1,012 research outputs found

    Plankton Studies V. The Plankton of the Illinois River, 1894-1899. Part II. Constituent Organisms and Their Seasonal Distribution

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    This paper gives the results of a statistical study of a series of quantitative plankton collections made in the channel of the Illinois River near Havana, Ill., at the Illinois Biological Station, in 1894-1899. The environmental conditions and the volumetric results of this investigation have been given in Part I. (Kofoid, '03), published in Volume VI. of this Bulletin.published or submitted for publicationis peer reviewe

    Combining Ability in Forage Sorghum Hybrids

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    Two cross-classified hybrid forage sorghum [Sorghum bicolor (L.) Moench] experiments were conducted at Mead, NE: Experiment 1 (3 females x 8 males), in 1973-75, and Experiment 2 (13 females x 2 males), in 1974-75. Data were collected on plant height, days to bloom, forage yield, percent dry matter (DM), percent protein, and in vitro dry matter disappearance (IVDMD) in both experiments and percent Brix in Experiment 1. Differences among hybrids averaged over females or over males were significant for each trait in one parental group or the other in each test except IVDMD in Test 1 and DM in Test 2. All traits were signficant for hybrid entries in both tests. Interactions of traits with years were often significant and, with the few degrees of freedom in F-tests, contributed to the nonsignificance of yield among females in Test 1 and males in Test 2. Genetic ratios indicated that general combining ability often was relatively high for days to bloom, height, DM, and forage yield; and was of some importance for IVDMD and Brix. Specific combining ability was most important for protein. Correlations among traits indicated that high forage yield often was positively correlated with tall height and late maturity; was negatively correlated with DM, protein, and IVDMD; and was not associated with Brix

    Genetic analysis of feed quality and seed weight of sorghum inbred lines and hybrids using analytical methods and NIRS

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    Eight lines of grain sorghum and their F1 hybrids were evaluated for contents of crude protein (CP), fat (FAT), and starch (STA); protein digestibility (PD); and in vitro dry matter disappearance (IVDMD). The effect of seed weight (SW) on these traits and the potential use of near infrared reflectance spectroscopy (NIRS) to predict them also were investigated. The male lines included three normal-seeded lines (TX2737, TX435, and P954063) and two largeseeded lines (PL-1 and Eastin1). The female lines included commonU.S. seed parent lines (Wheatland, Redlan, and SA3042). The lines and their hybrids were grown under dryland conditions at Kansas State University experiment fields in Ashland and Belleville, Kansas, in 1999. The experiments were conducted using a randomized complete block design with four replications at each location. The effect of genotype was significant for all measured traits. The male parent lines were highly variable and expressed high levels of genetic variation in combining ability for CP, PD, STA, and SW. The female parents were genetically more uniform; however, significant general combining ability effects were noted for PD and SW. Significant negative correlations were noted between CP and STA and between SW and STA. Significant positive correlations were found between CP and SW and between FAT and IVDMD. Crude protein content was predicted accurately by NIRS. Fat content and IVDMD could not be predicted by NIRS. The NIRS equations based on ground samples were more accurate than those based on whole-seed samples

    Constitutive modeling of advanced thermoset composites with application to sheet forming processes

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaves 164-169).Advanced thermoset composites are an important class of materials employed primarily in aerospace applications that consist of a thermoset polymer resin matrix that is reinforced by systematically arranged, continuous graphite fibers. Composite sheet forming, or thermoforming, is a process where flat sheets of composite layups are heated and formed into desired part shapes. Due to the complex nature of composite material response, successful composite sheet forming processes (that avoid defects such as fiber wrinkling) are traditionally the result of costly trial-and-error methods. The main objective of this research is to develop constitutive material models that can be utilized for modeling thermoset composite response during sheet forming processes. A continuum model has been developed that accounts for temperature and rate dependencies and allows solid finite element modeling that tracks material response on the microscopic level, including fiber wrinkling. The second model is a simplified, transversely isotropic elastic-plastic model that can be used together with a finite element model which employs structural (shell) elements to monitor macroscopic material response in a less computationally-intensive manner. The constitutive parameters of both models were optimized to match observed material behavior from unidirectional tensile and bending tests conducted on the composite at various temperatures and strain rates. The models were tested against a series of three-point bending verification tests that were conducted on quasi-isotropic composite layups at various rates and temperatures. Also included is an investigation of various finite element approaches that can be employed using these models to simulate(cont.) forming processes. The completed continuum model satisfactorily captures most composite behavior, with the exception of transverse shear flow behavior along the fibers. The model, developed using the assumption of isotropic flow response, requires greater refinement in order to more accurately capture composite behavior. The completed transversely isotropic elastic-plastic model satisfactorily captures all modes of composite behavior observed during experimentation. The simplified nature of this model, however, limits it from accurately describing behaviors such as fiber wrinkling during deformation.by Jamie N. Kofoid.S.M

    Genetic Analysis of Kafirins and Their Phenotypic Correlations with Feed Quality Traits, In Vitro Digestibility, and Seed Weight in Grain Sorghum

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    Twenty-three entries of grain sorghum (Sorghum bicolor (L.) Moench), including eight inbred lines (five males and three females) and 15 hybrids, were evaluated to determine the proportion of γ, αII, and β-αI-kafirins and their association with contents of crude protein, fat, and starch; protein digestibility; in vitro dry matter disappearance; and seed weight. The male lines included three normal-seeded lines (TX2737, TX435, and P954063) and two large-seeded lines (Eastin1 and PL-1). Female lines consisted of three common U.S. seed parent lines (Wheatland, Redlan, and SA3042). The lines and their hybrids were grown under dryland conditions at two locations in Kansas using a randomized complete block design. The effects of genotype, location, and males were significant for all kafirins. Wide variations in composition and general combining ability (GCA) for kafirin content were noted among parent lines and hybrids, with TX2737, Eastin1, and PL1 having the largest GCA values for γ (1.37), αII (1.99), and β-αI (2.57), respectively. Correlations among kafirins ranged from –0.89 to 0, whereas those of kafirins with feed quality traits, digestibility, and seed weight ranged from –0.45 to 0.48

    Genetic Analysis of Kafirins and Their Phenotypic Correlations with Feed Quality Traits, In Vitro Digestibility, and Seed Weight in Grain Sorghum

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    Twenty-three entries of grain sorghum (Sorghum bicolor (L.) Moench), including eight inbred lines (five males and three females) and 15 hybrids, were evaluated to determine the proportion of γ, αII, and β-αI-kafirins and their association with contents of crude protein, fat, and starch; protein digestibility; in vitro dry matter disappearance; and seed weight. The male lines included three normal-seeded lines (TX2737, TX435, and P954063) and two large-seeded lines (Eastin1 and PL-1). Female lines consisted of three common U.S. seed parent lines (Wheatland, Redlan, and SA3042). The lines and their hybrids were grown under dryland conditions at two locations in Kansas using a randomized complete block design. The effects of genotype, location, and males were significant for all kafirins. Wide variations in composition and general combining ability (GCA) for kafirin content were noted among parent lines and hybrids, with TX2737, Eastin1, and PL1 having the largest GCA values for γ (1.37), αII (1.99), and β-αI (2.57), respectively. Correlations among kafirins ranged from –0.89 to 0, whereas those of kafirins with feed quality traits, digestibility, and seed weight ranged from –0.45 to 0.48
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