Significant Hybrid Effects Research Articles

EFFECTS OF STOCKING RATE ON THE PERFORMANCE OF TWO HYBRIDS OF COMMERCIAL BROILERS IN THE HUMID TROPICS

The effects of four stocking rates (0.070, 0.093, 0.116 and 0.140m2/ bird) on the performance of two hybrids of commercial broilers were investigated. There were significant hybrid effects on initial and final body weights (P< 0.01) and on feed effici­ency (P <0.05) but not on average daily gain and feed consumption and mortality. Stocking effects which were not signi­ficant for initial body weight, feed efficiency and mortality were highly significant for final body weight, average daily gain and feed consumption, (P < 0.01). There were significant interactions bet­ween hybrid and stocking rate for average daily gain (P <0.01) and mortality (P < 0.05). It is suggested that in the humid tropics, the stocking rates of 0.116 and 0.140m2/ bird would be appropriate for rearing broilers. The results of the study also show­ed that different hybrids do vary on space requirements in respect • of certain produc­tion traits.

Partial diallel and potential of super sweet corn inbred lines bt 2 to obtain hybrids

ABSTRACT The aims of this study were to determine the potential of S4 super sweet corn inbred lines for hybrid synthesis, identify the predominant types of gene action and correlations among different traits, significant for breeding programs. The 81 hybrids obtained from a partial diallel 9x9 and three checks were evaluated. A complete randomized block design, with three replicates, and two sowing seasons was used. We could notice significant hybrid effects, general combining ability (GCA) of GI and GII groups and specific combining ability (SCA) in relation to evaluated traits, highlighting the existence of hybrids with superior performance and the expression of additive and non-additive effects. The inbred lines: L1, L3, L6 and L9 (GI) and L1’, L7’ and L9’ (GII) showed the best GCA and SCA estimates, being present in the nine selected hybrids with superior and competitive performance in relation to the checks. The estimated correlations indicate that, for a breeding program aiming to increase grain productivity, evaluating, at least, the dehusked ears, prioritizing genotypes with larger ear diameters and longer ear lengths is important.

Electronic and Magnetic Properties of Ni-Doped Zinc-Blende ZnO: A First-Principles Study.

The electronic structure, band structure, density of state, and magnetic properties of Ni-doped zinc-blende (ZB) ZnO are studied by using the first-principles method based on the spin-polarized density-functional theory. The calculated results show that Ni atoms can induce a stable ferromagnetic (FM) ground state in Ni-doped ZB ZnO. The magnetic moments mainly originate from the unpaired Ni 3d orbitals, and the O 2p orbitals contribute a little to the magnetic moments. The magnetic moment of a supercell including a single Ni atom is 0.79 μB. The electronic structure shows that Ni-doped ZB ZnO is a half-metallic FM material. The strong spin-orbit coupling appears near the Fermi level and shows obvious asymmetry for spin-up and spin-down density of state, which indicates a significant hybrid effects from the Ni 3d and O 2p states. However, the coupling of the anti-ferromagnetic (AFM) state show metallic characteristic, the spin-up and spin-down energy levels pass through the Fermi surface. The magnetic moment of a single Ni atom is 0.74 μB. Moreover, the results show that the Ni 3d and O 2p states have a strong p-d hybridization effect near the Fermi level and obtain a high stability. The above theoretical results demonstrate that Ni-doped zinc blende ZnO can be considered as a potential half-metal FM material and dilute magnetic semiconductors.

Hybrid effects in the fracture toughness of polyvinyl butyral-based nanocomposites

Hybrid polyvinyl butyral (PVB) nanocomposite films comprising surface-treated carbon nanotubes (CNT-COOH) and nanoclays (NC) were tested for their “trouser-leg” fracture toughness in comparison to the values of the respective CNT and NC parent composites and to that of the pristine PVB film. Relative to the fracture toughness of the pristine PVB, the parent composites PVB/CNT-COOH-0.2% and PVB/NC-2% and the PVB/CNT-COOH-0.2%/NC-2% hybrid exhibited 105, 118, and 181% improvements, respectively. These were both impressive fracture toughness improvements and a significant hybrid effect – the latter being only slightly lower than the nominal maximum effect of 223% based on the combined improvements of the parent composites. Part of the samples was tested qualitatively by ball impact test of ballistic glass samples with relevant films. Among these samples, the hybrid film presented the best result. A significant linear correlation between fracture surface energy and roughness values was taken to reflect a fracture resistance mechanism of crack front slowdown by its interactions with nanoparticles.

