Showing papers by "Korea University published in 1980"

Piezoelectricity Revealed in the Copolymer of Vinylidene Cyanide and Vinyl Acetate

Abstract: The piezoelectric properties of an alternative copolymer of vinylidene cyanide and vinyl acetate were investigated in connection with the results of dynamic modulus, X-ray diffraction, and electrostriction effect. The rolled and polarized copolymer showed piezoelectricity strong enough to be comparable to that in poly(vinylidene fluoride) films treated by the same poling conditions, but the piezoelectric activity prevailed at high temperature exceeding 100°C. This strong piezoelectricity is considered due to the introduction of large dipole moments such as C–CN groups in the molecule and to the orientation of this large dipole moment in the film.

Experimental study on the therapeutic effect of praziquente1(Embay 8440) in rats experimentally infected with Clonorchis sinensis

Abstract: Experimentally infected rats with 50 metacercariae of Clonorchis sinensis each were treated orally with different dosages of praziquantel. About 100 rats were divided into 8 groups in each developmental week after infection (from the first to 8th week after infection) and 24 rats served as untreated controls. In each developmental week after infection, about 15 rats divided into 4groups including control group(3 to 5 rats) were used to determine for the curative activity of praziquantel against C. sinensis. The experimentally infected rats in each developmental weeks after infection received praziquantel 1 x 100 mg/kg x 3 days, 3 x 100 mg/kg x 1 day and 3 x 100 mg/kg x 2 days. The effects of the drug were evaluated by the worm recovery rates, morphological changes of the worms and the number of eggs per gram of feces (EPG) after treatment. The feces of individual rats were collected once in a week at one week before and 4 weeks after treatment, and the number of Clonorchis eggs were examined by Stoll's egg counting method. The necropsy was performed on 4 weeks after treatment. The liver and the bile ducts were examined immediately after the dissection, and all of the worms recovered from the liver immersed in warm saline solution in a small petri dish in order to observe the motility of individual worms. After that, all worms obtained from the treated and untreated control rats were fixed in 10 percent formalin solution. The whole mount specimens were prepared by Semichon's acetocarmine stain for the study of morphlogical changes. In the treatment with dosage of 1 X 100 mg/kg for 3 consecutive days, relatively low worm recovery rates were shown in the early stages of infection than those of control groups. However there was no differences of the worm recovery rates between the later stages of infection (7 to 8 weeks after infection) and control groups. In the early stages of infection, the worms recovered in the bile ducts of each treated rats showed morphologically intact as normal control groups, however in the later stages of infection the worms showed damage of their reproductive organs such as testes, seminal receptacle and ovary etc. In the treatment with dosage of 3 X100 mg/kg X 1 day, the recovery rates of the worms in all developmental weeks after infection were considerably low and some growth inhibition of the worms were also noted. The worms recovered from the bile ducts in all developmental stages were seriously damaged in their reproductive organs, such as testes, seminal receptacle, ovary, Mehlis' gland, uterus and vitelline glands etc. The hyaline degenerations were also observed on the parenchymal tissues in the dead worms. The mean EPG values in this group were markedly reduced at the first 2 weeks after treatment. However the low values of EPG were generally noted at the 3rd to 4th week after treatment. On the other hand, in the treatment with dosage of 3 X 100 mg/kg X 2 days, no more the living worms was recovered in all developmental stages of Clonorchis. The dead worms recovered from the bile ducts were so seriously damaged that the morphological changes could not be observed. The mean EPG values in this group were markedly reduced during the first 2 weeks after treatment. At the 3rd week after treatment EPG value became negative in the most of all treated groups. No more the Clonorchis eggs were detected at the 4th week after infection, but only a very small numbers of eggs were found by the concentration method. From the above results, it is obvious that praziquantel exhibits a high degree of activity against Clonorchis sinensis in the rats, with no apparent differences in the efficacy against each developmental stage.

Epitaxial Integrated E-dE Silicon Detector with a Buried Low-Resistive Diffused Layer

Abstract: The epitaxial crystal growth technique combined with the impurity diffusion technique is applied on fabrication of integrated E-dE silicon detectors. Experimental results show that detector produced seems to have enough characteristics for use in practical experiments. This detector is compact and easy to handle, and eliminates the highly technical process of etching the substrate, which is necessary for producing the conventional epitaxial silicon dE detector.

