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Jennifer L. Specker - One of the best experts on this subject based on the ideXlab platform.

  • Metamorphosis in summer flounder: manipulation of rearing salinity to synchronize Settling Behavior, growth and development
    Aquaculture, 2004
    Co-Authors: Steven Gavlik, Jennifer L. Specker
    Abstract:

    Abstract In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and Settling Behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to size grading. Our goal was to use an environmental salinity change as a cue to synchronize Settling Behavior and produce a larger, more uniformly sized cohort of juvenile summer flounder. Early metamorphic flounder were exposed to either a 5-day fluctuating (30–20–30–20–30 ppt; “Flux”) or a single (30–20 ppt; “20 ppt”) drop in rearing salinity. A control (continuous 30 ppt) was used for comparison. Average values for a peak settlement interval (PSI; defined as the interval beginning on the day by which the first 20% had settled until the day 80% had settled) were not affected by salinity manipulation, though the 20-ppt treatment did significantly increase percent settled per day by 54 dah. Average fish size was increased by the 20-ppt treatment (19.3±0.5 mm), but not the flux treatment (17.2±0.4 mm), compared to the control (17.6±0.5 mm). Developmental stage was significantly increased in the 20-ppt treatment (3.2±0.1) in comparison to the Flux (2.9±0.1), but not the control (3.1±0.1). However, the 20-ppt treatment reduced variance in development. To confirm the positive effects of the 20-ppt treatment, a second experiment was performed. A single salinity drop (“20 ppt”), a previously successful ([Gavlik, S., Albino, M., Specker, J.L., 2002. Metamorphosis in summer flounder: Manipulation of thyoid status to synchronize Settling Behavior, growth, and development. Aquaculture 203 (3-4), 359-373]thyroid hormone manipulation treatment (“TH”) and a combination of the two (“TH+20 ppt”) were compared to a control (continuous 30 ppt, no thyroid manipulation). The mean PSI was significantly reduced by both TH (7±1 days) and TH+20 ppt (8±0 days) treatments, compared to the control (11±1 days). The PSI for the 20-ppt treatment (9±0 days) was not significantly different than the control. The percent flounder settled per day was significantly increased by 20 ppt salinity and significantly modified (decreased, then increased) by TH manipulation. Flounder exposed to 20-ppt salinity were both larger (20 ppt: 18.6±0.3 mm; TH+20 ppt: 18.3±0.3 mm) and more developmentally advanced (20 ppt: 3.1±0.04; TH+20 ppt: 3.2±0.03) than flounder in 30 ppt (TH: 17.8±0.3 mm/3.1±0.3; Control: 17.9±0.3 mm/3.0±0.05). Finally, 20-ppt treatment reduced variance in development, while TH treatment reduced variance in both growth and development. Percent survival was unaffected by treatment in both experiments. In summary, a decrease in rearing salinity, from 30 to 20 ppt, increased growth, Settling Behavior and development of metamorphosing summer flounder. A decrease in rearing salinity, in combination with a TH manipulation, should result in larger, more uniformly sized flounder cohorts. We expect this synchronization will reduce the cannibalism and labor costs associated with size grading of cultured, metamorphosing summer flounder.

  • Metamorphosis in summer flounder: manipulation of thyroid status to synchronize Settling Behavior, growth, and development
    Aquaculture, 2001
    Co-Authors: Steven Gavlik, Melissa Albino, Jennifer L. Specker
    Abstract:

    In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and Settling Behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to grading. Our goal was to use thyroid hormone manipulation to synchronize Settling Behavior and produce a uniformly sized cohort of juvenile summer flounder. Premetamorphic flounder were treated with exogenous thiourea (TU, 30 ppt, an inhibitor of thyroxine (T4) synthesis). Following removal of TU, metamorphosing flounder were exposed to either exogenous T4 (T4-Na salt, 100 ppb, dissolved in DMSO) or DMSO only. A control (no TU, then DMSO only, when appropriate) was used for comparison. Settling Behavior in the control was prolonged, with the Peak Settlement Interval (defined as the interval beginning on the day the first 20% settled until the day 80% had settled) requiring 9 days, and a Settling rate of 4.1±0.2 fish/day. Settling Behavior was synchronized by thyroid hormone treatment. The Peak Settlement Interval was reduced (5 days) and Settling rate increased (8.5±0.6 fish/day) by TU treatment. Treatment with TU followed by T4 further reduced the Peak Settlement Interval (3 days) and increased Settling rate (11.2±0.6 fish/day). Development rate (DR) and growth rate (GR) were reduced by TU treatment, but following TU with T4 treatment restored DR and GR to control levels. However, TU treatment eliminated the larger, potentially cannibalistic juveniles found in control tanks. Both treatments reduced variance in GR, whereas only TU-T4 reduced variance in DR. Percent survival was unaffected by treatment. In aquaculture, the effective synchronization of Settling Behavior by thyroid hormone manipulations should reduce the labor costs associated with grading. We recommend a treatment regime that could aid in the production of more uniform cohorts of juvenile summer flounder.

