• Electrical & Electronic Materials
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• v.9 no.7
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• pp.719-726
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• 1996

DLTS measurements were performed to study the annealing induced changes of the trap centers in MOV and to shed more light on the stability mechanism of the MOV. Two electron traps, Ec-0.26[eV] and Ec-(O.2-0.3)[eV], were observed in the unannealed samples in large quantities(7-9 X 1014[CM 3]), whereas the three electron traps Ec-0.17 [eV], Ec-0.26[eV] and Ec-(O.2-0.3)[eV] were observed far less in the annealed samples. The minima in the Ec-0.26[eV] trap density, coupled with the presented results that unannealed devices are unstable whereas 600.deg. C annealed devices are most stable, suggests that the instability of the MOV under long term electrical stressing is related to the Ec-0.26[eV] trap. This results support that the ion migration model for the device instability where the Ec-0.26[eV] defects may be the interstitial zinc or the migrating ions. The interstitial zinc originated as a result of the nonstoichiometric nature of ZnO might cause the degradation of the I-V characteristics of the MOV with long term electrical stressing.

• Korean Journal of Clinical Laboratory Science
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• v.41 no.3
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• pp.111-122
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• 2009

Cadmium (Cd) is known to exert gonadotoxic and spermiotoxic effects. The present study was performed to investigate the morphological effects and metallothionein (MT) expression by zinc pretreatment in the course of time of cadmium-induced testicular injury in rat. Fifty male Spraque-Dawley rats weighing 160~180 g were divided into two groups : saline-pretreated cadmium group and zinc-pretreated cadmium group. Rats of two groups received subcutaneous injection of saline and 100 mg/kg $ZnSO_4$ at 0, 2, 5 and 8 hrs intervals respectively. Cadmium chloride (4.5 mg/kg $CdCl_2$) was administrated intraperitoneally at 2 hrs after zinc injection and rats were killed 0, 12, 24, 48 and 72 hrs later. Testicular tissue damages, interstitial (Leydig) cells status and MT expression were determined using hematoxylin-eosin stained sections and a computerized image analysis system on sections immunostained with a mouse anti-metallothionein respectively. Zinc pretreatment was significantly reduced testicular damages in five pathological categories after cadmium administation. The number of surviving interstitial cells was significantly higher in the zinc-pretreated group than in the saline-preatreated group at 48 and 72 hrs after cadmium administration. Non-damaged testis showed the positivity of MT staining in spermatogenic cells, Sertoli cells and endothelium of blood vessel, but not in the Leydig cells. The positivity of MT staining in saline-pretreated group was significantly reduced at 24 hrs after cadmium administration, whereas zinc-pretreated group showed strong MT positive staining similar to the 0 hr by 42 hrs after cadmium administration. In damaged testis, MT positive staining was also observed in the Leydig cells of both groups. These results suggest that a major preventive effect of zinc against cadmium-induced testicular toxicity may be due to its ability to reduce the cytotoxicity of cadmium in spermatogenic cells and Leydig cells by inhibiting the susceptibility of the testis to cadmium but not MT production by cadmium.

• Korean Journal of Clinical Laboratory Science
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• v.42 no.3
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• pp.136-148
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• 2010

Cadmium (Cd) is known to exert gonadotoxic and spermiotoxic effects. The present study was performed to investigate the morphological effects and metallothionein (MT) expression by zinc pretreatment in the course of time of cadmium-induced testicular injury in rat. Fifty male Spraque-Dawley rats weighing 160-180 g were divided into two groups: saline-pretreated cadmium group and zinc-pretreated cadmium group. Rats of two groups received subcutaneous injection of saline and 100 mg/kg $ZnSO_4$ at 0, 2, 5 and 8 hrs intervals respectively. Cadmium chloride (4.5 mg/kg $CdCl_2$) was administrated intraperitoneally at 2 hr after zinc injection and rats were killed 0, 12, 24, 48 and 72 hrs later. Testicular tissue damages, Interstitial (Leydig) cells status and MT expression were determined using hematoxylin-eosin stained sections and a computerized image analysis system on sections immunostained with a mouse anti-metallothionein respectively. Zinc pretreatment was significantly reduced testicular damages in five pathological categories after cadmium administation. The number of surviving interstitial cells was significantly higher in the zinc-pretreated group than in the saline-preatreated group at 48 and 72 hrs after cadmium administration. Non-damaged testis showed the positivity of MT staining in spermatogenic cells, Sertoli cells and endothelium of blood vessel, but not in the Leydig cells. The potitivity of MT staining in saline-pretreated group was significantly reduced at 24 hrs after cadmium administration, whereas zinc-pretreated group showed strong MT positive staining similar to the 0 hr by 42 hrs after cadmium administration. In damaged testis, MT positive staining was also observed in the Leydig cells of both groups. These results suggest a major preventive effect of zinc against cadmium-induced testiculat toxicity may be due to its ability to reduce the cytotoxicity of cadmium in spermatogenic cells and Leydig cells by inhibiting the susceptibility of the testis to cadmium but not MT production by cadmium.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3547-3552
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• 2013

Single crystal EPR and optical studies of a mixed ligand zinc(II) complex doped with VO(II) ion is carried out to establish the structural properties. The angular variation of vanadyl hyperfine lines indicates a single site, with spin Hamiltonian parameters as: $g_{xx}=1.985$, $g_{yy}=1.979$, $g_{zz}=1.943$; $A_{xx}=8.71$, $A_{yy}=6.41$ and $A_{zz}=17.80$ mT. By comparing the direction cosines of principal g and A values with the direction cosines of metalligand bonds, it has been confirmed that the vanadyl ion has entered the lattice interstitially. The exact interstitial position of VO(II) in host lattice has been calculated using the fractional coordinates of atoms in the host lattice out of many assumptions. The EPR and optical data have been confirmed to obtain various bonding parameters, from which the nature of the bonding in the complex is discussed. FT-IR confirms the formation of structure of host lattice.

