• Microbiology and Biotechnology Letters
• /
• v.11 no.3
• /
• pp.155-161
• /
• 1983

The effects of ultraviolet light on bacteriophage f2 were investigated to determine the inactivation kinetics and its mechanism. The 260nm light showed a little higher inactivation rate than the one of 300 nm. In this work, our main concern was whether structural and/or conformational changes in the protein capsid could occur by UV irradiation. The inactivation for the first 20 minutes irradiation was rapid with a loss of about 4 logs and followed by a slower rate during the next 40 minutes with no survival noted in the samples irradiated for 90 minutes or longer. The structural change of the protein capsid was examined by optical spectroscopic techniques and electron microscopy. The absorption spectra of the UV irradiated phages showed no detectable differences in terms of the spectral shape and intensity from the control phage. However, the fluorescence emission spectroscopic data, i.e. 1) fluorescence quenching of tryptophan residues upon irradiation of 300 nm light, 2) enhancement of fluorescence emission of ANS (8-aniline-1-naphthalene sulfonate) bound to the intact phages compared to the one in the UV-treated phages, and 3) decrease of energy transfer efficiency from tryptophan to ANS in the UV-treated samples, presented remarkable differences between the intact and UV-treated phages. Such a structural alteration was also observed by electron microscopy The UV-treated phages appeared to be broken and empty capsids. Therefore, the inactivation of the bacteriophage f2 by UV irradiation is thought to be attributed to the structural change in the protein capsid as well as damage in the viral RNA by UV irradiation.

• Asian-Australasian Journal of Animal Sciences
• /
• v.33 no.1
• /
• pp.79-90
• /
• 2020

Objective: In the present study, an liquid chromatography/mass spectrometry (LC/MS) metabolomics approach was performed to investigate potential biomarkers of milk production in high- and low-milk-yield dairy cows and to establish correlations among rumen fluid metabolites. Methods: Sixteen lactating dairy cows with similar parity and days in milk were divided into high-yield (HY) and low-yield (LY) groups based on milk yield. On day 21, rumen fluid metabolites were quantified applying LC/MS. Results: The principal component analysis and orthogonal correction partial least squares discriminant analysis showed significantly separated clusters of the ruminal metabolite profiles of HY and LY groups. Compared with HY group, a total of 24 ruminal metabolites were significantly greater in LY group, such as 3-hydroxyanthranilic acid, carboxylic acids, carboxylic acid derivatives (L-isoleucine, L-valine, L-tyrosine, etc.), diazines (uracil, thymine, cytosine), and palmitic acid, while the concentrations of 30 metabolites were dramatically decreased in LY group compared to HY group, included gentisic acid, caprylic acid, and myristic acid. The metabolite enrichment analysis indicated that protein digestion and absorption, ABC transporters and unsaturated fatty acid biosynthesis were significantly different between the two groups. Correlation analysis between the ruminal microbiome and metabolites revealed that certain typical metabolites were exceedingly associated with definite ruminal bacteria; Firmicutes, Actinobacteria, and Synergistetes phyla were highly correlated with most metabolites. Conclusion: These findings revealed that the ruminal metabolite profiles were significantly different between HY and LY groups, and these results may provide novel insights to evaluate biomarkers for a better feed digestion and may reveal the potential mechanism underlying the difference in milk yield in dairy cows.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2014.02a
• /
• pp.289.1-289.1
• /
• 2014

In this study, we made a organic thin film device in MIS(Metal-Insulator-Semiconductor) structure by using PVP (Poly vinyl phenol) as a insulating layer, and CdSe/ZnS nano particles which have a core/shell structure inside. We dissolved PVP and PMF in PGMEA, organic solvent, then formed a thin film through a spin coating. After that, it was cross-linked by annealing for 1 hour in a vacuum oven at $185^{\circ}C$. We operated FTIR measurement to check this, and discovered the amount of absorption reduced in the wave-length region near 3400 cm-1, so could observe decrease of -OH. Boonton7200 was used to measure a C-V relationship to confirm a properties of the nano particles, and as a result, the width of the memory window increased when device including nano particles. Additionally, we used HP4145B in order to make sure the electrical characteristics of the organic thin film device and analyzed a conduction mechanism of the device by measuring I-V relationship. When the voltage was low, FNT occurred chiefly, but as the voltage increased, Schottky Emission occurred mainly. We synthesized CdSe/ZnS and to confirm this, took a picture of Si substrate including nano particles with SEM. Spherical quantum dots were properly made. Due to this study, we realized there is high possibility of application of next generation memory device using organic thin film device and nano particles, and we expect more researches about this issue would be done.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 2010.05a
• /
• pp.35.1-35.1
• /
• 2010