Low cycle fatigue behavior of a quenched and tempered niobium bearing HSLA steel

Abstract: The low cycle fatigue behavior of a quenched and tempered niobium (columbium) bearing high strength low alloy steel heat treated to give tempered martensitic microstructures presumably with and without fine niobium carbides was studied by transmission electron microscopy, stress relaxation, X-ray diffraction line broadening and strain-controlled fatigue testing. The steel without the niobium carbides cyclically softened rapidly at all strain amplitudes studied. This softening was attributed to the rearrangement of the dislocation substructure into a cell structure and to the accompanying decrease in internal stress. The steel presumably containing the fine niobium carbides cyclically softened to a lesser extent. This correlated with the observation that dislocations in this steel did not rearrange themselves into a cell structure and, hence, there was less change in the internal stress during cycling. The steel without the niobium carbides exhibited somewhat better strain-life behavior at large strain amplitudes. This was attributed to the cell structure being able to accommodate a greater amount of plastic strain in that steel.

An Epidemiological Note On The Taeniasis In Korea

Abstract: The present study was undertaken to evaluate the prevalence rate of Taenia spp infection and distribution of taeniasis caused by T solium among Koreans in several localities in Korea during the period from 1977 to 1980 A total of 1,946 stool specimens collected from students and inhabitants of Chungcheong Bug Do and Gyeongsang Nam Do were examined by cellophane thick smear method Among them, 40 persons were detected as Taenia egg positive cases The overall positive rate of Taenia spp shows 21 % The prevalence rate of male (23 %) is relatively higher than that of female (14 %) In order to observe the distribution of Taenia solium infection, the whole worms or a part of proglottids of Taenia spp were collected from the stools of egg positive cases by normal defecation or anthelmintic treatment For the species identification, expelled proglottids were examined microscopically by the number of branches of the uterus, presence of a vaginal sphincter or the accessory ovarian lobe etc Among 199 egg detected cases in this study 59 (391 %) out of 151 cases in Seoul, 12(400 %) of 30 cases in Gyeongsang Nam Do and 2 (250 %) from 8 taeniasis cases in Cheju Do were infected with T solium But none of T solium infection was found from 10 egg positive cases in Chungcheong Bug Do As a whole, the composition of species shows 367 per cent of T solium infection and 558 % of T saginata infection, and in 75 per cent the species were not identified

Anthelmintic effect of amidental (Bay d 8815) against Ancylostoma duodenale infection.

Abstract: A new anthelmintic, amidantel(Bay d 8815), an acetylated p-amino-phenyl-acetamidine was tried in 140 patients with Ancylostoma duodenale and other helminth infections. In the first trial, each 16 cases in 64 patients with A. duodenale were treated with 3.0, 6.0 and 9.0 or 10.0 mg/kg body weight of amidantel including placebo control. Another 76 patients infected with hookworms and other helminths were treated with 5.0, 6.0 and 8.0 mg/kg body weight of amidantel in the second trial. In order to assess the efficacy and safety of the drug, follow-up examination by repeated and replicated examinations over three consecutive days were performed at 14 to 16 days and 28 to 30 days after treatment, And complete laboratory studies including ECG were carried out before and one day after the medication. In the results, it was confirmed that amidantel is very effective against A. duodenale as well as Ascaris lumbricoides. With regard to dosage, a single dose of 6.0 mg/kg body weight of amidantel was found to be the most effective and well tolerated than the other dosages employed. In a single dose of 6.0 mg/kg body weight the cure rates were 93.8 and 96.6 per cent for A. duodenale infection and 90.9 and 93.1 per cent for ascariasis in the first and second trials respectivley. Relatively significant activity was also observed against Necator americanus at the dosages employed, however it was not superior to other drugs currently use. No significant activity was noted against Trichuris trichiura. Side effects including headache, nausea, dizziness and abdominal discomfort were usually mild and transient. No significant changes attributable to therapy were observed in hematology, blood biochemistry and urinalysis as well as ECG.