Steven Gavlik - One of the best experts on this subject based on the ideXlab platform.

  • Metamorphosis in summer flounder: manipulation of rearing salinity to synchronize Settling Behavior, growth and development
    Aquaculture, 2004
    Co-Authors: Steven Gavlik, Jennifer L. Specker
    Abstract:

    Abstract In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and Settling Behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to size grading. Our goal was to use an environmental salinity change as a cue to synchronize Settling Behavior and produce a larger, more uniformly sized cohort of juvenile summer flounder. Early metamorphic flounder were exposed to either a 5-day fluctuating (30–20–30–20–30 ppt; “Flux”) or a single (30–20 ppt; “20 ppt”) drop in rearing salinity. A control (continuous 30 ppt) was used for comparison. Average values for a peak settlement interval (PSI; defined as the interval beginning on the day by which the first 20% had settled until the day 80% had settled) were not affected by salinity manipulation, though the 20-ppt treatment did significantly increase percent settled per day by 54 dah. Average fish size was increased by the 20-ppt treatment (19.3±0.5 mm), but not the flux treatment (17.2±0.4 mm), compared to the control (17.6±0.5 mm). Developmental stage was significantly increased in the 20-ppt treatment (3.2±0.1) in comparison to the Flux (2.9±0.1), but not the control (3.1±0.1). However, the 20-ppt treatment reduced variance in development. To confirm the positive effects of the 20-ppt treatment, a second experiment was performed. A single salinity drop (“20 ppt”), a previously successful ([Gavlik, S., Albino, M., Specker, J.L., 2002. Metamorphosis in summer flounder: Manipulation of thyoid status to synchronize Settling Behavior, growth, and development. Aquaculture 203 (3-4), 359-373]thyroid hormone manipulation treatment (“TH”) and a combination of the two (“TH+20 ppt”) were compared to a control (continuous 30 ppt, no thyroid manipulation). The mean PSI was significantly reduced by both TH (7±1 days) and TH+20 ppt (8±0 days) treatments, compared to the control (11±1 days). The PSI for the 20-ppt treatment (9±0 days) was not significantly different than the control. The percent flounder settled per day was significantly increased by 20 ppt salinity and significantly modified (decreased, then increased) by TH manipulation. Flounder exposed to 20-ppt salinity were both larger (20 ppt: 18.6±0.3 mm; TH+20 ppt: 18.3±0.3 mm) and more developmentally advanced (20 ppt: 3.1±0.04; TH+20 ppt: 3.2±0.03) than flounder in 30 ppt (TH: 17.8±0.3 mm/3.1±0.3; Control: 17.9±0.3 mm/3.0±0.05). Finally, 20-ppt treatment reduced variance in development, while TH treatment reduced variance in both growth and development. Percent survival was unaffected by treatment in both experiments. In summary, a decrease in rearing salinity, from 30 to 20 ppt, increased growth, Settling Behavior and development of metamorphosing summer flounder. A decrease in rearing salinity, in combination with a TH manipulation, should result in larger, more uniformly sized flounder cohorts. We expect this synchronization will reduce the cannibalism and labor costs associated with size grading of cultured, metamorphosing summer flounder.

  • Metamorphosis in summer flounder: manipulation of thyroid status to synchronize Settling Behavior, growth, and development
    Aquaculture, 2001
    Co-Authors: Steven Gavlik, Melissa Albino, Jennifer L. Specker
    Abstract:

    In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and Settling Behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to grading. Our goal was to use thyroid hormone manipulation to synchronize Settling Behavior and produce a uniformly sized cohort of juvenile summer flounder. Premetamorphic flounder were treated with exogenous thiourea (TU, 30 ppt, an inhibitor of thyroxine (T4) synthesis). Following removal of TU, metamorphosing flounder were exposed to either exogenous T4 (T4-Na salt, 100 ppb, dissolved in DMSO) or DMSO only. A control (no TU, then DMSO only, when appropriate) was used for comparison. Settling Behavior in the control was prolonged, with the Peak Settlement Interval (defined as the interval beginning on the day the first 20% settled until the day 80% had settled) requiring 9 days, and a Settling rate of 4.1±0.2 fish/day. Settling Behavior was synchronized by thyroid hormone treatment. The Peak Settlement Interval was reduced (5 days) and Settling rate increased (8.5±0.6 fish/day) by TU treatment. Treatment with TU followed by T4 further reduced the Peak Settlement Interval (3 days) and increased Settling rate (11.2±0.6 fish/day). Development rate (DR) and growth rate (GR) were reduced by TU treatment, but following TU with T4 treatment restored DR and GR to control levels. However, TU treatment eliminated the larger, potentially cannibalistic juveniles found in control tanks. Both treatments reduced variance in GR, whereas only TU-T4 reduced variance in DR. Percent survival was unaffected by treatment. In aquaculture, the effective synchronization of Settling Behavior by thyroid hormone manipulations should reduce the labor costs associated with grading. We recommend a treatment regime that could aid in the production of more uniform cohorts of juvenile summer flounder.

