Development of a Model for Describing Accumulation of Color and Subsequent Destruction by Ozone in a Freshwater Recirculating Aquaculture System   总被引：2，自引：0，他引：2  

J. Michael  Christensen  Kelly A.  Rusch Ronald E  Malone 《Journal of the World Aquaculture Society》2000,31(2):167-174

The purpose of this study was to develop a mathematical model to assist in the determination of design numbers for color destruction by ozone as a function of feed rate. A mass balance model was developed that takes into account methods of introduction and removal of color, including removal by ozone. Because direct measurement of color mass or concentration is difficult, a representative unit was developed during this study called the color mass equivalent (CME). The CME represents a direct measurement of absorbance at 436 nm, which is a unitless measurement, multiplied by the system volume. The CME is directly proportional to the true concentration of color causing compounds at that wavelength. Once the model was developed, two studies were run to test the model. A 1,500-L recirculating fish system was set up with a 57-L bead filter and six 1-L fluidized sand beds. Approximately 45 kg of channel catfish Ictalurus puncfatus were placed in the system and fed 0.25 kg of 32% protein feed per day (0.55% body wt.). Once the system reached stable conditions, the system was flushed with clean water and samples were taken to estimate the accumulation rate of color in the system. After 5 wk, an ozone unit was activated and samples were taken to determine the destruction rate for color. Once an accumulation rate had been determined, a second study was performed to corroborate this value. The same ozone unit was installed on a 5,000-L recirculating fish system being fed 0.49 kg per day with a 171-L bead filter. Samples were taken to determine the destruction rate for color. The accumulation rate for color was 12.6 CME/kg feed and the destruction rates were 1.7 CME/g O₃ in the first study and 0.82 CMWg O₃ in the second study. This calculates to a range of 7 to 15 g O₃/kg feed to remove the color produced by the feed.  相似文献   

Microalgal production using a hydraulically integrated serial turbidostat algal reactor (HISTAR): a conceptual model     

Kelly A. Rusch  Ronald F. Malone 《Aquacultural Engineering》1998,18(4):251-264

A hydraulically integrated, serial turbidostat algal reactor (HISTAR) was mathematically modeled and developed for the mass production of microalgae. HISTAR, which hydraulically links precisely controlled turbidostats with continuous-flow stirred-tank reactors (CFSTRs) into a single production technology, was conceptualized emphasizing contaminant mitigation at the design stage to maintain system stability. This paper discusses the conceptual basis for the development of HISTAR and presents a theoretical overview of the CFSTRs. Mathematical modeling, using first-order algal growth kinetics combined with CFSTR reactor kinetics, was used to investigate the effects of system dilution rate, D_s; net algal specific growth rate, U_a; number of reactors, N; input algal biomass, X_i; and contaminant concentration, C_n, on algal productivity, as well as local dilution rate, D_n, on suspended contaminant washout. The simulation results allowed the determination of preliminary design ranges for prototype development.  相似文献   

A serological investigation of caseous lymphadenitis in four flocks of sheep     

Malone FE  Fee SA  Kamp EM  King DC  Baird GJ  O'Reilly KM  Murdock FE 《Irish veterinary journal》2006,59(1):19-21

A double antibody sandwich ELISA developed by ID-DLO, Lelystad to detect Corynebacterium pseudotuberculosis infection was used on 329 sheep from four pedigree Suffolk flocks in which clinical cases of caseous lymphadenitis (CLA) had occurred. At subsequent necropsy, typical CLA lesions were seen in 133 sheep, and the diagnosis was confirmed on culture. Lesions were most commonly seen in lungs (n = 46), parotid lymph nodes (n = 44), prescapular lymph nodes (n = 38) and mediastinal lymph nodes (n = 31). The sensitivity of the ELISA test for detecting culture-positive sheep was 0.88, while the specificity of the test was 0.55. The antibody ELISA detected 87.5 per cent of sheep that had CLA lesions restricted to internal organs only. It was concluded that the ELISA test has a valuable role in detecting sheep with both clinical and subclinical CLA.  相似文献   

Common ragweed (Ambrosia artemisiifolia) dry matter allocation and partitioning under different nitrogen and density levels     

ROBERT LESKOVŠEK  AVISHEK DATTA  STEVAN Z. KNEZEVIC  ANDREJ SIMONČIČ 《Weed Biology and Management》2012,12(2):98-108

