Showing papers by "Pusan National University published in 1986"

Structure and properties of dynamically cured EPDM/PP blends

Abstract: The structure and properties of polyolefin blends of ethylene–propylene–diene terpolymer (EPDM) and polypropylene were studied. Blends were prepared in a laboratory internal mixer where EPDM was cured with PP under shear with dicumyl peroxide (DCP) at different shear conditions (blend–cure). Blends were also prepared for comparison from EPDM which were dynamically cured in the absence of PP and blended later (cure–blend). The effect of DCP concentration, intensity of the shear mixing, and rubber/plastic composition were studied. In blend–cure, the melt viscosity increased with increasing DCP concentration in blends of 75% EPDM and 25% PP, but it decreased with increasing DCP concentration in blends of 75% PP and 25% EPDM. In cure–blend, however, the melt viscosity increased with increasing DCP concentration for all compositions. The melt viscosity decreased with increasing intensity of the shear mixing presumably due to the formation of the smaller segregated microdomain of the crosslinked EPDM gels in both blend–cure and cure–blend materials. The crystallization rate was higher in EPDM/PP blends than in PP homopolymer. The crystallization rates for various blending conditions were also compared.

Flavonoids from the leaves ofRhododendron brachycarpum

Abstract: The flavonoids isolated from the leaves ofRhododendron brachycarpum, were identified as quercetin, avicularin, quercitrin and hyperin.

Changes in surface properties of poly (ethylene terephthalate) treated with low temperature plasma: effect of pretreatment with dimethylformamide

Abstract: Mesures de mouillabilite, perte de masse, spectrometrie photoelectronique RX et microscopie electronique a balayage

Photothermal probe beam deflection measurement of thermal diffusivity of atmospheric air

Abstract: We have used a modified photothermal probe beam deflection system with a back pumping configuration for the measurements of the temperature-dependent thermal diffusivity of atmospheric air. The results are consistent and reasonably well agree with the literature values. The measured thermal diffusivity values are the same for the same measuring temperature regardless of the beam offsets and the deflecting surface temperatures. For the gas with known temperature-dependent thermal diffusivity, this method can be used to deduce the temperature of a gas from the measured thermal diffusivity value.

Synthesis of steroidal nitrosoureas as antitumor activity

Abstract: Steroidal nitrosoureas have been synthesized and their antitumor activity on L1210 cells was evaluated. N-(2-Chloroethyl)-N-nitrosocarbamoyl-3-aza-A-homo-5α-cholestane (5a) showed significantly low ED50 value of 1.6μg/ml whose activity is equivalent to that of methyl-CCNU (ED50=1.7mg/ml).

Directional growth for numerical wind wave models

Abstract: This study is concerned with the operation of spectral wind wave models. Many spectral wind wave models use a growth mechanism which operates on the point spectrum with directionality being introduced after the fact by the use of a spreading function. It is recognized here that this approach leads to errors whenever the wind and wave fields are not aligned. This is demonstrated by comparing the performance of two first generation models under various conditions. One makes use of a point spectral growth mechanism and follows the operation of the Spectral Ocean Wave Model (SOWM). The other uses a directional growth mechanism but is otherwise the same as the first. A large difference between the models is noted for swell corrupted seas.

Observation of the serum uric acid in essential hypertension.

Abstract: In order to observe the relationship of hyperuricemia and essential hypertension, we studied serum uric acid in 139 patients with essential hypertension visiting the Department of Internal Medicine, Pusan National University Hospital, between May 1982 and July 1983, and analyzed its values in terms of various clinical and laboratory parameters. The mean concentration of serum uric acid and incidence of hyperuricemia in essential hypertension were 6.60 ± 1.96 mg%, 57.9% and those of the normal control group were 3.87 ± 1.30 mg%, 17.8%, respectively with significantly higher values in the hypertension group. The mean concentration of serum uric acid and the incidence of hyperuricemia were significantly correlated with the levels of diastolic blood pressure, mean arterial pressure, BUN, and serum creatinine. Significant correlation between the mean concentration of serum uric acid and the extent of target organ damage and abnormal urine findings were observed.

Characterization of Three Types of Turban Shell Batillus cornutus Muscle—Ultrastructure and Protein Composition

Abstract: Three types of turban shell Batillus cornutus muscle-foot, opercular and visceral-were examined under an electron microscope, and the results discussed in association with their differ-ences in muscle protein composition. Myofibrils of foot muscle were partially surrounded by a collagen fibril layer of about 1μm thickness. Diameters of thick filaments fell in a wide range of 22-70nm (mean value, 50nm). The myofibrils were found to be crossing each other at right angles. The opercular muscle showed a similar structure, except that the collagen fibril layer was clearly thinner. The visceral muscle which surrounds the viscera was composed of roughly parallel-running myofibrils whose thick filaments had a mean diameter of 50nm, Paramyosin contents in the myofibrillar protein were 29-41% through the three types of muscle. The paramyosin to myosin heavy chain ratios were 25 and 2.3 in the foot and opercular muscles, respectively, whereas the ratio in the visceral muscle was 1.4. The collagen to crude protein ratio was 45% in the foot, 34% in the opercular and 5% in the visceral muscle, roughly agreeing with their electron microscopic differences.