Melissa Albino - One of the best experts on this subject based on the ideXlab platform.

  • Metamorphosis in summer flounder: manipulation of thyroid status to synchronize Settling Behavior, growth, and development
    Aquaculture, 2001
    Co-Authors: Steven Gavlik, Melissa Albino, Jennifer L. Specker
    Abstract:

    In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and Settling Behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to grading. Our goal was to use thyroid hormone manipulation to synchronize Settling Behavior and produce a uniformly sized cohort of juvenile summer flounder. Premetamorphic flounder were treated with exogenous thiourea (TU, 30 ppt, an inhibitor of thyroxine (T4) synthesis). Following removal of TU, metamorphosing flounder were exposed to either exogenous T4 (T4-Na salt, 100 ppb, dissolved in DMSO) or DMSO only. A control (no TU, then DMSO only, when appropriate) was used for comparison. Settling Behavior in the control was prolonged, with the Peak Settlement Interval (defined as the interval beginning on the day the first 20% settled until the day 80% had settled) requiring 9 days, and a Settling rate of 4.1±0.2 fish/day. Settling Behavior was synchronized by thyroid hormone treatment. The Peak Settlement Interval was reduced (5 days) and Settling rate increased (8.5±0.6 fish/day) by TU treatment. Treatment with TU followed by T4 further reduced the Peak Settlement Interval (3 days) and increased Settling rate (11.2±0.6 fish/day). Development rate (DR) and growth rate (GR) were reduced by TU treatment, but following TU with T4 treatment restored DR and GR to control levels. However, TU treatment eliminated the larger, potentially cannibalistic juveniles found in control tanks. Both treatments reduced variance in GR, whereas only TU-T4 reduced variance in DR. Percent survival was unaffected by treatment. In aquaculture, the effective synchronization of Settling Behavior by thyroid hormone manipulations should reduce the labor costs associated with grading. We recommend a treatment regime that could aid in the production of more uniform cohorts of juvenile summer flounder.

J. F. Morris - One of the best experts on this subject based on the ideXlab platform.

  • dynamic and steady shear properties of reversibly cross linked guar solutions and their effects on particle Settling Behavior
    THE XV INTERNATIONAL CONGRESS ON RHEOLOGY: The Society of Rheology 80th Annual#N#Meeting, 2008
    Co-Authors: N. Tonmukayakul, J. E. Bryant, Malcolm Seth Talbot, J. F. Morris
    Abstract:

    Rheological properties of guar of molecular weight MW = 2.2×106 reversibly cross‐linked with borate ion at different cross‐linker concentrations were investigated using small amplitude oscillatory sweep (SAOS) and steady shear at 25 °C and atmospheric pressure. Polymer concentration was fixed at 0.003 g/ml above the overlap concentration (C* = 5×10−4 g/ml). Four borate ion concentrations of 31, 62, 93 and 125 ppm were used. A transparent Couette cell was used to study the Settling Behavior of particles under simple shear. Dynamic Settling (i.e. under shear) results reveal that both shear thinning and elasticity of the suspending fluid affect Settling rate. For a lightly cross‐linked sample, Settling rate increases with increasing imposed shear rate; the Settling rate decreases for a highly cross‐linked sample. Full‐field images of the Couette during Settling show the development of a non‐homogeneous particulate structure during sedimentation in a highly cross‐linked sample. Extended particulate structures...

