related to manure application strategy. Runoff FC concentrations from manure-treated plots were higher than from control plot concentrations. Runoff concentrations of ammonia N, total Kjeldahl N, ortho-P and FC decreased approximately exponentially in response to increasing time of sample collection. These findings suggest that manure deposition on well-managed pasture at the rates used in this study might have a negligible impact on nutrient content of runoff. [source] Evaluation of residual values of different fertilisers at various rates used in phosphorus recapitalisation of an acid tropical soilJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2006Esther W Gikonyo Abstract The success of ,phosphorus (P) recapitalisation' depends on the changes in residual value (RV) over time. RVs of triple superphosphate (TSP), Gafsa phosphate rock (GPR) and Christmas Island phosphate rock (CIPR) were determined with and without manure bimonthly for 14 months. RV was calculated as the amount of previously applied fertiliser required to produce yield X divided by the amount of freshly applied TSP required to produce the same yield. Dry matter yield (DMY) response curves were curvilinear, with maximum DMY (11 t ha,1) occurring between 150 and 200 kg P ha,1 at 6 months and declining with time to 2,4 t ha,1 (14 months). Manure/fertiliser combinations increased DMY for CIPR but depressed DMY for TSP and GPR in all harvests except the first one. This can be attributed to nutrient imbalance caused by high P levels. RVs declined with time for fertilisers alone from 100,140% to 10,20% (14 months), while for fertiliser/manure combinations they declined from 110,180% to 10,20% (14 months). Increasing P rates from 100 to 300 kg P ha,1 resulted in the depression of initial RVs (100,140%) to 20,60% and later to 10,20% (14 months). Therefore P recapitalisation was not beneficial and hence annual P application would be recommended at 100,150 kg P ha,1. The phosphate rocks could effectively substitute for TSP. Copyright © 2006 Society of Chemical Industry [source] A thermally stimulated depolarization current study of polymers in the glass transition regionPOLYMER ENGINEERING & SCIENCE, Issue 1 2001Joseph S. Sedita The low-frequency dielectric properties of a number of polymers, composites and blends have been studied using a thermally stimulated depolarization current (TSDC) apparatus that was designed and constructed in-house. The TSDC technique can be used to determine the glass transition of a polymer sample. This TSDC glass transition temperature has been shown to be very similar to that obtained from differential scanning calorimetry (DSC). The actual difference between these two values depends on the heating rates used with each technique, however. TSDC data can also be combined with AC dielectric data to produce a data set, which possesses a very wide frequency range. Finally, individual TSDC relaxation peaks can be fit with the Williams-Walts distribution function to obtain an estimate of their distributions. This is especially useful when studying polymer blends, but could also be utilized in the study of other systems. [source] Sensitivity analysis of the moments of the profit on an Income Protection PolicyAPPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 1 2010Isabel Maria Cordeiro Abstract The main purpose of this paper is to perform a sensitivity analysis where we quantify and analyse the effects on the mean of the profit on an Income Protection policy and two risk measures of changing the values of the transition intensities. All the calculations carried out are based on a multiple state model for Income Protection proposed in Continuous Mortality Investigation Committee (Continuous Mortality Investigation Reports 1991; 12). Within this model, we derive a formula for the mean of the profit, which enables to evaluate it more efficiently. In order to calculate the two risk measures we use the numerical algorithms for the calculation of the moments of the profit proposed by Waters (Insurance: Mathematics and Economics 1990; 9:101,113). We carry out the sensitivity analysis considering two different situations: in the first situation, we update the premium rates used to calculate the moments of the profit, according to the changes in the values of the transition intensities; in the second one, we do not update the premium rates. Both analyses are of practical interest to insurance companies selling Income Protection policies. Copyright © 2009 John Wiley & Sons, Ltd. [source] Discount Rates in Disarray: Evidence on Flawed Goodwill Impairment TestingAUSTRALIAN ACCOUNTING REVIEW, Issue 4 2009Gerry Gallery Carlin and Finch, this issue, compare goodwill impairment discount rates used by a sample of large Australian firms with ,independently' generated discount rates. Their objective is to empirically determine whether managers opportunistically select goodwill discount rates subsequent to the 2005 introduction of International Financial Reporting Standards (IFRS) in Australia. This is a worthwhile objective given that IFRS introduced an impairment regime, and within this regime, discount rate selection plays a key role in goodwill valuation decisions. It is also timely to consider the goodwill valuation issue. Following the recent downturn in the economy, there is a high probability that many firms will be forced to write down impaired goodwill arising from boom period acquisitions. Hence, evidence of bias in rate selection is likely to be of major concern to investors, policymakers and corporate regulators. Carlin and Finch claim their findings provide evidence of such bias. In this commentary I review the validity of their claims. [source] | |||||||||||||