Growth mode of multilayer methane on graphite at low temperatures

Abstract: The growth process of multilayer methane on graphite was studied by a.c. heat-capacity technique in the temperature range 4–40 K. The heat-capacity anomalies related to orientational-ordering transitions show gradual change with increasing coverage towards bulk-like behaviour. This result is consistent with the conclusion that methane grows layer by layer on graphite surface for temperatures > 20 K. Another heat-capacity anomaly, unrelated to orientational-ordering transitions, was observed near 11 K for methane film with coverages higher than two layers. We suggest this anomaly is probably related to a structural transition in the multilayer film, possibly due to a wetting transition.

Effect of phenothiazine derivatives on the thermotropic phase transition of liposomal phospholipid membrane

Abstract: The effect of phenothiazine derivatives on the thermotropic transition of liposomal lipid bilayer made of dipalmitoyl phosphatidylcholine and dipalmitoyl phosphatidic acid was investigated with differential scanning calorimetry. The thermograms of the liposomal bilayer incorporated with levomepromazine, chlorpromazine, prochlorperazine, perphenazine and fluphenazine were obtained and the size of cooperative unit of the transition were calculated from the ratio of the van’t Hoff enthalpy change to the calculated enthalpy change of the transition. The results showed that incorporation of phenothiazine derivatives into the liposomal bilayer reduced the transition temperature at which the transition from solid state to liquid-crystalline state occurs, and broadened the thermogram peaks. Phenothiazine derivatives also significantly reduced the size of cooperative unit of the transition. The effect of the drugs was proportional to the concentration of the drug in the bilayer. This means that phenothiazine derivatives might have significant fluidizing effects on the biomembrane. The sizes of cooperative unit were successfully correlated with pharmacological activities of the drugs and the surface pressure increases of lipid monolayer by these drugs. These correlations might be ascribed to a possible hydrophobic nature of interaction between the biomembrane and the drugs involved in their pharmacology.

Fluorescence probe study on the solubilization sites of aniline derivatives in triton X-100 and zephiramine micelles

Abstract: The solubilization sites of aniline and its derivatives in micelles were investigated with fluorescence probe technique The fluorescence probes employed in this study are 12-(9-anthroyl) stearic acid (AS) and 2-p-toluidinylnaphthalene-6-sulfonate (TNS) which are incorporated in the interior of the micelle and attached to its surface, respectively As these two probes were effectively quenched by aniline and its derivatives, the modified Stern-Volmer relationship in micellar system could be applicable to estimate the partition coefficient, K p of the solubilizate between aqueous and micellar phase Because K p derived by this method reflects the relative proximity of the fluorophore to the quencher, the ratio of K p in the surface area to that in the interior of the micelle is interpreted in terms of the relative location of the solubilizate in micellar aggregate The results show that the solubilizates are not located in a definite position but distributed in the multiple-sites of the micelle The solubilization sites of the solubilizates in the micelle are dependent on their structures As the solubilizate has more numbers of N-substituents of aniline and more numbers, of carbon in the substituent, it tends to incorporate in the interior of the micelle more effectively

Age-metallicity relation for F-stars

Abstract: We derived the age-metallicity relation for the solar neighbourhood from the uvby, Hβ photometry of F-stars using the evolutionary models of Hejlesen (1980). It is shown that disk formation is divided into two phases according to the fast and slow collapse which accompany the initial rapid enrichment and slow increase of the metallicity of the galactic disk, respectively.

Chemical liver function tests and epidemiologic studies of HBsAg positive blood donors.

