• Environmental Analysis Health and Toxicology
• /
• v.24 no.2
• /
• pp.107-117
• /
• 2009

Metal pollution of aquatic ecosystems is a problem of economic and health importance. Information regarding molecular responses to metal exposure is sorely needed in order to identify potential biomarkers. To determine the effects of heavy metals on chironomids, the full-length cDNA of alcohol dehydrogenase (ADH3) from Chironomus riparius was determined through molecular cloning and rapid amplification of cDNA ends (RACE). The expression of ADH3 was analyzed under various cadmium and copper concentrations. A comparative and phylogenetic study among different orders of insects and vertebrates was carried out through analysis of sequence databases. The complete cDNA sequence of the ADH3 gene was 1134 bp in length. The sequence of C. riparius ADH3 shows a low degree of amino acid identity (around 70%) with homologous sequences in other insects. After exposure of C. riparius to various concentrations of copper, ADH3 gene expression significantly decreased within 1 hour. The ADH3 gene expression was also suppressed in C. riparius after cadmium exposure for 24 hour. However, the effect of cadmium on ADH3 gene expression was transient in C. riparius. The results show that the suppression of ADH3 gene by copper exposure could be used as a possible biomarker in aquatic environmental monitoring and imply differential toxicity to copper and cadmium in C. riparius larvae.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.159-159
• /
• 2016

Vertically-aligned carbon nanotubes (VCNT) have attracted much attention due to their unique structural, mechanical and electronic properties, and possess many advantages for a wide range of multifunctional applications such as field emission displays, heat dissipation and potential energy conversion devices. Surface modification of the VCNT plays a fundamental role to meet specific demands for the applications and control their surface property. Recent studies have been focused on the improvement of the electron emission property and the structural modification of CNTs to enable the mass fabrication, since the VCNT considered as an ideal candidate for various field emission applications such as lamps and flat panel display devices, X-ray tubes, vacuum gauges, and microwave amplifiers. Here, we investigate the effect of surface morphology of the VCNT by water vapor exposure and coating materials on field emission property. VCNT with various height were prepared by thermal chemical vapor deposition: short-length around $200{\mu}m$, medium-length around $500{\mu}m$, and long-length around 1 mm. The surface morphology is modified by water vapor exposure by adjusting exposure time and temperature with ranges from 2 to 10 min and from 60 to 120oC, respectively. Thin films of SiO2 and W are coated on the structure-modified VCNT to confirm the effect of coated materials on field emission properties. As a result, the surface morphology of VCNT dramatically changes with increasing temperature and exposure time. Especially, the shorter VCNT change their surface morphology most rapidly. The difference of field emission property depending on the coating materials is discussed from the point of work function and field concentration factor based on Fowler-Nordheim tunneling.

• Journal of Environmental Health Sciences
• /
• v.26 no.4
• /
• pp.21-28
• /
• 2000

Various man-made mineral fibers(MMMF) including refractory ceramic fiber(RCF) have been used widely in industries as insulation materials. The effect of fibrous dust on human health depends on fiber size, concentration (exposure level), and durability in biological system. Therefore, these parameters should be determined to evaluate accurately the potential risk of fibers on human health. The purpose of this study was to characterize the size of airborne fiber and the workers＇ exposure to airborne fibers in refractory ceramic fiber manufacturing and processing factories. Airborne fibers were collected on 25-mm mixed cellulose ester membrane filters at personal breathing zones, and analyzed by A and B counting rules of the National Institute for Occupational Safety and Health(NIOSH) Method # 7400. The average ratios of the fiber density by B rule to the fiber density by A rule was 0.84. This result indicates that the proportion of respirable fibers (<3 ${\mu}{\textrm}{m}$ diameter) in air samples was high. The average diameter and length of airborne fibers were 1.05${\mu}{\textrm}{m}$ and 35${\mu}{\textrm}{m}$, respectively. The average fiber concentrations (GM) of all personal samples was 0.26f/cc, and the average concentration was highest at blanket cutting and packing processes. The fifty seven percent of personal air samples was exceeded the proposed American Conference of Governmental Industrial Hygienists(ACGIH) Threshold Limit Value(TLV), i.e. 0.2 f/cc. It was concluded that the RCF industrial workers had the higher potential health risk due to small fiber diameter, long fiber length, and high exposure level to the airborne fibers.

