• Journal of Photoscience
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• v.9 no.2
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• pp.158-161
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• 2002

UV-B radiation gives harmful effects on plants, such as production of several types of DNA lesions, and growth inhibition. On the other hand, plants have some protective mechanisms, including filtering effect due to accumulation of phenolic compounds in epidermal cells and reactivation of DNA lesions, which are enhanced by UV-B irradiation. We have investigated the mechanism of UV-B effects on plants using cucumber seedlings as plant materials. Cucumber plants were cultivated in an artificially lit growth chamber. Supplemental UV-B irradiation, of which intensity was almost equal to the level of natural sunlight, retarded the growth of first leaves. The growth retardation must result trom the inhibition of cell division and/or cell growth. Microscopical observation of leaf epidermis suggested that the growth retardation might be mainly caused by cell growth inhibition. The retardation was, however, restored within 2 or 3 days after the termination of UV-B irradiation. It is known that UV-B irradiation lowers the activity of photo system II (PS II). In the present experimental conditions, however, UV-B irradiation has little effect on PS II activity as estimated by chlorophyll fluorescence. The stomatal conductance, a major factor determining photosynthetic rate, of first leaves increased during the growth. The increase of stomatal conductance was suppressed by UV-B irradiation and restored by termination of the irradiation. It has not been clear, however, what mechanisms are involved in the suppression of increase of stomatal conductance.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.12
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• pp.2004-2010
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• 2003

Fracture life and crack retardation behavior were examined experimentally using CT specimens of aluminum alloy 5083. Crack retardation life and fracture life were a wide difference. between 0.8 and 0.6 in proportion to ratio of load reduction. The wheeler model retardation parameter was used successfully to predict crack growth behavior. By using a crack propagation rule, prediction of fracture life can be evaluated quantitatively. A statistical approach based on Weibull distribution was applied to the test data to evaluate the dispersion in the retardation life and fracture life by the change of load reduction.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.601-607
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• 1994

This study was carried out to investigate the potential of phenol to induce embryotoxicity in the Sprague-Dawley rat. Seventy mated rats were distributed among three treated troups, a vehicle control group and a negative control group. Phenol was at dose levels of 20, 60 and 180mg/kg/day adminsistered by gavage to pregnant rats three times per day from days 7 to 12 of gestation. All dams were subjected to the caesarean section on day 20 of gestation. At 120mg/kg, dams exhibited decreased locomotivity. In addition, both weight reduction and retarded ossification of fetuses were observed. There were no signs of maternal toxicity or embryotoxicity at 20 and 60mg/kg. The results show that phenol induces fetal growth retardation at maternally subtoxic dose in rats.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.196-198
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• 2001

The growth retardation of Escherichia coli and Staphylococcus aureus by heat or acid treated leek (Allium tuberosum) extract was observed. Antimicrobial activity of the leek was the most effective when fresh leek extract was used, but it was stable after heat treatment at 68$^{\circ}C$ for 30 min or 98$^{\circ}C$ for 20 min. It was also relatively stable after incubated at pH 2.0 for 3 hrs. The antimicrobial activity in leek was not detected after dialysis with molecular weight cutoff of 12,000. Therefore it seems to be small molecule with molecular weight lower than 12,000.

• Clinical and Experimental Pediatrics
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• v.57 no.6
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• pp.292-296
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• 2014

The deletion of the distal long arm of chromosome 1 is associated with a characteristic facial appearance and a pattern of associated malformations. Characteristic manifestations include a round face with prominent 'cupid's bow' and downturned corners of the mouth, thin vermilion borders of lips, a long upper lip with a smooth philtrum, a short and broad nose, epicanthal folds, apparently low-set ears, micrognathia, microcephaly, abnormal hands and feet, variable cardiac or genital anomalies, moderate to severe mental retardation, and growth retardation. Using fluorescent in situ hybridization (FISH) analysis to map precisely the deletion, we present a case of chromosome 1q44 deletion with craniofacial characteristics, multiple congenital anomalies, and growth and psychomotor retardation. In comparison with other reported cases of 1q43-44 deletion, the subject does not show hydrocephalus, seizure, syn- or polydactyly of hands, and a urogenital anomaly. However, an arachnoid cyst, pinpoint dimple on the midline of the forehead, a right-sided supernumerary nipple and auricular pit, polydactyly of the right foot, adducted thumb, and flexion restriction of the proximal interphalangeal joint with a simian line in both hands were observed additionally.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.112-120
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• 2015