  • Dynamic and Steady Shear Properties of Reversibly Cross‐Linked Guar Solutions and Their Effects on Particle Settling Behavior
    AIP Conference Proceedings, 2008
    Co-Authors: N. Tonmukayakul, J. E. Bryant, Malcolm Seth Talbot, J. F. Morris
    Abstract:

    Rheological properties of guar of molecular weight MW = 2.2×106 reversibly cross‐linked with borate ion at different cross‐linker concentrations were investigated using small amplitude oscillatory sweep (SAOS) and steady shear at 25 °C and atmospheric pressure. Polymer concentration was fixed at 0.003 g/ml above the overlap concentration (C* = 5×10−4 g/ml). Four borate ion concentrations of 31, 62, 93 and 125 ppm were used. A transparent Couette cell was used to study the Settling Behavior of particles under simple shear. Dynamic Settling (i.e. under shear) results reveal that both shear thinning and elasticity of the suspending fluid affect Settling rate. For a lightly cross‐linked sample, Settling rate increases with increasing imposed shear rate; the Settling rate decreases for a highly cross‐linked sample. Full‐field images of the Couette during Settling show the development of a non‐homogeneous particulate structure during sedimentation in a highly cross‐linked sample. Extended particulate structures...

Fred Growcock - One of the best experts on this subject based on the ideXlab platform.

  • Settling Behavior of particles in fiber-containing Herschel Bulkley fluid
    Powder Technology, 2016
    Co-Authors: Rida Elgaddafi, Ramadan Ahmed, Fred Growcock
    Abstract:

    Abstract Fiber-containing, or fibrous, fluids are used in the petroleum industry to improve well-bore cleaning. Field studies indicate that fiber-containing sweep fluids can clean horizontal and highly inclined wells of drill cuttings very effectively. Fibrous fluids are also utilized in fracturing operations to place proppant particles within induced fractures. Efficiency of solid particle transport by these fluids depends on their ability to hinder Settling of the dispersed particles. This article presents results of experimental and theoretical investigations conducted on Settling Behavior of spherical particles in Herschel-Bulkley fluids containing chemically inert monofilament fibers 10 mm in length and 0.1 mm diameter at concentrations ranging up to 0.08% by weight. A model has been developed to predict particle Settling velocity under transient and steady state Settling conditions. Experiments were carried out with spherical glass particles 2 to 8 mm in diameter in a 100-mm fully transparent cylinder of sufficient length (2 m) to establish terminal Settling conditions. Wall effects were minimized by maintaining a ratio of particle diameter to cylinder internal diameter (d p /d cyl ) no greater than 0.08. To vary the rheological properties of the fluid, xanthan gum suspensions with three different polymer concentrations were used as base fluids. A moving digital video camera was used to track Settling particles. The camera records were used to determine instantaneous Settling velocity of each particle as a function of time. In fibrous suspensions, resistance to Settling is provided by both the base fluid (viscous drag) and the fibers (fiber drag). Fiber drag arises from mechanical and hydrodynamic interferences. Measurements of the terminal velocity of particles in the base fluids were used to compute viscous drag, while the terminal velocity data in the fibrous fluids was utilized to determine total drag (i.e. fiber drag plus viscous drag). Analysis of the data resulted in the development of an empirical correlation for the “fiber drag coefficient,” which varies with particle Reynolds number, fiber concentration and fluid Behavior index. With this information, a model has been developed that can be used to predict Settling velocity of spherical particles in suspensions of the prescribed fiber in Herschel-Bulkley fluids.

  • Settling Behavior of spherical particles in fiber-containing drilling fluids
    Journal of Petroleum Science and Engineering, 2012
    Co-Authors: Rida Elgaddafi, Ramadan Ahmed, Matthew George, Fred Growcock
    Abstract:

    Abstract Fiber-containing fluids are utilized in many industrial applications. In the petroleum industry, fiber suspensions are used to transport rock cuttings from the bottom of the hole to the surface. Moreover, fibrous fluids are applied in fracturing operations to transport proppant particles to the fractured space. Solids transport performance of these fluids largely depends on the Settling Behavior of suspended particles. This article presents results of experimental and theoretical investigations conducted on the Settling Behavior of 2 to 8 mm spherical particles in fiber-containing fluids. Experiments were carried out in a 2-m long and 100-mm diameter transparent cylinder. Both Newtonian and non-Newtonian fluids were tested. A moving digital camera system was used to track a particle while it settled. The camera records were used to determine the Settling velocity of each particle as a function of time. Fiber concentration was varied from 0.00% to 0.08% by weight. When a particle settles in the fibrous fluid, it experiences fiber drag in addition to conventional hydrodynamic resistance, i.e. viscous drag. Measured terminal velocity was used to compute the viscous component of the total drag. Subsequently, applying the momentum balance, the fiber drag component acting on the particle was determined from the total drag. Results show that the fiber drag is a function of the particle's projected area, Settling velocity, fiber drag coefficient, and density difference between the fluid and particle. Using experimental data, a semi-empirical model was developed to predict terminal Settling velocity of a particle in fiber-containing fluids. The correlation is valid for both Newtonian and non-Newtonian base fluids that have low concentrations of fully dispersed fibers with a length and diameter of 10 mm and 100 μm, respectively.