• Fisheries and Aquatic Sciences
• /
• v.19 no.10
• /
• pp.44.1-44.8
• /
• 2016

Rockfish, Sebastes schlegelii (mean length $14.53{\pm}1.14cm$ and mean weight $38.36{\pm}3.45g$), were exposed for 4 weeks with the different levels of ammonia in the concentrations of 0, 0.1, 0.5, and 1.0 mg/L at 19 and $24^{\circ}C$. The indicators of growth performance such as daily length gain, daily weight gain, condition factor, and hematosomatic index were significantly reduced by the ammonia exposure and high temperature. The ammonia exposure induced a significant decrease in hematological parameters, such as red blood cell (RBC) count, white blood cell (WBC) count, hemoglobin (Hb), and hematocrit (Ht), whose trend was more remarkable at $24^{\circ}C$. Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), and mean corpuscular hemoglobin concentration (MCHC) were also notably decreased by the ammonia exposure. Blood ammonia concentration was considerably increased by the ammonia concentration exposure. In the serum components, the glucose, glutamic oxalate transaminase (GOT), and glutamic pyruvate transaminase (GPT) were substantially increased by the ammonia exposure, whereas total protein was significantly decreased. But, the calcium and magnesium were not considerably changed.

• The Journal of Korean Academy of Prosthodontics
• /
• v.39 no.6
• /
• pp.625-632
• /
• 2001

Statement of Problem. Objective and quantitative measurement of implant stability is very important from implant installation to long-lasting maintenance period thereafter. Purpose of study. This study was to evaluate and compare two ISQ and PTVs on the implant stability measurements according to the increased effective implant length. Materials and methods. Twenty self-tapping fixtures were installed in the bovine scapula and in 10 of those for group I, ISQ and PTVs were obtained in the vertical/horizontal directions according to the increased effective implant length using $Osstell^{TM}$ and $Periotest^{(R)}$. After stability measurement, removal torques were measured between the after installation and after thread exposure group. Results. ISQ and PTVs showed decreased and increased values according to the increased abutment length. Apart from PTVs, ISQ values were shown higher in horizontal direction to the long axis of bone in both the after installation and the after thread exposure groups. Removal torque values were shown higher in after installation group. Conclusion. From the results of this study, implant stability measurement using resonance frequency analysis was more sensitive and discriminative than PTVs measurement.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
• /
• v.27 no.1
• /
• pp.55-71
• /
• 1997

Digora/sup (R)/ an intraoral digital radiography system utilizing image plate (IP) - has a dynamic range of exposure time which allows it to decrease the patient's exposure time and to increase diagnostic ability through image processing, transmission and storage. The purpose of this study was to evaluate the Digora/sup (R)/ system by assessing the effects of various exposure times on the detectability on the tip of the endodontic file. Examining the root canals of 45 extracted sound premolars, K -files No. 10, 15, and 20 were placed at slightly varying distances from the apex. The teeth were glued onto resin-plaster blocks. Five exposure times varying between 0.01 seconds and 0.25 seconds were used. Four observers were asked to measure the distance between the tip of the file and a reduction of crown portion, and obtained mean errors (subtracting true file length from the measured file length), comparing Digora/sup (R)/ monitors with E-plus films, which were both obtained under the same geometrical positions. The results were as follows : 1. Comparing E-plus film with Digora/sup (R)/ at 0.01 seconds, the mean errors in E-plus film showed -4.453 nun, -4.497 nun, and -3.857 nun, while the mean errors in Digora/sup (R)/ showed 0.065 nun, 0.607 nun, and 0.719 mm according to the file groups. Therefore there was a significant difference between E-plus film and Digora/sup (R)/(p<0.05). 2. By comparison of mean errors according to the various exposure times in the Digora/sup (R)/ system, the mean error at 0.01 seconds was significantly lower than that at 0.12 and 0.25 seconds in the No. 10 file group(p<0.05). And the standard deviation was the highest at 0.01 seconds. 3. Comparing E-plus film at 0.25 seconds with the Digora/sup (R)/ system, the mean errors showed a significant difference between E-plus film at 0.25 seconds and the Digora/sup (R)/ system at 0.25 seconds in No. 10 and 20 file groups(p<0.05). 4. Comparing E -plus film at 0.25 seconds with other exposure times, the mean errors showed a significant difference between E-plus film at 0.25 seconds and E-plus film at 0 .. 01 and 0.03 seconds in 10 file group(p<0.05). In the No. 15 and 20 file groups, there was a significant difference between E-plus film at 0.25 seconds and E-plus film at 0.01 seconds(p<0.05). In conclusion, Digora/sup (R)/ was better than E-plus film in detectability on the tip of the file at the exposure time of 0.01 seconds in all file groups. And we concluded that Digora/sup (R)/ can shorten exposure times up to 4％ of 0.25 seconds (0.01 sec), which is adequate exposure time for premolar in E-plus film using No. 15 and 20 files.