Dry matter partitioning and allocation is a major determinant of plant growth and its competitiveness. Common ragweed (Ambrosia artemisiifolia) is a troublesome agronomic weed species and it is also a major health concern in Europe and many other countries because of its rapid spreading and production of allergenic pollen. A field experiment was conducted in 2009 to determine the effect of nitrogen fertilizer levels (0, 100, and 200 kg ha^?1) and plant density levels (1.3, 6.6, and 13.2 plants per m²) on the leaf, stem dry matter partitioning, and dry matter allocation of ragweed. With an increasing density, the stem partitioning coefficient increased, whereas the leaf partitioning coefficient decreased. The addition of nitrogen had a limited effect on the leaf and stem dry matter partitioning. The root dry matter production decreased with an increasing density and was not influenced by the addition of nitrogen. Under intraspecific competition, ragweed exhibited a stronger above‐ground competition intensity than below the ground, which resulted in a greater root : shoot ratio, compared to the low‐density stands. The level of nitrogen influenced the vertical leaf, stem, and total dry matter distribution, with a greater allocation to the top stratum of the plants, thus increasing their competition for light. The biomass allocation of ragweed to the roots in response to the nitrogen supply exhibited a low plasticity, compared to the shoots, which displayed a high plasticity. The results of this study suggested that, under intraspecific conditions and with an increasing nitrogen supply, ragweed would be more competitive in above‐ground resource acquisition.  相似文献   

RZWQM simulated effects of crop rotation, tillage, and controlled drainage on crop yield and nitrate-N loss in drain flow   总被引：1，自引：0，他引：1  

L. Ma  R.W. Malone  D.B. Jaynes  S.A. Saseendran  J.C. Ascough II 《Geoderma》2007,140(3):260-271

Accurate simulation of agricultural management effects on N loss in tile drainage is vitally important for understanding hypoxia in the Gulf of Mexico. An experimental study was initiated in 1978 at Nashua, Iowa of the USA to study long-term effects of tillage, crop rotation, and N management practices on subsurface drainage flow and associated N losses. The Root Zone Water Quality Model (RZWQM) was applied to evaluate various management effects in several previous studies. In this study, the simulation results were further analyzed for management effects (tillage, crop rotation, and controlled drainage) on crop production and N loss in drain flow. RZWQM simulated the observed increase in N concentration in drain flow with increasing tillage intensity from NT (no-till) to RT (ridge till) to CP (chisel plow) and to MP (moldboard plow). It also adequately simulated tillage effects on yearly drain flow and yearly N loss in drain flow. However, the model failed to simulate lower corn and soybean yields under NT than under MP, CP, and RT. On the other hand, RZWQM adequately simulated lower yearly drain flow and lower flow-weighted N concentration in drain flow under CS (corn-soybean) and SC (soybean-corn) than under CC (continuous corn). The model adequately simulated higher corn yield under CS and SC than under CC. Applying the newly suggested N management practice for the Midwest of controlled drainage, the model simulated a 30% reduction in drain flow and a 29% decrease in N losses in drain flow under controlled drainage (CD) compared to free drainage (FD). With most of the simulations in reasonably close agreement with observations, we concluded that RZWQM is a promising tool for quantifying the relative effects of tillage, crop rotation, and controlled drainage on N loss in drainage flow. Further improvements on simulated management effects on crop yield and N mineralization are needed, however.  相似文献   

Role of landscape and hydrologic attributes in developing and interpreting yield clusters     

A. Bakhsh  R.S. Kanwar  R.W. Malone 《Geoderma》2007,140(3):235-246

Management of agricultural fields based on yield patterns may help farmers adopt environmentally friendly farming practices. Our objective was to investigate landscape and hydrologic attributes that affect spatial clusters of corn (Zea mays L.)-soybean (Glycine max L.) yields. The study was conducted at Iowa State University's northeastern research center near Nashua, Iowa, from 1993 to 1998. The yield data, normalized for annual climatic variability, were used in cluster and discriminant analysis, and the landscape and hydrologic data were overlain using ArcGIS software. Three clusters of low, medium and high categories were formed using 10 iterations with zero convergence options and satisfying the R², pseudo F-statistic and cubic clustering criteria. The spatial clusters, however, varied greatly over space and time domain for the study period. The map overlay analysis using ArcGIS showed that high yield clusters were affected by soil and lower elevation levels in the below average precipitation year of 1994. The annual normalized subsurface drainage volume, nitrate leaching losses, soil type and topographic attributes of slope, aspect, and curvature were used in stepwise discriminant analysis to identify the variables significantly related to the clusters. Soil and topographic attributes of curvature and aspect contributed significantly in cluster formations for four of the six years at P ≤ 0.15. The results suggest that cluster and discriminant analysis can be useful for identification of soil and topographic attributes affecting corn and soybean yield patterns, which can help in delineation of management zones for site specific management practices.  相似文献   