The Cu(In,Ga)Se2(CIGS) thin film solar cells have been achieved until almost 20% efficiency by NREL. These solar cells include chemically deposited CdS as buffer layer between CIGS absorber layer and ZnO window layer. Although CIGS solar cells with CdS buffer layer show excellent performance, many groups made hard efforts to overcome its disadvantages in terms of high absorption of short wavelength, Cd hazardous element. Among Cd-free candidate materials, the CIGS thin film solar cells with Zn compound buffer layer seem to be promising with 15.2%(module by showa shell K.K.), 18.6%(small area by NREL). However, few groups were successful to report high-efficiency CIGS solar cells with Zn compound buffer layer, compared to be known how to fabricate these solar cells. Each group's chemical bah deposition (CBD) condition is seriously different. It may mean that it is not fully understood to grow high quality Zn compound thin film on the CIGS using CBD. In this study, we focused to clarify growth mechanism of chemically deposited Zn compound thin film on the CIGS, especially. Additionally, we tried to characterize junction properties with unfavorable issues, that is, slow growth rate, imperfect film coverage and minimize these issues. Early works reported that film deposition rate increased with reagent concentration and film covered whole rough CIGS surface. But they did not mention well how film growth of zinc compound evolves homogeneously or heterogeneously and what kinds of defects exist within film that can cause low solar performance. We observed sufficient correlation between growth quality and concentration of NH3 as complex agent. When NH3 concentration increased, thickness of zinc compound increased with dominant heterogeneous growth for high quality film. But the large amounts of NH3 in the solution made many particles of zinc hydroxide due to hydroxide ions. The zinc hydroxides bonded weakly to the CIGS surface have been removed at rinsing after CBD.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.5
• /
• pp.861-868
• /
• 2017

Near band infrared imaging technique has adopted for imaging EL2 and shallow level distributions in undoped semi-insulating LEC GaAs. This technique, which relies on the mapping of near bandgap infrared transmission, is both rapid and non-destructive. Until now no quantitative analysis has been reported for near band edge region which gives the reverse contrast on EL2 absorption images. This paper presents the spectral, spatial and temperature dependence of photoquenching forward and inverse mechanism in the band edge domain for cells and walls and for direct and inverted contrast conditions during transitory regimes. The difference in the threshold for the EL2w and EL2b defects could be attributed to the contribution of a different electrical assistance due to a different species of impurities. Quantitative analysis results show an increased density of EL2w and a small reduction of EL2b in the region of the walls where there is a high density of dislocations.

• Ocean and Polar Research
• /
• v.39 no.2
• /
• pp.149-158
• /
• 2017

The opsin family of light sensitive proteins family makes up are the universal photoreceptor molecules of all visual systems in the vertebrates including teleosts. They can change their conformation from a resting state to a signaling state upon light absorption, which activates the G-protein coupled receptor, thereby resulting in a signaling cascade that produces physiological responses. However, this species is poorly characterized at molecular level due to little sequence information available in public databases. We have investigated the opsin family of nocturnal cutlass fish using the whole transcriptome sequencing method. The opsin genes were cloned and its expression in the tissues and organs were examined by qPCR. We cloned 6 opsin genes (RRH, Opn4, Rh1, Rh2, VA-opsin, and Opn3) in retina and brain tissue. It contained the seven presumed transmembrane domains that are characteristic of the G-protein-coupled receptor family. However, short wavelength sensitive pigment (SWS) and long wavelength sensitive pigment (LWS) were not detected in this study. The mRNA expression of the 6 photoreceptor genes were detected in retina and peripheral tissue. Our studies will lead to further investigation of the photic entrainment mechanism at molecular and cellular levels in cutlass fish and can be used in comparative studies of other fishes.

