• Applied Science and Convergence Technology
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• v.24 no.3
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• pp.67-71
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• 2015

InP/InGaP quantum structures (QSs) were grown on GaAs (001) substrates by a migration-enhanced molecular beam epitaxy method. Temperature-dependent photoluminescence (PL) and emission wavelength-dependent time-resolved PL (TRPL) were performed to investigate the optical properties of InP/InGaP QSs as a function of migration enhanced epitaxy (MEE) growth cycles from 2 to 8. One cycle for the growth of InP QS consists of 2-s In and 2-s P supply with an interruption time of 10 s after each source supply. As the MEE growth cycle increases from 2 to 8, the PL peak is redshifted and exhibited different (larger, comparable, or smaller) bandgap shrinkages with increasing temperature compared to that of bulk InP. The PL decay becomes faster with increasing MEE cycles while the PL decay time increases with increasing emission wavelength. These PL and TRPL results are attributed to the different QS density and size/shape caused by the MEE repetition cycles. Therefore, the size and density of InP QSs can be controlled by changing the MEE growth cycles.

• Neonatal Medicine
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• v.18 no.2
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• pp.177-181
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• 2011

Bronchopulmonary dysplasia (BPD) is characterized by arrest of vascular and alveolar development in premature infants. Recent advances in neonatology have increased the survival of immature babies. Consequently, the prevalence of BPD is increasing. Animal studies and autopsy findings of BPD have demonstrated interruption in vascular development and reversal of lung injury through promotion of vasculogenesis. Normal lung development is driven by temporal and spatial specific growth factors and cellto-cell signaling in vascular development. Lung injury through various pathways causes disruption in this complex interactive process and results in aberrant vascular development and subsequent BPD. By understanding the regulation of vascular growth of the lung, it would be possible to find new targets in the treatment and prevention of BPD in premature infants.

• Journal of Microbiology and Biotechnology
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• v.13 no.3
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• pp.477-481
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• 2003

The community escape response of Rhodobacter sphaeroides is exerted through the action of CerR and CerI, which code for a LuxR-type regulatory protein and acylhomoserine lactone synthase, respectively. Deletion of chromosomal DNA including cerR and cerI (mutant RI) or insertional interruption of cert (mutant AP3) resulted in two-fold increase in the cellular poly-${\beta}$-hydroxybutyrate (PHB) content In comparison with the wild-type under aerobic growth conditions. The PHB synthase (PhbC) activities of the cer mutants were doubled, and the enzyme expression was regulated at the level of phbC transcription. Thus, CerR, possibly in response to autoinducer (AI), appears to modulate the PHB content of aerobically grown cells by downregulating phbC transcription.

• Applied Science and Convergence Technology
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• v.24 no.6
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• pp.254-256
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• 2015

Effect of growth temperature ($T_g$) on the structural and optical properties of $In_{0.5}Ga_{0.5}As$ atomic layer epitaxial (ALE) quantum dots (QDs) is investigated in the range of $T_g=480-510^{\circ}C$. $In_{0.5}Ga_{0.5}As$ ALE QDs consist of 5 periods of short-period superlattices (SPSs) of 1 monolayer-thick InAs and GaAs. Number of coalescent QDs decreases as $T_g$ increases, and they disappear at $T_g=510^{\circ}C$. As $T_g$ increases in the range of $480-495^{\circ}C$, sizes of QDs increase, and densities of QDs decrease due to merge of QDs. On the contrary, although sizes of QDs are maintained at $T_g=495-510^{\circ}C$, densities of QDs decrease. This is attributed to the desorption of material-mainly indium-during the growth interruption. This conjecture is supported by the optical properties of the QDs as a function of $T_g$. As a result, we propose that optimum growth temperature of the QD is $495^{\circ}C$ with less repetition of SPSs than 5.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.1.1-11
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• 1992

To find heavy metal-specific effects on the photosynthetic apparatus of higher plants, we investigated effects of $CuCl_2$, HgCl_2$ and $ZnCl_2$ on electron transport activity and chlorophyll fluorescence induction kinetics of chloroplasts isolated from barley seedlings. Effects on some related processes such as germination, growth and photosynthetic pigments of the test plants were also studied. Germination and growth rate were inhibited in a concentration-dependent manner by these metals. Mercury was shown to be the most potent inhibitor of germination, growth and biosynthesis of photosynthetic pigments of barley plants. In the inhibition of electron transport activity, quantum yield of PS II, and chlorophyll fluorescence induction kinetics of chloroplasts isolated from barley seedlings, mercury chloride showed more pronounced effects than other two metals. Contrary to the effects of other two metals, mercury chloride increased variable fluorescence significantly and abolished qE in the fluorescence induction kinetics from broken chloroplasts of barley seedlings. This increase in variable fluorescence is due to the inhibition of the electron transport chain after PS ll and the following dark reactions. The inhibition of qE could be attributed to the interruption of pH formation and do-epoxidation of violaxathin to zeaxanthin in thylakoids by mercury. This unique effect of mercury on chlorophyll fluorescence induction pattern could be used as a good indicator for testing the presence and/or the concentration of mercury in the samples contaminated with heavy metals.