Abstract: The HBsAg positivity in age, sex, occupation, blood type, past history and chemical liver function tests were analyzed in 869 cases without symptoms of liver disease and positive testing for HBsAg by RPHA method, who were selected among 11, 197 blood donors of the Red-Cross Blood Bank in Pusan, Korea from August 1, to September 30, 1982. The following results were obtained: The overall HBsAg positivity in random blood donors was 7.76%. The HBsAg positivity of males was 8.36% and females 6.0%; males had a slightly higher positivity than females. The HBsAg positivity of the 16–20 year old age group had the highest frequency (9.05%), 21–25 year old age group 8.23%, 26–30 year old age group 5.72%, 31–35 year old age group 5.76%, 36–40 year old group 5.85%, 41–45 years old age group 4.76%, and 46–50 year old age group 3.7%. HBsAg positivity had decreasing tendency of frequency by increasing age. The HBsAg positivity of the merchant group had the highest frequency (10.26%), and next, the unemployed, salary man, student, soldier, in order of frequency. The HBsAg positivity in cases with blood type A had the highest frequency (8.07%), and next, cases with B type, O type, and AB type in order of frequency. The HBsAg positivity in cases with no past history in liver disease had the highest frequency (75.37%), and next, cases with history of liver diseases among family 12.54%, hepatitis with jaundice 5.06%, admission due to other diseases except liver diseases 3.57%, transfusion 2.42%, hepatitis without jaundice 1.04%. In chemical liver function tests of HBsAg positive blood donors, elevation of SGPT level showed highest frequency (10.70%), SGOT 7.7%, total serum bilirubin 5.29% and elevation of one or more than of SGPT, SGOT, total serum bilirubin 18.99%. Keywords: Chemical liver function test, HBsAg, Blood donor INTRODUCTION HBV hepatitis may be understood to bring on a carrier state even though viral diseases have not been known to do so in human host. This is the most reliable characteristic, which may give determination on the diagnosis and prognosis for HBV hepatitis.1) Until today, an exact definition for a HBV carrier has not been completely defined yet, but whether a carrier has symptoms of liver damage or not and has chronic liver disease (chronic hepatitis, liver cirrhosis, hepatocellular cancer or not, all tend to be generally implied in this category as a HBV carrier. Although the great clinical interest is that HBsAg chronic carriers are the source of hepatitis type B infection,2) the clinical course and prognosis have not been determined yet, so that clinical and epidemiological studies about the disease are needed to be studied focussing on HBsAg chronic carrier in a country with high incidence of HBV hepatitis such as Korea. So far there have been no conclusive reports in this country, and no reports about liver function tests in HBsAg positive blood donors. We reviewed the HBsAg positivity in the group of random blood donors according to age, sex, occupation, blood type, and past history, and studied the biochemical liver function tests in HBsAg positive blood donors.

Frequency of detectable HBsAg in fluid adherent to the endoscope, gastric juice, and saliva collected during endoscopy in patients positive for HBsAg.

Abstract: Gastric juice, saliva, and fluid adherent to the endoscope were collected from 50 patients who were seropositive for hepatitis B surface antigen (HBsAg) during the endoscopic examination of the upper gastrointestinal tract, and examined for HBsAg, using the radioimmunoassay. A positive test was obtained from 42.0% of the saliva samples, in 32.0% of the gastric juice specimens, and in 31.3% of the fluid adherent to the scope. These results should be taken as a warning, that calls for a more careful screening of the patients and disinfection of the endoscope.

[Studies on beta-glucuronidase activities in liver, stomach and small intestinal tissues of rabbits infected with Clonorchis sinensis]

Abstract: The author has studied the beta-glucuronidase activity in several tissues such as liver, stomach and small intestine of the male and female rabbits infected with different doses of metacercariae of Clonorchis sinensis. The metacercariae of Clonorchis sinensis were isolated from Pseudorasbora parva caught in Kim Hae by digestion technic. The experimental animals were sacrificed in the period of 1, 7, 14, 21, 28 and 35th days following the infection. The results obtained were summarized as follows: In the groups infected with 100 metacercariae, beta-glucuronidase activity was slightly increased during the entire periods than control rabbits. It was the highest in the first day with 1.535 and 1.421 mu/g, 14th days with 2.521 and 2.200 mu/g, and then lowered by the time, gradually. In the groups infected with 500 metacercariae, beta-glucuronidase activity was highly increased on the first day with 1.535 and 1.866 mu/g than that 100 metacercariae groups according to each organs. It was the highest on the 7th day and 14th day. In the groups infected with 1,000 metacercariae, beta-glucuronidase activity was remarkably increased in the first and 14th days according to each organs, and then lowered gradually day by day. beta-glucuronidase activity of all organs was more increased than that of normal organs and the highest activity in the liver with 2.521 mu/g, intestine(1.612) and stomach (1.581) respectively. beta-glucuronidase activity of rabbits was higher in the female than in the male. On the basis of these results, it was suggested that beta-glucuronidase activity was affected by the duration of infection and by the number of Clonorchis sinensis, according to the organs and sex of the rabbits.

Effective Temperatures, Radii, and Luminosities of O Emission, Be and Ae Stars

Abstract: Our de-reddened fluxes, together with the ultraviolet measurements of Thompson et al. (1978), have been compared with those of Kurucz’s (1979) model atmospheres to derive effective temperatures of some O emission, Be and Ae stars. With the measured monochromatic fluxes we determined their angular diameters and luminosities. It is found that the majority of the stars are cooler than the Zero-Age Main Sequence (ZAMS), suggesting that they are slightly more evolved than ZAMS stars.