Study on the electronic and optical properties of La-, Ce- and Nd-doped SnO2

To study the influence of rare earth element doping on the electronics structure and properties of SnO2, the lattice parameters, band structures, density of states, electron density differences and optical properties are investigated by density functional theory based on the plane wave pseudopotential method. The calculated results show that the bond lengths change the most due to La doping and the least for Nd, which indicates that the lattice distortion caused by rare-earth-doped SnO2 is related to the covalent radius of the doping atom. The band gap of SnO2 reduces the most due to La doping, but it is found that spin-up levels are in the forbidden band for Nd doping. The results show that Nd-doped SnO2 is half-metal material due to the existence of spin-up f electrons, and significant hybrid effects are induced by Nd 4f and O 2p states. The charge density difference shows that rare earth doping causes redistribution of the electrons of SnO2, and the metal property enhances. La atoms lose the most electrons and Nd atoms lose the least, which is consistent with the calculated results of band gaps. The calculated results of optical properties show that the imaginary part of the dielectric function has a red shift and the optical anisotropy of SnO2 is not strong, which indicates that the SnO2 crystal may have a preferred orientation along [0 0 1].

Co掺杂闪锌矿ZnO的磁性和光学性质

The band structure,density of state,magnetic and optical properties of Co doped zinc blende Zn O were systematically studied by using the first-principles based on the spin polarized density functional theory. The calculated results show that the ground state of Co doped zinc blende Zn O is antiferromagnetic and shows metal characteristics,while the ferromagnetic state shows the half-metallic characteristics. For the ferromagnetic coupling state,strong spin-orbit coupling appears near the Fermi level and shows no obvious asymmetry for up and down spins,which indicates a significant hybrid effects from Co 3d and O 2p states. The magnetic moments are mainly contributed by unpaired electrons in Co 3d and neighbor O 2p orbital and are correlated to the doped site of Co atoms.In addition,the calculated results of optical properties show that Co doped zinc blende Zn O has a strong absorptive capacity at the visible light,and the absorption peaks have red shift in the high energy region. The theoretical calculated results demonstrate that Co-doped zinc blende Zn O may become excellent magneto-optic materials.

Flexural strength of bidirectional hybrid epoxy composites reinforced by E glass and T700S carbon fibres

A study on the flexural properties of bidirectional hybrid epoxy composites reinforced by E glass and T700S carbon fibres in inter-ply configurations is presented in this paper. Test specimens are made by hand lay-up and their flexural properties are obtained by three point bend test in accordance with ASTM D790-07. For comparison, the flexural behaviour is also modelled numerically using finite element analysis (FEA), and analytically using the Classic Lamination Theory (CLT). It is shown from the results that in general, good agreement is found between the experimental data and the model predictions. The flexural strength decreases when partial laminas from a carbon/epoxy laminate are replaced by glass/epoxy laminas. No significant hybrid effects for the flexural strength are found from the experiments. However, simulation studies show that hybridisation can potentially improve the flexural strength.

Genotypic variation and heritability of growth and adaptive traits, and adaptation of young poplar hybrids at northern margins of natural distribution of Populus nigra in Europe

The study aimed at estimating the adaptation, genotypic variation and heritability of growth and other adaptive traits of poplar hybrids at the northern margins of the natural distribution of Populus nigra in Europe, and to compare with the performance of native aspen hybrids from the middle of their geographic ranges. A set of 105 clones of poplar hybrids originated from crossing Populus deltoides, P. nigra, Populus trichocarpa, Populus maximowiczii and Populus balsamifera and aspen hybrids obtained from crossing Populus tremula, Populus tremuloides and Populus alba were studied in two juvenile clonal trials in Lithuania. ANOVA revealed a significant hybrid effect for growth traits and bud flush phenology. P. maximowiczii × trichocarpa had the highest height increment followed by P. tremuloides × tremula. Most adaptive traits were under strong genetic control, with 0.61–0.94 heritability. Genotypic variation for height increment ranged 19.40–58.10%. Hybrid × site interaction was significant for height growth. The highest plasticity was found in P. balsamifera × trichocarpa and P. nigra, with ecovalences reaching 21.4–24.7%. The low inter-site (B-type) genotypic correlations and significant clone × site interaction found for most growth traits and autumn phenology indicated a presence of genotypic variation in plasticity/response of clones. Negative correlations between autumn leaf shed phenology and tree condition and survival indicate that clones with late growth cessation suffer from adaptation problems. Thus poplar breeding in Northern Europe has to incorporate hardy species from harsher climates of North America to maximize both tree growth and survival to match phenology to local climates.

