Melt rheology and mechanical properties in linear low density polyethylene (LLDPE)/low density polyethylene (LDPE), LLDPE/high density polyethylene (HDPE), and HDPE/LDPE blends were investigated. All three blends were miscible in the melt, but the LLDPE/LDPE and HDPE/LDPE blends exibiled two crystallization and melting temperatures, indicating that those blends phase separated upon cooling from the melt. The melt strength of the blends increased with increasing molecular weight of the LDPE that was used. The mechanical properties of the LLDPE/LDPE blend were higher than claculated from a simple rule of mixtures, whiele those of the LLDPE/HDPE blend conformed to the rule of mixtures, but the properties of HDPE/LDPE were less than the rule of mixtures prediction.

The rheology and morphology of four sets of binary blends of polyethylene synthesized with metallocene catalysis (metallocene polyethylene: MCPE) with polyolefins prepared using Ziegler‐Natta catalysts have been investigated. The blend systems are MCPE with high density polyethylene (MCPE‐HDPE), polypropylene (MCPE‐PP), poly(propylene‐co‐ethylene) (MCPE‐CoPP), and poly(propylene‐co‐ethylene‐co‐1‐butylene) (MCPE‐TerPP). Cole‐Cole plots [storage melt viscosity (η′) versus loss melt viscosity (η″)], plots of the dynamic storage modulus (G′) versus the dynamic loss modulus (G″), and plots of the log melt viscosity (η*, η′, and η″) versus blend compositions were constructed. The morphology of the blends after microtoming and etching was studied. The phase morphology of MCPE‐HDPE appeared homogeneous, whereas the other three blends were heterogeneous. Rheological and morphological investigations indicated that the MCPE‐HDPE blend was miscible, but the other three blends were immiscible in the melt as well as in the solid state. These observations can be rationalized in terms of the similarity of the chemical structures of the polyolefins.

ABSTRACT:The thermal, viscoelastic, and mechanical behaviors of three binary blends of ethylene 1-octene copolymer (EOC) regarding the melt index and density, one component made by Ziegler-Natta (FA and RF in abbreviation of the commercial name) and the other by metallocene catalysts (FM, EN and PL in abbreviation of the commercial name), have been investigated to understand molecular mechanism of the blends. Thermal studies reveal that the two constituents in the three blends exclude one another during crystallization, implying a phase separation. Viscoelastic properties show a single ␤ or ␥ transition in all the compositions, suggesting a miscibility in the amorphous region. The tensile modulus, yield stress, maximum strength at break, and elongation at break follow the rule of mixtures if the comonomer content does not differ too much. Otherwise, the modulus and yield stress are negatively deviated, whereas elongation at break is positively deviated from the weight-average value. The tensile properties of film at yield and break in the machine direction is increased with an addition of FM in the FA ϩ FM blend. Although all three blends form separate crystals in the crystalline state, a correlation exists between the mechanical properties and the density of EOCs.

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Corticobasal degeneration might be associated with aberrant manual approach behavior. Although our results do not support the working memory hypothesis, frontal dysfunction might have led to a loss of voluntary control of ontologically primitive propensity to move the forelimb in the direction to which one attends.

ABSTRACT. Epidemiology of Eimeria species in poultry flocks is important to increase the effectiveness of vaccinations and prophylactic strategies on chicken farms. In this study, fecal samples from 356 chicken farms were collected randomly and examined for the prevalence of Eimeria species. Through microscopic examination, it was determined that 78.7% of the tested farms were positive in Eimeriainfection. Seven Eimeria species were detected in all the positive farms by PCR amplification of the internal transcribed spacer 1 (ITS-1) region with species-specific primers. E. acervulina and E. tenella were the most prevalent, followed by E. brunetti and E. praecox (87.5, 62.5, 59.3, and 37.5% of the farms, respectively). Each of E. maxima, E. mitis, and E. necatrix was identified in 31.3% of the farms. Individual positive fecal samples contained multiple Eimeria species (mean=3.4). Since E. maxima is known to generate antigenic variants, cross-immunity was investigated for four isolates of E. maxima from the poultry farms in different regions of Korea. The extent of cross-protection varied from 54.3 to 100% against the heterologous isolates. The results obtained from this large-scale survey will be a useful reference for controlling coccidiosis in the poultry industry.

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Oxindole alkaloids in the paraherquamide/marcfortine family exhibit broad-spectrum anthelmintic activity that includes drug-resistant strains of nematodes. Paraherquamide (PHQ), 2-deoxoparaherquamide (2DPHQ), and close structural analogs of these compounds rapidly induce flaccid paralysis in parasitic nematodes in vitro, without affecting adenosine triphosphate (ATP) levels. The mechanism of action of this anthelmintic class was investigated using muscle tension and microelectrode recording techniques in isolated body wall segments of Ascaris suum. None of the compounds altered A. suum muscle tension or membrane potential. However, PHQ blocked (when applied before) or reversed (when applied after) depolarizing contractions induced by acetylcholine (ACh) and the nicotinic agonists levamisole and morantel. These effects were mimicked by the nicotinic ganglionic blocker mecamylamine, suggesting that the anthelmintic activity of PHQ and marcfortines is due to blockade of cholinergic neuromuscular transmission. The effects of these compounds were also examined on subtypes of human nicotinic ACh receptors expressed in mammalian cells with a Ca2+ flux assay. 2DPHQ blocked nicotinic stimulation of cells expressing alpha3 ganglionic (IC50 approximately 9 microm) and muscle-type (IC50 approximately 3 microm) nicotinic cholinergic receptors, but was inactive at 100 microm vs. the alpha7 CNS subtype. PHQ anthelmintics are nicotinic cholinergic antagonists in both nematodes and mammals, and this mechanism appears to underlie both their efficacy and toxicity.