• Toxicological Research
• /
• v.31 no.2
• /
• pp.97-104
• /
• 2015

The skin exposure to solar irradiation and photoreactive xenobiotics may produce abnormal skin reaction, phototoxicity. Phototoxicity is an acute light-induced response, which occurs when photoreacive chemicals are activated by solar lights and transformed into products cytotoxic against the skin cells. Multifarious symptoms of phototoxicity are identified, skin irritation, erythema, pruritis, and edema that are similar to those of the exaggerated sunburn. Diverse organic chemicals, especially drugs, are known to induce phototoxicity, which is probably from the common possession of UV-absorbing benzene or heterocyclic rings in their molecular structures. Both UVB (290~320 nm) and UVA (320~400 nm) are responsible for the manifestation of phototoxicity. Absorption of photons and absorbed energy (hv) by photoactive chemicals results in molecular changes or generates reactive oxygen species and depending on the way how endogenous molecules are affected by phototoxicants, mechanisms of phototoxcity is categorized into two modes of action: Direct when unstable species from excited state directly react with the endogenous molecules, and indirect when endogeneous molecules react with secondary photoproducts. In order to identify phototoxic potential of a chemical, various test methods have been introduced. Focus is given to animal alternative test methods, i.e., in vitro, and in chemico assays as well as in vivo. 3T3 neutral red uptake assay, erythrocyte photohemolysis test, and phototoxicity test using human 3-dimensional (3D) epidermis model are examples of in vitro assays. In chemico methods evaluate the generation of reactive oxygen species or DNA strand break activity employing plasmid for chemicals, or drugs with phototoxic potential.

• Journal of the Korean Wood Science and Technology
• /
• v.29 no.3
• /
• pp.36-46
• /
• 2001

This study was to find a way of reusing wood and plastic wastes, which considered as a troublesome problem to be solved in this age of mass production and consumption, in manufacturing wood fiber-polypropylene fiber composite panel. And the feasibility of this composite panel as a substitute for existing headliner base panel of automobile was also discussed, especially based on physical and mechanical performance. Nonwoven web composite panels were made from wood fiber and polypropylene fiber formulations of 50 : 50, 60 : 40, and 70 : 30, based on oven-dry weight, with densities of 0.4, 0.5, 0.6, and 0.7 g/$cm^3$. At the same density levels, control fiberboards were also manufactured for performance comparison with the composite panels. Their physical and mechanical properties were tested according to ASTM D 1037-93. To elucidate thickness swelling mechanism of composite panel through the observation of morphological change of internal structures, the specimens before and after thickness swelling test by 24-hour immersion in water were used in scanning electron microscopy. Test results in this study showed that nonwoven web composite panel from wood fibers and polypropylene fibers had superior physical and mechanical properties to control fiberboard. In the physical properties of composite panel, dimensional stability improved as the content of polypropylene fiber increased, and the formulation of wood fiber and polypropylene fiber was considered to be a significant factor in the physical properties. Water absorption decreased but thickness swelling slightly increased with the increase of panel density. In the mechanical properties of composite panel, the bending modulus of rupture (MOR) and modulus of elasticity (MOE) appeared to improve with the increase of panel density under all the tested conditions of dry, heated, and wet. The formulation of wood fiber and polypropylene fiber was considered not to be a significant factor in the mechanical properties. All the bending MOR values under the dry, heated, and wet conditions met the requirements in the existing headliner base panel of resin felt.

• Korean Journal of Materials Research
• /
• v.9 no.9
• /
• pp.913-918
• /
• 1999

As an alternative evaluation method of electromagnetic shielding properties, the material parameters are considered in determining the qualitative value of shielding effectiveness. The specimens are metallized nylon fabrics with the thickness of about 0.1 mm and the electrical conductivities in the range from 6.4$\times$10~2.4$\times$10(sup)5 mhos/m. On the basis of shielding theory, the shielding effectiveness (which is a sum of reflection loss and absorption loss) has been determined from the material parameters of the barrier sheets. For the conductive fabrics, the dominant shield mechanism is predicted to be reflection loss, which shows an increasing function of electrical conductivity. Comparing these theoretical value with the directly measured surface impedances, the error range is found to be within 10 dB, which demonstrates that the proposed material-parameters method can be a convenient way to determine the electromagnetic shielding properties.

• Korean Journal of Environmental Agriculture
• /
• v.11 no.2
• /
• pp.101-108
• /
• 1992

In order to illustrate adsorption phenomena of herbicides(alachlor and paraquat) on soils, absorption equation of herbicides and the relationships between soil properties and adsorption constants were investigated with 22 soils. The results were as follows : 1. The shaking time for approaching equillibrium reaction of herbicides(alachlor and paraquat) with woils were about 30 minutes for paraquat and 4 hours for alachlor, respectively. 2. The distribution coefficients of alachlor were inbetween 0.81-33.83 in 5 ppm and 0.09-15.52 in 50 ppm, respectively. 3. The adsorption of alachlor was positively correlated with organic matter and paraquat was with clay content of soils. 4. Both paraquat and alachlor were highly adsorbed in Chunpo series soil containing low contents of organic matter and clay on account of different mechanism from other soils, 5. Freundlich's adsorption constant(K) was greater than distribution coefficient(Kd), and the differences between K and Kd's were to be increased with increasing equillibrium concentrations.