Morphological Observations On Clonorchis Sinensis Obtained From Rats Treated With Praziquantel

Abstract: The present study was undertaken to observe the morphological changes of Clonorchis sinensis obtained from experimentally infected rats treated with praziquantel (Biltricide) which is a new anthelmintic agent with high activity against a broad spectrum of cestode and trematode species. For this study, the rats were infected experimentally with about 50 metacercariae of C. sinensis and were given praziquantel a single dose of 600 mg per kg of body weight at 5 weeks after infection. The Clonorchis worms were isolated from the bile ducts of the rats which were autopsied on the 4th day after treatment. After isolation the parasites were observed their shape and motility in the medium of 37 degrees C physiological saline solution, and then the fine structure of the tegument of C. sinensis was studied by means of light, scanning and transmission electron microscope. The findings of the observation were compared with those of untreated parasites. The results are as follows: 1. All the isolated worms moved actively in the medium of physiological saline solution (37 degrees C). A majority of the parasites obtained from the treated rats showed a large balloon shaped structure on the surface between oral and ventral suckers. But such structure has never seen in the parasites obtained from control rats. 2. By the scanning electron microscopic observation, the regular pattern of the tegumental ridges was significantly changed on the outer surfaces of parasites obtained from the treated rats as compared with those of the control rats. 3. By the transmission electron microscopic observation, the numerous mitochondriae in the syncytial tegumental layer of the treated parasites appeared to be degenerated and formed small vacuoles, and the tegumental ridges were also degenerated and showed somewhat flattened. 4. In the parasites obtained from the treated rats, a different size of vacuoles interspersed in the distal part of the syncytial tegument and also in subepithelial region of the urinary bladder. These vacuoles are fused each other and lead to the disruption of the apical region of syncytial tegument along the basement layer. Finally the basement layer was dislocated. So that the tegumental layer appeared as a large balloon.

On parameter estimation in Bernoulli trials with dependence

Abstract: A simple estimator is proposed for the dependence parameter for the Klotz model of Bernoulli trials with Markov dependence and it is compared with the ratio estimator given by Price and the approximate maximum likelihood estimator given by Klotz. The proposed estimator is shown to have considerably smaller bias than the other two estimators with comparable mean squared errors, and has all the large sample optimal properties that the other two estimators have.

Energy spectrum and phase velocity in two- and three-dimensional liquid helium II

Abstract: We have evaluated the excitation spectrum, structure factor, and phase velocity of two- and three-dimensional Bose fluids with a soft potential plus a Lennard-Jones type tail. For two dimensions, the excitation spectrum is similar to that for the bulk case, and the sound velocity, roton energy and momentum are found to be 164.4 m/s, 4.12 k and 1.02 A -1 , respectively. The three-dimensional phase velocity agrees well with the experimental dispersion curve.

In Vitro Activities Of Various Drugs Against Adult Worms Of Clonorchis Sinensis

Abstract: The present study was undertaken to evaluate in vitro activities of following drugs against adult worms of Clororchis sinensis: i.e., stibnal, chloroquine diphosphate, Hetol (1,4-bis-trichloromethylbenzol), dehydroemetine "Roche" (Ro 1-9334), niridazole (Ambilhar), bisbendazole, gentian violet, dithiazanine iodide, hexachlorophene, bithionol, niclofolan (Bilevon, Bayer 9015) and praziquantel (Embay 8440, Biltricide). After isolation from bile ducts of experimentally infected rabbits (3 months infection), the parasites were rinsed in sterilized Tyrode's solution and incubated for 24 hours at 37 degrees C in TC 199 medium with Earle's balanced salt solution containing 0, 0.01, 0.1, 1.0, 10 and 100 microgram/ml concentrations of each above drugs. The activities of each concentrations with each drugs were evaluated by the motility of the worms in culture tubes observing at 15, 30, 60 minutes and 2, 4, 6, 12, 18 and 24 hours by stereomicroscope. In the results, no effect was found at the adult worms of C. sinensis in all concentrations with stibnal, chloroquine diphosphate, Hetol, dehydroemetine, niridazole and bisbendazole. However, moderate activities were observed in the concentrations of 1.0 and 0.1 microgram/ml of gentian violet, dithiazanine iodide, hexachlorophene and bithionol. The highest activities were observed in all concentrations of niclofolan and praziquantel.