• Transactions on Electrical and Electronic Materials
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• v.13 no.1
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• pp.47-49
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• 2012

In this paper, we investigated the anomalous hump in the bottom gate staggered a-IGZO TFTs. During the positive bias stress, a positive threshold voltage shift was observed in the transfer curve and an anomalous hump occurred as the stress time increased. The hump became more serious in higher gate bias stress while it was not observed under the negative bias stress. The analysis of constant gate bias stress indicated that the anomalous hump was influenced by the migration of positively charged mobile interstitial zinc ion towards the top side of the a-IGZO channel layer.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.13-16
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• 2012

Zinc oxide (ZnO) films were deposited by an RF magnetron sputtering system with the RF power of 200W and 300W and flow rate of oxygen gases of 20 and 30 sccm, in order to research the growth of ZnO on carbon doped silicon oxide (SiOC) thin film. The reflectance of SiOC film on Si film deposited by the sputtering decreased with increasing the oxygen flow rate in the range of long wavelength. In comparison between ZnO/Si and ZnO/SiOC/Si thin film, the reflectance of ZnO/SiOC/Si film was inversed that of ZnO/Si film in the rage of 200~1000 nm. The transmittance of ZnO film increased with increasing the oxygen gas flow rate because of the transition from conduction band to oxygen interstitial band due to the oxygen interstitial (Oi) sites. The low reflectance and the high transmittance of ZnO film was suitable properties to use for the front electrode in the display or solar cell.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.58-64
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• 2008

Surface-void defects observed on the galvannealed(GA) steel sheets in Interstitial-free high-strengthened steels containing Si and Mn have been investigated using the combination of the FIB(Focused Ion Beam) and FE-TEM(Field Emission-Transmission Electron Microscope) techniques. The scanning ion micrographs of cross-section microstructure of defects showed that these defects were identified as craters which were formed on the projecting part of the substrate surface. Also, those craters were formed on the Si or Mn-Si oxides film through the whole interface between galvannealed coating and steel substrate. Interface enrichments and oxidations of the active alloying elements such as Si and Mn during reduction annealing process for galvanizing were found to interrupt Zn and Fe interdiffusion during galvannealing process. During galvannealing, Zn and Fe interdiffusion is preferentially started on the clean substrate surface which have no oxide layer on. And then, during galvannealing, crater is developed with consumption of molten zinc on the oxide layer.

• Korean Journal of Metals and Materials
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• v.46 no.5
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• pp.289-295
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• 2008

The effect of the alloy elements(Si/Mn) ratio on the coating quality including wettabilty with molten zinc, galvannealing kinetics and crater has been investigated in interstitial-free high strength steel(IFHSS) containing Si and Mn. When the Si/Mn ratio was below 0.75, IF-HSS exhibited a good wettability leading to a good galvannealed coating quality after annealing at $800^{\circ}C$ for 40s in $15%H_2-N_2$ mixed gas with dew point $-60^{\circ}C$. In contrast, the wettability and galvannealed coating quality were deteriorated in the Si/ Mn ratio above 0.75. It is shown that they have relevance to oxides forms by selective oxidation on the steel surface. The oxide particles dispersed on the steel surface with a surface coverage of below 40% resulted in good wettability and galvannealed coating quality. The oxide particle is mainly consisted of $Mn_2SiO_4$ with low contact angle in molten zinc. On the other hand, the continuous oxide layer on the steel surface, such as network- and film-type,caused to poor wettability and galvannealed coating quality. The coverage of oxide layer was above 80%, and its chemical species was $SiO_2$ with high contact angle in molten zinc. Consequently, the Si/Mn alloy ratio played an importance role in galvannealed coating quality of IF-HSS.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.107-108
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• 2006

ZnO is a promising material for UV or blue LEDs p-Type ZnO thin films which are imperative for the p-n junction of LEDs are difficult to achieve because of strong compensation of intrinsic defects such as zinc interstitial and oxygen vacancy. The method of codoping group three elements and group five elements is effective for the realization of p-type ZnO films. In this study, We codoped N and Al m ZnO thin films by RF magnetron sputtering and annealed the films in sputtering chamber. Some films showed p-type conductivity m Seeback effect measurement.

• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2032-2038
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• 2011

Matrix metalloproteinases (MMPs), a family of zinc-containing endopeptidases, participate in many normal processes such as embryonic development and wound repair, and in many pathological situations such as cancer, atherosclerosis, and arthritis. Peptidomimetic MMP inhibitors were designed and synthesized with N-formylhydroxylamine (retrohydroxamate) as a zinc-binding group and various side chains on the ${\alpha}$, P1', and P2' positions. Using in vitro MMP assays with purified MMPs (MMP-1, MMP-2, MMP-3, MMP-9, and MMP-14) and fluorogenic peptide substrates, it was found that compounds 2d and 2g selectively inhibit gelatinases (MMP-2 and MMP-9) and interstitial collagenase (MMP-1). They also inhibited the chemo-invasion of fibrosarcoma HT-1080 cells and tube formation of human umbilical vascular endothelial cells in a dose-dependent manner. Our results suggest that retrohydroxamate-based MMP inhibitors, especially compounds 2d and 2g, have the potential to be used as therapeutic drugs for cancer and other MMP-related diseases.