Mitochondrial heredity: a determinant in the toxic response of maize to the insecticide methomyl     

Koeppe DE  Cox JK  Malone CP 《Science (New York, N.Y.)》1978,201(4362):1227-1229

Mitochondria isolated from etiolated Texas male-sterile (TMS) cytoplasm maize (Zea mays L.) seedlings were adversely affected by methomyl (Lannate, 90 wettable powder), while those isolated from normal-fertile seedlings were not. In a manner analogous to that reported for Bipolaris (Helminthosporium) maydis (race T) toxin, experiments with TMS mitochondria showed that 1 to 3 millimolar methomyl inhibited the state 4 oxidation rate of combined malate and pyruvate while stimulating that of succinate or exogenous reduced nicotinamide adenine dinucleotide. Similar concentrations of methomyl effected an inhibition of phosphorylation, an increase in the percentage of transmittance of light through mitochondrial suspensions, and a decrease in the density of the mitochondrial matrix. Methomyl (15 millimolar) had little effect on the physiological activity or ultrastructure of isolated normal-fertile mitochondria. These observations provide the opportunity to specifically assess the homogeneity, or lack of it, of a cytoplasmic heritable characteristic in a widely divergent group of higher plants.  相似文献   

Deep earthquakes beneath mount st. Helens: evidence for magmatic gas transport?     

Weaver CS  Zollweg JE  Malone SD 《Science (New York, N.Y.)》1983,221(4618):1391-1394

Small-magnitude earthquakes began beneath Mount St. Helens 40 days before the eruption of 20 March 1982. Unlike earlier preeruption seismicity for this volcano, which had been limited to shallow events (less than 3 kilometers), many of these earthquakes were deep (between 5 and 11 kilometers). The location of these preeruptive events at such depth indicates that a larger volume of the volcanic system was affected prior to the 20 March eruption than prior to any of the earlier dome-building eruptions. The depth-time relation between the deep earthquakes and the explosive onset of the eruption is compatible with the upward migration of magmatic gas released from a separate deep reservoir.  相似文献   

Constructing a nitrogen fertilizer recommendation system using a dynamic model: what do farmers want?     

J. U. Smith  A. G. Dailey  M. J. Glendining  N. J. Bradbury  T. M. Addiscott  P. Smith  A. Bide  D. Boothroyd  E. Brown  R. Cartwright  R. Chorley  S. Cook  S. Cousins  S. Draper  M. Dunn  A. Fisher  P. Griffith  C. Hayes  A. Lock  S. Lord  J. Mackay  C. Malone  D. Mitchell  D. Nettleton  D. Nicholls  H. Overman  J. Purslow  A. Scholey  S. Senior  L. Sim  P. Taylor 《Soil Use and Management》1997,13(4):225-228

Abstract. An effective fertilizer recommendation system requires information on seasonal, soil-related and cultural variations in soil mineral nitrogen (N) and nutrient requirements of the crop. This can be provided by dynamic N turnover models, such as listed by Plentinger & Penning De Vries (1996). In this paper, we describe a survey of farmer opinion designed to ascertain what farmers want from such a decision support system. Over 100 farmers were surveyed. Surveyed farmers requested that default values be available for all model inputs. Inputs should be entered both by windows-based menu (for clarity) and tabular format (for speed), have user-selected units, and be fully supported by context-sensitive help. The system should have a hierarchical structure allowing access to fixed parameters, and be compatible with commonly used farm recording packages. Recommendations should be provided both for the field (single and optional application rates), and in tabular format across the whole farm. Simulations should be easily rerun using more recent crop and weather data. Turnover processes underlying recommendations should be illustrated by flow diagrams of flux between pools, pie charts of fertilizer fate, bar charts of movement down the soil profile and graphical plots of changes in N status against time.  相似文献   

CD3 SmIglymphoblastic leukaemia in an outbred domestic guinea pig     

MJ DAY  EK BRIGGS 《Australian veterinary journal》1997,75(3):217-218

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