• Korean Journal of Materials Research
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• v.18 no.10
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• pp.535-541
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• 2008

Growth behavior of InGaN/GaN self-assembled quantum dots (QDs) was investigated with respect to different growth parameters in low pressure metalorganic chemical vapor deposition. Locally formed examples of three dimensional InGaN islands were confirmed from the surface observation image with increasing indium source ratio and growth time. The InGaN/GaN QDs were formed in Stranski-Krastanow (SK) growth mode by the continuous supply of metalorganic (MO) sources, whereas they were formed in the Volmer-Weber (V-W) growth mode by the periodic interruption of the MO sources. High density InGaN QDs with $1{\sim}2nm$ height and $40{\sim}50nm$ diameter were formed by the S-K growth mode. Dome shape InGaN dots with $200{\sim}400nm$ diameter were formed by the V-W growth mode. InN content in InGaN QDs was estimated to be reduced with the increase of growth temperature. A strong peak between 420-460 nm (2.96-2.70 eV) was observed for the InGaN QDs grown by S-K growth mode in photoluminescence spectrum together with the GaN buffer layer peak at 362.2 nm (3.41 eV).

• Horticultural Science & Technology
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• v.32 no.4
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• pp.434-439
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• 2014

This research was conducted to examine the effects of night interruption (NI) at different times on vegetative growth and flowering in Salvia splendens 'Salsa'. Plants were grown in a growth chamber under 9-h photoperiod (short-day, SD) or 9-h photoperiod plus NI with light intensity at $3-5{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ photosynthetic photon flux. The NI was applied at 18:00-22:00 HR (NI18), 22:00-02:00 HR (NI22), or 02:00-06:00 HR (NI02). The net photosynthetic rate under NI18, NI22, and NI02 increased by 0.33, 0.16, and $0.13{\mu}mol{\cdot}CO_2{\cdot}m^{-2}{\cdot}s^{-1}$, respectively, during the NI period. Dry weight, plant height, and the number of nodes under NI were not significantly different from those of the plants under SD. However, flowering was earlier by approximately 9.8 days, and the number of flowers increased to 138.7 in NI02 compared to 36.4 flowers under SD at 17 weeks after the treatment. Our results indicate that NI02 was the most effective treatment in promoting flowering. Although vegetative growth of salvia was not increased in response to the increased net photosynthesis, flowering was promoted. Under NI18, NI22, and NI02 treatments, 77.8, 88.9, and 100.0% of salvia plants flowered within 8 weeks, whereas 44.4% of the plants flowered within the same time under SD conditions.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.86-91
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• 2013

The optical properties of InAs quantum dots (QDs) grown on GaAs substrates grown by molecular beam epitaxy have been studied using photoluminescence (PL) and time-resolved PL measurements. InAs QDs were grown using an arsenic interruption growth (AIG) technique, in which the As flux was periodically interrupted by a closed As shutter during InAs QDs growth. In this study, the shutter of As source was periodically opened and closed for 1 (S1), 2 (S2), or 3 s (S3). For comparison, an InAs QD sample (S0) without As interruption was grown in a pure GaAs matrix for 20 s. The PL intensity of InAs QD samples grown by AIG technique is stronger than that of the reference sample (S0). While the PL peaks of S1 and S2 are redshifted compared to that of S0, the PL peak of S3 is blueshifted from that of S0. The increase of the PL intensity for the InAs QDs grown by AIG technique can be explained by the reduced InAs clusters, the increased QD density, the improved QD uniformity, and the improved aspect ratio (height/length). The redshift (blueshift) of the PL peak for S1 (S3) compared with that for S0 is attributed to the increase (decrease) in the QD average length compared to the average length of S0. The PL intensity, PL peak position, and PL decay time have been investigated as functions of temperature and emission wavelength. S2 shows no InAs clusters, the increased InAs QD density, the improved QD uniformity, and the improved QD aspect ratio. S2 also shows the strongest PL intensity and the longest PL decay time. These results indicate that the size (shape), density, and uniformity of InAs QDs can be controlled by using AIG technique. Therefore the emission wavelength and luminescence properties of InAs/GaAs QDs can also be controlled.

• Clinical and Experimental Pediatrics
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• v.58 no.7
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• pp.270-273
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• 2015

Legg-Calve-Perthes (LCP) disease is characterized by idiopathic avascular osteonecrosis of the epiphysis of the femur head. The main factor that plays a role in the etiology of the disease is decreased blood flow to the epiphysis. Many predisposing factors have been suggested in the etiology of LCP disease, and most have varying degrees of effects. Here we present the case of a boy aged 4 years and 10 months with complaints of short stature and a diagnosis of multiple hypophyseal hormone deficiency, in whom LCP disease and difficult birth-related pituitary stalk interruption syndrome were identified by anamnesis. The present case revealed that LCP disease and hypophyseal hormone deficiency could be secondary to difficult birth and that LCP disease could be secondary to insulin-like growth factor 1 deficiency. Additionally, to the best of our knowledge there is no published case on the relation between LCP disease and insulin-like growth factor 1 deficiency. Therefore, we believe that this case is worthy of presentation.

• Journal of Life Science
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• v.24 no.12
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• pp.1345-1355
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• 2014

The interruption of angiogenesis using herbal extracts is now recognized as a useful approach for treating many solid tumors. To date, the best-validated antitumor approach is to target the vascular endothelial growth factor (VEGF)-induced angiogenic pathway. In the present study, we first identified the antiangiogenic activity of a hot-water extract of Rubus coreanus Miquel (RCMHE) in vitro and ex vivo. This extract suppressed VEGF-induced angiogenesis, the phosphorylation of extracellular regulated kinase (ERK), p38 and the activation of matrix metalloproteinases (MMPs). RCMHE also inhibited the VEGF-responsive phosphorylation of VEGFR2. These results clearly show that RCMHE may have potential therapeutic value for angiogenesis-associated human diseases through the suppression of angiogenesis and the interruption of the phosphorylation of VEGFR2.