In this study, the growth rate of surface cracks (da/dN) during the retardation period was analyzed in terms of effective stress intensity factor range(${\Delta}K_{eff}^*$) obtained by using the proposed effective plastic zone concept. Effective stress intensity factors obtained by using the effective plastic zone concept were smaller than those obtained by using Willenborg analysis. On the growth rate of surface cracks analyzed by ${\Delta}K$, the dependence of overload stress levels appears. On the growth rate by ${\Delta}K_{eff}$ obtained by Willenborg analysis, there is a linear relationship with two different slops between da/dN and ${\Delta}K_{eff}$. However, on the growth rate by ${\Delta}K_{eff}^*$ obtained by the proposed effective plastic zone concept, there is a linear relationship between da/dN and ${\Delta}K_{eff}^*$ that coincides with the results of constant amplitude loading.

• The Korea Journal of Herbology
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• v.29 no.5
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• pp.31-38
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• 2014

Objectives : Egg yolk is composed of various important chemical substances for human health. A calcium shortage causes the growth retardation on the body growth. In this study, we examined the therapeutic effects of calcium, vitamin D and egg yolk peptide (EYP) treatment on the retardation of the longitudinal bone growth induced by low-calcium diet in adolescent rats. Methods : Low calcium diets were administrated for 15 days. During the last five days, calcium and/or vitamin D and/or EYP were administrated. The body weights, longitudinal bone growth rates, the heights of growth plates, and bone morphogenetic protein (BMP)-2 and insulin-like growth factor (IGF)-1 expressions were measured using histochemical analysis. Results : Low calcium diets caused the significant reduction in body weight gains and the longitudinal bone growth. The heights of growth plates and the expressions of BMP-2 and IGF-1 showed the impairment of body growth as well. Calcium and/or vitamin D administration could not significantly increase the longitudinal bone growth. However, calcium, vitamin D, and EYP administration significantly increased the bone growth, the growth plate height, and BMP-2 and IGF-1 expressions. Conclusions : These results suggest that EYP enhances the longitudinal bone growth in the calcium and/or vitamin D deficiency and it could be a promising agent for the treatment of children suffering from malnutrition.

• Korean Journal of Pharmacognosy
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• v.13 no.3
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• pp.116-121
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• 1982

In order to investigate the side-effects of crude drugs, twenty drugs have been tested for the teratogenic effect in rats. Among seven drugs contained alkaloid as their ingredients, no one showed teratogenic effect, but Veratri rhizoma showed embryo-toxic as revealed by severe retardation in growth of the fetuses. The other thirteen drugs which have been used freguently in oriental medicines exhibited no teratogenic effect. Cyclophosphamide used as a reference compound showed severe malformation and retardation in the growth of rat fetuses. These findings suggest that the drug extracts adopted for the study might have no teratogenic effect in the rats.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.4
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• pp.72-77
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• 2002

The load interaction effect can be best illustrated by the phenomenon of overload retardation. Some prediction methods for retardation are reviewed and the problems discussed in the present paper. The so-called under-load effect much of the retardation disappears if a very low level minimum stress follows the overload, is also of importance for a prediction model to work properly under random load spectrum. The concept of Interactive Zone (IZ) fully considering reversed plasticity during unloading was discussed. This IZ concept can be combined with existing models to derive some improved models that can naturally take account of the under-load effect. Some simulations by IZ improved models for test under complex load sequences including multiple overloads and both over/under loads are compared with test results. It is seen that the improvement by IZ concept greatly enhanced the ability of existing models to accommodate complex load interaction effects.

• Journal of Ocean Engineering and Technology
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• v.18 no.1
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• pp.28-34
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• 2004

It is well known that tensile peak overloads may significantly delay suubsequent constant amplitude fatigue crack growth in many materials. Since real structures are usually subjected to complex load histories, the ability to predict accurate crack growth under realistic service conditions is of major engineering interest. This paper describes experiments on fatigue track growth in the integrally stiffened panel of 7075-T6 aluminum alloy. The effect of shape parameters and overload position on the fatigue crack growth behavior of integrally stiffened panels are discussed. Based on the experimental results, the following conclusions have been drawn: the overall fatigue crack growth retardation resulting from single overload in the stiffened panels was generally larger in the larger thickness ratio, although the retardation trends, according to the change in overload positions, were similar to those exhibited in the non-stiffened panels.