• Molecular & Cellular Toxicology
• /
• v.4 no.3
• /
• pp.211-217
• /
• 2008

To clarify the DNA damage from reactive oxygen species, we measured the DNA damage through Fpg/Endo III FLARE (Fragment Length Analysis with Repair Enzyme) assay and real time RT-PCR. The 80 SD rats assigned to 4 dose groups exposed to cumene vapor for 90 days. With Fpg/Endo III FLARE assay in hepatocytes, we found the OTM (Olive Tail Moment) and TL (Tail Length) significantly increased in no-enzyme treated and Fpg-treated control and 8 ppm groups with 28 days exposure. In Endo III-treated 8 ppm group, significantly increased the values with 90 days exposure. With lymphocytes, it was founded the values significantly increased in no-enzyme treated 800 ppm group in 28 and 90 days. It was significantly increased in Endo III-treated 80 ppm for 28 days and 800 ppm for 90 days. From the above findings, FLARE assay was suggested as being available as a biological marker for DNA damage induced by cumene exposure in SD rats. And we used real time RT-PCR for the OGG1 mRNA expression, it had dose-dependent biologic effects in 1 day exposure, but decrease the levels of rOGG1 mRNA. Our findings provide evidence that cumene exposure may cause suppression of rOGG1 in the rat hepatocytes or lymphocytes.

• Fisheries and Aquatic Sciences
• /
• v.20 no.3
• /
• pp.4.1-4.6
• /
• 2017

Juvenile Anoplopoma fimbria (mean length $16.8{\pm}2.2cm$, and mean weight $72.8{\pm}5.4g$) were exposed for 2 months with different levels of ammonia (0, 0.25, 0.50, 0.75, 1.00, and 1.25 mg/L). Growth performances such as daily length gain, daily weight gain, condition factor, and hepatosomatic index were significantly decreased by ammonia exposure. Hematological parameters such as red blood cell (RBC) count, hematocrit, and hemoglobin were also significantly decreased. In plasma inorganic components, calcium and magnesium were significantly decreased by ammonia exposure. In plasma organic components, there was no alteration in cholesterol and total protein. In enzyme plasma components, glutamic oxalate transaminase (GOT) and glutamic pyruvate transaminase (GPT) were significantly increased. The results of this study indicated that ammonia exposure can induce significant growth reduction and blood biochemistry alterations of A. fimbria.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.7 no.2
• /
• pp.1-11
• /
• 2004

The purpose of this study was to determine usability as potted flowers and garden plants by controlled plant height using growth retardants. There was no significant difference on the dwarfing effect according to the degree of exposure the sun, but growth was well under full exposure to the sun. The plant height was decreased by application of Cycocel (CCC), Bonzi (paclobutrzol), Ancymidol, and Uniconazole compared to the control group, and treatment of Bonzi $5mg{\cdot}L^{-1}$ was most dwarfing effect for both full sun exposure or 70% controlled shading condition. No consistent different was found in stem diameter, leaf color change, the content of chlorophyll and anthocyanin when the concentration of plant growth retardants was altered. These factors were affected only by light intensity. In comparison to the results of the control group, leaf length, leaf width, plant width and petiole length were all reduced by the application of growth retardants.

• Journal of the Korean Ceramic Society
• /
• v.27 no.8
• /
• pp.1043-1049
• /
• 1990

In this work, strength of ceramic fibers and monofilament composites were evaluated on the basis of Weibull's theory. The fibers used were β-SiC and γ-Al2O3 monofilament composites was fabricated by coating Al on the fiber surface by the use of vacuum evaporation method. Average tensile strength of ceramic fibers showed the tendency to linearly decrease with increasing gauge length. Also, Weibull moduli of ceramic fibers were decreased with increasing gauge length, Weibull modulus of β-SiC was 3.5 for 6-50mm, 2.8 for 100-200mm. Weibull modulus of γ-Al2O3 was 6.5 for 20-50mm, 6 for 100mm. Fibers in monofilament retained their original as-produced strength to exposure temperature of 400℃. However, tensile strength of both monofilament composites approved to remarkably degrade due to interfacial reaction-induced flaws on the fiber surface after thermal exposure of 600℃. In this case, Weibull modulus of monofilament composites was 2.7 for β-SiC and 5.2 for γ-Al2O3 respectively.