Flexural and tensile moduli of unidirectional hybrid epoxy composites reinforced by S-2 glass and T700S carbon fibres

A study on the flexural and tensile moduli of S-2 glass and T700S carbon fibre reinforced hybrid epoxy composites in intra-ply configurations is presented in this paper. Finite element analysis (FEA) and Classic Lamination Theory (CLT) were employed to model the flexural behaviour of hybrid composites, which was obtained from the three point bend test in accordance with ASTM: D790-10 at various span-to-depth ratios. The flexural moduli were obtained from the load–displacement curves. The models were validated against the experimental results from a previous study. With the aid of the developed models, the effects of fibre volume fractions, hybrid ratio and span-to-depth ratio were studied. The results show that flexural modulus increases when the span-to-depth ratio is increased from 16 to 32 and becomes stable as the span-to-depth ratio further increases. Since the modulus of glass fibres is much lower than that of carbon fibres, both flexural and tensile moduli decrease with increasing hybrid ratio. From the full carbon/epoxy laminate, when a carbon/epoxy lamina close to the outermost surface of the laminate is replaced by a glass/epoxy lamina, the flexural modulus decreases rapidly. This is due to the maximum tensile and compressive stresses occur at the two faces of the laminate in bending, and the stresses around the mid-plane are close to zero. Tensile modulus decreases with increasing hybrid ratio. Under tension, the stress distribution is determined by the relative difference in the tensile moduli of the carbon/epoxy and glass/epoxy laminas. If the difference is small, tensile modulus versus the hybrid ratio resembles a linear relationship and no significant hybrid effects exist; if the difference is large, a strong non-linear relationship is present and large hybrid effects exist. Simple mathematical formulas are presented for calculation of the flexural and tensile moduli of hybrid composites from the moduli of the carbon/epoxy and glass/epoxy composites, and the hybrid ratio.

Studies of the hybrid effect in mechanical properties of tencel blended ring-, rotor- and air-jet spun yarns

This paper presents a study of hybrid effect on mechanical properties of tencel blended ring-, rotor- and Murata jet spinning yarns. The tensile strength, breaking elongation, flexural rigidity and abrasion resistance of tencel-polyester and tencel-cotton blended yarns are examined and compared with the value predicted using linear and quadratic rule of mixture (ROM). It is observed that there is no significant hybrid effect on abrasion resistance of tencel-polyester mix yarns and tenacity and breaking extension of tencel-cotton mix yarns; hence, a linear ROM is found better in predicting the yarn properties. Further, for all yarn types, there is a significant hybrid effect on tenacity, breaking extension and flexural rigidity of tencel-polyester mixes and flexural rigidity and abrasion resistance of tencel-cotton mixes. A quadratic ROM model suits well for these yarns. Overall, it is found that there is a negative hybrid effect on tenacity and breaking extension whereas there is a positive hybrid effect on flexural rigidity for all the yarn samples irrespective of fibre and yarn type. The abrasion resistance has a mixed trend. Further, tencel-polyester yarns yield more satisfactory results than the tencel-cotton yarns in terms of strength and breaking extension but behave poorly during abrasion test for 200 cycles. Increasing tencel content both in tencel-polyester and tencel-cotton fibre-mix produces a rigid yarn with reduced abrasion resistance.

Study on heterosis of inter-subspecies between indica and japonica rice (Oryza sativa L.) using chromosome segment substitution lines

Heterosis for yield and its component traits between chromosome segments from IR24, anindica variety, and the counterparts from 02428, ajaponica rice, was investigated by using a hybrid F1 population composed of 63 combinations between 02428 and IR24 chromosome segment substitution lines (CSSLs) with the genetic background of Asominori,a japonica variety. Significant differences in heterosis for yield and yield-component traits were observed among the crosses. Analysis of graphical genotyping showed that 14 substituted segments were responsible for yield heterosis. All of them were from all the 12 chromosomes of IR24 except chromosomes 8 and 10. Six segments at the intervals of RFLP markers, such as X132-G1340-R459, X48-C393A, R288-R1854, R2918-X52, X257-C1350 and R367-X189-2-X24-2 on chromosomes 2, 3, 4, 11 and 12 respectively, had very significant heterosis for yield at the level ofP ⩽ 0.005 based ont-test, individually increasing the hybrid yield by more than 35% compared with the control cross “Asominori×02428”. Most of IR24 chromosome segments were found to have no significant hybrid effect for yield and yield-component traits, and one segment located at R2171 on chromosome 6 possessed significant negative effect with 27% of yield decrease. Advantages of using CSSLs in the heterosis studies were discussed and approaches of the partial and genome-wide exploitation of rice heterosis betweenindica andjaponica by molecular marker-assisted selection were then proposed.

Hybrid C/Pet/epoxy composites

Hybrid carbon/PET/epoxy composites were prepared by a wet layup technique and characterized by standard methods of fracture and impact tests. The influence of PET fibre surface treatment with polyfunctional amine on the composite properties has been studied in order to determine the role of the fibre/matrix interface. The state of the fibre/matrix interface has been examined by several techniques, such as SEM, differential scanning calorimetry (DSC) and contact angle measurements. A significant hybrid effect of the PET/aminated fibres on the curing reaction and T g of the epoxy matrix in the composites was established. It is probably due to the reaction between the amine groups of the fibre surface and the epoxy component of the resin, as determined by DSC.